  SEQ CHAPTER \h \r 1 				

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION

  SEQ CHAPTER \h \r 1 							PC Code 	128825

			DP Barcode	D384352

Date		December 22, 2010

MEMORANDUM

SUBJECT:	Revised EFED Registration Review Problem Formulation for
Bifenthrin

FROM:	José L. Meléndez, Chemist				

		Amanda Solliday, Biologist  

		Environmental Risk Branch V

		Environmental Fate and Effects Division (7507P)  

THROUGH:	Mah T. Shamim, Ph.D., Branch Chief

		Environmental Risk Branch V

		Environmental Fate and Effects Division (7507P)

		

TO:		Jacqueline Guerry, Chemical Review Manager

		Tracy Perry, Team Leader

Michael Goodis, Branch Chief

		Risk Management and Implementation Branch III

		Pesticide Re-evaluation Division (7508P)

The Environmental Fate and Effects Division (EFED) has completed the
revised problem formulation (attached) for the ecological risk,
environmental fate, endangered species, and drinking water assessment to
be conducted as part of the Registration Review of the pyrethroid
insecticide bifenthrin.  Functioning as the first stage of the risk
assessment process for registration review, this problem formulation
provides an overview of what is currently known about the environmental
fate and ecological effects associated with bifenthrin.  It also
describes the ecological risk hypothesis and analysis plan for
evaluating and characterizing risk to non-target species in support of
the registration of bifenthrin.  

As a result of public comments submitted to the public docket for the
preliminary problem formulation (dated June 9, 2010, document ID
EPA-HQ-OPP-2010-0384-0006 in   HYPERLINK "http://www.regulations.gov" 
www.regulations.gov  ), EFED has revised the problem formulation.  The
main revisions include:

1.	Revised conceptual model (i.e., risk hypothesis and conceptual
diagram), which was revised to stress the fact that bifenthrin is
applied over impervious surfaces when used on urban environments.  

2.	Updated Screening-Level Estimates of Agricultural Uses (SLUA) of
bifenthrin were provided.  

3.	Data on the effects of the synergist PBO on pyrethroid toxicity has
also been identified as part of the PBO work plan and supporting
documents (EFED Registration Review Problem Formulation for Piperonyl
Butoxide, dated December 13, 2010 [USEPA, 2010, D378420]).  

4.	The final risk assessment may also examine available information on
ecological risk from bifenthrin via land application of biosolids and
additional data may be required. 

5.	Clarification that the Agency is already in communication with CalDPR
regarding their pesticide reevaluation for pyrethroids and related data
should also be submitted to the Agency.

6.	Additional clarification of the challenges associated with cumulative
pyrethroid risk assessment in Section 2.2. Previous Risk Assessments,
Scientific Advisory Panels and Background.

In addition, the registrant-submitted fish full life cycle study for
bifenthrin (MRID 40791301) was formerly classified as supplemental.
Based on further review, this study is deemed invalid for quantitative
use in the final risk assessment and another fish full life cycle test
is requested at this time.

Based on the available data, it appears that bifenthrin is relatively
persistent in the environment under most circumstances.  Available data
suggests that it has the potential to bioaccumulate in terrestrial food
chains via consumption of contaminated aquatic organisms.  Bifenthrin is
very highly toxic to aquatic organisms, very highly toxic to terrestrial
invertebrates, and slightly to moderately toxic to birds and mammals.

Many of the environmental fate properties of bifenthrin are known. 
Nonetheless, there is uncertainty with respect to the aquatic metabolism
of bifenthrin and its overall persistence in the environment,
particularly in anaerobic environments.  Due to the very low solubility
of bifenthrin, there is concern with respect to the results of various
studies conducted in the presence of high levels of the cosolvent
acetonitrile.  The fate of bifenthrin in publicly-owned treatment works
(POTWs) is also an uncertainty.

There is uncertainty concerning the potential for adverse aquatic
effects, including benthic environments, for acute, chronic and
endangered species risk based on fate transport involving drift and
run-off, and persistence.  There is uncertainty concerning the potential
for adverse terrestrial effects for acute and endangered species risk to
birds, terrestrial invertebrates and plants based on fate transport,
drift and binding to the soil, and persistence.  In addition, there are
ecological data gaps that need to be addressed which increase
uncertainties in the preliminary risk picture for bifenthrin.  The
potential risk to pollinators and other beneficial insects from use of
bifenthrin appears to be high.

Environmental Fate and Ecological Risk Assessment Revised Problem
Formulation in Support of Registration Review for Bifenthrin

 

December 22, 2010

Environmental Fate and Effects Division

Office of Pesticide Programs

US Environmental Protection Agency

Prepared by:

Amanda Solliday, Biologist

N.E. Federoff, Wildlife Biologist

José L. Meléndez, Chemist

Secondary Revision:

Keith Sappington, Senior Scientist

Branch Chief

Mah T. Shamim, Ph.D.

Environmental Risk Branch V

Table of Contents

  TOC \o "1-3" \h \z \u    HYPERLINK \l "_Toc280784274"  1.	Purpose	 
PAGEREF _Toc280784274 \h  6  

  HYPERLINK \l "_Toc280784275"  2.	Problem Formulation	  PAGEREF
_Toc280784275 \h  6  

  HYPERLINK \l "_Toc280784276"  2.1.	Nature of Regulatory Action	 
PAGEREF _Toc280784276 \h  6  

  HYPERLINK \l "_Toc280784277"  2.2.	Previous Risk Assessments,
Scientific Advisory Panels and Background	  PAGEREF _Toc280784277 \h  7 


  HYPERLINK \l "_Toc280784278"  3.	Stressor Source and Distribution	 
PAGEREF _Toc280784278 \h  12  

  HYPERLINK \l "_Toc280784279"  3.1.	Mechanism of Action	  PAGEREF
_Toc280784279 \h  14  

  HYPERLINK \l "_Toc280784280"  3.2.	Overview of Pesticide Usage	 
PAGEREF _Toc280784280 \h  15  

  HYPERLINK \l "_Toc280784281"  3.3.	Environmental Fate and Transport	 
PAGEREF _Toc280784281 \h  28  

  HYPERLINK \l "_Toc280784282"  3.4.	Open Literature Information	 
PAGEREF _Toc280784282 \h  34  

  HYPERLINK \l "_Toc280784283"  4.	Receptors	  PAGEREF _Toc280784283 \h 
40  

  HYPERLINK \l "_Toc280784284"  4.1.	Aquatic and Terrestrial Effects	 
PAGEREF _Toc280784284 \h  40  

  HYPERLINK \l "_Toc280784285"  4.2.	Incident Database Review	  PAGEREF
_Toc280784285 \h  44  

  HYPERLINK \l "_Toc280784286"  4.3.	Ecosystems Potentially at Risk	 
PAGEREF _Toc280784286 \h  46  

  HYPERLINK \l "_Toc280784287"  5.	Assessment Endpoints	  PAGEREF
_Toc280784287 \h  46  

  HYPERLINK \l "_Toc280784288"  6.     Conceptual Model	  PAGEREF
_Toc280784288 \h  47  

  HYPERLINK \l "_Toc280784289"  6.1.	Risk Hypothesis	  PAGEREF
_Toc280784289 \h  47  

  HYPERLINK \l "_Toc280784290"  6.2.	Conceptual Diagram	  PAGEREF
_Toc280784290 \h  48  

  HYPERLINK \l "_Toc280784291"  7.        Analysis Plan	  PAGEREF
_Toc280784291 \h  53  

  HYPERLINK \l "_Toc280784292"  7.1.	Stressors of Concern	  PAGEREF
_Toc280784292 \h  53  

  HYPERLINK \l "_Toc280784293"  7.2.	Measures of Exposure	  PAGEREF
_Toc280784293 \h  54  

  HYPERLINK \l "_Toc280784294"  7.3.	Measures of Effect	  PAGEREF
_Toc280784294 \h  58  

  HYPERLINK \l "_Toc280784295"  7.4.	Integration of Exposure and Effects
  PAGEREF _Toc280784295 \h  59  

  HYPERLINK \l "_Toc280784296"  7.5.	Deterministic and Probabilistic
Assessment Methods	  PAGEREF _Toc280784296 \h  59  

  HYPERLINK \l "_Toc280784297"  7.6.	Endangered Species Assessments	 
PAGEREF _Toc280784297 \h  59  

  HYPERLINK \l "_Toc280784298"  7.7.	Drinking Water Assessment	  PAGEREF
_Toc280784298 \h  60  

  HYPERLINK \l "_Toc280784299"  7.8.	Endocrine Disruptor Screening
Program	  PAGEREF _Toc280784299 \h  61  

  HYPERLINK \l "_Toc280784300"  7.9.	Preliminary Identification of Data
Gaps	  PAGEREF _Toc280784300 \h  61  

  HYPERLINK \l "_Toc280784301"  8.	References	  PAGEREF _Toc280784301 \h
 75  

  HYPERLINK \l "_Toc280784302"  9.	Fate and Eco-Toxicity Bibliography	 
PAGEREF _Toc280784302 \h  80  

  HYPERLINK \l "_Toc280784303"  Appendix A.   PRD data request
justification tables	  PAGEREF _Toc280784303 \h  89  

 

1.	Purpose

The purpose of this problem formulation is to provide the foundation for
the ecological risk assessment being conducted for the registered uses
of bifenthrin.  As such, it articulates the purpose and objectives of
the risk assessment, evaluates the nature of the problem, and provides a
plan for analyzing the data and characterizing the risk (EPA, 1998). 
Additionally, this problem formulation is intended to identify data
gaps, uncertainties and potential assumptions needed to address those
uncertainties in characterizing the ecological risk associated with the
registered uses of bifenthrin. Bifenthrin is a type I synthetic
pyrethroid insecticide that is registered for a variety of agricultural,
non-agricultural and residential uses, such as (but not limited to)
corn, cotton, soybeans, green beans, caneberries, blueberries,
strawberries & raspberries, canola, pumpkins, peas, beans, broccoli,
canola, lettuce, artichokes, hops, pears, eggplants, citrus fruits,
spinach, grapes, potatoes, cilantro, okra, tomatoes, almonds, carrots,
peanuts, Swiss chard, Christmas tree plantations, conifers (seed
orchards), golf course turf, rights-of-way, ornamentals, residential
lawns, and for structural pest control.

2.	Problem Formulation

2.1.	Nature of Regulatory Action

This report summarizes the Environmental Fate and Effects Division’s
(EFED) Problem Formulation for the Registration Review of bifenthrin. 
Previous risk assessments were completed for the uses of the chemical
which serve as the basis for this assessment.

The Food Quality Protection Act of 1996 mandated the Environmental
Protection Agency (EPA or the Agency) to implement a new program, i.e.,
registration review (  HYPERLINK
"http://www.epa.gov/oppsrrd1/registration_review/" 
http://www.epa.gov/oppsrrd1/registration_review/ ). All pesticides
distributed or sold in the United States generally must be registered by
the EPA.  The decision to register a pesticide is based on the
consideration of scientific data and other factors showing that it will
not cause unreasonable risks to human health, workers, or the
environment when used as directed on product labeling.  The registration
review program is intended to ensure that, as the ability to assess risk
evolves and as policies and practices change, all registered pesticides
continue to meet the statutory standard of no unreasonable adverse
effects to human health and the environment.  Changes in science, public
policy, and pesticide use practices will occur over time.  Through the
new registration review program, the Agency periodically reevaluates
pesticides to make sure that as change occurs, products in the
marketplace can be used safely. 

As part of the implementation of the new Registration Review program
pursuant to Section 3(g) of the Federal Insecticide, Fungicide and
Rodenticide Act (FIFRA), the Agency is beginning its evaluation to
determine whether bifenthrin continues to meet the FIFRA standard for
registration.  This problem formulation for the environmental fate and
ecological risk assessment chapter in support of the registration review
is intended for the initial docket opening the public phase of the
review process.

2.2.	Previous Risk Assessments, Scientific Advisory Panels and
Background

Previous Ecological Risk Assessments

Recent risk assessments conducted on bifenthrin indicated risk concerns
for freshwater and estuarine/marine organisms.  In addition, there were
risk concerns for organisms living in the benthos (organisms residing in
the sediment layer, mainly invertebrates).  In 2008, the Agency issued
an assessment for the use of bifenthrin on bushberry (Crop Subgroup
13-B) and leafy petiole (Crop Subgroup 4-B) (D341634+; Federoff and
Meléndez, 2008).  The 2008 assessment was based on previously issued
assessments, since the use rates (maximum 0.5 lb a.i./A/season) were at
or below the maximum rate for previously approved uses.

In 2007, EFED issued an assessment for bifenthrin, for the use on
mayhaw, vegetable roots (except sugar beets), peanut, soybean, and
fruiting vegetables (Crop Subgroup B) (D336608; Meléndez and Federoff,
2007).  The seasonal rates for these crops ranged from 0.2 to 0.5 lb
a.i./A/season, with single application rates of 0.1 lb a.i./A and
retreatment intervals from 7 to 30 days.  The assessment concluded that
the chemical is highly toxic to exposed aquatic organisms on an acute
basis, and to nontarget beneficial insects.  Also, it was found that the
use patterns prescribed for bifenthrin have the potential for chronic
exposure and harm to fish and aquatic invertebrates, including those
living in or near the benthos, since bifenthrin is accumulated in the
sediment.  Risk quotients (RQs) exceeded the levels of concern (LOCs),
including endangered species, for a large number of the representative
species and scenarios.  The Agency concluded that the risk to birds and
mammals is minimal due to low toxicity.  Finally, in the review, it was
concluded at the time, that risk to terrestrial plants is unknown due to
a lack of data, but that it would also be considered minimal (based on
bifenthrin’s mode of action).  Based on the environmental fate
properties for bifenthrin it appeared to be immobile, very persistent in
the laboratory and field studies, stable to hydrolysis and photolysis,
very lipophilic and bioaccumulative.  The environmental fate database
was considered adequate for a Tier 1 risk assessment. 

The following studies have been submitted to the Agency and are in
review:

850.1735: Acute Sediment (Freshwater); test organism: Chironomus dilutus
(formerly known as Chironomus tentans); duration: 10 days, endpoint is
survival (MRID 46591502).

850.1740: Acute Sediment (Estuarine/Marine); Amphipods: Leptocheirus
plumulosus; 10-28 day duration; spiked sediment; endpoint: LC50, EC50,
NOAEC, LOAEC (MRID 46591501)

The following studies were requested in the same (2007) review:

Estuarine/marine fish life-cycle test (Guideline 72-5) using the TGAI of
bifenthrin.  The preferred test species is the Sheepshead minnow
(Cyprinodon variegatus).

Estuarine/marine aquatic invertebrate life-cycle test (Guideline 72-4)
using the TGAI of bifenthrin.  The preferred test species is the mysid
(Americamysis bahia).  

Furthermore, data on toxicity to plants is lacking.  In the 2007 review,
it was stated that: 

“Risk to terrestrial plants was not evaluated because toxicity data on
these receptors were not available.  However, information on bifenthrin
and from other pyrethroids suggests there are no direct toxic concerns
to plants from exposure to this family of compounds.”

In 2006, an incremental risk assessment was issued for the use of the
chemical on leafy brassica greens, peas and beans (dry), tobacco,
cilantro, okra and tuberous and corm vegetables (Group 1C) (D310879;
Rexrode and Meléndez, 2006).  The assessment was also based on
previously issued assessments for the chemical; similar conclusions were
made.

In 2005, the EFED issued the assessment for the use of bifenthrin for
wood preservation (D290992; Meléndez and Federoff, 2005).  For this
use, risks towards birds, mammals and plants were expected to be small
(precluded), due to lack of exposure; however, aquatic organisms were
presumed to be potentially exposed, since bifenthrin could leach into
the soil and reach adjacent bodies of water.  Railroad (crossroad) ties
were used as a representative scenario.  It was assumed that 100% of the
applied bifenthrin leached at once from the crossties.  However,
bifenthrin is immobile, hydrophobic, and has an extremely low solubility
in water; it appears that it would be tightly bound to wood, and that
the assumption is conservative.  At the time, the registrant was
required to perform a Wood Preservative Leaching Study, following the
American Wood Preservers’ Association’s Standard Method of
Determining the Leachability of Wood Preservatives (E11-97) or
equivalent.  This study has been submitted to the Agency and is
currently in review.

1999 Scientific Advisory Panel

A Scientific Advisory Panel (SAP) in 1999 examined the sediment toxicity
and fate of synthetic pyrethroids.  In response to a question regarding
whether sediment toxicity data on one pyrethroid (cypermethrin) could be
used to predict sediment toxicity to all pyrethroids, the panel
generally supported the method of using data from a few pyrethroids to
extrapolate information on toxicity to other pyrethroids.  The panel
recommended testing cypermethrin, “bifenthrin (relatively non-toxic to
freshwater aquatic organisms, very insoluble in water, large
bioconcentration factor) and possibly tefluthrin (highly toxic to
freshwater aquatic organisms, stable in water, intermediate solubility
in water to cypermethrin and bifenthrin)”   ADDIN EN.CITE
<EndNote><Cite><Author>USEPA</Author><Year>1999</Year><RecNum>42</RecNum
><DisplayText>(USEPA,
1999)</DisplayText><record><rec-number>42</rec-number><foreign-keys><key
app="EN" db-id="s0xer2w2o0xwx3e0a0tx0sz3zradttw529er">42</key><key
app="ENWeb"
db-id="RcJqaQrtmCQAAFU55fA">401</key></foreign-keys><ref-type name="EPA
Document">51</ref-type><contributors><authors><author>USEPA,</author></a
uthors><secondary-authors><author>SAP Report No.
99-03A</author></secondary-authors></contributors><titles><title>FIFRA
Scientific Advisory Panel Meeting, February 23, 1999 held ad the Holiday
Inn Hotel, Arlington, Virginia.</title><secondary-title>March 25,
1999</secondary-title><tertiary-title>Office of Pesticide
Programs</tertiary-title></titles><keywords><keyword>Pyrethroid,
esfenvalerate</keyword></keywords><dates><year>1999</year><pub-dates><da
te>March 25, 1999</date></pub-dates></dates><label>Scientific Advisory
Panel</label><urls><related-urls><url>http://www.epa.gov/scipoly/sap/mee
tings/1999/022399_mtg.htm#materials</url></related-urls></urls><access-d
ate>June 26, 2009</access-date></record></Cite></EndNote> (USEPA, 1999)
. Although this recommendation was made in 1999, the new CFR Part 158
requirements include sediment toxicity tests and these studies are
considered particularly important for ecological risk assessment of all
synthetic pyrethroids, including bifenthrin. 

The SAP commented on the use of Kd or KOC to estimate concentrations of
synthetic pyrethroids in sediments, recommending that the Agency
reconsider KOC as a measure of the binding potential of synthetic
pyrethroids to sediment and soil because the use of Kd alone limits
extrapolation to experimental conditions while KOC “allows one to
estimate partitioning across a wide variety of soil/sediment types”
(USEPA, 1999).  The Panel expressed concern that standard methods used
to measure sorption may not be applicable to highly hydrophobic
compounds due to high solids to water ratio, consideration of the
character of the organic matter, presence of dissolved organic carbon,
use of non-representative soils and sediments as sorbents, and improper
methods used to measure organic carbon.

While the biota-sediment-accumulation-factor is a widely accepted method
of assessment of bioaccumulation in sediments, the Panel indicated that
the bioconcentration data for Daphnia and Hyalella should be sufficient
to predict bioconcentration of pyrethroids.  Finally, the Panel
indicated that use of a solid phase microextraction (SPME) method to
determine the dissolved concentration in water could be used to account
for sorption of pyrethroids to organic carbon and colloids present in
the water column in the measurement of bioconcentration factors.

In 2003 and in response to the comments from the SAP on pyrethroids, 
EFED requested the following studies on bifenthrin and three other
synthetic pyrethroids (memorandum dated 12/22/03, Rexrode & Meléndez,
2003): 850.1735: Acute Sediment (freshwater), conducted for 10 days with
Hyalella azteca and Chironomus dilutus, endpoint is survival;
EPA/600/R-99/064: Chronic Freshwater Sediment Testing conducted for 65
days on Chironomus dilutus, survival, growth rate and reproduction (#
eggs/ female, time to oviposition, proportion of females ovipositing, %
hatch); and EPA/600/R01/020: Chronic Estuarine/ Marine Sediment Testing
conducted for 28 days on Leptocheirus plumulosus (percentage of neonates
that survive as adults, growth rate, reproduction (#eggs/ female, etc.)
and behavior.

To date, the Agency has received two whole sediment toxicity tests for
bifenthrin: MRID 465915-02 (acute 10-d test with C. dilutus) and MRID
465915-01 (chronic 28-d test with L. plumulosus). These studies are
currently under review.  However, it is noted that the 28-d test with L.
plumulosus only included survival and growth endpoints (with no
reproduction data were provided).  Therefore, this test will not satisfy
the Agency’s chronic whole sediment toxicity test requirement for
estuarine/marine invertebrates due to the lack of data on reproduction. 

2009 Scientific Advisory Panel

The OPP presented a “Proposed Common Mechanism Grouping for the
Pyrethrins and Synthetic Pyrethroids to a FIFRA SAP in June 2009 in the
context of its human health risk assessment. The OPP proposed two
subgroups based on Type I or Type II effects related to sodium current
tails and neurobehavioral impact, with esfenvalerate and fenpropathrin
showing symptoms of both types.  The panel indicated that substances
with mixed characteristics could be included in both groups.   This
mechanism of action assessment was performed by HED/OPP and presented to
the SAP to determine if a cumulative assessment is required for the
synthetic pyrethroids for assessing human health risks. Bifenthrin is a
Type 1 synthetic pyrethroid; it is not cyano substituted in the alpha
position.  Information on the SAP is available in the docket (with
non-copyright material available at http://  HYPERLINK
"http://www.regulations.gov"  www.regulations.gov ) under
EPA-HQ-OPP-2008-0489.

The EFED does not currently conduct cumulative ecological risk
assessments for several reasons.  Specifically, the Division does not
currently have the methodology to conduct similar cumulative risk
assessments for all of the (non-human) biological entities for which
EFED has responsibility.  In addition to addressing the toxicological
aspects of the cumulative effects of multiple pyrethroids to multiple
biological entities, a cumulative ecological risk assessment would
likely require consideration of exposure at a watershed scale in order
to incorporate spatial and temporal variability in pyrethroid
applications into cumulative exposure assessment.  EFED does not have
the modeling tools developed for conducting this type of assessment. 
However, EFED will consider open literature, currently available models
and other lines-of-evidence (e.g., monitoring data), as available, to
address the potential for cumulative effects of pyrethroids in the risk
description of the ecological risk assessment for bifenthrin.  

Open Literature Information

There are multiple articles in the open literature that indicate concern
over bifenthrin and other pyrethroids’ toxicity towards benthic and
other non-target aquatic organisms.  Also, the articles illustrate
bifenthrin’s prevalence over the environment, including urban
environments.  Please, refer to Section 3.4 for further details.

Aquatic Life Criteria and Aquatic Life Benchmarks

The Clean Water Act requires the Agency to publish water quality
criteria that accurately reflect the latest scientific knowledge on the
kind and extent of all identifiable effects on health and welfare which
might be expected from the presence of pollutants in any body of water,
including ground water. While these recommended criteria do not, in
themselves, impose any requirements, states and authorized tribes can
use them to develop water quality standards.  An Aquatic Life Ambient
Water Quality Criteria document has not been published for bifenthrin
(refer to url:   HYPERLINK "http://www.epa.gov/waterscience/criteria/" 
http://www.epa.gov/waterscience/criteria/  ).  However, the Agency is
aware of other efforts to derive aquatic life criteria for bifenthrin
and will consider this work when characterizing risk in the forthcoming
environmental risk assessment (see:   HYPERLINK
"http://www.swrcb.ca.gov/rwqcb5/water_issues/tmdl/central_valley_project
s/central_valley_pesticides/criteria_method/" 
http://www.swrcb.ca.gov/rwqcb5/water_issues/tmdl/central_valley_projects
/central_valley_pesticides/criteria_method/  .

Based on toxicity values revised by the EPA, the OPP publishes aquatic
life benchmarks for freshwater species, based on the most sensitive
species from the most recent risk assessments.  For bifenthrin, aquatic
life benchmarks have been published (see url:   HYPERLINK
"http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm#ben
chmarks" 
http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm#benc
hmarks ).  The aquatic life benchmarks are as follows:

Table 2.1. OPP Aquatic Life Benchmarks (Freshwater) for Bifenthrin
(µg/L)

Chemical Name	Fish	Invertebrates	Plants*

	Acute	Chronic	Acute	Chronic	Acute

Bifenthrin	0.075	0.04	0.8	0.0013	- - *

*No aquatic life benchmarks are available for vascular or non-vascular
plants.

Impaired Water Bodies

Bifenthrin is not individually identified as a cause of impairment for
any water bodies listed as impaired under section 303(d) of the Clean
Water Act, based on information provided at   HYPERLINK
"http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d
?p_cause_group_id=885" 
http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?
p_cause_group_id=885 .  However, the pyrethroids as a group have been
identified as a cause for impairment for three water bodies in Central
Valley, CA: Del Puerto Creek, Ingram Creek Site (confluence with
Hospital Creek to Hwy 33 crossing) and second Ingram Creek Site
(confluence with San Joaquin River to confluence with Hospital Creek). 
At the present time, additional bodies of water are being evaluated to
be included into the list of impaired bodies of water; however, they
have not been finalized (see   HYPERLINK
"http://www.waterboards.ca.gov/water_issues/programs/tmdl/integrated2010
.shtml" 
http://www.waterboards.ca.gov/water_issues/programs/tmdl/integrated2010.
shtml  and   HYPERLINK
"http://www.swrcb.ca.gov/rwqcb5/water_issues/tmdl/impaired_waters_list/3
03d_list.shtml" 
http://www.swrcb.ca.gov/rwqcb5/water_issues/tmdl/impaired_waters_list/30
3d_list.shtml  ).  The 2010 proposed 303(d) list for California contains
approximately 10 additional streams due to pyrethroids in the sediments
and bifenthrin has been implicated as the greatest contributor to the
pyrethroid toxicity observed.  EFED will include relevant information on
303(d) listings in the final environmental risk assessment.

Nonetheless, no Total Maximum Daily Load (TMDL) criteria have been
developed specifically for bifenthrin, based on information provided at 
 HYPERLINK
"http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detai
l?p_pollutant_group_id=885&p_pollutant_group_name=PESTICIDES" 
http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail
?p_pollutant_group_id=885&p_pollutant_group_name=PESTICIDES .  More
information on impaired water bodies and TMDLs can be found at  
HYPERLINK "http://www.epa.gov/owow/tmdl/"  http://www.epa.gov/owow/tmdl/
.  The Agency invites submission of water quality data for this
pesticide.  To the extent possible, data should conform to the quality
standards in Appendix A of the OPP Standard Operating Procedure:
Inclusion of Impaired Water Body and Other Water Quality Data in OPP’s
Registration Review Risk Assessment and Management Process (see:
http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm),
in order to ensure they can be used quantitatively or qualitatively in
pesticide risk assessments.

3.	Stressor Source and Distribution

Bifenthrin (Table 3.1) is a synthetic pyrethroid insecticide and
acaricide.  Its structure has three rings, two phenyl rings attached to
each other, and a cyclopropyl ring.  It is a Type I synthetic pyrethroid
(it is not cyano-substituted in the alpha position).  The chemistry of
bifenthrin may be dictated by its ester moiety.  It would be expected to
hydrolyze as the pH increases; however, in the available hydrolysis
study, the chemical was stable at all three pHs (5, 7 and 9).  The
structure of the molecule has two chiral centers and a double bond that
could result in a total of 8 isomers.  Chemically, bifenthrin contains
the Z, cis-isomers (includes the 1R and 1S configurations)
[(Z)-(1R)-cis-acid and (Z)-(1S)-cis-acid] out of eight isomeric esters. 
Bifenthrin has a (Z)-2-chloro-3,3,3-trifluoropropene (or
2-trifluoromethyl-2-chloro-ethene) substitution in the cyclopropyl ring.

A summary of physicochemical properties of bifenthrin is included in
Table 3.1.

(2-methyl[1,1′-biphenyl]-3-yl)methyl
(1R,3R)-rel-3-[(1Z)-2-chloro-3,3,3-trifluoro-1-propenyl]-2,2-dimethylcyc
lopropanecarboxylate	Bifenthrin data sheet:   HYPERLINK
"http://www.alanwood.net/pesticides/bifenthrin.html" 
http://www.alanwood.net/pesticides/bifenthrin.html    accessed 12/4/09

IUPAC Chemical Name	2-methylbiphenyl-3-ylmethyl
(1RS,3RS)-3-[(Z)-2-chloro-3,3,3-trifluoroprop-1-enyl]-2,2-dimethylcyclop
ropanecarboxylate

or



Appearance	It is an off-white to pale tan waxy solid with a faint,
slightly sweet smell.	USEPA OPPTS. 1988. Fact Sheet No.177 Bifenthrin.*

CAS Reg. No.	82657-04-3	Laskowski, 2002

Molecular Weight	422.9	Laskowski, 2002

Melting Point	68-70.6ºC	USEPA OPPTS. 1988. Fact Sheet No.177
Bifenthrin.*

Solubility (20oC)	0.0000140 mg/L or  1.40x10-5 ppm or 0.0140 ppb

‘Not Soluble’ according to FAO solubility classification.	Laskowski,
2002

FAO, 2000

Vapor Pressure (25oC)	1.80 x 10-7 mmHg (by extrapolation)

‘Non-volatile under field conditions.’	Laskowski, 2002

USEPA, 2008

Henry’s Law Constant	7.2 x 10-3 atm-m3/mol (from vapor pressure and
water solubility)	Laskowski, 2002

Octanol-Water Partition Coefficient (20oC)

(log KOW and KOW)	6.4 and 3.00 x 106	Laskowski, 2002

Octanol-Air Partition Coefficient

 = 1.02 x 107 (7.01)

  = 3133 (unitless)

Volatile from a water surface.	Calculated

USEPA, 2008

OH Radical Reaction Half-life	0.361 days	EPISuite v.4.0 Estimate

Biomagnification Potential	Presumption: If log KOA > 5, log KOW >2 and
the rate of chemical transformation is low, the chemical may biomagnify
in terrestrial food chains.**

For bifenthrin, log KOA> 5, log KOW>2 and rate of transformation is slow
in the environment and appears to be relatively slow in fish, with slow
depuration; it appears that bifenthrin has a potential to biomagnify in
terrestrial food chains.	**Gobas et al. 2003 and Armitage & Gobas, 2007
support this presumption utilized here only as a broad reference to
determine the potential for biomagnification.

*As cited in the EXTOXNET database.

Bifenthrin has a high molecular weight of 422.9 g/mol.  With an
extremely small solubility (only 0.0140 ppb) and a high octanol/ water
partition coefficient (KOW = 3.00x106).  Based on it octanol/ water
partition coefficient, it appears that bifenthrin has the potential to
bioaccumulate/bioconcentrate.  With a vapor pressure of 1.80 x 10-7
mmHg, and due to its very small solubility (0.0140 ppb), its calculated
Henry’s Law Constant is moderately high (7.2 x 10-3 atm-m3/mol).  In
addition, its Cwater/Cair is 3133, which classifies it as “volatile
from a water surface” (USEPA 2008).  Bifenthrin has the potential to
volatilize from wet surfaces.  The potential to volatilize may be
attenuated by its tendency to bind to organic matter (e.g., soils,
sediments, or organic matter and particulate in natural water).

