UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

	PC Code:  000325

DP Barcodes:  357063

MEMORANDUM	Date:  January 28, 2010

SUBJECT:	Metrafenone:  Ecological Risk Assessment For Proposed Use on
Grapes

FROM:	Tanja Crk, M.A., Biologist

		James A. Hetrick, Ph.D., Senior Scientist

		Dana Spatz, Branch Chief

Environmental Risk Branch III

		Environmental Fate and Effects Division (7507P)

		Office of Pesticide Programs		

		

TO:		Mary Waller, Product Manager

Fungicide Branch

		Registration Division (7505P) 

		Office of Pesticide Programs

This memorandum transmits the Environmental Fate and Effects
Division’s (EFED) environmental risk assessment for the active
ingredient, metrafenone, as a fungicide for uses on grapes to treat
powdery mildew; it is used for preventive but not curative measures. 
The proposed end-use product Metrafenone 300 is a suspension concentrate
containing 25.2% metrafenone.  Ground (liquid) application is the
proposed method of application. The maximum single application rate is
0.300 lbs a.i./A; at 6 applications per season, the seasonal maximum
rate is 1.80 lbs a.i./A. The minimum application interval is 14 days.

While metrafenone is expected to be slightly mobile, its major routes of
degradation are aqueous photolysis and aquatic metabolism, in both
aerobic and anaerobic conditions.  Soil metabolism is slow, with
laboratory half-lives of 6 months to a year and accumulation over two
years observed in field studies.  In aquatic environments, the measured
photolysis half-life was 6.4 days and metabolism in both aerobic and
anaerobic occurred with half-lives of one to four weeks. Exposure is
expected to be dominated by runoff and spray drift. Metrafenone exposure
may also result from off-site movement in runoff water and on
metrafenone -bearing soil particulates to adjacent fields (soil
erosion). The moderate Koc’s (Koc 1073 to 22517 L/kg-oc) of
metrafenone suggest that leaching to ground water/recharge to surface
water would not be a route of exposure. Long-range transport of
metrafenone in the gas phase is not considered a significant route of
exposure. While the high log Kow (4.3 at 25oC, pH 4) would suggest the
potential for bioaccumulation, the lipid normalized BCF (between 140 and
530) indicates that metrafenone is not expected to accumulate in tissues
of aquatic organisms.

The results of this screening-level assessment indicate a potential for
direct adverse effects to non-target mammals (dose-based RQs 1.14-2.91)
following chronic exposure; these RQs also exceed the federally listed
species LOC. Due to the potential for direct adverse effects to mammals
associated with the application of metrafenone on grapes, indirect
effects may consequently affect other aquatic and terrestrial species.
To reduce chronic risk to mammals, several components of the application
protocol would have to change. For example, in order to have no chronic
LOC exceedances (i.e., all RQs < 1) for mammals, the minimum single
application rate (0.2 lbs a.i./A) would have to be cut by 25% (i.e., to
0.15 lbs a.i./A) yet considered the maximum instead, the application
interval would have to nearly double (from 14 days up to 26 days), and
the maximum allowed number of applications would have to be cut from 6
to 5. Alternatively, in order to have no chronic LOC exceedances for
mammals, the minimum single application rate (0.2 lbs a.i./A) can still
be applied yet considered the maximum instead, but the application
interval would have to nearly double (from 14 days up to 26 days), and
the maximum number of applications would have to be cut by 50% (i.e.,
from 6 to 3). Furthermore, in order to have no chronic LOC exceedances
in nearly all cases for mammals –the one exception being an exceedance
for the 15g size glass consuming short grass where the calculated RQ is
1.02 – the minimum single application rate (0.2 lbs a.i./A) would be
changed to the maximum single application rate and the application
interval (14 days) could remain as currently prescribed by the label,
but the maximum number of applications would have to be reduced from 6
to 2.

Data were either not submitted or were deemed invalid for freshwater
invertebrates and marine/estuarine fish via chronic exposure. Without
data, risk cannot be ruled out for these taxa (either non-listed or
federally listed species). 

Non-definitive endpoints – in this case, where total concentrations
were estimated instead of the preferred dissolved concentrations in the
majority of aquatic studies on metrafenone – suggest potential chronic
risk to federally listed freshwater fish and acute risk to federally
listed marine/estuarine invertebrates. More detailed risk conclusions
are provided in the environmental risk assessment document.

Data Needs

The ecotoxicity and environmental fate data needs are summarized in
Tables 1 and 2 below.  Further explanation and characterization of these
data needs can be found in the executive summary of the ecological risk
assessment.

Table 1. Ecological Toxicity Data Gaps

Study	Reason

850.1075 Acute toxicity freshwater fish	Non-definitive endpoint
w/effects observed

850.1400 Freshwater fish early-life stage (chronic)	Non-definitive
endpoint w/effects observed

850.1300 Aquatic freshwater invertebrate life-cycle (chronic)	Invalid,
CFR data gap

850.1025 Acute marine/estuarine invertebrate (oyster)

     Or

850.1035 Acute marine/estuarine invertebrate (mysid)	Non-definitive
endpoint w/effects observed

OECD 218 Freshwater invertebrate whole sediment study (chronic)	Invalid,
CFR data gap

850.4400 Aquatic vascular plant growth, Tier II	Non-definitive endpoint
w/effects observed

850.5400 Aquatic non-vascular plant growth, Tier II	Non-definitive
endpoint w/effects observed

850.2100 Avian acute oral toxicity test (passerine species)	Not
submitted, CFR data gap

850.3020 Honeybee acute contact toxicity (on TEP)	Address formulation
uncertainty

850.4100 Seedling Emergence, Tier II (on TEP)	Address formulation
uncertainty

850.4150 Vegetative Vigor, Tier II (on TEP)	Address formulation
uncertainty



Table 2.  Environmental Fate Data Gaps

835.6100 Independent Laboratory Validations



NEW CHEMICAL REGISTRATION

(Section 3)

      ECOLOGICAL RISK ASSESSMENT

Metrafenone: Fungicide

USEPA PC # 000325

 

Chemical Name(s):  
(3-bromo-6-methoxy-2-methylphenyl)(2,3,4-trimethoxy-6-methylphenyl)metha
none (CAS)

	3’-bromo-2,3,4,6’-tetramethoxy-2’,6-dimethylbenzophenone (IUPAC)

Chemical Abstracts Service (CAS) Number: 220899-03-6

Chemical Family:   Benzophenone fungicide

Pesticidal Mode of Action:  Inhibits growth of mycelium on the leaf
surface, leaf penetration, formation of haustoria, and sporulation.
Likely affects actin proteins which play a role in cell function and
cell division.

Proposed End-use Product:  Metrafenone 300 SC (EPA Reg.No.7969-xxx);

                                              Suspension Concentrate,
25.2% (2.5 lbs a.i./gallon)

Target Pest(s):   Powdery mildew produced by Uncinula necator

Proposed Target Crop(s):   Grapes

Risk Assessors:	Tanja Crk, MA, Biologist

			James A. Hetrick, PhD, Senior Scientist

Environmental Risk Branch III

			Environmental Fate and Effects Division

Secondary Reviewers:	Pamela Hurley, PhD, Toxicologist

Environmental Risk Branch III

			Environmental Fate and Effects Division

Through:		Dana Spatz, Branch Chief 

Environmental Risk Branch III

			Environmental Fate and Effects Division

Table of Contents

  TOC \o "1-5" \h \z \u    HYPERLINK \l "_Toc238026248"  I.	Executive
Summary	5   

  HYPERLINK \l "_Toc238026249"  A.	Nature of the Chemical Stressor	5   

  HYPERLINK \l "_Toc238026250"  B.	Potential Risks to Non-target
Organisms	5   

  HYPERLINK \l "_Toc238026251"  C.	Environmental Fate Summary	6   

  HYPERLINK \l "_Toc238026252"  D.	Ecological Effects Summary	7   

  HYPERLINK \l "_Toc238026253"  E.	Uncertainties and Data Gaps	8   

  HYPERLINK \l "_Toc238026254"  1.	Environmental Fate and Exposure	8   

  HYPERLINK \l "_Toc238026255"  2.	Ecological Effects Data	9   

  HYPERLINK \l "_Toc238026256"  F.	 Endangered Species Considerations	12
 

  HYPERLINK \l "_Toc238026257"  II.	Problem Formulation	13  

  HYPERLINK \l "_Toc238026258"  A.	Nature of Regulatory Action	13  

  HYPERLINK \l "_Toc238026259"  B.	Stressor Source and Distribution	13  

  HYPERLINK \l "_Toc238026260"  1. 	Nature of the Chemical Stressor	13  

  HYPERLINK \l "_Toc238026261"  a.	Mode of Action  (MoA) of Metrafenone
15 

  HYPERLINK \l "_Toc238026262"  b.	Reactions of  Metrafenone in the
Environment	15   PAGEREF _Toc238026262 \h  Error! Bookmark not defined. 


  HYPERLINK \l "_Toc238026263"  2.	Overview of Pesticide Usage	 15  

  HYPERLINK \l "_Toc238026264"  C.	Receptors	15  

  HYPERLINK \l "_Toc238026265"  1.	Aquatic and Terrestrial Effects	15  

  HYPERLINK \l "_Toc238026266"  2.	Ecosystems Potentially at Risk	17  

  HYPERLINK \l "_Toc238026267"  D.	Assessment Endpoints	17  

  HYPERLINK \l "_Toc238026268"  E.	Conceptual Model	17  

  HYPERLINK \l "_Toc238026269"  1.	Risk Hypothesis	17  

  HYPERLINK \l "_Toc238026270"  2.	Conceptual Diagram	18  

  HYPERLINK \l "_Toc238026271"  F.	Analysis Plan	 19  

  HYPERLINK \l "_Toc238026272"  1.	Conclusions from Previous Risk
Assessments	19  

  HYPERLINK \l "_Toc238026273"  2.	Preliminary Identification of Data
Gaps	19  

  HYPERLINK \l "_Toc238026274"  3.	Measures of Exposure and Effects	23  

  HYPERLINK \l "_Toc238026275"  a.	Aquatic Exposure Models	24  

  HYPERLINK \l "_Toc238026276"  b.	Terrestrial Exposure Models	24  

  HYPERLINK \l "_Toc238026277"  III.	Analysis	28  

  HYPERLINK \l "_Toc238026278"  A.	Use Characterization	28  

  HYPERLINK \l "_Toc238026279"  B.	Exposure Characterization	28  

  HYPERLINK \l "_Toc238026280"  1.	Environmental Fate and Transport	28  

  HYPERLINK \l "_Toc238026281"  2.	Measures of Aquatic Exposure	31  

  HYPERLINK \l "_Toc238026282"  a.	Aquatic Exposure Modeling	31   
HYPERLINK \l "_Toc238026283"   

  HYPERLINK \l "_Toc238026287"  b.	Aquatic Exposure Monitoring and Field
Data	  PAGEREF _Toc238026287 \h  34  

  HYPERLINK \l "_Toc238026288"  c.	Aquatic Bioaccumulation Assessment	 
PAGEREF _Toc238026288 \h  34  

  HYPERLINK \l "_Toc238026289"  3.	Measures of Terrestrial Exposure	36  

  HYPERLINK \l "_Toc238026290"  a.	Terrestrial Exposure Modeling	36   

  HYPERLINK \l "_Toc238026292"  C.	Ecological Effects Characterization
38  

  HYPERLINK \l "_Toc238026293"  1.	Aquatic Effects Characterization	38  

  HYPERLINK \l "_Toc238026294"  a.	Aquatic Animals	38  

  HYPERLINK \l "_Toc238026295"  (1)	 Acute Effects	38  

  HYPERLINK \l "_Toc238026296"  (2)	Chronic Effects	47   

  HYPERLINK \l "_Toc238026298"  b.	Aquatic Plants	49  

  HYPERLINK \l "_Toc238026299"  2.	Terrestrial Effects Characterization
55  

  HYPERLINK \l "_Toc238026300"  a.	Terrestrial Animals	55  

  HYPERLINK \l "_Toc238026301"  (1)	Acute Effects	55  

  HYPERLINK \l "_Toc238026302"  (2)	Chronic Effects	62   

  HYPERLINK \l "_Toc238026304"  b.	Terrestrial Plants	67  

  HYPERLINK \l "_Toc238026305"  IV.	Risk Characterization	68  

  HYPERLINK \l "_Toc238026306"  A.	Risk Estimation - Integration of
Exposure and Effects Data	 68  

  HYPERLINK \l "_Toc238026307"  1.	Risk to Aquatic Animals and Plants	68
 

  HYPERLINK \l "_Toc238026308"  a.	Aquatic Animals	68  

  HYPERLINK \l "_Toc238026309"  (1)	Risk Following Acute Exposure	68  

  HYPERLINK \l "_Toc238026310"  (2)	Risk Following Chronic Exposure	69  

  HYPERLINK \l "_Toc238026311"  b.	Aquatic Plants	70  

  HYPERLINK \l "_Toc238026312"  2.	Risk to Terrestrial Animals and
Plants	70  

  HYPERLINK \l "_Toc238026313"  a.	Terrestrial Animals	70  

  HYPERLINK \l "_Toc238026314"  (1)	Risk Following Acute Exposure	71  

  HYPERLINK \l "_Toc238026315"  (2)	Risk Following Chronic Exposure	72  

  HYPERLINK \l "_Toc238026316"  b.	Terrestrial Plants	75  

  HYPERLINK \l "_Toc238026317"  B.	Risk Description	75 

  HYPERLINK \l "_Toc238026318"  1.	Risk to Aquatic Animals and Plants	75
 

  HYPERLINK \l "_Toc238026319"  a.	Aquatic Animals	75  

  HYPERLINK \l "_Toc238026320"  (1)	Risk Following Acute Exposure	75  

  HYPERLINK \l "_Toc238026321"  (2)	Risk Following Chronic Exposure	78  

  HYPERLINK \l "_Toc238026322"  b.	Aquatic Plants	79  

  HYPERLINK \l "_Toc238026323"  2.	Risk to Terrestrial Animals and
Plants	80  

  HYPERLINK \l "_Toc238026324"  a.	Terrestrial Animals	80  

  HYPERLINK \l "_Toc238026325"  (1)	Risk Following Acute Exposure	80  

  HYPERLINK \l "_Toc238026326"  (2)	Risk Following Chronic Exposure	82  

  HYPERLINK \l "_Toc238026327"  b.	Terrestrial Plants	83  

  HYPERLINK \l "_Toc238026328"  3.	Review of Incident Data	84  

  HYPERLINK \l "_Toc238026329"  4.	Endocrine Effects	84  

  HYPERLINK \l "_Toc238026330"  5.	Federally Threatened and Endangered
(Listed) Species..	85  

  HYPERLINK \l "_Toc238026331"  a.	Action Area	86  

  HYPERLINK \l "_Toc238026332"  b.	Taxonomic Groups Potentially at Risk
86  

  HYPERLINK \l "_Toc238026333"  (1)	Discussion of Risk Quotients	89  

  HYPERLINK \l "_Toc238026334"  (2)	Probit Dose Response Relationship	89
 

  HYPERLINK \l "_Toc238026335"  (3)	Data Related to Under-represented
Taxa	90  

  HYPERLINK \l "_Toc238026336"  (4)	Implications of Sublethal Effects	90
 

  HYPERLINK \l "_Toc238026337"  c.	Indirect Effects Analysis	92  

  HYPERLINK \l "_Toc238026338"  d.	Critical Habitat	93  

  HYPERLINK \l "_Toc238026339"  e.	Co-occurrence Analysis	94  

  HYPERLINK \l "_Toc238026340"  C.	Description of Assumptions,
Limitations, Uncertainties, Strengths and Data Gaps
………………………………………………………………
…………………....95  

  HYPERLINK \l "_Toc238026341"  1.	Assumptions, Limitations, and
Uncertainties Related to Exposure For All
Taxa…………………………………………………………
………………………95  	a. Maximum Use 
Scenario……………………………………………………95  


  HYPERLINK \l "_Toc238026342"  2.	Assumptions, Limitations and
Uncertainties  Related to Exposure For Aquatic Species	95  

  HYPERLINK \l "_Toc238026343"  Environmental Fate
Studies……………………………………………...…95

Aquatic Exposure Model	95  

  HYPERLINK \l "_Toc238026344"  b.	Bioaccumulation Modeling	96  

  HYPERLINK \l "_Toc238026345"  3.	Assumptions, Limitations and
Uncertainties Related to Exposure for Terrestrial Species	96  

  HYPERLINK \l "_Toc238026346"  a.	Location of Wildlife Species	96  

  HYPERLINK \l "_Toc238026347"  b.	Routes of Exposure	96  

  HYPERLINK \l "_Toc238026348"  c.	Dietary Intake and Other Limitations
of Oral Studies in Terrestrial Species	96  

  HYPERLINK \l "_Toc238026349"  d.	Incidental Releases Associated With
Use	98  

  HYPERLINK \l "_Toc238026350"  e.	Residue Levels Selection	99  

  HYPERLINK \l "_Toc238026351"  f.	TerrPlant Model	99  

  HYPERLINK \l "_Toc238026352"  4.	Assumptions, Limitations and
Uncertainties Related to Effects Assessment	99  

  HYPERLINK \l "_Toc238026354"  a.	Sublethal Effects	99 

  HYPERLINK \l "_Toc238026355"  b.	Age Class and Sensitivity of Effects
Thresholds	99 

  HYPERLINK \l "_Toc238026356"  c.	Use of Most Sensitive Species Tested
100  

  HYPERLINK \l "_Toc238026357"  5.	Assumptions, Limitations,
Uncertainties, Strengths and Data Gaps Related to the Acute and Chronic
LOC’s	100  

  HYPERLINK \l "_Toc238026358"  V.	Literature Cited	101  

  HYPERLINK \l "_Toc238026359"  VI.	Appendices	 109

VII.   LIST OF
FIGURES………………………………………………………
…….109

VIII. LIST OF
TABLES…………………………………………………………
…...109

 

Executive Summary

Nature of the Chemical Stressor

Metrafenone
(3-bromo-6-methoxy-2-methylphenyl)(2,3,4-trimethoxy-6-methylphenyl)metha
none; CAS Reg. No. 220899-03-6) is a new pesticide active ingredient
submitted for registration in the United States. Metrafenone is a
benzophenone fungicide with resistance code U8 (unknown mode of action).
What is known is that the chemical inhibits growth of mycelium on the
leaf surface, leaf penetration, formation of haustoria, and sporulation
of the target fungus, Uncinula necator (EPA Pesticide Fact Sheet 2006).
Metrafenone likely affects actin proteins which play a role in cell
function and cell division (Opalski et al. 2006). It has a local
inhibition effect; in other words, it is not systemic and not a contact
killer. 

As a new pesticide active ingredient, the actual usage of metrafenone is
not known. The end-use product Metrafenone 300 SC is proposed for use on
grapes to treat powdery mildew; it is used for preventive but not
curative measures. Ground (liquid) application is the proposed method of
application. The maximum single application rate is 0.300 lbs a.i./A; at
6 applications per season, the seasonal maximum rate is 1.80 lbs a.i./A.
The minimum application interval is 14 days.

Potential Risks to Non-target Organisms

The results of this screening-level assessment indicate a potential for
direct adverse effects to non-target mammals (dose-based RQs 1.14-2.91)
following chronic exposure; these RQs also exceed the federally listed
species LOC. Due to the potential for direct adverse effects to mammals
associated with the application of metrafenone on grapes, indirect
effects may consequently affect other aquatic and terrestrial species.
Data were either not submitted or were deemed invalid for freshwater
invertebrates and marine/estuarine fish via chronic exposure. Without
data, risk cannot be ruled out for these taxa (either non-listed or
federally listed species). Non-definitive endpoints – in this case,
where total concentrations were estimated instead of the preferred
dissolved concentrations in the majority of aquatic studies on
metrafenone – suggest potential chronic risk to federally listed
freshwater fish and acute risk to federally listed marine/estuarine
invertebrates.  Comparison of the non-definitive endpoints with aquatic
EECs indicates potential risk to the given federally listed taxa (see
Section I.F below, Table 3) but not the non-listed taxa summarized in
Table 1 and Table 2. 

Table   SEQ Table \* ARABIC  1 .  Summary of Environmental Risk
Conclusions for Aquatic Animals and Plants from Metrafenone Use on
Grapes at the Maximum Proposed Application Rate (0.3 lb a.i./A, Assuming
6 Applications/Year)*

Taxonomic Group	Assessment Endpoint	

Summarized Risk Characterization and Important Uncertainties

Freshwater Fish and Aquatic Phase Amphibians	Mortality	Acute risk is not
expected (from technical grade active ingredient, metabolites, and EU/UK
formulation).

	Reproduction, growth etc.	Chronic risk is not expected.

Freshwater Invertebrates	Mortality	Acute risk is not expected (from
technical grade active ingredient, metabolites, and EU/UK formulation).

	Reproduction, growth etc.	No acceptable studies available. Chronic risk
cannot be precluded.

Marine/

Estuarine Fish	Mortality	Acute risk is not expected.

	Reproduction, growth etc.	No studies submitted. Chronic risk cannot be
precluded.

Marine/

Estuarine Invertebrates	Mortality	Acute risk is not expected.

	Reproduction, growth etc.	Chronic risk is not expected.

Aquatic Plants	Acute Risk	Risk to vascular species is not expected from
technical grade active ingredient. In addition, risk to non-vascular
species is not expected (from the technical grade active ingredient,
metabolites, and EU/UK formulation).

* Consult ‘Risk Description’ section for further details. Also, risk
in this table implies risk to technical grade active ingredient unless
otherwise specified that metabolites and formulations were assessed as
well. 



Table   SEQ Table \* ARABIC  2 .  Summary of Environmental Risk
Conclusions for Terrestrial Animals and Plants from Metrafenone Use on
Grapes at the Maximum Proposed Application Rate (0.3 lbs a.i./A,
Assuming 6 Applications/Year)*

Taxonomic Group	Risk Endpoint	

Summarized Risk Characterization and Important Uncertainties

Birds, Reptiles and Terrestrial Phase Amphibians	Mortality	Acute risk is
not expected. 

	Reproduction, growth etc.	Chronic risk is not expected.



Mammals	Mortality	Acute risk is not expected.

	Reproduction, growth etc.	Chronic risk is expected.

Non-target Invertebrates	

Acute Risk	Acute risk to honeybees is not expected. Acute risk to
earthworms (from the technical grade active ingredient, a metabolite,
and EU/UK formulation) is not expected.

Terrestrial Plants	Acute Risk	Risk to terrestrial plants is not expected
(from EU/UK formulation).

* Consult ‘Risk Description’ section for further details. Also, risk
in this table implies risk to technical grade active ingredient unless
otherwise specified that metabolites and formulations were assessed as
well.



Environmental Fate Summary

While metrafenone is expected to be slightly mobile, its major routes of
degradation are aqueous photolysis and aquatic metabolism, in both
aerobic and anaerobic conditions.  Soil metabolism is slow, with
laboratory half-lives of 6 months to a year and accumulation over two
years observed in field studies.  In aquatic environments, the measured
photolysis half-life was 6.4 days and metabolism in both aerobic and
anaerobic occurred with half-lives of one to four weeks.

Soil photolysis and anaerobic aquatic metabolism of metrafenone led to
one major degradate, CL 377160 [Methanone,
(3-bromo-6-methoxy-2-methylphenyl)(3-hydroxy-2,4-dimethoxy-6-methylpheny
l)-], and anaerobic aquatic metabolism also led to six other major
degradates, but all were either unidentified or only tentatively
identified.  In addition, there were many minor degradates, which were
formed at low levels individually but reached substantial amounts as
groups.  

μg/L for the daily peak, 8.82 μg/L for the 21 day average, and 6.21
μg/L for the 60 day average. The highest aquatic EECs for total
metrafenone residues were 20.22 μg/L for the daily peak, 17.67 μg/L
for the 21 day average, and 16.98 μg/L for the 60 day average.

No monitoring data are available to compare with model estimates. 
Bioaccumulation modeling was conducted because metrafenone has a log
octanol:water coefficient > 4.  Maximum residue concentrations in fish
are expected to range from 17,636 to 19,586 µg/kg-ww. 

Ecological Effects Summary

Aquatic Organisms

The greatest amount of uncertainty in the assessment stems from aquatic
studies which were largely based on total concentrations (both dissolved
and undissolved) of the test compound. In all cases (except for the
chronic study on the saltwater mysid, but including aquatic plants), the
risk quotient values were not calculated. However, given comparisons of
the total concentrations for most available studies and soluble
concentrations for the saltwater mysid (chronic) and sheesphead minnow
(acute) to respective EEC values the implication is that acute and
chronic risk (including sublethal effects) to aquatic organisms
(including aquatic plants) is not expected as a result of metrafenone
use on grapes. However, the taxa for which studies were either submitted
and deemed unacceptable (chronic freshwater invertebrate studies) or not
submitted at all (chronic marine/estuarine fish), the risk as a result
of metrafenone use cannot be precluded.

Terrestrial Organisms

The acute oral avian studies indicated no effects; the acute dietary
avian studies indicated a significant change in body weight that was not
associated with a dose-response pattern. In the acute mouse study on the
technical grade active ingredient, only one mortality was reported. 
Therefore, no implications with lethal or sublethal acute effects can be
made for either avian or mammalian taxa. Metrafenone is classified as
‘practically non-toxic’ to honeybees and non-lethal to earthworms up
to the limit concentration. Therefore, the implication is that acute
risk to terrestrial invertebrates is not expected as a result of
metrafenone use on grapes. In addition, no terrestrial plant risks are
expected as a result of use of the EU/UK formulation; however, no data
on terrestrial plants are available on the U.S. formulation.

 

The avian chronic toxicity endpoint (NOAEC 848 mg a.i./kg diet) based on
egg production and hatchability did not yield chronic LOC exceedances.
The most sensitive chronic mammalian endpoint (NOAEL 35.9 mg/kg bw/day)
based on decreased body weights and body weight gain in F1 males as well
as body weights in F1 and F2 females, however, exceeded the chronic LOC,
which implies that sublethal chronic effects on mammals are expected
under field conditions. Therefore, given the LOC exceedance chronic risk
to mammals is expected as a result of metrafenone use on grapes. 

Uncertainties and Data Gaps

Environmental Fate and Exposure

All but one of the environmental fate studies required to support the
registration of metrafenone for use on grapes were submitted. 
Independent Laboratory Validations for the methods submitted for
analysis of metrafenone in soil and water remain a data gap. These data
gaps fall under the terrestrial field dissipation study guideline
(835.6100). For a list of submitted environmental fate studies for
metrafenone see Appendix F.

All of the environmental fate studies for the parent compound were
determined to be scientifically valid and therefore results from all of
the studies can be used to characterize the mobility and rates of
transformation of metrafenone.  However, many of the metabolism studies
have major uncertainties in the identification and pattern of formation
and decline of transformation products.  In all of the aquatic
metabolism studies, between 57% and 65% of the applied radioactivity
remains unidentified with incomplete characterization, and in two
aerobic soil metabolism studies, 15% and 44% of the applied
radioactivity is unidentified.   This includes at least four major
degradates that individually reach levels of 11% to 35% of the applied. 
Other transformation products appear as groups of up to 15 components,
in some cases characterized as each being <5% of the applied
radioactivity, but in other cases, some individual components make up 9%
to 10% of the applied.  Even when individual components can all be
classified as minor degradates, these groups represent such a large
portion of the applied radioactivity overall that the possibility that
they may have some impact as a group cannot be precluded despite their
lower individual levels.  This is especially true given that the
degradation pathways suggest that groups of degradates may have a high
degree of structural similarity and so may have similar fate and effects
behavior.  Without information to adequately characterize the
degradates, it was necessary to assume that they are of equal toxicity
to the parent in order to quantify risks for metrafenone extractable
residues.

In addition to the studies submitted by the registrant, EFED was
provided with a Draft Assessment Report (DAR) on Metrafenone written by
the United Kingdom.  That assessment reports that the long dissipation
time observed in field studies triggered a requirement for longer term
field accumulation studies. Two years into those five year studies,
results show that metrafenone appears to be accumulating, and that
metrafenone residues have been detected as deep as 20-30 cm below the
surface. These studies would provide useful information regarding the
environmental fate of metrafenone and would assist in reducing
uncertainties. 

Ecological Effects Data

The submitted ecotoxicity database is incomplete. The greatest amount of
uncertainty in the assessment stems from aquatic studies which were
largely based on total (both dissolved and undissolved) concentrations
of test compound; that is, the concentrations were measured without
centrifugation even though precipitate was observed or test was
conducted at the solubility limit of the metrafenone technical grade
active ingredient; the solubility limits of the metabolites are unknown.
To reduce uncertainty the majority of the toxicity studies, which are
considered supplemental, and cannot be used in a quantitative risk
estimation would need to be redone; especially those where mortality or
sublethal effects were observed. These aquatic studies are specified
below. For a list of submitted ecological effects studies for
metrafenone see Appendix G.

The following studies are considered data needs:  

	Aquatic studies

Given the freshwater fish studies on metrafenone technical grade active
ingredient and assuming that the concentrations in the environment reach
the solubility limit, the effect of the compound is likely to be low.
However, according to model estimated EECs (which include metrafenone
and metrafenone residue scenarios: 0.00153 - 0.02 mg/L), levels of
metrafenone (TGAI, TEP) at the solubility limit (0.2-0.5 mg/L at 12oC)
and metrafenone metabolites at the tested concentrations are not
expected to occur in the environment given the proposed grape use.
Therefore, acute risk to freshwater fish and aquatic-phase amphibians is
not expected as a result of metrafenone use on grapes. In addition,
although the EU/UK formulation – with which the submitted studies were
conducted – closely matches the U.S. formulation (i.e., BAS 560 03F)
it is still not its equivalent. Therefore, the effect of the U.S.
formulated product on freshwater fish and aquatic-phase amphibians is
not known. 

To reduce uncertainty in characterizing risk, which is currently based
on total concentrations, the freshwater fish studies on bluegill sunfish
(Lepomis macrochirus) are requested to make same species comparisons for
acute and chronic values. Bluegill was chosen over the rainbow trout due
to greater sensitivity (on an acute basis) of the bluegill to the TGAI
relative to the trout. Since the acute marine/estuarine fish study is
acceptable and given the above two studies, the acute to chronic ratio
can be utilized to estimate marine/estuarine chronic endpoints, negating
the need to fill this data gap. Special emphasis must be placed on
centrifuging the test samples prior to analytical determination of the
test compound.

 Acute: Freshwater fish toxicity (96-hour LC50 for Lepomis macrochirus)
(850.1075; 72-1), TGAI

 Chronic: Fish early-life stage (freshwater: Lepomis macrochirus)
(850.1400; 72-4), TGAI

Although acute freshwater invertebrate studies were based on total
concentrations, no effects were observed with the TGAI, negating the
need to request additional data. However, a chronic freshwater
invertebrate data gap still exists since the two reviewed studies were
deemed invalid. 

Chronic: Aquatic invertebrate life cycle (freshwater: Daphnia magna)
(850.1300; 72-4), TGAI

Effects were observed in both acute marine/estuarine invertebrate
studies with the TGAI on the eastern oyster (Crassostrea viginica) and
saltwater mysid (Americamysis bahia) but the endpoints are based on
total concentrations. Therefore, should concentrations in the
environment reach the solubility limit, the acute risk to
marine/estuarine invertebrates may be expected. However, according to
the model estimated EECs (0.00153 - 0.02 mg/L, which includes
metrafenone and total metrafenone residue scenarios), levels of
metrafenone at the solubility limit are not expected to occur in the
environment given the proposed grape use. Given these studies and
assuming that metrafenone concentrations in the environment are not
likely to reach the solubility limit, the acute risk to marine/estuarine
invertebrates is not expected. However, to reduce uncertainty in
characterizing risk, either study is requested to be redone with special
emphasis on centrifuging the test samples prior to analytical
determination of the test compound.

Acute: Marine/estuarine invertebrate either Crassostrea virginica
(850.1025; 72-3) or Americamysis bahia (850.1035; 72-3), TGAI 

A non-guideline chronic midge study (Chironomus riparius) with
metrafenone technical (97.1%) was deemed invalid on the basis of low
negative control emergence. Therefore, a chronic freshwater invertebrate
whole sediment study is requested. A protocol should be submitted for
approval prior to study initiation. The protocol should include spiked
sediment. The whole sediment study is requested because metrafenone has
a high logKow value (4.3 at 25oC, pH 4) and a high aerobic soil half
life (> 4 months), which indicates that the compound may partition to
sediment and persist.

