UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF           

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

MEMORANDUM

Date: 		04/02/2008

SUBJECT:	PP#7E7227; Bifenthrin (128825). Human-Health Risk Assessment
for a Section 3 Registration Request for Application of Bifenthrin and
Establishment of Tolerances for Residues in/on Bushberries (Crop
Subgroup 13B), Juneberry, Lingonberry, Salal, Aronia Berry, Lowbush
Blueberry, Buffalo Currant, Chilean Guava, European Barberry, Highbush
Cranberry, Honeysuckle, Jostaberry, Native Current, Sea Buckthorn, and
Leaf Petioles (Crop Subgroup 4B). 

Petition No.	7E7227	Decision No:	379758

DP No:	350900	40 CFR:	§180.442

Chemical No.:	128825	Class:	Synthetic Pyrethroid

Trade Names:	Capture 2EC, Capture LFR, Brigade 2EC, Brigade WSB	EPA Reg.
Nos.: 	279-3069; 279-3313; 279-3108, 279-3302

MRIDs:	47144501, 47144502, 47144503





From:		William D. Wassell, Chemist

Registration Action Branch 1/Health Effects Division (RAB1/HED, 7509P)

		P.V. Shah, Ph.D., Acting Branch Chief

		Inerts Assessment Branch/Registration Division (RD, 7505P)

		Mark I. Dow, Ph.D., Biologist

Alternate Risk Integration Assessment Team (ARIA)

		Risk Integration Minor Use & Emergency Response Branch/RD (7505P)

Through:	Dana Vogel, Branch Chief

		RAB1/HED (7509P)

To:		Daniel Rosenblatt/Shaja Brothers (RM 05)

	Registration Division (RD, 7505P)

The Interregional Research Project No. 4 (IR-4), on behalf of the
Agricultural Experiment Stations of FL, MI, NJ, OR, TN, and TX, has
submitted requests for Section 3 registrations for the application of
bifenthrin to leaf petioles, subgroup 4B, [celery, cardoon, Chinese
celery, celtuce, Florence fennel, rhubarb, and Swiss chard] and
bushberries, subgroup 13B [blueberry (highbush and lowbush), currant,
elderberry, gooseberry, and huckleberry].  In conjunction with this
request, the petitioner has proposed the establishment of tolerances for
bifenthrin
[(2-methyl[1,1’-biphenyl]3-yl)methyl-3-(2-chloro-3,3,3-trifluoro-1-pro
penyl)-2,2-dimethyl-cyclopropanecarboxylate)] in/on:

Bushberry subgroup 13B	2.0 ppm

Juneberry	2.0 ppm

Lingonberry	2.0 ppm

Salal	2.0 ppm

Aronia berry	2.0 ppm

Blueberry, lowbush	2.0 ppm

Buffalo currant	2.0 ppm

Chilean guava	2.0 ppm

European barberry	2.0 ppm

Highbush cranberry	2.0 ppm

Honeysuckle	2.0 ppm

Jostaberry	2.0 ppm

Native currant	2.0 ppm

Sea buckthorn	2.0 ppm

Leaf petioles subgroup 4B	3.0 ppm

Concurrently,   SEQ CHAPTER \h \r 1 IR-4 requests the amendment of the
following end-use products (EPs) containing bifenthrin as the active
ingredient (ai) in order to include new uses on leaf petioles and
bushberries:  Capture® 2 EC Insecticide/Miticide
(emulsifiable-concentrate formulation, EPA Reg. No. 279-3069), Brigade®
2EC (EPA Reg. No. 279-3313), Brigade® WSB (water-soluble bag, EPA Reg.
No. 279-3108), and Capture® LFR Insecticide (flowable-concentrate
formulation, EPA Reg. No. 279-3302).  These EPs are proposed for
multiple broadcast foliar applications at maximum seasonal rates of 0.5
pound (lb) ai/acre (A) using ground or aerial equipment.  The proposed
pre-harvest intervals (PHIs) are 1 day for bushberries and 7 days for
leaf petioles.

The HED of the Office of Pesticide Programs (OPP) is charged with
estimating the risk to human-health from exposure to pesticides.  The RD
of OPP has requested that HED evaluate hazard and exposure data and
conduct dietary, occupational, residential, and aggregate exposure
assessments, as needed, to estimate the risk to human-health that will
result from the proposed and registered uses of bifenthrin.

A summary of the findings and an assessment of human-health risk
resulting from the proposed and registered uses of bifenthrin are
provided in this document.  The hazard characterization was provided by
PV Shah, Ph.D., (RAB1); the residue chemistry review, dietary exposure
assessment, and aggregate exposure and risk assessment were provided by
William Wassell (RAB1); the occupational/residential exposure assessment
was provided by Mark Dow (RD); and the drinking water assessment was
provided by Jose Melendez of the Environmental Fate and Effects Division
(EFED). 

Table of Contents  TOC \o "1-4" \h \z \u  

  HYPERLINK \l "_Toc194995012"  1.0  Executive Summary	  PAGEREF
_Toc194995012 \h  5  

  HYPERLINK \l "_Toc194995013"  2.0  Ingredient Profile	  PAGEREF
_Toc194995013 \h  9  

  HYPERLINK \l "_Toc194995014"  2.1  Summary of Proposed Uses	  PAGEREF
_Toc194995014 \h  9  

  HYPERLINK \l "_Toc194995015"  2.2  Structure and Nomenclature	 
PAGEREF _Toc194995015 \h  11  

  HYPERLINK \l "_Toc194995016"  2.3  Physical and Chemical Properties	 
PAGEREF _Toc194995016 \h  12  

  HYPERLINK \l "_Toc194995017"  3.0  Hazard Characterization/Assessment	
 PAGEREF _Toc194995017 \h  12  

  HYPERLINK \l "_Toc194995018"  3.1  Acute Toxicity Profile	  PAGEREF
_Toc194995018 \h  12  

  HYPERLINK \l "_Toc194995019"  3.2  FQPA Considerations	  PAGEREF
_Toc194995019 \h  13  

  HYPERLINK \l "_Toc194995020"  3.2.1  Adequacy of the Toxicity Database
  PAGEREF _Toc194995020 \h  13  

  HYPERLINK \l "_Toc194995021"  3.2.2  Evidence of Neurotoxicity	 
PAGEREF _Toc194995021 \h  13  

  HYPERLINK \l "_Toc194995022"  3.2.3  Determination of Susceptibility	 
PAGEREF _Toc194995022 \h  13  

  HYPERLINK \l "_Toc194995023"  3.2.4  Degree of Concern Analysis	 
PAGEREF _Toc194995023 \h  13  

  HYPERLINK \l "_Toc194995024"  3.2.5  Recommendation for a DNT Study	 
PAGEREF _Toc194995024 \h  13  

  HYPERLINK \l "_Toc194995025"  3.2.6  FQPA SF for Infants and Children	
 PAGEREF _Toc194995025 \h  14  

  HYPERLINK \l "_Toc194995026"  3.3  Hazard Identification and Toxicity
Endpoint Selection	  PAGEREF _Toc194995026 \h  14  

  HYPERLINK \l "_Toc194995027"  3.3.1  Levels of Concern for Margin of
Exposure	  PAGEREF _Toc194995027 \h  16  

  HYPERLINK \l "_Toc194995028"  3.3.2  Recommendation for Aggregate
Exposure Risk Assessments	  PAGEREF _Toc194995028 \h  16  

  HYPERLINK \l "_Toc194995029"  3.4  Endocrine Disruption	  PAGEREF
_Toc194995029 \h  16  

  HYPERLINK \l "_Toc194995030"  4.0  Dietary Exposure/Risk
Characterization	  PAGEREF _Toc194995030 \h  17  

  HYPERLINK \l "_Toc194995031"  4.1  Pesticide Metabolism and
Environmental Degradation	  PAGEREF _Toc194995031 \h  17  

  HYPERLINK \l "_Toc194995032"  4.1.1  Metabolism in Primary Crops and
Livestock	  PAGEREF _Toc194995032 \h  17  

  HYPERLINK \l "_Toc194995033"  4.1.1.1  Metabolism in Primary Crops	 
PAGEREF _Toc194995033 \h  17  

  HYPERLINK \l "_Toc194995034"  4.1.1.2  Metabolism in Livestock	 
PAGEREF _Toc194995034 \h  18  

  HYPERLINK \l "_Toc194995035"  4.1.2  Metabolism in Rotational Crops	 
PAGEREF _Toc194995035 \h  18  

  HYPERLINK \l "_Toc194995036"  4.1.3  Analytical Methodology	  PAGEREF
_Toc194995036 \h  18  

  HYPERLINK \l "_Toc194995037"  4.1.4  Environmental Degradation	 
PAGEREF _Toc194995037 \h  18  

  HYPERLINK \l "_Toc194995038"  4.1.5  Food Residue Profile	  PAGEREF
_Toc194995038 \h  19  

  HYPERLINK \l "_Toc194995039"  4.1.5.1  Tolerance Summary	  PAGEREF
_Toc194995039 \h  20  

  HYPERLINK \l "_Toc194995040"  4.1.6  International Residue Limits	 
PAGEREF _Toc194995040 \h  20  

  HYPERLINK \l "_Toc194995041"  4.1.7  Drinking Water Residue Profile	 
PAGEREF _Toc194995041 \h  20  

  HYPERLINK \l "_Toc194995042"  4.2  Dietary Exposure and Risk	  PAGEREF
_Toc194995042 \h  21  

  HYPERLINK \l "_Toc194995043"  4.2.1  Acute Dietary Exposure and Risk	 
PAGEREF _Toc194995043 \h  21  

  HYPERLINK \l "_Toc194995044"  4.2.2  Chronic Dietary Exposure and Risk
  PAGEREF _Toc194995044 \h  22  

  HYPERLINK \l "_Toc194995045"  5.0  Residential (Non-Occupational)
Exposure/Risk Characterization	  PAGEREF _Toc194995045 \h  23  

  HYPERLINK \l "_Toc194995046"  5.1  Residential Handler Exposure	 
PAGEREF _Toc194995046 \h  23  

  HYPERLINK \l "_Toc194995047"  5.2  Residential Post-application
Exposure	  PAGEREF _Toc194995047 \h  24  

  HYPERLINK \l "_Toc194995048"  5.3  Other (Spray Drift)	  PAGEREF
_Toc194995048 \h  25  

  HYPERLINK \l "_Toc194995049"  6.0  Aggregate Risk Assessments and Risk
Characterization	  PAGEREF _Toc194995049 \h  25  

  HYPERLINK \l "_Toc194995050"  6.1  Acute Aggregate Risk	  PAGEREF
_Toc194995050 \h  25  

  HYPERLINK \l "_Toc194995051"  6.2  Short- and Intermediate-Term
Aggregate Risk	  PAGEREF _Toc194995051 \h  26  

  HYPERLINK \l "_Toc194995052"  6.3  Long-Term (Chronic) Aggregate Risk	
 PAGEREF _Toc194995052 \h  27  

  HYPERLINK \l "_Toc194995053"  6.4  Cancer Risk	  PAGEREF _Toc194995053
\h  28  

  HYPERLINK \l "_Toc194995054"  7.0  Cumulative Risk
Characterization/Assessment	  PAGEREF _Toc194995054 \h  28  

  HYPERLINK \l "_Toc194995055"  8.0  Occupational Exposure/Risk Pathway	
 PAGEREF _Toc194995055 \h  28  

  HYPERLINK \l "_Toc194995056"  8.1  Short-/Intermediate-Term Handler
Risk	  PAGEREF _Toc194995056 \h  28  

  HYPERLINK \l "_Toc194995057"  8.2  Short-/Intermediate-Term
Post-application Risk	  PAGEREF _Toc194995057 \h  30  

  HYPERLINK \l "_Toc194995058"  9.0  Data Needs and Label Requirements	 
PAGEREF _Toc194995058 \h  31  

  HYPERLINK \l "_Toc194995059"  9.1  Toxicology	  PAGEREF _Toc194995059
\h  31  

  HYPERLINK \l "_Toc194995060"  9.2  Residue Chemistry	  PAGEREF
_Toc194995060 \h  32  

  HYPERLINK \l "_Toc194995061"  9.3  Occupational and Residential
Exposure	  PAGEREF _Toc194995061 \h  32  

  HYPERLINK \l "_Toc194995062"  Appendix 1:  Subchronic, Chronic and
Other Toxicity Profile	  PAGEREF _Toc194995062 \h  33  

 

1.0  Executive Summary

References: 

Revised Preliminary HED Chapter for the Bifenthrin Tolerance
Reassessment Eligibility Decision (TRED). DP Barcode: D283796.  J.
Liccione. 12/04/2002.

