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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION

MEMORANDUM

Date: APR-19-2013 

SUBJECT: Ethalfluralin: Petition for the Establishment of Tolerances on Rapeseed subgroup 

20A and Sunflower Subgroup 20B; Request for Registration of Sonalan®10G 

(EPA Reg No. 62719-184) and Sonalan® HFP (EPA Reg No. 62719-188) on 

Rapeseed subgroup 20A and Sunflower Subgroup 20B.

PC Code: 113101 DP Barcode: D401523

Decision No.: 462704 Registration No.: 62719-184 & 62719-188

Petition No.: 2E8007 Regulatory Action: Section 3 Registration 

Risk Assessment Type: Single 

Chemical/Aggregate

Case No.: None

TXR No.: None CAS No.: 5523-68-6

MRID No.: None 40 CFR: 180.416

FROM: Mohsen Sahafeyan, Chemist/Risk Assessor

Yung G. Yang, Toxicologist

Risk Assessment Branch VI

Health Effects Division (7509P)

THROUGH: Felecia Fort, Branch Chief

Risk Assessment Branch VI

Health Effects Division (7509P)

TO: Laura Nollen and Barbara Madden, Minor Use Team

Risk Integration, Minor Use, and Emergency Response Branch

Registration Division (7505P)

This document provides the Health Effects Division (HED) human health assessment for the 

proposed establishment of tolerances and registration of new uses of the herbicides ethalfluralin 

on Rapeseed subgroup 20A and Sunflower Subgroup 20B.
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Introduction

Ethalfluralin [N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl)-benzenamine] is 

a selective preemergence herbicide registered for use on a variety of food and feed crops. The 

Interregional Research Project #4 (IR-4) has requested conversion of existing sunflower and 

canola/rapeseed tolerances to Rapeseed subgroup 20A and Sunflower subgroup 20B for 

Sonalan®10G (EPA Reg No. 62719-184) and Sonalan® HFP (EPA Reg No. 62719-188) with 

concurrent removal of tolerances for ethalfluralin in or on rapeseed and sunflower. Sonalan®

10G is a granular formulation containing 10% ethalfluralin and Sonalan® HFP is an emulsifiable 

concentrate formulation containing 3 lb/gal ethalfluralin. Both formulations are currently 

registered for preemergence control of certain annual grasses and broadleaf weeds in crambe, dry

beans, dry peas, peanuts, rapeseed, safflower, soybeans, and sunflower. The petitioner, IR-4, is 

proposing the following tolerances on the food commodities as shown below.

Commodity Proposed Tolerance (ppm)

Rapeseed

subgroup 20A

0.05

Sunflower 

subgroup 20B

0.05

Proposed Use

The proposed use pattern for all Rapeseed subgroup 20A and Sunflower subgroup 20B is similar 

to the existing registered use for canola/rapeseed and sunflower seed. The current total 

maximum use rate for Sonalan HFP formulation (3 lb ai/gal) on rapeseed is 2 1⁄2 pt/acre (0.94 lb

ai/A), on sunflower is 4 1⁄2 pt/acre (1.7 lb ai/A) and on safflower is 3 pt/acre (1.1 lb ai/A). The 

current total maximum use rate for Sonalan 10G formulation on rapeseed is 9.5 lb ai/A, on

sunflower is 17.0 lb ai/A, and on safflower is 11.5 lb ai/A. Grazing or foraging crops grown in 

treated soil is restricted.

Toxicity Data and Endpoint Selection

The last assessment of the toxicity database for ethalfluralin was included in the most recent 

comprehensive risk assessment (Ethalfluralin: Human Health Risk Assessment for (IR-4)

Proposed Uses on Dill and Potato, J. R. Tomerlin, 11/2/07. However, 40 CFR Part 158 was 

modified in 2007 to include the requirement for a neurotoxicity screening battery and an 

immunotoxicity study. In 2012, the Hazard and Science Policy Council (HASPOC) determined 

that the acute and subchronic neurotoxicity studies as well as a subchronic inhalation toxicity

study are not needed for the registered uses of ethalfluralin based on a weight-of-evidence 

approach considering all the available hazard and exposure information (Ethalfluralin: Summary 

of Hazard and Science Policy Council (HASPOC) Meeting of December 6, 2012: 

