Note: 

This is the correct version of the Amended 

Reregistration Eligibility Decision (RED) for the 

Methyldithiocarbamate Salts (Metamsodium, Metampotassium) and Methyl Isothiocyanate (MITC) 

Please disregard the version in document number: 

EPA-HQ-OPP-2005-0125-0506 
United States Prevention, Pesticides EPA 738-R-09-310 

Environmental Protection and Toxic Substances May 2009 

Agency (7508P) 

Amended Reregistration Eligibility 

Decision (RED) for the 

Methyldithiocarbamate Salts (Metamsodium, Metam-potassium) and 

Methyl Isothiocyanate (MITC) 
Amended Reregistration Eligibility Decision (RED) Document 

for 

Methyldithiocarbamate Salts (Metam-sodium, Metam-potassium) and Methyl 

Isothiocyanate (MITC) 

List B 

Case Nos. 2390 and 2405 

Approved by: ____________________________ 

Richard P. Keigwin, Jr., Director 

 Special Review and Reregistration Division 

 Date: ____________________________
3

Glossary of Terms and Abbreviations 

1,3-D 1,3-dichloropropene 

AGDCI Agricultural Data Call-In 

ai Active Ingredient 

aPAD Acute Population Adjusted Dose 

ARS Agricultural Research Service 

BCF Bioconcentration Factor 

BEAD Biological and Economic Analysis Division 

CFR Code of Federal Regulations 

cPAD Chronic Population Adjusted Dose 

CSF Confidential Statement of Formulation 

CSFII USDA Continuing Surveys for Food Intake by Individuals 

DCI Data Call-In 

DEEM Dietary Exposure Evaluation Model 

DFR Dislodgeable Foliar Residue 

DNT Developmental Neurotoxicity 

EC Emulsifiable Concentrate Formulation 

EDWC Estimated Drinking Water Concentration 

EEC Estimated Environmental Concentration 

EPA Environmental Protection Agency 

EUP End-Use Product 

FDA Food and Drug Administration 

FDMS Federal Docket Management System 

FIFRA Federal Insecticide, Fungicide, and Rodenticide Act 

FFDCA Federal Food, Drug, and Cosmetic Act 

FMP Fumigant Management Plan 

FQPA Food Quality Protection Act 

GAP Good Agricultural Practice 

GLN Guideline Number 

ha Hectare 

HC Human Concentration 

IR Index Reservoir 

ISCST3 Industrial Source Complex Short Term (model) 

Kd Dissociation Constant 

LC50 Median Lethal Concentration. A statistically derived concentration of a 

substance that can be expected to cause death in 50% of test animals. It is 

usually expressed as the weight of a substance per weight or volume of 

water, air, or feed, e.g., mg/l, mg/kg, or ppm. 

LD50 Median Lethal Dose. A statistically derived single dose that can be 

expected to cause death in 50% of the test animals when administered by 

the route indicated (oral, dermal, inhalation). It is expressed as a weight 

of substance per unit weight of animal, e.g., mg/kg. 

LOC Level of Concern 
4

LOAEL Lowest Observed Adverse Effect Level 

MATC Maximum Acceptable Toxicant Concentration 

μg/g Micrograms Per Gram 

μg/L Micrograms Per Liter 

MAT Maximum Air Temperature 

MBAO Methyl Bromide Alternatives Outreach 

MITC Methyl Isothiocyanate 

mg/kg/day Milligram Per Kilogram Per Day 

mg/L Milligram Per Liter 

MST Maximum Soil Temperature 

MOA Mode of Action 

MOE Margin of Exposure 

mph Miles Per Hour 

MRID Master Record Identification Number. EPA’s system for recording and 

tracking studies submitted. 

MSDS Material Safety Data Sheet 

MUP Manufacturing-Use Product 

NOAEL No Observed Adverse Effect Level 

OECD 

OPP EPA Office of Pesticide Programs 

OPPTS EPA Office of Prevention, Pesticides, and Toxic Substances 

PAD Population Adjusted Dose 

PCA Percent Crop Area 

PDCI Product-Specific Data Call-in 

PDP USDA Pesticide Data Program 

PERFUM Probabilistic Exposure and Risk Model for Fumigants 

PF Protection Factor 

PHED Pesticide Handler’s Exposure Data 

PHI Pre-harvest Interval 

ppb Parts Per Billion 

PPE Personal Protective Equipment 

ppm Parts Per Million 

PRZM/EXAMS Pesticide Root Zone Model/Exposure Analysis Modeling System (Tier II 

Surface Water Computer Model) 

RAC Raw Agriculture Commodity 

RED Reregistration Eligibility Decision 

REI Restricted Entry Interval 

RfD Reference Dose 

RQ Risk Quotient 

SCI-GROW Tier I Ground Water Computer Model 

SAP Science Advisory Panel 

SF Safety Factor 

SLC Single Layer Clothing 

TGAI Technical Grade Active Ingredient 

USDA United States Department of Agriculture 
5

USGS United States Geological Survey 

UF Uncertainty Factor 

UV Ultraviolet 

WPS Worker Protection Standard 
6

Table of Contents 

Methyldithiocarbamate Salts and Methyl Isothiocyanate Team.............................................. 8 

Abstract.......................................................................................................................................... 9 

I. Introduction ............................................................................................................................. 10

II. Chemical Overview................................................................................................................ 15 

A. Chemical Identity............................................................................................................... 15 

B. Use Profiles.......................................................................................................................... 16 

C. Regulatory History............................................................................................................. 18 

III. Metam-sodium and Metam-potassium Risk Assessments................................................ 19 

A. General Overview of Soil Fumigants ............................................................................... 19 

1. Human Health Risk ........................................................................................................ 19 

2. Environmental Fate, Ecological Effects and Risks...................................................... 23 

3. Benefits............................................................................................................................. 25

4. 2008 RED Mitigation Impacts ....................................................................................... 29 

B. Overview of Sewer Use Risk.............................................................................................. 31 

C. Overview of Antimicrobial Risk ....................................................................................... 32 

IV. Risk Management and Reregistration Eligibility Decision .............................................. 33 

A. Determination of Reregistration Eligibility..................................................................... 33 

B. Public Comments and Responses ..................................................................................... 36 

C. Regulatory Position............................................................................................................ 37 

1. Regulatory Rationale...................................................................................................... 37 

a. Soil Fumigant Uses of Metam-sodium and Metam-potassium............................... 37 

1. Use Sites Eligible for Reregistration ................................................................. 38 

aa. Bystander Risk Mitigation ....................................................................................... 43 

1. Buffer Zones........................................................................................................ 44 

2. Restriction for Schools and Other Difficult To Evacuate Sites ...................... 75 

3. Posting.................................................................................................................. 76 

bb. Occupational Risk Mitigation for Soil Uses........................................................... 78 

1. Handler Definition .............................................................................................. 79 

2. Handler Requirements ....................................................................................... 80 

3. Dermal Protection for Handlers........................................................................ 81 

4. Respiratory Protection for Handlers ................................................................ 85 

5. Tarp perforation and removal........................................................................... 93 

6. Entry Prohibitions .............................................................................................. 96 

cc. Other Risk Mitigation............................................................................................. 102 

1. Restricted Use Pesticide (RUP) Classification................................................ 102 

2. Good Agricultural Practices (GAPs)............................................................... 103 

3. Fumigant Management Plans (FMPs) ............................................................ 113 

4. Site Specific Response and Management........................................................ 120 

5. Notice to State Lead Agencies.......................................................................... 126 

6. Training for Applicators and Training Information for Other Handlers... 127 

7. Community Outreach and Education Program............................................. 132 

8. Ambient Air Monitoring Program.................................................................. 137 
7

b. Sewer Root Control Use ........................................................................................... 139 

c. Antimicrobial Uses.................................................................................................... 146 

2. Endocrine Disruptor Effects........................................................................................ 149 

3. Endangered Species Considerations ........................................................................... 150 

D. Conclusion......................................................................................................................... 150 

V. What Registrants Need to Do.............................................................................................. 150 

A. Manufacturing Use Products.......................................................................................... 151 

1. Additional Generic Data Requirements...................................................................... 151 

2. Labeling for Manufacturing-Use Products ................................................................ 158 

B. End-Use Products............................................................................................................. 158 

1. Additional Product-Specific Data Requirements....................................................... 158 

2. Labeling for End-Use Products................................................................................... 159 

Appendix A: Uses Eligible for Reregistration........................................................................ 202 

Appendix B: Studies Used to Make the Reregistration Decision ......................................... 214 

Appendix C: Technical Support Documents.......................................................................... 215 

Appendix D: FMP Template-MeBr Example ........................................................................ 218 
8

Methyldithiocarbamate Salts and Methyl Isothiocyanate Team 

Health Effects Risk Assessment Office of General Council

Ruth Allen Andrea Medici 

Judy Facey 

Anna Lowit 

Jessica Ryman Office of Enforcement and 

Charles Smith Compliance

Shalu Shelat David Stangel 

Biological and Economic Analysis Assessment Risk Management 

Jonathan Becker Dirk Helder 

Angel Chiri Veronique LaCapra 

Bill Chism John Leahy 

Colwell Cook Nikhil Mallampalli 

David Donaldson Cathryn OConnell 

John Faulkner Karen Santora 

Monisha Kaul 

Andrew Lee 

Nikhil Mallampalli Registration Support

William Phillips, II Tamue Gibson 

Sunil Ratnayake Mary Waller 

Elisa Rim 

Stephen Smearman 

TJ Wyatt 

Leonard Yourman 

Nicole Zinn 

Environmental Fate and Effects Risk Assessment

James Felkel 

Faruque Khan 

Gabriel Rothman 

Risk Management – Antimicrobial Uses

Timothy Dole 

Heather Garvie 

Diane Isbell 

Timothy Leighton 

Tim McMahon 

Kathryn Montague 

Rick Petrie 

Cassi Walls 
9

Abstract 

This document presents EPA’s amended decision regarding the reregistration eligibility 

of the currently registered soil, sewer root control, and antimicrobial uses of metam-sodium, the 

soil and antimicrobial uses of metam-potassium, and the antimicrobial uses of methyl 

isothiocyanate (MITC). This follows the 105-day public comment period on the Reregistration 

Eligibility Decision provided for stakeholders to have the opportunity to review and provide 

comments on issues related to the implementation of the risk mitigation measures. The 

Agency’s risk conclusions for metam-sodium and metam-potassium have not changed. In 

addition, all measures established in the July 2008 RED to reduce risks to bystanders and 

workers will still be required. However, the Agency has determined that certain modifications in 

how and when some measures will be implemented are appropriate. Products containing metamsodium and metam-potassium for these uses are eligible for reregistration provided that: (1) 

current data gaps are addressed; (2) the risk mitigation measures identified in the document are 

adopted; and (3) labels are amended to implement these measures. 

Generally, registered metam-sodium and metam-potassium application/fumigation uses 

fall into four basic categories that include: (1) use as an agricultural soil fumigant for all food, 

feed, and fiber crops; (2) use on golf course turf and for application to small areas of turf and 

soil; (3) use as a root-control agent in drains and sewers; and (4) use for a number of 

antimicrobial and industrial uses, including treatments for sugar (raw beets and cane sugar) 

processing facilities; leather; sewage, sludge, and animal waste; cooling water facilities; 

industrial water purification facilities; paints and coatings; petroleum operations; and remedial 

wood treatment. MITC is registered as an active ingredient for only one use, as an antimicrobial 

agent for remedial wood treatment. 

Concurrent to EPA’s review of the soil fumigant uses of metam-sodium and metampotassium, EPA assessed the risks and developed risk management decisions for four other soil 

fumigant pesticides, including: chloropicrin, dazomet, methyl bromide, and a new active 

ingredient, iodomethane. Risks of a fifth soil fumigant, 1,3-dichloropropene (1,3-D), were also 

analyzed along with the other soil fumigants for comparative purposes; its risk management 

decision was completed in 1998. The Agency evaluated these soil fumigants concurrently to 

ensure that human health risk assessment approaches are consistent and that risk tradeoffs and 

economic outcomes were considered appropriately in reaching risk management decisions. This 

review is part of EPA’s program to ensure that all pesticides meet current health and safety 

standards. 

EPA has identified potential human health risks of concern associated with the registered 

soil fumigant uses of metam-sodium and metam-potassium from acute inhalation exposure to 

handlers, bystanders, and re-entry workers. To reduce these exposures and to address subsequent 

risks of concern, EPA is requiring a number of mitigation measures, such as classifying some 

metam-sodium and metam-potassium products as restricted use, use-site restrictions, buffer 

zones, posting, emergency preparedness and response, monitoring and respiratory protection, 

restrictions on the timing of tarp perforation and removal operations, entry prohibitions, 
10

mandatory good agricultural practices (GAPs), fumigant management plans (FMPs), and training 

and outreach programs. Please note that only metam-sodium and metam-potassium soil and 

sewer use products and the MITC use for remedial treatment of wood poles and timbers will be 

classified as restricted use pesticides. 

The Agency has identified slight exceedance of the non-cancer level of concern for shortand intermediate-term dermal exposure to metam sodium to applicators associated with the 

registered sewer root control use of metam-sodium. The Agency also has identified concerns 

due to potentially harmful downstream effects of metam-sodium on denitrifying bacteria and the 

associated disruption to downstream sewage treatment facilities. To reduce applicator 

exposures, the Agency is requiring additional personal protective equipment (PPE), including 

chemical-resistant gloves, double layer clothing, and a NIOSH-approved full-face respirator with 

organic vapor cartridge. To reduce the potentially harmful effects of metam-sodium on 

denitrifying bacteria at downstream sewage treatment facilities, the Agency will be requiring 

additional label language requiring notification of downstream wastewater facilities before a 

metam application takes place. 

The Agency also has identified potential human health risks of concern associated with 

the registered antimicrobial uses of metam-sodium, metam-potassium, and MITC. To reduce 

these exposures, the Agency is requiring a number of mitigation measures, such as additional 

labeling language for remedial wood treatment and amended labeling for the cooling tower and 

sewage sludge/animal waste uses. In addition, the Agency will be calling in air concentration 

monitoring data for all enclosed facilities that use metam-sodium and metam-potassium. 

 The Agency is issuing this amended decision document for metam-sodium, metampotassium, and MITC, as announced in a Notice of Availability published in the Federal 

Register. 

I. Introduction

This amends and supersedes the document, “Reregistration Eligibility Decision for 

Methyldithiocarbamate Salts (Metam-sodium, Metam-potassium) and Methyl Isothiocyanate 

(MITC),” published by the U.S. Environmental Protection Agency (hereafter, EPA) on July 16, 

2008. That day EPA opened a 60-day public comment period on the implementation aspects of 

the risk mitigation measures that were required as conditions of reregistration eligibility under 

FIFRA. EPA received requests to extend the comment period from the Methyl Bromide Industry 

Panel (MBIP), California Specialty Crops Council, the Chloropicrin Manufacturers' Task Force 

(CMTF), the National Association of Manufacturers (NAM), the American Nursery and 

Landscape Association (ANLA), the California Strawberry Nurserymen's Association, the 

Agricultural Retailers Association, the American Forest and Paper Association, and McDermott, 

Will, and Emery LLP, on behalf of the Minor Crop Farmer Alliance (MCFA). In response to 

these requests, on August 29, 2008, EPA published a notice in the Federal Register extending 

the comment period for an additional 45 days. The comment period closed on October 30, 2008. 

EPA has completed its review of public comments as well as new scientific data and other 
11

information provided and determined that all measures established in the July 2008 RED to 

reduce risks to bystanders and workers will still be required. The Agency has determined that 

certain modifications in how and when some measures will be implemented are appropriate. The 

public comments and EPA’s responses, as well as other supporting documents, may be found in 

the public docket for metam-sodium and metam-potassium (EPA-HQ-OPP-2005-0125) at 

www.regulations.gov. EPA has determined that the modifications described herein will achieve 

the same protection goals for persons potentially exposed to metam-sodium and metampotassium and MITC but with a greater likelihood of compliance, fewer impacts on the benefits 

of metam-sodium and metam-potassium and MITC use, and with less uncertainty regarding the 

protectiveness of the required measures. Please see table 1 for modification from the 2008 RED 

to the 2009 amended soil fumigant REDs. 

Note: Washington State University has submitted studies to quantify the flux rate for metamsodium and metam-potassium from shank injection applications and from center pivot 

applications using a drizzle boom in the Pacific Northwest. These studies were submitted in 

April, 2009, and are currently in review. If these studies indicate that the buffer zones for these 

types of applications should be modified, the Agency will update the buffer tables prior to 

implementation of new labeling related to buffers for metam sodium in 2011. The results of 

these studies have not been included in this amended document. 

Table 1. Modifications from 2008 to 2009 Amended Soil Fumigant REDs 

Mitigation 2008 REDs 2009 Amended REDs 

Buffer Zones Buffer zones based on 

available data 

New chloropicrin data support smaller 

buffers and increased confidence in safety 

New dazomet data support larger buffers 

Buffer Credits Credits allowed based on 

available data; capped at 

50% 

New data support additional credits and an 

increase in the cap to 80% for chloropicrin 

and methyl bromide, metam-sodium and 

metam-potassium, and 40% for dazomet 

Structures within 

Buffer Zones 

Monitor with devices 

before reentry 

Monitor for sensory irritation before 

reentry 

Rights of Way Permission from local 

authorities must be granted 

if buffers extend onto 

rights of way 

Permission from local authorities is only 

required when a sidewalk or permanent 

walkway is present 

Buffer Overlap Buffers may not overlap Buffers may overlap; separate applications 

by 12 hours and increase emergency 

preparedness and response measures 

Restriction for 

Difficult to Evacuate 

Sites 

1/4 mile restriction around 

hard to evacuate areas 

including day care centers, 

nursing homes, schools; 

was to be in effect for the 

duration of the buffer zone 

period 

Maintain 1/4 mile restriction but allow a 

reduced restricted area of 1/8 mile for 

applications with smaller buffers (300 feet 

or less); is to be in effect during the 

application for 36 hours following the 

application 

Posting Posting required at buffer The posting requirement is retained but no 
12

Mitigation 2008 REDs 2009 Amended REDs 

zones points of entry, 

where people are likely to 

approach, and areas 

between these locations 

longer requires areas between the entry 

areas to be posted 

Information required on the signs has been 

simplified to encourage reuse of signs 

Handler Protection Described tasks that may 

only be performed by 

handlers and situations 

when 2 handlers were 

required to be present 

while in the buffer zone 

Tasks that may only be performed by 

handlers have been updated and clarified 

The situations have been clarified 

requiring 2 handlers to be present based on 

the chemical properties of the different soil 

fumigants, and current label statements 

Respiratory 

Protection 

Required monitoring 

devices to trigger 

additional measures 

Allow sensory irritation properties to 

trigger additional measures for MITC and 

chloropicrin 

Monitoring with devices required to 

remove respirators 

Monitoring with devices required for 

methyl bromide formulations with <20% 

chloropicrin 

Tarp perforation and 

removal 

Perforating tarps restricted 

to mechanical means only 

Perforating tarps by hand is allowed for 

areas less than 1 acre in size and for flood 

prevention activities 

Entry Prohibitions Entry for non-handlers is 

prohibited for the duration 

of the entry restricted 

period, until tarps have 

been removed, or if 14 

days has passed 

No major changes 

Restricted Use 

Classification 

The soil fumigant uses of 

metam-sodium and metam 

potassium, and MITC use 

for remedial treatment of 

wood poles and timbers

are required to be classified 

as restricted use 

No change 

Good Agricultural 

Practices 

(GAPs) 

Certain GAPs required for 

all fumigant applications 

Some clarifications and refinements have 

been made based on stakeholder comments 

Fumigant 

Management Plans 

(FMPs) 

FMPs required to be 

completed before fumigant 

application begins and 

post-application summary 

report required following 

the application 

No major changes. Based on comments an 

example of an FMP has been included to 

illustrate how the required information 

may be presented effectively 

Emergency Response 

and Preparedness 

If neighbors are near 

buffers they must be 

provided with information 

Same basic measures 

Monitoring required only during peak 

emission times of the day; irritation 
13

Mitigation 2008 REDs 2009 Amended REDs 

or buffer zones must be 

monitored every 1-2 hours 

over 48 hours with 

monitoring devices 

detection acceptable for MITC and 

chloropicrin in lieu of devices; methyl 

bromide requires devices 

Notice to SLAs Applicators required to 

provide notice to the 

appropriate state/tribal lead 

agency before fumigating 

to facilitate compliance 

assistance and assurance 

States may determine if they wish to 

receive this information 

All states required to include strategies for 

compliance assistance and assurance for 

soil fumigation in their cooperative 

agreements 

Applicator Training Certified applicators 

required to receive 

registrant soil-fumigant 

training every year 

Certified applicators required to receive 

registrant soil-fumigant training every 

three years 

Community Outreach 

and Education 

Registrants required to 

develop and implement 

community outreach & 

education programs along 

with information for first 

responder in high fumigant 

use areas 

Same basic requirement 

The Agency is providing information on 

where registrants are required to focus 

these efforts 

 With regard to implementation timing, EPA has determined that most measures can be 

efficiently implemented via revised product labels by the 2010 use season for the antimicrobial 

uses, the sewer root-control uses, and the soil fumigant uses. Other measures, in particular those 

related to buffer zones, will present greater compliance challenges and will require additional 

time for EPA to conduct the necessary outreach, and communication activities with states, tribes, 

other regulatory partners, fumigant users, and other stakeholders to facilitate transition. EPA has 

determined that these measures will be implemented via revised product labels by the 2011 use 

season. As a result, all measures described in this amended RED that are necessary for 

reregistration eligibility will appear on product labels by 2011. The table below shows the 

measures that will be implemented in 2010 and the additional measures that will be implemented 

in 2011. 

Table 2. Implementation Schedule for Soil Fumigant Risk Mitigation Measures 

Risk Mitigation Measure Currently 2010 2011 

Restricted Use (for soil uses of metam-sodium and 

metam-potassium, and MITC use for remedial 

treatment of wood poles and timbers only) ● ●

New Good Agricultural Practices ● ●

Rate reductions ● ●

Use site limitations ● ●

New handler protections ● ●
14

Risk Mitigation Measure Currently 2010 2011 

Tarp cutting and removal restrictions ● ●

Extended worker reentry restrictions ● ●

Training information for workers ● ●

Fumigant Management Plans ○ ●

First responder and community outreach ○ ●

Applicator training ○ ●

Compliance assistance and assurance measures ○ ●

Restrictions on applications near sensitive areas ●

Buffer zones around all occupied sites ●

Buffer credits for best practices ●

Buffer posting ●

Buffer overlap prohibitions ●

Emergency preparedness measures ●

○ = under development 

● = adopt completely 

The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) was amended in 1988 

to accelerate the reregistration of products with active ingredients registered prior to November 

1, 1984. The amended Act calls for the development and submission of data to support the 

reregistration of an active ingredient, as well as EPA’s review of all submitted data. 

Reregistration involves a thorough review of the scientific database underlying a pesticide's 

registration. The purpose of the Agency's review is to reassess the potential risks arising from 

the currently registered uses of the pesticide; to determine the need for additional data on health 

and environmental effects; and to determine whether or not the pesticide meets the “no 

unreasonable adverse effects” criteria of FIFRA. 

 

This document presents the Agency’s amended reregistration eligibility decision for all 

the registered uses of metam-sodium, metam-potassium, and methyl isothiocyanate. Metampotassium and metam-sodium are non-selective fumigants with fungicidal, herbicidal, 

insecticidal, and nematicidal properties. Metam-sodium and metam-potassium are converted to 

MITC in the environment, particularly in the presence of moisture (such as in soil after 

application). It is MITC that performs the fumigating activity. Metam-sodium and metampotassium have soil fumigant and antimicrobial uses, metam-sodium is also used as a root 

control agent in sewers and drains, and MITC is registered as an antimicrobial agent for treating 

wood poles and pilings. Separate risk assessments and analyses were developed for the soil 

fumigant, sewer root control, and antimicrobial uses of metam-sodium, metam-potassium, and 

MITC. To clearly present EPA’s decision regarding these uses, each use will be discussed in 

separate sections of this reregistration eligibility decision (RED). 

As a result of this review, the Agency has determined that certain uses of (1) metamsodium (including use as a pre-plant soil fumigant in certain crops, specified later in this 

document, and as a root control agent in sewers and drains, and as an antimicrobial agent to treat 
15

wood poles and timbers and sewage sludge and animal waste); (2) metam-potassium (including 

use as a pre-plant soil fumigant in certain crops, specified later in this document, and as an 

antimicrobial agent for treatment of pulp and paper, tanning drum leather applications, 

recirculating cooling water systems, and industrial water purification systems); and (3) MITC 

(for use as an antimicrobial agent to treat wood poles and pilings) are eligible for reregistration 

(see Appendix A), provided the risk mitigation measures outlined in this document are adopted, 

label amendments are made to reflect these measures (see the label table in Section V of this 

document), and data are developed to assess intermediate- and long-term risk to bystanders. 

This document consists of five sections. Section I contains the regulatory framework for 

reregistration and a synopsis of modifications from the July 2008 RED. Section II provides a 

profile of the use and usage of the chemical. Section III provides a general fumigant overview 

and also the metam-sodium, metam-potassium, and MITC risk assessments as well as benefit 

and impact assessments. Section IV presents the Agency’s reregistration eligibility and risk 

management decisions. Section V summarizes label changes necessary to implement the risk 

mitigation measures outlined in Section IV. Unless otherwise noted, all Agency references in 

this document are available for review in the metam-sodium and metam-potassium docket (EPAHQ-OPP-2005-0125) at www.regulations.gov. 

II. Chemical Overview 

 A. Chemical Identity 

 Both metam-sodium and metam-potassium are the active ingredients that make up 

reregistration case 2390 for the methyldithiocarbamate salts. The primary degradate of both 

metam-sodium and metam-potassium is methyl isothycyanate (MITC), which is the active 

ingredient that makes up reregistration case 2405. 

Table 3. Methyldithiocarbamate Salts & Methyl Isothiocyanate Nomenclature 

Chemical Structure: 

H C3

N

H

S

S

Na+

H C3

N

H

S

S

K

+

 H3

C

N

C S

Empirical Formula: C2H4NS2Na C2H4NS2K C2H3NS 

Common Name: Metam-sodium Metam-potassium Methyl 

isothiocyanate 

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

OPP Chemical Code: 039003 039002 068103 

Case Number: 2390 2390 2405 

Technical or 

Manufacturing-Use 

Registrants 

Douglas Products and 

Packing Company; 

IBC Manufacturing 

Co.; Buckman 

Laboratories Inc.; 

Buckman 

Laboratories Inc.; 

Athea Laboratories 

Inc.; Taminco Inc.; 

Tessenderlo Kerley, 

MLP International 

(Landis 

International, Inc.); 

Osmose Utilities 

Services, Inc. 
16

AMVAC Chemical 

Corporation; Drexel 

Chemical Co.; 

Loveland Products, 

Inc.; Taminco Inc.; 

BASF Sparks LLC; 

Tessenderlo Kerley, 

Inc.; Sewer Sciences, 

Inc.; Osmose Utilities 

Services, Inc. 

Inc. 

B. Use Profiles 

Pesticide Type: Metam-sodium and metam-potassium are broad-spectrum fumigants 

with fungicidal, bactericidal, algicidal, herbicidal, insecticidal, 

nematicidal, and antimicrobial properties. They are dithiocarbamate 

salts that break down quickly in the environment to the primary toxic 

degradate, methyl isothiocyanate. MITC is highly volatile and is 

responsible for the fumigant properties of metam-sodium and metampotassium. 

1. Soil Use

Target pests: Metam-sodium and metam-potassium are used on a wide range of 

pests including fungi, plants, insects, and nematodes. 

Use patterns: Metam-sodium and metam-potassium are registered: (1) as an 

agricultural soil fumigant for use on all food, feed, and fiber crops 

and (2) for use on golf course turf and for application to small areas 

of turf and soil. 

Formulations: Three formulation classes—liquid, soluble concentrate, and ready-touse—are registered for metam-sodium and metam-potassium. Most 

metam-sodium products are registered for general use. Only the 

metam-sodium products registered specifically for use on golf courses 

and for use on small areas of turf and soil are classified as “restricted 

use.” The “restricted use” classification restricts a product, or its uses, 

to use by certified pesticide applicators or those working under the 

direct supervision of a certified applicator. No metam-sodium 

products are intended for use by homeowners. 

Methods of Application: In agricultural settings, metam-sodium and metam-potassium are 

applied through chemigation or with tractor-drawn equipment. 

Chemigation methods include sprinkler irrigation (which accounts for 

90% of irrigation applications), drip irrigation, flood irrigation, and 

furrow irrigation. Tractor-drawn applications are carried out with 

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

injection equipment. Drip/trickle irrigation and tractor-drawn 
17

applications can be either tarped or untarped. Applications to smaller 

areas can be made with handheld equipment, including sprinkler cans, 

hose proportioners (hose-end sprayers), or power sprayers (handgun 

sprayers). Metam-sodium and metam-potassium applications to 

potting soil may be made by adding the chemical to soil in a cement 

mixer or by spraying it onto a soil stream as soil is ejected from a 

shredder 

Application Rates: The maximum application rate listed on most product labels for 

application to ornamentals; turf; and food, feed, and fiber crops is 320 

pounds of active ingredient per acre (lbs ai/A). Tobacco plant beds 

have a maximum application rate of 387 lbs ai/A on most product 

labels, but at least one product lists a rate as high as 412 lbs ai/A. For 

small areas of ornamentals, food and fiber crops, seed beds, plant 

beds, and lawns, the maximum application rate is 12 lbs ai/1000 

square feet. 

Annual Usage in the 

U.S.: 

Approximately 51-55 million pounds of metam-sodium and 1-2 

million pounds of metam-potassium used in the U.S. in 2002. 

2. Sewer Use 

Target pests: Metam-sodium is used as a root control agent for use in sewers and 

drains. 

Use patterns: Metam-sodium is classified as a restricted use product as a rootcontrol agent in drains and sewers. 

Formulations: Three formulation classes—liquid, soluble concentrate, ready-touse—are registered for metam-sodium. All metam-sodium products 

for sewer use are classified as restricted use pesticides. The “restricted 

use” classification restricts a product, or its uses, to use by certified 

pesticide applicators or those working under the direct supervision of 

a certified applicator.

Methods of Application: In sewer use applications, metam-sodium is applied using a foam 

applicator. 

Application Rates: For sewers and drains, the maximum application rate is 0.212 lbs 

ai/gallon of solution. 

3. Antimicrobial Use

Target pests: The antimicrobial uses of metam-sodium, metam-potassium, and 

MITC are used to control a number of microbiological pests, 

including bacteria and fungi. 

Use patterns: • Metam-sodium is registered as an antimicrobial agent for: (1) 

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

hides and skins), (3) raw cane and beet sugar processing 

facilities, and (4) sewage sludge/animal wastes. 

• Metam-potassium is registered as an antimicrobial agent for: 

(1) pulp and paper production, (2) leather processing, (3) raw 
18

cane and beet sugar processing facilities, (4) coatings 

(protective colloids, emulsion resins, and water-thinned 

paints), (5) metalworking cutting fluids and oils, (6) 

petroleum operations, (7) water cooling tower systems, and 

(8) industrial water purification systems. 

• MITC is registered as an antimicrobial agent for wood poles 

and pilings. 

Formulations: Two formulation classes—soluble concentrate and ready-to-use—are 

registered for metam-sodium and metam-potassium. MITC is 

formulated as a solidified-melt, where it is a solid at ambient 

conditions and melts and vaporizes at elevated temperatures found 

within the pole being treated. 

Methods of Application: The antimicrobial uses of metam-sodium, metam-potassium, and 

MITC 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. 

C. Regulatory History 

 Metam-sodium (PC Code 039003) and metam-potassium (PC code 039002) are included 

in pesticide reregistration case number 2390. Currently, there are 39 registered products 

containing metam-sodium and 16 registered products containing metam-potassium. Metamsodium and metam-potassium are broad-spectrum fumigants with fungicidal, herbicidal, 

insecticidal, bactericidal, algicidal, and nematicidal properties. 

Metam-potassium was first registered in the United States in 1973 as a fungicide, a 

bacteriostat, and a microbicide in a variety of commercial and industrial applications, such as 

pulp and paper mills, cooling tower waters, metalworking cutting fluids, and adhesives. In 1994, 

the use of metam-potassium expanded to include food and feed uses when used as a soil 

fumigant. 

 Metam-sodium was first registered in the United States in 1975. Metam-sodium is one of 

the most widely used agricultural pesticides in the United States and is presently registered on a 

wide variety of food and feed crops. Metam-sodium is also registered for a variety of 

antimicrobial and industrial uses. 

 Metam-sodium and metam-potassium are converted to MITC in the environment, 

particularly in the presence of moisture. It is MITC that performs the fumigating activity. It is 

the volatility of metam-sodium in the environment and the results of metabolism studies in plants 

that allow the Agency to conclude 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 the establishment of food tolerances. 
19

A Phase IV data call-in (DCI) was issued for metam-sodium and metam-potassium in 

September 1991 and included data requirements for ecotoxicity, toxicology, environment fate, 

and residue chemistry. Metam-sodium also was included in the October 1995 agricultural 

reentry DCI. 

Since metam-sodium and metam-potassium are converted to MITC in the environment, 

this RED will also include MITC. MITC (PC code 068103) is in case number 2405. Products 

containing MITC were first registered in 1984 as a soil fumigant with food and non-food uses. 

A Phase IV DCI was issued for MITC in July 1991 and included data requirements for 

ecotoxicity, toxicology, environment fate, and residue chemistry. In response to this DCI, the 

registrants canceled all remaining food uses in 1992. Currently, the only two remaining products 

containing MITC are for use on wood pilings, utility poles, and timbers for control of wood rot 

and decay due to fungal activity. Both products are classified as restricted use. 

III. Metam-sodium and Metam-potassium Risk Assessments 

A. General Overview of Soil Fumigants 

Soil fumigants are pesticides that form gasses when applied to soil. Once in the soil, the 

fumigants work by controlling pests that can disrupt plant growth and crop production. Soil 

fumigants play a very important role in agriculture, but they also have the potential to pose risk 

concerns to people involved in application of the chemicals (handlers), workers who re-enter 

fumigated fields (workers), and people who may be near the treated area (bystanders). 

 1. Human Health Risk 

The main risk of concern for handlers, workers, and bystanders associated with the soil 

uses of metam-sodium and metam-potassium is from acute inhalation exposure as a result of 

fumigant off-gassing. Metam-sodium and metam-potassium handlers also are at risk from direct 

fumigant exposure during applications. The term handler refers to persons involved in the 

application. For soil applications, handlers also include persons involved in perforating and 

removing of tarps. The term worker in this document refers to persons performing non-handler 

tasks within the application block after the fumigation process has been completed, such as 

planting. The term bystander refers to any person who lives or works in the vicinity of a 

fumigation site. 

In addition to the soil use of metam-sodium and metam-potassium, there are other uses 

that the Agency has assessed and included in this RED: (1) metam-sodium as a root control agent 

in sewers and drains and as an antimicrobial agent to treat wooden poles, timbers, sewage sludge, 

and animal waste; (2) metam-potassium as an antimicrobial agent for treatment of pulp and 

paper, leather tanning drum, recirculating cooling water systems, and industrial water 

purification systems; and (3) MITC as an antimicrobial agent to treat wood poles and pilings. 
20

When metam-sodium and metam-potassium are applied and mixed with moist soil or 

water, they are quickly broken down into several strong irritant products. One of these products 

is MITC, which accounts for most of the fumigant activity. Based on monitoring data, it is clear 

that bystander exposures to concentrations of MITC in the air after a metam-sodium and metampotassium application are possible. Therefore, the focus in assessing inhalation bystander and 

occupational exposures resulting from metam-sodium and metam-potassium applications is on 

concentrations of MITC. 

Estimating exposure to fumigants is different from non-fumigant pesticides due to 

fumigants’ volatility and thus, increased ability to move off site during and after application. 

For example, pesticide spray drift is the physical movement of pesticide particulate or droplets 

from the target site during the application and soon thereafter. In the case of soil fumigants, the 

pesticide moves as a gas (not as particulate or droplets), and movement off site can occur for an 

extended period after application. Importantly, fumigants have a well-documented history of 

causing large-scale human exposure incidents up to several thousand feet from treated fields. 

Assessing fumigant exposure takes into account the size of the fumigated field, the amount of 

fumigant applied, and the rate at which the fumigant escapes from the treated field. 

The term “flux rate” or “emission rate” defines the rate at which a fumigant off-gasses 

from a treated field. Many factors influence the rate of emissions from treated fields after the 

application of soil fumigants. Factors such as the application method, soil moisture, soil 

temperature, organic matter levels, water treatments, the use of tarps, biological activity in the 

soil, soil texture, weather conditions, soil compaction, and others influence the amount of 

fumigant that comes off the field and is available to move off site to areas where bystanders may 

be located. 

The human health risk assessment indicates that acute inhalation exposures to MITC of 

22 ppb or greater for a 1 to 8 hour time period for non-occupational (residential) bystanders and 

occupational handlers could potentially pose risks of concern. The 22 ppb concentration is based 

on a reversible endpoint from a human eye irritation and odor threshold study for acute 

exposures to MITC. The lowest observable adverse effect level (LOAEL) was 800 ppb, and the 

human concentration (HC) based on the No Observable Adverse Effect Level (NOAEL) from 

this study is 220 ppb. The NOAEL of 220 ppb being used by EPA is similar to a benchmark 

concentration level of 200 ppb submitted by the group Toxicology Excellence in Risk 

Assessment (TERA) on behalf of the metam-sodium and metam-potassium registrants. The 

benchmark concentration analysis thus supports the Agency’s toxicity endpoint. Since the study 

is a human exposure study for acute eye exposure to MITC, the standard 10X for animal to 

human extrapolation is not needed. However, a 10X human variability uncertainty factor for 

MITC was included, which when applied to the HC, results in the target concentration for acute 

inhalation exposures of 22 ppb. 

California Pesticide Illness Surveillance Program data from 1992-2003 confirm that eye 

effects from MITC exposure as seen in this human study provide a sensitive endpoint for 
21

regulating acute inhalation exposures. In many incident cases, people complain of eye effects. 

However, many reported cases also report systemic or respiratory effects, and a few have effects 

without eye irritation. Compared to eye irritation, the systemic and respiratory effects are more 

adverse in nature. Unfortunately, the available toxicity data in animals or humans do not allow a 

quantitative comparison of the dose response curves of the eye, systemic, and respiratory effects 

to determine the exact doses at which those effects occur. However, the Agency believes eye 

irritation provides a surrogate for other toxic effects and thus makes this the appropriate endpoint 

to regulate. To ensure that this endpoint is protective of any effects from repeated and longerterm exposures, EPA is requiring data to evaluate developmental, reproductive, chronic, and 

cancer hazards and has encouraged the registrants to pursue additional studies to characterize the 

dose response curves of different target organs. 

The Agency has not revised the 10X human variability uncertainty factor for MITC and 

the MITC-generating compounds. Agency scientists have carefully reviewed comments 

provided by the Metam Alliance and TERA that claim a mode of action (MOA) evaluation for 

MITC and the relative sensitivities of the eyes and lungs to MITC, support an uncertainty factor 

less than 10X. Upon request by the Metam Alliance, Agency scientists have evaluated the 

registrant's scientific position [see www.regulations.gov, docket number: EPA-HQ-OPP-2005-

0125]. While Agency scientists acknowledge that data are available to formulate a hypothesis 

for a MOA, currently available data are insufficient to support the key events of the proposed 

MOA and also to refute other scientifically plausible hypotheses (a step critical in a MOA 

framework analysis). Moreover, there remains uncertainty with respect to the dose response 

relationship for sensitive measures of respiratory effects. Thus, given gaps in the existing data 

for MITC, the Agency is unable to determine, according to existing guidance, that the 

uncertainty factor can be reduced. If, in the future, additional data are provided, the Agency will 

re-evaluate the scientific basis for MITC's human variability uncertainty factor. 

In assessing risks from metam-sodium and metam-potassium, the Agency considered 

multiple lines of evidence, using the best available information from monitoring studies, 

modeling tools, and incident data. 

• Monitoring: For the human health risk assessments completed for metam-sodium and 

metam-potassium and the other soil fumigants within the group, several field-scale 

monitoring studies were considered, as well as monitoring of workers and handlers 

involved in various tasks. These studies quantify metam-sodium and metam-potassium 

concentrations in and around fields at various times and distances during and after 

applications. Many of these data indicate that there can be risks of concern associated 

with metam-sodium and metam-potassium use at a broad range of distances from treated 

fields. However, these data are limited in their utility because they provide results only 

for the specific conditions under which the study was conducted. 

 

• Modeling: Models enable the use of data from monitoring studies to estimate 

concentrations and potential risks under a wide range of conditions and use patterns. 

EPA used the Version 2.1.4 of the Probabilistic Exposure and Risk model for Fumigants 
22

(also called the PERFUM model), to evaluate potential risks at distances around treated 

fields. PERFUM incorporates actual weather data and flux distribution estimates, then 

accounts for changes and altering conditions. Analyses based on a variety of model 

outputs were used to compare the potential risks at a range of distances. The PERFUM 

model and users manual are public domain and can be downloaded at 

http://www.exponent.com/perfum/. 

• Bystander, Handler, and Worker Incident Reports: Exposure incidents for the soil 

fumigants generally occur at a low frequency relative to the total number of fumigant 

applications performed annually. However, when fumigant incidents occur, there are 

often many people involved. Incidents involving workers tend to occur more often than 

incidents with bystanders. 

Reconstructing incidents to examine the exact factors that led to the incident can be 

difficult, especially when bystanders are involved, since all the factors that contributed to the 

incident may not have been documented. Some of the factors that have been linked to incidents 

in the past have included equipment failure, handler accidents, applicator failure to adhere to 

label recommendations and/or requirements, and temperature inversions. Incidents have 

occurred to bystanders close to fields and up to two miles away from the fumigated field. 

Based on these lines of evidence, and as described in more detail in the risk assessments, 

EPA has determined that metam-sodium and metam-potassium risks to handlers, workers, and 

bystanders are of concern given current labels and use practices. The human health risk 

assessments indicate that inhalation exposures to bystanders who live and work near agricultural 

fields and greenhouses where metam-sodium and metam-potassium soil fumigations occur have 

the potential to exceed the Agency’s level of concern without additional mitigation measures. 

