2

DMDS Preliminary Work Plan – Table of Contents

OVERVIEW .........................................................................................................................................4

ANTICIPATED DATA NEEDS.........................................................................................................5

STATUTORY AND REGULATORY AUTHORITY ......................................................................6

CHEMICAL FACTS............................................................................................................................6

USE AND USAGE INFORMATION ................................................................................................7

RECENT ACTIONS ............................................................................................................................8

ANTICIPATED RISK ASSESSMENTS FOR REGISTRATION REVIEW..................................8

TIMELINE..........................................................................................................................................10

NEXT STEPS .....................................................................................................................................10

Appendix – Additional Areas Considered in the DMDS Registration Review..........................11

References:

This Preliminary Work Plan summarizes the Environmental Protection Agency's current position 

based on the following documents:

1. Dimethyl Disulfide Human-Health Assessment Scoping Document in Support of 

Registration Review. Charles Smith, Shalu Shelat, Nancy McCarroll. D412525.

November 27, 2013.

2. EFED Registration Review Problem Formulation for Dimethyl Disulfide. Gabe Rothman, 

Joe Decant. D412524. December 3, 2013.

3. Dimethyl Disulfide (DMDS): Tier 1 Review of Human Incidents. Elizabeth Evans, Shanna 

Recore. D413869. August 20, 2013.

4. BEAD Chemical Profile (BCP) for Registration Review of Dimethyl Disulfide (029088). 

Leonard Yourman, Jihad Alsadek, Derek Berwald. June 24, 2013.

5. EFED Label Data Report: Dimethyl Disulfide (029088). April 19, 2013
3

6. HED Master Label Data Report: Dimethyl Disulfide (029088). April 19, 2013

These and other supporting documents for the DMDS registration review case may be found in

the docket EPA-HQ-OPP-2013-0488 at http://www.regulations.gov.
4

OVERVIEW

The docket for DMDS is now open, initiating the first public comment period for this registration 

review (docket number 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. This Preliminary Work Plan 

(PWP) document explains what EPA's Office of Pesticide Programs knows about DMDS, 

highlighting anticipated data and assessment needs, identifying the types of information that 

would be especially useful to the Agency in conducting the review, and providing an anticipated 

timeline for completing the registration review for DMDS. 

The registration review process was designed to include a public participation component to 

solicit input from interested stakeholders. The Agency intends, by sharing this information in the 

docket, to inform the public of what it knows about DMDS and what types of new data or other 

information would be helpful for the Agency to receive as it moves toward a decision on DMDS. 

The Agency encourages all interested stakeholders to review the PWP and Appendix and to 

provide comments and additional information that will help the Agency’s decision-making 

process for this chemical. In addition to general areas on which persons may wish to comment, 

there are some areas identified in the PWP and Appendix about which the Agency specifically 

seeks comments and information. Interested stakeholders could include: environmental nonprofit or interest groups; pesticide manufacturers; agricultural labor or commodity groups; 

commercial, institutional, residential, and other users of pesticides; or the public at large.

The Preliminary Work Plan begins by listing the anticipated data needs for DMDS. Next, it 

discusses the statutory and regulatory authority for Registration Review. Then the document 

provides chemical facts, use and usage information, recent actions, the anticipated risk 

assessments, and a projected registration review timeline for DMDS. Finally, the Appendix to 

this document includes identification and discussion of some areas that are considered generally 

in Registration Review along with some additional chemical case-specific information.
5

ANTICIPATED DATA NEEDS

Table 1 below summarizes anticipated data needs for DMDS. For additional discussion of the 

anticipated data needs, see the EFED Registration Review Problem Formulation for Dimethyl 

Disulfide and Dimethyl Disulfide Human-Health Assessment Scoping Document in Support of 

Registration Review.

