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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 prometryn. This work plan addresses public comments received 

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

review docket (EPA-HQ-OPP-2013-0032). Prometryn is an herbicide registered for use on 

vegetable crops, cotton, and fallow ground to control broadleaf grasses and weeds. The greatest 

use of prometryn is on cotton, celery (85% of crop treated), carrots, and fallow ground, based on 

use data from 1998 to 2011. 

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 prometryn. Last, there is a discussion of next steps.

UPDATES SINCE THE PWP WAS ISSUED

Pending Actions

The Agency registered new food uses of prometryn on snap beans and dill on September 11, 

2013. See 78 FR 55635 for details. These were pending when the PWP was completed.

Data Needs 

As a result of comments submitted by the prometryn registrant, Syngenta Crop Protection, an 

anaerobic aquatic metabolism is no longer necessary for registration review. More details are 

provided in the Summary of Comments and Agency Response section of this document. In 

addition, Syngenta has submitted several studies to EPA since the publication of the PWP. 

These studies, which may address some of the data needs identified in the PWP, are currently 

undergoing review. One of the data requirements associated with the January 2010 conditional 

registrations for the prometryn products Caparol® 4L (EPA Registration Number 100-620) and 

Prometryn Technical (100-542), listed as outstanding in the PWP, has recently been fulfilled. 

Specifically, a study submitted to fulfill the guideline requirement OSCPP 870.7800 

(Immunotoxicity) has been reviewed and determined to be acceptable. However, the conditional 

 

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http://www.epa.gov/oppsrrd1/registration_review/
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data requirements for Guidelines 850.1350 (Aquatic Invertebrate Life Cycle for Saltwater), 

860.1300 (Nature of the Residue in Plants for carrot or another root crop), and 870.6200 (Acute 

and Subchronic Neurotoxicity) remain outstanding. 

Water Quality Data 

EPA Region 9 has identified water monitoring data for prometryn. These data were collected by 

the California Department of Pesticide Regulation through their routine surface water monitoring 

program and may be found in the prometryn registration review docket, EPA-HQ-OPP-2013-

0032. Syngenta has also submitted water monitoring data for prometryn. All of the water 

monitoring data for prometryn are undergoing EPA review.

Endangered Species Consultation

As mentioned in the PWP, prometryn is the subject of an ongoing formal consultation with 

National Marine Fisheries Service under Section 7 of the Endangered Species Act. EPA met 

with Syngenta Crop Protection and staff from the National Marine Fisheries Service on March 

29, 2013 to discuss this consultation and pending biological opinion regarding the effects of 

prometryn on Pacific salmonids. Information about this meeting may be found in docket EPAHQ-OPP-2008-0654, which contains information related to this consultation.

SUMMARY OF COMMENTS AND AGENCY RESPONSES

During the 60-day public comment period on the Prometryn PWP, which opened on March 27, 

2013 and closed on May 28, 2013, the Agency received two public comments. Comments were 

submitted by the FIFRA Endangered Species Task Force (FESTF) and by Syngenta Crop 

Protection Corporation (Syngenta). The comments do not address the timeline described in the 

PWP, but they do address the anticipated ecological and human health risk assessments and data 

requirements.

In the PWP, EPA solicited comments on the specific topics of environmental justice, water 

quality concerns, and trade irritants. The Agency received water monitoring data from both 

Syngenta and California’s Department of Pesticide Regulation to address water quality concerns. 

No comments or other information were submitted concerning environmental justice. EPA 

received comments from Syngenta about the differences between US tolerances for prometryn 

and MRLs established by Canada, the European Union, and Australia. Syngenta also 

commented on EPA’s summary of prometryn use and usage as well as the Agency’s summary of 

application rates and other use parameters from current prometryn labels.

This section summarizes public comments that resulted in changes to the anticipated registration 

review data needs, risk assessments, or timeline, or are of a broader regulatory nature. This 

section does not capture every comment or all of EPA’s responses. However, public comments 

and EPA responses in their entirety are located in the docket, EPA-HQ-OPP-2013-0032. EPA’s 

response to comments related to the anticipated ecological risk assessment or data needs are in 

the document, EFED Response to Public Comments Submitted by Syngenta Crop Protection 

LLC Concerning the Registration Review of Prometryn, while those comments relevant to the 

anticipated human health risk assessment or data needs are addressed in the document, 
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Prometryn: Response to Comments on the Human Health Assessment Scoping Document. 

Comments related to the prometryn label data report are addressed in the document, Response to 

Public Comments Submitted by Syngenta Crop Protection Concerning the Registration Review 

of Prometryn. 

