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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 dazomet. This work plan addresses public comments received 

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

review docket (EPA-HQ-OPP-2013-0080). Dazomet is a non-selective soil fumigant with 

fungicidal, herbicidal, and nematicidal properties registered for use as a pre-plant soil fumigant for 

strawberries and tomatoes in California only, and nationally for non-bearing crops and golf course 

turf. Dazomet is also an active ingredient in a variety of antimicrobial products. After application 

dazomet breaks down quickly to the primary toxic degradate, methyl isothiocyanate (MITC) gas. 

MITC is also a registered pesticide, is highly volatile, and is responsible for the biocidal properties of 

this fumigant. The MITC case is addressed in a separate Preliminary Work Plan, located in the MITC 

docket (EPA-HQ-OPP-2013-0242).

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

UPDATES SINCE THE PWP WAS ISSUED

The Agency identified existing adsorption/desorption and leaching studies (835.1230 and 

835.1240), so these studies will not be required in registration review. The seedling emergence 

study on MITC (850.4100) was incorrectly captured as “in review” in the PWP, but should have been 

listed as a new registration review requirement. The activated sludge respiration inhibition (ASRI)

study (850.3300) was identified as a data need in the ecological problem formulation but was not 

captured in the data needs table in the dazomet PWP. The planned data needs in table 1 have 

been updated accordingly. 

There are no additional updates on dazomet since the PWP.

 1 http://www.epa.gov/oppsrrd1/registration_review/
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SUMMARY OF COMMENTS AND AGENCY RESPONSES

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

opened on September 25, 2013 and closed on November 25, 2013 the Agency received eight 

unique public comments. One of those comments includes a mass comment campaign from the 

Pesticide Action Network of North America (PANNA) which received 5,645 signatures, and 

requests the Agency re-evaluate risk assessment levels of concern and buffer zone distances

imposed by the 2008 reregistration eligibility decision. Comments were also submitted by the 

registrant, agricultural associations, non-profit organizations, and one state agriculture 

department. The comments address the registration review process and utility of soil fumigants 

in agriculture. The Agency considered the issues and concerns raised by each of the eight unique 

comments submitted, but the registration review timeline, data-requirements, and anticipated risk 

assessment needs did not change as a result of these comments. 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. Public comments in 

their entirety are located in dazomet docket, EPA-HQ-OPP-2013-0080. EPA’s responses to 

those public comments are in Responses to Public Comments on the Dazomet Preliminary Work 

Plan, which is also located in the dazomet docket.

PLANNED DATA NEEDS

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

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

in Support of the Registration Review of Dazomet and Dazomet Human-Health Assessment 

Scoping Document in Support of Registration Review, and Public Comments on the Dazomet 

Preliminary Work Plan. With the exception of removing the adsorption/desorption studies 

(835.1230 and 835.1240), the planned data needs have not changed from what was included in 

the PWP.

Table 1: Planned Data Needs for the Dazomet Registration Review

Guideline 

Number2 Study Title2

Test Material

Estimated 

Timeframe

(Months from 

receipt of DCI)

Anticipated Data Needs for the Parent Dazomet (for conventional uses of dazomet)

850.2100 Avian oral toxicity (passerine) TGAI 12

Anticipated Data Needs for the Parent Dazomet (for antimicrobial uses only)

875.1700 Product use information TEP 12

 2 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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Table 1: Planned Data Needs for the Dazomet Registration Review

Guideline 

Number2 Study Title2

Test Material

Estimated 

Timeframe

(Months from 

receipt of DCI)

875.1200

Dermal exposure for open pour 

mixing/loading paint (occupational) and 

applying paint (airless sprayer and 

brush/roller; occupational and residential)

TEP 24

875.2400 Post-application dazomet dermal exposure for 

finger painting TEP 24

Anticipated Data Needs for the Degradate MITC (for conventional uses of dazomet)

850.6100

Environmental chemistry methods and associated 

independent laboratory validations for air, soil, and 

water

MITC 12

850.4100 Seedling emergence (Tier II) MITC 12

835.4300 Aerobic aquatic metabolism MITC 24

NonguidelineHoneybee vapor exposure MITC 24

850.1400 Freshwater fish 

early-life stage MITC 12

Anticipated Data Needs for the Degradate MITC (for antimicrobial uses of dazomet only)

875.1400 Inhalation exposure for open pour 

mixing/loading paint (occupational) and 

applying paint (airless sprayer and 

brush/roller; occupational and residential)

MITC 24

875.2400 Post-application dermal exposure (for painted 

rooms) MITC 24

850.33003 Activated Sludge Respiration Inhibition (ASRI) MITC 12

 3 EPA has a published final guidance for this study: http://www.regulations.gov/#!documentDetail;D=EPA-HQOPPT-2009-0154-0021. OECD Test Guideline 209 can also be used as guidance for this study, available online at 

http://www.oecd-ilibrary.org/content/book/9789264070080-en. The results of the Activated Sludge Respiration 

