Docket Number EPA-HQ-OPP-201 4-0181 

www.regulations.gov 

MCPB Final Work Plan 

Registration Review 

Case Number 2365 

September 2014 

Approved by: ~ p ~~-' "!;> 

Richard P. Keigwin, Jr. 

Director 

Pesticide Re-evaluation Division 

Date: 
INTRODUCTION 

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

the registration review of MCPB. This work plan addresses public comments received 

concerning the Preliminary Work Plan (PWP), which was posted in the MCPB registration 

review docket (EPA-HQ-OPP-2014-0181). MCPB is a postemergence phenoxy herbicide 

registered for use to control annual and perennial broadleaf weeds in peas, spearmint, and 

peppermint. MCPB is not registered for any non-agricultural uses. The registration review case 

for MCPB includes MCPB acid (PC code 019201) and MCPB sodium salt (PC code 019202). 

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 timeline for MCPB. Lastly, there is a discussion of next steps. 

UPDATES SINCE THE PWP WAS ISSUED 

The PWP listed the pollinator acute oral toxicity and pollinator larval acute toxicity studies as 

anticipated data needs. Due to the Agency's new guidance for assessing risks to bees (see 

guidance document dated June 19,2014 at http://www2.epa.gov/sitcs/production/fi les/2014-

06/documents/pollinator risk assessment guidance 06 19 14.pd0, the Agency is modifying its 

pollinator data requirements for MCPB to include two additional studies: 

• Chronic oral toxicity to larval honeybees 

• Chronic oral toxicity to adult honeybees 

Various phenoxy herbicides are known to contain dioxin/furan impurities as a result of 

manufacturing processes. Previously submitted dioxin/furan data for MCPB did not indicate 

levels of concern. However, modern analytical methods are able to detect previously undetected 

levels of dioxin/furan impurities. This has prompted the Agency to modi.fy its list of data 

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

presence/level of dioxin/furan impurities in MCPB products using the most up-to-date analytical 

methods. The Agency notes that a study already exists which may serve to fulfill this 

requirement (Schoisswohl, 201 1). 

1 http://www .epa.gov/oppsrrd 1/registration_review/ 

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The Agency is also removing the requirement for guideline 860.1500 crop field trials on pea 

because a previously submitted study, MRID 44754101, fulfills this requirement. 

SUMMARY OF COMMENTS AND AGENCY RESPONSES 

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

on March 28,2014 and closed on May 27,20 14, the Agency received 3 submissions from the 

public. Comments were submitted by The MCPB Task Force, the FIFRA Endangered Species 

Task Force (FESTF), and the Center for Biological Diversity. The MCPB Task Force provided 

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

addressed the Agency's information request for additional data on dioxins and furans. The 

FIFRA Endangered Species Task Force commented that the technical registrants, Nufarm 

Limited and Nufarm Americas, Inc., are members of FESTF and are entitled to rely on FESTF 

data for endangered species risk assessment. The Center for Biological Diversity's comment 

addressed the Agency's responsibilities under the Endangered Species Act (ESA). 

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 

soli cited 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 in response to the PWP nor all of the 

Agency's responses. Rather, the Agency has summarized those 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, EPA-HQ-OPP-2014-0181 accessible at www.regulations.gov. Full public comments 

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

the 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, while those relevant to the anticipated human health risk assessment or data needs 

are in the MCP B. Response to Comments Received Regarding Scoping Document in Support of 

Registration Review. 

Comments submitted by the MCPB Task Force in EPA-HQ-OPP-2014-0181-0012. 

I. Comment: The Agency requested data on dioxinlfuran impurities in MCPB products in its 

registration review problem formulation. The Task Force noted that the Agency should 

identifY the needfor such data in the data call-in. 

Response: Various phenoxy herbicides are known to contain dioxinlfuran impurities as a 

result of manufacturing processes. Previously submitted dioxin/furan data for MCPB did not 

indicate levels of concern. However, modem analytical methods are able to detect 

previously undetected levels of dioxin/furan impurities. This 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 MCPB products using the 

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most up-to-date analytical methods. The Agency notes that a study already exists which may 

serve to fulfill this requirement (Schoisswohl, 2011) and should be submitted formally to the 

Agency. 

2. Comment: The MCPB Task Force believes that the request for additional pea field trial data 

has been made without consideration ofMRID 44754101, which was submitted in 1999 by 

interregional Research Project No. 4 (JR4). This study provides MCPB and metabolite 

residue datafrom eight residue trials conducted in typical pea producing areas of the US. 

The Task Force believes that these data are sufficient to support the continued registration of 

MCP B on peas. 

Response: During registration review, the Agency will perform a full evaluation of MRID 

44 7 54 I 0 1 for scientific acceptability. A preliminary screen of the data indicates that the 

study is scientifically acceptable and appears to meet guideline 860.1500 recommendations. 

The Agency believes that MRID 44754101 is adequate to fill the pea field trial data gap. 

Therefore, the Agency is removing the requirement for guideline 860.1500 crop field trials 

on pea. 

Comments submitted by the Center for Biological Diversity in EPA-HQ-OPP-2014-0181-

0011. 

3. Comment: The Centerfor 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 MCP B 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 MCP B on endangered and threatened 

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

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

opening for MCPB 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 MCPB 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. 

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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 

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, iteratjve 

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 MCPB 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 MCPB, EPA described the 

screening-level risk assessment to determine the potential effects of MCPB 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 ofMCPB. 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 ofMCPB 

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 MCPB as part of 

completing this registration review. 

