	

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF PREVENTION, PESTICIDES

						AND TOXIC SUBSTANCES

Date: 10/23/2007

MEMORANDUM

SUBJECT:	Cyfluthrin/Beta-cyfluthrin – Human Health Risk Assessment For
New Uses on Grasses, Alfalfa, and Sugar Beet Seed and Revised Tolerances
on Cereal Grain Commodities. 

Regulatory Action:  Section 3 Registration Action

Risk Assessment Type: Single Chemical Aggregate

PC Codes:	128831 – Cyfluthrin

		118831 – Beta-cyfluthrin

Petitions	6E7058, 6F7160, 7F7226, and 7F7200.

DP Barcode:	D331951; D331952: D335486; D339095; D339413; D339414; 

		D339415; D339445; D340710; D340711; D340712; D340713.

FROM:	Christina Swartz, Branch Chief

Kelly Schumacher, Toxicology

Douglas Dotson, Chemistry, Dietary Analysis

Suku Oonnithan, Occupational and Residential Exposure

Tom Moriarty, Risk Assessment

Registration Action Branch 2

Health Effects Division (7509P)

THROUGH:	Christina Swartz, Branch Chief

	Richard Loranger, Branch Senior Scientist

Registration Action Branch 2

Health Effects Division (7509P)

TO:	Marion Johnson, Chief

	Insecticide Branch

Registration Division (7505P)

	

	And

	Dan Rosenblatt, Chief

	Risk Integration Minor Use, and Emergency Response Branch

Registration Division (7505P)

Summary:  	HED has completed a human health risk assessment for the
proposed uses of and tolerances for cyfluthrin/beta-cyfluthrin
associated with the subject petitions: 6E7058 – use on grasses; 6F7160
– new use on sugar beet seed; 7F7200 -crop group tolerances; and,
7F7226 – increased application rate on alfalfa.  The dietary
assessment reflects proposed new uses and tolerances, and includes an
updated drinking water assessment.  While there are no residential
exposures associated with the subject petitions, an aggregate assessment
was conducted based on currently registered residential uses.  An
occupational exposure assessment has also been performed for the
proposed uses on grasses, alfalfa, and sugar beet seed treatment.

                                                                       
                                                                        
           

Table of Contents

  TOC \o "1-3" \h \z \u    HYPERLINK \l "_Toc179885342"  1.0  Executive
Summary	  PAGEREF _Toc179885342 \h  5  

  HYPERLINK \l "_Toc179885343"  2.0  Ingredient Profile	  PAGEREF
_Toc179885343 \h  11  

  HYPERLINK \l "_Toc179885344"  3.0 Hazard Characterization/Assessment	 
PAGEREF _Toc179885344 \h  12  

  HYPERLINK \l "_Toc179885345"  3.1  Database Summary	  PAGEREF
_Toc179885345 \h  12  

  HYPERLINK \l "_Toc179885346"  3.1.1  Studies Available and Considered	
 PAGEREF _Toc179885346 \h  12  

  HYPERLINK \l "_Toc179885347"  3.1.2  Mode of Action, Metabolism,
Toxicokinetic Data	  PAGEREF _Toc179885347 \h  13  

  HYPERLINK \l "_Toc179885348"  3.1.3  Sufficiency of Studies/Data	 
PAGEREF _Toc179885348 \h  14  

  HYPERLINK \l "_Toc179885349"  3.2  Toxicological Effects	  PAGEREF
_Toc179885349 \h  14  

  HYPERLINK \l "_Toc179885350"  3.3  FQPA Considerations	  PAGEREF
_Toc179885350 \h  16  

  HYPERLINK \l "_Toc179885351"  3.4  Hazard Identification and Toxicity
Endpoint Selection	  PAGEREF _Toc179885351 \h  17  

  HYPERLINK \l "_Toc179885352"  3.4.1  Acute Reference Dose (aRfD) –
General Population	  PAGEREF _Toc179885352 \h  17  

  HYPERLINK \l "_Toc179885353"  3.4.2  Chronic Reference Dose (cRfD)	 
PAGEREF _Toc179885353 \h  18  

  HYPERLINK \l "_Toc179885354"  3.4.3  Incidental Oral Exposure (Short-
and Intermediate-Term)	  PAGEREF _Toc179885354 \h  19  

  HYPERLINK \l "_Toc179885355"  3.4.4  Dermal Absorption	  PAGEREF
_Toc179885355 \h  19  

  HYPERLINK \l "_Toc179885356"  3.4.7  Inhalation Exposure (Short-Term)	
 PAGEREF _Toc179885356 \h  21  

  HYPERLINK \l "_Toc179885357"  3.4.8  Inhalation Exposure
(Intermediate- and Long-Term)	  PAGEREF _Toc179885357 \h  21  

  HYPERLINK \l "_Toc179885358"  3.4.9  Level of Concern for Margin of
Exposure (MOE)	  PAGEREF _Toc179885358 \h  22  

  HYPERLINK \l "_Toc179885359"  3.4.10  Recommendation for Aggregate
Exposure Risk Assessments	  PAGEREF _Toc179885359 \h  22  

  HYPERLINK \l "_Toc179885360"  3.4.11  Classification of Carcinogenic
Potential	  PAGEREF _Toc179885360 \h  23  

  HYPERLINK \l "_Toc179885361"  3.4.12  Summary of Toxicological Doses
and Endpoints for Cyfluthrin and Beta-Cyfluthrin for Use in Human Health
Risk Assessments	  PAGEREF _Toc179885361 \h  23  

  HYPERLINK \l "_Toc179885362"  3.5  Endocrine disruption	  PAGEREF
_Toc179885362 \h  24  

  HYPERLINK \l "_Toc179885363"  4.0  Public Health and Pesticide
Epidemiology Data	  PAGEREF _Toc179885363 \h  25  

  HYPERLINK \l "_Toc179885364"  5.0  Dietary Exposure/Risk
Characterization	  PAGEREF _Toc179885364 \h  25  

  HYPERLINK \l "_Toc179885365"  5.1  Metabolism and Environmental
Degradation	  PAGEREF _Toc179885365 \h  25  

  HYPERLINK \l "_Toc179885366"  5.1.1    Metabolism in Primary Crops	 
PAGEREF _Toc179885366 \h  25  

  HYPERLINK \l "_Toc179885367"  5.1.2  Metabolism in Livestock	  PAGEREF
_Toc179885367 \h  25  

  HYPERLINK \l "_Toc179885368"  5.1.4  Environmental Degradation	 
PAGEREF _Toc179885368 \h  26  

  HYPERLINK \l "_Toc179885369"  5.1.5  Pesticide Metabolites and
Degradates of Concern	  PAGEREF _Toc179885369 \h  27  

  HYPERLINK \l "_Toc179885370"  5.1.6  Drinking Water Residue Profile	 
PAGEREF _Toc179885370 \h  27  

  HYPERLINK \l "_Toc179885371"  5.1.7  Food Residue Profile	  PAGEREF
_Toc179885371 \h  28  

  HYPERLINK \l "_Toc179885372"  5.2  Dietary Exposure and Risk	  PAGEREF
_Toc179885372 \h  32  

  HYPERLINK \l "_Toc179885373"  5.2.1  Dietary Exposure Refinements	 
PAGEREF _Toc179885373 \h  32  

  HYPERLINK \l "_Toc179885374"  5.2.2  Acute and Chronic Dietary
Exposure/Risk	  PAGEREF _Toc179885374 \h  33  

  HYPERLINK \l "_Toc179885375"  5.2.3  Cancer Dietary Risk	  PAGEREF
_Toc179885375 \h  34  

  HYPERLINK \l "_Toc179885376"  6.0  Residential (Non-Occupational)
Exposure/Risk Characterization	  PAGEREF _Toc179885376 \h  34  

  HYPERLINK \l "_Toc179885377"  6.1  Spray Drift	  PAGEREF _Toc179885377
\h  35  

  HYPERLINK \l "_Toc179885378"  7.0  Aggregate Risk Assessments and Risk
Characterization	  PAGEREF _Toc179885378 \h  35  

  HYPERLINK \l "_Toc179885379"  7.1  Acute Aggregate Risk	  PAGEREF
_Toc179885379 \h  36  

  HYPERLINK \l "_Toc179885380"  7.2  Short-Term and Intermediate-Term
Aggregate Risk	  PAGEREF _Toc179885380 \h  36  

  HYPERLINK \l "_Toc179885381"  7.3  Chronic Aggregate Risk Assessment	 
PAGEREF _Toc179885381 \h  37  

  HYPERLINK \l "_Toc179885382"  7.4  Cancer Aggregate Risk Assessment	 
PAGEREF _Toc179885382 \h  37  

  HYPERLINK \l "_Toc179885383"  8.0  Cumulative Risk
Characterization/Assessment	  PAGEREF _Toc179885383 \h  37  

  HYPERLINK \l "_Toc179885384"  9.0  Occupational Exposure/Risk Pathway	
 PAGEREF _Toc179885384 \h  38  

  HYPERLINK \l "_Toc179885385"  9.1  Occupational/Non-Residential
Toxicological Profile for Cyfluthrin/Beta-cyfluthrin	  PAGEREF
_Toc179885385 \h  39  

  HYPERLINK \l "_Toc179885386"  9.2  Occupational/Non-Residential
Exposure Inputs	  PAGEREF _Toc179885386 \h  40  

  HYPERLINK \l "_Toc179885387"  9.3  Handler and Applicator Risks from
Proposed Uses on Grasses and Alfalfa	  PAGEREF _Toc179885387 \h  41  

  HYPERLINK \l "_Toc179885388"  9.4  Short-term and Intermediate-term
Exposures and Risk from Proposed Seed Treatment Use	  PAGEREF
_Toc179885388 \h  42  

  HYPERLINK \l "_Toc179885389"  9.5  Post-application Exposure and Risk	
 PAGEREF _Toc179885389 \h  43  

  HYPERLINK \l "_Toc179885390"  10.0  Data Needs and Label
Recommendations	  PAGEREF _Toc179885390 \h  44  

  HYPERLINK \l "_Toc179885391"  References	  PAGEREF _Toc179885391 \h 
46  

  HYPERLINK \l "_Toc179885392"  Appendix A.  Occupational Exposure and
Risk Tables	  PAGEREF _Toc179885392 \h  47  

  HYPERLINK \l "_Toc179885393"  Appendix B  Toxicology Profile of
Cyfluthrin and Beta-cyfluthrin	  PAGEREF _Toc179885393 \h  51  

  HYPERLINK \l "_Toc179885394"  Appendix C  Summary of
Cyfluthrin/Beta-cyfluthrin Tolerances	  PAGEREF _Toc179885394 \h  65  

 1.0  Executive Summary

Cyfluthrin and beta-cyfluthrin (an enriched isomer of cyfluthrin) are
non-systemic pyrethroid insecticides.   Cyfluthrin was first registered
in 1989, and currently there are approximately 145 active products
registered for use on a wide variety of sites including agricultural,
indoor/outdoor domestic dwellings, ant dens/mounds, and stored product
pests.  Beta-cyfluthrin was first registered in 1995 and currently there
are approximately 27 active registrations.  Permanent tolerances are
established for residues of cyfluthrin (40 CFR §180.436).  Tolerances
for cyfluthrin also cover beta-cyfluthrin, provided that the use rates
for beta-cyfluthrin are ½ that of cyfluthrin.  The current risk
analysis on cyfluthrin/beta-cyfluthrin was conducted to assess several
petitions; (i) an increase in the number of applications to alfalfa;
(ii) expanded geographical uses on grasses; (iii) request for crop group
15 (except rice) and for crop group 16 tolerances; and, (iv) a new use
for sugar beet seed treatment.  A summary of the subject petitions can
be found in Table 1.  Several field trial studies were submitted in
connection with the subject petitions which were reviewed and
incorporated into this assessment.  

Toxicologically, the primary target for cyfluthrin/beta-cyfluthrin is
the neuromuscular system; other non-specific effects include decreased
body weight gain, and decreased food consumption.  The observed
neuromuscular effects (tremors, gait abnormities, abnormal postural
reactions, splaying of limbs and decreases in activity) occurred mainly
in oral studies in the dog and the rat.  In general, the toxicity data
base does not indicate that any major differences in toxicity exist
between beta-cyfluthrin and cyfluthrin via the oral route.  Data from
the inhalation toxicity study showed evidence of clinical signs as well
as hypothermia and decreased body weight gains.  In a postnatal
inhalation study in mice, there were clinical signs of neurotoxicity in
the pups as well as increased spontaneous motor activity and paresthesia
(tingling, burning or prickling – also seen in oral studies).  

In oral developmental studies no increased susceptibility was observed
in the rat or rabbit; however, increased susceptibility was observed in
inhalation developmental studies.  Increased susceptibility was also
seen in oral reproduction studies and in a developmental neurotoxicity
study on beta-cyfluthrin.  The data also demonstrate increased
susceptibility of rats and mice to cyfluthrin postnatally.  The FQPA
Safety Factor was reduced to 1x because the database is complete and the
exposure database is sufficient. 

The database does not indicate that either cyfluthrin or beta-cyfluthrin
induces any endocrine disruption; and, there is no concern of
mutagenicity.  HED has classified cyfluthrin/beta-cyfluthrin as “not
likely to be carcinogenic to humans.” 

The metabolism of cyfluthrin/beta-cyfluthrin is well understood in both
plant and animal matrices, and analytical methods for the currently
registered and proposed uses have been submitted and validated.

The dietary analysis is refined and includes processing factors, percent
crop treated estimates, and monitoring data.  The dietary analysis also
includes secondary residues, and reflects revised tolerance values
associated with the subject petitions.  The updated drinking water
analysis considers all currently registered and proposed uses.

Acute dietary risks for the general population and all population
subgroups were not of concern to HED, with children 1 – 2 years old,
the highest exposed subpopulation, utilizing 53% of the acute population
adjusted dose (aPAD).  Chronic dietary risks for the general population
and all population subgroups were also not of concern to HED, with
children 1 – 2 years old, the highest exposed subpopulation, utilizing
17% of the chronic population adjusted dose (cPAD).

Aggregate assessments were also conducted for
cyfluthrin/beta-cyfluthrin.  The acute aggregate assessment included
food and drinking water only, and therefore is equal to the acute
dietary risk (children 1 – 2 years utilizing 53% of the aPAD).  In the
short-, and intermediate-term assessments, HED combined the current
chronic dietary exposure estimates with (previously assessed)
residential exposures.  (The current petitions do not indicate any
potential residential or non-occupational exposures).  Aggregate
assessments indicated no risks of concern.

HED’s occupational risk assessment examined risk to workers associated
with production of alfalfa, production of grasses, and for seed
treatment operations.  HED’s analysis indicates that handlers using
aerial or ground boom equipment for alfalfa or grass production are
required to wear base line protective equipment (PPE), chemical
resistant gloves, and a dust/mist respirator when handing liquid
formulations of cyfluthrin/beta-cyfluthrin; but, are adequately
protected with just base line PPE when handling water soluble bag
packaged wettable powder formulations.  Applicators and flaggers
involved in alfalfa and grass production were also adequately protected
with base line PPE.  Exposure to workers entering cyfluthrin and
beta-cyfluthrin treated fields to perform post-application activities is
not of concern.

Risks to individuals associated with sugar beet seed treatment were also
assessed.  Risks of concern existed for certain scenarios. 
Intermediate-term exposure to loaders/treaters involved in sugar beet
seed treatment was a concern to HED (MOE = 81).  Also, risks to an
individual performing all three seed treatment operations, (i.e.,
performing loading/treating, bagging, and sewing in one 8-hour work day)
was of concern to HED.  Risks to other individuals involved in the seed
treatment operation were not of concern to HED.  Also, risks to workers
who plant the Poncho Beta treated sugar beet seed are not a concern to
HED.

This risk assessment relies in part on data from studies in which adult
human subjects were intentionally exposed to a pesticide or other
chemical.  These studies, which comprise the Pesticide Handlers Exposure
Database (PHED), have been determined to require a review of their
ethical conduct, and have received that review. The studies in PHED were
considered appropriate (or ethically conducted) for use in risk
assessments.

Potential areas of environmental justice concerns, to the extent
possible, were considered for this human health risk assessment, in
accordance with US Executive Order 12898, Federal Actions to Address
Environmental Justice in Minority Populations and Low-Income
Populations,   HYPERLINK
"http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf" 
http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf .

As a part of every pesticide risk assessment, OPP considers a large
variety of consumer subgroups according to well-established procedures. 
In line with OPP policy, HED estimates risks to population subgroups
from pesticide exposures that are based on patterns of that subgroup’s
food and water consumption, and activities in and around the home that
involve pesticide use in a residential setting.  Extensive data on food
consumption patterns are compiled by USDA under the CSFII, and are used
in pesticide risk assessments for all registered food uses of a
pesticide.  These data are analyzed and categorized by subgroups based
on age, season of the year, ethnic group, and region of the country. 
Whenever appropriate, non-dietary exposures based on home use of
pesticide products, associated risks for adult applicators, and for
toddlers, youths, and adults entering or playing on treated areas
post-application are evaluated.  Further considerations are currently in
development as OPP has committed resources and expertise to the
development of specialized software and models that consider exposure to
bystanders and farm workers as well as lifestyle and traditional dietary
patterns among specific subgroups.

A separate but related petition (6F7159) was also submitted regarding
the proposed (Poncho Beta®) use on sugar beet seed.  The active
ingredient being addressed in Petition 6F7159 is clothianidin, which is
a co-active ingredient along with beta-cyfluthrin in Poncho Beta®.  The
occupational risks associated with clothianidin are addressed in a
separate document (D340131).  Together these two documents address the
occupational risks associated with the proposed use of Poncho Beta® for
sugar beet seed treatment.

Summary of Recommendations

HED recommends directions for use of Baythroid® 2, Renounce® 20WP, and
Baythroid® XL, be amended to exclude ultra-low volume applications to
grasses and alfalfa.

HED recommends the Addition of dust/mist respirators as a PPE
requirement for all liquid formulations of Baythroid® 2, Renounce®
20WP, and Baythroid® XL.

HED recommends the Registration Division consider the occupational risks
associated with the proposed use of Poncho Beta® in light of the
exposures from both beta-cyfluthrin and clothianidin prior to granting
this sugar beet seed treatment use and its associated tolerances.

Pending amendments and changes suggested to the proposed Baythroid® 2,
Renounce® 20WP, and Baythroid® XL labels, HED recommends the
registration of new uses and establishment of tolerances for
cyfluthrin/beta-cyfluthrin. 

HED recommends that the establishment of tolerances incorporates the
correct commodity definitions for cyfluthrin (and beta-cyfluthrin)
treated commodities as stated in Appendix C, Table 1 and in the table
below in this section.

A revised Section F is required reflecting HED recommendations, and for
the establishment of (separate) tolerances listed below for both
cyfluthrin and beta-cyfluthrin.  The cyfluthrin tolerances should be
included in 40CFR§180.436(a)(1), while a separate section under 180.436
should be established for tolerances for beta-cyfluthrin, analogous to
the tolerances for lambda-cyhalothrin and gamma-cyhalothrin in
§180.438.  The section for beta-cyfluthrin needs to be established
because registrations for cyfluthrin on these commodities might be
cancelled at some point in the future.  The tolerances for cyfluthrin
and beta-cyfluthrin should be established at the same levels.  The
recommended wording for the beta-cyfluthrin tolerance expression is as
follows: “Tolerances are established for residues of the insecticide
beta-cyfluthrin [mixture comprising the enantiomeric pair
(R)-α-cyano-4-fluoro-3-phenoxybenzyl
(1S,3S)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate and
(S)-α-cyano-4-fluoro-3-phenoxybenzyl
(1R,3R)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate with
the enantiomeric pair (R)-α-cyano-4-fluoro-3-phenoxybenzyl
(1S,3R)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate and
(S)-α-cyano-4-fluoro-3-phenoxybenzyl
(1R,3S)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate] in or
on the following commodities:”

HED also recommends that, at some point in the future, tolerances be
established for all food uses of beta-cyfluthrin (i.e., on those
commodities not included in the present actions) under the new section
to be created under 40 CFR §180.436.

Commodity	Recommended Tolerance (ppm)

Grass, forage, fodder and hay, group 17, forage	12

Grass, forage, fodder and hay, group 17, hay	50

Alfalfa, forage	5.0

Alfalfa, hay	13

Beet, sugar, roots	0.10

Beet, sugar, dried pulp	1.0

Barley, grain	0.15

Buckwheat, grain	0.15

Millet, grain	0.15

Oat, grain	0.15

Rye, grain	0.15

Wheat, grain	0.15

Corn, field, grain	0.05

Corn, sweet, kernel plus cob with husks removed	0.05

Sorghum, grain, grain	3.5

Wheat, bran	0.5

Corn, field, refined oil	None*

Rice, bran	None

Rice, hulls	None

Grain, cereal, forage, fodder and hay, group 17, forage, except rice 	25

Grain, cereal, forage, fodder and hay, group 17, stover, except rice 	30

Grain, cereal, forage, fodder and hay, group 17, straw, except rice 	7.0

Grain, cereal, forage, fodder and hay, group 17, hay except rice	6.0

Wheat, forage	None

Corn, field, forage	None

Corn, sweet, forage	None

Sorghum, grain, forage	None

Corn, field, stover	None

Corn, pop, stover	None

Corn, sweet, stover	None

Sorghum, grain, stover	None

Wheat, hay	None

Wheat, straw	None

Cattle, fat	2.0

Cattle, meat	0.10

Cattle, meat byproducts	0.10

Goat, fat	2.0

Goat, meat	0.05

Goat, meat byproducts	0.05

Hog, fat	0.5

Hog, meat	0.01

Hog, meat byproducts	0.01

Horse, fat	2.0

Horse, meat	0.05

Horse, meat byproducts	0.05

Milk	0.2

Milk, fat	5.0

Sheep, fat	2.0

Sheep, meat	0.05

Sheep, meat byproducts	0.05

*”None” indicates that an existing tolerance on that commodity
should be revoked.

