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EPA REGISTRATION DIVISION COMPANY NOTICE OF FILING FOR 

PESTICIDE PETITIONS PUBLISHED IN THE FEDERAL REGISTER 

EPA Registration Division contact: Laura Nollen, (703) 305-7390

Interregional Research Project Number 4 (IR-4)

Petition Number (PP# 0E7779)

EPA has received a pesticide petition, PP# 0E7779, from IR-4, 500 College 

Road East, Suite 201 W, Princeton, NJ 08540 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 dicamba (3,6-dichloro-o-anisic 

and its metabolite 3,6-dichloro-5-hydroxy-o-anisic acid (5-OH dicamba) in or on the 

raw agricultural commodity teff, forage at 90.0 parts per million (ppm); teff, grain at 6.0

ppm; teff, straw at 30.0 ppm; and teff, hay at 40.0 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 nature of dicamba residues in dicamba is adequately 

understood. The primary route of metabolism of dicamba is by demethylation to 

form DCSA and subsequent hydroxylation to form the minor metabolite DCGA 

(3,6-dichlorogentisic acid). DCSA and its glucose conjugates are the major 

metabolites from both pre and postemergence applications of dicamba. Parent 

dicamba can be expected to comprise a significant portion of the residue in both teff 

forage and hay for postemergence applications. DCGA and its conjugates can be 

expected to be present only at low levels in teff forage and hay. EPA has previously 

determined that the dicamba residues of concern are dicamba, DCSA, and 5-OH 

dicamba. Based on the results of metabolism studies, the current tolerance 

expression is adequate for teff forage and hay.

2. Analytical method. Adequate enforcement methods are available for the 

analysis of residues of dicamba and its relevant metabolites in or on plant and 

livestock commodities. Pesticide Analytical Manual (PAM) Vol. II lists appropriate 

analytical methods, based on gas chromatography (GC) with electron capture 

detection (GC/ECD), that are sufficient to provide for the enforcement of proposed 

dicamba tolerances in teff forage, grain, straw and hay.
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3. Magnitude of residues. The proposed tolerances are based on a US EPA 

ChemSAC decision. IR-4 received a request (PR 10195) for the use of dicamba on 

teff. Teff is a small grain grown as a warm season cereal crop and the cultural 

practices are similar to other small grains such as wheat, barley, rye and oats. 

Given that teff and other cereal grains have similar morphological, cultural 

practices, taxonomical characteristics, and share similar pest problems, IR-4 

proposed extrapolating the tolerances for wheat and other grains to tolerances for 

teff. IR-4 also stated that crop group 15 is scheduled to be included in a 2011 crop 

group submission to the EPA, which was confirmed by Bernie Schneider. Bernie 

stated that currently most of the teff is grown in ID and MT. Considering the low 

acreage grown in the US and the similarity to other cereal grains, the ChemSAC 

concurred with the IR-4 proposal for the use of dicamba on teff. In addition, the 

proposed tolerances for dicamba in teff forage and hay will not result in secondary 

residues in meat and milk above the tolerances already published at 40 CFR 

180.227.

B. Toxicological Profile

EPA has previously evaluated available toxicology data on dicamba and 

concluded the data are of sufficient quality and reliability to merit reregistration. 

EPA also found the available data to be adequate to characterize the toxicity of 

dicamba as it relates to human health including variability and sensitivity of major 

subgroups of consumers including infants and children. The nature of dicamba 

toxicity is discussed in the 2006 Registration Eligibility Decision (RED) and as part 

of a recent action to establish tolerances on sweet corn commodities (Federal 

Register: April 2, 2008, Vol. 73, No. 64, p. 17914-18; Petition No. 0E6209; Decision: 

304187; EPA-HQ-OPP-2007-0325).

1. Acute toxicity. As noted in Dicamba RED, 2006 and Decision 304187.

2. Genotoxicity. As noted in Dicamba RED, 2006 and Decision 304187.

3. Reproductive and developmental toxicity. As noted in Dicamba RED, 2006 

and Decision 304187.

4. Subchronic toxicity. As noted in Dicamba RED, 2006 and Decision 304187.

5. Chronic toxicity. As noted in Dicamba RED, 2006 and Decision 304187.

6. Animal metabolism. As noted in Dicamba RED, 2006 and Decision 304187.

7. Metabolite toxicology. Toxicity studies on DCSA and DCGA have been 

conducted to further characterize their toxicity. Overall, only a few minor 

quantitative and qualitative differences in toxicity were observed when comparing 

DCSA, DCGA and dicamba. These data demonstrate that the overall toxicity 

profiles of dicamba and its metabolites, DCSA and DCGA, are substantially similar 

and that neither DCSA nor DCGA present any new or unusual toxicity concerns 
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beyond what has already been considered for parent dicamba. Therefore, existing 

dicamba toxicity endpoints are sufficient to assess potential health risks from 

exposure to DCSA and DCGA metabolites. 

