Environmental Fate, Ecological Risk and 

Endangered Species Assessment 

in Support of the Registration Review of 

Fomesafen Sodium (PC123802)

Prepared by:

Paige D. Doelling, PhD, Fisheries Biologist

Stephen P. Wente, PhD, Biologist	U. S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch I

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington, DC 20460

Reviewed by:

Faruque Khan, PhD, Senior Fate Scientist



	

December 2008

Table of Contents

  TOC \h \z \t "ERA Heading 1,1,ERA Heading 2,2,ERA Heading 3,3,ERA
Heading 4,3,Appendix Header,1"    HYPERLINK \l "_Toc221951908"  1.0
Executive Summary	  PAGEREF _Toc221951908 \h  6  

  HYPERLINK \l "_Toc221951909"  1.1	Nature of Stressor	  PAGEREF
_Toc221951909 \h  6  

  HYPERLINK \l "_Toc221951910"  1.2	Potential Risk	  PAGEREF
_Toc221951910 \h  6  

  HYPERLINK \l "_Toc221951911"  1.3	Endangered Species Assessment	 
PAGEREF _Toc221951911 \h  7  

  HYPERLINK \l "_Toc221951912"  2.0	Problem Formulation	  PAGEREF
_Toc221951912 \h  9  

  HYPERLINK \l "_Toc221951913"  2.1	Stressor Description	  PAGEREF
_Toc221951913 \h  9  

  HYPERLINK \l "_Toc221951914"  2.2	Environmental Fate Summary	  PAGEREF
_Toc221951914 \h  9  

  HYPERLINK \l "_Toc221951915"  2.3	Mode of Action	  PAGEREF
_Toc221951915 \h  10  

  HYPERLINK \l "_Toc221951916"  2.4	Use Characterization	  PAGEREF
_Toc221951916 \h  10  

  HYPERLINK \l "_Toc221951917"  2.5	Assessment Endpoints	  PAGEREF
_Toc221951917 \h  12  

  HYPERLINK \l "_Toc221951918"  2.5.1	Ecosystems Potentially at Risk	 
PAGEREF _Toc221951918 \h  13  

  HYPERLINK \l "_Toc221951919"  2.5.2	Ecological Effects	  PAGEREF
_Toc221951919 \h  13  

  HYPERLINK \l "_Toc221951920"  2.5.2.1	Direct	  PAGEREF _Toc221951920
\h  13  

  HYPERLINK \l "_Toc221951921"  2.5.2.2	Indirect	  PAGEREF _Toc221951921
\h  13  

  HYPERLINK \l "_Toc221951922"  2.6	Risk Hypotheses	  PAGEREF
_Toc221951922 \h  15  

  HYPERLINK \l "_Toc221951923"  2.7	Results of Previous Assessments	 
PAGEREF _Toc221951923 \h  15  

  HYPERLINK \l "_Toc221951924"  2.8	Analysis Plan	  PAGEREF
_Toc221951924 \h  16  

  HYPERLINK \l "_Toc221951925"  3.0	Exposure Assessment	  PAGEREF
_Toc221951925 \h  17  

  HYPERLINK \l "_Toc221951926"  3.1	Label Application Rates and
Intervals	  PAGEREF _Toc221951926 \h  17  

  HYPERLINK \l "_Toc221951927"  3.2	Aquatic Exposure	  PAGEREF
_Toc221951927 \h  18  

  HYPERLINK \l "_Toc221951928"  3.2.1	PRZM-EXAMS Modeling Inputs and
Scenario Selection	  PAGEREF _Toc221951928 \h  18  

  HYPERLINK \l "_Toc221951929"  3.2.2	PRZM-EXAMS Modeling Output	 
PAGEREF _Toc221951929 \h  19  

  HYPERLINK \l "_Toc221951930"  3.2.3	Registrant-submitted Aquatic
Exposure Modeling	  PAGEREF _Toc221951930 \h  20  

  HYPERLINK \l "_Toc221951931"  3.2.4	SCIGROW Modeling for Ground Water	
 PAGEREF _Toc221951931 \h  20  

  HYPERLINK \l "_Toc221951932"  3.2.5	Soil Accumulation	  PAGEREF
_Toc221951932 \h  21  

  HYPERLINK \l "_Toc221951933"  3.3	National Surface Water Monitoring
Data	  PAGEREF _Toc221951933 \h  23  

  HYPERLINK \l "_Toc221951934"  3.3.1	Surface Water	  PAGEREF
_Toc221951934 \h  23  

  HYPERLINK \l "_Toc221951935"  3.3.2	Ground Water	  PAGEREF
_Toc221951935 \h  23  

  HYPERLINK \l "_Toc221951936"  3.4	Bird and Mammal Exposure (TREX)	 
PAGEREF _Toc221951936 \h  24  

  HYPERLINK \l "_Toc221951937"  3.5	Terrestrial Invertebrate Exposure	 
PAGEREF _Toc221951937 \h  26  

  HYPERLINK \l "_Toc221951938"  3.6	Terrestrial Plant Exposure
(TerrPlant & AgDrift)	  PAGEREF _Toc221951938 \h  27  

  HYPERLINK \l "_Toc221951939"  3.6.1	TerrPlant	  PAGEREF _Toc221951939
\h  27  

  HYPERLINK \l "_Toc221951940"  3.6.2	AgDrift	  PAGEREF _Toc221951940 \h
 28  

  HYPERLINK \l "_Toc221951941"  4.0	Effects Assessment	  PAGEREF
_Toc221951941 \h  30  

  HYPERLINK \l "_Toc221951942"  4.1	Specific Toxicological Concerns
Associated with this Chemical	  PAGEREF _Toc221951942 \h  30  

  HYPERLINK \l "_Toc221951943"  4.2	Aquatic Hazard Summary	  PAGEREF
_Toc221951943 \h  31  

  HYPERLINK \l "_Toc221951944"  4.3	Summary of Aquatic Ecotoxicity
Studies	  PAGEREF _Toc221951944 \h  33  

  HYPERLINK \l "_Toc221951945"  4.3.1	Aquatic Guideline Data	  PAGEREF
_Toc221951945 \h  33  

  HYPERLINK \l "_Toc221951946"  4.3.2	Aquatic Data from ECOTOX	  PAGEREF
_Toc221951946 \h  33  

  HYPERLINK \l "_Toc221951947"  4.4	Terrestrial Hazard Summary	  PAGEREF
_Toc221951947 \h  35  

  HYPERLINK \l "_Toc221951948"  4.5	Summary of Terrestrial Ecotoxicity
Studies	  PAGEREF _Toc221951948 \h  36  

  HYPERLINK \l "_Toc221951949"  4.5.1	Avian and Small Mammal Guideline
Data	  PAGEREF _Toc221951949 \h  36  

  HYPERLINK \l "_Toc221951950"  4.5.2	Terrestrial Plant Data	  PAGEREF
_Toc221951950 \h  36  

  HYPERLINK \l "_Toc221951951"  4.5.2.1	Guideline Studies	  PAGEREF
_Toc221951951 \h  36  

  HYPERLINK \l "_Toc221951952"  4.5.2.2	Additional Registrant-Submitted
Data	  PAGEREF _Toc221951952 \h  37  

  HYPERLINK \l "_Toc221951953"  4.5.3	Terrestrial Insect Data	  PAGEREF
_Toc221951953 \h  38  

  HYPERLINK \l "_Toc221951954"  4.5.4	ECOTOX Data	  PAGEREF
_Toc221951954 \h  38  

  HYPERLINK \l "_Toc221951955"  4.5.4.1	Biochemical Endpoints	  PAGEREF
_Toc221951955 \h  38  

  HYPERLINK \l "_Toc221951956"  4.5.4.2	Aquatic Community-Level	 
PAGEREF _Toc221951956 \h  39  

  HYPERLINK \l "_Toc221951957"  4.5.5	Carcinogenicity, Mutagenicity, and
Endocrine Disruption	  PAGEREF _Toc221951957 \h  40  

  HYPERLINK \l "_Toc221951958"  4.5.6	Toxic Effects of Multi-Active
Ingredient Labeled Products	  PAGEREF _Toc221951958 \h  40  

  HYPERLINK \l "_Toc221951959"  4.6	Incident Database Review	  PAGEREF
_Toc221951959 \h  41  

  HYPERLINK \l "_Toc221951960"  5.0	Risk Estimation	  PAGEREF
_Toc221951960 \h  42  

  HYPERLINK \l "_Toc221951961"  5.1	Aquatic RQ Summary	  PAGEREF
_Toc221951961 \h  43  

  HYPERLINK \l "_Toc221951962"  5.2	Terrestrial RQ Summary	  PAGEREF
_Toc221951962 \h  44  

  HYPERLINK \l "_Toc221951963"  5.2.1	Terrestrial Plants	  PAGEREF
_Toc221951963 \h  44  

  HYPERLINK \l "_Toc221951964"  5.2.1.1	TerrPlant	  PAGEREF
_Toc221951964 \h  44  

  HYPERLINK \l "_Toc221951965"  5.2.1.2	AgDrift	  PAGEREF _Toc221951965
\h  46  

  HYPERLINK \l "_Toc221951966"  5.2.2	Avian RQ Summary	  PAGEREF
_Toc221951966 \h  47  

  HYPERLINK \l "_Toc221951967"  5.2.3	Small Mammal RQ Summary	  PAGEREF
_Toc221951967 \h  48  

  HYPERLINK \l "_Toc221951968"  5.2.4	Terrestrial Invertebrate Summary	 
PAGEREF _Toc221951968 \h  48  

  HYPERLINK \l "_Toc221951969"  6.0	Risk Description	  PAGEREF
_Toc221951969 \h  50  

  HYPERLINK \l "_Toc221951970"  6.1	Aquatic Risk	  PAGEREF _Toc221951970
\h  50  

  HYPERLINK \l "_Toc221951971"  6.2	Terrestrial Risk	  PAGEREF
_Toc221951971 \h  53  

  HYPERLINK \l "_Toc221951972"  6.2.1	Birds, Reptiles, and Amphibians	 
PAGEREF _Toc221951972 \h  53  

  HYPERLINK \l "_Toc221951973"  6.2.2	Mammals	  PAGEREF _Toc221951973 \h
 54  

  HYPERLINK \l "_Toc221951974"  6.2.3	Terrestrial Invertebrates	 
PAGEREF _Toc221951974 \h  54  

  HYPERLINK \l "_Toc221951975"  6.2.4	Plants	  PAGEREF _Toc221951975 \h 
56  

  HYPERLINK \l "_Toc221951976"  6.3	Endangered Species	  PAGEREF
_Toc221951976 \h  58  

  HYPERLINK \l "_Toc221951977"  6.3.1	Aquatic Listed Species	  PAGEREF
_Toc221951977 \h  58  

  HYPERLINK \l "_Toc221951978"  6.3.2	Terrestrial Listed Species	 
PAGEREF _Toc221951978 \h  59  

  HYPERLINK \l "_Toc221951979"  6.3.3	Plants	  PAGEREF _Toc221951979 \h 
65  

  HYPERLINK \l "_Toc221951980"  6.3.4	Action Area	  PAGEREF
_Toc221951980 \h  66  

  HYPERLINK \l "_Toc221951981"  6.3.5	Probability of Individual Effects	
 PAGEREF _Toc221951981 \h  68  

  HYPERLINK \l "_Toc221951982"  6.4	Risk Conclusions	  PAGEREF
_Toc221951982 \h  70  

  HYPERLINK \l "_Toc221951983"  7.0	Uncertainties	  PAGEREF
_Toc221951983 \h  72  

  HYPERLINK \l "_Toc221951984"  7.1	Exposure Assessment Uncertainties	 
PAGEREF _Toc221951984 \h  72  

  HYPERLINK \l "_Toc221951985"  7.1.1	Aquatic Exposure	  PAGEREF
_Toc221951985 \h  72  

  HYPERLINK \l "_Toc221951986"  7.1.1.1	Modeling Assumptions	  PAGEREF
_Toc221951986 \h  72  

  HYPERLINK \l "_Toc221951987"  7.1.1.2	Monitoring Data	  PAGEREF
_Toc221951987 \h  72  

  HYPERLINK \l "_Toc221951988"  7.1.1.3	Impact of Vegetative Setbacks on
Runoff	  PAGEREF _Toc221951988 \h  72  

  HYPERLINK \l "_Toc221951989"  7.1.1.4	PRZM Modeling Inputs and
Predicted Aquatic Concentrations	  PAGEREF _Toc221951989 \h  73  

  HYPERLINK \l "_Toc221951990"  7.1.2	Terrestrial Exposure Uncertainties
  PAGEREF _Toc221951990 \h  73  

  HYPERLINK \l "_Toc221951991"  7.1.2.1	Residue Levels Selection	 
PAGEREF _Toc221951991 \h  74  

  HYPERLINK \l "_Toc221951992"  7.1.2.2	Dietary Intake	  PAGEREF
_Toc221951992 \h  74  

  HYPERLINK \l "_Toc221951993"  7.2	Effects Assessment Uncertainties	 
PAGEREF _Toc221951993 \h  75  

  HYPERLINK \l "_Toc221951994"  7.2.1	Age Class and Sensitivity of
Effects Thresholds	  PAGEREF _Toc221951994 \h  75  

  HYPERLINK \l "_Toc221951995"  7.2.2	Use of Surrogate Species Data	 
PAGEREF _Toc221951995 \h  75  

  HYPERLINK \l "_Toc221951996"  7.2.3	Extrapolation of Effects	  PAGEREF
_Toc221951996 \h  75  

  HYPERLINK \l "_Toc221951997"  7.2.4	Acute LOC Assumptions	  PAGEREF
_Toc221951997 \h  75  

  HYPERLINK \l "_Toc221951998"  References	  PAGEREF _Toc221951998 \h 
76  

  HYPERLINK \l "_Toc221951999"  Guideline Study References	  PAGEREF
_Toc221951999 \h  76  

  HYPERLINK \l "_Toc221952000"  ECOTOX References	  PAGEREF
_Toc221952000 \h  81  

 

Appendix A – Exposure and Modeling

Appendix B – Ecological Effects

Appendix C – ECOTOX Bibiligraphy

Appendix D – RQ Method and LOCs

Appendix E – Analysis Summary

Appendix F – LOCATES (Endangered Species)

Appendix G – Spray Drift Analysis 

Table of Figures

  TOC \c "Figure"  Figure 1 Chemical structure of fomesafen	  PAGEREF
_Toc217883368 \h  9 

Figure 2 Conceptual model for fomesafen effects	  PAGEREF _Toc217883369
\h  14 

Figure 3. Estimate of Fomesafen Loading in the Surface Soil	  PAGEREF
_Toc217883370 \h  23 

 



Table of Tables

  TOC \c "Table"  Table 1  Summary of Direct and Indirect Effects	 
PAGEREF _Toc221940748 \h  8 

Table 2  Current Fomesafen Registrations	  PAGEREF _Toc221940749 \h  11 

Table 3  Summary of Assessment Endpoints and Measures of Ecological
Effect	  PAGEREF _Toc221940750 \h  12 

Table 4  Label Application Rates and Intervals for Fomesafen Use on
Soybeans, Cotton, Snap Beans and Dry Beans1	  PAGEREF _Toc221940751 \h 
17 

Table 5  Label Application Rates and Intervals for Section 24c Uses of
Fomesafen	  PAGEREF _Toc221940752 \h  18 

Table 6.  Input Parameters for PRZM-EXAMS Modeling of Fomesafen on
Cotton, Soybeans, Dry Beans, and Snap Bean	  PAGEREF _Toc221940753 \h 
19 

Table 7.  PRZM-EXAMS Aquatic EECs for Fomesafen	  PAGEREF _Toc221940754
\h  20 

Table 8  PRZM-EXAMS EECs for Fomesafen at 0.50 lb ai/A	  PAGEREF
_Toc221940755 \h  20 

Table 9.  Input Parameters for SCIGROW Modeling for Fomesafen	  PAGEREF
_Toc221940756 \h  21 

Table 10 Label Application Rates and Intervals for Fomesafen Use on
Soybeans, Cotton, Snap Beans, and Dry Beans1	  PAGEREF _Toc221940757 \h 
21 

Table 11  Input Parameters for TREX Modeling	  PAGEREF _Toc221940758 \h 
24 

Table 12  Bird Dose Estimates	  PAGEREF _Toc221940759 \h  25 

Table 13  Mammal Dose Estimates	  PAGEREF _Toc221940760 \h  26 

Table 14  Terrestrial Invertebrate Exposure	  PAGEREF _Toc221940761 \h 
26 

Table 15  Terrestrial Plant Exposure	  PAGEREF _Toc221940762 \h  27 

Table 16  Drift Deposition from Ground Applications	  PAGEREF
_Toc221940763 \h  29 

Table 17  Drift Depostion from Aerial Applications	  PAGEREF
_Toc221940764 \h  29 

Table 18  Aquatic Toxicity Profile for Fomesafen	  PAGEREF _Toc221940765
\h  32 

Table 19  Terrestrial Toxicity Profile for Fomesafen	  PAGEREF
_Toc221940766 \h  35 

Table 20  Drift Deposition from Aerial Applications	  PAGEREF
_Toc221940767 \h  46 

Table 21  Drift Deposition from Ground Applications	  PAGEREF
_Toc221940768 \h  46 

Table 22  Avian RQ Summary	  PAGEREF _Toc221940769 \h  47 

Table 23  Small Mammal RQ Summary	  PAGEREF _Toc221940770 \h  48 

Table 24  Terrestrial Invertebrate RQ Summary	  PAGEREF _Toc221940771 \h
 49 

Table 25  Summary of Risk to Non-listed Aquatic Organisms	  PAGEREF
_Toc221940772 \h  52 

Table 26  Comparison of Chronic Data for Acifluorfen, Fomesafen, and
Oxyfluorfen.	  PAGEREF _Toc221940773 \h  54 

Table 27  Summary of Risk to Non-Listed Terrestrial Animals	  PAGEREF
_Toc221940774 \h  55 

Table 28  Summary of Risk to Non-listed Terrestrial Plants	  PAGEREF
_Toc221940775 \h  57 

Table 29  Summary of Risk to Listed Aquatic Organisms	  PAGEREF
_Toc221940776 \h  58 

Table 30  Summary of Risk to Listed Terrestrial Animals	  PAGEREF
_Toc221940777 \h  60 

Table 31.  Listed birds potentially at risk from fomesafen	  PAGEREF
_Toc221940778 \h  62 

Table 32.  Listed reptiles and amphibians potentially at risk from
fomesafen	  PAGEREF _Toc221940779 \h  63 

Table 33  Summary of Risk to Listed Plants	  PAGEREF _Toc221940780 \h 
64 

Table 34  Endangered Plants by Crop and State	  PAGEREF _Toc221940781 \h
 67 

Table 35  Probability of Individual Effects	  PAGEREF _Toc221940782 \h 
69 

Table 36  Summary of Direct and Indirect Effects	  PAGEREF _Toc221940783
\h  71 

 

1.0	Executive Summary

1.1	Nature of Stressor

Fomesafen is an herbicide.  It is applied as a foliar spray (both
pre-emergent and post-emergent) for control of broad-leaved weeds,
grasses, and sedges.  Mode of action is via cellular membrane
disruption.  It is highly persistent in soil (aerobic soil metabolism
half-lives of 29-99 weeks, dependent on soil type) resulting in a
potential for accumulation in terrestrial environments.  The label
suggests not planting sensitive crops in a fomesafen-treated field for a
3-18 month period, due to the persistence of fomesafen in the soil.
Additionally, it is highly mobile, and is expected to leach into
groundwater and be transported from the site via runoff into surface
waters.  Based on physical properties, bioaccumulation and long-range
transport are not expected to be of concern.  It is extremely toxic to
terrestrial plants, especially dicots, but of fairly low acute toxicity
to fish and wildlife.  Some chronic reproductive effects have been noted
in mammals, and may also occur in birds. No major degradates of
toxicological concern have been identified.

Potential Risk 

Chemical Properties 

Fomesafen is highly persistent and mobile in soil.  These environmental
fate properties are expected to promote year-to-year accumulation in
soil as well as off-site movement by leaching and runoff.  Because
fomesafen is spray applied, there is a potential for drift onto
non-target plants.  Prolonged phytotoxic effects on non-target plants
are expected based on the persistence of fomesafen.  EFED has no data
from which to determine how long it may be toxic, but the labels
recommend not planting sensitive crops in the use site for 3 to 18
months following treatment.

Ecological Risk Conclusions

Ecologically, the organisms most at risk from fomesafen are terrestrial
plants, especially dicots.  Because terrestrial plants are important
both ecologically (they provide a critical part of both the structure
and function that defines “habitat”) and economically (nearby
non-target, non-treated crop plants may be affected), these potential
impacts are an important consideration.  No LOCs were exceeded for
aquatic endpoints except the listed species LOC for freshwater
non-vascular plants.  At the time of this assessment, there were no
listed non-vascular freshwater plants, and no listed species had been
identified as having an obligate relationship with freshwater
non-vascular plants.  For terrestrial organisms, chronic LOCs were
exceeded for birds (and by extension, reptiles and amphibians) at all
but the lowest application rate.  Chronic LOCs were exceeded for mammals
only for small herbivorous mammals at the highest application rate. 
These LOC exceedences apply to both listed and non-listed species. 
Based on spray drift estimations, clearance distances for chronic
exceedences are well within the clearance distances for terrestrial
plants, thus if terrestrial plants are protected, then by virtue of
sensitivity, other vulnerable organisms should be protected as well. 
Clearance distances for chronic effects on birds, reptiles, amphibians,
and mammals are 10 ft from the application source for ground
applications (based on low boom estimates) and 100 ft for aerial
applications (based on application parameters used in AgDrift Tier I
estimates).  For terrestrial plants, using drift estimates based on the
more sensitive dicots, effects should be anticipated as far as 850 ft
for ground applications, and 1,000 ft for aerial applications.