Bifenthrin: Human-health Risk Assessment for Proposed Uses on Cilantro,
Leafy Brassica Greens (subgroup 5b), Tuberous and Corm Vegetables
(Subgroup 1c), Dried Shelled Peas and Beans (except Soybean) (Subgroup
6c) and Tobacco. DP Barcode: D310088. M. Rust-Clock, et al. 4/6/2006.

Bifenthrin: PP#6E7125, PP#6E7126, PP#6E7127, PP#6E7128; Human-Health
Risk Assessment for Proposed Uses on Mayhaw, Root Vegetables, (Except
Sugar Beets, Crop Subgroup 1B), Peanut, Pistachio, Soybean, and Fruiting
Vegetables (Crop Group 8). DP Number:  334154, W.D. Wassell et al.,
07/25/2007

Background

Bifenthrin is a neurotoxic insecticide acting through direct contact and
ingestion, having a slight repellent effect.  The primary biological
effects of bifenthrin and other pyrethroids on insects and vertebrates
are inhibition of the voltage-gated Ca2+ channels coupled with a
stimulatory effect on the voltage-gated Na+ channels.  All pyrethroids
act as axonic poisons, affecting both the peripheral and central nervous
systems, and share similar modes of action.  Pyrethroids, including
bifenthrin, stimulate repetitive action in the nervous system by binding
to voltage-gated sodium channels, prolonging the sodium ion permeability
during the excitatory phase of the action potential.  This action leads
to spontaneous depolarizations, augmented neurotransmitter secretion
rate and neuromuscular block, which ultimately results in paralysis of
the insect.

Bifenthrin is formulated as an EC, wettable-powder (WP), granular (G),
or flowable-concentrate (FlC) product and has registered uses on a
variety of commodities.  Current tolerances (ranging from 0.05 to 10
ppm) are established in 40 CFR §180.442 for residues of bifenthrin
in/on various plant and livestock commodities.  Time-limited tolerances
for orchard grass and sweet potato roots (0.05 ppm) have been
established in conjunction with Section 18 emergency exemptions [40 CFR
§180.442(2b)].  A tolerance of 0.05 ppm is established for residues of
bifenthrin in food and feeds as a result of uses in food/feed handling
establishments [40 CFR §180.442(2)].  Residential uses are registered
for bifenthrin; however, no new residential uses are proposed in the
subject actions.

A Tolerance Reassessment Eligibility Decision (TRED) was issued for
bifenthrin in 2002 (reference above) and human-heath risk assessments
were completed on 4/6/06 and 7/25/07.  The TRED and risk assessments
examined all registered and previously pending uses of bifenthrin. A
complete discussion of the hazard assessment is included in these
documents.  

Dietary Exposure Assessment

Acute and chronic dietary exposure and risk assessments were conducted
using the Dietary Exposure Evaluation Model-Food Commodity Intake
Database (DEEM-FCID™, Version 2.03) which uses food consumption data
from the U.S. Department of Agriculture’s (USDA) Continuing Surveys of
Food Intakes by Individuals (CSFII) from 1994-1996 and 1998.    SEQ
CHAPTER \h \r 1 

Acute Dietary Exposure and Risk

An acute population-adjusted dose (  SEQ CHAPTER \h \r 1 aPAD) is
established based upon the acute neurotoxicity study in rats.  In this
study, the lowest-observed-adverse-effect-level (LOAEL) of 70.3 mg
/kg/day is based on observations of mortality (females only), clinical
and functional observation battery (FOB) findings and differences in
motor activity.  An uncertainty factor (UF) of 100x (10x for
inter-species extrapolations, 10x for intra-species variations, and a
Food Quality Protection Act safety factor (FQPA SF) of 1x) was used to
calculate the aPAD.  The aPAD for bifenthrin is equal to 0.33 mg/kg/day.

A highly-refined, acute probabilistic dietary exposure and risk
assessment was conducted for drinking water and all registered and
pending uses of bifenthrin.  Anticipated residue estimates (ARs) were
developed based on the latest USDA’s Pesticide Data Program (PDP)
monitoring data 1998-2005, Food and Drug Administration (FDA) data, or
field trial data for bifenthrin.  ARs were further refined using the
latest percent crop-treated data (%CT) and processing factors where
appropriate. 

EFED calculated Tier 1 estimated drinking water concentrations (EDWCs)
for bifenthrin in ground and surface drinking water using the screening
concentration in ground water (SCI-GROW) and FQPA Index Reservoir
Screening Tool (FIRST) models, respectively.  EDWCs in ground water were
estimated as 0.003 ppb and 0.014 ppb in surface water.  The acute
drinking water concentration of bifenthrin in surface water (0.014 ppb)
is based on the application of bifenthrin to lettuce at the highest
application rate (0.5 lb ai/A/season) and the solubility of bifenthrin
in water.

The acute dietary exposure estimates for food and drinking water are not
of concern to HED (<100% of the aPAD) at the 99.9th percentile of
exposure.  Bifenthrin dietary exposure at the 99.9th percentile for food
and drinking water for the U.S. population is 10% of the aPAD and 25% of
the aPAD for all infants (<1 year old), the most highly-exposed
population subgroup.  These estimates include exposure from residues in
drinking water.

Chronic Dietary Exposure and Risk

A   SEQ CHAPTER \h \r 1 chronic population-adjusted dose (cPAD) is
established based upon the one-year oral toxicity study in dogs.  In
this study, the LOAEL of 2.7 mg /kg/day is based on observations of
increased incidence of tremors in both sexes.  An UF of 100x was used to
calculate the cPAD.  The cPAD for bifenthrin is equal to 0.013
mg/kg/day.

A refined chronic dietary exposure assessment was conducted for the
registered and pending uses of bifenthrin using single point estimates
of anticipated bifenthrin residues for food.  The estimated surface
water concentration of 0.014 ppb, based on application to lettuce at the
highest application rate and the water solubility of bifenthrin, was
also used for the chronic dietary assessment.

The chronic dietary exposure estimates for food and drinking water are
not of concern to HED (<100% cPAD) for the U.S. population and all
population subgroups.  Bifenthrin dietary exposure for food and drinking
water is 21% of the cPAD for the U.S. population and 55% of the cPAD for
children 3-5 years old, the most highly-exposed population subgroup.

Cancer Dietary Risk

The Cancer Assessment Review Committee (CARC, 1992) recommended that for
the purpose of risk characterization, the RfD approach should be used
for quantification of human risk.  The chronic exposure analysis
exhibited exposures that were less than 100% RfD, and it is assumed that
the chronic dietary endpoint is protective for cancer dietary exposure.

Residential Exposure and Risk

Bifenthrin has both indoor and outdoor residential uses.  Adults may be
exposed to bifenthrin residues during residential application of
bifenthrin.  Adults and children may be exposed to bifenthrin residues
after application (post-application) of bifenthrin products in
residential settings.  Risk estimates were generated for residential
handler exposures, and potential post-application contact with lawn,
soil, and treated indoor surfaces using HED’s Draft Standard Operating
Procedures (SOPs) for Residential Exposure Assessment, and dissipation
data from a turf transferable residue (TTR) study.  These estimates are
considered conservative, but appropriate, since the study data were
generated at maximum application rates.  

Residential Handler Risk Estimates

Short- to intermediate-term dermal and inhalation exposures may occur
for residential handlers of bifenthrin products.  Residential handler
risks from inhalation exposures to bifenthrin gas/vapor are considered
unlikely, since the vapor pressure of bifenthrin is low. Inhalation
exposure was assessed for aerosols/particulates during residential
mixing, loading, and application of granular products.  Short- and
intermediate-term handler margins-of-exposure (MOEs) estimated for
combined dermal and inhalation exposures were >100, and therefore, are
not of concern to HED.  

Residential Post-Application Risk Estimates

Adults and children may be potentially exposed to bifenthrin residues
after application of bifenthrin products in residential settings. 
Short- and intermediate-term post-application dermal exposures for
adults, and short- and intermediate-term post-application dermal and
incidental oral exposures for children are anticipated.  Risk estimates
were generated for potential contact with lawn, soil, and treated indoor
surfaces.  Short- and intermediate-term risks estimated for
post-application exposure for adults and children are not of concern to
HED.  Combined oral and dermal short-term exposures for children are not
of concern to HED.  Combined adult handler and post-application risk
estimates (inhalation and dermal) associated with homeowner applied
formulations are not of concern to HED. 

Aggregate Risk

≤100).  Chronic (>6 months) non-dietary post-application exposure to
bifenthrin from a residential treatment is considered unlikely;
therefore, chronic aggregate risk assessments were not performed.

Short- and Intermediate-term Endpoints

The short- and intermediate term dermal endpoints for use in risk
assessment are established for bifenthrin.  The effects seen were
observations of clinical signs (staggered gait and exaggerated hindlimb
reflex) and were identified from a 21 day dermal study in rats.  The
no-observable-adverse-effect-level (NOAEL) is 47.0 mg/kg/day.  The level
of concern (LOC) for occupational and residential dermal is a MOE of
less than 100.

The short- and intermediate-term inhalation toxicological endpoints are
established for bifenthrin.  The inhalation endpoints are identified
from a 90-day oral toxicity study in dogs.  The observations were
increased incidence of tremors in both sexes.  The NOAEL is 2.21
mg/kg/day. MOEs of less than 100 are considered risks of concern to HED.
 

