INTRODUCTION

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

the registration review of cyhalofop-butyl. This work plan addresses public comments received 

concerning the Preliminary Work Plan (PWP), which was posted in the cyhalofop-butyl

registration review docket (EPA-HQ-OPP-2014-0115). Cyhalofop-butyl is an herbicide that is 

registered for use for grass weed control in rice only.

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.

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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 cyhalofop-butyl. Lastly, there is a discussion of next steps.

UPDATES SINCE THE PWP WAS ISSUED

There are no additional updates on cyhalofop-butyl since the PWP.

SUMMARY OF COMMENTS AND AGENCY RESPONSES

During the 60-day public comment period on the cyhalofop-butyl Preliminary Work Plan, which 

opened on September 24, 2014 and closed on November 24, 2014 the Agency received three (3)

of public comments. Comments were submitted by Dow AgroSciences LLC, the Center for 

Biological Diversity (CBD), and the FIFRA Endangered Species Task Force (FESTF). 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 correct statements in the support 

documents for the PWP, or are of a broader regulatory nature. Public comments and EPA 

responses in their entirety are located in the docket, EPA-HQ-OPP-2014-0115. Summarized 

public comments and Agency responses related to the ecological risk assessment are in the

1 http://www.epa.gov/oppsrrd1/registration_review/

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Cyhalofop-butyl: Response to Public Comments on the Preliminary Ecological Risk Assessment 

for Registration Review of Cyhalofop-butyl while those relevant to the growth of rice are in the 

BEAD Response to the Dow AgroSciences Comments on BEAD Memo on Use of Cyhalofopbutyl in Rice Production. 

Comments submitted by Dow AgroSciences LLC in EPA-HQ-OPP-2014-0115-0022.

Comment: Dow AgroSciences (DAS) provided comments intended to address requests, errors, and 

inconsistencies found in the following EPA documents: 1) Cyhalofop-butyl FOCUS Meeting Notes 

Recorded by M. Ranville; 2) Cyhalofop-butyl FOCUS Meeting Notes Recorded by J. Bloom; 3) 

Cyhalofop-butyl Preliminary Work Plan; 4) Preliminary Ecological Risk Assessment for Registration 

Review of Cyhalofop-butyl; 5) Cyhalofop-butyl: Human Health Assessment Scoping Document in 

Support of Registration Review; 6) BEAD Chemical Profile for Registration Review: Cyhalofopbutyl; and 7) Rice Production Practices in the United States and Use of Cyhalofop-butyl for Weed 

Control in Rice Production

Response: The comments presented by DAS provide clarifications and consistency to the 

documents listed above. The response to comments documents from the Environmental Fate and 

Effects Division (EFED) and Biological and Economical Analysis Division (BEAD)

acknowledge general agreement with the comments of DAS on rice production practices and 

address/agree with DAS’ comments on the toxicity of cyhalofop-butyl to aquatic invertebrates 

and terrestrial plants. 

Comment: In the notes by M. Ranville from the FOCUS meeting, DAS disagrees with the 

following statements: “After the first crop is harvested, the field is drained and plowed. Then 

flooded again and ratoon crop might provide small second harvest. It would not be worth much 

to spray with herbicide and it would have to be planned well to meet the 60-day PHI” 

It should be: After the first crop of rice is harvested, the field is dry. The field is re-flooded to get 

the rice to start growing again. The field is not plowed between the first rice crop and the ratoon 

rice.

Response: The Agency agrees that after the harvesting of first crop, the rice field is dry. Soon 

after the harvest, pre-flood nitrogen rate is applied and field is re-flooded to stimulate the growth. 

Field is not plowed between rice crop and the ratoon rice. More information is found in 2012 

Texas Rice Production Guidelines (see especially page 54), at 

http://varietytesting.tamu.edu/rice/varietyfiles/2012_Rice_Production_Guidelines.pdf

Comments submitted by CBD in EPA-HQ-OPP-2014-0115-0017.

Comment: CBD’s comments focus on the EPA’s independent duty under the Endangered 

Species Act (ESA) to consult with the U.S. Fish and Wildlife Service and the National Marine 

Fisheries Service (the Services) on the registration review of cyhalofop-butyl.

Response: EPA plans to address the concerns raised by CBD as part of the implementation plan 

for assessing the risks of pesticides to listed species, which will be based on the 

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

address concerns specific to cyhalofop-butyl’s effects on listed species in connection with the 

development of its registration review decision.

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At this time, EPA has not fully developed its risk assessment process for listed species. In 

November 2013, the EPA, along with the Services and the U.S. Department of Agriculture, 

released a summary of their joint Interim Approaches for assessing risks to 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, available at http://www.nap.edu/catalog.php?record_id=18344, 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 December 2013 Pesticide Program Dialogue Committee (PPDC) and 

State-FIFRA Issues Research and Evaluation Group (SFIREG) meetings, allowing additional 

opportunities for stakeholders to comment on the Interim Approaches. 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, available at http://www.epa.gov/espp/2013/nas.html

Comments submitted by FESTF in EPA-HQ-OPP-2014-0115-0016.

Comment: FESTF noted that DAS is member of the task force and is entitled to make use of the 

FESTF database on species proximity to use sites. 

Response: The Agency is aware of the data developed by FESTF and will use those data to 

evaluate risks to listed species, as appropriate.

PLANNED DATA NEEDS

Table 1 below summarizes the planned data needs for cyhalofop-butyl based on the Cyhalofop-butyl. 