Chironomus dilutus (freshwater) using TGAI. Consult EPA Test Method
100.5 Life-cycle Test for Measuring the Effects of Sediment Associated
Contaminants on Chironomus dilutus (formerly Chironomus tentans) and
OECD Guideline 218 Sediment-Water Chironomid Toxicity Test Using Spiked
Sediment

Non-target aquatic plant studies were also based on total concentrations
leading to uncertainty in exposure concentrations and thus endpoint
values. Had valid endpoints (i.e., those based on dissolved
concentrations) been determined using these studies, they would likely
be greater than the highest model predicted concentration in the
environment, which implies that risk to vascular and non-vascular
species is not expected as a result of metrafenone use on grapes.
However, without centrifugation, the amount of chemical that is freely
dissolved and bioavailable cannot accurately be determined. Therefore,
vascular and non-vascular aquatic plant studies are requested with
special emphasis placed on centrifuging the test samples prior to
analytical determination of the test compound. In addition,
cyanobacteria yielded no effects given total concentrations and does not
need to be redone.

 

Aquatic vascular plant growth (Lemna spp.), Tier II (850.4400), TGAI

Aquatic non-vascular plant growth, Tier II (850.5400), TGAI

     Terrestrial Studies

An avian acute oral toxicity test in passerine species is required. 
Passerines are the most common birds (in terms of numbers and number of
species) in the United States.  Many utilize agricultural fields,
forests, residential areas and surrounding areas, and, therefore, have
the potential to be exposed to pesticides used in agricultural, forest,
and residential settings.  It is likely that, for the requested use
patterns, passerines are more likely to be exposed to metrafenone than
upland game species and waterfowl.  Passerines are smaller and have a
higher energy requirement than larger-sized birds.  As such, passerines
may be more sensitive than other birds. 

Passerine bird toxicity study (EPA approved protocol is required prior
to study initiation): Avian acute oral toxicity test (850.2100, 71-1),
TGAI

Formulated Product Testing

The available formulation product studies were conducted using three
different UK/EU formulated products (i.e., BAS 560 00F, BAS 560 01F, and
BAS 560 02F), one of which (BAS 560 00F) closely matches the U.S.
formulation (i.e., BAS 560 03F). Formulation studies in this assessment
are based on BAS 560 00F because data on the U.S. formulation were not
submitted. In order to eliminate uncertainty in effects characterization
of formulated products used within the U.S. on given taxa, future
registrant submitted studies should be based on the U.S. formulation. At
this time the effect of the U.S. formulation on given taxa is not known,
however, greater toxicity of the EU/UK formulation on the honeybee
relative to the TGAI was observed. Similarly, data submitted for
terrestrial plants is based on the EU/UK formulation. As a result, the
following studies are requested: 

Honeybee acute contact toxicity (850.3020, 141-1), TEP

Seedling emergence, Tier II (850.4225, 123-1), TEP

Vegetative vigor, Tier II (850.4250, 123-1), TEP

Endangered Species Considerations

Table 3 summarizes the listed species at risk associated with either
direct or indirect effects following application of metrafenone for the
proposed uses.

Concerns For Federally Listed as Endangered and/or Threatened Species

Table 3.  Listed Species Risks Associated With Direct or Indirect
Effects from Metrafenone use on Grapes at the Maximum Proposed
Application Rate (0.3 lbs a.i./A, Assuming 6 Applications/Year)  TC
"Table IB-1.  Listed species risks associated with direct or indirect
effects due to applications of propazine on sorghum" \f C \l "1"  

Listed Taxon	Direct Effects	Indirect Effects

Terrestrial and semi-aquatic plants - monocots	No	Yes from effects to
mammals

Terrestrial and semi-aquatic plants – dicots	No	Yes from effects to
mammals

Terrestrial invertebrates	No	Yes from effects to mammals

Birds	No	Yes from effects to mammals, FW fish, FW inverts, M/E fish, 
M/E inverts (mollusks)

Terrestrial-phase amphibians	No	Yes from effects to mammals

Reptiles	No	Yes from effects to mammals, FW fish, FW inverts, M/E fish, 
M/E inverts (mollusks)

Mammals	Yes for chronic1	Yes from effects to mammals, FW fish, FW
inverts, M/E fish,  M/E inverts (mollusks)

  Aquatic non-vascular plants	No	Yes from effects to mammals, FW fish,
FW inverts, M/E fish,  M/E inverts (mollusks)

Aquatic vascular plants	No	Yes from effects to mammals, FW fish, FW
inverts, M/E fish,  M/E inverts (mollusks)

Freshwater (FW) fish	Yes for chronic2	Yes from effects to mammals, FW
fish, FW inverts, M/E fish,  M/E inverts (mollusks)

Aquatic-phase amphibians	Yes for chronic3	Yes from effects to mammals,
FW fish, FW inverts, M/E fish,  M/E inverts (mollusks)

Freshwater (FW) invertebrates	Yes for chronic4	Yes from effects to
mammals, FW fish, FW inverts, M/E fish,  M/E inverts (mollusks)

Marine/estuarine (M/E) fish	Yes for chronic4	Yes from effects to
mammals, FW fish, FW inverts, M/E fish,  M/E inverts (mollusks)

Marine/estuarine (M/E) invertebrates (mollusk)	Yes for acute5, 

No for chronic6 	Yes from effects to mammals, FW fish, FW inverts, M/E
fish,  M/E inverts (mollusks)

1 The chronic LOC is exceeded on a dose basis for mammals in all size
classes eating short grass, for the 15 and 35 gram size classes eating
tall grass and broadleaf plants / small insects.  The chronic LOC on a
dietary basis is not exceeded for any of the food categories. 

2 The total concentration based endpoint (NOAEC: 0.118 mg total a.i./L)
for the chronic freshwater fish (fathead minnow) study (MRID 47267449)
with an effect on post-hatch survival is approximately 7x greater than
the highest estimated EEC (0.016 mg/L), hence risk to federally listed
freshwater fish cannot be precluded.

3 Results from freshwater fish used as surrogate for assessing risk to
aquatic-phase amphibians

4 Studies not submitted or invalid for which risk cannot be precluded.

5 Mollusk (Eastern oyster); 6 Saltwater mysid



Problem Formulation

The purpose of this problem formulation is to provide the foundation for
the ecological risk assessment being conducted for the fungicide
metrafenone. As such, it articulates the purpose and objectives of the
risk assessment, evaluates the nature of the problem, and provides a
plan for analyzing the data and characterizing the risk (EPA, 1998).  

Nature of Regulatory Action

Metrafenone is a new pesticide active ingredient being proposed as a
fungicide to control powdery mildew on grapes.  As a new active
ingredient submitted for registration, there are no previously prepared
ecological risk assessments by the Agency for metrafenone uses. However,
the European Commission has issued a Dossier for Metrafenone (DAR 2005).


Stressor Source and Distribution

The stressor is the metrafenone and its unidentified, extractable
degradation products when applied to grapes to control powdery mildew.
Therefore, metrafenone could potentially be used anywhere in the United
States where grapes are grown.

Nature of the Chemical Stressor

Figure 1 provides the chemical structure of metrafenone. Table 4
identifies the physical and chemical properties of metrafenone from
experimental data.

	

Figure 1. Chemical Structure of Metrafenone

 

Table 4. Environmental Fate Properties of Metrafenone

PARAMETER	VALUE(S) (units)	SOURCE	COMMENT

  Chemical Name
(3-Bromo-6-methoxy-2-methylphenyl)(2,3,4-trimethoxy-6-methylphenyl)-meth
anone	–	–

  Molecular Formula	C19H21BrO5.



  Molecular Weight	409	_	–

  Solubility (20 oC)	0.474 mg/L or ppm	MRID: 46415711	“Slightly
soluble” according to FAO Classification

  Vapor Pressure (20 oC)	1.15 x 10-6 mmHg	MRID: 46415713	–

  Henry’s Law constant	1.3 x 10-6 atm-m3/mole

Estimated from vapor pressure and water solubility.

  pKa (20 oC)	None	MRID: 46415714	–

Octanol-Water Partition Coefficient 

 (Log KOW,  at 25 oC, pH 4)	4.3	MRID: 46415715	–

  Hydrolysis Half-life 

  (pH 5, 7, 9; (50 oC))	Stable  	MRID: 47267422	Stable at all pHs.

  Aqueous Photolysis Half-life 

  (pH 5)	t1/2  = 6.4 days	MRID: 47267423	Value corrected to represent
natural sunlight at 40°N latitude; uncorrected lab half-life of 3.2
days (continuous irradiation; xenon lamp).

  Soil Photolysis Half-life	t1/2  = 31 days	MRID: 47267424	–

Aerobic Soil Metabolism 

Half-life	Silt loam:  	t1/2  = 178-277 d

Sandy loam:  	t1/2  = 277, 365 d

Clay loam: 	t1/2  = 299, 330 d

Loamy sand: 	t1/2  = 182 d

DT50 =  160 – 270 d	MRIDs: 

47267425

47267426

47267427	8 systems, 4 conducted with foreign soils.

In 2 studies metrafenone residues exceeded 50% at study termination (120
& 210 d)

  Anaerobic Aquatic Metabolism   

  Half-life	t1/2  = 21.6 d, 18.0 d

DT50 =  15 d, 3 d	MRIDs:

47267429

47267431	–

  Aerobic Aquatic Metabolism 

  Half-life	t1/2  = 27.3 d, 24.1 d

DT50 =  10 d, 11 d	MRID: 47267430	–

  Organic Carbon Partition

  Coefficient (KOC)	1073, 2230, 2331, 

22517, 2792 mL/gOC

	MRID: 47267420	“Slightly mobile” according to FAO Classification

  Soil Partition Coefficient (Kd)	15.1, 36.5, 40.1,

42.0, 86.5 mL/g	MRID: 47267420	--

Terrestrial Field Dissipation	t1/2  =144 d, 161 d, 210 d, 161 d

	MRID 47267432	Field studies were conducted in WA, ON,CA, FL

Bioaccumulation in Fish	BCF: 140 to 530	MRID 47267450	Lipid Normalized
BCF



Mode of Action (MoA) of Metrafenone

Metrafenone is a benzophenone fungicide. What is known is that the
chemical inhibits growth of mycelium on the leaf surface, leaf
penetration, formation of haustoria, and sporulation of the target
fungus, Uncinula necator (EPA Pesticide Fact Sheet 2006). Metrafenone
likely affects actin proteins which play a role in cell function and
cell division (Opalski et al. 2006).

Reactions of Metrafenone in the Environment

Metrafenone is expected to be slightly mobile.  Its major routes of
degradation are aqueous photolysis and aquatic metabolism, in both
aerobic and anaerobic conditions.  Soil metabolism is slow, with
laboratory half-lives of 6 months to a year and accumulation over two
years observed in field studies.  In aquatic environments, the measured
photolysis half-life was 6.4 days and metabolism in both aerobic and
anaerobic occurred with half-lives of one to four weeks.

Soil photolysis and anaerobic aquatic metabolism of metrafenone led to
one major degradate, CL 377160, and anaerobic aquatic metabolism also
led to six other major degradates, but all were either unidentified or
only tentatively identified.  In addition, there were many minor
degradates, which were formed at low levels individually but reached
substantial amounts as groups.  

Overview of Pesticide Usage

As a new pesticide active ingredient, the actual usage of metrafenone is
not known. The end-use product Metrafenone 300 SC is proposed for use on
grapes.

Ground application is the proposed method of application.  The label
states, “do not apply directly to water, to areas where surface water
is present, or to intertidal areas below the mean high water mark.” 
The chemical is to be applied at most 6 times per season at a maximum
application rate of 0.3 lbs a.i./A (Table 5). The label also states,
“do not make more than 2 sequential applications of Metrafenone 300 SC
fungicide before alternating to a labeled fungicide with a different
mode of action.”

Table 5.  Metrafenone use and application information based on the
proposed label for Metrafenone  300 SC

Use	Max. Single App. Rate 

(lbs a.i./A)	# of App. /

Season	Seasonal Max. Rate (lbs a.i./A)	Minimum App. Interval (days)

Grapes	0.300	6	1.80	14 days



Receptors

Aquatic and Terrestrial Effects

The receptor is the biological entity that is exposed to the stressor
(EPA, 1998). Based on the proposed uses for metrafenone, it is expected
that the aquatic and terrestrial receptors will include freshwater fish
and invertebrates, marine/estuarine fish and invertebrates, aquatic
plants, terrestrial plants, birds, mammals, and terrestrial
invertebrates.

Consistent with the process described in the Overview Document (EPA,
2004), this risk assessment uses a surrogate species approach in its
evaluation of metrafenone.  Toxicological data generated from surrogate
test species, which are intended to be representative of broad taxonomic
groups, are used to extrapolate to potential effects on a variety of
species (receptors) included under these taxonomic groupings.  

Acute and chronic toxicity data from studies submitted by pesticide
registrants are used to evaluate the potential direct effects of
metrafenone to the aquatic and terrestrial receptors identified in this
section.  This includes toxicity data on the technical grade active
ingredient, any major transformation products, and when available,
formulated products (e.g. “Six-Pack” studies).  

Table 6 provides a summary of the taxonomic groups and the surrogate
species tested to help understand potential acute ecological effects of
pesticides to these non-target taxonomic groups.  In addition, the table
provides a preliminary overview of the potential acute toxicity of
metrafenone by providing the acute toxicity classifications.

Table 6.  Test Species Evaluated for Assessing Potential Ecological
Effects of Metrafenone and the Associated Acute Toxicity Classification

Taxonomic Group	Surrogate Species	Acute Toxicity Classification

Birds1	  SEQ CHAPTER \h \r 1 Mallard Duck (Anas platyrhynchos)

Bobwhite Quail (Colinus virginianus)

Passerine species	Practically nontoxic

Practically nontoxic

No available study

  SEQ CHAPTER \h \r 1 Mammals

	  SEQ CHAPTER \h \r 1 Laboratory rat (Rattus norvegicus)

Laboratory mouse	Practically non-toxic

Practically non-toxic

  SEQ CHAPTER \h \r 1 Insects	  SEQ CHAPTER \h \r 1 Honey bee (Apis
mellifera L.)	Practically non-toxic

  SEQ CHAPTER \h \r 1 Freshwater fish2		  SEQ CHAPTER \h \r 1 Bluegill
sunfish (Lepomis macrochirus)

Rainbow trout (Oncorhynchus mykiss)	Highly toxic

Highly toxic

  SEQ CHAPTER \h \r 1 Freshwater invertebrates	  SEQ CHAPTER \h \r 1
Water flea (Daphnia magna)	At most, highly toxic

  SEQ CHAPTER \h \r 1 Marine/estuarine fish	  SEQ CHAPTER \h \r 1 
Sheepshead minnow (Cyprinodon variegatus)	Highly toxic

Marine/estuarine invertebrates	Mysid shrimp (Americamysis bahia)

Eastern oyster (Crassostrea virginica)	Highly toxic

Highly toxic

  SEQ CHAPTER \h \r 1 Terrestrial plants3	  SEQ CHAPTER \h \r 1 Monocots
– most sensitive species

Dicots – most sensitive species	No Classification

  SEQ CHAPTER \h \r 1 Aquatic plants and algae	  SEQ CHAPTER \h \r 1
Duckweed (Lemna gibba) 

Cyanobacteria/blue-green algae (Anabaena flos-aquae)

Marine diatom (Skeletonema costatum)

Freshwater diatom (Navicula pelliculosa)

Algae (Pseudokirchneriella subcapitata; previously known as Selenastrum
capricornutum)	No classification

  SEQ CHAPTER \h \r 1 1 Birds represent surrogates for terrestrial-phase
amphibians and reptiles.

2 Freshwater fish may be surrogates for aquatic-phase amphibians.

3 Normally four species of two families of monocots, of which one is
corn; six species of at least four dicot families, of which one is
soybeans.



Ecosystems Potentially at Risk

The ecosystems at risk are often extensive in scope, and as a result it
may not be possible to identify specific ecosystems during the
development of a baseline risk assessment.  However, in general terms,
terrestrial ecosystems potentially at risk could include the treated
field and areas immediately adjacent to the treated field that may
receive drift or runoff.  Areas adjacent to the treated field could
include cultivated fields, fencerows and hedgerows, meadows, fallow
fields or grasslands, woodlands, riparian habitats, and other
uncultivated areas.  

Aquatic ecosystems potentially at risk might include but are not
necessarily limited to water bodies adjacent to, or down stream from,
the treated field and might include impounded bodies such as ponds,
lakes and reservoirs, or flowing waterways such as streams or rivers.
For uses in coastal areas, aquatic habitat also includes marine
ecosystems, including estuaries.

Assessment Endpoints

Assessment endpoints represent the actual environmental value that is to
be protected, defined by an ecological entity (species, community, or
other entity) and its attribute or characteristics (EPA, 1998). 
Generally, the ecological entities may include the following: freshwater
as well as marine/estuarine fish and invertebrates, aquatic and
terrestrial plants, birds, reptiles, amphibians, mammals, and non-target
insects. For metrafenone: chronic risk to mammals is expected. The
attributes for each of these entities may include growth, reproduction,
and survival.  

Conceptual Model

A conceptual model provides a written description and visual
representation of the predicted relationships between metrafenone
residues, potential routes of exposure, and the predicted effects for
the assessment endpoint. A conceptual model consists of two major
components: risk hypothesis and a conceptual diagram (EPA, 1998).

Risk Hypothesis

For a pesticide to pose an ecological risk, it must reach ecological
non-target organisms (receptors) at biologically significant
concentrations. An exposure pathway is the means by which a pesticide
moves in the environment from the application site to non-target
organisms. The evaluation of the ecological exposure pathways in this
assessment includes an examination of the source and potential transport
pathways for metrafenone and the determination of exposure routes of
non-target species. 

Metrafenone, when used in accordance with the label, results in
potential direct adverse effects upon the growth and reproduction of
mammals.  As a result, given the persistence of metrafenone, there is
potential for indirect effects to terrestrial and/or aquatic organisms.

Conceptual Diagram

The conceptual model diagram is a generic graphic depiction of the risk
hypotheses identified in the previous section.  It is assumed that
metrafenone is capable of affecting exposed terrestrial and aquatic
organisms if environmental concentrations are sufficiently elevated as a
result of proposed label uses.  Through a preliminary process of
examining fate and effects data, the risk hypotheses and conceptual
model have been refined to reflect possible exposure pathways and the
organisms that are most relevant and applicable to this assessment
(Figure 2).  If exposed at sufficient levels, mortality may occur, as
well as sublethal effects.  Direct effects on a taxonomic group may
result in indirect effects (i.e., loss of habitat, food resources) to
other taxonomic groups.  This assessment will examine the potential for
these effects to occur within the surrogate taxa with the intent to
extrapolate to actual effects within the environment.

In order for a chemical to pose an ecological risk, it must reach
ecological receptors in biologically significant concentrations.  An
exposure pathway is the means by which a contaminant moves in the
environment from a source to an ecological receptor.  For this pathway
to be complete, it must have a source, a release mechanism, an
environmental transport medium for metrafenone and/or its transformation
products, a point of exposure for ecological receptors, and a feasible
route of exposure.  The assessment of these pathways thus includes an
examination of the sources and potential migration pathways for
constituents, and the determination of potential exposure routes.  

The conceptual model for both potential aquatic and terrestrial risk is
shown in Figure 2.  Exposure routes shown in dashed lines are not
quantitatively considered because the resulting exposures are expected
to be very low when compared to the major routes of exposure.

Exposure is expected to be dominated by runoff and spray drift.
Metrafenone exposure may also result from off-site movement in runoff
water and on metrafenone -bearing soil particulates to adjacent fields
(soil erosion). The moderate Koc’s (Koc 1073 to 22517 L/kg-oc) of
metrafenone suggest that leaching to ground water/recharge to surface
water would not be a route of exposure. Long-range transport of
metrafenone in the gas phase is not considered a significant route of
exposure.

This screening-level assessment for ground spray applications of
metrafenone only considered dietary exposure. Other routes of exposure
that were not considered in the assessment are incidental soil ingestion
exposure, inhalation exposure, dermal exposure, and drinking water
exposure.  These routes are not represented in the diagram (Figure 2).  

Figure 2.  Conceptual Model Depicting Sources of Exposure from
Metrafenone as well as Metrafenone Residues, Potential Receptors, and
Adverse Effects from the Proposed Uses of Metrafenone on Grapes.

 

Analysis Plan

The structure of this risk assessment is based on guidance contained in
U.S. EPA’s Guidance for Ecological Risk Assessment (U.S. EPA, 1998)
and is consistent with procedures and methodology outlined in the
Overview Document (U.S. EPA, 2004).

Conclusions from Previous Risk Assessments

There are no previous ecological risk assessments because this is the
first registration petition for metrafenone for use on grapes in the
United States.  

Preliminary Identification of Data Gaps

Review of the submitted studies indicated the following points:

Environmental Fate

All but one of the environmental fate studies required to support the
registration of metrafenone for use on grapes were submitted. 
Independent Laboratory Validations for the methods submitted for
analysis of metrafenone in soil and water remain a data gap. For a list
of submitted environmental fate studies for metrafenone see Appendix F.

All of the environmental fate studies for the parent compound were
determined to be scientifically valid and therefore results from all of
the studies can be used to characterize the mobility and rates of
transformation of metrafenone.  However, many of the metabolism studies
have major uncertainties in the identification and pattern of formation
and decline of transformation products.  In all of the aquatic
metabolism studies, between 57% and 65% of the applied radioactivity
remains unidentified with incomplete characterization, and in two
aerobic soil metabolism studies, 15% and 44% of the applied
radioactivity is unidentified.  This includes at least four major
degradates that individually reach levels of 11% to 35% of the applied. 
Other transformation products appear as groups of up to 15 components,
in some cases characterized as each being <5% of the applied
radioactivity, but in other cases, some individual components make up 9%
to 10% of the applied.  Even when individual components can all be
classified as minor degradates, these groups represent such a large
portion of the applied radioactivity overall that the possibility that
they may have some impact as a group cannot be precluded despite their
lower individual levels.  This is especially true given that the
degradation pathways suggest that groups of degradates may have a high
degree of structural similarity and so may have similar fate and effects
behavior.  Without information to adequately characterize the
degradates, it may be necessary to assume that they are of equal
toxicity to the parents in order to quantify risks.

In addition to the studies submitted by the registrant, EFED was
provided with a Draft Assessment Report (DAR) on Metrafenone written by
the United Kingdom.  That assessment reports that the long dissipation
time observed in field studies triggered a requirement for longer term
field accumulation studies. Two years into those five year studies,
results show that metrafenone appears to be accumulating, and that
metrafenone residues have been detected as deep as 20-30 cm below the
surface. These studies would provide useful information regarding the
environmental fate of metrafenone and would assist in reducing
uncertainties. 

Ecotoxicity

The submitted ecotoxicity database is incomplete. The greatest amount of
uncertainty in the assessment stems from aquatic studies which were
largely based on total (both dissolved and undissolved) concentrations
of test compound; that is, the concentrations were measured without
centrifugation even though precipitate was observed or test was
conducted at the solubility limit of the metrafenone technical grade
active ingredient; the solubility limits of the metabolites are unknown.
To reduce uncertainty the majority of the toxicity studies, which are
considered supplemental, and cannot be used in a quantitative risk
estimation would need to be redone; especially those where mortality or
sublethal effects were observed. These aquatic studies are specified
below. For a list of submitted ecological effects studies for
metrafenone see Appendix G.

The following studies are considered data needs:  

	Aquatic studies

Given the freshwater fish studies on metrafenone technical grade active
ingredient and assuming that the concentrations in the environment reach
the solubility limit, the effect of the compound is likely to be low.
However, according to model estimated EECs (which include metrafenone
and metrafenone residue scenarios: 0.00153 - 0.02 mg/L), levels of
metrafenone (TGAI, TEP) at the solubility limit (0.2-0.5 mg/L at 12oC)
and metrafenone metabolites at the tested concentrations are not
expected to occur in the environment given the proposed grape use.
Therefore, acute risk to freshwater fish and aquatic-phase amphibians is
not expected as a result of metrafenone use on grapes. In addition,
although the EU/UK formulation – with which the submitted studies were
conducted – closely matches the U.S. formulation (i.e., BAS 560 03F)
it is still not its equivalent. Therefore, the effect of the U.S.
formulated product on freshwater fish and aquatic-phase amphibians is
not known. 

To reduce uncertainty in characterizing risk, which is currently based
on total concentrations, the freshwater fish studies on bluegill sunfish
(Lepomis macrochirus) are requested to make same species comparisons for
acute and chronic values. Bluegill was chosen over the rainbow trout due
to greater sensitivity (on an acute basis) of the bluegill to the TGAI
relative to the trout. Since the acute marine/estuarine fish study is
acceptable and given the above two studies, the acute to chronic ratio
can be utilized to estimate marine/estuarine chronic endpoints, negating
the need to fill this data gap. Special emphasis must be placed on
centrifuging the test samples prior to analytical determination of the
test compound.

 Acute: Freshwater fish toxicity (96-hour LC50 for Lepomis macrochirus)
(850.1075; 72-1), TGAI

 Chronic: Fish early-life stage (freshwater: Lepomis macrochirus)
(850.1400; 72-4), TGAI

Although acute freshwater invertebrate studies were based on total
concentrations, no effects were observed with the TGAI, negating the
need to request additional data. However, a chronic freshwater
invertebrate data gap still exists since the two reviewed studies were
deemed invalid. 

Chronic: Aquatic invertebrate life cycle (freshwater: Daphnia magna)
(850.1300; 72-4), TGAI

Effects were observed in both acute marine/estuarine invertebrate
studies with the TGAI on the eastern oyster (Crassostrea viginica) and
saltwater mysid (Americamysis bahia) but the endpoints are based on
total concentrations. Therefore, should concentrations in the
environment reach the solubility limit, the acute risk to
marine/estuarine invertebrates may be expected. However, according to
the model estimated EECs (0.00153 - 0.02 mg/L, which includes
metrafenone and total metrafenone residue scenarios), levels of
metrafenone at the solubility limit are not expected to occur in the
environment given the proposed grape use. Given these studies and
assuming that metrafenone concentrations in the environment are not
likely to reach the solubility limit, the acute risk to marine/estuarine
invertebrates is not expected. However, to reduce uncertainty in
characterizing risk, either study is requested to be redone with special
emphasis on centrifuging the test samples prior to analytical
determination of the test compound.

Acute: Marine/estuarine invertebrate either Crassostrea virginica
(850.1025; 72-3) or Americamysis bahia (850.1035; 72-3), TGAI 

A non-guideline chronic midge study (Chironomus riparius) with
metrafenone technical (97.1%) was deemed invalid on the basis of low
negative control emergence. Therefore, a chronic freshwater invertebrate
whole sediment study is requested. A protocol should be submitted for
approval prior to study initiation. The protocol should include spiked
sediment. The whole sediment study is requested because metrafenone has
a high logKow value (4.3 at 25oC, pH 4) and a high aerobic soil half
life (> 4 months), which indicates that the compound may partition to
sediment and persist.

Chironomus dilutus (freshwater) using TGAI. Consult EPA Test Method
100.5 Life-cycle Test for Measuring the Effects of Sediment Associated
Contaminants on Chironomus dilutus (formerly Chironomus tentans) and
OECD Guideline 218 Sediment-Water Chironomid Toxicity Test Using Spiked
Sediment

Non-target aquatic plant studies were also based on total concentrations
leading to uncertainty in exposure concentrations and thus endpoint
values. Had valid endpoints (i.e., those based on dissolved
concentrations) been determined using these studies, they would likely
be greater than the highest model predicted concentration in the
environment, which implies that risk to vascular and non-vascular
species is not expected as a result of metrafenone use on grapes.
However, without centrifugation, the amount of chemical that is freely
dissolved and bioavailable cannot accurately be determined. Therefore,
vascular and non-vascular aquatic plant studies are requested with
special emphasis placed on centrifuging the test samples prior to
analytical determination of the test compound. In addition,
cyanobacteria yielded no effects given total concentrations and does not
need to be redone.

 

Aquatic vascular plant growth (Lemna spp.), Tier II (850.4400), TGAI

Aquatic non-vascular plant growth, Tier II (850.5400), TGAI

     Terrestrial Studies

An avian acute oral toxicity test in passerine species is required. 
Passerines are the most common birds (in terms of numbers and number of
species) in the United States.  Many utilize agricultural fields,
forests, residential areas and surrounding areas, and, therefore, have
the potential to be exposed to pesticides used in agricultural, forest,
and residential settings.  It is likely that, for the requested use
patterns, passerines are more likely to be exposed to metrafenone than
upland game species and waterfowl.  Passerines are smaller and have a
higher energy requirement than larger-sized birds.  As such, passerines
may be more sensitive than other birds. 

Passerine bird toxicity study (EPA approved protocol is required prior
to study initiation): Avian acute oral toxicity test (850.2100, 71-1),
TGAI

Formulated Product Testing

The available formulation product studies were conducted using three
different UK/EU formulated products (i.e., BAS 560 00F, BAS 560 01F, and
BAS 560 02F), one of which (BAS 560 00F) closely matches the U.S.
formulation (i.e., BAS 560 03F). Formulation studies in this assessment
are based on BAS 560 00F because data on the U.S. formulation were not
submitted. In order to eliminate uncertainty in effects characterization
of formulated products used within the U.S. on given taxa, future
registrant submitted studies should be based on the U.S. formulation. At
this time the effect of the U.S. formulation on given taxa is not known,
however, greater toxicity of the EU/UK formulation on the honeybee
relative to the TGAI was observed. Similarly, data submitted for
terrestrial plants is based on the EU/UK formulation. As a result, the
following studies are requested: 

Honeybee acute contact toxicity (850.3020, 141-1), TEP

Seedling emergence, Tier II (850.4225, 123-1), TEP

Vegetative vigor, Tier II (850.4250, 123-1), TEP

Measures of Exposure and Effects

EFED uses a tiered system of pesticide exposure modeling to assess
ecological risk following a registered application of that pesticide.
This tiered system is designed to minimize the amount of analysis which
is required to register any given chemical.  Each of the tiers is
designed to screen out pesticides by requiring higher, more complex
levels of investigation only for those that have not passed the next
lower tier.  Each tier screens out a percentage of pesticides from
having to undergo a more rigorous review prior to registration or
re-evaluation.

Aquatic Exposure Models

Tier II PRZM and EXAMS simulation models were used to estimate the
exposure concentrations of metrafenone in surface water for the proposed
use on grapes. The results are presented in Appendix B.

The data used as input parameters come solely from the environmental
fate studies and proposed product label submitted by the petitioner to
support in the United States the registration of metrafenone as a new
pesticide-active ingredient for grapes. 

KABAM (KOW (based) Aquatic BioAccumulation Model) v.1.0 is used to
estimate potential bioaccumulation of hydrophobic organic pesticides
such as metrafenone (log Kow > 4) in freshwater aquatic food webs and
subsequent risks to mammals and birds via consumption of contaminated
aquatic prey. The bioaccumulation portion of KABAM is based upon work by
Arnot and Gobas (2004) who parameterized a bioaccumulation model based
on PCBs and some pesticides (e.g., lindane, DDT) in freshwater aquatic
ecosystems. KABAM relies on a chemical's octanol-water partition
coefficient (KOW) to estimate uptake and elimination constants through
respiration and diet of organisms in different trophic levels. Pesticide
tissue residues are calculated for different levels of an aquatic food
web. The model then uses pesticide tissue concentrations in aquatic
animals to estimate dose- and dietary-based exposures and associated
risks to mammals and birds consuming aquatic organisms, using an
approach that is similar to the T-REX model (USEPA 2008). 

 

KABAM incorporates 7 trophic levels to describe bioaccumulation of a
pesticide in a model aquatic food web: phytoplankton, zooplankton (e.g.,
Daphnia sp.), benthic invertebrates (e.g., Chironomus sp., crayfish),
filter feeders (e.g., mussels, clams), small fish (e.g., young of the
year), medium sized fish (e.g., adult bluegill), and larger
upper-trophic level fish (e.g., largemouth bass).

 

Metrafenone concentrations in organisms of the aquatic trophic levels
listed above were used to estimate acute and chronic exposures of
piscivorous mammals and birds consuming fish. Applicable and available
acute and chronic toxicity data on metrafenone (mammals and birds) were
used to calculate risk quotients for estimated exposures due to
bioaccumulation of metrafenone in an aquatic ecosystem.  

Terrestrial Exposure Models

T-REX Model

The focus of terrestrial wildlife exposure estimates is for birds (also
acting as surrogate for reptiles and terrestrial-phase amphibians) and
mammals with an exposure route emphasis on uptake through the diet.  The
residues in or on potential dietary sources for mammals and birds (e.g.,
vegetation, insects, and seeds) were estimated using the Tier I model
T-REX (Version 1.4.1, 2008).  In this Tier I assessment, it was assumed
that organisms are exposed to one active ingredient in a given exposure
scenario.  In all screening-level assessments, the organisms are assumed
to consume 100% of their diet as one food type and one food source.  The
T-REX output is presented in the Risk Characterization section of this
document as well as an example in Appendix C.  

