Page 2 of 71 

1.0 Executive Summary......................................................................................................................... 4 

2.0 Ingredient Profile............................................................................................................................. 8 

2.1 Summary of Proposed End Use Products/Use Patterns................................................... 8 

2.2 Structure and Nomenclature .............................................................................................. 8 

2.3 Physical and Chemical Properties...................................................................................... 9 

3.0 Hazard Characterization/Assessment.......................................................................................... 10 

3.1 Hazard and Dose-Response Characterization ................................................................ 10 

3.1.1 Database Summary............................................................................................. 10 

3.1.2 Toxicological Effects......................................................................................... 10 

3.1.3 Dose-response.................................................................................................... 12 

3.1.4 FQPA ................................................................................................................... 13 

3.2 Absorption, Distribution, Metabolism, Excretion (ADME) ..................................... 13 

3.3 FQPA Considerations........................................................................................................ 14 

3.3.1 Adequacy of the Toxicity Database................................................................... 14 

3.3.2 Evidence of Neurotoxicity ................................................................................ 14 

3.3.3 Developmental Toxicity and Reproduction Studies...................................... 14 

3.3.4 Additional Information from Literature Sources............................................ 15 

3.3.5 Pre-and/or Postnatal Toxicity............................................................................ 15 

3.4 FQPA Safety Factor for Infants and Children .......................................................... 16 

3.5 Hazard Identification and Toxicity Endpoint Selection ................................................ 16 

3.5.1 Acute Reference Dose (aRfD) – All Populations.............................................. 16 

3.5.3 Chronic Reference Dose (cRfD) ........................................................................ 17 

3.5.4 Dermal Absorption........................................................................................... 17 

3.5.5 Occupational Dermal Exposure ........................................................................ 18 

3.5.6 Occupational Inhalation Exposure ................................................................... 19 

3.5.7 Level of Concern for Margin of Exposure ....................................................... 19 

3.5.8 Recommendation for Combining Routes of Exposure for Risk Assessments

............................................................................................................................ 20 

3.5.9 Classification of Carcinogenic Potential........................................................... 20 

3.5.10 Summary of Toxicological Doses and Endpoints for Use in Human Risk 

Assessments....................................................................................................... 20 

3.6 Endocrine disruption.................................................................................................... 22 

4.0 Public Health Data......................................................................................................................... 23 

5.0 Exposure Characterization/Assessment ...................................................................................... 23 

6.0 Aggregate Risk Assessment and Risk Characterization............................................................ 23 

7.0 Cumulative Risk Characterization Assessment.......................................................................... 23 

8.0 Occupational Exposure and Risk................................................................................................. 23 

8.1 Handlers.............................................................................................................................. 24 

8.1.1. Data and Assumptions for Handler Exposure Scenarios................................ 24 

8.1.2. Exposure and Risk............................................................................................. 25 

8.2 Postapplication.................................................................................................................... 27 

8.2.1. Exposure and Risk............................................................................................. 28 

8.3 Restricted Entry Interval.................................................................................................. 30 

9.0 Data Needs and Label Recommendations................................................................................... 31 
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9.1 Occupational Exposure ..................................................................................................... 31 

9.2 Toxicology...................................................................................................................... 31 

A.1 Toxicology Data Requirements.................................................................................................... 33 

A.2 Toxicity Profiles............................................................................................................................. 34

A.3 Executive Summaries .................................................................................................................... 41 
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1.0 Executive Summary

Nichino America, INC, has submitted a request for a Section 3 registration for a proposed use of a new 

active ingredient insecticide. Tolfenpyrad shows broad insecticidal activity against target pests 

through the egg, larval, nymph, and adult stages. The proposed use is for the control of thrips, aphids 

and scales on ornamental plants grown in greenhouses. There are no food or residential uses currently 

proposed for tolfenpyrad; however, food uses are anticipated in the future. The proposed use pattern 

will not likely result in residues in drinking water. 

The end-use product, Tolfenpyrad 15EC Insecticide is formulated as an emulsifiable concentrate (EC) 

and contains 15% of the active ingredient, tolfenpyrad. It is applied by backpack sprayer, high and 

low pressure handwand. The total maximum single application rate (AR) is 0.003 lb ai/gallon of 

water. The application rates on crops with a consecutive application schedule range from 0.003 – 0.006 

lb ai per gallon, per crop cycle, or growing season. In addition, 2 separate spray volumes are specified 

on the label, resulting in a range of application rates of 0.68 to 1.36 lb ai/A. Based on the number of 

seasonal applications (2 applications per crop cycle, with a minimum 10-day re-treatment interval) 

indicated on product labels and information provided by the registrant, non-dietary exposures are 

expected to be of short-, intermediate-, and long term durations for occupational handlers. Dermal 

short-, intermediate-, and long-term postapplication exposures are expected for workers conducting 

postapplication activities in greenhouses. 

Hazard Characterization

A variety of toxic effects were noted in the toxicology database for tolfenpyrad. However, the most 

consistent finding across species and studies was effects on body weight and body weight gain. 

Decreases in body weight and/or body weight gain were observed in adults of all species (rat, mice, 

rabbit, and dog) in the majority of the subchronic oral and dermal toxicity studies, and all chronic 

toxicity studies. The rat is the species most sensitive to body weight changes, with effects observed at 

much lower doses than in other species. The body weight changes observed in other species were 

similar in magnitude to those in rats, but were observed at higher doses. 

The body weight changes observed in the database were most often seen in the presence of decreased 

food consumption and in some studies, additional toxicity including liver/kidney effects and clinical 

signs. Moribundity and/or mortality were also noted in at least one study in all species. However, this 

was observed in the presence of body weight changes and mainly observed at the highest dose tested 

(HDT). 

Based on the proposed nonfood use pattern for tolfenpyrad, FQPA considerations do not apply. 

However, since food uses are anticipated in the future, FQPA hazard considerations are discussed in 

detail in the hazard section. Based on the toxicology database, HED recommends that the 10X FQPA 

safety factor for the protection of infants and children, be reduced to 1X. 

Tolfenpyrad is classified as “not likely to be carcinogenic to humans.” 

For purpose of the current risk assessment, endpoints were selected for occupational short- and 

intermediate- inhalation exposure and short-, intermediate-, and long-term dermal exposures. For 
Page 5 of 71 

dermal exposures, a route-specific 21-day dermal toxicity study in rats was used for endpoint selection. 

However, an extra 3x uncertainty factor (subchronic to chronic) was applied to long-term dermal risk 

assessments since a short-term dermal study was used to assess long-term dermal exposure. 

For short-and intermediate-term inhalation exposures, a 4-week inhalation study was used for endpoint 

selection. No toxic effects were observed up to the NOAEL of 10 mg/m3 (EPA calculated dose = 2.6 

mg/kg/day) and the LOAEL was not determined. However, the applicant noted that mortality was 

observed in a range-finding study at 26 mg/m3 (6.8 mg/kg/day). HED used the NOAEL of 2.6 

mg/kg/day from the 4-week inhalation study for risk assessment; however, the range-finding study 

should be submitted to the Agency for review as a condition of registration. 

For short-, and intermediate-term dermal and inhalation assessments, a combined uncertainty factor 

(UF) of 100 served as the basis for the level of concern (LOC) for occupational risk, or margins of 

exposure (MOEs). For the long-term dermal assessment, a combined uncertainty factor (UF) of 300 

served as the basis for the level of concern (LOC). Therefore, for short-, and intermediate term dermal 

and inhalation risk assessments, MOEs greater than 100 are not of concern. For long-term dermal risk 

assessments, MOEs greater than 300 are not of concern. 

Occupational Handlers Exposure

Data from the Pesticide Handlers Exposure Database (PHED) Version 1.1 were used to assess handler 

exposures (HED Science Advisory Council for Exposure (ExpoSAC), SOP No. 7, January 1999). 

A summary of the risks for occupational handlers is included in Table 4. The maximum application 

rate for each exposure scenario was assessed (i.e., 0.003 lb ai/gal). All handler short- and 

intermediate-term scenarios resulted in MOEs greater than the level of concern (MOEs > 100) with 

risk mitigation (e.g., chemical-resistant gloves). Long-term handler risks were also not of concern 

(MOEs > 300). HED recommends all handlers wear a long-sleeved shirt, long pants, socks, 

chemical-resistant gloves, and footwear as stated in the proposed label. 

Occupational Postapplication Exposure

Dermal 

HED used default assumptions with respect to dissipation on ornamental plants, standard TCs for 

various postapplication activities, and “day 0” foliar residue values (i.e., residues after initial 

treatment). The two spray volumes specified on the label were used to determine the application rate 

on a per acre basis, in order to determine the potential exposure from contacting treated foliage; these 

per acre application rates were 0.68-1.36 lb ai/A. Short-term exposure and risk calculations were 

considered representative/protective of intermediate-term exposure and risk. Long-term exposure and 

risk were also calculated. 

The short- and intermediate-term postapplication risks for ornamental crops were not of concern. 

Long-term postapplication MOEs are not of concern for low-medium contact activities (i.e., pruning, 

tying, hand pinching, and nursery activities). For long-term postapplication high contact activities (i.e., 

cutting flowers), a REI of 4 days would be needed to reach the target MOE of 300 at the maximum 

spray volume/A (AR=1.36 lb ai/A). However, it should be noted that long-term (≥ 6 months-1 year) 
Page 6 of 71 

dermal postapplication exposure was estimated assuming the same residue calculated on day of initial 

treatment. HED believes the residue available for exposure after 6 months or longer is likely to be 

lower than the residue value estimated on day of initial treatment. Considering the nature of the 

residues used for risk assessment, the MOE = 210 (on day 0) for high contact postapplication activities 

(AR=1.36 lb ai/A) is recognized as a conservative risk estimate. Submission of a chemical-specific 

DFR study for greenhouses is recommended to refine the residue values and reduce this uncertainty for 

high contact scenarios. 

 

Inhalation 

The Worker Protection Standard (WPS) for Agricultural Pesticides contains requirements for 

protecting workers from inhalation exposures during and after greenhouse applications through the use 

of ventilation requirements. Tolfenpyrad has a vapor pressure of 3.0 x 10-8 mm Hg. Although there is 

potential for postapplication inhalation exposure resulting from the use of tolfenpyrad in greenhouses, 

with proper use of ventilation, tolfenpyrad inhalation exposure is expected to be negligible. Therefore, 

a quantitative postapplication inhalation exposure assessment was not performed. This approach may 

be revisited in the future with potential changes in the Agency’s approach for assessing inhalation 

exposure and risk. 

Restricted Entry Interval

The REI specified on the proposed label is based on the acute toxicity of the tolfenpyrad technical 

material. Based on the acute toxicity profile of tolfenpyrad, the 24 hour REI appearing on the proposed 

label is appropriate for low, medium, and high contact postapplication activities. 

Environmental Justice Considerations

Potential areas of environmental justice concerns, to the extent possible, were considered in this human 

health risk assessment, in accordance with U.S. Executive Order 12898, “Federal Actions to Address 

Environmental Justice in Minority Populations and Low-Income Populations,” 

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 the USDA under the Continuing Survey 

of Food Intakes by Individuals (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. Additionally, OPP is able to assess dietary 

exposure to smaller, specialized subgroups, and exposure assessments are performed when conditions 

or circumstances warrant. Whenever appropriate, nondietary exposures based on home-use of 

pesticide products and associated risks for adult applicators and for toddlers, youths, and adults 

entering or playing on treated areas postapplication are evaluated. Further considerations are currently 

under evaluation as OPP has committed resources and expertise to the development of specialized 

software models and the refinement of current methodologies and policies that consider exposure to 
Page 7 of 71 

bystanders and farm workers as well as lifestyle and traditional dietary patterns among specific 

subgroups. To ensure that this risk assessment is consistent with scientific standards and policies 

under development, HED might refine the risk assessment components for all registered uses in the 

future. 

Review of Human Research

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) and Agricultural Reentry Task Force (ARTF), have been 

determined to require a review of their ethical conduct, have received that review, and have been 

determined to be ethically conducted. 

HED Conclusions/Recommendations 

Risks for occupational handlers who apply Tolfenpyrad 15EC Insecticide on ornamental plants in 

greenhouses are not of concern to HED. Risks from short- and intermediate-term postapplication 

activities are also not of concern to HED. Risks from long-term postapplication activities have been 

assessed in a conservative manner and are detailed above. 

Based on the current risk assessment, HED recommends: 

• All handlers should wear a long-sleeved shirt, long pants, socks, chemical-resistant gloves and 

footwear as stated in the proposed label. 

• The proposed label personal protective equipment (PPE) language should be revised to state the 

use of: “Chemical-resistant gloves made of materials such as barrier laminate or polyvinyl 

chloride.” 

• The default dislodgeable foliar residue (DFR) values and assumptions used in the assessment may 

be under or overestimated. Therefore, submission of a chemical-specific DFR study for 

greenhouses is recommended to reduce this uncertainty, and could potentially result in reduced 

exposure and risk estimates for all scenarios. 

• To determine the exposure duration that needs to be assessed for future registration actions, the 

applicant could provide the Agency with information to characterize the use pattern for the end-use 

product (EP) containing tolfenpyrad. Such information might include specific seasonal 

information about the use to be assessed, major regions on which the product is applied and how 

the product fits with other active ingredients in pest resistance management programs. 

• The Registration Division (RD) should ensure that the appropriate restricted reentry interval (REI) 

is included on the proposed label. 

• Proprietary data from the Agricultural Reentry Task Force (ARTF) have been used in this 

assessment. The chemical review manager (CRM) is encouraged to pursue data compensation in 

the event the registrant is not a member of this respective task force. 

Toxicology 
Page 8 of 71 

• The requirement for the 90-day dermal toxicity study is not waived. As a condition of registration, 

HED recommends Nichino submit the dermal toxicity study with rats dosed up to the limit dose in 

an effort to better characterize long-term dermal exposure. 

• As a condition of registration, the dose range-finding studies mentioned in the 4 week inhalation 

study (MRID 47447728) should be submitted to the Agency. It was stated that in a previously 

conducted study with groups of 3 rats/sex/concentration, mortality was observed after a single 6-

hour exposure to 26 or 79 mg/m3

. In repeated dose studies, similar groups of rats tolerated a 4-day 

exposure at 11 mg/m3 or 5 days at 3.6 mg/m3

2.0 Ingredient Profile 

Tolfenpyrad is a novel pyrazole insecticide proposed for use in the control of thrips, aphids and scales 

on ornamental plants grown in greenhouses. It has been registered in Japan, Dominican Republic, 

Thailand, and Taiwan. In addition to the United States, it is currently under development in Brazil. 

The chemical structure and nomenclature of tolfenpyrad are presented in Table 2.2, and the 

physicochemical properties of the technical grade of tolfenpyrad are presented in Table 2.3. The 

applicant has indicated that the active ingredient will be formulated as a 15% emulsifiable concentrate 

(EC) containing 1.25 lb ai/gal. The proposed use directions and application rates are summarized 

below in Table 2.1. 

2.1 Summary of Proposed End Use Products/Use Patterns

Table 2.1 summarizes the proposed use pattern and formulation specified in the end-use product 

containing tolfenpyrad. Applications of tolfenpyrad 15EC Insecticide are to be made using foliar spray 

equipment. The proposed label has personal protective equipment (PPE) recommendations which 

include: applicators and other handlers must wear long-sleeved shirt, long pants, socks, chemicalresistant gloves and footwear. 

Table 2.1. Summary of Proposed Use Patterns and Formulations for Tolfenpyrad.

Formulation Method of 

Application 

Use Sites Application Rate Timing of Application

Tolfenpyrad 15EC 

Insecticide 

- emulsifiable 

concentrate 

(15% a.i.) 

For Commercial use 

EPA Reg #71711-XX 

(1.25 lb ai/gal) 

foliar spray by 

low and high 

pressure 

handwand, 

backpack 

sprayer 

greenhouse-grown 

ornamental plants (ash, yew, 

rose, evening primrose, 

gladiolus, cherry, arrowood, 

marigold, moss rose, new 

guinea impatiens, petunia, 

gerbera, chrysanthemum, 

coleus, poinsettia, 

schefflera, lantana) 

Max single appl. rate 

= 0.00313 lb ai/gal 

(0.68 - 1.36 lb ai/A)‡ 

2 apps per crop cycle (0.006 lbs 

ai/gal); 

24-hour REI; 

10-day interval between apps; 

Apply uniformly. 

Do not apply more than 100 

gallons per 20,000 ft2

 (218 

gal/A) up to 10 gallons per 

1,000 ft2 (436 gal/A). 

 

‡ Lower Spray Volume = 0.68 lb ai/A (at 100 gal/20,000 ft2 = 218 gal/A) 

0.00313 lb ai/gal * 218 gal/A = 0.68 lb ai/A 

Higher Spray Volume = 1.36 lb ai/A (at 10 gal/1000 ft2

 = 436 gal/A) 

0.00313 lb ai/gal * 436 gal/A = 1.36 lb ai/A 

2.2 Structure and Nomenclature 
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Table 2.2. Test Compound Nomenclature.

Chemical Structure 

Empirical Formula C21H22ClN3O2

Common name 

Tolfenpyrad, OMI, OMI-88, Hatchi-Hatchi

Company experimental name N/A 

IUPAC name 4-chloro-3-ethyl-1-methyl-N-[4-(p-tolyloxy)benzyl]pyrazole-5-carboxamide 

CAS name 4-chloro-3-ethyl-1-methyl-N-[[4-(4-methylphenoxy)phenyl]methyl]-1H-pyrazole-5-

carboxamide 

CAS Registry Number 129558-76-5 

End-use product/EP Tolfenpyrad 15EC Insecticide

Chemical Class pyrazole 

Known Impurities of Concern N/A 

2.3 Physical and Chemical Properties 

Table 2.2. Physicochemical Properties for Tolfenpyrad. 

Parameter Value Reference 

Molecular Weight (TGAI) 383.9 MRID 47447704 

Melting point/range (PAI) 85.5-88.5° C MRID 47447705 

pH (TGAI) 5.1 MRID 47447704 

Density (TGAI) 1.25 g/cm3 MRID 47447704 

Water solubility (PAI) 0.061 mg/L MRID 47447705 

Solvent solubility (temperature not 

specified) (TGAI) 

n-heptane 6.92 g/L 

Xylene 218 g/L 

1,2 dichloroethane >250 g/L 

Methanol 50.8 g/L 

n-octanol 43.7 g/L 

Acetone 250 g/L 

Ethyl acetate 250 g/L 

MRID 47447704 

Vapor pressure (PAI) 4 x 10-5 Pa at 25 °C 

(= 3.0 x 10-8 mm Hg) 

MRID 47447705 
Page 10 of 71 

Table 2.2. Physicochemical Properties for Tolfenpyrad. 

Parameter Value Reference 

Dissociation constant, pKa No dissociation constant in the 

environmental pH range 

MRID 47447705 

Partition coefficient, 

log10POW (PAI) 

4.3 MRID 47447705 

PAI= Purified Active Ingredient 

TGAI-Technical Grade Active Ingredient 

3.0 Hazard Characterization/Assessment 

3.1 Hazard and Dose-Response Characterization 

3.1.1 Database Summary 

The toxicology database for tolfenpyrad is complete and the scientific quality of the submitted toxicity 

studies is relatively high. The toxicity profile can be characterized for potential systemic, 

carcinogenic, mutagenic, immunotoxic, developmental, and reproductive effects. Studies available for 

risk assessment included: acute oral, dermal, and inhalation toxicity, primary eye and dermal irritation 

and skin sensitization, subchronic oral toxicity (rat, mouse and dog), 21-day dermal toxicity and 

dermal penetration (rat), 4-week inhalation (rat), acute and subchronic neurotoxicity (rat), chronic dog, 

combined chronic/carcinogenicity (rat) and carcinogenicity (mouse), developmental toxicity (rat and 

rabbit), developmental immunotoxicity (rat), two-generation reproduction (rat), mutagenicity battery, 

and general metabolism. A developmental neurotoxicity (DNT) study was not included, but is not 

warranted at this time. 

3.1.1.1 Mode of action, metabolism, toxicokinetic data 

Tolfenpyrad is a pyrazole insecticide that impairs respiration of target pests through the inhibition of 

complex 1 of the mitochondrial respiratory electron transport chain. This results in very rapid 

insecticidal responses, including cessation of movement and feeding, lack of fecundity and eventual 

death of the pest. 

3.1.2 Toxicological Effects 

A variety of toxic effects were noted in the toxicology database for tolfenpyrad. However, the most 

consistent finding across species and studies was body weight and body weight gain. Decreases in 

body weight and/or body weight gain were observed in adults of all species (rat, mice, rabbit, and dog) 

in the majority of the subchronic oral and dermal toxicity studies, and all chronic toxicity studies. 

The rat is the species most sensitive to body weight changes, with effects observed at much lower 

doses than in other species. In rats, significant decreases in body weight and body weight gain were 

observed in subchronic oral and acute and subchronic neurotoxicity studies. Decreases in body weight 

and body weight gain were also seen in chronic rat studies but at lower doses than observed in the 

other rat studies. However, although seen at lower doses, the body weight decrements noted in the 

chronic study were not as pronounced as seen after subchronic exposure or in the neurotoxicity studies. 

 Decreases in body weight and body weight gain were also observed in reproduction, developmental 
Page 11 of 71 

toxicity, and developmental immunotoxicity studies at doses comparable to the chronic study. 

Significant decreases in body weight gain and food consumption were also seen in a 21-day dermal 

toxicity study but in the absence of any other systemic toxicity. 

Body weight changes observed in other species were similar in magnitude to those in rats, but were 

observed at higher doses. Significant decreases in body weight and body weight gain were seen in 

both mice and dogs after subchronic exposure; these effects were also noted in rabbits in a 

developmental toxicity study. Chronic exposure resulted in body weight and body weight gain 

decreases in mice and dogs at lower doses. The severity of body weight changes increased with dose 

in mice while body weight effects in dogs were seen only at the highest dose tested (HDT). 

The body weight changes observed in the database were most often seen in the presence of decreased 

food consumption and in some studies, additional toxicity including liver/kidney effects and clinical 

signs. Increased liver and kidney weights, liver and kidney hypertrophy, hyaline droplets in the 

kidney, and color change in the kidney were seen after subchronic exposure in rats. Chronic exposure 

resulted in similar effects along with color changes in the liver and liver histopathology at slightly 

lower doses than in the subchronic studies. Other effects noted in rats were effects on the harderian 

gland and lymph nodes. In dogs, both liver and kidney histopathology, along with testicular atrophy 

and clinical signs (emaciation, decreased movement, and staggering gait) were seen in short-term 

studies. Long-term exposure resulted in histopathology in the liver only, along with increased liver 

enzymes. No treatment-related effects were noted in the liver or kidney in mice. However, rough 

coats, hunched posture, ataxia, and hypoactivity were seen in subchronic studies. Missing ears and ear 

lesions (scabs, sores, ulceration, and inflammation) were seen in a chronic toxicity study. The ear 

lesions observed were likely self inflicted since the mice in the study were individually caged. No 

explanation was given to why the lesions occurred and the toxicological significance of this finding is 

unclear. 

 

Moribundity and/or mortality were noted in at least one study in all species and mainly observed at the 

HDT. Moribundity and mortality were noted in two dams in a rat reproduction study, and mortality 

was noted in one dam in a rabbit developmental toxicity study. In mice and dogs, mortality was 

observed in both subchronic and chronic toxicity studies. In all cases, effects were observed in the 

presence of body weight changes. 