Table 1.  Summary of Regulatory Actions for Current
Cyfluthrin/Beta-cyfluthrin

Petition/

DP Barcode	Petition Request	Label Trade Name/

EPA Reg. Number/

Active Ingredient	Product

Formulation	Label Information	Assessment   Conducted

(Document Barcode Ref )





Current Label Rates	Proposed Label Rates





	Max Single Rate 	No. of App.	Max Single  Rate	No. of App



	6E7058

D339445

D331952

D331951	Request for use on grasses throughout the U.S. 
(pasture/rangeland/grass for seed/grass for hay/grass in mixed stands
with alfalfa)	Baythroid® 2 (264-745)

cyfluthrin	EC 	0.044	3	0.044	4	Residue chemistry

(D 339413)

Dietary

(D339414)

Occupational

(D339445)



Renounce® 20WP

264-784

cyfluthrin	WP/WSP	Not on label	Not on label	0.044	4



	Baythroid® XL

264-840

beta-cyfluthrin	EC	0.022	3	0.022	4



	6F7160

D335486

D339413

D339414

D339415

	Request for new use on sugar beet seed

	Poncho Beta (264-RNLA)

264-RNLA

beta-cyfluthrin

(clothianidin)	Liquid	No existing use, new use is being proposed.	5.07
fl. oz/unit seed (100,000 seeds)	1	Residue chemistry

(D 339413)

Dietary

(D339414)

Occupational

(D339445)



7F7200

D339095

	Request to amend labels to include Crop Group 15 (except rice) and Crop
Group 16;

Establish tolerance for Crop Group 15 (except rice) and Crop Group 16
Baythroid® XL

264-840

beta-cyfluthrin	EC	0.019 – 0.022	2 - 10	No proposed change to this
label in connection to this petition.	Residue chemistry

(D 339413)

Dietary

(D339414)





7F7226

D340710

D340711

D340712

D340713	Increased seasonal rate on alfalfa (increased no. of
applications);

Increased tolerance on alfalfa	Baythroid® 2

264-745;

cyfluthrin	EC	0.044	~5	0.044	8	Residue chemistry

(D 339413)

Dietary

(D339414)

Occupational

(D339445)



Renounce® 20WP

264-784

cyfluthrin	WP/WSP	0.044	~5	0.044	8



	Baythroid® XL

264-840

beta-cyfluthrin	EC	0.022	4	0.022	8

	Baythroid® 2 (264-745) contains cyfluthrin at 25%:  Renounce® 20WP
(264-840) contains cyfluthrin at 20%

Baythroid® XL (264-840) contains beta-cyfluthrin at 12.7%; Poncho
Beta® contains beta-cyfluthrin at 4.6% and clothianidin at 34.3%.



2.0  Ingredient Profile

Both cyfluthrin and beta-cyfluthrin are mixtures of the same four
diastereomers.  Isomers I and II are in the cis configuration, and
Isomers III and IV are in the trans configuration.  Cyfluthrin is
comprised of approximately equal parts: Isomer I is approximately 25%,
Isomer II is approximately 19%, Isomer III is approximately 34% and,
Isomer IV is approximately 23%.  Beta-cyfluthrin on the other hand, is
enriched in Isomer II (approximately 35%) and Isomer IV (approximately
62%), and contains only minor amounts of Isomer I and Isomer III (less
than 3% of total).  The nomenclature and physicochemical properties of
cyfluthrin and beta-cyfluthrin are presented below in Tables 2 and 3.

 

Cyfluthrin and β-Cyfluthrin Nomenclature.

	

Diastereomer I (1R,3R,αR + 1S,3S,αS; 1:1; cis)

Diastereomer II (1R,3R,αS + 1S,3S,αR; 1:1; cis)

Diastereomer III (1R,3S,αR + 1S,3R,αS; 1:1; trans)

:	(RS)-α-cyano-4-fluoro-3-phenoxybenzyl
(1RS,3RS;1RS,3SR)-3-(2,2-dichlorovinyl)-2,2-
dimethylcyclopropanecarboxylate

beta-Cyfluthrin:	enantiomeric pair (R)-α-cyano-4-fluoro-3-phenoxybenzyl
(1S,3S)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate and
(S)-α-cyano-4-fluoro-3-phenoxybenzyl
(1R,3R)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate in
ratio 1:2 with the enantiomeric pair
(R)-α-cyano-4-fluoro-3-phenoxybenzyl
(1S,3R)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate and
(S)-α-cyano-4-fluoro-3-phenoxybenzyl
(1R,3S)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate

CAS name	cyano(4-fluoro-3-phenoxyphenyl)methyl
3-(2,2-dichloroethenyl)-2,2-

dimethylcyclopropanecarboxylate

CAS registry number	68359-37-5

End-use products (EPs)	Cyfluthrin:	Baythroid® 2 (2 lb/gal EC; EPA Reg.
No. 264-745)

 	Renounce® 20WP (20% WP; EPA Reg. No. 264-784)

beta-Cyfluthrin:	Baythroid® XL (1 lb/gal EC; EPA Reg. No. 264-840)





Table 3.  Physicochemical Properties of Technical Grade Cyfluthrin

Parameter	Value

Melting point/range (°C)	Isomer I: 57	Isomer II: 73-74

Water solubility  (μg/L at 20ºC)	Isomer I: 2.2	Isomer II: 1.9

Isomer III: 2.2	Isomer IV: 2.9

Solvent solubility (g/L room temperature)	Methylene chloride >200
Toluene  >200

Hexane 10-20		Isopropanol 20-50

Vapor pressure (20 or 25°C) 	7.2 x 10-9 Pa

Dissociation constant, pKa	does not dissociate

Octanol/water partition coefficient, Log(KOW)	Isomer I:  6	Isomer II:
5.9

Isomer III: 6	Isomer IV: 5.9

UV/visible absorption spectrum	Absorption maxima:  primary: 196 nm,
secondary 275 nm



3.0 Hazard Characterization/Assessment

3.1  Database Summary

3.1.1  Studies Available and Considered 

Available mammalian toxicology studies considered in the hazard
characterization include:  

Cyfluthrin

acute oral, dermal, and inhalation toxicity; eye and dermal irritation;
and dermal sensitization studies

subchronic oral, dermal, and inhalation toxicity studies in rats

prenatal developmental oral toxicity studies in rats and rabbits

prenatal developmental inhalation toxicity studies in rats

special postnatal inhalation study in mice

multi-generation reproduction studies in rats

chronic/carcinogenicity studies in rats and mice; chronic study in dogs

a complete battery of mutagenicity studies

delayed neurotoxicity oral and dermal studies in hens

metabolism studies in rats  

Beta-cyfluthrin

acute oral, dermal, and inhalation toxicity; eye and dermal irritation;
and dermal sensitization studies

subchronic oral toxicity studies in rats and dogs

subchronic inhalation toxicity study in rats

prenatal developmental oral toxicity study in rats

a complete battery of mutagenicity studies

acute, subchronic, and developmental neurotoxicity studies in rats

3.1.2  Mode of Action, Metabolism, Toxicokinetic Data

Mode of Action 

Cyfluthrin is a type II pyrethroid (i.e., it has a cyano group at the α
carbon position of the alcohol moiety, and it is more effective when the
ambient temperature is raised); beta-cyfluthrin is an enriched isomer of
cyfluthrin.  Pyrethroids initially stimulate nerve cells to produce
repetitive discharges which can eventually lead to paralysis.  Such
effects are caused by their action on the sodium channel through which
sodium ions enter the axon to cause excitation.  These effects are
produced in an insect’s nerve cord, which contains ganglia and
synapses, as well as in giant nerve fiber axons. Type II pyrethroids
give rise to the C-S syndrome of clinical signs of toxicity.  The C-S
syndrome consists of initial pawing and burrowing and later abnormal
movements, salivation, coarse tremors, and convulsions. 

Toxicokinetic Data 

Following oral administration, cyfluthrin is rapidly and nearly
completely absorbed.  In radiolabeled studies, peak plasma levels
occurred at about 2 hours after dosing.  Greater than 95% of the
administered radioactivity was excreted within 48 hours.  Radioactivity
was excreted in the urine and feces with virtually none being excreted
in expired air.  The ratio of radioactivity in urine/feces was higher in
males than in females.  About 50% of the total urinary radioactivity was
recovered during the first 6-8 hours after dosing and about 90% within
the first 24 hours.  At 48 hours, only the fat tissue (renal fat)
contained levels of radioactivity that clearly exceeded the overall mean
body level, being 6-11X higher.  Different dose levels (0.5 or 10 mg/kg)
or pretreatment (14X) did not appreciably affect the above findings. 
Results following intravenous dosing were quite similar to those
described for oral dosing.  Studies in male rats with bile fistulas
indicated an enterohepatic circulation of test material.  Parent
cyfluthrin is cleaved at the ester bond and then oxidized to yield
3-phenoxy-4-fluorobenzoic acid.  This intermediate is then either
hydroxylated and subsequently conjugated and excreted, or first bound to
glycine and then hydroxylated, conjugated and excreted. 

A comparative study in rats on the absorption of cyfluthrin after a
single dose indicates that when cremophor EL is used as the vehicle, the
concentration of cyfluthrin in the blood peaks after 1 hour and the rats
show signs of intoxication; whereas, when PEG 400 is used as the
vehicle, the blood level peaks at 6 hours after dosing and the maximum
blood level is about 1/5 of the level when the test substance is
administered with cremophor.  There was more cyfluthrin in the stomachs
of the rats treated with PEG 400 than there was in the stomachs of those
treated with cremophor.  Cyfluthrin appears to be absorbed more quickly
from the GI tract in the presence of cremophor than in the presence of
PEG 400.

3.1.3  Sufficiency of Studies/Data

Cyfluthrin toxicity data have been used as bridging data for
beta-cyfluthrin.  The toxicology databases together are considered
complete and adequate for selecting toxicity endpoints for risk
assessment.  The scientific quality is relatively high, and the toxicity
profiles of both cyfluthrin and beta-cyfluthrin can be characterized for
all effects, including potential developmental, reproductive, and
neurotoxic effects. 

3.2  Toxicological Effects

The HED risk assessment team has re-evaluated the
cyfluthrin/beta-cyfluthrin toxicological effects and endpoints for
assessing human health risk.  For a complete discussion of the
toxicological effects of cyfluthrin and beta-cyfluthrin, excluding the
recently received developmental neurotoxicity study, refer to
“Toxicology Chapter for Cyfluthrin/Beta-Cyfluthrin” (D283924, V.
Dobozy, 7/18/2002).

The acute toxicity of both cyfluthrin and beta-cyfluthrin is low to high
via the oral route of exposure (Categories I to III, depending on the
vehicle), moderate via the inhalation route (Categories II to III,
depending upon the vehicle), and low via the dermal route (Category IV).
 Cyfluthrin and beta-cyfluthrin are slight eye and dermal irritants, but
neither is a dermal sensitizer.

The databases on cyfluthrin and beta-cyfluthrin indicate one major
target for these chemicals, the neuromuscular system, along with
non-specific effects such as decreased body weight gain and food
consumption.  The neuromuscular effects (i.e., tremors, gait
abnormalities, abnormal postural reactions, splaying of limbs, and
decreases in activity) occurred mainly in oral studies in the dog and
the rat.  In some studies in rats and mice, ear lesions were observed,
which appear to be related to a known pyrethroid effect, paresthesia
(tingling, burning or prickling), which caused the animals to scratch
excessively.  

In oral studies with the rat, beta-cyfluthrin appeared more toxic than
cyfluthrin; however, in the oral studies with the dog (the most
sensitive species for clinical signs), beta-cyfluthrin did not appear to
be more toxic than cyfluthrin.  Weight of the evidence from the
cyfluthrin rat studies (28-day feeding and gavage studies, subchronic
feeding study, 14-day and 5-month neurotoxicity studies (gavage),
chronic feeding studies and the reproduction studies) indicates that the
clinical signs of neurotoxicity in the rat may commence at a dose level
somewhere between 40 and 60 mg/kg/day.  In the 90-day oral study with
beta-cyfluthrin, clinical signs of neurotoxicity were observed at
37.0/43.0 mg/kg/day (M/F), and in the 90-day subchronic neurotoxicity
study with beta-cyfluthrin, clinical signs of neurotoxicity were
observed at 27/30 mg/kg/day (M/F).  Comparison of the developmental rat
studies indicates that the LOAEL for beta-cyfluthrin is 10 mg/kg/day
(decrease in body weights and food consumption); whereas, the LOAEL for
cyfluthrin is greater than 10 mg/kg/day (although some slight effects
were observed in the range-finding study at this dose level).  In
contrast to the rat, when all of the available dog studies are
considered, gait abnormalities were observed at 13.9 mg/kg/day in the
90-day dog study with beta-cyfluthrin (NOAEL = 2.36 mg/kg/day), while
the LOAELs from three dog feeding studies on cyfluthrin (i.e., one
6-month and two 12-month studies) were based on similar effects and
occurred at similar doses of 15, 16, and 10.6 mg/kg/day (NOAELs = 5, 4,
and 2.4 mg/kg/day).  A comparison of these NOAELs does not indicate any
major differences in toxicity between beta-cyfluthrin and cyfluthrin in
the oral studies.  The studies also do not indicate any increase in the
severity of the effects over time (the NOAEL and LOAEL from the new dog
study is lower because of dose spread).  In addition, the NOAELs for the
28-day dog study and the 90-day dog study conducted with beta-cyfluthrin
are similar.  Therefore, it is unlikely that a NOAEL from a chronic dog
study conducted with beta-cyfluthrin would be less than the NOAEL for
the 90-day study conducted with beta-cyfluthrin.  In the dog, the
neurological clinical signs induced by pyrethroids in general do not
appear to be cumulative but rather, are transient.  In general, neither
sex appears to be more sensitive, for either dogs or rats.

The inhalation studies in the rat, cyfluthrin induced some clinical
signs, but these were not as severe as in the oral studies (e.g.,
reduced motility, dyspnea, piloerection, ungroomed coat, and eye
irritation).  In addition to the clinical signs, hypothermia and
decreased body weight gains were also observed in the rat inhalation
studies.  In a postnatal inhalation study in mice, there were clinical
signs of neurotoxicity in the pups as well as increased spontaneous
motor activity and paresthesia.  The inhalation toxicity of
beta-cyfluthrin and cyfluthrin can be compared through examination of
the 4-week studies on each compound, both of which used a common
vehicle.  A direct comparison is somewhat limited by the differences in
dose spacing; however, the studies show that the NOAELs and LOAELs are
not significantly different:  the NOAEL and LOAEL for the study
conducted with cyfluthrin are 0.12 and 1.6 mg/kg/day, respectively and
the NOAEL and LOAEL for the study conducted with beta-cyfluthrin are
0.07 and 0.73 mg/kg/day, respectively.  Both LOAELs are based on similar
effects, including body weight changes, with additional effects seen at
the higher dose of 1.6 mg/kg/day in the cyfluthrin study.

A number of the non-acute gavage studies conducted with cyfluthrin and
beta-cyfluthrin used cremophor as the vehicle.  Therefore, the toxicity
of the two isomer mixtures is probably enhanced in these studies.  The
repeated-dose dermal study conducted with cyfluthrin in the rat
validates this finding.  In that study, the only systemic effects
observed were at the limit dose of 1077 mg/kg/day (decreased food
consumption, red nasal discharge and urine staining).  All of the longer
term inhalation studies conducted with cyfluthrin and beta-cyfluthrin
use a PEG vehicle and it is likely that the same enhancement holds true
as well.  These vehicles can cause damage to the lungs.  The repeated
dose dermal study (18 applications) indicates that, with repeated dermal
exposure, significant dermal irritation will result.  The NOAEL for skin
irritation in that study is 113 mg/kg/day and the LOAEL is 376
mg/kg/day.  

Multiple hen studies by the oral, dermal and inhalation routes of
administration indicate that cyfluthrin is not a delayed neurotoxicant
and does not inhibit neurotoxic esterase.

Cyfluthrin has been classified as a Category E carcinogen (no evidence
of carcinogenicity) and, with the submission of new studies, is
reclassified as “not likely to be carcinogenic to humans” under the
Draft Proposed Guidelines for Carcinogen Risk Assessment (1999).  No
increase in any type of tumors was found in rats or mice in the
available carcinogenicity studies, although structure-activity
comparisons reveal indications of lung tumors in mice with three other
pyrethroids.  No evidence of mutagenicity was seen in any of the eight
acceptable studies on cyfluthrin or the five acceptable studies on
beta-cyfluthrin.  The submitted studies on cyfluthrin satisfy the
pre-1991 mutagenicity test battery.

3.3  FQPA Considerations

The cyfluthrin/beta-cyfluthrin risk assessment team has considered the
toxicity data regarding sensitivity of infants and children.  For a more
in-depth description of the FQPA considerations associated with
cyfluthrin and beta-cyfluthrin, excluding the recently received
developmental neurotoxicity study, refer to “CYFLUTHRIN and
BETA-CYFLUTHRIN - 3rd Report of the Hazard Identification Assessment
Review Committee.” (TXR 0050768, P. Hurley, 5/21/2002).

The mammalian toxicology database for cyfluthrin and beta-cyfluthrin is
complete and adequate for FQPA considerations.  Studies available
include prenatal developmental oral toxicity studies with rats
(cyfluthrin and beta-cyfluthrin) and rabbits (cyfluthrin only); prenatal
developmental inhalation toxicity studies (cyfluthrin) in rats; a
special postnatal inhalation toxicity study (cyfluthrin) in mice;
multi-generation reproduction studies (cyfluthrin) in rats; delayed
neurotoxicity oral studies (cyfluthrin) in hens; and acute, subchronic,
and developmental neurotoxicity (DNT) studies (beta-cyfluthrin) in rats.

Evidence of neurotoxicity typical of the pyrethroids was observed
throughout the toxicology database.  In the acute and subchronic
neurotoxicity studies, clinical signs of neurotoxicity, changes in
Functional Observational Battery (FOB) measurements, and decreased motor
activity were seen.  In the DNT study, decreased brain weights were seen
in female offspring at study termination along with decreased body
weights and body weight gains in pups of both sexes.  In the other
guideline studies on rats, dogs, and mice, neurotoxic effects including
clinical signs of neurotoxicity, gait abnormalities, changes in motor
activity, tremors, and abnormal postural reactions were seen following
oral and inhalation exposure.

There is a concern for pre- and/or postnatal toxicity resulting from
exposure to cyfluthrin and beta-cyfluthrin.  In the prenatal
developmental studies, there was no evidence of increased susceptibility
of rats or rabbits to in utero exposure to either cyfluthrin or
beta-cyfluthrin via the oral route; however, there was evidence of
increased qualitative and quantitative susceptibility of rats to in
utero exposure to cyfluthrin via the inhalation route.  A postnatal
inhalation study in mice demonstrates increased qualitative and
quantitative susceptibility of the offspring following exposure to
cyfluthrin.  Increased susceptibility is also seen in rats in oral
reproduction studies on cyfluthrin and in a developmental neurotoxicity
study on beta-cyfluthrin.

The degree of concern for all of the prenatal developmental, special
postnatal, reproduction, and developmental neurotoxicity studies that
demonstrate increased susceptibility (quantitative and/or qualitative)
is low because the effects in each of these studies are well
characterized, with conservative NOAELs established for all
developmental and offspring effects.  There are no residual
uncertainties because the points of departure (NOAELs) selected for risk
assessment are lower than the NOAELs from these studies and are, thus,
protective of any potential pre- and post-natal effects.

There are no residual uncertainties identified in the exposure
databases.  The acute dietary exposure assessment is refined, and
drinking water estimates were derived from conservative screening
models.  Although refined, HED believes that the dietary assessment is
based on reliable data and will not underestimate exposure/risk.  The
residential exposure assessment utilizes reasonable high-end variables
set out in HED’s Occupational/Residential Exposure SOPs.  The
aggregate assessment is based upon reasonable worst-case residential
assumptions, and is also not likely to underestimate exposure/risk to
any subpopulation, including those comprised of infants and children.   

Based on the data discussed above, the FQPA Safety Factor can be removed
(i.e., reduced to 1X) due to the completeness of the toxicology
database, the lack of residual concerns regarding pre- and post-natal
toxicity, and the reliance on exposure data that are unlikely to
underestimate exposure to the pesticide.