The approach used to estimate exposure of terrestrial animals to
metrafenone was based on potential foliar applications of metrafenone.
Upper-bound exposure levels were calculated for spray applications of
metrafenone using maximum proposed application rates for one application
for the proposed uses. The exposure estimates are based on a database of
pesticide residues on wildlife food sources associated with specified
application rates (Kenaga, 1972; Fletcher et al., 1994). Essentially,
for a single application, there is a linear relationship between the
amount of pesticide applied and the amount of pesticide residue present
on a given food item.  Food item residue levels are then linearly
adjusted based on application rate.  The upper-bound estimates are used
to estimate risks since these values represent the high-end exposure
that may be encountered for terrestrial species that consume food items
that have received label-specified pesticide application. Although these
represent higher-end estimates, they do not represent the highest
possible exposure estimates.  

T-REX is a simulation model that, in addition to incorporating the
relationship between application rate and food item residue
concentrations, accounts for pesticide degradation in the estimation of
terrestrial EECs. T-REX calculates pesticide residues on each type of
food item on a daily interval for one year. A first-order decay function
is used to calculate the residue concentration at each day based on the
concentrations present from both initial and all subsequent
applications.  The decay rate is dependent on the foliar dissipation
half-life. The food item concentration on any given day is the sum of
all residues up to that day, taking into account the first-order
degradation. The initial application occurs on day 0 (t=0) and the model
runs for 365 days.  Over the 365-day run, the highest residue
concentration is the measure of exposure (EEC) used to calculate risk
quotients (RQs).

The foliar dissipation half-life and residue decline studies can be
important in estimating exposure because they essentially determine how
long the pesticide remains in or on food items after application. In
many cases, neither empirically determined foliar dissipation nor
residue decline half-life (with a day 0 residue) values are available,
in which case the default value of 35 days is used (Willis and McDowell,
1987). That was the case for this assessment. 

TERRPLANT Model

The TerrPlant (Ver.1.2.2) model is used to predict EECs from terrestrial
uses for terrestrial plants located in dry and semi-aquatic areas
adjacent to the treated field or treated water body.  TerrPlant assumes
100% efficiency in ground and aerial applications. A semi-aquatic area
(wetland) is defined as a low-lying area of terrestrial habitat that is
wet but may dry up at times throughout the year.  TerrPlant incorporates
two similar conceptual models for depicting dry and semi-aquatic areas
of terrestrial habitats.  For both models, a non-target area is adjacent
to the target area. Pesticide exposures to plants in the non-target area
are estimated to receive runoff and spray drift from the target area. 

For a dry area adjacent to the treatment area, runoff exposure is
estimated as sheet runoff. Sheet runoff is the amount of pesticide in
water that runs off of the soil surface of a target area of land which
is equal in size to the non-target area (1:1 ratio of areas).  In the
sheet runoff scenario, the treated area generating runoff is assumed to
drain into an area with equal size containing seedlings, resulting in 1,
2, or 5% of the application rate being deposited.  For semi-aquatic
areas, runoff exposure is estimated as channel runoff.  Channel runoff
is the amount of pesticide that runs off of a target area 10 times the
size of the non-target area (10:1 ratio of areas).  In the channel
runoff scenario, a ten-to-one ratio of watershed area to receiving area
results in 10, 20, or 50% of the application rate being deposited on
soil with emerging or emerged seedlings.  The magnitude of runoff is
assumed to be dependent on the water solubility of the pesticide active
ingredient.  For pesticides with a solubility of <10, 10 to 100, or >100
ppm, runoff fractions of 0.01, 0.02 or 0.05 respectively are selected by
the model user.  

  

Exposures through runoff and spray drift are then compared to measures
of survival and growth (e.g. effects to seedling emergence and
vegetative vigor) to develop RQ values.  

The model compares the combined deposition estimates from runoff and
spray drift to adverse effect levels measured in seedling emergence
studies.  In addition, RQs are derived for plants with consideration for
spray drift exposures.  For monocots and for dicots, TerrPlant compares
estimated spray drift deposition, without a runoff exposure component,
to the more sensitive measure of effect, either seedling emergence or
vegetative vigor (USEPA 2005). 

Table 7 summarizes the measures of ecological effects and exposure used
to assess ecological risk following exposure to metrafenone with the
proposed uses.

Table 7.  Measures of Ecological Effects and Exposure for Metrafenone

Assessment Endpoint	Surrogate Species and Measures of Ecological
Effect1,2	Measures of Exposure

Birds3	Survival	Bobwhite Quail acute oral LD50, subacute dietary LC50

Mallard Duck acute oral LD50,  subacute dietary LC50	

Upper bound residues on food items (foliar)

	Reproduction and growth	Bobwhite Quail reproduction NOAEC/LOAEC

	Mammals	Survival	Laboratory rat acute oral LD50

Laboratory mouse acute oral LD50



Reproduction and growth	Laboratory rat reproduction NOAEL/LOAEL

	Freshwater fish4	Survival	Rainbow trout 96-hr LC50

Bluegill sunfish 96-hr LC50	Peak EEC5

	Reproduction and growth	Fathead minnow NOAEC/LOAEC	60-day average EEC5

Freshwater invertebrates	Survival	Water flea 48-hr EC50	Peak EEC5

	Reproduction and growth	No acceptable study available	21-day average
EEC5

Marine/estuarine fish	Survival	Sheepshead minnow 96-hr LC50	Peak EEC5

	Reproduction and growth	No study available	60-day average EEC5

Marine/estuarine invertebrates	Survival	Eastern oyster 96-hr EC50

Saltwater mysid 96-hr LC50	Peak EEC5

	Reproduction and growth	Saltwater mysid NOAEC/LOAEC	21-day average EEC5

Terrestrial plants6	Survival and growth	Monocot Seedling emergence 

EC25, NOAEC or EC05

Monocot Vegetative Vigor

EC25, NOAEC or EC05 

Dicot Seedling emergence

EC25, NOAEC or EC05 

Dicot Vegetative Vigor

EC25, NOAEC or EC05	Estimates of runoff and spray drift to non-target
areas

Insects	Survival 	Honey bee acute contact 48-hr LD50	Maximum application
rate

Aquatic plants and algae	Survival and growth	Duckweed 7-day EC50, NOAEC

Cyanobacteria 96-hr EC50, NOAEC

Marine diatom 96-hr EC50, NOAEC

Freshwater diatom 96-hr EC50, NOAEC

Green algae 96-hr EC50,  NOAEC

Algae 72-hr EC50, NOAEC

Green algae 72-hr EC50, NOAEC	Peak EEC5

1LD50 = Lethal dose to 50% of the test population; NOAEC = No observed
adverse effect concentration; LOAEC = Lowest observed adverse effect
concentration; LC50 = Lethal concentration to 50% of the test
population; EC50/EC25 = Effect concentration to 50%/25% of the test
population.

2 If species listed in this table represent most commonly encountered
species from registrant-submitted studies, risk assessment guidance
indicates most sensitive species tested within taxonomic group are to be
used for baseline risk assessments.

3 Birds represent surrogates for amphibians (terrestrial phase) and
reptiles.

4 Freshwater fish may be surrogates for amphibians (aquatic phase).

5 One in 10-year return frequency.

6 Four species of two families of monocots - one is corn, six species of
at least four dicot families, of which one is soybeans.  



Analysis

Use Characterization

The proposed end-use product is “Metrafenone 300 SC” (EPA Reg. No.
7969-XXX), a suspension concentrate containing 25.2%
(3-bromo-6-methoxy-2-methylphenyl)(2,3,4-trimethoxy-6-methylphenyl)metha
none (metrafenone) at a concentration of 2.5 lbs metrafenone per gallon.
 The product is claimed to provide “optimum disease control when
applied in a regularly scheduled protective fungicide program and when
used in a spray program that rotates fungicides with different modes of
action.” The product is intended to control powdery mildew of grapes. 


Ground application is the proposed method of application.  The label
states, “do not apply directly to water, to areas where surface water
is present, or to intertidal areas below the mean high water mark.” 
The chemical is to be applied at most 6 times per season at a maximum
application rate of 0.3 lbs a.i./A (Table 5). The label also states,
“do not make more than 2 sequential applications of Metrafenone 300 SC
fungicide before alternating to a labeled fungicide with a different
mode of action.” 

Exposure Characterization

Environmental Fate and Transport

Summary

Metrafenone is a new chemical of the benzophenone class that is expected
to be slightly mobile.  Its major routes of degradation are aqueous
photolysis and aquatic metabolism, in both aerobic and anaerobic
conditions.  Soil metabolism is slow, with laboratory half-lives of 6
months to a year and accumulation over two years observed in field
studies.  In aquatic environments, the measured photolysis half-life was
6.4 days and metabolism in both aerobic and anaerobic occurred with
half-lives of one to four weeks.

Soil photolysis and anaerobic aquatic metabolism of metrafenone led to
one major degradate, CL 377160 [Methanone,
(3-bromo-6-methoxy-2-methylphenyl)(3-hydroxy-2,4-dimethoxy-6-methylpheny
l)-]., and anaerobic aquatic metabolism also led to six other major
degradates, but all were either unidentified or only tentatively
identified.  In addition, there were many minor degradates, which were
formed at low levels individually but reached substantial amounts as
groups.  

μg/L for the daily peak, 8.82 μg/L for the 21 day average, and 6.21
μg/L for the 60 day average. The highest aquatic EECs for metrafenone
were 20.22 μg/L for the daily peak, 17.67 μg/L for the 21 day average,
and 16.98 μg/L for the 60 day average.

No monitoring data are available to compare with model estimates. 
Bioaccumulation modeling was conducted because metrafenone has a log
octanol:water coefficient > 4.  Maximum residue concentrations in fish
are expected to range from 17,636 to 19,586 µg/kg-ww. 

Persistence

Metrafenone biodegrades slowly in terrestrial environments.  In
laboratory studies in a variety of soils, aerobic soil metabolism linear
half-lives ranged from 178 to 365 days.  In four of the eight soils
tested, data collection extended long enough to determine an empirical
DT50, of 124 to 188 days in two silt loam soils and 272 to 362 days in a
clay loam and sandy loam soil.  In these two soils, metabolism appeared
to slow after 272 days.  No data are available for anaerobic soil
metabolism rates.  Photolysis on soil was observed in laboratory studies
to occur with a linear half-life of 31 days.  

In aquatic environments, metrafenone biodegrades in weeks to months in
both aerobic and anaerobic conditions (linear half-lives of 24-27 days
and 18-22 days, respectively).  Considering abiotic degradation,
metrafenone is photolyzed in water (half-life of 6.4 days), but is
stable to hydrolysis at pH values from 4 to 9. 

Degradation Products 

The only positively identified major degradate of metrafenone was CL
377160 [Methanone,
(3-bromo-6-methoxy-2-methylphenyl)(3-hydroxy-2,4-dimethoxy-6-methylpheny
l)-].  CL 377160 was formed through soil photolysis at up to 18.9% AR
and through anaerobic aquatic metabolism at up to 10.8% AR in the total
system. It was also formed as a minor degradate through aquatic
photolysis and aerobic aquatic metabolism.   A compilation of identified
degradation products are shown in Appendix A.

In one anaerobic aquatic metabolism study, another six degradates were
formed at >9%, but these were either unidentified or only tentatively
identified.  These included TN (tentatively identified as a lactone
compound; maximum 3.3%, 26.9% and 28.0% in the water layer, sediment and
total system, respectively), MB (tentatively identified as a
hydroxylation product of TN; maximum 1.1%, 11.6% and 11.7% in the water
layer, sediment and total system, respectively), and four unidentified
degradates formed in the total system at 9.3% to 13% AR.  

Carbon dioxide was also a major degradate, formed through aquatic
photolysis at up to 25% AR and through all other measured processes as a
minor degradate.

Most processes also resulted in formation of a substantial amount of
minor degradates, some individually measured and identified, but most
not.  Although all of these degradates were present at less than 10%,
and some at very low levels, they still may be of exposure concern
because of the large overall amounts.  In some cases minor degradates,
mostly unidentified, make up more than 50% of the applied radioactivity
in a single sampling event.  In addition, based on the structure of the
parent compound and the proposed degradation pathways, many of the minor
degradates may have a high degree of structural similarity to each other
and/or the parent and so may have cumulative effects.

Mobility

Batch equilibrium data on metrafenone suggest that the compound will
sorb to organic surfaces and would be considered “slightly mobile”
according to the FAO classification scheme (organic carbon partition
coefficients range from 1,073 to 2,792 ml/g-oc).  Also according to FAO
classification, metrafenone’s solubility in water of 0.447 mg/L is
considered “slightly soluble.”  It showed low volatility from soil
and water with <0.5% volatilization in any laboratory study, consistent
with the vapor pressure of 1.15 x 10-6 mmHg.  Therefore, dissipation in
the environment is expected to occur predominantly via runoff of
suspended soil and sediments to which metrafenone is adsorbed.  Based on
terrestrial field dissipation studies in the UK , metrafenone was
detected at a soil depth of 20-30 cm after 2 years.

In aquatic systems, partitioning of metrafenone to sediment occurred
rapidly.  In one anaerobic system, half of the applied metrafenone was
detected in sediment on the first day, and in three other systems (one
anaerobic, two aerobic), at least 50% of the parent compound had
partitioned to sediment within three to seven days.  Including
degradates, partitioning was rapid in anaerobic systems but slower in
aerobic systems.  In two anaerobic aquatic metabolism studies, more than
half of the applied radioactivity (AR) was found in sediment within one
week and radioactivity in the water layer was down to <5% AR in two to
six weeks.  However, in aerobic aquatic metabolism studies in two
systems, from 8% to 28% AR remained in the water layer at study
termination (100 days).

Field Dissipation Studies

Field dissipation studies were conducted on bare plots in California
(CA), Washington (WA), Ontario (ON), and Florida (FL).  The first-order
dissipation half-life for metrafenone in surface soils (0-7.5 cm) was
144 days (DT 50 14-30 days; DT 90 272-360 days) in CA, 161.2 days (DT 50
181-269 days; DT 90 540-900 days) in WA, 210 days (DT 50 59-272 days; DT
90 598-710 days) in ON, and 161 days (DT 50 14-30 days; DT 90 360-451
days) in FL.  No degradation products were detected above the limit of
quantification (LOQ) in the field dissipation studies.

The reference degradation product in the field study was CL377160.
Degradation was not a clear route of metrafenone dissipation in field
studies because of the lack of detectable degradation products in soil. 
Leaching is possible route of dissipation. There were sporadic
detections of metrafenone with soil depth in the Florida study with
maximum detection depth of 15-30 cm, Ontario study with maximum
detection depth of 60-75 cm, Washington study with a maximum depth depth
of  7.5-15 cm, and  California study with a maximum detection depth of
15-30 cm. The field studies were not designed to assess runoff and
volatilization of metrafenone residues.     

Bioaccumulation in Fish

Bluegill sunfish exposed to metrafenone, at 5 and 50 µg/L, accumulated
metrafenone residues during a 28 day accumulation period. After the
accumulation phase, the fish were transferred to metrafenone-free water
for a 14 day depuration phase.  For the bromophenyl labeled metrafenone,
lipid normalized bioconcentration factors (BCFs) ranged 140 to 460 in
whole fish.  For trimethoxybenzene labeled metrafenone, lipid normalized
bioconcentration factors (BCFs) ranged 490 to 530 in whole fish. The
lipid normalized BCF range indicates that metrafenone is not expected to
accumulate in tissues of aquatic organisms. Major bioaccumulated
residues (>10% of TRR) were identified as
[(3-Bromo-6-methoxy-2-methylphenyl)(4-hydroxy-2,3-dimethoxy-6-ethylpheny
l)methanone (CL 434223),  CL1500699 (3-
bromo-6-methoxy-2-methylphenyl)[4-(beta-D-gluco pyran
uronosyloxy)-2,3-dimethoxy-6-methyphenyl]-methanone), and CL377160. 
These degradation products were detected in whole fish, viscera, fillet,
and in the exposure water.  The bioaccumulation rate at 90% steady-state
of total radioactive residue and metrafenone ranged from 1.3 to 1.8 days
and 1.8 to 2.1 days, respectively.  The 95% depuration rate of total
radioactive residue and metrafenone ranged from 1.8 to 2.3 days and 1.8
to 2.1 days, respectively.    

Measures of Aquatic Exposure

Aquatic Exposure Modeling

The estimated environmental concentrations (EECs) reported in the
assessment were calculated using the Tier II model for surface water
(PRZM/EXAMS). Sample inputs and outputs of the model are presented in
Appendix B.

PRZM (v3.12.2, May 2005) and EXAMS (v2.98.4.6, April 2005) are screening
simulation models coupled with the input shell pe5.pl (Aug 2007) to
generate daily exposures and 1-in-10 year EECs of metrafenone and total
metrafenone residues that may occur in surface water bodies adjacent to
application sites receiving metrafenone residues through runoff and
spray drift for specific scenarios.  PRZM simulates pesticide
application, movement and transformation on an agricultural field and
the resultant pesticide loadings to a receiving water body via runoff,
erosion and spray drift.  EXAMS simulates the fate of the pesticide and
resulting concentrations in the water body.  The standard scenario used
for ecological pesticide assessments assumes application to a 10-hectare
agricultural field that drains into an adjacent 1-hectare water body,
2-meters deep (20,000 m3 volume) with no outlet.  PRZM/EXAMS was used to
estimate screening-level exposure of aquatic organisms to metrafenone
residues. The measure of exposure for aquatic species is the 1-in-10
year return peak or rolling mean concentration.  The 1-in-10 year peak
is used for estimating acute exposures of direct effects to aquatic
organisms as well as indirect effects. The 1-in-10-year 60-day mean
concentration is used for assessing chronic exposure. The 1-in-10 year
21-day mean concentration is used for assessing chronic exposures to
aquatic invertebrates. 

Input Parameters

The appropriate input parameters were selected from the
physical/chemical properties and environmental fate data submitted by
the petitioner to support registration of metrafenone.  Input parameters
were selected in accordance with US EPA-OPP EFED water model parameter
selection guidelines, Guidance for Selecting Input Parameters in
Modeling the Environmental Fate and Transport of Pesticides, Version
2.1, November 10, 2009.   Expanded information about the models,
selection of input parameters and scenarios can be obtained from
http://www.epa.gov /oppefed1/models/water/index.htm.  

The use input parameters were selected from label for the end-use
product “Metrafenone 300 SC.”  The physical-chemical properties and
environmental fate input parameters were obtained from studies submitted
and reviewed by the Agency. 

Total Residues Modeling Input Parameters

Calculation of total residue half-lives for metrafenone are based on the
concentration (expressed as percent of applied radioactivity) of
extractable residues (Table 8).  Extractable residues include
metrafenone, CL 377160, tentatively identified compounds, and
unidentified compounds (Appendix A).  

Table 8. Total Extractable Metrafenone Residue Half-lives from
Laboratory Degradation Studies  

Study Type	MRID1	Half-life (days)	Environmental Matrix	Extractable
Residues

Aqueous Photolysis	-23	27

Total Mass Balance - VOC – CO2

Soil Photolysis	-24	47.8

Acetonitrile, acetonitrile:0.2NHCl, 0.5 N NaOH

Aerobic Soil	-27	169.1	sandy loam soil	Acetonitrile,
acetonitrile:acetone, acetonitrile:water

Aerobic Soil	-26	210.0	clay loam soil	Acetone, methanol:water

Aerobic Soil	-25	277.2	silty loam soil	Acetone, methanol :water,
acetonitrile:0.5NHCl

Aerobic Soil	-27	277.3	clay loam soil	Acetonitrile,
acetonitrile:acetone, acetonitrile:water

Aerobic Soil	-27	301.4	silt loam soil	Acetonitrile,
acetonitrile:acetone, acetonitrile:water 

Aerobic Soil	-26	315.1	sandy loam soil	Acetone, methanol:water 

Aerobic Soil	-27	330.1	silt loam soil	Acetonitrile,
acetonitrile:acetone, acetonitrile:water 

Aerobic Soil	-26	364.8	loamy sand soil	Acetone, methanol:water 

Anaerobic Aquatic	-29	182.0	DI water- silty clay loam	Water + Acetone,
methanol acetic acid, acetonitrile, 0.5N NaOH:acetonitrile, ammonium
hydroxide:acetonitrile

Anaerobic Aquatic	-31	577.6	pond-sandy loam	Water +
acetone:acetonitrile, acetonitrile:formic acid, acetonitrile;water
formic acid, acetonitrile:water:triethylamine, acetonitrile:0.05 M
sodium phosphate dibasic, 0.5N ammonium hydroxide

Aerobic Aquatic	-30	91.2	river-loam	Water + acetone, methanol:acetic
acid, methylene chloride, acetonitrile:0.5N NaOH

Aerobic Aquatic	-30	123.8	pond-sand	Total Mass Balance - VOC – CO2

1- Prefix MRID number is 472674-



Surface water

Scenarios used to run PRZM and EXAMS (Tier II) for the proposed use are
shown in Table 9.  Input parameters for modeling in Tier II are shown in
Table 10.  

Table 9.  Scenarios used to estimate Metrafenone concentrations in
surface water.

Agricultural Commodity	Crop Scenario	Met File	Scenario Characterization

Grapes	NY  

CA	W14860.dvf

W93193.dvf	Standard Scenarios for assessing pesticides use on grapes





Table 10.  PRZM/EXAMS Input Parameters for Metrafenone and Total
Extractable Metrafenone Residues

PARAMETER	Metrafenone	Total Extractable Metrafenone  Residues	COMMENT
SOURCE

Application Rate per Event

Lb a.i./A (kg a.i./ha)	0.3 lb a.i./A	0.3 lb a.i./A

Metrafenone 300 SC Label

No. of Applications

 (Interval)	6 (14 day)	6 (14 day)

Metrafenone 300 SC Label

CAM

(Chemical App. Method)	2	2	Broadcast spray	Metrafenone 300 SC Label

Depth of Incorporation	0	0	Default

	Spray Drift Fraction / Application Efficiency	0.01 / 0.99	0.01 / 0.99
Assume ground spray.	EFED Input Guidance

Aerobic Soil Metabolism t1/(	303 days	313 days	Upper 90th percentile of
the mean half-life (n=8)	MRID 47267425

MRID 47267426

MRID 47267427

Aerobic Aquatic Degradation  t1/(  	28.2 days	158 days	Upper 90th
percentile of the mean half-life (n=2) 	MRID 47267430

Anaerobic Aquatic Degradation  t1/(	25.3 days	989 days	Upper 90th
percentile of the mean half-life (n=2)	MRID 47267429

MRID 47267431

Aqueous Photolysis t1/(	6.4 days	27.0 days	Corrected for dark	MRID
47267423

Hydrolysis t1/(	0 days	0 days	Stable	MRID 47267422

Soil Partition Coefficient (Koc)	2188 mL/goc	2188 mL/goc	Average Koc
MRID 47267420

Molecular Weight	409 g/mole	409 g/mole

MRID 47267423

Water Solubility @ 25°C	0.474 mg/L	0.474 mg/L

MRID 47267423

Vapor Pressure	1.15 x 10-6 mmHg	1.15 x 10-6 mmHg

EPA Fact Sheet (9/06)



Tier II- PRZM/EXAMS

Tier II estimated environmental concentrations for metrafenone and total
metrafenone residues are shown in Table 11. 

Table 11.  Estimated Exposure Concentrations for Metrafenone and Total
Metrafenone Residues from Surface Water.  Concentrations are in μg/L
(ppb)

Agricultural Commodity/Scenario

	1-in-10 yr Peak	1-in-10 yr 21-Day Average	1-in-10 yr 60-Day Average 

Metrafenone

NY Grapes	11.70	8.82	6.21

CA Grapes	1.53	1.10	0.75

Total Metrafenone  Residues*

NY Grapes	20.22	17.67	16.98

CA Grapes	2.25	1.89	1.58

*Parent metrafenone + identified and unidentified extractable residues



b.	Aquatic Exposure Monitoring and Field Data

Monitoring data for metrafenone in surface water and ground water are
not available in the United States or Europe.

c.	Aquatic Bioaccumulation Assessment

Available data on the octanol-water partition coefficient (Kow) for
metrafenone indicates that this pesticide may accumulate in aquatic food
webs.  Because the Log Kow is > 4.0, KABAM v.1.0 was used to estimate
concentrations of metrafenone in tissues of aquatic organisms resulting
from bioaccumulation. Input parameters are provided in Table 12 and
estimated concentrations of metrafenone in fish are provided in Table
13.  Sample KABAM output is provided in Appendix D.

Table 12.  Input Parameters and Chemical Characteristics of Metrafenone
Used in KABAM

Characteristic	Value	Comments

Log KOW	4.3

	KOW	19953

	KOC   (L/kg OC)	2188	Input value used in PRZM/EXAMS to derive EECs. 



Time to steady state (TS; days)	8	This value is calculated automatically
from the Log KOW value entered above.

Pore water EEC (µg/L)	16.8	Value generated by PRZM/EXAMS benthic file
for New York Grapes scenario for metrafenone total residue and high
runoff scenario.  PRZM/EXAMS EEC represents the freely dissolved
concentration of the pesticide in the pore water of the sediment. 

The appropriate averaging period of the EEC is dependent on the specific
pesticide being modeled and is based on the time it takes for the
chemical to reach steady state. 21-day average concentration (EEC) was
used as averaging period closest to the time to steady state calculated
above.

Water Column EEC (µg/L)	17.7	Value generated by PRZM/EXAMS water column
file for New York Grapes scenario for metrafenone total residue and high
runoff scenario.  PRZM/EXAMS EEC represents the freely dissolved
concentration of the pesticide in the water column. 21-day average
concentration (EEC) was used as averaging period closest to the time to
steady state calculated above (as discussed above for pore water).      
              



Table 13. Estimated Concentrations of Metrafenone in Fish (based on
metrafenone total residue scenario)

Ecosystem Component	Total concentration (µg/kg-ww)	Lipid normalized
concentration (µg/kg-lipid)	Contribution due to diet (µg/kg-ww)
Contribution due to respiration (µg/kg-ww)

Small Fish	17,636	440909	862.94	16,773.41

Medium Fish	18,305	457626	1,651.07	16,653.98

Large Fish	19,586	489661	3,063.04	16,523.40



Measures of Terrestrial Exposure

Terrestrial Exposure Modeling

T-REX

Exposure of free-ranging terrestrial animals is a function of the timing
and extent of pesticide application with respect to the location and
behavior of those species. OPP’s terrestrial exposure model generates
exposure estimates assuming that the animal is present on the use site
at the time that pesticide levels are highest. The upper-bound pesticide
residue concentration on food items is calculated from both initial
applications and any additional applications, taking into account
pesticide degradation between applications. Although this approach is
conservative, it is reasonable, particularly when considering acute
risks.  For acute risks, the assumption is that the duration of exposure
is a single day and, again, occurs when residue levels are highest.  In
evaluating chronic risks, longer-term exposure estimates are also based
on the assumption that the animal is present on the use site when
residue levels are highest and furthermore that it repeatedly forages on
the use site.

The current screening-level approach does not directly relate timing of
exposure to critical or sensitive population, community, or ecosystem
processes. Given that the application timing and location is
crop-dependent, it is difficult to address the temporal and spatial
co-occurrence of metrafenone use and sensitive ecological processes.
However, pesticides are frequently used from spring through fall; crop
cultivation frequently starts in the spring, hence uses of metrafenone
are likely to occur in spring and perhaps summer depending on the
region. Spring and early summer are typically seasons of active
migrating, feeding, and reproduction for many wildlife species.  The
increased energy demands associated with these activities (as opposed to
hibernation, for example) can increase the potential for exposure to
pesticide-contaminated food items since agricultural areas can represent
a concentrated source of relatively easily obtained, high-energy food
items. In this assessment, the spatial extent of exposure for
terrestrial animal species is limited to the use area only and the area
immediately surrounding the use area.

Currently, the Agency does not require toxicity studies on reptiles and
amphibians in support of pesticide registrations. To accommodate this
data gap, birds are used as surrogates for terrestrial-phase amphibians
and reptiles. It is assumed that, given the usually lower metabolic
demands of reptiles and amphibians compared to birds, exposure to birds
would be greater due to higher relative food consumption. While this
assumption is likely true, there are no supported relationships
regarding the relative toxicity of a compound to birds and herpetofauna.
The lack of toxicity data on reptiles and amphibians represents a source
of uncertainty in this assessment.

Tables 14 and 15 list selected predicted EECs for birds, reptiles,
terrestrial amphibians, and mammals obtained from T-REX simulations for
the proposed use of metrafenone at the maximum label rates.  

Table 14.  Terrestrial Food-Item Residue Estimates for Birds with
Metrafenone Proposed Use on Grapes at 0.3 lbs a.i./A (6 apps./year; 14
day app. interval) with a Foliar Dissipation Half-life default value of
35 Days.

Crop	Food Item	Maximum Dose-Based EECs (mg/kg)1	Maximum Dose-Based EECs
(mg/kg)2	Maximum Dose-Based EECs (mg/kg)3	Dietary-Based EECs (ppm)4

Grapes	Short grass	274.49	156.52	70.08	241.01

	Tall grass	125.81	71.74	32.12	110.46

	Broadleaf plants/ small insects	154.40	88.04	39.42	135.57

	Fruits, pods, seeds, lg. insects	17.16	9.78	4.38	15.06

1Based on 20 gram birds (acute)

2 Based on 100 gram birds (acute)

3 Based on 1000 gram birds (acute)

4 Dietary-based EECs apply to both acute and chronic exposure



Table 15. Terrestrial Food-Item Residue Estimates for Mammals with
Metrafenone Proposed Use on Grapes at 0.3 lbs a.i./A (6 apps./year; 14
day app. interval) with a Foliar Dissipation Half-life default value of
35 Days.

Size Class

(grams)	Adjusted

LD501	EECs



Short Grass	Tall Grass	Broadleaf Plants/

Small Insects	Fruits/Pods/

Seeds/

Large Insects	Granivore



Dose-Based	Dose-Based	Dose-Based	Dose-Based	Dose-Based

15	2225.56	229.78	105.32	129.25	14.36	3.19

35	1800.71	158.81	72.79	89.33	9.93	2.21

1000	778.86	36.82	16.88	20.71	2.30	0.51

Dietary-Based EECs2	241.01	110.46	135.57	15.06	Not applicable

1 Herbivores/ insectivores; Granivores

2  Dietary-based EECs apply to both acute and chronic exposure



TERRPLANT

Effects on non-target terrestrial plants are most likely to occur as a
result of spray drift and/or runoff from ground applications.  These are
important factors in characterizing the risk of metrafenone to
non-target plants, which is assumed to reach off-site soil.  The
TerrPlant (Ver.1.2.2) model predicts EECs for terrestrial plants located
in dry and semi-aquatic areas adjacent to the treated field.  The EECs
are based on the application rate and solubility of the pesticide in
water and drift characteristics.  The amount of metrafenone that runs
off is a proportion of the application rate and is assumed to be 1%,
based on metrafenone’s solubility of <10 ppm (i.e. 0.474 mg/L) in
water.  Drift from ground applications are assumed to be 1% the
application rate. An incorporation depth was not referenced in the label
setting the default value to 1 inch for ground applications.  For a
standard scenario on an agricultural field, the runoff scenario for
terrestrial plants inhabiting dry areas adjacent to a field is
characterized as “sheet runoff” (one treated acre to an adjacent
acre; a 1:1 ratio) and inhabiting semi-aquatic or wetland areas adjacent
to a field is characterized as “channelized runoff” (10 treated acre
to an adjacent low-lying acre; a 10:1 ratio).  The TerrPlant model EECs
are presented in Table 16.  

Table 16.  Estimated Environmental Concentrations of Metrafenone for
Terrestrial Plants from Grape Use  TC \f 3 "Table IIIB-4.  Estimated
Environmental Concentrations of Imazapyr for Terrestrial Plants from All
Uses for Ecological Assessment. 

