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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 topramezone. This work plan addresses public comments received 

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

review docket (EPA-HQ-OPP-2015-0127). Topramezone is a broad-spectrum systemic herbicide 

registered for use to control broadleaf and certain grass weeds. The mode of action in plants is 

inhibition of the 4-hydroxyphenylpyruvate dioxygenase (HPPD) enzyme. Topramezone is 

currently registered for use on corn, non-cropped areas, residential and non-residential turf grass, 

and aquatic use sites.

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

UPDATES SINCE THE PWP WAS ISSUED

A petition was submitted in November 2015 by technical registrant BASF for the use of 

topramezone on sugarcane. The petition is under review by the Registration Division.

The topramezone registration review data needs table has been revised by updating the 

timeframes of the “Semi-field testing for pollinators (tunnel or colony feeding studies) (Tier 2)” 

and “Field trial of residues in pollen and nectar (Tier 2)” studies from 12 to 24 months.

SUMMARY OF COMMENTS AND AGENCY RESPONSES

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

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

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

the Center for Biological Diversity. 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 

 

1 http://www2.epa.gov/pesticide-reevaluation
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justice, water quality concerns, and trade irritants, but no comments or information were received 

on those issues.

Below are summaries of the public comments and the EPA responses in their entirety. 

Comments submitted by the FIFRA Endangered Species Task Force (FESTF) in EPA-HQOPP-2015-0127-0008

1. Comment 1: The FIFRA Endangered Species Task Force (FESTF) submitted a comment 

informing the Agency that topramezone technical registrants AMVAC and BASF are FESTF 

members and are entitled to rely on FESTF data.

EPA Response 1: The Agency thanks FESTF for its comment and will take this under 

consideration.

Comments submitted by the Center for Biological Diversity in EPA-HQ-OPP- EPA-HQOPP-2015-0127-0009

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 topramezone 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 topramezone on endangered and threatened (listed) species and their designated 

critical habitat for the topramezone registration review. 

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

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

registration review decision for topramezone. 

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 National Academy of Sciences’ (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 report2outlines 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. 

 

2 http://www.nap.edu/catalog/18344/assessing-risks-to-endangered-and-threatened-species-from-pesticides
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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 workshops in April 

2014 and October 2014, 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 development of 

upcoming Registration Review decisions. The details of the joint Interim Approaches are 

contained in the white paper3“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 topramezone 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 topramezone, EPA described the 

screening-level risk assessment to determine the potential effects of topramezone 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 topramezone. 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 topramezone 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 topramezone as part of 

completing this registration review. 

 

3 http://www.epa.gov/endangered-species
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PLANNED DATA NEEDS

Table 1 below summarizes the planned data needs for topramezone based on the Problem 

Formulation for the Ecological Risk and Drinking Water Exposure Assessments to be Conducted 

for the Registration Review for Topramezone, August 26, 2015 and Topramezone. Human-Health 

Assessment Scoping Document in Support of Registration Review, July 10, 2015. The planned

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

Table 1: Planned Data Needs for the Topramezone Registration Review

Guideline 

Number4 Study Title4 Test 

Material

Estimated 

Timeframe

(Months from 

receipt of DCI)

850.2100 Avian oral toxicity (passerine species) TGAI 12

850.2300 Avian reproduction study (mallard) TGAI 24

850.3040 Field testing for pollinators (Tier 3)5 TEP 24

850.4500 Algal toxicity study TEP 12

850.6100 Environmental chemistry methods/independent 

laboratory validations in soil, water6 TGAI 12

Nonguideline 

(OECD 

TG237)

Acute oral toxicity to larval honey bees (Tier 1) TGAI 12

Nonguideline Chronic oral toxicity to adult honey bees (Tier 1) TGAI 12

Nonguideline Chronic oral toxicity to larval honey bees (Tier 1) TGAI 12

NonguidelineSemi-field testing for pollinators (tunnel or colony 

feeding studies) (Tier 2)5 TEP 24

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

TGAI = technical grade active ingredient; TEP = typical end-use product;

 

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 Study may be waived depending on results of Tier 1 pollinator studies.