Endangered Species Assessment

For listed animals, both aquatic and terrestrial, the primary risk posed
by use of fomesafen as currently registered under Section 3 is due to
potential degradation of plant communities providing food, shelter, or
protection from predators.  On the basis of these indirect effects and
the anticipated magnitude of such effect, an overall determination of
may affect, likely to adversely affect applies to all listed species
located with 850 ft of the application location.  The action area, based
on the furthest extent at which an LOC is exceeded (dicots), is 1,000 ft
away from agricultural land in geographic areas where fomesafen is
registered for use.  A list of potentially affected species is included
as Appendix F.  No direct effects are anticipated for aquatic organisms,
constituting a no effect determination for these organisms on the basis
of direct effects.  Based on available data, there is a chronic risk to
birds, reptiles, and terrestrial-phase amphibians.  The Agency is unable
to evaluate the potential magnitude of these chronic effects, thus the
overall determination for these taxa is may affect, likely to adversely
affect.



≤100 ft

Aerial ≤100 ft

from point of application	Yes

Potential for effects on other plants in the community.  Alteration of
habitat may create environment unsuitable to the listed species.

Effects may occur up to

Ground ≤300 ft

Aerial ≤900 ft

from point of application	No?

(only listed monocot affected is aquatic)

Dicots	Other1	Yes

Ground ≤300 ft

Aerial ≤900 ft

from point of application

No

(No potentially affected species have designated critical habitat)

	Dicots

	Yes

(6 potentially affected species have designated critical habitat)

Birds	Birds	Yes

Chronic Exceedences

Ground ≤10 ft

Aerial ≤100 ft

from point of application	Yes

Potential for effects on other plants in the community.  Alteration of
habitat may create environment unsuitable to the listed species.

Effects may occur up to

Ground ≤300 ft

Aerial ≤900 ft

from point of application	Yes

Potential for effects on other plants in the community.  Alteration of
habitat may create environment unsuitable to the listed species.

Effects may occur up to

Ground ≤300 ft

Aerial ≤900 ft

from point of application

	Reptiles





Terrestrial Phase Amphibians



	Mammals	Mammals



	FW Aquatic Plants2	FW Aquatic Plants	No

No LOC exceedences



SW Aquatic Plants	SW Aquatic Plants



	FW Aquatic Invertebrates	FW Crustacea





FW Bivalves





FW Gastropods



	FW Fish	FW Fish





Aquatic Phase Amphibians



	SW Aquatic Invertebrates	SW Crustacea





SW Bivalves





SW Gastropods



	SW Fish	SW Fish



	1 Cycads, Conifers, Fern Allies. These genera have no direct corollary
test organism, and have been evaluated based on the most sensitive plant
endpoint.

2 Evaluated based on both non-vascular plants (algae) and vascular
plants (duckweed)

2.0	Problem Formulation

Problem formulation provides a strategic framework for the risk
assessment.  By identifying the important components of the problem, it
focuses the assessment on the most relevant chemical properties,
exposure routes, and endpoints.

Stressor Description

Fomesafen is applied as a pre-plant, pre-emergence, and post-emergence
herbicide in soybeans, snap beans, dry beans, and cotton for control of
broadleaf weeds, grasses, and sedges. Fomesafen can be applied via
ground and aerial sprays. Because fomesafen is persistent in soil
(aerobic soil degradation t1/2 = 29 to 99 weeks at 0.50 lb ai/A
application rate; MRID 00135660), residual in soil of the treated field
is considered in this risk assessment as a secondary source.

Figure   SEQ Figure \* ARABIC  1  Chemical structure of fomesafen

Empirical formula:	C15H10ClF3N2O6S

Molecular weight:	438.77 g/mole

CAS Registry Nos.:	72178-02-0

Chemical Class:	Diphenyl ether

Environmental Fate Summary

Major routes of fomesafen dissipation are leaching, runoff, and
microbial degradation. Because fomesafen is persistent and mobile in
soil, it is expected to move from the application site into groundwater
and surface water. Additionally, off-site movement of fomesafen is
expected through spray drift from aerial and ground spray. The high
persistence of fomesafen is expected to contribute to year-to-year
accumulation in terrestrial and aquatic environments. 

Fomesafen is stable to abiotic hydrolysis. It undergoes slow
photodegradation in water

(t1/2 = 49 to 289 days). Fomesafen is persistent (aerobic soil t1/2 = 29
to 99 weeks) in aerobic soil and aquatic environments. However, it
degrades rapidly (t1/2 <20 days) in anaerobic environments. The major
degradation product of fomesafen is
5-(2-chloro-(,(,(-trifluoro-p-tolyloxy)-N-methylsulphonyl-panthranilamid
e (fomesafen amine). A minor degradation product is
5-(2-chloro-(,(,(-trifluoro-p-tolyloxy) anthranilic acid (fomesafen
amino acid). Neither degradate has been identified as a toxicological
concern. 

Fomesafen is expected to be very mobile in soil. Simple partitioning
coefficients range from 0.51 in loamy coarse sand to 2.45 in sandy clay
loam soil. Regression analysis indicates fomesafen sorption is not
dependent on soil organic matter content. Aged soil column leaching
studies indicate degradation products of fomesafen are not mobile in
soils; less than 0.06% of applied radioactivity was detected in the
leachate samples.

Field dissipation studies in NC, IL, MS, AR, AL, TX, LA, SD, MN, KY, IA,
and MO indicate fomesafen is moderately persistent to persistent (t1/2 =
50 to 150 days ) in surface soils under actual use conditions. Fomesafen
was detected at depths up to 30 inches in the soil profile. Fomesafen
amine was the only degradation product identified in field dissipation
studies. Prospective ground water monitoring in NC indicates fomesafen
moved through the soil profile into medium and deep ground water.

Fomesafen has a low potential for bioaccumulation in fish tissues.
Bioaccumulation factors for fosmesafen were 0.7 for whole fish, 0.2 for
edible tissues, and 5.2 for nonedible tissue. Bioaccumulated residues
decreased by 95% during a 14-day depuration period.

 2.3	Mode of Action

Fomesafen is a diphenyl ether. It disrupts the cell membrane of the
plant (  HYPERLINK "http://www.syngentacroprotection-us.com" 
www.syngentacroprotection-us.com ) by penetrating into the cytoplasm and
causing formation of peroxides and free electrons
(http://www.ces.purdue.edu/extmedia/WS/WS-23-W.html). The specific mode
of action is inhibition of protoporphyrinogen oxidase (Roberts 1998 
HYPERLINK http://www.weeds.iastate.edu)  ) . Fomesafen generally acts
quickly, and does not translocate. It has both foliar and soil activity.
Other herbicides in this group include aciflourfen, lactofen, and
oxyfluorfen.

2.4	Use Characterization

Fomesafen is used primarily as a pre-plant, pre-emergence, and
post-emergence herbicide to control broadleaf weeds, grasses, and sedges
in soybeans, snap beans, dry beans, and cotton. Methods of application
are ground spray and aerial spray (maximum 0.375 lb ai/A, soybeans, dry
beans, snap beans, and cotton). Application is limited to once a year,
or in alternate years, depending on location. Application rates are
regionally specific.

A search of OPPIN on 4/24/2008 (PDD) located 20 active Section 3 and
Section 24 registration numbers associated with the active ingredient
fomesafen. Of these, 5 were end-use products, 4 were technicals or
formulation intermediates (with no associated crops), and 11 were
state-specific special local needs (Sec. 24c), all of which were
associated with a single parent Section 3 label. Only 2 registrants
(Syngenta and BASF) hold current fomesafen registrations, and as of this
writing, BASF has submitted a Request for Voluntary Cancellation for its
fomesafen containing products.  Three of the end-use products include a
second active ingredient.



Table   SEQ Table \* ARABIC  2   Current Fomesafen Registrations

Product Name

(Registrant)	EPA Registration Number

(latest label date)	Active Ingredients

(% w/w)	Crops

Section 3 End Use Products

Reflex

(Syngenta)

Emulsifiable concentrate	100-993

(02/08/08)	Fomesafen 22.8%	Cotton, dry beans, snap beans, soybeans

Flexstar

(Syngenta)

Emulsifiable concentrate	100-1101

(03/20/07)	Fomesafen 22.1%	Soybeans

Prefix

(Syngenta)

Emulsifiable concentrate	100-1268

(4/13/07)	Fomesafen 10.2%

s-metolachlor 46.4%	Soybeans

BAS 530 04

(BASF)

Soluble concentrate	7969-82

10/22/97	Fomesafen 12.9%

Bentazon 29%	Soybeans

Faster

(BASF)

Soluble concentrate	7969-83

10/22/97	Fomesafen 7.2%

Bentazon 29.8%	Soybeans

Section 24 Registrations

Reflex

(Syngenta)

Emulsifiable concentrate	AL030003 AR030006 GA880005 MS980002 NC950010
SC030006 TX040002	Fomesafen 22.8%	Pine seedlings in nurseries

	NC870005

SC900004

Soybeans, idle cropland

	SC900004

Soybeans, idle cropland, non cropland

(USDA eradication program only)

	NE060002

Dry beans

	AR080004

Cotton

Section 3 Technicals and Formulation Intermediates

Fomesafen paste	100-1016	Manufacturing intermediates with no registered
crop uses.  Not anticipated to be environmentally relevant except in
case of spill.

Fomesafen technical	100-1017

	Fomesafen salt aqueous concentrate	100-1092



100-1103

	

2.5	Assessment Endpoints

Assessment endpoints are selected based on ecosystems typically at risk
from pesticide applications.  Specific ecological effects are evaluated
based on toxicity information from guideline tests and open literature
data, and focus on the general categories of survival, growth, and
reproduction.  Information regarding sub-lethal effects, if available,
is discussed in the risk characterization.  EFED assesses behavioral or
biochemical endpoints if they are quantitatively linked to effects on
survival or fecundity.

Table   SEQ Table \* ARABIC  3   Summary of Assessment Endpoints and
Measures of Ecological Effect

Assessment Endpoint	Measures of Ecological Effecta

Aquatic Environments

1.  Survival, growth, and reproduction of fish and aquatic phase
amphibians	Freshwater

1a.  Rainbow trout acute LC501

1b.  NOAEC estimated from sheepshead minnow ACR1

Saltwater

1c.  Sheepshead minnow acute LC501

1d.  Sheepshead minnow chronic NOAEC

2.  Survival, growth, and reproduction of aquatic invertebrates
Freshwater

2a.  Water flea EC501

2b.  Water flea chronic NOAEC1

Saltwater

2c.  Mysid shrimp acute EC501

2d.  Mysid shrimp chronic NOAEC1

3.  Survival, growth, and reproduction of aquatic plants	Freshwater

3a.  Non-vascular plant (freshwater algae) acute EC501 and NOAEC1

3b.  Non-vascular plant (freshwater algae) acute EC502 and NOAEC

Saltwater

3c.  Non-vascular plant (saltwater diatom) acute EC502 and NOAEC3

Terrestrial Environments

4.  Survival, growth, and reproduction of mammals	4a.  Guinea pig acute
LC501

4b.  Rat chronic NOAEC1

5.  Survival, growth, and reproduction of birds, terrestrial phase
amphibians, and reptiles	5a.  Mallard duck acute oral LC501

5b.  Mallard duck acute dietary LC501

5c.  Mallard duck chronic NOAEC1

6.  Survival, growth, and reproduction of terrestrial invertebrates	6a. 
Honey bee acute contact LC50

7.  Survival, growth, and reproduction of terrestrial plants	7a. 
Monocot (onion) seedling emergence EC251

7b.  Dicot (radish) vegetative vigor EC251

a  All toxicity data reviewed for this assessment are tabulated in
Appendix B.

1  Guideline study

2  ECOTOX study

2.5.1	Ecosystems Potentially at Risk

For typical fomesafen applications, the ecosystem at risk is the
application site itself, including organisms that might be sprayed
during application, organisms affected by residual fomesafen in the
soil; and the adjacent aquatic and terrestrial environments affected due
to runoff, spray drift, or groundwater contamination.  In water bodies
receiving runoff from the treatment site, fish, aquatic-phase
amphibians, aquatic invertebrates, and aquatic vascular and non-vascular
plants are considered.  Terrestrial organisms assessed include
non-target plants, insects, amphibians, reptiles, birds, and mammals. 
Because fomesafen is an herbicide, potential affects on non-target
plants have been addressed at length.  

2.5.2	Ecological Effects

Evaluation of ecological effects focuses initially on direct effects to
the groups of organisms residing in the ecosystems at risk, based on
ratios (risk quotients) of the estimated environmental concentration
(EEC) to a designated toxicity endpoint for a surrogate test organism. 
If pre-established levels of concern (LOCs) are exceeded for direct
effects, indirect effects to endangered species (e.g., food chain,
decrease in community diversity) are evaluated based on the group of
organisms exceeding the LOC.  Details on the RQ method and LOCs are in
Appendix G.  

2.5.2.1	Direct

Direct effects evaluated are the survival, growth, and reproduction of
various taxa of organisms potentially exposed to fomesafen.  Taxonomic
groups evaluated include aquatic plants (algae and vascular), aquatic
invertebrates, aquatic vertebrates, terrestrial plants, terrestrial
invertebrates, birds, and mammals.  There are currently no guideline
tests for reptiles or amphibians, so these taxa are evaluated using bird
data as a surrogate for reptiles and terrestrial phase amphibians, and
fish as a surrogate for aquatic phase amphibians.  Both acute and
chronic effects are considered.

2.5.2.2	Indirect

When herbicides are applied, indirect effects may include a decline in
primary productivity, or change in composition of plant communities
proximate to the treated area or systems (wetlands and water bodies)
receiving runoff from the site.  If LOCs are exceeded for any taxa,
potential indirect effects to endangered species are assessed.

 Figure   SEQ Figure \* ARABIC  2   Conceptual model for fomesafen
effects2.6	Risk Hypotheses

(	Fomesafen transported in runoff from treated areas may affect the
survival, growth, or reproduction of aquatic plants, aquatic
invertebrates, aquatic-phase amphibians or fish.

(	Fomesafen may affect the survival, growth, or reproduction of
non-target plants proximate to the treatment site.

(	Fomesafen residues in plant and animal dietary sources may affect
growth, survival, or fecundity of birds, terrestrial-phase amphibians,
or small mammals ingesting these materials.

(	Fomesafen residues on plants may affect survival of terrestrial
invertebrates.

2.7	Results of Previous Assessments

A Section 3 new use ecological risk assessment was conducted for
fomesafen in 2006 (DP302766) when it was proposed for use on cotton, dry
beans, and snap beans.  Two proposed rates (0.5 lb ai/A, ground only)
and 0.375 lb ai/A (ground and aerial) were evaluated.  An alternative
lower rate (0.2 lb ai/A) was also evaluated.

Key findings of this assessment included:

(	The greatest acute risk associated with fomesafen use was for
non-target terrestrial plants.  

(	The persistence and mobility of fomesafen in soil and the persistence
in aquatic environments is a concern. 

(	Accumulation in the soil of a field repeatedly treated with fomesafen
may adversely affect crops subsequently planted in the field.  Effects
from a single treatment may persist for 3-18 months.

(	Concentrations of fomesafen in shallow groundwater used for irrigation
purposes may be high enough to adversely affect crops subsequently
planted in the field.

(	Fomesafen is practically non-toxic to slightly toxic to aquatic
animals, both freshwater and estuarine/marine.  No adverse effects to
aquatic animals are anticipated based on proposed application rates.

(	Fomesafen does exert toxic effects on aquatic plants but risk
quotients (RQs) for the scenarios modeled were below the level of
concern (LOC).

(	Fomesafen is practically non-toxic to slightly toxic to birds and
mammals on an acute basis.  Chronic reproductive effects were noted in
rats.  A chronic LOAEC for birds was not established.  No acute risk
LOCs were exceeded, but acute endangered species LOCs were exceeded for
small mammals at application rates of 0.5 and 0.375 lb ai/A.  Some
chronic RQs for both birds and mammals exceeded the LOC at all
application rates.  The meaning of the exceedence for birds is
uncertain, as the guideline study submitted did not determine a LOAEC. 
Better data may significantly affect the chronic risk picture for birds.

Endangered Species

(	Based on LOC exceedences, the following taxa of endangered species
were identified as potentially being at risk from fomesafen use:
amphibians (terrestrial phase), birds, dicotyledon plants, mammals,
monocotyledon plants, and reptiles

(	Fomesafen is likely to affect plants near the treated areas, with
potential effects extending to >900 ft away from the treatment source in
the case of aerial application.  Direct effects (reduction of growth,
survival, or fecundity) may occur for endangered plants in the drift
zone.  Effects on non-endangered plants in the drift zone may constitute
indirect effects (reduction of food or cover) to endangered animals.

Fomesafen was registered for use on all proposed crops, with a maximum
application of 0.375 lb ai/A via both aerial and ground applications.

2.8	Analysis Plan

This assessment was conducted in accordance with the methods, and using
the models described in the Overview Document (USEPA 2004).  Some
additional methods were used to more specifically determine which listed
species might be at risk as a result of fomesafen use.  These methods
build on existing models and were as follows:

●	Terrestrial animals were grouped into “Kenaga categories” based
on diet and size information available in the natureserve database ( 
HYPERLINK "http://www.natureserve.org"  www.natureserve.org ) and
species recovery plans developed by the Services in order to determine
which animals were likely to be at risk.

●	The AgDrift model was used to determine how far away from the point
of application that estimated fomesafen concentrations on terrestrial
food items were high enough for RQs to exceed LOCs.  The point at which
the concentration is low enough that the RQ drops below the LOC is
referred to as the “clearance estimate” and is presented in the
appropriate tables.

3.0	Exposure Assessment

EFED conducted the exposure assessment using standard exposure modeling
methods, as described in the Overview Document (USEPA 2004).

3.1	Label Application Rates and Intervals

Fomesafen is registered under Section 3 as a pre-plant, pre-emergence,
and post-emergence herbicide for control of broadleaf weeds, grasses,
and sedges in soybeans, cotton, snap beans, and dry beans.  Additional
uses covered under Section 24c (special local needs, or SLN)
registrations are for use on pine seedlings in nurseries (AL, AR, GA,
MS, NC, SC, TX), for control of weeds in dry beans in Nebraska, and for
control of witchweed in soybeans and idle cropland in North Carolina and
South Carolina.  Use in South Carolina also includes non-cropland,
although the South Carolina uses are limited to areas included in the
USDA witchweed eradication program.

Section 3 labels belonging to the primary registrant, Syngenta, include
regionally specific application rates, shown in Table 1.  Based on these
labels, fomesafen can be applied via aerial and ground spray at a
maximum application rate of 0.375 lbs ai/A.  Section 3 labels belonging
to BASF do not provide regionally specific application rates, but “are
intended for use” in the areas included in Regions 1-4, and
application rates (0.19- 0.23 lb ai/A) are lower than those on the
Syngenta labels.

Table   SEQ Table \* ARABIC  4   Label Application Rates and Intervals
for Fomesafen Use on Soybeans, Cotton, Snap Beans and Dry Beans1

Region	States in Region	App Rate (lbs/A)	Application Interval

1	AL, AR, GA, LA, MS, MO2, NC, OK2, SC, TN, TX2	0.375	1 year

2	DC, DE, IL2, IN2, KY, MD, , OH2, PA3, WV, VA, 	0.375	2 year

3	CT, IA, ME, MA, MI3, NH, NJ, NY, PA3, RI, WI, VT	0.312	2 year

4	KS2, MI3, MN2, ND3, NE2 SD3, WI2	0.25	2 year

5	ND3, MN3, SD3	0.170	2 year

1REFLEX 2.5 Gallon( (EPA Reg. No. 100-993)

2Does not include entire state

3Portions of state are in multiple regions

Application rates on some of the Section 24c labels (pine seedling use,
also belonging to the primary registrant) are slightly higher, with a
maximum application rate of 0.5 lbs ai/A for pre-emergence applications.
 The higher rate does not apply in all states.  States included under
pine seedling uses are in Region 1 as defined on the parent label,
although the Section 24c label for Texas is assumed to include the
entire state. 

Table   SEQ Table \* ARABIC  5   Label Application Rates and Intervals
for Section 24c Uses of Fomesafen

Use Site	States	Application Technique	Max App Rate (lbs ai/A)
Application Interval

Pine seedlings in nurseries	AR, GA, MS, NC, SC,	Aerial or Ground 	0.5	1
year

	AL, TX	Aerial or Ground	0.375	1 year

Soybeans, idle cropland, non-cropland	SC (Horry and Marion counties)
Aerial or Ground	0.375	1 year

Soybeans, idle cropland	NC (Robeson, Cumberland, Sampson, Bladen, and
Pender counties)	Aerial or Ground	0.375	1 year

Dry beans	NE	Aerial or Ground	0.25	2 years

1 Based on areas currently infested with witchweed, as noted on  
HYPERLINK "http://www.ncagr.com/plantindustry/plant/weed/witchnc.htm" 
www.ncagr.com/plantindustry/plant/weed/witchnc.htm , accessed May 16,
2008

3.2	Aquatic Exposure

Tier II EFED aquatic exposure modeling uses the linked Pesticide Root
Zone Model and Exposure Analysis Model System (PRZM/EXAMS).  PRZM uses
the chemical’s physical and environmental fate properties and the site
characteristics to predict the concentration of pesticide in runoff and
entrained sediment from the field.  EXAMS estimates the concentration of
pesticide in an edge-of-field small water-body receiving runoff from the
field.  The water-body has a constant volume (20 million liters) with no
outflow and is intended to represent an upper-end occurrence
concentration.