Application Method	Application Rate (lbs a.i./A)	Total Loading to Dry
areas (lb/A) 1	Total Loading to Semi-Aquatic Areas (lb/A)2	Drift (lb/A)3

Ground	0.3*	0.006	0.033	0.003

Ground	1.8**	0.036	0.198	0.018

1 EEC = Sheet Runoff + Drift (1% for ground)

2 EEC = Channelized Runoff + Drift = 1% for ground

3 EEC for ground (appl rate x 1% drift)

* Maximum single application rate

**Maximum seasonal application rate



Ecological Effects Characterization

Aquatic Effects Characterization

a. Aquatic Animals

(1) Acute Effects

Freshwater Fish and Aquatic-Phase Amphibians -Technical

The freshwater fish studies on rainbow trout (Oncorhynchus mykiss, MRID
47267443) and bluegill sunfish (Lepomis macrochirus, MRID 47267442) are
classified as supplemental for several reasons. The water samples were
not centrifuged prior to analytical determination. Without
centrifugation, the amount of chemical that is freely dissolved and
bioavailable cannot be determined. Stability of exposure to the
dissolved form throughout the test is unknown. This is especially a
problem as some of the testing concentrations were conducted above the
water solubility limit of the technical grade active ingredient (0.2-0.5
mg a.i./L at 12oC). Therefore, the concentrations are reported as mg
‘total’ a.i./L and are not useful for RQ calculations, but can
contribute to risk description.

Freshwater Fish and Aquatic-Phase Amphibians – Metabolites /
Degradates

Similar to freshwater fish studies on the technical, the freshwater fish
studies on degradates of metrafenone on rainbow trout (O. mykiss MRID
47267444, 47267445) are also classified supplemental. The water
solubility limit was not given, and there was no report of whether the
test solutions were centrifuged prior to analytical determination of the
test concentrations to ensure that the measured concentrations represent
bioavailable material. For example, in the latter study (MRID 47267445),
undissolved test substance (likely the result of exceeding the limit of
water solubility of the test material) was noted at the bottom of the
test vessel in all treatment vessels throughout the definitive test. 
Again, the concentrations are reported as mg ‘total’ a.i./L and are
not useful for RQ calculations, but can contribute to risk description.

Freshwater Fish and Aquatic-Phase Amphibians -Formulations

Similar to the freshwater fish technical grade and metabolite/degradate
studies, the freshwater fish study on rainbow trout (O. mykiss MRID
47267605) is also classified as supplemental. There was no report of
whether the test solutions were centrifuged prior to analytical
determination. Without centrifugation, the amount of chemical that is
freely dissolved and bioavailable cannot be determined. Stability of
exposure to the dissolved form throughout the test is unknown; neither
is the water solubility for this formulation active ingredient. Again,
the concentrations are reported as mg ‘total’ a.i./L and are not
useful for RQ calculations, but can contribute to risk description.

Table 17.  Freshwater Fish Acute Toxicity Data

Common Name	%AI	Study parameters	LC50/NOAEC/LOAEC	MRID	Classification/

Category

Technical AC 375839 (a.k.a. BAS 560F)

Rainbow trout

Oncorhynchus mykiss	97.1	96 hour flow-through study

2 reps / 10 fish per rep.

Mean-measured: <0.000498 (negative, solvent), 0.065, 0.13, 0.25, 0.43,
and 0.82 mg total a.i./L	96-hr LC50 > 0.82 mg total a.i./L

NOAEC: 0.25 mg total a.i./L

Endpoint(s) affected: mortality, sublethal effects.

Mortality

Cumulative mortality after 96 hours was 0% among all fish in the
negative and solvent control groups, and in the treatment groups exposed
to 0.13 and 0.25 mg a.i./L of AC 375839. Cumulative mortality was 5%
among fish exposed to 0.065, 0.43 and 0.82 mg a.i./L of AC 375839 after
96 hours.

Sublethal effects

No sublethal effects were observed among fish in the negative or solvent
controls, 0.065, 0.13, 0.25 or 0.43 mg a.i./L treatment groups exposed
to AC 375839 after 96 hours. Within the 0.82 mg a.i./L treatment group,
16% of fish still living were lethargic and 5% exhibited dark
discoloration after 96 hours.	47267443	Supplemental (not to be used in
risk estimation)/

At most, Highly toxic1

Bluegill sunfish Lepomis macrochirus	97.1	96 hour flow-through study

2 reps / 10 fish per rep.

Mean-measured: <0.000498 (negative, solvent), 0.066, 0.14, 0.25, 0.45,
and 0.87 mg total a.i./L	96-hr LC50 > 0.87 mg total a.i./L

NOAEC: 0.45 mg total a.i./L

Endpoint(s) affected: mortality, sublethal effects.

Mortality

Cumulative mortality after 96 hours was 0% among all fish in the
negative and solvent control groups and all treatment groups except the
0.87 mg a.i./L treatment group in which 15% of fish died.

Sublethal effects

No sublethal effects were observed among fish in the negative or solvent
controls, 0.066, 0.14, 0.25 or 0.45 mg a.i./L treatment groups exposed
to AC 375839 after 96 hours. Within the 0.87 mg a.i./L treatment group,
18% of fish still living were lethargic and 12% were lying on the bottom
of the test chamber with little motion other than gill movement after 96
hours.	47267442	Supplemental (not to be used in risk estimation)/ At
most, Highly toxic1

Metabolites/ Degradates

Rainbow trout

Oncorhynchus mykiss	99.5	Reg. No. 4074484 (Metabolite of BAS 560 F)

96 hour static study; limit test

2 reps (neg. control), 3 reps (treatment) / 10 fish per rep.

Mean-measured: <1 (negative) and 99 mg total a.i./L	96-hr LC50 > 99 mg
total a.i./L

NOAEC ≥ 99 mg total a.i./L

Endpoint(s) affected: none.	47267444	Supplemental (not to be used in
risk estimation)/

At most, Slightly toxic1

Rainbow trout Oncorhynchus mykiss	98.2	Reg. No. 4084564

(Metabolite of BAS 560F)

96 hour static study

1 rep / 10 fish per rep.

Mean-measured: <1 (negative), 4.4, 9.2, 20.3, 35.2 and 58.4 mg total
a.i./L	96-hr LC50 15.8 (9.2-35.2) mg total a.i./L

NOAEC: 9.2 mg total a.i./L

Endpoint(s) affected: mortality, sublethal effects

Mortality

Cumulative mortality at 96 hours was 80% in the 20.3 mg total a.i./L
concentration and 100% in the two highest concentrations.

Sublethal effects

Tottering and distended abdomen were observed after 4 hours in the group
exposed to 58.4 mg total a.i./L; also observed among those in the group
exposed to 20.3 mg total a.i./L between 24 and 72 hours. Apathy and
distended abdomen were observed after 24 hours among those in the 35.2
mg total a.i./L treatment group and after 96 hours among those in the
group exposed to 20.3 mg total a.i./L.	47267445	Supplemental (not to be
used in risk estimation)/ Slightly toxic1



Formulations

Rainbow trout

Oncorhynchus mykiss 	24.7% a.i.; 

294 g BAS 560 00F/L	BAS 560 00F (SF 10358, RLF 12359) 

96 hour static study

2 reps. / 10 fish per rep.

Mean-measured: <4.05 (neg. control), 12, 20, 34, 56, and 94 mg form/L
[<1 (neg. control), 3.0, 4.9, 8.3, 13.7, and 23.3 mg total a.i./L]	96-hr
LC50 >94 mg form/L [>23.3 mg total a.i./L]

NOAEC ≥ 94 mg form/L [23.3 mg total a.i./L]

Endpoint(s) affected: none.  	47267605	Supplemental (not to be used in
risk estimation)/ At most, Slightly toxic1

1Based on LC50 (mg/L): < 0.1 very highly toxic; 0.1-1 highly toxic;
>1-10 moderately toxic; >10-100 slightly toxic; >100 practically
nontoxic



Freshwater Invertebrates -Technical

The freshwater invertebrate study using the technical grade active
ingredient on water flea (Daphnia magna, MRID 47267437) is classified as
supplemental. The water samples were not centrifuged prior to analytical
determination. Without centrifugation, the amount of chemical that is
freely dissolved and bioavailable cannot be determined. Stability of
exposure to the dissolved form throughout the test is unknown. This is
especially a problem as some of the testing concentrations were
conducted at or above the water solubility limit of the technical grade
active ingredient (0.2-0.5 mg a.i./L at 12oC). Therefore, the
concentrations are reported as mg ‘total’ a.i./L and are not useful
for RQ calculations, but can contribute to risk description.

Freshwater Invertebrates –Metabolites / Degradates

Similar to freshwater invertebrate study on the technical, the
freshwater invertebrate studies on degradates of metrafenone on the
water flea (D. magna MRID 47267438, 47267439) is also classified
supplemental. The water solubility limit was not given, and there was no
report of whether the test solutions were centrifuged prior to
analytical determination of the test concentrations to ensure that the
measured concentrations represent bioavailable material.  Again, the
concentrations are reported as mg ‘total’ a.i./L and are not useful
for RQ calculations, but can contribute to risk description.

Freshwater Invertebrates –Formulations

Similar to the freshwater invertebrate technical grade and
metabolite/degradate studies, the freshwater invertebrate study on water
flea (D. magna MRID 47267604) is also classified as supplemental. There
was no report of whether the test solutions were centrifuged prior to
analytical determination. Without centrifugation, the amount of chemical
that is freely dissolved and bioavailable cannot be determined.
Stability of exposure to the dissolved form throughout the test is
unknown; neither is the water solubility for this formulation active
ingredient. Again, the concentrations are reported as mg ‘total’
a.i./L and are not useful for RQ calculations, but can contribute to
risk description.

Table 18.  Freshwater Invertebrate Acute Toxicity Data

Common Name	%AI	Study parameters	EC50/NOAEC/LOAEC	MRID	Classification/

Category

Technical AC 375839 (a.k.a. BAS 560F)

Water flea

Daphnia magna	97.1	48 hour static study

2 reps.; 10 inverts. per rep

Mean-measured: <0.000498 (negative, solvent), 0.059, 0.12, 0.22, 0.45,
and 0.92 mg total a.i./L 	48-hr EC50 > 0.92 mg total a.i./L

Slope:  N/A

NOAEC ≥ 0.92 mg total a.i./L

Endpoint(s) affected: none.  	47267437	Supplemental (not to be used in
risk estimation)/

At most, Highly toxic1

Metabolites/ Degradates

Water flea

Daphnia magna	99.5	CL 375816

48 hour static study

4 reps.; 5 inverts per rep.

Mean-measured: <1 (negative), 12.9, 25.8, 51.4, and 102.5 mg total
a.i./L	48-hr EC50 > 102.5 mg total a.i./L Slope:  N/A

≥  102.5 mg total a.i./L

Endpoint(s) affected: none.  	47267438	Supplemental (not to be used in
risk estimation)/ Practically non-toxic1

Water flea

Daphnia magna	98.2	CL 4084564

48 hour static study

4 reps.; 5 inverts per rep.

Mean-measured: <1 (negative), 6.4, 12.5, 23.2, 49.6, 66.4 mg a.i./L
48-hr EC50 = 50.9 (42.1-63.5) mg total a.i./L

Slope:  4.59 (2.52-6.66)

NOAEC =  23.2 mg total a.i./L

Endpoint(s) affected: immobility.

Immobility

Cumulative immobility was 0% among all daphnids exposed to 0 (negative
control), 6.4 and 12.5 mg total a.i./L of CL 4084564 (Metabolite of BAS
560 F) after 48 hours. Cumulative immobility was 5% among animals
exposed to 23.2 mg total a.i./L, 55% among daphnids exposed to 49.6 mg
total a.i./L and 65% among animals exposed to 66.4 mg total a.i./L of CL
4084564 (Metabolite of BAS 560 F) after 48 hours.

  	47267439	Supplemental (not to be used in risk estimation)/ Slightly
toxic1

Formulations

Water flea 

Daphnia magna	24.7% a.i.; 294 g BAS 560 00 F/L	BAS 560 00 F (SF 10358,
RLF 12359) 

48 hour static study

2 reps.; 10 inverts per rep. 

Mean-measured: <0.810 (neg. control), 1.7, 3.1, 6.1, 12.2, 24.3, and
47.1 mg form/L [<0.20 (neg. control), 0.42, 0.76, 1.5, 3.0, 6.0, and
11.6 mg total a.i./L]

	48-hr EC50: 17.1 (12.8-24.3) mg form/L [4.2 (3.2-6.0) mg total a.i./L]

NOAEC: 6.1 mg form/L [1.5 mg total a.i./L]

Endpoint(s) affected: mortality and sublethal effects (immobility)

Mortality

Cumulative mortality after 48 hours was 0% among animals exposed to
mean-measured concentrations of 0 (negative control), 1.7, 3.1, 6.1 and
12.2 mg form/L. Cumulative mortality was 65% among animals exposed to
24.3 mg form/L and 90% among animals exposed to 47.1 mg form/L after 48
hours.

Immobility

Cumulative immobility aft 48 hours was 0% at mean-measured
concentrations of 1.7 and 47.1 mg form/L; 5% at neg. control, 3.1, and
6.1 mg form/L; 15% at 12.2 mg form/L; and, 25% at 24.3 mg form/L.  

	47267604	Supplemental (not to be used in risk estimation) / Moderately
toxic1

1Based on EC50 (mg/L): < 0.1 very highly toxic; 0.1-1 highly toxic;
>1-10 moderately toxic; >10-100 slightly toxic; >100 practically
nontoxic



Marine/Estuarine Fish

Unlike the majority of the aquatic studies, which were supplemental on
account of not having centrifuged samples which clearly exceeded the
water solubility limit, the marine/estuarine fish study on the
sheepshead minnow (Cyprinodon variegatus, MRID 47267446) is acceptable
on account of having centrifuged the two highest concentrations, both of
which were above the solubility limit of 0.3 mg a.i./L (in saltwater).
The results reveal no effects on mortality or sublethal effects.

Table 19.  Marine/ Estuarine Fish Acute Toxicity Data 

Common Name	%AI	Study parameters	LC50/NOAEC/LOAEC	MRID	Classification/

Category

Technical AC 375839 (a.k.a. BAS 560F)

Sheepshead Minnow

Cyprinodon variegatus	94.2	96 hour flow-through study

2 reps / 10 fish per rep.

Mean-measured: <0.04 (negative, solvent), 0.072, 0.13, 0.24, 0.32 (0.13
mg a.i./L based on centrifuged samples) and 0.65 (0.35 mg a.i./L based
on centrifuged samples) mg a.i./L	96-hr LC50 > 0.35 mg dissolved a.i./L

NOAEC ≥ 0.35 mg dissolved a.i./L

Endpoint(s) affected: none.	47267446	Acceptable/

At most, Highly toxic1

1Based on LC50 (mg/L): < 0.1 very highly toxic; 0.1-1 highly toxic;
>1-10 moderately toxic; >10-100 slightly toxic; >100 practically
nontoxic



Marine/Estuarine Invertebrates – Technical

The marine/estuarine invertebrate study using the technical grade active
ingredient on eastern oyster (Crassostrea virginica, MRID 47267440) is
classified as supplemental. Given that centrifugation was not performed
on all concentration test levels, it is possible that the endpoint
retrieved from this study will provide an underestimation of risk. For
example, we know that after centrifugation of the highest test level the
mean-measured concentration decreased by 42% relative to the
pre-centrifugation mean-measured concentration. The reduction in soluble
substance is likely due to the concentration being above the limit of
solubility (i.e., 0.3 mg a.i./L). Nevertheless, it is unknown from the
study results whether a similar reduction will occur at lower
concentrations, including one more above the limit of solubility and the
three levels remaining below the limit of solubility. Similarly, the
saltwater mysid study (Americamysis bahia, MRID 47267441) is classified
supplemental on account of no centrifugation of water samples at any
test concentration level prior to analytical determination.  Without
centrifugation, the amount of chemical that is freely dissolved and
bioavailable cannot be determined. Stability of exposure to the
dissolved form throughout the test is unknown. Therefore, the
concentrations are reported as mg ‘total’ a.i./L and are not useful
for RQ calculations, but can contribute to risk description.

Table 20.  Marine/ Estuarine Invertebrate Acute Toxicity Data

Common Name	%AI	Study parameters	EC50/LC50/NOAEC/LOAEC	MRID
Classification/

Category

Technical AC 375839 (a.k.a. BAS 560F)

Eastern oyster Crassostrea virginica	94.2	96 hour flow-through study

20 bivalves per level

Time-weighted average: <0.04 (negative, solvent), 0.0522, 0.104, 0.203,
0.287, and 0.573 mg total a.i./L (highest concentration centrifuged
yielded 0.33 mg dissolved a.i./L)	96-hr EC50: 0.22 (0.20-0.25) mg total
a.i./L2 

NOAEC: 0.0522 mg total a.i./L

Endpoint(s) affected: shell deposition.  

Shell deposition

Relative to the negative control, the mean percent reduction in shell
growth starting with the negative solvent is as follows: 17.4, 13.9,
26.3, 44.3, 84.2, and 100%, respectively. No significant differences (p=
0.05) were detected between the two controls.	47267440	Supplemental (not
to be used in risk estimation)/

Highly toxic1



Saltwater mysid Americamysis bahia	94.2	96 hour flow-through study

2 reps./ 10 mysids per rep.

Time-weighted average: <0.04 (negative, solvent), 0.0749, 0.129, 0.240,
0.416, and 0.663 mg total a.i./L

	96-hr LC50: 0.487 (0.428-0.575) mg total a.i./L2

NOAEC: 0.0749 mg total a.i./L

Endpoint(s) affected: mortality, sublethal effects.

Mortality

At 96 hours, cumulative mortality at the TWA concentrations 0.129 and
0.240 mg total a.i./L was 5%, at 0.416 mg total a.i./L was 15%, and at
0.663 mg total a.i./L was 95%.

Sublethal effects

No sub-lethal effects were observed in the controls or TWA 0.0749-0.240
mg total ai/L treatment levels.  At test termination 7 out of the
surviving 17 mysids in the 0.416 mg total ai/L level and the single
surviving mysid at the 0.663 mg total ai/L level were observed swimming
erratically.

	47267441	Supplemental (not to be used in risk estimation)/ Highly
toxic1

1Based on EC50 (mg/L): < 0.1 very highly toxic; 0.1-1 highly toxic;
>1-10 moderately toxic; >10-100 slightly toxic; >100 practically
nontoxic

2 Range is 95% confidence interval for endpoint



(2) Chronic Effects

Freshwater Fish – Technical

The freshwater fish study on fathead minnow (Pimephales promelas, MRID
47267449) is classified as supplemental. The solubility limit of the
test compound is not reported; it is possible given previous reports
that the limit was approximately 0.2-0.5 mg a.i./L at 12 oC, which
implies that the two highest test concentrations (0.421 and 0.839 mg
total a.i./L) potentially exceeded the solubility limit and yet
centrifugation (or filtration) was not mentioned as part of the protocol
prior to analytical determination. Without centrifugation, the amount of
chemical that is freely dissolved and bioavailable cannot be determined.
Stability of exposure to the dissolved form throughout the test is
unknown. Therefore, the concentrations are reported as mg ‘total’
a.i./L and are not useful for RQ calculations, but can contribute to
risk description.

Hatching occurred at all levels on Day 4, and hatching success averaged
88-94% for all levels, with no statistically significant differences
observed.  Post-hatch survival (28-days post-hatch) was
statistically-reduced compared to the negative control at the 227, 421,
and 839 μg total a.i./L levels (p≤0.05).  Post-hatch survival
averaged 96% at the negative control through 118 μg total a.i./L
levels, and 87, 86, and 11% at the 227, 421, and 839 μg total ai/L
levels, respectively.  No clinical signs of toxicity were observed
during the study in any treatment group.  Fish length was significantly
reduced relative to the average negative control length at levels above
421 μg total ai/L and wet and dry weight were significantly lower than
the negative control weights at the 839 μg total ai/L level; however,
significant impact on survival occurred at these levels.

Table 21.  Freshwater Fish Chronic Toxicity Data 

Common Name	%AI	Study parameters	NOAEC/LOAEC	MRID
Classification/Category

Technical AC 375839 (a.k.a. BAS 560F)

Fathead minnow

Pimephales promelas	97.1	32-day flow-through test

80 embryos per level, split into 20 embryos per cup, 1 cup per aquarium,
4 rep. aquaria per treatment

Time-weighted average: <0.498 (negative, solvent), 57, 118, 227, 421,
and 839 µg total a.i./L	NOAEC:  0.118 mg total a.i./L

LOAEC:  0.227 mg total a.i./L

Most sensitive endpoint: post-hatch survival

Endpoint(s) affected: post-hatch survival and growth (total length, wet
and dry weight)	47267449	Supplemental (not to be used in risk
estimation)



Freshwater Invertebrates – Technical

A chronic freshwater invertebrate study (MRID 47267447) with metrafenone
technical (97.1%) was deemed invalid due to instability of the chemical
under test conditions. A non-guideline chronic midge study (Chironomus
riparius, MRID 47267501) with metrafenone technical (97.1%) is also
invalid on the basis of low negative control emergence.

Marine/Estuarine Fish

No chronic marine/estuarine fish studies were submitted for review.

Marine/Estuarine Invertebrates- Technical

The marine/estuarine invertebrate study on saltwater mysid (Americamysis
bahia, MRID 47267448) is classified as acceptable. Although the
solubility limit of the test compound is not reported; it is possible
given previous reports that the limit was approximately 0.2-0.5 mg
a.i./L at 12 oC. The mean-measured test concentrations of the total
metrafenone present do not exceed the suggested solubility limit. In
addition, the highest nominal concentration (0.05 mg a.i./L) is
significantly below solubility (i.e., ≥ 4 - 10 times); in this
particular case, not centrifuging is considered to not affect
acceptability of the study. Finally, given the dilution system design,
where the stock solution was a solvent stock solution suggests that
solubility of the compound is not an issue in this particular case.

45 μg ai/L level (1.4 versus 5.8 offspring/female).  Similarly, the
number of offspring per female per reproductive day was
statistically-reduced compared to the negative control at the 45 μg
ai/L (0.10 versus 0.44 offspring/female/day).  Although not
statistically-compared, the percentage of females producing young
averaged ≥85% at the control through 22 μg ai/L treatment levels, but
only 25% at the 45 μg ai/L level.  The NOAEC for reproduction was
reported to be 22 μg ai/L.   

Table 22.  Marine/ Estuarine Invertebrate Chronic Toxicity Data 

Common Name	%AI	Study parameters	NOAEC/LOAEC	MRID
Classification/Category

Technical AC 375839 (a.k.a. BAS 560F)

Saltwater mysid Americamysis bahia	94.2	28-day flow-through test

Before pairing: 60 mysids per level

After pairing: 20 mysids per level

Time-weighted average: <LOD (negative, solvent), 2.8, 6.2, 12, 22, and
44 µg total a.i./L	NOAEC:  0.022 mg a.i./L1

LOAEC:  0.044 mg a.i./L

Most sensitive endpoint: reproduction (number of offspring/female/repro.
day)

Endpoint(s) affected: reproduction (number of offspring/female/repro.
day)	47267448	Acceptable

1 Bold value is the value that will be used to calculate risk quotients



Aquatic Plants

Vascular Aquatic Plants

The vascular aquatic plant study (MRID 47267511) on duckweed (Lemna
gibba) is classified as supplemental for several reasons, which are
considered major guideline deviations. The test was conducted for 7 days
instead of the guideline prescribed 14 days. More importantly, the
dissolved or soluble concentrations (i.e., post-centrifugation) of test
material were not determined. As a result of the latter, the stability
of exposure to the dissolved form throughout the test is unknown. This
is especially a problem as some of the testing concentrations were
conducted above the solubility limit of the technical grade active
ingredient (0.457 mg/L in water; 0.3 mg/L in 20X AAP media both at pH9).
Therefore, the concentrations are reported as mg ‘total’ a.i./L and
are not useful for RQ calculations, but can contribute to risk
description.

Non-vascular Aquatic Plants - Technical

The non-vascular aquatic plant studies on cyanobacteria (Anabaena
flos-aquae; MRID 47267512), marine diatom (Skeletonema costatum, MRID
47267513), freshwater diatom (Navicula pelliculosa, MRID 47267514), and
green algae (Pseudokirchneriella subcapitata, MRID 47267515) are
classified as supplemental for several reasons. The water samples were
not centrifuged prior to analytical determination. Without
centrifugation, the amount of chemical that is freely dissolved and
bioavailable cannot be determined. Stability of exposure to the
dissolved form throughout the test is unknown. This is especially a
problem as some of the testing concentrations were conducted above the
solubility limit of the technical grade active ingredient (0.457 mg/L in
freshwater; 0.3 mg/L in saltwater). Therefore, the concentrations are
reported as mg ‘total’ a.i./L and are not useful for RQ
calculations, but can contribute to risk description.

Non-vascular Aquatic Plants – Metabolites / Degradates

Similar to the non-vascular aquatic plant technical grade studies, the
non-vascular aquatic plant studies on the degradates are classified as
supplemental for several important reasons. For example, the algae study
(Pseudokirchneriella subcapitata MRID 47267516) did not report daily
observations of test solution appearance, metabolite water solubility,
and method of filtration of test solution, which leads to uncertainty in
the measured concentrations as well as the relationship of mean-measured
and nominal concentrations relative to the metabolite water solubility
value. For this reason too, the concentrations are reported as mg
‘total’ a.i./L and are not useful for RQ calculations, but can
contribute to risk description. In addition, the other algae study
(Pseudokirchneriella subcapitata MRID 47267517) did not centrifuge the
water samples prior to analytical determination. Without centrifugation,
the amount of chemical that is freely dissolved and bioavailable cannot
be determined. Stability of exposure to the dissolved form throughout
the test is unknown; neither is the metabolite water solubility. Again,
the concentrations are reported as mg ‘total’ a.i./L and are not
useful for RQ calculations, but can contribute to risk description.

Non-vascular Aquatic Plants - Formulations

Similar to the non-vascular aquatic technical grade and
metabolite/degradate studies, the non-vascular aquatic plant study on
the green algae (Pseudokirchneriella subcapitata) is also classified as
supplemental. Although centrifugation was conducted on the water samples
in this particular case the protocol states that it was used to remove
algal cells, which suggests that the centrifugation method may not have
removed the undissolved material. Without centrifugation, the amount of
chemical that is freely dissolved and bioavailable cannot be determined.
Stability of exposure to the dissolved form throughout the test is
unknown; neither is the water solubility for this formulation active
ingredient. Again, the concentrations are reported as mg ‘total’
a.i./L and are not useful for RQ calculations, but can contribute to
risk description.

Table 23.  Aquatic Plant Toxicity Data  TC \f 3 "Table IIIC-7. 
Non-target Aquatic Plant Toxicity for Imazapyr Acid and Isopropylamine
Salt of Imazapyr. 

Species

	%A.I.	Study Parameters	EC50/NOAEC	MRID No.	Study Classification

Technical AC 375839 (a.k.a. BAS 560F)

Vascular Aquatic Plants

Duckweed 

Lemna gibba

	94.2	Tier II study

7 day static renewal study

3 reps. / 4 plants per rep.

Mean measured: <0.04 (negative, solvent), 0.057, 0.10, 0.21, 0.41, and
0.76 mg a.i./L	Biomass (dry weight)

EC50 > 0.76 mg total a.i./L

NOAEC: 0.21 mg total a.i./L

Frond density

EC50 > 0.76 mg total a.i./L

NOAEC: 0.41 mg total a.i./L

Growth rate

EC50 > 0.76 mg total a.i./L

NOAEC: 0.41 mg total a.i./L

Most sensitive endpoint: biomass based on NOAEC

Endpoint(s) affected: biomass, frond density, growth rate	47267511
Supplemental (do not use in risk estimation)

Non-Vascular Aquatic Plants

Cyanobacteria (blue-green algae)

Anabaena flos-aquae	94.2	Tier II study

96 hour static study

3 reps.

Initial measured: <0.04 (negative, solvent), 0.0883, 0.139, 0.217,
0.580, and 0.862 mg a.i./L	Biomass (area under growth curve), cell
density, growth rate

EC50 > 0.862 mg total a.i./L

≥ 0.862 mg total a.i./L

Endpoint(s) affected: none.	47267512	Supplemental (do not use in risk
estimation)

Marine Diatom

Skeletonema costatum	94.2	Tier II study

96 hour static study

3 reps.

Initial measured: <0.04 (negative, solvent), 0.0509, 0.109, 0.214,
0.272, and 0.680 mg a.i./L	Biomass (area under growth curve)

EC50: 0.57 (0.38-0.85) mg total a.i./L

NOAEC: 0.0509 mg total a.i./L

Cell density

EC50 > 0.680 mg total a.i./L

NOAEC: 0.272 mg total a.i./L

Growth rate

EC50 > 0.680 mg total a.i./L

NOAEC: 0.272 mg total a.i./L

Most sensitive endpoint: biomass

Endpoint(s) affected: biomass, cell density, growth rate	47267513
Supplemental (do not use in risk estimation)

Freshwater Diatom

Navicula pelliculosa	94.2	Tier II study

96 hour static study

4 reps.

Initial measured: <0.04 (negative, solvent), 0.0761, 0.154, 0.276,
0.432, and 0.914 mg a.i./L	Biomass (area under growth curve)

EC50 > 0.914 mg total a.i./L

NOAEC: 0.432 mg total a.i./L

Cell density

EC50 > 0.914 mg total a.i./L

NOAEC: ≥0.914 mg total a.i./L

Growth rate

EC50 > 0.914 mg total a.i./L

NOAEC: ≥0.914 mg total a.i./L

Endpoint(s) affected: biomass based on NOAEC	47267514	Supplemental (do
not use in risk estimation)

Green Algae

Pseudokirchneriella subcapitata	97.1	Tier I study

72 hour static study

6 reps. (negative, solvent controls); 3 reps. (treatments)

Mean-measured: <0.498 (negative, solvent), 60, 123, 232, 472, and 870
g a.i./L	Biomass (area under growth curve)

EC50: 0.71 (0.65-0.77) mg total a.i./L

NOAEC: 0.23 mg total a.i./L

Cell density

EC50: 0.74 (0.67-0.82) mg total a.i./L

NOAEC: 0.23 mg total a.i./L

Growth rate

EC50 > 0.87 mg total a.i./L

NOAEC: 0.23 mg total a.i./L

Most sensitive endpoint: biomass

Endpoint(s) affected: biomass, cell density, growth rate	47267515
Supplemental (do not use in risk estimation)

Metabolites/ Degradates

Non-Vascular Aquatic Plants

Algae 

Pseudokirchneriella subcapitata	99.5	CL 375816 (Metabolite of BAS 560 F)

Tier I study

72 hour static study

5 reps. (negative control); 3 reps. (treatments)

Mean-measured: ND (negative), 6.50, 12.66, 25.80, 51.45, and 101.92 mg
a.i./L	Biomass (area under growth curve), Chlorophyll-a, and Growth rate

EC50 > 101.9 mg total a.i./L

NOAEC ≥ 101.9 mg total a.i./L

Endpoint(s) affected: none.	47267516	Supplemental (do not use in risk
estimation)

Algae

Pseudokirchneriella subcapitata	98.2	CL 4084564 (Metabolite of BAS 560
F)

Tier I study

72 hour static study

5 reps. (negative control); 3 reps. (treatments)

Mean-measured: ND (negative), 3.21, 6.28, 9.9, 18.57, 38.78, and 58.03
mg a.i./L	Chlorophyll-a

EC50: 24 (21-27) mg total a.i./L

NOAEC: 9.9 mg total a.i./L

Biomass (area under growth curve)

EC50: 26 (22-30) mg total a.i./L

NOAEC: 9.9 mg total a.i./L

Growth rate

EC50: 44 (40-47) mg total a.i./L

NOAEC: 9.9 mg total a.i./L

Most sensitive endpoint: chlorophyll-a

Endpoint(s) affected: chlorophyll-a, biomass, and growth rate	47267517
Supplemental (do not use in risk estimation)

Formulations

Non-Vascular Aquatic Plants

Green Algae Pseudokirchneriella subcapitata	24.7	BAS 560 00F (SF 10358,
RLF 12359)

Tier I study

72 hour static study

6 reps. (negative control); 3 reps. (treatments)

Initial mean-measured: <0.05 (negative), 0.188, 0.371, 0.716, 1.383,
2.717, and 5.681 mg a.i./L	Cell density

EC50: 0.66 (0.47-0.91) mg total a.i./L

NOAEC: 0.188 mg total a.i./L

Biomass (area under growth curve)

EC50: 0.73 (0.53-0.99) mg total a.i./L

NOAEC: 0.188 mg total a.i./L

Growth rate

EC50: 5.2 (4.4-6.2) mg total a.i./L

NOAEC: 0.188 mg total a.i./L

Most sensitive endpoint: cell density

Endpoint(s) affected: cell density, biomass, growth rate	47267607
Supplemental (do not use in risk estimation)



2. Terrestrial Effects Characterization

a. Terrestrial Animals

(1) Acute Effects

Birds – Technical

The acute avian oral studies (MRID 47267502, 47267503) on 23-week old
Northern bobwhite quail (Colinus virginianus) and 20-week old mallard
duck (Anas platyrhynchos), respectively, assessed over 14 days are
classified as acceptable.  AC 375839 Technical was administered to the
birds via gelatin capsules at nominal levels of 0 (vehicle control),
400, 600, 900, 1350, and 2025 mg ai/kg bw (limit dose).  The 14-day
acute oral LD50 was >2025 mg ai/kg bw (>limit dose).  The 14-day NOAEL
was 2025 mg ai/kg bw, as there were no mortalities, clinical signs of
toxicity, or treatment-related effects on body weight or food
consumption during the 14-day study.  In addition, no toxicological
effects were observed at necropsy.  AC 375839 Technical (metrafenone)
would be classified as practically non-toxic to young adult Northern
bobwhite quail (C. virginianus) as well as to young adult mallard duck
(A. platyrhynchos) in accordance with the classification system of the
U.S. EPA.  

