Pesticide Petition to Establish Tolerances for Oxathiapiprolin

I. E.I. du Pont de Nemours and Company

PP No. 5F8435

EPA has received a pesticide petition PP No. 5F8435 from E.I. du Pont de Nemours & Company

(“DuPont”), 1007 Market Street, Wilmington, DE 19898, proposing pursuant to section 408 (d) of the 

Federal Food, Drug, and Cosmetic Act, 21 U.S.C. 346a (d), to amend 40 CFR part 180 to establish 

tolerances for residues of oxathiapiprolin, 1-(4-{4-[(5RS)-5-(2,6-difluorophenyl)-4,5-dihydro-1,2-oxazol3-yl]-1,3-thiazol-2-yl}-1-piperidyl)-2-[5-methyl-3-(trifluoromethyl)-1H-pyrazol-1-yl]ethanone in or on 

the following commodities: soybean at 0.01 ppm; sunflower at 0.01 ppm.

EPA has determined that the petition contains data or information regarding the elements set forth in 

section 408 (d) (2) of the FFDCA; however, EPA has not fully evaluated the sufficiency of the submitted 

data at this time or whether the data supports granting of the petition. Additional data may be needed 

before EPA rules on the petition.

A. Residue Chemistry 

1. Plant metabolism. The metabolism of oxathiapiprolin is adequately understood to support the proposed 

tolerances. Studies in grape, lettuce and potato when treated at proposed label rates showed no significant 

metabolites. The metabolism of oxathiapiprolin in plants was similar regardless of the crop or the 

treatment regime. Oxathiapiprolin was the principal residue in most crop fractions at various sampling 

points up to crop maturity. The overall metabolism of oxathiapiprolin in rotated crops (cereals, root 

vegetables, leafy vegetables) was consistent with metabolism seen in the primary crops.

2. Livestock Metabolism. The metabolism of oxathiapiprolin in ruminants and poultry is adequately 

understood to support the proposed tolerances. Lactating goat and monogastric hen metabolism studies 

were conducted. The metabolism of oxathiapiprolin in the rat was, in general, consistent with that of the 

lactating goat (ruminant) and monogastric hen.

3. Analytical method. Adequate analytical methodology, high-pressure liquid chromatography with 

MS/MS detection, is available for enforcement purposes. 

4. Magnitude of residues. Field trials to meet country (Canada, the United States) requirements were 

carried out at exaggerated rates in soybeans and sunflowers. The trials covered a range of locations, 

climates and soil types and the data obtained represent a conservative scenario for the commercial use of 

the oxathiapiprolin-containing product in the major crop growing regions.

The oxathiapiprolin residues from these field trials were below the limit of detection in all soybean and 

sunflower crop commodities. Livestock feeding studies were not conducted.

B. Toxicological Profile

1. Acute toxicity. Based on EPA criteria, technical oxathiapiprolin is classified as acute toxicology 

category IV based on overall results from several studies. This compound is considered acute toxicology 

category IV for acute oral, dermal and inhalation toxicity and eye and skin irritation. Technical 

oxathiapiprolin is not a dermal sensitizer. 
Pesticide Petition to Establish Tolerances for Oxathiapiprolin

No evidence of neurotoxicity was observed in an acute study conducted with oxathiapiprolin in rats. The 

no-observed-effect level (NOEL) and no-observed-adverse-effect-level (NOAEL) in an acute 

neurotoxicity study were 2000 mg oxathiapiprolin/kg bw, which was the highest dose administered in the 

study. 

2. Genotoxicty. Oxathiapiprolin was evaluated in a battery of in vitro and in vivo genetic toxicology 

studies. Negative results were obtained in all studies indicating that oxathiapiprolin does not cause 

genetic damage and, therefore, does not pose a mutagenic hazard.

3. Reproductive and developmental toxicity. No effects on fertility were observed in one- and twogeneration reproduction studies in rats. No effects on development were observed in developmental 

toxicity studies in rats and rabbits. Slight delays in maturation were observed in male rats in the 

reproduction studies, with a NOAEL of 104 mg/kg bw/day. At much higher doses, decreases in offspring 

body weight were also observed.

4. Subchronic toxicity. Short-term oral feeding studies with oxathiapiprolin were conducted in rats, mice 

and dogs with durations of up to 90 days. In addition, two other studies were performed in rats: a 14-day 

oral gavage study (conducted as a part of early discovery) and a 28-day dermal study. No adverse effects 

were observed in any of these studies. In all cases, the NOAELs were greater than or equal to 1000 

mg/kg bw/day. Non-adverse findings observed in these studies were limited to changes in organ weights, 

clinical chemistry parameters and liver cytochrome P450 isozymes.

Oxathiapiprolin showed no evidence of immunotoxicity in a 28-day feeding study in mice. Additionally, no 

indications of a potential for oxathiapiprolin to affect the immune system were noted in the repeated dose 

toxicity studies with rats, mice or dogs. Based on this, oxathiapiprolin does not appear to pose an 

immunotoxic hazard.