3.2.1	PRZM-EXAMS Modeling Inputs and Scenario Selection

The aquatic exposure assessment for fomesafen was conducted to assess
use on soybeans, dry beans, snap beans, and cotton. The Mississippi
soybeans scenario was used as both a scenario representing MS soybeans
as well as a surrogate for dry beans and snap beans, as EFED currently
has no standard scenarios for these crops in this region. Standard
scenarios were selected to assess runoff potential from vulnerable use
sites in MS (soybean and cotton), NC (cotton), and TX (cotton). The MI
beans scenario from region 4 was selected to provide more geographical
balance to the analysis since all of the other scenarios occur in region
1. No other EFED scenarios had combinations of crop and location
relevant to this assessment. Input parameters for fomesafen were
selected according to EFED Input Parameter Guidance for PRZM/EXAMS1.
Input parameters are shown in   REF _Ref210113708 \h  \* MERGEFORMAT 
Table 6 .



Table   SEQ Table \* ARABIC  6 .  Input Parameters for PRZM-EXAMS
Modeling of Fomesafen on Cotton, Soybeans, Dry Beans, and Snap Bean

Parameter	Value	Comments	Source

Application Rates (kg ai/ha)	0.19 - 0.56	Varies by Region	Label1

Molecular Weight (grams/mole)	420

EPA 2020220

Solubility (mg/L)	1200	@pH = 7; 200c	MRID 45048207

Vapor Pressure (torr)	<7.5 × 10-7	@ 50oC	HSDB

Henry’s Constant (atm m3/mol) 	7.5 × 10-13	Estimated	HSDB

Kd (L/kg)	0.68	Lowest non-sand Kd	Acc. No. 259413

Aerobic Soil Metabolism Half-life (days)	511	Upper 90th percentile of
mean2	Acc. No. 071059

Acc. No. 00135660

Aerobic Aquatic Metabolism Half-life (days)	129.4	Upper 90th percentile
of mean3	Acc. No. 72158

Anaerobic Aquatic Metabolism Half-life (days)	1000	Conservative
Assumption 	No Data Available

Photodegradation in Water (days)	289	@pH = 7	MRID 40451101

Hydrolysis Half-life (days)	Stable	@pH = 7	Acc. No. 071059

1 Reflect application rates on the REFLEX 2LC, REFLEX 2.5, and REFLEX
labels

2 Calculated from half-lives of 187.6, 630, 57, 693, 349.3, 527.1, 207
days using a mean of 387.84 days and standard deviation of 242.90 days.

3 Calculated from half-lives of 139.9, 60.9, 92.4, and 115.5 days using
a mean of 102 days and standard deviation of 33.44 days.

The MI beans scenario from region 4 was selected to provide more
geographical balance to the analysis since all of the other scenarios
occur in region 1. No other EFED scenarios had combinations of crop and
location relevant to this assessment. Because applications in Region 4
are restricted to every other year, a modified copy of the PE5 shell was
created to only apply the pesticide in alternate years (odd years). This
can be seen in the Appendix A PRZM/EXAMS outputs for Michigan beans in
which the even year EECs are always lower than the odd years.

3.2.2	PRZM-EXAMS Modeling Output

For aerial applications (  REF _Ref210113803 \h  \* MERGEFORMAT  Table 7
), peak 1 in 10 year estimated environmental concentrations (EECs)
ranged from 2.3 ppb (beans, MI) to 12.0 ppb (cotton, TX). Chronic
1-in-10 year (21-day average and 60-day average) EECs ranged from 1.7
ppb (beans, MI, 60-day average) to 11.4 ppb (cotton, MS &TX, 21-day
average).

Table   SEQ Table \* ARABIC  7 .  PRZM-EXAMS Aquatic EECs for Fomesafen

Region	Crop	State	App. Date 	Aerial/ Ground 	Peak	21 days	60 days





	(g/L (ppb)

Region 1: Annual Applications at 0.375 lb a.i/A

1	Soybean	MS	5/1	A	8.99	8.57	7.74





G	8.19	7.77	6.95

1	Cotton	MS	5/15	A	11.83	11.37	10.07





G	11.20	10.79	9.56

1	Cotton	NC	5/10	A	8.99	8.72	8.03





G	8.20	7.96	7.34

1	Cotton	TX	5/10	A	11.96	11.39	10.31





G	11.44	10.90	9.85

Region 4: Every-other-year Applications at 0.28 lb a.i/A

4	Beans	MI	6/15	A	2.27	2.15	1.94





G	2.37	2.25	2.02



Peak 1-in-10 year EECs for ground spray applications (  REF
_Ref204412645 \h  \* MERGEFORMAT  Table 8 ) ranged from 10.9 ppb
(cotton, NC) to 15.3 ppb (cotton, TX).  Chronic 1 in 10 year (21-day
average and 60-day average) concentrations ranged from 9.8 ppb (cotton,
NC, 60-day average) to 14.5 ppb (cotton, TX, 21-day average).

Table   SEQ Table \* ARABIC  8   PRZM-EXAMS EECs for Fomesafen at 0.50
lb ai/A

Region	Crop	State	App. Date	Peak	21 days	60 days





(g/L 

1	Cotton	MS	5/15	14.9	14.4	12.7

1	Cotton	NC	5/10	10.9	10.6	9.8

1	Cotton	TX	5/10	15.3	14.5	13.1

1- Concentrations were derived for 0.50 lb ai/A using ground spray 

3.2.3	Registrant-submitted Aquatic Exposure Modeling

The registrant submitted Tier II PRZM/EXAMS modeling assessments for
fomesafen use on cotton and soybeans (MRID 450482-04, 450482-05,
450482-06).  The modeling scenarios used were developed to assess
fomesafen runoff from vulnerable use sites (Hydrologic D soils) with
high rainfall.  Selected scenarios represent sites in Tensas County, LA
(MRLA 131) for cotton; Leflore, MS (MRLA 131) for soybeans; and Dodge,
NE (MRLA 102B) for soybeans, and Sheboygan, WI (MRLA 95B).  Maximum
application rates were 0.31 lbs for snap beans, 0.5 lbs ai/A for cotton,
and 0.375 lbs ai/A for soybeans.  Only ground spray was considered,
although the labels allow aerial spray.  The sources (study
identification numbers) of environmental fate data are not reported. 
Additionally, there are no explanations for selection of the
environmental fate data in the exposure assessment.  The registrant
estimated environmental concentrations are similar in magnitude to, but
slightly higher than, those calculated by EFED.

3.2.4	SCIGROW Modeling for Ground Water

Because fomesafen is mobile and persistent in soil, a screening level
groundwater assessment using SCIGROW (ver. 2.3) was conducted to
estimate the concentration of fomesafen in shallow groundwater, which
could potentially be used for crop irrigation.  Input parameters for
SCIGROW are listed in Table 10.

Table   SEQ Table \* ARABIC  9 .  Input Parameters for SCIGROW Modeling
for Fomesafen

Parameter	Value	Comments	Source

Application Rate (kg ai/ha)- Cotton	0.375 – 0.17	Varies by Region
Label1

Koc (L/kg)	68	Estimated2	Acc No. 259413

Aerobic Soil Metabolism Half-life (days)	387.84	Mean3	Acc No. 071059

Acc. No. 00135660

1-Reflect maximum application rates on the REFLEX 2LC, REFLEX 2.5 and
REFLEX labels

2-Koc estimated using Kd/SOC=Koc; where Kd=0.68 and SOC=1% SOC
percentage

3-Calculated from half-lives of 187.6, 630, 57, 693, 349.3, 527.1, 207
days using a mean of 387.84 days and standard deviation of 242.90 days. 

Based on the SCIGROW estimate, the concentration of fomesafen in shallow
ground water in sand soils (  REF _Ref221071702 \h  \* MERGEFORMAT 
Table 10 ) is not expected to exceed 5.01 (g/L (Region 1).

Table   SEQ Table \* ARABIC  10  Label Application Rates and Intervals
for Fomesafen Use on Soybeans, Cotton, Snap Beans, and Dry Beans1

Region	Application Rate (lbs/A)

(Application Interval)	SCIGROW-estimated Groundwater Concentrations
(µg/L)	Fomesafen Application Due Solely to Irrigation (lbs ai/A)

1	0.375 (1 year)	5.01	2.27 × 10-3

2	0.375 (2 year)	2.5	1.13 × 10-3

3	0.312 (2 year)	2.08	9.42 × 10-4

4	0.25 (2 year)	1.67	7.56 × 10-4

5	0.17 (2 year)	1.14	5.16 × 10-4

1REFLEX 2.5 Gallon( (EPA Reg. No. 100-993)

Because fomesafen is expected to leach to groundwater, EFED has
calculated the maximum application rate of fomesafen from two inches of
irrigation water. This calculation assumes that two inches of irrigation
water is required for optimum plant growth.  The application rate of
fomesafen in terms of lbs ai/A in 2 inches of groundwater is calculated
as follows:

 

where: 

fomesafen is the estimated application rate of fomesafen in lbs ai/A in
2 in/A of groundwater; and

EEC is the region-specific SCIGROW EEC in groundwater from Table 5.

Based on two inches of irrigation and the SCIGROW estimate, the
application rate of fomesafen is estimated to vary from 0.00227 to
0.000516 lbs ai/A.

3.2.5	Soil Accumulation

Because of the persistence of fomesafen in soil, a screening level
assessment was conducted to quantify the accumulation of fomesafen
residues in soil.  This screening-level assessment does not consider
loss of pesticide to run-off and leaching (only degradation by aerobic
soil metabolism is considered). A first-order decay model was used to
estimate fomesafen soil concentrations over 20 years. This model is
based on first-order decay of a single application:

 

where: A is the soil fomesafen concentration at any point in time; A0 is
the original soil fomesafen concentration at the time that it was
applied; k is the upper 90th percentile of the mean aerobic soil
metabolism half-life (t1/2 = 511 days; k = 1.356452 × 10-3 days-1),
which was used to represent the microbial mediated decay rate of
fomesafen in soil; and t is the time since the fomesafen application.

Because multiple applications occur over this 20 year timeframe, this
equation is modified to account for multiple applications:

 

where: i is a counter variable that denotes the first fomesafen
application when i = 1 and the second when i = 2, etc.; n is the last
application; A0,i is the soil fomesafen concentration contributed by the
ith application; and ti is the time since the ith fomesafen application.

The soil fomesafen concentration contributed to the upper 15 cm of soil
by the ith application (A0,i) in mg/Kg is calculated as:

 

where: AppRate is the regional maximum application rate from Table 3 and
density is the bulk density of soil. The bulk density of soil varies
from 1.0 g/cm3 for clay soils to 1.8 g/cm3 for sandy or compacted soils
(  HYPERLINK "http://www.cdpr.ca.gov/docs/emon/pubs/sops/fsso001.pdf" 
http://www.cdpr.ca.gov/docs/emon/pubs/sops/fsso001.pdf ). The modeling
scenario assumes that 100% of fomesafen residue is applied to the soil
as recommended for a pre-emergent application.  The model scenario also
assumes that microbial degradation is the only route of dissipation from
the application site. These assumptions are expected to exaggerate
predicted formesafen soil concentrations.

  REF _Ref221072091 \h  \* MERGEFORMAT  Figure 3  illustrates the
fomesafen concentrations in soil reach a plateau after approximately 10
years regardless of the application rate or soil bulk density.  An
application rate of 0.375 lbs/A applied every year (Region 1) can
theoretically result in a maximum fomesafen concentration of 0.71 mg/kg
in soils with a low bulk density (1.0 g/cm3).  The same application rate
(0.375 lbs ai/A applied every year) can theoretically result in a
maximum fomesafen concentration of 0.4 mg/kg in soils with a high bulk
density (1.8 g/cm3). Applying fomesafen every other year (Region 2 to 5)
and at lower application rates also reduces residual soil fomesafen
concentrations.



Figure   SEQ Figure \* ARABIC  3 . Estimate of Fomesafen Loading in the
Surface Soil (0-15 cm depth) in Clay Soils (a; bulk density = 1.0 g/cm3)
and Sandy or Compacted Soils (b; bulk density = 1.8 g/cm3) of Regions 1
through 5.

3.3	National Surface Water Monitoring Data

3.3.1	Surface Water

The USGS National Water Quality Assessment (NAWQA) database was accessed
(6/9/08, SPW).  No data for fomesafen was located in the database, but
this appears to be because fomesafen is not included in the schedules of
chemicals quantified by the laboratory.  Therefore, a lack of data
should not be construed as meaning there are no detectable fomesafen
residues in surface waters.

3.3.2	Ground Water

g/L (at 4 months) to 17g/L (at 1 month).  It was detected at a
concentration of 1 g/L in the medium- to deep-depth wells.

These observed porewater concentrations are much higher than the SCIGROW
EECs for groundwater. Using the porewater concentrations of 1 mg/L and
17mg/L (from the groundwater study) as outer bounds of the fomesafen
groundwater concentrations that might be applied in irrigation water,
concentrations of fomesafen in irrigation water could range from 0.45 to
7.7 lbs ai/A, respectively.

3.4	Bird and Mammal Exposure (TREX)

EFED estimates exposure of birds and mammals using the Terrestrial
Exposure Model (TREX).  TREX uses the Kenaga nomagram, as modified by
Fletcher et al (1994) to determine pesticide residues on several
categories of food items, then calculates the potential dose an organism
might receive from ingesting contaminated items using allometric
equations.  Dose estimates are based on the upper bound dose and
assumptions that the organism exclusively eats one type of food item and
forages only in the treated and/or overspray areas.

Table   SEQ Table \* ARABIC  11   Input Parameters for TREX Modeling

Input Parameters	Value	Source

Application Rate	0.5 lb ai/A

0.375 lb ai/A

0.312 lb ai/A

0.25 lb ai/A

0.17 lb ai/A	Label

Reflex

100-993

Foliar Half-life	35 days	EFED Default

Number of Applications	1 per year	Label

Reflex

100-993

Avian LD50	5,000 mg/kg bw (mallard duck)	MRID 163168

Avian LC50	20,000 mg/kg diet (mallard duck)	MRID 163381

Avian NOAEC	46 mg/kg diet (mallard duck)	MRID 135639

Mammal LD50	607 mg/kg bw (guinea pig)	MRID 164901

Mammal NOAEC	1,000 mg/kd diet (rat)	MRID 144862



For birds, dose estimates for the 0.50 lb ai/A application rate range
from 2.1 mg/kg bwt (1000 g frugivores, granivores, and insectivores) to
134.0 mg/kg bwt (20 g herbivores).  At the 0.375 lb ai/A application
rate, estimated doses range from 1.6 mg/kg bwt (1000 g frugivores,
granivores, and insectivores) to 102.5 mg/kg bwt (1000 g fruit and
pods).  Dose estimates for the 0.17 lb ai/A application rate range from
0.7 mg/kg bwt (1000 g frugivores, granivores, and insectivores) to 46.5
mg/kg bwt (20 g herbivores).

Table   SEQ Table \* ARABIC  12   Bird Dose Estimates

Feeding Categories	Kenaga Upper Bound Dose (mg/kg bwt)

	Small

(20 g)	Medium 

(100 g)	Large

(1000 g)

0.50 lb ai/A Application Rate(pine seedlings, Region 1)

Short grass	133.93	76.38	34.19

Tall grass	61.39	35.01	15.67

Broadleaf plants/small insects	75.34	42.96 	19.23

Fruits/pods/seeds/large insects	8.37	4.77	2.14

0.375 lb ai/A Application Rate (Region 1 & 2)

Short grass	102.5	58.45	26.17

Tall grass	46.98	26.79	11.99

Broadleaf plants/small insects	57.66	32.88	14.72

Fruits/pods/seeds/large insects	6.41	3.65	1.64

0.17 lb ai/A Application Rate (Lowest Rate, Region 5)

Short grass	46.47	26.50	11.86

Tall grass	21.30	12.14	5.44

Broadleaf plants/small insects	26.14	14.90	6.67

Fruits/pods/seeds/large insects	2.90	1.66	0.74



For mammals dose estimates for the 0.50 lb ai/A application rate range
from 0.25 mg/kg bwt (1000 g granivore) to 112 mg/kg bwt (20 g short
grass).  At the 0.375 lb ai/A application rate, estimated doses range
from 0.2 mg/kg bwt (1000 g granivore) to 85.8 mg/kg bwt (20 g short
grass).  Dose estimates for the 0.17 lb ai/A application rate range from
0.1 mg/kg bwt (1000 g granivore) to 38.9 mg/kg bwt (20 g short grass).

Table   SEQ Table \* ARABIC  13   Mammal Dose Estimates

Feeding Categories	Kenaga Upper Bound Dose (mg/kg bwt)

	Small

(15 g)	Medium 

(35 g)	Large

(1000 g)

0.50 lb ai/A Application Rat e(Pine seedlings, Region 1)

Herbivores/Insectivores

Short grass	112.12	77.49	17.97

Tall grass	51.39	35.52	8.23

Broadleaf plants/small insects	63.07	43.59	10.11

Fruits/pods/seeds/large insects	7.01	4.84	1.12

Granivores

Fruits/pods/seeds/large insects	1.56	1.08	0.25

0.375 lb ai/A Application Rate (Region 1,2)

Herbivores/Insectivores

Short grass	85.81	59.30	13.75

Tall grass	39.33	27.18	6.30

Broadleaf plants/small insects	48.27	33.36	7.73

Fruits/pods/seeds/large insects	5.36	3.71	0.86

Granivores

Fruits/pods/seeds/large insects	1.19	0.82	0.19

0.17 lb ai/A Application Rate (Lowest Rate, Region 5)

Herbivores/Insectivores

Short grass	38.90	26.88	6.23

Tall grass	17.83	12.32	2.86

Broadleaf plants/small insects	21.88	15.12	3.51

Fruits/pods/seeds/large insects	2.43	1.68	0.39

Granivores

Fruits/pods/seeds/large insects	0.54	0.37	0.09



3.5	Terrestrial Invertebrate Exposure

g ai/g insect.  The fomesafen residue for a bee (µg ai/bee) is
calculated by multiplying the residue by the assumed weight of a honey
bee (0.128 g) to establish a dose per bee.  This method assumes that
contact is the relevant route of exposure, rather than ingestion.  This
method of estimation is believed to be adequate for fomesafen.

Table   SEQ Table \* ARABIC  14   Terrestrial Invertebrate Exposure

Application Rate

(lb ai/A)	Insect Size Category	EECs 

(mg ai/kg insect)	Dose per Bee

(g ai/bee)

0.50

(Pine seedlings, Region 1)	Small insects	67.50	8.64

	Large insects	7.50	0.96

0.375

(Regions 1,2)	Small insects	50.63	6.48

	Large insects	5.63	0.72

0.017 

(Region 5)	Small insects	22.95	2.94

	Large insects	2.55	0.32

3.6	Terrestrial Plant Exposure (TerrPlant & AgDrift)

Currently, EFED uses the TerrPlant Model (Version 1.2.1) to evaluate
exposure of terrestrial plants to pesticides applied on agricultural
fields.  In cases where spray drift may be of concern in the risk
assessment EFED also uses the AgDrift model.

3.6.1	TerrPlant

TerrPlant has two basic exposure scenarios.  The first is an adjacent
upland area, which is exposed to the pesticide via drift and dissolved
concentrations in sheet runoff.  The second is an adjacent semi-aquatic
(wetland) area, which is exposed to the pesticide via drift and to
dissolved concentrations in channelized runoff.  Drift is calculated as
a percentage of the application rate (1% for ground and 5% for aerial,
airblast, or spray chemigation) and is not adjusted for distance from
the application site.  The amount of dissolved pesticide in the runoff
component is estimated based on solubility of the active ingredient.  

Table   SEQ Table \* ARABIC  15   Terrestrial Plant Exposure

Application Method	Total Loading (Runoff + Drift) (lb ai/A)	Drift EEC
(lb ai/A)

	Upland Areas	Wetland Areas	All Areas

Application Rate 0.5 lb ai/A (Pine seedlings, Region 1)

Aerial	0.05	0.275	0.025

Ground	0.03	0.255	0.005

Application Rate 0.375 lb ai/A (Region 1 & 2)

Aerial	0.0375	0.20625	0.01875

Ground	0.0225	0.19125	0.00375

Application Rate 0.312 lb ai/A (Region 3)

Aerial	0.0312	0.1716	0.0156

Ground	0.01872	0.15912	0.00312

Application Rate 0.25 lb ai/A (Region 4)

Aerial	0.025	0.1375	0.0125

Ground	0.015	0.1275	0.0025

Application Rate 0.17 lb ai/A (Region 5)

Aerial	0.017	0.0935	0.0085

Ground	0.0102	0.0867	0.0017





3.6.2	AgDrift

Because of concerns about effects on non-target plants located in the
overspray or spray drift area, EFED elected to perform an analysis of
potential deposition of fomesafen using AgDrift modeling software. 
AgDrift was developed using extensive field-measured data sets, and
provides a method of estimating deposition of the compound of concern at
a specified distance away from the application source.  Deposition is
heavily dependent on the method of application and droplet size.  

The AgDrift modeling reported in   REF _Ref217197768 \h  Table 16  and  
REF _Ref217197829 \h  Table 17  is AgDrift Tier I, with associated
defaults.  It should be completely reproducible by anyone else using the
model with the same settings, as the only required inputs are the
application rate and distance from the field.  Please note, however,
that “fraction of applied” results were put

 into an Excel spreadsheet in order to more efficiently calculate RQs
for different endpoints and application rates.  Some of the values being
calculated are based on very low concentrations of fomesafen, and there
could be minor variations in output depending on how values for the
input or from the output are rounded. 