For bifenthrin, the log KOA range is 7.01 – 12.5 (calculated and
EPISuite v.4.0 estimate), the log KOW is 6.4 and the rate of
transformation is slow in the environment and appears to be relatively
slow in fish, with slow depuration; it appears that bifenthrin may have
a potential to biomagnify in terrestrial food chains, based on the
presumption made by Gobas et al. and Armitage & Gobas, in 2003 and 2007
articles, respectively.  Even though the EFED has not adopted an
official reference or guideline to distinguish chemicals that
biomagnify, Gobas et al. and Armitage & Gobas’ presumption was
utilized here as a general or broad reference to identify the potential
for biomagnification in terrestrial food chains.

3.1.	Mechanism of Action

 tc \l3 "2.  Mode of Action Bifenthrin is a neurotoxic insecticide
acting through direct contact and ingestion.  The insecticidal effect of
pyrethroids is characterized by a rapid “knock down,” or paralysis,
of insects.  All pyrethroids act as axonic poisons, affecting both the
peripheral and central nervous systems, and share similar modes of
action.  The primary biological effects of bifenthrin and other
pyrethroids on insects and vertebrates reflect an inhibition of the
correct firing of neurotransmitter deliver signals from one cell to
another via nerve membrane inhibition of the voltage-gated Ca2+ (calcium
ion) channels coupled with a stimulatory effect on the voltage-gated Na+
(sodium ion) channels. The pyrethroids (including bifenthrin) share
similar modes of action, and are considered axonic poisons that affect
both the peripheral and central nervous system.

It is now well established that severe neurological symptoms of
poisoning with pyrethroids in mammals and insects are the result of
modification of the Na+ channels activity (cellular pores through which
Na+ ions are permitted to enter the axon to cause excitation)
(Matsumura, 1985).  Advanced electrophysiological experiments using
voltage clamp and patch clamp, together with ligand-binding and ionic
flux experiments, have unveiled unique actions of pyrethroids of keeping
the Na+ channel in the open state for an extremely long period,
sometimes as long as several seconds. This modification of Na+ channel
properties leads to hyperactivity of the nervous system.  This action
leads to spontaneous depolarizations, augmented neurotransmitter
secretion rate and neuromuscular block, which ultimately results in
paralysis of the insect.

Pyrethroids have also been shown to suppress GABA and glutamate
receptor-channel complexes and voltage-activated Ca2+ channels, but the
toxicological significance of these actions is uncertain.  Relative to
physiological responses, researchers have designated two types of
pyrethroids, Type I (e.g., bifenthrin, resmethrin, permethrin) and Type
II (e.g., cypermethrin, deltamethrin, fenvalerate). Type I pyrethroids
action is mainly associated with compounds that cause nerve excitation
symptoms typified by the appearance of repetitive firing of axons in the
peripheral nervous system and a negatively correlated temperature
reversible knockdown property (Clark & Matsumura, 1987).

3.2.	Overview of Pesticide Usage

Bifenthrin has numerous uses.  A summary of agricultural use patterns
for bifenthrin, based on a set of labels, is shown in Table 3.2.

  SEQ CHAPTER \h \r 1 Table 3.2.  Summary of agricultural use
information for bifenthrin, based on the labels for Capture 2EC
Insecticide/ Miticide (EPA Reg. No. 279-3069), Brigade® WSB
Insecticide/ Miticide (EPA Reg. No. 279-3108), Brigade® 2EC
Insecticide/ Miticide (EPA Reg. No. 279-3313), Capture® LFR (EPA Reg.
No. 279-3302) and Capture 1.15G Insecticide/ Miticide (EPA Reg. No.
279-3244) (selected representative labels).

USE	SINGLE  APP. RATE   (lb a.i./A)	NUMBER OF APPS. AT MAX. RATE
SEASONAL APP. RATE (lb a.i./A)	INTERVAL BETWEEN APPS. (days)	APP. METHOD
INCORPO-RATION DEPTH (inches)	PHI

Cotton*

*Not for use in California	0.1	5	0.5	          3	Ground, aerial or ULV	0
14

Field corn (grain and silage), popcorn, field corn grown for seed, at
plant use	0.1	1	0.1	Do not apply to soil where there is > 30% cover of
crop residue remaining.	In furrow	5-7	30

Field corn (grain and silage), popcorn, field corn grown for seed-pre
emergence (PRE) or pre-plant incorporated (PPI)	0.062            

0.040	1	0.062             

0.040	N/A	PPI            

PRE	PPI= Pre-Plant Incorporated, no deeper than 3 in.

PRE= Pre-Emergence, not specified	N/A

Field corn (grain and silage), popcorn, field corn grown for seed,
foliar use	0.1	3	0.3 including at plant, PPI, PRE, and foliar	Not
specified	Ground or aerial, no ULV	0	30

Sweet corn, sweet corn grown for seed-at plant use	0.1	1	0.1	Do not
apply to soil where there is > 30% cover of crop residue remaining.	In
furrow; granules must be incorporated into the top 1”	0-1	N/A

Sweet corn (grain and silage), sweet corn grown for seed, foliar use 
0.1	2	0.2	Not specified	Ground or aerial, no ULV	0	1

Succulent peas and beans: Pea (Pisum spp.) dwarf pea, edible-pod pea,
English pea, garden pea, green pea, snow pea, sugar snap pea, Pigeon
pea, Bean (Phaseolus spp.) broadbean (succulent), lima bean (green),
runner bean, snap bean, wax bean, Bean (Vigna spp.) asparagus bean,
blackeyed pea, Chinese longbean, cowpea, mothpea, Southern pea, yardlong
pea, Jackbean Soybean (immature seed), Sword bean	At plant 0.08

Foliar     0.1	2	0.2 including at-plant plus foliar applications	Not
specified	Ground or aerial	0	3

Dried peas and beans: bean (Lupinus); bean (Phaseoulus) field, kidney,
lima, navy, pinto, tepary; bean (Vigna) adzuki, blackeyed, catjang,
cowpea, crowder pea, moth, mung, rice, southern, urd; broad bean (dry);
chickpea; guar; lablab bean; lentil; pea (Piscum), field pea; pigeon pea
At plant 0.1

Foliar     0.1	2	Do not apply more than 0.2 a.i. to peas, or 0.3 to
beans/ A/ season including at plant + foliar applications.	7	Ground or
aerial	0	14

Head and Stem Brassica Vegetables including: broccoli, Chinese broccoli,
Brussels sprouts, cauliflower, cavalo broccolo, kohlrabi, cabbage,
Chinese cabbage (napa), Chinese mustard cabbage (gai choy)	At plant 0.1

Foliar     0.1	5	0.5	7	Ground or aerial	0	7

Canola, Crambe, Rapeseed	0.04	2	0.08	14	Ground or aerial	0	35

Cucurbits: chayote, citron melon, cucumber, gherkin, edible ghourd
(various), muskmelon (various, for example cantaloupe and pineapple
melon), pumpkin, summer squash (various), winter squash (various),
watermelon (includes hybrids)	At plant 0.1

Foliar     0.1	3	0.3	7	Ground or aerial	0	3

Lettuce, head	At plant 0.1

Foliar     0.1	5	0.5	7	Ground or aerial	0	7

Caneberries including blackberries, bingleberrie dewberries lowberries
marion-berries olallie-berries young-berries loganberrie raspberries	0.1
2	0.2	One pre-bloom and one post-bloom	Ground or aerial	0	3

Artichoke	0.1	5	0.5	15	Ground or aerial	0	5

Hops*

*Not for use in California	0.1	3	0.3	21	Ground or aerial, no ULV	0	14

Pears	0.2	2-3	0.5	30	Ground or aerial	0	14

Eggplant	At plant 0.1

Foliar     0.1	2	0.2	7	Ground or aerial	0	7

Citrus*

*Not for use in California	0.25

0.5	2

1	0.5

0.5	Early and late season

N/A	Ground the product should not contact fruit or foliage

Ground	0

0	1

1

Spinach	At plant 0.1

Foliar     0.1	4	0.4	7	At plant, ground or aerial	0	40

Grapes	0.1	1	0.1	N/A	Ground or aerial	0	30

Leafy Brassica Greens: broccoli raab, bok choy, collards, kale, mizuna,
mustard greens, mustard spinach, rape greens	At plant 0.1

Foliar     0.1	4	0.4	7	Ground or aerial	0	7

Tuberous and corm vegetables: potato, sweet potato, arracacha,
arrowroot, Chinese artichoke, Jerusalem artichoke, edible canna,
cassava, chufa, dasheen, ginger, leren, tanier, turmer, yam bean, true
yam	0.3           at plant;   0.15       lay-by;       0.1     foliar
nmt 2 foliar applications	0.5 including soil applications	21 for foliar
applications	In furrow, lay-by  and foliar treatments by ground or
aerial	0	21

Cilantro, Coriander	At plant 0.1

Foliar     0.1	5	0.5	7	Ground or aerial	0	3

Okra	At plant 0.1

Foliar     0.1	2	0.2	7	Ground or aerial	0	7

Strawberries	0.2	2-3	0.5	7	Ground or aerial	0	0

Tobacco	0.1            pre-transplant;  0.1 at transplant;0.1     foliar
2	0.2	Not specified; do not make more than 2 foliar applications per
season	Pre-transplant soil application, at transplant water treatment
application, and foliar application	4 for pre-transplant soil
applications; 0 for foliar applications	Do not apply later than lay-by

Tree nut crop: almond, beech nut, Brazil nut, Butternut, cashew,
chestnut, chinquapin, filbert (hazelnut), hickory nut, macadamia nut
(bush nut), pistachio, walnut (black and English)	0.2	2-3	0.5	15	Ground
or aerial	0	7

(21 for pecans)

Root Crops: burdock, carrots, celeriac, turnip rooted chervil, chicory,
ginseng, horseradish, turnip rooted parsley, parsnip, radish, oriental
radish, rutabaga, salsify, black salsify, Spanish salsify, skirret,
turnip	0.1	5	0.5	7	Foliar	0	21

Root Crops: Garden Beets	0.1	4	0.4	7	Foliar	0	1

Soybeans	0.1	3	0.3	30	Foliar	0	18

Fruiting Vegetables: Eggplant, pepper (bell and non-bell), groundcherry
pepino	At plant 0.1

Foliar     0.1	2	0.2	7	Ground or aerial	0	7

Fruiting Vegetables:    tomato, tomatillo	At plant 0.1

Foliar     0.08	4	0.32	10	Ground	0	1

Peanut	0.1	5	0.5	14	Foliar	0	14

Mayhaw	0.1	2	0.2	7	Foliar	0	30

Leafy Petiole Vegetables: celery, cardoon, Chinese celery, celtuce,
Florence fennel, rhubarb, Swiss chard	0.1	5	0.5	7	Ground or aerial	0	7

Bushberries: highbush and lowbush blueberries, currant, elderberry,
gooseberry, huckleberry	0.1	5	0.5	7	Ground or aerial	0	1



Capture 2EC Insecticide/Miticide is an emulsifiable concentrate
Brigade® WSB Insecticide/ Miticide consists of water soluble bags,
Brigade® 2EC Insecticide/ Miticide is an emulsifiable concentrate,
Capture® LFR is a suspension concentrate formulation and Capture 1.15G
Insecticide/ Miticide is a formulation of granules.  These labels
illustrate the variety of formulations available for bifenthrin.  The
chemical may be applied by ground, air or ULV methods, pre-transplant
soil application, at transplant water treatment application, and foliar
application.  There is also a granular formulation for use on corn at
plant (granules are incorporated into the top one inch of the soil) or
foliar (as granules).  The EFED acknowledges that the different
formulations for bifenthrin may result in different exposure results,
and the various restrictions in the labels designed to mitigate exposure
to non-target organisms.  The purpose of the Table 3-2 of this document
is to present the highest exposure scenario, which is typically utilized
in Tier 1 environmental risk assessments.

	

The labels for bifenthrin require a buffer zone of 10 ft around certain
bodies of water, such as lakes, reservoirs, rivers, permanent streams,
marshes or natural ponds, estuaries and commercial fish farm ponds, so
as to allow growth of a maintained vegetative filter strip.  The
agricultural products should not be applied by ground equipment within a
distance of 25 ft, or by aerial equipment within a distance of 150 ft,
or by ULV within a distance of 450 ft from freshwater or estuarine/
marine bodies of water (e.g. lakes, reservoirs, rivers, permanent
streams, marshes or natural ponds, estuaries and commercial fish farm
ponds).

The Label Use Information System (LUIS report) & Usage/Label Use Reports
for Bifenthrin (provided by BEAD) was based on a partial listing of
labels, due to the large number of labels available for review; use data
is not based on an exhaustive review of the entire population of labels.
 Section 3 labels or major producers’ labels, along with all State and
Local Needs (SLNs) labels, are included in the LUIS report. These data
represent the major uses of this chemical.  This method to extract the
labels is intended to provide information about the maximum use rates
and the use patterns for bifenthrin.

 and corn, the average and maximum percent crop treated are relatively
low (≤5%), while for sweet corn these percentages may reach moderately
high values (30-50%).  For cantaloupes, honeydew and raspberries, the
maximum percent crop treated is ≥ 65%.  For honeydew and raspberries,
the average crop treated is 70%.

Table 3.3.  Updated Screening-Level Estimates of Agricultural Uses of
Bifenthrin (SLUA, dated 10/28/10).

Crop	Lbs. A.I.	Percent Crop Ttd.



Average	Maximum

Alfalfa	1,000	<1	<2.5

Almonds	6,000	10	15

Apples	<500	<1	<2.5

Artichokes	<500	10	30

Beans, Green	6,000	30	50

Blackberries	<500	15	20

Broccoli	<500	<1	<2.5

Brussels Sprouts *	<500	N/C	N/C

Cabbage	2,000	15	35

Caneberries	1,000	35	45

Canola/Rapeseed	2,000	5	10

Cantaloupes	3,000	30	65

Carrots	1,000	5	10

Cauliflower	<500	5	10

Celery	<500	<1	<2.5

Chicory *	<500	N/C	N/C

Corn	100,000	<2.5	5

Cotton	20,000	<2.5	5

Cucumbers	1,000	5	20

Dry Beans/Peas	<500	<1	<2.5

Grapes	1,000	<2.5	5

Hazelnuts (Filberts)	<500	5	5

Honeydew	3,000	70	80

Lettuce	1,000	5	10

Onions  +	<500	<1	<2.5

Peanuts	<500	<1	<2.5

Pears	<500	<1	<2.5

Peas, Green	1,000	5	25

Pecans	1,000	<2.5	<2.5

Peppers	1,000	10	20

Pistachios	5,000	30	30

Potatoes	1,000	<1	<2.5

Pumpkins	1,000	20	40

Raspberries	1,000	70	75

Sorghum	<500	<1	<2.5

Soybeans	10,000	<1	<2.5

Squash	1,000	10	25

Strawberries	3,000	25	55

Sunflowers +	<500	<1	<2.5

Sweet Corn	10,000	30	50

Tobacco	<500	<1	<2.5

Tomatoes	2,000	5	30

Walnuts	5,000	15	25

Watermelons	1,000	5	15

Wheat (Section 18 Use) +	2,000	<1	<2.5

All numbers are rounded.  '<500' indicates less than 500 pounds of
active ingredient.  '<2.5' indicates less than 2.5 percent of crop is
treated.  '<1' indicates less than 1 percent of crop is treated. 
‘N/C’ is indicates only lb. A.I. available.  ‘*’ is CA data only
(95% or more of U.S. acres in California).  ‘+’ is crops not known
to be listed on active end use product registrations or as Section 18
emergency exemptions when the report was run.  The sources of the SLUA
include the USDA-NASS, Private Pesticide Market Research and California
Department of Pesticide Regulation (CDPR) data.  The information
reflects amalgamated data developed by the Agency and are in a
releasable format.



The U.S. Geological Survey (USGS) pesticide agricultural use maps (Fig.
3.1) show regional scale patterns in use intensity within the United
States. The USGS pesticide maps are based on State level estimates of
pesticide use rates for individual crops, which have been compiled by
the National Center for Food and Agricultural Policy (NCFAP) for 1999
through 2004, and on the 2002 Census of Agriculture for county crop
acreage crop.

According to the map, the major agricultural uses for bifenthrin are
corn and cotton with 69.5 and 12.5% of the use, respectively.  Other
uses with >1% of the use included green beans, sweet corn and
strawberries.  Minor uses, with reported percent of the use between 0.5
and 1% are raspberries, canola, pumpkins, cantaloupe and squash.  As
expected, there is a general agreement between the SLUA and the USGS
map.  The map shows a generalized use of bifenthrin for agricultural
purposes throughout the country, with highest uses in the cornbelt and
the cotton belt.  Multiple agricultural uses are approved for the
chemical, other than the ones in the map, as indicated above in the
Table 3.2. 

Fig. 3.1. Estimated Use of Bifenthrin in 2002

Note of Caution:  The pesticide use maps available (  HYPERLINK
"http://water.usgs.gov/nawqa/pnsp/usage/maps/compound_listing.php?year=0
2" 
http://water.usgs.gov/nawqa/pnsp/usage/maps/compound_listing.php?year=02
 ) show the average annual pesticide use intensity expressed as average
weight (in pounds) of a pesticide applied to each square mile of
agricultural land in a county. The area of each map is based on
state-level estimates of pesticide use rates for individual crops that
were compiled by the CropLife Foundation, Crop Protection Research
Institute during based on information collected during 1999 through 2004
and on 2002 Census of Agriculture county crop acreage. The maps do not
represent a specific year, but rather show typical use patterns over the
five year period 1999 through 2004. Use intensity rates are expressed as
the pounds applied per square mile of mapped agricultural land in a
county. The area of mapped agricultural land for each county was
obtained from an enhanced version of the 1992 USGS National Land Cover
Data (NLCD). The key limitations of the data used to produce these maps
include the following: (1) state use coefficients represent an average
for the entire state and consequently do not reflect the local
variability of pesticide management practices found within states and
counties, (2) pesticide use estimates are not for a specific year, but
represent typical use patterns for the five year period, (3) state
pesticide use coefficients may not have been available for all states
where a pesticide may have been applied to agricultural land, and
therefore, are not displayed on the maps, (4) the county crop acreage is
based on the 2002 Census of Agriculture and may not represent all crop
acreage because of Census nondisclosure rules, and (5) agricultural land
area used to calculate the pesticide use intensity and display the data
was derived from 30-meter satellite remote sensing data that may over
estimate or underestimate the actual agricultural land area. The maps
are not intended for making local-scale estimates of pesticide use, such
as estimates at the county level. Please refer to   HYPERLINK
"http://water.usgs.gov/nawqa/pnsp/pubs/ofr00250/"  Method for Estimating
Pesticide Use  for a detailed discussion of how the pesticide use data
were developed.



In addition to the classical agricultural use sites, bifenthrin has
multiple other uses.  These uses include food/feed use sites and
non-food/ non-feed use sites.  Bifenthrin may be used in multiple urban
environments.  The extent of these uses, compared to agricultural uses
is uncertain, but it appears that the chemical is used widespread over
urban environments.  Many of these uses are classified as outdoor
residential such as ornamental lawns and turf, recreation area lawns,
ornamental and/ or shade trees, ornamental herbaceous and non flowering
plants, ornamental woody shrubs and vines, paths/patios, paved areas
(private roads/sidewalks), pet living/ sleeping quarters, and
residential lawns.  Table 3.4 provides a summary of the terrestrial
nonagricultural use sites for bifenthrin.  Application methods vary. 
Many of these uses could involve substantive exposure to wildlife,
specifically, aquatic organisms, and they will be assessed accordingly
(e.g., commercial/ industrial lawns, residential turf/ lawn, golf course
turf, rights of way/ fencerow/ hedgerow, ornamentals/ lawns and turf,
recreation area lawns and residential lawns).  Another use that will be
re-evaluated is wood protection treatment (outdoors).

Table 3.4. Uses Classified as Terrestrial Nonagricultural for Bifenthrin

Use	Max. App. Rate/ units	Max. No. Apps./ Year	Max. App. Rate per Year
Min. App. Int./ days

Agricultural farm premises	0.0052 lb/1000 sq ft	NS	NS	NS

Agricultural/ farm structures/ buildings and equipment	0.05 lb/1000 sq
ft

0.01 lb/mound	NS	NS	NS

Airports/ landing fields	0.2 lb/A

0.1 lb/mound

0.0051 lb/1000 sq ft	NS	NS, 0.2 lb/A	NS

Animal kennels/ sleeping quarters (commercial)	0.0052 lb/1000 sq ft	NS
NS	NS

Automobiles – taxis – limousines – recreational vehicles & tires
0.0512 lb/1000 sq ft	NS	NS	NS

Barns/ barnyards/ auction barns	0.2 lb/A

0.0517 lb/1000 sq ft

0.01 lb/mound	NS	NS, 0.2 lb	NS

Christmas tree plantations	0.1 lb/A

5.55E-4 lb/cu ft	NS, 3	NS, 0.3 lb/A	NS

Commercial storages/ warehouses premises	0.0052 lb/1000 sq ft	NS	NS	NS

Commercial/ industrial lawns	0.4 lb/A

0.0516 lb/1000 sq ft

0.0104 lb/mound	NS	NS, 0.4 lb/A	NS

Commercial/ institutional/ industrial premises/ equipment (outdoor)
0.0103 lb/mound

0.0516 lb/1000 sq ft

5.2E-4 lb/sq ft	NS	NS, 0.4 lb/A, 0.2 lb/A	NS

Conifers (seed orchards)	0.2 lb/A

5.62E-6 lb/1000 sq ft	NS, 6	NS, 0.6 lb/A	NS

Deciduous fruit trees (unspecified)	0.228 lb/A, 0.4679 lb/A

0.0686 lb/cu yd	NS	NS, 0.2 lb/A	NS

Gulf course turf	0.16, 0.2 or 0.4 lb/A

0.0092 lb/1000 sq ft

0.0017 lb/mound	NS	NS, 0.2 or 0.4 lb/A	NS

Greenhouse (empty or in use)	0.05, 0.1 or 0.2 lb/A

0.0046 lb/1000 sq ft	NS	0.2 lb/A	NS

Industrial areas (outdoor)	0.1, 0.16 or 0.2 lb/A

0.0092 lb/1000 sq ft

0.0104 lb/mound	NS	NS, 0.2 or 0.4 lb/A	NS

Non-agricultural outdoor buildings/ structures	0.05 lb/1000 sq ft

0.002 lb/sq ft

0.01 lb/mound

0.05, 0.1 or 0.2 lb/A

0.0052 lb/nest	NS	NS, 0.2 lb/A	NS

Non-agricultural rights-of way/ fencerows/ hedgerows	0.0519 lb/1000 sq
ft

0.0104 lb/mound

0.2 lb/A

0.0052 lb/nest	NS	NS, 0.2 lb/A	NS

Non-agricultural uncultivated areas/ soils	0.05 lb/1000 sq ft

0.0103 lb/mound

5.19E-4 lb/sq ft	NS	NS, 0.4 lb/A	NS

Ornamental and/ or shade trees	0.16, 0.2 or 0.4 lb/A

0.05 lb/1000 sq ft

0.02 lb/tree	NS	NS, 0.2 or 0.4 lb/A	NS

Ornamental ground cover	0.0052 lb/1000 sq ft	NS	NS	NS

Ornamental herbaceous plants	0.16, 0.2 or 0.4 lb/A

0.0107 lb/1000 sq ft	NS	NS, 0.2 or 0.4 lb/A	NS

Ornamental lawns and turf	0.1, 0.16, 0.2 or 0.4 lb/A

0.0516 lb/1000 sq ft

0.0104 lb/mound	NS	NS, 0.2 or 0.4 lb/A	NS

Ornamental non-flowering plants	0.16 or 0.2 lb/A

0.0516 lb/1000 sq ft

0.0052 lb/nest	NS	NS, 0.2 or 0.4 lb/A	NS

Ornamental sod farms (turf)	0.1, 0.2 or 0.4 lb/A

0.0092 lb/1000 sq ft

0.0017 lb/mound	NS	NS, 0.2 or 0.4 lb/A	NS

Ornamental woody shrubs and vines	0.2 or 0.4 lb/A

0.0519 lb/1000 sq ft

0.0052 lb/nest

0.0104 lb/mound	NS	NS, 0.2 or 0.4 lb/A	NS

Paths/ patios	0.2 lb/A (for outdoor residential use)

0.05 lb/1000 sq ft

0.0103 lb/mound	NS	NS, 0.2 lb/A	NS

Paved areas (private roads/ sidewalks)	0.4 lb/A

0.05 lb/1000 sq ft

0.0104 lb/mound	NS	NS, 0.4 lb/A	NS

Pet living/ sleeping quarters	0.0046 lb/1000 sq ft	NS	0.4 lb	NS

Recreation area lawns	0.1, 0.16, 0.2 or 0.4 lb/A

0.05 lb/1000 sq ft

0.0104 lb/mound	NS	NS, 0.2 or 0.4 lb/A	NS

Recreational areas	0.1, 0.2 lb/A

0.05 lb/1000 sq ft

5.19E-4 lb/sq ft

0.017 lb/mound	NS	NS, 0.2 or 0.4 lb/A	NS

Refuse/ solid waste sites (outdoor)	0.01 lb/mound

0.05 lb/1000 sq ft	NS	NS	NS

Residential lawns	0.05, 0.1 or 0.2 lb/A

0.05 lb/1000 sq ft

0.0103 lb/mound	NS	NS, 0.2 or 0.4 lb/A	NS

Wide area/ general outdoor treatment (public health use)	0.0052 lb/1000
sq ft	NS	NS	NS

Wood protection treatment (outdoors)	0.5978 lb/1000 sq ft

6.44E-4 lb/sq ft	NS	NS	NS

NS = Not Specified; AN = As Needed.  Data obtained from LUIS Report.



The Agency’s available non-agricultural bifenthrin national usage data
show about 100,000 lb for consumer-fertilizer combination use.  The
national usage on golf courses in 2002 was 20,000 lb. and the use on
institutional turf varied (<500 lb in 1999, 7,000 lb in 2004, and 2,000
lb in 2006).  Bifenthrin's use for landscaping was also variable (2,000
lb in 1999, <500 lb in 2002, 5,000 lb in 2004, and 6,000 lb in 2006). 
Lawn Care Operators' (LCOs) use of bifenthrin peaked in 2006 (63,000
lb), and the usage in nursery/greenhouse was 50,000 lb in 2002.  About
131,000 lb are used by pest control operators (PCOs) in 2000, and
127,000 lb in 2003.  Use on turf farms are 3,000 lb in 2004, and <1,000
lb in 2006 (Kline, Inc.).

Data from the California Department of Pesticide Regulation (CDPR)
provided by stakeholders, indicate that about half of bifenthrin use is
in urban areas.  The submitters provided usage information from
CDPR-PUR.  Based upon the submitted information, around 80% of the
bifenthrin used in urban areas in California is by professional
applicators (2007-2008) and most of the bifenthrin applied is for
structural pest control (2004-2008 data).  

The Agency has limited use and usage information relevant to urban
exposures and residential uses of pyrethroids, including bifenthrin. 
The Agency intends to use available non-agricultural use and usage data,
such as the Kline database, the California Department of Pesticide
Regulation’s (CDPR) Pesticide Use Reporting Data and Pest Control
Operator’s usage survey, and the Residential Joint Venture Task Force
homeowner survey data (2003), to make certain reasonable assumptions
regarding various applications and information related to
urban/residential use.  Due to the limited data available, exposure to
the environment and uncertainties will be characterized.  Detailed
information on non-agricultural use and usage of pyrethroid products,
specifically bifenthrin, would be useful in order to reduce those
uncertainties for the final environmental risk assessment for
bifenthrin.

Furthermore, there are several other indoor non-food or indoor
residential use sites like for example, automobiles, taxis, limousines,
recreational vehicles, tires, commercial storage/ warehouses premises,
commercial transportation facilities (non-food/non-feed),
commercial/institutional/industrial premises/equipment (indoor),
dairies/cheese processing plant premises (non-food contact), dairy farm
milk handling facilities/ equipment, dairy farm milk handling
facilities/equipment, dairy/cheese processing plant premises (non-food
contact), dairy farm milk storage rooms/houses/ sheds, eating
establishments, egg packing plants (commercial), feed mills/feed
processing plants, feed/ food treatment storage/processing/handling
equipment, food processing plants (non-food handling areas), food
processing plant premises, food stores/markets/supermarkets premises,
hospitals/medical institution premises (human/veterinary),
household/domestic dwellings (indoors), meat processing plant premises
(non-food contact), poultry processing plant premises (non-food
contact), poultry litter, refuse/solid waste sites (indoor), ships and
boats, storage areas (full or empty), and wood protection treatment
(indoor).  

For the indoor uses, the Division has conducted environmental risk
assessments for a few chemicals for Re-registration Eligibility
Decisions (e.g., permethrin, resmethrin and pyrethrins).  In a study
(Weston and Lydy 2010), several synthetic pyrethroids were observed in
effluents after secondary treatment from POTWs in the Sacramento-San
Joaquin Delta.  In the study, bifenthrin was the most frequently
detected pyrethroid.  It was found in 39% of the municipal wastewater
treatment plant effluents (POTWs) tested in the Sacramento-San Joaquin
Delta, at a maximum concentration of 6.3 ng/L, and it exceeded the
Hyalella azteca EC50 of 3.3 ng/L in 22% of the samples.  There is the
potential for synthetic pyrethroids to reach surface waters via exposure
from contaminated drains, and even after treatment in plants.  Thus,
EFED will evaluate the potential for exposure to aquatic organisms from
various of the indoor uses of bifenthrin.  Finally, bifenthrin also has
aquatic non-food industrial uses in drainage systems, and greenhouse
uses on for example forest trees (softwood – conifers).

According to the agricultural labels for bifenthrin (e.g., for Capture
and Brigade products, EPA Reg. Nos. 279-3069 and 279-3313),
product…“may be applied in tank mixtures with other products
approved for use on registered crops… Test for compatibility of
products before mixing.”  Toxicity data on environmental mixtures of
bifenthrin with other pesticides may be presented, if available, as part
of the ecological risk assessment.  It is expected that the toxic effect
of bifenthrin, in combination with other pesticides used in the
environment, is likely to be a function of many factors including but
not necessarily limited to: (1) the exposed species, (2) the
co-contaminants in the mixture, (3) the ratio of bifenthrin and
co-contaminant concentrations, (4) differences in the pattern and
duration of exposure among contaminants, and (5) the differential
effects of other physical/chemical characteristics of the receiving
waters (e.g. organic matter present in sediment and suspended water). 
Quantitatively predicting the combined effects of all these variables on
mixture toxicity to any given taxa with confidence is beyond the
capabilities of the available data and methodologies.  However, a
qualitative discussion of implications of the available pesticide
mixture effects data regarding the confidence of risk assessment
conclusions will be addressed as part of the uncertainty analysis.  EFED
will consider open literature, currently available models and other
lines-of-evidence (e.g., monitoring data), as available to address the
potential for cumulative effects of pyrethroids in the risk description
of the ecological assessment for bifenthrin.

Piperonyl butoxide (PBO) and MGK-264 are commonly used in formulations
with pyrethroids.  PBO acts as a potentiator in both mammals and insects
because the pyrethroid is not metabolized and excreted as quickly in its
presence (Barile 2004; Hodgson & Smart 2001).  Exposure to pyrethroids
along with PBO increases the toxicity of the pyrethroids (Amweg & Weston
2007; Weston & Lydy 2010).  MGK-264, another potentiator/synergist used
with pyrethroids, has similar effects as those observed for piperonyl
butoxide (Hodgson & Smart 2001).

The Agency routinely assesses potential exposure to formulations by
examining acute exposure to spray drift.  Acute toxicity data on the
formulation is compared to potential exposure to spray drift.  The sole
active bifenthrin registration that contains MGK-264 is for indoor use
for spot treatments and crack and crevice only (Reg. No. 68543-38).  The
spray drift associated with this use will be minimal.  Therefore, a
quantitative assessment of the potential aquatic exposure to the
formulation containing MGK-264 is not necessary; thus, data on typical
end use product are not required.  

