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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 dimethomorph. This work plan addresses public comments received 

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

registration review docket (EPA-HQ-OPP-2013-0045). Dimethomorph is a systemic morpholine 

fungicide developed to control downy mildews, late blights, and crown and root rots on grapes, 

potatoes, tomatoes, and other vegetables. Dimethomorph is also registered for use on various 

non-agricultural sites, such as forest trees and ornamental plants, but there are no registered 

residential uses. 

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

UPDATES SINCE THE PWP WAS ISSUED

There are no additional updates on dimethomorph since the PWP. 

SUMMARY OF COMMENTS AND AGENCY RESPONSES

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

opened on March 27, 2013 and closed on May 28, 2013, the Agency received two public 

comments. Comments were submitted by BASF, the dimethomorph technical registrant, and by 

the FIFRA Endangered Species Task Force. 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. No comments or 

information were received with regard to environment justice or water quality concerns, but 

BASF did comment on a tolerance issue which could result in a potential trade irritant. 

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 

 

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 http://www.epa.gov/oppsrrd1/registration_review/ 
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registration review data needs, risk assessments, or timeline, or are of a broader regulatory 

nature. All public comments and the Agency’s response to comments documents can be found 

in the dimethomorph docket EPA-HQ-OPP-2013-0045. 

Response to Public Comments by BASF Concerning the Registration Review of 

Dimethomorph from EPA Docket ID No. EPA-HQ-OPP-2013-0045, DP Barcode #413157. 

July 30, 2013. R. Prieto (Biological and Economic Analysis Division). 

Response to Comments Received During the Dimethomorph Initial Registration Review 

Docket Opening 60-Day Public Comment Period. July 31, 2013. T. Gibson (Registration 

Division), S. Piper (Health Effects Division), Monica Wait (Pesticide Re-evaluation 

Division). 

Registration Review: EFED Response to Registrant Comments on the Registration Review of 

Dimethomoph. July 30, 2013. S. Carey and I. Abdel-Saheb (Environmental Fate and Effects 

Division). 

Comments submitted by BASF in EPA-HQ-OPP-2013-0045-0010. 

Comment: Based on previously submitted dimethomorph data and endpoints required for risk 

assessment, BASF proposes to conduct a freshwater fish acute toxicity study with the fathead 

minnow (GDLN 850.1075) in lieu of the fish early-life stage toxicity study with the rainbow 

trout (GDLN 850.1400), which was listed as an anticipated data need in the PWP.

Response: The Agency agrees with BASF’s proposal that an acute study (GDLN 850.1075) 

with the fathead minnow, a freshwater fish, rather than an early life-stage study with the 

rainbow trout would be capable of producing the necessary endpoints to conduct an aquatic 

risk assessment. This endpoint from 850.1075 would then be compared with the available 

acceptable fathead minnow early-life study to derive an acute-to-chronic ratio (ACR) value 

in order to calculate toxicity endpoints for the aquatic risk assessment. The Fish Early LifeStage study (GDLN 850.1400) with the rainbow trout that was requested in the 

dimethomorph PWP and preliminary problem formulation is no longer required. A fish acute 

toxicity study with the fathead minnow is now required. 

Comment: BASF sought clarification as to whether the Agency is requesting an environmental 

chemistry method (ECM) and independent laboratory validation (ILV) for water only, or 

ECMs and ILVs for both water (GDLN 850.6100) and soil (GDLN 850.6100). Furthermore, 

BASF believes that the requirement for a soil ECM and ILV have been satisfied by a previous 

submission. Additionally, BASF noted that an ECM for the determination of dimethomorph in 

water is present and has been validated but that no ILV is currently available. 

Response: The Agency’s preliminary problem formulation requested an ECM and ILV for 

both water and soil. In the Preliminary Work Plan, only the ECM and ILV for water was 

listed individually in Table 1: Anticipated Data Needs. The ECM and ILV for soil was not 

listed in Table 1 because it is required as part of GDLN 835.6100, terrestrial field dissipation, 

under footnote 7 of the guideline. Since the full terrestrial field dissipation study was listed 

in Table 1, inclusive of the ECM and ILV for soil, there was no need to list it separately. 
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Based on BASF’s comment and the submitted information in MRID 44996201, the request 

for an ECM and ILV for the determination of dimethomorph in soil has been satisfied. 

Regarding the data requirement for an ECM and ILV in water (GDLN 850.6100), BASF 

stated that the ECM for water is available. As such, BASF should submit water ECM to the 

Agency. EPA confirms that the ILV for water continues to be required.

Comment: Regarding the data requirement for a terrestrial field dissipation study (GDLN 

835.6100), BASF states that they submitted four terrestrial field dissipation studies to EPA 

on October 24, 2012 as a condition of registration as stated in an April 3, 2009 letter from 

the Office of Pesticide Program’s Registration Division. BASF suggests that these studies 

satisfy the condition of registration and therefore meet the 835.6100 guideline requirements.

