2

Preliminary Work Plan – Table of Contents

Overview 4

Anticipated Data Needs 5

Statutory and Regulatory Authority 7

Chemical Facts 7

Use and Usage Information 8

Recent Actions 12

Anticipated Risk Assessments for Registration Review 12

Timeline 15

Next Steps 16

Appendix – Additional Areas Considered in the

Registration Review of Metam and MITC 17

References:

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

based on the following documents:

1. EFED and AD Registration Review Problem Formulation for Metam Sodium, Metam 

Potassium, and MITC. September 19, 2013

2. Metam Sodium, Metam Potassium, and MITC. Human Health Assessment Scoping 

Document in Support of Registration Review. September 4, 2013

3. Metam Sodium, Metam Potassium, MITC: Review of Human Incidents. August 29, 2013

4. BEAD Chemical Profile (BCP) for Registration Review: Methyldithiocarbamate

Salts Chemical Case [Includes Metam-sodium (039003) and Metam-potassium (039002)]. 

July 15, 2013

5. BEAD Chemical Profile (BCP) for Registration Review: Methyl Isothiocyanate 

(MITC)(068103). February 19, 2013

6. Metam Sodium (039003) Screening Level Usage Analysis (SLUA). April 30, 2012
3

7. Metam Potassium (039002) Screening Level Usage Analysis (SLUA). April 30, 2012

8. PRD Label Data Report: Food/Feed & Non-Food/Non-Feed Uses Considered in 

Registration Review Work Planning. Metam Sodium (039003). December 21, 2012

9. PRD Label Data Report: Food/Feed & Non-Food/Non-Feed Uses Considered in 

Registration Review Work Planning. Metam Potassium (039002). March 07, 2013

10. Amended Reregistration Eligibility Decision (RED) for the Methyldithiocarbamate Salts 

(Metam sodium, Metam potassium) and Methyl Isothiocyanate (MITC). May 2009.

These and other supporting documents for these registration review cases may be found in the

methyldithiocarbamate salts docket EPA-HQ-OPP-2013-0140 and the methyl isothiocyanate

docket EPA-HQ-OPP-2013-0242 at http://www.regulations.gov.
4

OVERVIEW

The dockets for the methyldithiocarbamate salts (metam sodium, metam potassium) (docket 

numbers EPA-HQ-OPP-2013-0140) and methyl isothiocyanate (MITC) (docket number EPAHQ-OPP-2013-0242) are now open, initiating the first public comment period for these

registration reviews. These cases include the following active ingredients: metam sodium, metam 

potassium, MITC. Metam sodium and metam potassium (hereafter referred collectively as 

“metam”) are non-selective fumigant biocides registered for use as pre-plant soil fumigants for

use on a variety of food, feed, fiber crops, forest trees, ornamentals and turf, including golf 

courses, to kill soil dwelling pests (fungi, weeds, insects, and nematodes). There are several nonagricultural registered uses of metam, including antimicrobial uses and sewer root control use. 

After application metam-sodium and metam-potassium break down quickly to the primary toxic

degradate, MITC gas. MITC is highly volatile and is responsible for biocidal properties of these 

fumigants. In addition to being a degradate of metam, MITC is also registered as an 

antimicrobial active ingredient for use in a variety of products. There are no registered residential 

uses of metam or MITC products. MITC is also the primary degradate of the fumigant active 

ingredient dazomet, which is addressed as a separate registration review case.

This Preliminary Work Plan (PWP) document explains what EPA's Office of Pesticide Programs

knows about metam and MITC, 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 metam and 

MITC.

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 metam and MITC and what types of new 

data or other information would be helpful for the Agency to receive as it moves toward a 

decision on metam and MITC. 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 non-profit 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 metam and MITC. 

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 metam and MITC. 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.

ANTICIPATED DATA NEEDS
5

Table 1 below summarizes anticipated data needs for metam and MITC. For additional 

discussion of the anticipated data needs, see the EFED and AD Registration Review Problem 

Formulation for Metam Sodium, Metam Potassium, and MITC, September 19, 2013, and Metam 

Sodium, Metam Potassium, and MITC. Human Health Assessment Scoping Document in Support 

of Registration Review, September 4, 2013.