There are no registered co-formulated products containing bifenthrin and
PBO.  However, according to registered labels for piperonyl butoxide
(PBO) products, the Agency is aware that bifenthrin may be co-applied
with PBO, a synergist, which may increase its toxicity substantially to
target and non-target organisms.  Currently, data on the extent to which
the toxicity of a pyrethroid active ingredient is enhanced by varying
concentrations of PBO are needed to address the ecological risk of
products when co-applied with PBO. At this time, the Agency is
evaluating the types of synergist data that will be needed across the
spectrum of co-applied pyrethroid/synergist products and the most
appropriate mechanisms for requiring such data. The need for synergist
data is discussed in the EFED Registration Review Problem Formulation
for Piperonyl Butoxide, dated December 13, 2010 (USEPA, 2010, D378420). 
The PBO Problem Formulation is available in the PBO registration review
docket at   HYPERLINK "http://www.regulations.gov"  www.regulations.gov 
(EPA-HQ-OPP-2010-0498).

Available literature data also suggest the potential for synergism in
the environment (e.g., Amweg et al. 2006, Weston et al. 2006). Piperonyl
butoxide and/or MGK-264 from other pyrethroid applications (e.g. the
application of an adulticide containing PBO), could interact with
bifenthrin.  Potential interactions will be described in the risk
assessment.

3.3.	Environmental Fate and Transport

A summary of environmental fate/ transport properties of bifenthrin is
included in Table 3.5.

  SEQ CHAPTER \h \r 1 Table 3.5.  Summary of environmental fate and
transport properties of bifenthrin.

PARAMETER	VALUE(S) (units)	SOURCE	COMMENT

  Hydrolysis Half-life 

  [pH 5, 7, 9; (25 oC)]	Stable at all three pHs and in unbuffered (pH
7.5) solution.	MRID: 00132539.	Study was performed in the presence of
~7% acetonitrile and at above the solubility limit. There is evidence of
precipitation.  A new study is being required.

  Aqueous Photolysis Half-life 	Relatively stable.

Natural sunlight was used.	MRID 00163084	Samples were not buffered,
contained ~30% acetonitrile as cosolvent, and study was at above the
solubility limit.  A new study is being required.

  Soil Photolysis Half-life	SiL soil t1/2  = 147 days and 98.5 days for
cyclopropyl and phenyl labels, respectively.

Corrected half-lives are 147 days and 106 days (no significant
degradation in dark control for cyclopropyl label).

trans-bifenthrin reached up to around 3.1% of the applied.	MRID 00163085
Natural sunlight in New Jersey, silt loam soil used.

  Aerobic Soil Metabolism Half-life	Soil	Cyclopropyl	Phenyl	Acc No:
073174, 073225, 141502, 251278, 251728, 254401, 254411, 264642, 532540;

MRID 00132540, 00141202, 00152266	There is a discrepancy in the rates of
reaction with both labels (phenyl label degraded faster in all
instances).  The studies were conducted separately.

	SL	132	115



	SiL	250	156



	SiClL	129	96.8



	14CO2 was 6-29% and non-extracted solids were 14-25% AR. 



  Anaerobic Soil Metabolism

  Half-life	Slow metabolism was observed after anaerobic conditions were
established.  75-79% of the recovered was bifenthrin at 61 days.	MRID
00163088	Samples were harvested only a few times.  Sampling performed
only at 0 (29 days after aerobic incubation), 31 and 61 days.  A new
study is being required.

  Aerobic Aquatic Metabolism

  Half-life	Not available	Not available	Gan et al. 2005 reports that the
aerobic aquatic half-lives in three sediments, at 20ºC, were in the
range of 428-483 days.  Data is required.

  Anaerobic Aquatic Metabolism

  Half-life	Not available	Not available	Gan et al. 2005 reports that the
anaerobic aquatic half-lives in three sediments, at 20ºC, were in the
range of 251-498 days.  Data is required.

  Adsorption/Desorption

  Batch Equilibrium

  Soil Partition Coefficient

  (Kd & KOC)	Adsorption:

Soil                   Kd               KOC

S                      992          131000

SL                   4192         239000

SiL                  5430         302000

ClL                  3690         275000

Desorption:

Soil                   Kd                 KOC

S                      3342         440000

SL                 11044          635000

SiL                11610          645000

ClL                10254          765000

In TLC studies, the Rf values reported for bifenthrin were as follows: 
Leon fine sand - 0.3

Cosad sandy loam (low %OM) - 0.03

Dunkirk silt loam - 0.08

Hagerstown clay loam - 0.07

The data indicates that bifenthrin is immobile in non-sandy soils.	Acc.
No. 251728

MRID 132541

	Provides minimal supplemental information, study does not fill
guideline requirements.

Study 00163089 is a mobility study of aged soil using TLC methodology. 
It was only screened to check if it provided suitable mobility
information.

  Laboratory Volatility	The mean volatility for day 14 was 5.07x10-5
µg/cm2-hr at 25ºC and 1.48x10-4 µg/cm2-hr at 40ºC. The maximum
recovered volatiles were 1.1% at 25ºC and 5.1% of the recovered at
40ºC.	MRID 41220601	Days 1 to 5 volatilities varied widely and the
trapping efficiency was not reported.

  Leachability from Treated Wood	Studies are currently in review.	MRID
47454101, 47454102	Two available studies are in review.

  Terrestrial Field Dissipation	Site                                    
Half-lives

Champaign, IL                    192 days

Fresco, CA                          345

Madera, CA                         155

Imperial County, CA           228

Tifton, GA                           122

Marion, AR                           78

Fresno, CA                           193

Champaign, IL                     118

Champaign, IL                     126

Marion, AR                          121

San Joaquin, Fresno      DT50 35 days	Acc No 264642 or MRID 00163091;

MRIDs 42339203, 42339201, 42334167, 41673103, 41673101, 41671302	- -

 Aquatic Field Dissipation	Dallas County, Orville, Alabama:

Residues of bifenthrin were found in the sediment and water of the pond
during the 12 months period after application; in the sediment, there
was no clear discernable pattern of decay.  Residues in fish tissues
were orders of magnitude higher than the concentration in water.	MRID:
40981803, 40981805, 40981808, 40981812, 40981814, 40981815, 40981816,
40981817, 40981818, 40981819.	- -

  Bioaccumulation in Fish (BCF)	2110X in edible portion, 8720X in the
non-edible portion, and 6090X in whole fish exposed to a nominal
concentration of 0.0026 ppb.  Depuration was slow with 43-53% of the
residues still remaining in the fish tissue after 42 days of depuration.
 The parent comprised 66.8-70.2% of the total radiocarbon, and
4’-OH-bifenthrin was 3.2-3.6%; 21.4-23.4% was un-extractable. 
Residues contained around 39% trans-bifenthrin, which the registrant
argues that might be a photoproduct.	Acc. No. 264642 or MRID: 163094,
163095

	  Bioaccumulation in Aquatic Non-

  Target Organisms	The following was reported: BCFs were independent of
the application rates: Daphnia magna – 270-440x; Asellus (water
exposure) – 71-82x; Asellus (water and soil exposure) – 120-180x;
Pimephales promela – 45-63x; Corbicula (aqueous phase) – 41-74x;
Corbicula (soil phase) – 92-140x.	MRID 42529902	Study was screened.



Bifenthrin is a persistent pyrethroid in the environment, stable to
hydrolysis and slow to biodegrade.  This Type 1 pyrethroid that has a
(Z)-2-chloro-3,3,3-trifluoropropene (or
2-trifluoromethyl-2-chloroethene) group attached to the cyclopropane
moiety appears to be stable to sunlight, as opposed to other early Type
1 pyrethroids like allethrin or resmethrin.  The very low water
solubility and hydrophobic (lipophilic) nature of bifenthrin leads to
strong soil adsorption and a tendency to partition to sediment in
aquatic systems.  The high octanol/ water partition coefficient suggests
that bifenthrin will bioconcentrate in aquatic organisms.  This is
confirmed by the bioaccumulation in fish study, where the
bioconcentration factors (BCFs) ranged from 2110x for edible portion to
8720x for the non-edible portion.  Lower BCFs for bifenthrin in a
bioaccumulation in aquatic non-target organisms study (screened only)
may be a result of chemical metabolism (biotransformation) by organisms.
 Bifenthrin has a low vapor pressure and a moderate Henry’s law
constant.  Given the fact that bifenthrin adsorbs strongly to soil
particles and to organic matter, volatilization from water and soil
surfaces may be reduced.  The hydroxyl radical reaction half-life for
bifenthrin is 0.4 days (EPISuite v.4.0 estimate), which appears to
preclude the potential for long term transport.

Studies conducted on bifenthrin indicate that it is persistent under
most conditions and bioaccumulative.   It appears that a major route of
degradation is aerobic metabolism.  Bifenthrin is stable to hydrolysis
at all pH values.  It is relatively stable to aqueous and soil
photolysis and degrades slowly under both aerobic and anaerobic soil
metabolism conditions (half-life range 97-250 days in 3 aerobic soils
using two radiolabels; and, relatively stable in anaerobic soil). 
Bifenthrin is immobile in four soils tested (KOC > 100,000, FAO
classification).  Field studies show a pattern consistent with the
laboratory studies, with relatively high persistence (half-lives ranging
from 78 to 345 days in 10 field trials) and  low mobility of the
chemical in soil.  In aquatic environments, it appears that residues of
bifenthrin persist in pond water and sediment for extended periods (at
least 12 months of monitoring).  No major metabolites were observed
(>10% of the applied) in any of the laboratory studies.  Bifenthrin was
highly bioaccumulative in fish with relatively slow depuration.

Degradation and Metabolism

Bifenthrin, is stable to hydrolysis at a pH range of 5 to 9, as shown in
laboratory studies.  Bifenthrin, was also stable in unbuffered solutions
exposed to natural summer sunlight in New Jersey.  It did not appear to
degrade substantially for a period of 30 days on a silt loam soil
following irradiation with natural sunlight (New Jersey).  The reported
half-life of 14C-bifenthrin in three soils under aerobic conditions,
using two radiolabels, ranged from 96.8 to 250 days.  In an anaerobic
soil metabolism study, a sandy loam soil was flooded.  The rate of
degradation of bifenthrin was very slow when the anaerobic conditions
were established.  No individual degradation products accounted for more
than 10% of the applied in any of the above mentioned studies.  The
hydrolysis and aqueous photolysis studies were performed in the presence
of a high concentration of acetonitrile due to the very low solubility
of bifenthrin.  The Agency does not have aerobic and anaerobic aquatic
metabolism studies.  Gan et al. 2005 determined the aerobic and
anaerobic aquatic metabolism of bifenthrin to be >250 days (see
additional details in Section 3.4, below).

Soil Sorption and Mobility

Bifenthrin was immobile in four soils tested (KOC >100,000, FAO mobility
classification FAO 2000).  Using a sand, sandy loam, silty loam, and
silty clay loam, adsorption experiments resulted in KOC values of
131000, 239000, 302000, and 275000, respectively.  The desorption KOC
values were 439000, 634000, 645000, and 765000, respectively.  All these
values were obtained at a single concentration.  Freundlich correlation
coefficients could not be established for bifenthrin.  The solutions
contained 2% acetonitrile as a cosolvent.

 μg/cm2 hr (average at 14 days).  The maximum recovered volatiles were
1.1% at 25ºC (and 5.1% at 40ºC).  Although the vapor pressure is
marginally low, the Henry’s Law Constant suggests that there could be
exposure during irrigation events.  On the other hand, bifenthrin does
not seem to be persistent in air.  As indicated in Table 3.1, the
hydroxyl radical reaction half-life for bifenthrin is ~0.4 days
(EPISuite v.4.0 estimate).  Therefore, chronic atmospheric exposure, or
transport are precluded, and any concerns would likely be restricted to
acute exposures.  Bifenthrin’s potential for volatilization may be
reduced significantly because it adsorbs strongly to soils, suspended
solids, particulate, sediment, and organic matter in the water column.

The theoretical maximum concentration of bifenthrin in air, based on its
vapor pressure, is 4.1 μg/m3.  However, one air monitoring study for
bifenthrin, performed by the California Air Resources Board (CARB 2001),
is available.  The maximum air concentration from the CARB monitoring
results was only 0.270 μg/m3 (270 ng/m3), which was “observed at the
east sampling site, during the 1st sampling period (application) of 2.7
hours.”  For the ambient monitoring, "the highest bifenthrin
concentration, 17 ng/m3 (0.97 pptv), was observed at the Helm Elementary
School (HES) sampling site in Helm on July 15, 1999."

The Health Effects Division (HED) waived the rat inhalation data
requirement based on bifenthrin’s low vapor pressure (1.8x10-7 mmHg),
which is over 400 times below the threshold value of 7.5x10-5 mmHg
(inhalation waiver criteria 2, for low volatility).  There is no
quantitative mammalian or avian inhalation data.

Field Dissipation

Numerous terrestrial field dissipation studies are available in various
states and counties of the nation.  They show that bifenthrin degrades
in the field with half-lives ranging from 78 to 345 days.  These studies
appear to confirm the findings of the laboratory studies.  They use
different formulations and application rates.  A supplemental aquatic
field dissipation study employing a site in Alabama showed that
bifenthrin in aquatic environments (a pond) persists for extended
periods of time.  It was found throughout the 12 months of monitoring
after the last pesticide application, that residues were present in the
water column and in the sediment, with no clear pattern of decline.

Bioaccumulation

Bifenthrin appears to be highly bioaccumulative.  Fish bioaccumulation
studies showed that bifenthrin bioaccumulated with BCF of 2110x in
edible portion, 8720x in the non-edible portion, and 6090x in whole fish
exposed to 0.0006 to 0.001 ppb of the chemical for 42 days.  Depuration
was slow with 43-53% of the residues still remaining in the fish tissue
after 42 days of depuration.  To characterize the residues, fish were
exposed to a higher concentration of bifenthrin, and the parent
comprised 66.8-70.2% of the total radiocarbon, and 4’-OH-bifenthrin
was 3.2-3.6%.  Unextractable radioactivity was 21.4-23.4%. The following
was reported in a screened bioaccumulation in aquatic non-target
organisms study: BCFs were independent of the application rates: Daphnia
magna – 270-440x; Asellus (water exposure) – 71-82x; Asellus (water
and soil exposure) – 120-180x; Pimephales promela – 45-63x;
Corbicula (aqueous phase) – 41-74x; Corbicula (soil phase) –
92-140x.

Transport

Bifenthrin can be spray applied by ground or aerially on agricultural
settings.  A buffer region is label recommended (150 ft. for aerial
applications that do not use ULV); however, under a high end drift
scenario (e.g. small droplets and/ or high wind speed), substantial
amounts of the chemical can reach adjacent bodies of water via spray
drift.  In addition, substantial fractions of the applied bifenthrin
should be available for runoff for several weeks to several months after
application.  Due to its low solubility (0.0140 ppb) and high level of
binding (KOC values ranging from 131,000 to 302,000) it appears that
bifenthrin would remain bound to the soils during run-off events, and
that the chemical would reach surface waters if the run-off event is
accompanied by erosion; however, transport of the chemical when
dissolved in water is not precluded.  A recent study suggests that
dissolved organic carbon (DOC) present in sediments may facilitate the
desorption of sediment-sorbed pyrethroids (forming dissolved
pyrethroid-DOC complexes).  Such enhanced desorption in the presence of
DOC may enhance the mobility of pyrethroids in streams and by extension,
in soils via runoff containing high amounts of DOC (e.g., Delgado-Moreno
et al 2010).

Once bifenthrin reaches surface water, the fate of the chemical is of
concern since bifenthrin is very toxic to fish and aquatic
invertebrates.  The Agency believes that bifenthrin, due to its high
level of binding, would remain bound to the sediments and would dissolve
only very slowly into the water column.  Organisms that live near the
sediments may be particularly at risk.  The sediments may serve as
reservoirs or repositories of bifenthrin, where it appears that it will
persist, as shown in an aquatic field dissipation study.

Bifenthrin is not likely to reach subsurface soil environments or ground
waters.  Various terrestrial field dissipation studies confirm that
bifenthrin remains mostly in the upper soil level.

Uncertainties

The major uncertainties with respect to the environmental fate studies
on bifenthrin are related to the extremely low solubility of bifenthrin
and the problems found when the registrant performed these studies.  The
hydrolysis, aqueous photolysis, and batch equilibrium studies were
performed in unusually high concentrations of acetonitrile.  For
example, the aqueous photolysis study was performed in the presence of
30% acetonitrile.  However, no substantial photolysis was observed.  The
cosolvent may have had an effect on the results.  Furthermore, the batch
equilibrium studies were performed at a single concentration (a
Freundlich isotherm was not developed).  The EFED has had to rely on
single point results.  An additional source of uncertainty is the
absence of aerobic and anaerobic aquatic metabolism studies.  The
persistence of bifenthrin in aquatic environments is uncertain.

Table 3.6 is a summary of degradate formation for bifenthrin.  Note
that, because bifenthrin is relatively stable or dissipates very slowly
in all studies, no major transformation products (≥10% of the applied)
were observed.  No degradates were flagged for further quantitation;
however, in the terrestrial field dissipation study, 4’-OH-bifenthrin
was monitored and detected in some of the sites. 

Table 3.6.  Summary of degradate formation from degradation of
bifenthrin.

STUDY TYPE	SOURCE	DEGRADATE and MAXIMUM CONCENTRATION



DEG1 (% applied)	DEG2 (% applied)	DEG3 (% applied)

  Hydrolysis	ACC: 251728, MRID: 132539.	NO hydrolysis product exceeded
10% of the applied during the study.

  Aqueous Photolysis	ACC: 264642.	NO aqueous photolysis product exceeded
10% of the applied during the study.

  Soil Photolysis	ACC: 264642 or MRID 163085..	NO soil photolysis
product exceeded 10% of the applied during the study.

  Aerobic Soil Metabolism	MRID: 141202, 254411, 532540, 251728, 254401,
073225, 073174, 251278.	NO aerobic soil metabolism product exceeded 10%
of the applied during the studies.  The most significant metabolite (Met
I) at 3-5.6% of the applied radioactivity was identified as
4’-OH-bifenthrin.  

  Anaerobic Soil Metabolism	. Acc. No. 264642 or MRID 163088	NO
anaerobic soil metabolism product exceeded 10% of the applied during the
study.  The following metabolites were observed at low concentrations:
4’-OH-bifenthrin, TFP acid, BP-alcohol, BP-acid and BP-aldehyde.

  Aerobic Aquatic Metabolism	Not available	Not available

  Anaerobic Aquatic Metabolism	Not available	Not available

  Terrestrial Field Dissipation	MRID: 40981803, 40981805, 40981808,
40981812, 40981814, 40981815, 40981816, 40981817, 40981818, 40981819.	  
                         4’-OH-bifenthrin detected in certain studies.

3.4.	Open Literature Information

The following is a cursory search of the available literature on
bifenthrin and synthetic pyrethroids in general, mostly about their
prevalence/occurrence, and about their toxicity to aquatic
invertebrates, bees and sediment dwelling organisms (which also pertains
to Section 4.1).  It is not intended to be exhaustive.  In the
relatively recent past there has been an increased awareness of the
prevalence and toxicity of bifenthrin, and other synthetic pyrethroids,
in sediment environments of urban and agricultural sites, particularly
in California.  A comprehensive review of the relevant open literature
studies will be conducted as part of the forthcoming ecological risk
assessment.

A recent study (Dai et al., 2010) showed that both bifenthrin and
deltamethrin exposure via 1:1 sucrose:water solutions significantly
reduced bee fecundity, decreased the rate at which bees develop to
adulthood and increased their immature periods. The toxicity of
bifenthrin and deltamethrin in sucrose:water solutions on workers of
Apis mellifera ligustica was also assessed, and the results showed that
the median lethal effects of bifenthrin and deltamethrin were 16.7 and
62.8 mg/L, respectively.

Amweg, et al., 2005 determined the toxicity of various synthetic
pyrethroids towards the freshwater amphipod, Hyalella azteca.  They
found that of all the synthetic pyrethroids tested, bifenthrin exhibited
the highest toxicity (average sediment 10-day LC50 = 0.18 µg/gOC).  Two
major factors affect the toxicity of the synthetic pyrethroids: the
presence of the synergist piperonyl butoxide (PBO) and the temperature. 
Amweg and Weston, 2007, documented the effects of the presence of PBO in
sediments containing the synthetic pyrethroid bifenthrin and other
chemicals [cadmium (a metal), chlorpyrifos (an organophosphate), DDT (an
organochlorine), and flouranthene (a polycyclic aromatic hydrocarbon)]. 
The 10-day Hyalella azteca LC50 was 0.26 µg/gOC vs. 0.12 µg/gOC in the
presence of PBO in the overlying water, at only 25 µg/L (increased
toxicity by a factor of 2.2).  For the other chemicals, the factor was
around or less than 1 (one) with no statistical difference in toxicity
for all but chlorpyrifos.  Eight field collected sediments, containing a
variety of synthetic pyrethroids, or synthetic pyrethroids and
chlorpyrifos (except for one sediment that contained only chlorpyrifos),
that were previously tested and found to be toxic to Hyalella azteca,
were examined with and without the presence of PBO.  All the sediments
exhibited higher toxicity in the presence of PBO except for the sediment
that contained only chlorpyrifos.

The effect of temperature was documented by Weston et al., 2009a.  In an
effort to identify factors affecting the toxicity identification
evaluation (TIE) of the synthetic pyrethroids (“manipulating a sample
in a manner that alters the toxicity of some toxicants but not
others”), they performed sediment toxicity tests at various
temperatures (13, 18, 23, or 28ºC).  10-day LC50 values to Hyalella
azteca were determined for four pyrethroids, including bifenthrin, also
for chlorpyrifos, cadmium and DDT (which were representative of other
classes of chemicals).  For the four pyrethroids, the toxicity
approximately doubled when the temperature was decreased from 23 to
18ºC, and approximately tripled when the temperature was further
decreased to 13ºC.  The results at 28ºC were mixed, but for some of
the control samples, survival was low, which could indicate that the
test species was not tolerant of the change to high temperature.  DDT
presented a similar response profile with temperature, but not as
pronounced as for the synthetic pyrethroids.  For chlorpyrifos and
cadmium, the responses were nearly independent of temperature and
opposite to the one for the pyrethroids, respectively.  Various field
samples with known amounts of pyrethroids also showed similar responses
to those of the tested pyrethroids (as indicated above), with a few
exceptions.  The authors speculated on possible repercussions of the
temperature-dependency of synthetic pyrethroid toxicity during the
winter season, when the temperatures of the waters and sediments are
lower.

In a recent study conducted by the US Department of Housing and Urban
Development, in collaboration with the USEPA, several chemicals were
surveyed on floors of occupied homes (Stout II et al., 2009).  The
survey involved several synthetic pyrethroids including bifenthrin. 
Bifenthrin was detected with a frequency of 33% (mean = 0.18 ng/cm2,
standard deviation = 2.1 ng/cm2, maximum value = 43 ng/cm2),
illustrating that this chemical is commonly applied, detected and
present in homes.

Bifenthrin is among the constituents monitored by the National Water
Quality Assessment (NAWQA), maintained by the U.S. Geological Survey. 
Multiple articles from the literature document the presence of synthetic
pyrethroids, including bifenthrin, in both urban and agricultural
sediments.  Weston et al. (2005) studied the presence of synthetic
pyrethroids in Roseville, CA, selected as a typical suburban
development.  Sediments from creeks that drain subdivisions of
single-family homes were found to be toxic to Hyalella azteca.  The
sediments were tested for several pesticides, including 7 pyrethroids. 
From the study, it was reported that…“The pyrethroid bifenthrin is
implicated as the primary cause of the toxicity, with additional
contributions to toxicity from the pyrethroids cyfluthrin and
cypermethrin.”  Bifenthrin was present in all the sediment samples. 
The authors indicate that the presence of synthetic pyrethroids was not
likely to be due to agricultural uses.  In Placer County, the use of
synthetic pyrethroids for agricultural purposes was reported to amount
to around 1%.  Amweg et al. (2006) also studied synthetic pyrethroids in
urban areas of California and Tennessee.  Bifenthrin was considered to
be the major contributor to the toxicity of sediments sampled in
California, due to its high reported concentrations and toxicity. 
However, in Tennessee only a few samples contained synthetic pyrethroids
and none of the samples were toxic to Hyalella azteca.  The differences
between the two sites were attributed to different climate, types of
residential development and pesticide use practices.

Holmes et al. (2008) presented the occurrence and toxicity of the
synthetic pyrethroids throughout the state of California’s urban creek
sediment samples.  First, 90 samples were screened for toxicity to
Hyalella azteca, of which around one third caused significant toxicity
to the organisms.  Later, 30 sample locations were selected for the
final study.  Of the 30 samples, 25 were toxic to H. azteca at 23ºC and
all 30 samples were toxic at 15ºC (the synthetic pyrethroids often show
higher toxicity at lower temperatures, see above).  Seven of eight
pyrethroids were detected in the sediment samples.  Fenpropathrin was
not detected in any of the samples, but bifenthrin was present in all
the 30 samples (2.19 to 219 ng/g dry weight).  Permethrin was the second
most detected pyrethroid.  The results suggested an important role of
the synthetic pyrethroids in California’s urban creeks sediment
toxicity.  When the toxic units (TUs) are partitioned by individual
pyrethroids, bifenthrin accounted for around two thirds of the toxicity
on an average basis statewide.  These are just a few examples that
illustrate the high use of synthetic pyrethroids in urban settings and
potential ecological ramifications.

Trimble et al. (2009) screened a previously referenced database of 24
pesticides and 94 urban sediment samples, with minimal agricultural or
industrial contribution, collected from creeks and streams throughout
central and northern California.  The synthetic pyrethroids and
chlorpyrifos were the pesticides detected more frequently.  Bifenthrin
was observed in greater than 90% of the samples (so did permethrin and
DDT).  After normalizing the chemical concentrations for organic carbon
“to provide better estimates of the biologically available chemical
fractions,” all the seven pyrethroids monitored had levels exceeding
the established level of interest, LOI (defined as 0.005 toxic units,
0.005 TU) for at least one sample.  Bifenthrin exceeded 0.5 TU (100x the
initially established LOI) in greater than 30% of the samples (so did
cypermethrin and cyfluthrin).

Budd et al. (2007) sampled sediments in mixed land (urban and
agricultural) in the San Diego Creek in Newport Bay Watershed in
southern California.  Bifenthrin and fenpropathrin were among the most
frequently detected synthetic pyrethroids, with bifenthrin found in
95-100% of the samples.  The highest concentrations were associated with
commercial nurseries.  The authors found in this case that the
concentration of synthetic pyrethroids was generally lower in
residential or commercial areas as opposed to agricultural sites.  Also,
the frequency of detections of pyrethroids was higher during the wet
season but the total concentration was not statistically different
between the wet and dry seasons.  Weston et al. (2004) studied the
presence of 26 pesticides, including five pyrethroids, in 70 sediment
samples taken from the agriculture dominated Central Valley in
California.  Ten-day sediment tests were conducted for Hyalella azteca
and Chironomus dilutus (formerly known as Chironomus tentans), for some
of the samples.  Synthetic pyrethroids were found in 75% of the sediment
samples; also they were found, based on a toxicity unit basis, to be
sufficiently high to cause toxicity in 40% of the samples toxic to C.
dilutus and around 70% of the samples toxic to H. azteca.  The most
commonly found pyrethroids were permethrin > esfenvalerate > bifenthrin
> lambda-cyhalothrin.

In a study, Gan et al. (2005) monitored the spatial distribution and
enrichment (enrichment ratio, ER, or ratio of the concentration of a
substance in eroded sediment to that of the source matrix) of the
synthetic pyrethroids permethrin and bifenthrin, along a 260-m runoff
path.  A sedimentation pond was used as the source point for the study
(permethrin and bifenthrin had been used extensively at the site, for
ant control, in a nursery environment).  It was observed that, in
general, the sediment concentration of permethrin and bifenthrin
increased with distance (downstream from the source).  Using the source
as the reference value, ERs were calculated for these chemicals.  The ER
reached 25.7-32.2 for bifenthrin at 145 m and beyond, and they were
lower for permethrin.  Also, the persistence of the test substances was
assessed, both, in aerobic and anaerobic environments.  The aerobic
aquatic half-lives in three sediments, for bifenthrin at 20ºC, found by
the researchers, were in the range of 428-483 days and the anaerobic
half-lives were 251-498 days.  The permethrin degradation under similar
conditions was significantly faster.  Weston et al. (2009b) found that
bifenthrin was the most frequently detected pyrethroid from runoff
waters from Roseville and Elk Grove urban sites.  Cyfluthrin and
permethrin were also frequently detected.  During the dry season,
bifenthrin was detected with a frequency of 75%, while during the wet
season, it was found with a frequency of detection of 100%.  It was
noted that stormwater runoff (mostly around the winter) was responsible
for more transport than irrigation runoff (mostly around the summer),
towards surface waters.  It was suggested that mitigation of the effects
of the synthetic pyrethroids would target both sources of runoff.  It
was reported that the use of bifenthrin (for retail and for professional
use) was higher approximately in the months around the summer.

Most of the studies related to the synthetic pyrethroids were conducted
in California.  Other studies document the presence of bifenthrin
elsewhere.  LeBlanc & Perkins (2009) documented the presence of the
chemical in Maine sediments.  Of five synthetic pyrethroids monitored,
only bifenthrin was detected, at levels of 1.26 – 16.68 ng/g (means). 
The other synthetic pyrethroids monitored were lambda-cyhalothrin,
permethrin, cyfluthrin and cypermethrin.  Four sediments were monitored:
 Mill Creek Lower Intertidal, Mill Creek Upper Intertidal, Back Cove and
Payson Park.

e pyrethroid found with the highest frequency of 94.1% (mean = 0.74
μg/gOC; maximum = 2.9 μg/gOC; compared to 10-day LC50 to Hyalella
azteca of 0.52 μg/gOC).  Approximately 50% of the bifenthrin
concentrations were greater than the LC50.  Lambda-cyhalothrin and
permethrin were also frequently detected; the detections of
lambda-cyhalothrin occurred frequently at concentrations of concern, but
the concentrations of permethrin were below the LC50 for H. azteca. 
Bifenthrin was the greater contributor to the TUs, followed by
lambda-cyhalothrin.  The TUs generally correlated well with the toxicity
of the samples, although some discrepancies between the TUs and toxicity
were noted (even after normalization for organic carbon).  There were no
seasonal variations of the TUs.  It was noted that bifenthrin and
lambda-cyhalothrin are often used to control fire ants and grub worms.

Ding et al. 2010 conducted monitoring for 29 pesticides, including
pyrethroids like bifenthrin and fenpropathrin, from both urban and
agricultural sites in central and southern counties in the state of
Illinois in 2008.  Most of the urban samples were from constructed storm
drains, while the agricultural samples were from small waterways between
farmlands in areas where mostly corn and soybeans were grown and the
major pesticides used were tefluthrin and atrazine.  Furthermore,
sediment toxicity tests towards Hyalella azteca were performed.  In the
urban samples, the synthetic pyrethroids were detected in 95% of the
samples.  Bifenthrin was detected in 80% of the samples, while
permethrin, lambda-cyhalothrin and fenpropathrin were also frequently
detected.  In the agricultural samples, bifenthrin, permethrin,
cypermethrin and tefluthrin were detected (frequency of detection 47%),
while fenpropathrin and lambda-cyhalothrin were not detected.  Ten of 17
urban sediment samples tested were significantly more toxic to H. azteca
than the controls.  Only one of the agricultural sediment samples was
significantly more toxic than the control.  The major source of TUs was
the pyrethroids (in particular, bifenthrin).  It was indicated that the
detections of fenpropathrin in the urban samples was unexpected because
it is a pesticide primarily used in agriculture.

