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INTRODUCTION

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

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

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

review docket (EPA-HQ-OPP-2015-0603). Pinoxaden is a selective and systemic herbicide 

registered for use to control annual grass weeds and certain broad leaf weeds in barley, winter 

wheat, and spring wheat. Pinoxaden is not registered for residential, public recreational, or other 

non-agricultural use.

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 pinoxaden. Lastly, there is a discussion of next steps.

UPDATES SINCE THE PWP WAS ISSUED

There are no additional updates on pinoxaden since the PWP.

SUMMARY OF COMMENTS AND AGENCY RESPONSES

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

opened on October 2, 2015 and closed on December 1, 2015, the Agency received three public 

comments. Comments were submitted by the FIFRA Endangered Species Task Force (FESTF), 

the Center for Biological Diversity, and Syngenta Crop Protection, LLC. 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 addressed 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-2015-

 1 http://www2.epa.gov/pesticide-reevaluation
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0603. Summarized public comments and Agency responses related to the anticipated ecological

risk assessment or data needs are in the EFED Response to Registrant Comments Regarding the 

Registration Review Problem Formulation for Pinoxaden, located in the pinoxaden registration 

review docket. 

Comments submitted by Syngenta Crop Protection, LLC Syngenta) In EPA-HQ-OPP2015-0603-0015. 

Comment: Syngenta presented alternative analyses of ecological effects endpoints and noted 

discrepancies in reported test materials. Syngenta also noted that they intend to submit several 

studies for EPA review.

Response: The Agency agrees with the identified errors regarding test formulations and further 

explains the endpoints chosen in the EFED Response to Registrant Comments Regarding the 

Registration Review Problem Formulation for Pinoxaden. In addition, EPA has received the 

referenced studies and will review them in preparation for the draft risk assessment.

Comment: Syngenta believes that they have submitted adequate information to demonstrate 

that technical pinoxaden is practically non-toxic to adult honey bees on an acute oral toxicity 

basis and that no further information is needed for the registration review of pinoxaden.

Response: The Agency is requesting additional information on the solubility issues encountered 

with the adult bee acute oral toxicity study (MRID 47293203). If additional information 

demonstrates that testing was conducted with a stable and homogeneous suspension, further 

testing would likely not be required.

Comment: Syngenta comments that a more recent Local Lymph Node Assay (LLNA) has been 

conducted since the Guinea pig maximization assay referenced in the HED Scoping Document 

and should be used to update the skin sensitization safety assessment profile.

Response: The above referenced LLNA study (MRID 48346201) was overlooked in the scoping 

process and will be cited in the pinoxaden risk assessment.

Comment: Syngenta notes that all end-use products are emulsifiable concentrates (EC). 

Response: The EPA agrees that all end-use products are emulsifiable concentrates, and that 

information will be reflected in the risk assessment. 

Comment: Syngenta notes that pinoxaden products are not registered for use on durum wheat. 

Response: EPA agrees that current labels prohibit use on durum wheat.
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Comments submitted by the FIFRA Endangered Species Task Force (FESTF) in EPA-HQOPP-2015-0603-0013. 

Comment: Syngenta is a FESTF member and is entitled to rely on the FESTF data to support

the analysis of pinoxaden use and potential exposure to endangered and threatened (listed) 

species.

Response: The Agency will consider the FESTF data during the pinoxaden registration review.

Comments submitted by the Center for Biological Diversity (CBD) in EPA-HQ-OPP-2015-

0603-0014. 

Comment: CBD’s 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 pinoxaden in accordance with the Endangered Species Act (ESA). CBD’s 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 listed species and their 

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

preliminary determinations regarding the effects of pinoxaden on listed species and their 

designated critical habitat. 

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

opening for pinoxaden 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 pinoxaden in connection with the development of its final 

registration review decision for pinoxaden.

In November 2013, the EPA, along with the Services and the USDA, 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 report 

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 report2

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. The agencies also held stakeholder workshops in April 

and October 2014, and in April 2015, allowing additional opportunities for stakeholders to 

comment on the Interim Approaches. Additional workshops are planned to enhance stakeholder 

involvement. 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 

 2 http://www.nap.edu/catalog.php?record_id=18344
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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”3, 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 FWP for 

pinoxaden 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 pinoxaden, EPA described the screeninglevel risk assessment to determine the potential effects of pinoxaden 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 pinoxaden. This screening-level 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 pinoxaden 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 

listed species and their designated critical habitats, these methods will be applied to subsequent 

analyses for pinoxaden as part of completing this registration review.

PLANNED DATA NEEDS

Table 1 below summarizes the planned data needs for pinoxaden based on the EFED 

Registration Review Problem Formulation for Pinoxaden, Pinoxaden Human Health Assessment 

Scoping Document in Support of Registration Review and Response to Comments document. The 

planned data needs have not changed from what was included in the PWP.