Several adverse effects were noted in young animals in developmental toxicity and reproduction 

studies; however, the effects were observed in the presence of significant maternal toxicity (significant 

body weight changes and/or moribundity/mortality). No evidence of increased quantitative or 

qualitative susceptibility was observed in the studies. In a developmental immunotoxicity study in 

rats, a potential increase in qualitative susceptibility was seen. In the study, decreased survival, body 

weight, body weight gain, increased blackish abdominal cavity, and dark green abnormal intestinal 

contents were observed in offspring animals at 3 mg/kg/day. At the same dose, decreased body weight 

(up to 10%), body weight gain (up to 36%) and food consumption were seen in maternal animals. 

There was no evidence of immunotoxicity observed in the study. 

No evidence of neurotoxicity was observed in acute and subchronic neurotoxicity studies for 

tolfenpyrad. Although hunched posture, ataxia, and hypoactivity were seen in mice in a 28 day 

toxicity study, these effects were not seen in a 90 day study or after chronic exposure. In dogs, 
Page 12 of 71 

decreased spontaneous movement, and staggering gait were observed after 13 weeks. In rats, 

decreased motor activity and prone position (lying face down) prior to death were noted in a 

reproduction study. Overall, the effects noted in the database were agonal effects mainly seen at high 

doses, not associated with neuropathology, and not noted in long-term studies. The effects observed 

are consistent with the mode of action for tolfenpyrad (mitochondrial inhibitor) and are not considered 

evidence of neurotoxicity. 

In a rat dermal toxicity study (21 days), decreased body weight gain and food consumption were 

observed in the absence of any other systemic toxicity. A rat dermal penetration study is also available 

which resulted in a dermal absorption factor (DAF) of 13%. 

No evidence of carcinogenicity was observed in cancer studies with mice and rats. Therefore, in 

accordance with EPA’s Final Guidelines for Carcinogen Risk Assessment (March, 2005), tolfenpyrad 

is classified as “not likely to be carcinogenic to humans.”

3.1.3 Dose-response 

Based on the proposed nonfood use pattern for tolfenpyrad, FQPA considerations do not apply. 

However, since food uses are anticipated in the future, endpoints were selected for dietary exposures. 

For acute dietary exposure, an acute reference dose (aRfD) of 0.1 mg/kg/day was selected for 

assessment of the general population, based on a NOAEL of 10 mg/kg/day in an acute neurotoxicity 

study in rats. At the LOAEL of 20 mg/kg/day, decreased body weight, body weight gain, and food 

consumption were seen. The effects were observed after a single dose exposure in a dietary study and 

are considered appropriate for acute dietary exposure. No separate endpoint was identified for acute 

dietary exposure for females 13-49 years of age. 

For chronic dietary exposure, a chronic reference dose (cRfD) of 0.006 mg/kg/day was selected for 

assessment of all populations, based on a NOAEL of 0.6 mg/kg/day from a combined 

chronic/carcinogenicity study in rats. Decreased body weight, body weight gain and food 

consumption, changes in the harderian glands (found in the eye), histopathological changes in liver, 

kidney and lymph nodes were observed at the LOAEL of 1.5 mg/kg/day. Chronic mouse and dog 

studies were also considered for chronic dietary exposure; however, the chronic rat study provided the 

most sensitive endpoint for chronic dietary risk assessment. 

For the purpose of the current risk assessment, endpoints were selected for occupational short- and 

intermediate-term inhalation exposure and short-, intermediate-, and long-term dermal exposure. For 

dermal exposures, a route-specific 21-day dermal toxicity study in rats was used for endpoint selection. 

However, an extra 3x uncertainty factor (subchronic to chronic) was applied to long-term dermal risk 

assessments since a short-term dermal study was used to assess long-term dermal exposure. 

For short-and intermediate-term inhalation exposures, a 4-week inhalation study was used for endpoint 

selection. No toxic effects were observed up to the NOAEL of 10 mg/m3 (EPA calculated dose = 2.6 

mg/kg/day) and the LOAEL was not determined. However, the applicant noted that mortality was 

observed in a range-finding study at 26 mg/m3

 (6.8 mg/kg/day). HED used the NOAEL of 2.6 

mg/kg/day from the 4-week inhalation study for risk assessment; however, the range-finding study 

should be submitted to the Agency for review. 
Page 13 of 71 

3.1.4 FQPA 

Based on the proposed nonfood use pattern for tolfenpyrad, FQPA considerations do not apply. 

However, since food uses are anticipated in the future, FQPA hazard considerations were addressed in 

HED’s evaluation of the submitted data and are discussed in section 3.3. 

3.2 Absorption, Distribution, Metabolism, Excretion (ADME) 

Several metabolism studies were conducted with radiolabeled tolfenpyrad in rats (MRIDs 47447837, 

47447836, 47447834). Overall, absorption, excretion, and metabolism of the test compound was 

rapid. Following a single oral dose, radioactivity was detected in the blood 0.5 h after administration. 

Blood concentrations of radioactivity plateaued after the third administration in the multiple dose 

study, suggesting there was no bioaccumulation following repeated administration. The highest 

concentrations of radioactivity were observed in the liver, kidney, brown fat and heart, with a 

redistribution that also included white fat, bone marrow and skin over time. Radioactivity 

concentrations dropped substantially from 12 to 168 h post-dosing. 

Tolfenpyrad was excreted in a rapid and dose-dependent manner following a single exposure. After a 

1 mg/kg single dose, approximately 67% of the administered dose (AD) was eliminated during the first 

24 h post-dosing, increasing to 85% AD at 48 h. In the 20 mg/kg single dose groups, excretion was 

somewhat slower, with up to 30% AD eliminated during the first 24 h post-dosing, increasing to up to 

70% AD at 48 h. Feces were the predominant route of excretion, accounting for up to 93% AD; 

residues in urine, expired air, and cage wash were negligible. Administration of repeated daily doses 

had no effect on the route of excretion or the extent of recovery. Tolfenpyrad was metabolized by 

oxidation to form a number of hydroxylated metabolites (Pt-CA, OH-PT and OH-PT-CA), followed by 

conjugation (glucuronide, sulfate, asparagines or taurine). The primary metabolite, PT-CA was found 

in plasma, liver, kidney, and fat (<5%), along with taurine-conjugated and hydroxylated forms, in the 

bile at 4.6-22.3%. Higher levels of PT-CA were found in the feces (9.0-36.2% AD); however, it was 

stated in the study that the additional PT-CA is likely formed by the action of the enterobacteria in the 

gut. Parent was identified in the feces at only at 0.3-14.8% AD, and the amount decreased with time. 

There were no significant differences observed in the blood pharmacokinetic parameters between the 

[PY-14C]- and [TO-14C]-label positions in the single or multiple dose studies. However, in animals 

given multiple doses of pyrazole-labled (14C) tolfenpyrad, blood levels of radioactivity were 

approximately 2- to 3-fold higher in females than in males. Females also had more radioactivity 

remaining in the gastrointestinal tract, and the amount remaining increased with dose. Conversely, 

absorption (defined as radioactivity found in the bile, urine, cage wash, and carcass) was greater in 

males (72.8-77.8% AD) than in females (57.9-69.4% AD). 
Page 14 of 71 

3.3 FQPA Considerations

3.3.1 Adequacy of the Toxicity Database 

The toxicology database for tolfenpyrad is adequate to characterize potential pre- and/or post-natal 

toxicity for assessing risks for infants and children. Acceptable studies for developmental toxicity in 

rats and rabbits, developmental immunotoxicity, 2-generation reproduction in rats, and neurotoxicity 

are available for FQPA assessment. 

3.3.2 Evidence of Neurotoxicity 

The clinical signs observed in the toxicology database are consistent with the mode of action 

(mitochondrial inhibitor) for tolfenpyrad and not considered evidence of neurotoxicity. Hunched 

posture, ataxia, and hypoactivity were seen in mice after 28 days at 104/126 mg/kg/day. These effects 

were not seen in a 90 day study in mice up to 46.2/57.9 mg/kg/day or after chronic exposure in mice 

up to 20.8/27.1 mg/kg/day. In dogs, decreased spontaneous movement, and staggering gait were 

observed after 13 weeks at 30 mg/kg/day. In rats, decreased motor activity and prone position (lying 

face down) prior to death were noted in a reproduction study at 3.0 mg/kg/day. Overall, the effects 

noted in the database were agonal effects, mainly seen at high doses, not associated with 

neuropathology, and not noted in long-term studies. No neurotoxic effects were noted in acute or 

subchronic neurotoxicity studies in rats. 

3.3.3 Developmental Toxicity and Reproduction Studies 

In a developmental toxicity study in rats, decreased body weight gain and food consumption were seen 

at 3 mg/kg/day (LOAEL) in maternal animals, while no effects were seen in fetuses at this dose. At 4.5 

mg/kg/day, decreases in body weight were seen in addition to decreases in body weight gain and food 

consumption. Additionally at 4.5 mg/kg/day (LOAEL), fetal effects included increased incidences of 

14th ribs, decreased fetal body weights, and decreased number of ossified metacarpals. 

In a developmental toxicity study in rabbits, there were no maternal or developmental effects observed 

up to 6 mg/kg/day. However, a single mortality, emaciation, decreased body weights, body weight 

gains, and food consumption were seen in maternal animals in the developmental range-finding study 

at 9 mg/kg/day. Also at 9 mg/kg/day, early resorption and incidences of supernumerary coronary 

orifices, fusion of the ossification centers of the caudal vertebral bodies, 13th ribs, and delayed 

ossification of the manus were seen in fetuses. 

In a developmental immunotoxicity study in rats, decreased body weight, body weight gain and food 

consumption were observed in maternal animals at 3 mg/kg/day. In offspring, decreased survival, 

body weight, body weight gain, increased blackish abdominal cavity, and dark green abnormal 

intestinal contents were seen at 3 mg/kg/day. 

In a 2-generation reproduction study in rats, decreased body weight and body weight gains, decreased 

 motor activity, reddish tears, and prone position prior to death in two dams were seen in parental 

animals at 3.0 mg/kg/day. Additionally, decreased gestation index, increased gestation duration, 

abnormal parturition, and total litter loss were observed in female animals at 3.0 mg/kg/day. In pups, 
Page 15 of 71 

decreased pup viability and body weights, as well as delays in attainment of developmental landmarks 

(eye opening, pinna folding, surface righting reflex) were observed at 3.0 mg/kg/day. 

3.3.4 Additional Information from Literature Sources 

A literature search did not reveal information that would impact the hazard or risk assessment. 

3.3.5 Pre-and/or Postnatal Toxicity

3.3.5.1 Determination of Susceptibility 

No evidence of increased quantitative or qualitative susceptibility was observed in developmental 

toxicity studies in rats or rabbits or a reproduction toxicity study in rats. However, a potential increase 

in qualitative susceptibility was seen in a developmental immunotoxicity study in rats. In the study, 

decreased survival, body weight, body weight gain, increased blackish abdominal cavity, and dark 

green abnormal intestinal contents were seen in offspring animals at 3 mg/kg/day. At the same dose, 

decreased body weight (up to 10%), body weight gain (up to 36%) and food consumption were 

observed in maternal animals. 

3.3.5.2 Degree of Concern Analysis and Residual Uncertainties for Pre- and/or Postnatal 

Susceptibility 

The purposes of the Degree of Concern analyses are to determine the level of concern for the effects 

observed when considered in the context of all available toxicity data, and to identify any residual 

uncertainties after establishing toxicity endpoints and traditional uncertainty factors to be used in the 

risk assessment. If residual uncertainties are identified, then HED determines whether these residual 

uncertainties can be addressed by an FQPA safety factor and, if so, the size of the factor needed. 

Although there is possibly increased qualitative susceptibility in the young in the developmental 

immunotoxicity study (DIT) in rats, there is low concern and there are no residual uncertainties 

regarding increased quantitative or qualitative pre- and/or postnatal susceptibility. In the DIT at 3 

mg/kg/day, significant decreases in body weight and body weight gain were observed in the maternal 

animals while decreased survival was seen in the offspring. The severity in pup effects compared to 

maternal suggests qualitative susceptibility. However, in developmental and reproduction studies in 

rats of the same strain and at the same dose, maternal mortality was observed in concert with less 

severe effects in offspring animals. When the DIT is considered along with the developmental and 

reproduction studies, it is likely that 3 mg/kg/day results in moribundity/mortality in maternal animals. 

Therefore, HED does not consider the isolated incident in the DIT a true indicator of qualitative 

susceptibility. Additionally, there is no evidence of quantitative susceptibility (effects occurred in the 

presence of maternal toxicity) in the study, a clear NOAEL was identified for the offspring effects 

seen, and no evidence of increased quantitative or qualitative susceptibility was seen in the 

developmental (rat and rabbit) or reproduction studies. Furthermore, the risk assessments are based on 

the most sensitive endpoints, and the NOAELs selected are considered protective of potential 

developmental and offspring effects. Considering the overall toxicity profile and the doses and 

endpoints selected for risk assessment for tolfenpyrad, the degree of concern for the effects observed in 

the DIT study is low. Therefore, HED recommends the FQPA factor be reduced to 1X (see 3.4). 
Page 16 of 71 

3.3.6 Recommendation for not requiring a Developmental Neurotoxicity Study 

Clinical signs consistent with the mode of action (mitochondrial inhibitor) for tolfenpyrad were 

observed in the toxicology database (sec. 3.3.2.). The effects observed were mainly seen at high doses, 

not associated with neuropathology, and not noted in long-term studies. Additionally, no neurotoxic 

effects were observed in acute or subchronic neurotoxicity studies in rats and there are no residual 

concerns for increased quantitative or qualitative susceptibility. Therefore, based on the overall 

toxicity database and the weight of the evidence, a developmental neurotoxicity study is not warranted 

at this time. 

3.4 FQPA Safety Factor for Infants and Children 

As mentioned previously, the proposed nonfood use pattern for tolfenpyrad does not require FQPA 

considerations. However, food uses are anticipated in the future so FQPA hazard considerations were 

addressed in HED’s evaluation. HED recommends that the 10X FQPA safety factor for the protection 

of infants and children, be reduced to 1X based on hazard considerations alone, since there are no 

potential food or residential exposures expected for the current actions. Once the food uses are 

submitted, HED will include the exposure assessment in the final conclusion regarding the FQPA 

safety factor. The decision to reduce the factor to 1X is based on the following hazard considerations: 

 

• The toxicological database is complete for the purpose of FQPA assessment. 

• There are no concerns for increased quantitative and qualitative susceptibility or residual 

uncertainties for pre-and postnatal toxicity. Although there is possibly increased qualitative 

susceptibility in the young in the developmental immunotoxicity study (DIT) in rats, there is 

low concern as discussed previously in Section 3.3.5.2 

• There is no concern for neurotoxicity, and a developmental neurotoxicity study (DNT) is not 

required. 

3.5 Hazard Identification and Toxicity Endpoint Selection 

3.5.1 Acute Reference Dose (aRfD) – All Populations 

Study Selected: Acute Neurotoxicity Study in Rats 

MRID No: 47447831 

Dose and Endpoint for Risk Assessment: NOAEL= 10 mg/kg/day, based on decreased body weight, 

body weight gain and food consumption observed at the LOAEL of 20 mg/kg/day. 

Uncertainty Factor: 100x (10x interspecies extrapolation, 10x intraspecies variability) 

Acute RfD = 

100 ( )

10 / /

UF

mg kg day = 0.1 mg/kg/day
Page 17 of 71 

Comments about Study/Endpoint/Uncertainty Factors: 

Although body weight changes are not usually the result of a single dose exposure, significant 

decreases in body weight (6-12%) and decreases in bodyweight gain (26%) were observed after a 

single dose exposure in a dietary study and are appropriate for acute dietary exposure. 

No separate endpoint was identified for acute dietary exposure for females 13-49 years of age. 

Resorptions seen in a range-finding developmental toxicity study in rabbits were considered for 

endpoint selection. However, the resorptions were seen in the presence of significant maternal effects 

(emaciation, body weight changes, and mortality) and are considered secondary to maternal toxicity 

and not a result of a single exposure. Therefore, the endpoint is not applicable to acute dietary risk 

assessment. 

3.5.2 Chronic Reference Dose (cRfD) 

Study Selected: Combined Chronic Toxicity/Carcinogenicity Study in Rats 

MRID No: 47463704 

Dose and Endpoint for Risk Assessment: NOAEL= 0.6 mg/kg/day, based on decreased body weight, 

body weight gain and food consumption of females, changes in the harderian glands (found in the eye) 

of males, histopathological changes in liver, kidney and lymph nodes in females, and histopathological 

changes in the kidney of males, observed at the LOAEL of 1.5 mg/kg/day. 

Uncertainty Factor: 100x (10x interspecies extrapolation, 10x intraspecies variability) 

Chronic RfD = 

100 ( )

0.6 / /

UF

mg kg day = 0.006mg/kg/day

Comments about Study/Endpoint/Uncertainty Factors: 

The study is appropriate for chronic dietary exposure due to the route (oral) and long-term duration of 

dosing. In addition, the dose selected is the lowest NOAEL in the toxicity database, and will therefore 

be protective of other observed toxic effects. Chronic mouse and dog studies were also considered for 

chronic dietary exposure; however, the chronic rat study provided the most sensitive endpoint for 

chronic dietary risk assessment. 

3.5.3 Dermal Absorption 

A dermal penetration study in rats is available for tolfenpyrad. In the study, tolfenpyrad was applied to 

the shaved skin of Sprague Dawley rats. Four males/dose/time points were tested with termination 

times of 0.5, 1, 2, 4, 10, or 24 hours post-administration. Analytical recoveries were 89-96 % AD. 

Very little of the applied dose was actually absorbed at any concentration, ranging from approximately 

6-13% absorbed at 24 hours post-dosing. Absorption continued throughout the 24 hour post-dosing 

period. 

 

Based on HED policy, the most appropriate dermal absorption value for risk assessment is based on 

the results from the mid-dose group (1 g/L; actual dose 8.4 μg/cm2

 skin), as percent dermal absorption 

was greatest at this dose level. Since absorption continued throughout a 24 hour post-dosing period, 

the dermal absorption factor (DAF) of 13% was selected based on measurements at this time point. 
Page 18 of 71 

However, a DAF was not used in the current risk assessment since the dermal point of departures are 

based on a route-specific study (21-day dermal toxicity). 

 

3.5.5 Occupational Dermal Exposure 

Short- and Intermediate-Term Dermal Exposure (up to 6 months of exposure) 

Study Selected: 21-day dermal toxicity in rats

MRID No: 47447806 

Dose and Endpoint for Risk Assessment: NOAEL= 200 mg/kg/day

Uncertainty Factor: 100x (10x interspecies extrapolation, 10x intraspecies variability) 

Comments about Study/Endpoint/Uncertainty Factors: 

Although decreased body weight gain and food consumption were noted at ≥ 50 mg/kg/day, these 

effects were not considered adverse and thus the highest dose tested (HDT) of 200 mg/kg/day was 

considered to be a NOAEL. There was no dose response relationship between tolfenpyrad exposure 

and decreased body weight gain and food consumption in the study, since decreases were similar at 

both 50 and 200 mg/kg/day. HED believes the lack of a dose response may be the result of saturation 

at doses ≥ 50 mg/kg/day. Since the dermal toxicity study did not test up to limit dose (1000 

mg/kg/day), the 200 mg/kg/day was used as the NOAEL for dermal risk assessments. The study is 

route-specific and the duration is appropriate for short-, and intermediate-term dermal exposure. 

The developmental toxicity studies (rats and rabbits), the developmental immunotoxicity study in rats 

and the reproduction study in rats were all considered for short-and intermediate-term dermal risk 

assessment. However, since there is no evidence of increased quantitative susceptibility between the 

young and the adult (i.e., developmental/offspring toxicity occurred at the same dose level as adult 

toxicity) the Agency concluded that selecting points of departure from route-specific studies that are 

protective for adults would also be protective for developmental/offspring effects. As a result, the 

dermal toxicity study is protective of potential offspring effects since it adequately measured systemic 

toxicity in maternal animals. 

Long-Term Dermal Exposure (> 6 months of exposure) 

Study Selected: 21-day dermal toxicity in rats

MRID No: 47447806 

Dose and Endpoint for Risk Assessment: NOAEL= 200 mg/kg/day

Uncertainty Factor: 100x (10x interspecies extrapolation, 10x intraspecies variability) 

Uncertainty Factor: 300x (10x interspecies extrapolation, 10x intraspecies variability, 3x subchronic 

to chronic) 

Comments about Study/Endpoint/Uncertainty Factors: 

The available subchronic (21-day) route specific dermal study is not of an appropriate duration for 

long-term exposure. Therefore, although the 21-day dermal study was used for long-term dermal risk 

assessment, an extra uncertainty factor of 3x was applied for subchronic to chronic extrapolation. The 

3x uncertainty factor is a data derived factor obtained by comparing the LOAELs from the available 
Page 19 of 71 

rat subchronic toxicity studies and chronic toxicity studies. In the 90 day, developmental, and 

reproduction toxicity studies the LOAELs range from approximately 3 to 5 mg/kg/day; the LOAEL in 

the chronic toxicity study is approximately 2 mg/kg/day. Since there is a 2-3x difference between the 

subchronic and chronic toxicity studies, the extra UF of 3x is considered protective of potential effects 

when extrapolating from subchronic to chronic exposure. 

The combined chronic/ carcinogenicity study was also considered for risk assessment. However, the 

route-specific study was considered more appropriate and the extra factor applied is considered 

protective of potential long-term effects. 

3.5.6 Occupational Inhalation Exposure 

Short- and Intermediate-Term Inhalation Exposure (up to 6 months of exposure) 

Study Selected: 4 week inhalation toxicity study in rats

MRID No: 47447728 

Dose and Endpoint for Risk Assessment: NOAEL= 10 mg/m3

 (2.6 mg/kg/day). No treatmentrelated effects were observed in the 4 week inhalation study. Mortality was observed in a rangefinding study at 26 mg/m3 (6.8 mg/kg/day day). 

Uncertainty Factor: 100x (10x interspecies extrapolation, 10x intraspecies variability)

Comments about Study/Endpoint/Uncertainty Factors: 

No toxic effects were observed up to 10 mg/m3 (EPA calculated dose = 2.6 mg/kg/day) in the main 

study; however, mortality was observed in a range-finding study at 26 mg/m3 (6.8 mg/kg/day), as 

stated in the inhalation study report. However, the detailed results of the range-finding study were not 

included, and should be submitted for review as a condition of registration. The developmental 

toxicity studies (rats and rabbits), the developmental immunotoxicity study in rats and the reproduction 

study in rats were all considered for short-and intermediate-term inhalation risk assessment. However, 

the inhalation study was selected because it is a route specific study and considered more appropriate 

for inhalation risk assessment than the oral studies. There is no evidence of increased quantitative 

susceptibility between the young and the adult (i.e., developmental/offspring toxicity occurred at the 

same dose level as adult toxicity) and the Agency concluded that selecting points of departure from 

route-specific studies that are protective for adults would also be protective for 

developmental/offspring effects. Therefore, the inhalation study it is protective of potential offspring 

effects since it adequately measured systemic toxicity in adult animals.

3.5.7 Level of Concern for Margin of Exposure 

The level of concern (LOC) for short-, and intermediate-term occupational dermal and inhalation risk 

assessment is 100. This includes conventional uncertainty factors of 10x for interspecies extrapolation 

and 10x for intraspecies variability. The LOC for long-term occupational dermal risk assessment is 

300. This includes the conventional uncertainty factors and an extra 3x uncertainty factor (subchronic 

to chronic) for the use of a short-term study to assess long-term exposure. The FQPA factor has been 

reduced to 1x and no other factors are warranted. 
Page 20 of 71 

Table 3.5.7 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 100 100 300

Inhalation 100 100 N/A

3.5.8 Recommendation for Combining Routes of Exposure for Risk Assessments

When there are potential occupational and residential exposures to a pesticide, the risk assessment 

must address exposures from three major sources: oral, dermal and inhalation exposures and determine 

whether the individual exposures can be combined if they have the same toxicological effects. For 

purposes of this risk assessment, there are no routes of exposure to combine. 