3.4  Hazard Identification and Toxicity Endpoint Selection

3.4.1  Acute Reference Dose (aRfD) – General Population

Study Selected:  Acute neurotoxicity study in rats (beta-cyfluthrin)

MRID Number:  44401101

Dose and Endpoint for Risk Assessment:  2 mg/kg (NOAEL), based on
clinical signs, changes in FOB parameters, and decreases in motor
activity observed at 10 mg/kg (LOAEL) 

Uncertainty Factor(s):  100X (10X for interspecies variability, 10X for
intraspecies variability)

Comments about Study/Endpoint/Uncertainty Factor:  

This endpoint for the general population is based on effects observed
after a single dose, which is the appropriate duration of exposure for
an acute endpoint, and the route of administration (oral) is appropriate
for dietary considerations.    TC \l3 "3.5.2	Acute Reference Dose (aRfD)
- General Population Selection of the acute dietary endpoint based on
the acute neurotoxicity (ACN) study is considered protective, as the
vehicle used in this study was cremophor, which has been shown to
enhance absorption of cyfluthrin, by increasing the amount of cyfluthrin
in the blood.  However, the NOAEL of 2 mg/kg in the ACN study where
cremophor was the vehicle is supported by a NOAEL of 2.36 mg/kg in the
90-day dog feeding study where beta-cyfluthrin was mixed directly into
the feed (i.e., no vehicle was used).  The LOAEL in this dog study was
based on gait abnormalities seen following 3 days of exposure to 13.9
mg/kg/day, similar to the effects seen after a single dose of 10 mg/kg
in the ACN study.  Selection of an endpoint based on a beta-cyfluthrin
study is considered protective of effects from both beta-cyfluthrin and
cyfluthrin, as beta-cyfluthrin is an enriched isomer of cyfluthrin.

A separate endpoint for acute dietary exposure to females 13-49 was not
selected because the acute reference dose for the general population is
protective of any potential developmental effects.  No developmental
effects are observed in any of the developmental studies at dose levels
in the 2 mg/kg range.  In the rat developmental toxicity study with
beta-cyfluthrin, increases in skeletal variations were observed at 40
mg/kg/day (NOAEL = 10 mg/kg/day); however, these effects generally
consisted of changes in ossification rates likely to be connected with
an observed decrease in mean fetal body weights, which are not
considered to be single dose effects.  Further, most of these
differences were seen in the number of fetuses affected and not in the
number of litters affected.  The acute reference dose for the general
population is also protective of the offspring effects seen in the
developmental neurotoxicity study with beta-cyfluthrin, which included
decreased brain weights in females at study termination, at 17.8
mg/kg/day (NOAEL = 11 mg/kg/day).  No other potential acute dietary
endpoints for females 13-49 were found in the available database.

3.4.2  Chronic Reference Dose (cRfD)   TC \l3 "3.5.3	Chronic Reference
Dose (cRfD) 

Study Selected:  Chronic toxicity study in dogs (cyfluthrin)

MRID Number:  44435401

Dose and Endpoint for Risk Assessment:  2.4 mg/kg/day (NOAEL), based on
clinical signs, gait abnormalities, and abnormal postural reactions
observed at 10.64 mg/kg (LOAEL) 

Uncertainty Factor(s):  100X (10X for interspecies variability, 10X for
intraspecies variability)

Comments about Study/Endpoint/Uncertainty Factor:  This endpoint is
selected from a chronic feeding study, the appropriate length and route
of exposure for a chronic dietary endpoint.  It is supported by the
chronic feeding study in the rat (NOAEL = 2.6 mg/kg/day) and the
multigeneration reproduction study in the rat (parental NOAEL = 3
mg/kg/day), where both LOAELs were based on decreased body weights.

Although the acute toxicity studies and the oral rat studies indicate
that beta-cyfluthrin is more toxic than cyfluthrin and the percentages
of the insecticidally active isomers in beta-cyfluthrin would indicate
that it could be up to twice as toxic as cyfluthrin, it is anticipated
that this endpoint would be protective for beta-cyfluthrin for the
following reasons.  While the oral studies in rats indicate that
beta-cyfluthrin is more toxic than cyfluthrin, the oral studies in dogs
(the most sensitive species for clinical signs), do not show that
beta-cyfluthrin is more toxic than cyfluthrin.  For example, the weight
of evidence from the cyfluthrin rat studies (28-day feeding and gavage
studies, subchronic feeding study, 14-day and 5-month neurotoxicity
studies (gavage), chronic feeding studies and the reproduction studies)
indicate that for cyfluthrin, it appears that the clinical signs of
neurotoxicity in the rat may commence at a dose level somewhere between
40 and 60 mg/kg/day; whereas, in the 90-day oral study with
beta-cyfluthrin, clinical signs of neurotoxicity were observed at
37.0/43.0 mg/kg/day (M/F) and in the 90-day subchronic neurotoxicity
study with beta-cyfluthrin, clinical signs of neurotoxicity were
observed at 27/30 mg/kg/day (M/F).  In addition, examination of the
developmental rat studies indicates that while the LOAEL for
beta-cyfluthrin is 10 mg/kg/day (based on decreased body weights and
food consumption), the LOAEL for cyfluthrin is greater than 10 mg/kg/day
(although some slight effects were observed in the range-finding study
at this dose level).  In contrast, when all of the available dog studies
are considered, the NOAEL for the 90-day dog study with beta-cyfluthrin
is 2.36 mg/kg/day with gait abnormalities observed at 13.9 mg/kg/day,
while the NOAELs and LOAELs from the 3 dog feeding studies conducted
with cyfluthrin (one 6-month and two 12- month studies are 5/4/2.4
(NOAELs) and 15/16/10.6 (LOAELs) mg/kg/day, respectively, based on
similar effects.  A comparison of these NOAELs does not indicate any
major differences in toxicity between beta-cyfluthrin and cyfluthrin.  A
comparison of these NOAELs also does not indicate any increase in the
severity of the effects over time (the NOAEL and LOAEL from the new dog
study is lower because of dose spread).  In addition, the NOAELs for the
28-day dog study and the 90-day dog study conducted with beta-cyfluthrin
are similar.  Therefore, it is unlikely that a NOAEL from a chronic dog
study conducted with beta-cyfluthrin would be less than the NOAEL for
the 90-day study conducted with beta-cyfluthrin.  In general, the
neurological clinical signs induced by pyrethroids in dogs appear to be
transient, rather than cumulative.

The NOAEL selected for the chronic RfD would be protective of any
concerns to the offspring in the oral pre-and post-natal studies,
including the developmental neurotoxicity study, because the NOAELs for
the offspring are greater than the selected NOAEL from the chronic dog
study.

3.4.3  Incidental Oral Exposure (Short- and Intermediate-Term)   TC \l3
"3.5.4	Incidental Oral Exposure (Short- and Intermediate-Term) 

Study Selected:  90-Day feeding study in dogs (beta-cyfluthrin)

MRID Number:  41267801

Dose and Endpoint for Risk Assessment:  2.36 mg/kg/day (NOAEL), based on
gait abnormalities beginning in the first week, increased incidence of
vomiting, and suggestive decreased body weight gain observed at 13.9
mg/kg/day (LOAEL)

Uncertainty Factor(s):  100X (10X for interspecies variability, 10X for
intraspecies variability)

Comments about Study/Endpoint/Uncertainty Factor:  For females, the
NOAEL/LOAEL in this study is 2.5/15.4 mg/kg/day. This study is
considered appropriate for short-term oral exposure (1-30 days) because
it is an oral study, and gait abnormalities were observed following 3
exposures.  It is supported by the chronic feeding study in the dog with
cyfluthrin in which vomiting was considered to be related to treatment
and was observed starting on day 1 (NOAEL 2.4 mg/kg/day).  The 90-day
feeding study in dogs is also supported by the acute neurotoxicity study
in rats conducted with beta-cyfluthrin, a single oral dose study with a
NOAEL of 2.0 mg/kg.  This endpoint is also considered appropriate for
intermediate-term exposure (30 days to 6 months) because it is selected
from a subchronic feeding study, the appropriate length and route of
exposure for intermediate incidental oral exposure.

This endpoint would be protective of any concerns to developing fetuses
and/or offspring in the oral prenatal developmental, developmental
neurotoxicity, and reproduction studies.  No developmental effects are
observed in any of these studies at dose levels in the 2.4 mg/kg/day
range.  

3.4.4  Dermal Absorption  TC \l3 "3.5.5	Dermal Absorption 

Dermal Absorption Factor:  5%

No dermal penetration/absorption studies are available for cyfluthrin or
beta-cyfluthrin.  A conservative dermal absorption value of 5% was
calculated as a comparative ratio of toxicity between the oral LOAEL of
50 mg/kg/day from a 28-day feeding study on cyfluthrin in rats and the
dermal LOAEL of 1077 mg/kg/day from a 21-day (18 applications) dermal
study on cyfluthrin in rats.  The basis for both LOAELs included
decreased food consumption; in addition, more severe toxic effects were
observed in the oral study (including gait abnormalities) at the LOAEL,
so the 5% dermal absorption factor is considered to be a conservative
estimate.

The dermal absorption factor is required for short-, intermediate- and
long-term dermal exposure assessments, since the endpoints for each of
these assessments are based on oral studies.

3.4.5  Dermal Exposure (Short- and Intermediate-Term)   TC \l3 "3.5.6
Dermal Exposure (Short-, Intermediate- and Long-Term) 

Study Selected:  90-Day feeding study in dogs (beta-cyfluthrin)

MRID Number:  41267801

Dose and Endpoint for Risk Assessment:  2.36 mg/kg/day (NOAEL), based on
gait abnormalities (both sexes), vomiting (both sexes), and suggestive
decreases in body weight gain observed in males at 13.9 mg/kg/day
(LOAEL)

Uncertainty Factor(s):  100X (10X for interspecies variability, 10X for
intraspecies variability)

Comments about Study/Endpoint/Uncertainty Factor:  For females, the
NOAEL/LOAEL in this study is 2.5/15.4 mg/kg/day.  This endpoint is based
on an oral study and should be used in conjunction with a 5% dermal
absorption factor (section 3.3.4).  

A 21-day dermal toxicity study in rats with a systemic NOAEL of 376
mg/kg/day and LOAEL of 1077 mg/kg/day was available.  The LOAEL was
based on decreased food consumption, red nasal discharge and urine
staining, none of which are considered severely adverse, nor do they
reflect the major target for cyfluthrin (clinical signs of
neurotoxicity).  No clinical signs of neurotoxicity were seen in this
study, while such signs were seen at comparable doses following a single
oral dose in rats as well as following repeated doses in dogs.
Therefore, the HED did not select this study for dermal exposure risk
assessments.  

Instead, the HED determined that an oral study is appropriate for both
short- and intermediate-term dermal exposure because the endpoints of
concern (clinical signs indicative of neurotoxicity) characteristic of
this compound, were seen in the most sensitive species (dog), starting
after 3 exposures.  In addition, this dose and endpoint are supported by
similar findings in the acute neurotoxicity study with beta-cyfluthrin;
the NOAEL was 2 mg/kg/day, and the LOAEL was 10 mg/kg/day based on
clinical signs, changes in FOB parameters, and decreased motor activity.

This endpoint would be protective of any concerns to developing fetuses
and/or offspring in the oral prenatal developmental, developmental
neurotoxicity, and reproduction studies.  No developmental effects are
observed in any of these studies at dose levels in the 2.4 mg/kg/day
range.

It was noted that following inhalation exposure, the developmental NOAEL
(0.00059 mg/L, which converts to 0.16 mg/kg/day) and LOAEL (0.0011 mg/L,
which converts to 0.3 mg/kg/day) are much lower than the dose (2.4
mg/kg/day) selected for this risk assessment. This would indicate that
the NOAEL from the dog study would not be specifically protective of
developmental effects observed in the inhalation studies.  It is noted,
however, that due to the significantly higher potential for absorption
via the inhalation route (complete or 100%) when compared to the dermal
route (5%), a direct comparison of NOAELs from inhalation studies cannot
be made for dermal exposure.

3.4.6  Dermal Exposure (Long-Term)   TC \l3 "3.5.6	Dermal Exposure
(Short-, Intermediate- and Long-Term) 

Study Selected:  Chronic toxicity study in dogs (cyfluthrin)

MRID Number:  44435401

Dose and Endpoint for Risk Assessment:  2.4 mg/kg/day (NOAEL), based on
clinical signs, gait abnormalities, and abnormal postural reactions
observed at 10.64 mg/kg (LOAEL) 

Uncertainty Factor(s):  100X (10X for interspecies variability, 10X for
intraspecies variability)

Comments about Study/Endpoint/Uncertainty Factor:

This endpoint is based on a chronic feeding study, which is the
appropriate length and route of exposure for a chronic endpoint.  It
should be used in conjunction with a 5% dermal absorption factor
(Section 3.3.4).  

3.4.7  Inhalation Exposure (Short-Term)

Study Selected:  4-Week inhalation study in rats (beta-cyfluthrin)

MRID Number:  41783001

Dose and Endpoint for Risk Assessment:  0.07 mg/kg/day (0.00026 mg/L;
NOAEL), based on decreases in body weight in both sexes and decreased
urinary pH in males observed at 0.73 mg/kg/day (0.0027 mg/L; LOAEL)

Uncertainty Factor(s):  100X (10X for interspecies variability, 10X for
intraspecies variability)

Comments about Study/Endpoint/Uncertainty Factor:  This study is of
appropriate duration and route for a short-term endpoint.  The 90-day
inhalation study of cyfluthrin in rats, which results in a lower
NOAEL/LOAEL was not selected because the duration of exposure is not
appropriate for a short-term endpoint.  A 4-week inhalation study in
rats is also available for cyfluthrin; however, it was not selected for
this endpoint because the NOAEL and LOAEL in the 4-week beta-cyfluthrin
inhalation study are lower and protective of effects in both 4-week
studies.  A 5-day inhalation study in rats with beta-cyfluthrin resulted
in the same NOAEL as the 4-week study that was ultimately selected for
this endpoint.  Finally, there are four other inhalation studies which
could have been used for this endpoint: three developmental inhalation
studies and a 7-day postnatal inhalation mouse study.  In all four
studies, qualitative and/or quantitative increased susceptibility was
observed in the offspring; however, all of the observed
developmental/offspring effects are well characterized and definitive
NOAELs can be established for these effects. Therefore, the degree of
concern for these studies is low.  The developmental NOAELs for the
three developmental studies are 0.125 and 0.160 (two combined studies)
mg/kg/day.  The NOAEL for the postnatal mouse study is 2.48 mg/kg/day. 
The proposed endpoint of 0.07 mg/kg/day would be protective of these
developmental/offspring NOAELs, as well as of the toxicity seen in the
remainder of the toxicology database, including all oral studies.

3.4.8  Inhalation Exposure (Intermediate- and Long-Term)

Study Selected:  13-Week inhalation study in rats (cyfluthrin)

MRID Numbers:  00157793, 40082901, 40239301

Dose and Endpoint for Risk Assessment:  0.02 mg/kg/day (0.00009 mg/L;
NOAEL), based on decreased body weights and body weight gains in males
and clinical signs in females observed at 0.16 mg/kg/day (0.000071 mg/L;
LOAEL)

Uncertainty Factor(s):  100X (10X for interspecies variability, 10X for
intraspecies variability)

Comments about Study/Endpoint/Uncertainty Factor:  This is a 13-week
inhalation study which is the appropriate route of exposure and the
appropriate time period for intermediate-term exposure.  For long term
exposure, an uncertainty factor for extrapolating from a subchronic
study to a chronic study will not be applied because there is no
evidence to show that there will be greater toxicity following longer
exposure (see the chronic dietary section for a more complete
discussion).  In addition, this study was conducted with cyfluthrin. 
Although beta-cyfluthrin is more acutely toxic than cyfluthrin, an
uncertainty factor for extrapolating from cyfluthrin to beta-cyfluthrin
was not added.  A comparison of 4-week inhalation data with cyfluthrin
and beta-cyfluthrin is somewhat limited by the differences in dose
spread; however, it does show that the NOAELs and LOAELs are not
significantly different:  the NOAEL and LOAEL for the study conducted
with cyfluthrin are 0.12 and 1.6 mg/kg/day, respectively and the NOAEL
and LOAEL for the study conducted with beta-cyfluthrin are 0.07 and 0.73
mg/kg/day, respectively.  Both 4-week study LOAELs are based on similar
effects, including body weight changes, with additional effects seen at
the higher dose of 1.6 mg/kg/day in the cyfluthrin study.  For further
discussion on this point with the oral data, see the chronic dietary
section.

The discussion on comparison with studies for which there is increased
susceptibility follows the same logic as in Section 3.4.8.  In addition,
the proposed endpoint of 0.02 mg/kg/day is protective of the toxicity
seen in the remainder of the toxicology database, including all oral
studies. 

3.4.9  Level of Concern for Margin of Exposure (MOE)

Table 4.   Summary of Levels of Concern for Risk Assessment.

Route	Short-Term

(1 - 30 Days)	Intermediate-Term

(1 - 6 Months)	Long-Term

(> 6 Months)

Occupational (Worker) Exposure

Dermal	100	100	N/A

Inhalation	100	100	N/A

Residential Exposure

Dermal	100	100	N/A

Inhalation	100	100	N/A

Incidental Oral	100	100	N/A



3.4.10  Recommendation for Aggregate Exposure Risk Assessments

Consistent with FQPA, 1996, HED considers an aggregate risk assessment
when there are potential residential exposures that may result in
exposure from three major pathways (oral, dermal, and inhalation).  The
risks for the different routes of exposure may be aggregated due to the
presence of a common toxicity endpoint (clinical signs of neurotoxicity
and/or body weight effects).

Cyfluthrin/beta-cyfluthrin is currently registered for residential uses
including indoor (e.g. total release fogger and crack and crevice spray)
and outdoor uses (e.g. spray fogger, and lawn applications).  Aggregate
risk assessments for acute, short-term, and intermediate-term durations
were conducted.  In an acute aggregate risk assessment, HED combines
acute dietary exposures (food + water).  For a short-term aggregate risk
assessment, HED combines the average dietary exposures (i.e., the
chronic dietary exposures from DEEM) with the short-term residential
exposure; and, for intermediate-term aggregate risk assessments, HED
combines average dietary exposures (food + water) with intermediate term
residential exposure.  For the residential component of the cyfluthrin
aggregate risk assessment, HED combined exposures from indoor carpet use
and outdoor lawn use to present a conservative residential exposure
scenario.  Exposure pathways from both indoor carpet use and outdoor
lawn use include dermal, inhalation, and oral routes for both short-term
and intermediate-term durations (see HED memo D283388; S. Tadayon;
7/31/03, and HED memo; Y. Donovan; D290925; 7/15/05).

3.4.11  Classification of Carcinogenic Potential

On March 14, 1986, HED classified cyfluthrin as a Category E carcinogen
(no evidence of carcinogenicity) based on the two older rat and mouse
studies.  Based on the new and old studies, cyfluthrin is classified as
“not likely to be carcinogenic to humans” (HIARC, 2001).

3.4.12  Summary of Toxicological Doses and Endpoints for Cyfluthrin and
Beta-Cyfluthrin for Use in Human Health Risk Assessments

A summary of toxicological endpoints and doses for use in the both the
dietary and non-occupational risk assessment as well as the occupational
assessment of cyfluthrin/beta-cyfluthrin is contained in Table 5, below.
 

Table 5.  Toxicological Doses and Endpoints for Cyfluthrin and
Beta-Cyfluthrin for Use in Non-Occupational Human Health Risk
Assessments.

Exposure/

Scenario	Point of Departure	Uncertainty Factors	Level of Concern for
Risk Assessment	Study and Toxicological Effects

Acute Dietary (All Populations)	NOAEL= 2 mg/kg	UFA= 10x

UFH = 10x

FQPA SF= 1x

	Acute RfD = 

0.02 mg/kg

aPAD =

0.02 mg/kg	Acute neurotoxicity in rats (beta-cyfluthrin)

LOAEL = 10 mg/kg based on clinical signs, changes in FOB parameters, and
decreases in motor activity. 

Chronic Dietary 

(All Populations)	NOAEL= 2.4 mg/kg/day	UFA= 10x

UFH = 10x

FQPA SF= 1x

	Chronic RfD = 

0.024 mg/kg/day

cPAD =

0.024 mg/kg/day	Chronic toxicity in dogs (cyfluthrin)

LOAEL = 10.64 mg/kg/day based on   clinical signs, gait abnormalities,
and abnormal postural reactions. 

Incidental Oral

Short- (1-30 Days) and Intermediate- Term (1 - 6 Months)	NOAEL= 2.36
mg/kg/day	UFA= 10x

UFH = 10x

FQPA SF= 1x

	Residential LOC for MOE = 100	90-Day feeding study in dogs
(beta-cyfluthrin)

LOAEL = 13.9/15.4 mg/kg/day (M/F) based on gait abnormalities, increased
incidence of vomiting, and suggestive decreased body weight gain.

Dermal 

Short- (1-30 Days) and Intermediate- Term (1 - 6 Months)	NOAEL= 2.36
mg/kg/day

Dermal absorption rate =  5%	UFA= 10x

UFH = 10x

FQPA SF= 1x

	Residential LOC for MOE = 100	90-Day dog feeding study
(beta-cyfluthrin)

LOAEL = 13.9/15.4 mg/kg/day (M/F) based on gait abnormalities, increased
incidence of vomiting, and suggestive decreased body weight gain.

Dermal 

Long-Term (>6 Months)	NOAEL= 2.4 mg/kg/day

Dermal absorption rate =  5%	UFA= 10x

UFH = 10x

FQPA SF= 1x

	Residential LOC for MOE = 100	Chronic toxicity in dogs (cyfluthrin)

LOAEL = 10.64 mg/kg/day based on   clinical signs, gait abnormalities,
and abnormal postural reactions.

