2 I NTRODUCTION

This is the Environm ental Protection Agency’s (EPA or the Agency ) Final Work Plan (FWP) for the registration review of methyldithiocarbamate salts (metam sodium, metam potassium) and methyl isothiocyanate (MITC) . This work plan addresses public comments received concerning the Preliminary Work Plan (PWP) , which was posted in the methyldithiocarbamate salts (metam sodium, metam potassium) registration review docket (EPA

- HQ

- OPP

- 2013

- 0140 ) and the MITC registration review docket (EPA

- HQ

- OPP

- 2013

- 0242 )

. Metam sodium and metam potassium (hereafter referred collectively as “metam”) are n on

- 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 non

- agricultural registered uses of metam , including antimicrobial uses and sewer root

- cont rol use . After application

, metam break s down quickly to the primary toxic degradate, MITC gas. MITC is highly volatile and is responsible for the biocidal properties of these fumigants. In addition to being a degradate of metam, MITC is also registered it self as an antimicrobial active ingredient for wood pole/timber use . 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 registra tion review

case.

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. Informatio n on this program is provided on the Agency’s website

. 1

The FWP begins with any up dates 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 response s to th o se comments

. This section is followed by registration review planned data needs, risk assessments expected to be conducted , and the projected registration review timeline for metam and MITC

. Lastly, th ere is a discussion of next steps.

UPDATES SINCE THE PWP WAS ISSUED

• Changes to data requirements, Table 1

o The table now clarifies that data are not required for antimicrobial metam and MITC products registered only for wood pole /timber use.

o In the PWP, the honey bee acute contact toxicity study (850.3020) was incorrectly marked as “under review.” The study was waived in 2010. Therefore, it has been removed from Table 1.

1 http://www.epa.gov/oppsrrd1/registration_review/3 o The avian acute inhalation study was not listed in the PWP table for previously
requ ired data. It is now included in Table 1 below. The study is under review.

o Reviews of the prenatal developmental toxicity study (870.3700) and the acute neurotoxicity study (870.6200) are now complete and classified as acceptable. Therefore, these studies have been removed from Table 1.

o Data received for sewer uses of metam have been reviewed and found acceptable. Therefore, the sewer use studies have been removed from Table 1.

o The timeframe for the ambient air monitoring program has been extended from Marc h 2014 to December 2016. Since the PWP was issued, the registrants have been working with the Agency to develop a protocol for this study.

o The metam registrant with antimicrobial products registered for cooling tower and industrial water purification syste m uses has agreed to remove those uses from product labels. These uses triggered the need for post

- application exposure data. Therefore, when the uses are removed from labels, then metam antimicrobial post

- application exposure data (875.2500 and 875.2900) will no longer be required.

• Changes to risk assessments, Table 2

o T he Agency has concluded that a drinking water assessment will not be required for metam and MITC. Based on use patterns and the volatile nature of MITC, the Agency does not expect MITC to adversely impact drinking water sources such as surface water and ground water.

SUMMARY OF COMMENTS AND AGENCY RESPONSES

During the 60

- day public comment period on the Metam and MITC Preliminary Work Plan

, which opened on September 25, 2013 and closed on November 25, 2013 , the Agency received 2 8 total public comments on both the MITC and metam dockets

. Comments were submitted by
growers, grower groups, state agricultural offices, University of Georgia Extension, the Center for Biological Diversity, the task force representing metam pesticide registrants, and the FIFRA Endangered Species Task Force (FESTF)

. Two comments address ed the timeline described in the PWP by requesting an extension to the comment period. Co mments from the Metam Task Force specifically addressed the planned ecological and human health risk asse ssments and data requirements. Most comments expressed strong support for the continued registration for metam soil fumigant products and provided bene fits information. Some comments expressed concern over recently implemented risk mitigation measures, which were the result of the previous re

evaluation progra m, known as reregistration for metam. No comments were received regarding the antimicrobial uses of metam or MITC. 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.

None of the public comments resulted in changes to the anticipated registration review data needs, risk assessments, or timeline, or are o f a broader regulatory nature. Public comments in their entirety are located in the docket s , EPA

- HQ

- OPP

- 2013

- 0140 and EPA

- HQ

- OPP

- 2013

- 0242

. Summarized public comments and Agency responses related to the anticipated ecological risk assessment or data needs are in the EFED Response to Metam Task Force Comments to4 Data Call

- In and Problem Formulation on the Registration Review of Metam Sodium, Metam Potassium and Methyl Isothiocyanate (MITC) (DP Barcode: D416688 , dated February 10, 2014

. Comments relevant to the anticipated human health risk assessment or data needs are in the RESPONSE TO COMMENTS. The Health Effects Division’s Response to the Idaho State Departmen t of Agriculture on the Metam Sodium, Metam Potassium, Methyl Isothiocyanate Registration Review Scoping Document for Human Risk Assessment , dated February 18, 2014

. Responses to all other comments are in the Responses to Public Comments on the Metam and MITC Preliminary Work Plan

.