Occupational Handler Risk

Based upon the proposed use pattern, HED expects the most highly-exposed
occupational pesticide handlers (mixers, loaders, applicators) to be 1)
mixer/loader using open-pour loading of liquids; 2) an aerial
applicator, 3) an applicator using open-cab, ground-boom spray
equipment.  The proposed WP formulation consists of the product in
water-soluble packages (WSP).  A mixer/loader loading WSP was not
assessed.  HED considers WSP to be a "closed loading system" thereby
reducing exposures to negligible amounts.  Exposure from handling
water-soluble packages is expected to be less than that experienced by
mixer/loaders using open-pour techniques.  HED believes most exposure
durations will be short-term (1-30 days). However, the Science Policy
Council for Exposure (ExpoSAC) maintains that it is possible for
commercial applicators to be exposed to intermediate-term exposure
durations (1-6 months).  Therefore, estimates for short- and
intermediate-term risks are presented.  Provided that mixer/loaders wear
protective gloves, all MOEs are above 100, and, therefore, are not of
concern to HED.

Occupational Post-Application Risk

Based on the proposed use pattern, HED has calculated post-application
exposure and risk for workers exposed to bifenthrin residues following
treatment.  Workers engaging in activities such as hand harvesting,
topping, stripping and irrigation activities were assessed.  Standard
assumptions were incorporated into the assessment to reflect
conservative risk estimates.  The MOE for the theoretically most
highly-exposed post-application agricultural activity is 370, and is not
of concern to HED.  All other identified post-application activities are
expected to have lower exposures and greater MOEs.  

Based on the acute toxicity category classification for bifenthrin, the
interim worker protection standard (WPS) restricted-entry interval (REI)
of 12 hours is adequate to protect agricultural workers from
post-application exposures.  The proposed end-use product labels list an
REI of 12 hours.

HED Recommendations

The tolerances proposed by the registrant in the current petitions are
listed below, along with HED’s recommended tolerance levels.   SEQ
CHAPTER \h \r 1 

Pending submission of a revised Section B (see requirements under
860.1200 Directions for Use) and a revised Section F (see requirements
under 860.1550 Proposed Tolerances), the residue chemistry and
toxicology databases support unconditional registration and
establishment of permanent tolerances for the following:  

Tolerance Summary for Bifenthrin.

Crop Group or Commodity	Proposed Tolerance (ppm)	Recommended Tolerance
(ppm)	Comments; Correct Commodity Definition

Bushberry subgroup 13B	2.0	1.8	Bushberry subgroup 13-07B

Juneberry	2.0	Not needed	Separate tolerances for new commodities listed
in crop subgroup 13-07B are no longer required; refer to the Final Rule
published in the Federal Register 12/7/07.

Lingonberry	2.0



Salal	2.0



Aronia berry	2.0



Blueberry, lowbush	2.0



Buffalo currant	2.0



Chilean guava	2.0



European barberry	2.0



Highbush cranberry	2.0



Honeysuckle	2.0



Jostaberry	2.0



Native currant	2.0



Sea buckthorn	2.0



Leaf petioles subgroup 4B	3.0	3.0

	

860.1200  Directions for Use

There are now adequate residue data supporting bifenthrin use on head
lettuce grown in CA.  Therefore, the petitioner may submit a revised
Section B to remove the existing restriction prohibiting use of
bifenthrin on head lettuce grown in CA.

Label revisions are required to remove the statement that emulsified oil
may be substituted for water for aerial applications; the submitted crop
field trials do not reflect the use of emulsified oil.

HED notes that the draft label for 1.5 lb/gal FlC formulation states
under Directions for Use that the product is for ground application
only, and application by air is prohibited, but indicates under the
specific use directions for leafy petiole vegetables and bushberries
that the product may be applied by air.  This discrepancy should be
resolved.

860.1550  Proposed Tolerances

•	The petitioner is required to submit a revised Section F to amend
the proposed tolerance for Bushberry subgroup 13-07B and to reflect
correct commodity definition as reflected in the tolerance summary table
(above).

2.0  Ingredient Profile

2.1  Summary of Proposed Uses

The petitioner has submitted draft labels for the 2 lb/gal EC
formulations (Capture® 2EC Insecticide/Miticide; EPA Reg. No. 279-3069
and Brigade® 2EC Insecticide/Miticide; EPA Reg. No. 279-3313), the 10%
WP formulation (Brigade® WSB Insecticide/Miticide; EPA Reg. No.
279-3108), and the 1.5 lb/gal FlC formulation (Capture® LFR; EPA Reg.
No. 279-3302).  Table 2.1 is a summary of the proposed application
scenarios.  

Table 2.1.  Summary of Proposed Directions for Use of Bifenthrin.

Applic. Timing, Type, and Equip.	Formulation

[EPA Reg. No.]	Max. Single Applic. Rate 

(lb ai/A)	Max. No. Applic. per Season	Max. Seasonal Applic. Rate

(lb ai/A)	PHI

Foliar, Broadcast, Ground (≥10 gal/A) or aerial (≥2 gal/A)	2 lb/gal
EC

[279-3069]	0.10	Not specified

(NS)	0.5	1

	10% WP

[279-3108]	0.10	NS	0.5	1

	2 lb/gal EC

[279-3313]	0.10	NS	0.5	1

	1.5 lb/gal FlC

≥10 gal/A) or aerial (≥2 gal/A)	2 lb/gal EC

[279-3069]	0.10	NS	0.5	7

	10% WP

[279-3108]	0.10	NS	0.5	7

	2 lb/gal EC

[279-3313]	0.10	NS	0.5	7

	1.5 lb/gal FlC

[279-3302]	0.10	NS	0.5	7

	Use Directions and Limitations:  For aerial applications, 1-2 quarts of
emulsified oil may be substituted for 1-2 quarts of water in the
finished spray.  A minimum 7-day RTI is specified.  

Lettuce, head

Foliar, Broadcast, Ground (≥15 gal/A for 2 lb/gal EC and ≥20 gal/A
for 10% WP) or aerial (≥5 gal/A)	2 lb/gal EC

[279-3069]	0.10	NS	0.5	7

	10% WP

[279-3108]	0.10	NS	0.5	7

	2 lb/gal EC

[279-3313]	0.10	NS	0.5	7

	Use Directions and Limitations:  For aerial applications of the EC
formulation, 1-2 quarts of emulsified oil may be substituted for 1-2
quarts of water in the finished spray.  A minimum 7-day RTI.

At planting

Soil banded, in-furrow, or broadcast soil surface

Ground	1.5 lb/gal FlC

[279-3302]	0.08	NS	(at plant)

0.5 (at plant + foliar applications of other bifenthrin products)	NS

	Use Directions and Limitations:  Applications may be made as a 5-7 inch
band over an open furrow (T-band), in-furrow with the seed, or broadcast
over the entire acre on the soil surface.



The following rotational crop restriction is specified for the 2 lb/gal
EC, 10% WP, and 1.5 lb/gal FlC formulations:  Crops for which bifenthrin
tolerances exist may be rotated at any time.  All other crops may be
rotated 30 days following the final application of bifenthrin.  The
labels specify an REI of 12 hours for all formulations.

The draft labels for the 2 lb/gal EC formulations prohibit use in CA. 
In addition, these labels specify that the product may be applied
through sprinkler including center pivot, lateral move, end tow, side
(wheel) roll, traveler, big gun, solid set, or hand move irrigation
systems.  The draft labels for the 10% WP and 1.5 lb/gal FlC
formulations specify that application through any type of irrigation
system is prohibited.

HED notes that the draft label for 1.5 lb/gal FlC formulation states
under Directions for Use that the product is for ground application
only, and application by air is prohibited, but indicates under the
specific use directions for leafy petiole vegetables and bushberries
that the product may be applied by air.  This discrepancy should be
resolved by submission of a revised Section B.

Conclusions.  The proposed use directions are adequate to allow
evaluation of the residue data relative to the proposed use.  However,
since adequate field trial data are now available to support the use of
the 2 lb/gal EC formulation on head lettuce grown in CA (Zone 10).  The
petitioner may submit a revised Section B to remove the existing
restriction prohibiting use of bifenthrin on head lettuce grown in CA. 
Additionally, label revisions are required for the proposed EPs to
remove the statement that emulsified oil may be substituted for water
for aerial applications; the submitted crop field trials do not reflect
the use of emulsified oil.

2.2  Structure and Nomenclature

Table 2.2.  Nomenclature of Bifenthrin.

Compound	



Common name	Bifenthrin

Company experimental names	Capture® Insecticide/Miticide

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

or

(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

CAS #	82657-04-03

End-use products/EPs	2.0 lb ai/gal EC formulation (Capture 2EC; EPA Reg.
No. 279-3069)

1.5 lb/gal FlC formulation (Capture® LFR; EPA Reg. No. 279-3313)

2.0 lb ai/gal EC (Brigade 2EC, EPA Reg. No. 279-3108)

1.5 lb/gal FlC formulation (Capture® LFR; EPA Reg. No. 279-3302)



2.3  Physical and Chemical Properties

Table 2.3.  Physicochemical Properties of the Technical Grade
Bifenthrin.

Parameter	Value	Reference

Melting range	68-70.6°C	Product Chemistry Chapter of the TRED



pH	NA1

	Density at 24°C	1.26 g/mL

	Water solubility	0.014 ppb

	Solvent solubility (g/100 mL)	8.9 in heptane and methanol

125 in acetone, chloroform, ether, methylene chloride, and toluene 

	Vapor pressure (Pa) at 25°C	2.41 x 10-5

	Dissociation constant (pKa)	Not applicable

	Octanol/water partition coefficient (Kow)	>1 x 106

	UV/visible absorption spectrum	NA

	1 NA = information not available. 

3.0  Hazard Characterization/Assessment

For a complete summary of the toxicology database, see the following
documents:

BIFENTHRIN - 3rd Report of the Hazard Identification Assessment Review
Committee. TXR No. 0051570. B. Tarplee. 2/19/2003.

Revised Preliminary HED Chapter for the Bifenthrin Tolerance
Reassessment Eligibility Decision (TRED). PC Code: 128825 DP Barcode:
D283796. J. Liccione. 12/04/2002.

Bifenthrin: PP#6E7125, PP#6E7126, PP#6E7127, PP#6E7128; Human-Health
Risk Assessment for Proposed Uses on Mayhaw, Root Vegetables, (Except
Sugar Beets, Crop Subgroup 1B), Peanut, Pistachio, Soybean, and Fruiting
Vegetables (Crop Group 8), 7/25/07, W.D. Wassell, DP#:  371449.

3.1  Acute Toxicity Profile

Table 3.1. Acute Toxicity Profile – Bifenthrin.



Guideline No./Study Type	

MRID No. 	

Results	Toxicity  Category

870.1100/Acute oral toxicity	0013519	LD50 = 70.1 mg/kg (♂); 53.8 mg/kg
(♀) 	II

870.1200/Acute dermal toxicity	00132520	LD50 > 2,000 mg/kg 	III

870.1300/Acute inhalation toxicity	46029703	Data waived. Acceptable
atmosphere could not be generated with product.	IV

870.2400/Primary eye irritation	00132522	Non-irritant	IV

870.2500/Primary dermal irritation	00132521	Non-irritant	IV

870.2600/Dermal sensitization	00132523	Not a sensitizer	N/A

 

3.2  	FQPA Considerations

3.2.1	  Adequacy of the Toxicity Database

The Hazard Identification and Review Committee (HIARC) concluded that
the toxicology database for bifenthrin is complete.