Weston and Lydy (2010) studied the possible sources of pyrethroids in
California’s Sacramento – San Joaquin River Delta, including urban
runoff, municipal wastewater treatment plants (or Publicly Owned
Treatment Works, POTWs), and agricultural discharges, in a study that
focused on water samples (as opposed to most of the studies above that
are related to sediments).  Samples were taken during the wet and dry
seasons.  Urban runoff samples were taken from concrete sumps, from
which pumps lift waters to adjacent rivers over levees.  POTWs with
secondary treatment were sampled just prior to discharge to surface
waters.  Agricultural discharges were collected at pump stations, where
the runoff is lifted over the levees.  Samples were tested for 8
pyrethroids and chlorpyrifos (LOQ around 1 ng/L for most samples). 
Tests to Hyalella azteca were also performed at the temperature measured
in the rivers.  Bifenthrin was found in 79, 39 and 12% of the samples of
urban runoff, POTWs and agricultural drains, respectively.  Also, 58, 22
and 2% of the samples, respectively, exceeded the EC50 = 3.3 ng/L for H.
azteca.  The maximum measured bifenthrin concentration was 29.8 ng/L. 
Through toxicity identification evaluation (TIE), it was found that the
toxicity was increased for most samples in the presence of PBO.  A
similar effect was observed when the temperature of the samples was
decreased.  In the presence of the enzyme E3, which is capable to
degrade the pyrethroids, the effect was a decreased toxicity of the
samples towards H. azteca.  In the presence of BSA (bovine serum
albumin), no effect on the toxicity of the samples towards H. azteca,
was observed.  The pyrethroid presence in POTWs was unexpected because
the effluents had low suspended material and the possible partitioning
with biosolids within the plants.  The authors indicated that possible
sources of pyrethroids are sewer disposal of household insecticides,
lice control shampoos, pet products and permethrin treated clothing.

Weston 2007 said that, “Contrary to popular perception,
non-agricultural use of pyrethroids far exceeds agricultural use, at
least in California, one of the few areas where data are available. A
similar situation is likely elsewhere where there is substantial urban
development. Whereas agricultural use of pyrethroids in California is
about 300,000 lb/yr, non-agricultural commercial use (mostly
applications done by professional pest control firms) is currently about
700,000 lb/yr. Retail sales to homeowners are not included in this
non-agricultural figure, but are probably about another 100,000 lb/yr.
Some of the major urban uses of pyrethroids include cypermethrin and
permethrin for termite control, permethrin to maintain landscaping, and
bifenthrin and cyfluthrin for a variety of pests around homes.”

In an effort to understand the fate of various insecticides on
hardscapes such as concrete, Jiang et al. (2010) measured the wash-off
potential of pesticides from impervious (concrete) surfaces, as possible
source of pesticide runoff following applications around homes.  Four
model pyrethroids were used.  The authors suggested that concrete
surfaces may serve as reservoirs or repositories of pyrethroids for
extended periods of time, and were possibly “retained below the
surface, likely in the micropores, due to physical trapping or chemical
sorption.”

Another effort to study pyrethroids on impervious surfaces was offered
by Jorgenson and Young (2010).  They studied the washoff profiles among
different formulations, and were led to also study the effects of inert
ingredients such as surfactants on the wash-off from concrete surfaces. 
Four pyrethroids (three types of formulations and five products) were
used.  Analysis of the formulations tested revealed complex mixtures. 
It was determined analytically that four of the five products contained
linear alkylbenzene sulfonate surfactant (LAS) at various
concentrations; thus, LAS was selected as a model surfactant to
determine the role of formulation components on pyrethroid wash-off. 
The experiments included: formulated products, neat pyrethroids (only
esfenvalerate and bifenthrin), and pyrethroid plus LAS (only
bifenthrin).  These researchers used a rain simulator to model runoff
events.  For the pyrethroids, during a runoff event, an initial rapid
dissipation was followed by a steadier rate of wash-off in most
instances (named Type A profile).  In other instances, a relatively
constant rate of pyrethroid wash-off during the whole runoff-event was
noted (named Type B profile).  Increasing the set time decreased the
wash-off for all the products.  It appeared that the EC formulation
tended to yield Type B profiles, as observed for lambda-cyhalothrin and
esfenvalerate.  When bifenthrin and esfenvalerate were applied in hexane
(as opposed to formulation), the dissipation followed the Type B
profile.  Testing of bifenthrin with LAS surfactant alone, resulted in a
Type A profile, and in an increase (7-fold) of the total mass wash-off
and of the event mean concentrations (EMC).  However, the total mass
removed was not as high as for the formulation 2007 Bifenthrin CE
(microemulsion RTU).  The authors indicate that the complexities and
differences of a formulated product may be responsible for the behavior
(order of magnitude differences) of the pyrethroids on concrete
surfaces.

Jiang et al. (In press) also provided information about the pyrethroid
permethrin on concrete substances.  Among other findings, the authors
reported that the permethrin desorption from such surfaces decreases
with sorption time.  This was attributed to the possible alkaline
decomposition of the test substance on the surface.  The authors
indicated that there is the potential for extended contamination due to
permethrin treated surfaces.

In the summer of 2007 and 2008, a number of residences in Riverside and
Moreno Valley, California were treated with bifenthrin and fipronil
insecticides and irrigated according to typical practices (Greenberg et
al. 2010).  Runoff from such residences was analyzed for bifenthrin and
for fipronil (including fipronil transformation products).  In 2007, the
mean bifenthrin concentrations from spray applications was 14.9 ug/L 1
week after application and 2.5 ug/L at 8 weeks after application. 
Bifenthrin granular applications resulted in much lower concentrations
in the runoff, which appeared to indicate that formulations may affect
the levels of runoff.  It was also found that, “During 2008,
insecticide runoff was reduced by using spray-free zones and pin stream
perimeter applications.”

4.	Receptors

4.1.	Aquatic and Terrestrial Effects

The receptor is the biological entity that is exposed to the stressor
(EPA, 1998).  Due to the outdoor uses of bifenthrin, the types of
receptors that may be exposed include both aquatic and terrestrial
receptors, such as birds, reptiles, mammals, amphibians, freshwater and
estuarine/marine fish, non-target terrestrial & aquatic invertebrates
and terrestrial & aquatic plants.  This list may not be comprehensive. 
Spray drift and runoff exposures are expected for both ground and aerial
applications of bifenthrin.  Consistent with the process described in
the Overview Document (USEPA, 2004), this risk assessment uses a
surrogate species approach in its evaluation of bifenthrin.  T  SEQ
CHAPTER \h \r 1 oxicological data generated from surrogate test species,
which are intended to be representative of broad taxonomic groups, are
used to extrapolate to potential effects on a variety of species
(receptors) included under these taxonomic groupings.   

Tables 4.1 and 4.2 provide a summary of the taxonomic groups and the
surrogate species tested to help understand potential acute ecological
effects of pesticides to these non-target taxonomic groups.  In
addition, the tables provide a preliminary overview of the potential
acute toxicity of bifenthrin by providing the acute toxicity
classifications.

Terrestrial Species

  SEQ CHAPTER \h \r 1 The available toxicity data suggests that
bifenthrin appears to be slightly toxic on an acute basis to avian
species based on a bobwhite quail (Colinus virginianus) single dose LD50
of 1800 mg/kg bw (ACC 251727) and an 8-day dietary LC50 of 1280 mg/kg
diet for the mallard duck (Anas platyrynchos). Bifenthrin showed no
adverse effects to reproduction at the highest concentration tested
(NOAEC = 75 mg/kg diet) in the two one-generation chronic studies
conducted on the bobwhite quail and mallard duck.

Mammalian toxicity data suggest that this compound is moderately toxic
to small mammals on an acute basis (rat LD50 = 53.8 mg/kg). Reproductive
effects were based on decreased maternal bodyweight noted at an LOAEC of
60 ppm (NOAEC = 30 ppm). For mammalian toxicity, EFED will coordinate
with HED to determine the most appropriate endpoints for acute and
chronic studies.

As expected for a registered insecticide, bifenthrin is very highly
toxic to nontarget terrestrial invertebrates. An acute contact study on
honeybees (Apis mellifera) for bifenthrin 0.8EC produced an LD50 = 0.015
µg/bee (Atkins, 1981). 

Table 4.1 Summary of most sensitive endpoints from submitted terrestrial
toxicity studies for bifenthrin.  

Species 

(common name)	Taxa Represented	End-point	Concentration	Test Substance (%
ai)	Citation 

MRID 

	Acute Toxicity Classification

Rat	Mammals	LD50	53.8 mg/kg	91.4	00132519	Moderately

Rattus norvegicus

(Laboratory Rat)

NOAEL	30 ppm	88.35	005336	N/A



LOAEL	60 ppm



	Colinus virginianus

(Bobwhite quail)

	Birds, terrestrial- phase amphibians, and reptiles	LD50	 1800 mg/kg bw
88.3	ACC 251727

Fletcher, 1984	 Slightly toxic

Anas platyrynchos (Mallard duck)

LC50	1280 mg/kg diet	88.3	ACC 251727

Fletcher, 1984	Slightly toxic

Colinus virginianus

(Bobwhite quail)

and

Anas platyrynchos (Mallard duck)

NOAEC	75 mg/kg diet	88.3%	264644

Huntington,

1987



	LOAEC	NA



	Apis mellifera

(Honey bee)	Terrestrial invertebrates	LD50	0.015 µg/bee	0.8% EC
VAOTALO1

Atkins, 1981	Very highly toxic



Aquatic Species

 

Freshwater

Bifenthrin technical is very highly toxic to freshwater fish, with a
96-hour LC50 = 0.15 µg ai/L in the most sensitive acute test conducted
on rainbow trout (Oncorhynchus mykiss). In other tests with bifenthrin
technical, the 96-hour LC50 = 0.35 µg a.i./L for warmwater bluegill
sunfish (Lepomis macrochirus). A chronic freshwater fish study for
bifenthrin technical resulted in an NOAEC of 0.04 µg a.i./L and LOAEC
of 0.096 µg ai/L for fathead minnow (Pimephales promelas) based on
reduced growth. 

Daphnia magna is used as the test species for freshwater invertebrates
for both acute and chronic effects. Acute toxicity values for daphnids
suggest that bifenthrin technical is very highly toxic to freshwater
invertebrates, with a 48-hour EC50 of 1.6 µg ai/L. Chronic toxicity to
invertebrates is represented through D. magna life cycle studies. In a
daphnid chronic life-cycle test with bifenthrin, the NOAEC = 0.0013
µg/L and the LOAEC = 0.003 µg/L based on adverse effects to growth and
# of young at mean-measured concentrations.  

Estuarine/Marine

Estuarine/marine fish are represented by the sheepshead minnow
(Cyprinodon variegatus). Acute toxicity studies indicates that
bifenthrin is very highly toxic to estuarine/marine fish, with an LC50 =
17.5 µg ai/L for the technical material.

Estuarine/marine aquatic invertebrates are represented by the mysid
shrimp (Americamysis bahia, formerly Mysidopsis bahia) and eastern
oyster (Crassostrea virginica) with toxicity studies indicating
bifenthrin is very highly toxic to both. In an acute study with mysid
shrimp, the 96-hour LC50 = 0.0040 µg ai/L for bifenthrin technical,
based on mean-measured concentrations.  In a study with the eastern
oyster, the 96-hour EC50 was 285 µg ai/L for bifenthrin technical. No
chronic estuarine/marine study with estuarine/marine invertebrates has
been submitted for bifenthrin. 

Table 4.2.  Summary of most sensitive endpoints from submitted aquatic
toxicity studies for bifenthrin.  

Species

(common name)	Taxa Represented	End-point	Duration

(hours)	 Mean concentration (µg ai/L)	Citation 

MRID 	Acute Toxicity Classification

Oncorhynchus mykiss

(Rainbow trout)	Freshwater fish and aquatic-phase amphibians	LC50	96
0.15	ACC251727

Hoberg 1983	Very Highly toxic

Pimephales promelas

(Fathead Minnow)

NOAEC	28 (days)	0.04	40791301





	LOAEC

0.096



Daphnia  magna

(Water Flea)	Freshwater Invertebrates 	EC50	48	1.6	41156501	Very highly
toxic



NOAEC	 21 (days)	0.0013	41156501



	LOAEC

0.003



Cyprinodon variegatus (Sheepshead minnow)	Estuarine/ Marine Fish	LC50	96
17.5	ACC264646

Battelle 1987	Very highly toxic

Americamysis bahia

(Mysid shrimp)	Estuarine/ Marine Invertebrates	LC50	96	0.004	

ACC264647

Battelle 1987	Very highly toxic



NOAEC	28 (days)	NA	NA	NA



LOAEC

NA





Plants

No aquatic or terrestrial plant data are available to the Agency for
bifenthrin. Prior assessments indicated that risks were unlikely due to
the chemical’s mode of action.  The Tier I study as defined in the
Pesticide Registration Rejection Rate Analysis (EPA 738-R-94-085 SD
December 1994) requires the EC50 aquatic plant test for Lemna gibba and
Selenastrum carpicornutum. New guidelines also require terrestrial plant
studies. 

ECOTOX

Available open literature will be used to evaluate the potential direct
effects of bifenthrin to the terrestrial receptors identified in this
section. This includes toxicity data on the technical grade active
ingredient, and when available, formulated products (e.g. “Six-Pack”
studies). 

At this time, a full and complete ECOTOX search has not been performed,
but will be conducted prior to issuance of any Data Call-in.  The open
literature studies will be identified through EPA’s ECOTOX database ( 
HYPERLINK "http://cfpub.epa.gov/ecotox/"  http://cfpub.epa.gov/ecotox/
), which employs a literature search engine for locating chemical
toxicity data for aquatic life, terrestrial plants, and wildlife.   The
evaluation of data can also provide insight into the direct and indirect
effects of bifenthrin on biotic communities from loss of species that
are sensitive to the chemical and from changes in structure and
functional characteristics of the affected communities. Open literature
toxicity data for other ‘target’ insect species (not including bees,
butterflies, beetles, and non-insect invertebrates including soil
arthropods and worms), which include efficacy studies, are not currently
considered in deriving the most sensitive endpoint for terrestrial
insects.   Efficacy studies do not typically provide endpoint values
that are useful for risk assessment (e.g., NOAEC, EC50, etc.), but
rather are intended to identify a dose that maximizes a particular
effect (e.g., EC100).  Therefore, efficacy data and non-efficacy
toxicological target insect data will not be included in the ECOTOX open
literature search. 

4.2.	Incident Database Review 

A preliminary review on January 20, 2010 of the Ecological Incident
Information System (EIIS, version 2.1), which is maintained by the
Agency’s Office of Pesticide Programs indicates reported ecological
incidents associated with the use of bifenthrin. These incidents are
summarized in Table 4.3. This total excludes incidents classified as
‘unlikely’ and only includes those incidents with certainty
categories of ‘highly probable’, and ‘probable’ and
‘possible’ (for EIIS) and ‘certain’, ‘highly likely’,
‘likely’, ‘probable’, and ‘possible’ (for AIMS).  In the
EIIS and AIMS databases, the “unlikely” category is used when a
chemical is not likely to be responsible for the incident.  For example,
an ‘unlikely’ classification might be applied in situations where a
given chemical is practically nontoxic to the category of organism
killed and/ or there is evidence that another pesticide or stressor
likely caused the incident.  Incidents classified as ‘unlikely’ for
bifenthrin will not be included in this Problem Formulation or the
ecological risk assessment conducted for Registration Review.  

There were 2 incidents reported as being highly probable, 5 reported as
probable and 3 reported as possible for bifenthrin. These incidents do
show that aquatic organisms and possibly bees may be adversely affected
if exposed.  See Table 4.3 for summary information.

Table 4.3. Wildlife Incidents Associated with Bifenthrin

Incident Number 	Taxa

Involved	Magnitude	Year	Location (County, State)	Use	Legality of Use
Certainty Category1	Residue

I016338-006	Fish	500	2005	Dutchess, NY	Building

Spray	RU	Highly Probable	No

I017659-001	Catfish

Koi	400	2006	CA	Residential Turf	RU	Highly Probable	No

I001280-019	Catfish	Small #	1994	NE	Corn Spray	M	Probable	No

I003351-028	Catfish	25	1994	Imperial, CA	Not reported	UN	Probable	No

I004439-076	Fish	Unknown	1996	NC	Not reported	RU	Probable	No

I009262-121	Rose	5	1999	Erie, NY	Home Tree	RU	Probable	No

I000080-009	Leafcutter bee	Unknown	1992	Not Reported	Alfalfa Seed	M
Probable	No

I012786-002	Trees	19	2001	Not Reported	Trees	UN	Possible	No

I012786-004	Cherry Laural	Unknown	2001	Not Reported	Trees	UN	Possible	No

I020835-001	Bees	61 hives	2007	UT	Alfalfa

Spray	UN	Possible	No

1Incidents classified as ‘unlikely’ are excluded.

RU=Registered Use

M=Misuse

UN=Unknown

Incident reports for non-target organisms typically provide information
only on mortality events and plant damage incidents. Except for
phytotoxic effects in terrestrial plants, sublethal effects for
organisms such as reduced growth or impaired reproduction are rarely
reported. EPA’s changes in the registrant reporting requirements for
incidents in 1998 may account for a reduced number of reported
incidents.  Registrants are now only required to submit detailed
information on ‘major’ fish, wildlife, and plant incidents.  Minor
fish, wildlife, and plant incidents, as well as all other nontarget
incidents, are generally reported aggregately and are not included in
EIIS.  In addition, there have been changes in state monitoring efforts
due to lack of resources.  

In the forthcoming risk assessment, each incident will be further
evaluated to determine if it represents current patterns of use for
bifenthrin.  Examples of additional considerations are mitigation (e.g.,
reduced application rates), product cancellations, and changes in use
patterns that have occurred since the date of the reported incidents.

As it has been indicated earlier, bifenthrin is among the constituents
monitored by the National Water Quality Assessment Data Warehouse,
(NAWQA) maintained by the U.S. Geological Survey; furthermore, multiple
articles from the literature document the presence of synthetic
pyrethroids like bifenthrin in both urban and agricultural sediments
(refer to Section 3.2).

4.3.	Ecosystems Potentially at Risk 

Bifenthrin may be applied on a variety of food crops, including (but not
limited to) corn, cotton, green beans, strawberries & raspberries,
canola, pumpkins, cantaloupe and squash.  In addition, it may be used in
numerous non-food sites (e.g. commercial or residential lawns, and
structural pest control).  Thus, the ecosystems at risk may be extensive
in scope, and as a result it may not be possible to identify specific
ecosystems during the development of a baseline risk assessment.  In
general terms, terrestrial ecosystems potentially at risk due to the use
of bifenthrin, could include the treated field and areas immediately
adjacent to the treated field that may receive drift or runoff.  Areas
adjacent to the treated field could include cultivated fields, fencerows
and hedgerows, meadows, fallow fields or grasslands, woodlands, riparian
habitats and other uncultivated areas.  Due to the persistence of
bifenthrin, it is expected to drift and/or runoff due to application to
food crops, resulting in possible exposure to aquatic ecosystems.
Aquatic ecosystems potentially at risk due to the use of bifenthrin
include water bodies adjacent to, or down stream from, the treated field
and might include impounded bodies such as ponds, lakes and reservoirs,
or flowing waterways such as streams or rivers. For uses in coastal
areas, aquatic habitat also includes marine ecosystems, including
estuaries. 

5.	Assessment Endpoints tc \l2 "C.	Assessment and Measurement Endpoints 


Assessment endpoints are defined as “explicit expressions of the
actual environmental value that is to be protected.”  Defining an
assessment endpoint involves two steps: 1) identifying the valued
attributes of the environment that are considered to be at risk; and 2)
operationally defining the assessment endpoint in terms of an ecological
entity (i.e., a community of fish and aquatic invertebrates) and its
attributes (i.e., survival and reproduction).  Therefore, selection of
the assessment endpoints is based on valued entities (i.e., ecological
receptors), the ecosystems potentially at risk, the migration pathways
of pesticides, and the routes by which ecological receptors are exposed
to pesticide-related contamination.  The selection of clearly defined
assessment endpoints is important because they provide direction and
boundaries in the risk assessment for addressing risk management issues
of concern.  Changes to assessment endpoints are typically estimated
from the available toxicity studies, which are used as the measures of
effects to characterize potential ecological risks associated with
exposure to pesticides, such as bifenthrin.

To estimate exposure concentrations, the ecological risk assessment
considers applications at the maximum application rate to fields that
have vulnerable soils.  The most sensitive toxicity endpoints are used
from surrogate test species to estimate treatment-related direct effects
on acute mortality and chronic reproductive, growth and survival
assessment endpoints.  Toxicity tests are intended to determine effects
of pesticide exposure on birds, mammals, fish, terrestrial and aquatic
invertebrates, and plants.  These tests include short-term acute,
sub-acute, and reproduction studies and are typically arranged in a
hierarchical or tiered system that progresses from basic laboratory
tests to applied field studies.  The toxicity studies are used to
evaluate the potential of a pesticide to cause adverse effects, to
determine whether further testing is required, and to determine the need
for precautionary label statements to minimize the potential adverse
effects to non-target animals and plants.

An open literature search will be conducted to determine any relevant
endpoints. The search will focus on survival, growth and reproductive
effects for aquatic and terrestrial effects of bifenthrin. More
sensitive endpoints from acceptable open literature studies will be
included in this risk assessment.

 6.     Conceptual Model tc \l2 "D.        Conceptual Model 

For a pesticide to pose an ecological risk, it must reach ecological
receptors in biologically significant concentrations.  An exposure
pathway is the means by which a pesticide moves in the environment from
a source to an ecological receptor.  For an ecological pathway to be
complete, it must have a source, a release mechanism, an environmental
transport medium, a point of exposure for ecological receptors, and a
feasible route of exposure.

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

6.1.	Risk Hypothesis tc \l3 "1.         Risk Hypotheses 

Risk hypotheses are specific assumptions about potential adverse effects
(i.e., changes in assessment endpoints) and may be based on theory and
logic, empirical data, mathematical models, or probability models (USEPA
1998).  For this assessment, the risk is stressor-initiated, where the
stressor is the release of bifenthrin into the environment.  The
following risk hypotheses are presumed for this screening-level
assessment:

Bifenthrin, when used outdoors in accordance with registered labels,
will likely lead to off-site movement of the compound via agricultural
and urban runoff, spray drift, and eroded soil leading to exposure of
nontarget plants and animals  Based on information on the environmental
fate, mode of action, direct toxicity and potential indirect effects,
EFED assumes that registered uses of bifenthrin have the potential to
cause reduced survival, growth, and reproduction to non-target
terrestrial and/ or aquatic animals and plants.

Bifenthrin, when used indoors, in accordance with current labels, may
result in off-site movement of the compound via wash-off into surface
waters via drains and municipal wastewater treatment plants, leading to
exposure of nontarget aquatic plants and animals.  This potential
exposure pathway may result in adverse effects upon the survival,
growth, and/or reproduction of non-target aquatic animals and plants.

 

The conceptual model is a generic graphic depiction of the risk
hypothesis.  It includes the potential pesticide or stressor
(bifenthrin), the source of the pesticide and/or transport pathways,
exposure media, exposure point, biological receptor types, and attribute
changes.

6.2.	Conceptual Diagram tc \l3 "2.         Diagram 

The conceptual site model is a generic graphic depiction of the risk
hypothesis, and assumes that the insecticide bifenthrin, a Type I
synthetic pyrethroid, having multiple outdoor agricultural and
non-agricultural uses, is capable of affecting aquatic and terrestrial
animals provided that environmental concentrations are sufficiently
elevated as a result of proposed label uses.  Based on an examination of
the physicochemical properties of bifenthrin, the fate and disposition
in the environment, and mode of application, a conceptual model was
developed that represents the possible relationships between the
stressors, ecological receptors, and the assessment endpoints.  Through
a preliminary iterative process of examining available data, the
conceptual model (i.e., the representation of the risk hypothesis) may
be refined to reflect the likely exposure pathways and the organisms
that are most relevant and applicable to this assessment (see Figures
6.1a and 6.1b, below). They include the potential pesticide or stressor
(bifenthrin, but the presence of toxicologically important metabolites
cannot be ruled out), the sources and/ or transport pathways, exposure
media and exposure points, biological receptor types and attribute
changes.

In order for a chemical to pose an ecological risk, it must reach
ecological receptors in biologically significant concentrations. An
exposure pathway is the means by which a pesticide moves in the
environment from a source to an ecological receptor. For an ecological
exposure pathway to be complete, it must have a source, a release
mechanism, an environmental transport medium, a point of exposure for
ecological receptors, and a feasible route of exposure.  In addition,
the potential mechanisms of degradation/ transformation (i.e., which
degradation/ transformation products may form in the environment, in
which media, and how much) must be understood, especially if for the
chemical, its metabolites/ transformation products are of greater
toxicological concern than the parent compound (note, however, that this
is not the case for bifenthrin, for which at this time, no major
metabolites have been identified).  The assessment of ecological
exposure pathways, therefore, includes an examination of the source and
potential migration pathways for constituents, and the determination of
potential exposure routes.

Under the possible uses of bifenthrin, the sources and mechanisms of
release of the compound are from ground or aerial spray or ULV
applications (note that this conceptual model considers agricultural
applications as well as certain non-agricultural and urban
applications).  Surface runoff from the areas of application is assumed
to depend on factors such as topography, irrigation, and rainfall
events.  In urban areas, factors that affect surface runoff also include
the presence of impervious surfaces and storm drain system design. 
Direct deposition may result in contamination of food items that may be
consumed by terrestrial organisms.  Spray drift results in contaminated
adjacent areas, including bodies of water.  Note that leaching to
groundwater is not considered an important source because bifenthrin is
highly immobile.  Due to bifenthrin’s potential for volatilization,
atmospheric transport cannot be ruled out.  It is noted, though, that
the estimated hydroxyl radical reaction half-life estimated by EpiSuite
v.4.0 is only 0.36 days.  It appears that bifenthrin would not persist
in the environment for extended periods of time.

For aquatic receptors, the major point of exposure is through direct
contact with the water column, sediment, and pore water (gill/
integument) contaminated with spray drift (from spray application)
and/or runoff and flow (e.g., piped storm drains) from treated areas. 
Indirect effects to aquatic organisms (both fish and aquatic
invertebrates) can also occur through impact to various food chains (it
was established earlier in this document that bifenthrin has the
potential to bioaccumulate/bioconcentrate).  The representative aquatic
receptors are certain freshwater and estuarine/ marine fish,
invertebrates, and, in certain cases, aquatic plants.  The major point
of exposure for terrestrial animals is consumption of food contaminated
with residues such as grass, foliage, and small insects.  For plants,
the point of exposure is direct contact or root uptake.  The
representative terrestrial receptors are mammals, birds and terrestrial
plants.  The attribute changes used to assess risk to terrestrial
receptors depend on the type of test (e.g., reduced survival, growth, or
reproduction for animals and seedling emergence and vegetative vigor for
plants).  It should be noted, that these species do not cover all the
possible species in the animal and plant kingdoms; certain taxa are
considered as surrogates for other taxa.  For example, fish are
considered surrogates for aquatic phase amphibians in the absence of
amphibian toxicity data.

This conceptual model also shows details about biomagnification for a
chemical (see piscivorous birds and mammals in Fig. 6.1a).  Bifenthrin
has a very high KOW and according to its physicochemical and fate
properties, there is a potential for bioaccumulation/ bioconcentration
in aquatic organisms, and biomagnification in terrestrial organisms.

Bifenthrin shows a very low solubility, a very high KOW and also high
KOC’s.  These properties suggest that the chemical partitions with the
sediments, and with organic matter, suspended in the water bodies. 
Bifenthrin is likely to concentrate in the sediments, where it could
persist.  Such sediments could serve as repositories of the chemical for
extended periods of time and could potentially be toxic to sediment
dwelling organisms, affecting the food chain; however, transport of
bifenthrin when dissolved in water is not precluded, especially when it
occurs on impervious surfaces.  These issues will also be assessed in
the risk assessment for bifenthrin.

Despite the fact that bifenthrin shows a moderate Henry’s Law
Constant, that would suggest some potential for volatilization, and it
is persistent in the environment, the hydroxyl radical reaction
half-life for the chemical is 0.4 days (EPI Suite v.4.0 estimate).  The
short (atmospheric) half-life suggests that the potential for
atmospheric transport for bifenthrin is relatively low and that this
source of the chemical is of low importance, compared to spray drift,
runoff and/ or direct contact after application.

Figure 6.1a.  Aquatic conceptual model depicting stressors, exposure
pathways, and potential effects to aquatic organisms from the use of
bifenthrin on agricultural and certain non-agricultural sites

 

1 Includes flow across vegetation and vegetated drainage systems (e.g.,
swales) and flow across impervious surfaces and through impervious
(piped) storm drains.

2 Immobilization is considered equivalent to mortality in toxicity tests
for aquatic invertebrates.

Dotted lines indicate exposure pathways that have a low likelihood of
contributing to ecological risk.

Figure 6.1b.  Terrestrial conceptual model depicting stressors,
exposure pathways, and potential effects to terrestrial organisms from
the use of bifenthrin on agricultural and certain non-agricultural sites
 

  SHAPE  \* MERGEFORMAT   

 

Dotted lines indicate exposure pathways that have a low likelihood of
contributing to ecological risk.  

 

The conceptual model for potential risks of bifenthrin to aquatic
organisms for various indoor uses of the chemical that could potentially
end up in a domestic wastewater “drain” is depicted in Fig. 6.2. 
The stressor is the chemical of concern, bifenthrin.  It is noted that
the transport pathway is wastewater flow, the exposure media is the
treatment facility that discharges into a surface water body of water
(where it may undergo dilution), and the exposure point or route,
receptor and attribute changes for aquatic organisms are similar to the
conceptual model for agricultural applications.

Figure 6.2.  Conceptual model for potential risks of bifenthrin to
aquatic organisms for various indoor uses of the chemical that could
potentially end up in the “drain”

 



7.        Analysis Plan 

 tc \l2 "E.        Analysis Plan 

In order to address the risk hypothesis, the potential for adverse
effects on the environment is estimated.  Usage, environmental fate and
transport, and ecological effects of bifenthrin are characterized and
integrated to assess the risks.  This is accomplished using a risk
quotient (ratio of exposure concentration to effects concentration)
approach.  Although risk is often defined as the likelihood and
magnitude of adverse ecological effects, the risk quotient-based
approach does not provide a quantitative estimate of likelihood and/ or
magnitude of an adverse effect.  However, as outlined in the Overview
Document (USEPA 2004), the likelihood of effects to individual organisms
from particular uses of a chemical is estimated using the probit
dose-response slope and either the level of concern (discussed below) or
the actual calculated risk quotient value.  

This analysis plan will be revisited and may be revised depending on the
data available in the open literature and the information submitted by
the public in response to the opening of the Registration Review docket.

7.1.	Stressors of Concern

The focus of this assessment is on the parent material, bifenthrin. 
However, the Agency will review open literature to identify degradate(s)
of potential toxicological concern (e.g. 4’-OH-bifenthrin was observed
in certain laboratory studies, and in terrestrial field dissipation
studies).

