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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 

compliant. The 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 endpoints 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 

suitability 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, multiplying the single available degradation half-life (MRID 40951510) 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; Sarmah 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 assessment.

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 appropriate value for use in 

risk assessment.

3. Aerobic Aquatic Metabolism (OCSPP guideline # 835.4300): 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). 
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DuPont believes that these reported DT50 values can be used 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 during 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 (1974) publication will be evaluated according to the current 

acceptability criteria for studies submitted under the OCSPP guideline 835.4400. If this 

study is determined to be inadequate or otherwise deficient, the Agency will make the 

conservative assumption that bromacil is stable to microbial degradation in the risk 

assessment. 

5. Issue 3 (Section 8.2, pg 44): DuPont agrees 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 seedling 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 registered DuPont end-use product formulations containing Bromacil. Of 

these, DuPont Hyvar X Herbicide (EPA Reg. No. 352-287) is an 80% a.i. containing dry 

powder formulation of Bromacil, and would be the representative typical end use product 

used in repeated testing.

• DuPont requests that EPA reconsider the need for new studies in light of 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 diluents 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 expected 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 uptake 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.
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References:

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

soils of New Zealand. Journal of Environmental Science and Health Part B (2009) 44, 325–336.

Wolf, D.C. and J.P Martin. 1974. Microbial Degradation of 2-Carbon-14 bromacil and terbacil. 

Soil Sci. Soc. Amer. Proc. 38:921-925.