EPA REGISTRATION DIVISION COMPANY NOTICE OF FILING FOR 

PESTICIDE PETITIONS PUBLISHED IN THE FEDERAL REGISTER 

EPA Registration Division contact: Mr. Jim Tompkins, 703-305-5697 

Valent U.S.A. Corporation 

8F7509 

 EPA has received a pesticide petition (8F7509) from Valent U.S.A. 

Corporation, 1600 Riviera Avenue, Suite 200, Walnut Creek, CA 94596 (EPA 

Company #59639) proposing, pursuant to section 408(d) of the Federal Food, Drug, and 

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

tolerance for residues of the herbicide chemical bispyribac-sodium, benzoic acid, 2,6-

bis-((4,6-dimethoxy-2-pyrimidinyl)oxy)-, sodium salt, and its des-methyl metabolite, 

sodium 2-(4,6-dimethoxypyrimidin-2-yl)oxy-6-(4-hydroxy-6-methoxypyrimidin-2-yl) 

benzoate in or on the raw agricultural commodity freshwater fish tissue at at 0.01 part 

per million (ppm). EPA has determined that the petition contains data or information 

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

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

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

petition.

A. Residue Chemistry

 1. Plant metabolism. The metabolism of bispyribac-sodium in crop plants has 

been reported previously and is adequately understood for the purpose of granting 

the proposed tolerances. 

 2. Analytical method. Practical analytical methods for detecting and 

measuring levels of bispyribac-sodium and its metabolites have been developed and 

validated in/on all appropriate plant and animal matrices. An analytical method for 

detecting bispyribac-sodium and its des methyl metabolite (KIH 2023) in fish tissue 

has been submitted with this petition. The LOQ of bispyribac-sodium and the 

metabolite in the analytical method for fish tissue is 10 ppb (0.01 ppm), which will 

allow monitoring for residues at the levels proposed for the tolerances. 

 3. Magnitude of residues. A 28-day magnitude of the residue study was 

conducted with bluegill sunfish, Lepomis macrochirus and channel catfish, Ictalurus 

punctatus. The study was performed at 2X the proposed application rate for 

bispyribac-sodium aquatic use to assess the potential accumulation of bispyribacsodium and its des-methyl metabolite in fish tissue. Total bispyribac-sodium and 

des-methyl metabolite residues in bluegill and catfish tissue at 4 hours after 

application were measured at <0.01 ppm. Total bispyribac-sodium residues in 
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bluegill and catfish tissue measured at day 1, 3, 7, 14, 21, and 28 days after dosing 

were all <0.01 ppm. Therefore, accounting for the 2X study dose rate, adequate 

data exist to support the proposed tolerance of the combined residue of bispyribacsodium parent and the des-methyl metabolite of 0.01 ppm in freshwater fish tissue.

B. Toxicological Profile

 1. Acute toxicity. The toxicological profile and toxicological endpoints for 

bispyribac-sodium supporting this petition for tolerances was published in the 

Federal Register on September 18, 2001 (Volume 66, Number 181. No acute toxicity 

endpoints of concern were identified for bispyribac-sodium.

 2. Genotoxicty. The toxicological profile and toxicological endpoints for 

bispyribac-sodium supporting this petition for tolerances was published in the 

Federal Register on September 18, 2001 (Volume 66, Number 181. No acute toxicity 

endpoints of concern were identified for bispyribac-sodium. 

 3. Reproductive and developmental toxicity. The toxicological profile and 

toxicological endpoints for bispyribac-sodium supporting this petition for tolerances 

was published in the Federal Register on September 18, 2001 (Volume 66, Number 

181. No acute toxicity endpoints of concern were identified for bispyribac-sodium.

 4. Subchronic toxicity. The toxicological profile and toxicological endpoints for 

bispyribac-sodium supporting this petition for tolerances was published in the 

Federal Register on September 18, 2001 (Volume 66, Number 181. No acute toxicity 

endpoints of concern were identified for bispyribac-sodium. 

 5. Chronic toxicity. The toxicological profile and toxicological endpoints for 

bispyribac-sodium supporting this petition for tolerances was published in the 

Federal Register on September 18, 2001 (Volume 66, Number 181. No acute toxicity 

endpoints of concern were identified for bispyribac-sodium.

 6. Animal metabolism. The toxicological profile and toxicological endpoints for 

bispyribac-sodium supporting this petition for tolerances was published in the 

Federal Register on September 18, 2001 (Volume 66, Number 181. No acute toxicity 

endpoints of concern were identified for bispyribac-sodium. 

 7. Metabolite toxicology. The toxicological profile and toxicological endpoints 

for bispyribac-sodium supporting this petition for tolerances was published in the 

Federal Register on September 18, 2001 (Volume 66, Number 181. No acute toxicity 

endpoints of concern were identified for bispyribac-sodium.