 The Tier I modeling extends to approximately 1,000 ft away from the
point of application.  At this point, the mathematical curve that
represents the deposition is asymptotic.  Thus, evaluations past this
point were not performed.  It is possible to estimate deposition at
longer distances using higher tiers of AgDrift, but the greater
distances add substantial uncertainty.  For aerial applications, the
deposition at 950 ft ranges from 0.3% to 4%, depending on droplet size. 
Deposition was estimated in 50 ft increments for droplet spectrums
ranging from very fine to very coarse (ASTM standard designation, 4
different ranges as implemented in the modeling software).  For ground
applications, estimates were done every 10 ft for the first 100 ft and
at 50 ft increments thereafter.  Estimates were done for both high and
low boom application methods, in the 2 droplet ranges implemented in
AgDrift (very fine to fine, fine to medium, ASTM standard designation). 
All values reported are based on the 90th percentile estimate.  Complete
modeling output is included in Appendix G.  

Values in the table are reported at the distance where deposition is
slightly lower than the NOAEC for the most sensitive plant, or at the
limit of the Tier I modeling, designated as >950 ft.  The actual
furthest extent of the Tier I model varies slightly depends on the
method of application and droplet size.

Table   SEQ Table \* ARABIC  16   Drift Deposition from Ground
Applications

Application Rate 

(lb ai/A)	Low Boom	High Boom

	Very Fine to Fine	Fine to Medium	Medium to Coarse	Coarse to Very Coarse

	Distance

(ft)	Deposition

(lb ai/A)	Distance

(ft)	Deposition

(lb ai/A)	Distance

(ft)	Deposition

(lb ai/A)	Distance

(ft)	Deposition

(lb ai/A)

0.5	300	0.0018	150	0.0017	450	0.0020	250	0.0017

0.375	200	0.0019	80	0.0020	400	0.0020	150	0.0019

0.312	200	0.0016	70	0.0020	350	0.0019	150	0.0016

0.25	150	0.0017	50	0.0019	300	0.0019	90	0.0019

0.17	80	0.0020	30	0.0019	250	0.0016	60	0.0018



Table   SEQ Table \* ARABIC  17   Drift Depostion from Aerial
Applications

Application Rate 

(lb ai/A)	Very Fine to Fine	Fine to Medium	Medium to Coarse	Coarse to
Very Coarse

	Distance

(ft)	Deposition

(lb ai/A)	Distance

(ft)	Deposition

(lb ai/A)	Distance

(ft)	Deposition

(lb ai/A)	Distance

(ft)	Deposition

(lb ai/A)

0.5	950	0.0214	950	0.0060	950	0.0028	700	0.0020

0.375	950	0.0161	950	0.0045	950	0.0021	550	0.0019

0.312	950	0.0134	950	0.0037	950	0.0021	550	0.0019

0.25	950	0.0107	950	0.0030 	600	0.0019	350	0.0020

0.17	950	0.0073	950	0.0020	400	0.0019	250	0.0019



4.0	Effects Assessment

Toxicity endpoints are established based on data generated from
guideline studies submitted by the registrant, and from open literature
studies that meet the criteria for inclusion into the ECOTOX database
maintained by EPA/ORD.  EFED policy is to use the effects endpoint from
the most sensitive tested species for each taxa evaluated.  In aquatic
systems, taxa evaluated include aquatic plants, invertebrates, and fish.
 Fish serve as a surrogate for aquatic-phase amphibians when amphibian
data are unavailable or unacceptable for quantitative use.  Where data
are available, separate endpoints are used for freshwater and
estuarine/marine organisms.  In terrestrial systems, taxa evaluated
include birds and mammals.  Bird endpoints are generally derived from
guideline studies on bobwhite quail and/or mallard duck.  Bird data are
used as a surrogate for reptiles and terrestrial-phase amphibians when
data for these taxa are unavailable or unacceptable for quantitative
use.  Mammal data are derived from guideline studies conducted on
laboratory rats, mice, or rabbits.

4.1	Specific Toxicological Concerns Associated with this Chemical

Fomesafen is a diphenyl-ether, one of a class of herbicides sometimes
referred to as light-dependent peroxidizing herbicides (LDPHs), which
have enhanced toxicity in the presence of solar ultra-violet radiation. 
Because toxicity of the LDPHs is affected by the presence of ultraviolet
(UV) radiation, toxicity tests used in this assessment, which were
conducted under standard laboratory lighting conditions, may
underestimate the toxicity of fomesafen to some taxa under natural
sunlight conditions.  The Agency is currently in the process of
developing a protocol for aquatic studies that evaluate the effect of UV
light on the toxicity of these herbicides, but at the time of this
assessment, it had not been finalized (EFED 2007).  Preliminary studies
have been submitted for some chemicals, but not fomesafen.  Fish early
life-cycle studies on oxyfluorfen conducted under UV light indicate
larval fish LD50s are approximately an order of magnitude lower than
LD50s based on standard lighting conditions (MRID 46585104).  In this
study, the larval fish appeared to hatch prematurely compared to the
controls, and then die.  Based on the mode of action, it is possible
that disruption of the egg cell membrane caused the premature hatch. 
The extent to which UV light enhances the toxicity of fomesafen is
unknown.  However, existing studies may underestimate the toxicity. 
Potential impacts of the underestimation are discussed in the Risk
Description (Section 6).

Fomesafen, along with other chemicals in this class have been associated
with peroxisome proliferation, which can induce hepatocellular
carcinomas in rodents.  (Smith and Elcombe 1989, Ashby et al as cited in
Krijt et al 1999.  A discussion of potential for carcinogenicity, based
on EFED’s review of open literature information and the HED’s review
of mammalian guideline studies, is included in the terrestrial effects
section.

4.2	Aquatic Hazard Summary

Fomesafen was originally registered for use in the 1980s.  Guideline
studies from that time were available for aquatic invertebrates and
fish, both freshwater and marine/estuarine.  Although some of the
studies were conducted on formulated product, and would not be
acceptable under current standards, they were classified as core or
supplemental under the guidelines at the time they were submitted, and
have been used in this assessment.  When necessary, endpoints for these
tests were re-calculated and/or data were converted to express toxicity
on the basis of active ingredient.  Overall, fomesafen is slightly toxic
to practically nontoxic to invertebrates and practically non-toxic to
fish on an acute basis.  Chronic tests were conducted under standard
laboratory lighting, and as noted in Section 4.1, may underestimate
toxicity by approximately an order of magnitude.

Table   SEQ Table \* ARABIC  18   Aquatic Toxicity Profile for
Fomesafen 

Assessment Endpoint	Surrogate Species	Toxicity Value Used 	Source
Citation	Comments

Freshwater

Acute Toxicity to Fish and Aquatic-phase Amphibians	Rainbow trout
LC50=126 mg/L

95%CI=117-135 mg/L

Slope=14.6	MRID

103023	Formulation1,2

(practically nontoxic)

Chronic Toxicity 

Fish and Aquatic-phase Amphibians	Calculated based on ACR

(Sheepshead minnow/sheeps-head minnow	LC50=9.4 mg/L

(ACR=13.4)	Estimated	Estimated from formulation data.

Daphnia ACR=7.5

Mysid ACR=35.7

Acute Toxicity to Aquatic Invertebrates	Water flea	LC50=376 mg/L

95%CI=323-437 mg/L

Slope=5.6	MRID 1631169	Formulation1,2

(practically nontoxic)

Chronic Toxicity 

Aquatic Invertebrates	Water flea	NOAEC=50 mg/L

LOAEC=100 mg/L	MRID

135642	Formulation1,2

Reduced growth, and # of offspring

Acute Toxicity to Aquatic Plants 

(non-vascular)	Green alga	LC50=0.092 mg/L3

NOAEC=0.010 mg/L3	MRID 46673804	Technical

Biomass most sensitive endpoint

Acute Toxicity to Aquatic Plants (vascular)	Duckweed	LC50= 0.210 mg/L

NOAEC=0.064 mg/L	MRID

46673803	Technical

Dry weight most sensitive endpoint

Saltwater

Acute Toxicity to Fish	Sheepshead minnow	LC50= >163mg/L

95%CI=ND

Slope=ND	MRID

135651	Formulation1,2

(practically nontoxic)

Chronic Toxicity to Fish 	Sheepshead minnow	NOAEC=12.2 mg/L

LOAEC=20.1 mg/L	MRID

135644	Formulation1,2

Reduced larval survival

Acute Toxicity to Aquatic Invertebrates	Mysid shrimp	LC50=25 mg/L

95%CI=19-38 mg/L

Slope=ND	MRID

135647	Formulation1,2

(slightly toxic)

Chronic Toxicity

Aquatic Invertebrates	Mysid shrimp	NOAEC=0.70 mg/L

LOAEC=1.7 mg/L	MRID 135648	Formulation1,2

Parental mortality

Acute Toxicity to Aquatic Plants 	SW diatom	LC50= 1.51 mg/L

NOAEC=0.94 mg/L	MRID 46673806	Technical

Biomass most sensitive endpoint

1 Data are from studies originally reviewed and classified in 1984, some
of which used formulated product. 2 For purposes of this risk
assessment, test concentrations were adjusted for percent ai if
necessary, and endpoints were re-calculated using TOXANAL software. 3
Endpoints have been revised since those reported in problem formulation,
which were based on provisional data.  ND-not determined.

4.3	Summary of Aquatic Ecotoxicity Studies

4.3.1	Aquatic Guideline Data

Fomesafen was originally registered for use in the 1980s.  Guideline
studies from that time were available for aquatic invertebrates and
fish, both freshwater and marine/estuarine.  Although some of the
studies were conducted on formulated product, and would not be
acceptable under current standards, they were classified as core or
supplemental under the guidelines at the time they were submitted.  When
necessary, endpoints were re-calculated and/or data were converted to
express toxicity on the basis of active ingredient. Aquatic plant data
are from studies conducted on the technical ingredient.  Acute toxicity
(LC50s) for fish and invertebrates ranges from 25 mg ai/L (mysid shrimp,
MRID 135647) to 1,507 mg/L (bluegill, MRID 163169).  No sub-lethal
effects were reported in the acute studies. Overall, fomesafen is
slightly toxic to practically nontoxic to invertebrates and practically
non-toxic to fish on an acute basis.  Chronic toxicity (NOAECs) for fish
and invertebrates range from 0.7 mg ai/L (mysid shrimp, parental
mortality, MRID 1354648) to 50 mg ai/L (Daphnia magna, reduced growth,
total number of offspring, MRID 1354642). Because of fomesafen’s low
toxicity to aquatic animals based on the available data, additional
studies were not requested at the time of problem formulation, and this
risk assessment was conducted using existing data.  More recent studies
on aquatic plants were conducted on the technical active ingredient
(ai).  LC50s for aquatic plants range from 0.092 mg ai/L (green alga,
MRID 46673804) to 71 mg ai/L (bluegreen alga, MRID 46673807).  NOAECs
range from 0.0095 mg ai/L (green alga, MRID 46673804) to 27.3 mg ai/L
(bluegreen alga, MRID 46673807).  

4.3.2	Aquatic Data from ECOTOX

Several studies were available in ECOTOX evaluating the effects of
fomesafen on aquatic organisms, including mesocosm studies that
addressed effects on community structure and primary productivity
(Caquet et al 2005 (E87334) and Caquet 2006 (E95935); Perschbacher et al
1997 (E53095)).  Other studies evaluated effects on the hematocytes of
snail exposed to fomesafen in solution Russo et al (2007) (E95100) and
Russo and Medec (2007) (E95590).

g/L (mean) in the fomesafen-only ponds and as 19.4 ±7.6 g/L
(mean) in the fomesafen-Agral 90 ponds.  The authors make no mention of
measuring concentrations in other compartments in the mesocosm or
performing any mass balance calculations to determine fate of fomesafen
in the mixture mesocosms, although they speculate (Caquet et al 2005) it
may have accumulated at the interfaces.

Currently, the EFED assumption for spray drift in aerial applications is
5%, and it is assumed to be the product (or whatever application mix)
deposited directly on the surface of a water body adjacent to a treated
field.  Study authors have essentially made the same assumption, and
evaluated the short-term effects (deposition-72 hrs) of a 1% and 10%
drift rate associated with aerial application to soybeans on the
phytoplankton community of a small (500-L) pond.  Based on this work,
one could interpret that short-term effects on the phytoplankton
abundance and production from concentrations of fomesafen ≤0.06 mg/L
are not anticipated.  This should be caveated with the fact that the
community was dominated by cyanobacteria (which appear to be less
sensitive to fomesafen than green algae).  Also, measurement endpoints
reported by authors evaluate overall primary productivity of the
sy瑳浥‬慲桴牥琠慨⁮潣浭湵瑩⁹瑳畲瑣牵ⱥ眠楨档洠
祡戠⁥潭敲爠獥潰獮癩⹥

 extended exposure.  At concentrations of ≤270 g/L for durations
≤504 hours (21 days) there was no observable abnormal behavior,
mortality, or reduction of hemocyte cell viability in the snails (Russo
et al 2007, Russo and Madec 2007).  Based on this work, it appears that
fomesafen induces an immune response in freshwater snails at
concentrations that may occur in the environment, but how these
responses translate to measurable effects at an organism level (e.g.,
reduced growth, tumor activation, increase susceptibility to disease)
are unknown.

4.4	Terrestrial Hazard Summary

Guideline studies evaluating effects on birds, mammals, and terrestrial
invertebrates were available for fomesafen.  Several ECOTOX studies
suitable for risk assessment purposes were available.  On an acute
basis, fomesafen is slightly toxic to mammals and practically non-toxic
to birds and honeybees.  Open literature studies indicate fomesafen may
induce homolysis and formation of hepatic carcinomas in some strains of
mice, but these occur at concentrations and durations of exposure far
higher than likely to occur in the environment based on current
registrations.  HED (USEPA 2006) has determined fomesafen is neither
mutagenic nor carcinogenic for humans, nor does it appear to be
associated with endocrine-disrupting effects.

Table   SEQ Table \* ARABIC  19   Terrestrial Toxicity Profile for
Fomesafen

Assessment Endpoint	Surrogate Species	Toxicity Value Used 	Source
Citation	Comments

Vertebrates

Acute Risk to Mammals	Guinea pig	LC50=607 mg/kg

95%CI=ND

Slope=ND	MRID 164901	Slightly toxic

Chronic Risk to Mammals	Rat	NOAEC=1,000 mg/kg

LOAEC=ND	MRID 144862	No reproductive effects

Acute Risk to Birds, Terrestrial-phase Amphibians, and Reptiles	Mallard
duck

(oral dose)	LC50=>5,000 mg/kg

95%CI=ND

Slope=ND	MRID 163168	Practically non-toxic

	Mallard duck (dietary)	LC50=>20,000 mg/kg

NOAEC=20,000 mg/kg	MRID

163384	Practically non-toxic

Chronic Risk to Birds, Terrestrial phase Amphibians, and Reptiles
Mallard duck	NOAEC=46 mg/kg

g/bee	MRID 135651	Practically non-toxic

Plants

Acute Risk to Monocots	Onion

(seedling emergence)	EC25= 0.084 lb ai/A

NOAEC=0.030 lb ai/A	MRID 46673801	Formulation

(Reflex 2 LC)

Acute Risk to Dicots	Lettuce

(vegetative vigor)	EC25= 0.002 lb ai/A

NOAEC=<0.002 lb ai/A	MRID 46673802

	4.5	Summary of Terrestrial Ecotoxicity Studies

4.5.1	Avian and Small Mammal Guideline Data

Guideline acute toxicity studies were available for birds (both dose and
dietary), and small laboratory mammals (dose).  The oral LD50 for
mallard ducks was greater than the highest dose tested (LD50>5,000
mg/kg, MRID163168).  Sub-acute dietary LC50s for both mallards and
bobwhite quail were also greater than the highest dose tested (>20,000
mg/kg, MRIDs 163384, 164901)  Acute oral dose LD50s were available for
guinea pigs (F 607 mg/kg, MRID 164901), mice (F 745 mg/kg, M 766 mg/kg,
MRID164901) and rats (F 1499 mg/kg, M 1858 mg/kg, MRID 164901).  On the
basis of both dose and dietary values, fomesafen is practically
non-toxic to birds and slightly toxic to mammals.  Endpoints for female
guinea pigs and mallard ducks were the most sensitive and were used to
develop risk quotients.

Chronic guideline studies were available for birds (mallard duck, MRID
135639) and small laboratory mammals (rat, MRID 144862).  The bird
guideline study did not establish a LOAEC, only determining that there
were no effects at the highest (mean-measured) concentration tested for
birds.  No sub-lethal effects were noted.  Lack of a LOAEC contributes
significant uncertainty to the evaluation of chronic risk to birds.  The
mallard duck NOAEC (46 ppm) is used in the determination of chronic risk
to birds, but it may over-estimate the risk to birds.  In some cases,
calculated exposure is near or above the maximum tested concentration. 
In the rat study, no treatment related reproductive parameters were
affected at the highest dose tested, resulting in a reproductive NOAEC
of 1,000 mg/kg (MRID 144862).  Changes in the liver histopathology of
both the parents and the offspring were noted at 1,000 mg/kg.  Histology
changes are difficult to link with the assessment endpoints of growth,
survival and fecundity evaluated by the Agency.  The reproductive NOAEC
of 1,000 mg/kg was used to develop endpoints for mammals.

Because of fomesafen’s low toxicity to terrestrial organisms based on
the available data, additional studies were not requested at the time of
problem formulation, and this risk assessment was conducted using
existing data.

4.5.2	Terrestrial Plant Data

4.5.2.1	Guideline Studies

Terrestrial plant guideline studies were available.  Fomesafen is
effective, both pre- and post-emergent, against a variety of plants,
although dicots appear to be more sensitive than monocots for both
endpoints (seedling emergence and vegetative vigor).  The product is
marketed as a control for broad-leafed weeds.

Guideline studies for seedling emergence (MRID 46673801, acceptable) and
vegetative vigor (MRID 46673802, acceptable) were available at the time
of this assessment.  Both studies evaluated the effects of fomesafen
formulated product (REFLEX 2LC) on 10 plant species.  Species tested
included 4 monocots (onion, barnyard grass, corn, and oats) and 6 dicots
(radish, lettuce, tomato, soybean, oilseed rape, and sugarbeet).  Two
concentrations were tested: 0.25 lb ai/A and 0.50 lb ai/A.  For
monocots, the seedling emergence EC25s ranged from 0.084 lb ai/A to
>0.48 lb ai/A (no effect at highest concentration tested).  Dicots were
more sensitive, with the seedling emergence EC25s  ranging from
0.005-0.35 lb ai/A, with the exception of soybeans, with an EC25 of
>0.48 lb ai/A (no effect at highest concentration tested).  Currently,
soybeans are the crop for which fomesafen is most commonly used.  For
dicots, the sensitivity range for the vegetative vigor endpoint is
similar to the seedling emergence endpoint. EC25s for the dicot
vegetative vigor endpoint range from 0.002-0.24 lb ai/A, with the
exception of soybeans, with an EC25 of >0.47 lb ai/A (no effect at
highest concentration tested).  For monocot vegetative vigor endpoint
EC25s ranged from 0.29 lb ai/A to >0.47 lb ai/A (no effect at highest
concentration tested). Based on this data, dicots appear more sensitive
than monocots, and the vegetative vigor and seedling emergence endpoints
appear to be equally sensitive. 

4.5.2.2	Additional Registrant-Submitted Data

Efficacy data (MRID 135656) were part of the data package submitted for
the original registration of fomesafen, and were considered in this
assessment.  The efficacy data included pre-emergence and post-emergence
treatment of 24 plant species, at two concentrations (0.25 and 1.0 kg
ai/ha, or when converted, 0.42 and 0.54 lb ai/A).  The two
concentrations are greater than most currently registered rates.  The
plant species tested included both monocots (11 species) and dicots (13
species).  Both crop (7 species) and non-crop (17 species) plants were
evaluated.  With the exception of soybeans, all plants tested
experienced >20% “damage” when treated pre-emergence, with a
significant number (65%) experiencing >80% damage when treated with the
lower concentration (0.25 kg ai/ha).  Applied post-emergence, fomesafen
is slightly less effective, with “damage” typically in the 0-40%
range for monocots and 40-80% range for dicots.  The report did not
specify how damage was quantified.

Additional plant data was submitted by the registrant during the
registration review process (MRID 47587101).  This submission was not
reviewed by EPA for acceptability, and raw data were not included, thus
values reported herein do not represent anything statistically generated
by the Agency.  Inclusion of these data is intended to provide a broader
view of potential effects on plants than is provided by guideline data
alone.  These data do not represent a regulatory endpoint.

The submission included an estimation a 10th percentile EC25, based on
EC25s for a range of plant species tested by the registrant. The
registrant’s database included 210 efficacy tests addressing 35 common
crop and weed, with multiple application rates ranging from 0.01-0.45 lb
ai/A.  Effects on the plants are rated on a visual scale of 1 to 10
compared to control plants, then converted to a percent effects scale
(0%=no damage, 100%=complete efficacy).  

4.5.3	Terrestrial Insect Data

Guideline tests for honeybees were submitted (MRID 135651, Core), as was
a field chronic effects study on earthworms (MRID 135652).  The acute
oral LD50 for honeybees was >50 g ai/bee, and the acute contact LD50
was >100 g ai/bee.  The field test for earthworms included two
applications of fomesafen, applied at one-year intervals.  Fields were
treated with 0.5 kg ai/ha and 5.0 kg ai/ha.  No adverse effects on total
numbers, total weights, or numbers of individual species were noted at
the 0.5 kg ai/ha treatment level.  A significant change in numbers of
one species of earthworm (Allolobophura nocturna) was noted at the
higher treatment level, but authors attributed this to modifications in
grass cover caused by the herbicide treatment rather than direct toxic
effects.

Studies were also submitted (MRID 135656) for eight species of
invertebrates, from the orders Acarina, Hemiptera, Diptera, Lepidoptera,
Coleoptera, and Nemotoda.  Fomsafen was applied to multiple life stages
at concentrations of 250 and 500 ppm.  The greatest level of mortality
in these tests was 9%.  Aphids (Aphis fabae) experienced mortality rates
of 9% at concentrations of 250 ppm and 500 ppm.