Comments submitted by FESTF in EPA-HQ-OPP-2013-0032-0010.

1. Comment: The FIFRA Endangered Species Task Force (FESTF) has submitted both an 

Information Management System and Nature Serve data to address the proximity of 

endangered species to prometryn uses. Syngenta, the technical registrant for prometryn, is 

an FESTF member and is entitled to rely on the FESTF data. 

Response: The Agency thanks FESTF for its comment and will consider the Information 

Management System and Nature Serve data during the prometryn registration review. 

Comments submitted by Syngenta Crop Protection in EPA-HQ-OPP-2013-0032-0011

2. Comment: Enclosed with this submission is data that has not been previously submitted to 

EPA to address the anticipated data need for Guideline Number 835.4100, Aerobic soil 

metabolism.

Response: EPA received the referenced study/overview under MRID numbers 49139001 

and 49139002, and the studies are under review. Until the review is complete and the studies 

are determined by EPA to be acceptable, the anticipated data requirement for OSCPP 

Guideline 835.4100 remains. 

3. Comment: The anticipated data need for OSCPP Guideline 835.4400, anaerobic aquatic 

metabolism is being addressed with the enclosed data. Syngenta believes that degradation of 

prometryn is very likely to be long (i.e., prometryn is essentially stable) as found under 

anaerobic soil metabolism conditions (included within the new aerobic soil metabolism study 

being submitted). Thus, Syngenta accepts the EPA's proposal to deem prometryn stable 

under anaerobic aquatic sediment conditions rather than conduct a new study.

Response: EPA has received an overview of anaerobic and aerobic soil metabolism studies

for prometryn (MRID 4913900). Based on this information, the Agency will assume that 

prometryn is stable under anaerobic aquatic sediment conditions. Therefore, the anticipated 

data requirement for an anaerobic aquatic metabolism study is no longer needed for the 

prometryn registration review.

4. Comment: Based on the qualitatively similar metabolic profiles demonstrated in cotton, 

celery and rice, there is no reason to believe that the carrot metabolism study will indicate 

the need for a ruminant feeding study. Should the carrot study reveal a metabolic profile 

with qualitatively significant differences, we would like to discuss the appropriateness of a 

ruminant feeding study with EPA at that time.
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Response: EPA will evaluate the need for a ruminant feeding study after the carrot (or other 

root crop) metabolism study2is submitted and reviewed. To this end, Syngenta is encouraged 

to submit the carrot metabolism study as soon as possible. In the interim, the Agency plans to

include the ruminant feeding study in the registration review data call-in (DCI) to ensure that 

these data will be available should they be needed for the registration review. 

5. Comment: We have evaluated the MRLs established in the US, Canada, EU, and Australia,

and have compiled this information in Appendix 1. 

Response: The Agency appreciates this information. EPA will work to harmonize US 

tolerances with MRLs and minimize trade irritants during the prometryn registration review. 

PLANNED DATA NEEDS

Table 1 below summarizes the planned data needs for prometryn based on the August 16, 2013 

document, EFED Response to Public Comments Submitted by Syngenta Crop Protection LLC 

Concerning the Registration Review of Prometryn, the March 19, 2013, EFED Registration 

Review Preliminary Problem Formulation for Prometryn, and the February 28, 2013, Prometryn 

Human-Health Assessment Scoping Document in Support of Registration Review. The table has 

been updated since the PWP to reflect changes resulting from public comments. The anaerobic 

aquatic metabolism study listed in the PWP and ecological problem formulation document is no 

longer needed. 

Table 1: Planned Data Needs for the Prometryn Registration Review

Guideline 

Number*

Study Title

Test Material

Estimated 

Timeframe

(Months from 

receipt of 

DCI)

Data Needs for Prometryn (parent)

835.4100 Aerobic soil metabolism TGAI or 

PAIRA 24

835.4300 Aerobic aquatic metabolism TGAI or 

PAIRA 24

850.6100

Environmental Chemistry Methods and Associated 

Independent Laboratory Validation in Water and 

Soil

TGAI 12

860.1480 Magnitude of the Residue –Meat/Milk TGAI 24

870.3465 28-Day Inhalation Study – Rat TGAI 12

875.2100 Dislodgeable Foliar Residue Study TEP 12

Non 

GDLN

ORD Study Method EPA 600/R-099-064. Chronic 

Freshwater Sediment Testing (Chironomus dilutus

or C. tentans

TGAI 24

 

2 Although EPA has received an acceptable carrot field trial study for prometryn, the conditional data requirement 

for a carrot metabolism study (Guideline 860.1300) remains outstanding. 
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Table 1: Planned Data Needs for the Prometryn Registration Review