Recommendations on the need for inhalation and neurotoxicity battery (acute and subchronic) 

studies, Kristin Rury, Feb. 2013, TXR number 0056533). However, the immunotoxicity study
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remains a data requirement at this time. Although an immunotoxicity study has not been 

received by the Agency, there is relatively little concern as there are no indications of 

immunotoxicity in the toxicology database; it does not appear that ethalfluralin directly targets 

the immune system. Additionally, ethalfluralin does not belong to a class of chemicals (e.g., the 

organotins, heavy metals, halogenated aromatic hydrocarbons) that would be expected to be 

immunotoxic. Furthermore, the Agency does not believe that conducting an immunotoxicity

study will result in a lower point of departure (POD) than that currently used for overall risk 

assessment; therefore, a database uncertainty factor (UFDB) is not needed to account for the lack 

of the study. The selected Point of Departures (PODs) and toxicological endpoints and profile 

from the most recent human health risk assessment do not require modification. 

The toxicology database concerning infants and children is considered to be complete with the

exception of an immunotoxicity study. Submitted studies included developmental rat and rabbit, 

and 2-generation reproduction in rats. HED has fully evaluated the toxicity database of 

ethalfluralin with respect to the potential for special sensitivity of infants and children, and 

concludes that there is low concern for pre- and postnatal susceptibility for infants and children. 

The FQPA safety factor has been reduced to 1X because (1) the toxicity database is adequate to 

characterize potential pre- and postnatal risk for infants and children; (2) no reproductive or 

developmental effects were observed in rats; and (3) although there were slight developmental 

effects observed (skeletal malformations) in rabbits (fetuses), they were seen in the presence of 

maternal toxicity. Additionally, the dose chosen for acute dietary risk assessment is protective of 

the slight developmental effects observed in the rabbit developmental toxicity studies. 

Residue Data

No residue data were submitted with this petition. Rapeseed (canola varieties) and sunflower 

seed are representative commodities for subgroup 20A and 20B respectively for which there are 

adequate residue data. Since the proposed use rates for all commodities in crop subgroup 20A 

and 20B are similar to those of rapeseed and sunflower seed, no further residue data are required. 

Residues in the field trials for canola and sunflower seed were non-detectable. 

Aggregate and Occupational Risks

The reported dietary risk estimates from exposure to food and water from the 2007 risk 

assessment was <1% of the population adjusted doses (PADs) for both acute and chronic 

exposures. The cancer risk estimate was 2 X 10-6. The action associated with this petition, i.e., 

expansion of registered crops from representative crops to crop subgroups 20A and 20B, is not 

expected to result in acute and chronic dietary exposures (food + water) above 1% of the acute 

and chronic PADs that were reported in the 2007 assessment. The change in cancer risk estimate 

from 2007 risk assessment is also expected to be minimal because the increase in consumption 

from the additional commodities in crop subgroup 20A and 20B and change in ethalfluralin 

residue levels in drinking water are expected to be minimal. There are also no livestock feed 

items for the commodities in the crop subgroups 20A and 20B and therefore, there is no concern 

for exposure from livestock.
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There are currently tolerances on representative crops of crop subgroups 20A and 20B. These 

registered crops, rapeseed seed and sunflower seed, in addition to registered safflower seed are 

by far the most consumed commodities in crop subgroups 20A and 20B. Other commodities in 

crop subgroup 20A and 20B have low consumptions and are not expected to contribute any 

significant amount to food exposure. 

The major contributor to ethalfluralin dietary exposure is drinking water; the exposure estimate 

for the cancer assessment was based on monitoring data. HED has reviewed the most recent

water monitoring data to ensure there have not been significant changes from the 2007 

assessment. Data from USDA’s Pesticide Data Program (PDP) and US Geological Survey, 

National Water-Quality Assessment Program (USGS/NAWQA) still show that there have been 

no detectable or very limited detectable residues of ethalfluralin in sampled drinking water and 

surface/ground water. PDP sampled 3515 samples of drinking water between 2006 and 2011 

and there were not detects at a limit of detection (LOD) between 30 and 400 parts per trillion 

(ppt). Likewise, there has been a very low detection frequency (0.8%) of ethalfluralin in the 