There are also risks of concern for occupational handlers involved in metam-sodium and metampotassium applications and tarp perforation/removal activities and for workers who may re-enter 

the treated area shortly after fumigation or tarp perforation has been completed. 

For more information about the specific information in the Agency’s human health risk 

analyses, the documents listed below are relevant and available in the metam-potassium docket 

(EPA-HQ-OPP-2005-0125) at www.regulations.gov. 

• Methyl Bromide, 1,3-Dichloropropene, Chloropicrin, Dazomet, Metam 

Sodium/Potassium, MITC: Health Effects Division (HED) Component of Agency 

Response To Comments On 2008 Reregistration Eligibility Documents. May 14, 

2009.

• EPA-HQ-OPP-2005-0125-0269, Metam-sodium: Final Revised Chapter of the 

Registration Eligibility Decision Document (RED); DP Barcode: D293354, Metamsodium PC Code: 039003, Metam-potassium PC Code: 039002, MITC PC Code 

068103. June 24, 2008.
23

• EPA-HQ-OPP-2005-0125-0261, Mode of Action, Eye Irritation, and the IntraSpecies Factor: Comparison of Chloropicrin and MITC. (Lowit, A. and Reaves, E.). 

May 27, 2008. 

• EPA-HQ-OPP-2005-0125-0074, Review of Fumigants Group Incident Reports 

• EPA-HQ-OPP-2005-0125-0075, Summary Fumigants Group Incident Reports 

• EPA-HQ-OPP-2005-0125-0103, Summary of Fumigants Group Incident and Other 

Data 

• EPA-HQ-OPP-2005-0125-0005, Metam-sodium Bystander Risk Assessment Report 

• EPA-HQ-OPP-2004-0159-0106, Revised Metam-sodium: Occupational and 

Residential Exposure Assessment for the Reregistration Eligibility Decision 

Document. (PC Codes 039003 and 068103; DP Barcode D293328) 

 2. Environmental Fate, Ecological Effects and Risks 

The Agency’s environmental fate and ecological effects risk assessments indicate that 

there may be some concerns for non-target organisms that may be exposed to metam-sodium and 

potassium. 

Metam-sodium and potassium degrade rapidly in soil to generate MITC, the volatile 

biocidal active product. Once MITC volatilizes into the atmosphere, it degrades rapidly due to 

direct photolysis. The primary concern for metam-sodium is the potential for acute exposure of 

terrestrial and aquatic organisms to MITC. Exposure to terrestrial organism such as birds and 

mammals to MITC would likely occur by the inhalation route. Potential exposure to aquatic 

organisms may occur from surface runoff/leaching and drift (wind) of MITC. 

Hazard 

Metam-sodium is considered moderately toxic on an acute oral basis to birds (LD50 = 211 

mg/kg). MITC is considered highly toxic on an acute oral basis to mammals (LD50 = 55 mg/kg), 

and moderately toxic via the inhalation route. Acute inhalation toxicity data with MITC are not 

available for birds. 

 

MITC is considered very highly toxic to both fish (lowest LC50 = 51.2 ppb) and aquatic 

invertebrates (lowest LC50 = 55 ppb). 

Exposure 

Terrestrial 

 

 Exposure of MITC to terrestrial animals was evaluated using the Industrial Source 

Complex Short Term (ISCST3) model together with information about MITC emissions from a 

treated field, taking into account the range of MITC concentrations which might be found under 

different conditions of application rate, weather, source size and shape (e.g., field size in acres) 

and distance from the treated field. 
24

Aquatic 

For MITC exposure to fish and aquatic invertebrates, EPA considers surface water only, 

since most aquatic organisms are not found in ground water. The aquatic exposure assessment 

for MITC relied on Tier II aquatic models. The Pesticide Root Zone Model (PRZM version 

3.1.2 beta) simulates fate and transport on the agricultural field, while the water body is 

simulated with Exposure Analysis Modeling System (EXAMS version 2.98.04). Simulations are 

run for multiple (usually 30) years and the reported estimated environmental concentrations 

(EECs) represent the values that are expected once every ten years based on the thirty years of 

daily values generated during the simulation for selected scenarios. 

PRZM/EXAMS simulates a 10 hectare (ha) field immediately adjacent to a 1 ha pond, 2 

meters deep with no outlet. The location of the field is specific to the crop being simulated using 

site-specific information on the soils, weather, cropping, and management factors associated with 

the scenario. The crop/location scenario in a specific state is intended to represent a high-end 

vulnerable site on which the crop is normally grown. Based on historical rainfall patterns, the 

pond receives multiple runoff events during the years simulated. PRZM has limited capabilities 

in capturing the amount of a volatile chemical in air, water, and sediment. The estimated 

concentrations of chemicals like MITC in surface water bodies may be upper bound. 

To simulate field application of metam-sodium, multiple scenarios were selected 

representing metam usage areas based on geography and weather. PRZM and EXAMS models 

are relevant scenarios were used to estimate MITC EECs in surface water based on label 

information for metam-sodium application to onions, turf, tomatoes, and potatoes at the highest 

application rate. 

Risk 

Terrestrial Risk 

A refined analysis using mammal inhalation data and both monitoring and modeling data 

for air concentrations of MITC do not indicate an acute risk of concern for wild mammals. 

Avian acute toxicity data via the inhalation route are needed to evaluate risk to birds. 

Risk to Plants

There is some uncertainty associated with risk of MITC to non-target plants, given the 

data gaps for guideline terrestrial plant toxicity data and an incomplete aquatic plant toxicity 

database. However based on the labeled phytotoxicity of MITC and some incidents, it is 

expected that at lease some non-target terrestrial plants off site may be at risk from off-gassed 

MITC. 

Aquatic Risk 
25

Acute aquatic levels of concern (LOCs) are slightly exceeded for MITC for both aquatic 

invertebrates [risk quotients (RQs) range from 0.15 to 0.64] and fish (RQs range 0.16 to 0.69). 

However, chronic exposure to MITC is expected to be low because of its high potential to 

volatilize from surface water bodies. 

Due to the current data gaps for MITC, the Agency is requiring additional eco-toxicity 

studies for both terrestrial and aquatic organisms. 

 

For more information on the Agency’s environmental fate and ecological effects risk 

analysis, refer to the document listed below: 

• EPA-HQ-OPP-2004-0159-0118, Revised Environmental Fate and Ecological Effects 

Risk Assessment for Metam-sodium and Metam-potassium. (PC Codes 039003 and 

039002; DP Barcode D293339). 

3. Benefits 

Soil fumigation can provide benefits to both food consumers and growers. For 

consumers it means more fresh fruits and vegetables can be cheaply produced domestically yearround because severe pest problems can be efficiently controlled. Benefits to crop production 

from metam-sodium and metam-potassium use accrue either from superior pest control (e.g., 

tomatoes) or lower production costs (e.g., carrots, onions, peanuts), or both (e.g., cucurbits, 

peppers, potatoes), as compared to the next best alternative. Commercially feasible alternatives 

frequently include other soil fumigants such as chloropicrin and 1,3-dichloropropene (or 

mixtures of both). However, feasibility of using 1,3-dichloropropene as an alternative is limited 

in California, a major usage region for metam-sodium and metam-potassium, due to local 

township caps on annual amounts permitted for use across all crops. Alternatives that may 

become commercially viable in the longer term include dimethyl disulfide (DMDS) and 

iodomethane, both in combination with chloropicrin. However, in the context of high metam-use 

sites, these materials are relevant only to cucurbits, peppers, and tomatoes, since these are the 

only metam-using crops for which registration of either chemical has been approved or is 

currently under consideration. 

The table below (Table 4) summarizes some aspects of the importance of metam-sodium 

and metam-potassium to crop production in all crops for which benefits assessments were 

conducted by the Agency and these have not changed from the assessments included as part of 

the July 2008 RED. For further details, the reader is referred to the impact assessments, carried 

out by the Biological and Economic Assessment Division (BEAD), which are available in the 

metam-sodium and metam-potassium docket (EPA-HQ-OPP-2005-0125) at 

www.regulations.gov. 

The economic benefits provided by metam-sodium and metam-potassium use in many of 

the crops are estimated to be substantial. For example, in potatoes, without metam, growers 
26

would likely switch to fumigation with 1,3-dichloropropene and chloropicrin, which is less 

effective at controlling key soil pests and more costly. BEAD estimates that net operating 

revenue, the difference between gross revenue and operating costs, would drop about 20% in 

California and by about 85% in the Pacific Northwest. Net operating revenue is a rough measure 

of grower income; it does not account for fixed costs of production. The annual regional 

economic value of metam-sodium and metam-potassium fumigation is estimated to be about $8 

million per year in California and about $48 million per year in the Pacific Northwest. 

Taken together, benefits analyses indicate that metam-sodium and metam-potassium use 

is generally important in a variety of crops, and that if these fumigants could not be used, there 

would likely be significant negative economic impacts. 

Table 4. Summary of benefits to crop production from metam-sodium & metampotassium 

Crop Likely Alternatives 

to Metam 

Predicted impacts of loss of Metam-sodium and Metam-potassium use 

Carrots 1,3-D (with and 

without 

chloropicrin), plus 

various herbicides 

and fungicides to a 

much lower extent. 

BEAD estimates the benefit of metam-sodium in California carrot 

production to be about $3.5 million annually resulting from reduced 

production costs compared to fumigation with 1,3-dichloropropene and 

applications of other herbicides and fungicides. However, 1,3-

dichloropropene is subject to regulatory restrictions in California that may 

limit its availability for use by carrot growers. If 1,3-dichloropropene were 

not available to California growers, the benefits of metam-sodium could be 

as much as $140 million. In California, net operating revenue (NOR) could 

drop by 17 % if the likely alternative replaces metam-sodium. In 

Washington, the drop in NOR is estimated at 26%. 

Cucurbits 1,3-D (with and 

without 

chloropicrin), plus 

various herbicides 

and fungicides 

Use of metam-sodium to control fungi and nematodes leads to improved 

yields over fumigation with 1,3-dichloropropene and chloropicrin and 

substantially reduces production costs, which makes cucurbit production 

viable in infested areas. The total benefit of fumigating with metamsodium is about $100 million annually in gross production. NOR for 

California growers drops by as much as 177% if metam is replaced with 

the likely alternatives.

Eggplant 1,3-D (with and 

without chloropicrin) 

The benefits of metam-sodium include higher yields and lower costs 

compared to fumigation with 1,3-dichloropropene and chloropicrin. 

Benefits range from $290-1,080/acre. The total contribution of metamsodium to California eggplant production is between $72,500 and $270,000 

annually. 

Grapes – 

vineyard replant 

1,3-D (with and 

without 

chloropicrin), 

Metam-sodium appears to be the preferred fumigant for vineyards in 

Washington and Oregon, saving growers $25-50/acre over fumigation with 

1,3-dichloropropene and chloropicrin. For the region, savings range from 

$16,500-33,000 annually. Metam-sodium may also benefit producers 

through improved yields over 1,3-dichloropropene alone. 

Nursery stock 

(fruit seedlings 

and roses) 

 Metam-sodium is used in nursery stock production throughout the U.S., 

however, few data are available to permit reliable estimates of area treated 

or quantity of fumigant used. Soil fumigation in nursery production 

controls diseases, nematodes and weeds and results in higher yields, higher 

quality plant production, and lower costs of production. Because of the 

great diversity of plants and production conditions and a general lack of 

data, BEAD has not been able to quantify the benefits, but they extend 

beyond producers to include consumers of nursery products and multiply 
27

Crop Likely Alternatives 

to Metam 

Predicted impacts of loss of Metam-sodium and Metam-potassium use 

considerably throughout the various production chains. 

Onions 1,3-D (with and 

without 

chloropicrin), plus 

various herbicides 

and fungicides 

Metam-sodium is about $34/acre less expensive than 1,3-dichloropropene 

and chloropicrin in the production of storage onions in Washington and 

Oregon, providing costs savings for the region ranging from $393,000 to 

$537,000 annually. 

Ornamentals 

(floriculture 

only) 

Methyl bromide + 

chloropicrin, 1,3-D 

(with and without 

chloropicrin), plus 

various herbicides 

and fungicides 

There is ample evidence of that fumigant use increases yield and quality 

and lowers production costs. Variations in pests and conditions suggest that 

yield and quality differences would be significant and that metam-sodium 

plays a critical role. This is especially significant for the propagative sector 

because changes in the supply of seedling stock would result in magnified 

changes to future supplies of mature plants and their products. 

Peanuts 1,3-D (with and 

without 

chloropicrin), 

aldicarb 

The benefits of metam-sodium in peanut production are largely seen in the 

North Carolina and Virginia areas. NOR for these growers drops by 7% if 

1,3D+Chloropicrin replaces metam; NOR drops by about 60% if aldicarb 

is the replacement. 

Peppers 1,3-D (with and 

without 

chloropicrin), plus 

various herbicides 

and fungicides 

Metam-Sodium, and to a lesser extent metam-potassium, improves yields 

and saves on production costs compared to fumigation with 1,3-

dichloropropene and chloropicrin. Use of metam-sodium makes pepper 

production viable on much of the 1,500 acres in pepper production in 

California. Total benefits range from $0.5-33.1 million annually. NOR for 

California growers drops by 15 to 51% if metam is replaced with the likely 

alternatives. 

Pome fruit 

(apples and 

pears) – orchard 

replant 

1,3-D (with and 

without 

chloropicrin), 

Orchards are fumigated at replanting to decrease mortality of young trees, 

improve growth and speed maturation, and increase yields throughout the 

lifespan of orchards. While 1,3-dichloropropene and chloropicrin are used 

more often, on appropriate soils, metam-sodium is often less expensive. In 

the absence of chloropicrin, metam-sodium would result in improved 

yields, valued at $92.8 million/year, over use of 1,3-dichloropropene alone. 

Some portion of the estimated benefits is passed along to consumers. 

Potatoes 1,3-D (+ 

chloropicrin). 

Approx. 13 % yield 

loss expected with 

1,3-D+Chloropricrin 

his alternative 

The benefits of metam-sodium include yield increases and lower 

production costs. Overall, the annual benefits of metam-sodium are 

estimated to be about $800 per acre in California, and about $250 per acre 

in the PNW, which translates to benefits of about $8 million per year in 

California, and about $48 million per year in the Pacific Northwest. At the 

farm level, in California, NOR would drop by 20% and in the PNW, by 

85% if metam is replaced by the likely alternatives. 

Stone fruit 

(apricot, cherry, 

nectarine, 

peach, plum 

and prune) 

1,3-D (with and 

without 

chloropicrin), 

probably to a lesser 

extent methyl 

bromide + 

chloropicrin 

As with pome fruit, orchards are fumigated prior to replanting to better 

establish new trees, increase survival rates, improve growth and enhance 

maturity, and increase yields throughout the lifespan of the orchard. On 

appropriate soils, metam-sodium provides cost savings of about $60/acre 

over 1,3-dichloropropene and chloropicrin. 

Sweet potatoes 1,3-D (with and 

without 

chloropicrin), plus 

various herbicides 

and fungicides 

Without metam-sodium, production of sweet potato would not be viable on 

nearly 10% of California fields. The benefits of metam-sodium amount to 

about $5.9 million in sweet potato production annually 

Tomatoes 1,3-D (with and 

without 

Metam-sodium provides more complete control of pests than does 1,3-

dichloropropene and chloropicrin, which results in improved yields and 
28

Crop Likely Alternatives 

to Metam 

Predicted impacts of loss of Metam-sodium and Metam-potassium use 

chloropicrin), plus 

various herbicides 

and fungicides; 

methyl bromide + 

chloropicrin (fresh 

tomatoes only) 

increased revenue of nearly $130/acre. This represents an annual value for 

metam-sodium of about $7.3 million in California. Major use is in 

processed tomato production in California. NOR for these growers drops 

by about 13% if likely alternatives replace metam-sodium. 

Note: As part of the response to public comments received on the REDs, the Agency reviewed 

the need for metam registration in the context of certain specialized situations (such as cover 

crops), and for specific minor crops (such as seed crops) and concluded that benefits of metam 

use there were important enough to warrant re-registration. This review is available in the BEAD 

memo titled “Response to comments on use site restrictions included in the Reregistration 

Eligibility Decision (RED) for Metam-Sodium and Metam-Potassium (DP # 363544)”. This 

topic is also discussed earlier in this document in the section titled “Rate Reduction and Use 

Sites”. 

There are a number of benefits assessments that have been completed by the Agency to 

estimate the value of these chemicals to various industries, which are listed below. 

• EPA-HQ-OPP-2005-0123-0321, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin, Metam-Sodium, and Methyl Bromide in Eggplant Production 

• EPA-HQ-OPP-2005-0123-0322, Assessment of the Benefits Soil Fumigants (Methyl 

Bromide, Chloropicrin, Metam-Sodium, Dazomet) Used by Forest Tree Seedling 

Nurseries 

• EPA-HQ-OPP-2005-0123-0323, Assessment of the Benefits of Soil Fumigation with 

Methyl Bromide, Chloropicrin, Dazomet, Metam Potassium and Metam Sodium for Use 

in Raspberry Nurseries, Fruit and Nut Deciduous Tree Nurseries, and Rose Bush 

Nurseries in California 

• EPA-HQ-OPP-2005-0123-0324, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin and Metam-sodium In Onion Production 

• EPA-HQ-OPP-2005-0123-0325, Assessment of the Benefits of Soil Fumigation with 

Methyl Bromide, Chloropicrin and Metam-sodium In Grape Production 

• EPA-HQ-OPP-2005-0123-0326, Assessment of the Benefits of Soil Fumigation with 

Methyl Bromide, Chloropicrin and Metam-sodium In Tree Nut Production 

• EPA-HQ-OPP-2005-0123-0327, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin, and Methyl Bromide In Pome Fruit Production 

• EPA-HQ-OPP-2005-0123-0328, Assessment of the Benefits of Soil Fumigation with 

Methyl Bromide, Chloropicrin, and Metam Sodium In Stone Fruit Production 

• EPA-HQ-OPP-2005-0123-0329, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin, Methyl Bromide, and Metam-Sodium in Bell Pepper Production 

• EPA-HQ-OPP-2005-0123-0330, Assessment of the Benefits of Soil Fumigation with 

Metam-sodium in Potato Production 
29

• EPA-HQ-OPP-2005-0123-0331, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin, Methyl Bromide, and Metam-sodium In Strawberry Production 

• EPA-HQ-OPP-2005-0123-0332, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin, Methyl Bromide, Metam-sodium, and Dazomet In Strawberry Nursery 

Runner Production 

• EPA-HQ-OPP-2005-0123-0333, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin, Methyl Bromide and Metam-sodium In Sweet Potato Production 

• EPA-HQ-OPP-2005-0123-0334, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin In Tobacco Production 

• EPA-HQ-OPP-2005-0123-0335, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin, Methyl Bromide, and Metam-sodium in Tomato Production 

• EPA-HQ-OPP-2005-0123-0336, Assessment of the Benefits of Soil Fumigation with 

Metam Sodium in Carrot Production 

• EPA-HQ-OPP-2005-0123-0337, Assessment of the Benefits of Soil Fumigation with 

Metam Sodium in Peanut Production 

• EPA-HQ-OPP-2005-0123-0338, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin, Methyl Bromide, Metam Sodium and Dazomet in Ornamental Production 

• EPA-HQ-OPP-2005-0123-0339, Summary of the Benefits of Soil Fumigation with 

Methyl Bromide in Crop Production 

• EPA-HQ-OPP-2005-0123-0340, BEAD's Planned Impact Assessments on Agricultural 

Sites with Significant Use of Soil Fumigants 

• Analysis of Soil Fumigant Risk Management Requirements using Geographic 

Information Systems: Case Studies based on a Forest Seedling Nursery (DP# 363546) 

4. 2008 RED Mitigation Impacts 

Requirements in the July 2008 RED

The July 2008 RED acknowledged that even with the use of credits, there could be 

significant economic impacts to some growers who may not be able to accommodate large 

buffers based on their current application practices. However, the Agency believed that the 

options provided in the scalable buffer approach in the fumigant REDs would allow growers the 

flexibility to modify their practices to achieve smaller buffers; for example, by treating smaller 

application blocks, switching to a lower emission application method, or by switching to an 

alternative fumigant that would require smaller buffers. Therefore, the Agency concluded that 

growers would be able to alter their fumigation applications, given the flexibility designed into 

the system, in a manner that would enable growers to minimize the impact on production. The 

Agency noted, however, that the buffers would significantly impact some growers by delays in 

planting due to longer fumigation operations, additional planning, and more trips to the field for 

planting and other operations if fumigating in smaller blocks resulted in staggered operations. It 

was determined that some of these costs could be substantial in some production scenarios. 

Comments on the July 2008 RED
30

 The July 2008 RED requested commenters to submit a description of fumigation 

practices and provide maps of their property illustrating locations of fields, offices, residences, 

roads, and property lines so that the Agency could better understand the impacts of the mitigation 

plan. In response, various stakeholders, including several forest seedling nursery operations, 

submitted detailed information. From an analysis of the information submitted, including an 

analysis of a nursery and options they would have for compliance, the Agency concludes that it 

had overestimated the ease with which many growers and fumigators would be able to comply 

with the buffer requirements as presented in the July 2008 RED, and that potential impacts 

would be much greater than previously anticipated for some types of production. 

From the Agency’s analysis, the primary driver of the impacts is the size of the buffer 

zones, which will require many growers to divide their fields into smaller fumigation blocks to 

achieve smaller buffer zone distances. Two other contributing factors are the prohibition on 

buffers overlapping in space and time and the duration of the buffer zone. As discussed above, 

the Agency has provided flexibility on overlapping buffers. Nevertheless, the analysis indicates 

that the buffer system identified in the July 2008 RED can be less flexible than expected for 

certain scenarios, and the associated field topography, field infrastructure, and need for a 

consistent orientation in the application of a fumigant, constrain how a field may be divided. 

Together, these requirements could result in the loss of part of a grower’s field that can be 

effectively fumigated. Further, there may be substantial delays in completing fumigations and 

multiple trips to a field with fumigation equipment may often be necessary. Not only could there 

be delays in production activities in these instances, but it may also be difficult to maintain 

proper soil moisture over the period that multiple blocks would be fumigated. Soil moisture has 

been identified as a critical element in controlling emissions. Some growers will face numerous 

scheduling conflicts if they rely on commercial applicators, and the Agency estimates that 

growers would be more likely to conduct their own fumigations. In addition, repeated trips to 

the field to fumigate small blocks will increase costs, a further incentive for growers to conduct 

their own fumigations. 

The Agency does agree that compliance with buffer zone requirements as outlined in the 

July 2008 RED would be a significant challenge for applicators and growers. However, field 

flux studies, monitoring data, modeling analyses and information from incidents involving 

fumigants continues to support a conclusion that metam-sodium and metam-potassium off-gasses 

and moves away from treated fields at concentrations that have the potential to cause adverse 

effects. Therefore, the Agency still believes that buffer zones that exclude bystanders are a 

critical aspect of mitigating risks from metam-sodium and metam-potassium. 

In addition to these impacts, if emergency preparedness and response requirements were 

triggered due to proximity of neighbors, for example, the requirement in the July 2008 RED to 

monitor the buffer zone for its duration was estimated to impose the highest direct costs. The 

Agency estimates that the cost of sampling tubes alone could range from $1000 to over $3000 

for a field or enterprise, not including the cost of labor. These costs would fall 

disproportionately on growers with small acreage. As an alternative, growers could notify their 

neighbors of their intent to fumigate. However, the Agency understands and appreciates the 
31

many comments indicating that notification may not be an attractive option due to the potential 

for neighbors to attempt to impede or block fumigant applications. 

Finally, the Agency concludes that the development and implementation of workable 

fumigation strategies, considering buffer and other requirements, will require substantial new 

information and management skills on the part of growers and applicators. While the Agency’s 

risk management approach provides flexibility to the grower, providing a reasonable period of 

time for growers to adapt would reduce impacts. 

Based on this new information and EPA’s analyses, the Agency has identified 

modifications to the mitigation which will maintain the important protections necessary for the 

health and safety of workers and bystanders, but will increase the ability of fumigant users to 

comply by reducing impacts associated with the mitigation. This includes allowing buffer zone 

overlap and changes in monitoring requirements. In addition, due to new data that have been 

submitted to the Agency, buffer zones distances for some scenarios have been refined. Although 

many aspects of the RED mitigation will appear on labels in 2010, the Agency will not require 

buffers until the 2011 growing season. 

B. Overview of Sewer Use Risk 

Because metam-sodium degrades rather quickly to MITC, short-term, intermediate-term, 

and chronic inhalation exposures to metam-sodium by workers are expected to be negligible 

when compared with MITC exposures. To address the short- and intermediate-term MITC 

inhalation risks from MITC, in the July 2008 metam-sodium metam-potassium RED, the Agency 

required that any person(s) engaged in any activities that are likely to involve direct contact with 

metam-sodium (including, but not limited to, mixing, loading, and/or applying metam-sodium; 

equipment calibration; cleaning and repair of application equipment; entering into treated areas; 

sampling cleanup spills; and rinsate disposal) wear a respirator. The Agency is requiring a 

NIOSH-approved full-face respirator with organic vapor cartridge. 

While there is insufficient toxicological data to characterize the inhalation cancer risk of 

MITC, due to limitations in the rat and mouse MITC oral carcinogenicity studies, the Agency 

anticipates that these new respiratory requirements will adequately address this risk. However, 

the Agency is requiring additional study data for MITC. 

The Agency revised the non-cancer, short- and intermediate-term occupational handler 

dermal exposure assessments based on the additional usage and occupational exposure 

information provided by the metam-sodium sewer use registrants. The results of the revised noncancer, short-term occupational handler dermal exposure assessments for the sewer use of 

metam-sodium indicate that the MOEs for the dermal risk to handlers with engineering controls 

(e.g., closed mixing and loading systems) were above or just below the target MOE of 100, and 

the MOEs for the dermal risk to handlers with full dermal PPE (i.e., chemical resistant gloves 

and double layer clothing) were above 49, even at the highest daily rates of amount of product 

handled. In the case of the intermediate-term exposures with full dermal PPE, MOEs were below 
32

the target MOE of 100, even with engineering controls. Although not all short- and 

intermediate-term dermal exposure MOEs reached the target MOE of 100 with the required 

dermal protection and engineering controls, the occupational handler dermal exposure 

assessments are considered to be very conservative. 

EPA revised its occupational handler dermal cancer assessment for handlers engaged in 

sewer applications of metam-sodium to control roots in sewer systems based on the additional 

usage and occupational exposure information provided by the metam-sodium sewer use 

registrants during the post-RED comment period. The results of the revised cancer occupational 

handler dermal exposure assessment for the sewer use of metam-sodium indicate that cancer 

risks for workers in full dermal PPE requirements (i.e., chemical resistant gloves and double 

layer clothing) and/or those using engineering control technologies (i.e., closed mixing and 

loading systems) are below the target cancer risk level of between 1x10-4 to 1x10-6 for exposed 

handlers. 

Based on the short- and intermediate-term dermal exposure risks to workers, coupled 

with the worker risks associated with MITC inhalation exposures, the Agency is requiring that 

any person(s) engaged in any activities that are likely to involve direct contact with metamsodium, including but not limited to applying metam-sodium; cleaning and repair of application 

equipment; entering into treated areas; sampling cleanup of spills; and rinsate disposal, to wear 

double-layer clothing, chemical resistant gloves, and at least a NIOSH-approved full-face 

respirator with organic vapor cartridge. The Agency is also requiring a closed engineering 

systems be used for all mixing and loading activities. 

For more information on the Agency’s sewer use risk analysis, refer to the documents 

listed below (all are available in the metam-sodium docket at www.regulations.gov): 

• “Metam Sodium: Third Revision of the HED Human Health Risk Assessment;” May 

2009; Charles Smith; Health Effects Division, U.S. EPA. 

C. Overview of Antimicrobial Risk 

Due to the short loading and/or application durations (i.e., minutes), handlers (i.e., 

mixers/loaders) are not expected to be exposed to the metam-sodium degradate, MITC. 

However, the Agency has concerns for potential post-application inhalation exposures to MITC 

after metam-sodium applications in the leather and/or sugar processing industries and also 

workers in the vicinity of sewage sludge treatments. The Agency also has concerns for potential 

post-application inhalation exposures to MITC for workers in the vicinity of metam-potassium 

applications in the leather, pulp/paper, and sugar processing industries as well as in coatings and 

metal working fluid manufacturing, oil-field operations, cooling water towers, and industrial 

water purification facilities because MITC is a highly volatile organic chemical (vapor pressure 

= 150 mmHg). Furthermore, since metam-sodium and metam-potassium convert to MITC in 

aqueous media, the Agency also has concerns for the potential MITC inhalation exposures for 

the machinist who works with metal-working fluids that were preserved with metam-potassium. 
33

For more information on the Agency’s antimicrobial use and industrial risk analysis, refer 

to the documents listed below (all are available in the metam-sodium docket at 

www.regulations.gov): 

• EPA-HQ-OPP-2005-0125-0264, Revised Occupational and Residential/Bystander Assessment of 

the Antimicrobial Use (Remedial Wood Treatment) of Chloropicrin for the Reregistration 

Eligibility Decision (RED) Document (Phase 3 Comment Period). PC Code 081501, DP 

Barcode D314399. February 14, 2008. 

• EPA-HQ-OPP-2005-0125-0076, Occupational and Residential/Bystander Assessment of the 

Antimicrobial Use (Remedial Wood Treatment) of Methyl Isothiocyanate (MITC) for the 

Reregistration Eligibility Decision (RED) Document

• EPA-HQ-OPP-2005-0125-0077, Metam-potassium: Dietary Risk Assessment of Antimicrobial 

Uses in Sugar Processing for the Reregistration Eligibility Decision Document

• EPA-HQ-OPP-2005-0125-0078, Metam-potassium: Occupational and Residential Exposure 

Assessment of Antimicrobial Uses for the Reregistration Eligibility Decision Document 

• EPA-HQ-OPP-2004-0159-0119, Metam-sodium: Revised Occupational and Residential 

Exposure Assessment of Antimicrobial Uses for the Reregistration Eligibility Decision 

Document. (PC Codes 039003 and 068103) 

• EPA-HQ-OPP-2004-0159-0006, Ecological Risk from Antimicrobial Uses of Metam-sodium to 

be Considered in the RED 

• EPA-HQ-OPP-2004-0159-0017, Metam-sodium: Dietary Risk Assessment of Antimicrobial 

Uses for the RED 

IV. Risk Management and Reregistration Eligibility Decision 

A. Determination of Reregistration Eligibility 

 Section 4(g)(2)(A) of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) 

calls for the Agency to determine, after submission of relevant data concerning an active 

ingredient, whether pesticides containing the active ingredient are eligible for reregistration. The 

Agency has previously identified and required the submission of the generic (i.e., active 

ingredient specific) data to support reregistration of products containing metam-sodium, metampotassium, and MITC. 

In Phase 5, the Agency published a risk mitigation options paper.1 This document detailed 

potential mitigation options and sought public comment on these options. The following is the 

list of mitigation options discussed in the Agency’s paper: 

• Buffer zones; 

• Sealing methods; 

 

1 EPA-HQ-OPP-2005-0128-0031, Risk Mitigation Options to Address Bystander and Occupational Exposures from 

Soil Fumigant Applications 
34

• Timing of applications; 

• Application block size limitations; 

• Respiratory protection; 

• Tarp perforation/removal procedures; 

• Entry-restricted period; 

• Application method/practice restrictions; 

• Fumigant management plans (FMPs); 

• FMP certification; 

• Responsible parties; 

• Record keeping/reporting/tracking; 

• Restricted Use Pesticide Classification; 

• Notification and posting; 

• Good agricultural practices; 

• Fumigant manuals; and 

• Stewardship programs. 

Based on a review of the metam-sodium, metam-potassium, and MITC 

databases and public comments on the Agency’s assessments for these active 

ingredients, the Agency has sufficient information on the human health and ecological 

effects of metam-sodium, metam-potassium, and MITC to make decisions as part of 

the reregistration process under FIFRA. Further, based on the volatility of metamsodium, metam-potassium, and MITC and metabolism studies in plants, EPA has 

concluded that there is a reasonable expectation that no residue on food or feed items 

will occur with the use of these fumigants. Therefore, no tolerances have been 

established. 

As a result of this review, the Agency has determined that certain uses of (1) metamsodium (including use as a pre-plant soil fumigant in certain crops, as a root control agent in 

sewers and drains, and as an antimicrobial agent to treat wood poles and timbers and sewage 

sludge and animal waste); (2) metam-potassium (including use as a pre-plant soil fumigant in 

certain crops and as an antimicrobial agent for treatment of pulp and paper, tanning drum leather 

applications, recirculating cooling water systems, and industrial water purification systems); and 

(3) MITC (for use as an antimicrobial agent to treat wood poles and pilings) are eligible for 

reregistration, provided that the risk mitigation measures outlined in this document are adopted, 

label amendments are made to reflect these measures (as outlines in Section V), and data are 

developed to assess intermediate- and long-term risk to bystanders. Appendix A summarizes the 

uses of metam-sodium, metam-potassium, and MITC that are eligible for reregistration. 

The Agency’s decision takes into account the best available information on the potential 

risks and benefits of metam use. In reaching its reregistration decision and developing the 

metam mitigation proposal, EPA considered a range of factors, including: characteristics of 

bystander and other populations exposed to metam; hazard characteristics of metam-sodium, 

metam-potassium, and MITC; available information on levels of exposure, feasibility, cost, and 
35

effectiveness of various risk mitigation options; incident information; public comments; potential 

impacts of mitigation on growers ability to produce crops; availability of efficacious alternatives; 

comparative risks of alternative control methods; and the uncertainties and assumptions 

underlying the risk and benefit assessments. 

Some uncertainty remains associated with intermediate- and long-term exposure and risk 

to bystanders. To address these uncertainties, EPA is requiring additional data related to both 

toxicity and exposure. Notwithstanding these uncertainties, the Agency has decided to proceed 

with its reregistration decision and implementation of mitigation at this time because mitigation 

implemented to address acute bystander risk will also serve to address intermediate- and longterm bystander risk. 

A substantial amount of research is currently underway or is expected to begin in the near 

term to (1) address current data gaps, and (2) refine understanding of factors that affect fumigant 

emissions. Additionally, a number of new methods and technologies for fumigation are 

emerging. To ensure that data are developed and reviewed expeditiously, EPA plans to move the 

soil fumigants forward in registration review, from 2017 to 2013, which will allow EPA to 

consider new data and information relatively soon, determine whether the mitigation included in 

this decision is effectively addressing the risks as EPA believes it will, and to include other soil 

fumigants which are not part of the current review. 

Voluntary Cancellation of Antimicrobial Uses 

On May 15, 2008, the Agency received letters voluntarily cancelling several 

antimicrobial uses for metam-sodium and metam-potassium. The antimicrobial uses of metamsodium that were cancelled included: (1) treatment of process waters during the production of 

sugar (i.e., raw cane and beet sugars) and (2) treatment of brine-cured hides and skins (i.e., 

leather) during processing. The antimicrobial uses of metam-potassium that were cancelled 

included: (1) the sugar beet and sugar cane use; (2) all leather uses, with the exception of the 

tanning drum leather use; (3) all paint uses (including the preservation of protective colloids and 

emulsion resins); (4) all water-based drilling, completion, and packer fluid uses; (5) all 

petroleum secondary recovery operation uses; (6) all once-through cooling water applications, 

and (7) all cutting fluids (metalworking fluids) uses. As a result of these cancellations, these uses 

have not been evaluated in the RED. 

The Agency has determined that the remaining registered antimicrobial uses for metamsodium (i.e., remedial treatment of wooden poles and timbers and treatment of sewage sludge 

and animal waste), metam-potassium (i.e., use in tanning drum leather, pulp and paper, 

recirculating cooling water systems, and industrial water purification systems), and MITC (i.e., 

remedial treatment of wooden poles and timbers) will not pose unreasonable risks or adverse 

effects to humans or the environment, provided that the risk mitigation measures and label 

changes outlined in this RED are implemented and, therefore, products containing metamsodium, metam-potassium, and MITC for these uses are eligible for reregistration. 
36

 Based on its evaluation of metam-sodium, metam-potassium, and MITC, the Agency has 

determined that products containing these chemicals, unless labeled and used as specified in this 

document, would present risks inconsistent with FIFRA. Accordingly, should a registrant fail to 

implement any of the risk mitigation measures identified in this document, the Agency may take 

regulatory action to address the risk concerns from the use of these chemicals. If all changes 

outlined in this document are incorporated into the product labels, then current risks for metamsodium, metam-potassium, and MITC will be adequately mitigated for the purposes of this 

determination under FIFRA. Once a comprehensive endangered species assessment is 

completed, further changes to these registrations may be necessary. 

B. Public Comments and Responses 

The Phase 3 public comment period on the preliminary risk assessments and related 

documents lasted from July 13 through October 12, 2005. The Agency responses to Phase 3 

public comments related to metam-sodium and metam-potassium soil uses, metam-sodium sewer 

use, and antimicrobial uses for metam-sodium, metam-potassium, and MITC can be found in the 

metam-sodium docket (EPA-HQ-OPP-2005-0125) at www.regulations.gov. 

 

EPA revised its risk assessments and developed benefits and risk mitigation options 

during Phase 4. The Phase 5 public comment period, for revised risk assessments, benefits 

analysis, and risk management options lasted from May 2 to November 3, 2007. The Agency 

responses to Phase 5 public comments related to metam-sodium and metam-potassium soil uses, 

metam-sodium sewer use, and antimicrobial uses for metam-sodium, metam-potassium, and 

MITC can be found in the following documents, available in the metam-sodium docket (EPAHQ-OPP-2005-0125) at www.regulations.gov.

• The Health Effects Division’s Response to Comments on EPA’s Phase 5 

Reregistration Eligibility Decision Document for Dazomet. (Smith, C., Dated June 

2008).

• Response to Phase 5 Public Comments on the Phase 4 Dazomet Environmental 

Fate and Ecological Risk Assessment. (Khan, F., and Felkel, J., Dated April 2, 

2008). 

• Response to Phase 5 BEAD Related Public Comments Received on the 

Reregistration of Chloropicrin, Dazomet, Metam Potassium, Metam Sodium, and 

Methyl Bromide. (Donaldson, D. et al., Dated June 2008). 

• Review of Stakeholder Submitted Impact Assessments of Proposed Fumigant 

Buffers, Comments on Initial Buffer Zone Proposal, and Case Studies of the Impact 

of a Flexible Buffer System for Managing By-Stander Risks of Fumigants. (Wyatt, 

T., et al, Dated June 2008). 

• Phase 6 Response to Substantive Public Comments on Antimicrobials Division’s 

Occupational and Residential Assessments for the Reregistration Eligibility 

Decision (RED) Documents for the following chemicals: Methylisothiocyanate 

(MITC), Metam Sodium, Dazomet, and Chloropicrin. (Walls, C., Dated February 

14, 2008).
37

• SRRD’s Response to Phase 5 Public Comments for the Soil Fumigants. (July 

2008).

The Agency also opened a 60-day public comment period following the publication of the 

Metam-Sodium and Metam-Potassium RED on July 16, 2008. The Agency received requests to 

extend the comment period, so in response to these requests, on August 29, 2008, EPA published 

a notice in the Federal Register extending the comment period for an additional 45 days. The 

comment period closed on October 30, 2008. The Agency has reviewed these public comments 

as well as new scientific data and other information provided and determined that all measures 

established in the July 2008 RED to reduce risks to bystanders and workers will still be required. 

The Agency has determined that certain modifications in how and when some measures will be 

implemented are appropriate. The following documents include EPA’s responses to comments 

on the July 2008 RED which may be found in the metam-sodium and metam-potassium docket: 

• Further Response to Public Comments on the 7/9/08 Completed Dazomet RED. 

(Dated March 3, 2009). 

• Methyl Bromide, 1,3-Dichloropropene, Chloropicrin, Dazomet, Metam 

Sodium/Potassium, MITC: Health Effects Division (HED) Component of Agency 

Response To Comments On 2008 Reregistration Eligibility Documents (Dated May 

14, 2009). 

• Response to BEAD Related Public Comments Received on the Reregistration 

Eligibility Decision for Chloropicrin, Dazomet, Metam Potassium, Metam Sodium, 

and Methyl Bromide (DP# 363545; Dated May 14., 2009).

• Analysis of Soil Fumigant Risk Management Requirements using Geographic 

Information Systems: Case Studies based on a Forest Seedling Nursery (DP# 

363546; Dated May 13, 2009). 

• SRRD’s Response to Post-RED Comments for the Soil Fumigants (Dated May 20, 

2009). 

C. Regulatory Position 

1. Regulatory Rationale 

The Agency has determined that products containing metam-sodium, metam-potassium, 

and MITC are eligible for reregistration provided the risk mitigation measures outlined in this 

document are adopted and label amendments are made to reflect these measures. EPA has 

determined that the modifications to the measures outlined in the July 2008 RED, described 

herein, will achieve the same protection goals for person’s potential exposed to metam-sodium 

and metam-potassium but with a greater likelihood of compliance, fewer impacts on the benefits 

of metam use, and with less uncertainty regarding the protectiveness of the required measures. 

The following is a description of the rationale for managing risks associated with the use of these 

fumigants. Where labeling revisions are warranted, specific language is set forth in the label 

table in Section V of this document.

a. Soil Fumigant Uses of Metam-sodium and Metam-potassium 
38

i. Rate Reduction and Use Sites 

While most current labels for metam-sodium and metam-potassium state that 320 lb ai/A 

is the maximum allowed rate, there are some labels which suggest that calculated rates may be 

higher than 320 lb ai/A. To consistently clarify the maximum application rates for pre-plant soil 

fumigation, label language will be required to specifically state 320 lb ai/A as the upper limit for 

all application methods. No other rate changes for soil fumigation uses are required in this 

decision. 

1. Use Sites Eligible for Reregistration 

In the July 2008 Metam-Sodium and Metam-Potassium RED, the Agency determined the 

following uses to be eligible for reregistration: asparagus (nursery production only), artichokes, 

broccoli, Brussels sprouts, cabbage, carrot, cauliflower, celery, cucurbits (cucumber, cantaloupe, 

honeydew, pumpkin, squash, and watermelon), eggplant, forest seedlings, grape (vineyard 

replant only), lettuce, mint, nursery stock (fruit seedlings and rose bushes only), oranges, onion, 

pome fruit (apples and pears; orchard replant only), stone fruit (apricot, cherry, nectarine, peach, 

plum and prune; orchard replant only), ornamentals (floriculture only), peanut, pepper, potato, 

spinach, strawberries, sweet potato, tobacco, tomatoes, and turf (including golf courses). 