3.5.9 Classification of Carcinogenic Potential 

There was no evidence of carcinogenicity in cancer studies with mice and rats. Therefore, in 

accordance with EPA’s Final Guidelines for Carcinogen Risk Assessment (March, 2005), tolfenpyrad 

is classified as “not likely to be carcinogenic to humans.” 

3.5.10 Summary of Toxicological Doses and Endpoints for Use in Human Risk Assessments 

3.5.10a Note: There are currently no food or residential uses associated with Tolfenpyrad; 

however, endpoints have been chosen in anticipation of any future food or residential 

uses. 

Table 3.5.10a Summary of Toxicological Doses and Endpoints for Tolfenpyrad for Use in Dietary and NonOccupational Human Health Risk Assessments. 

Exposure/ 

Scenario 

Point of 

Departure 

Uncertainty/

FQPA Safety 

Factors 

RfD, PAD, 

Level of 

Concern for 

Risk 

Assessment 

Study and Toxicological Effects 

Acute Dietary 

(General 

Population, 

including Infants 

and Children) 

NOAEL= 10 

mg/kg/day 

UFA= 10 x 

UFH=10 x 

FQPA SF=1x 

Acute RfD = 0.1 

 mg/kg/day 

aPAD = 0.1 

mg/kg/day 

LOAEL=20 mg/kg/day from an acute 

neurotoxicity study in rats, based on 

decreased body weight body weight gain and 

food consumption. 

Chronic Dietary 

(All Populations) 

NOAEL= 0.6 

mg/kg/day 

UFA= 10 x 

UFH=10 x 

FQPA SF=1x 

Chronic RfD = 

0.006 

mg/kg/day 

cPAD = 0.006 

mg/kg/day 

 LOAEL = 1.5 mg/kg/day from a combined 

chronic/carcinogenicity in rats, based on 

decreased body weight, body weight gain, 

and food consumption of females, gross 

changes in the Harderian glands of males, 

and histopathological changes in the liver, 

kidney and mesenteric lymph nodes of 

females and the kidney of males. 
Page 21 of 71 

Table 3.5.10a Summary of Toxicological Doses and Endpoints for Tolfenpyrad for Use in Dietary and NonOccupational Human Health Risk Assessments. 

Exposure/ 

Scenario 

Point of 

Departure 

Uncertainty/

FQPA Safety 

Factors 

RfD, PAD, 

Level of 

Concern for 

Risk 

Assessment 

Study and Toxicological Effects 

Dermal 

Short-Term 

And 

Intermediate-Term 

(Up to 6 months of 

exposure) 

 

NOAEL= 200 

mg/kg/day 

UFA= 10 x 

UFH=10 x 

FQPA SF=1x 

Residential LOC 

for MOE = 100 

No LOAEL determined in 21-day dermal 

study in rats; not tested up to the limit dose of 

1000 mg/kg/day. 

Only minimal changes in body weight gain 

(no absolute body weight changes) and food 

consumption were observed in the study and 

not considered adverse. 

Dermal Long-Term 

(>6 months) 

NOAEL= 200 

mg/kg/day 

UFA= 10 x 

UFH=10 x 

UFS=3 x 

FQPA SF=1x 

Residential LOC 

for MOE = 300 

No LOAEL determined in 21-day dermal 

study in rats; not tested up to the limit dose of 

1000 mg/kg/day. 

Only minimal changes in body weight gain 

(no absolute body weight changes) and food 

consumption were observed in the study and 

not considered adverse. 

Inhalation ShortTerm 

And 

Intermediate-Term 

(Up to 6 months of 

Exposure) 

NOAEL= 2.6 

mg/kg/day 

IAF = 100% 

UFA= 10 x 

UFH=10 x 

FQPA SF=1x 

Residential LOC 

for MOE = 100 

No LOAEL determined 

4 week inhalation study in rats. 

No effects observed up to 2.6 mg/kg/day in 

main study. Mortality observed at 6.8 

mg/kg/day in a range-finding study. 

Cancer (oral, 

dermal, inhalation) 

Classification: “Not likely to be Carcinogenic to Humans” based on the absence of significant tumor 

increases in two adequate rodent carcinogenicity studies. 

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). UFS = use of a short-term study for long-term risk assessment. 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. DAF = dermal absorption factor. IAF = inhalation absorption factor. 
Page 22 of 71 

3.5.10b The following endpoints were chosen for the current risk assessment and apply to the 

proposed nonfood use on ornamentals. 

Table 3.5.10b Summary of Toxicological Doses and Endpoints for Tolfenpyrad 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-Term 

And 

IntermediateTerm 

(Up to 6 months 

of Exposure) 

NOAEL= 

200 

mg/kg/day 

UFA= 10 x 

UFH=10 x 

Occupational LOC 

for MOE = 100 

No LOAEL determined in 21-day dermal 

study in rats; not tested up to the limit dose of 

1000 mg/kg/day. 

Only minimal changes in body weight gain 

(no body weight changes) and food 

consumption were observed in the study and 

not considered adverse. 

Dermal LongTerm (>6 

months) 

NOAEL= 

200 

mg/kg/day 

UFA= 10 x 

UFH=10 x 

UFS=3 x Occupational LOC 

for MOE = 300 

No LOAEL determined in 21-day dermal 

study in rats; not tested up to the limit dose of 

1000 mg/kg/day. 

Only minimal changes in body weight gain 

(no body weight changes) and food 

consumption were observed in the study and 

not considered adverse. 

Inhalation ShortTerm 

And 

IntermediateTerm 

(Up to 6 months 

of Exposure) 

NOAEL= 2.6 

mg/kg/day 

IAF = 100% 

UFA= 10 x 

UFH=10 x Occupational LOC 

for MOE = 100 

No LOAEL determined 

4 week inhalation study in rats. No effects 

observed up to 2.6 mg/kg/day in main study. 

Mortality observed at 6.8 mg/kg/day in a 

range-finding study. 

Cancer (oral, 

dermal, 

inhalation) 

Classification: “Not likely to be Carcinogenic to Humans” based on the absence of significant tumor 

increases in two adequate rodent carcinogenicity studies. 

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). UFS = use of a short-term study for long-term risk assessment. MOE = margin of exposure. LOC 

= level of concern. 

3.6 Endocrine disruption 

As required under FFDCA section 408(p), EPA has developed the Endocrine Disruptor Screening 

Program (EDSP) to determine whether certain substances (including pesticide active and other 

ingredients) may have an effect in humans or wildlife similar to an effect produced by a “naturally 

occurring estrogen, or other such endocrine effects as the Administrator may designate.” The EDSP 

employs a two-tiered approach to making the statutorily required determinations. Tier 1 consists of a 

battery of 11 screening assays to identify the potential of a chemical substance to interact with the 

estrogen, androgen, or thyroid (E, A, or T) hormonal systems. Chemicals that go through Tier 1 

screening and are found to have the potential to interact with E, A, or T hormonal systems will proceed 
Page 23 of 71 

to the next stage of the EDSP where EPA will determine which, if any, of the Tier 2 tests are necessary 

based on the available data. Tier 2 testing is designed to identify any adverse endocrine related effects 

caused by the substance, and establish a dose-response relationship between the dose and the E, A, or 

T effect. 

Between October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 

chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. This list of 

chemicals was selected based on the potential for human exposure through pathways such as food and 

water, residential activity, and certain post-application agricultural scenarios. This list should not be 

construed as a list of known or likely endocrine disruptors. 

Tolfenpyrad is not among the group of 58 pesticide active ingredients on the initial list to be screened 

under the EDSP. Under FFDCA sec. 408(p) the Agency must screen all pesticide chemicals. 

Accordingly, EPA anticipates issuing future EDSP test orders/data call-ins for all pesticide active 

ingredients. 

For further information on the status of the EDSP, the policies and procedures, the list of 67 chemicals, 

the test guidelines and the Tier 1 screening battery, please visit our website: 

http://www.epa.gov/endo/. 

4.0 Public Health Data 

No public health/epidemiology data were used in developing this risk assessment. 

5.0 Exposure Characterization/Assessment 

Since this request is for a non-food use (greenhouse ornamentals), dietary, residential and drinking 

water exposure are not anticipated; therefore, assessments are not required for purposes of this risk 

assessment. 

6.0 Aggregate Risk Assessment and Risk Characterization 

Aggregate risk assessments are not needed at this time. 

7.0 Cumulative Risk Characterization Assessment

Unlike other pesticides for which EPA has followed a cumulative risk approach based on a common 

mechanism of toxicity, EPA has not made a common mechanism of toxicity finding as to tolfenpyrad 

and any other substances and tolfenpyrad does not appear to produce a toxic metabolite produced by 

other substances. For the purposes of this action, therefore, EPA has not assumed that tolfenpyrad has 

a common mechanism of toxicity with other substances. For information regarding EPA’s efforts to 

determine which chemicals have a common mechanism of toxicity and to evaluate the cumulative 

effects of such chemicals, see the policy statements released by EPA’s Office of Pesticide Programs 

concerning common mechanism determinations and procedures for cumulating effects from substances 

found to have a common mechanism on EPA’s website at http://www.epa.gov/pesticides/cumulative/. 

8.0 Occupational Exposure and Risk 
Page 24 of 71 

8.1 Handlers 

Tolfenpyrad 15EC Insecticide is formulated as an emulsifiable concentrate (EC) and contains 15% of 

the ai, tolfenpyrad. The product is to be applied by backpack sprayer, high pressure handwand, and 

low pressure handwand equipment. The proposed maximum single application rate is 0.003 lb ai per 

gallon. The application rates range from 0.003 – 0.006 lb ai per gallon per crop cycle. In addition, 

two separate spray volumes are specified on the label, resulting in a range of application rates of 0.68 

to 1.36 lb ai/A. Based on the number of seasonal applications (2 applications per crop cycle, with a 

minimum 10-day RTI) indicated on product labels and information provided by the registrant, nondietary exposures are expected to be of short-, intermediate- and long-term durations for occupational 

handlers. 

However, based on integrated pest management practices and chemical rotations, long-term handler 

exposures are considered to be less likely and any assessments of such exposures are likely to be 

conservative. No handler activities are expected for more than 6 consecutive months. Since doses 

selected for short-, intermediate- and long-term assessments are the same, the short-term exposure and 

risk assessment is protective of long-term exposures. 

The following handler exposures result from dermal and inhalation routes for the proposed greenhouse 

uses: 

• Mixing/Loading/Applying Liquid Formulation for High Pressure Handwand 

• Mixing/Loading/Applying Liquid Formulation for Low Pressure Handwand 

• Mixing/Loading/Applying Liquid Formulation for Backpack Sprayer 

8.1.1. Data and Assumptions for Handler Exposure Scenarios 

The assumptions, parameters and factors used for the exposure calculations include: 

 

• Application rates were based on the proposed label. Maximum application rate on proposed 

 label = 32 oz/100 gal. Product contains 1.25 lb ai/gal (0.0098 lb ai/fl oz). 

Maximum Single Application Rate = 32 oz/100 gal * 0.0098 lb ai/fl oz = 0.00313 lb ai/gal 

 

• Unit Exposures: Chemical-specific data for assessing exposure during pesticide handling activities 

were not submitted to the Agency in support of this Section 3 application. It is HED policy to use 

data from PHED to assess handler exposures for regulatory actions when chemical-specific data 

are not available (HED ExpoSAC, SOP No. 7, January 1999). 

 

The baseline clothing level was used as a starting point to calculate handler exposures, even though 

the proposed label recommends the use of baseline clothing plus chemical-resistant gloves. 

Depending upon the need for additional dermal protection, additional PPE is added to obtain an 

MOE higher than the LOC. The baseline clothing level for occupational exposure scenarios 

generally represents an individual wearing long pants, a long-sleeved shirt, shoes, socks, no 

chemical-resistant gloves, and no respirator. As reflected in the calculations included herein, PPE 

may involve the addition of chemical-resistant gloves. For handlers mixing/loading and applying 

liquids with high and low pressure handwand and backpack sprayer, no data are available to assess 
Page 25 of 71 

risks at baseline attire. Therefore, those handler scenarios were assessed at baseline plus chemicalresistant gloves. 

The proposed label has PPE recommendations which include: 

• Applicators and other handlers must wear a long-sleeved shirt, long pants, socks, chemicalresistant gloves and footwear. 

 

• Area Treated: Based on HED’s Exposure Science Advisory Committee SOP Number 9.1, the 

following gallons per day were assumed: 

 

• 40 gallons/day for mixing/loading/applying liquids using low-pressure handwand, and 

backpack sprayer. 

 

• 1000 gallons/day for mixing/loading/applying liquids using high pressure handwand. 

• Body Weight: The average adult body weight of 70 kg was used for all calculations, since the 

 endpoints selected for risk assessment were not sex-specific. 

8.1.2. Exposure and Risk

Summaries of the short-term risks (MOEs) at baseline (a long-sleeved shirt, long pants, shoes, and 

socks), and at baseline plus chemical-resistant gloves for handlers, are included in Table 8.1.2. The 

results indicate that dermal and inhalation risks do not exceed HED’s LOC, with MOEs greater than 

100 at the baseline clothing scenario with the addition of chemical-resistant gloves, which are already 

specified on the proposed label. 

HED recommends that the proposed label PPE language be amended from: 

“Chemical-resistant gloves made of any waterproof material such as barrier laminate or 

polyvinyl chloride” to “Chemical-resistant gloves made of materials such as barrier laminate or 

polyvinyl chloride.” 
Page 26 of 71 

Table 8.1.2. Short- and Intermediate-Term Handler Exposure for Tolfenpyrad.Exposure Scenario 

Mitigation Levela

Dermal Unit Exposureb(mg/lb ai)

Inhalation Unit Exposure b (mg/lb ai)

Crop Application 

Ratec

Amount Treatedd

Dermal Dosee(mg/kg/day)

Dermal MOEf

Inhalation Doseg(mg/kg/day)

InhMO

Short- and Intermediate-Term 

Mixing/Loading and Applying liquids for high pressure handwand application (PHED data) 

Single layer, Gloves 

2.5 0.120 mg/lb 

ai

Ornamentals 0.00313 lb 

ai/gal 

1,000 gallons/day 

0.11179 1,800 0.00537 480 

Mixing/Loading and Applying liquids for low pressure handwand (PHED data) 

Single layer, Gloves 

0.43 0.03 mg/lb 

ai

Ornamentals 0.00313 lb 

ai/gal 

40 gallons/day 

0.00077 260,000 0.00005 48,

Mixing/Loading and Applying liquids for backpack sprayer application (PHED data) 

Single layer, Gloves 

2.50 0.03 mg/lb 

ai

Ornamentals 0.00313 lb 

ai/gal 

40 gallons/day 

0.00447 45,000 0.00005 48,

a. Baseline Dermal: Long-sleeve shirt, long pants, and no gloves. Baseline plus Gloves Dermal: Baseline plus chemical-resistant gloves. b. Unit Exposures based on PHED Version 1.1. c. Application Rates based on proposed use on label for tolfenpyrad. d. Exposure Science Advisory Council Policy No. 9.1. e. Dermal Dose (mg/kg/day) = Daily Unit Exposure (mg/lb ai) x Application Rate (lb ai/gal) x Gallons Treated / Body Weight (70 kg). 

f. Dermal MOE = NOAEL (200 mg/kg/day) / Dermal Daily Dose (mg/kg/day). Short- and Intermediate-Term LOC = 100; Long-term LOC = 300 

g. Inhalation Dose (mg/kg/day) = Daily Unit Exposure (μg/lb ai) x Application Rate (lb ai/acre) x Acres Treated / Body Weight (70 kg). 

h. Inhalation MOE = NOAEL (2.6 mg/kg/day) / Inhalation Daily Dose (mg/kg/day). Level of concern = 100. 
Page 27 of 71 

8.2 Postapplication 

Based on the number of seasonal applications indicated on these product labels, the proposed 

greenhouse use pattern, and information provided by the registrant, postapplication exposures 

are expected to be short- (1-30 days), intermediate- (1-6 months), and long-term (≥ 6 months-1 

year) in duration. However, only short-term and long-term exposures were quantitatively 

assessed. Since doses selected for short- and intermediate-term assessments are the same, the 

short-term exposure and risk assessment is protective of intermediate-term exposures. Since 

tolfenpyrad is going to be used on multiple rotational ornamental crops, workers are expected to 

conduct nursery postapplication activities and will potentially be exposed to foliar residues more 

than 6 consecutive months per year. 

Since no chemical-specific data such as DFR studies were submitted to estimate postapplication 

exposure, postapplication activities were assessed using dermal TCs from ExpoSAC: ARTF 

Ornamental Plants Transfer Coefficients, April 2002, summarized in Table 8.2. In addition, 

default assumptions with respect to the fraction available for transfer and residue dissipation (as 

described below) were used, along with the following: 

• Application Rate = 0.68 – 1.36 lb ai/A, representing the lower and higher spray volumes 

specified on the label and shown in Table 2.1. 

• Exposure Duration = 8 hours per day 

• Body Weight = 70 kg 

The fraction of ai retained on foliage surfaces is assumed to be 20% (0.2) of the application rate 

on the day of initial treatment. This fraction is assumed to further dissipate at the rate of 10% 

(0.1) per day. These are standard values established by HED ExpoSAC when no information is 

known about possible bonding to soil and foliar surfaces and dissipation of the active ingredient 

over time.

HED generally assesses exposure at “day 0” (i.e., on the day of treatment), and if MOEs are 

below the LOC, HED determines how many days would be needed in order to achieve an MOE 

>100. These calculations take into consideration the type of reentry activities likely to occur for 

a given scenario. Higher contact activities (such as hand harvesting or harvesting cut flowers) 

result in higher exposures, and may require longer reentry intervals to be specified on the label. 

Table 8.2 Anticipated Postapplication Activities and Dermal Transfer Coefficients for Greenhouse use of 

Tolfenpyrad. 

Proposed Crops Policy Crop/Group 

Category 

Transfer 

Coefficients 

(cm2/hr) 

Activity Reference† 

Ornamentals ash, yew, rose, evening 

primrose, gladiolus, 

cherry, arrowood, 

110 outdoor ornamental 

pruning, tying 

MRID 454695-01; 

ARTF Study No. 

ART043 
Page 28 of 71 

175 greenhouse hand 

pinching ornamentals; 

nurseries activities 

MRID 453445-01; 

ARTF Study No. 

ART039 

marigold, moss rose, new 

guinea impatiens, 

petunia, gerbera, 

chrysanthemum, coleus, 

poinsettia, schefflera, 

lantana 

400 harvest (workers moved 

plants to trucks and 

reorganized the gallon 

pots or containers) 

MRID 454695-02; 

ARTF Study No. 

ART044 

Cut flowers 5100 (short-term) 

2700 

(intermediateand long term) 

hand-harvesting MRID 465139-01 

† The information in the table is based on proprietary and non-proprietary data. 

8.2.1. Exposure and Risk 

Inhalation 

The WPS for Agricultural Pesticides contains requirements for protecting workers from 

inhalation exposures during and after greenhouse applications through the use of ventilation 

requirements. Tolfenpyrad has a vapor pressure of 3.0 x 10-8 mm Hg. Although there is potential 

for postapplication inhalation exposure resulting from the use of tolfenpyrad in greenhouses, 

with proper use of ventilation, tolfenpyrad inhalation exposure is expected to be negligible. 

Therefore, a quantitative postapplication inhalation exposure assessment was not performed. 

This approach may be revisited in the future with potential changes in the Agency’s approach for 

assessing inhalation exposure and risk. 

Dermal 

A summary of the postapplication MOEs and respective reentry intervals is provided in Table 

8.2.1. Based on the number of seasonal applications indicated on the proposed product labels, 

and information provided by the registrant, postapplication exposures are expected to be shortintermediate- and long-term in duration for all ornamentals plants. Standard assumptions with 

respect to body weight, area treated, and TCs were used to calculate the MOEs for occupational 

reentry. Since the same endpoint was selected for short- and intermediate-term exposure, shortterm exposure and risk are representative/protective of intermediate-term exposures. For longterm exposures, HED provided a comparison of the estimated number of days required before an 

MOE reached the LOC. 

Two spray volumes were assessed with application rates ranging from 0.68-1.36 lb ai/A; the 

default approach was used for estimating REIs, since no DFR data were submitted. 

The short- and intermediate-term postapplication assessments for ornamental crops resulted in 

MOEs of 100 or greater on “day 0” (immediately after application) for low, medium and high 

contact exposure activities (i.e., pruning, tying, hand pinching, nursery activities, and cutting 

flowers) and were not of concern. 

Long-term postapplication MOEs are not of concern for low-medium contact activities (i.e., 
Page 29 of 71 

pruning, tying, hand pinching, and nursery activities). For long-term postapplication high contact 

activities (i.e., cutting flowers), a REI of 4 days would be needed to reach the target MOE of 300 

at the maximum spray volume/A (AR=1.36 lb ai/A). However, it should be noted that long-term 

(≥ 6 months-1 year) dermal postapplication exposure was estimated assuming the same residue 

calculated on day of initial treatment (i.e., day “0” residue value). HED believes the residue 

available for exposure after 6 months or longer is likely to be lower than the residue value 

estimated on the day of initial treatment. The day “0” residue value used for long-term 

postapplication dermal assessment represents a high-end assumption. Considering the nature of 

the residues used for the long-term postapplication risk assessment, the MOE = 210 (on day 0) 

for high contact activities at the maximum spray volume/A (1.36 lb ai/A) is recognized as a 

conservative risk estimate. 

Submission of a chemical-specific DFR study for greenhouses is recommended to refine the 

residue values and reduce the uncertainty for high contact scenarios. 

Table 8.2.1. Short-, Intermediate- and Long-Term Postapplication Exposure and Risk for Tolfenpyrad.

Crops Activity Application 

Rate 

(lb ai/A) 

DATa 

(TC - cm2/hr) 

DFRb (ug/cm2) Daily Dosec

(mg/kg/day) 

MOEd

Short- and Intermediate-term

0.68 0 

(110 cm2/hr) 

pruning, 1.523 0.0191 10,000 

tying 

1.36 0 

(110 cm2/hr) 

3.046 0.0383 5,200 

0.68 0 

(175 cm2/hr) 

hand 1.523 0.0305 6600 

pinching, 

nursery 

activities 1.36 0 

(175 cm2/hr) 

3.046 0.0609 3,300 

0.68 0 

(400 cm2/hr) 

harvesting 1.523 0.0696 2,900 

(workers 

moved plants 

to trucks and 

reorganized 

the gallon 

pots or 

containers) 

1.36 0 

(400 cm2/hr) 

3.046 0.1393 1,400 

0.68 0 

(5100 cm2/hr) 

1.523 0.8878 230 

Ornamentals 

hand 

harvesting; 

cutting 

flowers 1.36 0 

(5100 cm2/hr) 

3.046 1.7756 110 
Page 30 of 71 

Table 8.2.1. Short-, Intermediate- and Long-Term Postapplication Exposure and Risk for Tolfenpyrad.