 3 http://www.epa.gov/espp/2013/nas.html
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Table 1: Data Needs for the Pinoxaden Registration Review

Guideline 

Number4 Study Title Test Material

Estimated

Timeframe

(Months from 

receipt of DCI)

Data Needs for the Parent Pinoxaden

850.6100 Environmental Chemistry Method and 

Independent Laboratory Validation for Water TGAI 12

Non-Guideline 

(Tier 1) Honey bee larvae acute toxicity TGAI 12

Non-Guideline

(Tier 1) Honey bee adult chronic oral toxicity TGAI 12

Non-Guideline 

(Tier 1) Honey bee larvae chronic toxicity TGAI 12

Non-Guideline 

(Tier 2)5

Semi-field testing for pollinators (tunnel or 

colony feeding studies TEP or TGAI 24

Non-Guideline 

(Tier 2)5 Field trials of residues in pollen and nectar TEP 24

OCSPP 850.3040 

(Tier 3)5 Field testing for pollinators TEP 24

Data Needs for the Pinoxaden Degradate

850.6100 Environmental Chemistry Method and 

Independent Laboratory Validation for Water NOA-407854 12

850.6100 Environmental Chemistry Method and 

Independent Laboratory Validation for Water NOA-447204 12

Outstanding Data Requirements from Conditional Registration(s)6

Non-Guideline 

(Tier 1) Honey bee adult acute oral toxicity TGAI Due 

9/2/2016

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 pinoxaden. 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 

 4 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/#!documentDetail;D=EPA-HQ-OPPT-2009-0154-0028 5 Tier 2 and 3 (Semi-field and full field colony-level studies). The need for a higher-tiered test for pollinators will be determined 

based upon lower-tiered tests and/or other lines of data and the need for a refined pollinator risk assessment. 6 The study listed in this section was previously required as a condition of registration in 2005 and is due on 

9/2/2016 per the Agency’s 9/2/2015 letter to Syngenta. This study will not be included in the anticipated 

Registration Review DCI because it is already required as a condition of registration.
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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 Pinoxaden Registration Review

Type of Risk Assessment Conduct? Notes

Ecological and Environmental Fate

Comprehensive ecological 

(species to be assessed include 

terrestrial and aquatic 

organisms), including 

endangered species 

Y The Total Toxic Residue approach will be used for modeling exposure 

to all three pinoxaden residues (pinoxaden parent, NOA-407854, and 

NOA-447204).

Incidents Will check 

for updates

For a discussion of reported ecological incidents for pinoxaden see 

page 26 of the Problem Formulation.

Human Health

Dietary

Food Y Revised dietary risk assessments may be required to reflect the most 

recent dietary exposure models, newly estimated drinking water 

concentrations and/or changes to the toxicological endpoints. 

Drinking water

Occupational

Handlers (mixers, loaders, 

applicators)

Y Updated occupational exposure assessments may be required during 

Registration Review to reflect all currently registered uses and 

consider new exposure estimates based on current SOPs and science 

policies or if there are changes in toxicological endpoints. 

Post-application

Residential

Handlers N Pinoxaden is not registered for use in residential or public settings. 

Post-application

Spray drift/volatilization Y The need for a spray drift and volatilization risk assessment for 

pinoxaden will be examined during Registration Review. 

Other

Aggregate Y Evaluates the combined risk from dietary and residential exposures. 

As there are no residential uses, a revised aggregate assessment would 

be equivalent to the revised dietary assessment.

Cumulative N Not applicable; pinoxaden has not been identified as a member of a 

cumulative group that shares a common mechanism of toxicity. 

Tolerances Y The need for livestock commodity tolerances will be re-evaluated. In 

addition, the tolerance expression in 40 CFR§180.611 will need to be 

updated so that it appropriately covers the metabolites and degradates 

of pinoxaden and specifies the residues to be measured for each 

commodity. Potential harmonization of the residues of concern for 

U.S. tolerances and Canadian maximum residue limits (MRLs) will be 

evaluated.

Incidents Will check 

for updates

For a discussion of reported human incidents for pinoxaden, see page 

8 of the Scoping Document and the Tier I (Scoping) Review of Human 

Incidents.
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TIMELINE

EPA has created the following estimated timeline for the completion of the pinoxaden 

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

Table 3: Registration Review for Pinoxaden– Projected Registration Review Timeline

Activities Estimated Date

Opening the Docket

Open Docket and 60-day Public Comment Period September 2015 – Completed

Close Public Comment November 2015 – Completed

Case Development

Final Work Plan March 2016 – Completed

Issue DCI 2016 – April – June

Data Submission 2018 – April – June

60-day Public Comment Period for Draft Risk Assessments7 2019 – October – December

Registration Review Decision

60-day Public Comment Period for Proposed Registration 

Review Decision 2020 – July – September

Registration Review Decision and Begin Post-Decision Followup

2021

Total (years) 6

NEXT STEPS

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

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

June 2016. 

 7 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.