Guideline 

Number*

Study Title

Test Material

Estimated 

Timeframe

(Months from 

receipt of 

DCI)

Non 

GDLN

ORD Study Method EPA 600/R-099-064. Chronic 

Freshwater Sediment Testing (Hyallela azteca)

TGAI 24

Non 

GDLN

ORD Study Method EPA 600/R-099-020. Chronic 

Estuarine/Marine Sediment Testing (Leptocheirus 

plumulosus)

TGAI 24

Data Needs for the Prometryn Degradate Hydroxypropazine (GS-11526)

850.1010 Acute toxicity freshwater invertebrates Degradate 12

850.4400 Aquatic plant toxicity test using Lemna spp Degradate 12

850.4500 Algal toxicity1 Degradate 12

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

radiolabeled. 

*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

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Freshwater algae, Pseudokirchneriella subcapita, should be tested.

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 prometryn. For human health, EPA 

will conduct revised dietary 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 below summarizes the planned registration review risk assessments based on the EFED 

Problem Formulation and HED Scoping Document. The planned risk assessments have not 

changed from what was included in the PWP.

Table 2: Planned Risk Assessments for the Prometryn 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 

Yes EPA expects to include prometryn, its unextracted

residues, and the degradate hydroxypropazine (GS11526) in the anticipated ecological risk assessment. 

EPA expects to consider slightly different residues for 

plants and animals. See page 32 of the problem 

formulation for details. 
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Planned Risk Assessments for the Prometryn Registration Review

Type of Risk Assessment Conduct? Notes

Incidents Will check 

for updates

EPA has received reports of crop damage, other 

incidents to nontarget plants, and fish kills associated 

with exposure to prometryn; these are summarized on 

pages 29 and 30 of the Problem Formulation.

Human Health

Dietary

Food Yes EPA expects to revise the 2009 dietary risk assessment 

for food and drinking water as part of a pending 

registration decision. The Agency may rely on this 

revised dietary assessment for registration review. 

Drinking water Yes EPA anticipates revising estimates of prometryn 

residues in drinking water. Because there is limited 

information regarding the toxicity of a major 

degradate, hydroxypropazine (GS-11526), EPA intends 

to include it as a residue of concern for drinking water 

along with the parent compound.

Occupational

Handlers (mixers, loaders, 

applicators)

Yes EPA may evaluate occupational risks associated with 

dry flowable (DF) formulations of prometryn. EPA 

expects to evaluate post-application risks for all 

formulations. 

Post-application Yes 

Residential

Handlers No No residential uses are currently registered for 

prometryn; therefore, no residential handler or postapplication assessments are necessary. 

Post-application No

Other

Aggregate Yes Evaluates the combined risk from dietary and 

residential exposures. Any aggregate assessment for 

prometryn would be limited to residues in food and 

water.

Cumulative No Although prometryn is a triazine, and certain triazine 

pesticides were identified as a common-mechanism 

group (CMG), it has been excluded from the triazine 

CMG because it does not share the toxicity profile of 

the CMG triazines. 

Tolerances Yes The tolerance expression for prometryn in 40 CFR 

§180.222 needs to be updated to reflect current Agency 

policies and to ensure that it covers the prometryn 

metabolites and degradates of concern. 

Incidents Will check 

for updates

At this time, there does not appear to be a concern for 

human poisonings, based on the low frequency and 

severity of incident cases reported for prometryn3. 

 

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See the November 13, 2012 memo, Prometryn: Review of Human Incidents, for details. 
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TIMELINE

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

registration review in Table 3 below. The projected timeline has been updated since the PWP to 

reflect impacts of recent Agency actions shortening the timeframe between the FWP and DCI 

issuance and adding a quarter between posting of preliminary risk assessments (PRAs) and 

proposed decisions. 

Table 3: Projected Registration Review Timeline for Prometryn

Activities Estimated Date

Opening the Docket

Open Docket and 60-day Public Comment Period 2013 – March

(completed)

Close Public Comment 2013 – May (completed)

Case Development

Final Work Plan 2013 – September

Issue DCI 2013 – Oct - Dec

Data Submission 2015 – Oct - Dec

60-day Public Comment Period for Draft Risk Assessments42017 – April - June

Registration Review Decision

60-day Public Comment Period for Proposed Registration 

Review Decision

2017 – Oct - Dec

Registration Review Decision and Begin Post-Decision Followup2019

Total (years) 6

NEXT STEPS

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

and human health studies for prometryn through a DCI, expected to be issued in late 2013.

 

4 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.