EPA REGISTRATION DIVISION - COMPANY NOTICE OF FILING FOR PESTICIDE PETITION 

EPA Registration Division contact: Sidney Jackson, (703) 305-7610

Docket I.D. Number: EPA-HQ-OPP-2015-0035

Interregional Research Project Number 4 (IR-4)

Pesticide Petition Number: PP# 4E8334 

EPA has received a pesticide petition (4E8334) from Interregional Research Project Number 4 (IR-4), IR-4 

Project Headquarters, Rutgers, The State University of New Jersey, 500 College Road East, Suite 201 W, 

Princeton, NJ 08540 in cooperation with Valent U.S.A. Corporation, 1600 Riviera Avenue, Suite 200, 

Walnut Creek, California 94596, 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 tolerances for 

residues of the herbicide clethodim, including its metabolites and degradates, determined by measuring 

only the sum of clethodim, 2-[(1E)-1-[[[(2E)-3-chloro-2-propenyl]oxy]imino]propyl]-5-[2-

(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one, and its metabolites containing the 5-(2-

ethylthiopropyl)cyclohexene-3-one and 5-(2-ethylthiopropyl)-5-hydroxycyclohexene-3-one moieties and 

their sulphoxides and sulphones, calculated as the stoichiometric equivalent of clethodim, in or on the 

raw agricultural commodities: Onion, bulb subgroup 3-07A at 0.2 parts per million (ppm), Vegetable, 

fruiting group 08-10 at 1.0 ppm, Fruit, pome group 11-10 at 0.2 ppm, Fruit, stone group 12-12 at 0.2 

ppm, Berry, low growing, subgroup 13-07G, except cranberry at 3.0 ppm, Rapeseed subgroup 20A, 

except flax at 0.5 ppm, Sunflower subgroup 20B at 5.0 ppm, Cottonseed subgroup 20C at 1.0 ppm and 

Stevia at 12 ppm. Upon establishment of the aforementioned tolerances, IR-4 proposes to remove 

established tolerances for residues of the herbicide clethodim in or on the raw agricultural commodities: 

canola at 0.5 ppm, cotton, undelinted seed at 1.0 ppm, onion, bulb at 0.2 ppm, strawberry at 3.0 ppm, 

and sunflower, seed at 5.0 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 support granting of the petition. 

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

A. Residue Chemistry

1. Plant metabolism. The metabolism of clethodim is adequately understood for the purpose of 

granting the proposed tolerances.

2. Analytical method. Practical analytical methods for detecting and measuring levels of clethodim 

have been developed and validated in/on all appropriate agricultural commodities and respective 

processing fractions. The LOQ of clethodim in the methods is 0.2 ppm, which will allow monitoring of 

food with residues at the levels proposed for the tolerances.

3. Magnitude of residues. Residue data has been submitted which adequately support the requested 

tolerances.
B. Toxicological Profile

A summary of the toxicological endpoints for clethodim used for human risk assessment is discussed in 

EPA’s January 30, 2014 Clethodim Preliminary Risk Assessment for Registration Review. As noted the 

toxicology database for clethodim is complete and sufficient for selecting toxicity endpoints and points 

of departure (PODs) for risk assessment. The acute reference dose (aRfD) of 1 mg/kg/day was calculated 

from the NOAEL from an acute neurotoxicity study and an uncertainty factor of 100X. The chronic 

reference dose (cRfD) of 0.3 mg/kg/day was calculated from the NOAEL from the carcinogenicity study 

in mice and an uncertainty factor of 100X. Clethodim is not carcinogenic so a cancer assessment was 

not performed. The requirement for a subchronic inhalation study was waived (HASPOC, TXR 0056491,

2/20/2013).

