Docket Number EPA-HQ-OPP-2014-0180 

www.regulations.gov 

MCPA Final Work Plan 

Registration Review 

Case Number 0017 

September 2013 

Approved by: ~,::n 

Date: 

Richard P. Keigwin, Jr. 

Director 

Pesticide Re-evaluation Division 

q- c:J- '-f 
INTRODUCTION 

This is the Environmental Protection Agency's (EPA or the Agency) Final Work Plan (FWP) for 

the registration review of MCPA (2-methyl-4-chlorophenoxyacetic acid). This work plan 

addresses public comments received concerning the Preliminary Work Plan (PWP), which was 

posted in the MCPA registration review docket (EPA-HQ-OPP-20 14-0 180). MCPA is a postemergence herbicide that is registered for use for selective control ofbroadleafweeds in various 

agricultural and non-agricultural settings. Agricultural use sites include barley, flax, grasses 

grown for seed, oats, pastureland, peas, rye, and wheat. Non-agricultural use sites include 

uncultivated fields, ornamental and residential lawns, and turf. The registration review case for 

MCPA includes MCPA acid (PC code 030501), MCPA sodium salt (PC code 030502), MCPA 

dimethylamine salt (PC code 030516), MCPA isoctyl ester (PC code 030563 ), and MCPA 2-

ethylhexyl ester (PC code 030564). 

The Agency is implementing the registration review program pursuant to Section 3(g) of the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and will review each registered 

pesticide every 15 years to determine whether it continues to meet the FIFRA standard for 

registration. Changes in science, public policy, and pesticide use practices occur over time. The 

registration review program is intended to make sure that, as the ability to assess risk evolves and 

as policies and practices change, all registered pesticides continue to meet the statutory standard. 

The public phase of registration review begins when the initial docket is opened for each case. 

Information on this program is provided on the Agency's website. 1 

The FWP begins with any updates since the PWP was issued. Next is a summary of substantive 

comments received during the public comment period for the PWP concerning anticipated data 

needs, expected risk assessments, or the estimated timeline identified in the PWP, and a 

summary of the Agency's responses to those comments. This section is followed by registration 

review planned data needs, risk assessments expected to be conducted, and the projected 

registration review time line for MCP A. Lastly, there is a discussion of next steps. 

UPDATES SINCE THE PWP WAS ISSUED 

The PWP listed the acute oral toxicity to adult honeybee and acute oral toxicity to larval 

honeybee studies as anticipated data needs. The MCP A Task Force Ill commented that 

previously submitted honeybee data may meet the Agency's need for adult acute oral toxicity 

honeybee data. A review of the existing MCPA honeybee data suggests that additional adult 

acute oral toxicity honeybee data will not be needed for risk assessment, therefore, the pollinator 

acute oral toxicity study is being removed as a data requirement. Due to the Agency's new 

guidance for assessing risks to bees (see guidance document dated June 19, 20 14 at 

http://www2.epa.gov/sites/production/files/20 14-

06/documents/pollinator risk assessment guidance 06 19 14.pdt), the Agency is also 

modifying its pollinator data requirements for MCPA to include two additional pollinator 

studies: 

• Chronic oral toxicity to larval honeybees 

1 http://www .epa.gov/oppsrrd I /registration _review/ 

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• Chronic oral toxicity to adult honeybees 

Various phenoxy herbicides are known to contain dioxinlfuran impurities as a result of 

manufacturing processes. Previously submitted dioxin!furan data for MCP A did not indicate 

levels of concern. However, recent data on dioxin!furan impurities in MCPB products has 

prompted the Agency to modify its list of data requirements to include guideline 830.1700--

preliminary analysis in order to confirm the presence/level of dioxin!furan impurities in MCPA 

products using the most up-to-date analytical methods. 

The PWP listed guideline 875.2100 dislodgeable foliar residue as an anticipated data need 

because according to Agency policy at the time, these data were required when margins of 

exposure (MOEs) were less than 4 times the level of concern (LOC). Since the issuance ofthe 

PWP, the Agency has updated this approach and is now requiring dislodgeable foliar residue 

data when the occupational post-application MOEs are less than 2 times the LOC. Therefore, the 

Agency is removing its requirement for guideline 875.21 00--dislodgeable foliar residue data. 