The acute avian dietary studies (MRID 47267504, 47267505) on 11-day old
Northern bobwhite quail (C. virginianus) and 9-day old mallard duck (A.
platyrhynchos), respectively, assessed over 8 days are classified as
acceptable. AC 375839 Technical was administered to the birds in the
diet at nominal concentrations of 0 (negative control), 100, 270, 729,
1968, and 5314 mg ai/kg diet (adjusted for purity).  Mean-measured
concentrations were <3.6 (<LOD, control), 98, 262, 809, 2130, and 6070
mg ai/kg diet, respectively.  The 8-day acute dietary LC50 was >6070 mg
ai/kg diet.  Given there was no dose-response, the NOAEC was the highest
concentration tested, 6070 mg a.i./kg diet. There were no
treatment-related mortalities, clinical signs of toxicity, or effects on
food consumption.  Some gross pathological changes were observed.  AC
375839 Technical (metrafenone) would be classified as practically
non-toxic to juvenile bobwhite quail (C. virginianus) as well as to
juvenile mallard duck (A. platyrhynchos) on an acute dietary basis, in
accordance with the classification system of the U.S. EPA.

Table 24.  Avian Acute Toxicity Data

Common Name	%AI	Study parameters	LD50/LC50 NOAEL/

LOAEL	MRID	Classification/Category

Technical AC 375839 (a.k.a. BAS 560F)

Northern Bobwhite Quail  Colinus virginianus	95.86	Acute oral study

5 birds/sex/dose level

14 day observation period

Nominal: 0 (vehicle), 400, 600, 900, 1350, and 2025 mg a.i./kg bw 

	LD50 > 2025 mg a.i./kg bw 

NOAEL: 2025 mg/kg bw

Probit slope: N/A

Endpoint(s) affected: none.	47267502	Acceptable/

Practically non-toxic1

Mallard Duck

Anas platyrhynchos	95.86	Acute oral study

5 birds/sex/dose level

14 day observation period

Nominal: 0 (vehicle), 400, 600, 900, 1350, and 2025 mg a.i./kg bw 	LD50
>2025 mg a.i/kg bw

NOAEL:  2025 mg a.i./kg bw

Probit slope: N/A

Endpoint(s) affected: none.	47267503	Acceptable/

Practically non-toxic1

Northern Bobwhite Quail  Colinus virginianus	95.86	Acute dietary study

12 birds per rep.(neg. control & treatment); 3 reps. (neg. control), 1
rep. per treatment

5 days on treatment, 3 additional days observation

Mean-measured: <3.6 (neg. control), 98, 262, 809, 2130, and 6070 mg
a.i./kg diet	LC50 >6070 mg a.i./kg diet

NOAEC: 6070 mg a.i./kg diet

LOAEC >6070 mg a.i./kg diet

Issues3: body weight change (significant reduction in body weight gain
(39%, relative to Control 1) at the 262 mg ai/kg diet level). However,
no concentration-response was observed so it may not be biologically
significant.	47267504	Acceptable/

Practically non-toxic2

Mallard Duck

Anas platyrhynchos	95.86	Acute dietary study

12 birds per rep.(neg. control & treatment); 3 reps. (neg. control), 1
rep. per treatment

5 days on treatment, 3 additional days observation

Mean-measured: <3.6 (neg. control), 98, 262, 809, 2130, and 6070 mg
a.i./kg diet	LC50 > 6070 mg a.i./kg diet

NOAEC:  6070 mg a.i./kg diet

LOAEC >6070 mg a.i./kg diet

Issues3: body weight change (significant reduction in body weight gain
(19%, relative to controls) at the 262 mg ai/kg diet level). However, no
concentration-response was observed so it may not be biologically
significant.	47267505	Acceptable/

Practically non-toxic2

1 Based on LD50 (mg/kg) <10 very highly toxic; 10-50 highly toxic;
51-500 moderately toxic; 501-2000 slightly toxic; >2000 practically
nontoxic

2  Based on LC50 (mg/kg) <50 very highly toxic; 50-500 highly toxic;
501-1000 moderately toxic; 1001-5000 slightly toxic; >5000 practically
nontoxic

3 The Northern bobwhite and mallard duck acute dietary studies were
conducted at the same time in the same laboratory using the same feed.
Therefore, the observance of body weight change at the same
concentration level (262 mg a.i./kg diet) in both studies calls into
question the validity of the effect as a result of the chemical versus
some other factor.



Mammals  - Technical

In an acute oral toxicity study (MRID 47267522), three per sex, fasted,
young adult C57BL mice [(age: 8- 13 weeks old, wt. males 23.0-25.7g,
females 17.0-18.7g)] were given a single oral dose of the test material
(BAS 560 F)  prepared in 0.5% CMC solution in doubly distilled water in
a sequential manner at a dose level of 2000 mg/kg bw by gavage and
observed for 14 days. The three females were dosed in step 1, and the
three males in step 2. The oral LD50 is > 2000 mg/kg in mice which
classifies the product (metrafenone technical) in EPA Toxicity Category
III for oral toxicity.

One male animal died on Day 4. This animal showed poor general health,
dyspnea, tremor, piloerection and sunken flanks. The dead mouse showed
discoloration of the lungs, and ulcer/erosion in stomach. All other male
and female animals survived showed no obnormalities, and gained body
weight during the first week post-exposure.  No gross abnormalities were
noted for any of the surviving animals when necropsied at the
termination.

Mammals – Formulation

In an acute oral toxicity study (MRID 47267609), 5/sex of 
Sprague-Dawley derived (Crl:CD(SD)BR) albino rats (age: 8 weeks; weight:
206-229 g males and 165-184 g females) were given a single oral dose of
AC 375839 300 g/L SC (RLF12359) (Lot No. R2066-048; 294 g/L and 25.21%
AC 375839; density 1.19 g/mL; pH 6.6; viscous beige liquid) as received
at a dose of 5000 mg/kg bw administered by oral gavage.  The amount of
test solution to be administered was calculated for each animal. Animals
were observed for clinical signs of toxicity and mortality several times
on the day of dosing and daily for 14 days.  Individual body weights
were recorded prior to dosing (day 0) and on days 7 and 14. A gross
necropsy examination was performed on all animals at scheduled
euthanasia. All animals survived and gained weight. No clinical signs of
toxicity were observed. No gross pathological findings were observed at
necropsy. The oral LD50 is > 5000 mg/kg in rats which classifies the
product (metrafenone formulation) in EPA Toxicity Category IV for oral
toxicity.

Table 25.  Mammalian Acute Toxicity Data 

Common Name	%AI	Study parameters	LD50 /NOAEL	MRID
Classification/Category

Technical AC 375839 (a.k.a. BAS 560F)

Mouse	94.2	Acute oral study

2000 mg technical/kg bw (limit test) administered by gavage

3/sex/dose level

14-day observation period	Acute oral LD50 >2000 mg technical/kg bw (F,
M, both)2

NOAEL:  No NOAEL

LOAEL: No LOAEL	47267522	Acceptable/ 

Practically non-toxic1

Formulation

Laboratory albino rat	25.21%; AC 375839 300 g/ L SC (RLF 12359)	Acute
oral study

5000 mg form/kg bw (limit test) administered by gavage

5/sex/dose level

14-day observation period	Acute oral LD50 >5000 mg form/kg bw (F, M,
both) [> 1,260.5 mg a.i./kg bw] 3

NOAEL:  No NOAEL

LOAEL: No LOAEL	47267609	Acceptable4/

Practically non-toxic1

1 Based on LD50 (mg/kg) <10 very highly toxic; 10-50 highly toxic;
51-500 moderately toxic; 501-2000 slightly toxic; >2000 practically
nontoxic

2 One male animal died on Day 4. This animal showed poor general health,
dyspnea, tremor, piloerection and sunken flanks. The dead mouse showed
discoloration of the lungs, and ulcer/erosion in stomach.

3 All animals survived and gained weight. No clinical signs of toxicity
were observed. No gross pathological findings were observed at necropsy.


4 The study satisfies the OECD Guideline 401, which is no longer
considered an acceptable protocol. The preferred protocol is OECD 425:
Acute Oral Toxicity-Up-and-Down Procedure. 



Terrestrial Invertebrates – Technical

The terrestrial invertebrate study on honey bees (Apis mellifera, MRID
47267508) classified as acceptable. The contact test had 4% mortality in
the negative and solvent controls and 0% mortality in the 100 µg
a.i./bee level by 48 hours; there were no sub-lethal effects in the
contact test. The oral test also had 4% mortality in the negative
control, 2% mortality in the solvent control, and 2% mortality in the
114 µg a.i./bee level at 24 and 48 hours; sub-lethal effects were 0% in
the negative control, 2% in the solvent control, and 6% in the 114 µg
a.i./bee level only at 4 hours.

In a 14 day acute limit toxicity study, earthworms (Eisenia fetida, MRID
47267518) were exposed to AC 375839 at a nominal concentration of 1000
mg a.i./kg dry weight of artificial soil. No concurrent reference
chemical test was conducted in this study. The report indicated that the
experiment was carried out in accordance with OECD 207. However, only
one concentration was tested which did not fulfill the requirement of
the guideline. No earthworm mortality was observed in the water control
or test substance treatment. There was one mortality in the acetone
control group. The 14 day LC50 was > 1000 mg a.i./kg dry soil, the
concentration tested. No significant difference in earthworm burrowing
time (i.e., time needed for 10 earthworms to burrow into the soil after
placement on soil surface) was observed. The average weight loss between
Day 0 and Day 14 was 20.6, 3.5 and 39.7 mg in the test groups of water
control, acetone control, and test substance treatment, respectively.
There was a significant difference in weight change between acetone
control and test substance treatment. However, there was no significant
difference between the water control and the test substance. Therefore,
the sub-lethal effect of AC 375839 at a concentration of 1000 mg a.i./kg
dry wt soil on weight loss is uncertain. The end-point toxicity
concentration of AC 375839 can not be determined from this study,
however, it is considered to be non-lethal to earthworms up to a
concentration of 1000 mg a.i./kg dry soil. No other observable compound
related toxicity effect was reported.

Terrestrial Invertebrates – Metabolites

In a 14 day acute toxicity study, earthworms (E. fetida, MRID 47267519)
were exposed to CL 377160 at nominal concentrations of 0, 198, 296, 444,
667, and 1000 mg CL 377160/kg dry weight of artificial soil. No
concurrent reference chemical test was conducted in this study, however,
the facility conducts annual test with 2-chloroacetamide in a
concentration range of 0 – 30 mg/kg dw of soil. The experiment was
carried out in accordance with OECD 207. There were no observable
compound related toxicity effects. No sub-lethal toxicity, specifically
body weight loss, was observed. Calculations using the mean body weight
for each treatment against the mean initial body weight (440 mg each)
showed that there were body weight gains of 3.3%, 5.3%, 7.7%, 10.5%,
4.6%, and 2.7% for the treatments of 0, 198, 296, 444, 667, 1000 mg/kg
dry soil weight. No other toxicity effect was reported. In addition, no
earthworm mortality was observed in the water control or in test
substance treatments. The 14 day LC50 was > 1000 mg/kg dw of soil.  The
14 day NOEC, based on mortality and body weight, was 1000 mg/kg dw of
soil, the highest concentration tested. The CL 377160 is considered to
be non-toxic to earthworms up to a concentration of 1000 mg/kg dw of
soil based on this study. However, a freeze storage stability study
submitted by the applicant (PMRA # 1620213) showed that CL 377160
rapidly bound and degraded in soils even at – 5 ºC. Therefore, the
LC50 obtained from this study is uncertain and the actual LC50 could be
lower. 

Terrestrial Invertebrates – Formulations

The terrestrial invertebrate study on honey bees (A. mellifera, MRID 
47267606) classified as supplemental. The study uses a formulation to
test toxicity. For honeybee acute contact toxicity studies, a TGAI test
compound is required. Relative to a similar honeybee acute contact
toxicity test (MRID 47267508), which shows no mortality at the treatment
level (100 g a.i./bee), this formulation appears to be more toxic at
a lower nominal concentration (100 g product./bee ≈ 24 g
a.i./bee) having 24% mortality. This information suggests that there is
something in the formulation that is more toxic than the active
ingredient acting alone. Finally, the concentrations of test substance
in the dosing solutions were not determined. Therefore, the actual dose
levels used are unknown.

The contact test had 2% mortality in the negative and solvent controls
and 24% mortality in the 100 µg a.i./bee level by 48 hours; sub-lethal
effects were 0% in the negative and solvent controls, and 10% in the 100
µg a.i./bee level only at 4 hours but not thereafter. The oral test
also had 2% mortality in the negative control, 0% mortality in the
solvent control, and 4% mortality in the 113.4 µg a.i./bee level by 48
hours; sub-lethal effects were 0% in the negative control, 2% in the
solvent control, and 0% in the 113.4 µg a.i./bee level.

In a 14 day acute limit toxicity study, earthworms (E. fetida, MRID
47267608) were exposed to AC 375839 300 g/L SC RLF12359 (SF10358) at
1000 mg formulation/kg dry weight of artificial soil. No concurrent
reference chemical test was conducted in this study. The report
indicated that the experiment was carried out in accordance with OECD
207. However, only one concentration was tested which did not fulfill
the requirement of the guideline. No earthworm mortality was observed in
the water control or in test substance treatment. The 14 day LC50 was >
1000 mg formulation/kg dry soil. No significant difference in earthworm
burrowing time (i.e., time needed for 10 earthworms to burrow into the
soil after placement on soil surface) was observed at day 7. The average
weight loss between Day 0 and Day 14 was 20.6 and 87.9 mg in the test
groups of water control and test substance treatment, respectively. The
difference is statistically significant. The 14 day NOEC, based on body
weight loss, was < 1000 mg/kg dry soil, the concentration tested. The
end-point toxicity concentration of the test substance can not be
determined from this study; however, it is considered to be non-lethal
to earthworms up to a concentration of 1000 mg formulation/kg dry soil.
No other observable compound related toxicity effect was reported.

Table 26.  Terrestrial Invertebrate Acute/Subacute Toxicity Data

Common Name	%AI	Study parameters	LD50 /NOAEL	MRID
Classification/Category

Technical AC 375839 (a.k.a. BAS 560F)

Honey bees

Apis

Mellifera	95.86	48 hour acute contact and oral toxicity tests

5 reps. / 10 bees per rep.

 μg a.i./bee; Oral: 0 (negative, solvent), 114 μg a.i./bee	48 hour
contact LD50 > 100 g ai/bee 

NOAEC: 100 μg a.i./bee

LOAEC > 100 µg a.i./bee 

48 hour oral LC50 > 114 g ai/bee 

NOAEC: 114 μg a.i./bee

LOAEC > 114 µg a.i./bee 	47267508	Acceptable/ Practically non-toxic1

Earthworm Eisenia fetida	95.86	14 day acute limit toxicity

4 reps (treatment); 1 rep (control) / 10 earthworms per rep.

Nominal: 1,000 mg a.i./kg dry soil	14 day LC50 >1,000 mg a.i./kg dry
soil

NOAEC < 1,000 mg a.i./kg dry soil

LOAEC = 1,000 mg a.i./kg dry soil

Endpoint(s) affected: possibly weight loss	47267518	Supplemental/
Non-GLN2

Metabolites

Earthworm Eisenia fetida	97	CL 377160 (hydrolytic metabolite of
metrafenone)

14 day acute toxicity

4 reps (treatment); 1 rep (control) / 10 earthworms per rep.

Nominal: 198, 296, 444, 667, and 1000 mg CL 377160/kg dry soil          
     	14-day LC50 >1,000 mg CL377160/kg dry soil

NOAEC: 1,000 mg CL 377160/kg dry soil

LOAEC: 1,000 mg CL 377160/kg dry soil

Endpoint(s) affected: none.	47267519	Supplemental/ Non-GLN2

Formulations 

Honey bees

Apis mellifera	24.4% a.i.; 

288 g/L	AC 375839 in a 300 g/L SC (SF10358/ RLF12359)

48 hour acute contact and oral toxicity tests

5 reps. / 10 bees per rep.

negative, solvent), 100 μg test material3/bee; Oral: 0 (negative,
solvent), 113.4 μg test material/bee	48 hour contact LD50 > 100 g
form/bee [>24.4 μg a.i./bee]

NOAEC < 100 μg form/bee [<24.4 μg a.i./bee]

LOAEC: 100 µg form/bee [24.4 μg a.i./bee]

48 hour oral LC50 > 113.4 g form/bee [>27.7 μg a.i./bee]

NOAEC: 113.4 μg form/bee [27.7 μg a.i./bee]

LOAEC > 113.4 µg form/bee [> 27.7 μg a.i./bee]	47267606	Supplemental/
Practically non-toxic1 

Earthworm Eisenia fetida	288 g a.i./L	AC 375839 300 g/L SC RLF12359
(SF10358)

14 day acute limit toxicity

4 reps (treatment); 1 rep (control) / 10 earthworms per rep.

Nominal: 1,000 mg form/kg dry soil	14 day LC50 >1,000 mg form4/kg dry
soil

NOAEC < 1,000 mg form/kg dry soil

LOAEC < 1,000 mg form/kg dry soil

g a.i./bee) <2 highly toxic; 2-10.99 moderately toxic; ≥11
practically non-toxic

2 Deemed acceptable by PMRA

3 ‘Test material’ is assumed to mean ‘formulation’

4 Not enough information provided in the study to determine active
ingredient content 



(2) Chronic Effects

Birds - Technical

≥1320 mg a.i./kg diet. 

The one-generation reproductive toxicity study (MRID 47267507) used 16
pairs per level of ca. 5-month old mallard duck (Anas platyrhynchos)
over 22 weeks.  BAS 560 F was administered to the birds in the diet at
nominal concentrations of 0 (control), 450, 900, or 1350 mg ai/kg diet. 
Mean-measured concentrations were <18.6 (<LOQ, control), 438, 848, and
1316 mg ai/kg diet, respectively.  No treatment-related effects were
observed on any adult parameter at any treatment level, or on any
offspring parameter at the 438 and 848 mg ai/kg diet levels.  At the
1316 mg ai/kg diet level, a statistically-significant reduction in the
number of eggs laid per hen per week was observed compared to the
control (3.3 versus 4.5 eggs/hen/week).  Hatchability was also reduced
at the 1316 mg ai/kg level, where the percentage of chicks
“dead-in-shell” of fertile eggs increased from 15.7% for the control
level to 36.8% for the 1316 mg ai/kg diet level.  As a direct result,
the percentage of hatched chicks of fertile eggs was also
statistically-different from the control (57.0 versus 77.0%).  The study
was deemed supplemental on account of several guideline deviations
including lack of reporting for pre-test mortality, the initial age of
the birds was below (ca. 5 months) recommended age (at least 7 months),
and cage size was significantly smaller than recommended (OPPTS
recommends at least 10,000 cm2 per bird; instead, the floor space was
only 4225 cm2 per bird).

Table 27.  Avian Chronic Toxicity Data

Common Name	%AI	Study Parameters	NOAEC/LOAEC	MRID	Classification

Technical AC 375839 (a.k.a. BAS 560F)

Northern Bobwhite Quail

Colinus virginianus	95.86	1-generation reproduction study

Pre-laying exposure 10 weeks; egg laying exposure 12 weeks

2 birds per pen (1 ♂: 1♀); 20 pens per neg. control and treatment

Mean measured:  <3.75 (neg. control), 181, 486, and 1320 mg a.i./kg diet
NOAEC ≥ 1320 mg a.i./kg diet

LOAEC ≥ 1320 mg a.i./kg diet

Endpoint(s) affected: none.	47267506	Acceptable

Mallard Duck

Anas platyrhynchos	99.4	1-generation reproduction study

Pre-laying exposure 10 weeks; egg laying exposure 12 weeks

2 birds per pen (1 ♂: 1♀); 20 pens per neg. control and treatment

Mean measured:  <18.6 (neg. control), 438, 848, and 1316 mg a.i./kg diet
NOAEC: = 848 mg a.i./kg diet1

LOAEC: 1316 mg a.i./kg diet

Endpoint(s) affected: egg production (eggs laid per ♀ per wk) and
hatchability (% dead-in-shell of fertile eggs)	47267507	Supplemental

1 Bold value is the value that will be used to calculate risk quotients



Mammals - Technical

In a rat 2-generation reproduction study (MRIDs 46415729, 46415728) and
given the parental animals, no treatment-related effects were observed
on mortality, clinical signs of toxicity, or macroscopic examinations.
The LOAEL for parental toxicity is 1000 ppm (equivalent to 72.8/84.8
mg/kg bw/day [M/F]), based on decreased body weights and body weight
gains in the F1 males.  The NOAEL is 500 ppm (equivalent to 35.9/42.9
mg/kg bw/day [M/F]). In the offspring, no effects of treatment were
observed on clinical signs of toxicity, litter parameters, sexual
maturation, anogenital distance, hematology, or macroscopic or
microscopic pathology. The LOAEL for offspring toxicity is 10,000 ppm
(equivalent to 759/864 mg/kg bw/day [M/F]), based on decreased body
weights in the F1 and F2 pups.  The NOAEL is 1000 ppm (equivalent to
72.8/84.8 mg/kg bw/day [M/F]). No effects of treatment were observed on
estrous cycle number or length, sperm parameters, primordial follicle
count, or reproductive performance. Thus, the LOAEL for reproductive
performance was not observed.  The NOAEL for reproductive performance is
10,000 ppm (equivalent to 759/864 mg/kg bw/day [M/F]).

In a rat developmental toxicity study (MRID 46415726), no
treatment-related effects were observed on mortalities, clinical signs,
body weights, body weight gains, food consumption, hematology, liver
weights, liver histology, or gross pathology relative to maternal
toxicity. Therefore, the maternal LOAEL was not observed.  The maternal
NOAEL is 1000 mg/kg/day (limit dose). Regarding developmental toxicity:
there were no treatment-related effects on the numbers of litters,
fetuses (live or dead), resorptions (early, late, or complete litter) or
on sex ratio or post-implantation loss, on fetal body weights or on
skeletal ossification, indicating no effect on fetal growth or
development; there were no treatment-related external, visceral, or
skeletal variations on development or other malformations. Thus, the
developmental LOAEL was not observed.  The developmental NOAEL is 1000
mg/kg/day (limit dose).

In a rabbit developmental toxicity study (MRID 46415727), no
treatment-related effect was observed on mortalities, hematology, or
gross pathology relative to maternal toxicity. Therefore, the maternal
LOAEL is 350 mg/kg/day, based on decreased body weight gains and food
consumption; increased liver weights; and increased incidences and/or
severity of periportal hepatocellular hypertrophy and diffuse
hepatocellular vacuolation.  The maternal NOAEL is 50 mg/kg/day.
Regarding developmental toxicity: there were no treatment-related
effects on the numbers of litters, fetuses (live or dead), resorptions
(early, late, or complete litter) or on sex ratio or post-implantation
loss, on fetal body weights or on skeletal ossification, indicating no
effect on fetal growth or development; there were no treatment-related
external, visceral, or skeletal variations on development or other
malformations. Thus, the developmental LOAEL was not observed.  The
developmental NOAEL is 700 mg/kg/day.

Table 28.  Mammalian Chronic Toxicity Data

Common Name	%AI	Study Parameters	NOAEC/

LOAEC	MRID	Classification/Category

Technical AC 375839 (a.k.a. BAS 560F)

Rat	95.86	2-generation reproduction study 30 CD Sprague-Dawley
rats/sex/group/generation, by feeding (diet).

3 treatment groups; 1 untreated diet control group

Nominal: 0, 5001, 1000, 10000 ppm

M: 0, 35.9, 72.8, 759 mg BAS 560 F/kg/day

F: 0, 42.9, 84.8, 864 mg BAS 560 F/kg/day

	Parental systemic NOAEL (M/F): 35.9/42.9 mg/kg bw/day1

LOAEL (M/F): 72.8/84.8 mg/kg bw/day, based on decreased body wts and
body wt gain F1 males as well as body wts in F1 and F2 females

Offspring/Develop-mental Toxicity NOAEL (M/F): 72.8/84.8 mg/kg bw/day

LOAEL (M/F): 759/864 mg/kg bw/day, based on decreased body wts in F1 and
F2 pups 

Reproductive Toxicity NOAEL (M/F): 759/864 mg/kg bw/day 

LOAEL (M/F):  not attained	46415729

46415728	Acceptable / Guideline

Rat	95.86	Developmental toxicity study

25 rats per dose, by gavage.

3 treatment groups; 1 untreated control group

0, 50, 500, 1000 mg BAS 560 F/kg/day	Maternal

NOAEL: 1000 mg/kg/day (HDT; limit dose)

LOAEL: not attained

Developmental

NOAEL: 1000 mg/kg/day (HDT; limit dose)

LOAEL: not attained	46415726	Acceptable/ Guideline

Rabbit	95.86	Developmental toxicity study

25 rabbits per group, by gavage.

3 treatment groups; 1 untreated control group

0, 50, 350, 700 mg BAS 560 F/kg/day	Maternal

NOAEL: 50 mg/kg/day

LOAEL: 350 mg/kg/day, based on decreased body wt gains and food
consumption; increased liver wts; increased incidences and/or severity
of periportal hepatocellular hypertrophy and diffuse hepatocellular
vacuolation

Developmental

NOAEL: 700 mg/kg/day (HDT)

LOAEL: not attained	46415727	Acceptable/ Guideline

1 Bold value is the value that will be used to calculate risk quotients



b. Terrestrial Plants

The two tier I terrestrial plant studies, seedling emergence (MRID
47267509) and vegetative vigor (MRID 47267510), are both supplemental
and are based on the UK/EU formulation (BAS 560 00F, 42.8% purity). The
lower application rates in the studies (0.091 and 0.288 lbs a.i./A for
the seedling emergence study; and, 0.091 and 0.285 lbs a.i./A for all
but soybean [0.099 and 0.283 lbs a.i./A] for the vegetative vigor study)
relative to the label application rate (0.3 lbs a.i./A) leads to
uncertainty in the risk characterization especially as effects were
noted, but the NOAEC and EC05 are undefined. The latter two endpoints
are used for endangered species risk calculations, which cannot be done
in this case. Tier II tests are requested to define the latter
endpoints, to have a study available that is based on the U.S.
formulation, and, subsequently, reduce uncertainty in risk
characterization.

All species were not significantly affected by the two treatments in the
seedling emergence study.  The most sensitive monocot and dicot species
could not be determined.  The NOAEC for all species (monocot and dicot)
was 0.288 lbs ai/A. The EC05, EC25 >0.288 lbs a.i./A. For the highest
treatment level tested, the following effects were noted -- the %
inhibition relative to control that is greater than 5% was observed in
the following plants for the given endpoint: emergence (oat, tomato);
survival (oat, onion, tomato), dry weight (onion, ryegrass), and height
(cucumber, onion, soybean, tomato). 

All species were not significantly affected by the two treatments in the
vegetative vigor study.  The most sensitive monocot and dicot species
could not be determined.  The NOAEC for all monocot species was 0.285
lbs ai/A. The EC05, EC25 >0.285 lbs a.i./A. The NOAEC for all dicot
species was the same as that for the monocots except for the soybean
which was 0.283 lbs a.i./A (with the EC05 and EC25 > 0.283 lbs a.i./A).
For the highest treatment level tested, the following effects were noted
-- the % inhibition relative to control that is greater than 5% was
observed in the following plants for the given endpoint: dry weight
(ryegrass) and height (none). 



Risk Characterization

Risk Estimation –Integration of Exposure and Effects Data

A quantitative estimation of risk integrates EECs and toxicity estimates
and evaluates the likelihood of adverse ecological effects to non-target
species. In a deterministic approach, an exposure estimate is divided by
a single point estimate of toxicity to calculate a risk quotient (RQ).
The RQ is then compared to Agency Levels of Concern (LOCs, Appendix H),
which serve as criteria for categorizing potential risk to non-target
organisms and the need to consider regulatory action.  

Risk to Aquatic Animals and Plants

The greatest amount of uncertainty in the assessment stems from aquatic
studies which were largely based on total concentrations (both dissolved
and undissolved) of the test compound. In all cases (except for the
chronic study on the saltwater mysid, but including aquatic plants), the
risk quotient values were not calculated.

Aquatic Animals

Risk following acute exposure

Freshwater Fish and Aquatic-Phase Amphibians

The acute aquatic risk quotients (RQs) for freshwater fish and
aquatic-phase amphibians were not calculated. Test compound in solution
was not centrifuged and measured (post-centrifugation) in any of the
acute freshwater fish studies (on the technical, metabolites, and
formulations), even though higher concentrations tested exceeded or
likely exceeded the solubility limit of the test compound.  Without
centrifugation, the amount of chemical that is freely dissolved and
bioavailable cannot be determined.  Uncertainty in the level of
dissolved test compound in the solution for all studies renders
calculated endpoints suitable for qualitative use only.

Freshwater Invertebrates

The acute aquatic risk quotients (RQs) for freshwater invertebrates were
not calculated. Test compound in solution was not centrifuged and
measured (post-centrifugation) in any of the acute freshwater
invertebrate studies (on the technical, metabolites, and formulations),
even though higher concentrations tested exceeded or likely exceeded the
solubility limit of the test compound. Without centrifugation, the
amount of chemical that is freely dissolved and bioavailable cannot be
determined. Uncertainty in the level of dissolved test compound in the
solution for all studies renders calculated endpoints suitable for
qualitative use only.

Marine/Estuarine Fish

The study on the technical active ingredient (MRID 47267446) yielded an
LC50 greater than the highest concentration tested because there were no
mortalities and no sublethal effects; therefore, RQs are not reported.

Marine/Estuarine Invertebrates

The acute aquatic risk quotients (RQs) for marine/estuarine
invertebrates were not calculated. Test compound in solution was not
consistently centrifuged and measured (post-centrifugation) in any of
the acute marine/estuarine invertebrate studies (on the technical), even
though higher concentrations tested exceeded or likely exceeded the
solubility limit of the test compound.  Without centrifugation, the
amount of chemical that is freely dissolved and bioavailable cannot be
determined.  Uncertainty in the level of dissolved test compound in the
solution for all studies renders calculated endpoints suitable for
qualitative use only.

Risk following chronic exposure

Freshwater Fish and Aquatic-Phase Amphibians

The chronic aquatic risk quotients (RQs) for freshwater fish and
aquatic-phase amphibians were not calculated. Test compound in solution
was not centrifuged and measured (post-centrifugation) in the chronic
freshwater fish study (on the technical), even though higher
concentrations tested exceeded or likely exceeded the solubility limit
of the test compound. Without centrifugation, the amount of chemical
that is freely dissolved and bioavailable cannot be determined. 
Uncertainty in the level of dissolved test compound in the solution for
this study renders calculated endpoints suitable for qualitative use
only.

Freshwater Invertebrates

No acceptable guideline and non-guideline chronic studies on freshwater
invertebrates are available.  Therefore, a quantitative estimation of
risk cannot be conducted.  Chronic risk to freshwater invertebrates
cannot be precluded.

Marine/Estuarine Fish

No chronic studies on marine/estuarine fish are available.  Therefore, a
quantitative estimation of risk cannot be conducted.   Chronic risk to
marine/estuarine fish cannot be precluded.

Marine/Estuarine Invertebrates

The chronic aquatic LOC was not exceeded for the proposed use of
metrafenone for the technical tested. Table 29 summarizes the RQ values
and scenarios used to compare to chronic aquatic LOCs for marine
invertebrates.