3.2.2	  Evidence of Neurotoxicity

The HIARC concluded that there is a concern for neurotoxicity resulting
from exposure to bifenthrin.  This is based on the observation of
neurotoxicity (clinical signs) in the acute neurotoxicity, subchronic
neurotoxicity, 2-generation reproduction, developmental toxicity, dermal
toxicity, subchronic toxicity and chronic toxicity studies.   In
addition, FOB findings were observed in the acute and subchronic
neurotoxicity studies.  Since the last HIARC, the registrant submitted a
DNT study, which establishes clear NOAEL for the adult and offspring
toxicity.  The NOAEL in adults and offspring is based on the clinical
signs of neurotoxicity.

3.2.3  Determination of Susceptibility

Based on the results in developmental toxicity studies in rats and
rabbits, there is no quantitative or qualitative evidence of increased
susceptibility of rat or rabbit fetuses to in utero exposure to
bifenthrin.  In the prenatal developmental (gavage) toxicity study in
rats, a slight increase in the incidence of “hydroureter without
hydronephrosis” was observed in fetuses at the highest dose tested
(1.77 mg/kg/day); maternal toxicity (tremors) was also observed at this
dose level, and the maternal and developmental NOAELs were equivalent at
0.88 mg/kg/day.  This effect was not observed in the prenatal
developmental (dietary) toxicity study in rats.  In the prenatal
developmental toxicity study in rabbits, there was no evidence of
developmental toxicity at the highest dose tested.   

Based on the results in a 2-generation reproduction study in rats, there
was no quantitative or qualitative evidence of increased susceptibility
of neonates (as compared to adults) to bifenthrin.

Based on the results of the developmental neurotoxicity (DNT) study in
rats, there was no quantitative or qualitative evidence of increased
susceptibility of neonates (as compared to adults) to bifenthrin.  In
this study, the maternal and offspring toxicity NOAEL is 50 ppm (3.6
mg/kg/day during gestation and 8.3 mg/kg/day during lactation) based on
clinical signs of neurotoxicity.  This study did not impact endpoints
selected for various exposure scenarios.  

3.2.4  	Degree of Concern Analysis

There are no concerns or residual uncertainties for pre- and/or
post-natal toxicity following exposure to bifenthrin.

3.2.5	  Recommendation for a DNT Study

A DNT study with bifenthrin is available.  This study does not show any
evidence of increased susceptibility of offspring following exposure to
bifenthrin.  This study did not impact endpoints selected by the HIARC
for various exposure scenarios.  

3.2.6	  FQPA SF for Infants and Children

	The bifenthrin risk assessment team recommends that the 10X FQPA SF for
increased susceptibility be reduced to 1X for all exposure scenarios. 
This recommendation is based on the following considerations:

The toxicology database is complete. 

There are no residual uncertainties concerning pre- and post natal
toxicity.  

There are no residual uncertainties with respect to exposure data. 

The dietary food exposure assessment utilizes field trial data and 100%
CT for all proposed commodities.  Anticipated residue values and %CT
were used for some commodities.  By using these assumptions, the acute
and chronic exposures/risks will not be underestimated.  

The dietary drinking water assessment (Tier 1 estimates) utilizes values
generated by model and associated modeling parameters which are designed
to provide conservative, health protective, high-end estimates of water
concentrations.  

The FQPA SF recommended by the bifenthrin review team assumes that the
exposure databases (dietary food, drinking water, and residential) are
complete and that the risk assessment for each potential exposure
scenario includes all metabolites and/or degradates of concern and does
not underestimate the potential risk for infants and children.

Based upon the above-described data, the FQPA SF can be reduced to 1x
since there are no residual uncertainties for pre and/or post-natal
toxicity.

3.3	  Hazard Identification and Toxicity Endpoint Selection

The strengths and weaknesses of the bifenthrin toxicology database were
considered during the process of toxicity endpoint and dose selection. 
The selected toxicity endpoints are summarized in Table 3.3.



Table 3.3.  Summary of Toxicological Doses and Endpoints for Bifenthrin.



Exposure Scenario	Dose Used in Risk Assessment, UF	FQPA SF and LOC for
Risk Assessment	Study and Toxicological Effects

Acute Dietary-

general population, including infants and children	NOAEL = 32.8 mg/kg

UF = 100

Acute RfD = 0.33 mg/kg/day	FQPA SF = 1X

aPAD = acute RfD

               FQPA SF

= 0.33 mg/kg/day	Acute neurotoxicity study in rats. LOAEL = 70.3
mg/kg/day based on observations of mortality (females only), clinical
and FOB findings and differences in motor activity.

Chronic Dietary-

general population, including infants and children	NOAEL = 1.3 mg/kg/day

UF = 100

Chronic RfD = 0.013 mg/kg/day	FQPA SF = 1X

cPAD = cRfD

               FQPA SF

= 0.013 mg/kg/day	1-year oral toxicity in dogs. LOAEL = 2.7 mg/kg/day
based on observations of increased incidence of tremors in both sexes.

Short-Term 

(1-30 days) 

Incidental Oral 

	NOAEL= 2.21 mg/kg/day

UF = 100

MOE= 100	Residential MOE = 100

FQPA SF = 1X

	90-day oral toxicity study in dogs. LOAEL = 4.42 mg/kg/day based on
observations of increased incidence of tremors in both sexes.

Intermediate-Term (1-6 months) Incidental Oral 	NOAEL= 2.21 mg/kg/day

UF = 100

MOE= 100	Residential MOE = 100

FQPA SF = 1X

	90-day oral toxicity study in dogs. LOAEL = 4.42 mg/kg/day based on
observations of increased incidence of tremors in both sexes.

Short-Term 

(1-30 days) 

Dermal	Dermal NOAEL = 47 mg/kg/day

UF = 100

MOE= 100	Residential MOE = 100

FQPA SF = 1X

Occupational MOE = 100	21-day dermal study in rats.

LOAEL = 93 mg/kg/day based on observations of clinical signs (staggered
gait and exaggerated hindlimb reflex).

Intermediate-Term (1-6 months) Dermal	Dermal NOAEL = 47 mg/kg/day

UF = 100

MOE= 100	Residential MOE = 100

FQPA SF = 1X

Occupational MOE = 100	21-day dermal study in rats.

LOAEL = 93 mg/kg/day based on observations of clinical signs (staggered
gait and exaggerated hindlimb reflex).

Long-Term 

(>6 months)

Dermal	Dermal NOAEL = 47 mg/kg/day

UF = 100

MOE= 100	Residential MOE = 100

FQPA SF = 1X

Occupational MOE = 100	21-day dermal study in rats.

LOAEL = 93 mg/kg/day based on observations of clinical signs (staggered
gait and exaggerated hindlimb reflex).

Short-Term 

(1-30 days)

Inhalation	NOAEL= 2.21 mg/kg/day

UF = 100

MOE= 100	Residential MOE = 100

FQPA SF = 1X

Occupational MOE = 100	90-day oral toxicity study in dogs. LOAEL = 4.42
mg/kg/day based on observations of increased incidence of tremors in
both sexes.

Intermediate-Term (1-6 months) Inhalation	NOAEL= 2.21 mg/kg/day

UF = 100

MOE= 100	Residential MOE = 100

FQPA SF = 1X

Occupational MOE = 100	90-day oral toxicity study in dogs. LOAEL = 4.42
mg/kg/day based on observations of increased incidence of tremors in
both sexes.

Long-Term

(>6 months)

Inhalation	NOAEL= 1.3 mg/kg/day

UF = 100

MOE= 100	Residential MOE = 100

FQPA SF = 1X

Occupational MOE = 100	1-year oral toxicity in dogs. LOAEL = 2.7
mg/kg/day based on observations of increased incidence of tremors in
both sexes.

Cancer (oral, dermal, inhalation)	Classification:  Category C (possible
human carcinogen).  No Q1* has been derived. The RfD approach
recommended for cancer assessment.

UF = uncertainty factor, FQPA SF = FQPA Safety Factor, NOAEL =
no–observed-adverse-effect-level, LOAEL =
lowest-observed-adverse-effect-level, RfD = reference dose (a = acute, c
= chronic), PAD = population-adjusted dose, MOE = margin of exposure,
LOC = level of concern, N/A = Not Applicable.

3.3.1	  Levels of Concern for Margin of Exposure

The target MOEs for occupational and residential exposure risk
assessments are as follows:

  

Table 3.3.1. Levels of Concern for Margin of Exposure

Route

	Duration

	Short-Term

(1-30 days)	Intermediate-Term

(1-6 Months)	Long-Term

(>6 Months)

Occupational (Worker) Exposure

Dermal	100a	100	100

Inhalation	100	100	100

Residential (Non-Dietary) Exposure

Oral	100	100	100

Dermal	100	100	100

Inhalation	100	100	100

a Based on the conventional UF of 100X (10X for inter-species
extrapolation and 10X for intra-species variation).

3.3.2  Recommendation for Aggregate Exposure Risk Assessments

The toxicity endpoints selected for these routes of exposure may be
aggregated as follows:  for short-, intermediate- and long-term
aggregate exposure risk assessments, the oral, dermal and inhalation
(oral equivalent) routes can be combined because of the common toxicity
endpoints (clinical signs of neurotoxicity) via these routes.

3.4	  Endocrine Disruption

EPA is required under the Federal Food, Drug, and Cosmetic Act (FFDCA),
as amended by FQPA, to develop a screening program to determine whether
certain substances (including all pesticide active and other
ingredients) “may have an effect in humans that is similar to an
effect produced by a naturally occurring estrogen, or other such
endocrine effects as the Administrator may designate.”  Following
recommendations of its Endocrine Disruptor and Testing Advisory
Committee (EDSTAC), EPA determined that there was a scientific basis for
including, as part of the program, the androgen and thyroid hormone
systems, in addition to the estrogen hormone system.  EPA also adopted
EDSTAC’s recommendation that the Program include evaluations of
potential effects in wildlife. For pesticide chemicals, EPA will use the
Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and, to the
extent that effects in wildlife may help determine whether a substance
may have an effect in humans, FFDCA authority to require the wildlife
evaluations.  As the science develops and resources allow, screening of
additional hormone systems may be added to the Endocrine Disruptor
Screening Program (EDSP).  Bifenthrin database did not indicate any
endocrine mediated effects.  When additional appropriate screening
and/or testing protocols being considered under the Agency’s EDSP have
been developed, bifenthrin may be subjected to further screening and/or
testing to better characterize effects related to endocrine disruption. 