This list of crops was based on one or more of the following criteria: (1) the crop showed 

significant usage of metam-sodium and metam-potassium, as indicated by BEAD usage data, 

and/or (2) stakeholders for the crop submitted compelling benefits information for metamsodium and metam-potassium use during the Phase 5 comment period, and/or (3) removal of 

metam-sodium and metam-potassium use appeared likely to increase use of methyl bromide, 

which is being phased out under the Montréal Protocol. “Significant usage” was defined as a 

crop that has more than 5% crop treated annually or more than 1,000,000 lb of metam sodium or 

metam potassium applied annually. 

All other pre-plant uses were to be deleted, unless additional information to support a 

compelling case for the economic benefits of metam-sodium and metam-potassium was 

provided. This decision was based on potentially high risk to bystanders from metam-sodium and 

metam-potassium, coupled with a lack of indication of high economic benefits for crops not 

included in the group described above. 

During the post-RED comment period, the Agency received comments from various 

stakeholders asking that the Agency consider the eligibility of additional use sites. Key 

considerations identified during the post-RED comment period included: 

• Crops that are typically included as part of a rotational schedule or cover crop regimen. The 

Agency agrees that limiting the use metam-sodium and metam-potassium may have some 

unintended consequences. These include preventing good soil erosion management (with 

cover crops), and magnifying the negative economic impact on growers who have to alter 
39

their crop rotation scheme unexpectedly due to, for example, changes in weather conditions 

or economic considerations, such as contractual agreements with processors. As a result, the 

following crops, which have been reported to be part of typical rotational schedules for 

metam users, will be added as eligible use sites: alfalfa, barley, rye, sugar beets, corn, and 

wheat. In addition, the Agency will add “cover crops,” i.e., crops planted between periods of 

regular crop production to prevent soil erosion, control weeds, and improve soil quality that 

are incorporated into the soil before the next crop is planted and may not be harvested for 

food or feed, to the list of eligible use sites for metam-sodium and metam-potassium. 

• Use of metam-sodium and metam-potassium as a potential alternative to methyl bromide for 

orchard replant of tree nuts, berry crops, ginger, and pineapple. The Agency analyzed the use 

of soil fumigants for orchard replant of tree nut crops, berry crops (i.e., blueberry, blackberry, 

raspberry, etc.), ginger, and pineapple and determined that restriction of these uses of metamsodium and metam-potassium are likely to lead to an increased reliance on methyl bromide. 

As a result, orchard replant of tree nuts, berry crops, ginger, and pineapple have been added 

as eligible use sites for metam-sodium and metam-potassium. 

• Metam-sodium and metam-potassium use on minor crops. The Agency received comments 

from stakeholders asking that several minor uses (e.g., arugula, wild rocket, and parsley; 

grapefruit) of metam-sodium and metam-potassium be considered eligible. While such minor 

crop uses might not reach the threshold of “significant usage,” in cases where the crops 

mentioned were likely to be similar to others that were retained for reregistration, in terms of 

the pest management needs and crop production benefits, the Agency made sure to evaluate 

those uses for eligibility in the RED addendum. Specifically, the Agency is including several 

of the EPA crop group listings as eligible use sites to provide growers additional flexibility 

with regard to use site eligibility [for a description of these crop groups, see “Pesticide 

Tolerances; Revision of Crop Groups, Final Rule, Federal Register Notice, May 17, 1995 

(Volume 60, Number 95); http://www.epa.gov/fedrgstr/EPA-PEST/1995/May/Day-17/pr266.html]. As an example, by including “EPA Crop Group 4, Leafy Vegetables” as an eligible 

use site, arugula, wild rocket, parsley and a number of other potential minor uses, which are 

similar to lettuce and spinach in terms of the pest management needs and crop production 

benefits, become eligible use sites. Further, the Agency is adding “crops grown solely for 

seed” to the list of eligible use sites, because information from growers and extension agents 

indicates that, while a minor use, use of soil fumigants on seed crops is important for control 

of weeds and disease. 

• California Department of Pesticide Regulation usage data. In responding to the post-RED 

comments, the Agency examined the California Department of Pesticides (CDPR) pesticide 

usage data for recent years (2003-2006), since the state generally is a significant user of 

metam-sodium and metam-potassium products and is a major producer of a diverse array of 

crops that may rely on soil fumigation, to ensure that it did not miss any important uses of 

metam. Based on these data, it appears that there are few crops not already deemed eligible 

for reregistration that do not meet the criterion of 5% or more of the crop acreage treated 

annually. Only seven additional crops, including sweet basil, Chinese greens (often a 
40

synonym for bok choy), celeriac (a member of the celery family), collard, dill, leeks, and 

Swiss chard, were identified as having 5% or more of the crop treated in at least one year 

during the time period studied. Based on this analysis, the Agency is adding these seven 

additional to the list of eligible use sites for metam-sodium and metam-potassium. 

Based on the original criteria for determining eligible use sites (see above) as well as the 

comments and additional information received during the post-RED comment period, the EPA 

has determined that the following expanded list of metam-sodium and metam-potassium use sites 

are eligible for reregistration. All other pre-plant uses are to be deleted, and product labels must 

be amended to reflect use only on the crops specified as eligible for reregistration. 

 

• Alfalfa, 

• Asparagus (nursery production only), 

• Artichokes, 

• Barley, 

• Basil, 

• Beet, 

• Berries, [includes all EPA Crop Group 13, Berries Group, i.e., blackberry (Rubus eubatus); 

bingleberry; black satin berry; boysenberry; Cherokee blackberry; chesterberry; Cheyenne 

blackberry; coryberry; darrowberry; dewberry; Dirksen thornless berry; Himalayaberry; hullberry; 

lavacaberry; lowberry; lucretiaberry; mammoth blackberry; marionberry; nectarberry; olallieberry; 

Oregon evergreen berry; phenomenalberry; rangeberry; ravenberry; rossberry; Shawnee blackberry; 

youngberry, and varieties and/or hybrids of these; blueberry (Vaccinium spp.); currant (Ribes spp.); 

elderberry (Sambucus spp.); gooseberry (Ribes spp.); huckleberry (Gaylussacia spp.); loganberry 

(Rubus loganobaccus); raspberry-black and red (Rubus occidentalis, Rubus strigosus, Rubus idaeus)], 

• Broccoli, 

• Brussels sprouts, 

• Cabbage, 

• Carrot, 

• Cauliflower, 

• Celeriac, 

• Chinese greens or bok choy, 

• Cilantro, 

• Citrus (orchard replant only), [includes all of EPA Crop Group 10, Citrus Fruits, i.e., calamondin 

(Citrus mitis X Citrofortunella mitis); citrus citron (Citrus medica); citrus hybrids (Citrus spp.) 

(includes: chironja, tangelo, tangor); grapefruit (Citrus paradisi); kumquat (Fortunella spp.); lemon 

(Citrus jambhiri, Citrus limon); lime (Citrus aurantiifolia); mandarin (tangerine) (Citrus reticulata); 

orange, sour (Citrus aurantium); orange, sweet (Citrus sinensis); pummelo (Citrus grandis, Citrus 

maxima); satsuma mandarin (Citrus unshiu)], 

• Collard, 

• Corn, 

• Cover crops (i.e., crops planted between periods of regular crop production to prevent soil erosion, 

control weeds, and improve soil quality that are incorporated into the soil before the next crop is 

planted and may not be harvested for food or feed), 

• Crops grown solely for seed, 
41

• Cucurbits [includes all of EPA Crop Group 9, Cucurbit Vegetables Group, i.e., chayote (fruit) 

(Sechium edule); Chinese waxgourd (Chinese preserving melon) (Benincasa hispida); citron melon 

(Citrullus lanatus var. citroides); cucumber (Cucumis sativus); gherkin (Cucumis anguria); gourd, 

edible (Lagenaria spp.) [includes: hyotan, cucuzza (Luffa acutangula, L. cylindrical; includes 

hechima, Chinese okra)]; Momordica spp. (includes balsam apple, balsam pear, bitter melon, Chinese 

cucumber); muskmelon [hybrids and/or cultivars of Cucumis melo (includes true cantaloupe, 

cantaloupe, casaba, crenshaw melon, golden pershaw melon, honeydew melon, honey balls, mango 

melon, Persian melon, pineapple melon, Santa Claus melon, and snake melon)]; pumpkin (Cucurbita 

spp.); squash, summer (Cucurbita pepo var. melopepo) (includes: crookneck squash, scallop squash, 

straightneck squash, vegetable marrow, and zucchini); squash, winter (Cucurbita maxima; C. 

moschata) (includes: butternut squash, calabaza, hubbard squash) and (C. mixta; C. pepo) (includes 

acorn squash, spaghetti squash); and watermelon (includes hybrids and/or varieties of Citrullus 

lanatus)], 

• Dill, 

• Eggplant, 

• Forest seedlings, 

• Ginger, 

• Grape (vineyard replant only), 

• Kale, 

• Kohlrabi, 

• Leafy greens [includes all of EPA Crop Group 4, Leafy Vegetables (Except Brassica Vegetables), i.e., 

amaranth (leafy amaranth, Chinese spinach, tampala) (Amaranthus spp.); arugula (roquette) (Eruca 

sativa); cardoon (Cynara cardunculus); celery (Apium graveolens var. dulce); celery, Chinese (Apium 

graveolens var. secalinum); celtuce (Lactuca sativa var. angustana); chervil (Anthriscus cerefolium); 

chrysanthemum, edible-leaved (Chrysanthemum coronarium var. coronarium); chrysanthemum; 

garland (Chrysanthemum coronarium var. spatiosum); corn salad (Valerianella locusta); cress, 

garden (Lepidium sativum); cress, upland (yellow rocket, winter cress) (Barbarea vulgaris); 

dandelion (Taraxacum officinale); dock (sorrel) (Rumex spp.); endive (escarole) (Cichorium endivia); 

fennel, Florence (finochio) (Foeniculum vulgare Azoricum Group); lettuce, head and leaf (Lactuca 

sativa); orach (Atriplex hortensis); parsley (Petroselinum crispum); purslane, garden (Portulaca 

oleracea); purslane, winter (Montia perfoliata); radicchio (red chicory) (Cichorium intybus); rhubarb 

(Rheum rhabarbarum); spinach (Spinacia oleracea); spinach, New Zealand (Tetragonia 

tetragonioides, T. expansa); spinach, vine (Malabar spinach, Indian spinach) (Basella alba); and 

swiss chard (Beta vulgaris var. cicla)],

• Leek, 

• Mint, 

• Mustard, 

• Nursery stock (fruit seedlings and rose bushes only), 

• Onion, 

• Ornamentals (floriculture only), 

• Pome fruit (orchard replant only), [includes all of EPA Crop Group 11, Pome Fruits Group —

Commodities, i.e., apple (Malus domestica); crabapple (Malus spp.); loquat (Eriobotrya japonica); 

mayhaw (Crataegus aestivalis, C. opaca, and C. rufula); pear (Pyrus communis); pear, oriental 

(Pyrus pyrifolia); and quince (Cydonia oblonga)], 

• Peanut, 

• Pepper, 

• Potato, 
42

• Radish, 

• Rye, 

• Sugar beet, 

• Soybean, 

• Stone fruit (orchard replant only), [includes all of EPA Crop Group 12, Stone Fruits Group—

Commodities, i.e., apricot (Prunus armeniaca); cherry, sweet (Prunus avium); cherry, tart (Prunus 

cerasus); nectarine (Prunus persica); peach (Prunus persica); plum (Prunus domestica, Prunus spp.); 

plum, Chickasaw (Prunus angustifolia); plum, Damson (Prunus domestica spp. insititia); plum, 

Japanese (Prunus salicina); plumcot (Prunus. armeniaca X P. domestica); prune (fresh) (Prunus 

domestica, Prunus spp.)], 

• Strawberries, 

• Sugar beet, 

• Sweet potato, 

• Swiss Chard, 

• Tobacco, 

• Tomatoes, 

• Tree nuts (orchard replant only), [includes all of EPA Crop Group 14, Tree Nuts Group (i.e., almond 

(Prunus dulcis); beech nut (Fagus spp.); Brazil nut (Bertholletia excelsa); butternut (Juglans 

cinerea); cashew (Anacardium occidentale); chestnut (Castanea spp.); chinquapin (Castanea 

pumila); filbert (hazelnut) (Corylus spp.); hickory nut (Carya spp.); macadamia nut (bush nut) 

(Macadamia spp.); pecan (Carya illinoensis); and walnut, black and English (Persian) (Juglans spp.) 

as well as pistachio], 

• Turnip, 

• Turf (including golf courses), and 

• Wheat 

ii. Human Health Risk Management 

For details on the metam-sodium and metam-potassium human health risk assessment, 

please refer to the human health risk assessments and addenda. These documents are also 

available in the public docket EPA-HQ-OPP-2005-0125, located on-line in the Federal Docket 

Management System (FDMS) at www.regulations.gov. 

Dietary Risk 

Based on the currently registered use patterns for metam-sodium and metam-potassium, 

dietary exposure, including exposure from drinking water, is not expected and no dietary risk 

mitigation is warranted for metam-sodium and metam-potassium at this time. 

Bystanders, Workers, and Handlers 

The human health risk assessments indicate that inhalation exposures to bystanders, 

handlers, and workers who live and work near agricultural fields and greenhouses where metamsodium and metam-potassium fumigations occur have the potential to exceed the Agency’s level 

of concern without additional mitigation measures. To reduce the potential for metam-sodium 
43

and metam-potassium exposure to bystanders, handlers, and workers and to address associated 

risks of concern, EPA is requiring a number of mitigation measures which include: 

• Clarifying maximum application rates 

• Clarifying use sites; 

• Buffer zones; 

• Dermal protection for handlers; 

• Respiratory protection and air monitoring for handlers; 

• Restrictions on the timing of perforation and removing of tarps; 

• Posting; 

• Good agricultural practices; 

• Fumigant management plans; 

• Site specific response and management; and 

• Notice to state lead agencies. 

The Agency also believes that registrant developed training and community outreach 

programs, will help reduce risk. Additionally, EPA is interested in working with registrants to 

identify additional measures that could be implemented as part of product stewardship. These 

additional measures should include efforts to assist users’ transition to the new label 

requirements. 

 Some of the required mitigation measures only address one group of potentially exposed 

individuals (i.e., bystanders, handlers, or workers), while other measures will help reduce risk to 

more than one group. All mitigation measures are designed to work together to reduce 

exposures, enhance safety, and facilitate compliance and enforcement. The Agency has based its 

risk mitigation decision on a flexible approach, which EPA believes will be protective and allow 

users to make site-specific choices to reduce potential impacts on benefits of the use. While 

some of these measures, buffer zones for example, can be used to estimate margins of exposure 

(MOEs), others, such as emergency preparedness and response and community education, will 

contribute to bystander safety, but are difficult to express in terms of changes to quantitative risk 

estimates such as MOEs. However, EPA has determined that these measures, working together, 

will prevent unreasonable adverse effects on human health. 

aa. Bystander Risk Mitigation 

Bystanders are persons who live and/or work near fumigated fields and are potentially 

exposed to fumigant emissions that travel off site. In some cases the bystanders are workers 

performing agricultural tasks in nearby fields. If they are employed by the grower who has 

control of the fumigated field, they are more likely to be aware that a fumigant application has 

occurred. 

Bystander risks for people that live near treated fields differ from other human health 

risks evaluated under FIFRA, for example residential and worker reentry risks. Unlike 

residential exposures resulting from use of products to control pests in and around the home, 
44

non-occupational bystanders receive no direct benefit from the pesticide, which was applied 

elsewhere. These bystanders have not made a decision to purchase a pest control product or 

service, and, as a result, they have little access to information about the product (e.g., hazards, 

safety information, first aid, etc.) or symptoms of exposure. Additionally, non-occupational 

bystander exposures to fumigants are largely involuntary and unanticipated. In this regard nonoccupational bystander exposure is similar to dietary exposure in that people consuming foods or 

drinking water expect to be safe from possible adverse effects associated with pesticide residues 

that could be present in their food and drinking water. 

Unlike workers, non-occupational bystanders typically receive no safety information or 

training related to the pesticide to which they may be exposed. Whereas workers are generally 

expected to play an active role in protecting themselves from pesticide risk, no such expectation 

exists for non-occupational bystanders. Workers who experience symptoms of pesticide 

exposure are also more likely to link their symptoms to the pesticide and take steps to receive 

appropriate treatment. Conversely, bystanders are much less likely to attribute adverse effects to 

pesticide exposures or to have access to information needed to take appropriate steps to mitigate 

the effects of the exposure. Thus, EPA’s mitigation includes elements for emergency 

preparedness and response, notice to state lead agencies, training, and community outreach as 

well as labeling changes. 

 The mitigation measures for bystander risks resulting from soil fumigation are described 

 further in the following sections. 

1. Buffer Zones 

The human health risk assessments indicate bystanders may be exposed to MITC air 

concentrations following metam-sodium and metam-potassium applications that exceed the 

Agency’s level of concern based on current label requirements. In general, the risk from 

inhalation exposures decreases as the distance from the field where bystanders are located 

increases. Because of this relationship, the Agency has determined that a buffer zone must be 

established around the perimeter of each application block where metam-sodium and metampotassium is applied. The Agency acknowledges that buffer zones alone will not mitigate all 

risks or eliminate incidents caused by equipment failure, human error, adverse weather (e.g., 

temperature inversions), or other events. The Agency however does believe that buffer zones 

along with other mitigation measures required by this decision and described below will mitigate 

risks so that bystanders will not experience unreasonable adverse effects. 

The Agency considered various buffer zone schemes ranging from fixed buffer zones for 

every application to site-specific buffer zones. During the Phase 5 comment period, the Agency 

received input in favor of a flexible buffer approach that would allow fumigant users to 

determine the buffer zone distance based on site conditions and application practices. While the 

Agency believes that site-specific buffer zones would provide the most flexibility for users, the 

EPA currently does not have sufficient data to support this scheme. As a result, the Agency has 
45

developed a scalable buffer zone system that does provide flexibility by setting buffer zones for 

different application methods at various acreages and application rates. 

Version 2.1.4 of the Probabilistic Exposure and Risk model for Fumigants (also called 

the PERFUM model) combined with monitoring data and incident data were used to characterize 

the risk for specific buffer zone distances corresponding to the range of application scenarios 

anticipated. Additional information on the PERFUM inputs and outputs can be found in Agency 

risk assessment, (EPA-HQ-OPP-2005-0123-0285), in a June 2006 a peer-reviewed article 

describing the model (http://www.sciencedirect.com/science/journal/13522310), and/or the 

PERFUM user’s guide which can be download from the internet 

(http://www.exponent.com/perfum/). A CD containing all of the PERFUM input/output files and 

files with the PERFUM MOE/air concentration analysis that were considered for this decision 

are available upon request at the OPP Docket Office. 

(a) Buffer Zone Requirements 

General Requirements in the July 2008 RED 

The 2008 metam-sodium and metam-potassium RED described general buffer zone 

requirements for metam-sodium and metam-potassium and other soil fumigants. This included 

the definition of a buffer zone, the requirement to exclude non-handlers from the buffer zone 

during the buffer-zone period, and the definition of the application block. 

 The RED also did not allow buffer zones to overlap and fumigations were prohibited 

within 1⁄4 mile of difficult to evacuate sites such as schools, state licensed day care centers, 

nursing homes, and hospitals, if occupied during the buffer zone period. Exemptions for 

vehicular and bicycle traffic were allowed on roadways through the buffer zone. However, bus 

stops or other locations where persons wait for public transit were not permitted within the buffer 

zone. Structures within the buffer zone were also not allowed to be occupied during the buffer 

zone period and air samples were required before bystanders could enter the structure following 

expiration of the buffer-zone period. In addition, before a buffer zone could extend onto 

adjacent private or public property, the applicator needed to obtain written permission from the 

owner/operator or local authority to allow the buffer zone to extend onto the property. This was 

to ensure that non-handlers would not enter the buffer zone and that buffer zones did not overlap. 

Comments on the July 2008 RED 

During the post-RED comment period, the Agency received many comments from 

stakeholders concerning the buffer zone requirements. Many comments stated that the large 

buffer zone distances would make fumigation infeasible and the mitigation options were not 

flexible enough to allow some fumigations to occur; however other comments expressed concern 

that buffers EPA specified would not be large enough to protect bystanders. 

 
46

The Agency also received numerous comments that buffer zone duration will present 

severe hardship for growers. Many commenters expressed concern that the buffer zone overlap 

restriction would have the unintended consequence of forcing some applications to occur during 

less-than-optimal weather and soil conditions, because the restriction could preclude nearby 

application blocks from being treated when weather and soil conditions would be optimal for 

reducing emissions. Hence, subsequent fumigations in adjacent fields would have an increased 

chance of occurring when weather and soil conditions are more conducive to off-gassing. 

Examples cited by commenters where this situation could occur include the Southeast and 

Pacific Northwest where optimal soil moisture conditions occur during a limited time period. 

The commenters felt that while the buffer zone is in effect, properly trained and equipped 

handlers should be allowed to enter adjacent application blocks to make applications. Several 

commenters felt that providing an exception to this prohibition would make buffers more 

workable, reduce delays, allow a more efficient use of equipment and labor, allow growers 

additional flexibility to achieve compliance with buffer requirements, and potentially reduce risk 

if applications could be made under more favorable soil and weather conditions. In addition, 

some comments suggested that allowing adjacent application blocks to be treated would not 

increase risk to bystanders since the Agency’s mitigation measures encourage users to split 

application blocks into smaller treatment areas which result in less fumigant being applied, less 

exposure, and less potential risk. 

Some comments also asked for clarification on various aspects of the buffer zone 

requirements, and some asked that EPA provide additional increments for acreages and 

application rates for buffer zone tables. In addition, many comments stated that buffer zone 

credits should be greater for the use of tarps and for certain environmental conditions. A number 

of comments indicated that obtaining written permission from local authorities for buffers to 

extend over roads and rights-of-way would be extremely difficult, and that neighbors may not 

provide permission. EPA also received additional field emissions (flux) data for some 

fumigants, as well as additional information regarding factors that affect fumigant emissions. 

Based on EPA’s review of the comments, and new data and information, the Agency has 

determined that certain amendments to the buffer zone requirements are appropriate. EPA 

believes these amendments will maintain the important protections for bystanders but will 

increase the feasibility of compliance with buffers and will reduce potential impacts of buffers on 

the beneficial uses of soil fumigants. The Agency does agree that compliance with buffer zone 

requirements as outlined in the July 2008 RED would be a significant challenge for applicators 

and growers. However, field flux studies, monitoring data, modeling analyses, and information 

from incidents involving fumigants continue to support a conclusion that metam-sodium and 

metam-potassium off-gasses and moves away from treated fields at concentrations that have the 

potential to cause adverse effects. Therefore, the Agency still believes that buffer zones that 

exclude bystanders are a critical aspect of mitigating risks from the use of metam-sodium and 

metam-potassium. The Agency believes the modifications to the buffer requirements, specified 

below, will increase compliance feasibility and encourage further adoption of emission reduction 

application techniques, while still protecting human health and the environment. 
47

Amended RED Requirements 

EPA has determined that no changes to several aspects of the general buffer zone 

requirements from the 2008 RED are appropriate. This includes 

- the definition and duration of a buffer zone; 

- the requirement to exclude field workers, nearby residents, pedestrians, and other 

bystanders from the buffer zone during the buffer zone period (except for transit); 

- the definition of the application block; 

- the minimum buffer of 25 feet and maximum buffer of 1⁄2 mile. 

- the requirement limiting entry into buffer zones to handlers who have been properly 

trained and equipped according to EPA’s Worker Protection Standard; 

- the exemption for transit through buffer zones; 

- the prohibition on including in buffer zones bus stops or other locations where 

persons wait for public transit; 

- the prohibition against including in buffer zones buildings under the control of the 

owner/operator of the application block used for storage such as sheds, barns, 

garages, etc., unless the storage buildings are not occupied during the buffer zone 

period, and the storage buildings do not share a common wall with an occupied 

structure; 

- the prohibition against including in buffer zones residential areas that are not under 

the control of the owner/operator unless occupants agree in writing that they will 

voluntarily vacate the buffer zone until the buffer zone period expires; 

- the prohibition against including in buffer zones agricultural areas that are not under 

the control of the owner/operator unless the owner/operator of the other area provides 

written agreement that they, their employees, and other persons will not enter the 

buffer zone; and 

- the prohibition against including in buffer zones publicly owned and/or operated 

areas such as parks, sidewalks, walking paths, playgrounds, and athletic fields 

without first obtaining written permission from local authorities. 

EPA has determined that certain other amendments to the July 2008 RED requirements 

are appropriate; these are discussed in greater detail below. The amended buffer zone 

requirements are summarized at the end of this section. 

Buffer Zone Proximity - Exception to Allow Buffer Zone Overlap 

The Agency is concerned that emissions from multiple fields located close to one another 

could be higher than air concentrations from individually treated fields. As a result, bystanders 

outside of buffers for individual application blocks could be exposed to concentrations of 

concern particularly if peak concentrations from multiple application blocks in proximity to each 

other coincide. To reduce the potential for off-site movement of fumigant emissions beyond 

buffer zones for multiple fumigated fields, the July 2008 RED prohibited buffer zones from 

multiple application blocks from overlapping, including application blocks fumigated by other 

property operators. 
48

EPA has considered the comments submitted and has determined that allowing an 

exception to the buffer zone overlap prohibition, under the conditions specified below, is 

reasonable and will not demonstrably alter the protection goals provided to bystanders in the July 

2008 RED. EPA has determined that buffer zones from nearby and adjacent application blocks 

may overlap one another provided at least 12 hours have elapsed from the end of one application 

until the start of the next application. By separating the application times by at least 12 hours the 

fumigant emission peaks are less likely to occur at the same time which would sufficiently 

reduce potential exposure outside buffer zones and meets the Agency’s protection goals. 

The Agency is maintaining the requirement for buffer zones around each application 

block to be in effect for 48 hours, as well as the requirement that only properly trained and 

equipped handlers are allowed to enter into buffers zones. 

To clarify, below are conditions when buffer zones may or may not overlap: 

• A buffer zone may NOT overlap buffer zones from other application blocks that 

are already in effect UNLESS a minimum of 12 hours has elapsed from the time 

the first application ends until the second application begins. 

Metam only: Applications of metam-sodium and metam-potassium can take place on 

large fields, typically greater than 80 acres, and may require several days to complete (e.g., via 

center pivot or lateral move irrigation systems). In situations where such large field sizes are 

treated the offsite movement of emissions may be proportionately less, on an acre basis, than 

smaller fields because the fetch (i.e., area over which emissions are diluted) for certain areas of 

such fields would be either contained totally within the boundaries of the field or it would allow 

for significant dilution as the emissions move from the application block offsite into the buffer 

zone. As a result of the time requirements involved in treating such large areas and the reduced 

per acre contributions to overall emissions on large fields, EPA believes there is less potential 

for peak emissions from multiple large applications blocks to coincide and result in 

concentrations of concern outside adjacent buffers within localized areas than would be expected 

if the situation varied by larger numbers of smaller fields being treated that would more likely 

result in coincidental peak emissions (e.g., fields that take no more than one day to treat and that 

are smaller in acreage). 

Although current modeling supports a conclusion that as application block size increases, 

the emissions into the buffer areas are reduced on a per acre basis, the data to support a robust 

analysis of this relationship is very limited at this time. Based on comments provided, EPA also 

recognizes that compliance with the prohibition on buffer overlap in areas such as the Pacific 

Northwest with large-scale production systems based on center pivot applications would be 

extremely challenging for metam users. EPA also understands that, due to the length of time 

needed to complete these applications, separating applications by 12 hours is also impractical. 

EPA also wishes to encourage adoption of improved application techniques such as low release 

height-solid stream center pivot systems because it believes that their use will reduce the 
49

potential for exposures of concern because they reduce droplet drift potential for those in 

proximity to fields and may reduce application rates as well because of more effective water 

delivery. Based on these considerations, the Agency has determined that buffer zones may 

overlap for center-pivot application blocks only if each block is treated using low release heightsolid stream center pivot systems which will increase the feasibility of compliance with buffer 

zone requirements and will not demonstratively alter the protection provided to bystanders. 

The Agency is maintaining the requirement for buffer zones around each application 

block to be in effect for 48 hours and that only properly trained and equipped handlers are 

allowed to enter into buffers zones. 

To clarify, below are conditions when buffer zones may or may not overlap: 

• A buffer zone may NOT overlap buffer zones from other application blocks that 

are already in effect UNLESS a minimum of 12 hours has elapsed from the time 

the first application ends until the second application begins. 

Metam Only: For Low Release Height-Solid Stream Center Pivot Applications only: 

• A buffer zone may NOT overlap buffer zones from other application blocks 

which are already in effect UNLESS both application blocks are treated using low 

release height-solid stream center pivot systems. The 12 hour waiting period does 

not apply in this instance. 

EPA has determined that when fumigators exercise the exception to allow buffers to 

overlap, the emergency preparedness and response measures described later in this document 

must be implemented if there are homes, businesses, or property not within the control of the 

fumigator within 300 feet of the buffer zone. 

To ensure handlers are aware that they are working in an existing buffer from an 

overlapping buffer zone area, the labels will require the certified applicator, before beginning the 

application, to determine whether the application block or its resulting buffer will overlap with a 

buffer that is already in effect. If so, the certified applicator must inform handlers of this and the 

health effects, early signs of exposure, and respiratory protection and PPE requirements for 

products applied in both the application block in which they are working and the other 

application block. The Agency is requiring that all treatment areas and buffers be clearly posted 

with proper signage to ensure handlers entering a treatment area are aware of previous treatments 

and the existence of buffers. In addition, certified applicators must obtain permission from other 

landowners when buffers extend onto other lands which provides an additional mechanism to 

ensure handlers are aware when they are working in a buffer zone and that they have the 

necessary information regarding health effects, warning properties, and respiratory/PPE 

requirements for all products they may be exposed to. 

Areas not under the control of owner/operator of the application block 
50

For areas not under the control of the owner/operator of the application block, the 

requirements remain unchanged except (1) air samples do not need to be taken to allow 

occupants to reenter buildings or homes after the buffer zone period has expired, and (2) buffer 

zones may include publicly owned and/or operated roads, including rights of ways, without first 

obtaining written permission from local authorities; however, if a sidewalk or permanent walking 

path is associated with the road or right-of-way, written permission must be given by the 

appropriate state and/or local authorities. 

In summary, areas of a buffer zone not under the control of the owner/operator of the 

application block, may not include residential areas (including employee housing, private 

property, buildings, commercial, industrial, and other areas that people may occupy or outdoor 

residential areas, such as lawns, gardens, or play areas) unless the occupants provide written 

agreement that they will voluntarily vacate the buffer zone during the entire buffer zone period. 

The Agency determined that the concentrations of the fumigants 48 hours after completion of the 

application were likely to be below the Agency’s level of concern, and that the warning 

properties of MITC would alert persons reentering these sites if concentrations had not yet 

dissipated. Therefore, monitoring of buildings and outdoor areas after termination of the buffer 

zone is not necessary and will no longer be required. 

Buffer zones may still not include agricultural areas owned/operated by persons other 

than the owner/operator of the application block unless the owner/operator of the application 

block can ensure that the buffer zone will not overlap with a buffer zone from any adjacent 

property owners, taking into account the amended requirements for overlapping buffers. In 

addition, the applicator must still receive written permission from the owner/operator of areas 

that are not under the control of the applicator stating that the owner, their employees, and other 

persons other than handlers, consistent with buffer overlap provisions, will stay out of the buffer 

zone during the entire buffer zone period. The goal of this agreement is to ensure that a property 

owner of an agricultural field adjacent to an area that will be treated with a fumigant is aware 

when the fumigation will occur. This will allow the applicator to post on the adjacent property 

and take other required safety measures to ensure that persons on the property will not be 

exposed to a fumigant at levels above the Agency’s level of concern. Informing the property 

owner of the adjacent field will enable them to take any appropriate safety measure. The Agency 

believes that requiring the applicator obtain written permission will be an enforceable measure 

that will meet the goal of protecting workers and bystanders on adjacent properties that fall 

within a buffer zone. 

In addition, buffer zones still may include publicly owned and/or operated areas such as 

parks, sidewalks, walking paths, playgrounds, and athletic fields only if the area is not occupied 

during the buffer zone period and entry by non-handlers is prohibited during the buffer zone 

period. Written permission from the appropriate state and/or local authorities to include those 

public areas in the buffer zone is also still required. 
51

However, for roads and rights-of-ways, EPA has determined that these may be included 

in buffers, subject to local laws and regulations, as long as it is posted according to the 

requirements of this amended RED. If, as discussed above, the road or right-of-way has an 

associated sidewalk or permanent walking path, then written permission would also be required 

to include the area in the buffer zone. The Agency believes that if a town or county has invested 

resources into building a sidewalk or establishing a walking path, it is reasonable to anticipate 

pedestrian traffic at that location. In such circumstances EPA believes a local authority would be 

best positioned to make a determination about the practicality of preventing non-handlers from 

entering the buffer zone. EPA acknowledges that laws and regulations vary from jurisdiction to 

jurisdiction and that the requirement to post points of entry into buffer zones may necessitate 

additional steps on the part of fumigant applicators before a road or right-of-way can be included 

in a buffer. 

(b) PERFUM Model Inputs 

The major input parameters for the modeling are: application rates, application block 

sizes, application method emission profiles, weather conditions, and the target air concentration 

(based on acute inhalation endpoint and uncertainty factors). The following summarizes the key 

points for each of these input parameters. 

Application Rates

The Agency modeled up to 320 lb ai/acre for all metam applications, the maximum 

application rate permitted on the metam product labels. However, typical application rates vary 

by crop and geographic region. According to EPA proprietary data for 2004-2005, 

approximately 94% of metam-sodium was applied at a rate of 225 lb ai/acre or less. OPP’s 

Biological and Economic Analysis Division (BEAD) completed a series of benefits assessments 

by crop and region that included a more detailed analysis of use rates and are available for 

review in the metam-sodium docket (EPA-HQ-OPP-2005-0125) at www.regulations.gov. 

Rates for bedded or strip applications (lb ai per treated area) were converted to broadcast 

equivalent application rates to determine the minimum buffer zone distance. In Figures 1 and 2

(shown below), the dashed line represents the perimeter of the field, the shaded area is the 

portion of the field that is treated, and the un-shaded area is the area of the field that is untreated. 

As an example, assume that both fields are 10 acres, and only 50% of field in Figure 2 is 

fumigated, and the rate per treated acre is 400 lbs ai/A for both Figure 1 and 2. In this case, the 

broadcast rate for Figure 1 is 400 lb ai/A but the effective broadcast equivalent rate for Figure 2 

is 200 lbs ai/A. Labels may express rates as lbs per treated acre under the application 

instructions but they must identify buffer zone distances based on the broadcast or effective 

broadcast equivalent rates. [Note: In the risk assessment, a 60% value for proportion of field 

treated was used in the calculations.] 
52

Figure 1. Broadcast Application Figure 2. Bedded Application

 Application Block Sizes

For all application methods, the Agency modeled up to 120 acres, which is the limit of 

the PERFUM model. However, typical application block sizes vary by crop and geographic 

region. In the Pacific Northwest, crops are typically grown in fields averaging 120-acres in size, 

while crops in California, the upper Midwest, and the Southeast tend to be smaller, typically 10-

60 acres, 30-50 acres, and 10-40 acres respectively. OPP’s Biological and Economic Analysis 

Division (BEAD) completed a series of benefits assessments by crop and geographic region that 

included a more detailed analysis of typical application block sizes, which are available for 

review in the metam-sodium docket (EPA-HQ-OPP-2005-0125) at www.regulations.gov. 

The application block size pertains to size of the field and not the size of the area treated. 

The area inside the dashed lines in both Figures 1 and 2 is the application block. In this example 

the application block size for both figures is 10 acres. For both figures, 10 acres would be used 

to determine the buffer zone distance. 

During the post-RED comment period, the Agency received comments requesting buffer 

zone distances for additional acreage increments for small fields. In response, the Agency 

determined buffer distances for smaller block sizes (1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 acres) for all 

application methods except center pivot irrigation applications and determined buffer zone 

distances for all relevant block sizes to 10-acre increments. Although the Agency added 

additional acreage and rate increments, not all increments may be captured by the tables 

presented. If the tables do not capture a specific acreage or rate, round up to the nearest acre or 

rate. For example, when applying to a 9.5 acre field, round up to 10 acres. 

Emission Studies

The Agency’s revised human health risk assessment (see: “Metam Sodium: Third 

revision of the HED Human Health Risk Assessment,” 4/30/09, DP# 293354 in the metam 

sodium docket: EPA-HQ-OPP-2005-0125) included modeling of five pre-plant soil application 

methods: (1) sprinkler irrigation (with standard2 and intermediate3 water seals), (2) shank 

 

2 A standard water seal consisted of either a 1⁄2 inch of water added immediately after an application and another 1⁄2-

inch of water applied within 24 hours of the application (chemigation study) or a 1⁄2 inch of water applied within 24 

hours of the application (shank injection study). 
53

injection (with standard1 and intermediate2 water seals, compaction, and standard polyethylene 

tarps), (3) drip irrigation (with and without standard polyethylene tarps), and (4) flood irrigation, 

and (5) spray boom application, followed by rototiller and then a flatroller. Modeling for the 

spray/rototiller/roller application method was added based on flux study data that was provided 

to the Agency during the post-RED comment period. The modeling performed by EPA is based 

on 15 field volatility studies. The majority of these studies were conducted in California (12), 

with several also conducted in Florida (2) and Washington (1). 

While the Agency considered the modeling data from all 14 emissions studies available, 

it used a subset of the most representative emissions studies to serve as the basis for developing 

the buffer zone distances. These studies included: (1) the Bakersfield, CA, sprinkler irrigation 

study with intermittent water seal (USDA CSREES Project #74; 09/02); (2) the Bakersfield, CA, 

shank injection study with intermittent water seal (USDA CSREES Project #74; 09/02); (3) the 

Citra, FL, drip irrigation study with tarps (USDA CSREES Project #74; 02/03); (4) the Brawley, 

CA, flood irrigation study (MRID 473143-01); and (5) the Smith River, CA, spray/rototiller/roll 

study (MRID 47572201). For application methods where the Agency does not currently have 

emissions study data available, these emissions study profiles also served as surrogate data. The 

spray blade injection applications were derived from the rotary tiller emission study profile. The 

buffer zone distances for all chemigation and the low-release height and low-drift center pivot 

applications were derived from the sprinkler irrigation emission study profile with intermittent 

water seal. It should be noted that the Agency does not believe that the sprinkler irrigation study 

emissions data are representative of the high-release height center pivot application method 

(which includes use of end guns). However, the Agency has selected buffer zone distances for 

this application method that it believes are sufficiently protective of bystander risk. Washington 

State University has submitted studies to quantify the flux rate for metam-sodium and metampotassium from shank injection applications and from center pivot applications using a drizzle 

boom in the Pacific Northwest. These studies were submitted in April, 2009, and are currently in 

review. If these studies indicate that the buffer zones for these types of applications should be 

modified, the Agency will update the buffer tables prior to implementation of new labeling 

related to buffers for metam sodium in 2011. The results of these studies have not been included 

in this amended document and the buffer tables below. EPA is requiring the registrants to 

submit studies to quantify the flux rate for metam-sodium and metam-potassium from center 

pivot applications using low-, medium- and high- release equipment, both with and without the 

use of endguns. The Agency will include the results of this research in its final labeling 

decisions, if possible. 

Based on the site characteristics (i.e., maximum air temperature, maximum soil 

temperature, field capacity) of the field volatility studies that served as the basis for the buffer 

zone distances, the profiles modeled for both the sprinkler irrigation (with intermediate water 

 3

 An intermediate water seal consisted of a 1⁄4 inch of water applied immediately after application, two additional 1⁄4-

inch water seals applied the same day as the application, as well as three additional 1⁄4-inch water seals applied the 

day following application. 
54

seals) and shank injection (with intermediate water seals) scenarios, were assumed to represent 

high-end but not necessarily the worst case for metam applications in the U.S. The profiles 

modeled for both the drip and flood irrigation scenarios as well as the rotary tiller application 

scenarios, which served as the basis for the buffer zone distances, were assumed to represent 

more “typical” site characteristics. The Agency believes that several required GAPs, including 

mandatory soil temperature and soil moisture requirements, will greatly reduce the likelihood 

that worst case scenarios will occur. 

Weather

The largest use of metam-sodium and metam-potassium for soil fumigation in the U.S. 

occurs in the Pacific Northwest and California, followed by the upper Midwest and the 

Southeast. Based on these high-use areas, six weather station data sets were modeled (Ventura, 

CA; Bakersfield, CA; Bradenton, FL; Tallahassee, FL; Flint, MI; and Yakima, WA). Each 

modeling run used five years of weather data (e.g., 1,825 potential application days) for each 

location. Generally, Ventura, and Bradenton weather data result in the largest buffer zone 

distances, followed by Bakersfield and Tallahassee. Flint data result in significantly smaller 

buffers. 

Target Air Concentrations 

As described in the Human Health Risks section of Section III, the 22 ppb target air 

concentration is based on a reversible sensitive endpoint from a human eye irritation and odor 

threshold study for acute exposures to MITC, with a 10X human variability uncertainty factor for 

intraspecies extrapolation. The lowest observable adverse effect level (LOAEL) is 800 ppb, and 

the human concentration (HC) based on the no observable adverse effect level (NOAEL) from 

this study is 220 ppb. 

The Agency focused on achieving an MOE of 10 at upper percentiles of each of the 

distributions from the PERFUM modeling outputs. However, the buffer zone distances required 

to achieve this MOE would have been prohibitively large and likely would have been impossible 

for most growers to implement. The Agency believes that the buffer zone distances being 

required, in addition to the other mitigation requirements described herein (i.e., restricted use 

pesticide classification, posting and emergency preparedness procedures for buffer zones, 

mandatory good agricultural practices, required fumigant management plans, soil fumigant 

training requirements for applicators and handlers, and ambient air monitoring programs in highuse areas), adequately address the risk of acute fumigant exposure to bystanders and will greatly 

reduce the magnitude and frequency of exposure incidents. 

(c) PERFUM Model Outputs 

The PERFUM model outputs are presented in percentiles for “whole field” and the 

“maximum distance” distributions. The model also provides outputs as distributions of air 
55

concentrations from which margins of exposure (MOEs) can be estimated. The following 

summarizes the key points for each of these output parameters. 