Inhalation

Short-Term 

(1-30 Days)	NOAEL= 0.00026 mg/L 

(0.07 mg/kg/day)	UFA= 10x

UFH = 10x

FQPA SF= 1x

	Residential LOC for MOE = 100	28-Day rat inhalation study
(beta-cyfluthrin)

LOAEL = 0.0027 mg/L (0.73 mg/kg/day) based on decreases in body weight
in both sexes and decreased urinary pH in males.

Inhalation

Intermediate- (1-6 months) and Long-Term (>6 months)	NOAEL= 0.00009 mg/L


(0.02 mg/kg/day)	UFA= 10x

UFH = 10x

FQPA SF= 1x

	Residential LOC for MOE = 100	13-Week rat inhalation study (cyfluthrin)


LOAEL =  0.00071 mg/L (0.16 mg/kg/day) based on decreases in body weight
and body weight gain in males and clinical signs in females.

Cancer (oral, dermal, inhalation)	Classification:  “Not likely to be
Carcinogenic to Humans”

Point of Departure (POD) = A data point or an estimated point that is
derived from observed dose-response data and  used to mark the beginning
of extrapolation to determine risk associated with lower environmentally
relevant human exposures.  NOAEL = no observed adverse effect level. 
LOAEL = lowest observed adverse effect level.  UF = uncertainty factor. 
UFA = extrapolation from animal to human (interspecies).  UFH =
potential variation in sensitivity among members of the human population
(intraspecies).  FQPA SF = FQPA Safety Factor.  PAD = population
adjusted dose (a = acute, c = chronic).  RfD = reference dose.  MOE =
margin of exposure.  LOC = level of concern.  N/A = not applicable.

3.5  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 the
recommendations of its Endocrine Disruptor Screening and Testing
Advisory Committee (EDSTAC), EPA determined that there was 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
FIFRA and, to the extent that effects in wildlife may help determine
whether a substance may have an effect in humans, FFDCA has 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).

When the appropriate screening and/or testing protocols being considered
under the Agency’s EDSP have been developed, beta-cyfluthrin may be
subjected to additional screening and/or testing to better characterize
effects related to endocrine disruption.

4.0  Public Health and Pesticide Epidemiology Data

No public health data are being considered at this time.

5.0  Dietary Exposure/Risk Characterization

5.1  Metabolism and Environmental Degradation

5.1.1    Metabolism in Primary Crops

HED has concluded that the nature of cyfluthrin/beta-cyfluthrin in
plants is adequately understood based on plant metabolism studies
conducted in cotton, soybeans, potatoes, apples, wheat, and tomatoes. 
Data from those studies indicate that the nature of the residue is
similar in all plant matrices.  The major detected residue is the parent
cyfluthrin which comprised between 38% – 98% of the total radioactive
residues (TRR).  In plants, cyfluthrin was seen to metabolize slowly
with little translocation.  Other metabolites detected, including
FPBalc, FPBald, FPBacid, FPBamide, FPB methyl ester, and 4'-OH-FPBacid,
generally comprised <10% of the TRR.  HED, therefore, has determined
that the residue of concern in plants is cyfluthrin per se.  The nature
of cyfluthrin residues in plants is summarized in the HED memorandum
Registration for Use on Grasses, Alfalfa, and Seed Treatment Use on
Sugar Beets, (D. Dotson; D339413; 10/15/2007).

5.1.2  Metabolism in Livestock

The nature of cyfluthrin/beta-cyfluthrin is adequately understood in
livestock based upon metabolism data in cattle and poultry.  In
lactating cows the parent comprised 56-100% of the TRR in tissues and
milk.  In poultry, the parent comprised 28-56% of the TRR in muscle,
fat, skin, and eggs, (in poultry liver and kidney, the parent comprised
9-12% of the TRR).  Metabolites (FPBalc, FPBald, FPBacid, and
4'-OH-FPBacid), comprised 0-43% of the TRR in cow tissues and milk and
0-19% of the TRR in poultry tissues and eggs.  The residue of concern in
animals is cyfluthrin, per se.

5.1.3  Analytical Methodology

Residue Analytical Method

Adequate GC/ECD methods are available in PAM Vol. II for enforcing
tolerances for cyfluthrin/beta-cyfluthrin residues in/on plant
commodities (Method 85823) and animal commodities (Method 85883).  The
limit of detection for cyfluthrin/beta-cyfluthrin in both methods is
0.01 ppm in the tested plant and animal commodities.

In the current grass, alfalfa, and sugar beet field trials, as well as
the sugar beet processing study, samples were analyzed for residues of
cyfluthrin using Bayer Method 108139-1 (GC/MS).  This method was
previously reviewed by the Agency and deemed adequate for data
collection, and was adequately validated on grass, alfalfa, and sugar
beet commodities in conjunction with the analysis of field trial and
processing study samples.

The validated limit of quantitation (LOQ) for cyfluthrin residues in
grass forage and hay is 0.05 ppm, and the statistically calculated limit
of detection (LOD) is 0.014 ppm for forage, and 0.020 ppm for hay.  The
validated LOQ for cyfluthrin residues is 0.01 ppm for all sugar beet
commodities, and the statistically calculated LODs are 0.003 ppm for
tops and roots, and 0.0011-0.0018 ppm for processed fractions.

Multiresidue Method

Data pertaining to the recovery of cyfluthrin using FDA's multiresidue
methods were submitted in 1998 (MRID 40355901), and forwarded to FDA. 
The FDA Pestrak Data Base (PAM Vol. I, Appendix, dated 11/6/90)
indicates that complete recovery has been obtained for cyfluthrin using
FDA multiresidue methods.

5.1.4  Environmental Degradation

Cyfluthrin is moderately persistent in the environment and immobile.  
Data suggest that the primary routes of dissipation include hydrolysis
in alkaline media (T½ = stable, essentially stable and 2.1 days at
pH’s 5, 7 and 9 respectively); aqueous photolysis (T½ = 0.7 - 4.5
days); and, soil photolysis (T½ = 5.6 days).  Data indicate that
aerobic soil metabolism plays a secondary role in the dissipation of
cyfluthrin (T½ = ranged from 73.5 and 94.8 days).  Data show that
cyfluthrin degrades slowly under normal conditions of aerobicity and
organic matter, but degrades faster under anaerobic environments or in
soils with higher organic matter.  While moisture level does not appear
to have a significant effect on cyfluthrin’s rate of degradation, pH
does (degrading faster in conditions of higher pH).

Similar to other pyrethroids, cyfluthrin is hydrophobic, binding
strongly to soil surfaces. The moderate persistence of the chemical, its
high soil affinity and low solubility indicate (i) a low potential to
leach to subsurfaces and to contaminate groundwater; and, (ii) that the
chemical has a high potential to reach surface waters in runoff events
accompanied by erosion occurring during periods of weeks to months after
application.  Once the chemical reaches surface waters, the potential
impact to water quality appears to be mostly due to parent compound. 
Cyfluthrin residues could also reach surface waters via spray drift.   

Once cyfluthrin reaches surface waters, the potential impact to water
quality appears to be mostly due to cyfluthrin, per se.  Laboratory
studies predict that once the chemical reaches surface waters, it may
persist for moderate periods of time.  Cyfluthrin’s lipophilicity and
affinity to particulate make it unavailable to photolysis.  In addition,
photolysis would be limited only to clear shallow waters or the upper
layers of the water column.  

5.1.5  Pesticide Metabolites and Degradates of Concern

The HED previously determined that the residue of concern in all
matrices (plants, livestock, and drinking water) is cyfluthrin, per se
(MARC Decision Memorandum; 6/13/02; TXR 0050805).  The cyfluthrin risk
assessment team is in agreement with this previous determination.

Table 6. Summary of Metabolites and Degradates to be included in the
Cyfluthrin/Beta-cyfluthrin Risk Assessment and Tolerance Expression*

Matrix	Residues included in Risk Assessment	Residues included in
Tolerance Expression



	Primary Crop	Cyfluthrin, per se	Cyfluthrin, per se

	Rotational Crop	N/A	N/A

	Ruminant	Cyfluthrin, per se	Cyfluthrin, per se

	Poultry	Cyfluthrin, per se	Cyfluthrin, per se

	Drinking Water	Cyfluthrin, per se	Not Applicable

* Although most of the residue from for use of beta-cyfluthrin consists
of the enriched isomers of that active ingredient, low percentages of
the other isomers are present and the analytical method does not
distinguish between the isomers of cyfluthrin and beta-cyfluthrin. 
Therefore, the residue of concern from use of beta-cyfluthrin for
practical purposes is cyfluthrin.

5.1.6  Drinking Water Residue Profile

Estimates of cyfluthrin residues in drinking water were provided by the
Environmental Fate and Effects Division (J.L. Melendez 9/6/2007;
D331952; D340739) and incorporated directly into the dietary assessment.
 Acute and chronic screening level estimates of drinking water
concentrations (EDWCs) in surface water were generated using FIRST
v.1.1.0, (Dec. 12, 2005), and ground water concentration estimates were
generated using SCI-GROW v.2.3, (Jul 29, 2003).

Based on survey of all the currently registered and proposed uses of
cyfluthrin, it was determined that cyfluthrin use on alfalfa and cotton
would lead to the highest surface water and ground water drinking water
exposure estimates (EDWCs), respectively.  Based upon the proposed use
of cyfluthrin on alfalfa (0.35 lb ai/acre/season), the acute drinking
water concentration in surface water is 3.677 ppb, and the chronic EDWC
is estimated to be 0.155 ppb.  The SCI-GROW generated EDWC (in
groundwater) is 0.457 ppb of cyfluthrin, which is recommended for use
both for acute and chronic exposures.  EDWCs are summarized in Table 7.

Table 7.  Estimated Drinking Water Concentrations for
Cyfluthrin/Beta-cyfluthrin

Duration	Application Rate	Surface Water Concentration (ppb)	Groundwater
Concentration (ppb)

Acute	0.35 lb ai/A/season(alfalfa)	3.677	0.457

Chronic

(non-cancer)	0.50 lb. ai/A/season (cotton)	0.155	0.457



5.1.7  Food Residue Profile

5.1.7.1  Crop Field Trials

Grasses

The available field trial data for grasses adequately reflect geographic
distribution, application rate, and proposed PHI.  The data support the
use of cyfluthrin/beta-cyfluthrin on grasses at up to four broadcast
foliar applications at a maximum single application rate of 0.044 lb
ai/A, with a minimum RTI of 5 days, for a maximum use rate of 0.178 lb
ai/A/season.  The data also support a 0-day PHI for cutting of both
forage and hay.  The available data support proposed tolerances of 50
ppm cyfluthrin/beta-cyfluthrin on grass hay and 12 ppm
cyfluthrin/beta-cyfluthrin on grass forage.

The field trial data using the emulsifiable concentrate (EC) formulation
of cyfluthrin on grasses also support the use of the WP formulation on
grass, since previous side-by-side tests on numerous crops using EC and
WP formulations of cyfluthrin have shown that the use of an EC
formulation typically results in higher crop residues than use of a WP. 
Also, in accordance with an earlier HED decision the current field trial
data for cyfluthrin (conducted with cyfluthrin) also support the use of
beta-cyfluthrin at a maximum of 0.022 lb ai/A/application for a total
use rate of 0.089 lb ai/A/season.

Alfalfa

Crop field trial data was submitted to support the use of cyfluthrin on
alfalfa (EC).   The highest average field trial (HAFT) value reported
for cyfluthrin residue in/on alfalfa forage was 5.65 ppm (max.
individual value 5.88 ppm).  The HAFT value for cyfluthrin residue in/on
alfalfa hay was 15.27 ppm (max. individual value 16.49 ppm).  HED used
the recent guidance for setting tolerances based on field trial data and
determined the appropriate tolerances for alfalfa forage to be 5.0 ppm,
and for alfalfa hay to be 13 ppm.

Sugar Beets

The available field trial data for sugar beet seed treatment was
conducted with cyfluthrin, and adequately support the use of cyfluthrin
on sugar beet seed at an application rate of 0.035 lb ai/100,000 seeds. 
These data also support the use of beta/cyfluthrin at a maximum
application rate of 0.017 lb ai/100,000 seeds.  These data adequately
reflect geographic distribution, and samples were collected at normal
crop maturity.  The samples were analyzed using an adequate analytical
method and the sample storage durations are supported by the available
storage stability data.  Field trial values for both sugar beet roots
and tops were below the LOQ, and as a result, HED’s statistical
tolerance generator was not used to determine tolerances.  Therefore,
HED recommends that the tolerance be set at 0.10 ppm.

Cereal Grains Except Rice (Crop Group 15)

A tolerance of 4.0 ppm is currently in effect for residues of
cyfluthrin/beta-cyfluthrin in the Cereal Grain Crop Group (Group 15). 
This tolerance covers residues resulting from stored grain uses as well
as from foliar applications.  In 2004, HED recommended that the stored
grain uses be cancelled (Y. Donovan, 12/16/04, D290921), but noted that
cancellation of these uses should only occur after the product cleared
the channels of trade.  Currently, HED has reviewed field trial data
that were originally reviewed between 1998 and 2004 regarding foliar
applications to wheat, field corn, sweet corn, and sorghum.

Wheat

Field trial data for foliar applications to wheat were submitted and
reviewed in 2004.  In its 2004 review, HED recommended that the cereal
grain crop group tolerance of 4.0 ppm be revoked and that a tolerance of
0.2 ppm be established in wheat grain.  However, the statistically
generated tolerance, which is currently required by HED policy, is 0.15
ppm.  As a result, HED recommends that the wheat grain tolerance be
established at 0.15 ppm (rather than the 0.2 ppm tolerance proposed in
2002).  This 0.15 ppm tolerance should be extended to the following
cereal grains:  barley, buckwheat, millet, oats, and rye.  

Field Corn

Field trial data for field corn have been submitted and reviewed.  HED
previously concluded that the corn grain tolerance of 0.01 ppm was
adequate to cover the existing at-plant and foliar uses.  However, the
0.01 ppm tolerance was not in harmonization with the Codex MRL (0.05
ppm).  In 2002, HED did not recommend harmonizing the field corn grain
tolerance with the Codex MRL owing to a pending stored grain use
tolerance of 4.0 ppm.  Since that time, the stored grain registrations
have been cancelled, and as a result, HED now recommends that the field
corn grain tolerance be harmonized with the Codex MRL.  Therefore, HED
recommends in favor of a tolerance of 0.05 ppm in field corn grain.  The
recommended tolerances for cyfluthrin resides on animal feed items
associated with field corn are discussed below, in the section entitled
Forage, Fodder, and Straw of Cereal Grains Group Except Rice (Crop Group
16).

Corn

Field trial data for sweet corn were evaluated by HED in 1989 and 1995. 
A tolerance of 0.05 ppm was established for sweet corn, kernel plus cob
with husks removed.  This tolerance is currently in effect and is
equivalent to the Codex MRL of 0.05 ppm in maize.  HED recommends that
this tolerance remain in effect.  Tolerances are also in effect in sweet
corn forage and stover.  HED’s recommendations concerning these
tolerances are discussed in the section below, entitled Forage, Fodder,
and Straw of Cereal Grains Group Except Rice (Crop Group 16).

Sorghum

In 1996 HED recommended in favor of a 4.0 ppm tolerance for residues in
sorghum grain resulting from foliar applications.  In 2004, HED
recommended that the sorghum grain tolerance be re-established based on
pre-harvest uses of cyfluthrin.  This tolerance is equivalent to the
cereal grain crop group tolerance being cancelled, i.e., 4.0 ppm.  
However, under current HED policy, the statistically generated tolerance
for sorghum grain is 3.5 ppm.   The recommended tolerances for animal
feed items associated with sorghum are discussed in the section below.

Rice

Rice is a member of the cereal grains crop group, and therefore, was
covered by the 4.0 ppm tolerance set in that crop group.  However, since
these uses have been cancelled the tolerance in rice should also be
removed.  Since there are no further registrations for foliar
application of cyfluthrin to rice, HED recommends that no new tolerance
in rice be established.

Forage, Fodder, and Straw of Cereal Grains Group Except Rice (Crop Group
16)

Adequate field trial data have been submitted for wheat forage, fodder,
and straw, field corn forage and fodder, sweet corn forage and stover,
and sorghum forage and stover.  Tolerances based upon these data are
currently in effect.  The registrant has requested a tolerance in Crop
Group 16, the Forage, Fodder, and Hay of the Cereal Grains (Except Rice)
Group, and has proposed a tolerance of 7.0 ppm in the entire crop group.
 Below is HED’s current analysis of the data relevant to the petition
for a Crop Group 16 tolerance.

Forage

Forage field trial data are available for wheat, field corn, sweet corn,
and sorghum.  The current tolerance in sweet corn forage is 15 ppm and
is based upon field trial data submitted in 1989 and 1990.  Residue
values recorded in these data ranged from 2.97 ppm to 53.2 ppm.  For
statistical reasons, HED believed that the 53.2 ppm value was aberrant,
and so based the existing 15 ppm tolerance on the next lowest value in
that data set, (13.6 ppm).  For the current recommendation the same data
set was re-analyzed with HED’s statistical tolerance generator.  Based
upon the result of the tolerance generator, HED recommends that the
tolerance in the forage of the Cereal Grains Crop Group (Except Rice) be
set at 25 ppm.

Stover

Stover field trial data are available for field corn, sweet corn, and
sorghum.  The individual field trial values obtained for the stover of
each commodity were entered into HED’s statistical tolerance generator
to determine the recommended tolerance for each.  As a result, HED
recommends that the tolerance for the stover of the Cereal Grains Crop
Group (Except Rice) be set at 30 ppm, which is the highest value of the
three stover forms.  A tolerance of 30 ppm is currently in effect for
sweet corn stover.  HED recommends that this tolerance be extended to
the stover of the other cereal grains (except rice).

Hay

The only commodity for which hay field trial data are available is
wheat.  Based upon the statistical tolerance generator, HED recommends
that this tolerance be set at 6.0 ppm and be applied to hay of the
Cereal Grains Crop Group (except rice).

Straw

The only commodity for which straw field trial data are available is
wheat.  Based upon the statistical tolerance generator, HED recommends
that this tolerance be set at 7.0 ppm and be applied to straw of the
Cereal Grains Crop Group (except rice).

5.1.7.2  Revocation of Certain Tolerances

Since crop group tolerances are being established in the forage, stover,
hay, and straw of the cereal grains commodities, the individual
tolerances that are currently in effect should be revoked.  These
tolerances include the following:  wheat forage (5.0 ppm), wheat hay
(6.0 ppm), wheat straw (6.0 ppm), field corn forage (3.0 ppm), field
corn stover (6.0 ppm), popcorn stover (6.0 ppm), sweet corn forage (15
ppm), sweet corn stover (30 ppm), sorghum grain forage (2.0 ppm), and
sorghum grain stover (5.0 ppm).  A Tolerance Summary table for
cyfluthrin/beta-cyfluthrin can be found in Appendix C.  

5.1.7.3  Processed Food and Feed

Grass

There are no regulated processed commodities associated with grass.

Sugar Beets

sing all values ≥LOD for each commodity, the processing factors were
calculated to be <0.3x for refined sugar, <0.2x for molasses, and 12x
for dried pulp.

Cereal Grains Crop Group Except Rice

Wheat

In 2004, HED recommended in favor of a 0.5 ppm tolerance in wheat bran. 
However, at that time a 6.5 ppm tolerance was established based upon the
stored grains use.  Since the stored grains use has been cancelled, HED
recommends that the current 6.5 ppm tolerance in wheat bran be decreased
to 0.5 ppm.

Corn

An acceptable field corn processing study was submitted in 2002.  Even
though the residues in processed commodities were not measured, HED
concluded that residues would not exceed 0.01 ppm.  There is a current
corn oil tolerance of 30 ppm, which was established in conjunction with
the stored grain uses; however, this use is being cancelled.  Therefore,
HED recommends that the 30 ppm tolerance be revoked.  The recommended
corn grain tolerance of 0.05 ppm will be adequate to cover residues in
field corn, refined oil.

Rice

The current tolerances in effect for rice bran (6.0 ppm) and hulls (18.0
ppm) are derived from rice as a component of the cereal grains crop
group.  As mentioned above, the cereal grains group tolerance is being
cancelled.  Therefore, since there are no other registrations for foliar
application of cyfluthrin/beta-cyfluthrin to rice, the current
tolerances for rice bran and hulls should be revoked.

5.1.7.4  International Residue Limits

Whenever possible, HED attempts to harmonize with Codex MRLs.  As stated
above, HED currently recommends that the field corn grain tolerance be
harmonized with the Codex MRL, and set at 0.05 ppm.  The current 0.05
ppm tolerance in sweet corn, kernel plus cob with husks removed is
harmonized with the Codex MRL for maize.  Regarding international
harmonization of the proposed tolerances associated with the subject
petitions (grasses, and sugar beet), there are no established or
proposed Canadian, Mexican or Codex MRLs for cyfluthrin residues. 