Table 1: Anticipated Data Needs for the Metam and MITC Registration Review

Guideline 

Number Study Title Test Material

Estimated 

Timeframe

(Months from 

receipt of DCI)

Anticipated Data Needs for All Uses of Metam and MITC

835.4300 Aerobic aquatic metabolism MITC 24

850.4100 Terrestrial plant toxicity, seedling emergence MITC 12

850.6100

Environmental chemistry methods and associated 

independent laboratory validations for air and 

water

MITC 12

Nonguideline Acute vapor exposure honey bee study MITC 12

Anticipated Data Needs for Soil Fumigant Uses of Metam

835.8100 Field volatility – shank bedded application Metam TEP 12

Outstanding Data Requirements from Post-RED DCIs for All Uses1

870.3800 Reproduction and fertility effects MITC Due April 2014

870.4200 Carcinogenicity MITC Due April 2014

835.8100 Field volatility from soil – center pivot application

Metam – TEP 

(metam soil fumigant 

product)

Under review

850.1025 Oyster acute toxicity test (shell deposition) MITC Under review

850.1035 Mysid acute toxicity test MITC Under review

850.1075 Fish acute toxicity test, freshwater and marine MITC Under review

850.3020 Honey bee acute contact toxicity MITC Under review

850.4150 Vegetative vigor (Tier II) MITC Under review

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

870.3700 Prenatal developmental toxicity study MITC Under review

870.6200 Neurotoxicity screening battery MITC Under review

Outstanding Data Requirements from Post-RED DCIs for Sewer Uses Only2

 1 The studies listed in this section were previously required through generic metam sodium (metam-Na) and metam 

potassium (metam-K) data call-ins (DCI) issued in March 2010 and are still outstanding. The DCI numbers are as 

follows: Soil Fumigant Registrants (Metam-Na: GDCI-039003-28196, Metam-K: GDCI-039002-28888); 

Antimicrobial Registrants (Metam-Na: GDCI-039003-29028, Metam-K: GDCI-039002-29030); Sewer Use 

Registrants (Metam-Na: GDCI-039003-29029); MITC registrants (GDCI-068103-29026). These studies will not

be included in the anticipated Registration Review DCI because they are already required through the earlier 

DCIs.
6

Table 1: Anticipated Data Needs for the Metam and MITC Registration Review

Guideline 

Number Study Title Test Material

Estimated 

Timeframe

(Months from 

receipt of DCI)

875.1300 Inhalation exposure--outdoor

Metam – TEP 

(metam sewer root 

control use product)

Under review

875.1700 Product use information

Metam– TEP 

(metam sewer root 

control use product)

Under review

Outstanding Data Requirements from Post-RED DCIs for Soil Fumigant Uses Only3

NonguidelineAmbient air monitoring program Metam – TEP Due March 

2014

Outstanding Data Requirements from Post-RED DCIs for Antimicrobial Uses Only4

875.1200 Dermal exposure--indoor TEP Extension 

requested*

875.1400 Inhalation exposure--indoor TEP Extension 

requested*

875.1600 Application exposure monitoring data reporting TEP Extension 

requested*

875.1700 Product use information TEP Extension 

requested*

875.2500 Inhalation exposure TEP Extension 

requested*

875.2700 Product use information – post-application TEP Extension 

requested*

875.2800 Description of human activity TEP Extension 

requested*

875.2900 Data reporting and calculations TEP Extension 

requested*

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

* The recently submitted extension request will be reviewed prior to issuing the Final Work Plan.