4.5.4	ECOTOX Data

Some information regarding toxicity of fomesafen was available in the
open litereature.  Full reviews of studies with endpoints potentially
useful for this risk assessment are located in Appendix B.  No studies
contained endpoints lower than those derived from guideline studies. 
Summaries of studies evaluating biochemical and community-level
endpoints are presented below.

4.5.4.1	Biochemical Endpoints

Several studies (Krijt et al 1993 (E95026); Krijt et al 1994a (E95399);
Krijt et al 1994b (E95589); Krijt et al 1999 (E95400); Krijt et al 2003
(E95588)) evaluating the effects of fomesafen on mammalian hematocytes
were located and reviewed.  The work of Krijt et al demonstrates that
fomesafen ingested by mice at concentrations ranging from 100-2,500 ppm
diet for 10 days causes elevated liver and fecal porphyrins, primarily
via inhibition of the 7th enzyme of the heme biosynthesis protoprophyrin
III oxidase (Krijt et al 1993).  Body weight gain is statistically
significantly affected when fomesafen is administered at concentrations
of 2,500 ppm in diet for 10 days (Krijt et al 1993).  The treatment
groups in all investigations are small (n=3 or 4).  Mice used in the
experiments were generally in the size range of 30-35 grams.  In some
cases, fomesfen may also inhibit uroporphyrinogen III decarboxylase, but
specific biochemical responses may vary dependent on the strain of mouse
(Krijt et al 1994m, Krijt et al 2003).  Consumption of high doses
(2,300-3,000 ppm) for extended periods of time (50 weeks to 14 months)
caused development of precancerous cells in the liver (Krijt et al
1999).  Even with extended exposure, mice appeared to recover following
a period of clean diet (3months) with liver porphyrins decreasing, and
liver histology not noticeably different from controls (Krijt et al
1999).  In both studies that included a recovery period, liver porphyrin
concentrations decreased rapidly following withdrawal from fomesafen,
but did not return to the same levels as controls during the observation
period (Krijt et al 1999). 

g/L(“maximum mean”) in the fomesafen only ponds and as 19.4 ±7.6
g/L (“maximum mean”) in the fomesafen-Agral 90 ponds 

on from concentrations of fomesafen ≤0.06 mg/L are not anticipated. 
This should be caveated with the fact that the mesocosm community was
dominated by cyanobacteria (which appear to be less sensitive to
fomesafen than green algae based on registrant-submitted studies: MRID
46673806, green alga EC50 92 g/L; MRIDs 46673807, blue-green alga
EC50 710 g/L).  Also, measurement endpoints reported by authors
evaluate overall primary productivity of the system, rather than
community structure, which may be more responsive.

4.5.5	Carcinogenicity, Mutagenicity, and Endocrine Disruption

) as the mode of action for fomesafen-induced hepatocarcinogeneisis
in mice.  The data did not support either mutagensis or cytotoxicity
followed by regenerative proliferation as alternative modes of
action.” (USEPA 2006).

EPA is required under the FFDCA, as amended by FQPA, to develop a
screening program to determine whether certain substances (including all
pesticide active and other ingredients) “may have an effect in humans
that is similar to an effect produced by a naturally occurring estrogen,
or other such endocrine effects as the Administrator may designate.” 
Following the recommendations of its Endocrine Disruptor Screening and
Testing Advisory Committee (EDSTAC), EPA determined that there were
scientific bases for including, as part of the program, androgen and
thyroid hormone systems, in addition to the estrogen hormone system. 
EPA also adopted EDSTAC’s recommendation that the Program include
evaluations of potential effects in wildlife.  When the appropriate
screening and/or testing protocols being considered under the Agency’s
Endocrine Disrupter Screening Program (EDSP) have been developed and
vetted, fomesafen may be subjected to additional screening and/or
testing to better characterize effects related to endocrine disruption.

4.5.6	Toxic Effects of Multi-Active Ingredient Labeled Products 

Mammalian toxicity data were available for several formulated products,
including one containing only fomesafen and all those containing
multiple active ingredients.  Based on female guinea pig data (used as
the assessment endpoint LD50 = 607 mg/kg bw), rats are less sensitive to
fomesafen (female LD50 = 1,499 mg/kg bw).  For the formulations, rat
data was compared to minimize variability associated with interspecies
variation.

Flexstar (reg#100-1101), which contains only fomesafen (22.1%) has an
LD50 of 3863 mg/kg (female, 95% CI not reported, MRID44030101).  Prefix
(reg #100-1268), which contains both fomesafen and s-metolachlor (10.1%
and 46.5% respectively) has an LD50 of 5,000 mg/kg (combined, 95% CI
2,865-8,390, MRID46952103).  Metolachlor has an LD50 of 2780 mg/kg
(combined, 95% CI 2,180-3,545, MRID00015523).  Formulations containing
bentazon (BAS 530 04 (29%), reg#7969-82 and Faster (29.8%), reg#7969-83)
have an LD50 of >1210 mg/kg and 1470 mg/kg (95% CI 1,000-2,160, MRIDs
40340502, 40031302).  Bentazon has an LD50 of 1480 mg/kg (MRIDs 92065,
64314).

Although guideline studies are not designed to elucidate such effects,
there do not appear to be additive or synergistic acute toxicity effects
between fomesafen and any of the currently co-formulated active
ingredients based on available data.  Toxic effects to mammals from
ingestion of the formulated products containing fomesafen alone or
fomesafen in conjunction with s-metolachlor or bentazon are not
anticipated to exceed toxic effects estimated based on the technical
active ingredient (Appendix H).

4.6	Incident Database Review

EFED maintains EIIS, a database containing reported incidents of damage
to non-target species caused by pesticide use.  There are a total of 65
reported incidents (Appendix F) for fomesafen, 64 of which are damage to
agricultural crops.  Incidents reported cover a range of 13 years
(1992-2005), but many of them (83%) were reported in 2001-2003.  Corn
was the crop most frequently reported damaged, accounting for 86% of the
total plant damage reports.  The most frequently reported routes of
exposure for corn were direct treatment, drift, and carryover.  In many
cases (36%) the legality was classified as registered use.  In other
cases (55%), the legality of application is unknown.  The certainty that
the incident was related to fomesafen use was generally classified as
probable.  Other crops damaged included green peas, cotton, and soybeans
under registered use conditions.  Only 5 cases of misuse or accidental
misuse were reported.

 

There is one report of a fish kill (I007601-001).  In this incident,
there was a report of approximately 200 fish (channel catfish, crappie,
largemouth bass, and redear sunfish) dying following a legal application
to a soybean site.  The certainty of the kill being related to fomesafen
runoff is classified as possible.  Application was in accordance with
registered use.

5.0	Risk Estimation

Risk is estimated by calculating the ratio of the expected environmental
concentration and the appropriate toxicity endpoint.  This value is the
risk quotient (RQ), which is then compared to pre-established levels of
concern (LOC) for each category evaluated.  The RQ methodology, LOCs,
and specific details of calculation are contained in Appendix G.  The
highest EECs and most sensitive endpoints are used to determine the
screening level RQ.  Using these two values, theoretically, results in a
conservative estimate of risk.

5.1	Aquatic RQ Summary

≤0.02.  Acute risk RQs for fresh-and saltwater plants, both vascular
and non-vascular, ranged from <0.01 to 0.16.  In no cases did RQs for
plants exceed the acute risk LOC.  Listed species RQs for fresh- and
saltwater aquatic plants ranged from <0.01 to 1.6.  At the 0.5 lb ai/A
application rate, RQs for freshwater non-vascular plants exceed the
listed species LOC.  For some, but not all of the scenarios modeled, RQs
for freshwater non-vascular plants exceed the listed species LOC at the
application rate of 0.375 lb ai/A (RQs for all scenarios modeled are
included in Appendix A).  In no cases did the modeled concentrations of
fomesafen exceed the LOAEC for freshwater non-vascular plants.  

Fomesafen appears to pose very low risk to aquatic ecosystems based on
the data currently available.

Table 21  Summary of Aquatic RQs

Taxa	Acute RQ	Chronic RQ1	Endangered Species RQ2

Highest Section 24 Use on Cotton at 0.5 lb ai/A (MS scenario, ground
application)

FW Aquatic Plants (algal)	0.16	NA1	1.6 a

FW Aquatic Plants (vascular)	0.07	NA1	0.24

FW Aquatic Invertebrates	<0.01	<0.01	<0.01

FW Fish	<0.01	NC	<0.01

SW Aquatic Plants	0.01	NA1	0.02

SW Aquatic Invertebrates	<0.01	<0.01	<0.01

SW Fish	<0.01	<0.01	<0.01

Highest Section 3 EEC: Use on Cotton at 0.375 lb ai/A (TX scenario,
aerial application)

FW Aquatic Plants (algal)	0.13	NA1	1.2a

FW Aquatic Plants (vascular)	0.06	NA1	0.19

FW Aquatic Invertebrates	<0.01	<0.01	<0.01

FW Fish	<0.01	<0.01	<0.01

SW Aquatic Plants	<0.01	NA1	0.01

SW Aquatic Invertebrates	<0.01	0.02	<0.01

SW Fish	<0.01	<0.01	<0.01

Lowest EEC:  Use on Beans at 0.17 lb ai/A (MI scenario, aerial
application)

FW Aquatic Plants (algal)	0.03	NA1	0.24

FW Aquatic Plants (vascular)	0.01	NA1	0.04

FW Aquatic Invertebrates	<0.01	<0.01	<0.01

FW Fish	<0.01	<0.01	<0.01

SW Aquatic Plants	<0.01	NA1	<0.01

SW Aquatic Invertebrates	<0.01	<0.01	<0.01

SW Fish	<0.01	<0.01	<0.01

1 There are no chronic aquatic plants tests. 2 Endangered species RQ for
plants are calculated based on NOAEC.  Endangered species RQs for
animals are calculated in the same way as acute risk values, but
compared to a different LOC.  NA – not applicable, NC – Not
calculated, data not available.  aExceeds endangered species LOC.

5.2	Terrestrial RQ Summary

5.2.1	Terrestrial Plants

Risk quotients were calculated based on the exposures estimated by both
TerrPlant and AgDrift.  Calculations were made using data from both
types of guideline studies (vegetative vigor and seedling emergence). 
Evaluations were done for both monocots and dicots.  The most sensitive
endpoint was dicot vegetative vigor (EC25=0.0016 lb ai/A, NOAEC=0.00098
lb ai/A).  For the seedling emergence tests, calculated EC05 was
unavailable, and the reported NOAEC was greater than the calculated
EC25, so the EC25 was used as the toxicity endpoint for the endangered
species analysis.

5.2.1.1	TerrPlant

Because fomesafen is highly toxic to terrestrial plants, RQs for all
application rates, both aerial and ground, are presented below.  It is
especially toxic to dicots, and RQs exceed the LOC for both non-listed
and listed species of plants in upland and wetland areas, as well as on
the basis of spray drift alone.  RQs for non-listed dicots range from
4.3 (drift only, 0.17 lb ai/A) to 59.8 (wetland, 0.5 lb ai/A).  RQs for
listed dicots range from >0.85 (drift only, 0.17 lb ai/A) to 59.8
(wetland, 0.5 lb ai/A).  For non-listed monocots, RQs exceed the LOC
only in the wetland area.  Non-listed monocot RQs range from <0.1 (drift
only, 0.17 lb ai/A) to 3.3 (wetland, 0.5 lb ai/A).  RQs for listed
monocots range from <0.1 (drift only, 0.17 lb ai/A) to 3.3 (wetland, 0.5
lb ai/A).



Table 22  Terrestrial Plant Risk Quotients Based on TerrPlant

Application Rate

(lb ai/A)	Total Loading RQ

(Seedling Emergence)	Total Loading RQ

(Seedling Emergence)	Drift Only

(Vegetative Vigor)

	Upland Areas	Wetland Areas	Drift Only

	Monocot	Dicot	Monocot	Dicot	Monocot	Dicot

Aerial Applications   Non-listed Plants

0.5

Region 1 pine	0.60	10.87a	3.27a	59.78a	0.30	12.50a

0.375

Region 1 & 2	0.45	8.15a	2.66a	44.84a	0.22	9.38a

0.312

Region 3	0.37	6.78a	2.04a	37.30a	0.19	7.80a

0.25

Region 4	0.30	5.43a	1.64a	29.89a	0.15	6.25a

0.17

Region 5	0.20	3.70a	1.11a	20.33a	0.10	4.25a

Ground Applications   Non-listed Plants

0.5

Region 1 pine	0.36	6.52a	3.04a	55.43a	<0.1	2.50a

0.375

Region 1 & 2	0.27	4.89a	2.28a	41.58a	<0.1	1.88a

0.312

Region 3	0.22	4.07a	1.87a	34.59a	<0.1	1.56a

0.25

Region 4	0.18	3.26a	1.52a	27.72a	<0.1	1.25a

0.17

Region 5	0.12	2.22a	1.03a	18.85a	<0.1	0.85

Aerial Applications   Listed Plants

0.5

Region 1 pine	1.67a	10.87a	9.17a	59.78a	0.83	>12.50a

0.375

Region 1 & 2	1.25a	9.87a	6.88a	54.28a	0.63	>9.38a

0.312

Region 3	1.04a	8.21a	5.72a	45.16a	0.52	>7.80a

0.25

Region 4	0.83	6.58a	4.58a	36.18a	0.42	>6.25a

0.17

Region 5	0.57	4.47a	3.12 	24.61a	0.28	>4.25a

Ground Applications   Listed Plants

0.5

Region 1 pine	1.00a	7.89a	8.50a	67.11a	0.17	>2.50a

0.375

Region 1 & 2	0.75	5.92a	6.38a	50.33a	0.13	>1.88a

0.312

Region 3	0.62	4.93a	5.30a	41.87a	0.10	>1.56a

0.25

Region 4	0.50	3.95a	4.25a	33.55a	<0.1	>1.25a

0.17

Region 5	0.34	2.68a	2.89a	22.82a	<0.1	>0.85

a Exceeds or equals LOC of 1

5.2.1.2	AgDrift

Acute risk RQs and listed species RQs were calculated for aerial and
ground applications (low boom and high boom) using the EC25 and NOAEC
for the most sensitive dicot (lettuce EC25 0.0002 lb ai/A, NOAEC
<0.00019 lb ai/A).  As the endpoints are so similar, RQs presented below
apply to both listed and non-listed species.  Because the droplet size
is an important parameter in determining spray drift, clearance
distances and RQs were calculated for all droplet spectrum available in
AgDrift.  The maximum extent of AgDrift Tier I modeling is approximately
1,000 ft from point of application for aerial applications, but the
specific distance varies slightly dependent on the droplet spectrum. 
For the sake of consistency, modeling was terminated at 950 ft for all
spectra.  At this distance, the mathematical curve which describes the
deposition is asymptotic, there are only small declines for greater
linear distances. 

 For aerial applications, fomesafen applied with a very fine to fine or
fine to medium droplet spectrum exceeds the terrestrial plant LOC at all
application rates.  For coarser droplet spectra, RQs range from 0.96 to
1.4, and clearance distances range from 250 ft to >950 ft.  Ground
applications require a narrower buffer to clear the LOC, especially a
low boom.  Clearance distances for ground applications range from 30 ft
to 450 ft.

Table   SEQ Table \* ARABIC  20   Drift Deposition from Aerial
Applications

Application Rate 

(lb ai/A)	Very Fine to Fine	Fine to Medium	Medium to Coarse	Coarse to
Very Coarse

	Clearance Distance

(ft)	RQ

unitless	Clearance Distance

(ft)	RQ

unitless	Clearance Distance

(ft)	RQ

unitless	Clearance Distance

(ft)	RQ

unitless

0.5	>950	10.7	>950	3.0	>950	1.4	700	0.98

0.375	>950	8.0	>950	2.3	>950	1.1	550	0.94

0.312	>950	6.7	>950	1.9	>950	1.1	550	0.94

0.25	>950	5.4	>950	1.5	600	0.96	350	0.98

0.17	>950	3.6	>950	1.0	400	0.94	250	0.96

Bold designates an exceedence (LOC=1)

Table   SEQ Table \* ARABIC  21   Drift Deposition from Ground
Applications

Application Rate 

(lb ai/A)	Low Boom	High Boom

	Very Fine to Fine	Fine to Medium	Medium to Coarse	Coarse to Very Coarse

	Clearance Distance

(ft)	RQ

unitless	Clearance Distance

(ft)	RQ

unitless	Clearance Distance

(ft)	RQ

unitless	Clearance Distance

(ft)	RQ

unitless

0.5	300	0.88	150	0.83	450	0.98	250	0.83

0.375	200	0.96	80	0.98	400	0.95	150	0.96

0.312	200	0.80	70	0.90	350	0.97	150	0.85

0.25	150	0.83	50	0.93	300	0.94	90	0.95

0.17	80	0.98	30	0.93	250	0.79	60	0.88



5.2.2	Avian RQ Summary

For birds, no acute LOCs were exceeded at any application rates.

Chronic RQs are reported as <RQ, due to the fact that the NOAEC
established in the guideline study was not definitive.  At the
application rate of 0.5 lb ai/A, chronic LOCs for birds in three out of
the four food categories (short grass, tall grass, and broadleaf
plants/small insects) were exceeded.  At the application rate of 0.375
lb ai/A, chronic LOCs for birds consuming the food categories of short
grass and broadleaf plants/small insects were exceeded.  At the
application rate of 0.17 lb ai/A, chronic LOCs for birds in the short
grass food category were exceeded.

Table   SEQ Table \* ARABIC  22   Avian RQ Summary

Risk quotients based on Kenaga upper bound EECs	Acute dose-based RQs1
Acute dietary-based RQs1	Chronic RQs

	20g	100g	1000g	All birds	All birds

Maximum Application Rate 0.5 lb ai/A (pine seedlings, states in region
1)

Short grass	0.05	0.02	0.01	0.01	<2.61c

Tall grass	0.02	0.01	<0.01	<0.01	<1.20c

Broadleaf plants/small insects	0.03	0.01	<0.01	<0.01	<1.47c

Fruits/pods/seeds/lg insects	<0.01	<0.01	<0.01	<0.01	<0.16

Common Application Rate 0.375 lb ai/A (all crops, regions 1, 2)

Short grass	0.04	0.02	0.01	<0.01	<1.96c

Tall grass	0.02	0.01	<0.01	<0.01	<0.90

Broadleaf plants/small insects	0.02	0.01	<0.01	<0.01	<1.10c

Fruits/pods/seeds/lg insects	<0.01	<0.01	<0.01	<0.01	<0.12

Minimum Application Rate 0.17 lb ai/A (all crops, region 5)

Short grass	0.02	0.01	<0.01	<0.01	<0.89c

Tall grass	0.01	<0.01	<0.01	<0.01	<0.41

Broadleaf plants/small insects	0.01	<0.01	<0.01	<0.01	<0.50

Fruits/pods/seeds/lg insects	<0.01	<0.01	<0.01	<0.01	<0.06

a exceeds acute risk LOC (0.5)

b exceeds endangered species acute risk LOC (0.1)

c exceeds chronic risk LOC (1.0)

5.2.3	Small Mammal RQ Summary

For mammals, no acute LOCs were exceeded at any application rates.  The
chronic LOC was exceeded only for small (15g) mammals eating short grass
at the highest rate (0.5 lb ai/A, pine seedlings in AR, GA, MS, NC, and
SC).

Table   SEQ Table \* ARABIC  23   Small Mammal RQ Summary

Risk Quotients based 

on Kenaga 

upper bound EEC	Acute 

dose-based RQs	Chronic 

dose-based RQs	Chronic dietary-based RQs

	15 g	35 g	1000 g	15 g	35 g	1000 g 	All mammals

Maximum Application Rate 0.5 lb ai/A (pine seedlings, states in region
1)

Short grass	0.09	0.07	0.04	1.04 c	0.89	0.48	0.48

Tall grass	0.04	0.03	0.02	0.48	0.41	0.22	0.22

Broadleaf plants/

small insects	0.05	0.04	0.02	0.59	0.50	0.27	0.27

Fruits/pods/seeds/

lg insects	0.01	<0.01	<0.01	0.07	0.06	0.03	0.03

Seeds (granivores)	<0.01	<0.01	<0.01	0.01	0.01	0.01	NA

Common Application Rate 0.375 lb ai/A (all crops, regions 1&2)

Short grass	0.06	0.05	0.03	0.78	0.67	0.36	0.36

Tall grass	0.03 	0.03	0.01	0.36	0.31	0.16	0.17

Broadleaf plants/

small insects	0.04	0.03	0.02	0.44	0.38	0.20	0.20

Fruits/pods/seeds/

lg insects	<0.01	<0.01	<0.01	0.05	0.04	0.02	0.20

Seeds (granivores)	<0.01	<0.01	<0.01	0.01	0.01	<0.01	NA

Minimum Application Rate 0.17 lb ai/A (all crops, region 5)

Short grass	0.03	0.02	0.01	0.35	0.30	0.16	0.16

Tall grass	0.01	0.01	0.01	0.16	0.14	0.07	0.07

Broadleaf plants/

small insects	0.02	0.01	0.01	0.20	0.17	0.09	0.09

Fruits/pods/seeds/

lg insects	<0.01	<0.01	<0.01	0.02	0.02	0.01	0.01

Seeds (granivores)	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	NA

a Equals or exceeds acute risk LOC (0.5)

b Equals or exceeds listed species acute risk LOC (0.1)

c Equals or exceeds chronic risk LOC (1.0)

5.2.4	Terrestrial Invertebrate Summary

g ai/bee (based on large insect estimator, 0.5 lb ai/A) to 8.64 g
ai/bee (based on small insect estimator).  Using the acute contact LD50
of >100 g ai/bee, anticipated exposure at the treatment site would
not be greater than approximately 9% of the LD50.  RQs calculated on
this basis are shown below.  At the time of this assessment, OPP has an
interim listed species acute risk LOC for terrestrial insects, but does
not have a corresponding LOC for non-listed species.



g ai/bee)

0.50

(Pine seedlings, Region 1)	Small insects	<0.09 a	8.64

	Large insects	<0.01	0.96

0.375

(Regions 1, 2)	Small insects	<0.07 a	6.48

	Large insects	<0.01	0.72

0.017 

(Region 5)	Small insects	<0.03	2.94

	Large insects	<0.01	0.32

a Equals or exceeds interim listed species acute risk LOC (0.05)

Non-guideline field tests on earthworms submitted by the registrant
showed that fomesafen did not have observable adverse effects on total
numbers, total weights, or numbers of individual species at a treatment
level of 0.45 lb ai/A.  Decline in the population of one species of
earthworms in the test plots was attributed to the change in plant cover
on the plot as a result of the herbicide application.