SUMMARY OF COMMENTS AND AGENCY RESPONSES 

During the 60-day public comment period on the MCPA Preliminary Work Plan, which opened 

on March 28,2014 and closed on May 27,2014, the Agency received five submissions from the 

public. Comments were submitted by the MCPA Task Force Three, the Center for Biological 

Diversity, the Central Valley Regional Water Quality Control Board (of California), the FIFRA 

Endangered Species Task Force (FESTF), and a private citizen. The MCPA Task Force Three's 

comments covered the erroneous classification of one product under an incorrect PC code, the 

submission of pollinator data for MCPA, EPA's information request on dioxins and furans, and 

technical corrections for information cited in the Agency's registration review documents. The 

Center for Biological Diversity's comments addressed the Agency's responsibilities under the 

Endangered Species Act (ESA). The Central Valley Regional Water Quality Control Board 

asked EPA to consider the cumulative risk of additive toxicities between MCP A and other 

phenoxy herbicides during registration review. FESTF commented that the technical registrants, 

Albaugh, Dow, and Nufarm, are FESTF members and are entitled to rely on FESTF data for 

endangered species assessment. A private citizen commented in favor of banning MCP A and 

similar pesticides due to their potential for bioaccumulation in fatty tissues and potential damage 

to human health from endocrine disruption. 

The comments do not address the timeline described in the PWP, but they do address the planned 

ecological and human health risk assessments and data requirements. In the PWP, EPA also 

solicited comments on the specific topics of environmental justice, water quality concerns, and 

trade irritants, but no comments or information were received on those issues. 

This section does not capture every comment made about the PWP nor all of the Agency's 

responses. Summarized below are public comments that resulted in changes to the anticipated 

registration review data needs, risk assessments, or timeline, or are of a broader regulatory 

nature. Public comments and EPA responses in their entirety are located in the docket, EPAHQ-OPP-2014-0180, accessible at www.regulations.gov. Summarized public comments and 

Agency responses related to the anticipated ecological risk assessment or data needs are in the 

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EFED Response to Public Comments on: Preliminary Problem Formulation for Environmental 

Fate and Ecological Risk, Endangered Species, and Drinking Water Assessments for MCPA, 

while comments relevant to the anticipated human health risk assessment or data needs are in the 

document, MCPA. Response to Comments Received Regarding Scoping Document in Support of 

Registration Review. Public comments and Agency responses related to use and usage and the 

general registration review program are in the MCPA: PRD Responses to Comments on 

Registration Review Preliminaty Work Plan. 

Comments submitted by MCPA Task Force Three in EPA-HQ-OPP-2014-0180-0022. 

1. Comment: An acute oral honeybee toxicity study completed according to OECD guideline 

213 was submitted to EPA (MRID 47666601) and was evaluated as scientifically sound but 

was classified supplemental because it did not meet guideline requirements. A second 

honeybee acute toxicity study (MRJD 45897007) evaluating the contact and oral LD5o of 

MCPA acid was conducted according to EPPO Standard PP 1/ 170(2) and submitted to the 

Agency. 

Response: The registration review problem formulation originally requested two honeybee 

studies: an acute oral toxicity study (following OECD guideline 213) and a larval toxicity 

study (following OECD guideline 237). A review of MRIDs 4 7666601 and 45897007 

suggests that additional adult acute oral honeybee data will not be needed for risk 

assessment. The Agency's policy on pollinator protection has recently been updated (see 

http://www2.epa.gov/sites/production/files/20 14-

06/documents/pollinator risk assessment guidance 06 19 14.pdl). Accordingly, the 

Agency is modifying its pollinator data requirements to include an additional adult chronic 

oral toxicity honeybee study and a repeat-dose chronic larval honeybee toxicity study. Thus, 

the Agency is modifying its pollinator data requirements to the following: 

• Acute oral toxicity to larval honeybees 

• Chronic oral toxicity to larval honeybees 

• Chronic oral toxicity to adult honeybees 

2. Comment: Technical phenoxy herbicide registrants have provided dioxin/furan data at 

different times for several decades in response to Agency requirements for data on impurities 

of potential toxicological concern in technical MCP A products. These results have 

demonstrated non-detectable or extremely low detections while the LOQs for many 

dioxins/furans have steadily declined with analytical advances. EPA should make specific 

requests to technical registrants for additional data at currently achievable LOQs. 