Inhibition Test (ASRI) expected to be required will determine which of these four biodegradation tests would be 

anticipated to be required. If the ASRI test EC50 is less than or equal to 20 mg/L, then either the (i) Biodegradation 

in Activated Sludge Study or (ii) Simulation Test – Aerobic Sewage Treatment: A. Activated Sludge Units or (iii) 

the Porous Pot Test would be anticipated to be required. If the ASRI test EC50 is greater than 20 mg/L, then the 

DCI expected to be issued would provide that the registrant would choose to conduct either: (i) Ready 

Biodegradability or (ii) a) Biodegradation in Activated Sludge or b) Simulation Test – Aerobic Sewage Treatment: 

A. Activated Sludge Units or c) the Porous Pot Test. If the Ready Biodegradability study is conducted and passes, 

then no further testing would be expected to be required. If, however, the antimicrobial fails the Ready 

Biodegradability study, then the a) Biodegradation in Activated Sludge or b) Simulation Test – Aerobic Sewage 

Treatment: A. Activated Sludge Units, or c) the Porous Pot study would be expected to be required.
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Table 1: Planned Data Needs for the Dazomet Registration Review

Guideline 

Number2 Study Title2

Test Material

Estimated 

Timeframe

(Months from 

receipt of DCI)

835.31104 Ready Biodegradability MITC 12

835.32205 Porous Pot Test MITC 12

835.32806 Simulation Tests to Assess the 

Biodegradability of Chemicals Discharged in 

Wastewater

MITC 12

835.32407 Simulation Test – Aerobic Sewage Treatment: 

A. Activated Sludge Units MITC 12

Outstanding Data Requirements from GDCI-035602-288508 (2010 Soil Fumigant Dazomet DCI)

835.8100 Field volatility from soil TEP In review

850.1025 Oyster acute toxicity (shell deposition) MITC In review

850.1035 Mysid acute toxicity MITC In review

850.1075 Fish acute toxicity, freshwater and marine MITC In review

850.2300 Avian reproduction test TGAI In review

850.3020 Honey bee acute toxicity MITC Due April 2014

850.4150 Vegetative vigor (Tier II) MITC In review

850.4400 Aquatic plant growth toxicity (Tier II) MITC In review

870.4200 Carcinogenicity MITC Due April 2014

 4 EPA has a published final guideline for this study: http://www.regulations.gov/#!documentDetail;D=EPA-HQOPPT-2009-0152-0017. The biodegradation study anticipated to be required is based on results of an Activated 

Sludge Respiration Inhibition test. 5 EPA has a published final guideline for this study: http://www.regulations.gov/#!documentDetail;D=EPA-HQOPPT-2009-0152-0024. The biodegradation study anticipated to be required is based on results of an Activated 

Sludge Respiration Inhibition test. 6 EPA has a published final guideline for this study: http://www.regulations.gov/#!documentDetail;D=EPA-HQOPPT-2009-0152-0036. The biodegradation study anticipated to be required is based on results of an Activated 

Sludge Respiration Inhibition test. 7 EPA has a published final guideline for this study: http://www.regulations.gov/#!documentDetail;D=EPA-HQOPPT-2009-0152-0034. The biodegradation study anticipated to be required is based on results of an Activated 

Sludge Respiration Inhibition test. 8 The studies listed in this section were previously required through a generic data call-in issued in March 2010 and 

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

are already required through the earlier DCI.
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Table 1: Planned Data Needs for the Dazomet Registration Review

Guideline 

Number2 Study Title2

Test Material

Estimated 

Timeframe

(Months from 

receipt of DCI)

870.3700 Prenatal developmental toxicity study MITC In review

870.3800 Reproduction and fertility effects MITC Due April 2014

870.6200 Neurotoxicity screening battery MITC In review

Nonguideline 

(numbered 

as SS-2 on 

the 

dazomet 

DCI)

Avian acute inhalation

MITC In review

Outstanding Data Requirements from GDCI-035602-290249(2010 Antimicrobial Dazomet DCI10)

875.1200 Dermal Exposure - Indoor TEP In review

875.1400 Inhalation Exposure - Indoor MITC Extension 

requested*

875.1600 Application exposure monitoring data reporting TEP Extension 

requested*

875.1700 Product Use Information TEP Extension 

requested*

875.2500 Inhalation Exposure MITC In review

875.2700 Product Use Information TEP Extension 

requested*

875.2800 Description of human activity TEP Extension 

requested*

875.2900 Data reporting and calculations TEP Extension 

requested*

850.1025 Oyster acute toxicity (shell deposition) MITC In review

850.1035 Mysid acute toxicity MITC In review

 9 The studies listed in this section were previously required through a generic data call-in issued in March 2010 and 

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

are already required through the earlier DCI.