Table 29.  Metrafenone: Chronic Risks to Marine/Estuarine Invertebrates
(Application Rate 0.3 lbs a.i./A, 6 Applications/Year)



Species	

 Toxicity Endpoint (µg/L)	

Scenario

	

21-Day EEC

(µg/L)	

Chronic Risk Quotient1	

Levels of Concern Exceeded2

Saltwater mysid

Americamysis bahia	

NOAEC = 22

g a.i./L

Technical	Grapes (Metrafenone)

NY Grapes

CA Grapes	

8.82

1.10	

0.40

0.05	

No

No

Saltwater mysid

Americamysis bahia	

NOAEC = 22

g a.i./L

Technical	Grapes (Total Metrafenone Residues)

NY Grapes

CA Grapes	

17.67

1.89	

0.80

0.09	

No

No

1 Chronic Risk Quotients are calculated using the following formula:
EEC/NOAEC

2 Chronic LOC for marine/estuarine invertebrates = 1



Aquatic Plants

The aquatic plant risk quotients (RQs) were not calculated. Test
compound in solution was not centrifuged and measured
(post-centrifugation) in these studies (on the technical, metabolites,
and formulations), even though higher concentrations tested exceeded or
likely exceeded the solubility limit of the test compound. Without
centrifugation, the amount of chemical that is freely dissolved and
bioavailable cannot be determined.  Uncertainty in the level of
dissolved test compound in the solution for these studies renders
calculated endpoints suitable for qualitative use only.

Risk to Terrestrial Animals and Plants

Terrestrial Animals

To assess risks of metrafenone to non-target birds and mammals, EECs and
acute and chronic RQs for residues on various forage categories (short
grass, tall grass, broadleaf plants/small insects, fruits/pods/large
insects, and seeds) were obtained from the Tier 1 model, T-REX v. 1.4.1
for foliar spray applications to the proposed crops.  The model assumes
initial concentrations on plant surfaces based on Kenaga predicted
maximum residues as modified by Fletcher et al. (1994), and assumes
first-order dissipation.  In this case, six applications at 0.3 lbs
a.i./A were used.  

For birds, acute RQs are derived using dose-based and dietary-based
acute toxicity values.  For mammals, acute RQs are derived using a
dose-based acute toxicity value, and chronic RQs are derived using a
dose-based chronic toxicity value (the test material was administered by
gavage) and a dietary-based chronic toxicity value using the standard
FDA laboratory rat conversion value provided in the T-REX model. 
Dietary-based RQs are calculated using EECs expressed in terms of
residue concentration for the various forage categories and toxicity
values (LC50 or NOAEC) expressed in units of dietary concentration. 
Dose-based RQs are calculated using a body weight-adjusted LD50 and
consumption-weighted equivalent dose sorted by food source and body
size.  For both birds and mammals, three weight categories (or sizes)
are considered.

Risk following acute exposure

Birds

The acute oral and dietary endpoints are both greater than the highest
concentrations tested (>2025 mg a.i./kg bw and >6070 mg a.i./kg diet,
respectively). There were no mortalities or treatment related clinical
signs of toxicity in the acute oral studies; one death in each dietary
study was observed but was not considered treatment related. Therefore,
RQ values are not reported. Further discussion will be provided in the
risk description. 

Potential risk to piscivorous birds

The potential risk to piscivorous birds considers exposure via
consumption of fish contaminated with metrafenone total residues. 
However, the acute oral and dietary endpoints are both greater than the
highest concentrations tested (>2025 mg a.i./kg bw and >6070 mg a.i./kg
diet, respectively). There were no mortalities or treatment related
clinical signs of toxicity in the acute oral studies; one death in each
dietary study was observed but was not considered treatment related.
Therefore, RQ values are not reported. Further discussion will be
provided in the risk description. 

Mammals  

The acute endpoints for mammals are both greater than the highest
concentrations tested (LD50: >2000 mg technical/kg bw, mouse; >5000 mg
form/kg bw, rat). There were no mortalities or treatment related
clinical signs of toxicity in the acute oral rat study; one death was
observed in the acute oral mouse study. Therefore, RQ values are not
reported. Further discussion will be provided in the risk description. 

Potential risk to piscivorous mammals

The potential risk to piscivorous mammals considers exposure via
consumption of fish contaminated with metrafenone total residues.
However, the mammalian acute endpoints are both greater than the highest
concentrations tested (LD50: >2000 mg technical/kg bw, mouse; >5000 mg
form/kg bw, rat). A male mouse died in the acute oral mouse study (MRID
47267522) on the technical; there were no mortalities in the acute oral
rat study (MRID 47267609) on the formulation. Therefore, RQ values are
not reported. Further discussion will be provided in the risk
description.

Terrestrial invertebrates

Metrafenone is classified as ‘practically non-toxic’ to honey bees
on an acute contact basis, based on available data for the TGAI and
formulation (24.4% a.i.). Given a non-guideline acute earthworm study
using the technical active ingredient, metrafenone is considered to be
non-lethal to earthworms up to a concentration of 1000 mg a.i./kg dry
soil. Similarly, given a non-guideline acute earthworm study using a
metrafenone metabolite, the metabolite too is considered to be
non-lethal to earthworms up to a concentration of 1000 mg/kg dry weight
of soil. In addition, given a non-guideline acute earthworm study using
a formulation, the formulation is also considered to be non-lethal to
earthworms up to a concentration of 1000 mg formulation/kg dry soil.
Additional discussion is provided in the risk description section.

Risk following chronic exposure

Birds

Utilizing the chronic endpoint (848 mg a.i./kg diet) from a 1-generation
reproduction study (MRID 47267507) conducted with mallard duck and the
T-REX model v.1.4.1, the chronic avian dietary-based RQs do not exceeded
the chronic LOC for birds for any food category.

Table 30.  Upper Bound Kenaga, Chronic Avian Dietary Based Risk
Quotients

Grapes: 0.3 lbs a.i./A; 6 Applications/season

NOAEC (ppm)	EECs and RQs1,2,3

	Short Grass	Tall Grass	Broadleaf Plants/

Small Insects	Fruits/Pods/

Seeds/

Large Insects

	EEC	RQ	EEC	RQ	EEC	RQ	EEC	RQ

181	241.01	0.28	110.46	0.13	135.57	0.16	15.06	0.02

1 Risk Quotients are calculated using the following formula: EEC / NOAEC

2 Chronic risk LOC = 1 

3 Based on avian chronic NOAEC = 848 mg a.i./kg diet



	Potential risk to piscivorous birds

The potential risk to piscivorous birds considers exposure via
consumption of fish contaminated with metrafenone total residues.  None
of the RQs exceed the chronic LOC for birds.  The following table
provides estimated RQs from KABAM using the maximum application rate and
the scenario yielding the highest aquatic EECs (New York Grapes
scenario; metrafenone total residue and high runoff scenario).  

Table 31. Chronic RQ values for Birds Consuming Fish Contaminated by
Metrafenone (based on KABAM)1

Wildlife Species	Dose Based	Dietary Based2,3

sandpipers	N/A	0.016

cranes	N/A	0.016

rails	N/A	0.018

herons	N/A	0.019

small osprey	N/A	0.022

white pelican	N/A	0.023

N/A = Not applicable

1 NY Grapes scenario (at 0.3 lbs a.i./A with 6 applications/year) 

2 Based on avian chronic NOAEC = 848 mg a.i./kg diet

3 LOC for chronic risk = 1.0



Mammals

The chronic LOC is exceeded on a dose basis for mammals in all size
classes eating short grass, for the 15 and 35 gram size classes eating
tall grass and broadleaf plants / small insects.  The chronic LOC on a
dietary basis is not exceeded for any of the food categories.  Risks to
mammals following chronic exposure will be further discussed in the risk
description section.

Table 32.  Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk
Quotients Grapes: 0.3 lbs a.i./A; 6 Applications/season

NOAEC (ppm)	EECs and RQs1,2, 3

	Short Grass	Tall Grass	Broadleaf Plants/

Small Insects	Fruits/Pods/

Seeds/

Large Insects

	EEC	RQ	EEC	RQ	EEC	RQ	EEC	RQ

500	241.01	0.48	110.46	0.22	135.57	0.27	15.06	0.03

1 Risk Quotients are calculated using the following formula: EEC / NOAEC

2 Chronic risk LOC = 1 

3 Based on mammalian chronic dietary NOAEL: 500 mg/kg diet



Table 33.  Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk
Quotients

Size Class

(grams)	Adjusted NOAEL	EECs and RQs1,2, 3



Short Grass	Tall Grass	Broadleaf Plants/

Small Insects	Fruits/Pods/

Seeds/

Large Insects	Granivore



EEC	RQ	EEC	RQ	EEC	RQ	EEC	RQ	EEC	RQ

15	78.90	229.78	2.914	105.32	1.33	129.25	1.64	14.36	0.18	3.19	0.04

35	63.84	158.81	2.49	72.79	1.14	89.33	1.40	9.93	0.16	2.21	0.03

1000	27.61	36.82	1.33	16.88	0.61	20.71	0.75	2.30	0.08	0.51	0.02

1 Risk Quotients are calculated using the following formula: EEC / NOAEC

2 Chronic risk LOC = 1 

3 Based on mammalian chronic dose-based NOAEL: 35.9 mg/kg bw/day

4 Bolded values exceed LOC



Potential risk to piscivorous mammals

The potential risk to piscivorous mammals considers exposure via
consumption of fish contaminated with metrafenone total residues.  None
of the RQs exceed the chronic LOC for mammals.  The following table
provides estimated RQs from KABAM using the maximum application rate and
the scenario yielding the highest aquatic EECs (New York Grapes
scenario; metrafenone total residue and high runoff scenario).  

Table 34. Chronic RQ Values for Mammals Consuming Fish Contaminated by
Metrafenone (based on KABAM) 1

Wildlife Species	Dose Based2,3	Dietary Based2,3

fog/water shrew	0.103	0.019

rice rat/star-nosed mole	0.125	0.018

small mink	0.159	0.025

large mink	0.176	0.025

small river otter	0.189	0.025

large river otter	0.219	0.027

1 NY Grapes scenario (at 0.3 lbs a.i./A with 6 applications/year) 

2 Based on mammalian chronic NOAEC = 35.9 mg/kg bw/day

3 LOC for chronic risk = 1.0



Terrestrial Plants

Terrestrial plant risk quotients were not calculated on account of
indeterminate endpoints generated in both the seedling emergence and
vegetative vigor studies.

Risk Description

Based on the available ecotoxicity data and predicted environmental
exposures, this ecological risk assessment supports the presumption of
risk to mammals following chronic exposure.  

Risk to Aquatic Animals and Plants

Aquatic Animals

Risk following acute exposure

Freshwater Fish and Aquatic-Phase Amphibians

Technical

The metrafenone limit of water solubility is approximately 0.2-0.5 mg/L
at 12oC. The acute rainbow trout study (MRID 47267443) indicated only 5%
mortality at levels below (0.065 mg total a.i./L) and above (0.43 and
0.82 mg total a.i./L) the solubility limit, which implies the effect may
not be dose related; 16% of fish were lethargic and 5% exhibited dark
discoloration after 96 hours only at the highest concentration tested
(0.82 mg total a.i./L). The acute bluegill sunfish study (MRID 47267442)
indicated 15% mortality, 18% lethargic fish, and 12% virtually immobile
but respiring fish at the highest concentration tested (0.87 mg total
a.i./L) after 96 hours. Given that the test solution was not
centrifuged, the amount of actual dissolved active ingredient
potentially leading to the observed effects is unknown. Nevertheless,
given these studies and assuming that metrafenone concentrations in the
environment reach the solubility limit, the effect of the technical
grade active ingredient on freshwater fish is likely to be low. However,
according to the model estimated EECs (0.00153 - 0.02 mg/L, which
includes metrafenone and total metrafenone residue scenarios), levels of
metrafenone at the solubility limit are not expected to occur in the
environment given the proposed grape use. Therefore, acute risk to
freshwater fish and aquatic-phase amphibians is not expected as a result
of metrafenone use on grapes given the results from the studies using
technical grade active ingredient.

Metabolites/Degradates

The limits of water solubility for metabolites of metrafenone were not
reported in the available studies; exceedance of solubility limit for a
given metabolite (Reg. No. 4084564) was assumed given observed
undissolved test substance in all five treatment groups of one acute
study (MRID 47267445). The acute rainbow trout study (MRID 47267444) was
a limit test with no effects noted at 99 mg total a.i./L. Another acute
rainbow trout study (MRID 47267445) indicated 80% mortality at 20.3 mg
total a.i./L and 100% mortality at 35.2 and 58.4 mg total a.i./L;
sublethal effects were observed in the three highest concentrations:
20.3 mg total a.i./L (tottering, apathy, and distended abdomen), 35.2 mg
total a.i./L (apathy and distended abdomen), and 58.4 mg total a.i./L
(tottering and distended abdomen). Given that the test solution was not
centrifuged, the amount of actual dissolved metabolite potentially
leading to the observed effects is unknown. According to the model
estimated EECs (0.00225 - 0.02 mg/L, which includes total metrafenone
residue scenarios), levels of metrafenone metabolites at the tested
levels are not expected to occur in the environment given the proposed
grape use. Therefore, the effect of metrafenone metabolites on
freshwater fish is likely to be low.

Formulations

The metrafenone limit of water solubility is approximately 0.2-0.5 mg/L
at 12oC. The acute study (MRID 47267605) using a formulation (BAS 560
00F, SF 10358, RLF 12359) indicated no effects on rainbow trout at
concentrations above the solubility limit, from 3.0 to 23.3 mg total
a.i./L. Given that the test solution was not centrifuged, the amount of
actual dissolved active ingredient is unknown. Not unlike the conclusion
drawn for the technical active ingredient, given this study and assuming
that metrafenone concentrations in the environment reach the solubility
limit, the effect of this particular formulation on freshwater fish is
likely to be low. However, according to the model estimated EECs
(0.00153 - 0.02 mg/L, which includes metrafenone and total metrafenone
residue scenarios), levels of metrafenone at the solubility limit are
not expected to occur in the environment given the proposed grape use.
Although this EU/UK formulation closely matches the U.S. formulation
(i.e., BAS 560 03F) it is still not its equivalent. Therefore, the
effect of the U.S. formulated product on freshwater fish and
aquatic-phase amphibians is not known.

Freshwater Invertebrates

Technical

The metrafenone limit of water solubility is approximately 0.2-0.5 mg/L
at 12oC. The acute study (MRID 47267437), in which the three highest
concentrations (0.22, 0.45, and 0.92 mg total a.i./L) were at or above
the solubility limit, indicated no effects on daphnia. Given that the
test solution was not centrifuged, the amount of actual dissolved active
ingredient is unknown. Nevertheless, given this study and assuming that
metrafenone concentrations in the environment reach the solubility
limit, the effect of the technical grade active ingredient on freshwater
invertebrates is likely to be low. However, according to the model
estimated EECs (0.00153 - 0.02 mg/L, which includes metrafenone and
total metrafenone residue scenarios), levels of metrafenone at the
solubility limit are not expected to occur in the environment given the
proposed grape use. Therefore, acute risk to freshwater invertebrates is
not expected as a result of metrafenone use on grapes given the results
from the studies using technical grade active ingredient.

Metabolites/Degradates

The limits of water solubility for metabolites of metrafenone were not
reported in the available studies. The acute daphnia study (MRID
47267438) with CL 375816 indicated no effects. Another acute daphnia
study (MRID 47267439) indicated 5, 55, and 65% immobility at the three
highest concentrations 23.2, 49.6, and 66.4 mg total a.i./L,
respectively, after 48 hours (test termination). Given that the test
solution was not centrifuged, the amount of actual dissolved metabolite
potentially leading to the observed effects is unknown. According to the
model estimated EECs (0.00225 - 0.02 mg/L, which includes total
metrafenone residue scenarios), levels of metrafenone metabolites at the
tested levels are not expected to occur in the environment given the
proposed grape use. Therefore, the effect of metrafenone metabolites on
freshwater invertebrates is likely to be low.

Formulations

The metrafenone limit of water solubility is approximately 0.2-0.5 mg/L
at 12oC. The acute study (MRID 47267604) using a formulation (BAS 560
00F, SF 10358, RLF 12359) indicated 65 and 90% mortality at the two
highest concentrations 6.0 and 11.6 mg total a.i./L, respectively, at 48
hours (test termination); 5% immobility was observed in the negative
control, 0.76 and 1.5 mg total a.i./L concentrations, 15% at 3.0 mg
total a.i./L, and 25% at 6.0 mg total a.i./L. Given that the test
solution was not centrifuged, the amount of actual dissolved active
ingredient potentially leading to the observed effects is unknown. Not
unlike the conclusion drawn for the technical active ingredient, given
this study and assuming that metrafenone concentrations in the
environment reach the solubility limit, the effect of this particular
formulation on freshwater invertebrates is potentially low. However,
according to the model estimated EECs (0.00153 - 0.02 mg/L, which
includes metrafenone and total metrafenone residue scenarios), levels of
metrafenone at the solubility limit are not expected to occur in the
environment given the proposed grape use. Although this EU/UK
formulation closely matches the U.S. formulation (i.e., BAS 560 03F) it
is still not its equivalent. Therefore, the effect of the U.S.
formulated product on freshwater invertebrates is not known.

Marine/Estuarine Fish

The study on the technical active ingredient (MRID 47267446) yielded an
LC50 greater than the highest concentration tested because there were no
mortalities and no sublethal effects; therefore, RQs were not reported.
Comparison of the peak aquatic EECs (0.02 mg/L, taken from the total
metrafenone residue scenario) with the highest concentration tested
(0.65 mg a.i./L uncentrifuged; 0.35 mg a.i./L centrifuged) shows that
the EECs were at least 17 times less than the highest concentrations
tested in the studies. Therefore, acute risk to marine/estuarine fish is
not expected as a result of metrafenone use on grapes.

Marine/Estuarine Invertebrates

The metrafenone limit of water solubility is approximately 0.2-0.5 mg/L
at 12oC. The acute eastern oyster study (MRID 47267440) indicated
effects on shell deposition, whereby relative to the negative control
the mean percent reduction in shell growth starting with the negative
solvent (then, 0.0522, 0.104, 0.203, 0.287 mg total a.i./L, and 0.33 mg
dissolved a.i./L) is as follows: 17.4, 13.9, 26.3, 44.3, 84.2, and 100%,
respectively. Therefore, should concentrations in the environment reach
the solubility limit, the acute risk to marine/estuarine invertebrates
may be expected. However, given that the test solution was not
centrifuged for all but the highest test concentration, the amount of
actual dissolved active ingredient potentially leading to the observed
effects is unknown. Meaning that interpretation of effects from total
concentrations cited here may underestimate potential risk. Similarly,
the acute saltwater mysid study (MRID 47267441) indicated a dose related
effect, this time on mortality at the four out of five highest
concentrations: 5% at 0.129 and 0.240 mg total a.i./L, 15% at 0.416 mg
total a.i./L, and 95% at 0.663 mg total a.i./L; in addition, erratic
swimming was observed in the two highest concentrations by test
termination. Despite the dose response, without centrifugation, the
amount of chemical that is freely dissolved and bioavailable cannot be
determined and, again, interpretation of effects from total
concentrations cited here may underestimate potential risk. However,
according to the model estimated EECs (0.00153 - 0.02 mg/L, which
includes metrafenone and total metrafenone residue scenarios), levels of
metrafenone at the solubility limit are not expected to occur in the
environment given the proposed grape use. Given these studies and
assuming that metrafenone concentrations in the environment are not
likely to reach the solubility limit, the acute risk to marine/estuarine
invertebrates is not expected.

Risk following chronic exposure

Freshwater Fish and Aquatic-Phase Amphibians

a.i./L (p≤0.05).  Post-hatch survival averaged 96% at the negative
control through 0.118 mg total a.i./L levels, and 87, 86, and 11% at the
0.227, 0.421, and 0.839 mg total ai/L levels, respectively.  Therefore,
a dose response is evident and implies that should concentrations in the
environment reach the solubility limit, the chronic risk to freshwater
fish may be expected. No clinical signs of toxicity were observed during
the study in any treatment group.  Fish length was significantly reduced
relative to the average negative control length at the two highest
concentrations 0.421 and 0.839 mg total ai/L and wet and dry weight were
significantly lower than the negative control weights at the highest
concentration (0.839 mg total a.i./L level); however, significant impact
on survival occurred at these levels. Given that the test solution was
not centrifuged, the amount of actual dissolved active ingredient
potentially leading to the observed effects is unknown. For example, the
NOAEC value is low (0.118 mg total a.i./L) even though the measured
concentration includes dissolved and undissolved substance, but had the
sample been centrifuged – including the dissolved compound only - the
value would likely be lower. Therefore, conclusions drawn from these
data would lead to an underestimation of potential risk. According to
the model estimated EECs (0.00075 - 0.017 mg/L, which includes
metrafenone and total metrafenone residue scenarios), levels of
metrafenone at the solubility limit are not expected to occur in the
environment given the proposed grape use. Assuming that metrafenone
concentrations in the environment are not likely to reach the solubility
limit or the concentrations used in this study, the chronic risk to
freshwater fish and aquatic-phase amphibians is not expected.

Freshwater Invertebrates

No acceptable chronic ecotoxicity studies on freshwater invertebrates
are available. Chronic risk to freshwater invertebrates cannot be
precluded.  

Marine/Estuarine Fish

No chronic ecotoxicity studies on estuarine/marine fish have been
submitted to the Agency for review.  Chronic risk to estuarine/marine
fish cannot be precluded.

Marine/Estuarine Invertebrates

The chronic aquatic LOC was not exceeded for the proposed use of
metrafenone for the technical active ingredient (MRID 47267448) tested
on the marine/estuarine invertebrate (saltwater mysid); no data is
available for metabolites or formulation studies on marine/estuarine
invertebrates. Although reproduction (number of offspring per female per
reproductive day) was the (most sensitive) affected endpoint in this
study, yielding a definitive endpoint, the RQ calculations indicate that
chronic risk to marine/estuarine invertebrates is not expected as a
result of metrafenone use.

Aquatic Plants

For all aquatic plant studies, dissolved or soluble concentrations
(i.e., post-centrifugation) of test material were not determined.
Without centrifugation, the amount of chemical that is freely dissolved
and bioavailable cannot be determined. This is especially a problem as
some of the testing concentrations were conducted above the solubility
limit of the technical grade active ingredient (MRID 47267511, 47267512,
47267513, 47267514, 47267515, technical; MRID 47267607, formulation). In
addition, the metabolite solubility limit is unknown which leads to
uncertainty in interpreting the measured concentrations in the
metabolite studies (MRID 47267516, 47267517).  The lowest concentration
tested among the vascular plants (MRID 47267511, L. gibba: 0.057 mg
total a.i./L; or, 0.033 mg a.i./L assuming a 42% reduction after
hypothetical centrifugation) and non-vascular plants (MRID 47267513, S.
costatum: 0.0509 mg total a.i./L; or 0.0295 mg a.i./L) is higher than
the highest peak aquatic EEC value of 0.02 mg/L (assuming the total
metrafenone residue scenario). Therefore, had valid endpoints (i.e.,
those based on dissolved concentrations) been determined using these
studies, they would likely be greater than the highest model predicted
concentration in the environment, which implies that risk to vascular
and non-vascular species is not expected as a result of metrafenone use
on grapes. Although the EU/UK formulation used in one of the studies
closely matches the U.S. formulation (i.e., BAS 560 03F) it is still not
its equivalent. Therefore, the effect of the U.S. formulated product on
vascular and non-vascular aquatic plants is not known.

Risk to Terrestrial Animals and Plants

Terrestrial Animals

Risk following acute exposure

Birds

The acute oral and dietary endpoints are both greater than the highest
concentrations tested (>2025 mg a.i./kg bw and >6070 mg a.i./kg diet,
respectively). There were no mortalities or treatment related clinical
signs of toxicity in the acute oral studies; one death in each dietary
study was observed but was not considered treatment related. As a
result, RQ values were not reported. Toxicity characterization implies
that the technical is practically non-toxic. In addition, the highest
concentration tested for the oral studies (2025 mg a.i./kg bw) is 7
times higher than the highest dose-based EEC (274.49 mg/kg) calculated
from T-REX; meanwhile, the highest concentration tested for the dietary
studies (6070 mg a.i./kg diet) is 25 times higher than the highest
dietary-based EEC (241.01 mg/kg). Therefore, given that comparison,
acute risk to birds is not expected as a result of metrafenone use.

Potential risk to piscivorous birds

Several characteristics of metrafenone indicate that it has the
potential to accumulate in tissues of aquatic organisms.  The log of the
n-octanol/water partition coefficient for metrafenone is 4.3 (at 25oC,
pH 4). The lipid normalized BCF was determined to be between 140 and 530
(see MRID 47267450).

As stated in the risk estimation section, the acute oral and dietary
endpoints are both greater than the highest concentrations tested (>2025
mg a.i./kg bw and >6070 mg a.i./kg diet, respectively). There were no
mortalities or treatment related clinical signs of toxicity in the acute
oral studies; one death in each dietary study was observed but was not
considered treatment related. As a result, RQ values were not reported.
The highest concentration tested for the oral studies (2025 mg a.i./kg
bw) is 147 times higher than the highest dose-based EEC (13.73 mg/kg
bw/day) calculated from KABAM for birds consuming fish contaminated by
metrafenone total residues; meanwhile, the highest concentration tested
for the dietary studies (6070 mg a.i./kg diet) is 310 times higher than
the highest dietary-based EEC (19.59 mg/kg). Therefore, given that
comparison, acute risk to piscivorous birds is not expected due to
consumption of fish contaminated with metrafenone.

Mammals

There were no mortalities in the acute oral rat study (MRID 47267609) on
the formulation; one death was observed in the acute oral mouse study
(MRID 47267522) on the technical active ingredient.  Although the EU/UK
formulation used in the formulation study closely matches the U.S.
formulation (i.e., BAS 560 03F) it is still not its equivalent.
Therefore, the effect of the U.S. formulated product on mammals is not
known. 

The acute endpoints for mammals are both greater than the highest
concentrations tested (LD50: >2000 mg technical/kg bw, mouse; >5000 mg
form/kg bw, rat). Therefore, RQ values were not reported. In the mouse
study, only 3 individuals/sex were tested with mortality in 1/6 animals
(17%).  With a larger test sample, the LD50 could be approached. The
toxicity classification implies that the technical is practically
non-toxic to mice. In addition, the highest concentration tested for the
oral study (2000 mg a.i./kg bw) is 9 times higher than the highest
dose-based EEC (229.78 mg/kg) calculated from T-REX. Therefore, given
that comparison, acute risk to mammals is not expected as a result of
metrafenone use.

Potential risk to piscivorous mammals

Risk to piscivorous mammals via consumption of fish contaminated with
metrafenone was assessed because metrafenone has the potential to
accumulate in tissues of aquatic organisms. 

As stated in the risk estimation section, there were no mortalities in
the acute oral rat study (MRID 47267609) on the formulation and there
was only one death in the acute oral mouse study (MRID 47267522) on the
technical. Although the EU/UK formulation used in the formulation study
matches the U.S. formulation (i.e., BAS 560 03F) it is still not its
equivalent. Therefore, the effect of the U.S. formulated product on
mammals is not known.

The highest concentration tested for the oral studies (2000 mg a.i./kg
bw) is 257 times higher than the highest dose-based EEC (7.795 mg/kg
bw/day) calculated from KABAM for mammals consuming fish contaminated by
metrafenone total residues. Therefore, given that comparison, acute risk
to piscivorous mammals is not expected due to consumption of fish
contaminated with metrafenone.

Terrestrial invertebrates

The 48-hour contact LD50 is >24.4 μg a.i./bee [>100 μg form/bee] with
a NOAEC of <24.4 μg a.i./bee and a LOAEC of 24.4 µg a.i./bee based on
mortality.  Based on this toxicity data, metrafenone is classified as
‘practically non-toxic’ to honeybees on an acute contact basis. 
Thus, risk to honeybees is not expected as a result of direct contact
with metrafenone.  Similarly, the non-guideline earthworm studies
consider metrafenone, its degradate, and a formulation to be non-lethal
to earthworms up to a concentration of 1000 mg a.i./kg dry soil, 1000
mg/kg dry weight of soil, and 1000 mg formulation/kg dry soil,
respectively. E. fetida is found in topsoil at depths of approximately
5-20cm. Given a soil depth of 20 cm and assuming a maximum application
rate per season (1.8 lbs a.i./A, which assumes a hypothetical maximum
active ingredient loading rate since the seasonal rate would not be
applied all at once and likely degrade if applied in the recommended 6
applications of at most 0.3 lbs a.i./A), the EEC is much lower (0.77
mg/kg soil) than the concentrations generated in these studies. At
shallower depths (5 cm), the EEC is higher (3.08 mg/kg soil), but still
lower than the study concentration (1000 mg a.i./kg soil). Therefore,
risk to earthworms is not expected as a result of metrafenone use on
grapes. Although the EU/UK formulation used in the formulation studies
for the bee and earthworm matches the U.S. formulation (i.e., BAS 560
03F) it is still not its equivalent. Therefore, the effect of the U.S.
formulated product on bees (and earthworms) is not known.

Risk following chronic exposure

Birds

The chronic avian dietary-based RQ does not exceed the chronic LOC for
birds for any food catogory. The study (MRID 47267507) was done on
mallard duck using the technical grade and yielded a definite endpoint
based on egg production (eggs laid per female per week) and hatchability
(% dead-in-shell of fertile eggs). Due to the fact that the RQ is only
based on one bird species, there is an uncertainty associated with the
estimated risk for all avian species. Nevertheless, given that LOCs were
not exceeded, chronic risk to birds is not expected as a result of
metrafenone use on grapes.

Potential risk to piscivorous birds

As previously stated, risk to piscivorous birds via consumption of fish
contaminated with metrafenone was assessed because metrafenone has the
potential to accumulate in tissues of aquatic organisms.  As stated in
the risk estimation section, none of the RQs exceed the chronic LOC for
birds.   Therefore, chronic risk to piscivorous birds is not expected
due to consumption of fish contaminated with metrafenone total residues.

Mammals

The chronic LOC is exceeded on a dose basis for mammals in all size
classes eating short grass, for the 15 and 35 gram size classes eating
tall grass and broadleaf plants / small insects.  The chronic LOC on a
dietary basis is not exceeded for any of the food categories.  The study
(MRID 46415729, 46415728) was done on the rat using the technical grade
and yielded a definite endpoint based on decreased body weights and body
weight gain in F1 males as well as body weights in F1 and F2 females.
Due to the fact that the RQ is only based on one mammalian species,
there is an uncertainty associated with the estimated risk for all
mammals. Nevertheless, given the LOC exceedance chronic risk to mammals
is expected as a result of metrafenone use. To reduce chronic risk to
mammals, several components of the application protocol would have to
change. For example, in order to have no chronic LOC exceedances (i.e.,
all RQs < 1) for mammals, the minimum single application rate (0.2 lbs
a.i./A) would have to be cut by 25% (i.e., to 0.15 lbs a.i./A) yet
considered the maximum instead, the application interval would have to
nearly double (from 14 days up to 26 days), and the maximum allowed
number of applications would have to be cut from 6 to 5. Alternatively,
in order to have no chronic LOC exceedances for mammals, the minimum
single application rate (0.2 lbs a.i./A) can still be applied yet
considered the maximum instead, but the application interval would have
to nearly double (from 14 days up to 26 days), and the maximum number of
applications would have to be cut by 50% (i.e., from 6 to 3).
Furthermore, in order to have no chronic LOC exceedances in nearly all
cases for mammals –the one exception being an exceedance for the 15g
size glass consuming short grass where the calculated RQ is 1.02 – the
minimum single application rate (0.2 lbs a.i./A) would be changed to the
maximum single application rate and the application interval (14 days)
could remain as currently prescribed by the label, but the maximum
number of applications would have to be reduced from 6 to 2.

Potential risk to piscivorous mammals

As previously stated, risk to piscivorous mammals via consumption of
fish contaminated with metrafenone was assessed because metrafenone has
the potential to accumulate in tissues of aquatic organisms.  As stated
in the risk estimation section, none of the RQs exceed the chronic LOC
for mammals.   Therefore, chronic risk to piscivorous mammals is not
expected due to consumption of fish contaminated with metrafenone.