Toxicity data for environmental mixtures of bifenthrin with other
pesticides (those mixtures occurring in the environment following
application), if available, may be presented as part of the ecological
risk assessment.  Bifenthrin may be applied in tank mixtures with other
products approved for use on registered crops.  It is expected that the
toxic effect of bifenthrin, in combination with other pesticides used in
the environment, is likely to be a function of many factors including,
but not necessarily limited to: (1) the exposed species, (2) the
co-contaminants in the mixture, (3) the ratio of bifenthrin and
co-contaminant concentrations, (4) differences in the pattern and
duration of exposure among contaminants, and (5) the differential
effects of other physical/ chemical characteristics of the receiving
waters (e.g. organic matter present in sediment and suspended water). 
Quantitatively predicting the combined effects of all these variables on
mixture toxicity to any given taxa with confidence is beyond the
capabilities of the available data and methodologies.  However, a
qualitative discussion of implications of the available pesticide
mixture effects data on the confidence of risk assessment conclusions
will be addressed as part of the uncertainty analysis.  A discussion of
implications of the available pesticide mixture effects data on the
confidence of risk assessment conclusions will be addressed in the risk
description of the final ecological assessment.

7.2.	Measures of Exposure

In order to estimate risks of bifenthrin exposures in aquatic and
terrestrial environments, all exposure modeling and resulting risk
conclusions will be made based on maximum application rates for the
current use patterns.  Available monitoring data will also be considered
when describing potential environmental exposure to non-target
organisms.

Measures of exposure are based on aquatic and terrestrial models that
predict estimated environmental concentrations of bifenthrin using
maximum labeled application rates and methods, as well as any mitigation
measures specifically indicated on the label.  The models used to
predict aquatic EECs are the Pesticide Root Zone Model coupled with the
Exposure Analysis Model System (PRZM/EXAMS).  Also, to estimate exposure
related to releases of bifenthrin from domestic wastewater treatment
plants, the Exposure and Fate Assessment Screening Tool’s (E-FAST2)
down-the-drain module will be used.  The model used to predict
terrestrial exposure is T-REX.  The model used to derive EECs relevant
to terrestrial and wetland plants is TerrPlant.  The potential for
bioaccumulation for the chemical is assessed using the KABAM model, as
well the results from bioconcentration in fish studies (the
bioconcentration factors).  These models are parameterized using
relevant reviewed registrant-submitted environmental fate and transport
data, including information on biotransformation rates by aquatic biota.

PRZM (v.3.12.2, May 2005) and EXAMS (v.2.98.4.6, April 2005) are
screening simulation models coupled with the input shell PE5.pl (August,
2007) to generate daily exposures and 1-in-10 year EECs of bifenthrin,
that may occur from spray drift and runoff to surface water bodies
adjacent to application sites.   PRZM simulates pesticide application,
movement and transformation on an agricultural field and the resultant
pesticide loadings to a receiving water body via runoff, erosion and
spray drift.  The EXAMS model simulates the fate of the pesticide and
resulting concentrations in the water body.  The standard scenario used
for ecological pesticide assessments assumes application to a 10-hectare
agricultural field that drains into an adjacent 1-hectare water body
that is 2 meters deep (20,000 m3 volume) with no outlet.  PRZM/ EXAMS is
used to estimate screening-level exposure of aquatic organisms to
bifenthrin and/ or its transformation products, should they be of
concern.  The measure of exposure for aquatic species is the 1-in-10
year return peak or rolling mean concentration.  The 1-in-10 year peak
is used for estimating acute exposures of direct effects to aquatic
organisms. The 1-in-10-year 60-day mean is used for assessing chronic
exposure to fish and aquatic-phase amphibians. The 1-in-10-year 21-day
mean is used for assessing aquatic invertebrate chronic exposure.

Given the aquatic toxicity of bifenthrin and its likelihood to occur in
sediment, the Agency will also consider the potential exposures
resulting from benthic/ sediment concentrations (EECs).  Pore water
concentrations are commonly used to predict toxicity of non-ionic
substances in sediments and characterize exposure to organisms that
spend time in or near sediments (Di Toro et al. 1991; US EPA 2002). 
PRZM/ EXAMS estimates 1-in-10-year peak and 21-day mean EECs for pore
water.

At the present time, EFED considers the use of the impervious scenario
(a PRZM modeling scenario) as the most suitable available modeling
approach for impervious runoff.  The PRZM impervious scenario may be
used in the tier 2 coupled aquatic models PRZM/EXAMS along with a
residential or other appropriate scenario such as rights-of-way (ROW) to
obtain EECs.  The conceptual model for the residential scenario
integrates simultaneous modeling of the individual use scenario with an
impervious scenario.  This approach assumes that no watershed is
completely covered by either the ¼ acre lot (the basis for the
residential scenario) or undeveloped land (the basis for the ROW
scenario) for residential and ROW use patterns; therefore, differential
amounts of runoff will occur within the watershed.  The impervious
scenario was developed to represent the paved areas within a watershed
not including roads, parking lots, sidewalks, and buildings outside the
¼ acre lot (the ¼ acre lot scenario accounts for impervious surfaces
such as buildings within the represented area).  By modeling a separate
scenario for impervious surfaces, it is also possible to estimate that
amount of exposure that could occur when the pesticide is oversprayed
onto this surface.  Using two scenarios in tandem requires
post-processing of the modeled output in order to derive a weighted EEC
that represents the contribution of both the pervious (i.e., residential
and ROW scenarios) and the impervious surfaces.  A Microsoft Excel
spreadsheet has been developed that allows for the weighting and
aggregation of exposure from both scenarios.  The daily time series from
each model run should be copied from the times series file (NAME_TS.out)
generated from the PRZM graphical user interface (PE5.pl) into the
spreadsheet provided.  The time series data are then weighted based on
percentage of impervious surface, the percentage of the pervious surface
treated, and an adjusted time series is created.  Rolling averages for
the relevant durations of exposure (e.g., 21 day and 60 day averages)
are calculated, and the relevant one-in-ten year return EEC is generated
from these distributions.  

For the purposes of risk assessment it will be assumed that 1% of the
application rate could reach the impervious surfaces surrounding each
residential lot.  This amount of overspray is not based on empirical
data (no publicized studies on this occurrence have been found in the
open literature); however, the assumption is consistent with the
standard assumption of 1% spray drift with ground applications in
ecological risk assessments.  In general, incorporation of impervious
surfaces into the exposure assessment results in increasing runoff
volume in the watershed, which tends to reduce overall pesticide
exposure assuming 1% overspray to the impervious surface.  Alternative
assumptions for percent impervious surfaces, percentage of use site
treated, and percentage of overspray may be considered in order to
characterize the assumptions of the ecological risks assessment in the
context of the individual exposure assessment and risk conclusions.  For
example, previously tested assumptions used in the endangered species
assessments may be considered for characterization (i.e., 10% and 30%
impervious surfaces, 10% lot treated, and 0% and 10% overspray) unless
other relevant values can be determined (i.e., modeling may be completed
for the impervious surface with 0% and 10% overspray to provide lower
and upper bound values).  The results of these alternate modeling
exercises may be discussed in the assessment.

In addition, the impervious surface scenario can be used for other
purposes, such as use sites for which no other scenario exists and the
use is assumed to be represented by an impervious surface.

The Division acknowledges that washoff from impervious surfaces could be
sources of pyrethroids.  Nonetheless, at the present time, the EFED does
not anticipate requiring washoff studies.  These previously described,
and other subsequently published studies will be taken into
consideration at the time of the final environmental risk assessment. 
Furthermore, EFED will consider a pathway identification study being
proposed by the Pyrethroids Working Group (PWG), which will be conducted
per CDPR requirements and of which a draft protocol dated 9/17/2010 was
received.

The Agency has limited use and usage information relevant to urban
exposures and residential uses of pyrethroids, including bifenthrin. 
The Agency intends to use available non-agricultural use and usage data,
such as the Kline database, the California Department of Pesticide
Regulation’s (CDPR) Pesticide Use Reporting Data and Pest Control
Operator’s usage survey, and the Residential Joint Venture Task Force
homeowner survey data (2003), to make certain reasonable assumptions
regarding various applications and information related to
urban/residential use.  Due to the limited data available, exposure to
the environment and uncertainties will be characterized.  Detailed
information on non-agricultural use and usage of pyrethroid products,
specifically bifenthrin, would be useful in order to reduce those
uncertainties for the final environmental risk assessment for
bifenthrin.

To estimate exposure related to releases of bifenthrin to domestic
wastewater treatment, the Agency will rely on the Office of Pollution
Prevention and Toxics (OPPT) model, Exposure and Fate Assessment
Screening Tool (E-FAST, version 2.0, 2007, or EFAST2). From this model,
the Agency used the “Down-the-Drain” module, which is designed for
releases to domestic wastewater treatment. It is suitable for all the
sources of bifenthrin that could potentially be exposed through a
“down-the-drain” scenario. The model provides screening level
estimate concentrations of chemicals in surface water that may result
from household uses and the disposal of consumer products into
wastewater using a few simple input parameters (production volume and
fraction of the chemical removed during wastewater treatment).  The
exposure model available to the Division for wastewater exposures is for
indoor uses only (i.e., “down-the-drain”).  The Agency does not
contemplate to consider exposures due to combined sewer system overflow
at this time.  The non-crop outdoor uses described by the combination of
the impervious and residential or ROW PRZM scenarios run in tandem, as
described above, presumably provide high end estimated exposure
environmental concentrations (EECs).  They describe applications to
pervious and impervious surfaces and the direct exposure to the EXAMS
modeling pond; thus, they are more conservative than exposures due to
combined sewer overflows.

The Agency is actively evaluating the extent to which ecological risk
from bifenthrin via land application of biosolids should be addressed in
its forthcoming environmental fate and ecological risk assessment, and
by extension, any additional data that may be required.  As part of this
evaluation, OPP is working closely with the Office of Water which
regulates land application of biosolids under the Clean Water Act.  

The Agency has also been made aware of the presence of bifenthrin in
compost [email communication from D. Alder, of the California Department
of Pesticide Regulation (CDPR), to Jacqueline Guerry on 01/12/2010]. 
Compost containing turf from golf courses or urban residences that may
be used by organic growers has been found to contain detectable levels
of bifenthrin.  According to the communication, “CDPR has requested a
scoping document from CalRecycle to document further define the problem
that includes: 

1.	The percentage of green waste being received by composters from golf
courses and urban residences.

2.	Documented concentrations of bifenthrin in green waste as reported by
composters, organic-certifying organizations, and/or the California
Department of Food and Agriculture.

3.	Identification of its significant adverse effects.”

The Agency will continue to work with the CDPR, and be aware of this
issue.  This issue is just developing.  Should it be required, the issue
will be discussed either qualitatively or quantitatively in the risk
assessment.

Exposure estimates for terrestrial animals assumed to be in the target
area are derived using the T-REX model (version 1.3.1, 12/07/2006). 
This spreadsheet-based model calculates the residues on avian and
mammalian food items along with the dissipation rate of a chemical
applied to foliar surfaces (for single or multiple applications) in
order to estimate acute and reproductive risk quotients.  T-REX
calculates EECs and risk quotients based on both the upper bound and
mean residue concentrations as presented by Hoerger and Kenaga (1972)
and modified by Fletcher et al. (1994). These concentrations are
determined using nomograms that relate application rate of a pesticide
to residues remaining on dietary items of terrestrial organisms.  For
pesticides such as bifenthrin, which can be applied as a dust, this
includes the amount of pesticide per square foot, used in LD50 per
square foot risk assessment calculations.

  SEQ CHAPTER \h \r 1 EECs for terrestrial plants inhabiting dry and
wetland areas are derived using TerrPlant (version 1.2.2, 12/26/2006). 
This model uses estimates of pesticides in runoff and in spray drift
(assumed to be 0% for granulars) to calculate EECs.  EECs are based upon
solubility, application rate and minimum incorporation depth.

As indicated in Table 3.1 and its associated text in Section 3,
bifenthrin appears to have a potential to bioaccumulate in aquatic
organisms and biomagnify in terrestrial organisms.  The potential for
bioaccumulation of bifenthrin will also be examined in the risk
assessment.  The bioconcentration factors ranged from 2110 (edible) to
8720 (non-edible) and depuration rate is slow (43-53% of the residues
still remaining in the fish after 42 days of depuration, Acc. No.
264642, MRID 163094, 163095).  Bioaccumulation will be assessed using
the results from bioaccumulation in fish studies, as well as the KABAM
model (KOW (based) Aquatic BioAccumulation Model, version 1.0, 2009),
adjusting for biotransformation rates.  KABAM is used to estimate
potential bioaccumulation of hydrophobic organic pesticides in
freshwater aquatic ecosystems and risks to mammals and birds consuming
aquatic organisms which have bioaccumulated these pesticides.

7.3.	Measures of Effect

Ecological effects data are used as measures of direct and indirect
effects to biological receptors.  Data are typically obtained from
registrant-submitted studies or from literature studies identified by
ECOTOX.  The ECOTOX database provides more ecological effects data in an
attempt to bridge existing data gaps.  ECOTOX is a source for locating
single chemical toxicity data and potential chemical mixture toxicity
data for aquatic life (freshwater and saltwater), terrestrial plants,
and wildlife.  ECOTOX was created and is maintained by the USEPA,
Office of Research and Development, and the National Health and
Environmental Effects Research Laboratory's Mid-Continent Ecology
Division.

The acute measures of effect used for animals in this assessment are the
LD50, LC50 and EC50.  LD stands for "Lethal Dose", and LD50 is the
amount of a material, given all at once, that is estimated to cause the
death of 50% of the test organisms.  LC stands for “Lethal
Concentration” and LC50 is the concentration of a chemical that is
estimated to kill 50% of the test organisms.  EC stands for “Effective
Concentration” and the EC50 is the concentration of a chemical that is
estimated to produce a specific effect in 50% of the test organisms. 
Endpoints for chronic measures of exposure for listed and non-listed
animals are the NOAEL/NOAEC and NOAEC.  NOAEL stands for “No
Observed-Adverse-Effect-Level” and refers to the highest tested dose
of a substance that has been reported to have no harmful (adverse)
effects on test organisms.  The NOAEC (i.e.,
“No-Observed-Adverse-Effect-Concentration”) is the highest test
concentration at which none of the observed effects were statistically
different from the control.  The NOEC is the
No-Observed-Effects-Concentration.  For non-listed plants, only acute
exposures are assessed (i.e., EC25 for terrestrial plants and EC50 for
aquatic plants); for listed plants either the NOAEC or EC05 is used.

Information on the potential effects of bifenthrin on non-target animals
is also collected from the Ecological Incident Information System
(EIIS).  The EIIS is a database containing adverse effect (typically
mortality) reports on non-target organisms where such effects have been
associated with the use of pesticides.  Information on incidents
involving avian species is also provided through the Avian Monitoring
Information System (AIMS), which is maintained by the American Bird
Conservancy.  

Where available, sub-lethal effects observed in both
registrant-submitted and open literature studies will be evaluated
qualitatively.  Such effects may include behavioral changes (e.g.,
lethargy and changes in coloration).  Quantitative assessments of risks,
though, are limited to those endpoints that can be directly linked to
the Agency’s assessment endpoints of impaired survival, growth and
reproduction.

In absence of data on terrestrial-phase amphibians and reptiles, t  SEQ
CHAPTER \h \r 1 he assessment of risk from direct effects to non-target
organisms makes the assumption that the toxicity of bifenthrin to birds
is similar to terrestrial-phase amphibians and reptiles.  The same
assumption is made for fish and aquatic-phase amphibians in the absence
of aquatic-phase amphibian data. 

7.4.	Integration of Exposure and Effects

Risk characterization is the integration of exposure and ecological
effects characterization to determine the potential ecological risk from
the use of pesticides and the likelihood of direct and indirect effects
to non-target organisms in aquatic and terrestrial habitats.  The
exposure and toxicity effects data are integrated in order to evaluate
the risks of adverse ecological effects on non-target species.  For the
assessment of risks, the risk quotient (RQ) method is used to compare
exposure and measured toxicity values.  EECs are divided by acute and
chronic toxicity values.  The resulting RQs are then compared to the
Agency’s Levels of Concern (LOCs) (USEPA 2004).  These criteria will
be used to indicate when bifenthrin’s uses, as directed on the label,
have the potential to cause adverse direct or indirect effects to
non-target organisms.  In addition, incident data from the EIIS will be
considered as part of the risk characterization.

7.5.	Deterministic and Probabilistic Assessment Methods

The quantitative assessment of risk will primarily depend on the
deterministic point-estimate based approach described in the risk
assessment.  An effort may also be made to further qualitatively
describe risk using probabilistic tools that the Agency has developed. 
These tools have been reviewed by FIFRA Scientific Advisory Panels ( 
HYPERLINK "http://www.epa.gov/scipoly/sap/index.htm" 
http://www.epa.gov/scipoly/sap/index.htm ) and have been deemed as
appropriate means of refining assessments where deterministic approaches
have identified risks.

7.6.	Endangered Species Assessments

Consistent with the Agency’s responsibility under the Endangered
Species Act (ESA), the Agency will evaluate risks to Federally-listed
threatened and/or endangered (listed) species from registered uses of
bifenthrin.  This assessment will be conducted in accordance with the
Overview Document (USEPA 2004), provisions of the ESA, and the
Services’ Endangered Species Consultation Handbook (USFWS/NMFS, 1998).

The assessment of effects associated with the registration of bifenthrin
is based on an action area.  The action area is considered to be the
area directly or indirectly affected by the federal action, as indicated
by the exceedance of Agency Levels of Concern (LOCs) used to evaluate
direct or indirect effects.  The Agency’s approach to defining the
action area under the provisions of the Overview Document (USEPA 2004)
considers the results of the risk assessment process to establish
boundaries for that action area with the understanding that exposures
below the Agency’s defined LOCs constitute a no-effect threshold.  
For the purposes of this assessment, attention will be focused on the
footprint of the action (i.e., the area where bifenthrin application
occurs), plus all areas where offsite transport may result in potential
exposure that exceeds the Agency’s LOCs.  Specific measures of
ecological effect that define the action area for listed species include
any direct and indirect effects and/ or potential modification of its
critical habitat, including reduction in survival, growth, and
reproduction as well as the full suite of sub-lethal effects available
in the effects literature.  Therefore, the action area extends to a
point where environmental exposures are below any measured lethal or
sub-lethal effect threshold for any biological entity at the whole
organism, organ, tissue, and/ or cellular level of organization.  In
situations where it is not possible to determine the threshold for an
observed effect, the action area is not spatially limited and is assumed
to be the entire United States.

Probit Analysis

Analysis of raw data from the aquatic acute toxicity studies for
bifenthrin estimate slopes of 3.5 (95% C.I. 2.08 and 4.99) for
freshwater fish, 1.69 (95% C.I. 1.35 and 2.03) for freshwater
invertebrates, and a 4.5 default slope for estuarine/marine fish and for
estuarine/marine invertebrates. Based on these slopes, the corresponding
estimate chance of individual mortality following bifenthrin exposure is
1 in 3.79 x 105 for freshwater fish, 1 in 7.17 x 101 for freshwater
invertebrates, and 1 in 4.18 x 108 for estuarine/marine fish and
invertebrates.

To explore possible bounds to such estimates, the upper and lower values
for the mean slope estimate can be used to calculate upper and lower
estimates of the effects probability associated with the listed species
LOC. These values are 1 in 2.94 x 102 to 1 in 2.36x1010 for freshwater
fish and 1 in 2.53 x 101 to 1 in 2.42 x 102 for freshwater
invertebrates.

Currently, EFED does not assess risk to non-target insects.  Results of
acceptable studies are used for recommending appropriate label
precautions.  Based on the results of a single study in honey bees (LD50
of 0.015 μg a.i./bee), bifenthrin is classified as highly toxic on an
acute contact basis. This study suggests that the acute toxicity to
non-target beneficial endangered insects may also be of concern should
exposure actually occur.

  SEQ CHAPTER \h \r 1 Toxicity data are not available for terrestrial
and semi-aquatic plants; thus, risks associated with bifenthrin exposure
to terrestrial plants cannot be assessed.  Furthermore, a review of
bifenthrin’s mode of action (neural toxin) suggests that direct
toxicity to plants should not be an issue of concern.  However, these
studies are required under the new guidelines.

7.7.	Drinking Water Assessment

A drinking water assessment will be conducted to support future human
health risk assessments of bifenthrin should it be required. The
drinking water assessment will incorporate model estimates of bifenthrin
in surface and ground waters.  Concentrations in surface waters will be
estimated using FQPA Index Reservoir Screening Tool (FIRST, v.1.1.1,
12/18/07) (or subsequently using PRZM/ EXAMS, with the Index Reservoir -
see description above, if refinements are required).  Ground water
estimates of concentrations will be estimated using the Screening
Concentration in Ground Water (SCI-GROW) model (v.2.3, July 2003).  The
drinking water assessment will also include a summary of available
surface and ground water monitoring data.

7.8.	Endocrine Disruptor Screening Program

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

 

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

Bifenthrin is among the group of 58 pesticide active ingredients on the
initial list to be screened under the EDSP. The Agency will review the
EDSP Tier 1 data and any “other scientifically relevant information”
submitted in response to test orders.  Based on this review the Agency
will determine the need for additional testing.  For further information
on the status of the EDSP, the policies and procedures, the list of 67
chemicals, the test guidelines and the Tier 1 screening battery, please
refer to the following website:    HYPERLINK "http://www.epa.gov/endo/" 
http://www.epa.gov/endo/  .

7.9.	Preliminary Identification of Data Gaps

The California Department of Pesticide Regulation (CDPR) placed
bifenthrin and other synthetic pyrethroids into reevaluation in 2006. 
Certain data requirements were imposed to those pyrethroids.  EPA is
already in communication with CDPR and their data should also be
submitted to the Agency.  More information on the CDPR reevaluation
program for pyrethroids at   HYPERLINK
"http://www.cdpr.ca.gov/docs/registration/reevaluation/chemicals/pyrethr
oids.htm" 
http://www.cdpr.ca.gov/docs/registration/reevaluation/chemicals/pyrethro
ids.htm  .

7.9.1.	Fate

After evaluation of the available data for bifenthrin, the following are
the data gaps for registration review:

835.2120 Hydrolysis – The available study was performed in the
presence of high levels of cosolvent acetonitrile (around 7%; maximum
allowed 1% v/v) and at high concentrations (0.5 and 5.2 ppm vs. the
solubility of bifenthrin is 0.014 ppb; thus the test was performed at
>35,000X the solubility limit of bifenthrin).  There was evidence of
precipitation during the test.  According to the authors, bifenthrin was
stable to hydrolysis at a pH range of 5 to 9.  It is unknown if the
presence of the cosolvent, or the extremely high concentrations could
have affected or confounded the study results. According to the OPPTS
835.2120 guideline, “In case a higher concentration of solvents is
considered (e.g., in the case of poorly soluble test substances), this
could only be allowed when it can be shown that the solvent has no
effect on the hydrolysis of the test substances.”  The registrant
should address the Agency’s concern, or a new study is required.

835.2240 Aqueous Photolysis – The available study was performed in the
presence of high levels of cosolvent acetonitrile (around 30%).  Also,
the samples were not buffered and the studies were performed at above
the solubility limit (at 1 ppm vs. the solubility of 0.014 ppb).  The
study indicates that bifenthrin was stable to aqueous photolysis in
natural sunlight.  It is unknown if the presence of the cosolvent could
have affected the study results.  In the same study, using artificial
light, bifenthrin degraded with a reported half-life of 11.9 days and in
sensitized (acetone) solution it was 0.31 days.  There is a high level
of uncertainty with respect to the levels of photolysis.  A new study is
required.  The EFED may waive the requirement of a cosolvent
concentration of ≤1% by volume provided that the registrant submits
the following:

The UV/Vis spectrum for bifenthrin in buffered solution (preferred at pH
5): this will allow the Agency to determine bifenthrin’s potential for
aqueous photolysis.

Information confirming that efforts have been made to improve the
analytical methods for the parent and possible transformation products.

Evidence that acetonitrile (or the cosolvent chosen) does not sensitize
bifenthrin, causing the rate of photolysis to increase.

Proof that the lowest feasible concentration of the cosolvent was used.

835.4100 Aerobic Soil Metabolism – A study performed in one soil
should be submitted.  At this time the Agency has studies performed in
three soils; however, the studies lasted 120 days for the alcohol label
and 180 days for the cyclopropyl label.  According to test OPPTS
Guideline 835.4100 & 835.4200, studies are required in a total of four
soils.  The registrant should monitor the volatiles, which were not
monitored in the previous studies, and there is uncertainty about their
relevance.

835.4200 Anaerobic Soil Metabolism – The available study was performed
with only one soil and for a period of roughly 2 months of anaerobic
incubation.  Anaerobic studies with one soil type are generally
sufficient for the evaluation of transformation pathways. Rates of
transformation should be determined in at least three additional soils
(from Fate, Transport and Transformation Test Guidelines – OPPTS
Guideline 835.4100 & 835.4200).  The study indicates that after the soil
was flooded (converted to anaerobic), the metabolism was very low.  Data
performed for a longer period of time will help the Agency to determine
rates of transformation and presence of possible metabolites.  The
registrant should monitor closely the volatiles, for which there is
uncertainty about their relevance.

835.4300 Aerobic Aquatic Metabolism – No study has been submitted. 
The study is required.  The registrant should monitor the volatiles, for
which there is uncertainty about their relevance.

835.4400 Anaerobic Aquatic Metabolism – No study has been submitted. 
The study is required.  The registrant should monitor the volatiles, for
which there is uncertainty about their relevance.

 ≥ 100,000; FAO Mobility Classification).  A new study is required.

Environmental Chemistry Methods (ECMs), and Independent Laboratory
Validations (ILVs), for Soil, Water and Sediment.  ECMs associated with
the Terrestrial Field Dissipation study (Field dissipation §158.1300;
OPPTS guidelines 835.6100, 835.6200, and 835.6300), along with
successful confirmatory method trials (validation) by an independent
laboratory (i.e. ILVs), are required.  If there is risk concern for a
given taxon, ECMs should be available for the environmental media in
which organisms of the taxon reside.  These ECMs should have limits of
quantization for the residues of concern that are lower than the
relevant toxicological levels of concern.  Previous reviews on
bifenthrin indicate that there is high concern for acute and chronic
aquatic toxicity.  Certain scenarios may have triggered acute and
chronic levels of concern for freshwater and/ or estuarine/ marine
aquatic invertebrates and/ or for fish.  In addition, the latter risk
assessments conducted on bifenthrin, indicated risk concerns for
organisms living in the benthos.  Therefore, ECMs for water and sediment
are required in addition to the ECM for soil.  The ECMs should include
parent and those residues found in the laboratory studies that exceeded
10% of the applied.  Based on the available data at this time, the
following appear to be the residues of concern for each media, but this
could change, based upon the results of the other environmental fate
studies.

Soil, Water and Sediment – parent only:

The registrant is encouraged to submit state-of-the-art environmental
chemistry methods; further, multi-residue methods (MRMs) for soil, water
and sediment are preferred, if applicable.  The registrant submitted one
method for soil (MRID 41673103, LOQ and LOD unknown, published in the
Agency’s ECM website) is available, that could quantify bifenthrin and
its metabolite 4’-hydroxy-bifenthrin (4’-OH-bifenthrin) in soil; the
standard solutions were at 0.1 ng/µL and the fortified soil control
samples had 0.05 – 0.1 ppm of each analyte.  These levels of
quantization may not be appropriate.  Also, the studies MRID 47053001
and 47053002 will be evaluated for its suitability.  A full description
of the method validation procedures performed by an independent
laboratory should also be submitted.  It should include the following
information (Corbin et al. 2006): (a) Recovery level(s) of the test
compound(s) from the soil, water and sediment (substrates) at various
relevant fortification level(s) using the residue analytical
methodology; (b) a validated method sensitivity level; (c) results of
the study and statistical test applied, including a stepwise
presentation of the procedure for calculating percent recovery from the
raw data; (d) all the data/ information necessary to independently
verify the results; (e) summary of the results; and, (f) discussion and
conclusions of the results.

Other data needs:

Leachability from Treated Wood – A study was required in a previous
review document (D290992, 03/09/05) and two studies were submitted
(MRIDs 47454101 and 47454102).  One study was conducted based on the
American Wood Preservers Association Standard Method of Determining the
Leachability of Wood Preservatives (E11-97) and the other was conducted
according to an OECD proposed guideline Estimation of Emissions from
Preservative – Treated Wood to the Environment (currently assigned
guideline number 313).  These studies are currently in review.  This
data requirement is considered unfulfilled until the studies are
reviewed and deemed acceptable.

POTW Effluent Monitoring – Request any existing or ongoing POTW
effluent monitoring data for the pyrethroids be submitted to the Agency.

POTW Treatability Study – The Agency has recently requested and
provided comments on a protocol developed by the Pyrethroid Working
Group (PWG) for a bench scale study of waste water treatment, to assess
the percentage removed in the biosolids by the treatment, the amount
that would degrade during treatment, and the amount that would remain in
the waste water.   These data would be used to inform removal
percentages by waste water treatment, which is an input to the Exposure
and Fate Assessment Screening Tool’s (E-FAST) down-the-drain module.  
The Office of Pesticide Programs will continue to confer with the Office
of Water with the goal of refining our down-the-drain assessment for
registration review.  It is the responsibility of the registrant to
ensure that bifenthrin is included in the study completed by the PWG or
conduct a similar study on their own (following submission of a protocol
for review).

The Agency received comments from stakeholders with concerns regarding
the value of a POTW Treatability Study and its representativeness of
numerous treatment plant designs.  EFED recognizes that such differences
in plant design and operation may affect removal efficiencies, which is
why it is proposing to require a POTW treatability study for bifenthrin,
to support its EFAST2 down-the-drain modeling.  EFED is currently
working with the registrant on the design of this study to best meet the
Agency’s environmental risk assessment needs.  Part of the design of
this study will need to address factors that the commenters present
(i.e., the effect of differences in POTW design and operation on removal
efficiencies) to the extent practicable.  This may involve differences
in experimental conditions and/ or the use of POTW simulation models to
address these concerns.  The ability to extrapolate the bench scale
results to results from available POTW monitoring data will also be
evaluated.  The forthcoming environmental risk assessment would address
the uncertainty involved in the interpretation and extrapolation of
results from the POTW treatability study to the national scale.

The Agency is actively evaluating the extent to which ecological risk
from bifenthrin via land application of biosolids should be addressed in
its forthcoming environmental fate and ecological risk assessment, and
by extension, any additional data that may be required.  As part of this
evaluation, OPP is working closely with the Office of Water which
regulates land application of biosolids under the Clean Water Act.

EFED is unaware of any studies that suggest inhibition of POTW treatment
processes is a significant risk due to documented pyrethroid exposures. 
Furthermore, EFED considers effects on POTW treatment processes to be
beyond the scope of its environmental risk assessments.

Table 7.1 lists the status of the environmental fate data requirements
for bifenthrin.

Table 7.1. Summary of Environmental Fate Data Requirements for
Bifenthrin  SEQ CHAPTER \h \r 1 

Study Identification	

Use

Pattern1	Does EPA Have

Data To Satisfy

This Requirement?	Bibliographic Citation	Must Additional Data Be
Submitted Under FIFRA 3(c)(2)(B)?