4.0  Dietary Exposure/Risk Characterization

4.1  Pesticide Metabolism and Environmental Degradation

References:

Bifenthrin TRED,   SEQ CHAPTER \h \r 1 S. Levy, 21-AUG-2002; DP# 283808

Bifenthrin: Human-health Risk Assessment for Proposed Uses on Cilantro,
Leafy Brassica Greens (subgroup 5b), Tuberous and Corm Vegetables
(Subgroup 1c), Dried Shelled Peas and Beans (except Soybean) (Subgroup
6c) and Tobacco. M. Rust-Clock, et. al. 4/6/2006

45794202.der

PP#7E7227; Bifenthrin (128825). Section 3 Registration Request for
Application of Bifenthrin to Bushberry (Crop Subgroup 13B), Juneberry,
Lingonberry, Salal, Aronia Berry, Lowbush Blueberry, Buffalo Currant,
Chilean Guava, European Barberry, Highbush Cranberry, Honeysuckle,
Jostaberry, Native Current, Sea Buckthorn, and Leaf Petioles (Crop
Subgroup 4B) and FMC Corporation’s Field Trial Data on Head Lettuce. 
Summary of Analytical Chemistry and Residue Data. Pending, W.D. Wassell,
DP#: 342661

  SEQ CHAPTER \h \r 1 Memo, M. Flood, 07/23/93,   SEQ CHAPTER \h \r 1
PP#7F3456

4.1.1  Metabolism in Primary Crops and Livestock

4.1.1.1  Metabolism in Primary Crops

  SEQ CHAPTER \h \r 1 The nature of bifenthrin residues in plants is
adequately understood based on the available metabolism studies with
corn, cotton, and apple.  HED previously determined that for purposes of
tolerance expression and risk assessment, the residue of concern in
cotton and apple commodities is bifenthrin per se (Memoranda, M. Flood,
12/24/87 and N. Dodd, 7/02/87).  After re-examining the cotton and apple
metabolism data and additional corn metabolism data, the HED Metabolism
Committee (Memo, M. Flood, 7/23/93) reaffirmed that the residue of
concern in plant commodities is bifenthrin per se.

In conjunction with a previous risk assessment for use on tuberous and
corm vegetables, IR-4 submitted a metabolism study on potatoes
reflecting both soil and foliar applications of [14C] bifenthrin.  The
potato study is adequate and the results from the metabolism study
support HED’s previous determination that the residue of concern is
bifenthrin per se.  The bifenthrin review team agrees with these
decisions.

4.1.1.2  Metabolism in Livestock

Adequate studies are available depicting the metabolism of
[14C]bifenthrin in ruminants and poultry.  The nature of the residue in
livestock is adequately understood based on goat and hen metabolism
studies.  The HED Metabolism Committee determined that for purposes of
tolerance expression and risk assessment, the residue of concern in
livestock is bifenthrin per se (Memo, M. Flood, 7/23/93).  The
bifenthrin review team agrees with this decision.

4.1.2  Metabolism in Rotational Crops

Adequate confined and field rotational crop studies are available. 
Based on the confined study, HED has concluded that the residue of
concern in rotational crops is the parent compound only.  The bifenthrin
review team agrees with this decision.

4.1.3  Analytical Methodology

Adequate gas chromatography/electron-capture detection (GC/ECD) methods
are available for enforcing tolerances for bifenthrin residues in plant
and livestock commodities.  The available methods for plant commodities
generally involve extraction of the sample with acetone, partitioning
with hexane, purification using a Florisil column, and analysis of
residues by GC/ECD.  The limit of quantitation (LOQ) for these methods
is 0.05 ppm.  

Residues of bifenthrin in/on blueberry and celery were determined using
a GC/ECD method (FMC Report P-2132M).  For this method, residues are
extracted with hexane using the Dionex ASE-200, concentrated, and
cleaned up using a Florisil column, then analyzed by GC/ECD.  The
validated LOQ for bifenthrin is 0.05 ppm, and the reported limit of
detection (LOD) is 0.01 ppm. The method was adequately validated in
conjunction with analysis of samples from the field trials.

4.1.4  Environmental Degradation

References:

Tier I Estimated Environmental Concentrations of Bifenthrin for the Use
in the Human-Health Risk Assessment. 03/05/2008, J. Melendez

Memo, 6/21/2002, S. Knizer, TXR# 0050887

  SEQ CHAPTER \h \r 1 The environmental fate database for bifenthrin is
complete enough to characterize drinking water exposure.  The submitted
data indicate that bifenthrin is relatively persistent under both
laboratory and field conditions.  Bifenthrin is relatively immobile in
four soils tested.  Due to its low mobility, bifenthrin is not likely to
reach subsurface soil environments (lower microbial activity) or ground
waters.  Various terrestrial field dissipation studies confirm that
bifenthrin remains mostly in the upper soil level.  Due to its low
solubility and high level of binding it appears that bifenthrin would
remain bound to the soils during run-off events and it may reach surface
waters if the run-off event is accompanied by erosion.

The HED MARC concluded that the parent compound, bifenthrin per se,
should be the residue of concern for risk assessment in drinking water
based on its persistence and the absence of major degradates in
laboratory studies (Memo, 6/21/2002, S. Knizer, TXR# 0050887).  The
bifenthrin review team agrees with this decision.

4.1.5  Food Residue Profile

The field trials with bifenthrin on celery and blueberries are   SEQ
CHAPTER \h \r 1 adequate.  An adequate number of trials were conducted
reflecting the proposed use patterns in the appropriate geographic
regions, and the appropriate commodities were collected at the proposed
PHIs.  Samples were analyzed using adequate analytical methods. 
Tolerance levels for residues in/on bushberry (subgroup 13-07B) and leaf
petioles (subgroup 4B) were determined using the North American Free
Trade Agreement (NAFTA) maximum residue limits (MRL)/Tolerance
Harmonization Spreadsheet. 

Blueberries:  IR-4 has submitted field trial data for the use of
bifenthrin on blueberries.  At each trial site, five foliar
directed/broadcast applications of the 2 lb/gal EC formulation were made
at 4- to 8-day RTIs to blueberries at 0.093-0.106 lb ai/A/application,
for a total seasonal rate of 0.498-0.507 lb ai/A.  At four trials, a
second treated plot received five foliar direct/broadcast applications
of 10% WP at 0.096-0.102 lb ai/A/application, with 6- to 8-day RTIs, for
a total seasonal rate of 0.492-0.499 lb ai/A.  At each trial, samples
were harvested at commercial maturity, 1 day after the last application
of bifenthrin.  In the submitted field trials, maximum residues of
bifenthrin were 1.61 ppm and 1.06 ppm, respectively, for trials with the
EC and WP formulations.  The results of the blueberry trials are
summarized in Table 4.1.5a.

Table 4.1.5a.  Summary of Residue Data from Blueberry Field Trials with
Bifenthrin.

Commodity	Total Applic. Rate

 (lb ai/A)	PHI (days)	EP	Residue Levels  (ppm)





n	Min.	Max.	HAFT1	Mean	Std. Dev.

Proposed Use Pattern:  Maximum Seasonal Rate of 0.5 lb ai/A with a 1-day
PHI.

Blueberry	0.498-0.509	1	2 lb/gal EC	18	0.36	1.61	1.36	0.80	0.34

	0.492-0.499	1	10% WP	8	0.37	1.06	0.91	0.65	0.28

1  HAFT = Highest-Average Field Trial result.

Celery:  IR-4 has submitted field trial data for the use of bifenthrin
on celery in response to a data gap specified in DP# 277993 (8/15/02, S.
Levy).  At each treated plot, five foliar directed/broadcast
applications of either the 2 lb/gal EC or 10%WP formulation of
bifenthrin were made at 6- to 8-day RTIs to celery at 0.096-0.106 lb
ai/A/application, for a total seasonal rate of 0.497-0.515 lb ai/A. 
Celery samples were harvested at commercial maturity, 6- to 8-days after
the last application of bifenthrin.  In these trials, residues of
bifenthrin were 0.11-1.78 ppm and 0.06-1.16 ppm in/on celery,
respectively, for trials with the EC and WP formulations.  

Table 4.1.5b.  Summary of Residue Data from Celery Trials with
Bifenthrin.

Commodity	EP	Total Applic.

Rate 

(lb ai/A)	PHI

(days)	Residue Levels (ppm)





N	Min.	Max.	HAFT1	Mean	Std. Dev.

Proposed Use Pattern:   Maximum Seasonal Rate of 0.5 lb ai/A with a
7-day PHI.

Celery	2 lb/gal EC	0.497-0.514	6-7	8	0.11	1.78	1.49	0.75	0.54

Celery	10% WP	0.499-0.515	6-7	8	0.06	1.16	1.07	0.56	0.38

1  HAFT = Highest-Average Field Trial result.

  SEQ CHAPTER \h \r 1 4.1.5.1  Tolerance Summary

The bifenthrin tolerances proposed by the registrants in the subject
petition are listed below in Table 4.1.5.1, along with HED’s
recommended tolerance levels.   SEQ CHAPTER \h \r 1  Tolerance levels
for residues of bifenthrin in/on bushberries (subgroup 13-07B) and leaf
petioles (subgroup 4B) were determined using the NAFTA MRL/Tolerance
Harmonization Spreadsheet. 

Table 4.1.5.1.  Tolerance Summary for Bifenthrin in/on Bushberries and
Leaf Petioles.

Crop Group or Commodity	Proposed Tolerance (ppm)	Recommended Tolerance
(ppm)	Comments; Correct Commodity Definition

Bushberry subgroup 13B	2.0	1.8	Bushberry subgroup 13-07B

Juneberry	2.0	Not needed	Separate tolerances for new commodities listed
in crop subgroup 13-07B are no longer required; refer to the Final Rule
published in the Federal Register 12/7/07.

Lingonberry	2.0



Salal	2.0



Aronia berry	2.0



Blueberry, lowbush	2.0



Buffalo currant	2.0



Chilean guava	2.0



European barberry	2.0



Highbush cranberry	2.0



Honeysuckle	2.0



Jostaberry	2.0



Native currant	2.0



Sea buckthorn	2.0



Leaf petioles subgroup 4B	3.0	3.0

	

4.1.6  International Residue Limits

There are currently no established Codex, Canadian, or Mexican MRLs for
bifenthrin in/on the proposed commodities.  Therefore, harmonization is
not an issue for the subject petition.  

  SEQ CHAPTER \h \r 1 

4.1.7  Drinking Water Residue Profile

Drinking Water Estimates

The EDWCs for bifenthrin were calculated based on a maximum application
rate of 0.5 lb ai/A/season to lettuce.  The acute drinking water
concentration in surface water is 0.0140 ppb of bifenthrin, based on
aerial applications to lettuce.  The cancer/chronic drinking water
concentration is 0.0140 ppb (based on applications of lettuce, highest
application rate).  The SCI-GROW generated EDWC is 0.003 ppb of
bifenthrin, which is recommended for use in both acute and chronic
exposures.  Because of the very low solubility of bifenthrin, the EDWCs
did not exceed 0.0140 ppb (the solubility of bifenthrin in water).



Table 4.1.7.  Tier 1 Estimated Drinking Water Concentrations for
Bifenthrin.

Drinking Water Source    (Model Used) 	Use (Rate Modeled)	Maximum EDWC  
                                    (ppb) 

Groundwater (SCI-GROW)	Lettuce (0.5 lb. ai/A/season)	Acute and Chronic
0.0030

Surface water  (FIRST)	Lettuce (0.5 lb. ai/A/season)	Acute	0.0140

	Lettuce (0.5 lb. ai/A/season)	Chronic	           0.0140



4.2  Dietary Exposure and Risk

Acute and chronic dietary exposure and risk assessments were conducted
using DEEM-FCID™, Version 2.03, which uses food consumption data from
the USDA’s CSFII from 1994-1996 and 1998.    SEQ CHAPTER \h \r 1 The
analyses were performed as part of a registration action; (1) to support
a Section 3 Registration for use on bushberries (subgroup 13-07B) and
leaf petioles (subgroup 4B); and (2) to include drinking water estimates
reflecting the new uses.