6.0	Risk Description

Aquatic Risk

Based on currently available data, fomesafen appears to be of relatively
low toxicity to aquatic animals in freshwater and estuarine/marine
systems.  Both acute and chronic effects were considered.  Fomesafen is
a light-dependent peroxidizing herbicide (LDPH), and may be more toxic
under conditions of natural sunlight than in laboratory lighting
(Matringe 1989).  The Agency has proposed testing this class of
compounds under ultra-violet (UV) light conditions (EFED 2007), but as
of the time of this risk assessment, such data were not available for
fomesafen.  Based on fish early-life cycle tests submitted for
oxyfluorfen, another chemical in this class, UV light conditions appear
to increase the toxicity by approximately an order of magnitude (MRID
46585104).  To evaluate the effect of this increase in toxicity, fish
early life cycle endpoints were adjusted by an order of magnitude and
RQs were recalculated for all scenarios modeled.  In all cases, RQs were
<0.015.  It should be noted, however, that the freshwater fish early
life cycle endpoint was based on an ACR calculated from the saltwater
fish studies, thus considerable uncertainty surrounds this endpoint. 
Based on the effects noted in the oxyfluorfen study (decreased hatching
time and reduced larval survival) and the mode of action of LDPHs, it
seems possible that oxyfluorfen may have affected the viability of the
egg cell membrane surrounding the larva. Given this possibility,
extrapolation of the enhanced toxicity to the fish life stages used in
the acute toxicity tests was not judged to be appropriate.  No tests
conducted under UV light conditions were available for aquatic
invertebrates, thus the type or magnitude of phototoxic effects on these
types of organisms is unknown.  Given that many zooplankters have
translucent bodies, and are present in the surface layers of water
bodies where UV rays might penetrate (Barron et al 2000, Diamond et al
2005), photoenhanced toxicity to these taxa is a possibility.

In aquatic ecosystems, aquatic plants are the taxa most sensitive to
fomesafen.  Aquatic plants (both vascular and non-vascular) are the
primary producers, and may serve as the primary energy base in some
aquatic systems either via consumption by herbivores or energy input to
the detrital food web.  Perturbations to the base of the food chain have
the potential to modify community structure and/or productivity of the
affected system.  There are no acute risk LOC exceedences for any
application rates.  RQs exceed the listed species LOC for freshwater
non-vascular plants for the application rate of 0.375 lb ai/A in some
scenarios modeled, and for the application rate of 0.5 lb ai/A in all
scenarios modeled.  However, EECs (2-25 g/L) do not exceed the LOAEC
(23 g/L), which is based on a 9% inhibition in biomass
(MRID46673804).  Mesocosm studies (Caquet et al 2005, Caquet 2006) show
that fomesafen concentrations of 30-60 g/L can cause perturbations in
the system, but these perturbations are primarily associated with shifts
in species composition and abundance rather than primary productivity. 
Mesocosm studies conducted by Pershbarger et al (1997) indicate
short-term effects on phytoplankton abundance and composition from
concentrations of fomesafen ≤60 g/L are not measurable, but it must
be noted that their experimental system was dominated by blue-green alga
(EC50 = 71,000 g/L, MRID 46673807), which are less sensitive to
fomesafen than the green alga (EC50 = 92 g/L, MRID 46673804).  The
mesocosm studies were both conducted outdoors under natural sunlight
conditions, thus any photoenhancement of fomesafen toxicity for these
taxa would be implicitly incorporated into study results.  Measurable
differences in the algal composition and productivity of water bodies
receiving runoff from fields treated with fomesafen at the application
rates evaluated in this document are not anticipated.  At the time of
this assessment, there were no listed freshwater non-vascular plants,
and no indications of any obligate relationships between a listed
species and freshwater algae.  

Fomesafen may indirectly affect aquatic systems by damaging plants in
adjacent wetland or riparian zones.  Modification of the vegetation in
wetlands or riparian zones could cause decreased allochthonous input,
increased sediment input, destabilization of the stream bank, or changes
in the structural components (plant).  Effects on waterbody associated
plant communities can be minimized by ensuring an adequate offset
distance is maintained between the application site and the wetland or
riparian zone.  Appropriate offset distances are discussed in the
terrestrial plants section.



Table   SEQ Table \* ARABIC  25   Summary of Risk to Non-listed Aquatic
Organisms

Assessment Endpoint	Crops	Estimator	LOC Exceedence

Freshwater

Acute Toxicity to Fish and Aquatic-phase Amphibians	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Chronic Toxicity 

Fish and Aquatic-phase Amphibians	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Acute Toxicity to Aquatic Invertebrates	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Chronic Toxicity 

Aquatic Invertebrates	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Acute Toxicity to Aquatic Plants 

(non-vascular)	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Acute Toxicity to Aquatic Plants (vascular)	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Saltwater

Acute Toxicity to Fish	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Chronic Toxicity to Fish 	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Acute Toxicity to Aquatic Invertebrates	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Chronic Toxicity

Aquatic Invertebrates	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Acute Toxicity to Aquatic Plants 	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No



Terrestrial Risk

In general, fomesafen presents low risk to terrestrial animals on an
acute basis, with no acute LOC exceedences for either birds or mammals. 
However, there are chronic LOC exceedences for both birds and mammals at
all application rates.  Fomesafen poses a risk to terrestrial plants,
especially dicots, in areas which may be subject to drift or runoff from
the application site.  Due to the sensitivity of dicots to fomesafen,
effect from drift may occur as far away from the use site as 1,000 ft
for aerial applications and 300 ft for ground applications.

6.2.1	Birds, Reptiles, and Amphibians

In the avian reproduction study on mallard ducks (MRID 135639), no
endpoints were affected, thus the NOAEC was established as the highest
dose tested (46 mg/kg diet).  No LOAEC was determined, so based on the
available data, the meaning of the chronic LOC exceedences for birds is
difficult to interpret, either in terms of which endpoints might be
affected, or if chronic exposure to fomesafen is at levels that would
trigger these effects.  

It should also be noted that generally bobwhite quail, which were not
tested for fomesafen, are more sensitive than mallard ducks.  Avian data
for fomesafen and several structurally similar compounds, acifluorfen
(PCs 114401-114404), oxyfluorfen (PC 111601), and lactofen (PC 128888),
is presented below.  The data available for the other chemicals suggests
reproductive effects of fomesafen may include reduction in embryo
survival, number of hatchlings, and/or number of eggs laid.  The data
also suggests that bobwhite quail are the more sensitive species for
this class of chemicals, thus the mallard data used in the risk
assessment may underestimate the risk to more sensitive species. 
Mammalian data were also considered in an attempt to characterize the
potential chronic toxicity for birds.  Reproductive effects were noted
in the lactofen and oxyfluorfen tests.

Because the reported NOAECs and LOAECs are in part an artifact of the
test concentrations selected and sufficient data points are not
available to generate chronic dose-response curves, no specific
conclusions should be drawn regarding relative toxicity of the
compounds.  In the absence of more definitive chronic avian data for
fomesafen, the Agency concludes that there is a chronic risk to
insectivorous or herbivorous birds, reptiles, and/or terrestrial-phase
amphibians foraging in or near the treated area for all application
rates.  Potential effects on the fecundity of frugivorous birds foraging
in or near the treated area should be anticipated for the 0.5 lb ai/A
application rate.



Table   SEQ Table \* ARABIC  26   Comparison of Chronic Data for
Acifluorfen, Fomesafen, and Oxyfluorfen.

Chemical	Test Organism	NOAEC

(mg/kg diet)	LOAEC

(mg/kg diet)	Endpoints Affected

Avian

Acifluorfen

(PC114401)	Bobwhite quail

(MRID 107491)	20	100	Reduced number of embryos

	Mallard duck

(MRID 107492)	100	>100	No endpoint affected

Fomesafen	Mallard duck

(MRID 135639)	46	>46	No endpoint affected

Lactofen

(PC128888)	No chronic data available

Oxyfluorfen

(PC111601)	Bobwhite quail

(MRID 46070102)	124	256	Survivor weight, embryo survival, number of
hatchlings

	Mallard duck

(MRID 46070101)	506	751	Eggs laid, embryo survival, number of hatchlings

Mammalian

Acifluorfen

(PC114401)	Rat

(MRID155548)	2500	ND	No reproductive effects

Fomesafen	Rat

(MRID144862)	1000	ND	No reproductive effects

Lactofen

(PC128888)	Rat

(AC73859)	50	500	Reduced pup weight

Oxyfluorfen

(PC111601)	Rat

(MRID42014901)	400	1600	Decreased body weight, # live pups/litter

6.2.2	Mammals

For mammals, no acute LOCs were exceeded at any application rate.  The
chronic LOC was exceeded only for small (15g) mammals eating short grass
at the highest application rate (0.5 lb ai/A, pine seedlings in AR, GA,
MS, NC, and SC).  Thus effects on the endpoints of growth, survival, and
fecundity are not anticipated at the 0.375 lb ai/A application rate.

Open literature data demonstrated elevated levels of liver and fecal
porphyrins in mice fed 100 mg/kg diet for 10 days (Krijt et al 1994b). 
Based on TREX estimates of dietary EECs, only the 0.5 lb ai/A rate
exceeds 100 mg/kg rate.  Given the existing body of data regarding
fomesafen effects on the liver porphyrins of small mammals, effects on
this biochemical endpoint appear unlikely, although there is a
difference in sensitivity amongst strains of mice (Krijt et al 1994a). 
Where laboratory mice strains are in a species sensitivity distribution
as compared to small wild mammals is unknown.

6.2.3	Terrestrial Invertebrates

Based on available data, effects on terrestrial invertebrates, while
possible, do not appear likely.  Lack of indicated toxicity in guideline
bee studies, guideline aquatic invertebrate studies, and non-guideline
studies on soil invertebrates, arthropods, and in aquatic mesocoms
support this conclusion.



Table   SEQ Table \* ARABIC  27   Summary of Risk to Non-Listed
Terrestrial Animals

Assessment Endpoint	Application Rate

lb ai/A	Size Class

(g)	LOC Exceedence1	Clearance estimate





Distance from site (ft)	Rate

(lb ai/A)

Vertebrates

Acute Risk to Mammals	0.5	15

35

1000	No

No

No	Clears at current rate

	0.375	15

35

1000	No 

No

No	Clears at current rate

	0.17	15

35

1000	No

No

No	Clears at current rate

Chronic Risk to Mammals	0.5	15

35

1000	Yes (SG)

No

No	Aerial 02

Ground 10	0.473

Clear

Clear

	0.375	15

35

1000	No

No

No	Clears at current rate

	0.17	15

35

1000	No

No

No	Clears at current rate

Acute Risk to Birds, Terrestrial-phase Amphibians, and Reptiles	0.5	20

100

1000	No

No

No	Clears at current rate

	0.375	20

100

1000	No

No

No	Clears at current rate

	0.17	20

100

1000	No

No

No	Clears at current rate

Chronic Risk to Birds, Terrestrial-phase Amphibians, and Reptiles	0.5
All	Yes (SG, TG, BL, SL)	Aerial 100

Ground 10	0.192

	0.375	All	Yes (SG, BL)	Aerial 100

Ground 10	0.192

	0.17	All	Yes (SG)	Aerial 100

Ground 10	0.192

Invertebrates

Acute Risk to Invertebrates	All rates	All	Risk appears unlikely	Not
applicable

1 LOC exceedences using more conservative dose-based estimates

2 AgDrift clearance estimate is ~45% deposition directly below aircraft

3 Clearance level is for short grass estimate 

4 OPP does not currently have an acute risk LOC for non-listed
terrestrial invertebrates

Feeding categories:  short grass (SG), tall grass (TG), broadleaf
plants, small insects (BL), seeds, large insects (SL), granivore-mammals
only (G)

NA – Not applicable

6.2.4	Plants

The non-target organisms of greatest concern for fomesafen are plants in
the overspray, runoff, and spray drift zones.  Fate data do not indicate
fomesafen is likely to be subject to long-range atmospheric transport,
thus this route of exposure has not been addressed in the assessment. 
It is, however, persistent in soil, and may affect plants growing in the
soil of treated fields or overspray areas for an extended period
(approximately a year) following application.  Because of the
persistence, it is also likely to accumulate in fields repeatedly
treated with fomesafen, even if the field is only treated in alternate
years.  The theoretical maximum concentration occurs in about 10 years
if the field is treated in alternate years.  Maximum residual
concentration for an application rate of 0.375 lb ai/A is 0.29 lb ai/A,
and for an application rate of 0.5 lb ai/A is 0.38 lb ai/A.  These
concentrations are greater than the seedling emergence EC25s of the most
sensitive dicot (tomato, EC25 0.005 lb ai/A) and the most sensitive
monocot (onion, EC25 0.084 lb ai/A).

Shallow groundwater used for irrigation of agricultural fields could
potentially contain sufficient fomesafen to affect some crops.  Based on
estimated concentrations delivered to a field receiving 2 inches of
irrigation water (0.0004-0.0077 lbs ai/A, based on application rate of
0.5 lb ai/A to field), sensitive crop species such as radish, lettuce,
oilseed rape, and tomato (EC25s of 0.002-0.008 lb ai/A) could be
affected.  How long fomesafen will persist in the groundwater is not
well defined. 

Fomesafen has the potential to adversely affect plant communities of
concern beyond the edges of the treated field.  Plants potentially
affected by fomesafen include crops in neighboring fields, hedgerows,
riparian zones, and wetlands.  Using AgDrift (Tier 1), EFED was unable
to calculate the distance required for the acute plant risk to fall
below the LOC for aerial applications, with toxicity predicted to occur
at least to 900 ft beyond the application point for aerial applications
and 300 ft for ground applications.  Potential runoff effects to
wetlands near the treatment site are difficult to evaluate, as the
amount of runoff is greatly influenced by slope, presence of buffers,
and degrees of channelization in runoff swales.  Wetlands receiving
direct runoff from treated sites are likely to be affected.

Because fomesafen is an herbicide, it may affect the primary
productivity, community composition, and/or structure of herbaceous
communities located near the margins of the treated fields.  EFED has no
data with which to evaluate the potential effect on woody plants,
although given the mode of action for fomesafen (cell membrane
disruption), woody plants may be more resistant.  Modifications to the
plant community may have significant effects on the populations of
animals dependent on those communities.

Table   SEQ Table \* ARABIC  28   Summary of Risk to Non-listed
Terrestrial Plants

Assessment Endpoint	Type of Plant	Application Rate

lb ai/A	LOC Exceedence2	Clearance estimate1





Distance from site (ft)	Rate

(lb ai/A)

Acute Risk to Monocots	Aerial Application

	Upland	0.5	No	Clears at current rate

(Based on 

runoff and drift)



0.375	No



	0.312	No



	0.25	No



	0.17	No



Wetland	0.5	Yes	100	0.084



0.375	Yes





0.312	Yes





0.25	Yes





0.17	Yes



	Ground Application

	Upland	0.5	No	Clears at current rate

(Based on 

runoff and drift)



0.375	No



	0.312	No



	0.25	No



	0.17	No



Wetland	0.5	Yes	10	0.084



0.375	Yes





0.312	Yes





0.25	Yes





0.17	Yes



Acute Risk to Dicots	Aerial Application

	Upland	0.5	Yes	>900	0.002



0.375	Yes





0.312	Yes





0.25	Yes





0.17	Yes



	Wetland	0.5	Yes





0.375	Yes





0.312	Yes





0.25	Yes





0.17	Yes



	Ground Application

	Upland	0.5	Yes	300	0.002



0.375	Yes	200



	0.312	Yes	200



	0.25	Yes	150



	0.17	Yes	80



Wetland	0.5	Yes	300



	0.375	Yes	200



	0.312	Yes	200



	0.25	Yes	150



	0.17	Yes	80

	1  Based on drift estimates from AgDrift, does not include runoff

6.3	Endangered Species 

6.3.1	Aquatic Listed Species

No aquatic endangered species are at risk for direct effects from
fomesafen.  Although there are listed species LOC exceedences for
freshwater non-vascular plants, there were no listed freshwater
non-vascular plants at the time of this assessment.  Additionally, no
listed species have been identified as having an obligate relationship
with freshwater non-vascular plants.  This results in a determination of
no effect for aquatic organisms on the basis of direct effects. 
Indirect effects to aquatic organisms are possible, based on potential
effects on riparian and wetland plant communities.  For an evaluation of
indirect effects, please see the section on endangered plants.

Table   SEQ Table \* ARABIC  29   Summary of Risk to Listed Aquatic
Organisms

Assessment Endpoint	Crops	Estimator	LOC Exceedence

Freshwater

Acute Toxicity to Fish and Aquatic-phase Amphibians	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Chronic Toxicity 

Fish and Aquatic-phase Amphibians	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Acute Toxicity to Aquatic Invertebrates	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Chronic Toxicity 

Aquatic Invertebrates	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Acute Toxicity to Aquatic Plants 

(non-vascular)	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	Yes

Yes

No

Acute Toxicity to Aquatic Plants (vascular)	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Saltwater

Acute Toxicity to Fish	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Chronic Toxicity to Fish 	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Acute Toxicity to Aquatic Invertebrates	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Chronic Toxicity

Aquatic Invertebrates	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No

Acute Toxicity to Aquatic Plants 	Pine seedlings

Cotton, Beans (soy, snap, dry)

Cotton, Beans (soy, snap, dry)	MS cotton (0.5lb ai)

TX cotton (0.375 lb ai)

MI beans (0.375 lb ai)	No

No

No



Terrestrial Listed Species

There are no listed species acute risk LOC exceedences for birds or
mammals.  Chronic risk LOCs were exceeded for herbivorous birds at all
application rates except the 0.17 lb ai/A rate (Region 5).  Chronic risk
LOCs were exceeded for insectivorous birds at applications rates of
0.375 lb ai/A and higher (Region 1 & 2).  As birds are the surrogate for
reptiles and terrestrial-phase amphibians, these exceedences also apply
to those taxa.  Exceedences are based on a non-definitive endpoint from
a guideline study, and thus may overestimate risk.  In absence of a
definitive endpoint, the Agency assumes effects may occur at any
exposure concentrations about the established NOAEC.  The AgDrift model
was used to estimate the distances from the application site for
exposure to drop below the level of concern based on the most
conservative estimator (short grass).  The resulting clearance distances
were 10 ft for ground applications and 100 ft for aerial applications. 
Thus, for listed insectivorous and herbivorous birds, reptiles, or
amphibians nesting or foraging within 100 ft of the application source,
the direct effects determination is may affect, likely to adversely
affect.  For organisms located greater than 100 ft away from the field,
the direct effects determination is no effect.    REF _Ref217117673 \h 
\* MERGEFORMAT  Table 31  and   REF _Ref217117726 \h  \* MERGEFORMAT 
Table 32  show which species have been identified as potentially at
risk, based on application rate, geographic location, and dietary
habits.  Indirect effects on listed birds, reptiles, and
terrestrial-phase amphibians are possible, based on potential effects on
plant communities and/or designated habitat.  For an evaluation of
indirect effects, please see the section on endangered plants.

For mammals, there were no listed species acute risk LOC exceedences or
chronic risk LOC exceedences for any of the existing Section 3
application rates.  For application rates of 0.375 lb ai/A or less, the
effects determination for mammals is no effect.  Chronic risk LOCs were
exceeded for the small herbivorous mammals (15g) at the 0.5 lb ai/A
application rate, which applies only to pine seedlings in AR, GA, MS
,NC, and SC.  Based on the available data (LOCATES and dietary
information), no listed small herbivorous mammals occur in these
locations.