Neurotoxicity endpoints were included in the subchronic (90-day feeding) study that tested up to intake 

levels of >1000 mg/kg bw/day in male and female rats. No evidence of neurotoxicity was observed. No 

treatment-related clinical signs indicative of potential neurotoxicity were observed in repeated dose

studies in mice or dogs.

5. Chronic toxicity. Based on the results of chronic feeding studies in rats and mice, oxathiapiprolin was 

not carcinogenic in either species. No indications of chronic toxicity were observed in either study. A 

one-year toxicity study was also conducted in dogs, with no toxicologically relevant findings. Possible 

test substance-related changes in organ weights and clinical chemistry parameters were observed. 

6. Rat metabolism. [

14C]Oxathiapiprolin was investigated in rats after single low and high dose 

administration, and after multiple treatments at low doses. At the low dose (10 mg/kg bw) absorption 

was 31-49%, and declined to 5.4-7.7% at the high dose (200 mg/kg bw). Peak plasma concentrations 

occurred at 0.25-9.5 hours. Plasma 14C residue concentrations showed steady-state kinetics in male and 

female rats after multiple low dose administrations (10 mg/kg bw for 14 days).

Maximum tissue concentrations at Tmax occurred in the liver. Clearance was rapid for liver and other 

tissues by 168 hours after dosing. All tissues at 168 hours, including the carcass, collectively retained 

<0.05% of the dose. The pattern of distribution was similar between sexes and single and multiple dose 

administration. The low percentage and concentration values in tissues indicate very low potential for 

accumulation.
Pesticide Petition to Establish Tolerances for Oxathiapiprolin

Plasma terminal elimination half-lives ranged from 40-51 hours following single or multiple low-dose 

administration. Excretion in urine and faeces was >95% complete by 48 hours after single dosing. The 

pattern of excretion was similar after multiple dosing. Faecal excretion was the primary route of 

elimination (90%). Recovery in urine was much lower (2.5%). Essentially no excretion occurred by 

exhalation.

Oxathiapiprolin metabolism pathways mainly involved hydroxylation at various ring carbons and ring 

opening. Pyrazole-piperidine bridge cleavage followed by further oxidation resulted in pyrazole 

metabolites.

7. Metabolite toxicology. Oxathiapiprolin is considered to be the only molecule of toxicological 

relevance. Toxicology studies conducted with metabolites support this conclusion.

8. Endocrine disruption. No relevant effects were observed on any endocrine tissue in short- and long-term 

studies in rats, mice and dogs to suggest an adverse impact on estrogen or androgen pathways or on steroid 

biosynthesis. The reproduction studies in rats provided sufficient information to fully interpret the effects 

of oxathiapiprolin on reproduction. No observations in that study suggested an adverse effect on 

estrogen. Additionally, investigational studies were conducted that suggest no adverse effects on 

estrogen. The slight delay in maturation observed in male rats in the reproduction studies may be 

exacerbated by weight effects; however, the data suggest that other factors are involved. Investigational 

studies did not reveal any adverse effects on androgens by oxathiapiprolin in rats. 

C. Aggregate Exposure

The residue of concern is parent oxathiapiprolin only. Due to the limited toxicity observed in the 

oxathiapiprolin toxicological database, HED previously determined that toxicological endpoints and 

points of departure (POD) were not required for oxathiapiprolin. 

1. Dietary exposure

While dietary exposure to oxathiapiprolin may occur through food and drinking water, no risks of 

concern are anticipated due to the lack of toxicity at anticipated human exposure levels from the 

proposed new use for oxathiapiprolin as a seed treatment for soybean and sunflower seed.

2. Non-dietary exposure. Since there are no residential or home uses non-dietary exposure has not been 

assessed.

D. Cumulative Effects

A determination has not been made that oxathiapiprolin has a common mechanism of toxicity with other 

substances. Oxathiapiprolin does not appear to produce a common toxic metabolite with other 

substances. A cumulative risk assessment was, therefore, not performed for this analysis.

E. Safety Determination

1. U.S. population. While dietary exposure to oxathiapiprolin may occur through food and drinking 

water, no risks of concern are anticipated due to the lack of toxicity at anticipated human exposure levels 

from the proposed new use for oxathiapiprolin as a seed treatment for soybean and sunflower seed. Thus, 
Pesticide Petition to Establish Tolerances for Oxathiapiprolin

there is a reasonable certainty that no harm will result to the general population from the aggregate 

exposure to oxathiapiprolin. No additional safety factors are warranted.

2. Infants and children. While dietary exposure to oxathiapiprolin may occur through food and drinking 

water, no risks of concern are anticipated due to the lack of toxicity at anticipated human exposure levels 

from the proposed new use for oxathiapiprolin as a seed treatment for soybean and sunflower seed. Thus, 

there is a reasonable certainty that no harm will result to infants and children from the aggregate 

exposure to oxathiapiprolin. No additional safety factors are warranted.

F. INTERNATIONAL TOLERANCES

No tolerances have been established to date for oxathiapiprolin on soybean or sunflower.