C. Aggregate Exposure

1. Dietary exposure.

i. Food. An acute and chronic dietary analysis was conducted to estimate exposure to potential 

clethodim residues in/on all commodities with existing tolerances. As detailed in EPA’s January 30, 2014 

Clethodim Preliminary Risk Assessment for Registration Review, Health Effects Division conducted a 

conservative unrefined assessment including tolerance levels residues and 100% crop treated using 

DEEM version 7.81. The addition of the proposed uses to the approved uses of clethodim is expected to 

make a negligible incremental contribution to the dietary burden and therefore, the risk assessment has 

not been repeated to include these minor uses.

ii. Drinking water. Drinking water concentrations were calculated by the Environmental Fate and 

Effects Division (EFED) using PRZM-GW. The highly conservative maximum screening-level acute and 

chronic EDWCs (1.43 and 1.15 mg/L, respectively) from the alfalfa use pattern were used in the dietary 

assessment. Details can be found in EPA’s January 30, 2014 Clethodim Preliminary Risk Assessment for 

Registration Review.

2. Non-dietary exposure. Clethodim is currently registered for use on several agricultural crops and 

a variety of non-food uses, including residential landscaped areas. Tolerances proposed in the current 

petition do not impact non-dietary exposure. EPA noted in its 2014 Preliminary Risk Assessment for 

Registration Review short term residential exposure to Clethodim may occur from ornamental plants 

beds, landscapes, trees, shrubs and ground cover. The results of the aggregate assessment (food, water 

and residential) indicate that total short-term aggregate margins of exposure (MOEs) are not of concern 

(i.e. an MOE ≥ 100) with baseline attire (shorts, short-sleeved shirt, shoes and socks).

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." EPA does not have, at this time, available data to determine whether clethodim 

has a common mechanism of toxicity with other substances or how to include this pesticide in a 

cumulative risk assessment. For the purposes of this tolerance action, EPA has not assumed that 

clethodim has a common mechanism of toxicity with other substances.
E. Safety Determination

FFDCA section 408 provides that EPA shall apply an additional margin of safety, up to ten-fold, for added 

protection for infants and children in the case of threshold effects, unless EPA determines that a 

different margin of safety will be safe for infants and children. The toxicological database for evaluating 

prenatal and postnatal toxicity for clethodim is complete with respect to current data requirements, and 

there are no special prenatal or postnatal toxicity concerns for infants and children. EPA has concluded 

that reliable data support reduction of the FQPA Safety Factor for protection of infants and children to 

1X.

1. U.S. population. Based on EPA’s January 30, 2014 Clethodim Preliminary Risk Assessment for 

Registration Review, Dietary Risk Estimates (Food + Drinking Water), the acute and chronic dietary (food 

and drinking water) exposure is estimated at 10% and 12% of the acute and chronic Population Adjusted 

Dose (PAD), respectively, for the general U.S. population. Aggregate exposures below 100% of the PAD 

are generally considered to represent a reasonable certainty of no harm to exposed populations. IR-4 

concludes that there is a reasonable certainty that no harm will result to the U.S. population (or any subpopulations) by including the incremental additional exposure resulting from the proposed uses of 

clethodim.

2. Infants and children. Based on EPA’s January 30, 2014 Clethodim Preliminary Risk Assessment for 

Registration Review, Dietary Risk Estimates (Food + Drinking Water), the acute and chronic dietary (food 

and drinking water) exposure is estimated at 29% and 30% of the acute and chronic PAD, respectively, 

for infants <1 year old, the most highly exposed subpopulation. Aggregate exposures below 100% of the 

PAD are generally considered to represent a reasonable certainty of no harm to exposed populations. 

IR-4 concludes that there is a reasonable certainty that no harm will result to the U.S. population (or any 

sub-populations) by including the incremental additional exposure resulting from the proposed uses of 

clethodim.

F. International Tolerances

The U.S. residue definition is harmonized with Codex, but not Canada. Canada’s tolerance expression 

includes clethodim and its metabolites containing the 2-cyclohex-1-enone moiety, but does not include 

the sulphoxides and sulphones.

The following Codex Maximum Residue Limits (MRL) have been established for clethodim: Bean, dry at 

2.0 ppm, Onion, dry bulb at 0.5 ppm, Peanut at 5.0 ppm, Potato at 0.5 ppm, Sugar beet, roots at 0.1 

ppm, Sunflower, seed at 0.5 ppm and Tomato at 1.0 ppm.