EFED calculated the ground and surface drinking water Tier 1 EDWCs for
bifenthrin new uses using SCI-GROW and FIRST models.  It was found that
lettuce is still the use with the major exposure and the highest PCA,
and, therefore, the drinking water assessment results did not change
from the previous ones.  The EDWCs for bifenthrin were calculated based
on a maximum application rate of 0.5 lb ai/A/season and the EDWCs in
ground water were estimated as 0.003 ppb and 0.014 ppb in surface water.

4.2.1  Acute Dietary Exposure and Risk

A highly-refined, acute probabilistic dietary exposure and risk
assessment was conducted for all supported (and pending) food uses and
drinking water.  ARs were developed based on the latest USDA PDP
monitoring data 1998-2005, FDA data, or field trial data for bifenthrin.
ARs were further refined using the latest %CT data and processing
factors where appropriate.  The EDWC of 0.014 ppb, based on application
to lettuce at the highest application rate, was used to account for
exposure from residues in water.

The acute dietary exposure estimates for food and drinking water are
below HED’s level of concern (<100% aPAD) at the 99.9th percentile of
exposure.  Bifenthrin dietary exposure at the 99.9th percentile for food
and drinking water is 10% of the aPAD for the U.S. population and 25% of
the aPAD for all infants (<1 year old), the most highly-exposed
population subgroup.



Table 4.2.1.  Results of Bifenthrin Acute Dietary (Food + Drinking
Water)

Exposure Analysis Using DEEM FCID.

Population Subgroup	aPAD (mg/kg/day)	99.9th Percentile



Exposure (mg/kg/day)	% aPAD

General U.S. Population	0.33	0.034	10

All Infants (< 1 year old)	0.33	0.084	25

Children 1-2 years old	0.33	0.059	18

Children 3-5 years old	0.33	0.052	16

Children 6-12 years old	0.33	0.044	13

Youth 13-19 years old	0.33	0.026	8.0

Adults 20-49 years old	0.33	0.018	5.5

Adults 50+ years old	0.33	0.014	4.4

Females 13-49 years old	0.33	0.018	5.4



4.2.2  Chronic Dietary Exposure and Risk

A refined chronic dietary exposure assessment was also conducted for
drinking water and the supported food uses of bifenthrin using single
point estimates of anticipated bifenthrin residues, including %CT for
food/feed crops.  The EDWC of 0.014 ppb, based on application to lettuce
at the highest application rate, was used for the chronic dietary
assessment.

The chronic dietary exposure estimates for food and drinking water are
below HED’s level of concern (<100% cPAD) for the U.S. population and
all population subgroups.  Bifenthrin dietary exposure for food and
drinking water is 21% of the cPAD for the U.S. population and 55% of the
cPAD for children 3 to 5 years old, the most highly-exposed population
subgroup.



Table 4.2.2. Results of Chronic Dietary (Food + Drinking Water)
Exposure and Risk for Bifenthrin.

Population Subgroup	Chronic Dietary

	Dietary Exposure

(mg/kg/day)	% cPAD

General U.S. Population	0.0028	21

All Infants (< 1 year old)	0.0030	23

Children 1-2 years old	0.0067	52

Children 3-5 years old	0.0072	55

Children 6-12 years old	0.0053	41

Youth 13-19 years old	0.0027	21

Adults 20-49 years old	0.0020	16

Adults 50+ years old	0.0018	14

Females 13-49 years old	0.0021	16



5.0 	 Residential (Non-Occupational) Exposure/Risk Characterization

Bifenthrin: REVISED Residential Exposure Assessment and Recommendations
for the Tolerance Reassessment Eligibility Decision (TRED) Document. S.
Weiss. D286358. 10/25/2002. 

Bifenthrin products are available to homeowners for indoor and outdoor
application to residential premises.  Adults and children may be
potentially exposed to bifenthrin residues resulting from application.  

Potential exposure and risk to residents (or “homeowners”) have been
assessed previously by HED.  Information for this section was adapted
from previous residential assessment for bifenthrin performed in 2002
(see reference above).  Since completion of the last residential
assessment, no product cancellations or new uses have occurred that
would alter the conclusions. A summary of the exposure and risk
resulting from residential uses of bifenthrin is provided below.  These
exposure estimates were used in the aggregate risk assessment which
appears in Section 7.0 of this document.  

5.1  Residential Handler Exposure

End-use products containing bifenthrin are formulated as
ready-to-use-sprays, emulsified concentrates, wettable powders,
granulars, pelletized tablets, and pressurized liquids.  

The current maximum application rates of granulars and liquids by
lawn-care operators (LCOs) are 0.4 and 0.3 lb ai/acre, respectively. 
For liquid and granular formulations applied by homeowners, the maximum
rate is 0.2 lb ai/acre.  In a letter to the Agency dated September 16,
2002, FMC agreed to lower the maximum rate for all turf uses to 0.2 lb
ai/acre.  Bifenthrin products may be applied by pest-control operators
(PCOs) and homeowners in and around homes as a spray in concentrations
of up to 0.06%.  The majority of residential labels do not specify
frequency of application.  

Short- and intermediate-term exposures may occur for residents applying
bifenthrin products.  Chronic exposures are not anticipated for
residential handlers.  The exposure and risk for residential handlers
were assessed using the revised draft SOPs for Residential Exposure
Assessment, and includes surrogate data from the Pesticide Handlers
Exposure Database (PHED) Outdoor Residential Exposure Task Force
(ORETF).  Since PHED and ORETF do not include data for ready-to-use
spray bottle application, data from a proprietary study were used to
estimate exposure (MRID 44739301). 

The major exposure scenarios for non-occupational (residential) handler
exposures are as follows:	

	*  Mixing/loading/applying liquids for low-pressure handwand
application.

	*  Mixing/loading/applying liquids for hose-end sprayer application.

	*  Mixing/loading/applying liquids for backpack sprayer application.

	*  Paintbrush application.

	*  Loading/applying a granular for belly-grinder application.

	*  Loading/applying a granular for push-type spreader application.

	*  Applying a granular with bare hands.

	*  RTU spray bottle application.

The most likely residential handler exposure scenario resulting in the
highest exposure and risk is for loading/applying granular formulation
by belly-grinder application.  The short- and intermediate-term MOEs are
300 for dermal and 25,000 for inhalation, resulting in a combined MOE of
300.  The exposure for this use is not of concern to HED.  

5.2	  Residential Post-application Exposure

Adults and children may be potentially exposed to bifenthrin residues
after application of bifenthrin products in residential settings. 
Short- and intermediate-term post-application dermal exposures for
adults, and short- and intermediate-term post-application dermal and
incidental oral exposures for children are anticipated.  Long-term
exposure is not expected.  Risk estimates were generated for potential
contact with lawn, soil, and treated indoor surfaces using HED’s Draft
SOPs for Residential Exposure Assessment, and for the lawn scenarios,
dissipation data from a chemical-specific TTR study.  Indoor surface
residues in homes were based on crack and crevice data collected for
bifenthrin and malathion.  These estimates are considered conservative
screening level estimates, since the study data were adjusted to reflect
maximum application rates.  The scenarios that result in the highest
exposure are summarized in Table 5.2. 



Table 5.2. Summary of Residential Post-Application Risk for Bifenthrin.

Exposure Scenario	Population	Route of Exposure	Short-Term MOE
Intermediate-Term MOE

Indoor: High- Contact Activity	Adults	Dermal	3100	3100

	Toddlers	Dermal

Oral	1800

2600	1800

5500

Outdoor:

High-Contact Activity on Turfgrass	Adults	Dermal	2300	4500

	Toddler	Oral and Dermal	740 Oral

1400 Dermal	1600 Oral

2700 Dermal



5.3  Other (Spray Drift)

Spray drift is always a potential source of exposure to residents nearby
to spraying operations.  This is particularly the case with aerial
application, but, to a lesser extent, could also be a potential source
of exposure from the ground application method employed for bifenthrin. 
The Agency has been working with the Spray Drift Task Force, EPA
Regional Offices and State Lead Agencies for pesticide regulation and
other parties to develop the best spray drift management practices.  On
a chemical by chemical basis, the Agency is now requiring interim
mitigation measures for aerial applications that must be placed on
product labels/labeling.  The Agency has completed its evaluation of the
new database submitted by the Spray Drift Task Force, a membership of
U.S. pesticide registrants, and is developing a policy on how to
appropriately apply the data and the AgDRIFT® computer model to its
risk assessments for pesticides applied by air, orchard airblast and
ground hydraulic methods.  After the policy is in place, the Agency may
impose further refinements in spray drift management practices to reduce
off-target drift with specific products with significant risks
associated with drift.

6.0	  Aggregate Risk Assessments and Risk Characterization

In accordance with the FQPA, HED must consider and aggregate pesticide
exposures and risks from three major sources:  food, drinking water, and
residential exposures.  In an aggregate assessment, exposures from
dietary and residential sources are added together and compared to
quantitative estimates of hazard (e.g., a NOAEL), or the risks
themselves can be aggregated.  When aggregating exposures and risks from
various sources, HED considers both the route and duration of exposure.

Short-term aggregate risk assessment is required for bifenthrin due to
the potential for residential exposure.  The common toxicological effect
observed across the oral and dermal routes of exposure is clinical signs
of neurotoxicity.  An aggregate MOE was calculated by taking the inverse
of the sum of inverse MOEs for dietary and non-dietary (incidental oral
and dermal) exposure pathways.

6.1  	Acute Aggregate Risk

No acute residential/recreational exposures are expected.  Since the
dietary assessment included food and water, the exposures in Table 5.2.1
represent acute aggregate exposures.  The acute aggregate risk estimates
are not of concern to HED. 

6.2	  Short- and Intermediate-Term Aggregate Risk

Because there is the potential for short- and intermediate-term,
non-dietary exposure of children and adults to bifenthrin as a
residential treatment (indoors and outdoors), it is appropriate to
aggregate these exposures with dietary (food and water) exposure. 
Adults can be exposed through the residential application of bifenthrin
via dermal and inhalation routes and through post-application exposure
via the dermal route (treated turf).  Children might be exposed
following application in residential settings via dermal and incidental
oral routes.  HED believes that if a toddler were to be exposed to
bifenthrin granules, it would most likely be episodic; that is, a
one-time occurrence, and not likely to be repeated.  Therefore, this
episodic scenario was not aggregated with dietary exposure.

Residential exposure and risk have been summarized based on HED
residential risk assessments for the existing uses of bifenthrin.  Those
scenarios resulting in the highest exposure and risk for adults and
children have been summarized in Table 6.2.1.  These exposures were used
to calculated short- and intermediate-term aggregate risk by combining
residential exposure with that from dietary sources.

Table 6.2.1.  Summary of Residential Risk Resulting in Highest Exposure
and Risk for Bifenthrin.