Table   SEQ Table \* ARABIC  30   Summary of Risk to Listed Terrestrial
Animals

Assessment Endpoint	Application Rate

lb ai/A	Size Class

(g)	LOC Exceedence1	Clearance estimate





Distance from site (ft)	Rate

(lb ai/A)

Vertebrates

Acute Risk to Mammals	0.5	15

35

1000	No

No

No	Clears at current rate

	0.375	15

35

1000	No 

No

No	Clears at current rate

	0.17	15

35

1000	No

No

No	Clears at current rate

Chronic Risk to Mammals	0.5	15

35

1000	Yes (SG)

No

No	Aerial 02

Ground 10	0.473

Clear

Clear

	0.375	15

35

1000	No

No

No	Clears at current rate

	0.17	15

35

1000	No

No

No	Clears at current rate

Acute Risk to Birds, Terrestrial-phase Amphibians, and Reptiles	0.5	20

100

1000	No

No

No	Clears at current rate

	0.375	20

100

1000	No

No

No	Clears at current rate

	0.17	20

100

1000	No

No

No	Clears at current rate

Chronic Risk to Birds, Terrestrial-phase Amphibians, and Reptiles	0.5
All	Yes (SG, TG, BL, SL)	Aerial 100

Ground 10	0.192

	0.375	All	Yes (SG, BL)	Aerial 100

Ground 10	0.192

	0.17	All	No	Clears at current rate

Invertebrates

Acute Risk to Invertebrates	0.5	All	Yes	Aerial 0

Ground 10	0.28

	0.375	All	Yes



	0.17	All	No	Clears at current rate

1 LOC exceedences using more conservative dose-based estimates

2 AgDrift clearance estimate is ~45% deposition directly below aircraft

3 Clearance level is for short grass estimate 

4 OPP does not currently have an acute risk LOC for non-listed
terrestrial invertebrates

Feeding categories:  short grass (SG), tall grass (TG), broadleaf
plants, small insects (BL), seeds, large insects (SL), granivore-mammals
only (G)



Indirect Effects and Critical Habitat Effects (Birds, Reptiles,
Amphibians, and Mammals)

The most likely indirect effect on listed animals is modification of
habitat as a result of damage to plants.  The habitat modification could
include reduced food supply, locations for nesting or burrowing, and/or
reduced cover for predator avoidance.  Both monocots and dicots are
affected by fomesafen, although based on available data, effects on
sensitive species of dicots occur at lower concentrations.  The
assessment endpoint used for non-listed plant species is the EC25, a
measure of a 25% reduction in the most sensitive endpoint for the most
sensitive plant.  Although plant sensitivity to fomesafen varies,
determining the range of sensitivities in plant communities near
application sites is beyond the scope of this assessment.  For
fomesafen, the most sensitive endpoints are typically biomass and
percent survival.  While it is difficult to predict community-level
effects on the plant community supporting the listed plants, a 25%
reduction in these endpoints is likely to reduce the viability of any
affected population.  Degradation of habitat could indirectly affect
listed species in a number of ways.  Thus, for purposes of this
assessment, exceedence of the non-listed plant LOC is considered a
“may affect, likely to adversely affect” for listed animals, and has
the potential to modify designated critical habitat for habitat located
within 1,000 ft of aerial applications and 850 ft of ground
applications.

Potential mitigation measures include but are not limited to: 1) 
restricting applications of fomesafen within 1,000 ft of populations of
endangered plants, and 2)  restricting applications of fomesafen at
sites where runoff to wetland areas is likely. Removal of aerial
application methods from the label is another possibility.  However, in
light of the fact that anticipated effects zones are almost as wide for
ground applications, this may not be the most beneficial mitigation.



Table   SEQ Table \* ARABIC  31 .  Listed birds potentially at risk from
fomesafen

Common Name	Scientific Name	Pine	Soybean	Cotton	Dry Beans	Snap Beans

Flycatcher, Southwestern Willow	Empidonax trailii extimus

R1	R1	R1

	Plover, Piping	Charadrius melodus	R1	R1, R2	R1, R2	R1, R2	R1, R2

Tern, California Least	Sterna antillarum browni

R1	R1	R1

	Tern, Interior Least	Sterna antillarum	R1	R1, R2	R1

R1, R2

Warbler, Bachman’s	Vermivora bachmanii	R1	R2

	R1, R2

Warbler, Golden-cheeked	Dendroica chrysoparia	R1	R1	R1	R1	R1

Warbler, Kirtland’s	Dendroica kirtlandii	R1	R1, R2	R1

R1, R2

Woodpecker, Red-cockaded	Picoides borealis	R1	R1, R2	R1, R2	R1	R1, R2

Woodpecker, Ivory-billed	Campephilus principalis

R2

	R2



Table   SEQ Table \* ARABIC  32 .  Listed reptiles and amphibians
potentially at risk from fomesafen

Common Name	Scientific Name	Pine	Soybean	Cotton	Dry Beans	Snap Beans

Frog, Dusky Gopher	Rana capito sevosa	R1



R1

Salamander, Cheat Mountain	Plethodon nettingi

R2

	R2

Salamander, Flatwoods	Ambystoma cingulatum	R1	R1	R1

R1

Salamander, Red Hills	Phaeognathus hubrichti	R1	R1	R1

R1

Salamander, Shenandoah	Plethodon shenandoah

R2

	R2

Toad, Houston	Bufo houstonensis	R1	R1	R1	R1	R1

Tortoise, Gopher	Gopherus polyphemus	R1	R1	R1	R1	R1

Turtle, Alabama Red-bellied	Pseudemys alabamensis	R1	R2	R1

R1

Turtle, Northern Bog	Clemmys muhlenbergii

R1

R2	R2

Turtle Flattened Musk	Sternotherus depressus	R1	R3	R1	R1	R1

Turtle Plymouth Red-bellied	Pseudemys rebriventris bangsi



	R3

Turtle, Ringed Sawback	Graptemys oculifera	R1	R1	R1	R1	R1

Turtle, Yellow-blotched Map	Graptemys flavimaculata	R1	R2	R1	R1	R1





Table   SEQ Table \* ARABIC  33   Summary of Risk to Listed Plants

Assessment Endpoint	Type	Application Rate

lb ai/A	LOC Exceedence2	Clearance estimate1





Distance from site (ft)	Rate

(lb ai/A)

Acute Risk to Monocots	Aerial Application

	Upland	0.5	Yes	100	0.03



0.375	Yes





0.312	Yes





0.25	No	Clears at current rate



0.17	No



Wetland	0.5	Yes	100	0.03



0.375	Yes





0.312	Yes





0.25	Yes





0.17	No	Clears at current rate

	Ground Application

	Upland	0.5	Yes	20	0.03



0.375	No	Clears at current rate



0.312	No



	0.25	No



	0.17	No



Wetland	0.5	Yes	20	0.03



0.375	Yes	10



	0.312	Yes





0.25	Yes





0.17	Yes



Acute Risk to Dicots	Aerial Application

	Upland	0.5	Yes	>900	<0.002



0.375	Yes





0.312	Yes





0.25	Yes





0.17	Yes



	Wetland	0.5	Yes





0.375	Yes





0.312	Yes





0.25	Yes





0.17	Yes



	Ground Application

	Upland	0.5	Yes	300	<0.002



0.375	Yes	200



	0.312	Yes	200



	0.25	Yes	150



	0.17	Yes	80



Wetland	0.5	Yes	300



	0.375	Yes	200



	0.312	Yes	200



	0.25	Yes	150



	0.17	Yes	80

	6.3.3	Plants

Using LOCATES, a list of plants co-occurring with labeled crops was
generated.  For crops listed only on Syngenta labels, which contain
wording such that application outside the designated regions would be
considered misuse, search parameters were constrained to only states
listed on the label.  BASF labels (soybeans only) contained less
specific language, thus the search was nationwide, resulting in the
inclusion of Florida and Hawaii.  Table 30 shows the number of species
potentially affected by crop and state.  Numbers of monocots and dicots
are shown separately.  Ferns, cycads, and lichens, for which no data
were available, are listed with dicots, which are more sensitive to
fomesafen.

Direct Effects

Exceedences of endangered species LOC (based on NOAECs) for the most
sensitive plants tested constitute a “may affect” determination. 
Based on this definition, use of fomesafen may affect listed plants of
all varieties located near the application site.  Spray drift analysis
using AgDrift (Tier I, Terrestrial Assessment, Point Deposition, ASAE
fine to medium spray) resulted in clearance distances of approximately
1,000 ft for dicots, and 200 ft for monocots for aerial applications at
a maximum rate of 0.375 lb ai/A.  For ground applications, clearance
distances were estimated at 850 ft for dicots and 20 ft for monocots. 
As no data are available to evaluate the sensitivity of endangered
plants to fomesafen, all are conservatively assumed to be as sensitive
as the most sensitive species tested.  

While plants are not subject to the same “take” definitions as
animals, the dicot listed species clearance distances for fomesafen are
approximately the same as the dicot clearance distances for non-listed
species, which are based on a 25% reduction in the most sensitive
endpoint for the most sensitive plant.  For fomesafen, the most
sensitive endpoints are typically biomass and percent survival.  While
it is difficult to predict community-level effects on the plant
community supporting the listed plants, a 25% reduction in these
endpoints is likely to reduce the viability of any affected population.

Thus, fomesafen is likely to adversely affect dicots up to 1,000 ft away
from the application point, and likely to adversely affect monocots up
to 100 ft away from the application point for aerial applications, based
on the maximum application rate of 0.375 lb ai/A.  For ground
applications, the respective distances would be 850 ft for dicots, and
10 ft for monocots.

Note that spray drift estimates do not take into the account the effects
of runoff from the treated site.  Because runoff conditions and the
quality of vegetated buffers vary widely from site to site, these
effects are difficult to estimate in a general sense.  However, except
in cases of extreme channelization or nearly bare ground, runoff across
a 1,000 ft buffer is likely to be low.  Because fomesafen is less toxic
to monocots, a grassy buffer would likely be more effective.

Potential mitigation measures include but are not limited to: 1)
restricting applications of fomesafen within 1,000 ft of populations of
endangered plants, and 2) restricting applications of fomesafen at sites
where runoff to wetland areas is likely.  Removal of aerial application
methods from the label is another possibility.  However, in light of the
fact that anticipated effects zones are almost as wide for ground
applications, this may not be the most beneficial mitigation.

Indirect Effects

Pesticide-mediated indirect effects to plants are usually the loss of an
important pollinator or dispersal species.  Given the relatively low
toxicity of fomesafen to animals in general, the likelihood of these
types of effects appears to be extremely low.  Some endangered plant
species may require the presence of other non-endangered plant species
to create a suitable habitat.  Fomesafen effects on the habitat plants
could constitute an indirect effect, but without detailed information on
the plant’s life history and distribution, EFED is unable to even
qualitatively evaluate this type of effect.

6.3.4	Action Area

The action area is determined based on the furthest range of anticipated
effects. Based on the work of Russo et al (2007) and Russo and Madec
(2007), it appears that fomesafen induces an immune response in
freshwater snails and no definitive NOEC for this effect has been
experimentally determined. Therefore for purposes of the ESA, the action
area is considered to be the entire U.S.

Other than this sub-lethal snail immune response, the most sensitive
organisms evaluated are terrestrial dicots.  Based on an analysis with
AgDrift, deposition from aerial applications at the highest Section 3
rate (0.375 lb ai/A) at 950 ft away from the point of application will
be 0.004 lb ai/A.  The most sensitive endpoint is the dicot NOAEC of
0.002 lb ai/A.  At approximately 1,000 ft, the decline curve in AgDrift
based empirical measurements is asymptotic.  For a fine-to-medium
droplet size spray, only 1.2% of applied will be deposited on the
downwind side of the field, presuming no interception.

Thus, for practical reasons, the extent of these dicot effects is
estimated at 1,000 ft from point of application.  This applies to all
agricultural land in the regions where fomesafen is registered for use
under the existing Syngenta labels.

Table   SEQ Table \* ARABIC  34   Endangered Plants by Crop and State

State	Pine	Soybeans	Cotton	Dry Beans	Snap Beans

	Monocot	Dicot1	Monocot	Dicot1	Monocot	Dicot1	Monocot	Dicot1	Monocot
Dicot1

AL	3	13	3	11	3	13	1	1	3	12

AR

	0	3	0	2

	0	3

CT

	1	0

	0	2	1	1

DC

	2	0







DE





	2	0	2	0

GA	6	12	6	12	4	12

	6	11

IA

	2	4

	2	3	2	4

IL

	2	7



	1	7

IN

	1	4

	0	1	1	4

KS

	1	1	1	1

	1	1

KY

	0	10



	0	9

LA

	0	2



	0	2

MA

	1	0

	1	0	2	1

ME

	2	1

	2	1	2	1

MD

	2	4

	1	2	2	4

MI

	3	3

	3	2	3	5

MN

	2	1

	1	2	2	2

MO

	1	7	0	3	0	1	2	2

MS	0	3	0	3	0	3	0	1	0	3

NC	5	21	5	21	3	16	1	5	5	22

ND

	1	0

	1	0	1	0

NE

	1	1

	1	2	1	0

NH





	1	0	1	1

NJ

	3	2

	3	0	3	2

NY

	1	5

	1	5	1	5

OH

	2	4

	1	1	2	4

OK

	2	0



	2	0

PA

	2	0

	2	0	2	0

RI

	0	1



	1	1

SC	6	14	6	14	3	11	1	5	6	14

SD

	1	0

	1	0	1	0

TN

	2	18	0	5

	1	3

TX	2	5	2	14	2	24	2	11	2	13

VA

	1	3	2	7	0	1	4	13

VT

	0	1



	0	1

WI

	2	4



	2	4

WV





	0	1	1	4

BASF Labels only (soybeans nationwide)

FL

	1	25







HI

	11	74







Dicot1  This category also includes fern, lichens, and cycads, which are
reported separately in LOCATES.

Blank rows or section of rows indicate that crop does not co-occur with
any endangered plants in that state.

6.3.5	Probability of Individual Effects

Generally, available toxicity data provides an LC50 or an EC50, (the
concentration at which 50% of the test population exhibits the
designated endpoint, usually mortality).  Because the Endangered Species
Act (ESA) requires determination of potential effects at an individual
level, this information must be extrapolated from existing data. The
Agency uses the probit dose response relationship as a tool for deriving
the probability of effects on a single individual (U.S. EPA, 2004).  The
individual effects probability associated with the acute RQ is based on
the mean estimate of the probit dose response slope and an assumption
that that probit model is appropriate for the data set.  In some cases,
probit is not the appropriate model for the data, and EFED has low
confidence in extrapolations from these types of data sets.  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.  Individual effect probabilities are
calculated based on an Excel spreadsheet tool IECV1.1 (Individual Effect
Chance Model Version 1.1) developed by the U.S. EPA, OPP, Environmental
Fate and Effects Division (June 22, 2004).

Probability of individual effects for the various assessment endpoints,
if the acute RQ equals the endangered species LOC, is provided below in 
 REF _Ref160961235 \h  \* MERGEFORMAT  Table 35 .  Probablity of
individual effects is only evaluated for animals on an acute basis.  For
plant endangered species risk quotients and animal chronic risk
quotients, the endpoint used is a no effect level, thus an evaluation of
the probability of individual effects is not applicable.

Table   SEQ Table \* ARABIC  35   Probability of Individual Effects

Assessment Endpoint	Surrogate Species	LC50 and Slope	Fits Probit	Chance
of Individual Effect

Acute Toxicity to FW Fish	Rainbow trout	126 mg/L and 9.7 (lower bound)

126 mg/L and 14.6

126 mg/L and 19.5 (upper bound)

At LOC of 0.05	Yes	<1 in 1016

<1 in 1016

<1 in 1016

1 in 4.2×108

Acute Toxicity to FW Aquatic Invertebrates	Water flea	376 mg/L and 3.9
(lower bound)

376 mg/L and 5.6

376 mg/L and 7.3 (upper bound)

At LOC of 0.05	Yes	1 in 5.1x106

1 in 6.3x1012

<1 in 1016

1 in 4.2×108

Acute Toxicity to SW Fish	Sheepshead minnow	>163 mg/L and 4.5 (default
slope)

At LOC of 0.05	No	1 in 2.9x105

NA

Acute Toxicity to SW Aquatic Invertebrates	Mysid shrimp	>163 mg/L and
4.5 (default slope)

At LOC of 0.05	No	1 in 2.9x105

NA

Acute Toxicity to Mammals	Guinea pig	607 mg/kg and 4.5 (default slope)

At LOC of 0.1	No	1 in 2.9x105

1 in 2.9×105

Acute Toxicity to Birds, Terrestrial phase Amphibians and Reptiles
Mallard duck	Dose

>5,000 mg/kg and 4.5(default slope)

At LOC of 0.1

Diet

>20,000 mg/kg and 4.5(default slope)

At LOC of 0.1	No	

1 in 2.9x105

NA

1 in 2.9x105

NA

N.A. – Non-definitive endpoint.

6.4	Risk Conclusions

Fomesafen is persistent in surface and ground water, and has high
potential to leach to ground water, given its mobility in soil. 
Ecologically, the organisms most at risk from fomesafen are terrestrial
plants, especially dicots.  Because terrestrial plants are important
both ecologically (they provide a critical part of both the structure
and function that defines “habitat”) and economically (nearby
non-target, non-treated crop plants may be affected), these potential
impacts are an important consideration.  No LOCs were exceeded for
aquatic endpoints except the listed species LOC for freshwater
non-vascular plants.  At the time of this assessment, there were no
listed non-vascular freshwater plants, and no listed species had been
identified as having an obligate relationship with freshwater
non-vascular plants.  For terrestrial organisms, chronic LOCs were
exceeded for birds (and by extension, reptiles, and amphibians) at all
but the lowest application rate.  Chronic LOCs were exceeded for mammals
only for small herbivorous mammals at the highest application rate. 
These LOC exceedences apply to both listed and non-listed species. 
Based on spray drift estimations, clearance distances for chronic
exceedences are well within the clearance distances for terrestrial
plants, thus if terrestrial plants are protected, then by virtue of
sensitivity, other vulnerable organisms should be protected as well. 
Clearance distances for chronic effects on birds, reptiles, amphibians,
and mammals are 10 ft from the application source for ground
applications (based on low boom estimates) and 100 ft for aerial
applications (based on application parameters used in AgDrift Tier I
estimates).  For terrestrial plants, using drift estimates based on the
more sensitive dicots, effects should be anticipated as far as 850 ft
for ground applications, and 1,000 ft for aerial applications.



Table   SEQ Table \* ARABIC  36   Summary of Direct and Indirect Effects

Evaluation Organism	LOCATES Category	Direct Effects	Indirect Effects
Critical Habitat

Effects

Monocots	Monocots	Yes

Ground ≤100 ft

Aerial ≤ 100ft

from point of application	Yes

Potential for effects on other plants in the community.  Alteration of
habitat may create environment unsuitable to the listed species.

Effects may occur up to

Ground ≤300 ft

Aerial ≤ 900ft

from point of application	No?

(only listed monocot affected is aquatic)

Dicots	Other1	Yes

Ground ≤300 ft

Aerial ≤ 900ft

from point of application

No

(No potentially affected species have designated critical habitat

	Dicots

	Yes

(6 potentially affected species have designated critical habitat

Birds	Birds	Yes

Chronic Exceedences

Ground ≤10 ft

Aerial ≤ 100ft

from point of application	Yes

Potential for effects on other plants in the community.  Alteration of
habitat may create environment unsuitable to the listed species.

Effects may occur up to

Ground ≤300 ft

Aerial ≤ 900ft

from point of application	Yes

Potential for effects on other plants in the community.  Alteration of
habitat may create environment unsuitable to the listed species.

Effects may occur up to

Ground ≤300 ft

Aerial ≤ 900ft

from point of application

	Reptiles





Terrestrial Phase Amphibians



	Mammals	Mammals



	FW Aquatic Plants2	FW Aquatic Plants	No

No LOC exceedences



SW Aquatic Plants	SW Aquatic Plants



	FW Aquatic Invertebrates	FW Crustacea





FW Bivalves





FW Gastropods



	FW Fish	FW Fish





Aquatic Phase Amphibians



	SW Aquatic Invertebrates	SW Crustacea





SW Bivalves





SW Gastropods



	SW Fish	SW Fish



	1 Cycads, Conifers, Fern Allies. These genera have no direct corollary
test organism, and have been evaluated based on the most sensitive plant
endpoint.

2 Evaluated based on both non-vascular plants (algae) and vascular
plants (duckweed)



7.0	Uncertainties

Risk assessment, by its very nature, is not exact, and requires the risk
assessor to make assumptions regarding a number of parameters, to use
data which may or may not accurately reflect the species of concern, and
to use models which are a simplified representation of complex
ecological processes.  In this risk assessment, EFED has attempted to
locate the best available data regarding use and toxicity of fomesafen. 
Frequently, such information are better expressed as ranges rather then
points, and when this is the case, EFED has opted to make use of the end
of range which would result in a conservative estimate of risk.  These
uncertainties, and the directions in which they may bias the risk
estimate, are described below.

7.1	Exposure Assessment Uncertainties

7.1.1	Aquatic Exposure

Overall, the uncertainties inherent in the aquatic exposure assessment
tend to result in over-estimation of exposures.  This is apparent when
comparing modeling results with monitoring data.  Estimated peak
exposures are generally 1-2 orders of magnitude above the highest
detections in the monitoring data.  In general, the monitoring data
should be considered a lower bound on exposure, while modeling
represents an upper bound.  The modeling conservatively assumes that the
receiving water body and the application site are adjacent.

7.1.1.1	Modeling Assumptions

The uncertainties incorporated in the exposure assessment cannot be
quantitatively characterized.  However, given the available data and
EFED’s policy to rely on conservative modeling assumptions, it is
expected that the modeling results in an over-prediction in exposure. 
Qualitatively, conservative assumptions which may affect exposure
include the following: 

The assessment assumes all applications within the modeled watersheds
occur concurrently (same time and same day) at the maximum application
rate.

The assessment assumes all applications are at maximum label rate.

7.1.1.2	Monitoring Data

No surface water monitoring data was identified for fomesafen..
Groundwater data was only available from the registrant submitted
prospective groundwater study.

7.1.1.3	Impact of Vegetative Setbacks on Runoff

EFED does not currently have an effective tool to evaluate the impact of
vegetative setbacks on runoff and pesticide loadings.  The effectiveness
of such setbacks is highly dependent on the condition of the vegetative
strip.  A well-established, healthy vegetative setback can be a very
effective means of reducing runoff and erosion from agricultural fields
and may substantially reduce loading to aquatic ecosystems.  However, a
setback that is narrow, of poor vegetative quality, or channelized is
likely to be ineffective at reducing loadings.  The presence and quality
of setbacks are site-specific, and may vary widely, even within a small
geographic area.  EFED does not currently incorporate any “buffer
reduction” in its runoff exposure estimates.  Until such time as
quantitative methods to estimate the effect of vegetative setbacks of
various conditions on pesticide loadings become available, EFED’s
aquatic exposure predictions are likely to overestimate exposure where
healthy vegetative setbacks exist and may underestimate exposure where
poorly developed, channelized or no setbacks exist.

