1 OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460

January 7 , 2016

PC Code: 079801

MEMORANDUM DP Barcode : 4 309 64

SUBJECT : Thiram : Response to Comments on the EFED Problem Formulation for Registration

Review

FROM: Elyssa Arnold, Risk Assessment Process Leader Ron Parker, Senior Environmental Engineer

Environmental Risk Branch 2 Environmental Fate and Effects Division (7507P)

THROUGH : Brian Anderson , Branch Chief

Environmental Risk Branch 2 Environmental Fate and Effects Division (7507P )

TO: Wilhelmena Livingston, Chemical Review Manager Kevin Costello, Branch Chief Risk Management and Implementation Branch 4

Pesticide Re

- e valuation Division (7508P)

The Env ironmental Fate and Effects Division (EFED) reviewed comment s from the Thiram Task Force and the Physicians Committee for Responsible Medicine on the “ Registration Review: Preliminary Problem Formulation for Environmental Fate, Ecological Risk, Endangered Species, and Human Health Drinking Water Exposure Assessments for Ferbam and Thiram ” ( DP 427810, 427924 , Doc ket ID

EPA

– HQ

– OPP

– 2015

– 0433 ). The purpose of this memorandum is to respond to th ese comme nt s

.

Comments from the Thiram Task Force

1. Comment summary: The Thiram Task Force believes that the Agency should reconsider the need for the pollinator studies identified in the preliminary Work Plan. The EPA categorizes pesticides as

“toxic to bees” if the acute contact LD 50 is > 11 μg /bee. Available data indicat e that the contact LD 50 for thiram is 73.72 μg/bee and was considered by the Agency to be practically nontoxic to bees. Additionally, it is not believed that there have been any adverse incidents involving thiram and bees.

EFED response: Although thiram is categorized as practically non

- toxic to adult honeybees via

acute contact exposure, there is considerable uncertainty regarding the potential effects of the compound on honey bee larval development and survival as well as potential for chronic effects. Additional data on pollinators are needed to fully characterize the risk associated with thiram use to all developmental stages of honey bees, as sensitivity may vary according to life

- stage (adult vs. eggs, larvae, and pupae), length of exposure (acute v s. chronic), and route of exposure (contact vs.2 oral). As indicated in EPA guidance issued in 2014 1 , assessing risks to bees involves a battery of laboratory

- based studies. These studies are intended to examine effects to individual bees and provide insigh t on potential effects to solitary species of bees. Depending on the outcome of those studies, semi

- field and full

- field studies involving whole bee colonies may be required to refine risk estimates and provide insight into the potential effects of a pesti cide on social bees. Additionally, as the risk assessment process is intended to provide information on non

- Apis as well as honey bees, there are solitary and social non

- Apis bees which feed directly on pollen and would likely be exposed to any residues th at are sorbed to pollen.

An absence of report ed incidents does not necessarily equate to an absence of incidents given the nature of incident reporting. Incidents that do not involve acute mortality events can be difficult to identify and are very rarely reported.

2. Comment summary: The members of the Thiram Task Force hold segmented labels for foliar and

seed treatment uses. It would be helpful to the Task Force if the Final Work Plan could designate which data requirements are for foliar uses, for seed tr eatments and for both.

EFED response: OCSPP 850.4150, Vegetative Vigor, is applicable to foliar uses only. All other requested ecotoxicity studies apply to both foliar uses and seed treatments.

Comment from the Physicians Committee for Responsible Medicine (PCRM)

1. Comment summary: PCRM has identified acute avia n oral toxicity data for a passerine species via Extoxnet ( http://extoxnet.orst.edu/pips/thiram.htm ) . The stated LD 50 is >100 mg/kg in red

- winged

blackbirds. If additional data are needed, PCRM recommends using the OECD Test Guideline 223 (TG223) instead of EPA Guideline 850.2100 in the interest of reducing the numbers of animals used.

EFED response: EFED will review the red

- winged blackbird study referenced by PCRM if it is submitted to the Agency for that purpose. However, EFED notes that a limit dose of 100 mg/kg is unlikely to be sufficient for risk assessment. EFED will accept TG223 studies in place of 850. 2100

studies under the conditions laid out in EFED’s 2011 Guidance for Classifying Studies Conducted Using the OECD Test Guideline 223 (TG223) (Acute Avian Oral Sequential Dose Study) ( http://www.epa.gov/pesticide

- science

- and

- assessing

- pesticide

- risks/guidance

- classifying

- studies

conducted

- using

- oecd ).

1 USEPA. 2014. Guidance for Assessing Pesticide Risks to Bees. Office of Pesticide Programs United States Environmental Protection Agency, Health Canada Pest Management Regulatory Agency, California Department of Pesticide Regulat ion. June 19, 2014. Available at: http://www.epa.gov/pollinator

- protection/pollinator

- risk

- assessment

- guidance