Population	Exposure Scenario	Route of Exposure	Short-Term MOE

Adults	Loading/applying granulars with a belly-grinder	Handler	Dermal
and Inhalation	300 Dermal

25,000 Inhalation

	Hose-end Sprayer Application	Handler	Dermal and Inhalation	97,000
Inhalation

3000 Dermal



Post-Application	Dermal	2300

	Liquid Structural Wood Treatment with Paintbrush	Handler	Dermal and
Inhalation	23,000 Inhalation

600 Dermal



Post-Application	No exposure expected due to low accessibility to
treated areas (termite control).

	Indoor: 

Liquid Crack and Crevice Spray	Handler	Dermal and Inhalation	210,000
Inhalation

14,000 Dermal



Post-Application	Dermal	3100

Toddler	Outdoor:

High Contact Activity on Turfgrass	Post-Application	Hand-to- Mouth/Oral
740



	Mouthing Treated Turf	3000



	Soil Ingestion	220,000



	Dermal	1400

1 Combined MOE for handlers since dermal and inhalation endpoints
(clinical signs) [1/(1/MOE-dermal)+(1/MOE-inhalation)]. 

The short- and intermediate-term NOAEL for non-dietary oral exposure is
based on the 90-day oral toxicity study in dogs (NOAEL = 2.21
mg/kg/day).  The short- and intermediate-term NOAEL for dermal exposure
is based on the 21-day dermal toxicity study in the rat (NOAEL = 47
mg/kg/day).  The common toxicological effect observed across the oral
and dermal routes of exposure is clinical signs of neurotoxicity.  The
aggregate LOC (MOE) is 100.

The results of the short- and intermediate-term aggregate risk
assessment for various subpopulations based on age are reported in Table
6.2.2.  Short- and intermediate-term aggregate (dietary + residential)
MOEs for the general U.S. population and any subpopulation of the
general U.S. population are greater than or equal to 180 and therefore
are not of concern to HED.

Table 6.2.2.  Short- and Intermediate-Term Aggregate Risk for
Bifenthrin.

Population	Dietary MOE1	Non-dietary Oral MOE2	Dermal MOE3	Inhalation
MOE4	Aggregate MOE5

General U.S. Population	790	N/A	300	25,000	220

All Infants         (<1 yr old)	740	590	1400	N/A6	270

Children 1-2 yrs. Old	330	590	1400

180

Children 3-5 yrs. Old	310	590	1400

180

Children 6-12 yrs. Old	420	N/A	1400

320

Youth 13-19 yrs. Old	820

1400

520

Adults 20-49 yrs. Old	1100

300	25,000	230

Adults 50+ yrs. Old	1200

300	25,000	240

Females 13-49 yrs. Old	1100

260	25,000	210

1 Dietary MOE = [(short- or intermediate-term oral NOAEL)÷(chronic
dietary exposure)]; NOAEL = 2.21 mg/kg/day; chronic dietary (food +
water) exposures (see Table 5.2.2) were utilized as surrogates for
short- and intermediate-term exposures. 

2 Non-dietary oral MOE = [(short- or intermediate-term oral NOAEL)÷(sum
of all high-end incidental oral residential exposure)]; NOAEL=2.21
mg/kg/day; chronic dietary (food + water) exposures (see Table 4.2.2)
were utilized as surrogates for short- and intermediate-term exposures.

3 Dermal MOE = [(short- or intermediate-term dermal NOAEL)÷(high-end
dermal residential exposure)]; NOAEL=47 mg/kg/day; structural wood
treatment (paintbrush application) used for adult estimates.

4 Inhalation MOE = [(short- or intermediate-term inhalation
NOAEL)÷(high-end dermal residential exposure)]; NOAEL=2.21 mg/kg/day.

5 Aggregate MOE (dietary and residential) = 1÷[(1÷dietary MOE) +
(1÷non-dietary oral MOE) + (1÷dermal MOE) + (1÷inhalation MOE)];
values expressed to 2 significant figures; Inhalation MOE based on adult
residential handler exposure. 

6 N/A = not applicable.

6.3  Long-Term (Chronic) Aggregate Risk

A chronic (non-cancer) aggregate risk assessment was not performed,
because chronic residential exposure to bifenthrin (i.e., >6 months) is
not considered likely to occur based upon the use patterns.

6.4	  Cancer Risk

The CARC (1992) recommended that for the purpose of risk
characterization, the RfD approach should be used for quantification of
human risk.  The chronic exposure analysis revealed <100% RfD, and it is
assumed that the chronic dietary endpoint is protective for cancer
dietary exposure.

7.0  	Cumulative Risk Characterization/Assessment

Bifenthrin is a member of the pyrethroid class of pesticides.  EPA is
not currently following a cumulative risk approach based on a common
mechanism of toxicity for the pyrethroids.  Although all pyrethroids
alter nerve function by modifying the normal biochemistry and physiology
of nerve membrane sodium channels, available data show that there are
multiple types of sodium channels and it is currently unknown whether
the pyrethroids as a class have similar effects on all channels or
whether modifications of different types of sodium channels would have a
cumulative effect.  Nor do we have a clear understanding of effects on
key downstream neuronal function, e.g., nerve excitability, or how these
key events interact to produce their compound specific patterns of
neurotoxicity.  Without such understanding, there is no basis to make a
common mechanism of toxicity finding.  There is ongoing research by the
EPA’s Office of Research and Development and pyrethroid registrants to
evaluate the differential biochemical and physiological actions of
pyrethroids in mammals.  When available, the Agency will consider this
research and make a determination of common mechanism as a basis for
assessing cumulative risk.  For information regarding EPA’s procedures
for cumulating effects from substances found to have a common mechanism
on EPA’s website at   HYPERLINK
"http://www.epa.gov/pesticides/cumulative/" 
http://www.epa.gov/pesticides/cumulative/ .

8.0	  Occupational Exposure/Risk Pathway

8.1  Short-/Intermediate-Term Handler Risk

Based upon the proposed use pattern, HED expects the most highly-exposed
occupational pesticide handlers (mixers, loaders, applicators) to be: 
1) mixer/loader using open-pour loading of liquids; 2) an aerial
applicator, 3) an applicator using open-cab, ground-boom spray
equipment.  A mixer/loader loading water-soluble packages is NOT
assessed.  HED considers water-soluble packaging to be a "closed loading
system" thereby reducing exposures to negligible amounts.  Exposure from
handling water-soluble packages is expected to be less than that
experienced by mixer/loaders using open-pour techniques.  HED believes
most exposure durations will be short-term (1-30 days).  However, the
ExpoSAC maintains that it is possible for commercial applicators to be
exposed to intermediate-term exposure durations (1-6 months). 
Therefore, estimates for short- and intermediate-term risks are
presented.  

It is expected that some private applicators may perform all tasks; that
is, mix, load and apply the material.  However, HED ExpoSAC draft SOP
(dated:  3/29/00) directs that although the same individual may perform
all tasks, in some cases they shall be assessed separately.  The
available exposure data for combined mixer/loader/applicator scenarios
are limited in comparison to the monitoring of these two activities
separately.  These exposure scenarios are outlined in the PHED Surrogate
Exposure Guide (August 1998).  HED has adopted a methodology to present
the exposure and risk estimates separately for the job functions in some
scenarios and to present them as combined in other cases.  Most exposure
scenarios for hand-held equipment (such as handwands, backpack sprayers,
and push-type granular spreaders) are assessed as a combined job
function.  With these types of hand-held operations, all handling
activities are assumed to be conducted by the same individual.  The
available monitoring data support this and HED presents them in this
way.  Conversely, for equipment types such as fixed-wing aircraft,
groundboom tractors, air-blast sprayers, or high-pressure handwand
sprayers, the applicator exposures are assessed and presented separately
from those of the mixers and loaders.  By separating the two job
functions, HED determines the most appropriate levels of protective
equipment (PPE) for each aspect of the job without requiring an
applicator to wear unnecessary PPE that might be required for a
mixer/loader (e.g., chemical-resistant gloves may only be necessary
during the pouring of a liquid formulation).  

No chemical-specific data were available with which to assess potential
exposure to occupational pesticide handlers.  The estimates of exposure
to pesticide handlers are based upon surrogate study data available in
the PHED (v. 1.1, 1998).  For pesticide handlers, it is HED standard
practice to present estimates of dermal exposure for “baseline”;
that is, for workers wearing a single layer of work clothing consisting
of a long-sleeved shirt, long pants, shoes plus socks and no protective
gloves as well as for “baseline” and the use of protective gloves or
other PPE as might be necessary.  

The RAB1 toxicology team also identified short- and intermediate-term
inhalation toxicological endpoints.  The inhalation endpoints are
identified from a 90-day oral toxicity study in dogs.  The observations
were increased incidence of tremors in both sexes.  The NOAEL is 2.21
mg/kg bw/day.  MOEs less than 100 are of concern to HED.  

The CARC (1992) has characterized bifenthrin as Category C (possible
human carcinogen) and recommended that for the purpose of risk
characterization, the RfD approach should be used for quantification of
human cancer risk.  Since no cancer potency factor was identified, a
cancer risk assessment is not necessary.

See Table 8.1 for a summary of estimated exposures and risks to
occupational pesticide handlers. In this case, the toxicological effects
are similar (i.e., clinical signs of neurological) for the dermal and
inhalation routes although they were identified from different studies. 
Therefore, separate dermal and inhalation MOEs were calculated which
were then used to calculate combined MOEs.



Table 8.1.  Summary of Exposure & Risk for Occupational Handlers
Applying Bifenthrin.

Unit Exposure1

Mg ai/lb handled	Applic. Rate2

lb ai/unit	Units Treated3	Avg. Daily Exposure4

mg ai/kg bw/day	MOE5	Combined

MOE6

Mixer/Loader Using Open-Pour Liquid

Dermal:

SLNoGlove     2.9 HC

SLWithGlove  0.023 HC

Inhal.             0.0012 HC	0.1 lb ai/A	350 A/day	Dermal:

SLNoGlove    1.45

SLWithGlove  0.012

Inhal.              0.0006	

32

3,900

3,700	

32

1,900

Aerial Applicator (Pilots  not required to wear gloves)

Dermal:

SLNoGlove 0.0050 MC

SLWithGlove

Inhal        0.000068 MC	0.1 lb ai/A	350 A/day	Dermal:

SLNoGlove    0.0025

Inhal.          0.000034	

19,000

65,000	

15,000

Applicator Open-cab Ground-boom

Dermal:

SLNoGlove   0.014 HC   

SLWithGlove0.014 MC

Inhal.               0.00074 HC	0.1 lb ai/A	200 A/day	Dermal:

SLNoGlove    0.004

SLWithGlove 0.004

Inhal.           0.00021	

12,00

12,000

11,000	

5,600

5,600

1.  Unit Exposures are taken from “PHED SURROGATE EXPOSURE GUIDE”,
Estimates of Worker Exposure from The Pesticide Handler Exposure
Database Version 1.1, August 1998.   Inhal. = Inhalation.  Units = mg
ai/pound of active ingredient handled.  Data Confidence: LC = Low
Confidence, MC = Medium Confidence, HC = High Confidence.

2.  Applic. Rate = Taken from the proposed label.

3.  Units Treated are taken from “Standard Values for Daily Acres
Treated in Agriculture”; SOP No. 9.1.   Science Advisory Council for
Exposure; Revised July 5, 2000.