§158.1300 ENVIRONMENTAL FATE

Degradation Studies-Lab:

835.2120  Hydrolysis	1,2	Yes	251728 (132539)	Yes2

835.2240  Photodegradation in Water	1,2	Yes	

264642 (163084)	Yes2

835.2410  Photodegradation on Soil	1,2	Yes	

ACC: 264642 or MRID 163085	No

835.2370  Photodegradation in Air	1,2	No	Not Available	Reserved3

Metabolism Studies-Lab:

835.4100  Aerobic Soil	1,2	Yes	

073174, 073225, 141502, 251278, 251728, 254401, 254411, 532540	Yes4

835.4200  Anaerobic Soil	1,2	Yes	

Acc. No. 264642 or MRID 163088	Yes

835.4400  Anaerobic Aquatic	1,2	No	Not Available	Yes

835.4300  Aerobic Aquatic	1,2	No	Not Available	Yes

Mobility Studies:

835.1230  Leaching – Adsorption/ Desorption	1,2	Yes	

251728, 254411	Yes

835.1410  Volatility (Lab)	1,2	Yes	

41220601	No

835.8100  Volatility (Field)	1,2	No	Not Available	Reserved3

Dissipation Studies-Field:

835.6100  Terrestrial Field Dissipation	1,2	Yes	

264642, 42339203, 42339201, 42334167, 41673103, 41676101, 41671302	No

835.6200  Aquatic Field Dissipation	1,2	Yes	40981803, 40981805,
40981808, 40981812, 40981814, 40981815, 40981816, 40981817, 40981818,
40981819	No

835.6300   Forestry Dissipation	1,2	No	Not Applicable	N/A

Ground Water Monitoring Studies:

835.7100  Ground Water Monitoring	1,2	No	NA	Reserved

§158.1100  SPRAY DRIFT

201-1  Droplet Size Spectrum	1,2	No	Not Available	No5

202-1  Drift Field Evaluation	1,2	No	Not Available	No5

Other Studies:

Environmental Chemistry Methods (ECMs) and Independent Laboratory
Validations (ILVs)	1,2	Partially	41673103,

47053001, 47053002	Reserved6

Leachability from Treated Wood	1.2	Yes	47454101, 47454102	Reserved6

1.  Use Patterns: 1=Terrestrial/Food; 2=Terrestrial/Feed.

2.  The studies were conducted in the presence of acetonitrile and other
problems were observed.  New studies are required.

3.  Reserved pending evaluation of the results of the volatiles from all
the laboratory metabolism studies.

4.  One study is required, conducted in one soil; the registrant should
monitor the volatiles in this study, since this was not done in any of
the available studies and there is uncertainty as to their relevance.

5.  Data requirement covered by submission of the Spray Drift Task
Force.

6.  Reserved pending evaluation of two available studies.



7.9.2	Effects

For registration review, the following studies are being requested to
fulfill any data gaps:

Bifenthrin is part of the Endocrine Disruptor Screening Program; certain
data has been required for the chemical under the program (DCI on
11/19/09; 90-day response by 02/27/10).  Please, refer to the website:  
HYPERLINK "http://www.epa.gov/endo/"  http://www.epa.gov/endo/ .

Study Title:  Endocrine Disruptor Screening Program

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

 

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

Bifenthrin is among the group of 58 pesticide active ingredients on the
initial list to be screened under the EDSP. The Agency will review the
EDSP Tier 1 data and any “other scientifically relevant information”
submitted in response to test orders.  Based on this review the Agency
will determine the need for additional testing.  For further information
on the status of the EDSP, the policies and procedures, the list of 67
chemicals, the test guidelines and the Tier 1 screening battery, please
visit our website:    HYPERLINK "http://www.epa.gov/endo/" 
http://www.epa.gov/endo/  .

Guideline Number: 850-2100

Study Title:  Passerine Acute Avian Oral  

Although an acute avian oral study was received for both the Mallard
duck and Bobwhite quail, the Agency updated its data requirements in 40
CFR Part 158 (October 26, 2007) to include an acute oral toxicity study
for both a passerine species and either a waterfowl or an upland game
species.  Prior to starting toxicity testing, a protocol will need to be
provided for review. Many passerine species utilize agricultural fields,
forests, residential areas and surrounding areas, and, therefore, have
the potential to be exposed to pesticides used in agricultural, forest,
and residential settings. It is likely that, for most pesticide use
patterns, passerines are more likely to be exposed to pesticides than
upland game species and waterfowl. Passerines are smaller in size and
generally have faster metabolisms than the waterfowl and upland game
bird species traditionally used in avian toxicity tests which could
impact their sensitivity to chemicals.

Guideline Number: 850-1400

Study Title: Fish Early Life Stage (Saltwater)

No acceptable chronic studies for bifenthrin have been submitted for
marine fish . The acute toxicity of bifenthrin to estuarine/marine fish
and environmental fate properties indicate the potential for chronic
exposure and effects to animals in this taxon, per 40 CFR Part 158 data
requirements (October 26, 2007). For example, the acute LC50 for
freshwater fish (0.15 μg ai/L) is well below the 1.0 mg/L criterion
specified in 40 CFR Part 158 for conditionally requiring this study. 
Furthermore, the persistence of bifenthrin in water is expected to
substantially exceed the 4-d half life criterion.  Without this study,
the Agency would have to presume chronic risk to listed and non-listed
estuarine/marine fish, but would not be able to quantify the risk.

Guideline Number: 850-1500

Study Title: Fish Full Life Cycle

The need for a full life cycle chronic toxicity test of bifenthrin to
fish is indicated based on its aquatic toxicity and environmental fate
properties per 40 CFR Part 158 data requirements (October 26, 2007).
Specifically, a fish full life cycle study may be conditionally required
when the end use product is expected transported to water from its
intended use site, and if any of the following apply: 

1. The EEC is > 0.1 the NOEC from the fish ELS or invertebrate LC test,
or

2. Studies of other organisms indicate reproductive physiology in fish
may be affected.

For bifenthrin, 60-d EECs in surface water range from 0.017 to 0.10
µg/L based on a recent assessment of new uses on mayhew, soybean and
other crops (D336608; Meléndez and Federoff, 2007).  These EECs clearly
exceed 0.004 µg/L, which is one tenth of the fathead minnow ELS NOAEC
(i.e., 0.004 = 0.1 * 0.04 µg/L MRID 40791301) and the freshwater
invertebrate LC NOAEC (0.0013 µg/L; MRID 41156501).  Furthermore,
adverse effects were observed on Daphnia magna reproduction at 0.003
ug/L, which may indicate that similar reproductive effects are likely to
occur in fish.  

Although a fish full life cycle study was previously submitted to the
Agency and classified as supplemental (MRID 40791301), a recent review
of this study revealed that it is unacceptable based on numerous
deficiencies identified in the study, such as low control survival and
an inadequate number of replicates (D381123; October 14, 2010). 
Therefore, a new fish full life cycle study is required.  Should the
registrant choose to conduct the study on an estuarine/marine fish, then
the additional requirement for an ELS study with estuarine/marine fish
could be satisfied with just one study.

Guideline Number: 850-1350

Study Title: Aquatic Invertebrate Life Cycle (Estuarine/marine)

The need for a life cycle chronic toxicity of bifenthrin to
estuarine/marine invertebrates is indicated based on its aquatic
toxicity and environmental fate properties per 40 CFR Part 158 data
requirements (October 26, 2007).   The preferred test species is
Americamysis bahia. Specifically, bifenthrin is intended for use such
that its presence in estuarine/marine environment in significant
concentrations is expected.  In addition, the acute LC/EC50 for
bifenthrin (e.g., 1.6 µg/L for Daphnia magna, is substantially lower
than the 40 Part 158 trigger value of 1 mg/L.  Previous risk assessments
have indicated that the aquatic EECs are > 0.01 of the acute LC/EC50
values for bifenthrin, which is another condition for triggering an
estuarine/marine invertebrate life cycle study.  Finally, it is noted
that the acute toxicity of estuarine/marine invertebrates (LC50 of 0.004
µg/L) is nearly three orders of magnitude lower than that for
freshwater invertebrates (EC50 of 1.6 µg/L).  This comparison suggests
that estuarine/marine invertebrates may be particularly sensitive to
bifenthrin.  Information on the chronic toxicity of bifenthrin to
estuarine/marine invertebrates is therefore needed.

Non-Guideline Study

Study Title:  Whole sediment: chronic invertebrates freshwater and
marine

For bifenthrin, available information indicates that benthic organisms
may be exposed via run-off or spray drift applications used in
agricultural, forest, and residential settings. Specifically, the peak
sediment porewater EECs predicted for bifenthrin (0.006 – 0.014 ppb,
for a variety of crops) exceed 0.1 of the acute LC/EC50 (0.004 ppb for
M. bahia), which satisfies one of the criteria for requiring chronic
whole sediment toxicity testing under 40 CFR Part 158.  Further, the
expected half-life of bifenthrin in sediment (observed to be relatively
stable in anaerobic soil metabolism study, and 251-498 days for
anaerobic aquatic metabolism, Gan et al. 2005) is substantially greater
than 40 CFR Part 158 criterion of 10 days.  The third set of trigger
criteria for requiring chronic testing (Kd > 50, or log KOW > 3 or KOC >
1000) is also met for bifenthrin (e.g., Kd values are 992-5430, log KOW
is 6.4, and KOC values are 131,000-275,000).  Finally, the potential for
persistent exposure from bifenthrin in sediment is also indicated by
open literature studies on pyrethroids (Weston et al. 2005, Amweg et al.
2006 and Ding et al. 2010). 

As noted previously, acute and chronic sediment toxicity tests for
freshwater or marine invertebrates have been submitted (MRIDs 465915-02
& -01, respectively) in response to a previous SAP on pyrethroid
sediment toxicity testing.  However, the 28-d chronic whole sediment
toxicity test with L. plumulosus did not include measurement of
reproductive endpoints. and does not satisfy the chronic whole sediment
testing requirements for estuarine/marine invertebrates.

For sediment, studies involving pyrethroids, tests on Hyalella azteca,
Chironomus dilutus, and Leptocheirus plumulosus are requested.  Although
both are freshwater species, Hyalella and Chironomus differ
substantially in their ecological niche (i.e., epibenthic vs. infaunal
species).  Furthermore, Hyalella and Chironomus differ significantly in
their physiology and life history, with Chironomus being the only
sediment test species undergoing metamorphosis and emergence from an
aquatic to a terrestrial life stage.  There is also evidence suggesting
Hyalella is among the more sensitive invertebrates to some pyrethroids
based on water column tests (Anderson et al. 2006, Maund et al., 2002).
Bifenthrin has the potential to enter estuarine/marine water bodies
based on current usuage patterns that include coastal areas. Therefore,
testing is required for Leptocheirus plumulosus, an estuarine/marine
sediment-dwelling invertebrate species.

The Agency has received a chronic whole sediment toxicity test with L.
plumulosus for bifenthrin (MRID 465915-01). This study is currently
under review.  However, it is noted that the 28-d test with L.
plumulosus only included survival and growth endpoints (with no
reproduction data were provided).  Therefore, this test will not satisfy
the Agency’s chronic whole sediment toxicity test requirement for
estuarine/marine invertebrates due to the lack of data on reproduction. 

Guideline Numbers: (OPPTS 850.1010)

Study Title: Aquatic Invertebrate Acute Toxicity (Hyalella azteca)

Available information indicates that the freshwater amphipod, Hyalella
azteca, is substantially more sensitive to pyrethroids than Daphnia
magna, the commonly tested freshwater invertebrate (e.g., Anderson et
al. 2006; Maund et al., 2002).  Information on the acute toxicity of
bifenthrin to H. azteca was not identified in this problem formulation. 
Therefore, in order to ensure that risk to sensitive aquatic
invertebrates are appropriately quantified, additional acute toxicity
testing of H. azteca is needed (water column exposure, not
sediment-spiked).

Guideline Numbers: (OPPTS 850.1035)

Study Title:  TEP Toxicity testing with Aquatic Organisms

Testing on Typical end-use products (TEP)

According to the Part 158 data requirements, testing on the typical
end-use product may be required for aquatic toxicity tests when any of
the following conditions exist: 

	1.  The end-use product will be introduced directly into the aquatic
environment.

2.  The maximum expected environmental concentration or estimated
environmental concentration in the aquatic environment is greater than
or equal to one-half the LC50 or EC50 of the TGAI.

3.  An ingredient in the end-use formulation other than the active
ingredient is expected to enhance the toxicity of the active ingredient
or cause toxicity to aquatic organisms.

Previous assessments indicated that the expected environmental
concentrations of bifenthrin in aquatic environments were based on the
solubility limit in water (0.014 ppb). In freshwater and
estuarine/marine tests conducted with bifenthrin technical, the most
toxic 96-hour LC50s were 0.15 ug/L for rainbow trout, 1.6 ug/L for
Daphnia, 17.5 µg/L for sheepshead minnow and 0.004 µg/L for mysid
shrimp. Therefore, bifenthrin fulfills the second requirement for TEP
testing for estuarine/marine invertebrate species only.

A Typical End-Use Product is defined in the Pesticide Assessment
Guidelines Subdivision J Hazard Evaluation:  Nontarget plants on Part
120-2(1) on Page 18 as “a pesticide product that is representative of
a major formulation category (e.g., emulsifiable concentrate, granular
product, wettable powder) and pesticide group (e.g., herbicide,
fungicide, insecticide etc.) and contains the active ingredient of the
applicant’s product.” (Holst and Ellwanger, 1982)

Page 5 of the Pesticide Assessment Guidelines Subdivision J Hazard
Evaluation:  Nontarget plants provide additional information on what TEP
data should be tested for toxicity testing in the following excerpt.

“The Agency seeks to avoid imposing a burden of duplicative testing on
applicants for registration.  Therefore, where 40 CFR Part 158 specifies
that the test substance should be a representative end-use product,
testing may be performed using the formulation in question (end-use
product being registered) or similar, yet representative, end-use
product.  It is not necessary to repeat the test using other similar
products.” (Holst and Ellwanger, 1982).

When TEP data are requested, data should be submitted for the different
formulations, e.g., wettable powder, emulsifiable concentrate, granular,
along with a rationale as to why the TEP is representative of other
similar end-use products. Acute aquatic toxicity studies conducted with
the Typical End-Use Product (TEP) may be used to assess effects as a
result of exposure to spray drift only and reflect potential effects
from a brief exposure to the formulation. Therefore, appropriate TEPs
should be selected from formulations that are registered for
agricultural uses, not residential.

Guideline Numbers: 850.4150 and 850.4250

Study Title: Vegetative vigor and Seedling emergence, Tier I/II

No acceptable toxicity data are currently available to assess the risk
of bifenthrin to non-target terrestrial plants. Since bifenthrin has
residential outdoor uses, vegetative vigor and seedling emergence
studies are required.  These phytotoxicity data are needed to evaluate
the level of pesticide exposure to non-target terrestrial and aquatic
plants and to assess the impact of pesticides on endangered and
threatened plants.  

Guideline Number: 850.4400

Study Title: Aquatic Vascular Plant Growth-Lemna spp. Tier I/II

No acceptable studies for bifenthrin have been submitted for vascular
aquatic plants. The Agency has finalized its update to the data
requirements in 40 CFR Part 158.  In these updated data requirements,
which were promulgated on October 26, 2007, vascular plant testing is
required for pesticides such as bifenthrin with outdoor uses.

Guideline Number:  850.5400

Study Title:  Algal toxicity test, Tier I/II  

No toxicity data are currently available to assess the risk of
bifenthrin to aquatic nonvascular plants. Since bifenthrin has
residential outdoor uses, Tier I/II aquatic nonvascular plant studies
are required.  These phytotoxicity data are needed to evaluate the level
of pesticide exposure to non-target aquatic plants and to assess the
impact of pesticides on endangered and threatened plants.  

Table 7.2 lists the status of the ecological effects data requirements
for bifenthrin.

Table 7.2. Ecological Effects Data Requirements for Bifenthrin



Data Requirement	

Use

Pattern1	Does EPA Have

Data To Satisfy

This Requirement?

(Yes, No, or Partially)	

Bibliographic

Citation	Must Additional

Data Be Submitted

Under FIFRA 3(c)(2)(B)?

§158.490 TERRESTRIAL ORGANISMS

71-1(a)   Acute Avian Oral, Quail/Duck 	1,2	Partially	ACC251727
Fletcher/1984	Yes1

71-2(a)   Acute Avian Diet, Quail              	1,2	Yes	ACC251727
Fletcher/1984	No

71-2(b)   Acute Avian Diet, Duck              	1,2	Yes	ACC251727
Fletcher/1984	No

71-3       Wild Mammal Toxicity               	1,2	N/A

71-4(a)   Avian Reproduction Quail	1,2	Yes	ACC264644

Huntington/1987	No

71-4(b)   Avian Reproduction Duck          	1,2	Yes	ACC264644

Huntington/1987	No

§158.630  AQUATIC ORGANISMS TESTING

72-1(a)   Acute Fish Toxicity Bluegill         	1,2	Yes	ACC 251727

Hoberg 1983	No

72-1(b)   Acute Fish Toxicity (TEP)	1,2	No	N/A	No*

72-1(c)   Acute Fish Toxicity Rainbow  Trout          	1,2	Yes	ACC
251727

Hoberg 1983	No

72-2(a)   Acute Aquatic Invertebrate           	1,2	Yes	41156501	No

72-2(b)   Acute Aquatic Invertebrate   (TEP)         	1,2	No	N/A	No*

72-3(a)   Acute Est/Mar Toxicity Fish         	1,2	Yes	264646

Battelle 1987	No

72-3(b)   Acute Est/Mar Toxicity Mollusk    	1,2	Yes	40383501	No

72-3(c)   Acute Est/Mar Toxicity Shrimp    	1,2	Yes	264647

Battelle 1987	No

72-3(d)   Acute Est/Mar Toxicity Fish (TEP)	 	1,2	No	N/A	No*

72-3(e)   Acute Est/Mar Toxicity Mollusk  (TEP)  	1,2	No	N/A	No*

72-3(f)   Acute Est/Mar Toxicity Shrimp  (TEP)  	1,2	No	N/A	Yes

72-4(a)   Early Life Stage Fish                  	1,2	No (Saltwater)	N/A
Yes

72-4(b)   Life Cycle Aquatic Invertebrate (freshwater) 	1,2	Yes	41156501
No

850.1350  Life Cycle Aquatic Invertebrate (saltwater)	1,2	No	N/A	Yes

72-5   Life Cycle Freshwater Fish         	1,2	No	40791301	Yes3

72-6   Aquatic Organism Accumulation	1,2	N/A

72-7(1)   Simulated Aquatic Field Study	1,2	N/A

72-7(b)   Actual Aquatic Field Study	1,2	N/A

850.1730  Bioaccumulation in Fish	1,2	Yes	264642 ( 163094, 163095)	No

850.1950  Accumulation in Aquatic Non-target Organisms	1,2	Yes	42529902
Study currently in review

850.1010  Aquatic Invertebrate Acute Toxicity (Hyalella azteca)	1, 2	No
NA	Yes

850.1735 Whole sediment:  acute freshwater invertebrates (C. dilutus)	1,
2	Yes	46591502	Study currently in review

850.1740 Whole sediment:  acute marine invertebrates	1, 2	No	NA	No2

Whole sediment:  chronic invertebrates freshwater (H. azteca)	1, 2	No	NA
Yes

Whole sediment:  chronic invertebrates freshwater (C. dilutus)	1, 2	No
NA	Yes

Whole sediment:  chronic invertebrates marine (L. plumulosus)	1, 2	Yes
46591501	Yes



§158.540 PLANT PROTECTION

122-1(a) Seed Germ, Seedling Emergence TEP	1,2	No	NA	Yes

122-2     Aquatic Plant Growth	1,2	No	NA	Yes

122-1(b)  Vegetative Vigor TEP	1,2	No	NA	Yes

123-1(a) Seed Germ./Seedling Emerg.	1,2	No	NA	No4

123-1(b) Vegetative Vigor	1,2	No	NA	No4

123-2     Aquatic Plant Growth	1,2	No	NA	No5



§158.490 NONTARGET INSECT TESTING

141-1     Honey Bee Acute Contact           	1,2	Yes	VAOTAL01

Atkins 1981	No

141-2     Honey Bee Residue on Foliage   	1,2	Yes	163104 1986	No

141-5     Field Test for Pollinators	1,2	NA

1 Data are required for one passerine species and either on waterfowl or
one upland game bird species. At this time, only acute oral tests for a
game bird species and a waterfowl have been submitted.

2 This data requirement was previously listed as “held in reserve”.
Based on the requirements listed in 40 CFR Part 158, the persistent
half-life of bifenthrin meets the criteria for chronic whole sediment
tests, not acute. Therefore, only chronic sediment tests are requested
at this time. 

3 This study is classified as invalid based on current review. Previous
studies listed the study as supplemental. Should the registrant choose
to conduct the study on an estuarine/marine fish, then the additional
requirement for an ELS study with estuarine/marine fish could be
satisfied with just one study.

4 Required if a tested terrestrial species exhibits a 25 percent or
greater detrimental effect in the Tier I study.

5 Required if a tested aquatic species exhibits a 50 percent or greater
detrimental effect in a Tier I study.

* Does not trigger submission of TEP data:

According to the Part 158 data requirements, testing on the typical
end-use product may be required for aquatic toxicity tests when any of
the following conditions exist: 

	1.  The end-use product will be introduced directly into the aquatic
environment.

2.  The maximum expected environmental concentration or estimated
environmental concentration in the aquatic environment is greater than
or equal to one-half the LC50 or EC50 of the TGAI.

3.  An ingredient in the end-use formulation other than the active
ingredient is expected to enhance the toxicity of the active ingredient
or cause toxicity to aquatic organisms.

Previous assessments indicated that the expected environmental
concentrations of bifenthrin in aquatic environments were based on the
solubility limit in water (0.014 ppb). In freshwater and
estuarine/marine tests conducted with Bifenthrin technical, the most
toxic 96-hour LC50s were 0.15 ug/L for Rainbow trout, 1.6 ug/L for
Daphnia, 17.5 µg/L for sheepshead minnow and 0.004 µg/L for Mysid
shrimp. Therefore, Bifenthrin fulfills the second requirement for TEP
testing for estuarine/marine invertebrate species only.





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Toxicity of the Pyrethroid Insecticide Cypermethrin in Sediments. 
Environmental Toxicology and Chemistry, 21 (1):9-15.

Matsumura, F. 1985. Toxicology of insects. 2nd ed. Plenum New York.

Meléndez, J.L. and N.E. Federoff.  2005.  EFED Chapter for the New Use
of Bifenthrin (BISTAR® WT) as a Wood Preservative.  Memorandum to S.
Stanton and G. LaRocca dated 3/9/05.  DP Barcode D290992.  Environmental
Fate and Effects Division, OPP, OPPTS, USEPA.

Meléndez, J.L. and N.E. Federoff.  2007.  EFED Science Chapter for the
Section 3 and IR-4 New Uses of Bifenthrin on Mayhew, Vegetable Roots,
Except Sugar Beets, Peanut, Soybean, and Fruiting Vegetables Subgroup B.
 Memorandum to S. Brothers, A. Balexand and G. LaRocca dated 9/27/07. 
DP Barcodes D336608, D336609 and D336610.  Environmental Fate and
Effects Division, OPP, OPPTS, USEPA.

Rexrode, M. and J.L. Meléndez.  2003.  EFED’s rationale for choosing
Cypermethrin, Esfenvalerate, Bifenthrin, and Cyfluthrin for sediment
testing as discussed with the Pyrethroid Working Group (PWG). 
Memorandum to M. Johnson & G. LaRocca dated 12/22/03.  Environmental
Fate and Effects Division, OPP, OPPTS, USEPA.

Rexrode, M. and J.L. Meléndez.  2006.  Tolerance Petition for the Use
of Bifenthrin on Leafy Brassica Greens, Peas and Beans (dry), Tobacco,
Cilantro, Okra and Tuberous and Corm Vegetables.   SEQ CHAPTER \h \r 1
Incremental Ecological Effects Risk Assessment Due to the New Uses. 
Memorandum to S. Brothers, S. Jackson, B. Alexander, D. Rosenblatt and
G. LaRocca dated 2/21/06.  DP Barcodes D310879, D310881, D313300,
D313728, D313741, D322221 and D322222.  Environmental Fate and Effects
Division, OPP, OPPTS, USEPA.

Stout II, D.M., K Bradham, P.P. Egeghy, P. Jones, C.W. Croghan, P.A.
Ashley, E. Pinzer, W. Friedman, M.C. Brinkman, M.G. Nishioka and D.C.
Cox.  2009.  American Healthy Homes Survey: A National Study of
Residential Pesticides Measured from Floor Wipes.  Environ. Sci.
Technol., 2009, 43, 4294–4300.

Trimble, A.J, D.P. Weston, J.B. Belden, and M.J. Lydy.  2009. 
Identification and Evaluation of Pyrethroid Insecticide Mixtures in
Urban Sediments.  Environ Toxicol & Chem 26 (8) pp. 1687–1695  (from
ET&C paper in press).

U.S. Environmental Protection Agency.  1998.  Guidelines for Ecological
Risk Assessment.  Risk Assessment Forum, Office of Research and
Development,  Washington, D.C.  EPA/630/R-95/002F.  April 1998.

U.S. Environmental Protection Agency. 1999. FIFRA Scientific Advisory
Panel Meeting, February 23, 1999 held at the Holiday Inn Hotel,
Arlington, VA. SAP Report No. 99-03A. March 25, 1999. Office of
Pesticide Programs. Available at url:   HYPERLINK
"http://www.epa.gov/scipoly/sap/meetings/1999/022399_mtg.htm#materials" 
http://www.epa.gov/scipoly/sap/meetings/1999/022399_mtg.htm#materials 
(Accessed December 15, 2009) 

U.S. Environmental Protection Agency.  2000.  Risk Characterization
Handbook.  Science Policy Council, U.S. Environmental Protection Agency,
Washington, D.C.  20460.  EPA 100-B-00-002.  December 2000.

U.S. Environmental Protection Agency. 2002. Technical Basis for the
derivation of Equilibrium Partitioning Sediment Guidelines (ESGs) for
the Protection of Benthic Organisms: Nonionic Organics [Draft].  EPA
Document No. 822R02041. October 2002.

U.S. Environmental Protection Agency.  2004.  Overview of the Ecological
Risk Assessment Process in the Office of Pesticide Programs, U.S.
Environmental Protection Agency.  Endangered and Threatened Species
Effects Determinations.  Office of Prevention, Pesticides and Toxic
Substances, Office of Pesticide Programs, Washington, D.C.  January 23,
2004.

U.S. Environmental Protection Agency.  2005.  Generic Format and
Guidance for the Level I Screening Ecological Risk Assessments Conducted
in the Environmental Fate and Effects Division.  Office of Pesticide
Programs, Washington, D.C.  January 24, 2005.

U.S. Environmental Protection Agency. 2008. OPPTS 835.6100 Terrestrial
Field Dissipation. EPA 712-C-08-020. October 2008. Office of Prevention,
Pesticides, and Toxic Substances.  United States Environmental
Protection Agency. Available at   HYPERLINK
"http://www.epa.gov/opptsfrs/publications/835_6100.pdf" 
http://www.epa.gov/opptsfrs/publications/835_6100.pdf  (Accessed
December 16, 2009).

U.S. Environmental Protection Agency. 2009.  A Set of Scientific Issues
Being Considered by the EPA Regarding: Evaluation of the Common
Mechanism of Action of Pyrethroid Pesticides.  SAP Minutes No. 2009-07. 
FIFRA SAP Meeting held 6/16/09 in Arlington, VA.  Meeting Minutes dated
9/9/09.

U.S. Fish and Wildlife Service (USFWS) and National Marine Fisheries
Service (NMFS).  1998. Endangered Species Consultation Handbook: 
Procedures for Conducting Consultation and Conference Activities Under
Section 7 of the Endangered Species Act.  Final Draft.  March 1998.

Weston, D.P., J. You and M.J. Lydy. 2004.  Distribution and Toxicity of
Sediment-Associated Pesticides in Agriculture-Dominated Water Bodies of
California’s Central Valley.  Environ. Sci. Technol. 2004, 38,
2752-2759.

Weston, D.P., R.W. Holmes, J. You and M.J. Lydy.  2005.  Aquatic
Toxicity Due to Residential Use of Pyrethroid Insecticides.  Environ.
Sci. Technol., 2005, 39 (24), pp 9778–9784.

Weston, D.P. Amweg, E.L., Mekebri, A., Ogle, R.S. and M.J. Lydy. (2006).
Aquatic effects of aerial spraying for mosquito control over an urban
area. Environ. Science Technol. 40(18): 5817-22.

Weston, D.  2007. Impacts of Pyrethroid Pesticides on Water Quality from
Urban and Agricultural Sectors.  Conference Proceedings;  California
Plant and Soil Conference: Opportunities for California Agriculture. 
California Chapter of the American Society of Agronomy, pp. 35-37.

Weston, D.P., J. You, A.D. Harwood and M.J. Lydy. 2009a. Whole Sediment
Toxicity Identification Evaluation Tools for Pyrethroid Insecticides:
III. Temperature Manipulation.  Environ. Tox. & Chem., Vol. 28, No. 1,
pp. 173–180, 2009

Weston, D.P., R.W. Holmes, and M.J. Lydy.  2009b.  Residential runoff as
a source of pyrethroid pesticides to urban creeks.  Environmental
Pollution 157 (2009) 287–294

Weston, D.P. and M.J. Lydy.  2010.  Urban and Agricultural Sources of
Pyrethroid Insecticides to the Sacramento-San Joaquin Delta of
California.  Environ. Sci. Technol. 2010, 44, 1833–1840.

9.	Fate and Eco-Toxicity Bibliography

161-1       Hydrolysis



132518	FMC Corp. (1983) FMC 54800 Insecticide. (Compilation; unpublished
study received Nov 3, 1983 under 279-EX-101; CDL:251725-A) 

132539	Herbst, R.; Kikta, E. (1983) Hydrolysis of FMC 54800: P-0701.
(Un- published study received Nov 3, 1983 under 279-EX-101; submitted by
FMC Corp., Philadelphia, PA; CDL:251728-A) 

152860	FMC Corp. (1984) Chemistry: Environmental Fate [of FMC 54800].
Un- published study. 10 p. 



161-2       Photodegradation-water



163084	Wu, J. (1986) Photodegradation of FMC 54800 in Aqueous Solution:
Rept. No. P-1349. Unpublished study prepared by FMC Corp., Agricultural
Chemical Group. 33 p. 

161-3       Photodegradation-soil



163085	Wu, J. (1986) Photodegradation of FMC 54800 in/on Soil: Rept. No.
P-1351. Unpublished study prepared by FMC Corp., Agricultural Chemical
Group. 38 p. 

162-1       Aerobic soil metabolism



132540	Bixler, T.; Gross, E.; Willow, E.; et al. (1983) FMC 54800
Aerobic Soil Degradation: P-0712. (Unpublished study received Nov 3,
1983 under 279-EX-101; submitted by FMC Corp., Philadelphia, PA;
CDL:251728-B) 

141202	Reynolds, J. (1984) Aerobic Soil Metabolism of FMC 54800 - Fate
of Acid Cyclopropyl ring)-[Carbon 14] FMC 54800 and Metabolite
Characterization: P-0872. Unpublished study prepared by FMC Corp. 22 p. 

152266	Reynolds, J. (1984) Aerobic Soil Metabolism of FMC 54800 - Fate
of Alcohol (Phenyl)-[Carbon-14] FMC 54800 in a Sandy Loam Soil after 21
Days. Unpublished study prepared by FMC Corp. 17 p. 

152860	FMC Corp. (1984) Chemistry: Environmental Fate [of FMC 54800].
Un- published study. 10 p. 

162-2       Anaerobic soil metabolism



163088	Reynolds, J. (1986) Metabolism of Acid (Cyclopropyl Ring)-[carbon
14] and Alcohol(Phenyl Ring-[carbon 14] FMC 54800 in Soil under
Anaerobic Conditions: Rept. No. P-1338. Unpublished study pre- pared by
FMC Corp., Agricultural Chemical Group. 26 p. 

163-1       Leach/adsorp/desorption



132541	Kinne, L.; Froelich, L. (1983) Soil Mobility of FMC 54800:
P-0721. (Unpublished study received Nov 3, 1983 under 279-EX-101; sub-
mitted by FMC Corp., Philadelphia, PA; CDL:251728-C) 

141203	Froelich, L. (1984) Soil Adsorption/Desorption Characteristics of
FMC 54800: P-0797. Unpublished study prepared by FMC Corp. 19 p. 