Terrestrial Plants

As stated in the risk estimation section, terrestrial plant risk
quotients were not calculated on account of indeterminate endpoints
generated in both the seedling emergence and vegetative vigor studies.
The lower application rates in the studies (0.091 and 0.288 lbs a.i./A
for the seedling emergence study; and, 0.091 and 0.285 lbs a.i./A for
all but soybean [0.099 and 0.283 lbs a.i./A] for the vegetative vigor
study) relative to the label application rate (0.3 lbs a.i./A) leads to
uncertainty in the risk characterization especially as effects were
noted. However, the effects in both studies are not considered
significant and the NOAEC and EC05 are undefined (seedling emergence:
NOAEC 0.288 lbs a.i./A; EC05, EC25 > 0.288 lbs a.i./A; vegetative vigor:
NOAEC 0.285 lbs a.i./A; EC05, EC25 > 0.285 lbs a.i./A). Consequently,
the most sensitive monocot and dicot species could not be determined
from either study. Hypothetically, had the NOAEC been determined to be
0.091 lbs a.i./A (the lower concentration tested) in both the vegetative
vigor and seedling emergence studies and given the maximum single
application rate (0.3 lbs a.i./A), the risk would not have triggered
concern for either the dicot or monocot species. In addition, the EECs
based on the maximum seasonal application rate (1.8 lbs a.i./A) range
from 0.018 – 0.198 lbs a.i./A, which are below the concentrations
tested in these studies. Since effects were not significant at the test
concentrations, which are higher than the calculated EECs, risk to
terrestrial plants is not expected as a result of use of the EU/UK
formulation. Both studies were conducted on the EU/UK formulation (BAS
560 00F); therefore, uncertainty exists in determining risk to the U.S.
formulation (BAS 560 03F). Tier II tests are requested to better define
the toxicity endpoints, to have a study available that is based on the
U.S. formulation, and, subsequently, reduce uncertainty in risk
characterization.

Review of Incident Data

With the proposed use on grapes, metrafenone will be applied in the
United States for the first time.  Therefore, no incident data are
available at this time. 

Endocrine Effects

As required under FFDCA section 408(p), EPA has developed the Endocrine
Disruptor Screening Program (EDSP) to determine whether certain
substances (including pesticide active and other ingredients) may have
an effect in humans or wildlife similar to an effect produced by a
“naturally occurring estrogen, or other such endocrine effects as the
Administrator may designate.”  The EDSP employs a two-tiered approach
to making the statutorily required determinations. Tier 1 consists of a
battery of 11 screening assays to identify the potential of a chemical
substance to interact with the estrogen, androgen, or thyroid (E, A, or
T) hormonal systems.  Chemicals that go through Tier 1 screening and are
found to have the potential to interact with E, A, or T hormonal systems
will proceed to the next stage of the EDSP where EPA will determine
which, if any, of the Tier 2 tests are necessary based on the available
data. Tier 2 testing is designed to identify any adverse endocrine
related effects caused by the substance, and establish a dose-response
relationship between the dose and the E, A, or T effect.

Between October 2009 and February 2010, EPA is issuing test orders/data
call-ins for the first group of 67 chemicals, which contains 58
pesticide active ingredients and 9 inert ingredients.  This list of
chemicals was selected based on the potential for human exposure through
pathways such as food and water, residential activity, and certain
post-application agricultural scenarios.  This list should not be
construed as a list of known or likely endocrine disruptors.

Metrafenone is not among the group of 58 pesticide active ingredients on
the initial list to be screened under the EDSP.  Under FFDCA sec. 408(p)
the Agency must screen all pesticide chemicals.  Accordingly, EPA
anticipates issuing future EDSP test orders/data call-ins for all
pesticide active ingredients. 

For further information on the status of the EDSP, the policies and
procedures, the list of 67 chemicals, the test guidelines and the Tier 1
screening battery, please visit our website:  http://www.epa.gov/endo/.

Federally Threatened and Endangered (Listed) Species

Section 7 of the Endangered Species Act, 16 U.S.C. Section 1536(a)(2),
requires all federal agencies to consult with the National Marine
Fisheries Service (NMFS) for marine and anadromous listed species, or
the United States Fish and Wildlife Services (FWS) for listed wildlife
and freshwater organisms, if they are proposing an "action" that may
affect listed species or their designated habitat.  Each federal agency
is required under the Act to insure that any action they authorize,
fund, or carry out is not likely to jeopardize the continued existence
of a listed species or result in the destruction or adverse modification
of designated critical habitat.  To jeopardize the continued existence
of a listed species means "to engage in an action that reasonably would
be expected, directly or indirectly, to reduce appreciably the
likelihood of both the survival and recovery of a listed species in the
wild by reducing the reproduction, numbers, or distribution of the
species" (50 C.F.R. § 402.02).

To facilitate compliance with the requirements of the Endangered Species
Act (subsection (a)(2)), the Office of Pesticide Programs has
established procedures to evaluate whether a proposed registration
action may directly or indirectly reduce appreciably the likelihood of
both the survival and recovery of a listed species in the wild by
reducing the reproduction, numbers, or distribution of any listed
species (USEPA, 2004).  After the Agency’s screening level risk
assessment is conducted, if any of the Agency’s listed species LOCs
are exceeded for either direct or indirect effects, an analysis is
conducted to determine if any listed or candidate species may co-occur
in the area of the proposed pesticide use or areas downstream or
downwind that could be contaminated from drift or runoff/erosion.  If
listed or candidate species may be present in the proposed action areas,
further biological assessment is undertaken.  The extent to which listed
species may be at risk then determines the need for the development of a
more comprehensive consultation package as required by the Endangered
Species Act.

Both acute endangered species and chronic risk LOCs are considered in
the screening-level risk assessment of pesticide risks to listed
species. Endangered species acute LOCs are a fraction of the
non-endangered species LOCs or, in the case of endangered plants, RQs
are derived using lower toxicity endpoints than non-endangered plants. 
Therefore, concerns regarding listed species within a taxonomic group
are triggered in exposure situations where restricted use or acute risk
LOCs are triggered for the same taxonomic group.  The risk assessment
also includes an evaluation of the potential probability of individual
effects for exposures that may occur at the established endangered
species LOC both in the risk characterization and the endangered species
sections.  This probability is calculated using the established
dose/response relationship and assumes a probit (probability unit)
dose/response relationship.  

Action Area

For listed species assessments, the action area is considered to be the
area affected directly or indirectly by the Federal action and not
merely the immediate area where metrafenone is applied.  At the initial
Level 1 screening assessment, broadly described taxonomic groups are
considered, and thus, conservatively assumes that listed species within
those broad groups are co-located with the pesticide treatment area. 
This means that terrestrial plants and wildlife are assumed to be
located on or adjacent to the treated site and aquatic organisms are
assumed to be located in a surface water body adjacent to the treated
site.  The assessment also assumes that listed species are located
within the area of highest exposure to the pesticide, and that exposure
will decrease with increasing distance from the treated area.  

If the assumptions associated with the screening-level action area
result in RQs that are below the listed species LOCs, a "no effect"
determination conclusion is made with respect to listed species in that
taxa, and no further refinement of the action area is necessary. 
Furthermore, RQs below the listed species LOCs for a given taxonomic
group indicate no concern for indirect effects upon listed species that
depend upon the taxonomic group covered by the RQ as a resource. 
However, in situations where the screening assumptions lead to RQs in
excess of the listed species LOCs for a given taxonomic group, a
potential for a "may affect" conclusion exists and may be associated
with direct effects on listed species belonging to that taxonomic group
or may extend to indirect effects upon listed species that depend upon
that taxonomic group as a resource.  In such cases, additional
information on the biology of listed species, the locations of these
species, and the locations of use sites could be considered along with
available information on the fate and transport properties of the
pesticide to determine the extent to which screening assumptions
regarding an action area apply to a particular listed organism.  These
subsequent refinement steps could consider how this information would
impact the action area for a particular listed organism and may
potentially include areas of exposure that are downwind and downstream
of the pesticide use site.

Taxonomic Groups Potentially at Risk

The preliminary risk assessment for endangered species indicates that
the proposed use and application rate for metrafenone either exceeds the
Endangered Species LOCs for the following taxonomic groups (underlined
[chronic exposure to mammals]) or those for which risk cannot be
precluded (also underlined [chronic exposure to freshwater fish and
invertebrates, acute exposure to marine/estuarine invertebrate, chronic
exposure to marine/estuarine fish]).

Chronic exposure to mammals

Data was not submitted or was deemed invalid for the following: chronic
exposure to freshwater invertebrates and marine/estuarine fish. A
passerine bird study is also not available at this time. Lack of data
does not preclude risk.

Data was supplemental, but inadequate for risk quotient calculations
which would have helped to determine risk to endangered species for the
following: acute exposure to freshwater fish and invertebrates, acute
exposure to marine/estuarine invertebrates, chronic exposure to
freshwater fish; and, aquatic plants. Therefore, there is uncertainty in
determining risk to these taxonomic groups. However, the total
concentration based endpoint (EC50: 0.22 mg total a.i./L) for the acute
marine/estuarine invertebrate (eastern oyster) study (MRID 47267440)
with an effect on shell deposition is 11x greater than the highest
estimated EEC (0.02 mg/L), hence risk to federally listed
marine/estuarine invertebrates cannot be precluded. The total
concentration based endpoint (NOAEC: 0.118 mg total a.i./L) for the
chronic freshwater fish (fathead minnow) study (MRID 47267449) with an
effect on post-hatch survival is approximately 7x greater than the
highest estimated EEC (0.016 mg/L), hence risk to federally listed
freshwater fish cannot be precluded. Applying similar calculations to
the acute freshwater fish and invertebrate data as well as data for
aquatic plants assumes low risk to federally listed species.

Data was acceptable, but inadequate for risk quotient calculations for
the following: acute exposure to marine/estuarine fish. Therefore, there
is uncertainty in determining risk to these taxonomic groups. The
highest concentration tested in the acute marine/estuarine fish
(sheepshead minnow) study (MRID 47267446) was 0.35 mg dissolved a.i./L
which is 17.5x greater than the highest estimated EEC (0.02 mg/L) but
there were no effects on mortality or sublethal effects, hence risk to
federally listed marine/estuarine fish is assumed to be low. Acceptable
data for acute exposure to birds yields non-definitive endpoints with no
effects; therefore, acute risk to federally listed birds is expected to
be low. For similar reasons, acute risk to federally listed piscivorous
birds, mammals, and piscivorous mammals is also expected to be low.

Concerns For Federally Listed as Endangered and/or Threatened Species

Table 35.  Listed Species Risks Associated with Direct or Indirect
Effects from Metrafenone use on Grapes at the Maximum Proposed
Application Rate (0.3 lbs a.i./A, Assuming 6 Applications/Year)  TC
"Table IB-1.  Listed species risks associated with direct or indirect
effects due to applications of propazine on sorghum" \f C \l "1"  

Listed Taxon	Direct Effects	Indirect Effects

Terrestrial and semi-aquatic plants - monocots	No	Yes from effects to
mammals

Terrestrial and semi-aquatic plants – dicots	No	Yes from effects to
mammals

Terrestrial invertebrates	No	Yes from effects to mammals

Birds	No	Yes from effects to mammals, FW fish, FW inverts, M/E fish, 
M/E inverts (mollusks)

Terrestrial-phase amphibians	No	Yes from effects to mammals

Reptiles	No	Yes from effects to mammals, FW fish, FW inverts, M/E fish, 
M/E inverts (mollusks)

Mammals	Yes for chronic1	Yes from effects to mammals, FW fish, FW
inverts, M/E fish,  M/E inverts (mollusks)

  Aquatic non-vascular plants	No	Yes from effects to mammals, FW fish,
FW inverts, M/E fish,  M/E inverts (mollusks)

Aquatic vascular plants	No	Yes from effects to mammals, FW fish, FW
inverts, M/E fish,  M/E inverts (mollusks)

Freshwater (FW) fish	Yes for chronic2	Yes from effects to mammals, FW
fish, FW inverts, M/E fish,  M/E inverts (mollusks)

Aquatic-phase amphibians	Yes for chronic3	Yes from effects to mammals,
FW fish, FW inverts, M/E fish,  M/E inverts (mollusks)

Freshwater (FW) invertebrates	Yes for chronic4	Yes from effects to
mammals, FW fish, FW inverts, M/E fish,  M/E inverts (mollusks)

Marine/estuarine (M/E) fish	Yes for chronic4	Yes from effects to
mammals, FW fish, FW inverts, M/E fish,  M/E inverts (mollusks)

Marine/estuarine (M/E) invertebrates (mollusk)	Yes for acute5, 

No for chronic6 	Yes from effects to mammals, FW fish, FW inverts, M/E
fish,  M/E inverts (mollusks)

1 The chronic LOC is exceeded on a dose basis for mammals in all size
classes eating short grass, for the 15 and 35 gram size classes eating
tall grass and broadleaf plants / small insects.  The chronic LOC on a
dietary basis is not exceeded for any of the food categories. 

2 The total concentration based endpoint (NOAEC: 0.118 mg total a.i./L)
for the chronic freshwater fish (fathead minnow) study (MRID 47267449)
with an effect on post-hatch survival is approximately 7x greater than
the highest estimated EEC (0.016 mg/L), hence risk to federally listed
freshwater fish cannot be precluded.

3 Results from freshwater fish used as surrogate for assessing risk to
aquatic-phase amphibians

4 Studies not submitted or invalid for which risk cannot be precluded.

5 Mollusk (Eastern oyster); 6 Saltwater mysid



Discussion of risk quotients

The Agency’s LOCs for mammals (chronic) are exceeded for the use of
metrafenone on grapes as outlined in previous sections. The risk to the
remaining federally listed taxonomic groups (freshwater fish and
invertebrates (chronic), marine/estuarine invertebrate (acute),
marine/estuarine fish (chronic)) cannot be precluded on the basis of
toxicity data and estimated exposures. Should estimated exposure levels
occur in proximity to listed resources, the available screening level
information suggests a potential concern for direct effects on listed
species within the taxonomic groups listed above associated with the
uses of metrafenone as described in Section III.A.  The registrant must
provide information on the proximity of federally listed mammals,
freshwater fish and invertebrates, as well as marine/estuarine fish and
invertebrates to the metrafenone use sites. This requirement may be
satisfied in one of three ways: 1) having membership in the FIFRA
Endangered Species Task Force (Pesticide Registration [PR] Notice
2000-2); 2) citing FIFRA Endangered Species Task Force data; or 3)
independently producing these data, provided the information is of
sufficient quality to meet FIFRA requirements. The information will be
used by the OPP Endangered Species Protection Program to develop
recommendations to avoid adverse effects to listed species.

Probit dose response relationship

The Agency uses the probit dose response relationship as a tool for
providing additional information on the potential for acute direct
effects to aquatic and terrestrial animals (U.S. EPA, 2004).  As part of
the risk characterization, an interpretation of acute RQ for listed
species is discussed.  This interpretation is presented in terms of the
chance of an individual event (i.e., mortality or immobilization) should
exposure at the EEC actually occur for a species with sensitivity to
metrafenone on par with the acute toxicity endpoint selected for RQ
calculation.  To accomplish this interpretation, the Agency uses the
slope of the dose response relationship available from the toxicity
study used to establish the acute toxicity measures of effect for each
taxonomic group that is relevant to this assessment.  The individual
effects probability associated with the acute RQ is based on the mean
estimate of the slope and an assumption of a probit dose response
relationship.  In addition to a single effects probability estimate
based on the mean, upper and lower estimates of the effects probability
are also provided to account for variance in the slope, if available. 
The upper and lower bounds of the effects probability are based on
available information on the 95% confidence interval of the slope. 
Studies with good probit fit characteristics (i.e., statistically
appropriate for the data set) are associated with a high degree of
confidence.  Conversely, a low degree of confidence is associated with
data from studies that do not statistically support a probit dose
response relationship.  In addition, confidence in the data set may be
reduced by high variance in the slope (i.e., large 95% confidence
intervals), despite good probit fit characteristics.  In the event that
dose response information is not available to estimate a slope, a
default slope assumption of 4.5 (95% C.I.: 2 to 9) (Urban and Cook,
1986) is used.  

Individual effect probabilities are calculated based on an Excel
spreadsheet tool IEC v1.1 (Individual Effect Chance Model Version 1.1)
developed by the U.S. EPA, OPP, Environmental Fate and Effects Division
(June 22, 2004).  The model allows for such calculations by entering the
mean slope estimate (and the 95% confidence bounds of that estimate) as
the slope parameter for the spreadsheet.  In addition, the acute RQ is
entered as the desired threshold. However, on account of either
non-definitive acute endpoints or endpoints based on total
concentrations (dissolved + undissolved test compound) instead of
dissolved concentrations only, the acute studies which would otherwise
be useful for calculating individual effect probabilities cannot be
used.

Data related to under-represented taxa

Effects data on under-represented taxonomic groups were not submitted by
the Registrant. Effects data from other analyzed sources were either not
obtained (ECOTOX Database, PAN Database) or were not available (publicly
available ECOTOX) for this screening risk assessment. 

Implications of sublethal effects

For the sublethal effects discussed below, it is noted that EFED cannot
quantitatively assess the relationship between any of the observed
sublethal effects and potential reduction in survival or reproductive
impairment at this time.  Instead, the concentrations at which sublethal
effects were observed in laboratory studies are discussed in relation to
the concentrations at which mortality and/or reproductive effects were
observed in the same laboratory studies and compared to aquatic and
terrestrial EECs and assessed as to whether or not they may be expected
under field conditions. The EU/UK formulation (BAS 560 00F), which is
used in all formulation studies, closely matches the U.S. formulation
(i.e., BAS 560 03F) but is not equivalent. The formulation studies are
cited and evaluated in this assessment. However, at this time, the
effect of the U.S. formulation on any given taxa is not known.

Acute Studies

Aquatic Organisms

The greatest amount of uncertainty in the assessment stems from aquatic
studies which were largely based on total concentrations (both dissolved
and undissolved) instead of the soluble concentrations of the test
compound.  

Given the freshwater fish acute toxicity data the bluegill sunfish
(Lepomis macrochirus) appears to be more sensitive than the rainbow
trout (Oncorhynchus mykiss) on the technical grade active ingredient.
Sublethal effects (lethargic and motionless fish) were observed in the
bluegill study at the highest concentration tested (0.87 mg total
a.i./L) which is greater than the peak aquatic EEC (0.02 mg a.i./L).
Similarly, the lowest tested metabolite concentration at which sublethal
effects were observed for the trout study was at 20.3 mg total a.i./L,
which is also below the total metrafenone residue peak EEC. The numbers
imply that sublethal effects on freshwater fish due to the parent or
metabolite of metrafenone are not expected under field conditions. 

The freshwater invertebrate study on daphnia using the technical grade
active ingredient and a metabolite (CL 375816) indicated no effects. On
the other hand, another metabolite study (using CL 4084564) indicated
immobility at 23.2 mg total a.i./L, which is also above peak EEC levels.
The numbers imply that sublethal effects on freshwater invertebrates due
to the parent or metabolite of metrafenone are not expected under field
conditions. 

No effects were observed for the marine/estuarine fish technical grade
active ingredient study. Erratic swimming was observed in the saltwater
mysid (Americamysis bahia) study at 0.416 mg total a.i./L and mortality
at 0.129 mg total a.i./L, which are again above peak EEC levels.
Therefore, the values imply that sublethal effects on marine/estuarine
fish and invertebrates due to the parent metrafenone are not expected
under field conditions. 

Terrestrial Organisms

The acute oral avian studies indicated no effects; the acute dietary
avian studies indicated a significant change in body weight that was not
associated with a dose-response pattern. In the mammal study on the
technical grade active ingredient, only mortality was reported. 
Therefore, no implications with sublethal effects can be made. 

Chronic Studies

Aquatic Organisms

The freshwater fish chronic toxicity endpoint (NOAEC 0.118 mg total
a.i./L) based on post-hatch is greater than the highest chronic EEC
(0.017 mg a.i./L). Similarly, the marine/estuarine invertebrate chronic
toxicity endpoint (NOAEC 0.022 mg a.i./L) based on reproduction is
greater than the highest chronic EEC (0.018 mg a.i./L). The values imply
that chronic effects on freshwater fish and marine/estuarine
invertebrates are not expected under field conditions. 

No acceptable chronic freshwater invertebrate studies are available. No
chronic marine/estuarine fish studies were submitted for review. 

Terrestrial Organisms

The avian chronic toxicity endpoint (NOAEC 848 mg a.i./kg diet) based on
egg production and hatchability did not yield chronic LOC exceedances.
The most sensitive chronic mammalian endpoint (NOAEL 35.9 mg/kg bw/day)
based on decreased body weights and body weight gain in F1 males as well
as body weights in F1 and F2 females, however, exceeded the chronic LOC,
which implies that sublethal chronic effects on mammals are expected
under field conditions. 

Indirect Effects Analysis

In conducting a screen for indirect effects, direct effects LOCs for
each taxonomic group are used to make inferences concerning the
potential for indirect effects upon listed species.  The listed species
rely upon non-listed organisms in these taxonomic groups as resources
critical to their life cycle.  Pesticide-use scenarios, resulting in RQs
that are below all direct effect listed species LOCs for all taxonomic
groups assessed are considered of no concern for risks to listed species
either by direct or indirect effects.   However, there may be situations
where a taxonomic group is not quantitatively assessed (e.g.,
terrestrial insects), but other lines of evidence are sufficiently
supportive of concerns for indirect effects on listed organisms that are
dependant upon that taxonomic group.

Where One or More Animal Taxonomic Group RQs Exceed the LOC for Listed
Species 

The Level I screening indirect effects analysis documents those types of
dependencies upon non-listed organisms that could be important sources
of indirect effects to listed organisms should effective levels of the
pesticide coincide with locations of listed species and the biologically
based resources upon which they depend.  In cases where screening-level
acute RQs for a given animal group equal or exceed the endangered
species acute LOC, the Agency uses the dose response relationship from
the toxicity study used for calculating the RQ to estimate the
probability of acute effects associated with an exposure equivalent to
the EEC.  This information serves as a guide to establish the need for
and extent of additional analysis that may be performed using
Services-provided “species profiles” as well as evaluations of the
geographical and temporal nature of the exposure to ascertain if a not
likely to adversely affect determination can be made.  The degree to
which additional analyses are performed is commensurate with the
predicted probability of adverse effects from the comparison of dose
response information with the EECs.  The greater the probability that
exposures will produce effects on a taxa, the greater the concern for
potential indirect effects for listed species dependant upon that taxa,
and therefore, the more intensive the analysis on the potential listed
species of concern, their locations relative to the use site, and
information regarding the use scenario (e.g., timing, frequency, and
geographical extent of pesticide application).  The greatest concerns
would exist when exposure is associated with a risk higher than the
effects probability associated with the non-endangered LOC for a
pesticide with an average slope of 4.5.  

For metrafenone, risks to listed species are predicted within the
following taxa: mammals, freshwater fish and invertebrates,
marine/estuarine invertebrates, and marine/estuarine fish. Changes in
fish and aquatic invertebrate populations could indirectly affect other
fish and aquatic invertebrates, aquatic plants, birds, reptiles and
mammals.  The chronic endpoint for mammalian species is based on
decreases in body weight and/or body weight gain in both the parents and
pups.  If body size following chronic metrafenone exposure is reduced to
the extent that it has an impact on mammalian populations, reduction in
mammalian populations that are used as a resource for listed species may
be of concern.  Given that the chronic LOC is exceeded for mammals,
indirect effects to listed species (e.g., other mammals, birds,
amphibians, reptiles, plants (pollination) and terrestrial
invertebrates) that rely on mammals as a primary food source, or on
mammal burrows for shelter or breeding habitat, may be of concern. 

Critical Habitat

In the evaluation of pesticide effects on designated critical habitat,
consideration is given to the physical and biological features
(constituent elements) of a critical habitat identified by the U.S Fish
and Wildlife and National Marine Fisheries Services as essential to the
conservation of a listed species and which may require special
management considerations or protection.   The evaluation of impacts for
a screening level pesticide risk assessment focuses on the biological
features that are constituent elements and is accomplished using the
screening-level taxonomic analysis (risk quotients, RQs) and listed
species levels of concern (LOCs) that are used to evaluate direct and
indirect effects to listed organisms.

The screening-level risk assessment has identified potential concerns
for indirect effects on listed species for those organisms dependant
upon mammals, freshwater fish and invertebrates, marine/estuarine
invertebrates, and marine/estuarine fish. In light of the potential for
indirect effects, the next step for EPA and the Service(s) is to
identify which listed species and critical habitat are potentially
implicated.  Analytically, the identification of such species and
critical habitat can occur in either of two ways.  First, the agencies
could determine whether the action area overlaps critical habitat or the
occupied range of any listed species.  If so, EPA would examine whether
the pesticide's potential impacts on non-endangered species would affect
the listed species indirectly or directly affect a constituent element
of the critical habitat.  Alternatively, the agencies could determine
which listed species depend on biological resources, or have constituent
elements, that fall into the taxa that may be directly or indirectly
impacted by the pesticide.  Then EPA would determine whether use of the
pesticide overlaps the critical habitat or the occupied range of those
listed species.  At present, the information reviewed by EPA does not
permit use of either analytical approach to make a definitive
identification of species that are potentially impacted indirectly or
critical habitat that is potentially impacted directly by the use of the
pesticide. EPA and the Service(s) are working together to conduct the
necessary analysis.

This screening-level risk assessment for critical habitat provides a
listing of potential biological features that, if they are constituent
elements of one or more critical habitats, would be of potential
concern.  These correspond to the taxonomic groups identified above as
being of potential concern for indirect effects (i.e., mammals,
freshwater fish and invertebrates, marine/estuarine invertebrates, and
marine/estuarine fish).  This should serve as an initial step in problem
formulation for further assessment of critical habitat impacts outlined
above, should additional work be necessary.

Co-occurrence Analysis

The goal of the analysis for co-location is to determine whether sites
of pesticide use are geographically associated with known locations of
listed species.  At the screening level, this analysis is accomplished
using the LOCATES v. 2.10.4 database.  The database uses location
information for listed species at the county level and compares it to
agricultural census data for crop production at the same county level of
resolution.  The product is a listing of federally listed species that
are located within counties known to produce the crop upon which the
pesticide will be used. 

Tables 36 and 37 below report the number of states and counties in which
endangered species reside that have the proposed metrafenone use. The
‘grape’ category was selected in LOCATES.  The data suggest that
there is considerable potential for exposure to a variety of endangered
species from metrafenone use. For additional LOCATES output refer to
Appendix E.

	Species Counts by State for Indicated Crops

	No species were excluded.

	Minimum of 1 Acre.

	All Medium Types Reported

	grapes

AL, AK, AZ, AR, CA, CO, CT, DE, DC, FL, GA, HI, ID, IL, IN, IA, KS, KY,
LA, ME, MD, MA, MI, MN, MS, MO, MT, NE, NV, NH, NJ, NM, NY, NC, ND, OH,
OK, OR, PA, PR, RI, SC, SD, TN, TX, UT, VT, VA, WA, WV, WI, WY

Table 36.  Number of Endangered Species Potentially Exposed to
Metrafenone with the Proposed Uses

	Mammals	Amphibians	Birds	Reptiles	Arachnids	Insects	Conf/Cyc	Dicot
Ferns	Lichen	Monocots

Counties	744	93	595	231	12	153	6	493	28	14	272

States	47	11	43	24	4	28	3	41	8	4	37

Species	129	21	163	74	13	73	4	607	20	4	109



Table 37.  Number of Endangered Species Potentially Exposed to
Metrafenone with the Proposed Uses

	Bivalve	Crustacean	Fish	Gastropod	Marine Mammal

Counties	290	56	449	44	50

States	27	13	38	16	7

Species	205	21	197	32	10



Description of Assumptions, Limitations, Uncertainties, Strengths, and
Data Gaps

Assumptions, Limitations, and Uncertainties Related to Exposure for all
Taxa

Maximum Use Scenario

The screening-level risk assessment focuses on characterizing potential
ecological risks resulting from a maximum use scenario, which is
determined from labeled statements of maximum  application rate and
number of applications with the shortest time interval between
applications.  The frequency at which actual uses approach this maximum
use scenario may be dependant on fungicide resistance, timing of
applications, cultural practices, and market forces.  

Assumptions, Limitations, and Uncertainties Related to Exposure for
Aquatic Species

Environmental Fate Studies

All of the environmental fate studies for the parent compound were
determined to be scientifically valid and therefore results from all of
the studies can be used to characterize the mobility and rates of
transformation of metrafenone.  However, many of the metabolism studies
have major uncertainties in the identification and pattern of formation
and decline of transformation products.  In all of the aquatic
metabolism studies, between 57% and 65% of the applied radioactivity
remains unidentified with incomplete characterization, and in two
aerobic soil metabolism studies, 15% and 44% of the applied
radioactivity is unidentified.  This includes at least four major
degradates that individually reach levels of 11% to 35% of the applied. 
Other transformation products appear as groups of up to 15 components,
in some cases characterized as each being <5% of the applied
radioactivity, but in other cases, some individual components make up 9%
to 10% of the applied.  Even when individual components can all be
classified as minor degradates, these groups represent such a large
portion of the applied radioactivity overall that the possibility that
they may have some impact as a group cannot be precluded despite their
lower individual levels.  This is especially true given that the
degradation pathways suggest that groups of degradates may have a high
degree of structural similarity and so may have similar fate and effects
behavior.  Without information to adequately characterize the
degradates, it may be necessary to assume that they are of equal
toxicity to the parents in order to quantify risks.

Aquatic Exposure Modeling

The lack of complete characterization and identification of degradation
products prompted additional aquatic exposure modeling on total
metrafenone residues.  Although this modeling approach is conservative,
it is reasonable modeling approach to address uncertainties in
degradation product identification.

Bioaccumulation Modeling

Bioaccumulation modeling was conducted because metrafenone has a log Kow
> 4.  The bioaccumulation modeling was conducted using guidance for the
KABAM model.  It is recommended to report the sediment pore water and
water column concentrations at the appropriate time when the pesticide
concentration reaches steady-state.  An evaluation of the time series
for metrafenone showed no clear plateau in metrafenone concentrations. 
Therefore, the appropriate averaging time was selected at 21 days to
serve as a conservative exposure concentration for bioaccumulation
modeling.  

Assumptions, Limitations, and Uncertainties Related to Exposure for
Terrestrial Species

Location of Wildlife Species

For this screening-level terrestrial risk assessment, a generic bird or
mammal was assumed to occupy either the treated field or adjacent areas
receiving metrafenone at the treatment rate on the field.  Actual
habitat requirements of any particular terrestrial species were not
considered, and it was assumed that species occupy, exclusively and
permanently, the modeled treatment area.  Spray drift model predictions
suggest that this assumption leads to an overestimation of exposure to
species that do not occupy the treated field exclusively and
permanently.

Routes of Exposure

This screening-level assessment for ground (liquid) applications of
metrafenone only considered dietary exposure. Other routes of exposure
that were not considered in the assessment are incidental soil ingestion
exposure, inhalation exposure, dermal exposure, and drinking water
exposure.

Dietary Intake and Other Limitations of Oral Studies in Terrestrial
Species

The avian acute oral study and the avian subacute dietary study each
have limitations for estimating the risk to wild species exposed to
pesticides in the environment.  Both studies have a fixed exposure
period and do not allow for differences in the responses of individuals
to different durations of exposure.  With the acute oral study, the
chemical is administered in a single dose.  This does not mimic wild
bird exposure through multiple feedings.  Also, it does not account for
the effect of different environmental matrices on absorption rate into
the gastrointestinal tract of the animal.  With the acute dietary study,
the endpoint is reported as the concentration mixed with food that
produces a response rather than as the dose ingested.  Although food
consumption sometimes allows for estimation of a dose, calculations of
the mg/kg/day are confounded by undocumented spillage of feed and how
consumption is measured over the duration of the test.  Usually, if
measured at all, food consumption is estimated once at the end of the
five-day exposure period.  Group housing of birds undergoing testing
allows for a measure of only the average consumption per day for a
group, and consumption estimates can be further confounded if birds die
within a treatment group.  In addition, the dietary study utilizes young
birds.  The exponential growth of young birds complicates the estimate
of the dose; controls often nearly double in size over the duration of
the test.  Since weights are only taken at the initiation and at the end
of the exposure period, the dose per body weight (mg/kg) is difficult to
estimate with any precision.  The interpretation of this test can be
further confounded by dietary consumption.  Estimation of the acute LC50
value is not only a function of the intrinsic toxicity of the pesticide,
but also the willingness of the birds to consume treated food.  

In addition to the uncertainties associated with the two toxicity
studies utilized for estimating acute risk to birds, other factors, not
normally taken into account in a screening level risk assessment may
narrow the differences between the dose-based and dietary-based acute
RQs for birds. The factors include differences in gross energy and
assimilative efficiency of laboratory feed versus food items in the
field, basic maintenance metabolic rates between wild birds and captive
birds, seasonal free living dietary requirements for wild birds
(including gorging behavior) and specific food avoidance behavior. 
These uncertainties may either overestimate or underestimate the risk in
a screening level assessment.