10 The exposure and air concentration monitoring data required by the 2010 antimicrobial dazomet DCI is to support 

the following dazomet uses identified by the 2009 Amended Dazomet RED. These uses include: 1) a treatment 

during the production of pulp and paper; 2) a materials preservative treatment for paper coatings, non-food 

adhesives, epoxy flooring compounds, slurries, and high viscous suspensions; 3) a biocide treatment during 

petroleum operations; 4) a biocide treatment in recirculating cooling water systems; and 5) a remedial wood 

treatment to utility poles. 
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Table 1: Planned Data Needs for the Dazomet Registration Review

Guideline 

Number2 Study Title2

Test Material

Estimated 

Timeframe

(Months from 

receipt of DCI)

850.1075 Fish acute toxicity, freshwater and marine MITC In review

860.1520 Processed Food/Feed (paper manufacturing 

processes

TEP In review

870.3700 Prenatal developmental toxicity study MITC In review

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

* After the PWP was issued, antimicrobial dazomet registrants submitted an updated extension request, which is 

currently under review.

RISK ASSESSMENTS FOR 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 dazomet. 

For human health, EPA anticipates the need to conduct revised occupational and bystander risk 

assessments during registration review for conventional uses, and occupational and residential 

assessments for antimicrobial uses 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 and the planned assessments have not 

changed from what was included in the PWP.

Table 2: Anticipated Risk Assessments for the Dazomet 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 Since dazomet rapidly hydrolyzes to MITC, potential 

exposure to aquatic receptors is primarily to MITC

via surface runoff; consequently, the toxicity data for 

MITC will be used to assess risk to fish, aquatic 

invertebrates, and aquatic plants. Terrestrial exposure 

to birds, mammals, invertebrates can occur through 

consumption of dazomet granules and/or by

inhalation of MITC. 

Incidents Will check for 

updates

For a discussion of reported ecological incidents for 

dazomet, see page 16 of the Problem Formulation.

Human Health
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Dietary

Food N The uses of dazomet on strawberries and tomatoes 

(California only) are considered non-food uses, since 

there is no reasonable expectation of finite residues 

in/on food crops when dazomet is used as a pre-plant 

fumigant for the labeled use sites. An assessment is 

not anticipated in registration review.

Drinking water N Based on environmental fate data, the residual 

contents in soils, and monitoring data, the Agency 

does not expect MITC to adversely impact the 

drinking water sources such as surface water and 

ground water, so an assessment is not anticipated in 

registration review.

Occupational

Handlers (mixers, loaders, 

applicators)

Y For soil fumigant and antimicrobial uses, updates to 

handler risk assessments are anticipated.

Post-application Y An updated occupational post-application risk 

assessment for some antimicrobial uses is anticipated. 

N Based on re-entry restrictions specified by the 2009 

amended RED for the conventional uses of dazomet, 

the Agency does not expect risk to re-entry workers to 

exceed the Agency’s level of concern. 

Residential

Handlers Y For antimicrobial uses only, additional residential

handler dermal and inhalation exposure data are 

required and will be reviewed and incorporated in the 

risk assessment in registration review.

Post-application Y For antimicrobial uses only, additional postapplication dermal exposure data are required and 

will be reviewed and incorporated in the risk 

assessment in registration review.
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Bystander Y For soil uses, there is the potential for residential 

bystander (anyone not involved in the application) 

inhalation exposure to MITC after a soil fumigation 

application of dazomet. A revised residential risk 

assessment is anticipated in registration review to 

update risk to bystanders during and following soil 

fumigant uses of dazomet products. 

Additionally, the Agency anticipates updating the 

fumigant factors document, which provides a 

discussion of values and parameters used as the basis 

for buffer zone reduction credits as well as for 

establishing Good Agricultural Practices (GAPs) for 

the fumigants. Buffer zones and GAPs were specified 

by the 2009 amended RED as measures to mitigate 

occupational and bystander risk.

Other

Aggregate N Evaluates the combined risk from dietary and 

residential exposures. No dietary risk is anticipated 

from dazomet. Therefore, an aggregate assessment is 

not anticipated.

Cumulative N Dazomet is not a member of a cumulative group, so 

no cumulative risk assessment is planned

Tolerances N Currently labeled dazomet use as a pre-plant soil 

fumigant is considered non-food, so there are no 

tolerances established for this chemical.

Incidents Will check for 

updates

For a discussion of reported human incidents for 

dazomet, see page 8 of the Scoping Document and 

Dazomet: Review of Human Incidents.

TIMELINE

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

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

lengthening of the timeframe between posting of the draft risk assessment and the proposed 

decision by one quarter.

Table 3: Projected Dazomet Registration Review Timeline

Activities Estimated Date

Opening the Docket

Open Docket and 60-day Public Comment Period September 2013 - Completed

Close Public Comment November 2013 - Completed

Case Development

Final Work Plan February 2014 - Completed
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Table 3: Projected Dazomet Registration Review Timeline

Activities Estimated Date

Issue DCI 2014 April - June

Data Submission 2016 April - June

60-day Public Comment Period for Draft Risk 

Assessments11

2017 Oct. – Dec.

Registration Review Decision

60-day Public Comment Period for Proposed 

Registration Review Decision

2018 –July-Sept.

Registration Review Decision and Begin Post-Decision 

Follow-up

2019

Total (years) 6

NEXT STEPS

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

and human health studies for dazomet through a Data Call-In Notice, expected to be issued by

June 2014. 

 11 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.