5.2  Dietary Exposure and Risk

Acute and chronic dietary exposures via food and drinking water result
from the currently registered and proposed uses of
cyfluthrin/beta-cyfluthrin.  A full discussion of the refined dietary
exposure from the registered and proposed uses of
cyfluthrin/beta-cyfluthrin can be found in the HED memorandum Cyfluthrin
and Beta-Cyfluthrin Acute Probabilistic and Chronic Dietary Exposure
Assessments for the Section 3 Registration Actions, (D. Dotson;
10/15/07; D339414).  

Permanent tolerances are established for residues of cyfluthrin in/on a
wide variety of plant commodities at levels ranging from 0.01 ppm in/on
peanuts, tree nuts, and tuberous and corm vegetables to 600 ppm in/on
aspirated grain fractions (40CFR §180.436).  Tolerances are also
established on animal commodities at levels ranging from 0.01 ppm in
eggs and poultry fat, meat, and meat byproducts to 30 ppm in milk fat;
as well as a tolerance for the use of cyfluthrin in food and feed
handling establishments.  The Agency previously concluded that
tolerances for cyfluthrin will also cover beta-cyfluthrin provided that
the use rates for beta-cyfluthrin are ½ the use rates of cyfluthrin.

The current dietary analyses are refined, incorporating the most
appropriate factor(s) to estimate residues of cyfluthrin/beta-cyfluthrin
in/on agricultural commodities or animal commodities.  Dietary residue
estimates were refined using: (i) empirical and default processing
factors; (ii) percent crop treated estimates and projected percent crop
treated estimates; and, (iii) monitoring data.  The dietary exposure
estimates reflect: (i) currently registered and proposed agricultural
crops; (ii) residues resulting from animal feed treatment; (iii)
secondary residues from use of cyfluthrin/beta-cyfluthrin as a direct
animal treatment; and, (iv) for the chronic analysis, residues resulting
from treatment of food handling establishments.

5.2.1  Dietary Exposure Refinements

Processing factors were available for many of the commodities in the
analysis.  Various studies provided by the registrant characterize the
effect (reduction or concentration) of the pesticide on a commodity as a
result of various processing or preparation procedures such as washing,
juicing, drying, peeling, trimming, oil extraction, etc.  When empirical
processing factors were not available, default processing factors were
used.  Where appropriate, HED translated a processing factor from one
commodity to another, and when two processing factors were available
(e.g., a processing factor for washing leaf lettuce and one for washing
mustard greens), HED chose the more conservative value.  HED does not
apply a processing factor to a commodity where monitoring data is
available, since monitored commodities already reflect food preparation
practices which processing factors aim to characterize.  Processing
factors are applicable when estimating both acute and chronic dietary
exposures.

Percent crop treated values were applied to further refine residue
estimates.  For crops which are currently registered, percent crop
treated values are taken from the USDA’s National Agricultural
Statistics Service.  HED used projected percent crop treated values
where tolerances are being proposed or where usage information is not
yet available.  In the acute dietary analysis, the maximum percent crop
treated value is applied, whereas in the chronic analysis the average
percent crop treated value is used.

Tolerances for cyfluthrin/beta-cyfluthrin exist in animal (cattle, goat,
hog, poultry, and sheep) meat, meat byproducts and fat, as well as in
milk and eggs.  Residue values for these commodities were entered either
as the established tolerance value, or refined by deriving a secondary
residue estimate (which incorporates refined residue estimates on animal
feed items).  The current secondary residue estimates for
cyfluthrin/beta-cyfluthrin also reflect updated guidance, and therefore,
differs from secondary residue estimates contained in previous
cyfluthrin/beta-cyfluthrin risk assessments.  The secondary residue
estimates from cattle (residues in tissues and in milk) reflected not
only exposure to the animal via the diet but also exposure from a direct
“pour-on” treatment (currently registered for application to beef
and dairy cattle only).  Residues resulting from both these pathways
were added together in order to determine the total secondary residues
in cattle commodities.

The current dietary risk assessment also reflects proposed changes to
the cyfluthrin/beta-cyfluthrin tolerance expression resulting from
current petitions and changes to guidance regarding livestock diets as
discussed above.

5.2.2  Acute and Chronic Dietary Exposure/Risk

To calculate dietary exposure, residue estimates are coupled with
consumption information.  The Dietary Exposure Evaluation Model software
with the Food Commodity Intake Database (DEEM-FCID, V. 2.03) integrates
consumption data from USDA’s Continuing Surveys of Food Intakes by
Individuals (CSFII), 1994-1996, and 1998.  Based upon the 1994-1996, and
1998 CSFII consumption data, HED concluded that is appropriate to report
risk for the following population subgroups: the general U.S.
population; all infants (< 1); children 1-2; children 3-5; children
6-12; youth 13-19 adults 20-49; females 13-49; and, adults 50+ yrs old. 
For acute dietary scenarios, consumption data are retained as individual
components whereas for chronic dietary scenarios, consumption data are
averaged for the entire US population and within population subgroups. 
Estimated concentrations of cyfluthrin/beta-cyfluthrin in drinking
water, Sec. 5.1.6, are incorporated directly into the dietary analysis. 
Finally, dietary exposure estimates are compared to either the acute
population adjusted dose (aPAD), or the chronic population adjusted dose
(cPAD).  (The aPAD and cPAD are arrived at by dividing the endpoint/dose
by the appropriate uncertainty factors and FQPA factor.)  Exposures that
exceed 100% of the aPAD or cPAD are a risk concern to HED.

Estimated acute dietary risks for the U.S population and all population
subgroups are not of concern to HED at the 99.9th percentile.  Estimated
chronic dietary risks for the U.S. population and all population
subgroups are also not of concern to HED.  The results of the chronic
dietary exposure analysis are reported in Table 8.

Table 8.  Summary of Dietary Exposure and Risk for Cyfluthrin 

Population Subgroup	Acute Dietary Exposure	% aPAD

(99.9th Percentile)	Chronic Dietary Exposure	% cPAD

General U.S. Population	0.006378	32	0.001195	5

All Infants < 1 yr old	0.007614	38	0.002075	8.6

Children 1-2 yrs old	0.010536	53	0.004084	17

Children 3-5 yrs old	0.009869	49	0.002951	12

Children 6-12 yrs old	0.004907	25	0.001750	7.3

Youth 13-19 yrs old	0.005287	26	0.000973	4.1

Adults 20-40 yrs old	0.005390	27	0.000865	3.6

Adults 50+  yrs old	0.006398	32	0.000909	3.8

Females 13-49 yrs old	0.004788	24	0.000855	3.6



5.2.3  Cancer Dietary Risk

HED has classified cyfluthrin as “not likely to be carcinogenic to
humans.”  Based upon this classification, HED has determined there is
insufficient hazard to warrant a cancer dietary risk assessment.

			

6.0  Residential (Non-Occupational) Exposure/Risk Characterization

The current petitions do not involve any residential/non-occupational
uses.  However, several active cyfluthrin products are registered for
use at residential sites including indoor (e.g. total release fogger,
and crack and crevice spray) and outdoor uses (e.g. spray fogger, and
lawn applications).  In 2002, HED completed an updated
residential/non-occupational assessment of these uses (D283388; S.
Tadayon; 7/31/02).  Estimated risks from the
residential/non-occupational uses were not of concern to HED.  The 2002
assessment was considered screening level since it did not reflect
applicable revisions to the HED Residential Exposure SOPs. 
Incorporation of the updated SOPs would have refined the exposure
estimates and likely would have resulted in higher MOEs.  Risks for the
population subgroups at greatest risk, from both indoor and outdoor
residential uses of cyfluthrin are summarized below in Table 9. 



Table 9.  Selected MOEs for Residential/Non-Occupational Uses of
Cyfluthrin 

Scenario	Population Subgroup	Duration



Short-term duration	Intermediate-term duration

Indoor Uses (carpet use)	All infants < 1year	1300	490

Outdoor Uses (lawn use)	All infants < 1 year	1400	920

	Adults	1600	540



6.1  Spray Drift

Spray drift is always a potential source of exposure to residents near
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.  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.

HED notes that 0.14 lb ai/acre was the application rate use to estimate
non-occupational/residential exposure from cyfluthrin/beta-cyfluthrin
use on lawns.  Since this rate is equal to or higher than many of the
agricultural application rates, the scenario is protective of any
exposure of farm children, including toddlers, via spray drift from
agricultural cyfluthrin/beta-cyfluthrin applications.

7.0  Aggregate Risk Assessments and Risk Characterization

Consistent with FQPA, HED considers aggregate risk to pesticide
exposures that come from three major sources: food, drinking water, and
residential uses.  In an aggregate assessment, exposures from relevant
sources are added together and compared to quantitative estimates of
hazard (e.g., a NOAEL or PAD), or the risks themselves can be
aggregated.  When aggregating exposures and risks from various sources,
HED considers both the route (oral, dermal, and inhalation) and duration
of exposure.  

Based upon the non-occupational/residential uses of cyfluthrin, HED has
determined that acute, short-term, intermediate-term, and chronic
aggregate risk assessments are appropriate.  For the short-term and
intermediate-term aggregate assessments, HED combined the two potential
residential exposure scenarios (indoor carpet, and outdoor lawn) for a
single worst-case residential exposure component.  (Estimates of
exposure and risk from residential uses of cyfluthrin/beta-cyfluthrin
can be found in HED document D283388; S. Tadayon; 7/31/03).  For both
short-term and intermediate-term scenarios, HED estimated aggregate risk
to the general U.S. population, infants (< 1 year), and children (1 –
2 years). 

7.1  Acute Aggregate Risk

The acute aggregate risk is equal to dietary exposure via food and
drinking water, and is identical to the exposure and risk characterized
in Section 5.2.2.  Acute aggregate risks for cyfluthrin/beta-cyfluthrin
are less than 100% of the aPAD and therefore, do not present a risk
concern to HED.  

7.2  Short-Term and Intermediate-Term Aggregate Risk

To estimate short-term aggregate risk, HED combined the chronic dietary
(food + water) exposures (as a measure of average dietary exposure) with
the short-term residential exposure.  To estimate intermediate-term
aggregate risk HED combined chronic dietary (food + water) exposures
with intermediate term residential exposure.  Short-term and
intermediate-term aggregate risks are summarized in Tables 10 and 11
below.

Table 10.  Short-Term Aggregate Risk Calculations for Cyfluthrin

Population

Subgroup	Average Dietary	Residential (indoor carpet + outdoor lawn)1
Aggregate MOE6

	Dietary 

(food + water)	Residential

Inhalation	Residential

Dermal	Residential

Incidental Oral



Exposure	MOEf+w2	Exposure	MOEI3	Exposure	MOED4	Exposure	MOEO5

	U.S population	0.001195	2000	5.7E-5	1200	2.5E-3	940	Not assessed	Not
assessed	420

Infant

(<1 yr)	0.002075	1100	4.6E-5	1500	1.5E-3	1600	6.9E-4	3400	400

Child

(1-2 yrs)	0.004084	580	3.6E-5	1900	1.4E-3	1700	6.4E-4	3700	320

1 Individual exposure values for residential uses can be found in HED
Memo; S. Tadayon; 6/31/0; D28338.  Exposure values and MOEs for combined
residential exposures can be found in HED Memo; Y. Donovan; 7/15/05;
D290925.

2 MOE food + water : short-term oral NOAEL = (2.36 mg/kg/day) / chronic
dietary exposure from DEEM.

3 MOE inhalation = short-term inhalation NOAEL (0.07
mg/kg/day)/residential inhalation exposure

4 MOE dermal = short-term dermal NOAEL (2.36 mg/kg/day)/dermal
residential exposure.  Dermal exposure adjusted with 5% dermal
absorption factor. 

5 MOE oral = short-term incidental oral NOAEL (2.36
mg/kg/day)/hand-to-mouth residential exposure.

6 Aggregate MOE (food + water + residential) =

__________________1__________________

1/MOE f+w  +  1/MOEI       +  1/MOED     +  1/MOEO



Table 11.  Intermediate-Term Aggregate Risk Calculations for
Cyfluthrin/Beta-Cyfluthrin

Population Subgroup	Average Dietary	Residential (indoor carpet + outdoor
lawn)1	Aggregate MOE6

	Dietary

(food + water)	Residential

Inhalation	Residential

Dermal	Residential

Incidental Oral



Exposure	MOE2f+w	Exposure	MOE3I	Exposure	MOE4D	Exposure	MOE5O

	U.S.

Population	0.001195	2000	5.7E-5	350	2.5E-3	940	Not assessed	Not assessed
220

Infant

(<1 yr)	0.002075	1100	4.6E-5

	430

	1.5E-3

	1600

	6.9E-4

	3400

	240

Child 

(1-2 yrs)	0.004084	580	3.6E-5	560	1.4E-3	1700	6.4E-4	3700	230

1: Individual exposure values for residential uses can be found in HED
Memo; S. Tadayon; 6/31/0; D28338.  Exposure values and MOEs for combined
residential exposures can be found in HED Memo; Y. Donovan;
7/15/05;D290925.

2: MOE food + water = intermediate-term oral NOAEL (2.36
mg/kg/day)/chronic dietary exposure from DEEM.

3: MOE inhalation = intermediate-term inhalation NOAEL (0.02
mg/kg/day)/residential inhalation exposure

4: MOE dermal = intermediate-term dermal NOAEL (2.36 mg/kg/day)/dermal
residential exposure.  Dermal exposure adjusted with 5% dermal
absorption factor. 

5: MOE oral = intermediate-term incidental oral NOAEL (2.36 mg/kg/day
)/hand-to-mouth residential exposure.

6: Aggregate MOE (food + water + residential) =

__________________1__________________

1/MOE f+w +  1/MOEI  +  1/MOED +  1/MOEO

7.3  Chronic Aggregate Risk Assessment

The dietary exposure pathway (food and drinking water) is the only
source of chronic exposure to cyfluthrin (i.e., 180 consecutive days or
more).  Therefore, the long-term aggregate exposure and risk estimates
are equivalent to the chronic dietary exposure and risk estimates
discussed in Section 5.2.2 above.  The chronic aggregate risks for
cyfluthrin are less than 100% of the cPAD for all population subgroups,
and therefore, do not pose a risk concern for HED.

7.4  Cancer Aggregate Risk Assessment

Based upon HED’s cancer classification of cyfluthrin and consequently
the lack of hazard to warrant a cancer dietary risk assessment, a cancer
aggregate risk assessment was not conducted. 

8.0  Cumulative Risk Characterization/Assessment

Cyfluthrin and beta-cyfluthrin are members of the pyrethroid class of
pesticides.  Although all pyrethroids alter nerve function by modifying
the normal biochemistry and physiology of nerve membrane sodium
channels, EPA is not currently following a cumulative risk approach
based on a common mechanism of toxicity for the pyrethroids.  Although
all pyrethroids interact with sodium channels, there are multiple types
of sodium channels and it is currently unknown whether the pyrethroids
have similar effects on all channels.  The Agency does not have a clear
understanding of effects on key downstream neuronal function e.g., nerve
excitability, nor do we understand how these key events interact to
produce their compound specific patterns of neurotoxicity.  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 the results of
the research become available, the Agency will consider the findings and
make a determination of common mechanism as a basis for assessing
cumulative risk.  Information regarding EPA’s procedures for
cumulating effects from substances found to have a common mechanism can
be found on EPA’s website at   HYPERLINK
"http://www.epa.gov/pesticides/cumulative/" 
http://www.epa.gov/pesticides/cumulative/ .

9.0  Occupational Exposure/Risk Pathway

A full analysis of the occupational exposure and risks associated with
the proposed uses of cyfluthrin/beta-cyfluthrin can be found in the HED
memorandum, Cyfluthrin and Beta-cyfluthrin: Occupational Risk Assessment
to Support the Uses o Alfalfa and Grasses and the Use of Beta-Cyfluthrin
on Sugar Beet, (September 7, 2007; D339445).

.e., MOE ≥ 100).  When estimating risk to workers who reenter treated
areas, HED considers the post-application activities for a given crop,
and the expected exposure from each activity to estimate risk.  For
handlers as well as workers who reenter fields treated with
cyfluthrin/beta-cyfluthrin, HED’s level of concern (LOC) is 100.  

Application methods associated with the proposed uses on alfalfa and
grasses include aerial/aerial ULV (by fixed wing or by helicopter), and
groundboom/chemigation (sprinkler irrigation system only).  Application
for commercial seed treatment is with a slurry or liquid with a slurry
treater or a direct treater.  Commercial seed treatment also involves
individuals who bag the treated seed and/or sew the bag shut.  Table 12
lists the occupational exposures associated with each petition.



Table 12.  Summary of Petitions and Occupational Assessments for
Cyfluthrin/Beta-cyfluthrin

Petition Description	Petition No.	Occupational Exposures Assessed

Petition for use of cyfluthrin/beta-cyfluthrin on grasses throughout the
U.S. including mixed stands with alfalfa	6E7058	Exposure to handlers
(mixers, loaders, applicators, flaggers)

Exposure to post application workers



Petition for new use as sugar beet seed treatment	6F7160	Exposure to
loader, and seed treater;

Exposure to the bagger of treated seeds

Exposure to the sewer of bags filled with treated seed

Exposure to post treatment workers (planters)

Petition for increased number of applications to alfalfa (increased
seasonal application rate)	7F7226	Exposure to handlers (mixers, loaders,
applicators, flaggers)

Exposure to post application workers

Request to amend labels to include Crop Group 15 (except rice) and Crop
Group 16	7F7200	No occupational exposure assessments associated with
this petition.



9.1  Occupational/Non-Residential Toxicological Profile for
Cyfluthrin/Beta-cyfluthrin

The cyfluthrin risk assessment team has re-evaluated the cyfluthrin
toxicological database and believes it continues to be sufficient to
assess the occupational risks associated with the subject petitions. 
The cyfluthrin risk assessment team remains in agreement with the
previous conclusions drawn by HED regarding the hazard of cyfluthrin.  A
full characterization of the hazard of cyfluthrin and beta-cyfluthrin
can be found in the HED memorandum Cyfluthrin and Beta-cyfluthrin –
3rd Report of the Hazard Identification Assessment Review Committee (P.
Hurley, TXR 0050768, 05/21/2002).  Based upon the proposed uses and
information regarding the production of grasses, sugar beet seed
treatment, and alfalfa production, HED has determined that exposure
duration for occupational handlers and applicators is short-term (1 –
30 days), and intermediate-term (1 – 6 months).  Therefore, both the
short-term and intermediate-term toxicity endpoints were applied in this
cyfluthrin/beta-cyfluthrin occupational assessment.  Table 13 summarizes
the toxicological endpoints for assessing occupational/non-residential
risks from cyfluthrin/beta-cyfluthrin.  



Table 13.  Summary of Toxicological Doses and Endpoints for Cyfluthrin
and Beta-Cyfluthrin for Use in Occupational Human Health Risk
Assessments.

Exposure/

Scenario	Point of Departure	Uncertainty Factors	Level of Concern for
Risk Assessment	Study and Toxicological Effects

Dermal 

Short- (1-30 Days) and Intermediate- Term (1 - 6 Months)	NOAEL= 2.36
mg/kg/day

Dermal absorption rate =  5%	UFA= 10x

UFH = 10x	Occupational LOC for MOE = 100	90-Day dog feeding study
(beta-cyfluthrin)

LOAEL = 13.9/15.4 mg/kg/day (M/F) based on gait abnormalities, increased
incidence of vomiting, and suggestive decreased body weight gain.

Dermal 

Long-Term (>6 Months)	NOAEL= 2.4 mg/kg/day

Dermal absorption rate =  5%	UFA= 10x

UFH = 10x	Occupational LOC for MOE = 100	Chronic toxicity in dogs
(cyfluthrin)

LOAEL = 10.64 mg/kg/day based on   clinical signs, gait abnormalities,
and abnormal postural reactions.

Inhalation

Short-Term 

(1-30 Days)	NOAEL= 0.00026 mg/L 

(0.07 mg/kg/day)	UFA= 10x

UFH = 10x	Occupational LOC for MOE = 100	28-Day rat inhalation study
(beta-cyfluthrin)

LOAEL = 0.0027 mg/L (0.73 mg/kg/day) based on decreases in body weight
in both sexes and decreased urinary pH in males.

Inhalation

Intermediate- (1-6 months) and Long-Term (>6 months)	NOAEL= 0.00009 mg/L


(0.02 mg/kg/day)	UFA= 10x

UFH = 10x

	Occupational LOC for MOE = 100	13-Week rat inhalation study
(cyfluthrin) 

LOAEL = 0.00071 mg/L (0.16 mg/kg/day) based on decreases in body weight
and body weight gain in males and clinical signs in females.

Cancer (oral, dermal, inhalation)	Classification:  “Not likely to be
Carcinogenic to Humans”

Point of Departure (POD) = A data point or an estimated point that is
derived from observed dose-response data and  used to mark the beginning
of extrapolation to determine risk associated with lower environmentally
relevant human exposures.  NOAEL = no observed adverse effect level. 
LOAEL = lowest observed adverse effect level.  UF = uncertainty factor. 
UFA = extrapolation from animal to human (interspecies).  UFH =
potential variation in sensitivity among members of the human population
(intraspecies).  MOE = margin of exposure.  LOC = level of concern.  N/A
= not applicable.

9.2  Occupational/Non-Residential Exposure Inputs

No chemical specific exposure data were submitted with the subject
petition for grasses, or with the petition for the increased number of
applications to alfalfa.  Therefore, when estimating exposure from the
proposed uses on grasses, and increased rate for alfalfa, HED used
surrogate data from the Pesticide Handlers Exposure Data Base (PHED)
Version 1.1, and standard assessment variables established by the Health
Effects Division Science Advisory Council for Exposure.