The maximum distance distribution is a compilation of the farthest predicted buffer 

distances (i.e., the farthest downwind points) over 5 years of weather, and the whole field 

distribution, as described, differs because it includes all points around the perimeter for the same 

period. It also should be noted that another way to consider this is that maximum buffer results 

are a subset of the whole field results and that maximum distances allow for more resolution at 

the upper percentiles of this distribution. Version 2.1.4 of PERFUM also allows for direct 

consideration of air concentrations at various distances around treated fields. These values were 

also considered in the decision-making process. 

An analysis based on a variety of PERFUM outputs was used in the buffer distance 

determinations. This involved consideration of the typical maximum and whole-field results, 

which are predictions of the distances at which a target concentration of concern (i.e., the human 

equivalent concentration adjusted by applicable uncertainty factors) is achieved at varying 

percentiles of exposure. In addition, a complementary approach, which determined the 

percentiles of exposure for maximum and whole-field buffers at predetermined buffer distances, 

was employed. Air concentration data were also used to calculate risk estimates (i.e., margins of 

exposure) at predefined buffer distances and varied percentiles of exposure. 

This overall approach allowed the Agency to utilize more of the information available 

from PERFUM so that a more comprehensive view of the risks could be considered. Buffer 

distances indicated by this type of analysis along with information from monitoring studies and 

incidents were valuable in determining buffer distances to manage potential risks from metamsodium and metam-potassium use when coupled with other mitigation measures. 

Buffer Zone Distances

 The Agency has developed required buffer zone distances based on application method, 

application rate, and application block size (rounding up to nearest whole units for application 

rate and block size). These distances are summarized in Tables 5 to 11 below. 

For each of the outdoor pre-plant soil emission profiles, presented in the July 2008 RED, 

distances were first chosen for the rates identified in the risk assessment as the 10%, 25%, 50%, 

75% and 100% of the maximum rates (i.e., 32, 80, 160, 240, and 320 lb ai/A for all metam 

applications), each paired with application block sizes of 5, 10, 20, 30, 40, 50, 60, 80, 100, and 

120 acres. Distances for the other rates in the buffer zone tables were scaled by assuming a 

linear relationship between the 10%, 25%, 50%, 75% and 100% maximum label rates [e.g., 

distance at 37.5% rate = (distance at 25% rate + distance at 50% rate)/2]. This scaling was 

necessary to provide an incremental spread of rates. It should be noted that the distances in the 

lookup tables are not model outputs, although the model outputs were a tool used for their 

development. A description of how the model outputs were used to characterize the buffer zone 

distances is provided immediately after the buffer zone look-up tables (Tables 5 to 11). 
56

Additionally, during the post-RED comment period, the Agency received a comment from 

the Northwest Horticultural Council, which indicated that the primary application method for 

orchard replant using metam sodium in the Pacific Northwest, a row/strip treatment of metam 

sodium to a future tree row using a weed sprayer while irrigation sprinklers are running, was not 

specifically addressed in the Agency’s RED decision. Based on the information provided by the 

Council, EPA is allowing this application method, provided that the handler protection 

requirements referenced in the handler protection sections of the RED addendum are followed 

and buffer zones consistent with Table 8: All Chemigation Except Center Pivot and Flood 

Applications are implemented. 

 Minimum and Maximum Distances 

 

A minimum buffer zone of 25 feet will be required regardless of site-specific application 

parameters. In some instances, the PERFUM model predicts that the risks reach the target at the 

edge of the field, but the Agency believes that a 25-foot minimum buffer is a good agricultural 

practice. While modeling may support no buffer in some cases, a minimum buffer is being 

required because of variability in emission rate over a field and other factors not accounted for in 

the modeling. Conversely, application scenarios requiring buffers zone distances of more than 1⁄2 

mile (2,640 feet) are prohibited. EPA believes that for areas where metam-sodium and metampotassium are used, buffers greater than 1⁄2 mile are not practical and difficult to enforce. 

The buffer zone distances were not based on the selection of a specific percentile or 

distribution from the PERFUM modeling results. Rather, EPA used a weight of evidence 

approach to set the buffers that included consideration of the hazard profile of metam-sodium 

and metam-potassium, information from incident reports, monitoring data, and stakeholder 

comments along with comprehensive analysis of results from PERFUM modeling and 

consideration of results using other models (e.g., Industrial Source Complex Model). The 

analysis of PERFUM results considered distances at various percentiles of the whole field and 

maximum distance distributions as well as and predicted MOEs for various distances. The risk 

assessment characterizes additional types of analysis that were performed. The following 

characterizes the risks associated with the buffer zone distances summarized in Tables 5 to 11. 

The buffer zone distances at the 90th percentile maximum distribution is equivalent to 

saying a person at the location on the perimeter of the buffer zone where the maximum 

concentration occurs during the worst case 24-hour period following the fumigation of a specific 

field during a 5-year period would have at least a 90% chance of exposure below the level of 

concern. The buffer zone distances at the 90th percentile whole field distribution is equivalent to 

saying a person somewhere on the perimeter of the buffer zone during the worst case 24-hour 

period following the fumigation of a specific field during a 5-year period would have at least a 

90% chance of exposure below the level of concern. The risk assessment, available in the 

metam-sodium and metam-potassium docket (EPA-HQ-OPP-2005-00125) at 

www.regulations.gov, characterizes additional types of analysis that were performed. 
57

Note: Washington State University has submitted studies to quantify the flux rate for metamsodium and metam-potassium from shank injection applications and from center pivot 

applications using a drizzle boom in the Pacific Northwest. These studies were submitted in 

April, 2009, and are currently in review. If these studies indicate that the buffer zones for these 

types of applications should be modified, the Agency will update the buffer tables prior to 

implementation of new labeling related to buffers for metam sodium in 2011. The results of 

these studies have not been included in this amended document and the buffer tables below. 
58

Table 5. Center Pivot Irrigation Application (High Release Height*) 

Buffer Zone Distance in Feet 

Application Rate (lb ai/A) 

Block 

Size 

(A) 

32 56 80 100 120 140 160 180 200 220 240 260 280 300 320 

1 50 80 125 160 185 205 220 235 250 262 275 288 300 312 325 

5 50 100 150 188 225 263 300 313 325 338 350 363 375 389 400 

10 50 100 150 200 250 300 350 375 400 425 450 488 525 563 600 

20 75 138 200 250 300 350 400 450 500 550 600 650 700 750 800 

30 75 138 200 269 338 407 475 557 638 719 800 850 900 950 1000 

40 100 200 300 363 425 488 550 638 725 813 900 975 1050 1125 1200 

50 100 200 300 382 463 544 625 719 813 907 1000 1100 1200 1300 1400 

60 200 300 400 475 550 625 700 825 950 1075 1200 1300 1400 1500 1600 

70 200 300 400 488 575 663 750 888 1025 1163 1300 1400 1500 1600 1700 

80 200 300 400 500 600 700 800 950 1100 1250 1400 1500 1600 1700 1800 

90 250 350 450 550 650 750 850 1000 1150 1300 1450 1563 1675 1788 1900 

100 300 400 500 600 700 800 900 1050 1200 1350 1500 1625 1750 1875 2000 

110 350 450 550 650 750 850 950 1100 1250 1400 1550 1688 1825 1963 2100 

120 400 500 600 700 800 900 1000 1150 1300 1450 1600 1750 1900 2050 2200 

140 600 700 800 900 1000 1100 1200 1350 1500 1650 1800 1950 2100 2250 2400 

160 800 900 1000 1100 1200 1300 1400 1550 1700 1850 2000 2150 2300 2450 2600 

* This buffer zone distance table is for center pivot irrigation equipment in which the: 1) release height 

OR spray height greater than 8 feet, and 2) there is > 30 lbs psi at the sprinkler head. 
59

Table 6. Center Pivot Irrigation Application (Medium Release Height**) 

Buffer Zone Distance in Feet 

Application Rate (lb ai/A) 

Block 

Size 

(A) 

32 56 80 100 120 140 160 180 200 220 240 260 280 300 320 

1 25 25 25 37 50 62 75 87 100 112 125 138 150 162 175 

5 25 38 50 63 75 88 100 113 125 138 150 263 175 188 200 

10 25 50 75 94 113 132 150 175 200 225 250 288 325 363 400 

20 25 50 75 107 138 169 200 250 300 350 400 450 500 550 600 

30 25 50 75 125 175 225 275 357 438 519 600 650 700 750 800 

40 50 75 100 163 225 288 350 438 525 613 700 775 850 925 1000 

50 50 75 100 182 263 344 425 519 613 707 800 900 1000 1100 1200 

60 75 138 200 275 350 425 500 625 750 875 1000 1100 1200 1300 1400 

70 75 138 200 288 375 463 550 688 825 963 1100 1200 1300 1400 1500 

80 75 138 200 300 400 500 600 750 900 1050 1200 1300 1400 1500 1600 

90 88 169 250 350 450 550 650 800 950 1100 1250 1363 1475 1588 1700 

100 100 200 300 400 500 600 700 850 1000 1150 1300 1425 1550 1675 1800 

110 150 250 350 450 550 650 750 900 1050 1200 1350 1488 1625 1763 1900 

120 200 300 400 500 600 700 800 950 1100 1250 1400 1550 1700 1850 2000 

** This buffer zone distance table is for center pivot irrigation equipment in which the: 1) release height 

AND spray height is less than 8 feet, AND 2) 29lbs. or less PSI at the sprinkler head, AND 3) there are no 

end guns. 
60

Table 7. Center Pivot Irrigation Application (Low Release Height-Solid Stream***) 

Buffer Zone Distance in Feet 

Application Rate (lb ai/A) 

Block 

Size 

(A) 

32 56 80 100 120 140 160 180 200 220 240 260 280 300 320 

1 25 25 25 30 35 40 50 60 70 85 105 125 145 165 185 

5 25 25 25 35 50 63 75 94 113 132 150 163 175 188 200 

10 25 38 50 63 75 88 100 125 150 175 200 225 250 275 300 

20 25 38 50 70 89 107 125 157 188 438 250 288 325 363 400 

30 25 38 50 75 100 125 150 188 225 263 300 350 400 450 500 

40 25 50 75 107 138 169 200 238 275 313 350 413 475 538 600 

50 25 50 75 119 163 207 250 294 338 382 425 494 563 632 700 

60 50 75 100 150 200 250 300 363 425 488 550 613 675 738 800 

70 63 100 138 192 244 297 350 419 488 557 625 694 763 832 900 

80 75 125 175 232 288 344 400 475 550 625 700 775 850 925 1000 

90 88 138 188 254 319 385 450 532 613 694 775 857 938 1019 1100 

100 100 150 200 275 350 425 500 588 675 763 850 938 1025 1113 1200 

110 125 188 250 325 400 475 550 644 738 832 925 1019 1113 1207 1300 

120 150 225 300 375 450 525 600 700 800 900 1000 1100 1200 1300 1400 

*** This buffer zone distance table is for center pivot irrigation equipment in which the: 1) release height 

AND spray height is less than 4 feet, AND 2) 29lbs. or less PSI at the sprinkler head, AND 3) solid 

stream nozzle (e.g. drizzle boom, Smart Drop, etc.), AND 4) there are no end guns. 
61

Table 8. All Chemigation Except Center Pivot 

and Flood Applications Buffer Zone Distance In Feet

Application Rate (lb ai/A) 

Block 

Size 

(A) 

32 56 80 100 120 140 160 180 200 220 240 260 280 300 320 

1 25 38 50 55 62 68 75 80 87 93 100 115 125 137 150 

2 25 38 50 57 65 73 81 88 97 104 113 152 138 150 163 

3 25 38 50 58 67 78 88 97 106 116 125 189 150 163 175 

4 25 38 50 60 70 83 94 105 116 127 138 226 163 175 188 

5 25 38 50 63 75 88 100 113 125 138 150 263 175 188 200 

6 25 40 55 69 83 97 110 125 131 155 170 268 205 223 240 

7 25 43 60 75 90 106 120 138 140 173 190 273 235 258 280 

8 25 45 65 81 98 114 130 150 146 190 210 278 265 293 320 

9 25 48 70 87 105 123 140 163 155 208 230 283 295 328 360 

10 25 50 75 94 113 132 150 175 200 225 250 288 325 363 400 

20 25 50 75 107 138 169 200 250 300 350 400 450 500 550 600 

30 25 50 75 125 175 225 275 357 438 519 600 650 700 750 800 

40 50 75 100 163 225 288 350 438 525 613 700 775 850 925 1000 

50 50 75 100 182 263 344 425 519 613 707 800 900 1000 1100 1200 

60 75 138 200 275 350 425 500 625 750 875 1000 1100 1200 1300 1400 

70 75 138 200 288 375 463 550 688 825 963 1100 1200 1300 1400 1500 

80 75 138 200 300 400 500 600 750 900 1050 1200 1300 1400 1500 1600 

90 88 169 250 350 450 550 650 800 950 1100 1100 1363 1475 1588 1700 

100 100 200 300 400 500 600 700 850 1000 1150 1300 1425 1550 1675 1800 

110 150 250 350 450 550 650 750 900 1050 1200 1350 1488 1625 1763 1900 

120 200 300 400 500 600 700 800 950 1100 1250 1400 1550 1700 1850 2000 
62

Table 9. Shank Injection Applications-Tarped and Untarped 

Buffer Zone Distance In Feet

Application Rate (lb ai/A)

Block 

Size 

(A) 

32 44 56 68 80 100 120 140 160 180 200 220 240 260 280 300 320 

1 25 25 25 25 25 25 25 25 25 32 38 44 50 56 63 69 75 

2 25 25 25 25 25 25 25 25 25 32 38 44 50 58 66 74 81 

3 25 25 25 25 25 25 25 25 25 32 38 44 50 60 69 79 88 

4 25 25 25 25 25 25 25 25 25 32 38 44 50 61 72 83 94 

5 25 25 25 25 25 25 25 25 25 32 38 44 50 63 75 88 100 

6 25 25 25 25 25 26 28 29 30 38 45 53 60 75 90 105 120 

7 25 25 25 25 25 28 30 33 35 44 53 62 70 88 105 123 140 

8 25 25 25 25 25 29 33 36 40 51 60 70 80 100 120 140 160 

9 25 25 25 25 25 31 35 40 45 57 68 79 90 113 135 158 180 

10 25 25 25 25 25 32 38 44 50 63 75 88 100 125 150 175 200 

20 25 25 25 25 25 32 38 44 50 69 88 132 175 207 238 269 300 

30 25 32 38 44 50 57 63 69 75 113 150 188 225 257 288 319 350 

40 25 32 38 44 50 57 63 69 75 119 163 207 250 288 325 363 400 

50 25 38 50 63 75 82 88 94 100 150 200 250 300 350 400 450 500 

60 25 38 50 63 75 82 88 94 100 163 225 288 350 413 475 538 600 

70 38 51 63 76 88 104 119 135 150 207 263 319 375 444 513 582 650 

80 50 63 75 88 100 125 150 175 200 250 300 350 400 475 550 625 700 

90 63 76 88 100 113 138 163 188 213 266 319 372 425 500 575 650 725 

100 75 88 100 113 125 150 175 200 225 282 338 394 450 525 600 675 750 

110 75 91 107 123 138 163 188 213 238 298 357 416 475 550 625 700 775 

120 75 94 113 132 150 175 200 225 250 313 375 438 500 575 650 725 800 
63

Table 10. Rotary Tiller and Spray Blade Applications 

Buffer Zone Distance In Feet 

Application Rate (lb ai/A) 

Block 

Size 

(A) 

32 56 80 100 120 140 160 180 200 220 240 260 280 300 320 

1 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 

5 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 

6 25 25 25 25 25 25 25 25 25 25 25 27 29 30 32 

7 25 25 25 25 25 25 25 25 25 25 25 29 32 36 39 

8 25 25 25 25 25 25 25 25 25 25 25 30 36 41 46 

9 25 25 25 25 25 25 25 25 25 25 25 32 39 47 53 

10 25 25 25 25 25 25 25 25 25 25 25 34 43 52 60 

20 25 25 25 25 25 25 25 25 25 25 25 49 73 97 120 

30 25 25 25 25 25 25 25 25 25 25 25 64 103 142 180 

40 25 25 25 25 25 25 25 25 25 25 25 75 125 275 225 

50 25 25 25 25 25 25 25 42 58 74 90 135 180 225 270 

60 25 25 25 25 25 25 25 57 88 119 150 188 225 263 300 

70 25 25 25 25 25 25 25 64 103 142 180 218 255 293 330 

80 25 25 25 25 25 25 25 72 118 164 210 248 285 323 360 
64

Table 11. Drip Irrigation Applications-Tarped and Untarped 

Buffer Zone Distance in Feet 

Application Rate (lb ai/A) 

Block 

Size 

(A) 

32 56 80 100 120 140 160 180 200 220 240 260 280 300 320 

1 25 25 25 25 25 25 25 25 25 25 25 32 38 44 50 

2 25 25 25 25 25 25 25 27 28 30 31 37 41 46 50 

3 25 25 25 25 25 25 25 29 32 35 38 41 44 47 50 

4 25 25 25 25 25 25 25 30 35 39 44 46 47 49 50 

5 25 25 25 25 25 25 25 32 38 44 50 50 50 50 50 

6 25 25 25 26 28 29 30 37 43 49 55 56 58 59 60 

7 25 25 25 28 30 33 35 42 48 54 60 63 65 68 70 

8 25 25 25 29 33 36 40 47 53 59 65 69 73 76 80 

9 25 25 25 31 35 40 45 52 58 64 70 76 80 85 90 

10 25 25 25 32 38 44 50 57 63 69 75 82 88 94 100 

20 25 38 50 57 63 69 75 82 88 94 100 125 150 175 200 

30 25 38 50 57 63 69 75 94 113 132 150 188 225 263 300 

40 25 50 75 82 88 94 100 113 125 138 150 200 250 300 350 

50 25 50 75 82 88 94 100 125 150 175 200 250 300 350 400 

60 25 63 100 113 125 138 150 175 200 225 250 300 350 400 450 

70 25 76 125 140 150 163 175 207 250 269 300 350 400 450 500 

80 25 88 150 163 175 188 200 238 275 313 350 400 450 500 550 

For all pre-plant soil applications for metam-sodium and metam-potassium, the buffer 

zone distances necessary to achieve the target MOE (an MOE of 10), for all weather station data 

modeled, are prohibitively large and would likely be impossible for most growers to implement. 

The Agency worked to balance the need to develop buffer zone distances that are sufficiently 

protective with the benefits that accrue from the use of metam-sodium and metam-potassium. 

The Agency believes that the buffer zone distances it has selected, combined with the other 

mitigation measures described herein (e.g., requiring GAPs and FMPs; posting and emergency 

preparedness requirements; soil fumigant training requirements for applicators and handlers; 

clarifying use sites and ambient air monitoring programs in high-use areas) will adequately 

address the risk of acute exposure to bystanders and will greatly reduce the magnitude and 

frequency of exposure incidents. 

The Agency selected the buffer zone distances for metam-sodium and metam-potassium, 

such that the resulting MOEs are ≥ 3 for all application methods and all weather stations data. 

While this does not meet the target air concentration for the buffer zone distances, even at the 

lowest MOE (MOE of 3), the predicted air concentration at the edge of the buffer would be 12 

times lower than the lowest observable adverse effect level (LOAEL), which is the level at which 

eye irritation effects begin in humans. 
65

The table below (Table 12) shows the buffer distances and risk characterization for some 

key use scenarios, based on crop, region, typical application rate, and typical application block 

size. It also shows the percentile for the whole field and max distribution for each distance, as 

well as the MOE at the 95th percentile air concentration of PERFUM. 

• As noted previously, the target MOE for metam-sodium and metam-potassium is 10, and 

the MOEs for these key metam use scenarios range from 3 up to 26. 

• For the key metam use scenarios presented below, all of the whole field percentiles range 

from 60 to 99.9 percent, and the max percentiles range from <5 to 99 percent. 

• The use of GAPs, FMPs, and other mitigation measures required by this decision will 

contribute to an additional decrease in risk (see GAPs and FMPs sections below, pages 

103 and 113 respectively). 

Example 

Consider the use scenario listed below (in Table 12) for potatoes grown in the Pacific 

Northwest using a center pivot with medium release height (i.e., maximum spray height less than 

8 feet off the ground and no use of end guns). Here, with an application rate of 140 lb ai/acre and 

an application block size of 120 acres, the buffer zone distance (without emissions credits) would 

be 700 feet. Note that: 

 

• The MOE at the 95th air concentration from the PERFUM modeling data at this buffer 

distance is 4. 

• The risk level corresponding to this buffer zone distance at the 95th percentile whole field 

distribution is equivalent to saying a person at any location on the perimeter of the buffer 

zone during the worst 24-hour period following the fumigation of a specific field during a 5-

year period would have at least a 75% chance of having of exposure below the level of 

concern (i.e., MOE ≥ 10). 

• The risk level corresponding to the buffer zone distances at the 95th percentile maximum 

distribution is equivalent to saying a person at the location on the perimeter of the buffer 

zone where the maximum concentration occurs during the worst case 24-hour period 

following the fumigation of a specific field during a 5-year period would have a 15% chance 

of exposure below the level of concern (i.e., MOE ≥ 10 for these typical use scenarios). 
66

Table 12. Buffer Zone Distances and Risk Characterization for Key Metam Use Scenarios 

Whole Field and 

Max Distance 

Percentiles 

Crop Region Application Method 

Typical 

Application 

Rates 

(lb ai/A) 

Typical 

Application 

Block Size 

(A) 

Buffer Zone 

Distances 

(ft) w/o 

Credits 

Whole 

Field 

Max 

MOEs at the 

95th Air 

Concentration 

from 

PERFUM2 

Center Pivot – high release 

height 140 120-160 900-1300 n/a n/a n/a 

Center Pivot – medium release 

height without end gun PNW 140 120 700 75 15 4 

Center Pivot – low release 

height-solid stream, without end 

gun 

140 120 525 60 15 3 

80 175 60 <5 4 

Potatoes 

PNW Shank Injection 140 

120 225 60 <5 3 

10 82 65 <5 3 AZ & CA Shank (Strip, Tarped) 210 40 185 60 <5 3 

10 200 75 <5 3 

Cucurbits 

Southeast Shank (Strip, Tarped) 320 40 400 70 <5 3 

40 10 25 97 80 15 Shank (Strip, Tarped) 60 40 38 65 <5 9 

Tomatoes 

(Processed) CA 

Drip (Tarped) 40 10 25 99.9 99 26 

Tomatoes 10 200 75 <5 3 

(Fresh) Southeast Shank (Strip, Tarped) 320 40 400 70 <5 3 

30 169 60 <5 3 OR & WA Shank Strip 210 40 185 60 <5 3 

110 30 60 65 <5 5 

Onions 

CA Shank Strip 150 40 72 60 <5 3 

10 250 70 <5 3 Chemigation (Strip) 240 40 700 80 10 3 

10 75 75 10 5 

CA 

Drip (Tarped) 240 40 150 65 <5 3 

10 200 75 <5 3 

Peppers 

Southeast Shank (Strip, Tarped) 320 40 400 70 <5 3 

Peanuts NC & VA Chisel Strip (Shaped Beds) 35 50 25 85 35 12 

Sweet 10 175 65 <5 3 

Potato CA Shank (Strip, Tarped) 300 40 363 65 <5 3 

Tobacco 90 10 25 85 40 7 SC & VA Shank (Strip Tarped) 252 40 269 65 <5 3 

10 50 65 <5 4 CA Shank (Strip Tarped) 160 40 75 60 <5 3 

10 200 75 <5 3 

Eggplant 

Southeast Shank (Strip Tarped) 320 40 400 70 <5 3 

The Agency believes that the buffer zone distances described above, combined with other 

risk mitigation described herein, will provide protection against unreasonable adverse effects. 
67

Amended General Buffer Zone Requirements 

The following describes the general buffer zone requirements, as amended, for metam 

sodium: 

• “Buffer zone” is an area established around the perimeter of each application block or 

greenhouse where a soil fumigant is applied. The buffer zone must extend from the edge of 

the application block or greenhouse perimeter equally in all directions. 

• All non-handlers including field workers, nearby residents, pedestrians, and other bystanders, 

must be excluded from the buffer zone during the buffer zone period except for transit (see 

exemptions section). 

• The “buffer zone period” starts at the moment when any fumigant is delivered/dispensed to 

the soil within the application block and lasts for a minimum of 48 hours after the fumigant 

has stopped being delivered/dispensed to the soil. 

• An “application block” is a field or portion of a field treated with a fumigant in any 24-hour 

period. See exception provided in the “Buffer zone proximity” section below. 

Buffer zone proximity-Exception to Allow Buffer Zone Overlap

• To reduce the potential for off-site movement from multiple fumigated fields, buffer zones 

from multiple metam-sodium and metam-potassium application blocks may not overlap 

UNLESS: 

o A buffer zone may NOT overlap buffer zones from other application blocks that 

are already in effect UNLESS a minimum of 12 hours has elapsed from the time 

the first application ends until the second application begins. 

o Emergency preparedness and response measures specified later in this document 

have been implemented if there are any homes, businesses, or property not within 

the control of the fumigator within 300 feet of each buffer zone. 

For Metam-Sodium and Metam-Potassium Low Release Height-Solid Stream Center 

Pivot Applications only: 

o A buffer zone may NOT overlap buffer zones from other application blocks 

which are already in effect UNLESS both application blocks are treated using low 

release height-solid stream center pivot systems. The 12 hour waiting period does 

not apply in this instance. 

o Emergency preparedness and response measures specified later in this document 

have been implemented if there are any homes, businesses, or property not within 

the control of the fumigator within 300 feet of each buffer zone. 

 Buffer zone distances
68

• Buffer zone distances must be based on look-up tables on product labels. Twenty-five feet is 

the minimum buffer distance regardless of site-specific application parameters. 

• For selective replant fumigation in an orchard using hand held application methods (e.g., 

deep injection auger probes), the minimum buffer zone will be 25 feet measured from the 

center of each injection site (i.e., tree hole). 

Authorized entry to buffer zones

• Only authorized handlers who have been properly trained and equipped according to EPA’s 

Worker Protection Standard (WPS) and label requirements may be in the buffer zone during 

the buffer zone period. 

Exemptions for transit through buffer zones 

• Vehicular and bicycle traffic on public and private roadways through the buffer zone is 

permitted. "Roadway" means that portion of a street or highway improved, designed or 

ordinarily used for vehicular travel, exclusive of the sidewalk or shoulder even if such 

sidewalk or shoulder is used by persons riding bicycles. In the event a highway includes two 

or more separated roadways, the term "roadway" shall refer to any such roadway separately. 

(This definition is based on the definition of roadway in the Uniform Vehicle Code prepared 

by the National Committee on Uniform Traffic Laws and Ordinances. See 

http://www.ncutlo.org/ for more details) 

• Bus stops or other locations where persons wait for public transit are not permitted within the 

buffer zone. 

• See the Posting Section of this document for additional requirements that may apply. 

Structures under the control of owner/operator of the application block 

• Buffer zones may not include buildings used for storage such as sheds, barns, garages, etc., 

UNLESS, 

1. The storage buildings are not occupied during the buffer zone period, and 

2. The storage buildings do not share a common wall with an occupied structure. 

• See the Posting Section of this document for additional requirements that may apply. 

Areas not under the control of owner/operator of the application block

• Buffer zones may not include residential areas (including employee housing, private 

property, buildings, commercial, industrial, and other areas that people may occupy or 

outdoor residential areas, such as lawns, gardens, or play areas) UNLESS,

1. The occupants provide written agreement that they will voluntarily vacate the buffer zone 

during the entire buffer zone period, and 

2. Reentry by occupants and other non-handlers must not occur until, 

° The buffer zone period has ended, and; 
69

° Sensory irritation is not experienced 

• Buffer zones may not include agricultural areas owned/operated by persons other than the 

owner/operator of the application block, UNLESS,

1. The owner/operator of the application block can ensure that the buffer zone will not 

overlap with a buffer zone from any adjacent property owners, except as provided for 

above, and 

2. The owner/operator of the adjacent areas (i.e., areas that are not under the control of the 

owner/operator of the application block) provides written agreement to the applicator that 

they, their employees, and other persons will stay out of the buffer zone during the entire 

buffer zone period. 

• Buffer zones must not include roads and rights of way UNLESS, 

1. The area is not occupied during the buffer zone period, and 

2. Entry by non-handlers is prohibited during the buffer zone period. 

3. Applicators must comply with all local laws and regulations. 

• For all other publicly owned and/or operated areas such as parks, side walks, walking paths, 

playgrounds, and athletic fields, buffer zones must not include these areas UNLESS, 

1. The area is not occupied during the buffer zone period, 

2. Entry by non-handlers is prohibited during the buffer zone period, and 

3. Written permission to include the public area in the buffer zone is granted by the 

appropriate state and/or local authorities responsible for management and operation of 

the area. 

4. Applicators must comply with all local laws and regulations. 

Restriction for Schools and Other Difficult-to-Evacuate Sites

• “Difficult-to-evacuate” sites include schools (preschool to grade 12), state licensed day care 

centers, nursing homes, assisted living facilities, hospitals, in-patient clinics, and prisons. 

• No fumigant application with a buffer zone greater than 300 feet is permitted within 1⁄4 mile 

(1320 feet) of the sites listed above unless the site is not occupied during the application and 

the 36-hour period following the application. 

• No fumigant application with a buffer zone of 300 feet or less is permitted within 1/8 mile 

(660 feet) of the sites listed above unless the site is not occupied during the application and 

the 36-hour period following the application. 

(d) Buffer Zone Reduction Credits 

Requirements in the July 2008 RED 

In preparing for the July 2008 RED, the Agency undertook a significant effort to evaluate 

available empirical data results, modeling, and scientific studies reported in the literature 

regarding the factors and control methods that may reduce emissions from soil fumigants. For 

details on the Agency’s analysis, please see the June 9, 2008 memo, “Factors Which Impact Soil 

Fumigant Emissions - Evaluation for Use in Soil Fumigant Buffer Zone Credit Factor 
70

Approach,”4 in the metam-sodium and metam-potassium docket. The Agency also coordinated 

and led a discussion on this issue at the 2006 and 2007 Methyl Bromide Alternatives Outreach 

(MBAO) Conferences with leading researchers and other stakeholders. A general description of 

the MBAO sessions can be found at http://mbao.org. 

 Based on the Agency’s analysis of the current data, the Agency developed metamsodium and metam-potassium buffer zone reduction credits for: high-barrier tarps (10%), soils 

with high organic matter (10%), soils with high clay content (10%), and low-temperature soils 

(10%). The July 2008 RED stated that the buffer zone credits were additive, but that the total 

credit could not exceed 40 percent. The Agency believes that in addition to reducing bystander 

risk and the size of buffer zones, these credits have the potential to also decrease application 

rates. Applicators will be required to document any information about buffer zone credits that 

apply in the Fumigant Management Plan (FMP). 

Comments on the July 2008 RED 

Data were submitted since the July 2008 RED was issued that show greater reductions in 

emissions from the use of tarps and environmental conditions than what was determined in the 

July 2008 RED. In addition, the information submitted during the comment period indicated an 

additive effect in reducing emissions when multiple factors were combined. As a result, EPA has 

updated the buffer reduction credits and determined that the 40% credit cap should be increased 

to 80%. The new credits for individual factors and the cap on credits are detailed below. For 

details on the Agency’s analysis please see the May 14, 2009 memo; “Methyl Bromide (PC Code 

053201), Chloropicrin (PC Code 081501), Dazomet (PC Code 035602), Metam Sodium and 

Potassium (PC Codes 039003 & 039002), MITC (PC Code 068103), DP Barcode D362369, 

Updated Health Effects Division Recommendations For Good Agricultural Practices and 

Associated Buffer Credits,” in the metam docket. 

Soil Conditions

Soil conditions like the amount of organic matter and type of soil do have an impact on 

fumigant emissions. However, soil conditions differ from other credits because they are 

essentially beyond a grower’s ability to change. Although a grower may not be able to 

manipulate organic matter or soil type, the Agency’s factors document indicates that soil 

conditions can reduce fumigant emissions, and is offering credits for these conditions. EPA 

acknowledges that some variability in soil characteristics within a given field is likely. If users 

are unsure whether the fields they intend to treat meet the criteria for a credit, they may consult 

with their local agriculture extension office or soil conservation district for assistance in 

determining soil characteristics. 

The Agency’s factors document not only reviews available literature regarding soil 

conditions, but also describes modeling exercises that estimate the impact of organic matter and 

 

4

 Factors Which Impact Soil Fumigant Emissions - Evaluation for Use in Soil Fumigant Buffer Zone Credit Factor 

Approach, June 9, 2008, DP Barcode: 306857 
71

soil type using Chain_2D. Chain_2D is a first principles model that takes into consideration 

factors such as boundary layers or moisture that could impact fumigant emissions. The Agency 

used Chain_2D as modified by Dow AgroSciences’ Steve Cryer and Ian van Wesenbeek in the 

sensitivity analysis5. Cryer and van Wesenbeek modified the original source code to create a 

more usable graphical user interface; this included incorporating a new air/soil boundary 

condition proposed by Wang in 19986

. See the Agency’s factors analysis for further details 

about the CHAIN_2D model7

. 

Based on the review of available literature and modeling with the CHAIN_2D model, 

EPA believes 10 percent buffer zone credits are appropriate if the application block contains soil 

with organic matter of greater than 3 percent and/or for clay content of at least 27 percent. 

CHAIN_2D that shows the impact of changes in organic content is not fumigant specific. 

 

The Agency’s Chain_2D sensitivity analysis suggests that organic matter can have a 

small impact on emissions. There is generally a high correlation between the organic matter 

content of the soils and the dissociation constant (K d) value. Increasing K d value by 10 or 25 

percent generally reduced emissions by 10 or 20 percent. Decreasing the Kd value by 10 or 25 

percent increased emissions by 10 or 20 percent (see figures 147 to 154 of the factors analysis 

for further details). 

Generally, clay loam and sandy clay loam soils tended to show significantly lower 

emissions than other soil types, sometimes showing 50 percent lower reductions. Conversely, 

loamy sand and loam soils tended to show higher emissions than other soil types (see figures 167 

to 174 of the factors analysis for further details). 

Since the 2008 RED, information from the Chloropicrin Task Force has been submitted 

and has allowed the Agency to reevaluate credits for soil organic matter. From these studies the 

Agency has determined that soils with between 1% and 2% organic matter will get a 10% credit, 

soils with between 2% and 3% organic matter will get a 20% credit, and greater than 3%, a 30% 

credit. No credit will be given for soils with less than 1% organic matter. The credit for clay 

content of greater than 27% will remain at 10%. 

Soil Temperature

In the July 2008 RED, the Agency provided a 10% buffer zone credit for all chemigation, 

center pivot, and/or tractor drawn (i.e., shank injection, spray blade, and rotary tiller) application 

in soils with temperatures of 70°F or less when measured at a soil depth of 3 inches for all 

chemigation, center pivot, spray blade, and rotary tiller applications and at the injection depth for 

 

5

 Cryer, S.A. (2007) Air/Soil Boundary Conditions For Coupling Soil Physics and Air Dispersion Modeling. 

Unpublished report of Dow AgroSciences LLC (Report # DN241493)

6 Wang, D; Yates, S.R.; Jury, W.A. (1998) Temperature Effect on Methyl Bromide Volatilization: Permeability of 

Plastic Cover Films. J. Environ. Qual. 27, 821-827. 

7

 Factors Which Impact Soil Fumigant Emissions - Evaluation for Use in Soil Fumigant Buffer Zone Credit Factor 

Approach, June 9, 2008, DP Barcode: 306857 
72

shank injection applications. The Agency’s analysis of available data indicated increased soil 

temperature corresponds to increased fumigant emissions rates. Given that lower soil 

temperatures lead to lower fumigant emission rates, a credit was provided for application 

scenarios with lower soil temperatures. Because the emissions studies from which the buffer 

zones were developed for chemigation, center pivot, and tractor drawn applications all occurred 

at high air and soil temperatures, with maximum air temperatures (MATs) between 90-106°F 

and/or maximum soil temperatures (MSTs) between 90-93°F (where reported), a credit was 

given. Because the emissions studies used to develop buffer distances for the remaining 

application methods (i.e., drip and flood irrigation) occurred at lower temperatures, with MATs 

between 70-73°F and a MSTs of 70°F (where reported), an emission credit was not provided to 

reduce the buffers for these application methods. 

During the post-RED comment period, the Agency reviewed all of the currently available 

data on the effects of soil temperature on fumigant emissions. Based on this analysis, the Agency 

is providing an additional soil temperature credits as described below. 

Center Pivot and Shank Application 

The emissions studies used to currently develop buffer distances for metam sodium 

applications performed using center pivot and shank equipment occurred at high temperatures. 

The average day/night air temperature in these studies ranged from 80-90°F and the maximum 

soil temperatures ranged from 90-93°F (where reported). A 10% emission credit is being 

provided to reduce the buffers for these types of applications in soils with temperatures ranging 

from 50-70°F when measured at a soil depth of 3 inches. In addition a 20% emission credit is 

being provided to reduce the buffers for these types of applications in soils with temperatures of 

50°F or less when measured at a soil depth of 3 inches. 

Drip and Flood Irrigation and Rotary Tiller Applications

The emissions studies used to currently develop buffer distances for metam sodium 

applications performed using drip and flood irrigation as well as rotary tiller equipment occurred 

at reasonable temperatures. The average day/night air temperature in these studies was 

approximately 60°F and the maximum soil temperatures around 70°F (where reported). A 10% 

emission credit is being provided to reduce the buffers for these types of applications in soils 

with temperatures of 50°F or less when measured at a soil depth of 3 inches. 

Note: Stakeholders and the registrants have proposed a laboratory soil column study examining 

the effect of soil temperature and soil moisture on MITC emissions. This study may provide 

more information around the effect on MITC emissions and the emissions for metam-sodium and 

metam-potassium may be revisited if necessary after review of these data. 

High-Barrier Tarps
73

In the July 2008 RED, a 10% buffer credit was given when one of the following highbarrier tarps is used: Bromostop® (1.38 mil), IPM Clear VIF (1.38 mil), Eval/Mitsui (1.38 mil), 

Hytiblock 7 Black (0.00125”), XL Black Blockade (0.00125”), or Hytibar (1.5 mil) for either a 

shank injection or drip metam-sodium and metam-potassium application. Because current study 

data do not demonstrate significant reductions in MITC emissions using standard polyethelyne 

tarps, no credit was provided for “standard” tarped metam applications. The credit was based on 

a study (Papiernik 2004) that shows significant reductions in MITC emissions when using a 

Hytibar (a high-barrier) tarp when compared to a standard polyethylene tarp in drip irrigation 

experiments in both sand mesocosm and field experiments. Given that study data (Wang et al., 

2006) have shown that MITC and chloropicrin pass through standard tarps at similar rates, the 

Agency decided to allow emissions credits for the Hytibar tarp as well as the other high-barrier 

tarps that were given an emissions reduction credit for chloropicrin applications. The Agency 

believed that the actual reduction for tarps could be higher for certain conditions but that a 10% 

credit was appropriate based on uncertainties in the available data. 

Since the July 2008 RED was published, the Agency has looked at all of the available 

tarp data, in total. There is very limited data currently available that examines the ability of highbarrier tarps to reduce MITC emissions. One literature study (Papiernik et. al., 2004) showed 

significant reductions in MITC emissions when using a Hytibar (a high-barrier) tarp when 

compared to a standard polyethylene tarp in drip irrigation experiments. Also, another study 

(Wang et. al., 2006) showed that MITC and chloropicrin pass through standard tarps at similar 

rates (same order of magnitude). 

As a result, the Agency has decided to allow emissions credits for all high-barrier tarps 

that are being given an emissions reduction credit for chloropicrin. The Agency has selected 

more conservative credits for MITC based on uncertainties in the available data. 

• A 15% buffer credit is appropriate for the following high-barrier tarps: Canslit 

Heatstrip Silver and Canslit Metalized. 

• A 30% buffer credit is appropriate for the following high-barrier tarps: Olefinas 

Embossed VIF, Klerks VIF, Pliant Blockade, Bromostop® (1.38 mil), 

Eval/Mitsui TIF (1.38 mil), Hytiblock 7 Black (0.00125”), XL Black Blockade 

(0.00125”), Hytibar (1.5 mil), and IPM Clear VIF (1.38 mil). 

Credit Cap

The Agency determined, in the July 2008 RED, that the buffer zone credits were 

additive. This meant, for example, that a 10% credit for a high barrier tarp could be added to a 

10 % credit for organic matter to achieve a total credit of 20%. The Agency placed a limit, or 

“credit cap,” of 40% on the total size of the credit allowed for metam. During the comment 

period, the Agency received new data concerning a number of factors that impact fumigant 

emissions as well as a number of comments indicating that there should not be a cap on credits or 

that the cap should be raised. Some suggested that the 40% cap would be a disincentive to 

growers considering whether to adopt emission-reducing application methods. 
74

Upon review of the new data and public comments, the Agency has decided to raise the 

credits cap to 80%. The Agency has reviewed the new studies to evaluate the extent to which the 

various factors that reduce emissions act independently, and has reconsidered the earlier studies. 

As a result of this evaluation, the Agency concludes that credits be additive up to a cap of 80% 

for all fumigants. This revised credit cap is based on studies that show a greater-than-40% 

reduction in emissions when two or more factors are combined. Further, EPA believes that 

increasing the credit cap to 80% will encourage adoption of emission reduction techniques, result 

in lower off-site fumigant concentrations, and will allow for reduced application rates for various 

tarps. 

Credit Example 

If an application block is 10 acres and the applicator is planning to make a shank tarped 

application of 320 lbs of metam per acre, the buffer distance from the look up tables is 200 feet. 

If the applicator decides to use the Hytibar (1.5 mil) high barrier tarp, then the buffer zone may 

be reduced by 30 percent. By calculating 30 percent of 200 feet (200 feet x 30% = 60 feet buffer 

credit) and then subtracting the original buffer distance by the credit (200 feet – 60 feet = 140 

feet) the final buffer distance required is 140 feet. 

Other Buffer Zone Credits Considered 

Other factors such as soil moisture content, field preparation, water sealing, and 

application injection depth could not be quantified as to how effectively they reduce emissions 

and were not used to establish buffer credits at this time. However, EPA has established 

mandatory good agricultural practices (GAPs) for these conditions. If additional tarps or other 

emission factor data become available to show the emissions from metam-sodium and metampotassium applications are decreased, the Agency will consider adding those to the metamsodium and metam-potassium label. More information on the type of data the Agency is looking 

for can be found in the Health Effects Division Recommendations for Fumigant Data 

Requirements (J. Dawson, C. Smith, dated June 2008). 