 2 The studies listed in this section were previously required through a generic metam sodium (metam-Na) data callin (DCI) issued in March 2010 and are still outstanding. The DCI number is as follows: Metam-Na: GDCI-039003-

29029. These studies will not be included in the anticipated Registration Review DCI because they are already 

required through the earlier DCIs. 3 The studies listed in this section were previously required through generic metam sodium (metam-Na) and metam 

potassium (metam-K) data call-ins (DCI) issued in March 2011 and are still outstanding. The DCI numbers are as 

follows: Metam-Na: GDCI-039003-840, Metam-K: GDCI-039002-839. These studies will not be included in the 

anticipated Registration Review DCI because they are already required through the earlier DCIs. 4 The studies listed in this section were previously required through generic metam sodium (metam-Na) and metam 

potassium (metam-K) data call-ins (DCI) issued in March 2010 and are still outstanding. The DCI numbers are as 

follows: Metam-Na: GDCI-039003-29028, Metam-K: GDCI-039002-29030. These studies will not be included in 

the anticipated Registration Review DCI because they are already required through the earlier DCIs.
7

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.

5

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 metam and MITC.

CHEMICAL FACTS

Table 2 provides a summary of the chemical facts for metam and MITC.

Table 2: Chemical Facts for Metam and MITC

Metam Sodium Metam Potassium MITC

PC code 039003 039002 068013

Case Number 2390 2390 2405

CAS Number 137-42-8 137-41-7 556-61-6

Year first registered 1975 1973 1984

Pesticide Type Antimicrobial, fungicide, herbicide, insecticide,

nematicide

Chemical class Fumigant

Reregistration Eligibility 

Decision (RED)

2008 – RED

2009 – Amended RED

 5 http://www.epa.gov/oppsrrd1/registration_review/
8

Table 2: Chemical Facts for Metam and MITC

Tolerance Reassessment 

Eligibility Decision 

(TRED)

Not applicable

Cumulative group Not applicable

40 CFR Citation There are no established tolerances for metam or MITC. All 

registered food/feed uses are considered non-food uses.

6

Dual-use Yes. Metam is registered for conventional and antimicrobial 

pesticidal uses. MITC is registered for antimicrobial uses only.

Non-pesticidal uses There are no identified non-pesticidal uses of metam or MITC.

Pesticide Re-evaluation 

Division, Chemical 

Review Manager

Jose Gayoso

gayoso.jose@epa.gov

(703) 347-8652

Antimicrobial Division, 

Chemical Review 

Manager

Wanda Henson

henson.wanda@epa.gov

(703)-308-6345

Registration Division, 

Product Manager

Shaja Joyner

joyner.shaja@epa.gov

(703) 308-3194

USE AND USAGE INFORMATION

Table 3 and 4 summarize the use and usage information for metam and MITC. Please see the 

BEAD Chemical Profile (BCP) for Registration Review: Methyldithiocarbamate Salts Chemical 

Case Includes Metam-sodium (039003) and Metam-potassium (039002)]. July 15, 2013 and the

BEAD Chemical Profile (BCP) for Registration Review: Methyl Isothiocyanate (MITC)(068103). 

February 19, 2013, in the registration review docket for more details on use and usage, as well as 

a summary of past alternatives and benefits assessments on metam soil fumigant uses.

Table 3: Metam Sodium and Metam Potassium Product Use and Usage Information

Summary of Use and Sites Metam sodium and metam potassium are broad spectrum nonselective fumigants with fungicidal, herbicidal, insecticidal and 

nematicidal properties.

Conventional Uses

Metam sodium and metam potassium are registered for pre-plant 

soil fumigant use for: (1) many food, feed, and fiber crops, (2) 

forest trees, (3) ornamentals, and (4) golf course turf.

Metam soil fumigant uses are meant to sterilize the soil prior to 

 6 Metam’s volatility in the environment and results of metabolism studies in plants assure that there is no reasonable 

expectation of finite residues to be incurred in/on any raw agricultural commodity when these products are applied 

according to label directions. Therefore, this fumigant does not require food tolerances and is not subject to the 

amendments to the FFDCA promulgated under the Food Quality Protection Act of 1996. – Metam Sodium: Phase 5 

Revised Chapter of the Reregistration Eligibility Decision Document (RED). Smith, C. April 12, 2007.
9

Table 3: Metam Sodium and Metam Potassium Product Use and Usage Information

planting a desired crop. 

