EPA REGISTRATION DIVISION COMPANY NOTICE OF FILING FOR 

PESTICIDE PETITIONS PUBLISHED IN THE FEDERAL REGISTER 

EPA Registration Division contact: Mark Suarez (703-305-0120)

INSTRUCTIONS: Please utilize this outline in preparing the pesticide petition. In 

cases where the outline element does not apply, please insert “NA-Remove” and 

maintain the outline. Please do not change the margins, font, or format in your 

pesticide petition. Simply replace the instructions that appear in green, i.e., “[insert 

company name],” with the information specific to your action.

TEMPLATE:

Bayer CropScience LLC

[Insert petition number]

EPA has received a pesticide petition ([insert petition number]) from Bayer 

CropScience LLC, 2 T. W. Alexander Drive, Research Triangle Park, NC 27709

proposing, pursuant to section 408(d) of the Federal Food, Drug, and Cosmetic Act 

(FFDCA), 21 U.S.C. 346a(d), to amend 40 CFR part 180. by establishing a tolerance for

residues of deltamethrin [(1R, 3R)-3(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylic acid (S)-alpha-cyano-3-phenoxybenzyl ester] and its major metabolites transdeltamethrin [(s)-alpha-cyano-3-phenoxybenzyl-(1R, 3S) -3-(2,2-dibromovinyl)-2,2-

dimethylcyclopropanecarboxylate] and alpha-R-deltamethrin [(R)-alphacyano-3-

phenoxybenzyl-(1R, 3R)-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate]: in 

or on food and feed commodities at 0.05 ppm following wide-area mosquito adulticide 

applications. EPA has determined that the petition contains data or information regarding 

the elements set forth in section 408 (d)(2) of the FDDCA; however, EPA has not fully

evaluated the sufficiency of the submitted data at this time or whether the data supports 

granting of the petition. Additional data may be needed before EPA rules on the petition.

A. Residue Chemistry

1. Plant metabolism. The metabolism of deltamethrin in plants is well understood. 

Deltamethrin metabolism studies in tomatoes, corn, apples, and cotton demonstrate the 

same metabolic pathway. The residues of concern are the parent cis-deltamethrin, and its 

isomers, trans-deltamethrin and alpha-R-deltamethrin.

2. Analytical method. Residues of deltamethrin (cis and trans isomers) were 

extracted from homogenous 10-g samples of alfalfa forage, lettuce leaves, and grass 

forage using acetone/n-hexane/ dichloromethane as the extraction solvent. Homogenous 
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5-g samples of alfalfa hay and grass hay were soaked in water overnight prior to 

extraction. Residues of cis-deltamethrin and trans-deltamethrin were extracted using 

acetone/ n-hexane/dichloromethane as the extraction solvent with sonication. Samples 

were then filtered before an IS solution was added. After evaporation of the organic 

phase to dryness, the dry residue was taken up with toluene. An aliquot of the toluene 

extract was concentrated to dryness and dissolved in dichloromethane/acetone, followed 

by solid phase extraction (SPE) clean up with Varian MEGA BE SCX-2 GM cartridges. 

The extracts were again concentrated to dryness and dissolved in aqueous acetonitrile/10 

mM ammonium acetate before analysis by HPLC/MS/MS.

HPLC separation was performed with an Ascentis Express C18, 2.7 μm, 150 mm × 3 mm 

HPLC column. 

Quantitation of each analyte was based on the daughter ion transitions of the analyte and 

the respective internal standard analog. The responses of LC/MS/MS system to each 

analyte and its internal standard were measured in samples and in standards, and a 

relative response was calculated (calculated as the ratio of the analyte and the stable 

isotopically labeled internal standard responses). The relative response of the analyte in 

each sample was compared to the relative response of the analyte in the standards.

The total deltamethrin residue is the sum of the individual measured residue of cisdeltamethrin and trans-deltamethrin.

3. Magnitude of residues. Two field trials were conducted to measure the 

magnitude of deltamethrin residues in/on alfalfa, leaf lettuce, and grass following each of 

ten broadcast foliar ultra-low volume (ULV) spray applications of BES0668 Insecticide. 

BES0668 Insecticide was applied to alfalfa, leaf lettuce, and grass at two different target 

rates of 0.75 g ai/ha/application and 1.5 g ai/ha/application. The interval between 

applications was 2 to 4 days. All applications were made with ULV misters that 

produced droplets typical of commercial equipment (≥80% of the droplets were <20 μm 

in diameter). Results:

Alfalfa; Based on the average residues in alfalfa forage, residues would be expected to 

remain below 0.050 ppm following multiple treatments at either rate. At the 1.5 g 

ai/acre/application treatment rate, total residues varied from 0.0174 ppm to 0.1205 ppm 

with the average residues remaining below 0.080 ppm at all time points. Since the dried 

matrix of alfalfa hay is only used for animal feed, secondary residues in meat milk, and 

eggs arising from this use at either rate would be expected to be negligible.