EPA (through OPP’s Environmental Stewardship Branch) has proposed to co-fund a 

grant with USDA-ARS for several flux studies in the southeastern U.S. These studies would 

provide (1) field data on the emission reduction potential of certain low permeability barrier 

films to support possible, additional, buffer reduction credits as well as to (2) help develop an 

affordable and reliable hybrid field/lab test to evaluate the many barrier films available to 

growers. EPA has also prepared a document to describe possible research and study designs to 

reduce uncertainties in understanding emission factors in the context of different films and seals, 

agricultural practices, and environmental conditions.8

 These studies were completed in the 

spring of 2009 and data from these studies will be submitted to the Agency for review in the near 

future. 

 

8

 Health Effects Division Recommendations for Fumigant Data Requirements. June 2008. DP Barcode 353724 
75

Other factors such as soil moisture content, field preparation, water sealing, and 

application depth could not be used to justify credits based on the available data. However, EPA 

has established mandatory good agricultural practices (GAPs) for these conditions. See the GAP 

section of this document for further discussion. If additional data on such emission reduction 

methods becomes available, EPA will consider developing further credits. 

2. Restriction for Schools and Other Difficult To Evacuate Sites 

Certain types of sites are difficult to evacuate should an incident occur. EPA determined 

that additional measures to reduce the potential need to evacuate these types of sites were 

necessary to reduce risk of exposure to occupants and address potential challenges associated 

with an accident. There were many comments on this measure including: requests to delete this 

requirement; suggestions to reduce the size of the restricted area; a proposal to use a scalable 

approach to calculate the distance; requests to define and refine the places included on this list so 

that facilities such as research universities were excluded; suggestions to shorten the duration of 

the requirement so applicators may be able to take advantage of weekends to fumigate; questions 

about how to determine where these sites are located, and other suggestions to change the 

required measures. 

Based on a review of the comments, the Agency has retained this mitigation measure to 

ensure the protection goals are still achieved and encourage lower-emission application methods. 

The mitigation measures have been refined such that compliance is more effective in achieving 

the protection goal. Modifications to this requirement include: shortening the duration of the 

restriction so weekends may be used to fumigate near schools and day cares; clarifying the types 

of schools that are covered by this requirement; removing the term “elder care facilities” from 

the list since many of the same facilities are included in the terms, “ assisted living facilities, 

nursing homes, and in-patient clinics;” and reducing the restricted area from 1/4 mile to 1/8 mile 

for application blocks with less than 300 foot buffers. The 1/8 mile (660 feet) distance is more 

than twice the required buffer distance and remains protective of people who may be difficult to 

evacuate while reducing the potential challenges of complying with the restrictions for some 

users who may be fumigating in close proximity to these types of institutions. EPA has 

determined that these modifications achieve the same protection goals as the 2008 RED but 

provide additional clarity and flexibility that will enhance users’ ability to practically and 

effectively comply with the requirements. EPA also believes that reducing the restricted area for 

blocks with buffers less than 300 feet will provide an incentive for some users to adopt loweremission application methods or practices. The revised measures are summarized below. 

• “Difficult-to-evacuate” sites include schools (preschool to grade 12), state licensed day 

care centers, nursing homes, assisted living facilities, hospitals, in-patient clinics, and 

prisons. 

• No fumigant application with a buffer zone greater than 300 feet is permitted within 1/4 

mile (1320 feet) of the sites listed above unless the site is not occupied during the 

application and the 36-hour period following the start of application. 
76

• No fumigant application with a buffer zone of 300 feet or less is permitted within 1/8 

mile (660 feet) of the sites listed above unless the site is not occupied during the 

application and the 36-hour period following the start of application. 

3. Posting 

Posting is recognized as an effective means of informing workers and bystanders about 

areas where certain hazards and restrictions exist. Current soil fumigant labels require treated 

areas to be posted and handlers are required to wear specific PPE when they are in a treated area. 

For buffer zones to be effective risk mitigation, bystanders, including agricultural workers in 

nearby areas, need to be informed of the location and timing of the buffer zone to ensure they do 

not enter designated areas. 

In addition to alerting bystanders, posting a buffer zone will help handlers determine 

where and when they are required to use PPE. As described in the Handler Section, handlers 

working in treated areas or buffers during the buffer zone period must use label-specified PPE 

and meet other requirements under the Worker Protection Standard (WPS). Therefore, EPA has 

determined that to ensure the protectiveness of buffers for bystanders and handlers, the perimeter 

of the fumigant buffer zones must be posted. 

Comments received in response to the July 2008 RED decisions recommended some 

changes to the posting requirements to make them easier to understand and implement. Based on 

EPA’s review and consideration of these comments, EPA has slightly revised the posting 

requirements and provided additional clarification as described below. 

EPA had included two exceptions for the buffer zone posting requirement. The first 

exception did not require posting in situations where the land 300 feet from the edge of the 

buffer was under the control of the property operator. Based on comments that this measure was 

too complicated and confusing this exception has been removed. There were also comments that 

the examples provided in the description of a physical barrier may lead to misinterpretation of 

the requirement. EPA agrees and believes that a performance standard is a more effective means 

of communicating the requirement. Therefore, to reduce the potential for confusion, the 

examples have been removed. 

In the 2008 RED, signs were required to be posted at usual points of entry and likely 

routes of approach to buffer zones. If there were no usual points of entry or likely routes of 

approach, then posting was required in the corners of buffer zones, and between the corners, so 

signs could be viewed from one another. Many comments expressed concern over the burden 

and potential confusion with the number of signs that may need to be posted and how many signs 

may need to be posted depending on the configuration of the field. EPA agrees that signs posted 

in areas where there is low likelihood of workers or others approaching or accessing the buffer 

provide little risk reduction, but can add substantially to the challenges of compliance. As a 

result, the Agency has revised the criteria for location of signs since the areas that are of most 
77

concern are those where people are most likely to enter (e.g., roads, footpaths, etc.), and at likely 

routes of approach such as the perimeter of a buffer that faces a housing development. 

Comments also indicated that the requirement to include certain application-specific 

information on the posted signs would make reuse of the signs more difficult and would also 

substantially increase the amount of time needed to prepare signs before posting. These 

comments stated that the primary purpose of signs is to communicate to bystanders the buffer 

zone locations. EPA generally agrees with these comments; therefore certain applicationspecific details on the posted signs, like the date and time of the fumigation and buffer zone 

restrictions, have also been reduced to allow the signs to be reused more easily. 

Comments also stated that the posting example included in the 2008 RED was confusing. 

Since the posting restrictions have been simplified by removing the distance criteria, the example 

has been removed from this document. There were no substantive comments suggesting a 

change to the exception for posting multiple contiguous blocks and no changes have been made 

in this Amendment. 

The revised posting requirements are listed below and have been included in the revised 

label table. 

Requirements 

• Posting of a buffer zone is required unless there is a physical barrier that prevents 

bystander access to the buffer zone. 

• Buffer zone posting signs must: 

o Be placed at all usual points of entry and along likely routes of approach from areas 

where people not under the land operator’s control may approach the buffer zone. 

o Some examples of points of entry include, but are not limited to, roadways, 

sidewalks, paths, and bike trails. 

o Some examples of likely routes of approach are the area between a buffer zone and a 

roadway, or the area between a buffer zone and a housing development. 

• Buffer zone posted signs must meet the following criteria: 

o The printed side of the sign must face away from the treated area toward areas from 

which people could approach. 

o Signs must remain legible during entire posting period and must meet the general 

standards outlined in the WPS for text size and legibility (see 40 CFR §170.120). 

o Signs must be posted before the application begins and remain posted until the buffer 

zone period has expired. 

o Signs must be removed within 3 days after the end of the buffer zone period. 

o Registrants must provide generic buffer zone posting signs which meet the criteria 

above at points of sale for applicators to use. 
78

Exception: If multiple contiguous blocks are fumigated within a 14-day period, the entire 

periphery of the contiguous blocks’ buffer zones may be posted. The signs must remain posted 

until the last buffer zone period expires and signs may remain posted until 3-days after the buffer 

zone period for the last block has expired. 

Additional requirements for treated-area posting: 

• The treated area posted signs must remain posted for no less than the duration of the entry 

restricted period after treatment. 

• Treated area signs must be removed within 3 days after the end of the entry-restricted 

period. 

• Signs must meet the general standards in the WPS for placement, text size, and location 

(40 CFR §170.120). 

Contents of Signs 

The treated area sign (currently required for 

fumigants) must state the following: 

-- Skull and crossbones symbol 

 

-- "DANGER/PELIGRO," 

-- "Area under fumigation, DO NOT 

ENTER/NO ENTRE," 

-- "Metam-Sodium or Metam-Potassium 

Fumigant in USE," 

-- the date and time of fumigation, 

-- the date and time entry prohibition is lifted 

-- Name of this product, and 

-- name, address, and telephone number of the 

certified applicator in charge of the fumigation. 

The buffer zone sign must include the 

following: 

-- Do not walk sign 

-- "DO NOT ENTER/NO ENTRE," 

-- "Metam-Sodium or Metam-Potassium 

[Name of product] Fumigant BUFFER 

ZONE,” 

-- contact information for the certified 

applicator in charge of the fumigation 

bb. Occupational Risk Mitigation for Soil Uses 

 

The Agency has concerns for handlers involved in metam-sodium and metam-potassium 

applications for both dermal and inhalation exposure. In many cases with maximum personal 

protective equipment (PPE), exposure still exceeds the Agency’s level of concern for short-term 

and long-term exposures. Based on stakeholder comments, there appears to be a 

misunderstanding as to what EPA considers to be handler activities. 

Because the metam sodium/potassium registrants have not indicated that they support the 

following uses for metam sodium/potassium: (1) use in greenhouses, (2) use in treating potting 
79

soil (e.g., cement grinder and shredder uses); (3) handheld uses, including sprinkler can and 

hose-end proportioners/sprayers; and (4) open-pour applications (e.g., treatments for Dutch Elm 

Disease and Oak Wilt, treatment of orchard replant sites), the metam sodium/potassium labels 

will be revised such that these uses are not permitted. 

1. Handler Definition 

Based on stakeholder comments provided during the Phase 5 comment period, the July 

2008 RED clarified fumigation tasks that meet EPA’s definition of handler activities, as 

currently defined in the WPS and on fumigant labels. During the post-RED comment period the 

Agency received some comments from stakeholders who were concerned that the Agency was 

redefining handlers. It was not the Agency’s intention to change the current definition. As a 

result, the Agency has slightly changed the language from July 2008 RED so it is clear that the 

Agency is just clarifying the existing definition and not writing a new one. Below is the revised 

language. 

“The following activities are prohibited from being performed in the fumigant application 

block or surrounding buffer zone during the buffer zone period by anyone other than persons 

who have been appropriately trained and equipped as handlers in accordance with the 

requirements in the Worker Protection Standard (40 CFR Part 170), from the start of the 

application until the entry-restricted period ends. Those activities include those persons: 

• Participating in the application as supervisors, loaders, drivers, tractor co-pilots, 

shovelers, cross ditchers, or as other direct application participants (note: the application 

starts when the fumigant is first introduced into the soil and ends after the fumigant has 

stopped being delivered/dispensed to the soil); 

• Using devices to take air samples to monitor fumigant air concentrations; 

• Persons cleaning up fumigant spills (this does not include emergency personnel not 

associated with the fumigation application); 

• Handling or disposing of fumigant containers; 

• Cleaning, handling, adjusting, or repairing the parts of fumigation equipment that may 

contain fumigant residues; 

• Installing, repairing, or operating irrigation equipment in the fumigant application block 

or surrounding buffer zone during the buffer zone period; 

• Entering the application site or surrounding buffer zone during the buffer zone period to 

perform scouting or crop advising tasks; 

• Installing, perforating (cutting, punching, slicing, poking), removing, repairing, or 

monitoring tarps: 

o until 14 days after application is complete if tarps are not perforated and removed 

during those 14 days, or 

o until tarp removal is complete if tarps are both perforated and removed less than 

14 days after application; or 
80

o until 48 hours after tarp perforation is complete if they will not be removed within 

14 days after application. 

o In addition, to the above, persons outside the perimeter of the buffer zone who visually 

monitor application equipment to ensure proper functioning and monitor fumigant air 

concentrations must also be trained and equipped as handlers in accordance with the 

requirements in the WPS (40 CFR Part 170).” 

2. Handler Requirements 

Since many incidents are caused by human error and equipment failure, EPA believes the 

presence of on-site trained personnel would help to reduce these risks. To address these risks, 

the July 2008 RED required that (1) a certified applicator must supervise all fumigant handlers 

during the entire period that the person is performing a fumigant handling task within the treated 

field or within the buffer zone, (2) the person monitoring another handler could also be engaged 

in fumigant handling tasks during the monitoring period, and (3) the certified applicator 

supervising metam-sodium and metam-potassium applications could perform all tasks without 

anyone supervising them. 

The July 2008 Metam-Sodium and Metam-Potassium RED included exceptions for the 

on-site applicator supervision requirements in cases when the certified applicator typically leaves 

the site during an application. Requirements in the RED label table specified that for overhead, 

flood, or furrow irrigation and chemigation applications, the certified applicator supervising the 

fumigant application must be on site at the start of application but may leave and return for 

periodic monitoring of the fumigation site as long as he/she monitors the site at least once every 

four hours if the site is 20 acres or less; once every three hours if the site is greater than 20 acres, 

but less than 80 acres; and once every two hours if the site is 80 acres or more. The Agency 

believes that consistent monitoring of water-run applications (e.g., drip, overhead, flood, or 

furrow irrigation and chemigation) is needed to help reduce potential risks during an application. 

In addition to certified applicator supervision, in the July 2008 RED, the Agency required 

that a minimum of two WPS-trained handlers remain on site when handlers are fixing tarps, 

moving irrigation equipment, and/or performing other handler tasks as defined above. This 

mitigation measure was put in place to address the possibility that handlers could be overcome 

with the vapors and have difficulty leaving the area while they are performing these tasks. The 

Agency is removing this handler requirement for the MITC generating chemicals since the 

hazard profiles are not the same for all the soil fumigants. With MITC-generating compounds, 

EPA believes eye or sensory irritation would likely be felt in sufficient time for a handler to 

leave the area or put on a respirator, before more serious effects occur. With chloropicrin, in 

contrast, as indicated by precautionary statements on current labels, a handler may be overcome 

more quickly, justifying the presence of another person to provide assistance if needed. 

During the post-RED comment period the Agency received many comments that stressed 

the difficulty implementing a requirement that mandates certified applicators to maintain visual 

contact with handlers. The commenters also indicated that for longer applications this 
81

requirement would be a huge burden. Other stakeholders stated that the Agency needs to modify 

the requirement to ensure that the certified applicator is on site while others believe EPA should 

require that all handlers are certified applicators, which would eliminate the need for direct 

handler supervision. 

The Agency has considered the comments and has revised the certified applicator and 

WPS-trained handler requirements for different application methods. EPA believes that these 

revisions accomplish the same goal as the July 2008 RED mitigation while reducing the burden 

on users. 

• For all applications, except water run, (e.g., shank, rotary tiller, etc.) from the start of the 

application until the fumigant has stopped being delivered/dispensed into the soil, i.e., 

after the soil is sealed, the certified applicator must be at the fumigation site and must 

directly supervise all persons performing handling activities. 

• For water-run applications (e.g., chemigation, center pivot, lateral move, drip, overhead, 

flood, furrow irrigation, etc.), the certified applicator must be at the fumigation site to 

start the application including set-up, calibration, and initiation of the application. The 

certified applicator may leave the site but must return at least every two hours to visually 

inspect the equipment to ensure proper functioning and monitor the air around the buffer 

zone and must supervise all WPS-trained handlers on-site until the fumigation has 

stopped being delivered/dispersed into the soil. WPS-trained handlers may perform the 

monitoring functions in place of the certified applicator but must be under the supervision 

of the certified applicator and able to communicate with the certified applicator at all 

times during monitoring activities via cell phone or other means. The results of 

monitoring activities must be captured in the FMP. 

• For fumigant handling activities that take place after the fumigant has been 

delivered/dispensed into the soil until the entry restricted period expires, the certified 

applicator does not have to be on-site, but must have communicated in writing to the site 

owner/operator and handlers the information necessary to comply with the label and 

procedures described in the FMP (e.g., emergency response plans and procedures). 

The July 2008 RED also required that certified applicators supervising the application 

completed a metam-sodium and metam-potassium registrant training program within the 

preceding 12 months before they applied a metam-sodium and metam-potassium product. The 

Agency is still requiring certified applicators complete the registrant training; however, the 

Agency is now requiring the certified applicators successfully complete the training every three 

years. Please see the Soil Fumigation Training for Applicators and Other Handlers section for 

further. 

3. Dermal Protection for Handlers 

The Agency’s human health risk assessment for metam-sodium and metam-potassium 

identifies dermal risks for many handler tasks that exceed the Agency’s level of concern for 

short-term, and intermediate-term exposures to the parent metam-sodium and metam-potassium. 

To address these dermal risk concerns, in the July 2008 Metam-Sodium and Metam-Potassium 
82

RED, the Agency required handlers engaged in various tasks (e.g., transferring or loading 

liquids; operating motorized ground application equipment with open cabs; and cleaning up 

spills) to wear dermal protection (e.g., double layer clothing, chemical resistant footwear plus 

socks) to protect against dermal exposure. 

 During the post-RED comment period, the Agency received a comment from the 

Northwest Horticultural Council indicating that the primary application method for orchard 

replant using metam sodium in the Pacific Northwest, a row/strip treatment of metam sodium to 

a future tree row using a weed sprayer while irrigation sprinklers are running, was not 

specifically addressed in the Agency’s RED decision. Based on additional information provided 

by a representative for the Council in a 3/13/08 e-mail to the Agency (a copy of this e-mail has 

been posted to the metam sodium docket at EPA-HQ-OPP-2005-0125), EPA is including this 

application method, provided that handlers wear the following dermal PPE to protect them from 

both the product and sprinkler irrigation: long-sleeved shirt and long pants; a full waterproof, 

chemical-resistant suit; chemical-resistant gloves; chemical-resistant footwear plus socks; and 

protective eyewear. Generally, the Agency does not like to require the use of full waterproof, 

chemical-resistant suits for handlers, given concerns regarding heat stress for handlers, especially 

for handheld applications. However, based on the comments submitted by the Council indicating 

that this PPE is currently a standard practice and these applications are likely occurring in a 

cooler weather climate, the Agency is requiring such PPE in this instance. 

The majority of comments relating to dermal handler protection for metam-sodium and 

metam-potassium that the Agency received during the post-RED comment period involved the 

need for additional clarification of key dermal handler mitigation and risk concerns. Specifically, 

clarification of the “baseline work clothes” requirement was requested. The Agency has more 

clearly defined this term in the dermal requirements section below to avoid any potential 

confusion. 

Additionally, during the post-RED comment period, the Agency received comments from 

various stakeholders indicating that the Agency had not fully characterized the dermal risks from 

metam-sodium and metam-potassium, specifically short-term and intermediate-term non-cancer 

and cancer dermal risks in the July 2008 Metam-Sodium and Metam-Potassium RED. To address 

these concerns, the Agency is providing additional characterization of these risks below. 

Metam-Sodium and Metam-Potassium Non-Cancer Occupational Dermal Risks: Short-Term 

and Intermediate-Term 

The results of the non-cancer, short-term and intermediate-term handler dermal exposure 

assessments indicate that the MOEs for the dermal risk to handlers with both full PPE (i.e., 

gloves and double-layer clothing) and/or engineering controls (i.e., closed mixing and loading 

systems and use of enclosed cabs) are above the Agency’s level of concern (LOC) (i.e., MOE < 

100) for many of the agricultural scenarios. The estimated exposures and risks are summarized in 

Tables 1-4 in Appendix J of the third revision of the Agency’s human health risk assessment. To 
83

view, please see, “Metam Sodium: Third Revision of the HED Human Health Risk Assessment, 

DP# 293354 located in the metam sodium docket at: EPA-HQ-OPP-2005-0125. 

For short-term hander exposure scenarios, the margins of exposure (MOEs) for handlers 

loading metam products at higher application rates for large acreage applications exceed the 

Agency’s level of concern even with the addition of maximum personal protective equipment 

(PPE). This is also true for applicators who are applying metam products at higher application 

rates for large acreage applications. However, for many of the short-term handler exposure 

scenarios, when loading metam products for more typical acreage applications at typical 

application rates, MOEs are below the Agency’s level of concern when additional PPE and/or 

engineering controls are incorporated. For applicators, when treating typical acreage at more 

typical application rates, MOEs are below the Agency’s level of concern with additional PPE or 

when using a closed cab that provides dermal protection. 

For intermediate-term exposures, the MOEs for handlers for the dermal risk to handlers 

with both full PPE (e.g., gloves and double-layer clothing) and/or engineering controls (e.g., 

closed mixing and loading systems) exceed the Agency’s LOC (i.e., MOE < 100) for the 

majority of the agricultural scenarios. 

Short- and intermediate-term dermal exposure MOEs for many handler scenarios are 

below an MOE of 100 with the required dermal protection and/or engineering controls. The 

occupational dermal risk assessments are based on data from the Pesticide Handler Exposure 

Database (PHED) and Outdoor Residential Exposure Task Force (ORETF). PHED and ORETF 

were designed to be used to assess nonvolatile pesticides. In the case of metam-sodium and 

metam-potassium, these data were used because there are no chemical-specific data available to 

the Agency. Since metam-sodium and metam-potassium degrades quickly to MITC, the dermal 

short- and intermediate-term risk assessment for metam generated by the Agency using data 

from PHED and ORETF can be considered to be conservative. 

For the intermediate-term dermal exposures, another source of conservatism comes from 

the assumption that workers are exposed throughout an 8-hour workday for a 1- 6 month period. 

However, the Agency believes that many handlers, particularly private applicators of metam 

sodium, typically apply metam-sodium and metam-potassium for much shorter periods of time. 

In a 2004 survey of growers and applicators that use metam sodium conducted by the Metam 

Sodium Alliance and reviewed by the Agency, average number of days per year that growers 

reported potential metam exposure was 15 days, while custom applicators had an average of 50 

days per year. 

To address the short- and intermediate-term dermal risks from metam-sodium and 

metam-potassium, consistent with the mitigation required in the July 2008 RED, the Agency is 

requiring handlers engaged in various tasks to wear dermal protection to protect against dermal 

exposure. Given the conservative nature of the non-cancer short- and intermediate-term dermal 

exposure assessment, coupled with the Agency’s dermal PPE requirements and engineering 

control requirements, which are detailed below in the dermal requirements section, the Agency 
84

believes that these measures are protective of possible short-term and intermediate-term dermal 

risks for metam-sodium and metam-potassium. 

Metam-Sodium and Metam-Potassium Cancer Occupational Risks: Dermal Exposures

The Agency’s metam-sodium and metam-potassium cancer occupational handler dermal 

exposure assessment indicates that cancer risks for both noncommercial and commercial 

handlers are above the Agency’s LOC (ranging from 1x10-4 to 1x10-6) for the majority of 

agricultural scenarios with maximum PPE in place. This assessment should be considered 

conservative for a number of reasons. (1) The assessments were based on data from PHED and 

ORETF, which are generally meant to assess non-volatile pesticides. Using this data to assess 

dermal exposure to metam sodium should be considered very conservative due to the volatile 

nature of metam sodium. (2) Closed systems are used to mix and load metam-sodium and 

metam-potassium, which will greatly reduce any potential exposure to metam-sodium and 

metam-potassium itself. (3) Much of the equipment typically used to apply metam-sodium and 

metam-potassium also greatly reduces any potential exposure to metam-sodium and metampotassium itself. Tractor applications of metam sodium either immediately incorporate or 

directly inject metam sodium into the ground, and handlers are typically not in the field during 

chemigation applications. 

Dermal Requirements 

The Agency is requiring the mitigation measures specified below to reduce dermal 

exposures for handlers. Where indicated, “baseline work clothes” refers to long-sleeved shirt, 

long pants, and socks and shoes. 

• Transferring Liquids

o To reduce risk to handlers who transfer liquids from any container into 

application equipment or delivery equipment, the following is required: 

 Double-layer clothing (i.e., baseline work clothes and coveralls), 

chemical-resistant gloves, chemical-resistant apron, chemical-resistant 

footwear plus socks, and protective eyewear. 

o To reduce risk to handlers who transfer liquids from any container into 

application equipment or delivery equipment using a closed-connect system that 

reduces leakage to less than 2 ml of liquid per disconnect, the following is 

required: 

 Baseline work clothes, chemical resistant gloves, chemical resistant apron, 

protective eyewear, and a closed-connect system. 

• Driving Ground Rigs: 

o To reduce risk to handlers driving ground rig with a closed cab that provides 

dermal protection, the following is required: 

 Baseline work clothes. 
85

o To reduce risk to handlers driving a ground rig that does not provide dermal 

protection, the following is required: 

 Double-layer clothing (i.e., baseline work clothes and coveralls) and 

chemical-resistant footwear plus socks.

• Set-up, Calibration, and Start Up of Chemigation Equipment: 

o To reduce risk to handlers who set-up and calibrate chemigation and irrigation 

equipment and start the application from inside the buffer zone, the following is 

required: 

 Baseline work clothes and protective eyewear. 

• Row/Strip Treatment Application of Metam Sodium via Weed Sprayer while Irrigation 

Sprinklers are Running: 

o To reduce risk to handlers who apply metam-sodium and metam-potassium via 

weed sprayer while irrigation sprinklers are running for row/strip treatment for 

orchard replant, the following is required: 

 Long-sleeved shirt and long pants; chemical-resistant gloves; full 

chemical-resistant coveralls and chemical-resistant footwear plus socks; 

and protective eyewear. 

• Early Entry or Monitoring PPE: 

o To reduce risk to handlers (1) entering a treated area during the application or (2) 

entering the treated field up to 120 hours after the application has ended for any 

reason (including, but not limited to, equipment repair, cleaning up spills, 

equipment monitoring, scouting), or (3) entering the buffer zone for up to 48 

hours after the application, the following is required: 

 Baseline work clothes. If the handler will to be exposed to liquid or liquid 

spray from the application equipment, they must wear full chemicalresistant coveralls, chemical-resistant gloves, chemical- resistant apron, 

chemical resistant footwear plus socks, and protective eyewear. 

4. Respiratory Protection for Handlers 

The Agency’s human health risk assessment for metam indicates that inhalation risks for 

many handler tasks exceed the Agency’s LOC for the acute exposure to the parent (metam) and 

MITC. In the 2008 Metam-Sodium and Metam-Potassium RED, the Agency required handlers 

potentially exposed to MITC vapors from metam-sodium and metam-potassium applications to 

either wear at least a half-face respirator during the handling activity, or follow the monitoring 

program detailed below. In addition, the Agency required that for some handling tasks, 

respirators were required to be worn at all times due to the short duration of the task and the 

potentially high concentration of MITC exposure. The certified applicator supervising the 

fumigant application must ensure that any handler who enters the buffer zone (including tractor 

drivers, loaders, irrigators, tarp cutters, removers, etc.) is either wearing respiratory protection or 
86

is following the handler monitoring requirements, with respirators immediately available to each 

handler. 

During the post-RED comment period, the Agency received several comments on the 

Respiratory Protection for Handlers section. For MITC, comments focused on the feasibility of 

using colorimetric tubes, due to the current sensitivity and accuracy of the tubes; the cost of the 

tubes; and the Agency’s trigger level of 100 ppb, which some commenters questioned, given that 

the Agency’s level of concern for acute MITC exposures is 22 ppb. Some comments also 

suggested that rather than wear respirators, fumigators should have the option of ceasing the 

application until air concentrations of MITC are less than the action level. 

After reviewing the comments, the Agency has determined that respiratory protection is 

still needed to mitigate risks to metam-sodium and metam-potassium handlers if concentrations 

of MITC reach a certain level. EPA is requiring at least a NIOSH-approved full-face respirator 

and is also revising the required procedures for determining when respirators must be used due to 

technological limitations of currently available monitoring devices that are appropriate for field 

use. EPA believes that while colorimetric tubes are likely to be reliable at higher concentrations 

and when used in more static conditions (e.g., a warehouse or laboratory), under the dynamic 

conditions characteristic of outdoor field fumigation, currently available devices provide 

somewhat less reliable information about concentrations relative to EPA’s action level, which is 

below the levels for which the devices are rated. 

The Agency is aware of several commercial systems for monitoring MITC, including 

colorimetric tubes from the following manufacturers: Sensidyne and Dragaer. While these tubes 

have detection limits of at least 100 ppb, based on commenters’ experience and the accuracy of 

the tubes (e.g., some tubes have a standard deviation plus or minus 20-30%), the Agency 

believes it is possible that handlers will experience sensory irritation before the monitoring 

device shows a level of concern. As such, the Agency does not believe that initial monitoring to 

trigger the use of respirators significantly reduces handler risks. EPA is also concerned that 

monitoring with devices that are not reliable could cause handlers to believe that concentrations 

are below the action level despite other indications (eye irritation). As a result, the Agency is 

removing the initial monitoring requirement. In addition, EPA is aware that monitoring with 

these devices adds significant costs to fumigations. For additional details please see the 

following document: Analysis of Soil Fumigant Risk Management Requirements using 

Geographic Information Systems: Case Studies based on a Forest Seedling Nursery, dated May 

13, 2009, located in the metam docket. 

EPA does believe, however, that monitoring devices that are currently available will 

generally be reliable at higher concentrations of MITC and that there is high value in air 

monitoring using currently available devices in certain situations. As a result, EPA is 

maintaining the requirement for colorimetric tube monitoring once use of respirators has been 

triggered and respirators are being worn. This will enable handlers to detect concentrations that 

would exceed the upper working limit of the respirator. Additionally monitoring will still be 

required to help enable handlers to determine if concentrations have decreased and whether it is 
87

safe to either remove respirators or to resume the application if the fumigator has opted to cease 

the application rather than wear respirators. 

The Agency is modifying the procedures for respiratory protection because of 

technological limitations of currently available devices. However, the Agency does believe that 

quantitative air monitoring would enhance worker safety if the appropriate technology were 

available. Some equipment manufacturers have indicated interest in developing devices that 

would be more functional and reliable for field fumigation applications (e.g., badge-type 

monitors). EPA encourages such efforts and plans to stay abreast of developments and 

improvements in monitoring devices and will consider this issue again in registration review or 

sooner should such monitors become available in the short term. 

Since the Agency has removed the initial monitoring requirement, regulating at an action 

level of 100 ppb is no longer appropriate since that level was based on the lowest detection limit 

of the currently available MITC monitoring tubes. Due to the reliability issue discussed above, 

instead, the Agency is using an action level of 600 ppb which corresponds to early signs of 

exposure and effects are non-severe and reversible at this level. The Agency believes that this 

level is effective as a warning for handlers of when concentrations are reaching the point where 

steps are needed to protect fumigant handlers from inhalation exposures. 

Respiratory Requirements 

The following procedures must be followed for all agricultural pre-plant soil applications 

of metam-sodium and metam-potassium. In addition to the respiratory protection requirements, 

the Agency believes that GAPs, FMPs, and other mitigation measures will reduce inhalation 

risks from MITC to levels below the EPA’s level of concern. 

• If at any time any handler experiences sensory irritation (tearing, burning of the eyes or 

nose) then either: 

o A NIOSH-approved full-face respirator with organic vapor cartridge must be 

worn by all handlers who remain in the application block and surrounding buffer 

zone, or 

o Operations must cease and handlers not wearing respiratory protection must leave 

the application block and surrounding buffer zone. 

• Handlers can remove respirators or resume operations if two consecutive breathing-zone 

samples taken at the handling site at least 15 minutes apart show that levels of MITC 

have decreased to less than 600 ppb, provided that handlers do not experience sensory 

irritation. Samples must be taken where the irritation is first experienced. 

• When respirators are worn, then air monitoring samples must be collected at least every 2 

hours in the breathing zone of a handler performing a representative handling task. 

• If at any time: (1) a handler experiences any sensory irritation when wearing a respirator, 

or (2) an air sample is greater than or equal to 6000 ppb, then all handler activities must 

cease and handlers must be removed from the application block and surrounding buffer 

zone. If operations cease the emergency plan detailed in the FMP must be implemented. 
88

• Handlers can resume work activities without respiratory protection if two consecutive 

breathing-zone samples taken at the handling site at least 15 minutes apart show levels of 

MITC have decreased to less than 600 ppb, provided that handlers do not experience 

sensory irritation. 

• During the collection of air samples a respirator must be worn by the handler taking the 

air samples. Samples must be taken where the irritation is first experienced. 

• Work activities may resume if the following conditions exist provided that the 

appropriate respiratory protection is worn: 

o Two consecutive breathing zone samples for MITC taken at the handling site at 

least 15 minutes apart must be less than 600 ppb, 

o Handlers do not experience sensory irritation while wearing the APR, and 

o Cartridges have been changed. 

o During the collection of air samples a respirator must be worn by the handler 

taking the air samples. Samples must be taken where the irritation is first 

experienced. 
89

Figure 3. Provides an illustration of the requirements when handlers cease operations. 

Handler activity begins. Handlers 

are NOT wearing APRs. 

Sensory Irritation 

Certified applicator in charge 

decides to cease operations rather 

than continue with respirators. 

Handlers must stop work and 

leave application block and buffer 

zone. 

If 2 samples taken at least 15 

minutes apart (by a handler 

wearing an APR) show 

concentrations are less than 600 

ppb and NO sensory irritation, 

then 

Resume operations. 
90

Figure 4. Provides an illustration of the requirements when handlers put on a respirator. 

Handler activity begins. Handlers 

are NOT wearing APRs. 

Sensory Irritation 

Certified applicator in charge 

decides to continue operations. 

All handlers in the application 

block and buffer zone put on an 

APR. Air monitoring program 

begins. 

Feel irritation through APR, OR 

monitoring indicates 

concentrations above 6000 ppb. 

Handlers must stop work and 

leave application block and buffer 

zone. 

If, 2 consecutive samples taken at 

least 15 minutes apart, by a 

handler wearing an APR are 

above 600 ppb BUT below 6000 

ppb, no sensory irritation is felt, 

and the cartridge is changed, then

If 2 consecutive samples taken at 

least 15 minutes apart, by a 

handler wearing an APR, are less 

than 600 ppb and NO sensory 

irritation, then 

Resume operations wearing an 

APR. Air monitoring continues. 

Resume operations without an 

APR or remove respirator. 
91

Respiratory Protection Equipment

In the July 2008 RED, the Agency required handlers to wear an air purifying respirator 

approved for MITC. For additional clarity, even though currently there are no air-purifying 

respirator cartridges certified by the Mine Safety and Health Administration-National Institute 

for Occupational Safety and Health (MSHA-NIOSH) for protection against MITC, 

NIOSH/OSHA does recommend respirators with organic vapor cartridges for MITC use, and the 

Agency is requiring at least a full-face respirators with organic-cartridges be used when a 

respirator is necessary; the Agency will consider other APR-cartridges combinations provided 

written certification of their efficacy against MITC is provided to the Agency. The EPA assumes 

that respirators have a protection factor of 10, therefore, the respiratory protection will only be 

protective up to MITC concentrations of 6000 ppb, and if concentrations exceed 6000 ppb (or if 

eye irritation occurs), operations must cease. At air concentrations greater than 6000 ppb, the 

respirator is not designed to protect handlers from inhaling more than 600 ppb of MITC. 

Therefore, the handler must continue to monitor once respirators are donned. If concentrations 

of MITC exceed 6000 ppb or if eye irritation occurs, then the operations must cease until levels 

of MITC are measured to be below 600 ppb from consecutive air samples. 

The Agency did receive comments regarding the cartridge recommendations, the 

recommended equipment, and the assumed respirator protection factor. All of these comments 

are addressed in detail in the following document located in the metam-sodium and metampotassium docket: Methyl Bromide, 1,3-Dichloropropene, Chloropicrin, Dazomet, Metam 

Sodium/Potassium, MITC: Health Effects Division (HED) Component of Agency Response To 

Comments On 2008 Reregistration Eligibility Documents (Dated May 14, 2009). The Agency 

would like to clarify issues regarding the respiratory protection cartridges and respirators. 

Comments suggested that the Agency require organic-vapor cartridges. This was the Agency’s 

intention in the July 2008 RED. Others commented on the use of full-face respirators and 

goggles. The Agency is requiring at least a NIOSH-approved full-face respirator with an 

organic-vapor cartridge when respirators are required. 

Respirator fit testing, training, and medical qualification

As detailed in the July 2008 RED, the respirator protection factor described above in the 

Respiratory Protection Equipment section is based on the following assumptions: 1) the 

respirator is fit-tested, 2) proper respirator training occurs, and 3) an annual medical evaluation 

and clearance is completed. Without these requirements, it is unclear whether the reduction in 

inhalation exposure that is assumed by the protection factor will be achieved. In order to ensure 

that the respiratory protection EPA is assuming is being achieved in the field, respiratory 

requirements will include fit testing, respirator training, and annual medical evaluation. 

During the post-RED comment period, the Agency received a variety of comments 

ranging from full support of the requirement, to comments about the cost and time burden 

associated with the requirement. The Agency also received several comments regarding the 
92

details of this requirement, for example who conducts the fit-testing and medical exam and what 

the medical exam entails. 

While EPA recognizes that there is a cost associated with the fit-testing, training, and 

medical exam requirement the Agency still believes that respirator fit-testing, training, and 

medical exams are a necessary part of the mitigation package. Since the Agency is now offering 

a cease operations option where handlers can leave the application block and surrounding buffer 

zone in lieu of putting on a respirator, the Agency is only requiring that handlers who wear a 

respirator are fit-tested, trained, and medically examined. The Agency believes that this revision 

will reduce the cost associated with this requirement while still keeping the same level of 

protection for the handlers that wear respirators. The following language must be added to 

product labels: 

“Employers must also ensure that any handler that uses a respirator is: 

• Fit-tested and fit-checked using a program that conforms to OSHA’s requirements (see 29 

CFR Part 1910.134) 

• Trained using a program that confirms to OSHA’s requirements (see 29 CFR Part 1910.134) 

• Examined by a qualified medical practitioner to ensure physical ability to safely wear the 

style of respirator to be worn. A qualified medical practitioner is a physician or other 

licensed health care professional (PLHCP) who will evaluate the ability of a worker to wear a 

respirator. The initial evaluation consists of a questionnaire that asks about medical 

conditions (such as a heart condition) that would be problematic for respirator use. If 

concerns are identified, then additional evaluations, such as a physical exam, might be 

necessary. The initial evaluation must be done before respirator use begins. It does not need 

to be repeated unless the health status or respirator use conditions change.” 

Respirator availability 

The handler employer must confirm and document in the FMP that enough respirators 

and cartridges are available for each handler that wears a respirator. The Agency is requiring 

that at minimum one handler must have the appropriate respirator and cartridges available and 

that the handler is fit-tested, trained, and medically examined. 

Tarp Repair

The July 2008 RED required handlers to wear APRs if they perform tarp repair 

operations before the entry-restricted period has ended. The requirements were different from 

other handling activities because the duration of tarp repair activities was believed to be shorter 

than other handling tasks and therefore tarp repair activities would not trigger the initial 

monitoring requirement. Upon consideration of comments the Agency received on this 

requirement, EPA has determined that respiratory protection for tarp repair activities should be 

handled consistently with other handler activities, i.e., handlers repairing tarps are not required to 

wear respirators unless sensory irritation is experienced. Additionally, the Agency believes that 

tarp repair like other handling activities described above would benefit from the development of 
93

sensitive monitoring devices to reliably inform handlers if and when concentrations are above 

the action level for respiratory protection. EPA will reevaluate this measure during Registration 

Review or sooner if such devices are available in the short term. 

5. Tarp perforation and removal 

The Agency’s risk assessment indicates that there is a risk concern for handlers during the 

perforation (cutting, poking, punching, or slicing) and removal of tarps, and notes potential for 

increased risk when high barrier tarps are used. To address these risks EPA required the 

following mitigation in the July 2008 RED: 

• Tarps cannot be perforated until a minimum of 5 days (120 hours) after fumigation was 

complete. 

• Tarps cannot be removed until 24 hours after tarp perforation is complete. 

• If tarps are not removed after perforation, planting cannot start until 48 hours after 

perforation is complete. 

• If tarps are left intact for at least 14 days after the fumigation is complete then planting 

can take place as tarps are being perforated. 

• Broadcast tarps could be removed before 5 days if adverse weather compromised the 

integrity of the tarp provided that at least 48 hours had passed since fumigation 

completion, the buffer zone was extended until 24 hours after the tarp removal was 

complete, and untreated areas in the application block are not treated for at least 24 hours 

after tarp removal is complete. 

• Tarp perforation must be done using mechanical methods. 

• Each broadcast tarp panel must be perforated using a lengthwise cut. 

During the post-RED comment period the Agency received comments on the tarp 

perforation and removal requirements. In particular, the Agency received comments on the 

adequacy of the 5 day requirement for high barrier tarps to protect workers; the difficulty 

implementing the 24 hour wait period between tarp perforation and removal; and concerns 

regarding the weather condition exceptions, mechanical perforation, and broadcast panel 

perforation. 

 There is some uncertainty regarding potential risks if high barrier tarps are perforated 

after 5 days. This is because worker exposure data used in the risk assessments are generally 

based on what has been the industry standard tarping technology, i.e., low or high density 

polyethylene tarps, typically with higher application rates and no significant emphasis on using 

the GAPs as defined in the RED. Data indicate that high barrier tarps are effective measures to 

reduce fumigant emissions (see Methyl Bromide (PC Code 053201), Chloropicrin (PC Code 

081501), Dazomet (PC Code 035602), Metam Sodium and Potassium (PC Codes 039003 & 

039002), MITC (PC Code 068103), Updated Health Effects Division Recommendations for 

Good Agricultural Practices and Associated Buffer Credits). While this reduction decreases the 

risk to bystanders, it could increase the risk to handlers perforating or removing tarps because 

more fumigant could be trapped between the soil surface and the tarp—currently California 
94

Department of Pesticide Regulation (CDPR) prohibits the use of methyl bromide with certain 

high barrier tarps due to worker concerns. 