8. Endocrine disruption. Dicamba does not belong to a class of chemicals 

known for having adverse effects on the endocrine system. No effects indicative of 

endocrine disruption have been observed in the various short- and long-term studies 

conducted with various mammalian species.

C. Aggregate Exposure

1. Dietary exposure. Existing tolerances for dicamba residues in meat and 

milk are adequate to support the proposed tolerances of dicamba in teff forage, 

grain, straw and hay. In addition, the proposed new use that supports the teff 

forage, grain, straw and hay tolerances does not result in an increase in estimated 

drinking water exposure beyond what has already been evaluated by EPA. 

Consequently, no incremental dietary (food plus water) exposure to dicamba is 

anticipated from the proposed tolerances, and the most recent EPA dietary 

exposure assessment supporting dicamba tolerances for sweet corn commodities 

(Federal Register: April 2, 2008, Vol. 73, No. 64, p. 17914-18; Petition No. 0E6209; 

Decision: 304187) is adequate to support the proposed tolerances on teff, forage, 

grain, straw and hay.

i. Food. In support of the proposed tolerances for sweet corn commodities, a 

highly conservative acute dietary assessment was conducted for all dicamba food 

exposures assuming 100% of crop and livestock food commodities contain tolerance 

level residues. Acute dietary (food plus water) exposure (95th percentile) was 

conservatively estimated to be 0.044 mg/kg bw/day for the general population and 

0.109 mg/kg bw/day for the most highly exposed subpopulation of infants < 1year 

old. A Tier I chronic dietary assessment was also conducted and chronic dietary 

exposure was conservatively estimated to be 0.012 mg/kg bw/day for the general 

population and 0.030 mg/kg bw/day for the most highly exposed subpopulation of 

children aged 1-2 years old.

ii. Drinking water. EPA estimated concentrations of dicamba and DCSA in 

groundwater and surface water using the Pesticide Root Zone Model/Exposure 

Analysis Modeling System (PRZM/EXAMS) and Screening Concentration in 

Ground Water (SCI-GROW) models. Combined estimated environmental 

concentrations (EECs) of dicamba and DCSA for acute exposures are estimated to 

be 367 parts per billion (ppb) for surface water and 0.016 ppb for ground water. 

The combined EECs for chronic exposures are estimated to be 13.8 ppb for surface 

water and 0.016 ppb for ground water. Estimates of exposure from drinking water 

were combined with the food exposures reported above.

2. Non-dietary exposure. Dicamba is currently registered for use on residential 

sites, including home lawns and golf courses. Residential handlers are likely to be 
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exposed to dicamba residues via dermal and inhalation routes during handling, 

mixing, loading and applying activities. Post application exposure to dicamba also 

exists for adults and children who reenter a treated area. EPA assessed non-dietary 

exposure (residential handler and residential post application) to dicamba in 

support of the proposed tolerances for sweet corn commodities (Federal Register: 

April 2, 2008, Vol. 73, No. 64, p. 17914-18; Petition No. 0E6209; Decision: 304187). 

Non-dietary exposure to dicamba did not exceed the Agency’s level of concern.

D. Cumulative Effects

EPA has not made a common mechanism of toxicity finding for dicamba.

E. Safety Determination

1. U.S. population. The proposed dicamba tolerances for teff forage, grain, 

straw and hay do not pose any incremental dietary exposure to the general US 

population beyond that which has been previously considered by EPA as part of 

previous regulatory actions. A conservative dietary exposure analysis (food plus 

water) was conducted for dicamba in support of the proposed tolerances for sweet 

corn commodities (Federal Register: April 2, 2008, Vol. 73, No. 64, pages 17914-18; 

Petition No. 0E6209; Decision No. 304187). Dietary exposure from all registered 

uses of dicamba combined utilized only 4.4% aPAD and 2.6% cPAD for the general 

US population. Considering the completeness of the overall toxicity database 

supporting this petition, there is reasonable certainty that no harm will result from 

aggregate exposure arising from current and proposed dicamba uses including all 

anticipated dietary and non-occupational exposures.

2. Infants and children. The proposed dicamba tolerances for teff forage, 

grain, straw and hay do not pose any incremental dietary exposure to infants and 

children beyond that which has been previously considered by EPA. A conservative 

dietary exposure analysis (food plus water) showed that exposure from all registered 

dicamba uses contributes only 11% aPAD for the most highly exposed population 

subgroup of infants less than one year old for acute exposure, and 6.7% cPAD for 

the most highly exposed population subgroup of children 1-2 years old for chronic 

exposure. Considering the completeness of the overall toxicity database supporting 

this petition, there is reasonable certainty that no harm will result from aggregate 

exposure arising from current and proposed dicamba uses including all anticipated 

dietary and non-occupational exposures.

F. International Tolerances

There currently are no CODEX, Canadian or Mexican maximum residue 

limits (MRLs) for residues of dicamba on teff forage, grain, straw or hay.