Table 1: Anticipated Data Needs for the DMDS Registration Review

Guideline 

Number1 Study Title1

Test Material

Estimated 

Timeframe

(Months from 

receipt of DCI)

NonGuideline Acute Honey Bee Vapor Exposure TGAI 24

Outstanding Data Requirements from Conditional Registration2

875.1300 Inhalation Exposure, outdoor (broadcast shank 

injection with a high barrier tarp) TEP Due 4/1/2014

875.1300 Inhalation Exposure, outdoor (raised bed shank 

injection with a high barrier tarp) TEP Due 4/1/2014

875.1300 Inhalation Exposure, outdoor (raised bed drip 

irrigation with a high barrier tarp) TEP Due 4/1/2014

835.8100 Field volatility (broadcast shank injection with a 

high barrier tarp) TEP Due 4/1/2014

835.8100 Field volatility (raised bed shank injection with a 

high barrier tarp) TEP Due 4/1/2014

835.8100 Field volatility (raised bed drip irrigation with a 

high barrier tarp) TEP Due 4/1/2014

850.4150 Terrestrial plant toxicity, vegetative vigor tier II TEP Due 5/14/2014

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

 1 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 2 The studies listed in this section were previously required as conditions of registration [July 9, 2010] and are still 

outstanding. These studies will not be included in the anticipated Registration Review DCI because they are 

already required as conditions of registration. http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP2007-0092-0029
6

STATUTORY AND REGULATORY AUTHORITY

The Food Quality Protection Act (FQPA) of 1996 mandated a registration review program. All 

pesticides distributed or sold in the United States (U.S.) generally must be registered by the 

Environmental Protection Agency (EPA or the Agency), based on scientific data showing that 

they will not cause unreasonable risks to human health or the environment when used as directed 

on product labeling. 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 of no unreasonable adverse effects to human health or the 

environment. Changes in science, public policy, and pesticide use practices will occur over time. 

Through the registration review program, the Agency periodically reevaluates pesticides to make 

sure that as change occurs, products in the marketplace can be used safely. Information on this 

program is provided on EPA’s website.

3

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. The regulations governing registration review begin at 40 CFR 155.40. The 

Agency will consider benefits information and data as required by FIFRA. The public phase of 

registration review begins when the initial docket is opened for each case. The docket is the 

Agency’s opportunity to state what it knows about the pesticide and what additional risk analyses 

and data or information it believes are needed to make a registration review decision. After 

reviewing and responding to comments and data received in the docket during this initial 

comment period, the Agency will develop a Final Work Plan (FWP) and anticipated schedule for 

the registration review of DMDS.

CHEMICAL FACTS

Table 2 provides a summary of the chemical facts for DMDS.

Table 2: Chemical Facts for DMDS

PC code 029088

Case Number 7454

CAS Number 624-92-0

Date first registered July 9, 2010

Pesticide Type Soil fumigant 

Chemical class Reduced organosulfur compound

Reregistration Eligibility 

Decision (RED)

Because it was registered after November 1984, DMDS was not 

subject to reregistration.

Tolerance Reassessment 

Eligibility Decision 

(TRED)

Not applicable. DMDS does not require the establishment of food 

tolerances, because the currently registered uses of DMDS as a preplant soil fumigant are considered non-food.

Cumulative group Not applicable. DMDS has not been identified as a member of a 

cumulative group that shares a common mechanism of toxicity.

 3 http://www.epa.gov/oppsrrd1/registration_review/
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Table 2: Chemical Facts for DMDS

40 CFR Citation There are no established tolerances for DMDS. The currently 

registered uses of DMDS as a pre-plant soil fumigant are 

considered non-food and do not require food tolerances.

Dual-use DMDS is registered for conventional pesticidal uses only and has 

no registered antimicrobial or biopesticidal uses.

Non-pesticidal uses DMDS has industrial uses, primarily in the refining and 

petrochemical industries. It is also used to dissolve elemental sulfur 

in order to unplug natural gas wells, as an additive to prevent metal 

dusting during the manufacture of ‘sponge iron,’ and as a 

thiomethylating agent in organic synthesis.

Pesticide Re-evaluation 

Division, Chemical 

Review Manager

Garland Waleko, waleko.garland@epa.gov, 703-308-8049

Registration Division, 

Product Manager

Tony Kish, kish.tony@eps.gov, 703-308-9443

USE AND USAGE INFORMATION

Table 3 summarizes the use and usage information for DMDS. Please see the BEAD Chemical 

Profile (BCP) for Registration Review of Dimethyl Disulfide (029088) in the registration review 

docket for more details.

