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 ~ ~&.;. ,.,,--

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 if not, then recommend using the OECD Test Guideline 

(TG) 223 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 

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laboratory. Additionally, any observation of regurgitation by the test species, which has been 

observed in passerine testing, would severely limit the utility of the 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 of food 

and habitat) for fish from exposure to chlorothalonil is an important aspect of the assessment. 

Therefore, deriving an accurate, definitive acute LC50 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 of the 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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