With regard to the subject petition for new use on sugar beet seed, no
chemical specific data were submitted with this petition either. 
However, the petitioner did submit an occupational risk assessment
summary (MRID 47007811) with the subject petition for sugar beet seed
treatment.  A data evaluation record for this MRID was not prepared
because it did not contain any original field data.  Table 14 identifies
the specific occupational exposure scenario combinations, including the
worker population, the product formulation and equipment variations.

Table 14.

Short- and Intermediate-term Occupational Exposure Scenarios Applicable
for the Proposed Uses of Cyfluthrin and beta-Cyfluthrin on Alfalfa and
Grasses.

No.	Exposure Scenario	Active Ingredient

Mixing/Loading

1	liquid, open mixing/loading for aerial, fixed wing and rotary
equipment	Cyfluthrin

2	liquid, open mixing/loading for ground boom equipment	Cyfluthrin

3	liquid, open mixing/loading for chemigation	Cyfluthrin

4	WP/WSB, open mixing/loading for aerial equipment 	Cyfluthrin

5	WP/WSB, open mixing/loading for ground boom equipment	Cyfluthrin

6	WP/WSB, open mixing/loading for chemigation	Cyfluthrin

7	liquid, open mixing/loading for aerial equipment	beta-Cyfluthrin

8	liquid, open mixing/loading for ground boom equipment	beta-Cyfluthrin

9	liquid, open mixing/loading for chemigation	beta-Cyfluthrin

Applying/Flagging

10	liquid and WP, applying by aerial fixed wing equipment, enclosed cab 
Cyfluthrin

11	liquid and WP, applying by aerial rotary equipment, enclosed cab 
Cyfluthrin

12	liquid and WP, applying by ground boom equipment, open cab	Cyfluthrin

13	liquid and WP, flagging, aerial applications	Cyfluthrin

14	liquid, applying by aerial fixed wing equipment, enclosed cab 
beta-Cyfluthrin

15	liquid, applying by aerial rotary equipment, enclosed cab 
beta-Cyfluthrin

16	liquid, applying by ground boom equipment, open cab	beta-Cyfluthrin

17	liquid, flagging, aerial application 	beta-Cyfluthrin 

1: scenario numbers listed in Table 14 correspond with scenario numbers
found in Table 1, and Table 2 in Appendix A.

9.3  Handler and Applicator Risks from Proposed Uses on Grasses and
Alfalfa

The proposed labels for grasses and alfalfa specify baseline PPE
(long-sleeved shirt and long pants, socks, and shoes), chemical
resistant gloves, and protective eye-wear for handlers; and, specify a
restricted entry interval of (REI) of 12-hours.  Dermal and inhalation
exposures can be combined for short and intermediate-term scenarios
respectively, due to the common endpoints between these exposure routes.


Estimated risk to handlers of wettable powder/water soluble bag
formulation, when using either aerial, ground boom, or chemigation
equipment are not a risk concern to HED when baseline PPE is assumed. 
Estimated risk to handlers of liquid formulations, when using ground
boom equipment, are not a risk concern to HED when baseline PPE is
assumed.  However, risks associated with liquid formulations when using
either aerial or chemigation equipment are a concern to HED when only
baseline PPE is assumed.  However, when HED assumes baseline PPE,
chemical resistant gloves, and a dust/mist respirator, risks were not of
concern.  As can be seen in Table 15, five of six handler exposure
scenarios involving liquid formulations require a dust/mist respirator,
(which is not indicated on the petition labels), to reach a MOE ≥ 100.
 Addition of a dust/mist respirator was required to bring
intermediate-term inhalation exposure risks above HED’s LOC of 100.

Regarding applicators and flaggers for the proposed use on grasses and
on alfalfa, the short-term and intermediate-term risks are not a concern
to HED when liquid or wettable powder formulations are applied via
aerial, groundboom, or chemigation equipment when baseline PPE is
assumed.  HED notes that the proposed use directions for grasses and
alfalfa require gloves which will provide additional protection to
applicators and flaggers.  Conclusions of handler and applicator risks
and required PPE are presented in Table 15.  Appendix A contains
expanded tables of handler and applicator exposure and risk.

Table 15. 

Summary of PPE Where MOE ≥ 100

Operation	Active Ingredient	Product Formulation	Application Method	PPE
Required to Reach MOE≥ 100



Handlers	Cyfluthrin	Liquid

	Aerial	PPE stated on proposed label + dust/mist respirator



	Ground boom	PPE stated on proposed label + dust/mist respirator



	Chemigation	PPE stated on proposed label + dust/mist respirator



WP/WSB

	Aerial	PPE stated on proposed label



	Chemigation	PPE stated on proposed label



	Ground boom	PPE stated on proposed label

	Beta-cyfluthrin	Liquid	Aerial	PPE stated on proposed label + dust/mist
respirator



	Ground boom	PPE stated on proposed label



	Chemigation	PPE stated on proposed label + dust/mist respirator



Applicators	

Cyfluthrin

and

Beta-cyfluthrin

	All formulations	All application methods	PPE stated on proposed label



9.4  Short-term and Intermediate-term Exposures and Risk from Proposed
Seed Treatment Use

The proposed use pattern for sugar beet seed treatment indicates that
during the seed treatment season, workers may be treating several
batches of seeds per day for several weeks resulting in both short-term
(1-30 days) and intermediate-term (1-6 months) exposure durations. 
Dermal and inhalation exposures can be combined for short and
intermediate-term scenarios respectively, due to the common endpoints
between these exposure routes. 

The Poncho Beta® label specifies the following PPE: (i)
loaders/treaters must wear long sleeved shirt and long pants, shoes with
socks, chemical resistant gloves, and dust/mist respirator, (ii) baggers
and sewers must wear long sleeved shirt and long pants, shoes with
socks, and a dust/mist respirator.  HED assessed the risk to loaders, to
baggers, and to sewers separately (i.e., an individual who only loads,
or only bags, or only sews), and also assessed risks to an individual
who would perform all three tasks involved in seed treatment.



Risks to Individuals Performing One Discrete Task

Short-term MOEs for all three operations do not represent a risk concern
to HED.

Intermediate-term MOEs to baggers and sewers do not represent a risk
concern to HED.

Intermediate-term MOE to loader/treaters does represent a risk concern
to HED (MOE = 81).

Risks to Individuals Performing All Three Discrete Tasks

Short-term and intermediate-term MOEs for individuals who perform all
three tasks represent a risk concern to HED, (short-term MOE = 58,
intermediate-term MOE = 19).

HED notes that the estimated risks to an “multiple operator” may be
an overestimation because HED does not have data that accurately
represents exposures from a single-person operation (including
representative equipment, and/or the amount of seed that can be treated
by a single person).  Additional information regarding seed treatment
run by a single person would be necessary to better estimate exposure
and risk from this scenario.  However, in the absence of more specific
data, HED must rely on the data in hand which indicates that the risk to
a multiple operator is a concern to HED.  Conclusions of seed treatment
risks and required PPE are presented in Table 16.

Table 16.  Seed Treatment Operations for Proposed Use on Sugar beet
Seed:

PPE Where MOE ≥ 100

 Operation	PPE Required to Reach MOE≥ 100

Loading, treating	

Intermediate-term MOE = 81 and represents a risk concern to HED

Assumes PPE stated on the proposed label



Bagging	PPE stated on the proposed label



Sewing	PPE stated on the proposed label



Multiple operations	

Risks are above HED’s level of concern

Short-term  MOE = 58

Intermediate-term  MOE =  19

Assumes PPE stated on the proposed label + chemical resistant gloves





9.5  Post-application Exposure and Risk 

 not of concern (MOEs ≥ 100).  

Post-application exposure from the proposed seed treatment use is likely
when workers (planters) transfer the treated seeds from bags to
planter-hoppers and/or while planting/drilling the seed.  The estimated
post-application exposures and risks (short- and intermediate-term) to
planters of Poncho Beta® treated sugar beet seed are not of concern. 
While no PPE is required for planters while seeding/planting, HED does
not anticipate direct contact with treated seed since the planting
machinery places/drills the seed and covers it in one operation. 
Treated seeds once covered with soil are protective of workers who may
reenter the field soon after planting for irrigation.  No other
post-application activity is performed in a freshly seeded sugar beet
field.  There is no restricted entry interval (REI) for the treating and
planting of pre-treated seeds.

10.0  Data Needs and Label Recommendations

No data gaps were identified in the process of conducting the above
analysis for the subject petitions.  Based upon HED’s analysis, the
following label amendments are recommended to the proposed
cyfluthrin/beta-cyfluthrin labels submitted in connection with the
subject petitions.

Directions for Use:

Proposed labels for use on grasses and alfalfa must be amended to
exclude ultra-low volume aerial application (using a minimum of 1 qt./A
of vegetable oil).  No data were submitted to support this type of
application, and therefore, should be removed from the proposed label.

Occupational Personal Protective Equipment:

Addition of dust/mist respirators as a PPE requirement for all liquid
formulations of Baythroid® 2, Renounce® 20WP, and Baythroid® XL.

The intermediate-term MOE for loaders involved in the sugar beet seed
treatment process is of concern to HED (intermediate-term MOE for
loader/treater = 81), additional PPE may be warranted for this scenario
(such as double layer clothing, or a respirator with protection factor
of 10).  As earlier, additional risk considerations regarding sugar beet
seed treatment with Poncho Beta®, are also being addressed through a
separate HED document (D340131).  Together, this document and D340131
address the occupational risks associated with the proposed use of
Poncho Beta® on sugar beet seed.  Therefore, HED recommends the
Registration Division consider the occupational risks associated with
the proposed use of Poncho Beta® in light of the exposures and risks
from both beta-cyfluthrin and clothianidin prior to granting the
proposed use and/or tolerances associated with the proposed sugar beet
seed treatment use (sugar beet roots, and sugar beet dried pulp).



New Uses:

Pending amendments and changes HED has suggested to the proposed
Baythroid® 2, Renounce® 20WP, and Baythroid® XL labels, HED
recommends the registration of new uses and establishment of tolerances
for cyfluthrin/beta-cyfluthrin. 

Revised Tolerances for Cyfluthrin:

HED recommends that the establishment of tolerances incorporates the
correct commodity definitions for cyfluthrin (and beta-cyfluthrin)
treated commodities as stated in Appendix C, Table 1 and in the Summary
of Recommendations.

Revised Section F:

A revised Section F is required reflecting HED recommendations, and for
the establishment of (separate) tolerances listed below for both
cyfluthrin and beta-cyfluthrin.  The cyfluthrin tolerances should be
included in 40 CFR §180.436(a)(1), while a separate section under
180.436 should be established for tolerances for beta-cyfluthrin,
analogous to the tolerances for lambda-cyhalothrin and gamma-cyhalothrin
in §180.438.  The section for beta-cyfluthrin needs to be established
because registrations for cyfluthrin on these commodities might be
cancelled at some point in the future.  The tolerances for cyfluthrin
and beta-cyfluthrin should be established at the same levels.  The
recommended wording for the beta-cyfluthrin tolerance expression is as
follows: “Tolerances are established for residues of the insecticide
beta-cyfluthrin [mixture comprising the enantiomeric pair
(R)-α-cyano-4-fluoro-3-phenoxybenzyl
(1S,3S)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate and
(S)-α-cyano-4-fluoro-3-phenoxybenzyl
(1R,3R)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate with
the enantiomeric pair (R)-α-cyano-4-fluoro-3-phenoxybenzyl
(1S,3R)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate and
(S)-α-cyano-4-fluoro-3-phenoxybenzyl
(1R,3S)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate] in or
on the following commodities:”

HED also recommends that, at some point in the future, tolerances be
established for all food uses of beta-cyfluthrin (i.e., on those
commodities not included in the present actions) under the new section
to be created under 40 CFR §180.436.



References

Cyfluthrin and Beta-Cyfluthrin: Occupational Risk Assessment to Support
the Uses on Alfalfa and Grasses and the Use of Beta-Cyfluthrin on Sugar
Beet.  Petition Nos. 6E7058 (Grasses), 6F7160 (Sugar Beet), and 7F7226
(Alfalfa). Sep. 28, 2007; S.Oonnithan; D339445.

Tier I Drinking Water Assessment for the Registration for the New Uses
of Cyfluthrin and Beta-cyfluthrin on Alfalfa (Increased Application
Rate, Section 3), Grasses (Pasture, Rangeland, Grass for Seed, Grass for
Hay, Grass in Mixed Stands with Alfalfa, IR-4 Tolerance Petition),
Cereals Crop Group 15 (Beta-cyfluthrin), Cereals Crop Group 16 except
rice (Beta-cyfluthrin), and  sugar beets (Beta-cyfluthrin).  Sep. 24,
2007; J.L. Meléndez; D331952, and D340739.

Cyfluthrin and Beta-Cyfluthrin  Acute Probabilistic and Chronic Dietary
Exposure Assessments for the Section 3 Registration Actions. 
10/15/2007;  D.Dotson; D339414.

Cyfluthrin and beta-Cyfluthrin.  Registration for Uses on Grasses,
Alfalfa, and Seed Treatment Use on Sugar Beets.  Request for Replacement
of Individual Cereal Grain Tolerances with Crop Group Tolerance for
Cereal Grains (Except Rice), Crop Group 15, and Replacement of
Individual Tolerances on Forage and Stover/Straw of Wheat, Corn, and
Sorghum with Crop Group Tolerance for Forage, Fodder, and Straw of
Cereal Grains, Crop Group 16 (Except Rice).  Summary of Analytical
Chemistry and Residue Data.  10/15/2007; D.Dotson; D339413.

Beta-Cyfluthrin: Developmental Neurotoxicity Study in Rats.  September
6, 2007; A.Levy; D293830.

Cyfluthrin:  Occupational and Residential Exposure Assessment (Section
3) for the Registration of Brassica Vegetables, Garbanzo Beans, Head
Lettuce, Peas, Soybeans, Corn and Stored Grain.  July 31, 2002;
S.Tadayon; D283388.

PP# 2F6445, 2F6479, 1F6290, 1E6318, 3E6583, and 3D6776.  FQPA Human
Health Risk Assessment for Cyfluthrin – Proposal for Tolerances of
Residues in/on numerous vegetable crops, fruit crops, tree nuts,
peanuts, wheat, grass, and dried peas and beans.  07/15/05; Y.Donovan;
D290925.

Cyfluthrin and Beta-Cyfluthrin – Report of the Hazard Identification
Assessment Review Committee.  April 11, 2001; P.Hurley; HED Doc. No.
014535.Appendix A.  Occupational Exposure and Risk Tables

Table 6.  Short- and Intermediate-term Occupational Risks to
Mixers/Loaders From the Use of Cyfluthrin and beta-Cyfluthrin on Alfalfa
and Grasses 

Chemical	Mixing/Loading Exposure                                
Scenario  #	

PPE 1	Dermal Unit Exposure         (mg/lb ai)	Inhalation Unit Exposure  
(µg/lb ai)	Dermal Dose                     (mg/kg/day) 2	Inhal. Dose  
(mg/kg/day) 3 	Total        Short-term          MOE 4	Total     
Interm.- term           MOE 4

Cyfluthrin	1. Liquid, Open, Aerial	BL	2.9	1.2	0.109371	0.000905	17	11

"         "	1a.    "	 "	BL+G+R	0.023	0.24*	0.000867	0.000181	340	110

"         "	2. Liquid, Open,        Ground boom 	BL	2.9	1.2	0.018229
0.000151	100	66

"         "	2a.    "	 "	BL+G+R	2.9	0.24*	0.018229	0.000030	120	110

"         "	3. Liquid, Open, Chemigation	BL	2.9	1.2	0.031900	0.000264	58
37

"         "	3a.    "	 "	BL+G+R	0.023	0.24*	0.000253	0.000053	1,200	360

"         "	4. WP/WSB, Open, Aerial 	BL	0.021	0.24	0.000792	0.000181	340
110

"         "	5. WP/WSB, Open,   Ground boom	BL	0.021	0.24	0.000132
0.000030	2,100	640

"         "	6. WP/WSB, Open, Chemigation 	BL	0.021	0.24	0.000231
0.000053	1,200	370

Beta-cyfluthrin	7. Liquid, Open, Aerial	BL	2.9	1.2	0.054686	0.000453	34
22

"         "	7a.    "	 "	BL+G+R	0.023	0.24*	0.000434	0.000091	680	210

"         "	8. Liquid, Open,           Ground  boom 	BL	2.9	1.2	0.009114
0.000075	200	130

"         "	9. Liquid, Open, Chemigation	BL	2.9	1.2	0.015950	0.000132
120	75

"         "	9a.    "	 "	BL+G+R	2.9	0.24*	0.015950	0.000026	140	120

1.  BL = baseline PPE (long-sleeve shirt, long pants, shoes with socks,
and no respirator), G = Gloves, R = dust-mist respirator.

2.  Dermal dose/day = (app. rate)(area treated/day)(dermal unit
exposure)(dermal absorption factor)(conversion factor [0.01]) ÷ body
weight

3.  Inhalation dose/day = (app. rate)(area treated/day)(inhalation unit
exposure)(conversion factor [0.01]) ÷ body weight

4.  Total Short-term or Total Intermediate-term MOE: 1 ÷ 1/dermal MOE +
1/ inhalation MOE 

*.  Applied an 80% reduction factor to the inhalation unit exposures for
the use of dust/mist respirator as a mitigation measure. Ref: Exposure
mitigating Table (PHED).  



Table 7.  Short- and Intermediate-term Occupational Risks to Applicators
From the Use of Cyfluthrin and beta-Cyfluthrin on Alfalfa and Grasses  

Chemical	Mixing/Loading Exposure                                
Scenario  #	

PPE 1	Dermal  Unit Exposure (mg/lb ai)	Inhalation Unit Exp.  (µg/lb ai)
Dermal Dose                     (mg/kg/day) 2	Inhal. Dose   (mg/kg/day)
3 	Total        Short-term          MOE 4	Total      Interm.- term      
    MOE 4

Cyfluthrin	10. Liquid & WP, Aerial, Fixed wing, Enclosed cab	BL	0.005
0.068	0.000189	0.000051	1,200	380

"         "	11. Liquid & WP, Aerial, Rotary, Enclosed cab	BL	0.0019
0.0018	0.000072	0.0000014	20,000	10,000

"         "	12. Liquid & WP, Gr. boom,  Open cab	BL	0.014	0.74	0.000088
0.000093	730	210

"         "	13. Liquid & WP, Aerial, Flagger	BL	0.011	0.35	0.000121
0.000077	870	260

Beta-cyfluthrin	14. Liquid & WP, Aerial, Fixed Wing, Enclosed cab	BL
0.005	0.068	0.000094	0.000026	2,500	760

"         "	15. Liquid & WP, Aerial, Rotary, Enclosed cab	BL	0.0019
0.0018	0.000036	0.000001	40,000	20,000

"         "	16. Liquid & WP, Gr. boom,  Open cab	BL	0.014	0.74	0.000044
0.000047	1,500	430

"         "	17. Liquid & WP, Aerial, Flagger	BL	0.011	0.35	0.000061
0.000039	1,700	510

1.  BL = baseline PPE, G = Gloves, R = dust/mist respirator; baseline
PPE consists of long-sleeve shirt, long pants, shoes with socks and no
respirator. 

2.  Dermal dose/day = (app. rate)(area treated/day)(dermal unit
exposure)(dermal absorption factor)(conversion factor [0.01]) ÷ body
weight

3.  Inhalation dose/day = (app. rate)(area treated/day)(inhalation unit
exposure)(conversion factor [0.01]) ÷ body weight

4.  Total Short-term or Total Intermediate-term MOE: 1 ÷ 1/dermal MOE +
1/ inhalation MOE



Table 10. Short-and Intermediate-Term Postapplication Risks to Workers
Who Enter Alfalfa and Grass Fields Treated with Cyfluthrin and
beta-Cyfluthrin.  



Crops 1	Chemical	Max. Single Appl. Rate (lb ai/A)	DFR µg/cm2	Transfer
Coefficient 3	Dermal Dose  (mg/kg/day) 4	Short & Inter.-term MOE 5

Alfalfa and Grass grown for seed 	cyfluthrin	0.044	0.099	1500 scouting 
0.00085	2,800

	beta-cyfluthrin	0.022	0.049	1500 scouting 	0.00042	5,600

1.  Among the grass crop sites (pasture, rangeland, grasses grown for
hay and seed, grass mixed-stands with alfalfa), grass grown for seed is
expected to have the maximum postapplication activities.