Leaf Lettuce; At both the 0.75 g ai/acre/application and the 1.5 g ai/acre/application 

treatment rates, all residues in leaf lettuce at all time points were below the current food 

use tolerance (<0.050 ppm). Based on the average residues in leaf lettuce, residues 

would be expected to remain below 0.050 ppm following multiple treatments at either 

rate.

Grass; Based on the average residues in grass forage, residues would be expected to 

remain at or below 0.050 ppm following multiple treatments at either rate. At the 1.5 g 
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ai/acre/application treatment rate, total residues varied from 0.0298 ppm to 0.1495 ppm 

with the average residues remaining below 0.1200 ppm at all time points. 

Since the dried matrix of grass hay forage is only used for animal feed, secondary

residues in meat milk, and eggs arising from this use at either rate would be expected to 

be negligible.

B. Toxicological Profile

1. Acute toxicity. The acute oral toxic potency of deltamethrin depends on the 

vehicle that is used, with an LD50 in rats that ranges from 66.7 mg/kg (males) when 

administered in sesame oil to >5000 mg/kg (both sexes) in an aqueous methylcellulose 

suspension. Deltamethrin technical is classified in Category II for acute oral and 

inhalation toxicity, Category III for dermal toxicity and eye irritation and Category IV for 

skin irritation. Deltamethrin is not a skin sensitizer but can cause transient paresthesia (a 

local itching, burning or tingling sensation of the skin) following skin contact to sensitive 

individuals.

2. Genotoxicity. There was no evidence of mutagenicity in a battery of in vitro 

and in vivo studies with technical-grade deltamethrin. Therefore, deltamethrin is 

classified as non-mutagenic.

3. Reproductive and developmental toxicity. A rat development toxicity study

conducted with deltamethrin indicated a maternal NOEL of 3.3 mg/kg/day based on

clinical observations, decreased weight gain and mortality. The developmental NOEL 

was 11mg/kg/day (HDT). 

In a rabbit development toxicity study with deltamethrin, the maternal NOEL was

considered to be 10 mg/kg/day based on decreased body weights at 32 mg/kg/day. The 

developmental NOEL was > 32 mg/kg/day (HDT). 

In a developmental neurotoxicity study, the maternal NOAEL was 6.8 mg/kg bw/day, 

based on decreased body weight, weight gain and food consumption during gestation and 

decreased body weight and food consumption during lactation noted at 16 mg/kg/day. 

The offspring NOAEL was 6.8 mg/kg bw/day, based on delayed balanopreputial 

separation, reduced body weight and weight gain before weaning for both sexes, with 

recovery after weaning. There was no evidence of neurodevelopment effects at any dose 

level.

In a two-generation rat reproduction study with deltamethrin the parental NOAEL was 

5.4 mg/kg/day based on clinical signs and increased mortality. The offspring NOAEL 

was 5.8 mg/kg/day based on decreased body weights, body weight gain and increased 

pup mortality. Deltamethrin was not a reproductive toxicant.

4. Subchronic toxicity. A 90-day rat oral toxicity study was conducted with

deltamethrin administered by gavage. The NOEL was 1.0 mg/kg/day based on reduced 

body weight gain and slight hypersensitivity. In another 90-day rat dietary study with 

deltamethrin, the NOEL was 300 ppm (23.9 mg/kg/day for males, 30.5 mg/kg/day for 
4

females) based on uncoordinated movement, unsteady gait, tremors, increased 

sensitivity to sound, shakes and spasmodic convulsions. The difference in the NOEL 

between the two studies is attributed to the different routes of exposure (gavage in oil 

vs. administered in diet).

A 12-week study was conducted with deltamethrin in mice. The NOEL was 300 ppm

(61.5 mg/kg/day in males and 77.0 mg/kg/day in females) based on chronic

contractions, convulsions, poor condition, decreased weight gain and mortality.

Two 13-week dog studies were conducted with deltamethrin. In the first study, beagle 

dogs were administered deltamethrin by capsule using PEG 200 as a vehicle. The 

NOEL for this study was 1 mg/kg/day based on tremors, unsteadiness, jerking

movements, salivation, vomiting, liquid feces and/or dilation of the pupils. In the

second study, deltamethrin was administered by capsule without a vehicle to beagle

dogs. The NOEL for this study was 10 mg/kg/day based on unsteady gait, tremors, head 

shaking, vomiting and salivation. The difference in toxicity between the two studies is

attributed to the enhanced absorption resulting from the use of PEG 200 as a vehicle in 

the first study. 