 8. Endocrine disruption. The toxicological profile and toxicological endpoints 

for bispyribac-sodium supporting this petition for tolerances was published in the 

Federal Register on September 18, 2001 (Volume 66, Number 181. No acute toxicity 

endpoints of concern were identified for bispyribac-sodium.
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C. Aggregate Exposure

 1. Dietary exposure. For the aggregate assessment, average daily dietary 

exposures (i.e., estimates of chronic dietary exposure) are aggregated with 

swimming exposures from the day of exposure (i.e., assuming 45 ppb bispyribacsodium in water). Residential dietary and post-application recreational swimming 

exposures were aggregated and assessed against the short- and intermediate-term 

oral endpoint of 100 mg/kg/d. Total estimated aggregate exposures are 0.000560 

mg/kg/d for adult females and 0.00106 mg/kg/d for children. Corresponding MOEs 

are 178,000 for adult females and 94,400 for children. Exposure estimates for 

drinking water were made based upon the drinking water EEC’s calculated using 

the proposed aquatic use pattern of bispyribac-sodium. MOE’s were all greater 

than 100, so it is concluded that anticipated aggregate exposures to bispyribacsodium as conservatively estimated here are not of concern.

 i. Food. Acute - No acute toxicity endpoint of concern was identified for 

bispyribac-sodium, therefore, no acute dietary risk assessment was performed. b 

Chronic - Chronic dietary exposure for the general U.S. population is 0.000301 

mg/kg/d (0.3% cRfD). Thus, chronic dietary exposures resulting from the proposed 

aquatic use of bispyribac-sodium are not of concern. 

 ii. Drinking water. A modified tier I rice model utilized previously by EPA 

was used as the basis for estimating drinking water EECs resulting from the 

proposed bispyribac-sodium aquatic uses. The rice model was modified to calculate 

initial EECs for water bodies of several depths following either surface or 

subsurface applications of bispyribac-sodium resulting from the proposed use 

patterns, including a single application and four applications at the minimum 

retreatment interval of 30 days. The drinking water EECs are based on total 

bispyribac-sodium residues (parent bispyribac-sodium plus the des-methyl 

degradate). The estimated maximum peak concentration is 60 ppb, assuming a 0.3 

meter deep water body treated with four surface applications at 0.1 lb ai per surface 

acre. When four surface applications are made at 0.1 lb ai per surface acre with a 

30-day interval, the annual average concentration is estimated to be 14 ppb for a 0.3 

meter deep water body. The estimated long-term residue in treated water bodies 

(~14 ppb) is greater than EPA’s surface water estimate of 0.32 ppb for the existing 

rice use, so the chronic dietary assessment includes residues of 14 ppb. Potential 

residues of bispyribac-sodium in drinking water account for the vast majority of 

human dietary exposure, contributing 98% of exposure for the U.S. population and 

98.5% of exposure for all infants. 

 2. Non-dietary exposure. Bipsyribac-sodium is intentionally added to water 

bodies at concentrations of up to 45 ppb. People swimming in treated water bodies 

may therefore be exposed to bispyribac-sodium. Exposures for recreational 

swimming have been modeled using SWIMODEL. Dermal, aural and inhalation 

exposures were negligible. Total daily exposure on the day of application was 
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0.000281 mg/kg/d for adult females and 0.000767 mg/kg/d for children. Assessed 

against the short- and intermediate-term incidental oral toxicity endpoint of 100 

mg/kg/d, MOEs were 356,000 and 130,000 for adult females and children, 

respectively. Thus, conservatively estimated exposures to bispyribac-sodium 

resulting from potential swimming exposure to the maximum application rate on 

the day of treatment are not of concern. 

D. Cumulative Effects

 Section 408(b)(2)(D)(v) requires that the Agency must consider "available 

information" concerning the cumulative effects of a particular pesticide's residues 

and "other substances that have a common mechanism of toxicity." Available 

information in this context include not only toxicity, chemistry, and exposure data, 

but also scientific policies and methodologies for understanding common 

mechanisms of toxicity and conducting cumulative risk assessments. Although the 

Agency has some information in its files that may turn out to be helpful in 

eventually determining whether a pesticide shares a common mechanism of toxicity 

with any other substances, EPA does not at this time have the methodologies to 

resolve the complex scientific issues concerning common mechanism of toxicity in a 

meaningful way for most registered pesticides.

E. Safety Determination

 1. U.S. population. i. Acute Risk. No assessment performed. ii. Chronic Risk. 

Chronic dietary (food + drinking water) exposure for the general U.S. population is 

0.000301 mg/kg/d (0.3% cRfD). Thus, there is no concern for chronic risk in the US 

population from dietary exposure to bispyribac-sodium.

2. Infants and children. i. Safety Factor for Infants and Children. EPA has 

determined that the special 10x SF to protect infants and children should be 

removed [Federal Register of March 31, 2004 (69 FR 16823) (FRL-7351-2)]. The 

FQPA factor has been removed because developmental toxicity and offspring 

toxicity NOAELs/LOAELs are well characterized; there is a well-defined doseresponse curve for the cardiovascular effects; and the endpoints of concern used for 

overall risk assessments are appropriate for the route of exposure and population 

subgroups. 

 ii. Acute Risk. No acute endpoint has been identified for infants and 

children. Therefore, no assessment of acute exposure from food to this subgroup is 

required. 

iii. Chronic Risk. Chronic dietary exposures to bispyribac-sodium range 

from 0.000421 mg/kg/d (0.4% cRfD) for children aged 3-5 years old to 0.000982 

mg/kg/d (1.0% cRfD) for all infants. Thus, chronic dietary exposures to infants and 

children resulting from the proposed aquatic use of bispyribac-sodium are not of 

concern. 

F. International Tolerances
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 Bispyribac-sodium has not been evaluated by the JMPR and there are no 

Codex Maximum Residue Limits (MRL) for bispyribac-sodium. MRL values have 

been established on rice grain to support the use of bispyribac-sodium on rice in the 

following countries: 

US 0.02 ppm 

Mexico 0.02 ppm 

Japan 0.1 ppm 

Korea 0.1 ppm 

Brazil 0.01 ppm 

Malaysia: 0.05mg/kg Rice (milled or polished) 

Russia: 0.1mg/kg