UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON D .C. , 20460

MEMORANDUM PC Code: 081901 DP Code: 411527 July 23, 2013 Subject:
To:

From:
Through: Chlorothalonil- Environmental Fate and Effects Division's Response to Public Comments on the**R~gistration** Review Problem Formulation Jose Gayoso, Chemical Review Manager Risk Management and Implementation Branch 2 Pesticide Re-evaluation Division (7508P) Amy Blankinship, Chemist

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# ,.,,-- Environmental Risk Branch 3**~** Environmental Fate and Effects Division (7507P) Dana Spatz, Branch**Ch efc::::~~»'...._::::='~...J**  Rosanna Louie-Juzwiak, Risk Assessment Process Leade Melissa Panger, Ph
.D., Senior Biologist Environmental Risk Branch 3 Environmental Fate and Effects Division (7507P)
This document contains the Environmental Fate and Effects Division's (EFED) response to public comments received on the chlorothalonil registration review problem formulation from the Physicians Committee for Responsible Medicine (PCRM) dated May 29, 2012 (posted to the Chlorothalonil Registration Review docket on March 18,2013, Docket ID EPA-HQ-OPP-2011-0840). Additional public comments received earlier were addressed by EFED in a memo dated August 28, 2012.


### 1. Comment Summary: It appears that data may be available to fulfill the passerine acute oral data requirement (Mineau eta/. 2001 ), and ifnot, then recommend using the OECD Test Guideline (TG) 22 3 protocol instead ofthe OCSPP 850.2100 guideline
. EFED RESP 'ONSE: EFED reviewed the available toxicity data as well as the referenced Mineau et 

### al. 2001 paper, and an acute oral study with a passerine species was not conducted and as such remains a data gap. As referenced by PCRM, another available approach to conducting the acute avian oral toxicity test is the OECD TG 223, for which the Agency has previously developed guidance on addressing the conduct and acceptability of studies conducted under TG 223 (USEP A 2011). Specifically, as the 223 guideline was validated using the northern bobwhite quail (Colinus virginianus) , the guidance states that while the use of another species (i.e. , a passerine) may be considered, low background mortality for the test species needs to be demonstrated 

### in the testing
1laboratory. Additionally, any observation ofregurgitation by the test species, which has been observed in passerine testing, would severely limit the utility ofthe results obtained using**th€ ~**  TG 223 (as well as for studies conducted under 850
.2100); additional guidance on this issue is also available by the Agency (USEPA 2012). 2. Comment Summary: PCRM suggests using the acute threshold or "limit test" approach for fulfilling the acute fish (saltwater) toxicity test (OCSPP 850.1075) data requirement. Additionally, they state that as the EC50 for invertebrates is known and low, that conducting a limit test with fish at this level may accomplish the Agency data needs. Finally, they encourage the use of(Q)SAR data either in place of, or addition to, the fish experimental data. EFED RESPONSE: In conducting an ecological risk assessment for the registration review of chlorothalonil, assessing both potential direct as well as indirect effects 

### (i.e., potential loss offood and habitat) for fish from exposure to chlorothalonil is an important aspect ofthe assessment. Therefore, deriving an accurate, definitive acute LC 50 value for fish is considered necessary Jbr evaluating potential direct risk from exposure to chlorothalonil. Currently, EPA utilizes information obtained from (Q)SAR as part ofthe risk assessment screening process, typically during the problem formulation phase, to determine whether aquatic toxicity data may be necessary for chemicals as well as their degradates of concern. Given that chlorothalonil is classified as very highly toxic to aquatic animals, it is considered important to have empirically-derived acute toxicity data to evaluate potential risk.

References: Mineau P., A. Baril, B. T. Collins, J. Duffe, G. Joerman, and R. Luttik
. 2001. Pesticide acute toxicity reference values for birds. Rev. Environ
. Contam. Toxicol. 170: 13-74. United States Environmental Protection Agency. 2011. Guidance for classifying studies conducted using the OECD test guideline 223 (TG23) (acute oral sequential dose study). Memorandum from Donald 

### J. Brady, Environmental Fate and Effects Division. November 9, 201.1
. http://www.epa .gov/pesticides /science /efed/policy guidance/team authors/terrestrial biology tech t eam/review avian acute oral oecd tg223.htm United States Environmental Protection Agency. 2012. Guidance for use when regurgitation is observed in avian acute toxicity studies with passerine species. Memorandum from Donald 

### J . Brady, Environmental Fate and Effects Division. April9, 2012.



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