2.  DFR :

(app. rate)(fraction of ai retained on foliage [20%])(fraction of
residue that dissipates daily [10%])(conversion factor [4.54
E+8][2.47E-8])

3. Transfer coefficient (TC) is for alfalfa (surrogate crop) with medium
exposure potential.

4. Dermal Dose: (dislodgeable foliar residue on designated
day)(conversion factor [10E-3])(transfer coefficient)(dermal absorption
factor)(exposure time [8 hrs]) ÷ body weight

5. Dermal MOE: NOAEL/dermal dose

Table 9.  Short- and Intermediate-Term Risks to Seed Treatment Workers
and Planters From the Use of beta-Cyfluthrin Containing Poncho Beta on
Sugar 	  Beet. 1

Exposure

Scenarios	Worker   

Type	

PPE 2	Qty Treated / Planted/day      (lbs)	Unit Exp. Dermal/day

(mg/lb ai)	Unit Exp. Inhal./day

(µg/lb ai)	Dermal 

Dose/day

(mg/kg) 3 	Inhalation

Dose/day 

(mg/kg) 4	Total        Short-term          MOE 5	Total      Interm.-
term           MOE 5

Loading/Treating	L/T	S, G	52,000	0.023	0.34	0.00365	0.00108	59	18

Loading/Treating	L/T	S, G, R	52,000	0.023	0.068 *	0.00365	0.00022	220	81

Bagging, treated seed	Bagger	S	52,000	0.0091	0.16	0.00144	0.00051	130	38

Bagging, treated seed	Bagger	S, R	52,000	0.0091	0.032 *	0.00144	0.00010
490	180

Sewing, bagged seed	Sewer	S	52,000	0.0062	0.23	0.00098	0.00073	92	27

Sewing, bagged seed	Sewer	S, R	52,000	0.0062	0.046 *	0.00098	0.00015	400
130

Doing multiple jobs	Multiple	S, G	52,000	0.0420	1.6	0.00666	0.00508	13	4

Doing multiple jobs	Multiple	S, G, R	52,000	0.0420	0.32 *	0.00666
0.00102	58	19

Handling/ Planting 6 	Farmer, Postappl.	S, #	640	0.25	3.4	0.00049
0.00013	470	150

2.  S = Single layer (long sleeve shirt and long pants) and no gloves, G
= chemical resistant gloves, R = dust/mist respirator  

3.  Dermal dose = (app. rate)(area treated/day)(dermal unit
exposure)(dermal absorption factor)(conversion factor [0.01]) ÷ body
weight

4.  Inhalation dose = (app. rate)(area treated/day)(inhalation unit
exposure)(conversion factor [0.01]) ÷ body weight

5.  Total Short-term or Total Intermediate-term MOE: 1 ÷ 1/dermal MOE +
1/ inhalation MOE

6.  Postapplication exposure.

* Applied an 80% reduction factor to the inhalation unit exposure for
the use of dust/mist respirator, which is a PPE requirement on the label
for all seed treatment workers. Ref: Exposure Mitigating Table (PHED).

#.  For handlers/planters, label specifies gloves for loading only.

Appendix B.  Toxicology Profile of Cyfluthrin and Beta-cyfluthrin

The requirements (40 CFR 158.340) for food uses for beta-cyfluthrin are
in Table 1.  Use of the new guideline numbers does not imply that the
new (1998) guideline protocols were used.

Appendix B, Table 1

Toxicology Data Requirements – cyfluthrin/beta-cyfluthrin

Test 

	Technical

	Required	Satisfied

870.1100    Acute Oral Toxicity	

870.1200    Acute Dermal Toxicity	

870.1300    Acute Inhalation Toxicity	

870.2400    Primary Eye Irritation	

870.2500    Primary Dermal Irritation	

870.2600    Dermal Sensitization		yes

yes

yes

yes

yes

yes	yes

yes

yes

yes

yes

yes

870.3100    Oral Subchronic (rodent)	

870.3150    Oral Subchronic (nonrodent)	

870.3200    21-Day Dermal	

870.3250    90-Day Dermal	

870.3465    90-Day Inhalation		yes

yes

yes

no

no	yes

yes

yes

-

yes

870.3700a  Developmental Toxicity (rodent)	

870.3700b  Developmental Toxicity (nonrodent)	

870.3800    Reproduction		yes

yes

yes	yes

yes

yes

870.4100a  Chronic Toxicity (rodent)	

870.4100b  Chronic Toxicity (nonrodent)	

870.4200a  Oncogenicity (rat)	

870.4200b  Oncogenicity (mouse)	

870.4300    Chronic/Oncogenicity		yes

yes

yes

yes

yes	yes1

yes

yes

yes

yes

870.5100    Mutagenicity—Gene Mutation - bacterial	

870.5300    Mutagenicity—Gene Mutation - mammalian	

870.5375    Mutagenicity—Structural Chromosomal Aberrations	

870.5550   Mutagenicity—Other Genotoxic Effects		yes

yes

yes

yes	yes

yes

yes

yes

870.6100a  Acute Delayed Neurotox. (hen)	

870.6100b  90-Day Neurotoxicity (hen)	

870.6200a  Acute Neurotox. Screening Battery (rat)	

870.6200b  90-Day Neurotox. Screening Battery (rat)	

870.6300    Developmental Neurotoxicity		yes

no

yes

yes

yes	yes

-

yes

yes

yes

870.7485    General Metabolism	

870.7600    Dermal Penetration		yes

no	yes

-

1  Satisfied with combined chronic toxicity/carcinogenicity study

Appendix B  Toxicology Profile of Cyfluthrin and Beta-cyfluthrin

Appendix B, Table 2

Acute Toxicity Profile – Cyfluthrin

Guideline No.	Study Type	MRID(s)	Results	Toxicity Category

870.1100	Acute oral – rat	00131499

00131518	In cremophor

g/kg (♂)

In acetone

LD50 = 254 mg/kg (♂)

In N-methyl pyrollidone

LD50 = 500 -1000 mg/kg (♂)	I

II

III

870.1200	Acute dermal – rat	00131499

00131518	In cremophor

LD50 > 5000 mg/kg (♂+♀)

In 0.9% NaCl

LD50 > 5000 mg/kg (♂+♀)

Undiluted

LD50 > 5000 mg/kg (♂+♀)	IV

870.1300	Acute inhalation – rat	00131509	Aqueous cremophor 

LC50 > 0.735 mg/L (♂)

LC50 = 0.468 mg/L (♀)

DMSO/polyethylene glycol LC50 = 0.575 mg/L (♂)

LC50 = 0.490 mg/L (♀)	II

870.2400	Acute eye irritation – rabbit	00131499	No corneal opacity;
transient irritation for 3 days	III

870.2500	Acute dermal irritation – rabbit	00131499	

Non-irritating.  Primary irritation score = 0	IV

870.2600	Skin sensitization – guinea pig	00131512

00131513	Not a sensitizer (Draize test)

Not a sensitizer

(Maximization test)	N/A



Appendix B  Toxicology Profile of Cyfluthrin and Beta-cyfluthrin

Appendix B, Table 3

Acute Toxicity Profile – Beta-Cyfluthrin

Guideline No.	Study Type	MRID(s)	Results	Toxicity Category

870.1100	Acute oral – rat	41244101	In xylene

Fasted:

LD50 = 211 mg/kg (♂)

LD50 = 336 mg/kg (♀)

Fed:

LD50 = 307 mg/kg (♂)

LD50 = 343 mg/kg (♀)	II

870.1100	Acute oral – rat	41244102	In PEG 400

Fasted:

LD50 = 380 mg/kg (♂)

LD50 = 651 mg/kg (♀)

Fed:

LD50 = 655 mg/kg (♂)

LD50 = 1369 mg/kg (♀)	II (♂)

III (♀)

870.1100	Acute oral – rat	41244104	In acetone/peanut oil

Fasted:

LD50 = 84 mg/kg (♂)

LD50 = 77 mg/kg (♀)

Fed:

LD50 = 141 mg/kg (♂)

LD50 = 108 mg/kg (♀)	II

870.1100	Acute oral – mouse	41244103	In PEG 400

Fasted:

LD50 = 91 mg/kg (♂)

LD50 = 165 mg/kg (♀)	II

870.1200	Acute dermal – rat	41244105	In xylene

LD50 > 5000 mg/kg (♂)

LD50 > 5000 mg/kg (♀)	IV

870.1200	Acute dermal – rat	41244106	In PEG 400

LD50 > 5000 mg/kg (♂)

LD50 > 5000 mg/kg (♀)	IV

870.1300	Acute inhalation – rat	41205701	Aerosol

LC50 = 0.081-0.082 mg/L (♂+♀)

Dust

LC50 = 0.532 mg/L (♂+♀)	II

III

870.2400	Acute eye irritation – rabbit	41205702	Slight ocular irritant
III

870.2500	Acute dermal irritation – rabbit	41205702	Very slight dermal
irritant  	IV

870.2600	Skin sensitization – guinea pig	43611601	Not a sensitizer;
however, positive control data not available	N/A

Appendix B  Toxicology Profile of Cyfluthrin and Beta-cyfluthrin

Appendix B, Table 4

Subchronic, Chronic and Other Toxicity Profile – Cyfluthrin and
Beta-Cyfluthrin

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

870.3100

	90-Day oral toxicity (rat)

Beta-cyfluthrin (99.7% a.i.)	41244108 (1986)

Acceptable/guideline 

M:  0, 2.3, 9.5, 18.9 mg/kg/day

F:  0, 2.5, 10.9, 42.4 mg/kg/day

M:  0, 37.0 mg/kg/day

F:  0, 43.0 mg/kg/day	NOAEL = 9.5/10.9 mg/kg/day (M/F)

LOAEL = 37.0/43.0 mg/kg/day (M/F) based on gait abnormalities, necrosis
in head and neck region, mortality (2), decreased body weight gain.

870.3100

	90-Day oral toxicity (rat)

Cyfluthrin (84.2% a.i.)	00131524 (1980)

Unacceptable/guideline

M:  0, 2.2, 7.4, 22.3 mg/kg/day

F:  0, 2.7, 8.8, 28.0 mg/kg/day	NOAEL = 22.3/28.0 mg/kg/day (M/F)

LOAEL = not observed

870.3150

	90-Day oral toxicity (dog)

Beta-cyfluthrin (99% a.i.)	41267801 (1987)

Acceptable/guideline

M:  0, 0.39, 2.36, 13.9 mg/kg/day

F:  0, 0.39, 2.5, 15.4 mg/kg/day	NOAEL = 2.36/2.5 mg/kg/day (M/F)

♂) or 17 applications within 22 days (♀)	Dermal NOAEL = 113
mg/kg/day

Dermal LOAEL = 376 mg/kg/day based on gross and histological skin
lesions.  

Systemic NOAEL = 376 mg/kg/day

Systemic LOAEL = 1077 mg/kg/day based on decreased food consumption, red
nasal discharge and urine staining. 

Non-guideline	28-Day oral toxicity (rat)

Cyfluthrin	00131525 (1983)

Supplementary

0, 5, 15, 50 mg/kg/day	NOAEL = 15 mg/kg/day

LOAEL = 50 mg/kg/day based on gait abnormalities, salivation,
nervousness, decrease in body weight, food consumption, changes in
hematological, clinical chem. & urinalysis parameters, increases in
selected organ wts., cytoplasmic swelling of glandular epithelium of
submaxillary gland, minimal degrees of fiber degeneration in sciatic
nerve (# not reported) which disappeared after recovery period.

Note: The NOAEL was changed to 15 mg/kg/day and the LOAEL to 50
mg/kg/day by the HIARC (May 21, 2002 report).

870.3465

	90-Day inhalation toxicity (rat)

Cyfluthrin (94.9% a.i.)	00157793 (1984), 40082901, 40239301

Acceptable/guideline 

0, 0.00009, 0.00071, 0.00451 mg/L 

(0, 0.02, 0.16, 0.91 mg/kg/day)

In ethanol/PEG 400 (1:1), 

6 hrs/day, 5 consecutive days/week	NOAEL = 0.00009 mg/L (0.02 mg/kg/day)

LOAEL = 0.00071 mg/L (0.16 mg/kg/day) based on decreased body weights
and body weight gains in males and clinical signs in females.

Non-guideline	4-Week inhalation toxicity (rat)	

Cyfluthrin (93.8% a.i.) 	41842601 (1989)

Acceptable/non-guideline

0, 0.00044, 0.006,  0.047 mg/L 

(0, 0.12, 1.6, 12.8 mg/kg/day)

In ethanol/PEG 400 (1:1), 

6 hrs/day, 5 consecutive days/week	NOAEL = 0.00044 mg/L (0.12 mg/kg/day)

LOAEL = 0.006 mg/L (1.6 mg/kg/day) based on decreases in body weight and
body weight gain in males, hypothermia, reduction in leukocyte counts
(F) and low serum protein.

Non-guideline	4-Week inhalation toxicity (rat)

Beta-cyfluthrin (97.9% a.i.)	41783001 (1989) 

Acceptable/non-guideline

0, 0.00026, 0.0027, 0.023  mg/L

(0, 0.07, 0.73, 6.3 mg/kg/day)

In ethanol/PEG 400 (1:1), 

6 hrs/day, 5 consecutive days/week	NOAEL = 0.00026 mg/L (0.07 mg/kg/day)

LOAEL = 0.0027 mg/L (0.73 mg/kg/day) based on decreased body weights, (
urine pH in males.

Non-guideline	5-Day  inhalation study (rat)	

Beta-cyfluthrin (98% a.i.)	41205708 (1988) 

Acceptable/non-guideline 

0, 0.00025, 0.0038, 0.028 mg/L

(0, 0.07, 1.03, 7.6 mg/kg/day)

In ethanol/PEG 400 (1:1), 

6 hrs/day	NOAEL = 0.00025 mg/L (0.07 mg/kg/day)

LOAEL = 0.0038 mg/L (1.03 mg/kg/day) based on unpreened hair coat,
piloerection, hepatoid foci in lungs. 

Non-guideline	28-Day oral toxicity (dog)

Beta-cyfluthrin	41244109 (1986) 

Acceptable/non-guideline

0, 0.25, 2.0, 16.0/8.0 mg/kg/day 

(2 dogs/sex/dose)	NOAEL = 2.0 mg/kg/day (both sexes)

LOAEL = 8.0 mg/kg/day based on impaired movement and conjunctival
irritation.

870.3700a

	Prenatal oral developmental toxicity in rodents (rat)

Beta-cyfluthrin (96.5-97.3% a.i.)	44116501 (1996)

Acceptable/guideline 

0, 3, 10, 40 mg/kg/day

1% Cremophor in municipal tap water	Maternal NOAEL = 3 mg/kg/day

Maternal LOAEL = 10 mg/kg/day based on reduced body weight gain and
reduced food consumption with post-treatment recovery.  

Developmental NOAEL = 10 mg/kg/day

Developmental LOAEL = 40 mg/kg/day based on reduced fetal body weights
and increased skeletal variations.  

870.3700a	Prenatal oral developmental toxicity in rodents (rat)

Cyfluthrin (93.4%)	00157794 (1983)

Unacceptable/guideline

0, 1, 3, 10 mg/kg/day

1% Cremophor EL in distilled water	Maternal NOAEL = 10 mg/kg/day

Maternal LOAEL = not observed

Developmental NOAEL = 10 mg/kg/day

Developmental LOAEL = not observed

870.3700b

	Prenatal oral developmental toxicity in non-rodents (rabbit)

Cyfluthrin 

(96% a.i.) 	42675401 (1992)

Acceptable/guideline

0, 20, 60, 180 mg/kg/day

In corn oil, by gavage	Maternal NOAEL = 20 mg/kg/day

Maternal LOAEL = 60 mg/kg/day based on decreased body weight gain and
food consumption during the dosing period.  

Developmental NOAEL = 180 mg/kg/day

Developmental LOAEL = not observed

870.3700a	Prenatal inhalation developmental toxicity in rodents (rat )

Cyfluthrin (96.2% a.i.) 

	43393401 (1991-1994)

Acceptable/guideline 

0, 0.00046, 0.00255, 0.0119, 0.0128 mg/L/day (0.125, 0.692, 3.234, 3.478
mg/kg/day)

In PEG-400:ethanol for 6 hrs/day	Maternal NOAEL = not determined

Maternal LOAEL = 0.00046 mg/L (0.125 mg/kg/day) based on decreased body
weight gain and relative food efficiency.

Developmental NOAEL = 0.00046 mg/L (0.125 mg/kg/day)

Developmental LOAEL = 0.00255 mg/L (0.692 mg/kg/day) based on reduced
fetal and placental weights and reduced ossification in phalanx,
metacarpals, vertebrae.

870.3700a	Prenatal inhalation developmental toxicity in rodents (rat )

Cyfluthrin (92.9% and 93%) 

	40780401 (1988) 

Acceptable/guideline 

1.   0, 0.0011, 0.0047, 0.0237 mg/L/day

(0, 0.299, 1.277, 6.44 mg/kg/day)

2.  0, 0.00009, 0.00025, 0.00059, 0.0042 mg/L/day

(0, 0.0245, 0.0679, 0.160, 1.141 mg/kg/day)

Dissolved in a 1:1 mixture of Lutrol and ethanol for 6 hrs/day.	Maternal
NOAEL = 0.0011 mg/L (0.299 mg/kg/day)

Maternal LOAEL = 0.0047 mg/L (1.277 mg/kg/day) based on reduced
motility, dyspnea, piloerection, ungroomed coats, eye irritation.

Developmental NOAEL = 0.00059 mg/L (0.160 mg/kg/day)

Developmental LOAEL = 0.0011 mg/L (0.299 mg/kg/day) based on increased
incidence of runts and skeletal anomalies in sternum. 

Non-guideline	7-Day postnatal inhalation study (pups & dams) in mice
with spontaneous motor activity measurements

Cyfluthrin (96.8% a.i.)	44373401 (1997)

Acceptable/non-guideline

0, 0.006, 0.015, 0.058 mg/L

(0, 2.48, 6.21, 24.0 mg/kg/day)

In PEG 400, 6 hrs/day, for 7 consecutive days	Maternal NOAEL = 0.058
mg/L (24.0 mg/kg/day) 

Maternal LOAEL = not determined

Offspring NOAEL = 0.006 mg/L (2.48 mg/kg/day)

Offspring LOAEL = 0.015 mg/L (6.21 mg/kg/day) based on clinical signs of
toxicity and spontaneous motor activity observed in females 4 months
after exposure. 

870.3800	Reproduction and fertility effects

(rat)

Cyfluthrin (95.4% a.i.), corn oil/acetone premix	44371401 (1996) 

Acceptable/guideline

Premating and gestation:

M:  0, 3, 9, 29 mg/kg/day

F:  0, 4, 10, 33 mg/kg/day

First 2 weeks of lactation:

0, 7, 19, 59 mg/kg/day 

	Parental/Systemic NOAEL = 3/4 mg/kg/day (M/F)

Parental/Systemic LOAEL = 9/10 mg/kg/day (M/F) based on reductions in
body weights and food consumption.

Offspring NOAEL = 7 mg/kg/day (M/F)

Offspring LOAEL = 19 mg/kg/day based on coarse tremors in pups during
lactation and decreases in mean litter weight.

Non-guideline	“Supplemental” 2-generation reproduction study (rat)

Cyfluthrin (95.5% a.i.)	44371402 (1997)

Acceptable/non-guideline 

M:  0, 1.9, 3.8 mg/kg/day

F:  0, 2.1, 4.2 mg/kg/day

Corn oil/acetone premix	Parental/Systemic NOAEL = 3.8/4.2 mg/kg/day
(M/F)

Parental/Systemic LOAEL = not determined

Offspring NOAEL = 3.8/4.2 mg/kg/day (M/F)

Offspring LOAEL = not determined

Non-guideline	Pilot one-generation reproduction study (rat)

	

Cyfluthrin (95.7-96.2% a.i.), corn oil/acetone premix 

	43792901 (1995)

Acceptable/non-guideline

M:  0, 3.4, 9.3, 24.2, 38.9 mg/kg/day

F:  0, 4.1, 10.5, 27.2, 43.9 mg/kg/day

Gestation:

0, 3.9, 10.1, 27.2, 45.0 mg/kg/day 

Lactation:

0, 7.8, 22.9, 59.6, 95.9 mg/kg/day	Parental/Systemic NOAEL = 22.9
mg/kg/day

Parental/Systemic LOAEL = 59.6 mg/kg/day based on hind leg splay,
ataxia, reduction in body weight gain.

Offspring NOAEL = 7.8 mg/kg/day

Offspring LOAEL = 22.9 mg/kg/day based on tremors during lactation and
pup weight decreases.

Dosages for the NOAEL and LOAEL calculated from weekly mean test
material consumption during lactation because both the large variation
in consumption values and the increased test material consumption during
the time that the effects were noted.



870.3800	Reproduction and fertility effects (rat)

	(1983)

Cyfluthrin	00131532 (1983)

Acceptable 

M:  0, 3.8, 12.3, 37.2 mg/kg/day

F:  0, 5.4, 15.1, 48.5 mg/kg/day

This study was classified core minimum, although it had a number of
deficiencies:  test article 50% premix with Wessalon S, no individual
litter observations, limited necropsy & histopathology, other reporting
deficiencies.	Parental/Systemic NOAEL = 12.3/15.1 mg/kg/day (M/F)

Parental/Systemic LOAEL = 37.2/48.5 mg/kg/day (M/F) based on decreased
body weight gain.

Offspring NOAEL = 5.4 mg/kg/day

Offspring LOAEL = 15.1 mg/kg/day based on decreased viability during
lactation period and decreased body weight gains.



870.4100b

	Chronic toxicity (dog)

Cyfluthrin

(94.9-95.1% a.i.)	44435401 (1997)

Acceptable/guideline

M:  0, 1.36, 2.43, 10.64, 15.47 mg/kg/day

F:  0, 1.46, 3.61, 10.74, 17.99 mg/kg/day

Corn oil premix	NOAEL = 2.43/3.61 mg/kg/day (M/F)

LOAEL = 10.64/10.74 mg/kg/day (M/F) based on clinical signs, gait
abnormalities, and abnormal postural reactions in males and females.