Crops Activity Application 

Rate 

(lb ai/A) 

DATa 

(TC - cm2/hr) 

DFRb (ug/cm2) Daily Dosec

(mg/kg/day) 

MOEd

Short- and Intermediate-term

Long-Term 

0.68 0 

(110 cm2/hr) 

pruning, 1.523 0.0191 10,000 

tying 

1.36 0 

(110 cm2/hr)

3.046 0.0383 5,200 

0.68 0 

(175 cm2/hr) 

hand 1.523 0.0305 6,600 

pinching, 

nurseries 

activities 1.36 0 

(175 cm2/hr) 

3.046 0.0609 3,300 

0.68 0 

(400 cm2/hr) 

harvesting 1.523 0.0696 2,900 

(workers 

moved plants 

to trucks and 

reorganized 

the gallon 

pots or 

containers) 

1.36 0 

(400 cm2/hr) 

3.046 0.1393 1,400 

0.68 0 

(2700 cm2/hr) 

1.523 0.4700 430 

0 

(2700 cm2/hr)

3.046 0.9400 210 

Ornamentals 

handharvesting 

1.36 

4 

(2700 cm2/hr) 

1.999 0.6168 320 

Note: 

a. DAT = Days After Treatment. TC = Transfer Coefficient. 

b. Dislodgeable Foliar Residue (DFR) = Application Rate (lb ai/A) x (1- Daily Dissipation Rate)t

 x 4.54E8 ug/lb x 2.47E-8 

A/cm2

 x 0.2 

c. Short- and Intermediate-term Daily Dose = [DFR (ug/cm2

) x TC (cm2/hr) x 0.001 mg/ug x 8 hrs/day] ÷ Body Weight (70 kg); 

 Long-term Daily Dose = [DFR (ug/cm2

) x TC (cm2/hr) x 0.001 mg/ug x 8 hrs/day] ÷ Body Weight (70 kg) 

d. Short- and Intermediate-term MOE = NOAEL/Daily Dose (NOAEL = 200 mg/kg/day; LOC = 100). 

e. Long-term MOE = NOAEL/Daily Dose (NOAEL = 200 mg/kg/day; LOC = 300). 

 

 

8.3 Restricted Entry Interval

The REI specified on the proposed label is based on the acute toxicity of tolfenpyrad technical 
Page 31 of 71 

material which is classified as Category III for acute dermal and inhalation toxicity, Category IV 

for dermal and eye irritation, and Category II for acute oral toxicity. Based on the acute toxicity 

profile of tolfenpyrad, the 24 hour REI appearing on the proposed label is appropriate for low, 

medium, and high contact postapplication activities. 

9.0 Data Needs and Label Recommendations

9.1 Occupational Exposure 

Based on the current risk assessment: 

• All handlers should wear a long-sleeved shirt, long pants, socks, chemical-resistant gloves 

and footwear as stated in the proposed label. 

• The proposed label personal protective equipment (PPE) language should be revised to state 

the use of: “Chemical-resistant gloves made of materials such as barrier laminate or 

polyvinyl chloride.” 

• The default dislodgeable foliar residue (DFR) values and assumptions used in the assessment 

may be under or overestimated. Therefore, submission of a chemical-specific DFR study for 

greenhouses is recommended to reduce this uncertainty, and could potentially result in 

reduced exposure and risk estimates for all scenarios. 

• To determine the exposure duration that needs to be assessed for future registration actions, 

the applicant could provide the Agency with information to characterize the use pattern for 

the end-use product (EP) containing tolfenpyrad. Such information might include specific 

seasonal information about the use to be assessed, major regions on which the product is 

applied and how the product fits with other active ingredients in pest resistance management 

programs. 

• The Registration Division (RD) should ensure that the appropriate restricted reentry interval 

(REI) is included on the proposed label. 

9.2 Toxicology 

• The requirement for the 90-day dermal toxicity study is not waived. As a condition of 

registration, HED recommends Nichino submit the dermal toxicity study with rats dosed up 

to the limit dose in an effort to better characterize long-term dermal exposure 

• As a condition of registration, the dose range-finding studies mentioned in the 4 week 

inhalation study should be submitted to the Agency. It was stated that in a previously 

conducted study with groups of 3 rats/sex/concentration, deaths were observed after a single 

6-hour exposure to 26 or 79 mg/m3

. In repeated dose studies, similar groups of rats tolerated 

a 4-day exposure at 11 mg/m3

 or 5 days at 3.6 mg/m3

References: 

Tolfenpyrad: Occupational Risk Assessment to Support Registration for Use of the New Active 

Ingredient on Ornamental Plants in Greenhouses. D366500, Z. Figueroa, June 3, 2010. 
Page 32 of 71 
Page 33 of 71 

Appendices 

Appendix A: Toxicology Assessment

A.1 Toxicology Data Requirements 

The requirements (40 CFR 158.340) for non-food use for tolfenpyrad are in Table A1. Use of the 

new guideline numbers does not imply that the new (1998) guideline protocols were used. 

Technical 

Table A.1 Test 

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 21/28-Day Dermal .......................................................... 

870.3250 90-Day Dermal ............................................................... 

870.3465 90-Day Inhalation........................................................... 

yes 

yes 

no 

yes 

no 

yes 

yes 

yes 

 no 

--- 

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..................................................... 

no 

no 

no 

no 

no 

yes 

yes 

yes 

yes 

yes 

870.5100 Mutagenicity—Gene Mutation - bacterial...................... 

870.5300 Mutagenicity—Gene Mutation - mammalian................. 

870.5375 Mutagenicity—Structural Chromosomal Aberrations .... 

870.5395 Mutagenicity—Mammalian Erythrocyte Micronucleus . 

870.5550 Mutagenicity—Unscheduled DNA Synthesis ................ 

870.5915 Mutagenicity—In Vivo Sister Chromatid Exchange 

yes 

yes 

yes 

no 

no 

no 

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 Develop. Neuro .............................................................. 

no 

no 

no 

no 

no 

--- 

--- 

--- 

--- 

--- 

870.7485 General Metabolism ....................................................... 

870.7600 Dermal Penetration......................................................... 

no 

no 

yes 

yes 

870.7800 Immunotoxicity................................................ yes yes 
Page 34 of 71 

A.2 Toxicity Profiles 

Table A.2.1. Acute Toxicity Profile -Tolfenpyrad 

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

870.1100 Acute Oral -Rat 47457501 LD50 Males => 

386 mg/kg bw 

LD50 Females 

=>150 mg/kg bw 

LD50 Combined 

=>239 mg/kg bw 

II 

870.1200 Acute Dermal-Rat 47457503 LD50 Males > 

2000 mg/kg bw 

LD50 Females > 

3000 mg/kg bw 

LD50 Combined > 

2500 mg/kg bw 

III 

870.1300 Acute Inhalation-Rat 47447734 LC50 Males >2.21 

mg/L 

LC50 Females 

>1.50 mg/L 

LC50 Combined 

>1.82 mg/L 

III 

870.2400 Acute Eye Irritation-Rabbit 47457505 Mildly irritating III 

870.2500 Acute Dermal Irritation-Rabbit 47457507 Slightly irritating IV 

870.2600 Skin Sensitization-Guinea Pig 47447740 Not Sensitizing - 

Table A.2.2 Subchronic, Chronic and Other Toxicity Profile for Tolfenpyrad 

Type of 

Study/Guide 

line 

Study Title MRID Results 

870.3100 90-Day Oral Toxicity, Rat 

w/4 week recovery 

47447743 Levels tested: 0, 15, 80, 160 ppm or 0/0, 0.9/1, 

4.8/5.2, 9.3/9.3 mg/kg/day in males/females 

 

NOAEL (M/F) =15 ppm or 0.9/1 mg/kg/day 

LOAEL (M/F) = 80 ppm or 4.8/5.2 mg/kg/day, 

based on decreased body weight (5-9%), body 

weight gain (8-13%), and food consumption in both 

sexes; increased relative liver and kidney weight, 

hepatocellular hypertrophy and kidney hypertrophy, 

hyaline droplets in the kidney, brown color change 

in the liver.; brown color change in the harderian 

gland along with hypersecretion. 

Additionally at 160 ppm, decreased body weight (8-

26%), body weight gain (35-41%) and food 

consumption; small sex organs (seminal vesicle, 

ovary, uterus, and vagina; ovarian and uterine 

atrophy and decreased ovarian weight.

870.3100 90-Day Oral Toxicity, 47463702 and Levels tested: 0, 15, 100, 300 pm or 0/0, 2.4/3.0, 
Page 35 of 71 

Table A.2.2 Subchronic, Chronic and Other Toxicity Profile for Tolfenpyrad 

Type of 

Study/Guide 

line 

Study Title MRID Results 

Mouse 47447801 15.9/20.2, 46.2/57.9 mg/kg/day in males/females 

NOAEL (M/F)-300 ppm or 46.2/57.9 mg/kg/day 

LOAEL (M/F)-not determined in main study; 600 

ppm (104/126 mg/kg/day) based on decreased body 

weights, body weight gains, clinical signs (rough 

coats, hunched posture, ataxia, hypoactivity), and 

moribundity/mortality seen in 28 day oral study. 

Note: Decreased Body weight gain (42%) was 

observed at 300 ppm in the range-finding study; 

however, 600 ppm (the HDT) was selected as the 

LOAEL for the 90 day mouse study since no effects 

on body weight gain were seen in this study at 300 

ppm. 

870.3150 4-week Oral Toxicity, 

Dog (capsule) 

13-week Oral Toxicity, 

Dog (capsule) 

47447805 

47447803 

Levels tested: 0, 1, 5, 10 mg/kg/day 

NOAEL (M/F) = 5 mg/kg/day 

LOAEL (M/F) = 10 mg/kg/day, based on abnormal 

feces and liver and kidney histopathology. 

Levels tested: 0, 1, 5, 10 mg/kg/day 

NOAEL (M/F) = 10 mg/kg/day 

LOAEL (M/F) = Not determined 

870.3150 13-week Oral Toxicity, 

Dog (capsule) 

47447804 Levels tested: 0, 10, 30, 100 mg/kg/day 

NOAEL (M/F) = 10 mg/kg/day 

LOAEL (M/F) = 30 mg/kg/day, based on mortality 

(1/4 males); clinical signs (no defecation/watery 

feces, emaciation, decrease in spontaneous 

movement, and staggering gait); decreased body 

weights, body weight gains, and food consumption; 

and effects on the liver (increased cytoplasmic 

eosinophilia and centrilobular vacuolation in the 

hepatocytes) and in males, testes (atrophy) and 

kidney (vacuolization of tubular epithelium). 

870.3200 21-Day Dermal 47447806 Levels tested: 0, 10, 50, 200 mg/kg/day 

NOAEL (M/F) = 200 mg/kg/day 

LOAEL (M/F) = not determined 

At ≥ 50 mg/kg/day, decreased body weight gain and 

food consumption observed. 

870.3250 90-Day Dermal No study Available: Waiver request submitted 

870.3465 4-Week Inhalation 

Toxicity, Rat 

47447728 Levels tested: 0, 0.50, 2.0, 10 mg/m3 or 0, 0.0005, 

0.002, and 0.01 mg/L 

NOAEL = 10 mg/m3 (EPA calculated 2.6 

mg/kg/day) 

LOAEL = not determined 

Mortality observed at 26 mg/m3

 (EPA calculated 6.8 

mg/kg/day) in range-finding study (not available). 

870.3700a Developmental Toxicity, 

Rat (Gavage) 

47447809 Levels tested: 0, 1, 3, 4.5 mg/kg/day; GD 6-15) 

Maternal NOAEL =1mg/kg/day 
Page 36 of 71 

Table A.2.2 Subchronic, Chronic and Other Toxicity Profile for Tolfenpyrad 

Type of 

Study/Guide 

line 

Study Title MRID Results 

Maternal LOAEL = 3 mg/kg/day, based on 

decreased body weight gains and food consumption 

Developmental NOAEL = 3 mg/kg/day 

Developmental LOAEL = 4.5 mg/kg/day, based on 

increased incidences of 14th ribs, decreased fetal 

body weights, and decreased number of ossified 

metacarpals. 

870.3700b Developmental Toxicity, 

Rabbit (Gavage) 

47447811 Levels tested: 0, 1, 3, 6 mg/kg/day GD 6-18 

Maternal NOAEL = 6 mg/kg/day 

Maternal LOAEL = 9 mg/kg/day. The maternal 

LOAEL was not established in the current study but 

was 9 mg/kg/day in the preliminary study (MRID 

47447810) based on a single mortality, emaciation, 

and on decreased body weights, body weight gains, 

and food consumption 

Developmental NOAEL = 6 mg/kg/day 

Developmental LOAEL = 9 mg/kg/day. The 

developmental LOAEL was not established in the 

current study but was 9 mg/kg/day in the 

preliminary study based on increased early 

resorption and incidences of supernumerary 

coronary orifices, fusion of the ossification centers 

of the caudal vertebral bodies, 13th ribs, and delayed 

ossification of the manus 

870.3800 2 Generation 

Reproduction, Rat 

(feeding) 

47447817 Levels tested: 0, 0.75, 1.5, or 3.0 mg/kg/day. 

Parental NOAEL = 1.5 mg/kg/day 

Parental LOAEL = 3.0 mg/kg/day, based on 

decreased body weight and body weight gains, 

decreased motor activity, reddish tears, and prone 

position prior to death in two dams. 

Reproductive NOAEL= 1.5 mg/kg/day 

Reproductive LOAEL=3.0 mg/kg/day, based on 

decreased gestation index, increased gestation 

duration, abnormal parturition, and total litter loss 

Offspring NOAEL = 1.5 mg/kg/day 

Offspring LOAEL = 3.0 mg/kg/day, based on 

decreased pup viability and body weights, and 

delays in attainment of developmental landmarks 

(eye opening, pinna folding, surface righting reflex) 

870.3800 1 Generation 

Reproduction, Rat 

(feeding) 

47447816 Levels tested: 0, 15, 50, 100 ppm or 0/0, 0.86/0.92, 

2.7/2.9, 4.8/4.4 mg/kg/day. 

Parental NOAEL = 15 ppm or 0.86/0.92 mg/kg/day 

Parental LOAEL = 50 ppm or 2.7/2.9 mg/kg/day, 

based on decreased body weight gains and food 

consumption during pre-mating, and on decreased 

body weights during gestation and lactation in the 

females. 

Reproductive NOAEL= 50 ppm 

Reproductive LOAEL= 100 ppm or 4.8/4.4, based 

on increased gestation duration 
Page 37 of 71 

Table A.2.2 Subchronic, Chronic and Other Toxicity Profile for Tolfenpyrad 

Type of 

Study/Guide 

line 

Study Title MRID Results 

Offspring NOAEL = 15 ppm 

Offspring LOAEL = 50 ppm, based on decreased 

body weights and body weight gains in both sexes. 

870.4100 Chronic Toxicity-1 Year, 

Dog (feeding) 

47442818 Levels tested: 0, 1, 5, 10 (reduced from 20) 

mg/kg/day 

NOAEL (M/F) 5 mg/kg/day 

LOAEL (M/F) 10 mg/kg/day, based on mortality, 

vomiting, decreased body weights, body weight 

gains, food consumption,, increased serum alanine 

aminotransferase in the males, and microscopic liver 

findings in males and females 

870.4200a Carcinogenicity, 18-

Month Mouse (feeding) 

47463703 Levels tested: 0, 15, 150 ppm or 0, 2.2/2.8, 

20.8/27.1 mg/kg/day in males/females; An 

additional group of 50 mice/sex/dose was treated 

similarly at a dose of 500 ppm for Weeks 1-12, 400 

ppm for Weeks 13-19, and 300 ppm for Weeks 20-

79 (60.9/75.9 mg/kg bw/day in males/females). The 

dose for the high group was adjusted twice due to 

observed toxicity (mortality). 

NOAEL (M/F) 15 ppm or 2.2/2.8 mg/kg/day 

LOAEL (M/F) 150 ppm or 20.8/27.1 mg/kg/day, 

based on moderate decreases in body weight (3-9%) 

and body weight gain (18%), food consumption, and 

clinical signs (increased incidence of ears missing in 

males and ear sores and scabs in females) 

870.4200b Chronic/Oncogenicity, 2- 

Year, Rat (feeding) 

47463704 Levels tested: 0, 15, 40, 80 ppm or 0/0, 0.6/0.7, 

1.5/1.9, and 3.1/3.8 mg/kg/day in males/females 

NOAEL (M/F) 15 ppm or 0.6/0.7 mg/kg/day 

LOAEL (M/F) 40 ppm or 1.5/1.9 mg/kg/day, based 

on decreased body weight, body weight gain, and 

food consumption of females, gross changes in the 

Harderian glands of males, and histopathological 

changes in the liver, kidney and mesenteric lymph 

nodes of females and the kidney of males.

870.5100 Technical (OMI-88) 

In vitro Bacterial Gene 

Mutation (S. 

typhimurium/ E. coli)/ 

mammalian activation 

gene mutation assay 

47463705 Negative. There was no evidence of induced 

mutant colonies over background. 

 

870.5100 Metabolite (OH-PT) 

In vitro Bacterial Gene 

Mutation (S. 

typhimurium/ E. coli)/ 

mammalian activation 

gene mutation assay 

47447822 Negative. There was no evidence of induced 

mutant colonies over background. 

 

870.5300 Technical (OMI-88) 47463706 Negative. There was no evidence of induced mutant 

colonies over background in the presence or absence 

of S9-activation. 
Page 38 of 71 

Table A.2.2 Subchronic, Chronic and Other Toxicity Profile for Tolfenpyrad 

Type of 

Study/Guide 

line 

Study Title MRID Results 

In Vitro Gene Mutation 

assay in mouse lymphoma

cells 

870.5375 Technical (OMI-88) 

In vitro Mammalian 

Cytogenetics 

(Chromosomal Aberration 

Assay in Chinese Hamster 

Lung (CHL) cells) 

47447824 Negative. There was no evidence of structural 

chromosome aberrations induced over background 

in the presence or absence of S9-activation. 

Note: cultures treated for 24 and 48 hours in the 

absence of S9 in Trial 2 resulted in a marked 

increase in the frequency of cells with numerical 

chromosome aberrations (predominantly polyploidy) 

that exceeded the historical control range. However, 

this effect decreased with an increase in dose. 

Similarly, a significant effect was only observed at 

the low-dose (10.1 μg/mL) during Trial 1 (24 hr, -

S9). The biological significance of polyploidy in 

vitro is not completely understood at the present 

time. Therefore, this finding was not considered to 

be an adverse treatment-related effect. The positive 

controls induced the appropriate response in the 

presence and absence of S9 in both trials. 

870.5375 Metabolite (OH-PT) 

In vitro Mammalian 

Cytogenetics 

(Chromosomal Aberration 

Assay in Chinese Hamster 

Lung (CHL) cells)

47447826 Negative. There was no evidence of structural 

chromosome aberrations induced over background 

in the presence or absence of S9-activation. 

870.5395 Technical (OMI-88) 

In Vivo Mammalian 

Cytogenetics - Erythrocyte 

Micronucleus Assay 

47447827 Negative. There was no significant increase in the 

frequency of micronucleated polychromatic 

erythrocytes in bone marrow after any treatment 

time. 

Non-guideline Technical (OMI-88) 

Cell Cycle Kinetics Assay

47463707 The purpose of this study was to explain the 

polyploidy observed in a previously conducted 

Chinese hamster lung chromosome aberration study 

(MRID 47447824). In the absence of S9-activation, 

Tolfenpyrad caused cell cycle delay after exposure 

for as little as 3 hours and polyploidy after as little 

as 6 hours exposure. The polyploidy observed in 

the previous chromosome aberration study was 

likely due to the inhibition of cell cycle progression.

870.6200a Acute Neurotoxicity, Rat 

(gavage) 

47447831 Levels tested: 0, 20, 40, 60 mg/kg/day in males and 

0, 10, 20, or 40 mg/kg/day in females. 

NOAEL (M/F) = 10 mg/kg/day 

LOAEL (M/F) = 20 mg/kg/day, based on decreases 

in body weight, body weight gain and food 

consumption in females. 

870.6200b Subchronic Neurotoxicity, 

Rat (feeding 

47447830 0, 15, 40, 80 ppm or 0/0, 1/1.2, 2.7/3.2, 5.4/6 

mg/kg/day 
Page 39 of 71 

Table A.2.2 Subchronic, Chronic and Other Toxicity Profile for Tolfenpyrad 

Type of 

Study/Guide 

line 

Study Title MRID Results 

NOAEL (M/F) =40 ppm or 2.7/3.2 mg/kg/day 

LOAEL (M/F) = 80 ppm or 5.4/6 mg/kg/day, based 

on decreased body weights, body weight gains, and 

food consumption 

870.6300 Developmental 

Neurotoxicity, Rat 

No study Available: Waiver request submitted 

870.7485 Metabolism, Rat 47447837, 

47447836, 

47447834, 

47447833, and 

47447835 

The test compound was rapidly absorbed and 

excreted. Total recoveries ranged from 91.3-99.6% 

of the administered dose (AD) across all groups and 

in both sexes. Feces were the predominant route of 

excretion. Across all single dose groups, 88.2-

93.2% AD was excreted in the feces and 1.7-3.0% 

AD was eliminated in the urine. Negligible amounts 

of radioactivity were recovered in the expired air 

and cage wash, both accounting for ≤0.1% AD. In 

the bile duct-cannulated rats at 48 h post-dosing, the 

majority of radioactivity was excreted in the bile 

(51.3-69.5% AD), with minor amounts eliminated in 

the feces (3.5-8.3% AD) and urine (0.7-3.0% AD), 

indicating that bile was the primary route of 

excretion for the absorbed test material. Absorption 

(defined as radioactivity found in the bile, urine, 

cage wash, and carcass) was greater in males (72.8-

77.8% AD) than in females (57.9-69.4% AD). 

Females also had more radioactivity remaining in 

the gastrointestinal tract, and the amount remaining 

increased with dose. 

870.7600 Dermal Penetration, Rat 47447839 At 24 hours in the 1 g/L group, the dermal 

absorption is 13%. 

870.7800 Developmental 

Immunotoxicity, Rat 

(feeding) 

47447840 Levels tested: 0, 0.75, 3 mg/kg/day 

Maternal NOAEL = 0.75 mg/kg/day 

Maternal LOAEL = 3 mg/kg/day, based on 

decreased body weight (up to 10%), body weight 

gain (up to 36%), and food consumption in the P 

generation 

Offspring NOAEL = 0.75 mg/kg/day 

Offspring LOAEL = 3 mg/kg/day, based on 

decreased survival, body weight, and body weight 

gains; increased incidence of blackish abdominal 

cavity and dark green abnormal intestinal content; 

and decreased thymus and spleen weights in the F1 

and/or F2 generations 

Note: No treatment-related effects noted on the 

immune system. 

Non guideline In vitro metabolism 47447838 Total recovery was 91.0-108.1% of the radioactivity 

added to the incubations, of which the parent 

compound accounted for 10.2-12.4%. Only 1.4-

1.9% of the radioactive residues were found in 
Page 40 of 71 

Table A.2.2 Subchronic, Chronic and Other Toxicity Profile for Tolfenpyrad 

Type of 

Study/Guide 

line 

Study Title MRID Results 

unidentified compounds; the remaining 

approximately 88% of the isolated metabolites were 

identified. In addition to the parent, a total of 17 

metabolites were identified. The primary metabolite 

was OH-PT-CA (24.5-32.4%); other major 

metabolites included PT-CA (13.4-16.2%), CO-PTCA (9.3-13.2%), OH-PT (7.6-8.4%), PT-OH (6.7-

7.7%), and OH-PT-OH (3.8-5.3%). The other 

metabolites were present at <5% of the total 

incubation dose. 