7.1.1.4	PRZM Modeling Inputs and Predicted Aquatic Concentrations

EFED used the linked PRZM/EXAMS model in this assessment, which produces
estimated aquatic concentrations based on site conditions and historical
meteorological files (generally 30-year).  The “peak” pesticide
concentration used in the assessment is probability-based, and is
expected to be exceeded once within a ten-year period.  PRZM is a
process-based "simulation" model, which calculates what happens to a
pesticide in a farmer's field on a day-to-day basis.  It considers
factors such as rainfall and plant transpiration of water, as well as
how and when the pesticide is applied.  The two major components are
hydrology and chemical transport.  Water movement in and off the field
is simulated by the use of generalized soil parameters, including field
capacity, wilting point, and saturation water content.  Soils in each
scenario are selected to represent high availability conditions for the
pesticide.  The chemical transport component simulates the method of
pesticide application on the soil or on the plant foliage and the
environmental processes acting on the pesticide.  Dissolved, adsorbed,
and vapor-phase concentrations in the soil are estimated by
simultaneously considering the processes of pesticide uptake by plants,
surface runoff, erosion, decay, volatilization, foliar wash-off,
advection, dispersion, and retardation.  

Uncertainty associated with each of these individual components adds to
the overall uncertainty of the modeled concentrations.  Equations in the
model have not been shown to exert any directional bias.  Model inputs
from the required environmental degradation studies are chosen to
represent the upper confidence bound of the mean, and are not expected
to be exceeded in the environment 90% of the time.  Mobility input
values are selected to be representative of conditions in the open
environment.  Natural variation in soils adds to the uncertainty of
modeled values.  Factors such as application date, crop emergence date,
and canopy cover can affect estimated concentrations.  Ambient
environmental factors, such as soil temperatures, sunlight intensity,
antecedent soil moisture, and surface water temperatures may cause
actual aquatic concentrations to differ from the modeled values.

Terrestrial Exposure Uncertainties

For terrestrial exposure estimates, the T-REX model is used to estimate
exposure and calculate RQs.

7.1.2.1	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
possible that much of these data reflect residues averaged over entire
above ground plants in the case of grass and forage sampling.

7.1.2.2	Dietary Intake

It was assumed that ingestion of food items in the field occurs at rates
commensurate with those in the laboratory. Although the screening
assessment process adjusts dry-weight estimates of food intake to
reflect the increased mass in fresh-weight wildlife food intake
estimates, it does not allow for gross energy differences.  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.  

Differences in assimilative efficiency between laboratory and wild diets
suggest that current screening assessment methods do not account for a
potentially important aspect of food requirements.  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. Environmental Protection Agency, 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.  In the screening process,
exposure may be underestimated because metabolic rates are not related
to food consumption.

7.2	Effects Assessment Uncertainties

7.2.1	Age Class and Sensitivity of Effects Thresholds

It is generally recognized that test organism age may have a significant
impact on the observed sensitivity to a toxicant.  For guideline tests,
young (and theoretically more sensitive) organisms are used.  Testing of
juveniles may overestimate toxicity at older age classes for active
ingredients of pesticides which act directly (without metabolic
transformation) on the organism, because younger age classes often have
not developed enzymatic systems associated with the detoxification of
xenobiotics.  When the available toxicity data provides a range of
sensitivity information with respect to age class, the risk assessors
use the most sensitive life-stage information as measures of effect. 

7.2.2	Use of Surrogate Species Data

Currently, there are no FIFRA guideline toxicity tests for amphibians or
reptiles.  Therefore, in accordance with EFED policy, data for the most
sensitive freshwater fish are used as a surrogate for aquatic-phase
amphibians, and data for the most sensitive bird are used as a surrogate
for terrestrial-phase amphibians and reptiles.  Use of data from the
most sensitive organism is assumed to be protective of the majority of
other organisms which may encounter the pesticide.

7.2.3	Extrapolation of Effects

Length of exposure and concurrent environmental stressors will likely
affect the response of the organism to fomesafen.  Because of the
complexity of an organism’s response to multiple stressors, the
overall direction of the response is unknown.  Additional environmental
stressors may decrease or increase the sensitivity to the herbicide. 
Timing, peak concentration, and duration of exposure are critical in
terms of evaluating effects, and these factors will vary both temporally
and spatially.  Overall, the effect of this variability may result in
either an overestimation or underestimation of risk

7.2.4	Acute LOC Assumptions

The risk characterization section of this assessment includes an
evaluation of the potential for individual effects.  The individual
effects probability associated with the acute RQ is based on the
assumption that the dose-response curve fits a probit model.  It uses
the mean estimate of the slope and the LC50 to estimate the probability
of individual effects.

References

Barron, MG, Little EE, Calfee R, and S. Diamond. 2000. Quantifying solar
spectral irradiance in aquatic habitats for the assessment of
photoenhanced toxicity.  Environmental Toxicology and Chemistry
19:920-925.

Diamond, SA, Trenham, PC, Adams MJ, Hossack, BR, Knapp, RA, Stark, SL,
Bradford, D, Corn PS, Czarnowski, K, Brooks, PD Fagre, D, Breen , B,
Detenbeck NE, and K Tonessen. 2005.  Estimated Ultraviolte radiation
doeses in wetlands in six national parks.  Ecosystems. 8:462-477.

EFED. 2007.  Memo on: Environmental Fate and Effects Division
recommendation regarding the light dependent peroxidizing herbicides
(LDPHs), DP Barcode D333803, dated 4/16/2007.

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.

HED 2006.  Fomesafen sodium human health risk assessment for a proposal
to amend se on soybeans and proposals to add uses on cotton, dry beans,
and snap beans.  DP Barcode D325797, dated 2/28/06.

Matringe, M, Camadro, J-M, Labbe, D, and R. Scalla. 1989. 
Protophorphyrinogen oxidase as a molecular target for diphenyl ether
herbiciceds.  Biochem J. 260:231-235.

Roberts, T. (Ed.). 1998. Metabolic Pathways of Agrochemicals, Part One:
Herbicides and Plant Growth Regulators. Royal Society of Chemistry,
Cambridge. 849pp.

Smith, L.L. and Elcombe, C.R., 1989. Mechanistic studies: their role in
the toxicological evaluation of pesticides. Food Addit. Contam. 6 Suppl.
1, pp. S57–S65.

U.S. EPA.  2004.  Overview of the Ecological Risk Assessment Process in
the Office of Pesticide Programs.  Office of Prevention, Pesticides, and
Toxic Substances.  Office of Pesticide Programs.  Washington, D.C. 
January 23, 2004.

U.S. EPA. 2006.  Fomesafen Sodium.  Human Health Risk Assessment for a
Proposal To Amend Use on Soybeans, and Proposals to Add Uses on Cotton,
Dry Bean and Snap Bean.  DP Barcode D325797.  Health Effects Division,
Office of Pesticide Programs, Washington D.C. February 28, 2006.

Guideline Study References

Avian Single Dose Oral Toxicity

163168  Roberts, N.; Fairley, C. (1981) The Acute Oral Toxicity (LD50)
of PP021 to the Mallard Duck: ICI/370/WL/80792. Unpublished study
prepared by Huntingdon Research Centre. 16 p

Avian Dietary Toxicity

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摧䇮~ᔀ; Fairley, C.; Woodhouse, R. (1981) The Subacute Dietary
Toxicity (LC50) of PP021 to the Bobwhite Quail: ICI 335/80798.
(Unpublished study received May 28, 1982 under 10182-EX-30; pre- pared
by Huntington Research Centre, England, submitted by ICI Americas, Inc.,
Wilmington, DE; CDL:247592-D)

163384  Roberts, N.; Fairley, C.; Woodhouse, R. (1981) The Subacute
Dietary Toxicity LC50 of PP021 to the Mallard Duck: HRC Report No. ICI
336/80816. Unpublished study prepared by Huntingdon Research Centre. 29
p.

Avian Reproduction

135639  Roberts, N.; Fairley, C.; Chanter, D.; et al. (1982) The Effect
of the Dietary Inclusion of Fomesafen on Reproduction in the Mal- lard
Duck: HRC Report No. ICI 338/82134. (Unpublished study re- ceived Nov
22, 1983 under 10182-83; prepared by Huntingdon Re- search Centre, Eng.,
submitted by ICI Americas, Inc., Wilming- ton, DE; CDL:072156-B)

135640  Roberts, N.; Fairley, C.; Hakin, B.; et al. (1982) The Effect of
Dietary Inclusion of Fomesafen on Reproduction in the Bobwhite Quail:
HRC Report No. ICI 337/82259. (Unpublished study re- ceived Nov 22, 1983
under 10182-83; prepared by Huntingdon Re- search Centre, Eng.,
submitted by ICI Americas, Inc., Wilming- ton, DE; CDL:072156-C)

Acute Toxicity to Freshwater Fish

103023  Hill, R.; Harland, B.; Maddock, B. (1981) PP021: Determination
of the Acute Toxicity of JF7383 a 25% w/v Formulation to Rainbow Trout
(Salmo gairdneri): BL/B/2026. (Unpublished study received May 28, 1982
under 10182-EX-30; prepared by Imperial Chemical Industries PLC, Eng.,
submitted by ICI Americas, Inc., Wilming- ton, DE; CDL:247592-E)

163169  Hill, R.; Maddock, B.; Harland, B. (1981) PP021: Determination
of the Acute Toxicity of JF 7383, a 25% w/v Formulation to Bluegill
Sunfish (Lepomis macrochirus): Brixham Report No. BL/B/2014; Brixham
Study No. F697/B. Unpublished study prepared by Imperial Chemical
Industries PLC. 20 p.

Acute Toxicity to Freshwater Invertebrates

103024  Edwards, P.; Brown, S.; Francis, P.; et al. (1980) PP021:
Toxicity of Technical Material and Formulation, JF7383, to First Instar
Daphnia magna: Report Series RJ 0111 B. (Unpublished study re- ceived
May 28, 1982 under 10182-EX-30; submitted by ICI Ameri- cas, Inc.,
Wilmington, DE; CDL:247592-G)



Acute Toxicity to Estuarine/Marine Organisms

135643  Jaber, M.; Hawk, R. (1982) The Acute Toxicity of PP021 as the
Aque- ous Sodium Salt (GFU060) to the Sheepshead Minnow: Report No.
TMUE0019/B. (Unpublished study received Nov 22, 1983 under 10182-83;
submitted by ICI Americas, Inc., Wilmington, DE; CDL: 072156-F)

135645  Jaber, M.; Hawk, R. (1982) The Acute Toxicity of PP021 as the
Aque- ous Sodium Salt (GFU 060) to the Fiddler Crab: Report No.
TMUE0020/B. (Unpublished study received Nov 22, 1983 under 10182-83;
submitted by ICI Americas, Inc., Wilmington, DE: CDL: 072156-H)

135646  Jaber, M.; Hawk, R. (1982) The Acute Toxicity of PP021 as the
Aque- ous Sodium Salt (GFU 060) to the Pink Shrimp: Report No.
TMUE0021/B. (Unpublished study received Nov 22, 1983 under 10182-83;
submitted by ICI Americas, Inc., Wilmington, DE; CDL: 072156-I)

135647  Jaber, M.; Hawk, R. (1982) The Acute Toxicity of Technical Grade
PP021 to Mysid Shrimp: Report No. TMUE0024/B. (Unpublished study
received Nov 22, 1983 under 10182-83; submitted by ICI Americas, Inc.,
Wilmington, DE; CDL:072156-J)

135649  Thompson, R.; Comber, M.; Hill, R. (1982) Fomesafen: Acute
Toxici- ty of JF 7383 to Larvae of the Pacific Oyster: Study No. G018/C;
Report No. BL/B/2219. (Unpublished study received Nov 22, 1983 under
10182-83; prepared by Imperial Chemical Industries PLC, Eng., submitted
by ICI Americas, Inc., Wilmington, DE; CDL: 072156-L)

Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study

135644  Hill, R.; Caunter, J.; Cornish, S. (1983) Fomesafen: The
Toxicity of an Aqueous Solution of Its Sodium Salt (JF7383) to
Sheepshead Minnow ... Embryos and Larvae: Study No. J530/C; Report No.
BL/ B/2293. (Unpublished study received Nov 22, 1983 under 10182- 83;
prepared by Imperial Chemical Industries PLC, Eng., submit- ted by ICI
Americas, Inc., Wilmington, DE; CDL:072156-G) 

Acute oral toxicity in rats

15523  Bathe, R. (1973) Acute Oral LDI50^ of Technical CGA-24705 in the
Rat: Project No. Siss 2979. (Unpublished study received Mar 1, 1974
under 5G1553; prepared by Ciba-Geigy, Ltd., submitted by Ciba-Geigy
Corp., Greensboro, N.C.; CDL:094220-B)

158241  Kieczka, H. (1985) Report on the Study of Acute Oral Toxicity on
the Rat ...: [BAS 530 04 H]: Project No. 10A123/85; Report No. 85/260.
Unpublished study prepared by BASF Aktiengesellschaft. 10 p.

64314  Hofmann, H.T.; Freisberg, K.O. (1974) Acute Oral Toxicity of the
Sodium Salt of 3-Isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one-
2,2-dioxide to the Rat. (Translation from German; unpublished study
received Jul 12, 1974 under 3G1309; prepared by BASF, W. Germany,
submitted by BASF Wyandotte Corp., Parsippany, N.J.; CDL:092065-R)

92065  Mobil Chemical Company (1971) ?Nematocides for the Control of
Nematodes in Sugarcane|. (Compilation; unpublished study, in- cluding
published data, received Jun 25, 1972 under 2F1204; CDL: 091025-A)

164900  Henderson, C. (1981) PP021: Acute Oral Toxicity, Skin Irritation
and Eye Irritation: CTL Report No. CTL/P/562. Unpublished study prepared
by Imperial Chemical Industries Ltd., Central Toxicolo- gy Laboratory.
25 p.

164901  Henderson, C. (1980) PP021: Acute Toxicity and Local Irritation:
CTL Report No. CTL/P/506. Unpublished study prepared by Imperial
Chemical Industries Ltd., Central Toxicology Labora- tory. 43 p.

40340802  Kieczka, H. (1985) Report on the Study of Acute Oral Toxicity
on the Rat Based on OECD of BAS 530 03H: Reg. Doc. #BASF 85/0258.
Unpublished study prepared by BASF Aktiengesellschaft. 14 p.

40439201  Barber, J. (1987) Fluazifop-P-Butyl/Fomesafen: Acute Oral
Toxicity to the Rat of a 0.75/1.0 lb/US gal Formulation: Rept. No.
CTL/P/ 1971. Unpublished study prepared by Imperial Chemical Industries,
Ltd. 27 p.

43236202  Duerden, L. (1994) Fomesafen: Acute Oral Toxicity to the Rat
of a 120g/l ME Formulation: Lab Project Number: CTL/P/4371: AR5709.
Unpublished study prepared by Zeneca Central Toxicology Lab. 49 p.

43949801  Lees, D.; Connolly, H. (1996) Fomesafen: Acute Oral Toxicity
to the Rat of a 240 g/l SL Formulation: Lab Project Number: AR6152:
CTL/P/4912. Unpublished study prepared by Zeneca Central Toxicology Lab.
59 p.

44030101  Robinson, P. (1996) Flexstar HL (Fomesafen): Acute Toxicity
Study in Rats of a 225.57 g/l ME Formulation: Lab Project Number:
AR6173: CTL/P/4949. Unpublished study prepared by Zeneca Central
Toxicology Laboratory. 62 p. 

44032401  Robinson, P. (1996) Fomesafen Sodium Salt Aqueous Concentrate:
Acute Oral Toxicity Study in Rats of a 316.1 g/L MUP Formulation: Lab
Project Number: AR6155: CTL/P/4979. Unpublished study prepared by Zeneca
Central Toxicology Lab. 62 p.

44036702  Robinson, P. (1996) Twister:
Fomesafen/Fenoxaprop/Fluazifop-p-Butyl: Acute (Oral) Toxicity Study in
Rats of a 130.78/19.22/68.42 g/L ME Formulation: Lab Project Number:
AR6174: CTL/P/4931. Unpublished study prepared by Zeneca Central
Toxicology Lab. 73 p.

2-generation repro.-rat

144862  Tinston, D.; Bishop, L.; Hollis, K.; et al. (1984) Fomesafen:
Two Generation Reproduction Study in the Rat: Report Nos. CTL/P/869 and
CTL/P/869S. Unpublished study prepared by Imperial Chemical Industries
PLC. 1052 p.

Registrant Submitted Non-guideline

135635 ICI Americas, Inc. (1983) Flex 2LC Herbicide (Containing
Fomesafen). (Compilation; unpublished study, Nov 22, 1983 under
10182-83; CDL:072153-A)

46585104  Palmer, S.; Kendall, T.; Krueger, H. (2005) Oxyfluorfen: An
Early Life-Stage Toxicity Test with the Fathead Minnow (Pimephales
promelas) Under Ultraviolet Light Conditions. Project Number: 379A/114,
040442. Unpublished study prepared by Wildlife International, Ltd. 127
p.

47587101  Overmeyer, JP, Wall, SB, Chen, W, Henry, KS. (2008) 
Supporting Data and Information for EPA’s Endangered Species
Assessments. Syngenta Crop Protection, Inc. Greensboro, NC.

ECOTOX References

Caquet, T. ( 2006). Use of Carbon and Nitrogen Stable Isotope Ratios to
Assess the Effects of Environmental Contaminants on Aquatic Food Webs. 
Environ.Pollut. 141: 54-59. 

	EcoReference No.: 95935

	Caquet, T., Deydier-Stephan, L., Lacroix, G., Le Rouzic, B., and
Lescher-Moutoue, F. (2005). Effects of Fomesafen, Alone and in
Combination with an Adjuvant, on Plankton Communities in Freshwater
Outdoor Pond Mesocosms.  Environ.Toxicol.Chem. 24: 1116-1124.

	EcoReference No.: 87334

Krijt, J., Psenak, O., Vokurka, M., Chlumska, A., and Fakan, F. (2003).
Experimental Hepatic Uroporphyria Induced by the Diphenyl-Ether
Herbicide Fomesafen in Male DBA/2 Mice.  Toxicol.Appl.Pharmacol. 189:
28-38.

EcoReference No.: 95588

	Krijt, J., Stranska, P., Sanitrak, J., Chlumska, A., and Fakan, F.
(1999). Liver Preneoplastic Changes in Mice Treated with the Herbicide
Fomesafen.  Hum.Exp.Toxicol. 18: 338-344.

EcoReference No.: 95400

	Krijt, J., Van Holsteijn, I., Hassing, I., Vokurka, M., and Blaauboer,
B. J. (1993). Effect of Diphenyl Ether Herbicides and Oxadiazon on
Porphyrin Biosynthesis in Mouse Liver, Rat Primary Hepatocyte Culture
and HepG2 Cells.  Arch.Toxicol. 67: 255-261.

EcoReference No.: 95026

Krijt, J., Vokurka, M., Sanitrak, J., and Janousek, V. (1994). Effect of
Protoporphyrinogen Oxidase Inhibitors on Mammalian Porphyrin Metabolism.
 ACS Symp.Ser. 559: 247-254.

EcoReference No.: 95589

	Krijt, J., Vokurka, M., Sanitrak, J., Janousek, V., Van Holsteijn, I.,
and Blaauboer, B. J. (1994). Effect of the Protoporphyrinogen
Oxidase-Inhibiting Herbicide Fomesafen on Liver Uroporphyrin and
Heptacarboxylic Porphyrin in Two Mouse Strains.  Food Chem.Toxicol. 32:
641-650.

EcoReference No.: 95399

Nemoto, M. C. M., Nahas, E., Pitelli, R. A., and Coelho, L. (2002).
Germination and Mycelial Growth of Bipolaris euphorbiae Muchovej &
Carvalho as Influenced by Herbicides and Surfactants.  Braz.J.Microbiol.
33: 352-357.

EcoReference No.: 95538

	Perschbacher, P. W., Stone, N., Ludwig, G. M., and Guy, C. B. Jr. (1997
). Evaluation of Effects of Common Aerially-Applied Soybean Herbicides
and Propanil on the Plankton Communities of Aquaculture Ponds. 
Aquaculture 157: 117-122.

EcoReference No.: 53095

	Russo, J., Lefeuvre-Orfila, L., and Lagadic, L. (2007).
Hemocyte-Specific Responses to the Peroxidizing Herbicide Fomesafen in
the Pond Snail Lymnaea stagnalis (Gastropoda, Pulmonata). 
Environ.Pollut. 146: 420-427.

EcoReference No.: 95100

	Russo, J. and Madec, L. (2007). Haemocyte Apoptosis as a General
Cellular Immune Response of the Snail, Lymnaea stagnalis, to a Toxicant.
 Cell Tissue Res. 328: 431-441.

EcoReference No.: 95590

 The classification is currently undergoing the QA/QC process within
EFED.

1 Guidance for Selecting Input Parameters in Modeling the Environmental
Fate and Transport of Pesticides. Version II, 2/28/02.

  Clarification of label language provided in email from James Stone,
Registration Division, OPP on May 1, 2008.  BASF labels (7969-82,
7969-83) contain the phrase “intended for use” in certain geographic
areas, which is too vague for use outside the listed areas to be
construed as misuse.

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Soil 

invertebrates

Soil accumulation, leaching and runoff

Terrestrial 

plants

Aquatic 

plants

invertebrates

vertebrates

Attribute

Change

Habitat integrity

Reduced cover

Community change

Food chain

Reduction in primary productivity

Reduction in prey

Shift in community composition

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Terrestrial 

insects

Birds and Mammals

Receptors

b

a

Spray drift

Direct application

Runoff

Source

Stressor

Fomesafen applied to crop