163089	Kinne, L. (1984) Mobility of FMC 54800 Aged Soil Residues: Rept.
No. P-1029; Study No. S-182-84-19. Unpublished study prepared by FMC
Corp., Agricultural Chemical Group. 21 p. 

163-2       Volatility - lab



163090	Ferraro, C.; Zuccarello, W. (1986) FMC 54800 Laboratory
Volatility Study: The Volatility of Active Ingredient in Capture 2.0 EC
Insecticide/Miticide from Soil under Varying Conditions of Temp-
erature, Soil Moisture and Air Flow Rate: Rept. No. P-1463. Unpublished
study prepared by FMC Corp., Agricultural Chemical Group. 24 p. 

163223	Hu, H. (1983) Vapor Pressure of FMC 54800: Rept. No. CGP-83-1;
Pr. No. G182.305. Unpublished study prepared by FMC Corp., Center
Technical Dept. 17 p. 

41220601	Bowman, B. (1989) Laboratory Volatility from Soil of FMC 54800:
Proj. ID PC 0119. Unpublished study prepared by Analytical Bio-
Chemistry Laboratories. 40 p. 

164-1       Terrestrial field dissipation



163091	Stearns, J. (1984) Dissipation of Residues of FMC 54800 in Soils
Treated with Capture 2.0 EC: Rept. No. RAN-0141. Unpublished study
prepared by FMC Corp., Agricultural Chemical Group. 25 p. 

41673101	Hicks, S. (1990) Bifenthrin Field Dissipation Study .: Lab Pro-
ject Number: 182E4188E1: 882037-1: PC-0147. Unpublished study prepared
by Siemer & Associates, Inc. 383 p. 

41673102	Culligan, J. (1990) Terrestrial Field Dissipation: Magnitude of
the Residue of Bifenthrin and 4'-Hydroxy-Bifenthrin in Soil: Lab Project
Number: 182E4188E1-1. Unpublished study prepared by FMC Corp. 91 p. 

41673103	Stenzel, J. (1990) Interim Report of the Terrestrial Field
Dissipation of Bifenthrin and 4'-Hydroxy-Bifenthrin in/on Bare Soil: Lab
Project Number: 182E4189R1. Unpublished study prepared by FMC Corp. 118
p. 

42339201	Stenzel, J.; Culligan, J. (1991) Final Report of the 1989 Study
of the Terrestrial Field Dissipation of Bifenthrin in/on Bare Soil in
Champaign, Il: Lab Project Number: P-2639: 182E4189R1. Unpublished study
prepared by FMC Corp. 117 p. 

42339203	Culligan, J. (1991) Terrestrial Field Dissipation--Bifenthrin
and 4'-Hydroxy-Bifenthrin in Soil: Lab Project Number: 18234188E1-1.
Unpublished study prepared by FMC Corp. 114 p. 

165-4       Bioaccumulation in fish



163094	Surprenant, D. (1985) Accumulation and Elimination of [Carbon
14]- Residues by Bluegill (Lepomis macrochirus) Exposed to [Carbon
14]-FMC 54800: Rept. #BW-85-4-1765; Bionomics Study #282.1184. 6108.140.
Unpublished study prepared by Springborn Bionomics, Inc. 46 p. 

163095	Tullman, R. (1986) Analysis of [Carbon 14]-FMC 54800 Residues in
Bluegill Sunfish and Water: Rept. No. P-1342. Unpublished study prepared
by FMC Corp., Agricultural Chemical Group. 37 p. 

165-5       Bioaccum-aquatic non-target



42529902	Surprenant, D. (1988) Bioavailability, Accumulation and Aquatic
Toxicity of carbon 14|-FMC 54800 Residues Incorporated into Soil: Lab
Project Number: BW-85-12-1894: 282-0185-6109-000. Unpublished study
prepared by Springborn Bionomics Inc. 87 p. 



NON Guideline Section Selections

46535601	Cheplick, J. (2005) National Runoff, Erosion, and Leaching
Assessment with the Pesticide Root Zone Model (PRZM): Pyrethroid.
Project Number: WEI/794/05. Unpublished study prepared by Waterborne
Environmental, Inc. (WEI). 14 p.

46535602	Cheplick, J. (2005) Direct Observation Based Method to Assign
Topographic Factor (LS) to Areas of Concern with Quantified Statistical
Confidence: (Pyrethroid). Project Number: WEI/794/05. Unpublished study
prepared by Waterborne Environmental, Inc. (WEI). 12 p.

46535603	Holmes, C. (2005) Proposed Methodology to Redistribute Doane
Pesticide Use Data Based on NASS 2002 Census of Agriculture Data:
(Pyrethroid). Project Number: WEI/794/05. Unpublished study prepared by
Waterborne Environmental, Inc. (WEI). 14 p.

46535604	Ritter, A. (2005) Approach for the Monte Carlo Assessment (Task
I) of the Sensitivity Analysis of Synthetic Pyrethroid Sediment Exposure
Assessments to Drift and Runoff Entry Routes. Project Number:
WEI/794/05. Unpublished study prepared by Waterborne Environmental, Inc.
(WEI). 49 p.

47454101	Chen, A. (2007) Determination of Bifenthrin Residues Leaching
from Wood Treated with Bistar WT Insecticide. Project Number:
182WAT07PS01, P/3932. Unpublished study prepared by FMC Corp. 36 p.

47454102	Enriquez, M. (2006) Determination of Bifenthrin Leaching From
Wood Treated with 3% Bifenthrin ME (Wood Preservative Formulation).
Project Number: A/25/05/05. Unpublished study prepared by Battelle
Europe. 52 p.

47506602	Hall, L.; Killen, W.; Anderson, R. (2008) A Comparison of
Sediment Sampling Methods for Pyrethroids in Urban/Residential Sediments
of California Streams and Additional Pyrethroid Sampling in Pleasant
Grove Creek Backwater Surrogate Sites- Pyrethroid: Assessment. Project
Number: T001584/08. Unpublished study prepared by Wye Research and
Education Center. 62 p.

47506603	Hall, L.; Killen, W.; Anderson, R.; et. al. (2008) An
Assessment of Benthic Communities with Concurrent Physical Habitat,
Pyrethroid, and Metals Analysis in an Urban and Residential Stream in
California in 2006 and 2007-Pyrethroid: Assessment. Project Number:
T001523/08. Unpublished study prepared by Wye Research and Education
Center and Northern Illinois University. 229 p.

47647801	Hanzas, J.; Stone, C.; Toth, B.; et al. (2008) Bifenthrin and
Beta-Cyfluthrin: Quantification of Pyrethroid Runoff Losses from Treated
Turfgrass Under Over-Irrigation Conditions and Simulated Rainfall: Final
Report. Project Number: 082018, SEI001. Unpublished study prepared by
Stone Environmental, Inc., CRG Marine Laboraties, Inc. and Agvise
Laboratories. 280 p.

163080	Martin, F. (1985) Storage Stability of Bifenthrin in/on Various
Crops and Soils: Rept. No. P-1268. Unpublished study prepared by FMC
Corp., Agricultural Chemical Group. 23 p. 

163081	Martin. F. (1986) Storage Stability of Bifenthrin in/on Various
Crops and Soils: Rept. No. P-1459. Unpublished study prepared by FMC
Corp., Agricultural Chemical Group. 26 p. 

71-1       Avian Single Dose Oral Toxicity



132532	Fletcher, D. (1983) Report to ...: Acute Oral Toxicity Study with
FMC 54800 Technical in Bobwhite Quail: BLAL No. 83 QD 30; FMC #A83-963.
(Unpublished study received Nov 3, 1983 under 279- EX-101; prepared by
Bio-Life Assoc., Ltd., submitted by FMC Corp., Philadelphia, PA;
CDL:251727-A) 

132534	Fletcher, D. (1983) Report to ...: Acute Oral Toxicity Study with
FMC 54800 Technical in Mallard Ducks: BLAL No. 83 DD 23; FMC #A83-964.
(Unpublished study received Nov 3, 1983 under 279-EX- 101; submitted by
FMC Corp., Philadelphia, PA; CDL:251727-C) 

71-2       Avian Dietary Toxicity



132533	Fletcher, D. (1983) Report to ...: 8-Day Dietary LC50 Study with
FMC 54800 Technical in Bobwhite Quail: BLAL No. 83 QC 34; FMC No.
A83-965. (Unpublished study received Nov 3, 1983 under 279-EX-101;
prepared by Bio-Life Assoc., Ltd., submitted by FMC Corp., Philadelphia,
PA; CDL:251727-B) 

132535	Fletcher, D. (1983) Report to ...: 8-Day Dietary LC50 Study with
FMC 54800 Technical in Mallard Ducklings: BLAL No. 83 DC 34; FMC No.
A83-966. (Unpublished study received Nov 3, 1983 under 279-EX-101;
submitted by FMC Corp., Philadelphia, PA; CDL: 251727-D) 

71-4       Avian Reproduction



163097	Roberts, N.; Phillips, C.; Anderson, A.; et al. (1986) The
Effects of Dietary Inclusion of FMC 54800 on Reproduction in the Bob-
white Quail: Rept. No. FCC 57A/851423. Unpublished study pre- pared by
Huntingdon Research Centre Ltd. 337 p. 

163098	Roberts, N.; Phillips, C.; MacDonald, I. (1986) The Tissue
Residues of FMC 54800 in the Bobwhite Quail following a Reproduction
Study: Rept. No. FCC 57(b)/851567. Unpublished study prepared by
Huntingdon Research Centre Ltd. 54 p. 

163099	Roberts, N.; Phillips, C.; Anderson, A.; et al. (1986) The Effect
of Dietary Inclusion of FMC 54800 on Reproduction in the Mallard Duck:
Rept. No. FCC 58A/851430. Unpublished study prepared by Huntingdon
Research Centre Ltd. 239 p. 

163100	Roberts, N.; Phillips, C.; MacDonald, I. (1986) The Tissue
Residues of FMC 54800 in the Mallard Duck following a Reproduction
Study. Rept. No. FCC 58(b)/851316. Unpublished study prepared by
Huntingdon Research Centre Ltd. 51 p. 

40266301	Roberts, N.; Phillips, C.; Anderson, A.; et al (1987) The
Effects of Dietary Inclusion of FMC 54800 on Reproduction in the Bob-
white Quail (Revised): Lab Proj. ID FCC 57A/851423 and FCC 57(b) 851567.
Unpublished study revised by Huntington Research Cent- re, Ltd. 368 p. 

72-1       Acute Toxicity to Freshwater Fish



132536	LeBlanc, G.; Hoberg, J. (1983) Acute Toxicity of FMC-54800
Technical to Bluegill ...: Bionomics Report #BW-83-8-1445; FMC Study No.
A83-987. (Unpublished study received Nov 3, 1983 under 279-EX-101;
prepared by EG & G, Bionomics, submitted by FMC Corp., Philadelphia, PA;
CDL:251727-F) 

163156	Hoberg, J. (1983) Acute Toxicity of FMC-54800 Technical to
Rainbow Trout (Salmo gairdneri): FMC Study No. A83-967. Unpublished
study prepared by EG&G Bionomics. 21 p. 

72-2       Acute Toxicity to Freshwater Invertebrates



132537	LeBlanc, G.; Surprenant, D. (1983) Acute Toxicity of FMC 54800
Technical to Daphnia magna: Bionomics Report #BW-83-8-1444; FMC Study
#A83-986. (Unpublished study received Nov 3, 1983 under 279-EX-101;
prepared by EG & G, Bionomics, submitted by FMC Corp., Philadelphia, PA;
CDL:251727-G) 

163139	Hoberg, J.; Noll, M.; Henzel, S.; et al. (1985) [Carbon 14] -
FMC- 54800: D. magna: 21-Day Chronic (Flow-through): Study # 282-
0484-6102-130. Unpublished raw data prepared by Springborn Bionomics,
Inc. 97 p. 

72-3       Acute Toxicity to Estuarine/Marine Organisms



163101	Barrows, M. (1986) Acute Toxicity of FMC 54800 to Sheepshead
Minnow (Cyprinodon variegatus): Final Report. Unpublished FMC study no.
A85-1874 prepared by Battelle, New England Marine Research Lab. 304 p. 

163102	Barrows, M. (1986) Acute Toxicity of FMC 54800 to Mysid Shrimp
(Mysidopsis bahia): Final Report: Unpublished FMC Study No. A85- 1875
prepared by Battelle, New England Marine Res. Lab. 443 p. 

163103	Ward, G. (1986) Acute Toxicity of FMC 54800 Tech. on Shell Growth
of the Eastern Oyster (Crassostrea virginica): Revised Toxicity Rept.:
ESE No. 85-322-0950-2130. Unpublished study prepared by Environmental
Science and Engineering, Inc. 80 p. 

40266501	Ward, G. (1987) Acute Effect of FMC 54800 Technical on New
Shell Growth of the Eastern Oyster (Crassostrea virginica): Study No.
A86-2203; Lab Project ID: 85-322-0960-2130. Unpublished study prepared
by Environmental Science and Engineering, Inc. 37 p. 

40383501	Ward, G. (1987) Acute Toxicity of FMC 54800 Technical to
Embryos and Larvae of the Eastern Oyster (Crassostrea virginica):
Laboratory Project ID ESE No. 87-318-0200-2130: FMC Corporation Study
No. A87-2264. Unpublished study prepared by Environmental Science and
Engineering, Inc. 71 p. 

72-4       Fish Early Life Stage/Aquatic Invertebrate Life Cycle
Study



40275401	Hoberg, J.; Nicholson, R.; Grandy, K.; et al. (1985) The
Chronic Toxicity of [Carbon 14]-FMC-54800 Daphnia magna under Flow-
through Conditions: Laboratory ID: 282-0484-6102-130. Unpub- lished
study prepared by Springborn Bionomics, Inc. 35 p. 

40569402	Drenner, R.; Hoagland, K.; Smith, J.; et al. (1988)
Experimental Microcosm Study of the Effects of Sediment-Bound Bifenthrin
on Gizzard Shad and Plankton: FMC Study No. A87-2414. Unpublished study
prepared by Texas Christian University. 197 p. 

41156501	Burgess, D. (1989) Chronic Toxicity of Carbon 14|-FMC 54800 to
Daphnia magna under Flow-through Test Conditions: ABC Final Report No.
36980. Unpublished study prepared by Analytical Bio-Chemistry
Laboratories, Inc. 244 p. 

41640501	Ward, T.; Boeri, R. (1990) Life Cycle Toxicity of Bifenthrin
FMC 54800 to the Mysid, Mysidopsis bahia: Lab Project Number: 9080/ FMC.
Unpublished study prepared by Resource Analysts, Inc., EnviroSystems
Div. 49 p. 

42338801	Boeri, R.; Ward, T. (1991) Life Cycle Toxicity of Bifenthrin
(FMC 54800) to the Mysid, Mysidopsis bahia: Lab Project Number:
A90-3318. Unpublished study prepared by Resource Analysts, Inc.,
EnviroSystem Div. 48 p. 

72-5       Life cycle fish



40791301	McAllister, W. (1988) Full Life Cycle Toxicity of Carbon
14|-FMC 54800 to Fathead Minnow (Pimephales promelas) in a Flow-through
System: ABC Final Report No. 34843. Unpublished study prepared by
Analytical Bio-Chemistry Laboratories, Inc. 1922 p. 

41032101	Palmieri, M. (1989) FMC Response to Ecological Effects Branch
Review Classification of the "Full Life Cycle Toxicity of Carbon14|-FMC
54800 to Fathead Minnow (Pimephales Promelas) in a Flow-through System".
Unpublished study. 17 p. 

72-7       Simulated or Actual Field Testing



40981802	Akkari, K. (1985) Bifenthrin Pond Study - Analytical
Methodology, Storage Stability, and Pre-Test 1 Data: Proj. ID SG
182-85-10; P-1217. Unpublished study prepared by FMC Corp. 101 p. 

40981803	Alvarez, M. (1988) Bifenthrin (FMC 54800) Aquatic (Pond) Study
- Drift Card Analysis: Proj. ID 182AF8760; P-1918. Unpublished study
prepared by FMC Corp. 61 p. 

40981805	Akkari, K. (1988) Bifenthrin Pond Study - Magnitude of the
Residue of Bifenthrin in Pond Water: Proj. ID 182E55E01; P-1937.
Unpublished study prepared by FMC Corp. 65 p. 

40981807	Akkari, K. (1988) Bifenthrin Pond Study - Storage Stability of
Bifenthrin in Field Fortified Samples: Proj. ID 182E55E01; P-1949.
Unpublished study prepared by FMC Corp. 72 p. 

40981808	Akkari, K. (1988) Bifenthrin Pond Study - Magnitude of the
Residue of Bifenthrin in Pond Sediment: Proj. ID 182E55E01; P-1955.
Unpublished study prepared by FMC Corp. 70 p. 

40981812	Ridler, J. (1988) Bifenthrin Pond Study - Magnitude of The
Residue of Bifenthrin in Biological Samples: Proj. ID 182E55E01; P-1976.
Unpublished study prepared by FMC Corp. 85 p. 

40981813	Ridler, J. (1988) Analytical Method for the Determination of
Bifenthrin in Biological Samples: Project ID: 182E55E01. Unpublished
study prepared by FMC Corp. 46 p. 

40981814	Akkari, K. (1988) Bifenthrin Pond Study--Magnitude of the
Residue of Bifenthrin in Sediment Bucket: Project ID: 182E55E01. Unpu-
blished study prepared by FMC Corp. 60 p. 

40981815	Liu, D. (1988) Bifenthrin (FMC 54800) Aquatic (Pond)
Study--Aircraft Tank Mixture Analysis: Project ID: AF860038. Unpublished
study prepared by FMC Corp. 19 p. 

40981816	ui, D. (1988) Bifenthrin Pond Study: Analytical Method for the
Determination of Bifenthrin in Aircraft Tank Mixture: Project ID:
AF860038. Unpublished study prepared by FMC Corp. 9 p. 

40981817	Akkari, K. (1988) Bifenthrin Pond Study--Magnitude of the
Residue of Bifenthrin in Bioassay Water: Project ID: 182E55E01. Unpu-
blished study prepared by FMC Corp. 97 p. 

40981818	Akkari, K. (1988) Bifenthrin Pond Study--Magnitude of the
Residue of Bifenthrin in Run-Off Water and Sediment: Project ID:
182E55E01. Unpublished study prepared by FMC Corp. 60 p. 

40981819	Akkari, K. (1988) Bifenthrin Pond Study--Magnitude of the
Residue of Bifenthrin in Field Soil: Project ID: 182E55E01; 182E55E763.
Unpublished study prepared by FMC Corp. 72 p. 

40981820	Akkari, K.; Javick, R. (1988) Bifenthrin Pond Study: Analytical
Method for the Determination of Bifenthrin in Soil: Project IDs:
182AF8763; 182E55E01. Unpublished study prepared by FMC Corp. 46 p. 

40981821	Giddings, J. (1988) FMC 54800 Aquatic Effects Field Study:
Phase I Baseline Ecological Survey of Hagan's Pond Orrville, Alabama:
Project ID:Report BW-86-7-2082; Study No. 282-6110-000. Unpublished
study prepared by Springborn Life Sciences, Inc. 600 p. 

40981822	Sherman, J. (1989) Bifenthrin Pond Study: Ecological Effects
During Treatment and Post-Treatment Follow-up Studies of Hagan's Pond,
Orville, Alabama: Project ID: A84-1285-02; FMC/54800. Unpu- blished
study prepared by The Academy of Natural Sciences of Philadelphia. 1037
p. 

81-1       Acute oral toxicity in rats



132519	Norvell, M.; Freeman, C. (1983) Acute Oral Toxicity of FMC 54800
Technical in Rats: Study #A83-859. (Unpublished study received Nov 3,
1983 under 279-EX-101; submitted by FMC Corp., Philadel- phia, PA;
CDL:251726-A) 

132527	DeProspo, J.; Freeman, C. (1983) Acute Oral Toxicity of 54800,
2EC in Rats: Study #A83-1027. (Unpublished study received Nov 3, 1983
under 279-EX-101; submitted by FMC Corp., Philadelphia, PA;
CDL:251726-I) 

141187	Freeman, C. (1984) Acute Oral Toxicity of FMC 54800 10 WP in
Rats: Study Number A84-1268. Unpublished study prepared by FMC Toxi-
cology Laboratory. 54 p. 

155285	Freeman, C. (1983) Acute Oral Toxicity of FMC 54800, 100 g/l EC
in Rats: Study Number A83-1054. Unpublished study prepared by FMC Corp.
61 p. 

40383605	Freeman, C. (1987) Acute Oral Toxicity Study in Rats: FMC
102032 Tech.: Study No. A87-2314. Unpublished study prepared by FMC
Corp. 15 p. 

40637602	Gabriel, D. (1987) 1.0% Talstar, Aerosol Concentrate,: Acute
Oral Toxicity, Single Level - Rats: Proj. No. 87-5835A. Unpub- lished
study prepared by Biosearch Inc. 9 p. 

41150202	Gabriel, D. (1989) PT 1800DS, Aerosol Concentrate, Form
#62-002: WRL Project #35-014: Acute Oral Toxicity, Single Level - Rats:
Biosearch Project No. 89-6589A. Unpublished study prepared by Biosearch
Inc. 8 p. 

41413602	DeProspo, J. (1984) FMC 54800 80 G/L Flowable: Acute Oral
Toxicity in Rats: Study No. A84-1247. Unpublished study prepared by FMC
Toxicology Laboratory. 51 p. 

41539002	Freeman, C. (1987) Acute Oral Toxicity Study in Rats: Capture 2
EC: Lab Project Number: A87-2410. Unpublished study prepared by FMC
Toxicology Laboratory. 26 p. 

41744301	Freeman, C. (1990) Acute Oral Toxicity Study in Rats: FMC 54800
1 EC: Lab Project Number: A90-3234. Unpublished study prepared by FMC
Corp. 25 p. 

41968506	Freeman, C. (1990) Acute Oral Toxicity Study in Rats: FMC 78161
Technical: Lab Project Number: A90-3173. Unpublished study pre- pared by
FMC Corp. 24 p. 

41968513	Freeman, C. (1990) Acute Oral Toxicity Study in Rats: FMC 78162
Technical: Lab Project Number: A90-3172. Unpublished study pre- pared by
FMC Corp. 24 p. 

42023302	Freeman, C. (1991) Bifenthrin 5% Tablet Blend: Acute Oral
Toxicity Study in Rats: Lab Project Number: A91-3412. Unpublished study
prepared by FMC Corp. 27 p. 

42094202	Freeman, C. (1990) Bifenthrin 0.2% Granules: Acute Oral
Toxicity Study in Rats: Lab Project Number: A90-3157. Unpublished study
prepared by FMC Corp. Toxicology Lab. 14 p. 

42231802	Freeman, C. (1991) Acute Oral Toxicity Study in Rats: Lab
Project Number: A91-3473. Unpublished study prepared by FMC Corp. 22 p. 

42376102	Gabriel, D. (1992) Acute Oral Toxicity, LD50--Rats: PT 1810
Concentrate Less Propellant|: Lab Project Number: 91-7460A: 35-43.
Unpublished study prepared by Biosearch Inc. 18 p. 

43758101	Freeman, C. (1994) FMC 54800 0.3% ME: Acute Oral Toxicity Study
in Rats: Revised Report: Lab Project Number: A90-3300. Unpublished study
prepared by FMC Corp. 20 p. 

43758402	Freeman, C. (1995) FMC 54800 13% MUP: Acute Oral Toxicity Study
in Rats: Lab Project Numbers: A94-4124: ATM-0214: 307. Unpublished study
prepared by FMC Corp. 44 p. 

43780502	Freeman, C. (1995) FMC 54800 0.2G: Acute Oral Toxicity Study in
Rats: Lab Project Number: A95/4138. Unpublished study prepared by FMC
Corp. 38 p. 

43782102	Freeman, C. (1995) FMC 54800 0.2% G (Fertilizer): Acute Oral
Toxicity Study in Rats: Lab Project Numbers: A95-4148: ATM-0229.
Unpublished study prepared by FMC Corp. 37 p. 

44368201	Freeman, C. (1997) Acute Oral Toxicity Study in Rats: FMC 54800
2EC: Lab Project Number: A96-4546: 26. Unpublished study prepared by FMC
Corp. 65 p. 

44418201	Hoffman, G. (1996) Acute Oral Toxicity Study with PT-1820
Talstar T.R. in Rats: Lab Project Number: 95-1316. Unpublished study
prepared by Huntingdon Life Sciences. 39 p. 

44657101	Freeman, C. (1998) Acute Oral Toxicity Study in Rats: FMC 54800
IF: Lab Project Number: A97-4772. Unpublished study prepared by FMC
Corporation. 43 p. 

44869002	Freeman, C. (1998) FMC 54800 2.4% ME: Acute Oral Toxicity Study
in Rats: Lab Project Number: A38-4879. Unpublished study prepared by FMC
Corporation. 31 p. 

45353602	Freeman, C.; Scubelek, S. (2001) Acute Oral Toxicity Study in
Rats: Bifenthrin 1.15 G: Lab Project Number: A20000-5290. Unpublished
study prepared by FMC Corporation. 21 p. {OPPTS 870.1100} 

45364902	Allen, D. (1995) Semafor 20 FS: Acute Oral Toxicity Test in the
Rat: Lab Project Number: 240/125: A2001-5348. Unpublished study prepared
by Safepharm Labs., Ltd. 34 p. 

45654404	Tiwari, V. (2002) Acute Oral Toxicity Study of Bifenthrin
Technical in Rats: Final Report: Lab Project Number: 3415. Unpublished
study prepared by Jai Research Foundation. 33 p. 

45730302	Kuhn, J. (2002) Acute Oral Toxicity Study in Rats:
Bifenthrin/Spinosad 240 g/l SC: Final Report: Lab Project Number:
A2002-5548: 7025-02. Unpublished study prepared by Stillmeadow, Inc. 22
p. {OPPTS 870.1100} 

46425301	H.R. Mclane, Inc. (2004) Restricted Use Product: Control XX-X-X
Turf Fertilizer with 0.069% Bifenthrin Insecticide. Project Number:
EPA/CSI/BIFENR69/PC1. Unpublished study. 7 p.

46431902	Wright, J. (2004) Talstar 2% MB Insecticide Acute Toxicology
Waiver Request. Project Number: 04/PRA/104. Unpublished study prepared
by Product & Regulatory Associates, L.L.C. 14 p.

46778504	Wright, J. (2006) NUP Granule Insecticide: Acute Toxicity
Waiver Request. Project Number: 06/PRA/119. Unpublished study prepared
by Product & Regulatory Associates, LLC. 11 p.

46795910	Wright, J. (2006) NUP Fertilizer Insecticide: Acute Toxicology
Waiver Request. Project Number: 06/PRA/121. Unpublished study prepared
by Product & Regulatory Associates, LLC. 10 p.



123-2           Aquatic plant growth



45020014	Hoagland, K.; Drenner, R.; Smith, J. et al. (1992) Freshwater
Community Responses to Mixtures of Agricultural Pesticides: Effects of
Atrazine and Bifenthrin. Environmental Toxicology and Chemistry
12:627-637. 



850.1790       Chironomid Sediment Toxicity Test



46871501	Giddings, J. (2006) Overview of Sediment Toxicity Studies with
Synthetic Pyrethroids. Project Number: 06723, 06273. Unpublished study
prepared by Compliance Services International. 62 p.



141-1 	Bee/Non-target Insect Toxicity

163096	FMC Corp. (1986) Hazard Evaluation: Wildlife & Aquatic Organisms:
Bifenthrin Tech. Insecticide/Miticide. Unpublished compilation. 60 p. 

163104	FMC Corp. (1986) Nontarget Insects [Toxicity of Residues on
Foliage]: Bifenthrin Tech. Unpublished compilation. 45 p. 

44396503	Giddings, J. (1997) Aquatic Mesocosm and Field Studies with
Cotton Pyrethroids: Observed Effects and Their Ecological Significance:
Lab Project Number: 97-6-7014: 13656.0497.6100.900. Unpublished study
prepared by Springborn Labs., Inc. 102 p. 



Appendix A.   PRD data request justification tables 

The following proposed Data Call-in tables include rationales for
requiring the data requested in this problem formulation, explanations
of the utility of the data, and explanations for how the data might
impact risk assessment, following the format provided by PRD.

Guideline Number: 835.2120

Study Title:  Hydrolysis

Guideline Number: 835.2240

Study Title:  Aqueous Photolysis

Rationale for Requiring the Data

According to 40 CFR Part 158, Subpart N (Environmental Fate) §158.1300
(Environmental fate data requirements table), these data are required
for all terrestrial use patterns.

The available hydrolysis study was performed in the presence of high
levels of the cosolvent acetonitrile (around 7%) and at high
concentrations (0.5 and 5.2 ppm vs. the solubility of bifenthrin, which
is 0.014 ppb).  There was evidence of precipitation.  It is unknown if
the presence of the cosolvent or the high concentration of the test
substance could have affected the study results.

The available aqueous photolysis study was also performed in the
presence of high levels of cosolvent acetonitrile (around 30%).  Also,
the samples were not buffered and the studies were performed at above
the solubility limit (at 1 ppm vs. the solubility of 0.014 ppb).  The
study indicates that bifenthrin was stable to aqueous photolysis in
natural sunlight.  It is unknown if the presence of the cosolvent could
have affected the study results.  In the same study, using artificial
light, bifenthrin degraded with a reported half-life of 11.9 days and in
sensitized (acetone) solution it was 0.31 days.  There is a high level
of uncertainty with respect to the levels of photolysis (rate of
reaction), and the possible transformation products.

Practical Utility of the Data

How will the data be used? 

Bifenthrin is a synthetic pyrethroid with high toxicity towards aquatic
organisms, including those living in the benthos.  Knowledge of its
persistence in aquatic environments is important.  The results of this
study will be used in the environmental fate assessment, and later on,
in the ecological risk characterization.

In addition, the data will be used to derive the rate of reaction input
parameters to be used in the aquatic models GENEEC2, PRZM/ EXAMS and
FIRST.  The results from these models are used to determine exposure
concentrations in aquatic systems, for ecological risk estimation and to
determine surface drinking waters concentrations, in drinking water
exposure assessments.

How could the data impact the Agency’s future decision-making? 

Without these data, the Agency would have to make certain conservative
assumptions (e.g. assume that bifenthrin is stable to these processes in
the aquatic models).  These conservative assumptions could lead to
higher predicted concentrations (EECs), according to the models, and
consequently, higher risk quotients.  Also, there would be a higher
degree of uncertainty in the environmental fate assessment.  Knowledge
of these dissipation pathways in detail is essential to perform a better
and accurate environmental fate assessment and risk assessment.

The lack of these data will limit the flexibility the Agency and
registrants have in coming into compliance with the Endangered Species
Act and could result in use restrictions for bifenthrin that may be
unnecessary.





Guideline Number: 835.4100

Study Title:  Aerobic Soil Metabolism

Guideline Number: 835.4200

Study Title:  Anaerobic Soil Metabolism

Rationale for Requiring the Data

According to 40 CFR Part 158, Subpart N (Environmental Fate) §158.1300
(Environmental fate data requirements table), these data are required
for all terrestrial use patterns.

For aerobic soil metabolism, there are studies available with three
soils.  A study performed in one additional soil should be submitted.  
According to OPPTS Guideline 835.4100 & 835.4200, studies are required
in a total of four soils.  The registrant should monitor the volatiles,
which were not monitored in the previous studies, and there is
uncertainty about their relevance  

The available anaerobic soil metabolism study was performed with only
one soil and for a period of roughly 2 months of anaerobic incubation. 
Anaerobic studies with one soil type are generally sufficient for the
evaluation of transformation pathways.  Rates of transformation should
be determined in at least three additional soils.  Data performed for a
longer period of time will help the Agency to determine rates of
transformation and presence of possible metabolites.  The volatiles
should be monitored, since there is uncertainty about their relevance.