Response: The Task Force is correct; the Agency has access to MCPA-specific information 

on dioxin/furan impurities in MCPA products. However, recent data on dioxin/furan 

impurities in MCPB products has prompted the Agency to modify its list of data 

requirements to include guideline 830.1700- preliminary analysis, in order to confirm the 

presence/level of dioxinlfuran impurities in MCP A products using the most up-to-date 

analytical methods. 

3. Comment: MCPA is registeredfor use on alfalfa, barley, clover, flax, oats, pasture and 

rangeland grass, peas, rye, triticale, wheat, grass grown for seed, turf, lawns, golf courses, 

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and rights-of-way. For all these uses, there are limited (f any re-entry activities post 

application. Active ingredient-specific turftransferable residue data existfor turf uses. 

Since MCP A applications to all crops are made early in the growth cycle when plant height 

is less than 6 inches and surface areas of leaves are small, the results from the existing turf 

transferable residue evaluations that mimic these conditions should be applicable for 

evaluation of dislodgeable foliar residues (DFR). If EPA still believes a DFR study is still 

necessary, Agency input will be needed with regard to appropriate sampling techniques since 

a leaf punch system typically used will not be applicable. Data from the Agricultural Reentry Task Force may also provide evidence that MCPA crops are not appropriate or wellsuited to conduct DFR studies. 

Response: When the scoping document was published, the Agency's policy was to require 

DFR data when MOEs were less than 4 times the LOC ( <400). Since then, the DFR data 

requirement screen has been updated to require DFR data when the occupational postapplication MOEs are less than 2 times the LOC (<200). Due to this change, DFR data are 

no longer required for MCP A. 

Comments submitted by the Center for Biological Diversity in EPA-HQ-OPP-2014-0180-

0020. 

4. Comment: The Center for Biological Diversity 's (CBD) comments focus on the EPA's duty 

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

(the Services) on the registration review of MCPA in accordance with the Endangered 

Species Act (ESA). The CBD comments mention various aspects of the risk assessment 

process, including use of the best available data to develop endangered species risk 

assessments, and evaluation of effects on endangered and threatened species and their 

designated critical habitat. CBD also expresses concern regarding the rigor of the Agency's 

preliminary determinations regarding the effects of MCPA on endangered and threatened 

(listed) species and their designated critical habitat.for the MCPA registration review. 

Response: EPA has reviewed the comments from CBD on the registration review docket 

opening for MCP A and plans to address many of the concerns raised by CBD as part of the 

implementation plan for assessing the risks of pesticides to listed species based on the 

recommendations of the April 2013 National Academy of Sciences (NAS) report. EPA will 

address concerns specific to MCPA in connection with the development of its final 

registration review decision for this pesticide. 

In November 2013, the EPA, along with the Services and the USDA, released a summary 

of their joint Interim Approaches for assessing risks to endangered and threatened (listed) 

species from pesticides. The Interim Approaches were developed jointly by the agencies in 

response to the NAS recommendations and reflect a common approach to risk assessment 

shared by the agencies as a way of addressing scientific differences between the EPA and the 

Services. The NAS report outlines recommendations on specific scientific and technical 

issues related to the development of pesticide risk assessments that EPA and the Services 

must conduct in connection with their obligations under the ESA and FIFRA. 