Metam sodium is also registered for use as a root control agent for 

use in sewers and drains.

Antimicrobial Uses

Metam-sodium is currently registered as an antimicrobial agent for: 

(1) wood poles/timbers, (2) leather processing (e.g., brine-cured 

hides and skins), (3) sewage sludge/animal wastes.

Metam-potassium is registered as an antimicrobial agent for: (1) 

pulp and paper production, (2) leather processing, (3) raw cane and 

beet sugar processing facilities, (4) coatings protective colloids, 

emulsion resins, and water-thinned paints, (5) metal working 

cutting fluids and oils, (6) petroleum operations, (7) water cooling 

tower systems, and (8) industrial water purification systems.

Some antimicrobial uses of metam were voluntarily canceled, 

effective February 17, 2009 (Federal Register Notice 73FR49196, 

August 20, 2008). However, some canceled uses are still in the 

process of being removed from product labels.7

Therefore, the remaining metam sodium uses that will be assessed 

during registration review are (1) wood poles/timbers, and (2) 

sewage sludge/animal wastes.

The remaining metam potassium uses that will be assessed during 

registration review are (1) pulp and paper production, (2) tanning 

drum leather processing, (3) recirculating water cooling tower 

systems, and (4) industrial water purification systems.

Summary of Usage Agricultural Usage

Based on usage data from 2006-2011, metam-sodium's annual 

agricultural usage averaged 42 million pounds of active ingredient 

(A. I.), treating an average of approximately 307 thousand acres, for 

an average application rate of 136 pounds active ingredient per 

acre. For the same time period, potatoes (57%) and carrots (17%) 

accounted for the largest percentages of usage in terms of total 

pounds of A. I. applied. Potatoes (55%) and carrots (14%) 

 7 The following metam sodium use has been canceled and will be removed from existing product label(s) during 

registration review: (1) leather processing (e.g., brine-cured hides and skins).

The following metam potassium uses have been canceled and will be removed from existing product label(s): (1) 

leather processing (except for tanning drum leather), (2) raw cane and beet sugar processing facilities, (3) coatings 

protective colloids, emulsion resins, and water-thinned paints, (4) metal working cutting fluids and oils, (5) 

petroleum operations, (6) once-through water cooling systems, and (7) industrial water purification systems.
10

Table 3: Metam Sodium and Metam Potassium Product Use and Usage Information

accounted for the largest percentages of total area treated (TAT).

For the same time period, metam-potassium's annual agricultural 

usage averaged 12 million pounds of active ingredient, treating an 

average of approximately 77 thousand acres, for an average 

application rate of 150 pounds per acre. Potatoes (56%) and 

tomatoes (14%) accounted for the largest percentages of usage in 

terms of total pounds of A. I. applied. Potatoes (51%) and tomatoes 

(16%) accounted for the largest percentages of total area treated.

Usage data is not available since label directions were changed as 

specified in the 2009 amended RED (e.g., buffer zones, restricted 

use classification, etc.).

Non-Agricultural Usage

Non-agricultural usage data for metam sodium and metam

potassium are not available.

Formulation Type(s) Both metam-sodium and metam-potassium are formulated as 

soluble concentrate, ready-to-use solution, and pressurized gas.

Application Method(s) Soil fumigant Uses

In agricultural settings, metam-sodium and metam-potassium are

applied through chemigation or with tractor-drawn equipment.

Chemigation methods include center pivot, lateral move, solid set 

sprinkler, drip irrigation, flood irrigation, border irrigation, and

furrow irrigation. Tractor-drawn applications are carried out with

various types of shank soil injection, rotary tiller, and spray blade

injection equipment. Applications can either be tarped or untarped.

Sewer Uses

In sewer use applications, metam-sodium is applied using a foam

applicator.

Antimicrobial Uses

The antimicrobial uses of metam sodium and metam potassium 

have a number of application methods, including open pour and 

manual application of pre-filled tubes of solidified-melt product for 

treatment of wood poles and pilings; metering pump for pulp and 

paper, leather, cooling water towers, and industrial water 

purification; and metered injection for animal waste and sewage 

sludge treatment.