Based on CDPR’s prohibition and stakeholder’s comments, EPA considered requiring a 

longer interval such as 10 days before allowing high barrier tarps to be perforated. However, 

EPA was concerned that adding such a requirement could discourage fumigators from using high 

barrier tarps which potentially allow for lower application rates and reduce bystander risk 

associated with off gassing. New studies currently underway which involve use of high barrier 

tarps may enable EPA to refine estimates of handler risk in the future. EPA will consider these 

data during Registration Review, or sooner as the information becomes available. 

Since the Agency has designed the mitigation measures to work together and believes 

that measures to address handler risks are likely to protect these handlers when the reduced rates 

are considered in conjunction with other measures such as respiratory protection, GAPs, FMPs, 

and training, EPA is not increasing the amount of days before high barrier tarps can be 

perforated. 

During earlier comment periods EPA heard from various stakeholders that windy 

conditions sometimes caused tarps to blow off fields and create other hazards, e.g., to motorists 

on nearby roadways. As a result, in the July 2008 RED the Agency provided an exception to 

allow tarps to be removed after 48 hours under adverse weather conditions. During the postRED comment period EPA received comments that this exception did not fully address the issue 

since the mitigation required waiting a minimum of 48 hours after fumigation but tarps could 

blow of fields sooner than that. Commenters also said waiting 24 hours between tarp perforation 

and removal and the requirement to cut every broadcast tarp panel added to the potential for tarps 

to blow off fields and create other hazards: once tarps are cut they are prone to blowing off 

when windy conditions occur. To decrease the potential of broadcast tarps blowing off 

commenters also suggested that the Agency add flexibility to the 24 hour requirement by giving 

tarp removers the option to remove tarps 2 hours after tarp perforation if monitoring indicated 

levels below the Agency’s LOC. Commenters also suggested that every 1-3 tarp panels should 

be cut based on the professional judgment of the handler. 

Upon review of the comments the Agency agrees that the mitigation should be revised 

somewhat to allow for tarp removal at any time if the tarp is no longer performing its intended 

function and it is creating other types of risk. Therefore, EPA is revising the exception outlined 

in the RED to address these comments. EPA notes that handlers undertaking these tasks must 

follow the respiratory protection procedures detailed in Section 4 (Respiratory Protection for 

Handlers); this change still provides handler protection while reducing the unintended 

consequences of tarps creating other hazards. 

The Agency believes cutting every panel allows the fumigant trapped beneath each panel 

to off gas before the tarp is removed. If each panel is not cut, it is not likely that necessary offgassing can take place to reduce risks to handlers removing tarps. The Agency understands that 

the main concern for not cutting every panel is due to the potential for tarps to blow off and has 
95

determined that this concern is best addressed by modifying the 24-hour wait period. Tarps may 

be removed 2 hours after tarp perforation is complete provided that tarp removers follow the 

procedures set forth in the respiratory section of this document; therefore the risk to handlers will 

not increase as a result of this modification. EPA considered the suggestion to monitor before 

tarp removal begins; however, because of technical limitations with current technology the 

Agency did not include monitoring as part of the mitigation. As with the respiratory protection 

section, the Agency sees the value in a monitoring program if reliable and accurate devices are 

available and will consider monitoring during Registration Review or sooner if information 

becomes available. 

The Agency received comments supporting the requirement for mechanical tarp 

perforation, though other commenters stated that for some situations mechanical cutting is not 

feasible. Examples cited included at the start of a row when a mechanical device such as an 

ATV will be used to cut the tarps on the field, during flood prevention activities, and for small 

fields. Based on comments, EPA believes these are necessary short-duration activities. Provided 

the respiratory protection procedures for handlers are followed, these activities would not 

increase the risk to handlers. With regard to small fields where mechanical cutting is not 

feasible, the Agency considered the duration of the activity and the respiratory protection 

considerations and will permit manual perforation only for application blocks that are 1 acre or 

less in size. 

As a result of the Agency’s review and consideration of comments, the following 

summarizes the revised mitigation measures to address inhalation risks from tarp perforation and 

removal activities: 

• As described in the Handler Definition section of this document tarp perforators and 

removers are considered handlers for a specified duration and every handler must adhere 

to the respiratory protection procedures outlined in the Respiratory Protection section of 

this document. 

• Tarps must not be perforated until a minimum of 5 days (120 hours) have elapsed after 

the fumigant injection into the soil is complete (e.g., after injection of the fumigant 

product and tarps have been laid or after drip lines have been purged and tarps have been 

laid), unless a weather condition exists which necessitates the need for early perforation 

or removal See Early Tarp Removal for Broadcast Applications Only and Early Tarp 

Perforation with Seepage Irrigation sections below. 

• If tarps will be removed after planting, tarp removal must not begin until at least 2 hours 

after tarp perforation is complete. 

• If tarps will not be removed before planting, planting or transplanting must not begin 

until at least 48 hours after the tarp perforation is complete. 

• If tarps are left intact for a minimum of 14 days after fumigant injection into the soil is 

complete, planting or transplanting may take place while the tarps are being perforated. 

• Each tarp panel used for broadcast fumigation must be perforated. 

• Tarps used for fumigations may be perforated manually ONLY for the following 

situations: 
96

o At the beginning of each row when a coulter blade (or other device which 

performs similarly) is used on a motorized vehicle such as an ATV. 

o In fields that are 1 acre or less. 

o During early tarp removal in fields with seepage irrigation if rainfall necessitates 

draining fields 

• In all other instances tarps must be perforated (cut, punched, poked, or sliced) only by 

mechanical methods. 

• Tarp perforation for broadcast fumigations must be completed before noon. (seepage 

irrigation exception) 

• For broadcast fumigations tarps must not be perforated if rainfall is expected within 12 

hours. 

• Early Tarp Removal for Broadcast Applications Only: 

o Tarps may be removed before the required 5 days (120 hours) if adverse weather 

conditions have compromised the integrity of the tarp, provided that the 

compromised tarp poses a safety hazard. Adverse weather includes high wind, 

hail, or storms that blow tarps off the field and create a hazard, e.g., tarps blowing 

into power lines and onto roads. A compromised tarp is a tarp that due to an 

adverse weather condition is no longer performing its intended function and is 

creating a hazard. 

o If tarps are removed before the required 5 days have elapsed due to adverse 

weather, the events must be documented in the post fumigation summary section 

of the FMP. 

• Early Tarp Perforation with Seepage Irrigation 

o Tarp perforation is allowed before the 5 days (120 hours) have elapsed if rain 

necessitates field drainage. 

o Tarps must be immediately retucked and packed after soil removal. 

o Subsequent tarp perforations must not occur until the original 5 days have 

elapsed. 

o The events must be documented in the post fumigation summary section of the 

FMP.” 

6. Entry Prohibitions 

Most of the current metam-sodium and metam-potassium labels allow reentry to the 

treated field by workers 48 hours after application. The risk assessment indicates that risks 

exceed EPA’s level of concern for workers entering fields after 48 hours. However, the risk 

assessment indicates that extending this period decreases this risk. In addition, stakeholder 

comments prior to the July 2008 RED indicated that non-handler entry to perform postapplication (i.e., non-handler) tasks is generally not needed for at least 7 to 14 days following the 

completion of the application and could reduce the effectiveness of the fumigation by disturbing 

the soil thus allowing the fumigate to escape the soil before it effectively controls pests. 

Due to the volatile nature of metam-sodium and metam-potassium and the potential for 

worker exposure, in the July 2008 RED the Agency restricted entry into the treated area by 
97

anyone other than a protected handler. This restriction differs from a restricted entry interval 

(REI), that is currently required for most conventional pesticides, which contains exceptions for 

workers doing certain tasks before the REI has expired (e.g., scouting). Workers permitted entry 

under the REI are prohibited for soil fumigants. Under the Worker Protection Standard (WPS), 

exceptions allow certain tasks to take place before the REI has expired as long as dermal contact 

with treated surfaces will be limited; however for fumigants where inhalation exposure is the 

primary risk concern, entry to a treated area is further restricted. 

 

During the post-RED comment period, the Agency received comments that indicated the 

opposite of the comments received in phase 5. The post-RED comments stressed that the 

restriction would prohibit certain activities from taking place and that the restrictions were not 

warranted. Based on discussions with stakeholders and the risks identified, EPA does not 

believe that the entry restricted period will have a substantial impact on agricultural operations, 

and the Agency is not making any changes to the July 2008 RED mitigation listed below. 

EPA believes that risks will not exceed the Agency’s level of concern, provided entry 

(including early entry that would otherwise be permitted under the WPS) by any person—other 

than a correctly trained and PPE-equipped handler who is performing a handling task—is 

prohibited from the start of the application until: 

• 5 days (120 hours) after application has ended for untarped applications, or 

• After tarps are perforated and removed if tarp removal is completed less than 14 days 

after application, or 

• 48 hours after tarps are perforated if they will not be removed prior to planting, or 

• 5 days (120 hours) after application is complete if tarps are not perforated and removed 

14 days after the application is complete. 

Figures 5, 6, 7, and 8 provide illustrations of tarp perforation/removal and entry 

prohibition mitigation required for various metam-sodium and metam-potassium applications. 

The intervals depicted are the minimum that must be followed. 
98

Figure 5. Untarped Applications 

48 hours

Buffer Zone 

Period 

Begins 

Entry 

Restricted 

Period 

Begins 

Application 

Ends 

Buffer Zone 

Period Ends 

Entry 

Restricted 

Period Ends 

Application 

Begins 
99

Figure 6. Tarp Broadcast Applications (tarps removed before planting) 

Tarp 

Perforation 

Begins 

Buffer Zone 

Period 

Begins 

Entry 

Restricted 

Period 

Begins 

Application 

Ends 

Buffer Zone 

Period Ends 

Tarp 

Perforation 

Ends 

Entry 

Restricted 

Period Ends 

Tarp 

Removal 

Begins 

Tarp 

Removal 

Ends 

Application 

Begins 

2 hours 

48 hours 

5 days (120 hours) 
100

Figure 7. Tarp Bed Applications (Tarps not removed before planting) 

Application 

Begins 

Buffer Zone 

Period 

Begins 

Entry 

Restricted 

Period 

Begins 

Application 

Ends 

Buffer Zone 

Period Ends 

Tarp 

Perforation 

Begins 

Tarp 

Perforation 

Ends 

Planting Can 

Begin 

Entry 

Restricted 

Period Ends 

48 hours 

48 hours 

5 days (120 hours) 
101

Figure 8. Tarp Bed/Broadcast Applications (Tarps are not perforated until 14 days after 

application) 

Application 

Begins 

Buffer Zone 

Period 

Begins 

Entry 

Restricted 

Period 

Begins 

Application 

Ends 

Buffer Zone 

Period Ends 

Entry 

Restricted 

Period Ends 

Tarp 

Perforation 

& Planting 

5 days (120 hours) 

48 hours 

14 days 
102

cc. Other Risk Mitigation 

1. Restricted Use Pesticide (RUP) Classification 

All soil fumigant products containing methyl bromide, 1,3-dichloropropene (Telone®), 

iodomethane, and chloropicrin are currently classified as RUPs. Soil fumigant products 

containing metam-sodium and metam-potassium are currently unclassified as such. However, 

MITC, the byproduct of metam-sodium and metam-potassium, has characteristics that meet the 

criteria for restricted use for both human hazard criteria (as specified in 40 CFR 152.170(b)) and 

from other evidence (as specified in 40 CFR 152.170(d)) including use history and incident data 

from exposure to MITC. 

Human Hazard Criteria 

The acute toxicity profile of MITC shows it is more acutely toxic (toxicity categories are 

all I or II) than metam-sodium and metam-potassium (mostly toxicity categories III and IV). 

While the product toxicity of metam-sodium and metam-potassium do not meet the hazard 

criteria for classification as restricted use, the degradate product of MITC, which both handlers 

and bystanders can be exposed to, does meet the criteria. 

Other Evidence 

If any soil fumigant is not applied correctly, bystanders may be exposed to concentrations 

that exceed levels of concern and that could cause significant adverse effects. There is a history 

of incidents involving metam-sodium in which multiple bystanders experienced illness/injury 

despite being several hundred to several thousand feet from the treated area. The application of 

soil fumigants can pose hazards for several hours from the time of application to several days 

after application. Depending on the situation, worker and/or area air monitoring may be required 

to ensure that exposure limits are not exceeded. Special equipment is often needed to apply soil 

fumigant safely and accurately (e.g., compaction rig, tarp equipment, self-contained breathing 

apparatus). To apply soil fumigants safely and ensure bystanders and applicators are not 

adversely affected, handlers also need specialized skills and training.

In sum, metam-sodium and metam-potassium meet the standard for restricted use because: 

• The application of these fumigants involves complex operations requiring specialized 

training and/or experience. 

• Fumigant label directions call for specialized apparatus and protective equipment that is 

not available to the general public. 

• A minor failure to follow label directions may result in severe adverse effects. 

• Even if directions for use are followed, use may result in discernible adverse effects, of 

both direct and indirect nature, on non-target organisms. 

Therefore, the Agency has determined that all metam-sodium and metam-potassium soil 

fumigant products must be classified as restricted use. Label requirements will include the 

following details, which are also contained in the attached label table. 
103

Requirement on Labels

“Restricted Use Pesticide due to acute inhalation toxicity to humans.” 

“For retail sale to and use by Certified Applicators or persons under their direct supervision and 

only for those uses covered by the Certified Applicator’s certification.” 

2. Good Agricultural Practices (GAPs) 

Since the application methods and work practices of fumigators have direct impacts on 

the amount of fumigant applied and emitted, the Agency determined that labeling should require 

proven practices that will reduce risks to handlers, bystanders, and the environment. Registrants, 

applicators, growers, and other stakeholders have consistently reported to the Agency that GAPs 

are a key mitigation measure to reduce the amount of fumigants applied and fumigant emissions. 

The purpose of this section in the July 2008 RED was to specify good agricultural 

practices (GAPs) that were required for soil applications of metam-sodium and metampotassium. The practices specified contribute to reducing emissions and thereby are expected to 

reduce potential for worker and bystander exposures. 

The Agency received comments regarding the GAPs outlined in the July 2008 RED. 

These comments addressed a range of topics: 

• making the GAPs voluntary rather than mandatory label requirements, 

• buffer zone credits associated with GAP implementation, 

• wind speed requirements and the description of inversion conditions, 

• crop residue requirements, 

• application equipment requirements, 

• soil moisture and temperature requirements, 

• flexibility in the event that new GAPs are developed, 

• enforceability of GAPs, 

• university research exemptions, and 

These comments are addressed in detail in the Special Review and Reregistration 

Division’s response to comments document. Based on the comments, the Agency has revised 

some of the GAPs, and will continue to review GAPs as the Agency finalizes the soil fumigant 

labels. 

The GAPs outlined in the RED and this RED amendment has been shown to reduce 

emissions and bystander exposures and will continue to be mandatory label requirements. Buffer 

zone credits have been reanalyzed and additional credits have been calculated for various GAPs 

depending on the soil fumigant used (see buffer zone credit section). 

The Agency has clarified the language regarding inversions and wind speed 

requirements. The Agency agrees that erosion control is an important consideration. However, 

removing the crop residue prior to fumigation is important to limit the natural “chimneys” that 
104

will occur in the soil when crop residue is present. These “chimneys” allow the soil fumigants to 

move through the soil quickly and escape into the atmosphere. This may create potentially 

harmful conditions for workers and bystanders and will limit the efficacy of the fumigant. To 

accommodate both of these important considerations (erosion control and human health 

protection), the Agency encourages that the field be cleared of crop residue as close to the timing 

of the fumigation as possible to limit the length of time that the soil would be exposed to 

potentially erosive weather conditions. 

Note: The Agency plans to work with the registrants and other stakeholders to refine the GAPa 

for metam-sodium and metam-potassium prior to the 2010 and 2011 growing season. 

Weather Conditions 

The Agency received many comments related to the inversion label language including: 

concern that some of the characteristics of inversion conditions (like misty conditions or clear 

skies at night) do not always indicate the presence of an inversion: relying on a weather forecast 

to predict inversions is unreliable and not enforceable: and that prohibiting application during 

inversions does not address concerns of inversions during the off-gassing period. 

Based on these comments the Agency has revised the “weather conditions” section of the 

GAPs that relates to temperature inversions to clarify that parts of the weather conditions that are 

requirements and those that are included to help guide the applicator to identify temperature 

inversions. The measures have also been updated to prohibit application only if temperature 

inversion conditions are forecasted to persist for more than 18 of the 48 hours after the start of 

the application since this will filter out conditions when diurnal temperature inversions may 

occur, though even diurnal temperature inversions could contribute to exposures to fumigant 

concentrations outside buffers. As such, EPA believes that the measures described below in the 

emergency preparedness and response section of this document are important to address potential 

risks associated with shorter-term diurnal inversions. The Agency is also changing the wind 

speed requirement so winds may either be 2 mph at the start of application or be forecasted to 

reach 5 mph during the application. These changes are designed to prevent applications when 

inversion conditions are predicted to occur after the application has begun, since this is the time 

when the peak off-gassing is expected to occur. 

 Stakeholders also questioned where the inversion conditions must exist and to what 

extent the temperature inversion must exist that would prevent an application. The Agency has 

provided additional temperature inversion details and has added a prohibition for application 

during an air-stagnation advisory. Air-stagnation advisories are issued through the National 

Weather Service and usually capture long periods of air stillness that may remain in an area from 

one to several days. EPA has determined that these modifications achieve the same goals as the 

2008 RED since they provide additional clarity that will enhance users’ ability to practically 

comply with the requirements. The revised statements are stated below. 

The following are mandatory GAPs that must be followed during all applications, as 

specified below. All measurements and other documentation planned to ensure that the 

mandatory GAPs are achieved must be recorded in the FMP and/or the post application summary 

report. 
105

Registrants may also include optional GAPs that reduce emission on product labels. 

Some of the optional GAPs may qualify for buffer zone credits (e.g., reduced soil temperature, 

use of high barrier tarps, increased soil organic matter, and soils with increased clay content). 

All measurements and other documentation planned to ensure that the optional GAPs are 

achieved must be recorded in the FMP and/or the post application summary report. 

GAPS for Ground-rig Applications (Shank, Spray Blade, Rotary Tiller, etc.) 

Wind Speed 

• Wind speed at the application site must be a minimum of 2 mph at the start of the application 

or forecasted to reach at least 5 mph during the application. 

Weather conditions 

• Prior to fumigation the weather forecast for the day of the application and the 48-hour period 

following the fumigation must be checked to determine if unfavorable weather conditions 

exist or are predicted and whether fumigation should proceed. 

• Do not apply if a shallow, compressed (low-level) temperature inversion is forecast to persist 

for more than 18 consecutive hours for the 48-hour period after the start of application, or if 

there is an air-stagnation advisory in effect for the area in which the fumigation is planned. 

• Detailed local forecasts for weather conditions, wind speed, and air stagnation advisories 

may be obtained on-line at: http://www.nws.noaa.gov. For further guidance, contact your 

local National Weather Service Forecasting Office. 

Identifying Unfavorable Weather Conditions 

• Unfavorable weather conditions block upward movement of air, which results in trapping 

fumigant vapors near the ground. The resulting air mass can move off-site in unpredictable 

directions and cause injury to humans, animals or property. These conditions typically exist 

prior to sunset and continue past sunrise and persist as late as noontime. Unfavorable 

conditions are common on nights with limited cloud cover and light to no wind and their 

presence can be indicated by ground fog or smog and can also be identified by smoke from a 

ground source that flattens out below a ceiling layer and moves laterally in a concentrated 

cloud. 

Soil Conditions, Injection Depth and Soil Sealing 

• Soil must be in good tilth and free of large clods at the surface. If subsurface soil compaction 

layers (hardpans) are present within the intended fumigation treatment zone, a deep tillage to 

fracture these layers must occur prior to the soil fumigant application. 

• Field residue and stubble must be worked into the soil with little or no crop residue present 

on the soil surface. Crop residue that is present must not interfere with the soil seal. 

Removing the crop residue prior to fumigation is important to limit the natural “chimneys” 

that will occur in the soil when crop residue is present. These “chimneys” allow the soil 
106

fumigants to move through the soil quickly and escape into the atmosphere. This may create 

potentially harmful conditions for workers and bystanders and will limit the efficacy of the 

fumigant. However, crop residue on the field serves to prevent soil erosion from both wind 

and water and is an important consideration. To accommodate erosion control, fumigant 

efficacy, and human health protection, clear fields of crop residue as close to the timing of 

the fumigation as possible to limit the length of time that the soil would be exposed to 

potentially erosive weather conditions. 

 

• For shank injection applications: The injection point for bedded and broadcast shank 

injection applications shall be a minimum of 3 inches from the post-application soil surface. 

Chisel traces must be eliminated following an application and the soil surface must be 

compacted immediately with a culti-packer, ring roller, coil packer, soil-crumbler basket, 

bed-shaper, or other similar equipment. 

 

• For spray blade and rotary tiller applications: Spray or drip the product mixture on the soil 

immediately ahead of the bed-shaping equipment or tiller. The soil surface must be 

compacted immediately after application using a culti-packer, ring roller, soil-crumbler 

basket, bed-shaper, or other similar equipment. 

Soil temperature 

• For all ground-rig applications, the maximum soil temperature measured throughout the 

treatment area at a three-inch soil depth must be between 90-40 degrees F. 

Soil moisture 

• Soil moisture, at the start of an application, must be at 60-80% field capacity two to six 

inches below the soil surface. 

• To achieve soil moisture at 60-80% field capacity, water treatments before or during the 

application, or tillage before or during the application may be necessary. 

• To conserve soil moisture, pretreatment water or tillage should be done as close to the time of 

application as possible. 

• The soil shall contain at the time of application enough moisture two to six inches below the 

surface to meet the Feel Method test as appropriate for the soil texture. 

coarse textured soils (fine sand and loamy fine sand) there must be enough moisture (50 

to 75 percent available soil water moisture) to form a weak ball with loose and clustered 

sand grains on fingers, darkened color, moderate water staining on fingers, will not 

ribbon. 

moderately coarse textured soils (sandy loam and fine sandy loam) there must be 

enough moisture (50 to 75 percent available soil water moisture) to form a ball with 

defined finger marks, very light soil/water staining on fingers, darkened color will not 

stick. 
107

medium textured soils (sandy clay loam, loam, and silt loam) there must be enough 

moisture (50 to 75 percent available soil water moisture) to form a ball, very light 

staining on fingers, darkened color, pliable, and forms a weak ribbon between the thumb 

and forefinger. 

fine textured soils (clay, clay loam, and silty clay loam) there must be enough moisture 

(50 to 75 percent available soil water moisture) to form a smooth ball with defined finger 

marks, light soil/water staining on fingers, ribbons between thumb and forefinger. 

 For fields with more than one soil texture, soil moisture content in the lightest textured 

(most sandy) areas must comply with this soil moisture requirement. Whenever possible, the 

field should be divided into areas of similar soil texture and the soil moisture of each area should 

be adjusted as needed. Coarser textured soils can be fumigated under conditions of higher soil 

moisture than finer textured soils; however, if the soil moisture is too high, fumigant movement 

will be retarded and effectiveness of the treatment will be reduced. Previous and/or local 

experience with the soil to be treated or the crop to be planted can often serve as a guide to 

conditions that will be acceptable. If there is uncertainty in determining the soil moisture content 

of the area to be treated, a local extension service or soil conservation service specialist or pest 

control advisor (agriculture consultant) should be consulted for assistance. 

Prevention of Spillage 

• Do not apply or allow fumigant to drain onto the soil surface. 

Application and Equipment Considerations 

• Injectors must be placed below the soil surface before product flow begins. 

• Clear lines before lifting injectors from the soil. 

• Each injection line must have a check valve located as close as possible to the final 

injection point. 

• Use only tanks, hoses and fittings approved for metam.

• Dry connect fittings (closed transfer system) must be installed on all tanks and transfer 

hoses. 

• All systems must be equipped with an individual tank monitoring system to detect flow 

problems in each individual tank.

• Each nozzle must be equipped with a flow monitor, e.g. mechanical, electronic, or Redball type monitor. 

• Prior to applications, the applicator must ensure that: 
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• Application equipment is in good working order, 

• All tanks, hoses, fittings, valves and connections are tightened, sealed and not 

leaking, 

• Tank monitoring equipment, flow monitoring equipment and check valves are 

functioning properly, 

• There is no damage to hoses or piping, 

• Sight gauges and pressure gauges are working, 

• Nozzles and metering devices are of correct size and are sealed and unobstructed, 

• All shields are in place. 

Tarps 

• When tarps are used in tractor applications, the tarps must be installed immediately after 

application. 

• Only approved tarps identified in this document, in the section titled “Buffer Zone 

Reduction Credits,” may be used for credits towards reducing the buffer. 

• A written tarp plan must be developed and included in the FMP that includes: 

o Schedule and procedures for checking tarpaulins for damage, tears, and other 

problems, 

o Plans for determining when and how repairs to tarp will be made, and by whom, 

o Minimum time following injection that tarp will be repaired, 

o Minimum size of damage that will be repaired, 

o Other factors used to determine when tarp repair will be conducted, 

o Schedule, equipment and methods used to cut tarp, 

o Aeration plans and procedures following cutting and /or slitting prior to tarp removal 

or planting, and 

o Schedule, equipment, and procedures for tarp removal. 

GAPS for Sprinkler and Chemigation Applications 

Wind Speed 

 

• For mid-release, high-release and end-gun sprinkler or chemigation applications as 

defined by U.S. EPA, wind speed at the application site must be a minimum of 2 mph at 

the start of the application or forecasted to reach 5 mph during the application and the 

maximum wind speed is 8 mph. 

• For low release height-solid stream sprinkler or chemigation applications as defined by 

U.S. EPA, wind speed at the application site must be a minimum of 2 mph at the start of 

the application or forecasted to reach 5 mph during the application and the maximum 

wind speed is 25 mph. 
109

Wind Speed 

• Wind speed at the application site must be a minimum of 2 mph at the start of the application 

or forecasted to reach at least 5 mph during the application. 

Weather conditions 

• Prior to fumigation the weather forecast for the day of the application and the 48-hour period 

following the fumigation must be checked to determine if unfavorable weather conditions 

exist or are predicted and whether fumigation should proceed. 

• Do not apply if a shallow, compressed (low-level) temperature inversion is forecast to persist 

for more than 18 consecutive hours for the 48-hour period after the start of application, or if 

there is an air-stagnation advisory in effect for the area in which the fumigation is planned. 

• Detailed local forecasts for weather conditions, wind speed, and air stagnation advisories 

may be obtained on-line at: http://www.nws.noaa.gov. For further guidance, contact your 

local National Weather Service Forecasting Office. 

Identifying Unfavorable Weather Conditions 

• Unfavorable weather conditions block upward movement of air, which results in trapping 

fumigant vapors near the ground. The resulting air mass can move off-site in unpredictable 

directions and cause injury to humans, animals or property. These conditions typically exist 

prior to sunset and continue past sunrise and persist as late as noontime. Unfavorable 

conditions are common on nights with limited cloud cover and light to no wind and their 

presence can be indicated by ground fog or smog and can also be identified by smoke from a 

ground source that flattens out below a ceiling layer and moves laterally in a concentrated 

cloud. 

Soil Conditions 

• Soil must be in good tilth and free of large clods at the surface. If subsurface soil 

compaction layers (hardpans) are present within the intended fumigation treatment zone, 

a deep tillage to fracture these layers must occur prior to the soil fumigant application. 

• Field residue and stubble must be worked into the soil with little or no crop residue 

present on the soil surface. Crop residue that is present must not interfere with the soil 

seal. Removing the crop residue prior to fumigation is important to limit the natural 

“chimneys” that will occur in the soil when crop residue is present. These “chimneys” 

allow the soil fumigants to move through the soil quickly and escape into the atmosphere. 

This may create potentially harmful conditions for workers and bystanders and will limit 

the efficacy of the fumigant. However, crop residue on the field serves to prevent soil 

erosion from both wind and water and is an important consideration. To accommodate 

erosion control, fumigant efficacy, and human health protection, clear fields of crop 

residue as close to the timing of the fumigation as possible to limit the length of time that 

the soil would be exposed to potentially erosive weather conditions. 

Air Temperature 
110

• The maximum air temperature is 90 degrees F. 

Soil temperature 

• The maximum soil temperature, measured at a three-inch soil depth, is 90 degrees F. 

Soil Moisture 

• Apply sufficient water before or during the application to ensure soil moisture at 60-80% 

field capacity at a minimum of two to six inches below the soil surface at the start of the 

application. 

Flushing Irrigation Lines 

• Do not allow fumigant to remain in the irrigation system after the application is complete. 

After application of the fumigant, flush the injection and irrigation system with untreated 

water. The flush time must be adequate to purge the fumigant from the injection and 

irrigation system, but should be less than the amount that could over-saturate the beds. If 

common lines are used for both the fumigant application and a water treatment/seal (if 

applied), these lines must be adequately flushed before starting the water treatment/seal.

Set-up, Repair and Maintenance of Equipment 

• Anti-siphon and back-flow prevention devices must be installed and in working order. 

• Storage tanks must be inspected, in good condition, and not past their life expectancy to 

ensure product does not spill or leak. 

• Storage tanks must have proper pesticide labels on them. 

• Install a shut-off valve on the tank outlet to secure the bulk storage tank when not in use. 

- Use only tanks constructed with materials approved for handling metam-sodium and 

metam-potassium. 

- Inter-connect the pump power supply and injection pump so that, if the center pivot 

or linear move stops, the injection pump shuts off. 

GAPs for Drip Application 

Wind Speed 

• Wind speed at the application site must be a minimum of 2 mph at the start of the application 

or forecasted to reach at least 5 mph during the application. 

Weather conditions 
111

• Prior to fumigation the weather forecast for the day of the application and the 48-hour period 

following the fumigation must be checked to determine if unfavorable weather conditions 

exist or are predicted and whether fumigation should proceed. 

• Do not apply if a shallow, compressed (low-level) temperature inversion is forecast to persist 

for more than 18 consecutive hours for the 48-hour period after the start of application, or if 

there is an air-stagnation advisory in effect for the area in which the fumigation is planned. 

• Detailed local forecasts for weather conditions, wind speed, and air stagnation advisories 

may be obtained on-line at: http://www.nws.noaa.gov. For further guidance, contact your 

local National Weather Service Forecasting Office. 

Identifying Unfavorable Weather Conditions 

• Unfavorable weather conditions block upward movement of air, which results in trapping 

fumigant vapors near the ground. The resulting air mass can move off-site in unpredictable 

directions and cause injury to humans, animals or property. These conditions typically exist 

prior to sunset and continue past sunrise and persist as late as noontime. Unfavorable 

conditions are common on nights with limited cloud cover and light to no wind and their 

presence can be indicated by ground fog or smog and can also be identified by smoke from a 

ground source that flattens out below a ceiling layer and moves laterally in a concentrated 

cloud. 

Soil Conditions 

• Soil must be in good tilth and free of large clods at the surface. If subsurface soil 

compaction layers (hardpans) are present within the intended fumigation treatment zone, 

a deep tillage to fracture these layers must occur prior to the soil fumigant application. 

• Field residue and stubble must be worked into the soil with little or no crop residue 

present on the soil surface. Crop residue that is present must not interfere with the soil 

seal. Removing the crop residue prior to fumigation is important to limit the natural 

“chimneys” that will occur in the soil when crop residue is present. These “chimneys” 

allow the soil fumigants to move through the soil quickly and escape into the atmosphere. 

This may create potentially harmful conditions for workers and bystanders and will limit 

the efficacy of the fumigant. However, crop residue on the field serves to prevent soil 

erosion from both wind and water and is an important consideration. To accommodate 

erosion control, fumigant efficacy, and human health protection, clear fields of crop 

residue as close to the timing of the fumigation as possible to limit the length of time that 

the soil would be exposed to potentially erosive weather conditions. 

 

Soil Temperature 

• The maximum soil temperature is 90 degrees F, measured at three inches in depth. 

Set-up, Repair and Maintenance of Equipment 

• Properly label metam-sodium storage tanks. 
112

• Install a shut-off valve to secure the bulk storage tank when not in use. 

• Use only tanks constructed with materials approved for handling metam products. 

• The drip irrigation system (main lines, headers, drip tape) must be thoroughly checked for 

leaks before the start of the application. An adequate run-time and pressure are needed to 

detect leaks. Look for puddling along major pipes (holes on pipes or leaky joints), at the 

top and ends of rows (leaky connections, open drip tape), in the furrows and on the bed 

surface (damaged drip tape, malfunctioning emitters). 

• To inject fumigant, use a metering system, effectively designed and constructed of 

materials that are compatible with the fumigant and capable of being fitted with system 

interlocking controls. 

• The system must contain a functional back-flow/check valve and low-pressure drain 

appropriately located on the irrigation pipeline to prevent water source contamination and 

backflow. 

• The fumigant injection system must contain a functional, automatic, quick-closing check 

valve to prevent the flow of fumigant back toward the fumigant container. 

• The fumigant injection system must contain a functional, normally closed valve located 

on the intake side of the injection point and connected to the system interlock to prevent 

fumigant from being withdrawn from the supply tank when the irrigation system is either 

automatically or manually shut down. 

 

• The system must contain functional interlocking controls to automatically shut off the 

fumigant injection when the irrigation water flow stops or decreases to the point where 

fumigant distribution is adversely affected. 

Tarps 

• When tarps are used in drip irrigation the tarps must be installed immediately after 

application. 

• Only tarps mentioned previously in this document (in the subsection titled “Buffer Zone 

Reduction Credits”, may be used for credits towards reducing the buffer. 

 

• A written tarp plan must be developed and included in the FMP that that includes: 

o Schedule and procedures for checking tarpaulins for damage, tears, and other 

problems, 

o Plans for determining when and how repairs to tarp will be made, and by whom, 

o Minimum time following injection that tarp will be repaired, 

o Minimum size of damage that will be repaired, 

o Other factors used to determine when tarp repair will be conducted, 
113

o Schedule, equipment and methods used to cut tarp, 

o Aeration plans and procedures following cutting and /or slitting prior to tarp removal 

or planting, and 

o Schedule, equipment, and procedures for tarp removal. 

Flushing Drip Irrigation Lines 

• After application of the fumigant, flush the injection and irrigation system with untreated 

water. Do not allow fumigant to remain in the irrigation system after the application is 

complete. The total volume of water must be adequate to completely remove the 

fumigant from the irrigation system. If common lines are used for both the fumigant 

application and a water treatment/seal (if applied), these lines must be adequately flushed 

before starting the water treatment/seal. 

3. Fumigant Management Plans (FMPs) 

As noted elsewhere in this document, soil fumigation is a complex site-specific activity. 

Failure to adhere to label requirements and procedures for safe use has led to accidents affecting 

workers involved in fumigations as well as bystanders. Information from various sources shows 

that health and safety plans, FMPs in this context, typically reduce workplace injuries and 

accidents by prescribing a series of operational requirements and criteria. In fact plans like these 

are widely implemented in a variety of industries and are recommended as standard approaches 

for occupational health and safety management by groups such as American Industrial Hygiene 

Association9 (i.e., through “Administrative” and “Workplace” controls). The Centers for Disease 

Control provides guidance for developing health and safety plans in agricultural settings.10 The 

effectiveness of similar plans has also been evaluated in the literature. Examples include 

“lookback” reviews conducted by the Occupational Safety and Health Administration (OSHA) 

which essentially implemented standards in various industries then reviewed their effectiveness 

in this process as they are required to determine whether the standards should be maintained 

without change, rescinded or modified. OSHA is required by Section 610 of the Regulatory 

Flexibility Act (5 U.S.C. 610) and Executive Order 12866 to conduct the “lookback” reviews. 

These reviews are conducted to make the subject final standards more effective or less 

burdensome in achieving their objectives, to bring them into better alignment with the objectives 

of Executive Order 12866, and to make them consistent with the objectives of the Regulatory 

Flexibility Act. Two examples of “lookback” reviews that support the use of FMPs for soil 

fumigant health and safety management include: ethylene oxide use as a fumigant/sterilant, and 

grain handling facilities requirements.11

 

9 Ignacio and Bullock (2006) A Strategy For Assessing and Managing Occupational Exposures (Third Edition), 

American Industrial Hygiene Association, AIHA Press 2700 Prosperity Avenue, Suite 250 Fairfax VA 22031 (ISBN 

1-931504-69-5) 

10 Karsky (2002) Developing a Safety and Health Program to Reduce Injuries and Accident Losses, Centers For 

Disease Control National Ag Safety Database, available at http://www.cdc.gov/nasd/docs/d001501-

d001600/d001571/d001571.html 

11 United States Department of Labor, Occupational Safety and Health Administration (2008) Lookback Reviews 

available at http://www.osha.gov/dea/lookback.html
114

In the July 2008 RED, EPA required FMPs to be completed before a fumigant 

application occurs. EPA concluded that FMPs will reduce potential risks to bystanders as well as 

handlers by requiring that applicators have carefully planned, in writing, each major element of 

the fumigation. In this context, an FMP is a set of performance criteria for each application, 

including how the fumigator intends to comply with label requirements. As added benefits, the 

Agency determined that FMPs would ensure directions on the product labels were followed and 

that the conditions under which fumigation occurred were documented. EPA also concluded that 

FMPs would help ensure an appropriate response by the applicator or others involved in the 

application should an incident occur since a proper and prompt response would reduce the 

potential risk to bystanders from potential high exposure situations (e.g., readily available first 

responder contact information could reduce response times to impacted bystanders and carefully 

thought out emergency response plans can help ensure appropriate actions are taken in case of 

unforeseen events). 

The July 2008 RED provided a list of each major element FMPs would need to address. 

These included general site and applicator information, application procedures, and a description 

of how the fumigator planned to comply with label requirements for GAPs, buffer zones, 

monitoring, worker protection, posting, and providing notification to the state or tribal lead 

agency. FMPs also were required to include plans for communication between the applicator 

and others involved in the fumigation, documentation, and handling emergency situation. 

Additionally, EPA required that applicators complete a post fumigation summary that described 

any deviations from the FMP, measurements taken to comply with GAPs, and information about 

any problems such as complaints or incidents that occurred as a result of the fumigation. The 

RED also specified requirements for record keeping and that FMPs must be provided, upon 

request, to enforcement officials and handlers involved in the fumigation. 

According to stakeholder comments in earlier comment periods, much of the information 

required for the site-specific FMP was already being documented by users, and most industry 

stakeholders supported mandatory FMPs provided they are not too restrictive or complex and do 

not result in an excessive administrative burden. 

During the post RED comment period, EPA received several comments regarding FMPs. 

Stakeholders noted that much of the information required for the site-specific FMP is already 

being documented by users and most industry stakeholders supported mandatory FMPs provided 

they are not too restrictive or complex. Several comments from industry and user stakeholders 

expressed concern that FMP requirements would increase paperwork burden without providing 

significant risk reduction, though others supported FMPs provided they did not result in an 

excessive administrative burden. A number of comments suggested that the level of detail EPA 

had required was too great and could result in voluminous, resource-intensive plans. Some of 

these comments suggested that a checklist format would be more efficient and far less 

burdensome. Some comments expressed reservations about the ability of FMPs to enhance 

compliance with label requirements. Some commenters were concerned about the feasibility of 

providing a copy of the FMP to on-site handlers or enforcement personnel, though others said 

that copies of the FMP should be provided to workers in areas adjacent to the application block. 

Following EPA’s review of the post-RED comments, the Agency still believes that 

FMPs will reduce potential risks to bystanders as well as handlers and are a key component of 
115

the package of measures to reduce risks. EPA believes that FMPs will also enhance 

compliance by requiring that applicators verify and document compliance with the label 

requirements during and after application events are completed. In cases where errors may 

have occurred, a post-application summary may also prevent similar problems from occurring 

during future applications. However, in response to comments, the Agency has somewhat 

modified the list of elements that must be addressed in the FMP (as described below) to make 

it more streamlined and thus less burdensome to applicators and growers. In addition, the 

Agency has developed a sample template in which many of the elements are covered in 

checklist format, which fumigators have the option of downloading and modifying to meet the 

needs of their specific fumigation situations. See: 

http://www.epa.gov/pesticides/reregistration/soil_fumigants/. EPA will also continue to work 

with stakeholders to refine the FMP template and potentially develop others so it is a more 

useful tool for ensuring the safe application of metam-sodium and metam-potassium. 

The Agency estimates that, if a certified applicator decides not to use the FMP template 

and decides to prepare a narrative FMP, a carefully designed FMP could take several hours to 

develop the first time. Subsequent FMPs should require substantially less time to develop 

because much of the information can be reused from the initial plan. In addition, an enterprise 

fumigating multiple application blocks as part of a larger fumigation may format their FMP in a 

manner whereby all of the information that is common to all the application blocks is captured 

once, and any information unique to a particular application block or blocks is captured in 

subsequent, separate sections. 

Amended FMP Requirements 

Consistent with the July 2008 RED, the Agency is not requiring FMPs to be submitted to 

state or local agencies. They must, however be maintained by the applicator and grower, (if the 

grower is not the applicator), for a period of 2 years. 

The Agency agrees with comments that having both the applicator and the 

owner/operator provide copies of the FMP to handlers is unnecessarily duplicative and that 

providing each worker with a hardcopy of the FMP wastes paper. The Agency also agrees that it 

is not necessary for the FMP to be provided to the workers in areas adjacent to the application 

block. Workers in adjacent areas will be notified of the fumigation by buffer posting 

requirements and, in the case of neighbors whose land is part of a buffer zone, the adjoining 

neighbor has responsibility for workers in areas adjacent to the application for which permission 

was granted to use as part of a fumigation buffer. The Agency has revised the following 

requirement that was included in the 2008 RED, “Once the application begins, the certified 

applicator and owner/operator of the application block must provide a copy of the FMP to 

handlers involved in the fumigation, workers in adjacent areas to the application block, and 

federal/state/local enforcement personnel, upon request.” The RED Amendment requires the 

certified applicator to make a copy of the FMP available for viewing by handlers involved in the 

fumigation. The certified applicator or the owner/operator of the application block must provide 

a copy of the FMP to any federal, state, tribal, or local enforcement personnel who request the 

FMP. In the case of an emergency, the FMP must be made available when requested by 

federal/state/local emergency response and enforcement personnel.
116

The Agency agrees with comments that the term “etc.” complicates enforcement 

activities and has removed that term from the labels. 