The joint Interim Approaches were released prior to a stakeholder workshop held on 

November 15, 2013. In addition, the EPA presented the joint Interim Approaches at the 

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December 2013 Pesticide Program Dialogue Committee (PPDC) and State-FIFRA Issues 

Research and Evaluation Group (SFIREG) meetings. The agencies also held a stakeholder 

workshop in April 2014, allowing additional opportunities for stakeholders to comment on 

the Interim Approaches. Additional workshops are planned to enhance stakeholder 

involvement; the next workshop is scheduled for October 2014. As part of a phased, iterative 

process for developing the Interim Approaches, the agencies will also consider public 

comments on the Interim Approaches in connection with the development of upcoming 

registration review decisions. The details of the joint Interim Approaches are contained in 

the white paper, Interim Approaches for National-Level Pesticide Endangered Species Act 

Assessments Based on the Recommendations of the National Academy of Sciences April 2013 

Report, dated November 1, 2013. 

Given that the agencies are continuing to develop and work toward implementation of the 

Interim Approaches to assess the potential risks of pesticides to listed species and their 

designated critical habitat, the ecological problem formulation supporting this Final Work 

Plan for MCPA does not describe the specific ESA analysis, including effects determinations 

for specific listed species or designated critical habitat, to be conducted during registration 

review. In the ecological problem formulation document for MCPA, EPA described the 

screening-level risk assessment to determine the potential effects of MCP A on all taxa of 

non-target wildlife and plants, which will assume that listed species and their designated 

critical habitats may be present in the vicinity of the application of MCP A. This screeninglevel assessment will allow EPA to focus its future evaluations on the types of species where 

the potential for effects exists once the scientific methods being developed by the agencies 

have been fully vetted. While the agencies continue to develop a common method for ESA 

analysis, the planned screening-level risk assessment for the registration review of MCPA 

will describe the level of ESA analysis completed for this particular registration review case. 

Once the agencies have fully developed and implemented the scientific methods necessary to 

complete risk assessments for endangered and threatened (listed) species and their designated 

critical habitats, these methods will be applied to subsequent analyses for MCPA as part of 

completing this registration review. 

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PLANNED DATA NEEDS 

Table I below summarizes the planned data needs for MCPA based on the EFED Registration 

Review Problem Formulation for MCP A, the MCP A. Human Health Risk Assessment Scoping 

Document in Support of Registration Review, the MCP A. Response to Comments Received 

Regarding Scoping Document in Support of Registration Review, and the EFED Response to 

Public Comments on: Preliminary Problem Formulation for Environmental Fate and Ecological 

Risk, Endangered Species, and Drinking Water Assessments for MCPA. The table has been 

updated since the PWP to reflect changes to the data needs. 

Table 1: Planned Data Needs for the MCPA Registration Review 

Estimated 

Guideline 

Study Title 

Timefr ame 

Number-2 Test Material (Months from 

receipt of DCI) 

830.1700 Preliminary analysis MP 8 

835.1410 Volatility-laboratory TEP 12 

850.1730 Aquatic organisms bioavailability, TGAI 12 biomagnification, toxicity (fish)3 

850.2100 A vi an oral toxicity (passerine) TGAI 12 

850.2300 Avian reproduction (mallard duck) TGAI 24 

Environmental chemistry methods and associated 

850.6100 independent laboratory validation (soil, water, and TEP 12 

sediment) 

860.1300 Nature of the residue in plants (peas) PAIRA 24 

860.1500 Crop field trials (peas) TEP 24 

Non- Larval honeybee chronic oral toxicity4 TGAl 12 guideline 

Non- Adult honeybee chronic oral toxicity TGAI 12 guideline 

Non- Larval honeybee acute toxicity4

'

5 TGAI 12 guideline 

TGAI = techmcal grade act1ve mgred1ent; TEP = typ1cal end-use product; PAIRA = pure act1ve mgred1ent radiolabeled; MP = manufacturing use product 

2 On June 27,2012, EPA announced certain revisions in harmonized guideline series 850 - Ecological Effects Tests 

- including renumbering and other designations or changes for some guideline studies. See "Final Test 

Guidelines; OCSPP 850 Series; Notice of Availability" 77 FR 38282, June 27, 2012. 

http://www .regulations.gov/# !documentDetai I; D=EPA-HQ-OPPT -2009-0 154-0028 

3 The planned DCI will indicate that testing is to be done on MCPA 2-ethylhexyl ester. 4 A repeat dose honeybee larval toxicity study may be sufficient to assess both acute and chronic toxicity to 

developing brood. 5 The planned DCl will indicate that this study should follow OECD guideline 237. 

