Page 2 of 4 1. Aerobic Soil Metabolism (OCSPP guideline # 835.4100) : The degradation of bromacil has been widely studied and its degradation behavior is extensively documented. One of the studies recently conducted by Sarmah et al. (2009) is very representative of existing data, and guideline complia nt. T he degradation of bromacil was investigated in two contrasting New Zealand agricultural soils under controlled laboratory conditions. The controlled laboratory study design ( including soil characterization, temperature, study duration, sampling analysis, and recovery) exactly follows the test guidelines of EPA OPPTS 835.4100. Therefore, DuPont believes that the DT50 values estimated from this study may be used for the endpoint s of risk assessment, and another aerobic degradation study is not warranted.

Response: DuPont should formally submit the referenced Sarmah et al ., (2009) study if Agency review is desired . EFED will evaluate the study upon receipt and determine its

sui tability for use in risk assessment. If however, the study is determined to provide no additional useful information, EFED will maintain the approach discussed in the problem formulation, multiply ing the single available degradation half

- life (MRID 409515 10) by three to account for potential variability in degradation rates between different soil types

.

2. Adsorption/Desorption, Batch Equilibrium ( OCSPP guideline # 835.1230): DuPont agrees with the regulators that additional data may not increase the conservatism of the assumed sorption coefficient for bromacil, and DuPont believes that the values with an average of 48.4 L/Kgoc reported in the open literature (Gerstl and Yaron, 1983; Corwin and Farmer, 1984; Reddy et al. 1992; Turin and Bowman, 1997; S armah et al. 2009) can be used for modeling purpose and risk assessment. The value of 48.4 L/Kgoc is nearly identical to the average Koc value of 32 L/Kgoc from SCS/ARS database (USEPA, 2007) and 66 L/Kgoc from EPISuite v 4.1 as cited in EFED scoping asses sment.

Response: The open literature studies referenced by DuPont should be formally submitted to the Agency if it is desired that these data be considered at the time of risk assessment. EFED will consider the best available data and select the most ap propriate value for use in

risk assessment.

3. A erobic Aquatic Metabolism ( OCSPP guideline # 835.43 00) : DuPont will consider providing an aerobic aquatic metabolism study if such a requirement is included in the Data

Call

- in.

Response: EFED will review an aerobic aquatic metabolism study upon receipt. If this study is unacceptable or if DuPont does not submit a study, the Agency will make the conservative assumption that bromacil is stable to microbial degradation in the risk

assessment

.

4. Anaerobic Aquatic Metabolism ( OCSPP guideline # 835.4400) : In an open

- literature laboratory study, bromacil had an observed half

- life of 144 to 198 days under saturated (anaerobic) soil conditions from a well designed aquatic degradation study (Wolf, 1974).Page 3 of 4 DuPont believes that these reported DT50 values can be us ed for risk assessment. If found not acceptable for use in risk assessment by regulators, DuPont will consider providing an anaerobic aquatic metabolism study if such a requirement is included in the Data Call

- in.

Response: This study was investigated du ring the problem formulation phase

. Although EFED has not completed a formal review for this study, an official review will be conducted prior to the initiation of the registration review risk assessment

. During the review process, the Wolf and Martin (1 974) publication will be evaluated according to the current acceptability criteria for studies submitted under the OCSPP guideline 835.4400. If th is study is determined to be inadequate or otherwise deficient

, the Agency will make the conservative assumpt ion that bromacil is stab le to microbial degradation in the risk

assessment

.

5

. Issue 3 (Section 8.2, pg 44): DuPont agree s to perform an acute avian toxicity study with bobwhite quail at the maximum label rate for use in risk assessment if requested in a Data Call

In Notice.

Response: EFED will review the acute avian toxicity study upon receipt.

6

. Issue 4 (Section 8.2, pg 44) : DuPont does not agree that the see dling emergence and vegetative vigor tests need to be repeated. However, DuPont does agree that the original seedling emergence and vegetative vigor studies submitted (MRID 44488307 and MRID 42491101) utilized technical grade product instead of formulated product. In this regard we offer for your consideration:

• Bromacil technical grade product is water soluble and requires minimal additional ingredients in order to formulate the final product.

• There are 3 regist ered DuPont end

- use product formulations containing Bromacil. Of these, DuPont Hyvar X Herbicide (EPA Reg. No. 352

- 28 7) is an 80% a.i. containing dry powder formulation of Bromacil, and would be the representative typical end use product used in repeated t esting.

• DuPont requests that EPA reconsider the need for new studies in light o f the high concentration of active ingredient in the representative typical end use product. Specific to the 80% dry formulation, over half the balance of ingredients are diluen ts and all inerts are currently approved for food use under 40 CFR part 180. Upon examination of the current Confidential Statement of Formula (CSF) on file, it should be reasonable to conclude that the intentionally added inert ingredients would not be ex pected to affect the outcome of the non

- target plant testing.

Response: Since the formulation of DuPont Hyvar X herbicide (EPA Reg. No. 352

- 287) contains detergents (surfactants) that may enhance the toxicity of the active ingredient via

facilitated upta ke and/or transport , terrestrial plant testing with bromacil typical end use product ( TEP ) is still needed . Results from Tier II terrestrial plant seedling emergence and vegetative vigor testing will provide confirmatory evidence attesting to the enhancement (or

lack thereof ) of effects exerted by co

- formulants contained in the bromacil TEP.Page 4 of 4 References:

Sarmah et al. 2009. Dissi pation and sorption of six commonly used pesticides in two contrasting

soils of New Zealand. Journal of Environmental Sc ience and Health Part B (2009) 44, 325

– 336.

Wolf, D.C. and J.P M artin. 1974. Microbial Degradat i o n of 2

- Carbon

- 14 bromacil and terbacil.

Soil Sci. Soc. Amer. Proc. 38:921

- 925.