Technical Registrant(s) Conventional and Antimicrobial: Amvac Chemical Corporation

Conventional: Taminco, Tessenderlo Kerley

Antimicrobial: Buckman
11

Table 3: Metam Sodium and Metam Potassium Product Use and Usage Information

No. of Registrations Metam Sodium

Section 3 products:8 Conventional – 20

Antimicrobial – 8

Section 24(c) products: 11

Metam Potassium

Section 3 products:

Conventional – 5

Antimicrobial – 7

Section 24(c) products: 2

Restricted Use Yes – Soil fumigant and sewer uses

No – Antimicrobial uses

Table 4: MITC Product Use and Usage Information

Summary of Use and Sites MITC is registered as an antimicrobial agent for wood treatment. 

MITC is registered for use in large structural timbers (such as utility 

poles, pilling, and bridge timber). It is also registered for 

application to areas of timber where decay is suspected.

Summary of Usage Usage data are not available for MITC products.

Formulation Type(s) Ready-to-use solution (impregnated material).

Application Method(s) Manual application of pre-filled tubes of solidified-melt product for 

treatment of wood poles and pilings.

Technical Registrant(s) MLPC International

No. of Registrations Section 3 products: 1

Restricted Use No

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.

• Use/usage information on non-agricultural (turf, sewer, antimicrobial, etc.) use of metamsodium and metam-potasium would improve future assessments of the importance of 

these products.

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

application methods and equipment; maximum application rates; frequency of 

application, application intervals, and maximum number of applications per season; 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 (date of first application and application intervals) – national, 

state, and county.

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

(http://oaspub.epa.gov/pestlabl/ppls.home).
12

• Typical application interval (days).

• State or local use restrictions.

• Foreign technical registrants not listed above who supply technical metam and MITC to 

the US market.

• Impact of post-RED label changes on use/usage of metam products.

In addition, the Agency is interested in continuing the dialogue with stakeholders on label issues 

that have evolved during the RED label implementation process. 

RECENT ACTIONS

Registration Actions

In July and August 2013, three metam soil fumigant products were amended with reduced buffer 

zone distances for shank injection applications to bedded fields. 

In April and May 2013, the Agency received several FIFRA Section 24(c) Special Local Need 

registrations for North Carolina and Virginia for soil fumigant pre-plant application of metam to 

peanut fields. These registrations include buffer zone tables with application rates lower than 

what is available in the Section 3 metam soil fumigant labels.

Reregistration

A Reregistration Eligibility Decision (RED) for metam and MITC was completed in 2008 and 

amended in 2009. As a result of the RED, a variety of risk mitigation measures were required to 

be implemented. For details on the mitigation measures, see the Amended Reregistration 

Eligibility Decision (RED) for the Methyldithiocarbamate Salts (Metam sodium, Metam 

potassium) and Methyl Isothiocyanate (MITC), dated May 2009. Additionally, the Agency’s Soil 

Fumigant Toolbox website contains information on these and other soil fumigants: 

http://www.epa.gov/pesticides/reregistration/soil_fumigants/. More information on the 

reregistration process can be found on the following website: 

http://www.epa.gov/pesticides/reregistration/index.htm.

The product reregistration process, which starts after completion of a RED, is still ongoing for 

metam products.

Additionally, the Agency plans to work with stakeholders to determine if metam soil fumigant 

product labels should be reorganized or revised in order to clarify the Good Agricultural 

Practices and Buffer Zones that correspond to each of the various application methods.

ANTICIPATED RISK ASSESSMENTS FOR REGISTRATION REVIEW

The most recent comprehensive human health risk assessment for metam and MITC was 

completed on August 30, 2009 as a third update on the human health risk assessment that was 

conducted in preparation for the metam and MITC Reregistration Eligibility Decision (RED). 

The first version of the assessment was completed and released for public comment in 2004. 