PLANNED DATA NEEDS

Table 1 below summarizes the planned data needs for metam and MITC based on the EFED and AD Registration Review Problem Formulation for Metam Sodium, Metam Potassium, and MITC, dated September 19, 2013

, and Metam Sodium, Metam Potassium, and MITC. Human Health Assessment Scoping Document in Support of Registration Review, dated September 4, 2013

. Some minor changes were made to the planned data needs table from what was included in the PWP

. T imeframes for some previously required data have been updated. Also, the table now clarifies that data will not be required for antimicrobial metam and MITC products registered only for wood pole use. Therefore, the A gency does not anticipate any data call in for the MI TC product, which is registered only for wood pole use. For an explanation, see pages 34

- 35 of the Problem Formulation

.

Table 1: Planned Data Needs for Metam Registration Review

Guideline Number Study Title Test Material Estimated Timeframe (Months from receipt of DCI)

Anticipated Data Needs for Soil Fumigant and Antimicrobial (other than wood pole /timber use) Uses of Metam 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

Non

guideline 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 125 Table 1: Planned Data Needs for Metam Registration Review

Guideline Number Study Title Test Material Estimated Timeframe (Months from receipt of DCI)

Outstanding Data Requirements from Post

- RED DCIs for All Uses 2

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 850.4150 Vegetative vigor (Tier II) MITC Under review 850.4400 Aquatic plant growth toxicity (Tier II) MITC Under review

Non

guideline Avian acute inhalation MITC Under review

Outstanding Data Requirements from Post

- RED DCIs for Soil Fumigant Uses Only 3
Non

guideline Ambient air monitoring program Metam

– TEP Due December 2016 Outstanding Data Requirements from Post

- RED DCIs for Antimicrobial Uses Only 4

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*

2 The studies listed in this section were previously required through generic metam sodium (metam

- Na) and metam

potassium (metam

- K) data call

- in s (DCI) issued in March 2010 a nd ar e 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 DCI s

. 3 The studies listed in this section were previously required through generic metam sodium (metam

- Na) and metam potassium (metam

- K) data call

- in s (DCI) issued in March 201 1 a nd 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 DCI s

. 4 The studies listed in this section were previously required through generic metam sodium (metam

- Na) and metam potassium (metam

- K) data call

- in s (DCI) issued in March 201 0 a nd 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 requi red through the earlier DCI s

.6 Table 1: Planned Data Needs for Metam Registration Review

Guideline Number Study Title Test Material Estimated Timeframe (Months from receipt of DCI)

875.2500 Inhalation exposure TEP Data may be waived pending

use deletion

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 Data may be waived pending

use deletion TGAI = technical grade active ingredient; TEP = typical end

- use product *After the PWP was issued, antimicrobial metam registrants submitted an updated extension request, which is currently under review.

RISK ASSESSMENTS FOR REGISTRATION REVIEW

During registration review, t he Agency will conduct a comprehensive ecological risk assessment, including an endangered species assessment, for all uses of metam and MITC. For human health, EPA will conduct revised residential and occupational risk assessments du ring 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 assessment s , as well as any changes to the standard operating p rocedures or default exposure assumptions

.

Table 2 below summarizes the planned registration review risk assessments based on the Problem Formulation and Scoping Document and has been updated since the PWP to reflect a change to one of the planned risk assessments . This change was based on discussion within EPA and not as a result of public comments.

Table 2: Planned Risk Assessments for the Registration Review of Metam and MITC
Type of Risk Assessment Conduct? Notes
Eco logical 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.7 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 on the labeled use sites as preplant soil fumigants, so these uses are considered non

- food
uses, an d 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

. Drinking water N Based on use patterns and the volatile nature of MITC, the Agency does not expect MITC to adversely impact drinking water sources such as surface water and ground water. A drinking water assessment will not be required for metam and MITC

. Occupational Handlers (mixers, loaders, appl icators) 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 post

application 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.8 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 E valuates the combined risk from dietary and residential exposures. No dietary risk is anticipated from metam and MITC uses. Theref ore, an aggregate assessment is not anticipated. Cumulative N Metam and MITC are not members of a cumulative group, so no cumulative risk assessment is planned. Tolerances N Currently labeled u ses 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.

TIMELINE

EPA has created the following estimated timeline for the completion of the metam and MITC 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 asse ssment and the proposed decision by one quarter.

Table 3: Registration Review for Metam and MITC

– Projected Registration Review Timeline Activities Estimated Date Opening the Docket Open Docket and 60

- day Public Comment Period Sept. 2013

– Completed Close Public Comment Nov. 2013

– Completed9 Table 3: Registration Review for Metam and MITC

– Projected Registration Review Timeline Activities Estimated Date Case Development Final Work Plan March. 2014

- Completed Issue DCI 2014: April

- June Data Submission 2016: April

- June 60

- day Public Comment Period for Draft Risk Assessments 7 [1] 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 requ ire several environmental fate and ecological effects studies for metam and MITC through a D ata C all

- I n Notice , expected to be issued in 2014 to metam sodium and metam potassium soil fumigant and antimicrobial registrants

. R egistrants that onl y register products with wood pole /timber use will not be issued a Data Call

In Notice . Therefore, the registrant for MITC will not receive a Data Call

- In Notice.

7 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, t he Agency plans to provide a 60 calendar day public comment period generally for draft risk assessments.