870.4100b	Chronic toxicity (dog)

Cyfluthrin 	00151358 (1983)

Core minimum 

0, 1, 4, 16 mg/kg/day

50% premix with Wessalon S	NOAEL = 4.0 mg/kg/day

LOAEL = 16.0 mg/kg/day based on gait abnormalities, vomiting, liquid
feces, decreased body weights (males).

870.4100b	6-Month oral toxicity (dog)

Cyfluthrin	00131530 (1981)

Core minimum

0, 1.62, 5, 15 mg/kg/day	NOAEL = 5.0 mg/kg/day

LOAEL = 15.0 mg/kg/day based on gait abnormalities, arching backs,
vomiting, diarrhea.

870.4200	Carcinogenicity (mouse)

Cyfluthrin ((93.9% a.i.)	44589701 (1998)

Acceptable/guideline 

M:  0, 31.9, 114.8, 232.7 mg/kg/day

F:  0, 38.4, 140.6, 309.7 mg/kg/day

Corn oil premix	NOAEL = 31.9/140.6 mg/kg/day (M/F)

LOAEL = 114.8 mg/kg/day (M) based on ear skin lesions and reduced body
weight gains.  309.7 mg/kg/day (F) based on clinical signs, macroscopic
and microscopic pathology findings, and reduced body weights, body
weight gains, and food consumption.

No evidence of carcinogenicity

870.4200	Carcinogenicity (mouse)

Cyfluthrin 

(49.7-51.0% a.i.)	00137304 (1983)

Acceptable/guideline

M:  0, 11.6, 45.8, 194.5 mg/kg/day

F:  0, 15.3, 63.0, 259.9 mg/kg/day

Premix in Wessalon S	Study not acceptable for chronic toxicity.

No evidence of carcinogenicity



870.4300	Combined chronic feeding/ carcinogenicity (rat) 

Cyfluthrin (94.7% a.i.), 	44459301 (1997)

Acceptable/guideline

M:  0, 2.6, 11.6, 22.8 mg/kg/day

F:  0, 3.3, 14.4, 28.3 mg/kg/day

Acetone/corn oil pre-mix	NOAEL = 2.6/3.3 mg/kg/day (M/F)

LOAEL = 11.6/14.4 mg/kg/day (M/F) based on overall declines in body
weight gain by 12 and 10% in males and females, respectively.

No evidence of carcinogenicity

870.4300	Combined chronic feeding/ carcinogenicity (rat) 

Cyfluthrin 

(49.7-51.0% purity as a premix concentrate in Wessalon S)	00137303
(1983)

Acceptable/guideline

M:  0, 2.02, 6.19, 19.20 mg/kg/day

F:  0, 2.71, 8.15, 25.47 mg/kg/day

	NOAEL = 6.19/8.15 mg/kg/day (M/F)

LOAEL = 19.20/25.47 mg/kg/day (M/F) based on decreased body weights and
body weight gains.  

No evidence of carcinogenicity

870.5100	Gene mutation – bacterial reverse mutation assay

Cyfluthrin	00131539 (1982)

Acceptable/guideline

5-5000 ug/plate

	Negative.  

No increases in reverse mutations with and without activation.

870.5100	Gene mutation – yeast reverse mutation assay

Cyfluthrin	00131541, 00144017 (1982)

Acceptable/guideline	

312.5-1000 ug/mL	Negative.  

No increase in number of revertants with S138 cultures.  Increase in
number of revertants with S211 culture but not dose-related; no increase
in number of revertants when assay repeated.

870.5100	Gene mutation – bacterial reverse mutation assay

Cyfluthrin	00131540 (1982)

Acceptable/guideline	Negative.

No increases in reverse mutations with and without activation.

870.5100	Gene mutation – bacterial reverse mutation assay

Beta-cyfluthrin	41244110 (1986)

Acceptable/guideline 

Initial assay: 

20-12500 ug/plate

Confirmatory assay:  

500-8000 ug/plate	Negative.

No increases in reverse mutations in S. typhimurium strains TA 1535, TA
1537, TA 98 or TA 100 with and without activation.

870.5300	Gene mutation – 

in vitro mammalian cell gene forward mutation assay

Cyfluthrin	00157796 (1985)

Acceptable/guideline

3, 5, 7, 9, 10 ul/ml

	Negative.

Cyfluthrin did not induce forward mutations under conditions of assay

870.5300	Gene mutation – 

in vitro mammalian cell gene forward mutation assay

Beta-cyfluthrin	41244112 (1989)

Acceptable/guideline

50-100 ug/mL (insoluble), 20-40 ug/mL (soluble)	Negative.

No mutagenic response in CHO cells HGPRT assay with and without
activation.

870.5375	Cytogenetics -  in vitro mammalian cell chromosome aberration
test

Beta-cyfluthrin	41205703 (1988)

Acceptable/guideline 

500, 1000, 5000 ug/mL	Negative.

Not clastogenic in human lymphocytes.

870.5395	Cytogenetics –

mammalian erythrocyte micronucleus test

Beta-cyfluthrin	4124411 (1988)

Acceptable/guideline 

80 mg/kg

	Negative.

No increased frequency of micronucleated polychromatic erythrocytes in
mice bone marrow cells.

870.5500	Other effects – bacterial DNA damage 

Cyfluthrin	00131540 (1982)

Acceptable/guideline	Negative.

In rec- assay, no inhibition at doses of 100-10000 ug/disk.



870.5550	Other effects – bacterial DNA damage and repair in E. coli 

Cyfluthrin	00131538 (1981)

Acceptable/guideline

62.5-1000 ug/plate	Negative.

No induction of inhibition, both with and without activation.

870.5550	Other effects –

unscheduled DNA synthesis in cultured rat hepatocytes 

Cyfluthrin	00157798 (1985)

Acceptable/guideline

17, 50, 167, 500, 1667, 5000 ug/ml	Negative.

870.5550	Other effects –

unscheduled DNA synthesis in mammalian cells in culture

Beta-cyfluthrin 	41205704 (1987)

Acceptable/guideline 

1.01-1010 ug/mL

	Negative. 

870.5575	Other effects – 

mitotic gene conversion in Saccharomyces cerevisiae 

Cyfluthrin	00131542 (1982)

Acceptable/guideline

625-10000 ug/ml

	Negative.

870.5915	Other effects – in vivo sister chromatid exchange assay in
Chinese hamster ovary cells 

Cyfluthrin	00157795 (1985)

Acceptable/guideline

Non-activated assays:  3, 5, 10, 20 ug/ml 

Activated assays:  125, 250, 500, 1000 ug/ml 	Negative.

no increase in SCE frequency in treated cells 



870.6100	Delayed neurotoxicity (hen)

Cyfluthrin	00156585 (1985)

Supplementary

0 and 5000 mg/kg/day for 3 days	All hens died within 3 days; NTE
activity was not inhibited

870.6100	Oral delayed neurotoxicity (hen)

Cyfluthrin	00131543 (1981)

Supplementary

10 hens:  1000 (1x), 2500 (1x), 5000 (1x) mg/kg; 

30 hens:  5000 mg/kg (2x, 21 days apart); 

10 hens:  5000 mg/kg (5x daily for 1 week)

	In the single dose study, at 5000 mg/kg, five of the ten hens died.  
Moderate fiber alterations (axon fragmentation, occasional swelling and
eosinophilia of the axon fragments and vacuolation of the myelin
sheaths) in the sciatic nerve were observed in 2 hens.  Six hens at 2500
mg/kg showed signs of excitation during the first 3 days following
treatment. In the two dose study, hens showed initial signs of
intoxication during the first 3 days but were normal until the second
dose was administered when 4 hens died.  Symptoms following the second
treatment subsided; however, a second set of symptoms developed in 4/30
hens.  These symptoms resembled delayed type neurotoxicity.  Nerve fiber
degeneration was present in the majority of the hens.  The myelin sheath
was distended and the myelin sheath was described as being optically
void or granularly disintegrated.  The axons were described as swollen
or fragmented and in some areas activated or proliferated Schwann’s
cells were noted.  The nerves also contained macrophages in which
cytoplasm contained granular material.  In the 5-day study, 4/10 hens
died.  All hens showed initial toxic responses which eventually
disappeared.  Behavioral disorders accompanied by drowsiness and a
cramped gait were observed in 3 of the 6 survivors.  Mottled kidneys and
brittle livers were noted at necropsy.  Treatment-related fiber
degeneration (distension or granular disintegration of the medullary
sheath, swollen or fragmented axis cylinders and proliferated
Schwann’s cell in the sciatic nerve were reported.  One hen had
similar lesions in the spinal marrow.

870.6100	Oral delayed neurotoxicity (hen)

Cyfluthrin	 00131544 (1982)

10 hens: (5000 mg/kg, 1 x) or  20 hens: (5000 mg/kg, 2 x, 7 days apart).
  The first study was classified as Core supplementary - no
histopathology conducted) and the second study was classified as Core
minimum.	In the single dose study, the hens showed an initial weight
loss but recovered.  No other treatment-related effects were observed. 
In the two-dose study, 1 hen showed some signs of neurotoxicity on day
30.  There were no microscopic lesions in the nervous system.  

870.6100	Dermal delayed neurotoxicity (hen)

Cyfluthrin	00131545 (1982)

Minimum 

5000 mg/kg (paste with cellulose powder); in the first study, 10 hens
were exposed for 5 days for 23 hours/day.  In the second study, 10 hens
were exposed for 3 weeks, 5 days/week, 6 hours/day.	In the first study
there were 2 deaths on the 3rd and 10th day.  All other hens had
symptoms (apathy and disturbed behavior) but recovered.  Local
irritation and weight loss were also noted.  Two hens had minimal
segment-like nerve fiber degeneration (sciatic nerve), but this type is
often found in hens.  In the second study, the hens were apathetic. 
These symptoms disappeared after the first week in all hens except 2, in
which they persisted until the 38th and 51st day after the start of the
treatment, respectively.  Local irritation and body weight loss were
also observed.  No other neurologic effects were observed, including
microscopic. 

870.6100	Acute delayed neurotoxicity (hen)

Cyfluthrin	00131510 (1983)

Core minimum

 single 4-hour exposure or to 15 six-hour exposures over a 3-week period
at concentrations of  0.285, 0.445 or 0.596 mg/L in the single dose
study and 0.614 mg/L in the 3 week study	Nine of 10 hens died at 0.596
mg/L and none died in any of the lower concentrations.  These had some
nonspecific symptoms (behavior disturbances, sedation, eye irritancy),
which disappeared after 2 days.  Some initial weight loss was also
noted.  In the 3-week study, one hen died.  Nonspecific symptoms were
again observed.  Nothing remarkable was noted at necropsy.

870.6100	Acute delayed neurotoxicity (hen)

Cyfluthrin	00163040 (1986)

Core Minimum

4300 (1x), 4300 (2x: days 1 & 21), 1500 (5 consecutive days). 	4300,
1500: mortality, aggression, somnolence, cyanosis of crest.  Sl. axonal
degeneration of sciatic nerve in 1 hen given a single dose; sl. axonal
degeneration of spinal cord in 1 hen given 2 doses.  No
treatment-related changes in NTE activity.

870.6200a

	Acute neurotoxicity (rat)

Beta-cyfluthrin

((96.9% a.i.)	44401101  (1997) Acceptable/guideline 

0, 0.5, 2, 10 mg/kg 

In 1% Cremophor EL in deionized water	NOAEL = 2 mg/kg

LOAEL = 10 mg/kg based on clinical signs, changes in FOB parameters, and
decreases in motor activity.

870.6200b	Subchronic neurotoxicity (rat)

Beta-cyfluthrin ((96.5% a.i.) 	44296001 (1997) Acceptable/guideline 

M:  0, 2.02, 7.99, 26.81 mg/kg/day

F:  0, 2.34, 9.40, 30.83 mg/kg/day

In corn oil, 1% by weight in diet	NOAEL = 7.99/9.40 mg/kg/day (M/F)

LOAEL = 26.81/30.83 mg/kg/day (M/F) based on clinical signs, changes in
FOB measurements and possibly decreased body weights, body weight gains,
and food consumption

870.6300	Developmental neurotoxicity (rat)

Beta-cyfluthrin (95.1-97.6% a.i.)	46054101 (2003)

Acceptable/non-guideline

0, 30, 125, 200 ppm 

(Gestation:  0, 2.4, 11.0, 17.8 mg/kg/day)	Maternal NOAEL = 17.8
mg/kg/day

Maternal LOAEL = not observed

Offspring NOAEL = 11.0 mg/kg/day

Offspring LOAEL = 17.8 mg/kg/day based on decreased body weight and body
weight gain and decreased brain weights in females at termination.

870.7485	Metabolism and Pharmacokinetics

Cyfluthrin 

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remophor EL)	00072007 (1983)

Core Minimum when considered together with metabolism part of study

Single oral dose: 

0.5 and 10 mg/kg

Single i.v. dose: 

0.5 and 10 mg/kg 

Repeated oral dose:

0.5 mg/kg/day unlabeled for 14 days, then single dose labeled	Following
oral administration, the test material was rapidly and nearly completely
absorbed.  Peak plasma levels of radioactivity were observed at about 2
hours after dosing.  Greater than 95% of the administered radioactivity
was excreted within 48 hours.  Radioactivity was excreted in the urine
and feces with virtually none being excreted in expired air.  By 48
hours after dosing, >98% of the total retrieved radioactivity was
recovered in the urine and feces. The ratio of radioactivity in
urine/feces was higher in males than in females.  About 50% of the total
urinary radioactivity was recovered during the first 6-8 hours after
dosing and about 90% within the first 24 hours.  At 48 hours, only the
fat tissue (renal fat) contained levels of radioactivity that clearly
exceeded the overall mean body level, being 6-11X higher.  Levels of
radioactivity in brain were quite low, being 15-20X lower than the
overall mean body level. Different dose levels (0.5 or 10 mg/kg) or
pretreatment (14X) did not appreciably affect the above findings.  Some
sex differences, however, were observed as indicated by higher
urine/feces ratios in males and slightly higher organ/tissue levels of
radioactivity in females (except for fat tissue).

Following intravenous administration, a 2 phase plasma elimination
pattern was observed with plasma half-lives of about 2.1 and 20 hours. 
The apparent volume of distribution (Vd) was about 17% of the total body
volume, corresponding to the “readily diffusable part of the
extracellular fluid”.  Greater than 90% of the administered
radioactivity was excreted within 48 hours.  By 48 hours after dosing,
about 93-94% of the total retrieved radioactivity was recovered in the
urine and feces.  Residual levels of radioactivity in the body and in
individual organs/tissues were higher than after oral administration. 
In other respects, the results following intravenous dosing were quite
similar to those described for oral dosing.  Studies in male rats with
bile fistulas indicated an enterohepatic circulation of test material.

870.7485	Metabolism and Pharmacokinetics

Cyfluthrin 

(98% purity in 5% Cremophor EL)	00072007 (1983)

Core Minimum when considered together with biokinetic part of study

Single oral dose: 

0.5 and 10 mg/kg

Single i.v. dose: 

0.5 and 10 mg/kg 

Repeated oral dose:

0.5 mg/kg/day unlabeled for 14 days, then single dose labeled

	

Excretion of radioactivity was rapid.  Following oral administration,
>95% of the administered radioactivity was excreted within 48 hours, and
following intravenous injection, >90% within 48 hours.  Most of the
radioactivity was excreted in urine, the urine/fecal ratio being about
2-3X in males and about 1.6-1.8X in females following oral
administration and about 2.5X in males and about 2.6X in females
following intravenous injection.  Parent cyfluthrin is cleaved at the
ester bond and then oxidized to yield 3-phenoxy-4-fluorobenzoic acid. 
This intermediate is then either hydroxylated and subsequently
conjugated and excreted or first bound to glycine and then hydroxylated,
conjugated and excreted.  Identified metabolites and parent cyfluthrin
(in urine, feces and body) accounted for 65-73% of the recovered
radioactivity after a single oral or intravenous dose of 0.5 mg/kg and
about 82-83% of the recovered radioactivity after a single oral dose of
10 mg/kg or after 14 daily oral doses.



 TC \l1 " Appendix D:  Review of Human Research 

Appendix C  Summary of Cyfluthrin/Beta-cyfluthrin Tolerances

Appendix C; Table 1

Tolerance  Summary Table for Cyfluthrin/Beta-cyfluthrin

Commodity	Established Tolerance (ppm)	Proposed Tolerance (ppm)
Recommended Tolerance (ppm)	Comments; Correct Commodity Definition

Grass, forage, fodder and hay, group 17, forage	6.0 1	13.0	12	Adequate
grass field trial data are available.



Grass, forage, fodder and hay, group 17, hay	8.0 1	40.0	50

	Alfalfa, forage	-	5.0	5.0	Adequate alfalfa field trial data are
available.



Alfalfa, hay	10.0	15.0	13

	Beet, sugar, roots	-	0.09	0.10	Adequate field trial data are available

Beet, sugar, dried pulp	-	11	1.0	Maximum expected residues are 0.59 ppm
based on HAFT residues of 0.049 ppm and a 12x processing factor for
dried pulp.

Grain, cereal; Crop Group 15 (except Rice)	4.0	4.0	0.15	Wheat grain,
barley grain, buckwheat grain, millet grain, oat grain, rye grain,
triticale grain

Grain, cereal; Crop Group 15 (except Rice)	4.0	4.0	0.05	Corn, field,
grain

Grain, cereal; Crop Group 15 (except Rice)	4.0	4.0	0.05	Corn, sweet,
kernel plus cob with husks removed

Grain, cereal; Crop Group 15 (except Rice)	4.0	4.0	3.5	Sorghum, grain,
grain

Wheat, bran	6.5	-	0.5	Stored grain uses have been revoked

Corn, field, refined oil	30.0	-	-	The field corn, grain tolerance will
cover residues in corn oil

Rice, bran	6.0	-	-	Stored grain uses have been revoked

Rice, hulls	18.0	-	-	Stored grain uses have been revoked

Grain, cereal, forage, fodder and straw, Crop Group 16 (except Rice)	-2
7.0	25	Grain, cereal, forage, fodder and hay, group 17, forage, except
rice

Grain, cereal, forage, fodder and straw, Crop Group 16 (except Rice)	- 3
7.0	30	Grain, cereal, forage, fodder and hay, group 17, stover, except
rice

Grain, cereal, forage, fodder and straw, Crop Group 16 (except Rice)	- 4
7.0	7.0	Grain, cereal, forage, fodder, and hay, group 17, straw, except
rice

Grain, cereal, forage, fodder and straw, Crop Group 16 (except Rice)	- 5
7.0	6.0	Grain, cereal, forage, fodder and hay, group 17, hay, except
rice

Wheat, forage	5.0	-	-	Crop group tolerance is being established for
Forage of Grain, Cereal, except Rice (Crop Group 16)

Corn, field, forage	3.0	-	-

	Corn, sweet, forage	15	-	-

	Sorghum, grain, forage	2.0	-	-

	Corn, field, stover	6.0	-	-	Crop group tolerance is being established
for Stover of Grain, Cereal, except Rice (Crop Group 16)

Corn, pop, stover	6.0	-	-

	Corn, sweet, stover	30.0	-	-

	Sorghum, grain, stover	5.0	-	-

	Wheat, hay	6.0	-	-	Crop group tolerance is being established for Hay of
Grain, Cereal, except Rice (Crop Group 16)

Wheat, straw	6.0	-	-	Crop group tolerance is being established for Straw
of Grain, Cereal, except Rice (Crop Group 16)

Cattle, fat	10	NA	2.0	Based on the recalculated maximum dietary burdens
(MDBs) for beef cattle (20.9 ppm), dairy cattle (27.1 ppm) and swine
(3.21 ppm) and the residue data from the available cattle feeding study,
tolerances for livestock commodities can be substantially reduced.

Cattle, meat	0.4	NA	0.10

	Cattle, meat byproducts	0.4	NA	0.10

	Goat, fat	10	NA	2.0

	Goat, meat	0.4	NA	0.05

	Goat, meat byproducts	0.4	NA	0.05

	Hog, fat	10	NA	0.5

	Hog, meat	0.4	NA	0.01

	Hog, meat byproducts	0.4	NA	0.01

	Horse, fat	10	NA	2.0

	Horse, meat	0.4	NA	0.05

	Horse, meat byproducts	0.4	NA	0.05

	Milk	1.0	NA	0.2

	Milk, fat	30	NA	5.0

	Sheep, fat	10	NA	2.0

	Sheep, meat	0.4	NA	0.05

	Sheep, meat byproducts	0.4	NA	0.05

	NA = not applicable

1 Regionally restricted tolerances for grass grown in CA, OR, ID and WA.

2 Forage tolerances are established for wheat (5.0 ppm), field corn (3.0
ppm), sweet corn (15 ppm), and sorghum (2.0 ppm)

3 Stover tolerances are established for field corn (6.0 ppm), popcorn
(6.0 ppm), sweet corn (30 ppm), and sorghum (5.0 ppm)

4 A Straw tolerance is established for wheat (6.0 ppm)

5 A hay tolerance is established for wheat (6.0 ppm)

 Ware, G.W. The Pesticide Book. Fresno, CA, Thomson Publications, 1994,
pgs 171-172.

Page   PAGE  10  of   NUMPAGES  66 