Gross Energy and Assimilative Efficiency. This screening level risk
assessment does not allow for gross energy and assimilative efficiency
differences between wildlife food items and laboratory feed.  For
example, a typical laboratory avian feed, as used, contains
approximately 2750 kcal/ kg.  The Agency’s Wildlife Exposure Factors
Handbook (U.S. Environmental Protection Agency, 1993) presents the
following dry-weight and fresh weight caloric contents for selected
wildlife food items:

Food Item		Energy Dry (kcal/kg)		Energy Fresh (kcal/kg)

grasses				4200				1300

broadleaf forage		4200				2200

seeds				5100				4700

fruits				2000				1100

insects				5600				1600

On gross energy content alone, direct comparison of a laboratory dietary
concentration-based effects threshold to a fresh-weight pesticide
residue estimate would result in an underestimation of field exposure by
food consumption by a factor of 1.25 - 2.5 for most food items.  Only
for seeds would the direct comparison of dietary threshold to residue
estimate lead to an overestimate of exposure.

Depending upon species and dietary matrix, bird assimilation of wild
diet energy ranges from 23 - 80%, and mammal’s assimilation ranges
from 41 - 85% (U.S. EPA, 1993).  If it is assumed that laboratory chow
is formulated to maximize assimilative efficiency (e.g., a value of
85%), a potential for underestimation of exposure may exist by assuming
that consumption of food in the wild is comparable with consumption
during laboratory testing.

Metabolic Rates.  In the screening process, exposure may be
underestimated because metabolic rates are not related to food
consumption.   For example, the Wildlife Exposure Factors Handbook (U.S.
EPA, 1993) includes allometric models for estimating both existing
metabolic rate (EMR) and free living metabolic rate (FMR).  EMR is the
metabolic rate necessary for animal maintenance in captivity without
body weight loss, a condition similar to caged test animals.  FMR is the
energy requirement for an organism in the wild.  For passerine birds
these relationships are as follows:

EMR (kcal/day) = 1.572 (body weight g) 0.6210

FMR (kcal/day) = 2.123 (body weight g) 0.749

Using a weight range for passerines of 10 - 150 g, the EMR predictions
range from 6.6 to 35.3, and the FMR ranges from 11.9 to 90.5 kcal/day. 
Thus, it appears that not accounting for increased energy demands of
organisms in the wild when comparing dietary residues to dietary
toxicity thresholds represents about a two-fold underestimation in
exposure potential.

Free Living Metabolic Requirements.  The screening procedure does not
account for situations where the feeding rate may be above or below
requirements to meet free living metabolic requirements.  Gorging
behavior is a possibility under some specific wildlife scenarios (e.g.,
bird migration) where the food intake rate may be greatly increased. 
Kirkwood (1983) has suggested that an upper-bound limit to this behavior
might be the typical intake rate multiplied by a factor of 5.  

Avoidance.  In contrast is the potential for avoidance, operationally
defined as animals responding to the presence of noxious chemicals in
their food by reducing consumption of treated dietary elements.  This
response is seen in nature where herbivores avoid plant secondary
compounds.  For agrochemicals, Dolbeer et al. (1994) reported that the
use of methiocarb on fruit crops reduced depredation by birds.  Of
course, chemical treatment of food sources and any subsequent avoidance
of those food sources by a species may, in itself, result in detrimental
effects on the energetics of the species.

Incidental Releases Associated with Use

This risk assessment was based on the assumption that the entire
treatment area is subject to pesticide application at the rates
specified on the label. Uneven application of the pesticide through
changes in calibration of application equipment, spillage, and localized
releases at specific areas of the treated field that are associated with
specifics of the type of application equipment were not accounted for in
this assessment.

Residue Levels Selection

The Agency relies on the work of Fletcher et al. (1994) for setting the
assumed pesticide residues in wildlife dietary items.  These residue
assumptions are believed to reflect a realistic upper-bound residue
estimate, although the degree to which this assumption reflects a
specific percentile estimate is difficult to quantify.  It is important
to note that the field measurement efforts used to develop the Fletcher
estimates of exposure involve highly varied sampling techniques.  It is
entirely possible that much of these data reflects residues averaged
over the entire above ground plants in the case of grass and forage
sampling.  Depending upon a specific wildlife species’ foraging
habits, whole aboveground plant samples may either underestimate or
overestimate actual exposure.

TerrPlant Model

At this time, the TerrPlant model cannot accurately estimate terrestrial
exposure levels with pesticides applied with multiple applications or
application intervals.  The technology is not yet available for these
types of estimations.  The label states that a maximum of 1.8 lbs a.i./A
may be applied per season, with a maximum of six applications the
highest single application rate is 0.3 lbs a.i./A.  In modeling the
terrestrial EECs, it was assumed that there was one application per
year. If assuming one application of 1.8 lbs a.i./A the RQ values may be
considered an overestimate of risk, but assuming one application of 0.3
lbs a.i./A the RQ values may be considered an underestimate of risk.
Therefore, the model was used to bracket the potential risk on
terrestrial plants as a result of metrafenone use.

Assumptions, Limitations, and Uncertainties Related to Effects
Assessment

Sublethal Effects

For an acute risk assessment, the screening risk assessment relies on
the acute mortality endpoint as well as a suite of sublethal responses
to the pesticide, as determined by the testing of species response to
chronic exposure conditions and subsequent chronic risk assessment.
Consideration of additional sublethal data in the assessment is
exercised on a case-by-case basis and only after careful consideration
of the nature of the sublethal effect measured and the extent and
quality of available data to support establishing a plausible
relationship between the measure of effect (sublethal endpoint) and the
assessment endpoints.

	

Age Class and Sensitivity of Effects Thresholds

Testing of juvenile organisms may overestimate toxicity at older age
classes for pesticidal active ingredients that act directly (without
metabolic transformation) because younger age classes may not have the
enzymatic systems associated with detoxifying xenobiotics. However, the
influence of age may not be uniform for all compounds, and compounds
requiring metabolic activation may be more toxic in older age classes. 
The risk assessment uses the most sensitive life-stage information as
the conservative screening endpoint.

Use of Most Sensitive Species Tested

Screening risk assessment relies on a selected toxicity endpoint from
the most sensitive species tested; however, the selected toxicity
endpoints do not necessarily reflect sensitivity of the most sensitive
species in a given environment. The relative position of the most
sensitive species tested in the distribution of all possible species is
a function of the overall variability among species to a particular
chemical. Toxicity thresholds may vary up to four orders of magnitude
across species for some chemicals.  Therefore, risk conclusions may
under- or overestimate actual ecological risk for a given species. 

Assumptions, Limitations, Uncertainties, Strengths, and Data Gaps
Related to the Acute and Chronic LOC’s

The risk characterization section of the assessment document includes an
evaluation of the potential for individual effects to listed species at
an exposure level equivalent to the LOC.  This evaluation is based on
the median lethal dose estimate and dose/response relationship
established for the effects study corresponding to each taxonomic group
for which the LOCs are exceeded.  The slope of the probit-dose response
is used to generate a probability of individual effects near the low end
tail of the curve.  Predictions based on low probability events are by
nature highly uncertain.  Moreover, for this assessment the
dose-response curve representing a given taxa is generated from one
study using one species.  It is likely that the resulting dose-response
relationship does not represent the response of all species within a
taxa.  Calculating the probability of individual effects at the lower
and upper bounds of the slope is designed to address this source of
uncertainty but the extent to which this captures the variability within
a taxa is unknown.  In some cases, a probit dose-response relationship
cannot be calculated.  In these instances, event probabilities are
calculated based on a default slope assumption of 4.5 (Urban and Cook,
1986). 

Literature Cited

Open Literature and Other Documents

	

Arnot, J.A. and F.A.P.C. Gobas. 2004. A food web bioaccumulation model
for organic chemicals in aquatic ecosystems. Environmental Toxicology
and Chemistry, v23 (10), 2343-2355.

Draft Assessment Report (DAR). 2005. Initial risk assessment provided by
the rapporteur Member State United Kingdom for the new active substance:
Metrafenone as referred to in Article 8(1) of Council Directive
91/414/EEC. July 2005.

Fletcher, J.S., J.E. Nellesson, and T. G. Pfleeger. 1994.  Literature
review and evaluation of the EPA food-chain (Kenaga) nomogram, an
instrument for estimating pesticide residues on plants.  Environ. Tox.
and Chem. 13(9):1383-1391.

Hoerger, F. and E.E. Kenaga. 1972.  Pesticide residues on plants:
correlation of representative data as a basis for estimation of their
magnitude in the environment.  IN: F. Coulston and F. Corte, eds.,
Environmental Quality and Safety: Chemistry, Toxicology and Technology.
Vol 1.  George Theime Publishers, Stuttgart, Germany.  pp. 9-28.

Opalski, K., Tresch, S., Kogel, K-H, Grossmann, K., Kohle, H. and R.
Huckelhoven. 2006. Metrafenone: Studies on the mode of action of a novel
cereal powdery mildew fungicide. Pest Management Science, 62(5),
p.393-401. ISSN 1526-498X.

Urban, D.J. and N.J. Cook, 1986.  Hazard Evaluation Division Standard
Evaluation Procedure Ecological Risk Assessment.  EPA 540/9-85-001. 
U.S. Environmental Protection Agency, Office of Pesticide Programs,
Washington D.C.

U.S. Environmental Protection Agency (USEPA).  1993.  Wildlife Exposure
Factors Handbook.  Office of Research and Development, Washington, D.C. 
EPA/600/R-13/187a.

U.S. Environmental Protection Agency (USEPA) 1998. Guidelines for
Ecological Risk Assessment.  EPA/630/R-95/002F.  Published in 63 FR
26846; May 14, 1998.  U.S. Environmental Protection Agency, Washington,
DC.  April, 1998.

U.S. Environmental Protection Agency (USEPA). 2004.  Overview of the
Ecological Risk Assessment Process in the Office of Pesticide Programs,
U.S. Environmental Protection Agency.  Endangered and Threatened Species
Effects Determinations.  Office of Prevention, Pesticides and Toxic
Substances, Office of Pesticide Programs, Washington, D.C. January 23,
2004.  Online at:   HYPERLINK
"http://www.epa.gov/oppfead1/endanger/consultation/ecorisk-overview.pdf"
 http://www.epa.gov/oppfead1/endanger/consultation/ecorisk-overview.pdf 

U.S. Environmental Protection Agency (USEPA). 2006. Pesticide Fact
Sheet: Metrafenone. New Chemical. September 2006.

U.S. Environmental Protection Agency (USEPA). 2008.  (Terrestrial
Residue EXposure model) Version 1.4.1 (10/09/08). Environmental Fate And
Effects Division, Office Of Pesticide Programs, U.S. Environmental
Protection Agency. 

Willis, G.H., and L.L. McDowell.  1987.  Pesticide Persistence on
Foliage in Reviews of Environmental Contamination and Toxicology.  100:
23-73.

Fate Studies Submitted to the USEPA/Office of Pesticide Programs

MRID 47267450

Zulalian, J.  2001.  BAS 560 F (AC 375839): uptake, depuration,
bioconcentration and metabolism of carbon-14 labeled AC 375839 in
bluegill sunfish (Lepomis macrochirus) under flow-through conditions:
Unpublished study performed by BASF Corporation, BASF Agro Research,
Princeton, NJ (Analytical Phase) and ABC Laboratories, Inc., Aquatic
Toxicology Programs Division, Columbia, MO (In-Life Phase; p. 39;
Appendix B, pp.221-346).

MRID 47267436

Xing, J.  2002.  BAS 560 F (CL 375839): laboratory validation of LC/MS
determinative and LC/MS/MS confirmatory method M 3503 for the
determination of BAS 560 F and CL 375816 residues in drinking and
surface water.  Unpublished study performed by BASF Agro Research,
Princeton, New Jersey.

MRID 47267435

Travis, D.  2002.  BAS 560 F (CL 375839): laboratory validation of LC/MS
determinative and LC/MS/MS confirmatory method M 3441 for the
determination of BAS 560 F and CL 377160 residues in soil.  Unpublished
study performed by BASF Agro Research, Princeton, New Jersey; sponsored
and submitted by BASF Corporation, Research Triangle Park, North
Carolina. 

MRID 47267434

Smalley, R.  2001.  Method validation of RLA 12618.00 "LC-MS
determination of CL 375839 and CL 377160 residues in soil".  Unpublished
study performed by BASF Agro Research, Gosport, Hampshire, United
Kingdom.

MRID 47267431

Panek, M, et al.  2008.  Anaerobic aquatic metabolism of 14C-BAS 560 F. 
Unpublished study performed, sponsored and submitted by BASF
Corporation, Research Triangle Park, North Carolina. 

MRID 47267430

Yan, Z. and R.A. Huang.  2002.  BAS 560 F (AC 375839): aerobic
transformation in water-sediment systems (including Amendment #1). 
Unpublished study performed by BASF Corporation, Ewing, New Jersey. 

MRID 47267429

Huang, R.  2002.  BAS 560 F: anaerobic soil metabolism.  Unpublished
study performed, sponsored and submitted by BASF Corporation, Research
Triangle Park, North Carolina.

MRID 4726728

Afzal, J. 2002.  CL 377160 (metabolite of BAS 560 F) rate of degradation
in three different soils under aerobic conditions.  Unpublished study
performed by BASF Corporation, Princeton, New Jersey.

MRID 47267427

Singh, M. 2008.  Aerobic soil metabolism of 14C-BAS 560 F on US soils. 
Unpublished study performed, sponsored and submitted by BASF
Corporation, Research Triangle Park, North Carolina. 

MRID 47267426

Steinführer, T.  2000.  14C-AC 375839 (CL 375839) Rate of degradation
in three different soils under aerobic conditions.  Unpublished study
performed by Cyanamid Forschung GmbH, Schwabenheim, Germany.

MRID 47267425

Steinführer, T.  2000.  AC 37589: Metabolism in soil under aerobic
conditions.  Unpublished study performed by Cyanamid Forschung GmbH,
Schwabenheim, Germany. 

MRID 47267424

Ta, C. 2001.  BAS 560 F (AC 375839): Soil photolysis.  Unpublished study
performed by BASF Agro Research, Ewing, New Jersey.  

MRID 47267423

Fung, C.H.  2002.  BAS 560 F (AC 375839): Aqueous photolysis. 
Unpublished study conducted by BASF Agro Research, Princeton and Ewing,
New Jersey.

MRID 47267422

An, D.  1999.  AC 375839: Hydrolysis.  Unpublished study performed by
American Cyanamid Company, Ewing, New Jersey.  

MRID 47267421

Tornisielo, A. and R. Hoefs. 2008.  Adsorption/desorption of a
metabolite of BAS 560 F (Reg. No. 4082230) on US soils (including
Amendment No. 1).  Unpublished study performed by BASF SA,
Guaratingueta, Brazil; and sponsored and submitted by BASF Corporation,
Research Triangle Park, North Carolina.  

MRID 47267421

Tornisielo, A. and R. Hoefs. 2008.  Adsorption/desorption of BAS 560 F
on US soils (including Amendment No. 1).  Unpublished study performed by
BASF SA, Guaratingueta, Brazil; and sponsored and submitted by BASF
Corporation, Research Triangle Park, North Carolina

MRID 47267432

Jordan,J. J.M. Stewart, and R. Warren. 2008. Terrestrial field
dissipation of BAS 560 00F in vineyard/orchard and row crop use
patterns. Unpublished study performed by Research for Hire, Porterville,
CA (field phase), Quails Agricultural Laboratory, Inc. Canada (field
phase), Vaughn Agricultural Research Services, Branchton, Ontario (field
phase), Research Options, Inc., Winter Garden, Florida (field phase),
BASF RTP, NC (analytical phase); and Agvise Laboratories, Inc. Northwood
ND.

Effects Studies Submitted to the USEPA/Office of Pesticide Programs

MRID 47267502

Ahmed, M.S., R. Troup and T. Harris. 2000(a). Avian acute oral toxicity
test with AC 375839 Technical in Northern Bobwhite (Colinus
virginianus). BASF Doc ID 2000/7000117.

MRID 47267503

Ahmed, M.S., R. Troup and T. Harris. 2000(b). Avian acute oral toxicity
test with AC 375839 Technical in Mallard Duck (Anas platyrhynchos). BASF
Doc ID 2000/7000115.

MRID 47267504

Ahmed, M.S., R. Troup and T. Harris. 2000(c). Avian dietary toxicity
test with AC 375839 Technical in Northern Bobwhite (Colinus
virginianus). BASF Doc ID 2000/7000126.

MRID 47267505

Ahmed, M.S., R. Troup and T. Harris. 2000(d). Avian dietary toxicity
test with AC 375839 Technical in Mallard Duck (Anas platyrhynchos). BASF
Doc ID 2000/7000125.

MRID 47267506

Ahmed, M.S. and M. Rodgers. 2002. BASF: Assessment to determine the
effects on reproduction in Northern Bobwhite (Colinus virginianus). BASF
Doc ID 2002/7005090.

MRID 47267515

Barker, C., K.Drottar and H. Krueger. 2000(a). Effect of AC 375839 on
growth of the green alga, Selenastrum capricornutum. BASF Doc ID
2000/7000122.

MRID 47267449

Barker, C., K.Drottar and H. Krueger. 2000(b). Toxicity of AC 375839
during the early life-stages of the Fathead Minnow (Pimephales
promelas). BASF Doc ID 2000/7000128.

MRID 47267447

Barker, C., K.Drottar and H. Krueger. 2000(c). Toxicity of AC 375839
during the life-cycle of the Cladoceran (Daphnia magna). BASF Doc ID
2000/7000130.

MRID 47267448

Cafarella, M. 2007. BAS 560 F – Life-cycle toxicity test with mysids
(Americamysis bahia). BASF Doc ID 2007/7009454.

MRID 47267512

Desjardins, D. Kendall, T., Krueger, H. and A. Van Cott. 2005(a). A
96-hour toxicity test with the freshwater alga (Anabaena flos-aquae).
BASF Doc ID 2005/7003441.

MRID 47267514

Desjardins, D. Kendall, T., Krueger, H. and A. Van Cott. 2005(b). A
96-hour toxicity test with the freshwater diatom (Navicula pelliculosa).
BASF Doc ID 2005/7003436.

MRID 47267513

Desjardins, D. Kendall, T., Krueger, H. and A. Van Cott. 2005(c). A
96-hour toxicity test with the marine diatom (Skeletonema costatum).
BASF Doc ID 2005/7003443.

MRID 47267511

Desjardins, D. Kendall, T., Krueger, H. and A. Van Cott. 2005(d). A
7-day static renewal toxicity test with duckweed (Lemna gibba G3). BASF
Doc ID 2005/7003440.

MRID 47267438

Jatzek, J. 2002(a). CL 375816 (Metabolite of BAS 560 F, Benzophenone)
– Determination of the acute effect on the swimming ability of the
water flea Daphnia magna STRAUS. BASF Doc ID 2002/1004870. 

MRID 47267516

Jatzek, J. 2002(b). CL 375816 (Metabolite of BAS 560 F, Benzophenone)
– Determination of the inhibitory effect on the cell multiplication of
unicellular green algae. BASF Doc ID 2002/1004873.

MRID 47267439

Jatzek, J. 2002(c). CL 4084564 (Metabolite of BAS 560 F, Benzophenone)
– Determination of the acute effect on the swimming ability of the
water flea Daphnia magna STRAUS. BASF Doc ID 2002/1004869.

MRID 47267517

Jatzek, J. 2002(d). CL 4084564 (Metabolite of BAS 560 F, Benzophenone)
– Determination of the inhibitory effect on the cell multiplication of
unicellular green algae. BASF Doc ID 2002/1004872.

MRID 47267501

Krueger, H., MacGregor, J., Jaber, M. and C. Barker. 2001. Toxicity of
BAS 560 F to Chironomus riparius during a prolonged sediment toxicity
test. BASF Doc ID 2001/7000462. 

MRID 47267519

Luhrs, U. 2001. Acute toxicity (14 days) of Metabolite CL 377160
(Metabolite of BAS 560 F, Benzophenone) to the earthworm Eisenia fetida
in artificial soil. BASF Doc ID 2001/ 1007447.

MRID 47267518

Mulligan, E. 2001(a). Acute toxicity of AC 375839 to the earthworm
Eisenia fetida. BASF Doc ID 2001/7000259.

MRID 47267608

Mulligan, E. 2001(b). Acute toxicity of AC 375839 300 g/L SC RLF 12359
(SF 10358) to the earthworm Eisenia fetida. BASF Doc ID 2001/7000262.

MRID 47267442

Palmer, S. Krueger, H. MacGregor, J. and G Mitchell. 1999(a). Acute
toxicity of AC 375839 to bluegill, Lepomis macrochirus, under
flow-through test conditions. BASF Doc ID 1999/7000286.

MRID 47267443

Palmer, S. Krueger, H. MacGregor, J. and G Mitchell. 1999(b). Acute
toxicity of AC 375839 to rainbow trout, Oncorhynchus mykiss, under
flow-through test conditions. BASF Doc ID 1999/7000289.

MRID 47267437

Palmer, S. Krueger, H. MacGregor, J. and G Mitchell. 1999(c). Acute
toxicity of AC 375839 to Daphnia magna under static test conditions.
BASF Doc ID 1999/7000287.

MRID 47267605

Palmer, S. Krueger, H. MacGregor, J. and C. Barker. 2001(a). Acute
toxicity of BAS 560 00F (SF 10358, RLF 12359) to rainbow trout
(Oncorhynchus mykiss) under static test conditions. BASF Doc ID
2001/7000463.

MRID 47267604

Palmer, S. Krueger, H. MacGregor, J. and C. Barker. 2001(b). Acute
toxicity of BAS 560 00F (SF 10358, RLF 12359) to Daphnia magna under
static test conditions. BASF Doc ID 2001/7000464.

MRID 47267607

Palmer, S. Krueger, H. MacGregor, J. and C. Barker. 2001(c). Acute
toxicity of BAS 560 00F (SF 10358, RLF 12359) on growth of the green
alga, Selenastrum capricornutum.  BASF Doc ID 2001/7000465.

MRID 47267441

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, T. Kendall, H. Krueger and A. Van Cott, 2005(a). A 96-hour
flow-through acute toxicity test with the saltwater mysid (Americamysis
bahia). BASF Doc ID 2005/7003438.

MRID 47267446

Palmer, S., T. Kendall, H. Krueger and A. Van Cott, 2005(b). A 96-hour
flow-through acute toxicity test with the sheepshead minnow (Cyprinodon
variegatus). BASF Doc ID 2005/7003439.

MRID 47267440

Palmer, S., T. Kendall, H. Krueger and A. Van Cott, 2005(c). A 96-hour
shell deposition test with the eastern oyster (Crassostrea virginica).
BASF Doc ID 2005/7003442.

MRID 47267510

Porch, J. and H. Krueger. 2001. Effect of BAS 560 F 500g/L SC (RLF
12380) on vegetative vigor of ten species of plants. BASF Doc ID
2001/7002392.

MRID 47267509

Porch, J., K. Martin, and H. Krueger. 2001. Effect of BAS 560 F 500 g/L
SC (RLF 12380) on seedling emergence of ten species of plants. BASF Doc
ID 2001/7002391.

MRID 47267508

Strnad, A. and E. Mulligan. 2002(a). Acute toxicity of AC 375839
Technical to the honeybee, Apis mellifera. BASF Doc ID 2002/7004414.

MRID 47267606

Strnad, A. and E. Mulligan. 2002(b). Acute toxicity of AC 375839 in a
300 g/L SC (SF 10358/RLF 12359) to the honeybee, Apis mellifera. BASF
Doc ID 2002/7004415.

MRID 47267444

Zok, S. 2002(a). Reg. No. 4074484 (Metabolite of BAS 560 F) – Acute
toxicity study on the rainbow trout (Oncorhynchus mykiss) in a static
system over 96 hours. BASF Doc ID 2002/1004394.

MRID 47267445

Zok, S. 2002(b). CL 4084564 (Metabolite of BAS 560 F) – Acute toxicity
study on the rainbow trout (Oncorhynchus mykiss) in a static system over
96 hours. BASF Doc ID 2002/1005255.

 

MRID 47267507

Zok, S. 2006. BAS 560 F – 1 Generation reproduction study on the
mallard duck (Anas platyrhynchos) by administration in the diet. BASF
Doc ID 2006/1018046.

Appendices

Appendix A. Chemical Names, Structures, and Maximum Reported Amounts of
Metrafenone and Its Degradates.

Appendix B. Aquatic Model Input/Output Data.

Appendix C. Example T-REX Output for Metrafenone.

Appendix D. Example KABAM (v. 1.0) Results for Metrafenone.

Appendix E. LOCATES Output of Listed Species.

Appendix F. Submitted Environmental Fate Studies for Metrafenone.

Appendix G. Submitted Ecological Effects Studies for Metrafenone.

Appendix H. The Risk Quotient Method.

List of Figures

Figure 1. Chemical Structure of
Metrafenone…………………………………….……..13

Figure 2. Conceptual Model Depicting Sources of Exposure from
Metrafenone as well as Metrafenone Residues, Potential Receptors, and
Adverse Effects from the Proposed Uses of Metrafenone on
Grapes…………………………………………………………
….…19

List of Tables

Table 1. Summary of Environmental Risk Conclusions for Aquatic Animals
and Plants from Metrafenone Use on Grapes at the Maximum Proposed
Application Rate……...….6

Table 2. Summary of Environmental Risk Conclusions for Terrestrial
Animals and Plants from Metrafenone Use on Grapes at the Maximum
Proposed Application Rate………....6

Table 3. Listed Species Risks Associated with Direct or Indirect Effects
from Metrafenone use on Grapes at the Maximum Proposed Application
Rate…………..…..12

Table 4. Environmental Fate Properties of
Metrafenone…………………………..…….14

Table 5. Metrafenone Use and Application Information Based on the
Proposed Label for Metrafenone 300
SC…………………………………………………………….
.………15

Table 6. Test Species Evaluated for Assessing Potential Ecological
Effects of Metrafenone and the Associated Acute Toxicity
Classification………………….……...16

Table 7. Measures of Ecological Effects and Exposure for
Metrafenone……………….26

Table 8. Total Extractable Metrafenone Residue Half-lives from
Laboratory Degradation
Studies………………………………………………………
……………………………32

Table 9. Scenarios used to Estimate Metrafenone Concentrations in
Surface Water…....33

Table 10. PRZM/EXAMS Input Parameteres for Metrafenone and Total
Extractable Metrafenone
Residues………………………………………………………
………...….33

Table 11. Estimated Exposure Concentrations for Metrafenone and Total
Metrafenone Residues from Surface
Water………………………………………………………..
…..34

Table 12. Input Parameters and Chemical Characteristics of Metrafenone
Used in
KABAM…………………………………………………………
…………………….…35

Table 13. Estimated Concentrations of Metrafenone in Fish (based on
metrafenone total residue
scenario)………………………………………………………
……………..…..35

Table 14. Terrestrial Food-Item Residue Estimates for Birds with
Metrafenone Proposed Use on Grapes at 0.3 lbs a.i./A (6 apps./year; 14
day app. interval) with a Foliar Dissipation Half-life default value of
35 Days ………………………………………….37

Table 15. Terrestrial Food-Item Residue Estimates for Mammals with
Metrafenone Proposed Use on Grapes at 0.3 lbs a.i./A (6 apps./year; 14
day app. interval) with a Foliar Dissipation Half-life default value of
35 Days ………………………………………….37

Table 16. Estimated Environmental Concentrations of Metrafenone for
Terrestrial Plants from Grape
Use……………………………………………………………
………..……38

Table 17. Freshwater Fish Acute Toxicity
Data…………………………………….…   39

Table 18. Freshwater Invertebrate Acute Toxicity
Data…………………………………43

Table 19. Marine/Estuarine Fish Acute Toxicity
Data…………………………………..45

Table 20. Marine/Estuarine Invertebrate Acute Toxicity
Data…………………………..46

Table 21. Freshwater Fish Chronic Toxicity
Data……………………………………….47

Table 22. Marine/Estuarine Invertebrate Chronic Toxicity
Data………………………..49

Table 23. Aquatic Plant Toxicity
Data…………………………………………………..51

Table 24. Avian Acute Toxicity
Data……………………………………………………55

Table 25. Mammalian Acute Toxicity
Data…………..…………………………………57

Table 26. Terrestrial Invertebrate Acute/Subacute Toxicity
Data……………………….60

Table. 27. Avian Chronic Toxicity
Data…………………………………………………63

Table. 28. Mammalian Chronic Toxicity
Data…………………………………………..65

Table 29. Metrafenone: Chronic Risks to Marine/Estuarine Invertebrates
(Application Rate 0.3 lbs a.i./L, 6
Applications/Year)………………………………………….…
…..70

Table 30. Upper Bound Kenaga, Chronic Avian Dietary Based Risk
Quotients….…….72

Table 31. Chronic RQ Values for Birds Consuming Fish Contaminated by
Metrafenone (based on
KABAM)…………………………………………………………
……..…….73

Table 32. Upper Bound Kenaga, Chronic Mammalian Dietary Based Risk
Quotients.…73

Table 33. Upper Bound Kenaga, Chronic Mammalian Dose-Based Risk
Quotients……74

Table 34. Chronic RQ Values for Mammals Consuming Fish Contaminated by
Metrafenone (based on
KABAM)……………………………………………………….74

Table 35. Listed Species Risks Associated with Direct or Indirect
Effects from Metrafenone use on Grapes at the Maximum Proposed
Application Rate……………....88

Table 36. Number of Endangered Species Potentially Exposed to
Metrafenone as used on
grapes………..………………………………………………
…………………………...94

Table 37. Number of Endangered Species Potentially Exposed to
Metrafenone as used on
grapes…………………………………………………………
………………………….94

 TGAI: technical grade active ingredient; TEP: typical end-use product
(formulation)

 EC Directive 91/414.

 TGAI: technical grade active ingredient; TEP: typical end-use product
(formulation)

 PRZM 3.1.2.2 (5/16/05) and  EXAMS  2.98.04(4/25/04)  were used rather
than GENEEC2 (4/25/04) in anticipation of toxicity concerns for aquatic
organisms. 

 Monocots include corn, Zea mays; oat, Avena sativa; onion, Allium cepa;
and ryegrass, Lolium Perenne).  Dicots include cucumber, Cucumis sativa;
lettuce, Lactuca sativa; oilseed rape, Brassica napus; soybean, Glycine
max; sugarbeet, Beta vulgaris; and tomato, Lycopersicon esculentum.

 Soybean was treated with the test substance on a different day than the
other species, and the concentration of metrafenone in the test
substance was analyzed on the same day, thus soybean had a different
measured concentration than the other test species.

 The acute eastern oyster study (MRID 47267440) using the technical
grade active ingredient indicated a 42% reduction in concentration from
uncentrifuged sample to centrifuged sample. If the percentage is applied
to the NOAEC value from this study, 0.118 mg total a.i./L, it would
reduce to 0.068 mg a.i./L, which is still above the highest model
estimated EEC value (0.02 mg/L).

 See eastern oyster study (MRID 47267440)

 See eastern oyster study (MRID 47267440)

 Applicable to all dicot (and monocot) species except for the soybean
for which the endpoints are NOAEC 0.283 lbs a.i./A and EC05, EC25 >
0.283 lbs a.i./A in the vegetative vigor study only.

	Mayer, F.L. and M.R. Ellersieck, 1986. Manual of acute toxicity:
Interpretation and data base for 410 chemicals of freshwater animals.
Resource Publication 160. U. S. Fish and Wildlife Service. Department of
the Interior, Washington, D.C., 579 p.

 PAGE   

Page   PAGE  7  of   NUMPAGES  114 

Page   PAGE  1  of   NUMPAGES  114 

Seedling emergence

Individual Plants

Plants

Riparian

Wetland/ 

Vertebrates

Aquatic 

Invertebrates

Aquatic 

reproduction

Reduced  

Reduced growth

Reduced survivall

Individual Animals

Plants

Upland

Terrestrial

Phase Amphibians

Reptiles, Terrestrial 

Birds, Mammals,

Terrestrial Vertebrates

Changes

Attribute

Receptors

Uptake

Integument 

Gill/

Root Uptake

Direct contact/

Root Uptake

Direct contact/

Ingestion

Route

Exposure

Groundwater

Sediment

Water Body/ 

Receiving 

Foliage/Soil

Wetland 

Riparian/

Foliage/Soil

Upland

fruit, insects

Residues (foliage, 

Terrestrial Food 

Media

Exposure

Source/

Percolation

(Infiltration/

Leaching

Erosion

Runoff/

Drift

Spray

Deposition

Direct

Pathways

Transport

Source/

l 

Metrafenone applied as foliar spray with ground equipment on grapes

Stressor

Vegetative vigor

Individual 

vertebrates and 

invertebrates

Reduced

survivall

Reduced

growth

Reduced

reproduction

Plant 

population

Reduced

population

growth

Aquatic 

Plants

Uptake/ 

Adsorption

OFFICE OF

PREVENTION, PESTICIDES AND

TOXIC SUBSTANCES