Human Health Assessment Scoping Document in Support of Registration Review. The planned data needs 

have not changed from what was included in the PWP.

Table 1: Planned Data Needs for the cyhalofop-butyl Registration Review

Guideline 

Number Study Title2 Test Material

Estimated Timeframe

(Months from receipt of 

DCI)

870.3465 90-day Inhalation Rat2 TGAI 24

TGAI = technical grade active ingredient

2 Although the guideline is for a 90-day study, a 28-day study is considered adequate to satisfy the anticipated data 

requirement. The HASPOC concluded, based on weight-of-evidence considerations, that a subchronic inhalation 

toxicity study is needed; however, if the registrant can provide particle size distribution data for the granular product

such that the Agency can determine what fraction of the product is both respirable and inhalable, the Agency could 

re-consider the need for the inhalation study.

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RISK ASSESSMENTS FOR REGISTRATION REVIEW

During registration review, the Agency anticipates the need to conduct a revised occupational 

handler risk assessment and will consider the potential for bystander volatilization assessments. 

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, along with any changes 

to the standard operating procedures or default exposure assumptions.

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

Scoping Document, and the planned assessments have not changed from what was included in 

the PWP. As noted in Table 2, EFED has already developed its preliminary risk assessment for 

cyhalofop-butyl.

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Table 2: Planned Risk Assessments for the Cyhalofop-butyl Registration Review

Type of Risk Assessment Conduct? Notes

Ecological and Environmental Fate

Comprehensive ecological 

(species to be assessed 

include terrestrial and aquatic 

organisms), including an 

assessment of risks to 

threatened and endangered 

species

Has been 

conducted

The Agency has already developed and released its 

Preliminary Ecological Risk Assessment for 

Registration Review of Cyhalofop-butyl. The Agency 

was able to develop the risk assessment because the 

existing database is sufficient to support an 

assessment without the receipt and consideration of 

new data. Based on currently registered uses and 

labeled rates, the preliminary assessment identifies 

potential risks to some non-target organisms. An 

endangered species assessment has not been 

conducted at this time.

Incidents Will check for 

updates

Four ecological incidents have been reported for 

cyhalofop-butyl; see page 29 of the risk assessment. 

The Agency will continue to monitor its incident 

databases.

Human Health

Dietary

Food No Unless needed due to any updates to points of 

departure or exposure estimates from the diet. The 

dietary exposure database is adequate to support the 

existing registrations. Dietary risks estimated for the 

2012 assessment were not of concern. 

Drinking water No Unless needed due to any updates to points of 

departure or exposure estimates from drinking water. 

Drinking water risks estimated for the 2012 

assessment were not of concern. 

Occupational

Handlers (mixers, loaders, 

applicators)

Yes A handler inhalation assessment will be needed to 

account for inhalation toxicity or particle size 

distribution data.

Post-application No A dermal endpoint has not been identified for 

cyhalofop-butyl, so an occupational post-application 

risk assessment is not needed.

Residential

Handlers No There are no residential handler scenarios for 

cyhalofop-butyl.

Post-application Yes During registration review, the Agency will consider 

the potential for inhalation exposure to bystanders 

through volatilization.

Other

Aggregate No Because there are no residential uses of cyhalofopbutyl, an aggregate assessment is not needed.

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Table 2: Planned Risk Assessments for the Cyhalofop-butyl Registration Review

Cumulative No EPA has not made a common mechanism of toxicity 

finding as to cyhalofop-butyl and any other 

substances, and cyhalofop-butyl does not appear to 

produce a toxic metabolite produced by other 

substances.

Tolerances No There are no Codex Alimentarius Commission 

(Codex) or Canadian maximum residue limits 

(MRLs) for cyhalofop-butyl. As a result, there are no 

harmonization issues at the present time. 

Incidents Will check for 

updates

For a discussion of reported human incidents for 

cyhalofop-butyl, see page 10 of the Scoping 

Document and the Cyhalofop-butyl: Tier I Review of 

Human Incidents. Based on the low frequency and 

severity of reported incidents, there does not appear 

to be a concern at this time that would warrant further 

investigation. 

TIMELINE

EPA has created the following estimated timeline for the completion of the cyhalofop-butyl

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

Table 3: Registration Review for Cyhalofop-butyl – Projected Registration Review 

Timeline

Activities Estimated Date

Opening the Docket

Open Docket and 60-day Public Comment Period Sept. 2014 – Completed

Close Public Comment Nov. 2014 – Completed

Case Development

Final Work Plan Mar. 2015 - Completed

Issue DCI April - June 2015

Data Submission April - June 2017

60-day Public Comment Period for Draft Risk Assessments31] Oct. – Dec. 2018

Registration Review Decision

60-day Public Comment Period for Proposed Registration Review 

Decision 

July – Sept. 2019

Registration Review Decision and Begin Post-Decision Follow-up 2020

Total (years) 6

NEXT STEPS

As noted previously, the Agency plans to require data to support a human health risk assessment 

for cyhalofop-butyl through a Data Call-In Notice, expected to be issued in April- June of 2015. 

3 The regulations governing Registration Review generally require the Agency to provide a public comment period 

of at least 30 calendar days for draft risk assessments; see 40 CFR Part 155.53(c). For conventional pesticides, the 

Agency plans to provide a 60 calendar day public comment period generally for draft risk assessments.

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