A 21-day dermal toxicity study was conducted with deltamethrin in rats. The NOEL for 

systemic toxicity was determined to be 1000 mg/kg/day. In a subchronic inhalation 

study, rats were exposed to aerosolized deltamethrin for 6 hours per day, 5 days per 

week, for a total of 14 days over 3 weeks. Based on slightly decreased body weights and 

neurological effects at higher dose levels, it was concluded that 3 pg/L was the NOEC 

for systemic effects in this study.

5. Chronic toxicity. Deltamethrin was administered in the diet to beagle dogs for 

2 years. No treatment-related effects were observed and the NOEL was judged to be 40 

ppm (1.1 mg/kg/day). In another study, deltamethrin was administered by capsule 

(without a vehicle) to beagle dogs for 1 year. The NOEL in this study was determined at 

1 mg/kg/day based on clinical signs, decreased food consumption and changes in several 

hematology and blood chemistry parameters.

Two rat chronic toxicity/oncogenicity studies were conducted with deltamethrin. In the 

first study, the test substance was administered via the diet to rats for 2 years. The NOEL 

for this study was 20 ppm (1 mg/kg/day) based on slightly decreased weight gain. In a 

more recent study, deltamethrin was administered to rats in the diet for 2 years. The 

NOEL for this study was 25 ppm (1.1 and 1.5 mg/kg/day for males and females, 

respectively) based on neurological signs, weight gain effects and increased incidence of 

histopathological changes to the liver. No evidence of carcinogenicity was noted in either 

study.

Two mouse oncogenicity studies were conducted with deltamethrin. In the first study, 

deltamethrin was administered in the diet for two years. No adverse effects were 

observed and the NOEL was 100 ppm (12 and 15 mg/kg/day, respectively, for males and 

females). In another study, deltamethrin was administered in the diet to mice for 97 
5

weeks. The NOEL was 1000 ppm (15.7 and 19.6 mg/kg/day) based on a higher incidence 

of poor physical condition and a slight transient weight reduction. There was no evidence 

of oncogenicity in either study.

6. Neurotoxicity. Deltamethrin was administered by single gavage in rats. The

NOAEL was 5 mg/kg/day, based on salivation, soiled fur, impaired mobility, no response 

to approach or touch in several animals at 15 mg/kg. There was no evidence of 

neuropathological effects. 

In a subchronic neurotoxicity study, deltamethrin was administered in the diet of 

rats for 13 weeks. The NOAEL was 15 mg/kg/day, based on mortality, clinical signs of 

toxicity, FOB findings, and decreased body weights, body weight gains, and food 

consumption at 56 mg/kg/day. There was no evidence of neuropathological effects.

7. Animal metabolism. The absorption of deltamethrin appears to be highly

dependent upon the route and vehicle of administration. Once absorbed, deltamethrin is 

rapidly and extensively metabolized and excreted, primarily within the first 48 hours, in 

feces and an approximately equal amount in urine. Absorbed deltamethrin is cleaved by

hydrolysis at the ester site followed by rapid sulfate and glucuronide conjugation.

8. Metabolite toxicology. N-A Remove

9. Endocrine disruption. No special studies have been conducted to investigate

the potential of deltamethrin to induce endocrine effects. However, the standard battery

of required toxicity studies include an evaluation of the potential effects on reproduction 

and development, and an evaluation of the pathology of the endocrine organs following 

repeated or long-term exposure. There is no evidence that deltamethrin induces endocrine 

disruption.

C. Aggregate Exposure

1. Dietary exposure. As reported in the 2/17/2010 Human Health Assessment 

Scoping Document, the dietary exposure database is adequate to support the registration 

review of deltamethrin. Addition of Wide Area Mosquito Control use of deltamethrin 

should be covered by existing food handling area tolerances. Oral exposure to BES0668 

Insecticide product would be practically non-existent, because the product would not be 

applied directly to food crops. Therefore, additional dietary exposure would be 

negligible, such that there is no need to include this use in the dietary assessment for 

deltamethrin. 

2. Non-dietary exposure. 

a. Occupational exposure

Deltamethrin for public health mosquito adulticide uses on food/feed 

commodities are to be applied by PCOs only, using ULV aerial applications. The 

potential exposures and associated risks for handlers mixing, loading and applying 

deltamethrin as a mosquito adulticide are based on the proposed label for BES0668 

Insecticide (deltamethrin 2% liquid formulation). The maximum application rate is 
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0.00134 lb ai/acre per day, or 0.036 lb ai/acre per year. A maximum of 25 applications 

are allowed per year.