Each site-specific FMP must contain the following elements: 

 Applicator information (name, phone number, license number, employer name, employer 

address, date of completing registrant methyl bromide training program) 

 General site information 

3⁄4 Application block location, address, or global positioning system (GPS) coordinates 

3⁄4 Name, address, and, phone number of owner/operator of the application block 

3⁄4 Map, aerial photo, or detailed sketch showing field location, dimensions, buffer zones, 

property lines, roads, rights-of-ways, sidewalks, permanent walking paths, bus stops, 

water bodies, wells, nearby application blocks, surrounding structures (occupied and nonoccupied), locations of posted signs for buffers, and sites requiring 1⁄4 or 1⁄8 mile buffer 

zones (e.g., schools (preschool to grade 12), state licensed day care centers, nursing 

homes, assisted living facilities, hospitals, in-patient clinics and prisons) with distances 

from the application site labeled 

 General application information (target application date/window, brand name of fumigant, 

EPA registration number 

 Tarp Information and procedures for repair, perforation and removal (if tarp is used) 

3⁄4 Brand name, lot number, thickness 

3⁄4 Name and phone number of person responsible for repairing tarps 

3⁄4 Schedule for checking tarps for damage, tears, and other problems 

3⁄4 Maximum time following notification of damage that the person(s) responsible for tarp 

repair will respond 

3⁄4 Minimum time following application that tarp will be repaired 

3⁄4 Minimum size of damage that will be repaired 

3⁄4 Other factors used to determine when tarp repair will be conducted 

3⁄4 Name and phone number of person responsible for cutting and/or removing tarps (if other 

than certified applicator) 

3⁄4 Equipment/methods used to cut tarps 

3⁄4 Schedule and target dates for cutting tarps 

3⁄4 Schedule and target dates for removing tarps 

 Soil conditions (description of soil texture in application block, method used to determine 

soil moisture 

 Weather conditions (summary of forecasted conditions for the day of the application and the 

48-hour period following the fumigant application) 

3⁄4 Wind speed 

3⁄4 Inversion conditions (e.g., shallow, compressed (low-level) temperature inversion) 

3⁄4 Air stagnation advisory 

 Buffer zones 

3⁄4 Application method 

3⁄4 Application rate from lookup table on label (lb ai/A) 

3⁄4 Application block size from lookup table on label (acres) 

3⁄4 Credits applied 

3⁄4 Buffer zone distance 
117

3⁄4 Description of areas in the buffer zone that are not under the control of the 

owner/operator of the application block 

 Respirators and other personal protective equipment (PPE) for handlers (handler task, 

protective clothing, respirator type, respirator cartridge type, respirator cartridge replacement 

schedule, eye protection, gloves, other PPE) 

 Emergency procedures (evacuation routes, locations of telephones, contact information for 

first responders, local/state/federal contacts, key personnel and emergency 

procedures/responsibilities in case of an incident, equipment/tarp/seal failure, odor 

complaints or elevated air concentration levels outside buffer zone suggesting potential 

problems, or other emergencies). 

 Posting procedures (name, address, and phone number of person(s) who will post signs, 

location of posting signs, procedures for posting and sign removal) 

 Site-specific response and management (if applicable) 

3⁄4 Fumigant site monitoring 

 Description of who, when, where, and procedures for monitoring buffer zone 

perimeter 

3⁄4 Response information for neighbors 

 List of residences, businesses, and neighboring property owners informed 

 Name, address, and phone number of person doing notification 

 Method of sharing information 

 State and tribal lead agency notification (If state and/or tribal lead agency requires notice, 

provide a list of contacts that were notified and date notified.) 

 Plan describing how communication will take place between applicator, land owner/operator, 

and other on-site handlers (e.g., tarp cutters/removers, irrigators) for complying with label 

requirements (e.g., buffer zone location, buffer zone start/stop times, timing of tarp cutting 

and removal, PPE). 

3⁄4 Name and phone number of persons contacted 

3⁄4 Date contacted 

 Authorized on-site personnel 

3⁄4 Names, addresses and phone numbers of all handlers 

3⁄4 Employer name, addresses, and phone numbers for all handlers 

3⁄4 Tasks that each handler is authorized and trained to perform 

3⁄4 Date of PPE training for each handler 

3⁄4 For handlers designated to wear respirators when respiratory protection is required 

(minimum of one handler), date of medical qualification to wear a respirator and date of 

fit testing for respirator. 

 Air monitoring 

3⁄4 For handlers without respiratory protection: 

 If sensory irritation is experienced, indicate whether operations will be ceased or 

operations will continue with respiratory protection 

 If intend to cease operations when sensory irritation is experienced, provide the name, 

address, and phone number of the handler that will perform monitoring activities 

prior to operations resuming 

3⁄4 For handlers with respiratory protection: 

 Representative handler tasks to be monitored 

 Monitoring equipment to be used and timing of monitoring 

 Good Agricultural Practices (GAPs) 
118

3⁄4 Description of applicable mandatory GAPs (registrants may also include optional GAPs) 

3⁄4 Measurements and other documentation planned to ensure GAPs are achieved (e.g., 

measurement of soil and other site conditions, tarp repair/perforating/removal plans) 

 Description of hazard communication. (The buffer zone around the application block has 

been posted in accordance with the label. Pesticide product labels and material safety data 

sheets are on-site and readily available for employees to review.) 

 Record keeping procedures (the owner/operator of the application block that he/she (as well 

as the certified applicator) must keep a signed copy of the site-specific FMP and the post 

application summary for 2 years from the date of application). 

For situations where an initial FMP is developed and certain elements do not change for 

multiple fumigation sites (e.g., applicator information, authorized on-site personnel, record 

keeping procedures, emergency procedures) only elements that have changed need to be updated 

in the site-specific FMP provided the following: 

• The certified applicator supervising the application has verified that those elements are 

current and applicable to the application block before it is fumigated and has documented 

the verification in the site-specific FMP. 

• Recordkeeping requirements are followed for the entire FMP (including elements that do 

not change) 

Once the application begins, the certified applicator must make a copy of the FMP 

available for viewing by handlers involved in the fumigation. The certified applicator or the 

owner/operator of the application block must provide a copy of the FMP to any federal, state, 

tribal, or local enforcement personnel who request the FMP. In the case of an emergency, the 

FMP must be made available when requested by federal/state/local emergency response and 

enforcement personnel. 

Within 30 days of completing the application portion of the fumigation process, the 

certified applicator supervising the application must complete a post fumigation application 

summary that describes any deviations from the FMP that have occurred, measurements taken to 

comply with GAPs as well as any complaints and/or incidents that have been reported to 

him/her. The summary must include the actual date of the application, application rate, and size 

of application block fumigated. 

Specifically, the Post-Application Summary must contain the following elements: 

 Actual date of the application, application rate, and size of application block fumigated 

 Summary of weather conditions on the day of the application and during the 48-hour period 

following the fumigant application 

 Tarp damage and repair information (if applicable) 

3⁄4 Location and size of tarp damage 

3⁄4 Description of tarp/tarp seal/tarp equipment failure 

3⁄4 Date and time of tarp repair 

 Tarp removal details (if applicable) 
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3⁄4 Description of tarp removal (if different than in the FMP) 

3⁄4 Date tarps were cut 

3⁄4 Date tarps were removed 

 Complaint details (if applicable) 

3⁄4 Person filing complaint (e.g., on-site handler, person off-site) 

3⁄4 If off-site person, name, address, and phone number of person filing complaint 

3⁄4 Description of control measures or emergency procedures followed after complaint 

 Description of incidents, equipment failure, or other emergency and emergency procedures 

followed (if applicable) 

 Details of elevated air concentrations monitored on-site (if applicable) 

3⁄4 Location of elevated air concentration levels 

3⁄4 Description of control measures or emergency procedures followed 

3⁄4 Air monitoring results 

 When sensory irritation experienced: 

• Date and time of sensory irritation 

• Handler task/activity 

• Handler location where irritation was observed 

• Resulting action (e.g., cease operations, continue operations with respiratory 

protection) 

 When using a direct read instrument: 

• Sample date and time 

• Handler task/activity 

• Handler location 

• Air concentration 

• Sampling method 

 Date of sign removal 

 Any deviations from the FMP 

In addition to recordkeeping requirements from 7 CFR part 110 “Recordkeeping 

Requirements for Certified Applicators of Federally Restricted Use Pesticides”, this decision 

requires that both the applicator and owner/operator of the application block keep a signed copy 

of the site-specific FMPs and the post-application summary record for 2 years from the date of 

application.

• Applicators and other stakeholders have the flexibility to use EPA’s templates, prepare 

their own FMPs templates, or use other commercially available software with certain 

elements listed above in check-list and/or fill in the blank format. Below are examples of 

other FMP templates available on the internet for structural fumigations that may be 

useful to users when developing FMPs for metam-sodium and metam-potassium soil 

applications:

• http://www.cardinalproproducts.com/Misc/FMP%20Version%203.pdf

• http://www.pestcon.com/techlibrary/fum_mgmt_plan.doc

• http://www.agr.state.ne.us/division/bpi/pes/fumigation_plan.pdf

• http://www.agr.state.ne.us/division/bpi/pes/fumigation_plan2.pdf
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• http://nmdaweb.nmsu.edu/pesticides/Management%20Plans%20Required%20for%20Fu

migations.html

The Agency has provided a template located in the appendix of this document. 

4. Site Specific Response and Management

EPA believes measures for ensuring preparedness for situations when accidents or 

emergencies occur are an important part of the suite of measures necessary to address risks posed 

by fumigants. Therefore, EPA is requiring such measures at the community level in the form of 

educational materials for first responders, and measures for specific sites to ensure early 

detection and quick and appropriate response to situations as they arise. 

Although EPA believes buffers and other mitigation will prevent many future incidents, it 

is likely that some incidents will still occur due to accidents, errors, and/or unforeseen weather 

conditions such as diurnal inversions. Early detection and appropriate response to accidental 

chemical releases is an effective means of reducing risk, as well as addressing the source of the 

release. Reducing risks associated with incidents that may occur in the future is a key part of 

EPA’s soil fumigant decisions. By combining buffers with GAPs, FMPs, and effective 

emergency response, EPA is able to reach a “no unreasonable adverse effects” finding under 

FIFRA. 

To ensure that appropriate response mechanisms are in place in the event of a fumigant 

exposure incident, EPA is requiring that registrants provide training information, in the context 

of their community outreach and education programs to first responders in high-fumigant use 

areas and areas with significant interface between communities and fumigated fields. In 

addition, for situations in which people, homes, or other structures are in close proximity to 

buffer zones, applicators must either monitor buffer zone perimeters or, alternatively, provide 

emergency response information directly to neighbors. Each element is discussed in more detail 

below. 

First Responder Education 

EPA is requiring registrants through their community outreach and education programs 

(see the Community Outreach and Education Section), to ensure that emergency responders have 

the training and information that they need to effectively identify and respond to fumigant 

exposure incidents. EPA believes this will help ensure, in the case of a fumigant accident or 

incident that first responders recognize the exposure as fumigant related and respond 

appropriately. Additional details are included in the Community Outreach and Education 

Section of this document. 

Emergency Preparedness and Response Considerations for the 2008 RED 

Prior to the 2008 RED the EPA received comments from many stakeholders about the 

Agency’s emergency preparedness and response option. Users have commented that notification 

is burdensome and that it is unnecessary if buffer zones are also required. However, community 

groups have commented on the importance of bystanders being informed when fumigations are 
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occurring, since this group of pesticides, compared to other pesticides, has a greater potential to 

move off site and affect people not involved in the application. State regulators have different 

views on this requirement. Some support the sharing of information with neighbors, and some 

states have notification requirements for fumigations with certain products or for certain 

application methods. In addition, some states require notification to chemically sensitive 

individuals in proximity to pesticide applications. Others also had concerns about the 

enforceability of this type of measure and the possible burden on the states to enforce a 

notification requirement. 

California currently requires notification of persons within 300 feet of a methyl bromide 

buffer zone. California strawberry growers consider the 300 foot notification area for methyl 

bromide applications to be an extension of the buffer zone. In areas where a large number of 

people would need to be notified about a planned methyl bromide application, strawberry 

growers indicated that they would rather not use methyl bromide because some communities 

could mobilize to prevent the fumigation from taking place. Some stakeholders also commented 

that it would be protective and less burdensome if EPA required the user to monitor fumigant air 

concentrations at the edge of the buffer for 24 hours after the application to ensure the fumigant 

does not move beyond the buffer at concentrations that exceed EPA’s level of concern. If 

concentrations of concern were detected, the user would be required to implement the emergency 

response measures specified in the fumigant management plan. 

EPA has concluded that bystanders could take steps to protect themselves if they had 

basic information about fumigations and the appropriate steps to take if they experienced 

symptoms of exposure. In a number of fumigant incidents that have occurred, the magnitude and 

severity of the incident could have been significantly reduced if people had such information. 

Similarly, having on-site monitoring will enable site managers to take remedial action (i.e., 

activate the control plan in the FMP) to lower emissions sooner, also resulting in fewer and less 

severe exposures. And, if necessary, site managers would activate the emergency response 

elements of the FMP. 

Providing communities with information about local chemical releases is an important 

part of emergency preparedness programs and is recognized as an effective means of addressing 

risk at the local level. Some states, like Florida and Wisconsin, have requirements for providing 

information to chemically-sensitive individuals about chemicals used nearby so they can take 

steps to protect themselves from potentially harmful exposures (see http://edis.ifas.ufl.edu/pi004

and http://www.legis.state.wi.us/rsb/code/atcp/atcp029.pdf). The requirements in Florida do not 

apply to agricultural chemical applications. Wisconsin also requires fumigators applying metamsodium and metam-potassium products through chemigation to provide written notice to the 

county public health agency and to every individual or household within 1⁄4 miles of the 

chemigation application site (see http://www.legis.state.wi.us/rsb/code/atcp/atcp030.pdf). EPA 

agrees that information about how to recognize and address exposures can help citizens reduce 

potential risk. 

EPA understands that difficult challenges exist when agricultural land borders urban or 

suburban communities. While EPA’s decisions for the fumigants will not alleviate challenges 

that already exist, EPA is allowing options for ensuring emergency preparedness in an effort to 

lessen potential impact on growers, while maintaining the Agency’s protection goals. 
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EPA is not requiring a specific method of providing the information to neighbors, but 

rather that it be done in a way that effectively communicates, in a manner the recipients will 

understand. Some methods may not result in documentation that would be retained. To address 

concerns about enforcement, EPA is requiring that information on how and when the emergency 

response information was delivered, and to whom, be included in the FMP. 

Emergency Preparedness and Response Revisions 

To reduce risks to people who may be near a buffer zone (e.g., at their home or working 

in a nearby field) in the July 2008 RED EPA required applicators to either monitor buffer zone 

perimeters or, alternatively, provide emergency response information directly to neighbors. This 

requirement is not dependent on people actually being present in the nearby buildings and 

homes. In this respect it differs from the quarter/eighth mile buffer zone restriction on certain 

types of occupied structures. Rather, this measure is intended to ensure protection in places 

people may be found present. Whether measures are required depends on the size of the buffer 

zone and how close land (e.g., residential properties and businesses) may be to the buffer zone. 

The Agency received many comments about the Emergency Preparedness and Response 

requirements that suggested the requirements were too complex and confusing. To address these 

concerns, EPA has revised the structure and content of the requirements in the RED Amendment 

to improve clarity. As was outlined in the 2008 RED, it is important to note that site-specific 

Emergency Preparedness and Response measures are only required if there are people, homes or 

businesses within a certain specified distance from the edge of the buffer zone. 

Some comments were received that questioned the rationale behind scaling the 

Emergency Preparedness and Response measures. EPA believes that scaling the size of the 

Emergency Preparedness and Response area will be protective. Generally the larger the buffer 

distance the higher the application rate or the size of the treated area may be, which translates to 

a greater total amount of fumigant being applied and potentially higher exposure in the area 

surrounding the application block. The buffer distances for triggering the Emergency 

Preparedness and Response requirements are scaled to allow the amount of fumigant used (a 

surrogate for potential exposure) determine the applicable distance for implementing this 

requirement. When the area is scaled to the size of the buffer, small buffers which generally 

result from applications to small areas, at low application rates, and/or using low-emission 

application techniques, will have small or no areas to monitor or inform, while larger 

applications will have larger areas to monitor or inform. In addition, to create additional 

incentive to achieve the smallest buffer possible the EPA has included an exception for 

application blocks so fields with the smallest required buffers (25 feet) would not be subject to 

this requirement, since they are most likely using lower application rates, applying to smaller 

areas, and/or using better application methods. Based on changes to the buffer zone section 

regarding overlapping buffer zones, any buffer zone that overlaps with another buffer zone must 

use the maximum distance in the Emergency Preparedness and Response measures to determine 

if monitoring or providing information to neighbors is needed. None of the other distances have 

changed. 
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Many stakeholders also expressed concern over the potential burden the 2008 RED 

requirements may have on applicators and growers. Specifically, the frequency and cost of 

monitoring using sampling devices such as colorimetric tubes were of concern. Stakeholders felt 

the inherent warning properties of chloropicrin and MITC (i.e., eye irritation) were better 

indicators of exposure than available devices. Several of these comments noted concerns with the 

reliability of such devices at low concentrations. Additionally, several stakeholders indicated 

that monitoring is most appropriate and effective at dawn and dusk, the times of day when offsite movement of concentrations is most likely. Based on these comments, the Agency has 

revised the requirement so monitoring is required during those periods when risk of high 

concentrations of fumigant moving beyond buffers is greatest (i.e., at dawn and dusk). As a 

precaution, monitoring is also required once during the night and during the day. 

Additionally, as noted above in the respiratory protection section of this document, due to 

limitations on currently available technology for monitoring, use of sampling devices such as 

colorimetric tubes will not be required at this time. EPA believes that currently available devices 

are likely to be more reliable at fumigant concentrations which exceed EPA’s action level 

concentrations. In fact, some of these action levels are at or near the detection limits for the 

devices available for some fumigants. Additionally, colorimetric devices provide snapshot 

measurements. In conditions that are likely to be more static (e.g., monitoring an indoor 

fumigation such as a grain mill or warehouse) it is likely that minute to minute changes in 

conditions would not be as great as those anticipated for the more dynamic conditions 

characteristic of outdoor field fumigation where exposure concentrations could shift because of 

weather changes or stratification in soil conditions across a single field. 

The Agency is modifying the procedures for monitoring buffer zones because of 

technological limitations of currently available devices for MITC and chloropicrin that are not 

practical or reliable for field use. However, the Agency does believe that quantitative air 

monitoring would enhance safety if the appropriate technology were available as it is for methyl 

bromide. Some equipment manufacturers have indicated interest in developing devices that 

would be more functional and reliable for field fumigation applications (e.g., badge-type 

monitors). EPA encourages such efforts and plans to stay abreast of developments and 

improvements in monitoring devices and will consider this issue again in Registration Review or 

sooner should such monitors become available in the short term. In the interim, buffer 

monitoring for chloropicrin and the MITC generating chemicals will rely on sensory indicators 

(e.g., eye and/or nose irritation) to trigger a response instead of using tubes. Monitoring tubes 

are still required for measuring products that contain more than 80% methyl bromide. 

Finally some comments provided suggestions on how to increase flexibility in how a 

grower may comply with these measures as well as the effectiveness of the option to provide 

information to neighbors. EPA agrees with the importance of users being able to comply with 

these measures and has modified some aspects of the requirements for this option to reduce the 

number of notices an applicator may need to provide to a given neighbor. Also, to enhance the 

effectiveness of the information neighbors would receive, EPA is requiring that the information 

is provided close to when the application is planned to take place and early enough for neighbors 

to make use of the information. EPA believes these modifications will enhance compliance and 

effectiveness of the information if the emergency response criteria are met and applicators 

exercise this option. 
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Emergency Preparedness and Response Requirements 

When are Emergency Preparedness and Response Measures Needed?

If the buffer zone is: AND There is land (e.g. residential properties 

and businesses) NOT in the control of 

the property operator within this 

distance 

from the edge of the buffer zone: 

25 feet < Buffer ≤ 100 feet 50 feet 

100 feet < Buffer ≤ 200 feet 100 feet 

200 feet < Buffer ≤ 300 feet 200 feet 

Buffer > 300 feet or buffer zones 

overlap 

 300 feet 

Then either monitoring of the buffer zone perimeter or providing emergency response 

information to neighbors is required. 

If the buffer zone is 25 feet, the minimal buffer zone size, then the Emergency 

Preparedness and Response requirements are not applicable. Also, if all of the land within 300 

feet of the edge of the buffer zone is under the control of the property operator, then no site 

monitoring or informing neighbors would be required regardless of the size of the buffer zone. 

Fumigation Site Monitoring 

EPA has determined that monitoring of the buffer zone perimeter for fumigants moving 

beyond buffers is an effective approach to protecting bystanders. Under this approach, if the 

person monitoring the buffer perimeter experiences eye or nasal irritation, an early sign of 

exposure to concentrations that exceed the Agency’s action level, then the emergency response 

plan specified in the FMP must be implemented. If other problems occur, such as a tarp coming 

loose, then the appropriate control plan must be activated. Because data indicate that peak 

concentrations sometimes occur on the second day following applications, and the greatest 

potential for concentrations outside buffers may be observed at dawn and dusk, EPA has decided 

that this monitoring must be done at least three times per day during the full buffer zone period at 

dawn, dusk, and once during the night and during the day, to ensure concentrations do not 

exceed the action level which will be specified on product labels. 

Specific requirements include: 

• Monitoring must take place beginning on the day the application begins until the buffer zone 

period expires. 

• Monitoring must be conducted by a certified applicator or someone under his/her supervision. 

• Monitoring for air concentrations above the action level for the fumigant, as determined by 

sensory irritation, must take place in areas between the buffer zone perimeter and residences 

or other occupied areas that trigger this requirement. 

• The person monitoring for perceptible levels must start monitoring approximately 1 hour 

before sunset of the day the application begins and continue once during the night, once at 1 

hour after sunrise, and once during the day until the end of the buffer zone period. 
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• If at any time the person monitoring the air concentrations experiences sensory irritation, 

then the emergency response plan stated in the FMP must be immediately implemented. 

• If other problems occur, such as a tarp coming loose, then the appropriate control plan must 

be activated. 

• The location and any results of the air monitoring must be recorded in the FMP. 

While protective, this site monitoring might be burdensome for users fumigating in areas 

with few people. Therefore, EPA is allowing users the alternative option of providing 

emergency response information directly to neighbors. 

Response Information for Neighbors 

As an alternative to on-site monitoring, the certified applicator supervising the fumigation 

(or someone under his/her direct supervision) would need to ensure that residences, businesses, 

or other sites that meet the criteria outlined below have been provided the required information 

below at least 1 week prior to the fumigant application in a specified field. If after 4 weeks, the 

fumigation has not yet taken place, the information must be delivered again. 

• Information that must be provided includes: 

o The general location of the application block, 

o Fumigant(s) applied including the active ingredient, name of the fumigant 

product(s), and the EPA Registration number, 

o Contact information for the applicator and property owner/operator, 

o Time period in which the fumigation is planned to take place (must not range 

more than 4 weeks), 

o Early signs and symptoms of exposure to the fumigant(s) applied, what to do, and 

what emergency responder phone number to call who to call if you believe you 

are being exposed (911 in most cases), and. 

o How to find additional information about fumigants. 

The method for distributing information to neighbors must be described in the FMP and 

may be accomplished through mail, telephone, door hangers, or through other methods that can 

be reasonably expected to effectively inform people at residences and businesses within the 

required distance from the edge of the buffer zone. 

To clarify this measure, the following example is provided: 

• IF the buffer zone is 125 feet, then these requirements apply to residences within 100 feet of the 

buffer zone. Either the applicator must monitor the area between the dotted house (they must monitor 

where the black dot is) and the buffer zone or residents of the dotted house [people within 100 feet of 

the buffer zone] must be provided emergency response information. 

• So the dotted houses would need to be informed, but the location of the cross-hatched house would 

not prompt any action. 

Figure 9. Example Site Map for Informing Neighbors. 
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 If there are no residences or other occupied structures within 300 feet of the edge of the 

buffer zone, or if the buffer distance is the minimum of 25 feet, neither site monitoring nor 

providing information to neighbors is required. 

5. Notice to State Lead Agencies 

Ensuring fumigant users understand and comply with the new label requirements is an 

important component of the fumigant risk mitigation package since these requirements are 

designed to mitigate risks of concern for bystanders, handlers, and workers. Knowledge of the 

location and timing of fumigant applications allows enforcement officials to focus their 

compliance assistance and inspection efforts around periods when, and places where, 

fumigations are expected to occur. Therefore, in the July 2008 RED, the Agency required written 

notification of the appropriate state or tribal lead agency prior to fumigant applications. 

Following publication of the July 2008 REDs, the Agency received feedback from some 

states that were interested in receiving the notice because it would enhance their ability to 

provide technical assistance and assure compliance. However, the Agency also received 

comments from states that were concerned about the notification requirement largely due to 

resource constraints. Some states also indicated that they are already well-informed about when 

and where fumigations take place, and receiving specific notice of applications would create a 

paperwork burden rather than aid their compliance assistance and assurance programs. Some 

states recommended that, in lieu of receiving notice of fumigations, states could modify their 

cooperative agreements with EPA to incorporate specific strategies for assuring compliance with 

the new fumigant labels. States also suggested that rather than providing notice directly to states, 

fumigators could enter application information into a registrant-developed and maintained 

database. They suggested this would be an appropriate mechanism because it would standardize 

Treated field 

Buffer zone 

45 ft 

288 ft 

125 ft 

100 ft 
127

and streamline the process for applicators to provide the required information, and states could 

access and utilize information more quickly, with greater ease, and using fewer state resources. 

Based on consideration of public comments, the Agency still believes that compliance 

assistance and assurance is a critical component of the soil fumigant mitigation. EPA agrees that 

some states already have mechanisms in place to provide them with information needed to assist 

and assure compliance with new fumigant requirements, but other states are in need of additional 

information to accomplish this objective. The Agency also believes that all states in which 

fumigants are used will need to modify their cooperative agreements, to some extent, to 

incorporate strategies for compliance assistance and assurance to aid the transition from current 

labels to labels that reflect the new mitigation. 

While the Agency will continue to work with all state and tribal lead agencies on efficient 

ways to obtain the information needed to plan and implement compliance assistance and 

assurance activities, the Agency is currently retaining the notification requirement only for state 

and tribal lead agencies that choose to be notified of fumigant applications. The Agency plans 

to provide a website listing these state and tribal lead agencies and how and when these agencies 

want applicators to provide to them the following information: 

o Applicator and property owner/operator contact information (name, telephone 

number, and applicator license number) 

o Location of the application block(s) 

o Name of fumigant(s) products(s) applied including EPA Registration number 

o Time period in which fumigation may occur 

 For states already requiring such information through an existing state process, 

applicators will not be required to comply with this requirement. For example, the California 

Department of Pesticide Regulation already obtains this information as part of their permitting 

process for fumigant applications. 

The Agency will work with all states to amend their cooperative agreements to include 

strategies for compliance assistance and assurance, which will be particularly important over the 

next several years as the new mitigation measures are implemented. For states that do not 

choose to be notified of fumigant applications, modification of their cooperative agreements 

must include the methods these agencies will use to survey fumigation application periods and 

locations. 

6. Training for Applicators and Training Information for Other Handlers 

Soil fumigation is an inherently complex activity involving specialized equipment and 

application techniques. Additionally, the mitigation measures required as part of these decisions 

will introduce new requirements in the form of more detailed instructions and restrictions on soil 

fumigations. Failure to adequately manage fumigant applications increases risks to handlers 

involved in the fumigation, nearby workers, and other bystanders. Incident data show that a 

number of fumigant incidents are the result of misapplications, failure to follow label 

requirements and other safety precautions, and other errors on the part of fumigant applicators. 

Although states have certification programs, some of which include a specific category or 
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subcategory for soil fumigation, there currently is not a consistent standard across states and 

regions where soil fumigation is done. Additionally, the federal certification program currently 

has no category for soil fumigation, and while EPA is considering the development of a category 

for soil fumigation, the potential changes to the federal certification program and worker safety 

regulations to include a soil fumigation category are not anticipated in the near future. 

EPA believes that training is an effective way to increase applicators’ skill and 

knowledge so they are better prepared to effectively manage the complexities and risks 

associated with soil fumigation. Further, training is a means of ensuring fumigators are able to 

understand and comply with revised fumigant labeling. Therefore, EPA determined that training 

to establish a national baseline for safe fumigant use, developed and implemented by registrants, 

will help enhance fumigators’ ability to adequately manage the complexities of soil fumigation 

and failure to comply with fumigant product labeling. EPA also determined that providing 

additional safety information to other fumigant handlers will help them understand and adhere to 

practices that will help handlers protect themselves from risks of exposure. 

Soil Fumigation Training Considerations 

In comments on fumigant risk management options, stakeholders were broadly 

supportive of additional training for applicators and handlers. During the Phase 5 and post-RED 

comment periods, the majority of stakeholders, including growers, community groups, farm 

workers, states, and registrants expressed strong support for increased training for applicators 

and other handlers. Several comments noted that fumigant incidents affecting both fumigant 

workers and bystanders could have been prevented or mitigated if applicators had better training 

about correct practices and procedures. 

The Agency agrees that additional training for fumigant applicators and handlers will 

help educate and inform these workers, thus decreasing the likelihood of both incidents and 

noncompliance. EPA believes fumigant-specific training for applicators and additional training 

information for handlers also will help reduce the magnitude and frequency of exposure 

incidents and, coupled with the other mitigation measures described in this decision, will address 

risks of unreasonable adverse effects from the use of soil fumigants. 

It is important to note that training developed and provided by registrants as required by 

this RED is separate and distinct from state certification programs. EPA encourages registrants, 

in developing their training proposals, to work with states where their products are used to 

identify opportunities to build on and complement state programs. However, the training 

programs required as part of this decision are intended to be separate from the state certification 

process and will be developed and administered by registrants. Individual state regulatory 

agencies have the option of working with registrants on these activities, but are not required to 

do so. It is important to note that some fumigant registrants have already developed soil 

fumigant training programs that will serve as a good basis for this expanded effort. 

As noted above, several states have high-quality certification programs for fumigators 

that include exams to test the competency of fumigators. EPA recognized that for applicators to 

become certified in those states, they must acquire the knowledge and skill necessary to pass the 

exam. But several stakeholders commented that training opportunities are varied across the 
129

country, and the scope and detail of information provided in available training is not consistent. 

EPA is also concerned that information in existing programs will need to be substantially 

updated as a result of new requirements associated with this decision and the label changes 

which will implement it. Although EPA is considering revisions to the federal certification and 

training program in the future to include a soil fumigation category/subcategory, EPA believes 

that registrants have access to resources and materials to best develop and deliver training in the 

interim. 

EPA stresses that registrant training programs will be separate from the state certification 

process and will be developed and administered by registrants in coordination with EPA. EPA 

will, however, work with state organizations and training experts to explore opportunities for the 

registrant programs to supplement any existing state programs to provide additional training 

resources for fumigators working in those states. EPA will also work with state lead agencies 

and extension programs to review training program proposals, the content for the programs and 

materials, and proposed vehicles for delivery. 

During the post-RED comment period, the Agency received comments from several 

states asking that the applicator training requirements be coordinated with existing state 

certification and training programs. The Agency agrees that for states that have existing soil 

fumigation certification programs that address the same training elements required of the 

registrant soil fumigant training programs, as outlined in this section of the RED addendum, 

applicators should be able to complete the state certification program in lieu of completing the 

registrant soil fumigation training. For the state soil fumigation certification program to qualify, 

both EPA and the state must agree that the program satisfies the applicator training elements 

required in the RED. 

Pesticide labels will state that the certified applicator supervising that application must 

have successfully completed, within the last 36 months, a metam training program made 

available by the registrant. The Fumigant Management Plan must document when and where the 

training program was completed. This requirement for registrant-provided applicator training 

does not supersede or fulfill state requirements, unless the state has expressly acknowledged that 

the registrant training may substitute for state requirements 

Training for Applicators Supervising Fumigations 

The July 2008 RED required registrants to develop and implement training programs for 

applicators in charge of soil fumigations on the proper use of and best management practices for 

soil fumigants. This training would be required as a condition of use by product labeling. 

During the public comment period on the proposed mitigation measures and the post-RED 

comment period, stakeholders were broadly supportive of additional training for fumigators, but 

concerns were raised with regard to implementation of the training. The Agency also received 

comments from state representatives and pesticide applicator training organizations, such as the 

Association of American Pesticide Control Operators, Association of American Pesticide Safety 

Educators, and Certification & Training Assessment Group, expressing concern over EPA’s 

decision to implement the training via labeling and raising questions over compliance and state 

enforcement of such a requirement and the potential for conflict or redundancy with state 

certification and training programs. Various stakeholders recommended that, rather than a label-
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mandated training requirement, the Agency, instead, should require registrants to develop and 

implement training for soil fumigant applicators as a condition of registration. 

The Agency’s goal in requiring soil fumigation training for applicators is to ensure that 

all applicators in charge of soil fumigations understand the safe use of soil fumigants and in how 

to apply products in compliance with new product labeling, including provision required by the 

RED. Given the unique properties of soil fumigants and their application and safety procedures 

compared with other agricultural and non-agricultural pest control practices, the inherent 

complexities involved in soil fumigant applications, and the additional complexities that will 

arise with the implementation of the REDs, the Agency feels that additional training, above and 

beyond that available currently, will be needed. The states that currently have certification 

programs that include soil fumigation categories will not have requirements pertaining to the 

new mitigation and their programs will need to be modified. EPA agrees that making the 

required training programs a condition of registration is an important means of ensuring that such 

training is ultimately developed and implemented. However, it would not ensure that all 

individuals in charge of soil fumigant applications avail themselves of the training. The Agency 

believes that making successful completion of the training a condition of use is also important to 

achieve this goal. Therefore, EPA has decided that development and delivery of training will be 

a required in the DCI that accompanies this amended RED and successful completion of the 

training will remain a condition of use. 

Each registrant must develop and implement training programs for applicators in charge 

of soil fumigations on the proper use of and best practices for soil fumigants. Registrants will be 

required to submit proposals for these programs as data requirements that will accompany this 

RED. EPA will review each program and determine whether it adequately addresses the 

requirements specified in the DCI. The proposal must address, among other elements, both the 

content and the format for delivering training. The Agency acknowledges the value of hands-on 

training in the field, but recognizes that may not be feasible in all instances. The Agency 

welcomes and is actively seeking participation from state lead agencies and extension programs 

in the evaluation of the registrant training proposals and materials that are submitted. 

The training programs must address, at a minimum, the following elements: (1) how to 

correctly apply the fumigant, including how to comply with new label requirements; (2) how to 

protect handlers and bystanders; (3) how to determine buffer zone distances; (4) how to develop 

a FMP and complete the post-fumigation application summary; (5) how to determine when 

weather and other site-specific factors are not favorable for fumigant application; and (6) how to 

comply with required GAPs and how to document compliance with GAPs in the FMP. In 

addition, based on comments received during the post-RED comment period, the Agency is 

adding a seventh training element—training programs must also include information on how to 

develop and implement emergency response plans—to ensure that applicators are prepared in the 

event that a problem develops during or shortly after the fumigant application. EPA is also 

requiring registrants to incorporate a mechanism for evaluating the effectiveness of their training 

programs at conveying the required information to participants and for determining whether 

participants have successfully completed the training program. 

To assist states in enforcing these training requirements, the registrants will be required to 

(1) develop a database to track which certified applicators have successfully completed the 
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training, (2) make this database available to state and/or federal enforcement entities upon 

request, and (3) provide documentation (e.g., a card) to each training participant who 

successfully completes the training. This documentation shall include the applicator’s name, 

address, license number, and the date of completion. Applicators must provide to federal, state, 

or local enforcement personnel, upon request, this documentation that verifies successful 

completion of the appropriate training program(s). 

In the July 2008 RED, the Agency required applicators supervising fumigations to 

complete the training annually. During the post-RED public comment period, the Agency 

received comments from various stakeholders indicating that the substance and content of 

training would not change significantly from year to year, and that an annual training 

requirement for applicators would be excessive and burdensome to both applicators and 

registrants and was unnecessary. As a result of these comments, the Agency has decided to 

require applicators supervising fumigations to have successfully completed the program within 

the preceding 36 months and to document when and where the training program was completed 

in their FMPs. This may be accomplished, for example, by simply attaching a copy of the 

training documentation provided by the registrant to the FMP. The registrant also must be able 

to provide to federal, state, or local enforcement personnel, upon request, the names, addresses, 

and certified applicator license numbers of persons who successfully completed the training 

program, as well as the date of completion. 

Based on questions received during the post-RED comment period, the Agency is 

clarifying that applicator training requirements are active ingredient-specific rather than productspecific. That is, applicators who apply more than one of the soil fumigant active ingredients 

(i.e., methyl bromide, chloropicrin, metam-sodium, metam-potassium, or dazomet) will be 

required to complete training for each soil fumigant active ingredient they apply, but not for each 

different product containing the same active ingredient(s). Further, EPA encourages the soil 

fumigant registrants to jointly develop programs to reduce the redundancy of this training 

requirement. For example, a substantial portion of the required training is universal to all soil 

fumigants. Therefore modules addressing the information common to all could be generic and 

each fumigator would participate in those modules, while separate modules addressing active 

ingredient-specific content could be provided to those fumigators supervising applications with 

those active ingredients only. Documentation provided to trainees could indicate the active 

ingredient modules completed. While EPA sees efficiencies in such an approach, it will be the 

registrants’ choice as to how they will comply with the requirement to develop and implement 

training programs.

Training Materials for Handlers 

EPA is requiring registrants to prepare and disseminate training information and 

materials for other fumigant handlers, i.e., those working under the supervision of the certified 

applicator in charge of fumigations. The Agency is requiring registrants to submit proposals for 

these materials through the data call-ins that will accompany this RED. EPA will review these 

materials to determine whether they adequately address the requirements specified in the DCI. 

The Agency welcomes and is actively seeking participation from state lead agencies and 

extension programs in the evaluation of these handler training materials. 
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 The training materials must address, at minimum, the following elements: (1) what 

fumigants are and how they work, (2) safe application and handling of soil fumigants, (3) air 

monitoring and respiratory protection requirements for handlers, (4) early signs and symptoms of 

exposure, (5) appropriate steps to take to mitigate exposures, (6) what to do in case of an 

emergency, and (7) how to report incidents. Registrants must provide this training information 

through channels open to the public (e.g., via a website). Pesticide labels will require that 

applicators supervising fumigations provide this training information to handlers under their 

supervision before they perform any fumigant handling task, or they must ensure that handlers 

have been provided the required information within the preceding 12 months. The label will also 

require that the training information be provided in a manner that the handler can understand. 

Applicators supervising fumigations must ensure the FMP includes how and when the required 

training information was provided to the handlers under their supervision. 

“The certified applicator must provide fumigant safe handling information to each handler 

involved in the application in a manner that they can understand prior to performing any 

fumigant handling task or confirm that each handler participating in the application has received 

fumigant safe handling information in the past 12 months.” 

During the post-RED comment period, no substantive comments were received that 

resulted in changes to the RED requirements for training materials for handlers, as a result, these 

requirements are identical to those published in the July 2008 RED. However, during the 

comment period, the Agency received comments indicating that there was some confusion about 

whether fumigant handlers working under the supervision of the certified applicator would be 

required to be trained, i.e., participate in a training program developed by the soil fumigant 

registrant(s), or whether handlers would need only to be provided with training information and 

materials. The Agency wishes to clarify that handler participation in a registrant training 

program, per se, is not required. As noted above, applicators supervising a soil fumigation will 

be required to provide the registrant-developed, EPA-approved training information to handlers 

in a manner that they can understand prior to performing any fumigant handling task, or 

applicators must ensure that the handler has been provided the required information within the 

proceeding 12 months. 

7. Community Outreach and Education Program 

EPA understands from public comments, site visits, and stakeholder meetings, conducted 

as part of the soil fumigant review, that there is often a fundamental lack of information and 

communication about soil fumigants within communities where soil fumigation occurs, which 

has raised health and safety concerns among community members. This lack of information and 

communication has led to inappropriate responses in cases where fumigants have moved off site 

and into communities. This also has led, in some cases, to unwarranted concern and anxiety 

among communities about the risks associated with the use of fumigants. The Agency believes 

that outreach and education to communities where soil fumigation occurs is an important 

component of the overall package of measures to address bystander risk. Community outreach 

will address the risk of acute bystander exposure by informing community members in high-use 

areas about buffer zones and their characteristics and purpose, the meaning of posted warning 

signs, the importance of not entering buffer zones, how to recognize early signs of fumigant 

exposure, and how to respond appropriately in case of an incident. 
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In the July 2008 RED, the Agency required registrants to develop and implement 

community outreach and education programs to address these needs. At a minimum, these 

programs were to include the following elements: (1) what soil fumigants are and how they 

work, (2) what buffer zones are, (3) early signs and symptoms of exposure, (4) appropriate steps 

to take to mitigate exposures, (5) what to do in case of an emergency, and (6) how to report an 

incident as well as a plan for evaluating the effectiveness of these programs. Few details on how 

the programs would be implemented were provided in the RED. Rather, during the post-RED 

comment period, the Agency sought feedback from the registrants and other stakeholders on how 

best to design and target programs to community members in high-use areas. The Agency 

encouraged the registrants to work with existing community resources, such as community 

health networks, for disseminating information and implementing community outreach 

programs. 

During the post-RED comment period, the Agency received some comments from 

stakeholders that suggested that having registrants develop and implement a community outreach 

and education program is unnecessary and likely to needlessly raise heath and safety concerns 

among community members, and such a requirement could draw scarce resources from other 

registrant stewardship efforts. As noted previously, the Agency believes that providing basic 

information about soil fumigants and buffer zones as well as information on what to do in the 

event that an incident occurs to communities in high fumigant use areas is an important 

component of the overall package of risk mitigation measures to address bystander risk. EPA’s 

community outreach requirements do not preclude other voluntary stewardship programs or 

activities targeted to community members or the applicator/grower community, but rather are 

meant to help ensure that community members in high fumigant usage areas are informed about 

soil fumigant safety and better able to respond appropriately if an incident were to occur. 

Few recommendations and no specific proposals for these programs were received during 

the post-RED comment period. Therefore, the Agency is identifying minimum requirements that 

each registrant must fulfill when developing its community outreach programs in response to a 

DCI that will be issued. The Agency remains open to considering additional registrant outreach 

program elements that address the same needs and goals as the program requirements described 

below in their response to the DCI. EPA notes that some stakeholders have suggested that 

programs focusing on specific target audiences may be more effective in providing useful 

information in a meaningful way than broadcast messages to entire communities. Registrants 

have indicated that they will provide proposals for such programs in late May 2009. EPA looks 

forward to these proposals and will consider the extent to which they contribute to meeting the 

goals of the community outreach programs required by the RED. 