Table 3: DMDS Use and Usage Information

Summary of Use Dimethyl disulfide (DMDS) is a broad-spectrum pre-plant soil

fumigant 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.

DMDS may be co-applied with either chloropicrin, metam sodium, 

or 1,3-dichloropropene; these combinations are expected to be 

methyl bromide replacement fumigants. 

Use Sites Pre-plant soil fumigant on the following crops: strawberry, tomato, 

pepper, eggplant, cucumber, squash (all varieties), melons (all 

varieties), blueberry, forest nursery crops and field grown 

ornamentals.

Summary of Usage EPA has no usage data for DMDS because it was first registered for 

use in 2010. 

Formulation Type(s) Soluble concentrate, emulsifiable concentrate

Application Method(s) Applied to the soil prior to planting via shank injection (broadcast 

or raised bed) or drip irrigation equipment. Labels require treated 

areas to be covered by high-barrier, virtually impermeable film 

(VIF) tarps to reduce emissions.
8

Table 3: DMDS Use and Usage Information

Technical Registrant(s) Arkema, Inc. 

No. of Registrations 4 Section 3 products4. No Section 24c or Section 18 registrations.

Restricted Use Yes

Guidance for Commenters: Additional areas of use and usage related information

requested for this registration review, and of particular interest to EPA, are described below.

• Confirmation of the following label information: sites of application; formulations;

application methods and equipment; maximum application rates; frequency of 

application, and geographic limitations on use.

• Use distribution (e.g., acreage and geographical distribution of relevant use sites).

• Median and 90th percentile reported use rates (lbs ai/A) from usage data – national, state, 

and county.

• Typical application timing – national, state, and county.

• State or local use restrictions.

• Foreign technical registrants not listed above who supply technical DMDS to the US 

market.

RECENT ACTIONS

DMDS was first registered for its current uses on July 9, 2010. There are no other recent actions 

for DMDS. 

Most registration review dockets for active ingredients considered to be fumigant pesticides 

opened in September 2013; although the DMDS docket is opening in December 2013 it is still 

part of this group.

ANTICIPATED RISK ASSESSMENTS FOR REGISTRATION REVIEW

The most recent comprehensive human health risk assessment for DMDS was completed in

April 2010 when DMDS was initially registered with EPA. The most recent ecological and 

environmental fate risk assessment was also completed April 2010 for the same purpose. 

Findings and conclusions from these risk assessments are summarized in the EFED Registration 

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

Assessment Scoping Document in Support of Registration Review.

During registration review, the Agency anticipates the need to conduct a comprehensive

ecological risk assessment, including an endangered species assessment, for all uses of DMDS.

For human health, EPA anticipates the need to 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 anticipated to be submitted during registration 

review (already required though conditional registration), they will be considered in the new 

 4 Section 3 product labels can be obtained from the Pesticide Product Label System (PPLS) website 

(http://oaspub.epa.gov/pestlabl/ppls.home).
9

assessments, as well as any changes to the standard operating procedures or default exposure 

assumptions.

Table 4 below summarizes the anticipated registration review risk assessments based on the 

EFED Problem Formulation and HED Scoping Document.

Table 4: Anticipated 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.

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.
10

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 5 below.

Table 5: Projected DMDS Registration Review Timeline

Activities Estimated Date

Opening the Docket

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

Close Public Comment 2014 – February

Case Development

Final Work Plan 2014 – May 

Issue DCI 2014 – July-September

Data Submission 2016 – July-September 

60-day Public Comment Period for Draft Risk 

Assessments5

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

After the 60-day public comment period closes, the Agency will review and respond to any 

comments received in a timely manner and then issue a Final Work Plan for the registration 

review of DMDS.

 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.
11

Appendix – Additional Areas Considered in the DMDS Registration Review

PUBLIC COMMENTS AND FEEDBACK:

Guidance for Commenters: The areas below highlight topics of special interest to the Agency 

where your comments, data submissions, or reference to sources of additional information could 

be of particular use.