Aerial mixer/loaders are expected to have the highest exposure potential resulting from 

the occupational use of BES0668. There will be no residential non-occupational 

applications. Unit dermal and inhalation exposures of 37.6 μg/lb a.i. and 0.219 μg/lb a.i., 

respectively for a mixer/loader wearing long pants, a long-sleeved shirt, and protective 

gloves were obtained from the EPA Occupational Pesticide Handler Unit Exposure 

Surrogate Reference Table March 2013 version. A mixer/loader preparing spray solution 

to treat 1200 acres/day will handle 1.6 lb a.i./day. The dermal and inhalation daily

exposures for an 80-kg individual are calculated as follows with a 1% dermal absorption.

Daily Dermal Exposure: 37.6 μg/lb a.i. x 1.6 lb a.i./day x 0.01 ÷ 80 kg = 0.0075 

μg/kg/day

Daily Inhalation Exposure: 0.219 μg/lb a.i. x 1.6 lb a.i./day ÷ 80 kg = 0.0044 μg/kg/day

The dermal and inhalation toxicity endpoints for risk assessment are 1.0 mg/kg/day and 

0.9 mg/kg/day from the 90-day rat oral toxicity and the 21-day rat inhalation toxicity

studies, respectively. The MOEs for dermal and inhalation exposure are 133,000 for 

dermal exposure and 204,500 for inhalation exposure. Pilots and ground mixer/loaders 

and applicators will have larger MOEs.

b. Residential (Non-occupational) exposure and risk

Since applications for public health mosquito control are to be made by 

professional personnel (i.e., not residential) a residential handler exposure assessment is 

not required; however, there are potential post application exposures to adults and 

children from the ULV aerial applications of etofenprox uses in the vicinity of residential 

dwellings. Based on spray drift residue deposition testing submitted with this 

application, an adult whole body surface area is approximately 18,000 cm2 so that the 

spray drift potential exposure to an 80 kg adult 100 feet downwind would range from 6.3 

μg/kg to 15 μg/kg. Based on the Agency’s 1% dermal absorption factor and the shortterm dermal exposure NOAEL of 1 mg/kg/day the MOEs for bystanders would range 

from 67,000 to 160,000 showing minimal risk potential from drift. It is important to note 

that applications are not supposed to occur in a manner that could directly exposure 

someone to the drift. These residues would yield MOEs for toddlers in excess of 1000 

based on the Residential SOP defaults.

D. Cumulative Effects

Deltamethrin is a pyrethroid insecticide. In the cumulative risk assessment for 

pyrethroids, the EPA determined that pyrethroids perturb the kinetics of neuronal 

voltage-gated sodium ion channels (VGSC) following an action potential in vertebrates 

as a common mode of action. However, exposure to deltamethrin according to the 

proposed use pattern is expected to be negligible and therefore would not contribute to 

aggregate exposure or cumulative exposure assessment. The Agency currently retains a 
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3x FQPA safety factor for all pyrethroid insecticides, as per the Cumulative Risk 

Assessment for Pyrethroids (2012), based on evidence of underdeveloped clearance 

mechanisms in neonatal rats reported in the published literature..

E. Safety Determination

1. U.S. population. Based on the negligible potential for exposure and 

completeness of the toxicology database, it can be concluded that aggregate exposure to 

residues of deltamethrin present a reasonable certainty of no harm. The proposed 

mosquito adulticide use pattern will produce only negligible dietary or drinking water 

exposures. Thus, there is a reasonable certainty that the use of deltamethrin in BES0668 

Insecticide as a mosquito adulticide will present no harm from aggregate exposure.

2. Infants and children. FFDCA section 408 provides that EPA shall apply an 

additional ten-fold safety factor for infants and children in the case of threshold effects to 

account for pre and post natal toxicity and the completeness of the database, unless EPA 

determines there is sufficient evidence to support a different safety. The database is 

complete for FQPA purposes and there are no residual uncertainties for pre-/post-natal 

toxicity for deltamethrin, with submission of the immunotoxicity study (OPPTS 

870.7800). However, the Agency currently retains a 3x FQPA safety factor for all 

pyrethroid insecticides, as per the Cumulative Risk Assessment for Pyrethroids (2012), 

based on evidence of underdeveloped clearance mechanisms in neonatal rats reported in 

the published literature. The use pattern for the mosquito adulticide provides expectation 

of negligible exposure to infants or children. Thus, it can be concluded that there is a 

reasonable certainty that no harm will result from aggregate exposure to deltamethrin 

residues.

F. International Tolerances

Deltamethrin is a broad spectrum insecticide used throughout the world to control pests 

of livestock, crops, ornamentals plants and turf, and household, commercial, and 

industrial food use areas. As a consequence a large number of CODEX MRLs exist for 

deltamethrin. The MRLs can be found at the following link;

http://www.codexalimentarius.net/pestres/data/pesticides/details.html?id=135