Subsequent revisions were made to incorporate comments and new data. The most recent 
13

ecological and environmental fate risk assessment on metam and MITC was completed on 

December 29, 2010 to assess risk to the federally threatened California tiger salamander 

(Ambystoma californiense), as part of the stipulated injunction ordered by the Federal District 

Court for the Northern District of California in the case Center for Biological Diversity (CBD) 

vs. EPA et al. (Case No. 07-2794-JCS). The most recent comprehensive ecological and 

environmental fate risk assessment for all uses of metam and MITC was completed in August 

2004 in preparation for the metam and MITC RED. Antimicrobial risk was discussed in a May 

2008 memo. Findings and conclusions from these risk assessments are summarized in EFED and 

AD Registration Review Problem Formulation for Metam Sodium, Metam Potassium, and MITC. 

September 19, 2013 and Metam Sodium, Metam Potassium, and MITC. Human Health 

Assessment Scoping Document in Support of Registration Review. September 4, 2013.

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

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

and MITC. For human health, EPA anticipates the need to conduct revised residential and 

occupational risk assessments during registration review. If toxicological endpoints or points of 

departure are revised based on the data that are anticipated to be 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 5 below summarizes the anticipated registration review risk assessments based on the 

EFED Problem Formulation and HED Scoping Document.

Table 5: Anticipated Risk Assessments for the Registration Review of Metam and MITC

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 MITC will be considered the main stressor in the risk 

assessment. Due to the rapid conversion of metam to 

MITC, it is not expected that metam sodium and 

metam potassium will be bioavailable to terrestrial or 

aquatic organisms in any environmentally relevant 

concentration. 

Incidents Will check for 

updates

For a discussion of reported ecological incidents for 

metam and MITC, see page 28 of the Problem 

Formulation.

Human Health

Dietary

Food N There is no reasonable expectation of finite residues 

to be incurred in/on food and feed crops when metam 

sodium and metam potassium are used as preplant soil 

fumigants, so these uses are considered non-food 

uses, and tolerances are not needed. There is also no 

reasonable expectation of finite residues in/on food 

for the antimicrobial uses of metam sodium/potassium

and MITC.
14

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. However, a confirmatory updated 

drinking water assessment may be conducted in 

registration review.

Occupational

Handlers (mixers, loaders, 

applicators)

Y For soil fumigant, sewer, 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 The Agency does not anticipate conducting postapplication risk assessments for soil fumigant and 

sewer use in registration review.

Residential

Handlers N There are no registered residential uses of 

metam/MITC.

Post-application N There are no registered residential uses of 

metam/MITC.

Bystander Y A revised residential risk assessment is anticipated in 

registration review to update risk to bystanders from 

inhalation exposure to MITC during and following 

soil fumigant uses of metam 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 soil fumigants. Buffer zones and GAPs were 

required 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 metam and MITC uses. Therefore, and 

aggregate assessment is not anticipated.

Cumulative N Metam and MITC are not members of a cumulative 

group, so no cumulative risk assessment is planned.
15

Tolerances N Uses are considered non-food uses, so tolerances are 

not needed.

Incidents Will check for 

updates

For a discussion of reported human incidents for 

metam and MITC, see page 12 of the Scoping 

Document and the Metam Sodium, Metam Potassium, 

MITC: Review of Human Incidents. August 29, 2013.

Guidance for Commenters: Additional ecological information requested for this 

registration review, and of particular interest to EPA, is described below.

• Ecological incidents (non-target plant damage and avian, fish, reptilian, amphibian and 

mammalian mortalities) not already reported to the Agency.

• Water quality monitoring data (see Appendix for further details).

• Wastewater treatment plant monitoring data following upstream uses of metam sodium 

sewer root control applications.

Guidance for Commenters: Additional human health information requested for this 

registration review, and of particular interest to EPA, is described below.

• Occupational or bystander exposure incidents as a result of soil fumigant applications.

• Uses of metam soil fumigant products that are not clearly associated with Good 

Agricultural Practices or Buffer Zones found on product labels.

TIMELINE

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

metam and MITC in Table 6 below.