4.  Average Daily Dose (ADD) = Unit Exposure * Application Rate * Units
Treated  ( 70 kg body weight.   Dermal unit exposures not corrected for
dermal absorption since the dermal toxicological endpoints were derived
from a 21-day dermal study.  Inhalation assumes 100% absorption.

5.  MOE = NOAEL ( ADD.   Dermal NOAEL = 47 mg/kg bw/day.  Inhalation
NOAEL = 2.21 mg/kg bw/day.  

6.  MOEs may be combined when the dermal and inhalation toxicological
effect is the same though identified from different studies.  The
convention used to combine is   1/(1/MOEDERMAL + 1/MOEINHALATION).

An MOE of 100 is adequate to protect occupational pesticide handlers
from exposures to bifenthrin.  In this case, provided mixer/loaders wear
protective gloves, all MOEs are >100.  The lowest combined MOE is
>1,800.  Therefore these exposures are not of concern to HED.

8.2  Short-/Intermediate-Term Post-application Risk

Typically there is the possibility for agricultural workers to
experience post-application exposure to dislodgeable pesticide residues.
 In conjunction with the Agricultural Re-Entry Task Force (ARTF), HED
has identified a number of agricultural work activities that may result
in post-application, re-entry exposure to pesticides.  In addition, HED
has identified surrogate transfer coefficients (TCs) in units of cm²/hr
derived from exposure studies relative to “standard” agricultural
work activities but which were conducted to assess exposure to other
compounds. 

For the proposed new crop uses, the activity with the highest TC is hand
harvesting.  For leaf petiole vegetables, hand harvesting has a TC of
2,500 cm2/hr; hand harvesting for low-bush blueberries, the TC is 1,500
cm2/hr; hand harvesting for high-bush blueberries, the TC is 5,000
cm2/hr.  

Since there are no chemical-specific data with which to assess
post-application exposures to agricultural workers, RD uses 5,000 cm2/hr
TC in conjunction with the assumption that 20% of the rate of
application is available as dislodgeable foliar residue on day zero
after application.  The estimated post-application exposure is believed
to be conservative (i.e., protective).

The TCs used in this assessment are from an interim TC policy developed
by HED’s ExpoSAC using proprietary data from the ARTF database (SOP #
3.1 Revised 7 AUG 2000).  It is the intention of HED’s ExpoSAC that
this policy will be periodically updated to incorporate additional
information about agricultural practices in crops and new data on TCs. 
Much of this information will originate from exposure studies currently
being conducted by the ARTF, from further analysis of studies already
submitted to the Agency, and from studies in the published scientific
literature.  The following convention may be used to estimate
post-application exposure to agricultural workers.

Surrogate Dislodgeable Foliar Residue: 

DFR = application rate * 20 % available as dislodgeable foliar residue *
4.54 x 108 µg/lb * 2.47 x 10-8 A/cm2 or 1.08 x 10-3 ft2/cm²

and the Average Daily Dose

ADD = DFR (µg/cm2) * TC (cm2/hr) * hr/day * 0.001 mg/µg * 1/70 kg bw 

(  0.1 lb ai/A * 0.20 * 4.548 µg/lb *  2.47 x 10-8 A/cm² = 0.225
µg/cm2 and

0.225 µg/cm2 * 5,000 cm2/hr * 8 hr/day * 0.001 mg/µg * 1/70 kg bw =
0.128 mg/kg bw/day

Since MOE = NOAEL ( ADD then 47 mg/kg bw/day ( 0.128 mg/kg bw/day = 370

The MOE for the most highly-exposed post-application agricultural
activity is greater than 100 (370).  Therefore, the proposed uses are
not of concern to HED.  All other relevant post-application activities
for the proposed use pattern are expected to have lower exposures
therefore greater MOEs.  

RESTRICTED ENTRY INTERVAL (REI)

The four product labels associated with this assessment list an REI of
12 hours.  Bifenthrin is classified in Acute Toxicity Category III for
acute dermal toxicity.  It is classified in Acute Toxicity Category IV
for acute inhalation toxicity, for primary eye irritation and primary
skin irritation.  It is not a dermal sensitizer.  Therefore, the interim
WPS REI of 12 hours is adequate to protect agricultural workers from
post-application exposures to bifenthrin.  

9.0  	Data Needs and Label Requirements

9.1  Toxicology

None.

9.2  Residue Chemistry

Revised Section B/proposed label.

Revised Section F/proposed tolerances.

9.3  Occupational and Residential Exposure

None.

RDI: RAB1: 03/19/2008

Petition Number:  PP#7E7227

DP Number:  350900

PC Code:  128825

WDWassell:S10316:Potomac Yard:703-305-6135:7509P:RAB1

Appendix 1:  Subchronic, Chronic and Other Toxicity Profile

Guideline No. 	Study Type	MRID No. (year)/ Classification /Doses	Results

870.3100

	90-Day oral toxicity (rat)	00141199 (1984)

Acceptable/guideline

M:  0, 0.88, 3.8, 7.5, 15 mg/kg/day

F:  0, 1.04, 4.3, 8.5, 17.2 mg/kg/day	NOAEL=M/F: 3.8/4.3 mg/kg/day

LOAEL=M/F: 7.5/8.5 mg/kg/day based on increased incidence of tremors.

870.3150

	90-Day oral toxicity (dog)	00141200 (1984)

Acceptable/guideline

0, 2.21, 4.42, 8.84, 17.7 mg/kg/day	NOAEL =M/F: 2.21 mg/kg/day

LOAEL = M/F: 4.42 mg/kg/day based on based on increased incidence of
tremors.



870.3200

	21/28-Day dermal toxicity (rat)	45280501 (2000)

Acceptable/guideline

0, 23, 47, 93, 932 mg/kg/day	NOAEL = 47

LOAEL = 93 mg/kg/day based on staggered gait and exaggerated hindlimb
flexion.  

870.3200

	21/28-Day dermal toxicity (rabbit)	00141198 (1984)

Acceptable/guideline

0, 22, 44, 88 442 mg/kg/day	NOAEL = 88 mg/kg/day

LOAEL = 442 mg/kg/day based on loss of muscle coordination and increased
incidence of tremors.   

870.3700a

	Prenatal developmental in (rat, gavage)	00154482 (1983)

Acceptable/non-guideline

0, 0.44, 0.88, 1.77, 2.2 mg/kg/day	Maternal NOAEL = 0.88 mg/kg/day

LOAEL = 1.77 mg/kg/day based on tremors during gestation.

Developmental NOAEL and LOAEL were not established (fetuses were not
examined).

870.3700a

	Prenatal developmental in (rat, gavage)	00141201 (1984)

Acceptable/guideline

0, 0.44, 0.88, 1.77 mg/kg/day	Maternal NOAEL = 0.88 mg/kg/day

LOAEL = 1.77 mg/kg/day based on tremors.

Developmental NOAEL = 0.88 mg/kg/day

LOAEL = 1.77 mg/kg/day based on increased fetal and litter incidence of
hydroureter without nephrosis.

870.3700a

	Prenatal developmental in (rat, diet)	45352301 (2001)

Acceptable/guideline

0, 2.4, 4.8, 7.1, 15.5 mg/kg/day	Maternal NOAEL = 7.1 mg/kg/day

LOAEL = 15.5 mg/kg/day based on clinical signs and decreased food
consumption, body weight gains, and body weight gains (adjusted for
gravid uterine weight).

Developmental NOAEL = 15.5 mg/kg/day

LOAEL was not established.

870.3700b

	Prenatal developmental in (rabbit, gavage)	00145997 (1984)

Acceptable/guideline

0, 2.36, 3.5, 7 mg/kg/day	Maternal NOAEL = 2.36 mg/kg/day,

LOAEL = 3.5 mg/kg/day based on treatment-related head and forelimb
twitching.

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mg/kg/day based on tremors and decreased body weights.

Reproductive/ Offspring NOAEL = 5.0 mg/kg/day,

Reproductive/ Offspring LOAEL was not established.

870.4100b

	Chronic toxicity

(dog)	00163065 (1985)

Acceptable/guideline

0, 0.66, 1.3, 2.7, 4.4 mg/kg/day	NOAEL = 1.3 mg/kg/day,

LOAEL= 2.7 mg/kg/day based on increased incidence of tremors.

870.4300

	Chronic/ Carcinogenicity (rat)	00157226 (1986)

Acceptable/guideline

M: 0, 0.6, 2.3, 4.7, 9.7 mg/kg/day 

F: 0, 0.7, 3.0, 6.1, 12.7 mg/kg/day 	NOAEL = M/F: 4.7/3.0 mg/kg/day,

LOAEL =M/F: 9.7/6.1 mg/kg/day based on increased incidence of tremors.

No conclusive evidence of carcinogenicity

870.4300

	Chronic/ Carcinogenicity (mouse)	00157227 (1986)

Acceptable/guideline

M: 0, 6.7, 25.6, 65.4, 81.3 mg/kg/day 

F: 0, 8.8, 32.7, 82.2, 97.2 mg/kg/day 	NOAEL =M/F: 6.7/8.8 mg/kg/day,

LOAEL = M/F: 25.6/32.7 mg/kg/day based on based on increased incidence
of tremors.

Carcinogenic potential was evidenced by a dose-related increase in the
incidence of leiomyosarcomas in the urinary bladder, a significant
dose-related trend for combined hepatocellular adenomas and carcinomas
in males, and a significantly higher incidence of combined lung adenomas
and carcinomas in females.

870.6200a

	Acute neurotoxicity (rat, gavage)	44862102(1998)

Acceptable/Guideline

0, 9.4, 32.8, 70.3 mg/kg/day	NOAEL = 32.8 mg/kg/day,

LOAEL=70.3 mg/kg/day based on clinical signs of toxicity, FOB findings,
altered motor activity, and mortality (females only).

870.6200b

	Subchronic neurotoxicity screening battery (rat)	44862103 (1998)

Acceptable/Guideline

M:  0, 2.7, 5.6, 11.1 mg/kg/day

F:  0, 3.5, 6.7, 13.7 mg/kg/day	NOAEL= M/F: 2.7/3.5 mg/kg/day,

LOAEL= M/F: 5.6/6.7 mg/kg/day based on neuromuscular findings (tremors,
changes in grip strength and landing foot-splay).

870.6300	Developmental Neurotoxicity (rat)	46750501 (2006)

Acceptable/non-guideline

0, 3.6, 7.2 and 9.0 mg/kg/day (gestation)

0, 8.3, 16.2 and 20.7 mg/kg/day (lactation)	Maternal NOAEL = 3.6
mg/kg/day during gestation and 8.3 mg/kg/day during lactation,

LOAEL = 7.2 mg/kg/day during gestation and 16.2 mg/kg/day during
lactation based on clinical signs of neurotoxicity (tremors, clonic
convulsions, and increased grooming counts).

Developmental NOAEL =3.6 mg/kg/day during gestation and 8.3 mg/kg/day
during lactation.

Developmental LOAEL = 7.2 mg/kg/day during gestation and 16.2 mg/kg/day
during lactation based on clinical signs of neurotoxicity (increased
grooming counts).



Bifenthrin	Human-Health Risk Assessment	PC Code: 128825

Page   PAGE  1  of   NUMPAGES  35 