6 ECM/ILV needed for soil. Only the ILV is needed for water.
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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 topramezone. For human health, 

EPA will conduct revised occupational handler and post-application 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 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 Assessments for the Topramezone 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 Both topramezone and environmental transformation 

products are considered the stressors of concern. 

EFED will use a total toxic residue (TTR) approach, 

which is based on the assumption that the 

transformation products are of equal toxicity to the 

assessed organisms tested with the parent compound. 

The TTRs are defined as topramezone, M670H05, 

M670H01, and M670H10 for all taxa except plants. 

For plants, M670H05 is excluded. 

Incidents Will check for 

updates

For a discussion of reported ecological incidents for 

topramezone, see page 24 of the Problem 

Formulation.

Human Health

Dietary

Food N A new dietary exposure assessment is not anticipated 

to be needed during Registration Review unless there 

are significant increases to the drinking water 

exposure estimates and/or there are updates to the 

toxicity endpoints or safety factors.

Drinking water N A new dietary exposure assessment is not anticipated 

to be needed during Registration Review unless there

are significant increases to the drinking water 

exposure estimates and/or there are updates to the 

toxicity endpoints or safety factors.

Occupational

Handlers (mixers, loaders, 

applicators)

Y Updated occupational handler exposure assessments 

will be conducted during Registration Review for 

topramezone use on corn; all other exposure scenarios

will be re-evaluated if there are changes in the 

toxicity endpoints or safety factors. 

Post-application Y Updated occupational post-application exposure 

assessments will be conducted during Registration 

Review for topramezone use on corn; all other 

exposure scenarios will be re-evaluated if there are 

changes in the toxicity endpoints or safety factors. 

Residential

Handlers N New residential handler exposure and risk 

assessments are not anticipated to be needed during 

Registration Review unless there are updates to the 

toxicity endpoints or safety factors. 
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Post-application N New post-application residential exposure and risk

assessments are not anticipated to be needed during 

Registration Review unless there are updates to the 

toxicity endpoints or safety factors.

Drift/Volatilization Y The Agency will examine the need for a volatilization 

assessment as well as evaluate the potential 

topramezone exposure from spray drift during 

Registration Review.

Other

Aggregate N New aggregate assessments are not anticipated to be 

needed during Registration Review, unless there are 

changes in uses, procedures, drinking water exposure 

estimates, toxicity endpoints, and/or safety factors.

Cumulative N The Agency has sought additional information from 

registrants regarding the mode of action/adverse 

outcome pathway (MOA/AOP) for HPPD inhibiting 

chemicals. Submitted data are currently under review 

and will be used to evaluate the need for a cumulative 

assessment as part of Registration Review.

Tolerances N

Incidents Will check for 

updates

For a discussion of reported human incidents for 

topramezone see page 9 of the Scoping Document and 

the Topramezone: Tier I Review of Human Incidents. 

July 30, 2015

TIMELINE

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

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

Table 3: Projected Topramezone Registration Review Timeline

Activities Estimated Date

Opening the Docket

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

Close Public Comment December 2015 - Completed

Case Development

Final Work Plan February 2016 - Completed

Issue DCI April – June 2016

Data Submission April – June 2018

60-day Public Comment Period for Draft Risk 

Assessments7

Oct. – Dec. 2019

Registration Review Decision

 

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.
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Table 3: Projected Topramezone Registration Review Timeline

Activities Estimated Date

60-day Public Comment Period for Proposed 

Registration Review Decision

July - Sept. 2020

Registration Review Decision and Begin Post-Decision 

Follow-up

2021

Total (years) 6

NEXT STEPS

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

effects studies for topramezone through a Data Call-In Notice, expected to be issued in 2016.