UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

August 28, 2014 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

PC Codes: 019201, 019202 

MEMORANDUM DP Barcode: 420783 

SUBJECT: 

FROM: 

EPA Response to Comments Related to the Preliminary Problem Formulation for 

Ecological Risk and Environmental Fate, Endangered Species, and Drinking 

Water Assessments for MCPB and Its Salt 

Hannah Yingling, Biologist ~~ t~· . "/~ / ~ 1 "/ 

Larr1 Liu, Envir~nmental Scientist, Ph.D. ~ 0 C) nrf . Envrronmental Risk Branch V l • -I 0\jf 'If 

Environmental Fate and Effects Division (7507P) ~ 'f / 1, // 

THROUGH: Mah Shamim, Branch Chief, Ph.D. 

Environmental Risk Branch V 

Environmental Fate and Effects Division (7507P) 

TO: Khue Nguyen 

RM 51 

Pesticide Re-Evaluation Division (7508P) 

In response to the posting in the public docket of the "Registration Review :.. Preliminary 

Problem Formulation for Ecological Risk and Environmental Fate, Endangered Species, and 

Drinking Water assessments for MCPB" (Document ID EPA-HQ-OPP-2014-0181 in 

www.regulations.gov), Center for Biological Diversity and MCPB Task Force provided 

comments during the public comments period. The purpose of this memorandum is to address 

these comments. Listed below are the comments and EPA's responses. 
Section A. Common Comments from Center for Biological Diversity

1. Comment: EPA has an independent duty under the Endangered Species Act to consult 

with the U.S. Fish and Wildlife Service and National Marine Fisheries Service on the 

Reregistration of MCPB.

2. Comment: The EPA must make defensible “Not Likely to Adversely Affect” and “Likely 

to Adversely Affect” determinations as a prerequisite for defensible “Jeopardy” and “No 

Jeopardy” determinations. 

3. Comment: EPA and the Services must assess the Adverse Impacts of MCPB in Critical 

Habitat.

4. Comment: EPA has an independent duty under the Endangered Species Act to consult 

with the U.S. Fish and Wildlife Service and National Marine Fisheries Service on the 

Approval of all MCPB end-use products.

EFED Response: Regarding CBD’s request for EPA to begin informal consultation with the 

Services immediately after the workplan for MCPB is finalized, EPA plans to follow the March 

2013 stakeholder engagement paper (“Enhancing Stakeholder Input in the Pesticide Registration 

Review and ESA Consultation Processes and Development of Economically and 

Technologically Feasible Reasonable and Prudent Alternatives”) to identify the appropriate time 

for initiation of consultation, either formal or informal, with the Services. The stakeholder 

engagement paper, jointly developed by the EPA, USDA, and the Services and available at 

http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2012-0442-0038, allows for 

early interaction with the Services under informal consultation. EPA and the Services 

acknowledge that early interaction as part of informal consultation may result in refinements to 

EPA’s effects determinations that can improve the efficiency of the ESA compliance 

process. For example, EPA may involve the Services at the earliest stages of registration 

review. In general, EPA plans to initiate formal ESA consultation, if necessary, at the final 

decision stage in the registration review process. Consulting later in the process allows the EPA 

to develop more refined ecological risk assessments and to engage stakeholders in discussions 

that should result in more focused consultation packages that may include risk mitigation for 

listed species.

Section B. Common Comments from MCPB Task Force

1. Comment: MCPB Task Force indicated that they will likely accept assumed stability for 

soil photolysis and anaerobic aquatic metabolism.

EFED Response: Since the submitted soil photolysis study (MRID 43829901) was determined 

unacceptable and no anaerobic aquatic study has been submitted, in order to fully assess the fate 

of MCPB and its degradates in the environment, the registrant must submit soil photolysis and 

anaerobic aquatic metabolism studies.
2. Comment: For modeling purposes, MCPB Task Force recommended to use four halflives from four soils in two aerobic soil metabolism studies (MRIDs 43247601 and 47787801).

EFED Response: The Agency agrees with this approach.

3. Comment: MCPB Task Force pointed out that a “-OH” group is missing in the chemical 

structure for a degradate (4-(4-hydroxy-0tolyloxy)butyric acid.

EFED Response: The Agency will make the correction.

4. Comment: MCPB Task Force pointed out a typographical error on the release date of 

PRZM 3.12.2

EFED Response: The Agency acknowledges this typographic error. The correct release date of 

PRZM 3.12.2 is May 12, 2005.

5. Comment: MCPB Task Force claimed that the formulations for two labels (71368-5 and 

15440-38) are all SC liquids, not EC.

EFED Response: These two labels did not specify the type of formulations. The registrant must 

add the claimed formulations on these two labels.

6. Comment: MCPB Task Force recommended that the request for dioxins/furans impurity 

data for MCPB be included in the executive summary and subsequent DCI. The Task Force 

indicated that previous dioxins/furans studies have focused on the technical active ingredients 

because formulations are prepared under mild conditions that are not expected to generate 

dioxins/furans.

EFED Response: EFED noticed an impurity study that was submitted to PMRA and asked the 

registrant to submit the same study to OPP. In response, the registrant submitted this study in an 

informal way. Since this study used much lower LOQs than those in the currently available 

impurity studies in analyzing 17 dioxin and furan congeners in technical MCPB, EFED has 

determined that this study contains sufficient information to assess the impact of dioxin and 

furan congeners in the environment. Therefore, the registrant only needs to submit this study 

formally to OPP. No additional data are needed.

“Schoisswohl, D. (2011) Analysis for Tetra- to Octa-Chlorinated Dioxins and Furans in Seven 

Batches of Technical MCPA. Study Number: NUFARM/0711b. Unpublished study prepared by 

synlab Umweltinstitut Synlab GmbH.”

Though the MCPB Task Force did not submit comments in pollinator requirements, EFED 

would like to acknowledge a recent update in the policy on pollinator protection (Guidance for 

Assessing Pesticide Risks to Bees, 06.23.2014; signed by Donald Brady, Director, EFED1). In 

 

1
order to better address potential risks to bees that are likely to be exposed to pesticides, the 

following studies will be requested:: 

 Acute oral toxicity to adult honey bees 

 Acute oral toxicity to larval honey bees 

 Chronic oral toxicity to adult honey bees 

 Chronic oral toxicity to larval honey bees 

The Guidance also states that the need for higher tier studies will be determined based on the 

results of the Tier 1 studies listed above and risk management considerations including potential 

mitigation options.

Although the adult chronic oral toxicity study was not specified in the PF, this additional study 

should be conducted for the MCPB risk assessment. While the PF did indicate that an acute 

larval toxicity study (following OECD TG237) would be necessary, the release of the new 

guidance also requires a multiple-dose (chronic) larval toxicity study be submitted. The OECD 

has a draft guideline for this study that may be utilized. It may be possible to conduct the repeatdose study in such a way as to derive both an LD50 (acute endpoint of interest) and a NOAEC 

(chronic endpoint of interest) from a single study, thereby negating the need for separate acute 

and chronic larval toxicity studies. Furthermore, the Agency would be receptive to a rationale 

for bridging bee toxicity data between MCPA and MCPB. 

 

http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/terrestrial_biology_tech_team/Guidance

AssessingPesticideRisk2Bees.pdf