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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 DMDS. This work plan addresses public comments received 

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

review docket (EPA-HQ-OPP-2013-0488). DMDS is a broad-spectrum pre-plant soil fumigant 

currently registered for use to control or suppress nematodes, various soil borne pathogens, and 

weeds on the following crops: strawberry, tomato, pepper, eggplant, cucumber, squash (all 

varieties), melons (all varieties), blueberry, forest nursery crops and field grown ornamentals. 

The registered uses of DMDS as a pre-plant soil fumigant are considered non-food because 

DMDS quickly degrades or is metabolized into non-toxic degradates in the soil. The strong odor 

of DMDS is described as the smell of garlic or rotting/decaying matter; however the odor 

threshold is orders of magnitude below the level where nasal irritation is identified and may 

serve as a warning that the chemical is being used in the area. 

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

UPDATES SINCE THE PWP WAS ISSUED 

There are no additional updates on DMDS since the PWP. 

SUMMARY OF COMMENTS AND AGENCY RESPONSES 

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

on December 20, 2013 and closed on February 18, 2014, the Agency received one public 

comment, from the Center for Biological Diversity. EPA’s response to this comment is included 

in this section. The comment addresses the timeline described in the PWP as well as the planned 

ecological risk assessment with regard to threatened and endangered species. 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. 

 

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 http://www.epa.gov/oppsrrd1/registration_review/ 
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The public comment did not result in changes to the anticipated registration review data needs, 

risk assessments, or timeline. 

Comments submitted by the Center for Biological Diversity located at EPA-HQ-OPP-2013-

0488-0009. 

Comment: The Center for Biological Diversity’s (CBD) 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 DMDS. 

 

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

opening for DMDS 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 DMDS in connection with the development of its registration review 

decision for DMDS. 

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 

(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 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 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. 

PLANNED DATA NEEDS 

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

Review Problem Formulation for Dimethyl Disulfide and the Dimethyl Disulfide Human-Health 

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

not changed from what was included in the PWP. 
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Table 1: Anticipated Data Needs for the DMDS Registration Review 

Guideline 

Number2 Study Title2 Test 

Material 

Estimated 

Timeframe 

(Months from 

receipt of DCI) 

NonGuideline Acute Honey Bee Vapor Exposure TGAI 24 

Outstanding Data Requirements from Conditional Registration3

875.1300 Inhalation Exposure, outdoor (broadcast shank 

injection with a high barrier tarp) TEP Due September 1, 2014 

875.1300 Inhalation Exposure, outdoor (raised bed shank 

injection with a high barrier tarp) TEP Due September 1, 

2014

875.1300 Inhalation Exposure, outdoor (raised bed drip 

irrigation with a high barrier tarp) TEP Due September 1, 

2014

835.8100 Field volatility (broadcast shank injection with a 

high barrier tarp) TEP Due September 1, 

2014

835.8100 Field volatility (raised bed shank injection with a 

high barrier tarp) TEP Due September 1, 

2014

835.8100 Field volatility (raised bed drip irrigation with a 

high barrier tarp) TEP Due September 1, 

2014

850.4150 Terrestrial plant toxicity, vegetative vigor tier II TEP In Review 

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 

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 The studies listed in this section were previously required as conditions of registration [July 9, 2010] and were 

outstanding at the time of the PWP. These studies will not be included in the anticipated Registration Review 

DCI because they are already required and have been submitted as conditions of registration. 

http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2007-0092-0029
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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 DMDS. For human health, EPA will 

conduct revised occupational and residential (bystander) 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 DMDS 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 

Incidents Will check for 

updates 

For a discussion of reported ecological incidents for 

DMDS, see page 23 of the Problem Formulation. No 

incidents have been reported for DMDS. 

Human Health 

Dietary 

Food N Registered uses of DMDS are considered non-food; 

dietary exposure is not expected. 

Drinking water N Based on environmental fate data in water, the 

Agency does not expect DMDS to adversely impact 

drinking water sources.

Occupational 

Handlers (mixers, loaders, 

applicators) 

Y Revised occupational risk assessments may be 

necessary based on submission of the conditionally 

required worker exposure and field volatility data 

listed in Table 1. 

Post-application Y 

Residential 

Handlers N There are currently no registered residential uses of 

DMDS. 

Post-application N There are currently no registered residential uses of 

DMDS. 

Bystander Y Additional or revised residential bystander risk 

assessments may be necessary based submission of 

the conditionally required worker exposure and field 

volatility data listed in Table 1. 
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Other 

Aggregate N Evaluates the combined risk from dietary and 

residential exposures. 

Cumulative N DMDS has not been identified as a member of a 

cumulative group that shares a common mechanism 

of toxicity. 

Tolerances N The currently registered uses of DMDS as a pre-plant 

soil fumigant are considered non-food and do not 

require food tolerances. 

Incidents Will check for 

updates 

For a discussion of reported human incidents for 

DMDS see page 9 of the Scoping Document and 

Dimethyl Disulfide (DMDS): Tier 1 Review of Human 

Incidents. 

TIMELINE

EPA has created the following estimated timeline for the completion of the DMDS registration 

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

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

Activities Estimated Date 

Opening the Docket 

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

Close Public Comment Feb. 2014 – Completed

Case Development 

Final Work Plan May 2014 –Completed 

Issue DCI 2014 – July-September 

Data Submission 2016 – July-September 

60-day Public Comment Period for Draft Risk Assessments4 2018 – January-March 

Registration Review Decision 

60-day Public Comment Period for Proposed Registration Review 

Decision 

2018 – July-September 

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

Total (years) 6 

NEXT STEPS 

As noted previously, the Agency plans to require an ecological effects study for DMDS through 

a Data Call-In Notice, expected to be issued in 2014. 

 

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 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.