USGS/NAWQA monitoring data in the last search by The Environmental Fate and Effects 

Division, EFED (EFED Registration Review Problem Formulation for Ethalfluralin, M. Barratt and 

J. Housenger, D382172, 03/14/11). A new search also showed that from 2006 until the last 

sampling year, 2008, there was only one detect at 0.0011 ppb from 489 total samples, further 

minimizing concern for change in cancer risk from exposure to drinking water. Residues in

drinking water are not expected to change significantly from registration of crop subgroups 20A 

and 20B as the application rates for crop group 20A and 20B are the same as the currentlyregistered representative crops and there are far higher acreage of rapeseed and sunflower as 

compared to the combined acreage of other commodities in crop subgroups 20A and 20B. 

At this time, there are no current or proposed residential uses for ethalfluralin. Therefore, 

aggregate exposure and risk consist of only the dietary (food + water) pathway of exposure. 

Aggregate acute, chronic and cancer risks are not of concern for the proposed and existing uses.

HED concludes that the proposed uses on Crop Groups 20A and B will not significantly increase 

aggregate exposures and risk estimates for ethalfluralin from the most recent risk assessment 

(Ethalfluralin: Human Health Risk Assessment for (IR-4) Proposed Uses on Dill and Potato, J. 

R. Tomerlin, 11/2/07). 

Since the use pattern for Sonalan®10G and Sonalan® HFP on rapeseed subgroup 20A and 

sunflower subgroup 20B is identical to the currently registered crops, occupational risk estimates 

will be the same as those for rapeseed seed and sunflower seed, and are not of concern. 

Adequacy of the Proposed Tolerances

The petitioner, IR-4, is proposing the following tolerances on the food commodities as shown 

below.
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Commodity Proposed Tolerance (ppm) Current Tolerance for 

Representative Crop

(ppm)

Rapeseed

subgroup 20A

0.05 0.05 (for Rapeseed, seed)

Sunflower 

subgroup 20B

0.05 0.05 (for Sunflower, seed)

Proposed tolerances for residues of ethalfluralin on crop subgroups 20A and 20B commodities 

are identical to the tolerances for this chemical on the currently-registered rapeseed seed and 

sunflower seed, which are representative commodities for those crop subgroups. Since the use 

patterns on crop subgroups 20A and 20B commodities are the same as their representative crops, 

rapeseed seed and sunflower seed, HED agrees that these tolerance levels are appropriate. At 

present, there is no Codex or European MRLs for ethalfluralin and therefore, there are no 

concerns for international harmonization.

Conclusions

The toxicity database for ethalfluralin is considered complete except for an immunotoxicity

study. Adequate residue data are available to support the proposed use on crop subgroups 20A 

and 20B commodities, which have identical use patterns as the currently-registered 

representative commodities for those crop subgroups (rapeseed seed and sunflower seed). There 

will be no increase in aggregate exposure or risk from food or drinking water sources as a result 

of the proposed use; aggregate risk estimates are not of concern for ethalfluralin based on the 

most recent comprehensive risk assessments for that compound. Occupational exposures and 

risks are not of concern. Therefore, HED has no objections to granting the proposed registration 

of Sonalan®10G and Sonalan® HFP on crop subgroup 20A and crop subgroup 20B and

establishing tolerances as described below with simultaneous revocation of ethalfluralin 

individual tolerances on rapeseed, seed, sunflower, seed and safflower, seed. 

The Petitioner should revise the proposed tolerance expressions for ethalfluralin, as follows:

Tolerances are established for residues of the herbicide, ethalfluralin, including its 

metabolites and degradates, in or on the commodities in the table below. Compliance 

with the tolerance levels specified below is to be determined by measuring only the 

residues of ethalfluralin [ N -ethyl- N -(2-methyl-2-propenyl)-2,6-dinitro-4-

(trifluoromethyl)benzenamine].

Commodity Recommended Tolerance (ppm)

Rapeseed

subgroup 20A

0.05

Sunflower 

subgroup 20B

0.05
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Ethalfluralin individual tolerances on rapeseed, seed, sunflower, seed and safflower, seed, each 

at 0.05 ppm should also be simultaneously revoked.