Trade Irritants:

Through the registration review process, the Agency intends to solicit information on trade 

irritants and, to the extent feasible, take steps toward facilitating irritant resolution. The Agency 

will work to harmonize tolerances and international maximum residue limits (MRLs) and may 

modify tolerance levels to do so, when possible. Growers and other stakeholders are asked to 

comment on any trade irritant issues resulting from lack of MRLs or disparities between U.S. 

tolerances and MRLs in key export markets, providing as much specificity as possible regarding 

the nature of the concern. Because DMDS is not registered for food/feed uses in the U.S., it has 

no U.S. tolerances; therefore, the Agency does not anticipate any trade irritant issues for it.

Water Quality:

DMDS is not identified as a cause of impairment for any water bodies listed as impaired under 

section 303(d) of the Clean Water Act.

6

 In addition, no Total Maximum Daily Loads (TMDL) 

have been developed for DMDS.

7

 More information on impaired water bodies and TMDLs can 

be found at the Agency’s website.

8 The Agency invites submission of water quality data for 

this pesticide. To the extent possible, data should conform to the quality standards in Appendix 

A of the OPP Standard Operating Procedure: Inclusion of Impaired Water Body and Other

Water Quality Data in OPP’s Registration Review Risk Assessment and Management Process9

in order to ensure they can be used quantitatively or qualitatively in pesticide risk assessments.

Environmental Justice:

EPA seeks to achieve environmental justice, the fair treatment and meaningful involvement of all 

people, regardless of race, color, national origin, or income, in the development, implementation, 

and enforcement of environmental laws, regulations, and policies. To help address potential 

environmental justice issues, the Agency seeks information on any groups or segments of the 

population who, as a result of their location, cultural practices, or other factors, may have 

atypical, unusually high exposure to DMDS compared to the general population. Please 

comment if you are aware of any sub-populations that may have atypical, unusually high 

exposure compared to the general population.

 6 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885

7

http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant_

group_name=PESTICIDES 8 http://www.epa.gov/owow/tmdl/

9 http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm
12

ENDANGERED SPECIES:

A risk assessment that supports a complete endangered species determination has not been 

conducted for DMDS. The ecological risk assessment planned during registration review will 

allow the Agency to determine whether use of DMDS has “no effect” or “may affect” federally 

listed threatened or endangered species (listed species) or their designated critical habitats. 

When an assessment concludes that a pesticide’s use “may affect” a listed species or its 

designated critical habitat, the Agency will consult with the U.S. Fish and Wildlife Service 

and/or National Marine Fisheries Service (the Services), as appropriate.

ENDOCRINE DISRUPTOR SCREENING PROGRAM:

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of its recent registration decision for DMDS, EPA reviewed these 

data and selected the most sensitive endpoints for relevant risk assessment scenarios from the 

existing hazard database. However, as required by FFDCA section 408(p), DMDS is subject to 

the endocrine screening part of the Endocrine Disruptor Screening Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 

may designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine-related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between 

October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 

chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. A second list 

of chemicals identified for EDSP screening was published on June 14, 201310 and includes some 

pesticides scheduled for registration review and chemicals found in water. Neither of these lists 

should be construed as a list of known or likely endocrine disruptors. 

 10 See http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list of 

chemicals.
13

For further information on the status of the EDSP, the policies and procedures, the lists of 

chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our 

website. 11

HUMAN STUDIES:

Occupational

Past DMDS risk assessments rely in part on data from studies in which adult human subjects 

were intentionally exposed to a pesticide to determine their dermal and inhalation exposure. 

Many such studies, involving exposure to many different pesticides, comprise generic pesticide 

exposure databases such as the Pesticide Handlers Exposure Database (PHED) and the 

Agricultural Reentry Task Force (ARTF) Database. EPA has reviewed all the studies supporting 

these multi-pesticide generic exposure databases, and has found no clear and convincing 

evidence that the conduct of any of them was either fundamentally unethical or significantly 

deficient relative to the ethical standards prevailing at the time the research was conducted. All 

applicable requirements of EPA’s Rule for the Protection of Human Subjects of Research (40 

CFR Part 26) have been satisfied, and there is no regulatory barrier to continued reliance on 

these studies.

 11 http://www.epa.gov/endo/