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RISK ASSESSMENTS FOR REGISTRATION REVIEW 

During registration review, the Agency will conduct a comprehensive ecological risk assessment, 

including an endangered species assessment, for all uses of MCP A. For human health, EPA will 

conduct revised dietary, residential, and occupational risk assessments during registration 

review. If human health or ecological toxicological endpoints or points of departure are revised 

based on the data that are required for registration review, they will be considered in the new 

assessments, as well as any changes to the standard operating procedures or default exposure 

assumptions. 

Table 2 below summarizes the planned registration review risk assessments based on the EFED 

Problem Formulation and HED Scoping Document; the planned assessments have not changed 

from what was included in the PWP. 

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Table 2: Planned Risk Assessments for the MCP A Registration Review 

Type of Risk Assessment Conduct? Notes 

Ecoloeical and Environmental Fate 

Comprehensive ecological y 

(species to be assessed 

include terrestrial and aquatic 

organisms), including 

endangered species 

Incidents Will check for For a discussion of reported ecological incidents for 

updates MCPA, see the Problem Formulation. 

Human Health 

Dietary 

Food y An updated drinking water assessment is planned. 

Drinking water y Therefore, a revised dietary assessment may also be 

likely to incorporate revised drinking water estimates. 

Residential 

Handlers y Updated residential handler and post-application 

Post-application y assessments are planned since the Agency has revised 

its standard operating procedure for residential 

pesticide exposure assessment since the last human 

health risk assessment in 2004. 

Bystander y Residential exposure resulting from off-site transport 

may occur as a result of agricultural applications of 

MCP A. The Agency will evaluate the need for spray 

drift and volatilization risk assessment during 

registration review. 

Occupational 

Handlers (mixers, loaders, y An updated occupational assessment may be 

applicators) warranted to reflect any changes to Agency policy. 

Post -application y 

Other 

Aggregate y An updated aggregated assessment may be warranted 

to reflect any updates to the dietary and/or residential 

assessments. 

Cumulative N MCPA is a member ofthe alkylphenoxy herbicide 

class of pesticides. Although the various phenoxy 

herbicides have similar structural components, the 

Agency has not made a determination that they have a 

common mode of toxic action, and therefore a 

cumulative risk assessment is not planned for MCP A. 

Tolerances y The Agency plans to revise the tolerance expression 

for MCP A to be compliant with current policies. 

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Incidents Will check for For a discussion of reported human incidents for 

updates MCPA, see the Scoping Document and the MCPA (2-

methyl-4-chlorophenoxyacetic acid): Tier I Review of 

Human Incidents. 

TIMELINE 

EPA has created the following estimated timeline for the completion of the MPCA registration 

review in Table 3 below. The projected timeline has been updated to reflect completed actions. 

Table 3: Registration Review for MCPA- Projected Registration Review Timeline 

Activities Estimated Date · 

Opening the Docket 

Open Docket and 60-day Public Comment Period March 20 14-completed 

Close Public Comment May 20 14-completed 

Case Development 

Final Work Plan September 20 14-completed 

Issue DCI 20 14 Oct. - Dec. 

Data Submission 2016 Oct. - Dec. 

60-day Public Comment Period for Draft Risk 2018 April - June 

Assessments 

Registration Review Decision 

60-day Public Comment Period for Proposed 20 19 Jan. - March 

Registration Review Decision 

Registration Review Decision and Begin Post-Decision 2020 

Follow-up 

Total (years) 6 

NEXT STEPS 

As noted previously, the Agency plans to require several environmental fate, ecological effects, 

and human health studies for MCPA through a Data Call-In Notice, expected to be issued in late 

2014. 

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