The main metabolic pathways included the 

oxidations of the methyl moiety of T-CH3 and ω-1 

carbon of CH3CH2-P. The oxidation of these two 

carbons resulted in the formation of the 

hydroxylated metabolites PT-OH, OH-PT, and OHPT-OH. Further oxidation leads to the metabolites 

PT-CHO, PT-CA, OH-PT-CA, CO-PT, CO-PT-OH, 

and CO-PT-CA. Other metabolic pathways include 

the bond cleavage of the amide and methylene 

moieties, the demethylation of N-CH3, or the 

formation of the vinyl group after hydroxylation of 

CH3CH2-P. 
Page 41 of 71 

A.3 Executive Summaries 

Oral Subchronic Toxicity Study-Rat; OPPTS 870.3100 

EXECUTIVE SUMMARY: In a subchronic oral toxicity study (MRID 47447743), 

Tolfenpyrad (OMI-88; 99.33% a.i.; Lot No. 6D-01-2) was administered in the diet to Fischer 344 

rats (10/sex/dose) at doses of 0, 15, 80, or 160 ppm (equivalent to 0/0, 0.9/1.0, 4.8/5.2, and 

9.3/9.3 mg/kg/day for males/females) for 13 weeks. Additionally 6 rats/sex were similarly 

treated for 13 weeks at 0 or 160 ppm and then subsequently allowed 4 weeks of control diet 

(recovery period). 

No treatment-related effects were observed on mortality, clinical signs, ophthalmoscopic 

examinations, or urinalysis. 

Decreased body weights, body weight gains, and food consumption were noted in the 80 and 160 

ppm groups and decreased food efficiency was noted in the 160 ppm group. Decreased 

(p<=0.05) body weights were generally noted at Weeks 2-13 in the 80 ppm group (decr 4-9%) 

and throughout treatment in the 160 ppm group (decr 8-26%). Decreased (p<=0.01, except as 

noted) body weight gain was noted for the overall treatment period (Weeks 0-13) in the 80 ppm 

males (↓8%; not significant) and females (decr 13%) and the 160 ppm group (decr 35-41%). In 

males, food consumption (g/rat/day) was decreased (p<=0.05) in the 80 ppm group (decr 6-15%) 

for 5-6 of the 13 weeks. Decreased (p<=0.05) food consumption was observed throughout 

treatment in the 160 ppm group (decr 12-39%). The total mean food consumption for the 

treatment period was reduced by 5-10% in the 80 ppm group and by 23-31% in the 160 ppm `the 

13 weeks by sex and determined that the grand mean was decreased by 17-20% at 160 ppm. 

Decreased (p<=0.05) leukocyte counts were noted in the 80 and 160 ppm females at Week 14 

(decr 27-29%). The adversity of this effect was considered marginal due to the magnitude of 

change. 

At 160 ppm, the following sex organs were small: seminal vesicle, ovary, uterus, and vagina. 

Microscopically, increased incidences of slight ovary and uterus atrophy were observed at 160 

ppm. Decreased (p<=0.01) relative ovary weight was also noted (decr 20%). 

The following differences were observed in the clinical chemistry parameters of the 160 ppm 

group compared to the controls at Week 14: (i) decreased triglycerides in the males; (ii) 

increased potassium in both sexes; (iii) increased inorganic phosphorus in both sexes; (iv) 

increased urea nitrogen in females; (v) increased glucose in females; and (vi) increased 

γ-glutamyl transferase in females. 

In the 80 and 160 ppm groups, increased relative to body liver weights were noted. In the 160 

ppm group, increased incidence of brownish color was noted grossly in the liver, and an 

increased incidence of increased slight, diffuse hepatocellular hypertrophy was noted 

microscopically in males and females at 80 and 160 ppm. In both sexes of the 80 and 160 ppm 

groups, increased relative to body kidney weights were noted. Increased incidences of slight 

hyaline droplets in the kidney in the 80 and 160 ppm males and slight proximal tubular 
Page 42 of 71 

epithelium hypertrophy in the kidney in the 80 and 160 ppm females were observed. In the 80 

and 160 ppm group, increased incidence of brownish color and slight hypersecretion was 

observed in the Harderian gland. 

In general, partial or complete recovery occurred for all findings during the recovery period. 

The LOAEL is 80 ppm (equivalent to 4.8/5.2 mg/kg/day in males/females), based on 

decreased body weights, body weight gains, and food consumption in both sexes. 

Additionally, increased relative liver and kidney weights, hepatocellular hypertrophy, 

brown color change in the liver; hyaline droplets in the kidney; brown color change in the 

harderian gland along with hypersecretion. The NOAEL is 15 ppm (equivalent to 0.9/1.0 

mg/kg/day in males/females).

This study is classified as acceptable/guideline and satisfies the guideline requirements (OPPTS 

870.3100; OECD 408) for a subchronic oral toxicity study in the rat. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, and Quality 

Assurance statements were provided. 

Oral Subchronic Toxicity Study-Mouse; OPPTS 870.3100 

EXECUTIVE SUMMARY: In a subchronic oral toxicity study (MRID 47463702), 

Tolfenpyrad (99.33% a.i.; Lot No. 6D-01-2) was administered in the diet to 10 CD-1 

mice/sex/dose at dose levels of 0, 15, 100, or 300 ppm (equivalent to 0/0, 2.4/3.0, 15.9/20.2, and 

46.2/57.9 mg/kg/day in males/females) for 13 weeks. 

No adverse, treatment-related effects were observed on mortality, clinical signs, body weight, 

body weight gains, food consumption, food efficiency, ophthalmology, hematology, clinical 

chemistry, urinalysis, organ weights, or gross or microscopic pathology. 

During 4 of the 13 weeks, minor decreases (p<=0.05) in food consumption were observed in the 

300 ppm males (decr 10-12%), and a minor decrease (p<=0.05) of 8% was noted in overall 

(Weeks 1-13) food consumption. These decreases in food consumption did not significantly 

(p>0.05) effect body weight or body weight gain. 

The LOAEL was not established. The NOAEL was 300 ppm (equivalent to 46.2/57.9 

mg/kg/day in males/females), the highest dose tested. 

This study is classified as acceptable/guideline and satisfies the guideline requirements (OPPTS 

870.3100; OECD 408) for a subchronic oral toxicity study in the mouse. Although the LOAEL 

was not established and the limit dose was not tested, this study was considered acceptable based 

on an acceptable dose-selection rationale. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, Flagging, and 

Quality Assurance statements were provided. 
Page 43 of 71 

Oral Subchronic Toxicity Study-Dog; OPPTS 870.3150

EXECUTIVE SUMMARY: In a subchronic oral toxicity study (MRID 47447803), OMI-88 

(Tolfenpyrad, 99.33% a.i., Batch No. 6D-01-2) was administered to 4 Beagle dogs/sex/dose via 

gelatin capsule at dose levels of 0, 1, 5 or 10 mg/kg/day for 13 weeks. 

No effects of treatment were observed on mortality, body weight, body weight gain, food 

consumption, food efficiency, ophthalmological examinations, hematology, clinical chemistry, 

urinalysis, absolute and relative organ weights, or gross or microscopic pathology. 

Vomiting was observed at all doses in 2-3 males and 3-4 females, as well as 1 dog of each sex in 

the control groups. The total number of days of vomiting among treated animals (# observed out 

of a possible 92/93 days, M/F) was 6-15 in the males and 6-33 in the females, compared to 1-3 

days for affected controls. Soft feces was observed in all males at 5 and 10 mg/kg/day (vs. 1/4 

controls) with the total number of days being 16-23 treated vs. 2 controls). These findings were 

first observed during study Week 1, but the report did not indicate on which days. Additionally, 

mucous feces were noted in one 10 mg/kg/day female on 12 days during treatment. These 

findings may have reflected irritation to the gastrointestinal lining from a bolus (capsule) dose. 

Although vomiting and abnormal feces were observed more frequently in the treated groups 

compared to the controls, these findings were not accompanied by other clinical signs of toxicity 

and did not compromise food consumption, food efficiency, bodyweights, or body weight gains 

of the animals. Therefore, these findings were not considered adverse. The LOAEL was not 

observed (>10 mg/kg/day), and the NOAEL is 10 mg/kg/day.

This study is classified acceptable/guideline, and in conjunction with another 13-week oral 

toxicity study in dogs that establishes a LOAEL (MRID 47447804, reviewed concurrently in 

separate DER), fulfills the guideline requirement (OPPTS 870.3150; OECD 409) for a 

subchronic toxicity study in dogs. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, and Quality 

Assurance statements were provided. No Flagging statement was provided. 

Oral Subchronic Toxicity Study-Dog; OPPTS 870.3150

EXECUTIVE SUMMARY: In this subchronic oral toxicity study (MRID 47447804), 4 beagle 

dogs/sex/group were administered Tolfenpyrad (99.33% a.i.; Lot #6D-01-2) daily via capsule at 

doses of 0, 10, 30 or 100 mg/kg/day for 13 weeks. The study was conducted at higher doses than 

a previous 13-week oral dog study (MRID 47447803) to establish a clear LOAEL. 

There were no treatment-related effects on ophthalmoscopy, hematology or organ 

weights. 

In the 30 mg/kg/day group, one male (#3002) died on Day 90. In the 100 mg/kg/day group, one 

male (#4001) died on Day 13, and two females (# 4101 and 4103) died on Day 23. Additionally 

in this group, male #4004 and female #4102 were euthanized in extremis on Days 41 and 23, 
Page 44 of 71 

respectively. The remaining two males and one female in this group exhibited clinical signs 

such as no feces, emaciation, and decreased body weight and food consumption. Therefore, 

these surviving animals (#4002, 4003, and 4104) were terminated on Day 49. 

In all of the treated groups, salivation, vomiting and fecal abnormalities (soft feces, mucous 

feces, feces mixed with test material) were noted. These findings were observed with greater 

incidence and frequency at the higher two doses. Additionally at 30 and 100 mg/kg/day, 

incidences of no defecation, emaciation, decrease in spontaneous movement, and staggering gait 

were found in the males; and watery feces were observed in the females. These findings were 

reported in all dose groups during the first week, but it could not be determined from the 

individual animal data presentation in the study report whether they were observed on the initial 

day of dosing. At 100 mg/kg/day, mydriasis, lateral position, miosis and hypothermia were 

noted in the males; and emaciation, decrease in spontaneous movement, staggering gait and 

mydriasis were observed in the females (by Week 4). In general, these findings were dosedependently increased in incidence and/or frequency. 

At 100 mg/kg/day, body weights were decreased by 5-34% compared to controls in the males 

and by 8-39% in the females for Weeks 1 through 6. The magnitude of these differences became 

greater with time. Food consumption was decreased by 4-88% compared to controls during 

Weeks 2 through 7 in the males and by 15-76% during Weeks 1-7 in the females. 

At 30 mg/kg/day, body weights in the males were decreased by 6-14% compared to controls 

during Weeks 7 through 13, with only minor decreases of 1-2% prior to Week 7. In the females 

at this dose, body weights were decreased by 3-7% throughout the study. Body weight gains for 

the overall (Weeks 0-13) study were 55% lower than controls in the males and 18% lower in the 

females. At 30 mg/kg/day, food consumption was 7-38% lower than controls in the males from 

Weeks 6 through 13. Only minor sporadic differences in food consumption were noted in the 30 

mg/kg/day females and in both sexes at 10 mg/kg/day. 

At 10 mg/kg/day, body weights were only minimally decreased (1-5%). Furthermore, the 

decreases in body weights in the males were sporadic. Overall body weight gains were 18% 

lower than controls in the males and 27% lower in the females. 

Several changes in clinical chemistry indicated the reduced nutritional status of the animals, 

resulting from decreased food consumption, including decreased alkaline phosphatase at 30 and 

100 mg/kg/day in both sexes and decreased triglycerides in all treated groups in the females. 

Albumin and albumin/globulin ratio were increased and α1, β1, and β2 globulins were decreased 

in the 100 mg/kg/day females. The increase in albumin may indicate dehydration; whereas the 

decreases in globulins corroborate effects on the liver. 

Blood urea nitrogen was increased by 64% at 30 mg/kg/day at Week 13 and by 33 and 208% in 

the 100 mg/kg/day males at Weeks 4 and 7, respectively. Urine volume was decreased by 62-

73% in the 100 mg/kg/day males and females at Week 7. 

Atrophy of the thymus was noted at gross necropsy in the one male at 30 mg/kg/day that died 
Page 45 of 71 

(#3002) and in two males (#4002 and 4003) and one female (#4104) at 100 mg/kg/day. 

The following treatment-related microscopic lesions (# affected vs 0 controls) were observed at 

30 and 100 mg/kg/day: (i) increased cytoplasmic eosinophilia of hepatocyte in the 30 mg/kg/day 

males (2) and females (1) and 100 mg/kg/day males (4) and females (4); (ii) centrilobular 

vacuolation in hepatocytes in the 30 mg/kg/day males (1) and 100 mg/kg/day males (2) and 

females (2); (iii) atrophy of the thymus in the 30 mg/kg/day males (1) and 100 mg/kg/day males 

(3) and females (3); (iv) atrophy of the submandibular lymph node in the 30 mg/kg/day males (1) 

and 100 mg/kg/day males (3) and females (2); (v) atrophy of the mesenteric lymph node in the 

30 mg/kg/day males (1) and 100 mg/kg/day males (4) and females (2); (vi) vacuolation in the 

tubular epithelium in the kidneys in the 30 mg/kg/day males (1) and 100 mg/kg/day males (2) 

and females (1); (vii) atrophy of the Peyer’s patch in the ileum in the 30 mg/kg/day males (1) 

and 100 mg/kg/day males (4) and females (2); (viii) atrophy of the seminiferous tubules in the 

testes at 30 mg/kg/day (3) and 100 (4) mg/kg/day; (ix) decrease in the number of sperm in the 

lumen of the epididymis at 30 mg/kg/day (1) and 100 (1) mg/kg/day; (x) cell debris in the lumen 

of the epididymis at 30 mg/kg/day (1) and 100 (2) mg/kg/day; and (xi) atrophy of the prostate at 

30 mg/kg/day (1) and 100 (2) mg/kg/day. 

Additionally at 100 mg/kg/day, the following microscopic lesions were found (compared to 0 

controls): (i) brown pigmentation in Kupffer’s cell in 1 female; (ii) hypocellularity of the bone 

marrow in 2 males and 1 female; (iii) focal degeneration and hemorrhage in the cerebrum in 1 

male and 1 female; (iv) focal degeneration in the cerebellum in 1 male and 1 female; (v) focal 

hemorrhage in the cerebellum in 1 female; (vi) focal hemorrhage in the heart in 1 male and 1 

female; (vii) sublingual gland atrophy 1 male; (viii) focal hemorrhage in the lungs in 1male; (ix) 

lung congestion in 1 female; and (x) atrophy of the ovaries in 1 female. 

The LOAEL is 30 mg/kg/day based on: mortality (1/4 males); clinical signs (no 

defecation/watery feces, emaciation, decrease in spontaneous movement, and staggering 

gait); decreased body weights, body weight gains, and food consumption; and effects on the 

liver (increased cytoplasmic eosinophilia and centrilobular vacuolation in the hepatocytes) 

and in males, testes (atrophy) and kidney (vacuolization of tubular epithelium). The 

NOAEL is 10 mg/kg/day. 

This study is classified acceptable/guideline and satisfies the guideline requirements (OPPTS 

870.3150; OECD 409) for a subchronic oral toxicity study in dogs. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, Flagging and 

Quality Assurance statements were provided. 

Dermal Subchronic (28-day) Toxicity Study-Rat; OPPTS 870.3200

EXECUTIVE SUMMARY: In a repeated-dose dermal toxicity study (MRID 47447806), 

Tolfenpyrad (99.5% a.i., Lot #: 365-65A) was applied neat (moistened with 0.2 mL deionized 

water) to the shaved intact skin of 10 Sprague-Dawley rats/sex/dose at dose levels of 0, 10, 50, 

or 200 mg/kg/day, 6 hours/day for 21 consecutive days. 
Page 46 of 71 

No adverse compound-related effects were observed in mortality, clinical signs of toxicity, body 

weight, ophthalmoscopic exams, hematology, clinical chemistry, absolute or relative organ 

weights, or gross or microscopic pathology in either sex. No treatment-related dermal effects 

were observed at any dose in either sex. Slight dermal irritation was observed at 50 and 200 

mg/kg/day; however, this finding was not considered adverse. 

In the 50 mg/kg/day females, absolute food consumption was decreased (p<=0.05) by 9% during 

Days 15-21 and by 6% overall (Days 1-21). Additionally in these animals, non-statistically 

significant decreases in body weight were noted at Days 15 and 21 (decr 4-7%), overall (Days 1-

21) body weight gain was decreased (p<=0.01) by 42% compared to controls. 

In the 200 mg/kg/day females, absolute food consumption was decreased (p<=0.05) by 11% 

during Days 15-21 and by 7% overall. Additionally in these animals, non-statistically significant 

decreases in body weight were noted at Days 15 and 21 (decr 5-8%), and overall body weight 

gain was decreased (p<=0.01) by 44% compared to controls. 

The reviewers disagree with the Sponsor that the NOAEL was 200 mg/kg/day. The animals 

were of the appropriate age (approximately 8 weeks old) at the beginning of the study, and the 

controls displayed expected levels of body weight gain. These statistically significant decreases 

in overall body weight gain in the females were considered biologically significant. 

The LOAEL is 50 mg/kg/day, based on decreases in body weight gain and food 

consumption in the females. The NOAEL is 10 mg/kg/day. 

This study is classified as acceptable/guideline and satisfies the guideline requirement for a 21-

day dermal toxicity study (OPPTS 870.3200; OECD 410) in rats. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, Flagging, and 

Quality Assurance statements were provided. 

Subchronic Inhalation Study-Rat; OPPTS 870.3465

EXECUTIVE SUMMARY: In a subchronic inhalation toxicity study (MRID 47447728), 

Tolfenpyrad (99.5% a.i., Lot #365-65A) was administered as an aerosol dust in air to 10 

Sprague-Dawley rats/sex/concentration by nose-only exposure at concentrations of 0 (air), 0.50, 

2.0, or 10 mg/m3 (equivalent to analytical concentrations of 0, 0.0005, 0.002, and 0.01 mg/L, 

respectively) for 6 hours per day, 5 days/week during a 4-week period, for a total of 20 exposure 

days. 

There were no mortalities or clinical signs of toxicity. Furthermore, no treatment related effects 

were observed on body weights, body weight gains, food consumption, food efficiency, 

ophthalmology, clinical chemistry, urinalysis, gross pathology, or histopathology. 

At 10 mg/m3, the number of white blood cells was decreased by 24% (p<=0.05) in the females 
Page 47 of 71 

compared to controls. Corresponding decreases were observed in all white cell types in these 

animals, with significant (p<=0.05) decreases in the numbers of lymphocytes (decr 23%), 

monocytes (decr 29%), eosinophils (decr 57%), and basophils (decr 50%), and a non-significant 

decrease in the number of neutrophils (decr 27%). Additionally, the number of large unstained 

cells was significantly (p<=0.05) decreased by 25% in the females at this concentration. In the 

absence of corroborating findings, these decreases were considered to be of equivocal 

toxicological importance. These decreases were within historical control range and were not 

observed in males. 

Absolute liver weights and liver weights relative to body weight and to brain weight were 

increased by 15-17% (p<=0.05) in the 10 mg/m3

 females. Minimal diffuse hepatocellular 

hypertrophy was found in 2/10 males and 3/10 females at this concentration compared to 0 

controls. Although treatment-related, the increased liver weights and hepatocellular hypertrophy 

were considered to be an adaptive response to the test material and not adverse at this 

concentration. 

The LOAEL was not observed. The NOAEL is 10 mg/m3 (equivalent to an analytical 

concentration of 0.01 mg/L).

Although a LOAEL was not observed, an acceptable concentration-selection rationale was 

provided. In the previously conducted dose range-finding studies with groups of 3 

rats/sex/concentration, deaths were observed after a single 6-hour exposure to 26 or 79 mg/m3. 

In repeated dose studies, similar groups of rats appeared to tolerate a 4-day exposure at 11 

mg/m3 or 5 days at 3.6 mg/m3. Given the fact that mortality was observed at 26 mg/m3 after a 

single 6-hour exposure, it was reasonable for the Sponsor to select 10 mg/m3

 as the high 

concentration for a 28-day study (20 exposure days). Because only adaptive effects were noted 

in the liver in both sexes and equivocal decreases in white blood cells were seen in the females at 

10 mg/m3 in the current study, the reviewers recommend that any future 28-day study be 

conducted in the range 10 mg/m3 to 26 mg/m3. 

At the request of the Agency, this study was conducted for 4 weeks, instead of the 13 weeks 

required by Guideline OPPTS 870.3465. Aside from the different study duration, this study was 

conducted in accordance with Guideline OPPTS 870.3465. 

This 4-week study is classified as acceptable/guideline and satisfies the guideline requirement 

(OPPTS 870.3465; OECD 413) for a subchronic inhalation study in the rat. 

COMPLIANCE - Signed and dated Data Confidentiality, GLP Compliance and Quality 

Assurance statements were provided. 

Developmental Toxicity Study-Rat; OPPTS 870.3700a 

EXECUTIVE SUMMARY: In a developmental toxicity study (MRID 47447809), tolfenpyrad 

(99.33%; Lot # 6D-01-2) in 0.5% carboxymethylcellulose (CMC) was administered via daily 

oral gavage in a dose volume of 10 mL/kg to 24 naturally-mated presumed pregnant Sprague-
Page 48 of 71 

Dawley rats/dose group at doses of 0, 1, 3, or 4.5 mg/kg/day from gestation days (GD) 6-15. On 

GD 20, all surviving maternal rats were euthanized; each dam’s uterus was removed via cesarean 

section and its contents examined. The fetuses were examined for external, visceral, and skeletal 

malformations and variations. Another study report (MRID 47447812) stated that it included 

additional fetal examination data; however, these data were identical to the data for the visceral 

and skeletal examinations of the fetuses already presented in the definitive study report (denoted 

as “amended”). An addendum (MRID 47447813) was included to include summary and 

individual necropsy findings and data on maternal body weights and body weight gains corrected 

for total live fetal weight (in lieu of gravid uterine weight); these data are incorporated in 

appropriate sections within the body of this DER. Another addendum (MRID 47447815) was 

submitted to assess the possible effect of the shorter administration period on the study 

conclusions; this information is included in an appendix in this DER. 

All maternal animals survived until scheduled termination. No clinical signs of toxicity were 

noted in any of the dams. Aside from a single dam at 4.5 mg/kg/day with a mammary gland 

nodule, no gross abnormalities were found in any animal at any dose level. This finding was 

considered incidental to treatment. 

At 3 and 4.5 mg/kg/day, body weight gains were dose-dependently decreased (p<=0.01) by 57-

113% for GD 6-9, by 29-69% for GD 6-12, and by 24-47% for the overall (GD 6-15) treatment 

interval. Additionally at 4.5 mg/kg/day, body weight gains were decreased by 19% compared to 

controls for GD 6-20 and by 21% for GD 0-20 (when corrected for the total weight of the live 

fetuses). Body weights were decreased by 7-9% (p<=0.01) at 4.5 mg/kg/day beginning on GD 9 

and continuing throughout the remainder of the study. Maternal food consumption was dosedependently decreased (p<=0.01) by 9-12% at 3 mg/kg/day and by 28% 4.5 mg/kg/day on GD 9 

and GD 12. There were no treatment-related effects on body weights, body weight gains, or 

food consumption at 1 mg/kg/day. 