Response: Previously submitted dimethomorph terrestrial field dissipation studies (MRIDs 

48980101 thru 48980104) and the recently submitted stability study (MRID 49126901) are 

currently in review. The data gap will remain until the reviews are completed and the studies 

are found to be acceptable. 

Comment: A dimethomorph aerobic aquatic metabolism study (MRID 43917233) found no 

major metabolites greater than 10% of the total applied radioactivity, and based on that, 

BASF believes that the aquatic and drinking water assessments should be based on parent 

dimethomorph only rather than parent dimethomorph plus a previously unidentified 

degradate. 

Response: EPA concurs. The aquatic exposure and drinking water assessments will both be 

conducted for parent only. 

 
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PLANNED DATA NEEDS

Table 1 below summarizes the planned data needs for dimethomorph based on the following 

documents: Registration Review: Preliminary Problem Formulation for Environmental Fate 

and Ecological Risk, Endangered Species, and Drinking Water Assessments for Dimethomorph; 

Dimethomorph: Human Health Assessment Scoping Document in Support of Registration 

Review; and the three response to comments documents cited in the previous section. 

The table has been updated since the PWP to reflect public comments which resulted in changes 

to the data needs. 

Table 1: Planned Data Needs for the Dimethomorph Registration Review 

Guideline 

Number2 Study Title2 

Test Material 

Estimated 

Timeframe 

(Months from 

receipt of DCI) 

835.61003 Terrestrial field dissipation study (full study) TEP 24 

850.1075 Fish acute toxicity study (freshwater fish, fathead 

minnow) TGAI 12 

850.2100 Avian oral toxicity (passerine species) TGAI 12 

850.6100 Environmental chemistry methods and associated 

independent laboratory validation for water TGAI 12 

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

 

 

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 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 3

 Previously submitted terrestrial field dissipation studies are currently in review. However, this data need will 

remain until the reviews are completed and the studies are found to be acceptable. 
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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 dimethomorph. 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 assessments have not changed 

from what was included in the PWP. 

Table 2: Planned Risk Assessments for the Dimethomorph 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 For terrestrial and aquatic exposures, risk calculations 

will be for the parent dimethomorph alone. 

Incidents Will check for 

updates 

Currently, there are no reported ecological incidents 

for dimethomorph. For further information, see page 

12 of the EFED Problem Formulation. 

Human Health 

Dietary 

Food Y Only a chronic dietary exposure assessment is 

anticipated because no acute endpoint has been 

identified for dimethomorph. 

Drinking water Y The previous drinking water assessment used a 

conservative Tier I approach and was conducted for 

the parent dimethomorph only. 

Occupational 

Handlers (mixers, loaders, 

applicators) 

Y The anticipated occupational assessment will be for 

inhalation exposures only because no dermal endpoint 

Post-application Y was identified in available studies. 

Residential 

Handlers N There are no registered residential uses. 

Post-application N 

Other 

Aggregate N Because there are no residential exposures, an 

aggregate assessment, which evaluates the combined 

risk from dietary and residential exposures, is not 

needed. 

Cumulative N Dimethomorph is not part of a cumulative group. 
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Table 2: Planned Risk Assessments for the Dimethomorph Registration Review 

Type of Risk Assessment Conduct? Notes 

Tolerances Y Current tolerances, established in 40 CFR Part 

180.493, will be evaluated during registration review. 

Incidents Will check for 

updates 

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

that would warrant further investigation of 

dimethomorph human incidents. For a more detailed 

discussion, see Dimethomorph: Review of Human 

Incidents in the docket or page 6 of the HED Scoping 

Document. 

TIMELINE

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

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 FWP and DCI 

issuance and adding a quarter in between posting of the preliminary risk assessments and 

proposed decisions. 

Table 3: Projected Registration Review Timeline for Dimethomorph

Activities Estimated Date 

Opening the Docket 

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

Close Public Comment May 2013 – Completed 

Case Development 

Final Work Plan Sept. 2013 – Completed 

Issue DCI 2014 – Jan. - March 

Data Submission 2016 – Jan. - March4

60-day Public Comment Period for Draft Risk Assessments5 2017 – July - Sept.4

Registration Review Decision 

60-day Public Comment Period for Proposed Registration Review 

Decision 

2018 – Jan. - March4

Registration Review Decision and Begin Post-Decision Follow-up 2019 4 

Total (years) 6 4 

 

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 If the terrestrial field dissipation studies (GDLN 835.6100) currently in review are found to be acceptable, the 

timeline for data submission would be shortened from 24 months to 12 months. As such, the projected dates for 

data submission, draft risk assessments, proposed registration review decision, and post-decision follow-up would 

be moved up by one year. In that case, the total length of the registration review process for dimethomorph would 

be five years instead of six. 5

 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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NEXT STEPS

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

effects studies for dimethomorph through a Data Call-In Notice, expected to be issued in early2014.