Practical Utility of the Data

How will the data be used? 

Bifenthrin is a synthetic pyrethroid with high toxicity towards aquatic
organisms, including those living in the benthos.  Knowledge of its
persistence in terrestrial and aquatic environments is important.  The
results of this study will be used in the environmental fate assessment,
and later on, in the ecological risk characterization.

In addition, the data will be used to derive the rate of reaction input
parameter to be used in the aquatic models GENEEC2, PRZM/ EXAMS and
FIRST.  The results from these models are used to determine exposure
concentrations, for ecological risk estimation, and to determine surface
drinking water concentrations, for drinking water exposure assessments.

How could the data impact the Agency’s future decision-making? 

Without these data, the Agency would have to make certain conservative
assumptions (e.g. use a two times the aerobic soil metabolism half-life
input for the aerobic aquatic metabolism or two times the anaerobic soil
metabolism half-life for the anaerobic aquatic metabolism in the aquatic
models).  These conservative assumptions could lead to higher predicted
concentrations (EECs), according to the models, and consequently, higher
risk quotients.  Also, there would be a higher degree of uncertainty in
the environmental fate assessment.  Knowledge of these dissipation
pathways in detail is essential to perform a better and accurate
environmental fate assessment and risk assessment.

The lack of these data will limit the flexibility the Agency and
registrants have in coming into compliance with the Endangered Species
Act and could result in use restrictions for bifenthrin that may be
unnecessary.





Guideline Number: 835.4300

Study Title:  Aerobic Aquatic Metabolism

Guideline Number: 835.4400

Study Title:  Anaerobic Aquatic Metabolism

Rationale for Requiring the Data

According to 40 CFR Part 158, Subpart N (Environmental Fate) §158.1300
(Environmental fate data requirements table), these data are required
for all terrestrial use patterns.

There are no aerobic or anaerobic aquatic metabolism studies available
for review.

Practical Utility of the Data

How will the data be used? 

Bifenthrin is a synthetic pyrethroid with high toxicity towards aquatic
organisms, including those living in the benthos.  Knowledge of its
persistence in soil and aquatic environments is important.  The results
of this study will be used in the environmental fate assessment, and
later on, in the ecological risk characterization.

In addition, the data will be used to derive the rate of reaction input
parameter to be used in the aquatic models GENEEC2, PRZM/ EXAMS and
FIRST.  The results from these models are used for ecological risk
estimation and in drinking water exposure assessments.

How could the data impact the Agency’s future decision-making? 

Without these data, the Agency would have to make certain conservative
assumptions (e.g. use two times the aerobic soil metabolism half-life
input for the aerobic aquatic metabolism or two times the anaerobic soil
metabolism half-life for the anaerobic aquatic metabolism in the aquatic
models).  These conservative assumptions could lead to higher predicted
concentrations (EECs), according to the models, and consequently, higher
risk quotients.  Also, there would be a higher degree of uncertainty in
the environmental fate assessment.  Knowledge of these dissipation
pathways in detail is essential to perform a better and accurate
environmental fate assessment and risk assessment.

The lack of these data will limit the flexibility the Agency and
registrants have in coming into compliance with the Endangered Species
Act and could result in use restrictions for bifenthrin that may be
unnecessary.





Guideline Number: 835.1230

Study Title:  Mobility – Adsorption/ Desorption

Rationale for Requiring the Data

According to 40 CFR Part 158, Subpart N (Environmental Fate) §158.1300
(Environmental fate data requirements table), this data is required for
all terrestrial use patterns.

The available study was performed at a single concentration and no
Freundlich correlations are available.  Also, the solutions contained
acetonitrile as cosolvent (2%) this could have affected the results. 
The study indicated that bifenthrin is immobile in the soils tested (KOC
≥ 100,000; FAO Mobility Classification).  The mobility of this
chemical may be greatly under or overestimated and is uncertain.

Practical Utility of the Data

How will the data be used? 

Bifenthrin is a synthetic pyrethroid with high toxicity towards aquatic
organisms, including those living in the benthos.  Knowledge of its
mobility in soil environments and its organic carbon normalized
adsorption coefficient is important.  The results of this study will be
used in the environmental fate assessment, and later on, in the
ecological risk characterization.

In addition, the data will be used to derive the mobility input
parameter to be used in the aquatic models GENEEC2, PRZM/ EXAMS, FIRST
and SCI-GROW.  The results from these models are used for ecological
risk estimation and in drinking water exposure assessments.

How could the data impact the Agency’s future decision-making? 

Without these data, the Agency would have to make certain uncertain
assumptions (e.g. use the adsorption constants derived at the highest
concentration only for the mobility input parameter in the aquatic
models).  These uncertain assumptions could lead to higher predicted
concentrations (EECs), according to the models, and consequently, higher
risk quotients.  The KOC input parameter has a major effect in the
determination of the EECs for benthic organisms.  Also, there would be a
higher degree of uncertainty in the environmental fate assessment. 
Knowledge of the mobility of this chemical in detail is essential to
perform a better and accurate environmental fate and risk assessment.

The lack of these data will limit the flexibility the Agency and
registrants have in coming into compliance with the Endangered Species
Act and could result in use restrictions for this chemical that may be
unnecessary.





Guideline Number: None

Study Title:   Environmental Chemistry Methods (ECM) and Independent
Laboratory Validation (ILV) for Soil, Water and Sediment

Rationale for Requiring the Data

According to the data requirements in 40 CFR Part 158, ECMs are
currently required along with successful confirmatory method trials
(validation) by an independent laboratory (i.e. ILVs).  In addition to
the method for soil, at this time, methods are required for water and
sediment.  Acceptable ECMs for the residues of concern (parent and its
transformation products, if applicable) should have levels of
quantization that are adequate to address risk concerns or that are at
levels below the toxicological endpoints for the relevant aquatic
organisms.  The results of previous assessments indicate that there is
risk for freshwater and estuarine/ marine fish, invertebrates and
benthic organisms.  Therefore, ECMs for water and sediment are required
in addition to the ECM for soil.  The ECMs should include parent and
those residues found in the laboratory studies that exceed 10% of the
applied. The registrant is encouraged to submit state-of-the-art
environmental chemistry methods; further, multi-residue methods (MRMs)
for soil, water and sediment are preferred, if applicable.

Practical Utility of the Data

How will the data be used? 

The data will be used to verify the suitability of the methods. 
Subsequently the methods could be used by states or other enforcement
agencies, departments or entities, to monitor concentrations of the
residues of concern.  Validated analytical methods in environmental
media (a.k.a., ECMs) are useful for conducting and evaluating submitted
environmental fate and toxicity field and monitoring studies and for
addressing potential risks to the environment posed by the use and/or
accidental release of pesticides.

How could the data impact the Agency’s future decision-making? 

If monitoring of the chemical is required or performed, the Agency could
be able to determine if the chemical is present in the environment at
concentrations that are threatening to wildlife (or to humans, in the
case of drinking waters), according to the levels of concern (LOCs).  If
that is the case, measures to prevent these concentrations to occur
could be taken.  The data could also be used by enforcement entities
like the states or government agencies or departments.  Without these
data, the potential for the determination of residues of bifenthrin and
transformation products (if applicable) in soil, water and sediment is
restricted.  The lack of these data will limit the flexibility the
Agency and registrants have in coming into compliance with the
Endangered Species Act, and could result in use restrictions for
bifenthrin which may otherwise be avoided, or which are unnecessarily
severe.



Guideline Number: None

Study Title: POTW Effluent Monitoring and POTW Treatability Study

Rationale for Requiring the Data

POTW Effluent Monitoring – Request any existing or ongoing POTW
effluent monitoring data for the pyrethroids be submitted to the Agency.

POTW Treatability Study – The Agency has recently requested and
provided comments on a protocol developed by the Pyrethroid Working
Group (PWG) for a bench scale study of waste water treatment, to assess
the percentage removed in the biosolids by the treatment, the amount
that would degrade during treatment, and the amount that would remain in
the waste water.   These data would be used to inform removal
percentages by waste water treatment, which is an input to the Exposure
and Fate Assessment Screening Tool’s (E-FAST) down-the-drain module.  
The Office of Pesticide Programs will continue to confer with the Office
of Water with the goal of refining our down-the-drain assessment for
registration review. It is the responsibility of the registrant to
ensure that bifenthrin is included in the study completed by the PWG or
conduct a similar study on their own (following submission of a protocol
for review).

Practical Utility of the Data

How will the data be used? 

These data would be used to inform removal percentages by waste water
treatment, which is an input to the Exposure and Fate Assessment
Screening Tool’s (E-FAST) down-the-drain module.

How could the data impact the Agency’s future decision-making? 

Without these data, the Agency will have to make assumptions regarding
the level of removal of bifenthrin (e.g., results of modeling from the
EPIWEB v.4.0 may be used).  Since the assumptions are likely to be crude
and conservative.  The lack of these data will limit the flexibility the
Agency and registrants have in coming into compliance with the
Endangered Species Act, and could result in use restrictions for
bifenthrin which may otherwise be avoided, or which are unnecessarily
severe.



Guideline Number: 850-2100

Study Title:  Passerine Acute Avian Oral  

Rationale for Requiring the Data

Although an acute avian oral study was received for both the Mallard
duck and the Bobwhite quail, the Agency updated its data requirements in
40 CFR Part 158 (October 26, 2007) to include an acute oral toxicity
study for both a passerine species and either a waterfowl or an upland
game species.  Prior to starting toxicity testing, a protocol will need
to be provided for review. 

Many passerine species utilize agricultural fields, forests, residential
areas and surrounding areas, and, therefore, have the potential to be
exposed to pesticides used in agricultural, forest, and residential
settings

It is likely that, for most pesticide use patterns, passerines are more
likely to be exposed to pesticides than upland game species and
waterfowl 

Passerines are smaller and have faster metabolisms than the waterfowl
and upland game bird species traditionally used in avian toxicity tests
which could impact their sensitivity to chemicals.

Practical Utility of the Data

How will the data be used? 

Data from passerine toxicity studies will be used to estimate potential
risks to birds associated with uses of bifenthrin.  The data will reduce
uncertainties associated with the current risk assessment for passerine
species and will improve our understanding of the potential effects of
bifenthrin.

How could the data impact the Agency’s future decision-making? 

Because birds significantly contribute to overall environmental quality,
a solid understanding of the potential risks to birds, including
passerine species, is essential for sound environmental management. 
Without acceptable data for bifenthrin, the Agency cannot determine the
levels of bifenthrin that result in effects to passerine species.  If
the data indicates that registered usage may pose a risk of adverse
effects to non-target birds above the Agency Level of Concern, the
Agency may explore decision options to mitigate this risk.  The lack of
these data will limit the flexibility the Agency and registrants have in
coming into compliance with the Endangered Species Act, and could result
in use restrictions for bifenthrin which may otherwise be avoided, or
which are unnecessarily severe.





Guideline Number:  850.1035

Study Title: Mysid Acute Toxicity (saltwater, Bifenthrin TEP only)

Rationale for Requiring the Data

Bifenthrin has the potential to enter estuarine/marine water bodies
based on current usage patterns that include coastal areas and the
expected environmental concentrations in aquatic environments reported
in previous Bifenthrin assessments. Bifenthrin technical is very highly
toxic to estuarine/marine invertebrates on an acute basis, but no
information has been submitted for the Bifenthrin TEP. A new study is
required based on the absence of acceptable data to satisfy the
guidelines for acute estuarine/marine fish and invertebrate studies with
the typical end-use product. 

According to the Part 158 data requirements, testing on the typical
end-use product may be required for aquatic toxicity tests when any of
the following conditions exist: 

	1.  The end-use product will be introduced directly into the aquatic
environment.

2.  The maximum expected environmental concentration or estimated
environmental concentration in the aquatic environment is greater than
or equal to one-half the LC50 or EC50 of the TGAI.

3.  An ingredient in the end-use formulation other than the active
ingredient is expected to enhance the toxicity of the active ingredient
or cause toxicity to aquatic organisms.

Previous assessments indicated that the expected environmental
concentrations of bifenthrin in aquatic environments were based on the
solubility limit in water (0.014 ppb). In freshwater and
estuarine/marine tests conducted with Bifenthrin technical, the most
toxic 96-hour LC50s were 0.15 µg/L for rainbow trout, 1.6 µg/L for
Daphnia, 17.5 µg/L for sheepshead minnow and 0.004 µg/L for Mysid
shrimp. Therefore, bifenthrin fulfills the second requirement for TEP
testing for estuarine/marine invertebrate species only.

Practical Utility of the Data

How did the Agency make its re-registration decision without this data? 


To address potential risks, the Agency imposed mitigation, as an interim
measure, which included reduced use rates and application restrictions. 


How will the data be used?  

These data are needed for a registration review decision and for an
endangered species assessment, which will be conducted as part of that
decision.  The data would allow the Agency to determine acute risk to
estuarine/marine organisms from exposure to Bifenthrin.  The effects
data would be used to determine the likelihood that exposure to
Bifenthrin can potentially impact aquatic communities, either by direct
effects or by indirect effects on other organisms by reducing their food
sources.  

How could the data impact the Agency’s future decision-making?

If future endangered species risk assessments are performed without
these data, the Agency would have to assume that the Bifenthrin "may
affect" endangered estuarine/marine organisms directly (and endangered
species from other taxa indirectly), and use of Bifenthrin might need to
be restricted in areas where endangered species could be exposed.  The
lack of these data will limit the flexibility the Agency and registrants
have in coming into compliance with the Endangered Species Act and could
result in use restrictions for Bifenthrin which are unnecessarily
severe.





 

Guideline Number:  850.1400

μg a.i./L) is below the 1.0 mg/L criterion specified in 40 CFR Part 158
for conditionally requiring this study.  Furthermore, the persistence of
bifenthrin in water is expected to substantially exceed the 4-d half
life criterion specified in 40 CFR Part 158.



Practical Utility of the Data

How will the data be used?  

The estuarine/ marine fish early life stage study would allow the Agency
to analyze chronic effects, including effects on reproductive success
and growth, to saltwater species.  The effects data would be used to
determine the likelihood that the chronic risks can potentially impact
aquatic communities, either by direct effects on fish or by indirect
effects by reducing their food sources.  By refining the assessment, the
Agency would be able to determine whether the mitigation imposed as part
of the registration review process was appropriate due to toxicity
concerns with bifenthrin.

How could the data impact the Agency’s future decision-making?

If future endangered species risk assessments are performed without
these data, the Agency would have to assume that bifenthrin "may affect"
endangered estuarine/ marine fish directly (and endangered species from
other taxa indirectly), and use of bifenthrin might need to be
restricted in areas where endangered species could be exposed.  The lack
of these data will limit the flexibility the Agency and registrants have
in coming into compliance with the Endangered Species Act and could
result in use restrictions for bifenthrin which are unnecessarily
severe.





Guideline Number:  850.1500

Study Title:  Fish Full Life Cycle 

Rationale for Requiring the Data

The full life cycle chronic toxicity of bifenthrin to fish is indicated
based on its aquatic toxicity and environmental fate properties per 40
CFR Part 158 data requirements (October 26, 2007). Specifically, a fish
full life cycle study may be conditionally required when the end use
product is expected transported to water from its intended use site, and
if any of the following apply: 

1. The EEC is > 0.1 the NOEC from the fish ELS or invertebrate LC test,
or

2. Studies of other organisms indicate reproductive physiology in fish
may be affected.

For bifenthrin, 60-d EECs in surface water range from 0.017 to 0.10
µg/L based on a recent assessment of new uses on mayhew, soybean and
other crops (D336608; Meléndez and Federoff, 2007).  These EECs clearly
exceed 0.004 µg/L, which is one tenth of the fathead minnow ELS NOAEC
(i.e., 0.004 = 0.1 * 0.04 µg/L MRID 40791301) and the freshwater
invertebrate LC NOAEC (0.0013 µg/L; MRID 41156501).  Furthermore,
adverse effects were observed on Daphnia magna reproduction at 0.003
ug/L, which may indicate that similar reproductive effects are likely to
occur in fish.  

Although a fish full life cycle study was previously submitted to the
Agency and classified as supplemental (MRID 40791301), a recent review
of this study revealed that it is unacceptable based on numerous
deficiencies identified in the study, such as low control survival and
an inadequate number of replicates (D381123; October 14, 2010). 
Therefore, a new fish full life cycle study is required.  Should the
registrant choose to conduct the study on an estuarine/marine fish, then
the additional requirement for an ELS study with estuarine/marine fish
could be satisfied with just one study.

Practical Utility of the Data

How will the data be used?  

The fish full life cycle study would allow the Agency to analyze chronic
effects, including effects on reproductive success and growth, to fish
species.  The effects data would be used to determine the likelihood
that the chronic risks can potentially impact aquatic communities, by
direct effects on fish.  By refining the assessment, the Agency would be
able to determine whether the mitigation imposed as part of the
registration review process was appropriate due to toxicity concerns
with bifenthrin.

How could the data impact the Agency’s future decision-making?

If future endangered species risk assessments are performed without
these data, the Agency would have to assume that bifenthrin "may affect"
endangered fish directly, and the use of bifenthrin might need to be
restricted in areas where endangered species could be exposed.  The lack
of these data will limit the flexibility the Agency and registrants have
in coming into compliance with the Endangered Species Act and could
result in use restrictions for bifenthrin which are unnecessarily
severe.



Guideline Number:  850.1010

Study Title:   Aquatic Invertebrate Acute Toxicity (Hyalella)

Rationale for Requiring the Data

Available information indicates that the freshwater amphipod, Hyalella
azteca, is substantially more sensitive to pyrethroids than Daphnia
magna, the commonly tested freshwater invertebrate (e.g., Anderson et
al. 2006; Maund et al., 2002).  Information on the acute toxicity of
bifenthrin to H. azteca was not identified in this problem formulation. 
Therefore, in order to ensure that risk to sensitive aquatic
invertebrates are appropriately quantified, additional acute toxicity
testing of H. azteca is needed (water column exposure, not
sediment-spiked). 

Practical Utility of the Data

How will the data be used?  

The freshwater acute toxicity study with Hyalella would allow the Agency
to analyze acutely toxic effects to one of the most sensitive species of
freshwater aquatic invertebrates.  The effects data would be used to
determine the likelihood that acute risks can potentially impact aquatic
communities, either by direct effects on invertebrates or by indirect
effects by reducing the food source for their predators (e.g., fish). 
By refining the assessment, the Agency would be able to determine
whether the mitigation imposed as part of the registration review
process was appropriate due to toxicity concerns with bifenthrin.  

How could the data impact the Agency’s future decision-making?

If future risk assessments are performed without these data, the Agency
would have to account for the potential increased sensitivity of
Hyalella to bifenthrin using other means which may include using an
extrapolation factor based on sensitivity differences with other
pyrethroids.  Since this extrapolation factor would involve uncertainty,
it is likely that a conservative factor would be applied.  This may
impinge on the Agency’s flexibility in coming into compliance with the
Endangered Species Act and could result in use restrictions for
bifenthrin which are unnecessarily severe.





Guideline Number:  850.1350

Study Title:  Aquatic Invertebrate Life Cycle (Estuarine/Marine)

Rationale for Requiring the Data

The need for a life cycle chronic toxicity of bifenthrin to
estuarine/marine invertebrates is indicated based on its aquatic
toxicity and environmental fate properties per 40 CFR Part 158 data
requirements (October 26, 2007).   Specifically:

bifenthrin is intended for use such that its presence in
estuarine/marine environment in significant concentrations is expected; 

the acute LC/EC50 for bifenthrin (e.g., 1.6 µg/L for Daphnia magna, is
substantially lower than the 40 Part 158 trigger value of 1 mg/L; and  

previous risk assessments have indicated that the aquatic EECs are >
0.01 of the acute LC/EC50 values for bifenthrin, which is another
condition for triggering an estuarine/marine invertebrate life cycle
study.  

In addition, the acute toxicity of estuarine/marine invertebrates (LC50
of 0.004 µg/L) is nearly three orders of magnitude lower than that for
freshwater invertebrates (EC50 of 1.6 µg/L) which suggests that
estuarine/marine invertebrates may be particularly sensitive to
bifenthrin.  Information on the chronic toxicity of bifenthrin to
estuarine/marine invertebrates is therefore needed to reduce uncertainty
in assessing risk to these non-target organisms. The preferred test
species is Americamysis bahia.

Practical Utility of the Data

How will the data be used?  

The estuarine/marine life cycle study would allow the Agency to analyze
chronic effects, including effects on reproductive success and growth,
to estuarine/marine invertebrate species.  The effects data would be
used to determine the likelihood that the chronic risks can potentially
impact aquatic communities, by direct effects on invertebrates.  By
refining the assessment, the Agency would be able to determine whether
the mitigation imposed as part of the registration review process was
appropriate due to toxicity concerns with bifenthrin.

How could the data impact the Agency’s future decision-making?

If future risk assessments are performed without these data, the Agency
would have to presume chronic risk to estuarine/marine invertebrates and
the use of bifenthrin might need to be restricted in areas where
otherwise it would not need to be restricted. 





Guideline Numbers: Non-Guideline

Study Title:  Chronic whole sediment:  Freshwater and marine
invertebrates  

Rationale for Requiring the Data

Sediment toxicity tests for freshwater or marine invertebrates have been
submitted to the Agency and are in review.  To satisfy the Agency’s
updated data requirements for outdoor uses in 40 CFR Part 158 (October
26, 2007), for bifenthrin, available information indicates that benthic
organisms may be exposed via run-off or spray drift applications used in
agricultural, forest, and residential settings. Specifically:

The peak sediment porewater EECs predicted for bifenthrin (0.006 –
0.014 ppb for a variety of crops) exceed 0.1 of the acute LC/EC50 (0.004
ppb for M. bahia), which satisfies one of the criteria for requiring
chronic whole sediment toxicity testing under 40 CFR Part 158.

The expected half-life of bifenthrin in sediment (>250 days for
anaerobic aquatic metabolism) is substantially greater than 40 CFR Part
158 criterion of 10 days.  

The Kd values are 992-5430, log KOW is 6.4, and KOC values are
131,000-275,000, all of which exceed the third set of trigger criteria
for requiring chronic testing (Kd > 50, or log KOW >3 or KOC > 1000).

Finally, the potential for persistent exposure from bifenthrin in
sediment is also indicated by open literature studies on pyrethroids
(Weston et al. 2005, Amweg et al. 2006 and Ding et al. 2009). 

For sediment studies involving pyrethroids, chronic tests on Hyalella
azteca, Chironomus tentans, and Leptocheirus plumulosus are requested. 
Although both are freshwater species, Hyalella  and  Chironomus differ
substantially in their ecological niche (i.e., epibenthic vs. infaunal
species), physiology, and potential sensitivities to pyrethroid
exposure.  Bifenthrin has the potential to enter estuarine/marine water
bodies based on current usuage patterns that include coastal areas.
Therefore, testing is required for Leptocheirus plumulosus, an
estuarine/marine sediment-dwelling invertebrate species.

Practical Utility of the Data

How will the data be used? 

Data from sediment toxicity studies will be used to estimate potential
risks to benthic organisms associated with uses of bifenthrin.  The data
will reduce uncertainties associated with the current risk assessment
for benthic species and will improve our understanding of the potential
effects of bifenthrin.

How could the data impact the Agency’s future decision-making? 

Although there was uncertainty in estimating the effect of bifenthrin on
benthic organisms in previous assessments, there was a potential risk
associated with adverse effects identified for estuarine/marine acute
and chronic organisms.  Acceptable data for benthic organisms will
reduce the uncertainty from the previous assessment   If the data
indicates that registered bifenthrin usage may pose a risk of adverse
effects to non-target benthic organisms above the Agency Level of
Concern, the Agency may explore decision options to mitigate this risk. 
The lack of these data will limit the flexibility the Agency and
registrants have in coming into compliance with the Endangered Species
Act, and could result in use restrictions for bifenthrin which may
otherwise be avoided, or which are unnecessarily severe.

. 



Guideline Numbers: 850.4150 and 850.4100

Study Title: Vegetative vigor and Seedling emergence with TEP, Tier
I/Tier II



Rationale for Requiring the Data



No acceptable toxicity data are currently available to assess the risk
of bifenthrin to terrestrial plants.  The Agency updated its data
requirements in 40 CFR Part 158 (October 26, 2007) to include plant
studies.

Since bifenthrin has residential outdoor uses, vegetative vigor and
seedling emergence studies using TEP are required.  These phytotoxicity
data are needed to evaluate the level of pesticide exposure to
non-target terrestrial and aquatic plants and to assess the impact of
pesticides on endangered and threatened plants.  

Practical Utility of the Data



How will the data be used?  

Data from terrestrial plant toxicity studies will be used to estimate
potential risks to plants associated with uses of bifenthrin.  The data
will reduce uncertainties associated with the current risk assessment
for terrestrial plants and will improve our understanding of the
potential effects of bifenthrin on plants. 

How could the data impact the Agency’s future decision-making?

Because plants form the basis of most habitats and significantly
contribute to overall environmental quality, a solid understanding of
the potential risks to terrestrial plants is essential for sound
environmental management.  Without acceptable plant growth data for
bifenthrin, the Agency cannot determine the levels of bifenthrin that
result in effects to terrestrial plants.  If the data indicates that
registered bifenthrin usage may pose a risk of adverse effects to
non-target terrestrial plants plants above the Agency Level of Concern,
the Agency may explore decision options to mitigate this risk.  The lack
of these data will limit the flexibility the Agency and registrants have
in coming into compliance with the Endangered Species Act, and could
result in use restrictions for bifenthrin which may otherwise be
avoided, or which are unnecessarily severe.





Guideline Number: 850.4400

Study Title: Aquatic Vascular Plant Growth-Lemna spp. Tiers I/II



Rationale for Requiring the Data



No acceptable studies for bifenthrin have been submitted for vascular
aquatic plants. The Agency has finalized its update to the data
requirements in 40 CFR Part 158.  In these updated data requirements,
which were promulgated on October 26, 2007, vascular plant testing is
required for pesticides such as bifenthrin with outdoor uses.

Practical Utility of the Data



How will the data be used?

Data from aquatic plant toxicity studies will be used to estimate
potential risks to plants associated with uses of bifenthrin.  The data
will reduce uncertainties associated with the current risk assessment
for aquatic plants and will improve our understanding of the potential
effects on vascular aquatic plants. 

How could the data change the Agency’s decision, or impact the
Agency’s future decision-making?  

Because plants form the basis of most habitats and significantly
contribute to overall environmental quality, a solid understanding of
the potential risks to aquatic plants is essential for sound
environmental management.  Without plant growth data for bifenthrin, the
Agency cannot determine the levels of bifenthrin that result in effects
to vascular aquatic plants.  If the data indicates that registered
bifenthrin usage may pose a risk of adverse effects to non-target
aquatic vascular plants above the Agency Level of Concern, the Agency
may explore decision options to mitigate this risk.  

If future endangered species risk assessments are performed without
these data, the Agency would have to assume that bifenthrin "may affect"
endangered plants and use of bifenthrin might need to be restricted in
areas where endangered species could be exposed.  The lack of these data
will limit the flexibility the Agency and registrants have in coming
into compliance with the Endangered Species Act and could result in use
restrictions for bifenthrin that may be unnecessarily severe. 





Guideline Number:  850.5400

Study Title:  Algal toxicity test, Tier I/II  

Rationale for Requiring the Data



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its data requirements in 40 CFR Part 158 (October 26, 2007) to include
plant studies.

Practical Utility of the Data



How will the data be used?  

Data from Tier I/II nonvascular aquatic plant toxicity studies will be
used to estimate potential risks to plants associated with uses of
bifenthrin.  The data will reduce uncertainties associated with the
current risk assessment for nonvascular aquatic plants and will improve
our understanding of the potential effects of bifenthrin. 

How could the data impact the Agency’s future decision-making?

Because plants form the basis of most habitats and significantly
contribute to overall environmental quality, a solid understanding of
the potential risks to nonvascular aquatic plants is essential for sound
environmental management.  Without plant growth data for bifenthrin, the
Agency cannot determine the levels that result in effects to aquatic
plants.  If the data indicates that registered usage may pose a risk of
adverse effects to non-target aquatic nonvascular plants above the
Agency Level of Concern, the Agency may explore decision options to
mitigate this risk.  The lack of these data will limit the flexibility
the Agency and registrants have in coming into compliance with the
Endangered Species Act, and could result in use restrictions for
bifenthrin which may otherwise be avoided, or which are unnecessarily
severe.



 Type I pyrethroids are characterized by the fact that they do not have
the cyano moiety in the alpha carbon in their chemical structure (on the
other hand Type II pyrethroids contain this moiety), see Mechanism of
Action for additional distinctions between the two types.

 See Page 18 of the SAP meeting minutes (USEPA 2009).

 μg/g)/[(760)(Vm)], where Cs is the air concentration at saturation
(μg/m3), VP is the vapor pressure in mmHg, MW is the molecular weight
(g/mol), and Vm is the volume occupied by a gas at 25°C, and a pressure
of 1 atm, according to the ideal gas constant, which is 24.45 L/mol.

  Available at url:    HYPERLINK
"http://www.epa.gov/oppbead1/methods/ecmindex.htm" 
http://www.epa.gov/oppbead1/methods/ecmindex.htm  

 PAGE   

 PAGE   5 

	

  PAGE   60 

Stressor

Source

Attribute

Change

Bifenthrin applied to agricultural or non-agricultural use site

Direct

application

Spray drift

Terrestrial vertebrates

Terrestrial 

invertebrates

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in prey and food

Modification of PCEs 

  related to prey availability

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Modification of PCEs related

   to habitat

Terrestrial plants

grasses/ forbs, fruit, seeds (trees, shrubs)

Runoff

Terrestrial vertebrates 

Exposure Media 

& Receptors

Soil

Ingestion

Ingestion

Ingestion

Dermal uptake/Ingestion

Atmospheric transport

Root uptake/contact

Wet/dry deposition

Ingestion

Leaching to

Groundwater

Irrigation 

water

Stressor

Bifenthrin Applications that Could Potentially End Up
“Down-the-drain”

Source/

Transport

Pathways

Wastewater flow

Source/

Exposure

Media

Treatment Facility Discharges into Surface Waters

Exposure

Route

Gill/

 Integument Uptake

Receptors

Attribute

Changes

Aquatic Invertebrates,

Vertebrates

Individual Vertebrates and Invertebrates Reduced survival,  growth or
reproduction

Plant Population

Reduced population growth

Aquatic Plants

Uptake/ Adsorption

**Route of exposure includes only ingestion of fish and aquatic inverts.

Stressor

Source

Receptors

Attribute

Change

Bifenthrin applied to agricultural or non-agricultural use site

Spray drift

Aquatic animals

Invertebrates 

Vertebrates

**Piscivorous mammals 

  and birds           

Individual organisms

Reduced survival2

Reduced growth

Reduced reproduction

Food chain

Reduction in algae and  

   vascular plants

Reduction in prey

Modification of PCEs     

   related to prey availability

Habitat integrity

Reduction in primary       

   productivity

Reduced cover

Community change

Modification of PCEs related to                                         
                                  

   habitat

Surface water/

Sediment

Runoff

Aquatic Animals

Invertebrates

Vertebrates

Exposure

Media

Uptake/gills 

or integument

Ingestion

Ingestion

Atmospheric transport

Wet/dry deposition

Soil

Leaching to

Groundwater

Uptake/gills 

or integument

Aquatic Plants

Non-vascular

Vascular

Uptake/cell, 

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Impervious Surfaces

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