The maternal LOAEL is 3 mg/kg/day based on decreased body weight gains and food 

consumption. The maternal NOAEL is 1 mg/kg/day. 

There were no abortions, premature deliveries, complete litter resorptions, or dead fetuses. 

There were no effects of treatment on the numbers of litters, live fetuses, early resorptions, or 

late resorptions. Furthermore, sex ratio and post-implantation losses in the treated groups were 

comparable to controls. 

At 4.5 mg/kg/day, fetal body weights were decreased by 7-9% compared to controls. The mean 

number of ossified metacarpi at 4.5 mg/kg/day (6.43) was significantly (p<=0.05) lower than 

controls (7.00). The numbers of ossified cervical vertebrae, sternebrae, metatarsi, and sacral and 

caudal vertebrae of the treated groups were comparable to controls. 

No external or visceral variations were noted. Incidences of 14th ribs, a variation, were increased 

(p<=0.05) at 4.5 mg/kg/day (16 fetuses; 5 litters) compared to controls (1 fetus). There were no 

other treatment-related skeletal variations. 
Page 49 of 71 

At 4.5 mg/kg/day, one fetus (#L06 from Dam #50405) had microcephaly and anophthalmia 

observed externally, corresponding to holoprosencephaly observed viscerally. Additionally at 

this dose, abnormal origin of the right subclavian artery was noted in a single fetus. Although no 

historical control data were provided, it is unlikely that these findings were due to treatment 

because only a single fetus per each finding was affected. 

The developmental LOAEL is 4.5 mg/kg/day based on increased incidences of 14th ribs, 

decreased fetal body weights, and decreased number of ossified metacarpals. The 

developmental NOAEL is 3 mg/kg/day. 

This study is classified acceptable/guideline and satisfies the guideline requirement (OPPTS 

870.3700a; OECD 414) for a developmental toxicity study in rats.

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, Flagging, and 

Quality Assurance statements were provided. 

 

Developmental Toxicity Study-Rabbit; OPPTS 870.3700b

EXECUTIVE SUMMARY: : In a developmental toxicity study (MRID 47447811), 

tolfenpyrad (99.33%; Lot # 6D-01-2) in 0.5% carboxymethylcellulose (CMC) was administered 

via daily oral gavage in a dose volume of 5 mL/kg to 16 artificially inseminated Japanese White 

rabbits/dose group at doses of 0, 1, 3, or 6 mg/kg/day from gestation days (GD) 6-18. On GD 

28, all surviving maternal rabbits were euthanized; each doe’s uterus was removed via cesarean 

section and its contents examined. The fetuses were examined for external, visceral, and skeletal 

malformations and variations. 

In the 3 mg/kg/day group, one animal (# 50312) died on GD 28. Although no clinical signs of 

toxicity were noted in this animal prior to death, food consumption was decreased on GD 9, and 

essentially no food was eaten for the remainder of the study. Thus, body weights were 

consistently decreased after GD 9. Lung congestion, yellowing of the liver, and small spleen 

were noted during the gross necropsy. Microscopic findings of lung congestion, diffuse fat 

accumulation in the hepatocytes, and atrophy of the spleen corresponded to the gross lesions 

noted in this animal. Additionally, fat accumulation was found in the renal tubule epithelium at 

the corticomedullary junction of the kidney. In contrast to the investigator’s conclusions, the 

reviewers do not consider this death to be due to treatment because no mortality was observed at 

6 mg/kg/day in this study or in the preliminary study (MRID 47447810). Furthermore, the gross 

and microscopic findings noted in the lung, spleen, and kidney in this dam were not found in any 

of the maternal animals in the range-finding study (including one dam from the 9 mg/kg/day that 

died); and yellowish liver was noted in a single 3 mg/kg/day dam in the range-finding study, 

with no such findings at higher doses. 

In the 6 mg/kg/day group, one dam (# 50406) delivered prematurely on GD 27. No changes in 

clinical signs were observed in this animal on the previous day, and no gross abnormalities were 

found at necropsy. In the range-finding study, premature delivery was noted in a single dam at 6 

mg/kg/day and another at 9 mg/kg/day. It is important to note that all three of these premature 
Page 50 of 71 

deliveries occurred just prior to the expected day of parturition (on GD 27 or GD 28), and that no 

abortions or dead fetuses were observed. 

At 3 mg/kg/day, food consumption was decreased by 11-27% from GD 12 through GD 18. 

However, these decreases were not statistically significant and did not result in decreased body 

weights or body weight gains. 

At 6 mg/kg/day, food consumption was significantly (p<=0.01) decreased by 38% compared to 

controls on GD 9. Although food consumption remained decreased by 13-28% throughout the 

remainder of the treatment period, these decreases were not statistically significant. 

Furthermore, body weights were only decreased by 2-5% throughout the treatment period, with a 

mean body weight loss of 9 grams at this dose compared to a mean body weight gain of 99 

grams in the controls for the treatment period (GD 6-18). Therefore, in contrast to the 

investigators’ conclusions, these decreases in food consumption, body weights, and body weight 

gains were not considered adverse because they were minor and not biologically or statistically 

significant. 

In the preliminary study (see Appendix of this DER), one dam died at 9 mg/kg/day and another 

was emaciated. Maternal body weights, body weight gains, and food consumption were 

substantially decreased at this dose and considered to be adverse effects of treatment. 

The maternal LOAEL was not established in the current study but was 9 mg/kg/day in the 

preliminary study based on a single mortality, emaciation, and on decreased body weights, 

body weight gains, and food consumption. The maternal NOAEL is 6 mg/kg/day. 

There were no abortions or dead fetuses and no effects of treatment on the numbers of litters, 

early resorptions, or late resorptions. Fetal body weights and sex ratio in the treated groups were 

comparable to controls. The mean number of live fetuses/dam was decreased by 21% at 6 

mg/kg/day compared to controls. However, this decrease corresponded to a decrease of 18% in 

the mean number of implantations/dam in this dose group. Because implantation occurs prior to 

the initiation of treatment, these decreases were unrelated to exposure to the test material. 

Complete litter resorptions occurred in 0, 1, 1, and 2 litters at 0, 1, 3, and 6 mg/kg/day, 

respectively. In the 1 mg/kg/day litter (#50204), 3 mg/kg/day litter (#50301), and one of the 6 

mg/kg/day litters (#50403), only a single implantation occurred, which resulted in an early 

resorption. It is unlikely that the loss of these single implantations was due to treatment. The 

other complete litter resorption at 6 mg/kg/day (#50405) was characterized by 9 implantations 

resulting in early resorptions. Post-implantation loss was dose-dependently increased in all 

treated groups (12.70-16.67%) compared to controls (9.01%). Because the mean numbers of 

resorptions/dam in the treated groups were comparable to controls, the increased postimplantation loss is likely a reflection of the complete litter resorptions in these groups. 

Treatment with the test material did not affect growth or development of the fetuses. Fetal body 

weights were comparable to controls. The number of ossified cervical vertebrae, sternebrae, 

metacarpi, metatarsi, and sacral and caudal vertebrae of the treated groups were comparable to 

controls. There were no treatment-related variations or malformations.
Page 51 of 71 

In the preliminary study at 9 mg/kg/day, post-implantation loss and the number of early 

resorptions were increased, largely attributed to the complete litter resorption of an emaciated 

dam (# E05). Live litter size was decreased as a result. In the fetuses, increased incidences of 

fetuses with supernumerary coronary orifices, fusion of the ossification centers of the caudal 

vertebral bodies, and 13th ribs were observed. The number of ossified bones in the medial manus 

was decreased. 

The developmental LOAEL was not established in the current study but was 9 mg/kg/day 

in the preliminary study based on increased early resorption and incidences of 

supernumerary coronary orifices, fusion of the ossification centers of the caudal vertebral 

bodies, 13th ribs, and delayed ossification of the manus. The developmental NOAEL is 6 

mg/kg/day. 

This study is classified acceptable/guideline and, in conjunction with the preliminary study 

(MRID 47447810), satisfies the guideline requirement (OPPTS 870.3700b; OECD 414) for a 

developmental toxicity study in rabbits. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, and Quality 

Assurance statements were provided. 

Developmental Immunotoxicity in rats; Non-guideline 

EXECUTIVE SUMMARY: In a developmental immunotoxicity study (MRID 47447840), 

presumed pregnant Sprague-Dawley rats (15/dose) were administered Tolfenpyrad (OMI-88; 

99.33% a.i.; Lot no. 6D-01-2) as dietary admixtures at doses of 0, 0.75 or 3 mg/kg/day. The 

dietary formulations were presented to the P generation dams beginning on GD 0 and continuing 

through LD 21, after which the dams were sacrificed. The F1 generation rats were offered the 

dietary formulations at the same concentrations as their parents beginning on PND 21. Offspring 

following weaning, one pup/sex/litter was selected to continue on study when possible in both 

F1 and F2 generations. F1 and F2 males were treated daily from PND 21 until their scheduled 

necropsy at either 3 (F1 only) or 10 weeks of age (F1 and F2). The F1 parents were fed the test 

diets for at least 10 weeks prior to mating to produce the F2 litters. 

For maternal toxicity, mortality, clinical signs, body weight, body weight gain, food 

consumption, and gross pathology were evaluated in P and selected F1 and F2 adults. 

Additionally, in the P and F1 adults, the number of implantations, uterine contents, live and 

stillborn pups, litter size, and pup viability were evaluated. For offspring toxicity, the following 

parameters were evaluated in selected F1 and F2 pups: viability, clinical signs, body weight, 

body weight gain, organ weights (brain, thymus, and spleen), and gross pathology. 

Immunotoxicity parameters were evaluated in selected F1 and F2 adults (males only) including 

total leukocytes, leukocyte differential counts, spleen and thymus weights and cellularity, 

percentage distribution and number of lymphocyte subpopulations using surface markers, serum 

titer of anti-SRBC (sheep red blood cells) antibody, and delayed-type hypersensitivity (cellmediated immunity to keyhole limpet hemocyanin, KLH). 
Page 52 of 71 

For maternal toxicity, no treatment-related effects were observed on mortality, clinical signs, 

gross pathology, or reproduction in the P and F1 generations. In the P generation dams, 

decreased body weights (↓4-10%) were observed in the 3 mg/kg/day group at GD 7, 14, and 20 

and at LD 0, 4, and 7. Maternal cumulative body weight gains were decreased at GD 7, 14, and 

20 (↓20-36%), but increased body weight gains were observed at LD 7, 14, and 21 (↑62-145%). 

Decreased food consumption (g/rat/day) was noted throughout gestation and lactation (↓9-22%). 

 No adverse, treatment-related effects were noted on body weights, body weight gains or food 

consumption in the F1 adults. 

The maternal LOAEL is 3 mg/kg/day, based on decreased body weight, body weight gain, 

and food consumption in the P generation. The maternal NOAEL is 0.75 mg/kg/day. 

Offspring toxicity was observed at 3 mg/kg/day. Decreased numbers of offspring at birth and 

live offspring at birth (decr 12-13%) were noted relative to controls in the F1 generation and a 

decreased number of live offspring on PND 4 was noted before culling. Additionally, increased 

incidences of death and cannibalism were observed. A blackish abdominal cavity was noted 

from PND 1-6 in 3-34 pups in 9 litters vs 0 controls in the F1 generation and from PND 1-4 in 

1-4 pups in 2 litters vs 0 controls in the F2 generation. 

Mean pup weights and weight gains were decreased relative to the controls throughout lactation 

(decr 14-31%) in both sexes of the F1 generation. The greatest decreases in body weight gain 

were noted during PND 0-4 (before culling) (decr 28-31%), and the magnitude of decrease was 

reduced with time. Only sporadic, minor decreases were noted in the F1 generation after 

weaning, and these decreases were not considered adverse. Body weights and body weight gains 

in treated groups of the F2 generation were similar to the controls. 

In both sexes of the F1 generation (except as noted), decreased terminal weight was observed at 

PND 4 and PND 21 (decr 14-21%). Decreased absolute brain weight (decr 11-15%) and 

absolute and relative (to body weight) thymus (decr 35-48%) and spleen (decr 19-44%) were 

noted at PND 4. Decreased absolute brain weight (decr 4% each sex), absolute and relative 

thymus in males (decr 16-29%), and absolute thymus weights in females (decr 24%) were 

observed at PND 21. At PND 21 in the males, decreased terminal body weight (decr 16%), 

absolute brain weight (decr 4%) and absolute and relative thymus weights (decr 16-29%) were 

noted. 

In both sexes of the F2 generation, decreased absolute and relative (to body weight) thymus 

(decr 22-41%) and spleen (decr 25-34%) were noted at PND 4 and decreased absolute and 

relative thymus were also observed (decr 21-34%) at PND 21. Thymus weights were similar to 

controls by 10 weeks of age. Thus, the effect on body weight and organ weights were transient, 

suggesting a delay in development. 

In the F1 offspring on PND 4, an increased incidence of dark green abnormal contents of the 

small intestine was observed in males (4/10 treated vs 0/12 controls) and females (4/13 treated vs 

0/15 controls). In the F2 generation at 10 weeks, an increased incidence of renal pelvis 
Page 53 of 71 

dilatation was noted in males (3/10 treated vs 1/10 controls). 

The offspring LOAEL is 3 mg/kg/day, based on decreased survival, body weight, and body 

weight gains; increased incidence of blackish abdominal cavity and dark green abnormal 

intestinal content; and decreased thymus and spleen weights in the F1 and/or F2 

generations. The offspring NOAEL is 0.75 mg/kg/day. 

For immunotoxicity, no treatment-related effect was observed on the anti-SRBC antibody 

response (humoral immune response) or on the delayed-type hypersensitivity to KLH (cellmediated immune response) in F1 or F2 males at 10 weeks of age. Significant decreases of 

thymus weights were observed at 3 mg/kg/day group in the F1 and F2 generations. No 

histopathology was performed. When thymus or spleen weights were decreased, there was 

usually a corresponding decrease in cellularity and a reduction in one or more lymphocyte 

subsets. However, only minor changes were noted in the proportions of lymphocyte subsets (on a 

percentage-basis). This effect resulted in a corresponding transient effect on thymus and/or 

spleen cellularity. In addition, the functional tests (humoral or cell-mediated immune response) 

did not demonstrate any compromise in rats at 10 weeks of age. Therefore, any effect on the 

cellularity and the changes of lymphocyte subsets is considered secondary to the effect on 

development and transient. 

No significant treatment-related effects were noted on the immune system. The 

immunotoxicity LOAEL was not observed. The immunotoxicity NOAEL was 3 mg/kg/day, 

the highest dose tested. 

This study is classified acceptable/non-guideline; however, it can be used to satisfy guideline 

requirements for an immunotoxicity study (OPPTS 870.7800) since it has provided adequate 

information for evaluation of immune function upon exposure to the test substance. 

COMPLIANCE: Signed and dated Quality Assurance, Data Confidentiality, and Flagging 

statements were provided. A GLP Compliance statement was provided that stated the Submitter 

of this study was neither the Sponsor of this study nor conducted it and does not know whether it 

has been conducted in accordance with 40 CFR Part 160.

Reproduction and Fertility Effects-Rat; OPPTS 870.3800 

 

EXECUTIVE SUMMARY: In a two-generation reproduction toxicity study (MRID 

47447817), OMI-88 (tolfenpyrad; 99.33%; Lot # 6D-01-2) was administered in the diet to 30 

Sprague Dawley (Crj:CD) rats/sex/dose group at dietary levels of 0, 0.75, 1.5, or 3.0 mg/kg/day 

for two successive generations with one litter per generation. The P generation animals were fed 

the test diets for ten weeks prior to mating to produce the F1 litters. The F1 litters were culled 

on post-natal day (PND) 4 to eight pups/litter (four/sex where possible). On PND 21, one male 

and one female pup from 24 litters in the 0, 0.75, and 1.5 mg/kg/day dose groups and 22 litters 

(all litters used) in the 3.0 mg/kg/day group were selected and fed the same test diet 

concentration as their dam. These animals were fed the test diets for ten weeks prior to mating 

(at 13 weeks of age) to produce the F2 litters. 
Page 54 of 71 

No treatment-related effects were observed on organ weights, or macroscopic or microscopic 

findings. 

At 3.0 mg/kg/day, two P females began parturition on GD 23. Both dams showed a decrease in 

locomotor activity, reddish tears, and prone position; one of these dams (# 50428) died on GD 

24, and the other (# 50406) was killed and necropsied on GD 24 without completing parturition. 

 A third dam (# 50421) exhibited signs of parturition on GD 23 including hemorrhage from the 

vagina, along with reddish nasal discharge, anemia, and finally death on GD 23. Additionally in 

the P females, one dam (# 50413) showed vaginal hemorrhage, reddish nasal discharge, anemia, 

and total litter loss on LD 0. 

During the pre-mating period at 3.0 mg/kg/day, body weights were decreased in the P females, 

and in the F1 males and females. In the P females, cumulative body weight gains were 

decreased at all intervals beginning on PND 21 and continuing throughout pre-mating. Food 

consumption was decreased in the P and F1 males and females. Additionally at 3.0 mg/kg/day 

during the post-mating period, body weights, cumulative body weight gains, and food 

consumption were decreased in the P males, and body weights were decreased in the F1 males. 

During gestation in the P generation, body weights were decreased in the 1.5 mg/kg/day dams on 

GD 7-20, and in the 3.0 mg/kg/day dams throughout gestation (GD 0-20), resulting in decreased 

cumulative gestational body weight gains. Food consumption was also decreased in the 3.0 

mg/kg/day females throughout gestation. During gestation in the F1 generation, body weights 

were decreased in the 3.0 mg/kg/day dams, resulting in decreased cumulative gestational body 

weight gains. Food consumption was decreased on GD 14 and 20. 

During lactation, body weights were decreased in the 1.5 mg/kg/day P dams on LD 0, and in the 

3.0 mg/kg/day P dams on LD 0-7, and in the 3.0 mg/kg/day F1 dams on LD 0-4. Food 

consumption was decreased in the 3.0 mg/kg/day P females on LD 21, and in the 1.5 and 3.0 

mg/kg/day F1 dams. However, cumulative lactational body weight gains were increased in the 

3.0 mg/kg/day P and F1 dams, respectively, and food efficiency was generally increased in these 

doses in both generations, reflecting the recovery in body weight gains. 

The LOAEL for parental toxicity is 3.0 mg/kg/day, based on decreased body weight and 

body weight gains, decreased motor activity, reddish tears, and prone position prior to 

death in two dams The NOAEL is 1.5 mg/kg/day. 

No treatment-related effects were noted on the viability or lactation indices, sex ratio on PND 

21, on the day of attainment of criterion for either balanopreputial separation or vaginal patency, 

organ weights, or on gross or microscopic pathological findings. 

In the 3.0 mg/kg F1 offspring, decreases were observed in the mean total number of live pups on 

PND 0 and 4 (pre-culling), and mean number of female pups on PND 4 (post-culling) and 21. 

Additionally, the birth and live birth indices were lower at this dose compared to controls. 
Page 55 of 71 

Decreased pup body weights were observed at 3.0 mg/kg in the F1 pups from PND 0-21 and in 

the F2 pups from PND 4 (pre-cull) through 21. 

At 3.0 mg/kg, pinna unfolding was delayed in the F1 males and females on PND 2 and 3, and in 

the F2 males and females on PND 3. The day of eye opening was delayed in the F1 females and 

the F2 males. Surface righting reflex was delayed in the F1 males. All of these observations 

were considered to be related to the reduced body weights and body weight gains observed 

during lactation. 

The LOAEL for offspring toxicity is 3.0 mg/kg, based on decreased pup viability and body 

weights, and delays in attainment of developmental landmarks. The NOAEL is 1.5 mg/kg. 

No differences were observed in mean estrus cycle length in either generation. The number of 

primordial follicles, primary follicles, and total number of these follicles were similar between 

the control and 3.0 mg/kg/day groups in both generations. No treatment-related differences were 

observed in any of the measured sperm parameters in either generation. There were no effects of 

treatment on copulatory interval, or copulation or fertility indices in either generation. 

In the 3.0 mg/kg/day P females, the gestation index was decreased, gestation duration was 

increased, four dams showed abnormal parturition, and four dams had total litter loss. 

The LOAEL for reproductive toxicity was 3.0 mg/kg/day, based on decreased gestation 

index, increased gestation duration, abnormal parturition, and total litter loss. The 

NOAEL is 1.5 mg/kg/day.

This study is classified as acceptable/guideline and satisfies the guideline requirements (OPPTS 

870.3800; OECD 416) for a two-generation reproduction study in the rat. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, Flagging, and 

Quality Assurance statements were provided. 

Oral Chronic Toxicity study -Dog; OPPTS 870.4100

 

EXECUTIVE SUMMARY: In a chronic oral toxicity study (MRID 47447818), OMI-88 

technical (tolfenpyrad; 99.33% a.i.; Lot # 6D-01-2) was administered to four beagle 

dogs/sex/dose group daily by capsule at doses of 0, 1, 5 or 20 mg/kg/day for at least 12 months. 

However, the high dose was reduced to 10 mg/kg/day on Week 5 for the remainder of the study 

because of excessive toxicity. 

No adverse, treatment-related effects were observed on ophthalmoscopic examinations, 

hematology, urinalysis, organ weights or gross pathology. At 5 mg/kg/day, vomiting was 

observed in both sexes at greater frequency primarily during the first four weeks of dosing, and 

one male had serum alanine aminotransferase increased at Months 9 and 12 by 755% and 138%, 

respectively. These findings were considered to be treatment-related, but in the absence of 

evidence of systemic toxicity, were not considered to be adverse. 
Page 56 of 71 

Toxicity was observed in the 20/10 mg/kg/day group. Two premature deaths occurred. One 

male (#4004) died on Day 83. This dog presented with vomiting and abnormal feces (soft, 

watery, or mucus appearance, sometimes containing what appeared to be the test material) soon 

after the initiation of treatment. Beginning on Week 4, this dog displayed salivation, no 

defecation, decreased spontaneous movement, staggering gait, ananastasia, and hypothermia and 

was emaciated beginning on Week 6. At 1 to 2 weeks prior to death, this male also was 

observed with lateral position, abdominal respiration, oligopnea, and paleness of the conjunctival 

and oral mucosa. One female (#4103) died on Day 26. This animal was observed with vomiting 

and abnormal feces (soft and mucus appearance) during Weeks 1-4, and salivation, no 

defecation, and decreased spontaneous movement during Week 4. Additionally at this dose, 

vomiting was observed at greater frequency in the surviving dogs, particularly during the first 

four weeks of dosing. Soft feces were noted 1-4 times/week in the females during the first 

eleven weeks of dosing. Although these findings were observed during the first week, it could 

not be determined from the data as reported whether they were observed on Day 1. Treatmentrelated decreases in body weights, overall (Week 0-52) body weight gains, and food 

consumption were observed. The male that died generally lost body weight from Week 0 to time 

of death and had low food consumption (<200 g/day) from Week 3 on, with no food consumed 

during Weeks 5 and 6. Another male generally lost weight from Week 36 to Week 52, had low 

food consumption during Weeks 38, 41-45, 48, and 51, and it was noted that this dog’s weight 

was lower than the lightest control, resulting in decreased group mean food consumption on 

Week 52. In the females, overall body weight gains were decreased by 33%. This was due to 

two dogs that had weight fluctuations throughout treatment and frequent periods of low food 

consumption, resulting in overall body weight gains that were lower than the lowest control and 

decreased (p≤0.05) group mean food consumption on Week 5. Additionally, the female that died 

generally lost weight from Week 0 (9.0 kg) to time of death (Week 3; 8.7 kg), and had low food 

consumption prior to death. Negative food efficiencies were frequently observed at 20/10 

mg/kg/day, especially in the first 6-8 weeks, reflecting body weight losses in individual animals. 