Table 6: Projected Metam and MITC Registration Review Timeline

Activities Estimated Date

Opening the Docket

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

Close Public Comment 2013 – November

Case Development

Final Work Plan 2014 – February

Issue DCI 2014 April - June

Data Submission 2016 April - June

60-day Public Comment Period for Draft Risk 

Assessments9

2017 Oct. – Dec.

Registration Review Decision

60-day Public Comment Period for Proposed 

Registration Review Decision

2018 April - June

 9 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.
16

Table 6: Projected Metam and MITC Registration Review Timeline

Activities Estimated Date

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 metam and MITC.
17

Appendix – Additional Areas Considered in the Registration Review of 

Metam and MITC

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. Since metam uses are pre-plant and considered non-food, and MITC is

not registered for food/feed uses in the U.S., metam and MITC have no U.S. tolerances; 

therefore, the Agency does not anticipate any trade irritant issues.

Water Quality:

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

section 303(d) of the Clean Water Act.

10 In addition, no Total Maximum Daily Loads (TMDL) 

have been developed for MITC. More information on impaired water bodies and TMDLs can be 

found at the Agency’s website.

11 The Agency invites submission of water quality data for this 

pesticide in watersheds where soil fumigant use is prevalent. 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 Process12 in order to ensure they can be 

used quantitatively or qualitatively in pesticide risk assessments.

Due to the large and rapid conversion of metam sodium and metam potassium to MITC (83 

percent transformation and half life = 23 minutes), exposure to metam sodium and metam 

potassium in drinking water sources is not expected from pesticide applications.

In addition to the soil fumigant uses of metam sodium and metam potassium, there is a use in 

sanitary sewers to control tree roots. There is reportedly (Martyn, P., 2004) a contaminant 

(NDMA, nnitrosodimethylamine)in the product for which there is a National Recommended 

Water Quality Criteria of 0.00069 :g/L (current/potential drinking water) and 3.0 :g/L (no 

potential for drinking water). The Agency also requests submission of NDMA and MITC 

 10 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885 11 http://www.epa.gov/owow/tmdl/ 12 http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm
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water quality data at the discharge point in sewage treatment plants where MITC use in 

sewers occurs.

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 metam and/or MITC 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.

ENDANGERED SPECIES:

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

conducted for metam and MITC. The ecological risk assessment planned during registration 

review will allow the Agency to determine whether use of metam and MITC 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 most recent registration decision for metam and MITC,

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), 

metam and MITC are 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 
19

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, 201313 and includes some pesticides 

scheduled for Registration Review and chemicals found in water. 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.14

In the interim, EPA is making no human health or environmental safety findings associated with 

the EDSP screening of metam and MITC. Before completing this Registration Review, the 

Agency will make an EDSP FFDCA section 408(p) determination.

HUMAN STUDIES:

Occupational and Residential

Past metam and MITC 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), the 

Agricultural Reentry Task Force (ARTF) Database, and the Outdoor Residential Exposure Task 

Force (ORETF) 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.

Chemical-specific Human Studies

Past metam and MITC risk assessments rely in part on one human study which involved 

intentional exposure to MITC. An intentional dosing eye irritation and odor threshold study in 

human subjects (MRID no. 44400401) was used as the basis for the acute MITC endpoint. The 

Human Studies Review Board (HSRB) reviewed this study at a May 2-3, 2006 meeting. The 

HSRB concluded that all applicable requirements of EPA’s Rule for the Protection of Human 

Subjects of Research (40 CFR Part 26) were satisfied in the study and that there was no 

regulatory barrier to continued reliance on this study. In the course of registration review EPA 

will reconsider this study, as well as any other research involving intentional exposure of human 

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

chemicals.

14 http://www.epa.gov/endo/
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subjects to metam and/or MITC brought to its attention. If EPA decides to rely on any of these 

studies, EPA will ensure that all applicable regulatory requirements are met, including, but not 

limited to, the requirements for EPA ethics review and Human Studies Review Board review of 

certain research involving intentional exposure of human subjects.