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PLANNED DATA NEEDS 

Table 1 summarizes the planned data needs for MCPB based on the Registration Review; 

Preliminary Problem Formulation for Environmental Fate, Ecological Risk, Endangered 

Species, and Human Health Drinking Water Exposure Assessments for MCPB, MCPB and Salts. 

Human Health Assessment Scoping Document in Support of Registration Review, and MCPB. 

Response to Comments Received Regarding Scoping Document in Support of Registration 

Review. The table has been updated since the PWP to reflect changes to the data needs. 

Table 1: P lanned Da ta Needs for t he MCPB Registration Review 

Estimated 

Timeframe Guideline Study Title Test (Months from Number2 

Material receipt of 

DCI) 

Planned Data Needs for MCPB 

830.1700 Preliminary analysis MP 8 

835.241 0 Photodegradation on soil TGAI 12 

835.4400 Anaerobic aquatic metabolism TGAI 24 

850.1 300 Aquatic invertebrate life cycle (freshwater) TGAI 12 

850.1 350 Aquatic invertebrate life cycle (saltwater) TGAI 12 

850.1400 Fish early-life stage (estuarine/marine) TGAI 12 

850.2100 Avian oral toxicity (passerine )2 TGAI 12 

850.2300 Avian reproduction (mallard duck)3 TGAI 24 

850.4400 Aquatic plant growth (aquatic vascular plant toxicity) TEP 12 

850.4500 Algal toxicity TEP 12 

870.3465 28-day inhalation-rat TGAI 24 

875.2100 Dislodgeable foliar residue TEP 24 

Non- Pollinator acute oral toxicity--honeybee adult

3 TEP 12 

guideline 

Non- Pollinator acute oral toxicity--honeybee larvae 3

•

4 TGAI 12 

guideline 

· Non- Pollinator chronic oral toxicity-honeybee larvae 3

•

4 TGAI 12 guideline 

Non- Pollinator chronic oral toxicity-honeybee adult 3 TGAI 12 

guideline 

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, 20 12. 

http://www .rcgu I at ions.gov/#! documentDetail; D=EPA -HQ-QPPT-2009-0 154-0028 3 The planned DCI will note that in lieu of data on MCPB, the Agency will accept data on MCPA for this data need. 4 A repeat dose honeybee larval toxicity study with both acute and chronic toxicity endpoints may be submitted to 

satisfy this requirement. 

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Table 1: Planned Data Needs for the MCPB Registration Review 

Estimated 

Guideline Timeframe 

Number Study Title Test (Months from 

Material receipt of 

DCI) 

Outstanding Data Requirements from GDCI-019201-26570~ 

835.6100 Terrestrial field dissipation6 TEP In review 

850.1075 Freshwater fish toxicity (sheepshead minnow) TGAI/TEP In review 

850.1400 Fish early-life stage (freshwater) TGAI In review 

860.1850 Confined rotational crop7 TEP In review 

TGAI = techmcal grade active mgred1ent; TEP = typical end-use product; 

RISK ASSESSMENTS FOR REGISTRATION REVIEW 

During r~gistration review, the Agency will conduct a comprehensive ecological risk assessment, 

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

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

review. If 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 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. 

5 The studies listed in this section were previously required through a generic data call-in issued in March 2007. 

These studies will not be included in the anticipated Registration Review DC! because they are already required 

through the earlier DCI and have been previously submined and are undergoing review for acceptabi lity. 6 Data on the storage stability component of this study is still outstanding. Independent laboratory validations are 

required for the previously submined environmental chemistry methods in soil and water. 7 Data for MCPA were submined in lieu of data for MCPB and will be reviewed by the Agency. 

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Table 2: Planned Risk Assessments for the MCPB Registration Review 

Type of Risk Assessment Conduct? Notes 

Ecological and Environmental Fate 

Comprehensive ecological y 

(species to be assessed 

include terrestrial and aquatic 

organisms), including 

endangered species 

Ecological incidents Will check for There was one reported terrestrial plant incident for 

updates MCPB. For a discussion of reported ecological 

incidents for MCPB, see the Problem Formulation. 

Human Health 

Dietary 

Food y An updated drinking water assessment is likely, 

Drinking water y therefore, a revised dietary assessment is planned. 

Residential 

Handlers N There are no registered residential uses ofMCPB, 

Post-application N therefore a quantitative exposure/risk assessment for 

direct residential exposure is not necessary. 

Bystander y Residential exposures resulting from off-site transport 

may occur as a result of agricultural applications of 

MCPB. During registration review, the Agency will 

evaluate the need to assess potential residential 

bystander exposure. 

Occupational 

Handlers (mixers, loaders, y An updated occupational assessment is planned to 

applicators) incorporate occupational exposure data being required 

Post-application y (i.e., dislodgeable foliar residue data). 

Other 

Aggregate y Evaluates the combined risk from dietary and 

residential exposures. An updated aggregated 

assessment may be warranted to reflect any updates to 

the dietary and/or residential assessments. 

Cumulative N MCPB is a member of the alkylphenoxy herbicide 

class of pesticides. Although the 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 MCPB. 

Tolerances y The Agency plans to revise the tolerance expressions 

for MCPB during registration review to be compliant 

with current policies. 

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Human health incidents Will check for For a discussion of reported human incidents for 

updates MCPB, see the Scoping Document and the MCP B [ 4-

(2-methyl-4-chlorophenoxy) butyric acid] and Salts: 

Tier I Review of Human Incidents. There were no 

incidents reported for MCPB. 

TIMELINE 

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

review in Table 3 below. The projected timeline has not changed since the PWP. 

Table 3: Registration Review for MCPB- 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 2014 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 2019 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 MCPB through a Data Call-In Notice, expected to be issued in late 

2014. 

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