 Serum alanine aminotransferase (GPT) was increased in one 20/10 mg/kg/day male at Month 12 

by 243% over controls. Treatment-related microscopic findings were observed in the liver. 

Mild to severe increased cytoplasmic eosinophilia of the hepatocytes was observed in 2/4 males 

and 3/4 females, both compared to 0/4 controls. Additionally in the females, the following 

findings were noted: (i) mild pigmentation in the hepatocytes in 2/4 dogs compared to slight in 

1/4 controls; (ii) slight pigmentation in the Kupffer’s cells in 2/4 dogs compared to 0/4 controls; 

(iii) mild to moderate pigment in the hepatocytes by Schmorl’s stain in 2/4 dogs compared to 

slight in 3/4 controls; (iv) slight to mild pigment in the Kupffer’s cells by Schmorl’s stain in 2/4 

dogs compared to slight in 2/4 controls; (v) mild pigment in the hepatocytes by Berlin blue stain 

in 2/4 dogs compared to slight in 3/4 controls; and (vi) slight to mild pigment in the Kupffer’s 

cell by Berlin blue stain in 3/4 dogs compared to slight in 2/4 controls. The LOAEL is 10 

mg/kg/day, based on mortality, vomiting, decreased body weights, body weight gains, food 

consumption, increased serum alanine aminotransferase in the males, and microscopic 

liver findings in males and females. The NOAEL is 5 mg/kg/day. 

This study is classified as acceptable/guideline and satisfies the guideline requirements (OPPTS 

870.4100b; OECD 452) for a chronic oral toxicity study in dogs. 
Page 57 of 71 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, Flagging, and 

Quality Assurance statements were provided; however, the Submitter stated that they were 

neither the Sponsor nor Performing Laboratory of this study, and do not know if it was 

conducted in accordance with 40 CFR Part 160. 

Combined Chronic Toxicity/Carcinogenicity Feeding – Rat; OPPTS 870.4300 

EXECUTIVE SUMMARY: In a combined chronic toxicity/carcinogenicity study (MRID 

47463704), 50 Fischer (F344/DuCrj) rats/sex/dose were exposed to OMI-88 (Tolfenpyrad; 

99.33%; Lot No.: 6D-01-2) over 104 weeks in the diet at concentrations of 0, 15, 40, or 80 ppm 

(equivalent to 0/0, 0.561/0.686, 1.50/1.85, and 3.07/3.79 mg/kg/day in males/females). An 

additional 10 rats/sex/dose were treated similarly for 53 weeks and then sacrificed. 

No test substance-related effects were observed on mortality, clinical signs, food efficiency, 

ophthalmoscopic examinations, hematology, clinical chemistry, urinalysis, or organ weights. 

Systemically, the following statistically significant changes were noted in the 80 ppm group: 

decreased body weight, body weight gain, and food intake of males and females, increased 

incidences of white patched areas in the livers of females at Week 105, increased incidences of 

dark brown changes in the kidneys of males and females at Week 105, hypertrophy of the renal 

proximal tubular epithelial cells in males and females at Week 105, increased incidences of 

brown changes in Harderian glands of males and females at Week 105, increased hypersecretion 

of Harderian glands of males and females at Week 105, an increase in mast cells in the 

mesenteric lymph nodes of males at Week 105, increased sinus histiocytosis in the mesenteric 

lymph nodes of males and females at Week 105, and increased incidences and severity of foci of 

altered hepatocytes (basophilic) in females at Weeks 53 and 105. Hyaline droplets in the renal 

proximal tubular epithelial cells were observed more frequently in high dose males than controls 

at Week 53, but not at Week 105. 

At 40 ppm, slight, but statistically significant reductions in body weight, body weight gains and 

food consumption were observed throughout treatment in females. Grossly, the incidence of 

brown change in the Harderian gland was elevated in males. Non-neoplastic histopathological 

changes included increased sinus histiocytosis in mesenteric lymph nodes, hypertrophy of the 

proximal tubular epithelial cells of the kidney and increased foci of altered hepatocytes 

(basophilic) in females at Week 105. Hyaline droplets in the renal proximal tubular epithelial 

cells of the kidney were observed more frequently in mid dose males than controls at Week 53, 

but not at Week 105. 

The LOAEL is 40 ppm (equivalent to 1.50/1.85 mg/kg/day in males/females), based on 

decreased body weight, body weight gain, and food consumption of females, gross changes 

in the Harderian glands of males, and histopathological changes in the liver, kidney and 

mesenteric lymph nodes of females and the kidney of males. The NOAEL is 15 ppm 

(equivalent to 0.561/0.686 mg/kg/day in males/females).

At the doses tested, there was no treatment related increase in tumor incidence when compared 
Page 58 of 71 

to controls. Dosing was considered adequate based on decreased body weights, body weight 

gains and food consumption, and gross and/or pathological findings in both sexes at 40 ppm. 

This study is classified as acceptable/guideline and satisfies the guideline requirements (OPPTS 

870.4300; OECD 453) for a combined chronic toxicity/carcinogenicity study in rats. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, Flagging, and 

Quality Assurance statements were provided. The Submitter of the study stated that they were 

neither the Sponsor of the study nor conducted it, and did not know if it had been conducted in 

accordance with 40 CFR Part 160.

Carcinogenicity Study -Mouse; OPPTS 870.4200b 

EXECUTIVE SUMMARY: In a carcinogenicity study (MRID 47463703), Tolfenpyrad 

(OMI-88; 99.33% a.i.; Lot No. 6D-01-2) was administered in the diet to CD1 mice (50/sex/dose) 

for up to 18 months at doses of 0, 15 or 150 ppm (equivalent to 0, 2.2/2.8, and 20.8/27.1 mg/kg 

bw/day in males/females). An additional group of 50 mice/sex/dose was treated similarly at a 

dose of 500 ppm for Weeks 1-12, 400 ppm for Weeks 13-19, and 300 ppm for Weeks 20-79 

(60.9/75.9 mg/kg bw/day in males/females). The dose for the high group was adjusted twice due 

to observed toxicity. 

No treatment-related effects were observed on hematology parameters or organ weights. 

During the first 19 weeks there was an increased incidence of unscheduled deaths in the 400/500 

ppm group (5 each treated vs 0 controls). After Week 19 when the high dose was lowered to 300 

ppm, mortality was similar in all treated groups to the controls, or any effects were unrelated to 

dose. At 400/500 ppm (during Weeks 1-12), thinness was noted in both sexes, and some females 

were hypoactive and/or hunched (sometimes with distal tail sore/scab). These data suggest that 

400 ppm or more may exceed the maximum tolerated dose. 

At 300 ppm (during Weeks 20-79), the following findings were noted (# affected in treated 

group vs controls): ear sores/scabs in both sexes, ears missing in males, distal tail missing in 

both sexes, and distal tail sore/scab in females. 

Decreased (p<=0.05) body weights compared to controls were observed in the 150 (decr 3-9%) 

and 300 ppm males (decr 9-28%) and the 300 ppm females (decr 11-24%). These decreases 

contributed to an overall (Weeks 1-78) body weight gain decrease in the 150 (decr 18%) and 300 

ppm males (decr 49%) and the 300 ppm females (decr 47%). Body weight gain reductions 

(p<=0.05) were also noted in these groups for the intervals of Weeks 1-12 (decr 14-72%; treated 

at 500 ppm) and Weeks 13-20 (decr 80-100%; treated at 400 ppm), but body weight gains in 

these treated groups during Weeks 21-78 (treated at 300 ppm) were statistically similar to 

controls. Nevertheless, adverse effects on body weight and body weight gain were considered to 

be observed at 150 ppm and above, based on the overall body weight gain decrease of 18% at 

150 ppm. Decreased (p<=0.05) overall (Weeks 1-78) food consumption compared to the 

controls was observed in both sexes at 150 (decr 8-9%) and 300 ppm (decr 14-16%). Generally, 
Page 59 of 71 

decreases in food consumption were largest in magnitude during the first 12 weeks of treatment 

at 500 ppm. Decreased (not analyzed statistically) mean food efficiency was noted at 300 ppm 

in the males (decr 41%) and females (decr 24%). 

Considering all animals (n=50) at 300 ppm, increased incidences of the gross observations sore 

ears in males (34% treated vs 18% controls) and females (28% vs 10%) and small uterus (14% 

vs 0%) were noted. Histologically, increased incidences of atrophy were observed at 300 ppm in 

the ovary, uterus, and cervix (28-38% treated vs 0% controls). The histological correlates for ear 

lesions observed clinically and grossly were ulcers and inflammation. 

The LOAEL is 150 ppm (equivalent to 21/27 mg/kg bw/day in males/females), based on 

decreased body weights, body weight gains, food consumption in both sexes, and clinical 

signs (increased incidence of missing ears in males and ear sores and scabs in females). 

The NOAEL is 15 ppm (equivalent to 2.2/2.8 mg/kg/day in males/females).

At the doses tested, there was no treatment-related increase in tumor incidence when compared 

to controls. Dosing was considered adequate based on decreased body weights, body weight 

gains, food consumption, and food efficiency, and increased incidence of clinical signs, sore 

ears, and small uterus. 

This study is classified as acceptable/guideline and satisfies the guideline requirement for a 

carcinogenicity study [OPPTS 870.4200b; OECD 451] in mice. 

COMPLIANCE: Signed and dated GLP Compliance, Quality Assurance, Flagging, and Data 

Confidentiality statements were provided. 

Bacterial Reverse Mutation Assay; OPPTS 870.5100 

EXECUTIVE SUMMARY: In two independent trials of a reverse gene mutation assay in 

bacteria (MRID 47463705), Salmonella typhimurium strains TA98, TA100, TA1535, TA1537, 

and TA102 and Escherichia coli strain WP2uvrA were exposed to OMI-88 Technical 

(Tolfenpyrad; 99.33% a.i., Batch No. 6D-01-2) in dimethyl sulfoxide (DMSO) at concentrations 

of 0, 8, 40, 200, 1000, or 5000 μg/plate (all strains, +/-S9, Trial 1) and 0, 62.5, 125, 250, 500, or 

1000 μg/plate (all strains, +/-S9, Trial 2). The S9 fraction was derived from the livers of male 

Sprague-Dawley rats induced with Aroclor 1254TM. The standard plate incorporation method 

was used in Trial 1 (+/-S9) and Trial 2 (-S9), a pre-incubation step was added in Trial 2 (+S9). 

Standard strain-specific mutagens served as positive controls. 

OMI-88 Technical was tested at up to the limit of solubility (+/-S9). Cytotoxicity (thinning of 

background lawn and/or reduction in numbers of revertants) was observed in several strains 

(TA1535, TA1537, and TA102) at 500 and/or 1000 μg/plate in the pre-incubation test (Trial 2, 

+S9). There were no treatment-related increases in the mean number of revertants/plate in any 

strain in either trial (+/-S9). The positive controls induced marked increases in revertant 

colonies compared to controls in all strains in the presence and absence of S9-activation. There 

was no evidence of induced mutant colonies over background. 

The study is classified as acceptable/guideline and satisfies the guideline requirements (OPPTS 
Page 60 of 71 

870.5100; OECD 471) for in vitro mutagenicity (bacterial reverse gene mutation) data. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, and Quality 

Assurance statements were provided. 

Bacterial Reverse Mutation Assay; OPPTS 870.5100 

EXECUTIVE SUMMARY: In two independent trials of a reverse gene mutation assay in 

bacteria (MRID 47447822), Salmonella typhimurium strains TA98, TA100, TA1535, and 

TA1537 and Escherichia coli strain WP2uvrA were exposed to OH-PT (metabolite of 

Tolfenpyrad, 99.9% a.i.; Lot No. Y980423) in dimethyl sulfoxide (DMSO) as follows: 0, 2.44, 

4.88, 9.77, 19.5, 39.1, 78.1, 156, and 313 μg/plate (strains TA100, TA1535, and TA1537, -S9); 

0, 9.77, 19.5, 39.1, 78.1, 156, 313, 625, and 1250 μg/plate (strains TA98 and WP2uvrA, -S9); 0, 

9.77, 19.5, 39.1, 78.1, 156, 313, 625, and 1250 μg/plate (strains TA98, TA100, and WP2uvrA, 

+S9); 0, 39.1, 78.1, 156, 313, 625, 1250, 2500, and 5000 μg/plate (strain TA1535, +S9); and 0, 

2.44, 4.88, 9.77, 19.5, 39.1, 78.1, 156, and 313 μg/plate (strain TA1537, +S9). The S9 fraction 

was derived from the livers of male Sprague-Dawley rats induced with phenobarbital and 5,6-

benzoflavone. The standard plate incorporation method with a pre-incubation step was used 

both with and without S9-activation. Standard strain-specific mutagens served as positive 

controls. 

OH-PT was tested at up to the limit of solubility (+/-S9). With the exception of strain TA98, 

cytotoxicity (thinning of background lawn) was observed in all strains ≥625 –S9 and ≥2500 

μg/plate +S9. There were no treatment-related increases in the mean number of revertants/plate 

in any strain with or without S9. The positive controls induced marked increases in revertant 

colonies compared to controls in all strains in the presence and absence of S9-activation. There 

was no evidence of induced mutant colonies over background. 

The study is classified as acceptable/guideline and satisfies the guideline requirements (OPPTS 

870.5100; OECD 471) for in vitro mutagenicity (bacterial reverse gene mutation) data. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, and Quality 

Assurance statements were provided. However, an additional GLP compliance statement was 

provided which stated that the submitter of the study was neither the Sponsor nor conducted the 

study, and does not know if the study was conducted in accordance with 40 CFR Part 160. 

In Vitro Mammalian Cell Gene Mutation Test; 870.5300, OECD 476

 

EXECUTIVE SUMMARY: 

In Vitro Mammalian Chromosome Aberration Test; OPPTS 870.5375 

EXECUTIVE SUMMARY: In a mammalian cell cytogenetics assay (chromosome aberration; 

MRID 47447824), Chinese hamster lung (CHL) cell cultures were exposed to OMI-88 

(Tolfenpyrad; 99.33% a.i.; Batch # 6D-01-2) in DMSO at concentrations of 0, 4.9, 7.1, 10.1, 

14.4, 20.6, 29.4, 42.0, 60.0, 85.8, 123, 175, or 250 μg/mL for either 6 hours with an 18 hour 
Page 61 of 71 

recovery period in the presence of S9 or for 24 hours of continuous treatment in the absence of 

S9. In Trial 2, cell cultures were exposed at the following concentrations: 0, 32.8, 41.0, 51.2, 

64.0, 80.0, or 100 μg/mL for 6 hours with an 18 hour recovery period in the presence of S9; 0, 

8.6, 10.7, 13.4, 16.8, 21.0, 26.2, 32.8, 41.0, or 51.2 μg/mL for either 24 or 48 hours of 

continuous exposure in the absence of S9; and 0, 21.0, 26.2, 32.8, 41.0, 51.2, 64.0, 80.0, and 100 

μg/mL for 6 hours with an 18 hour recovery period in the absence of S9. The S9 fraction was 

derived from the livers of male Sprague-Dawley rats induced with AroclorTM 1254. 

Cyclophosphamide and methylmethanesulfonate served as positive controls in the presence and 

absence of S9, respectively. 

OMI-88 was tested up to cytotoxic concentrations (i.e., levels that induced a ≥50% decrease in 

cell numbers) both in the presence and absence of S9. In both independent trials, no significant 

increases in the percentage of cells with structural aberrations (excluding gaps) were observed at 

any concentration at any exposure interval in the presence or absence of S9. It was noted that 

cultures treated with OMI-88 for 24 and 48 hours in the absence of S9 in Trial 2 resulted in a 

marked increase in the frequency of cells with numerical chromosome aberrations 

(predominantly polyploidy) that exceeded the historical control range. However, this effect 

decreased with an increase in dose. Similarly, a significant effect was only observed at the lowdose (10.1 μg/mL) during Trial 1 (24 hr, -S9). The biological significance of polyploidy in vitro

is not completely understood at the present time. Therefore, this finding was not considered to 

be an adverse treatment-related effect. The positive controls induced the appropriate response in 

the presence and absence of S9 in both trials. There was no evidence of structural 

chromosome aberrations induced over background in the presence or absence of S9-

activation.

This study is classified as acceptable/guideline and satisfies the Guideline requirement (OPPTS 

870.5375, OECD 473) for in vitro mutagenicity (chromosome aberration) data. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, and Quality 

Assurance statements were provided. 

In Vitro Mammalian Chromosome Aberration Test; OPPTS 870.5375

EXECUTIVE SUMMARY: In a mammalian cell cytogenetics assay (chromosome aberration; 

MRID 47447826), Chinese hamster lung (CHL/IU) cell cultures were exposed to OH-PT 

(metabolite of Tolfenpyrad, 99.9% a.i.; Lot No. Y980423) in dimethyl sulfoxide (DMSO) at 

concentrations of 0, 40, 80, 120, 160, or 200 μg/mL for 6 hours with an 18 hour recovery period 

both in the presence and absence of S9, or at 0, 10, 30, 50, 70, 90, 110, or 130 μg/mL for 24 or 

48 hours of continuous treatment in the absence of S9. The S9 fraction was derived from the 

livers of male Sprague-Dawley rats induced with phenobarbital and 5,6-benzoflavone. 

Cyclophosphamide and mitomycin C served as positive controls in the presence and absence of 

S9, respectively. 

OH-PT was tested up to cytotoxic concentrations (+/-S9). Based on the cytotoxicity observed, 

the following concentrations were selected for evaluation: 40, 80, 120, and 160 μg/mL (6 hrs, 
Page 62 of 71 

+S9); 40, 80, and 120 μg/mL (6 hrs, -S9); 10, 30, 50, 70, and 90 μg/mL (24 hrs, -S9); and 10, 30, 

50, and 70 μg/mL (48 hrs, -S9). No positive results [incidence of cells with structural 

aberrations (excluding gaps) >=10%] or dose-dependent increases in the percentage of cells with 

structural aberrations (excluding gaps) were observed at any concentration after exposure for 6 

hours (±S9), 24 hours (-S9), or 48 hrs (-S9). Additionally, the incidence of polyploidy was 

similar to controls at all doses under all conditions. The positive controls induced the 

appropriate response in the presence and absence of S9. There was no evidence of structural 

chromosome aberrations induced over background in the presence or absence of S9-

activation. 

This study is classified as acceptable/guideline and satisfies the Guideline requirement (OPPTS 

870.5375, OECD 473) for in vitro mutagenicity (chromosome aberration) data. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, and Quality 

Assurance statements were provided. However, the GLP Compliance statement stated that the 

submitter of this study was neither the sponsor of the study nor conducted it, and does not know 

if it was conducted in accordance with 40 CFR Part 160. 

Mammalian Bone Marrow Chromosome Aberration Test; OPPTS 870.5385

EXECUTIVE SUMMARY:

Micronucleus Assay in Rats; OPPTS 870.5395 

EXECUTIVE SUMMARY: In a bone marrow micronucleus assay (MRID 47447827), 6 or 10 

male Crj:CD(SD)IGS rats dose were treated twice (24 hrs apart) via gavage (10 mL/kg) with 

OH-PT (metabolite of Tolfenpyrad; 99.9% a.i., Lot No. Y000328) in 0.5% carboxymethylcellulose at doses of 0, 5, 10, or 20 mg/kg. Bone marrow cells were harvested at 24 hours after 

the final dosing. Cyclophosphamide (20 mg/kg) administered once via gavage served as the 

positive control. 

At 20 mg/kg, one rat was found dead during the observation period (no further details were 

provided). Significant decreases (p<0.05) in incidence of PCEs (%) were observed in all 

treatment groups (decr 10-22%) compared to controls, indicating that the test material inhibited 

the growth of bone marrow cells. No treatment-related increases in the MPCE frequency were 

observed in any treatment group when compared to controls. The positive control induced the 

appropriate response. There was no significant increase in the frequency of micronucleated 

polychromatic erythrocytes in bone marrow after any treatment time. 

However, the study is not complete because female rats were not tested and no justification was 

provided to waive the requirement for both sexes. 

 

This study is classified as unacceptable/guideline and does not satisfy the guideline requirement 

(OPPTS 870.5395; OECD 474) for in vivo cytogenetic mutagenicity data. Nevertheless, the 

study can be upgraded if a rationale for testing only males can be provided. 
Page 63 of 71 

 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, and Quality 

Assurance statements were provided. However, the GLP Compliance statement stated that the 

submitter of this study was neither the sponsor of the study nor conducted it, and does not know 

if it was conducted in accordance with 40 CFR Part 160. 

Acute Neurotoxicity Study; OPPTS 870.6200

EXECUTIVE SUMMARY: In an acute neurotoxicity study (MRID 47447831), OMI-88 

(Tolfenpyrad; 99.5% a.i.; Lot # 365-65A) in corn oil was administered once via gavage 

(5 mL/kg) to 10 Sprague-Dawley rats/group at dose levels of 0, 20, 40, or 60 mg/kg in males and 

0, 10, 20, or 40 mg/kg in females, and the animals were observed for up to 14 days post-dosing. 

Neurobehavioral assessment (functional observational battery [FOB] and motor activity testing) 

was performed on 10 rats/sex/group at pre-dosing and Days 1 (approximately 6 hours postdosing; estimated time of peak effect), 8, and 15. At study termination, 5 rats/sex/group were 

anesthetized and perfused in situ for neuropathological examination. The tissues from the 

perfused animals in the control and high-dose (60 mg/kg males and 40 mg/kg females) groups 

were subjected to histopathological evaluation of brain and peripheral nervous system tissues. 

Acceptable positive control data were provided. 

No compound-related effects were observed in FOB parameters, motor activity, brain weights, or 

gross or neuropathology in either sex. 

In the 40 mg/kg males, transient decreases (decr 8-9%) in body weight were noted at Days 2-4, 

and body weight gains were decreased by 30% during Week 1. Despite increases (not 

statistically significant, NS) in body weight gain (incr 11%) during Week 2, overall (Days 1-15) 

body weight gains remained decreased by 9% at this dose. On Days 1-2, decreases were 

observed in both absolute (decr 76%) and relative (decr 75%) food consumption. The Sponsor 

stated that due to an error, only 5 of the 10 feed values for the males were recorded on Day 1 and 

none of the feed values were recorded on Day 2. Therefore, food consumption during the first 

few days of the study cannot be definitively evaluated for the males. However, because similar 

decreases in food consumption were observed in the treated females during Days 1-2, the 

reviewers considered these findings in the males to be indicative of a treatment-related effect. 

In the 60 mg/kg males, the following treatment-related clinical signs (# affected/10 treated vs. 

0/10 controls; unless otherwise stated) were observed: mild to severe dehydration (9 treated vs. 

1 control); scant feces (6); soft or liquid feces (3); and chromorhinorrhea (3). Body weights 

were decreased throughout the post-dosing period compared to controls, and were significantly 

decreased by 7-16% on Days 2-12. Body weight gains were decreased by 76% during Week 1, 

and despite increases (NS) in body weight gain (incr 33%) during Week 2, overall body weight 

gains remained decreased by 19% at this dose. On Days 1-2, decreases were observed in both 

absolute (decr 85%) and relative (decr 84%) food consumption. 

Effects in the 20 mg/kg males were limited to a minor transient decrease (decr 6%) in body 

weight on Day 2, and decreases in absolute (decr 64%) and relative (decr 63%) food 
Page 64 of 71 

consumption on Days 1-2. However, body weight gain and both absolute and relative food 

consumption values for Weeks 1 and 2, and the overall study were similar to controls. 

The systemic LOAEL in males was 40 mg/kg, based on decreased body weight, body weight 

gain, and absolute and relative food consumption. The systemic NOAEL in males is 20 

mg/kg.

In the 10 mg/kg females, body weight gain was decreased by 46% during Week 1 and by 30% 

during the overall (Days 1-15) study. Absolute and relative food consumption were both 

decreased by 30% on Days 1-2. 

In the 20 mg/kg females, transient decreases (decr 6-12% in body weight were noted at Days 2-

7. Body weight gains were decreased by 61% during Week 1. Despite an increase (NS) in body 

weight gain (incr 17%) during Week 2, overall body weight gain remained decreased by 26% in 

this group. Decreases were noted in both absolute (decr 44%) and relative (decr 41%) food 

consumption on Days 1-2. During Week 2, absolute and relative food consumption were similar 

to or increased compared to controls. Overall absolute and relative food consumption were 

similar to controls. 

At 40 mg/kg, one female rat (#27409) was found dead on Day 4. The following treatmentrelated clinical signs (# affected/10 treated vs. 0/10 controls) were observed: mild to severe 

dehydration (8) and urine-stained abdominal fur (7). Body weights were decreased throughout 

the post-dosing period compared to controls, and were significantly decreased by 8-21% on Days 

2-13. During Week 1, body weight gains were decreased by 136%, as this group actually lost 

weight (-7.9 g treated vs. 21.7 g controls). Despite an increase in body weight gain (incr 90%) 

during Week 2, overall body weight gain remained decreased by 35% in this group. Decreases 

were noted in both absolute (decr 63%) and relative (decr 62%) food consumption on Days 1-2. 

Although absolute food consumption was similar to controls, and relative food consumption was 

increased by 18% during Week 2, decreases in overall absolute (decr 23%) and relative (decr 

13%) food consumption were observed at this dose. 

The systemic LOAEL in females was 20 mg/kg/day, based on decreases in body weight, 

body weight gain and absolute and relative food consumption. The systemic NOAEL in 

females was 10 mg/kg/day.

The FOB findings (decreases in body weight in the 60 mg/kg males and the 40 mg/kg females on 

Day 8, and the increased appearance score of the 40 mg/kg females on Day 1) were considered 

systemic effects. Motor activity was similar to controls, and no compound-related neurological 

lesions were observed at any dose in either sex. Therefore, no neurological effects were 

observed at any dose in either sex.

The neurotoxicity LOAEL was not observed. The neurotoxicity NOAEL is 60 mg/kg in 

males and 40 mg/kg in females. 

The study is classified as acceptable/guideline and satisfies the guideline requirement (OPPTS 
Page 65 of 71 

870.6200a) for an acute neurotoxicity study in rats. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, Flagging, and 

Quality Assurance statements were provided. 

Subchronic Neurotoxicity Study; OPPTS 870.6200

EXECUTIVE SUMMARY: In a subchronic neurotoxicity study (MRID 47447830), OMI-88 

(Tolfenpyrad, 99.33% a.i., Batch No. 6D-01-2) was administered in the diet to 10 SpragueDawley rats/sex/group at dose levels of 0, 15, 40, or 80 ppm (equivalent to 0/0, 1.0/1.2, 2.7/3.2, 

and 5.4/6.0 mg/kg/day [M/F], respectively) for 13 weeks. Neurobehavioral assessment 

(functional observational battery [FOB] and motor activity testing) was performed using all rats 

at pre-dosing and Weeks 2, 4, 8, and 12. At study termination, 5 rats/sex/group were 

anesthetized and perfused in situ for neuropathological examination. The tissues from the 

perfused animals in the control and 80 ppm groups were subjected to histopathological 

evaluation of brain and peripheral nervous system tissues. Positive control data were not 

provided. 

No compound-related effects were observed in mortality, clinical signs of toxicity, FOB, motor 

activity, ophthalmoscopic parameters, gross pathology, brain measurements, or neuropathology. 

At 80 ppm, body weights (no statistical analyses reported) were decreased throughout the study 

in the males (decr <=5%) and in the females (decr 5-15%). Body weight gains were decreased 

(p<0.05) by 13% in the males during Weeks 0-8, and by 28 and 32% in the females during 

Weeks 0-8 and 8-13, respectively. Overall (Weeks 0-13) body weight gains were decreased by 

8% in the males (NS) and by 29% (p<0.01) in the females. In the females, food consumption 

was decreased (p<0.01) by 17 and 18% during Weeks 1-8 and 9-13, respectively, and by 18% 

overall (Weeks 1-13), and food efficiency was decreased (no statistical analyses reported) by 14 

and 22% during Weeks 1-8 and 9-13, respectively, and by 15% overall (Weeks 1-13). 

No compound-related effects were observed at 15 or 40 mg/kg in either sex. 

The systemic LOAEL was 80 ppm (equivalent to 5.4/6.0 mg/kg/day, M/F) based on 

decreased body weights, body weight gains, and food consumption. The systemic NOAEL 

is 40 ppm (equivalent to 2.7/3.2 mg/kg/day, M/F). 

No neurological effects were observed at any dose in either sex.

The neurotoxicity LOAEL was not observed. The neurotoxicity NOAEL is 80 ppm 

(equivalent to 5.4/6.0 mg/kg/day, M/F). 

The study is classified as acceptable/guideline and satisfies the guideline requirement (OPPTS 

870.6200b) for a subchronic neurotoxicity study in rats. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, Flagging, and 
Page 66 of 71 

Quality Assurance statements were provided. 

Cell Cycle Kinetics Assay in CHL Cells; Non-guideline 

EXECUTIVE SUMMARY: In a cell cycle kinetics assay (MRID 47463707), Chinese hamster 

lung (CHL) cell cultures were exposed to Tolfenpyrad (99.5% a.i.; Lot # 365-65A) in dimethyl 

sulfoxide (DMSO) at concentrations of 0, 5, 7, 8.5, 10, 13, or 15 μg/mL for approximately 3, 6, 

or 24 hours in the absence of S9-activation. The cultures were harvested at 24 hours after 

initiation of treatment. The purpose of this study was to explain the polyploidy observed in a 

previously conducted Chinese hamster lung chromosome aberration study (MRID 47447824; 

reviewed concurrently). 

Severe cell cycle delay was observed at the concentrations analyzed (5, 8.5, and 13 μg/mL) at all 

exposure times (3, 6, and 24 hours). The percentage of cells that completed 2 cell cycles was 

reduced at all concentrations as follows: after 3 hours of treatment (6.5-20.0% treated vs. 80.5% 

controls); after 6 hours of treatment (14.0-33.0% treated vs. 81.5% controls); and after 24 hours 

of treatment (4.0-32.0% treated vs. 66.5% controls). Treatment time was not a factor in cell 

cycle delay. Three hours of exposure was sufficient to arrest the cell cycle with little difference 

noted between the treatment times. Increases in polyploidy compared to controls were observed 

after 6 and 24 hours of treatment. The reviewers agree with the Sponsor that, in the absence of 

S9-activation, Tolfenpyrad causes cell cycle delay after exposure for as little as 3 hours and 

polyploidy after as little as 6 hours exposure. The polyploidy observed in the previous 

chromosome aberration study (MRID 47447824; reviewed concurrently) was likely due to the 

inhibition of cell cycle progression. 

This study is classified as acceptable/non-guideline and provides data that supports cell cycle 

delay as an explanation for the polyploidy observed during in vitro testing. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, Flagging, and 

Quality Assurance statements were provided. 

Metabolism Study-Rat; OPPTS 870.7485 

EXECUTIVE SUMMARY: : In a series of metabolism studies in the rat (MRIDs 47447837, 

47447836, and 47447834), [Pyrazole-3-14C]-OMI-88 or [Tolyl-U-14C]-OMI-88 (tolfenpyrad; Lot 

Nos. CFQ9339A, CFQ9339B, CFQ9338A, and CFQ9338B; radiochemical purity 98.4-99.7%) 

was administered to groups of F344 rats. Mass balance studies were conducted on five rats/sex 

with the following dose groups: in MRID 47447837, (i) a single 1 mg/kg oral gavage dose of 

[PY-14C]-OMI-88 or [TO-14C]-OMI-88 and (ii) a single 20 mg/kg oral gavage dose of [PY-14C]-

OMI-88; or in MRID 47447836, (iii) 14 daily 1 mg/kg oral gavage doses of [PY-14C]-OMI-88 

(males and females) or [TO-14C]-OMI-88 (males only). Blood pharmacokinetic studies were 

conducted on five rats/sex given single 1 or 20 mg/kg oral gavage doses of [PY-14C]-OMI-88 or 

[TO-14C]-OMI-88, or 14 daily 1 mg/kg oral gavage doses of [PY-14C]-OMI-88 (males and 

females) or [TO-14C]-OMI-88 (males only). Tissue distribution and depletion studies were 

performed on fifteen rats/sex/dose group given: (i) a single 1 mg/kg oral gavage dose of [PY-
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14C]-OMI-88 or [TO-14C]-OMI-88; (ii) a single 20 mg/kg oral gavage dose of [PY-14C]-OMI-88; 

or (iii) 14 daily 1 mg/kg oral gavage doses of [PY-14C]-OMI-88 (males and females) or [TO14C]-OMI-88 (males only). Five rats/sex/group were killed at 4 or 12 h for the 1 mg/kg groups, 6 

or 24 h for the 20 mg/kg groups, or 168 h for all groups. Biliary excretion studies were 

conducted on four rats/sex following a single 1 or 20 mg/kg oral gavage dose of [PY-14C]-OMI88. The concentration time-courses of radioactivity in blood and plasma were plotted, the 

concentration and recovery of radioactivity in tissues and excreta were determined. Metabolites 

were identified and quantified in the urine, feces and bile (MRID 47447834). Study design and 

metabolite identification was based on the results of a preliminary mass balance study (MRID 

47447833) and fate study (MRID 47447835). 

There were no differences observed in the blood pharmacokinetic parameters between the [PY14C]- and [TO-14C]-label positions in the single or multiple dose studies. Absorption of the test 

compound was rapid, with radioactivity detected in the blood 0.5 h after administration in the 

single dose study. In animals given a 1 mg/kg dose of [14C]-OMI-88, blood levels of 

radioactivity reached mean maximum concentrations at 2-6 h post-dosing. A biphasic 

elimination was observed. In animals given a 20 mg/kg dose of [14C]-OMI-88, blood levels of 

radioactivity reached a mean maximum concentration at 4-12 post-dosing. Biphasic elimination 

was not observed, suggesting a difference in the blood concentration-time profiles between the 

two doses. However, it was stated that a non-compartment model was used to calculate the 

elimination phase half-lives, due to poor data fit with the compartment model. The area under 

the concentration-time curves (AUC0→∞) generally increased proportionally with dose. In the 

multiple dose study, the blood concentrations of radioactivity tended to plateau after the third 

administration, suggesting there was no bioaccumulation following repeated administration. In 

animals given multiple doses of [PY-14C]-OMI-88, blood levels of radioactivity were 

approximately 2- to 3-fold higher in females than in males, reaching mean maximum 

concentrations at 12 h post-dosing in the females. Males receiving multiple doses of [TO-14C]-

OMI-88 had a maximum blood concentration at 8 h post-dosing, and biphasic elimination was 

observed. 

Total recoveries ranged from 91.3-99.6% of the administered dose (AD) across all groups and in 

both sexes. The test compound was rapidly excreted. In the 1 mg/kg single dose groups, 

approximately 57.1-66.8% AD was eliminated during the first 24 h post-dosing, increasing to 

83.8-85.1% AD at 48 h. In the 20 mg/kg single dose groups, excretion was somewhat slower, 

with 26.1-30.3% AD eliminated during the first 24 h post-dosing, increasing to 55.2-70.3% AD 

at 48 h. Feces were the predominant route of excretion. Across all single dose groups, 88.2-

93.2% AD was excreted in the feces, and 1.7-3.0% AD was eliminated in the urine. There were 

no differences between the sexes at either dose. Negligible amounts of radioactivity were 

recovered in the expired air and cage wash, both accounting for ≤0.1% AD. Administration of 

repeated daily doses had no effect on the route of excretion or the extent of recovery. Excretion 

approached steady-state by the fourth administration of the test compound. In the bile ductcannulated rats at 48 h post-dosing, the majority of radioactivity was excreted in the bile (51.3-

69.5% AD), with minor amounts eliminated in the feces (3.5-8.3% AD) and urine (0.7-3.0% 

AD), indicating that bile was the primary route of excretion for the absorbed test material. 

Absorption (defined as radioactivity found in the bile, urine, cage wash, and carcass) was greater 
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in males (72.8-77.8% AD) than in females (57.9-69.4% AD). Females also had more 

radioactivity remaining in the gastrointestinal tract, and the amount remaining increased with 

dose. 

The test compound did not distribute into the red blood cells; concentrations of radioactivity in 

plasma were never lower than those in whole blood in all groups. Generally, the highest 

concentrations of radioactivity were observed in the liver, kidney, brown fat and heart; a 

redistribution that also included white fat, bone marrow and skin was noted over time. Brown 

fat radioactivity concentrations were higher in females than in males. Radioactivity 

concentrations dropped substantially from 12 to 168 h post-dosing. 

Tolfenpyrad was metabolized by oxidation (Pt-CA, OH-PT and OH-PT-CA), followed by 

conjugation (glucuronide, sulfate, asparagines or taurine). The primary metabolite, 4-[4-[(4-

chloro-3-ethyl-1-methylpyrazol-5-yl)carbonylaminomethyl] phenoxy]benzoic acid (PT-CA), was 

present in the feces at 9.0-36.2% AD. PT-CA was also found in plasma, liver, kidney, and fat 

(<5%), and along with taurine-conjugated and hydroxylated forms, was also found in the bile at 

4.6-22.3%, and in the feces and urine of bile duct-cannulated rats. Parent was identified in the 

feces at 0.3-14.8%, and the amount decreased with time (4.1-14.8% at 0-24 h vs. 0.3-3.0% at 24-

48 h). The other identified fecal metabolites present at >5%AD were 4-[4-[(4-chloro-1-methyl3-(1-sulfoxyethyl)pyrazol-5-yl) carbonylaminomethyl]phenoxy]benzoic acid (Sul-OH-PT-CA) 

and 4-[4-[(4-chloro-3-(1-hydroxyethyl)-1-methylpyrazol-5-

yl)carbonylaminomethyl]phenoxy]benzoic acid (OH-PT-CA). In bile duct-cannulated rats, 

parent was found in small amounts in bile (0.1-0.4%) compared to feces (2.4-6.4%), suggesting 

that the parent indentified in feces was passing through the gastrointestinal tract unabsorbed. As 

bile was removed from the gastrointestinal tract of the bile duct-cannulated rats, it was 

considered that the PT-CA in the feces of these animals was formed by the action of 

enterobacteria in the gut. Parent was not found in the urine, plasma, liver, kidney or fat, 

particularly at tmax, indicating that parent was rapidly metabolized in the liver. A total of nine 

urinary metabolites were isolated and six were identified; however, none were present at >0.9% 

AD. Urinary metabolites were a mixture of cleavage products of the C-N bond of the 

benzylamine moiety, oxidation on the side chains of both radiolabeled rings, and conjugates, 

suggesting a complex metabolic profile. 

These metabolism studies are collectively classified acceptable/guideline and when reviewed 

together satisfy the guideline requirement for a Tier 1 metabolism study [OPPTS 870.7485, 

OECD 417] in rats. 

COMPLIANCE: Signed and dated Data Confidentiality, GLP Compliance, and Quality 

Assurance statements were provided. The Submitter of the study stated that they were neither 

the Sponsor of the study nor conducted it, and did not know if it had been conducted in 

accordance with 40 CFR Part 160. However, except for MRID 47447833, the study reports 

contained a statement from the Kashima Laboratory manager that the study was conducted 

according to US EPA 1989 GLP standards under FIFRA. 

Dermal Penetration Study-Rat; OPPTS 870.7600
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EXECUTIVE SUMMARY: In a dermal penetration study (MRID 47447839), [Pyrazole-14C] 

Tolfenpyrad (≥92.6% radiochemical purity; Batch No. 1 [Code CFQ14881]) was applied to the 

shaved skin (10.5 cm2

) of Sprague Dawley rats. Actual doses of 0.91, 8.41, or 99.90 μg/cm2 skin 

(0.1, 1, or 10 g/L formulations, respectively) were applied to the skin of each rat in volumes of 

10 μl/cm2 skin. Four males/dose/time point were tested using exposure durations and 

termination times of 0.5, 1, 2, 4, 10, or 24 hours post-administration. 

Analytical recoveries were 89.0-95.6% AD. Very little of the applied dose was actually 

absorbed at any concentration (6.32-12.9% AD) at 24 hours post-dosing. The absorbable dose 

was 31.6-33.5% in the 0.1 and 1 g/L groups and 13.6% in the 10 g/L group. Most of the dose 

was not absorbed (47.8-51.0% in the 0.1 and 1 g/L groups and 71.8% in the 10 g/L group. The 

greatest amount absorbed (12.9%) and either absorbed or absorbable (44.5%) was noted in the 1 

g/L group. The amount found in the skin was similar from 0.5-24 hours post-dose at 0.1 and 1 

g/L (24.2-33.5% AD) and at 10 g/L (8.36-17.1% AD). Absorption continued throughout the 24 

hour post-dosing period. In each group, the majority of the dose was isolated in the skin wash 

(sponges) and spreader (not absorbed), and substantial amounts were also isolated in the treated 

skin (absorbable dose). 

Maximum counts per gram were observed as follows: (i) at 0.1 g/L: liver (2930 dpm/g at 24 

hours), kidney (3049 dpm/g at 24 hours), and adrenals (2904 dpm/g at 2 hours); (ii) at 1 g/L: 

heart (35,024 dpm/g at 10 hours), liver (42,371 dpm/g at 24 hours), kidney (29,915 dpm/g at 10 

hours), and fat at 24 hours (20,031 dpm/g); and (iii) at 10 g/L, fat (24,119 dpm/g at 24 hours), 

heart (19,613 dpm/g at 24 hours), kidney (12,566 dpm/g at 24 hours), and liver (22,806 dpm/g at 

24 hours). Concentrations were 2177 dpm/g in the adrenals as soon as 0.5 hours post-dose in the 

0.1 g/L group. Excretion of the absorbed dose via the urine was noted at all time points, but 

minimal amounts were found in the feces until 24 hours post-dose. 

Given the uncertainty regarding deposition under actual field conditions, it is considered 

appropriate to derive an estimate of dermal absorption based on the results from the mid-dose 

group (1 g/L; actual dose 8.4 μg/cm2

 skin), as percent dermal absorption was greatest at this dose 

level. Based on the likely worker exposure time frame, it is considered most appropriate to 

adopt the dermal absorption value calculated for the group of animals for which the skin site was 

washed after 10 hours. Because absorption continued to occur throughout the study, the 

absorbable dose should also be considered in a conservative estimate of absorption. At 10 hours 

in the 1 g/L group, the absorbable and absorbed dose accounted for 36.5% of the applied dose. 

Consistent with the tier approach to risk assessment, if a more refined estimate of dermal 

absorption is necessary to obtain adequate margins of exposure, further analysis of the 

toxicokinetics may yield a more appropriate value to use in the occupational risk assessment 

(e.g., maximum body loads at each dose). 

This study is classified as acceptable/guideline and satisfies the guideline requirements (OPPTS 

870.7600; OECD none) for a dermal penetration study in rats. 
Page 70 of 71 

COMPLIANCE: Signed and dated GLP Compliance, Quality Assurance, and Data 

Confidentiality statements were provided. 

In Vitro Metabolism; Non-guideline

EXECUTIVE SUMMARY: This study was performed to characterize oxidative metabolites in 

the initial phase of metabolism that are supposed to be intermediary metabolites in vivo in 

mammals and to extrapolate obtained results to main metabolic reactions in plants. OMI-88 

(Tolfenpyrad) in ethanol was incubated with S9 for 3 hours. The incubation was terminated by 

extraction with acetonitrile. Extracts of incubations with unlabeled OMI-88 (0.1 mg/mL; 99.8% 

a.i.; Lot no. 6D-01-1) were analyzed to determine the molecular weights (by LC-MS) and 

structures of the HPLC-isolated metabolites through GC-MS, LC-MS/MS, and 1

H-NMR. 

Extracts of incubations with [Tolyl ring-U-14C] OMI-88 (0.01 mg/mL; 98.8% radiochemical 

purity; Lot no. CFQ 9338) or [Pyrazole-3-14C] OMI-88 (0.01 or 0.1 mg/mL; 99.3% 

radiochemical purity; Lot no. CFQ 9339) were analyzed by HPLC to quantify the metabolites 

present. Quantifying the metabolites from these incubations allowed the comparison of 

metabolism based on two different radiolabel positions in the test compound and two different 

quantities of test compound incubated with S9. Additionally, the metabolic profiles would 

determine if cleavage between the bonds of the pyrazole and tolyl rings occurs during the 

metabolism of the test compound. 

Total recovery was 91.0-108.1% of the radioactivity added to the incubations, of which the 

parent compound accounted for 10.2-12.4%. Only 1.4-1.9% of the radioactive residues were 

found in unidentified compounds; the remaining approximately 88% of the isolated metabolites 

were identified. In addition to the parent, a total of 17 metabolites were identified. The primary 

metabolite was OH-PT-CA (24.5-32.4%); other major metabolites included PT-CA (13.4-

16.2%), CO-PT-CA (9.3-13.2%), OH-PT (7.6-8.4%), PT-OH (6.7-7.7%), and OH-PT-OH (3.8-

5.3%). The other metabolites were present at <5% of the total incubation dose. 

The metabolic profiles were generally similar both qualitatively and quantitatively, regardless of 

the radiolabel position or the amount of radiolabled compound added (0.1 or 1.0 mg) to the 

incubation with S9. The only exceptions were that OH-PAM and CO-PAM were minor 

metabolites exclusive to incubations with [PY-14C] OMI-88, while OH-T-CA and CA-T-CA 

were minor metabolites exclusive to incubations with [TO-14C] OMI-88. These metabolites 

indicate that cleavage of the bonds between the pyrazole and tolyl rings can occur, but that this is 

only a minor metabolic pathway (5-6%). 

The main metabolic pathways included the oxidations of the methyl moiety of T-CH3 and ω-1 

carbon of CH3CH2-P. The oxidation of these two carbons resulted in the formation of the 

hydroxylated metabolites PT-OH, OH-PT, and OH-PT-OH. Further oxidation leads to the 

metabolites PT-CHO, PT-CA, OH-PT-CA, CO-PT, CO-PT-OH, and CO-PT-CA. Other 

metabolic pathways include the bond cleavage of the amide and methylene moieties, the 

demethylation of N-CH3, or the formation of the vinyl group after hydroxylation of CH3CH2-P. 

This in vitro study is classified acceptable/non-guideline and determined the metabolites of 
Page 71 of 71 

Tolfenpyrad radiolabeled in two different positions and incubated with S9 at two different 

quantities. Although the stated purpose was to also extrapolate these results to the main 

metabolic reactions in plants, no information was provided in this study to allow such 

extrapolation. 

COMPLIANCE: A signed and dated Data Confidentiality statements was provided. A signed 

and dated GLP Compliance was provided that states the submitter of this study does not know 

whether it was conducted in accordance with 40 CFR Part 160. A Quality Assurance statement 

was not provided.