In the absence of acceptable alternative proposals, registrants, will be required to provide 

information to the communities in the form of monthly public service announcements (PSAs) 

distributed via local radio stations or newspapers in high-use fumigant areas during the 

fumigation season(s) in those areas. As per the requirements included in the July 2008 RED, at a 

minimum, registrants must include the following information in their community outreach 

messages: (1) what soil fumigants are and how they work, (2) what buffer zones are, (3) early 

signs and symptoms of exposure to MITC, (4) appropriate steps to take to mitigate exposures to 

MITC, (5) what to do in case of an emergency, and (6) how to report an incident as well as a 
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plan for evaluating the effectiveness of these programs. Based on comments, EPA has decided 

that information on the meaning of posted warning signs is also important to help ensure the 

signs convey the needed information about the importance of staying out of buffer zones and 

treated areas. 

The Agency is requiring registrants to implement their outreach programs in communities 

located in areas where there is high soil fumigant use. For the purposes of the RED addendum, 

high-use areas are considered at the county level. To identify these areas, the Agency is 

proposing the process for identifying high-use areas in the subsection following the section on 

information for first responders. However, the Agency is willing to consider alternative 

proposals for identifying high soil fumigant-use areas, based on additional data sources and 

alternate approaches identified by the registrant(s) and other stakeholders. 

Information for First Responders 

In the July 2008 RED, the Agency required registrants to ensure that first responders in 

areas with high fumigant usage have the training and information that they need to effectively 

identify and respond to fumigant exposure incidents. Specifically, the registrants were required 

to provide information and/or training to first responders, which at a minimum, included the 

following elements: (1) how to recognize the early signs and symptoms of fumigant exposure, 

(2) how to treat fumigant exposures, and (3) how fumigant exposure differs from other pesticide 

exposure. In addition, the registrants were required to provide material safety data sheets to first 

responders for both the fumigant applied (e.g., metam-sodium and metam-potassium) as well as 

the active compound generated (e.g., MITC). Few details on how the education programs would 

be implemented were provided in the RED. Rather, during the post-RED comment period, the 

Agency sought feedback from the registrants and other stakeholders on how best to design and 

target programs to first responders in high-use areas. The Agency encouraged the registrants to 

work with state and local emergency response coordinators to identify needs and opportunities to 

supplement any information already included in state and local training for first responders about 

soil fumigants specifically. 

During the post-RED comment period, the Agency received comments from several 

registrants indicating that rather than requiring registrants to implement face-to-face training 

programs, the Agency should consider allowing the required first responder training information 

to be conveyed via written materials to state and local emergency response agencies, which 

would provide these agencies the ability to incorporate this information into their existing 

training programs. Other comments indicated that even if training programs were developed, it 

would be difficult to ensure participation of first responders. The Agency’s goal for the first 

responder training program is to ensure that first responders in high use fumigant areas have 

access to the information that they need to be able to quickly and effectively identify an exposure 

that is fumigant related and respond appropriately. The Agency agrees that this goal can be met 

by requiring the soil fumigant registrants to develop informational materials on the soil 

fumigants and distribute this information to first responders (i.e., police, fire, rescue, emergency 

medical services, and others who respond to “911” calls) in high soil fumigant-use areas. This 

would then provide the first responder entities the ability to incorporate this information into 

their existing first responder training programs as they best see fit. This recommendation has 

been incorporated into the RED amendments for the soil fumigants. 
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The Agency is willing to consider additional registrant proposals so long as they address 

the same needs and achieve the same goals as the program requirements described below. At a 

minimum, registrants will be required to develop and disseminate chemical-specific soil 

fumigant training materials to first responders i.e., police, fire, rescue, emergency medical 

services, and others who respond to “911” calls) operating in high fumigant-use areas. As a data 

requirement in the DCIs that will accompany the REDs, registrants must submit proposals 

detailing how they will (1) identify the firstresponder entities in high soil fumigant-use areas to 

which they will disseminate the training materials, and (2) provide materials to the first 

responders in these areas. Additionally registrants must provide draft copies of the training 

materials for EPA review and approval. As per the requirements included in the July 2008 RED, 

at a minimum, the materials must convey the following information to first responders: (1) how 

to recognize the early signs and symptoms of metam-sodium or metam-potassium fumigant 

exposure, (2) how to treat metam-sodium or metam-potassium fumigant exposures, and (3) how 

metam-sodium or metam-potassium fumigant exposures differ from other pesticide exposures as 

well as (4) copies of material safety data sheet(s) for the fumigant applied as well as for the 

active compound generated, if applicable. Training materials can take a number of forms, 

including: brochures, fact sheets, CDs, videos, web-based training materials, etc., as long as 

these materials incorporate, at a minimum, the information requirements identified above. 

The Agency is requiring registrants to target their first responder training information to 

those communities located in high soil fumigant-use areas. For the purposes of the RED, highuse areas are considered at the county level. To identify these areas, the Agency is proposing the 

following process. However, the Agency is willing to consider alternative proposals in the 

registrants’ response to the DCIs for identifying and targeting high-use soil fumigant areas, based 

on additional data sources and alternate approaches identified by the registrant(s). 

Process for Identifying High-Use Fumigant Areas: 

 Identifying high-use areas for metam-sodium and metam-potassium is a two-step process 

because reliable fumigant use data is not available at the county level from either publicly 

available data sources or EPA proprietary data sources. First, the states with high use of metamsodium and metam-potassium have been identified by the Agency using EPA proprietary data. 

[Although state-level data are available from USDA’s National Agricultural Statistics Service 

(NASS), EPA proprietary data are more robust.] Second, the high-use counties for metamsodium and metam-potassium within those states must be identified. The second step, identifying 

high-use counties, will be the registrant’s responsibility, using the process defined below. 

• Step 1: Identifying States with High Use of Metam-Sodium and Metam-Potassium: The 

Agency is defining states with high usage of metam-sodium and metam-potassium as 

those states where, on average, more than 100,000 lbs of metam-sodium and metampotassium are applied annually. To determine those states where, on average, more than 

100,000 lbs of metam-sodium and metam-potassium has been applied annually, the 

Agency obtained data on the average number of pounds of metam-sodium and metampotassium applied in all states across a ten–year period (1999-2008) using EPA 

proprietary data. To view the Agency’s analysis of this data, please see the Biological and 

Economic Analysis Division’s memo, “Process for Defining High-Use Fumigant Areas at 
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State and County Levels” dated May 14, 2009 and supporting documentation located in 

the metam-sodium and metam-potassium docket at EPA-HQ-OPP-2005-0128. 

• Step 2: Identifying Counties with High Use of Metam-Sodium and Metam-Potassium:

For each of the high-use states that the Agency identified in Step 1, the registrants will be 

required to identify the counties where use of metam-sodium and metam-potassium may 

be high. Because county-level fumigant usage data is not publicly available and EPA 

proprietary data are not reliable, crop acreage should be used as a surrogate indicator for 

fumigant usage. Crop acreage can be obtained for major use sites of metam-sodium and 

metam-potassium from the publicly available 2007 USDA Census of Agriculture. Crop 

acreages for each of the major use sites for metam-sodium and metam-potassium should 

be obtained for each the major use sites for metam-sodium and metam-potassium and 

then summed by county. All counties making up at least the top 90% of acreage in a state 

are considered high-use areas. Registrants will be required to target each of these highuse counties for community outreach programs. 

For the purposes of this analysis, the Agency defines a “major use site” as any crop that 

has more than 5% crop treated annually or more than 1,000,000 lb of metam-sodium and 

metam-potassium applied annually. 

Example Identifying High-Use Fumigant Areas for Metam Sodium and Metam-Potassium in 

California: 

 To help explain the process for identifying high-use fumigant areas for metam-sodium 

and metam-potassium the Agency is providing the following example, which identifies the highuse counties for the soil fumigant, metam-sodium and metam-potassium, usage in California. 

• Step 1: Identify States with High Use of Metam-Sodium and Metam-Potassium: 

o Based on its analysis of proprietary data, the Agency has identified the following 

high-use states for metam: California, Washington, Idaho, Oregon, Wisconsin, 

Michigan, Florida, Minnesota, North Carolina, Virginia, Arizona, Nevada, 

Georgia, Colorado, and North Dakota. This example will focus only on 

identifying the counties in California with high use of metam. The same process 

would be applied to other high-use states. 

• Step 2: Identify the Counties in California with High Use of Metam-Sodium and MetamPotassium:

o EPA has identified the following as the major use sites of metam-sodium and 

metam-potassium: artichokes, cabbage, cantaloupes, carrots, onions, peanuts, 

peppers, potatoes, spinach, squash, tomatoes, and watermelons. 

o Using the 2007 USDA Census of Agriculture, registrants will need to obtain 

harvested crop acreage data for each of the 12 major use sites for metam 

identified above for each county in California. (An example of this analysis is 

provided as a supporting document to the Biological and Economic Analysis 

Division’s memo “Process for Defining High-Use Fumigant Areas at State and 

County Levels” dated May 14, 2009 which is located in the metam-sodium and 

metam-potassium docket at EPA-HQ-OPP-2005-0125. 
137

o Registrants will then need to sum the total number of combined crop acres for 

these major use sites for each county in California and then select all the counties 

that make up at least the top 90% of acreage in the county. [An example of this 

analysis is also provided as a supporting document to the Biological and 

Economic Analysis Division’s memo “Process for Defining High-Use Fumigant 

Areas at State and County Levels” dated May 14, 2009 which is located in the 

metam-sodium and metam-potassium docket at EPA-HQ-OPP-2005-0125.] 

As with the training for fumigant applicators and handlers and the community outreach 

program that the Agency is requiring, the first responder training requirements are intended to be 

part of the registrants’ long-term product stewardship. The Agency encourages registrants to 

work with appropriate state emergency response entities in these areas to ensure that the 

appropriate first responder entities are being targeted and that the information being provided to 

first responders is both useful and presented appropriately. 

8. Ambient Air Monitoring Program 

In the July 2008 Metam-Sodium and Metam-Potassium RED, the Agency required the 

registrants to develop an air monitoring program in high-use areas to evaluate whether ambient 

air concentrations exceed EPA’s level of concern and help the Agency to determine whether the 

RED mitigation measures are adequately protective of bystanders and decide whether additional 

risk management measures are warranted. 

During the post-RED comment period, the Agency received 2008 ambient air monitoring 

data for MITC in Southern Franklin County, Washington, from the Washington State University 

(WSU) Food and Environmental Quality Lab (FEQL) [“2008 MITC Residential Community Air 

Assessment: Franklin County, Washington” (LePage and Goss 2008); MRID 47732802]. 

Agency analysis of ambient air data collected by WSU-FEQL in Southern Franklin County, 

Washington in 2005, 2007, and 2008 show exceedances of the Agency’s level of concern for 

MITC (MOE < 10) at two monitoring stations in the fall of 2008. Agency analysis of ambient air 

data for MITC in California from 1997-2001 developed by the California Air Resources Board 

(CARB) identified exceedances of the Agency’s short- and intermediate-term levels of concern 

(MOE < 30) at three sample locations (indoor and outdoor) in Bakersfield, California, in the 

summer of 1997. In addition, the Agency is aware of a number of on-going ambient monitoring 

efforts going on in certain parts of the country including California and the Pacific Northwest. 

(For additional information on the Agency’s analysis of both the WSU-FEQL and CARB 

ambient air monitoring data, please see “Metam Sodium: Third Revision of the HED Human 

Health Risk Assessment, DP# 293354 located in the metam–sodium and metam-potassium 

docket at: EPA-HQ-OPP-2005-0125.) The Agency is also concerned about chronic exposures 

and is seeking additional toxicity data on the long-term effects from inhalation exposure to 

MITC. However, none of the available ambient air studies conducted so far adequately reflects 

potential long-term concentrations of MITC. 

As part of the RED, the Agency is implementing a number of mitigation measures 

designed to reduce air concentrations of MITC. To help the Agency to determine if these 

mitigation measures are adequately protective of bystanders and to decide whether additional 

risk management measures are warranted, the Agency is requiring registrants to conduct ambient 
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air monitoring programs in six counties in the United States with the highest usage of metamsodium and metam-potassium, as identified in EPA’s analysis to identify high-use areas for 

implementing their community outreach and first responder training programs (see the 

Community Outreach Program and First Responder Education sections for details). Registrants 

are required to develop air monitoring programs that will enable the Agency to evaluate both: (1) 

potential maximum peak air concentrations in areas of high seasonal use and (2) potential 

community-level chronic air concentrations in areas of high metam-sodium and metampotassium use. The air monitoring should begin in 2010 and continue thru the 2011 and 2012 

application seasons. This data will allow the Agency to evaluate whether the package of 

mitigation measures, including buffer zones, have effectively reduced ambient air concentrations 

and will be included in the reevaluation for metam-sodium and metam-potassium in registration 

review. EPA encourages the registrants to work with existing air monitoring programs such as in 

CA and WA or the registrants may develop their own program. The registrant’s proposal for 

developing and implementing an air monitoring program will be required as a data requirement 

in the data call-in. Proposals should identify the six high use counties where ambient air 

monitoring will take place. EPA will review these proposals to determine whether they 

adequately address the requirements specified in the DCI. 

 

Environmental Risk Management 

In the July 2008 RED, EPA addressed the concerns about both aquatic and terrestrial 

risks which are discussed in Section III.C. The July 2008 RED also stated that EPA believed 

that mitigation measures detailed in the Human Health Risk Mitigation Section would also 

reduce ecological risks. The Agency stated that although buffer zones and GAPs do not directly 

reduce the potential risk to ecological organisms, these mitigation measures do provide an 

incentive to reduce fumigant application rates and individual treatment areas which in turn will 

contribute to lower exposure and risks for non-target organisms. 

The July 2008 RED discussed exposure to terrestrial organisms, such as birds and 

mammals, which could occur via inhalation of MITC. Potential exposure to aquatic 

invertebrates and fish may occur from surface runoff/leaching and drift (wind) of MITC. 

A species-specific analysis for the California Red-Legged Frog case has been conducted 

for metam-sodium and metam-potassium and it major degradate, MITC. The Agency 

determined that MITC “May-Affect” this species. The Agency’s assessment is currently with 

the Services (i.e., the U.S. Fish and Wildlife Service and the National Marine Fisheries Service). 

After the final determination has been made, the Agency may require other mitigation. 

 

The July 2008 RED also discussed uncertainty associated with potential risk to non-target 

plants, given that there are no data available. Additional plant toxicity data for MITC is being 

required. 

The July 2008 RED noted that based on the fate parameters of MITC, it should not 

persist in terrestrial environments because of volatilization and degradation and the available 

non-targeted monitoring data does not detect MITC in the ground-water samples within the U.S. 

However, MITC is highly soluble in water and has a low adsorption to soil which suggests that 

there is a potential of leaching to shallow groundwater under flooded and saturated conditions. 
139

Also, if intense rainfall or continuous irrigation occurs there is potential for MITC to move to 

surface water. Due to the importance of adequate soil moisture as described in the GAP section 

and the knowledge that volatilization is metam-sodium and metam-potassium’s most important 

route of dissipation, EPA required the following language in the July 2008 RED taking these 

factors into consideration: “While metam-sodium, metam-potassium, and their major degradate 

MITC have certain properties and characteristics in common with chemicals that have been 

detected in groundwater (MITC is highly soluble in water and has low adsorption to soil), 

volatilization is this chemical's most important route of dissipation.” 

While the Agency believes that volatilization is this chemical’s most important route of 

dissipation, it is being removed from the groundwater statement because volatilization is 

addressed in other areas of the mitigation package. The new language will state, “Metamsodium, metam-potassium and their major degradate MITC have certain properties and 

characteristics in common with chemicals that have been detected in groundwater (MITC is 

highly soluble in water and has low adsorption to soil).” 

The July 2008 RED also included language required for both tarped and non-tarped 

metam-sodium and metam-potassium applications to minimize potential for leaching. During 

the post-RED comment period commenters stated that the following language was not clear or 

enforceable: “For untarped applications of metam-sodium and metam-potassium, potential 

leaching into groundwater and runoff into surface water can be reduced by avoiding applications 

when heavy rainfall is forecasted to occur within 24 hours.” 

 EPA would like to clarify that the statement was meant to be advisory and not 

mandatory. However in an effort to clarify the requirement the Agency has revised the July 

2008 RED language as follows, “For untarped applications, leaching and runoff may occur if 

there is heavy rainfall after soil fumigation.” The revised statement is based on information 

presented in a 2007 article by Zhang and Wang12. 

Please see section V of this document for the revised ground water label statements. 

b. Sewer Root Control Use 

During the post-RED comment period, the Agency received additional usage and 

occupational exposure information from the two metam-sodium sewer use registrants, Sewer 

Sciences, Inc. and Douglas Products and Packaging Company, which allowed the Agency to 

refine the metam-sodium non-cancer (i.e., short-term and intermediate-term) and cancer sewer 

use risk estimates. (To view the revised metam-sodium human health risk assessment, which 

incorporates the revised sewer use risk estimates, please see: Metam Sodium: Third Revision of 

the HED Human Health Risk Assessment, 04/30/09, D357118 in the metam-sodium docket at 

EPA-HQ-OPP-2005-0125.) The comments specifically focused on the inputs of application rate, 

the amount of product handled per day, the amount of time applicators may be exposed during a 

work day, and the typical number of days per year that metam-sodium is used. A short summary 

 

12 Zhang, Y. and Wang, D .2007. Emission, distribution, and leaching of methyl 

isothiocyanate and chloropicrin under different surface containments. 

Chemosphere, 2007 Jun; 68(3): 445-454. 
140

of the information provided and an explanation of how it was used by the Agency in revising it 

risk assessment is summarized below. 

• Application Rate: The Agency revised the application rate used in the 2008 RED 

calculations (0.212 lb ai/A) based on typical application rate data submitted by Douglas 

Products and Packaging (0.111 lb ai/A) for Sanafoam Vaporooter II (EPA Registration 

No. 1015-70) and the application rate information listed on Sewer Science Inc.’s product, 

Rout, label (EPA Registration No. 64898-4) (0.127 lb ai/A). Both application rates were 

considered in the revised human health risk assessment. 

• Amount of Metam-Sodium Handled Daily: Sewer Sciences Inc. reported that their 

applicators treat between 4,500 and a maximum of 10,000 feet of sewer pipe (8” 

diameter) in a day, which corresponds to between 600 and 1,333 gallons of metamsodium handled per day. Douglas Products and Packaging reported that their applicators 

treat between 2000 and 4000 linear feet of sewer pipe (8” diameter) daily, which 

corresponds to between 250 and 500 gallons of metam-sodium handled per day. The 

Agency utilized both exposure estimates in its revised human health risk assessment. 

• Exposure – Number of Days Workers Treat Sewers Each Year: Based on an analysis of 

its sales data, Douglas Products reported that workers apply metam-sodium to sewers a 

maximum of 160 days per year. Sewer Sciences reports that applicators apply their 

products approximately 220 days per year. Both exposure scenarios were considered in 

the revised human health risk assessment. 

• Exposure – Number of Hours Exposed to Metam-Sodium Each Day: Sewer Sciences Inc. 

has reported that commercial applicators work with metam-sodium 8 hours each day and, 

therefore, metam-sodium worker exposures should be estimated at 8 hours daily. The 

comments submitted by Douglas Products and Packaging reported that the time per day 

that metam-sodium exposure can occur is limited to the amount of time actually spent 

loading the chemical and the time when the applicator hose is removed from the sewer 

manhole. Most of the application time consists of the hose being unrolled into the 

manhole cover and then rolled out of the manhole cover. Therefore, there is no potential 

for exposure to metam-sodium during most of the application time. Based on the usage 

and exposure information submitted by Douglas Products and Packaging, the Agency 

believes that it is appropriate to assume two hours of exposure to metam-sodium in its 

cancer assessments, since the duration of exposure to metam-sodium is limited. 

During the public comment period, the Agency also received information from Douglas 

Products indicating that closed engineering systems are employed for all mixing and loading 

activities. As a result, EPA is requiring closed mixing loading systems for all metam-sodium 

sewer use applications to limit exposures to handlers. 

In a February 2009 letter received from a representative on behalf of the registrant, Sewer 

Sciences Inc., the company provided data identifying the sewer use of metam-sodium as a source 

of N-nitrosodiumethylamine (NDMA) in wastewater and asked the Agency to consider this 

information in its assessment of the use of metam-sodium in sewers. In the Agency’s “Revised 

Environmental Fate and Ecological Effects Risk Assessment for Metam-sodium and Metampotassium” (PC Codes 039003 and 039002; DP Barcode D293339) (see the metam-sodium 

docket at: EPA-HQ-OPP-2004-0159-0118), the Agency acknowledged NDMA, for which there 

is a National Recommended Water Quality Criteria of 0.00069 μg/L (current/potential drinking 
141

water) and 3.0 μg/L (no potential for drinking water), as a reported contaminant in metamsodium sewer use products. To further evaluate metam-sodium sewer use as a potential source 

for NDMA in wastewater, the Agency will require the registrants, in response to the productspecific data call-in (pDCI) that will accompany this RED addendum, to report to the Agency 

any concentration of NDMA in their product(s), pursuant to FIFRA Section 158.350(a)(4). 

Based on comments received during the post-RED comment period the Agency is 

providing additional characterization or the dermal risks from metam-sodium and the inhalation 

risks from both metam-sodium and MITC. Additionally, comments received from Sewer 

Sciences, Inc. identified errors that had been made in July 2008 RED which included 

noncommercial handler cancer risks, representing five days of exposure, rather than the 

commercial handler cancer risks, which were represented by 220 days of exposure and 

presenting cancer risk from dermal exposures to metam-sodium when an OV respirator is worn. 

In their comments, Sewer Sciences Inc. correctly noted that if the cancer risks are derived from 

dermal exposure, a respirator would not be an effective means of mitigating these risks. 

Rationale 

Metam Sodium Non-Cancer Occupational Risk Concerns – Acute & Short-term Inhalation 

Risks from MITC Exposure 

Because metam-sodium degrades rather quickly to MITC, short-term, intermediate-term, 

and chronic inhalation exposures to metam-sodium by workers are expected to be negligible 

when compared with MITC exposures. To assess acute and short-term inhalation risks to 

applicators, EPA utilized two studies, conducted in Australia, which measured MITC air 

concentration levels during application of a metam-sodium product to sewers. These studies 

represent the best available acute- and short-term MITC inhalation exposure data. Table 12 

below summarizes the acute and short-term MOE estimates for MITC inhalation exposure to 

handlers based on exposure levels from these studies. Estimates represent baseline conditions as 

well as the use of dermal or respiratory protection, as indicated. 

Table 12. Handler MOEs for MITC Inhalation Exposure from 

Sewer Use Application of Metam-Sodium 

Baseline MOEs PF 10 Respirator 

MOEs

Study Sample MITC 

Conc. 

(ppm) Acute 

MOE 1

ST 

MOE 2

Acute 

MOE 1

ST 

MOE 2

Operator breathing zone exposure 0.27 1 1 10 10 

At point of application 22 <1 na 9-10 na 

Two manholes downstream (approx. 300 m) 0.017 36 na 360 na 

Sheers R (1994) 

Melbourne Water - 

Sanafoam 

Vaporooter Trial, 7 

November 1994 

At point of application - 24 hours post-application 0.023 26 na 260 na 

Operator breathing zone exposure < 0.017 13 10 130 100 

Operator breathing zone exposure < 0.027 8 7 80 70 

Operator breathing zone exposure 0.057 4 3 40 30 

At point of application - 30 mins post application 2.6 <1 na3 9-10 na3

At point of application - 90 mins post application 1.3 <1 na3 9-10 na3

At point of application - 180 mins post application 6.8 <1 na3 9-10 na3

Sheers R (1995) 

Melbourne Water - 

Sanafoam 

Vaporooter Trial, 

13-14 February 

1995, ICI Australia 

Operations Pty At point of application - 270 mins post application 4.4 <1 na3

 9-10 na3
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At point of application - 360 mins post application 0.87 1 na3 10 na Ltd. 3

At point of application - 24 hours post-application < 0.010 60 na3

 600 na3

1 Acute MOEs for breathing zones samples based on NOAEL of 0.22 ppm. For other samples (less than 15 minutes) 

acute MOEs based on 0.60 ppm. Acute target MOE = 10. 

2 MOEs were not estimated for static measure measurements. Short-term target MOE = 30. 3 na = not available 

These estimates indicate that for samples taken in the breathing zone of the applicator, 

the target MITC concentrations ranged from 0.27 ppm to < 0.017 ppm, with acute MOEs ranging 

from 1 to 13 and short-term MOEs ranging from 1 to 10. While these MOEs are below both the 

target MOE of 10 for acute inhalation exposures to MITC and the target MOE of 30 for shortterm exposures to MITC, as noted previously, these estimates do not take into account the use of 

respiratory protection. Samples taken at the point of application (i.e., directly over a manhole 

where a metam-sodium application had taken place, both immediately after an application and at 

regular intervals in time after an application had taken place), were largely below an MOE of 1. 

To address the short- and intermediate-term MITC inhalation risks from MITC, in the July 2008 

metam-sodium metam-potassium RED, the Agency required that any person(s) engaged in any 

activities that are likely to involve direct contact with metam-sodium (including, but not limited 

to, mixing, loading, and/or applying metam-sodium; equipment calibration; cleaning and repair 

of application equipment; entering into treated areas; sampling cleanup spills; and rinsate 

disposal) wear at least a NIOSH-approved full-face respirator with organic vapor cartridge 

approved for MITC. 

While there is insufficient toxicological data to characterize the inhalation cancer risk of 

MITC, due to limitations in the rat and mouse MITC oral carcinogenicity studies, the Agency 

anticipates that these new respiratory requirements will adequately address this risk. However, 

the Agency is requiring additional study data (see Section V), including: (1) an inhalation 

development toxicity rat study (GLN 870.3550), (2) a two-generation inhalation reproduction 

study in rat (GLN 870.3800), and (3) carcinogenicity studies (i.e., rat and mouse) for MITC 

(GLN 870.4200). In addition, to understand the ratio of the conversion of metam-sodium to 

MITC, the Agency is adding a requirement for monitoring data in the breathing zone of the 

mixer/loader/applicator for sewer use metam-sodium applicators (GLN 875.1300) This study 

should measure dermal exposure to metam-sodium and inhalation exposure to MITC to 

determine what handlers are being exposed to and in what quantities. This MITC monitoring 

data, in addition to the data being requested to characterize the inhalation cancer risk of MITC, 

will enable the Agency to further characterize the toxicity profile of this chemical and to confirm 

whether the mitigation measures being required are adequate or if additional measures are 

warranted. These data will be required as a part of the data call-in that will accompany this RED. 

Metam-Sodium Non-Cancer Occupational Risk Concerns – Short- and Intermediate-Term 

Dermal Risks from Metam-Sodium Exposure 

The Agency revised the non-cancer, short- and intermediate-term occupational handler 

dermal exposure assessments based on the additional usage and occupational exposure 

information provided by the metam-sodium sewer use registrants. The results of the revised noncancer, short-term occupational handler dermal exposure assessments for the sewer use of 

metam-sodium indicate that the MOEs for the dermal risk to handlers with engineering controls 

(e.g., closed mixing and loading systems) were above or just below the target MOE of 100, and 
143

the MOEs for the dermal risk to handlers with full dermal PPE (i.e., chemical resistant gloves 

and double layer clothing) were above 49, even at the highest daily rates of amount of product 

handled. In the case of the intermediate-term exposures with full dermal PPE, MOEs were below 

the target MOE of 100, even with engineering controls. Revised risk estimates are given in Table 

13 below. 

Table 13: Metam-Sodium Non-cancer Dermal Sewer Handler Risk Estimates

Application Rate 

(lbs ai/gal) 

Amount Handled 

Daily (gals) 

Baseline 

MOE 

PPE-G1 

MOE 

PPEG1

,DL2

MOE 

Eng Cont 

MOE6

Short-term Margins of Exposure 3

500 5 0.73 93 130 250 0.111 

1125 5

 0.33 41 56 110 

500 5 0.64 81 110 220 0.127 

1125 5

 0.29 36 49 96 

Intermediate-term Margins of Exposure 4

500 5 0.017 2.2 3 5.9 0.111 1125 5

 0.0077 0.97 1.3 2.6 

500 5 0.015 1.9 2.6 5.1 0.127 

1125 5

 0.0068 0.85 1.2 2.3 1

 G = gloves. 

2

 DL = double layer of clothing. 

3

 Short-term margins of exposure are calculated using a NOAEL of 4.22 mg/kg/day from a developmental rat 

toxicity study. Short-term target MOE = 100. 

4

 Intermediate-term margins of exposure are calculated using a NOAEL of 0.1 mg/kg/day from a chronic dog 

toxicity study. Intermediate-term target MOE = 100. 

5 500 and 1125 gallons handled per day equals treating 4,000 and 9,000 linear sewer feet per day. 

6 Engineering controls = mixing and loading activities, but not applications.

Although not all short- and intermediate-term dermal exposure MOEs reached the target 

MOE of 100 with the required dermal protection and engineering controls, the occupational 

handler dermal exposure assessments are considered to be very conservative. Coupled with the 

Agency’s dermal PPE requirements (i.e., chemical resistant gloves and double layer clothing) 

and engineering control requirements (i.e., closed mixing and loading systems), the Agency 

believes that it is being protective of possible metam-sodium short-term and intermediate-term 

dermal risks. The occupational dermal risk assessments are based on data from the Pesticide 

Handler Exposure Database (PHED). PHED was designed to be used only to assess nonvolatile 

pesticides. In the case of metam-sodium sewer use, PHED was used because there is no data 

available to the Agency to assess exposure to metam-sodium itself. Since metam-sodium 

degrades rather quickly to MITC, the dermal short- and intermediate-term sewer risk assessment 

for metam generated by the Agency using data from PHED can be considered very conservative. 

In addition, the mixer-loader open-pour exposure information from PHED used to estimate risk 

for sewer use handlers of metam-sodium mixing, loading, and applying is not necessarily a good 

representation of the actual sewer application activities. The PHED scenario assumes that the 

handler is directly mixing and pouring the chemical into the application tank, while application 

information provided by the registrants describes a lower-exposure practice in which the 

applicator unrolls a hose into the manhole cover and then rolls the hose out of the manhole cover 

as the chemical is being applied. 
144

Another source of conservatism comes from the fact that both the short- and 

intermediate-term dermal exposure assessments assume that workers are exposed throughout an 

8-hour workday. However, the Agency believes that the amount of time workers are exposed to 

metam-sodium each day is limited to the amount of time spent loading and applying metamsodium, which the Agency has estimated at 2 hours per day, based upon information submitted 

by the registrant, Douglas Products and Packaging Company. 

To address the short- and intermediate-term dermal risks from metam-sodium, consistent 

with the mitigation required in the July 2008 metam-sodium and metam-potassium RED, the 

Agency is requiring that any person(s) engaged in any activities that are likely to involve direct 

contact with metam-sodium (including, but not limited to, mixing, loading, and/or applying 

metam-sodium; equipment calibration; cleaning and repair of application equipment; entering 

into treated areas; sampling cleanup spills; and rinsate disposal) be required to wear double-layer 

clothing and chemical-resistant gloves. 

In addition to the worker PPE requirements, the Agency will also require closed 

engineering systems for all mixing and loading of metam-sodium for sewer use. In addition, all 

systems must be capable of removing the pesticide from the shipping container and transferring 

it into mixing tanks and/or application equipment. At any disconnect point, the system must be 

equipped with a dry disconnect or dry couple shut-off device that is warranted by the 

manufacturer to minimize drippage. Finally, handlers will also be required to stop application 50 

prior to the manhole and position a clean water rinse hose to continually rinse off the application 

hose as it is extracted from the sewer pipe. All of these mitigation measures are designed to 

further protect handlers from exposures. These additional requirements are a result of 

information that the Agency received from Douglas Products and Packaging Company during 

the post-RED comment period regarding typical usage scenarios, which included such practices. 

To better evaluate the dermal exposure to mixer/loader/applicators of metam sewer use 

applications and to confirm whether the mitigation measures included in this RED are adequate 

and/or determine whether additional mitigation measures are warranted, the Agency also will be 

requiring the registrants to submit outdoor dermal exposure data (GLN 875.1100) and product 

use information (875.1700) as a part of the data call-in that will accompany this RED. 

Metam-Sodium Cancer Occupational Risk Concerns 

EPA revised its occupational handler dermal cancer assessment for handlers engaged in 

sewer applications of metam-sodium to control roots in sewer systems based on the additional 

usage and occupational exposure information provided by the metam-sodium sewer use 

registrants during the post-RED comment period. The results of the revised cancer occupational 

handler dermal exposure assessment for the sewer use of metam-sodium indicate that cancer 

risks for workers in full dermal PPE requirements (i.e., chemical resistant gloves and double 

layer clothing) and/or those using engineering control technologies (i.e., closed mixing and 

loading systems) are below the target cancer risk level of between 1x10-4 to 1x10-6 for exposed 

handlers. Revised risk estimates are given in Table 14 below. 

Table 14: Metam-Sodium Cancer Sewer Risk Estimates
145

Application 

Rate 

(lbs ai/gal) 

Amount 

Handled 

Daily 

(gals) 

Hours 

per Day 

Exposed 

Number 

of Days 

Treating 

per 

Year 

Baseline 

Cancer Risk 

PPE-G1

Cancer Risk 

PPE-G1,DL2

Cancer Risk 

Eng Cont 

Cancer Risk 

160 2.5E-04 2.0E-06 1.4E-06 7.3E-07 0.111 220 1.8E-04 1.4E-06 1.1E-06 5.3E-07 

160 2.8E-04 2.3E-06 1.7E-06 8.4E-07 0.127 

500 3

 2 

220 2.1E-04 1.6E-06 1.2E-06 6.1E-07 1

 G = gloves. 

2

 DL = double layer of clothing. 

3 500 gallons handled per day equals treating 4,000 linear sewer feet per day. 

Potential Impacts of Metam-Sodium on Nitrifying Bacteria at Downstream Water Treatment 

Facilities 

During the Phase 5 and post-RED comment periods, the Agency received comments 

from various stakeholders, including Sewer Sciences Inc. and wastewater treatment plant 

personnel, indicating that metam-sodium impacted downstream wastewater treatment plant 

operations as a result of bacterial upset. Some wastewater treatment plant personnel provided 

anecdotal information that the use of metam-sodium led to upsets in the microorganisms at their 

facilities, but specific details regarding the circumstances that led to these upsets were not 

provided. During this period, the Agency also received comments from Douglas Products and 

Packaging and other wastewater treatment plant personnel, indicating that they have observed no 

evidence that metam-sodium has led to impacts on downstream wastewater treatment plant 

operations as a result of bacterial upset. 

The Agency evaluated the available literature to determine whether there is the potential 

concern for impacts to wastewater treatment plant microorganisms following application of 

pesticide products containing metam-sodium. Based on this analysis, the Agency has determined 

if large quantaties of metam-sodium are injected, “there may be circumstances in which 

application of pesticide products containing metam-sodium to control intrusion of roots into 

sewage collection pipes and storm drains could adversely affect activated sludge microorganisms 

in wastewater treatment plants downstream of sites where such products have been applied.” For 

full details on the Agency’s analysis, please see the 4-16-09 Antimicrobial Division memo, 

“Evaluation of Potential Impacts to Wastewater Treatment Plan Microorganisms Following 

Application of Pesticide Products Containing Metam Sodium (sodium methyldithiocarbamate) as 

an Active Ingredient to Control Intrusions of Roots into Sewage Collection Pipes and Storm 

Drains, located in the metam-sodium and metam-potassium docket at EPA-HQ-OPP-2005-

0125]. 

To mitigate the Agency’s concern over potentially harmful effects of metam-sodium on 

denitrifying bacteria and the associated disruption to downstream sewage treatment facilities, the 

Agency is requiring applicators to notify downstream wastewater facilities prior to the start of 

metam-sodium applications so that they may monitor the operations of the wastewater treatment 

plant. The applicators are required to report how much product they are applying to the sewer 

system to operators of downstream water treatment plants and to inform these operators that high 
146

concentrations of these chemicals in wastewater may adversely affect the biological sewage 

breakdown process in wastewater treatment plants. 

Conclusion for Sewer Root Control Use 

EPA has evaluated the need for control of invasive roots in sewer systems and the 

available chemical, mechanical, and non-chemical alternatives to metam-sodium, concluding that 

each type of control has a place in effective sewer maintenance (see Revised Alternatives 

Assessment on Root Control Use of Metam-Sodium in Sewer Lines (DP # 358321) and Response 

to Public Comments Received dated May 8, 2009 which is available in the metam-sodium and 

metam-potassium docket at EPA-HQ-OPP-2005-0125. 

Based on the short- and intermediate-term dermal exposure risks to workers, coupled 

with the worker risks associated with MITC inhalation exposures, the Agency is requiring that 

any person(s) engaged in any activities that are likely to involve direct contact with metamsodium, including but not limited to applying metam-sodium; cleaning and repair of application 

equipment; entering into treated areas; sampling cleanup of spills; and rinsate disposal, to wear 

double-layer clothing, chemical resistant gloves, and a NIOSH-approved full-face respirator with 

organic vapor cartridge. To help mitigate risks to mixer and loaders, the Agency is requiring that 

a closed engineering systems be used for all mixing and loading activities. 

To mitigate potential effects of metam-sodium on denitrifying bacteria and the associated 

disruption to downstream sewage treatment facilities, the Agency is requiring applicators to 

notify downstream waste water facilities prior to the start of metam-sodium applications so that 

they may monitor the operations of the wastewater treatment plant. 

Based on the revised occupational risk assessments, coupled with the conservative nature 

of the short- and intermediate-term non-cancer data, the Agency finds that these measures will be 

adequate to address the risks associated with the sewer use of metam-sodium. 

c. Antimicrobial Uses 

For details on the metam-sodium, metam-potassium, and MITC human health risk 

assessments, please refer to the Human Health Risk Assessments and addenda for these 

chemicals. The following documents are recent additions: 

• EPA-HQ-OPP-2005-0125-0267, Updated Label Language for the Antimicrobial Uses of 

Methyl Isothiocyanate (MITC) (PC Code 068103) for the Reregistration Eligibility 

Decision Document. May 13, 2008. 

• EPA-HQ-OPP-2005-0125-0266, Risk Mitigation Measures, Voluntary Cancellations and 

Updated Label Language for the Antimicrobial Uses of Metam Potassium (PC Code 

039002) for the Reregistration Eligibility Decision Document. May 15, 2008. 

• EPA-HQ-OPP-2005-0125-0265, Risk Mitigation Measures, Voluntary Cancellations and 

Updated Label Language for the Antimicrobial Uses of Metam Sodium (PC Code 

039003) for the Reregistration Eligibility Decision Document. May 15, 2008. 
147

These documents are also available in the public docket EPA-HQ-OPP-2005-00125, 

located on-line in the Federal Docket Management System (FDMS) at: www.regulations.gov. 

During the post-RED comment period, the Agency received a comment from Sewer 

Sciences, Inc., which identified errors on pages 86 and 88 of the RED, wherein the Agency 

inadvertently included a combined cancer risk value of metam sodium and metam potassium. 

The risk information presented in the risk assessments for the antimicrobial uses of metam 

sodium and metam potassium correctly state the cancer risk for antimicrobial uses of both metam 

sodium and metam potassium. This error has been corrected below. 

MITC 

The results from the occupational and potential bystander assessment indicated that the 

occupational and potential bystander risks to the remedial wood treatment uses of MITC (i.e., 

treatment of utility poles, pilings, bridge timbers, and laminated wood products located outdoors) 

are expected to be negligible, based on the product formulation, product packaging, method of 

application, and required use of PPE during the application activity. 

Mitigation for Wood Pole/Piling Use: 

The Agency is requiring the following label requirements, which are also contained in the 

label table, in Section V. 

1. “Plug the pre-drilled holes immediately after applications,” 

2. “Do not treat structures/beams indoors,” and 

3. “Do not drill an application hole through seasoning checks to apply product. If the hole 

intersects a check, plug the hole and drill another. If more than two treatment holes 

intersect an internal void or rot pocket, redrill the holes farther up the pole into relatively 

solid wood.” 

Metam-sodium 

The results of the occupational assessment for most antimicrobial uses of metam-sodium 

(i.e., treatment of poles and pilings, leather processing, and treatment of sewage sludge) 

indicated that the non-cancer dermal and inhalation risks to handlers were not of concern (i.e., all 

MOEs are greater than the target of 100). The cancer risks for the rest of the metam-sodium uses 

were in the range of 1.1e-4 to 6.8e-6, where the target cancer risk level is between 1e-4 to 1e-6 

for occupationally exposed workers. 

Because of the short loading and/or application durations (i.e., minutes), handlers (i.e., 

mixers/loaders) are not expected to be exposed to the metam-sodium degradate, MITC. 

Occupational post-application and potential bystander (i.e., residents) exposure to MITC after the 

pole treatment is considered negligible. Any migration of MITC through the wooden cap into 

the ambient air conditions is considered negligible. However, the Agency has concerns for 

potential post-application inhalation exposures to MITC after metam-sodium applications in the 

leather and/or sugar processing industries and also for workers in the vicinity of sewage sludge 
148

treatments. However, no data are available to estimate the air concentrations at these types of 

processing facilities. 

The following uses have been voluntarily cancelled for metam-sodium: (1) the sugar 

beet/sugar cane use and (2) all leather and hide processing uses. One registrant has voluntarily 

cancelled the organic sludge fumigation use; however, this use is still being maintained by 

another registrant. Therefore, the antimicrobial uses of metam-sodium that remain include: (1) 

the remedial treatment of wooden poles and timbers and (2) treatment of sewage sludge and 

animal waste. 

Mitigation for Wood Pole/Piling Use: 

The Agency is requiring the following label requirements, which are included in the label 

table, in Section V. 

1. “Plug the pre-drilled holes immediately after applications,” 

2. “Do not treat structures/beams indoors,” and 

3. “Do not drill an application hole through seasoning checks to apply product. If the hole 

intersects a check, plug the hole and drill another. If more than two treatment holes 

intersect an internal void or rot pocket, re-drill the holes farther up the pole into relatively 

solid wood.” 

Mitigation for Use to Treat Sewage Sludge and Animal Waste: 

The Agency is requiring the new label language be developed, which states that the 

treated material is placed in a protected storage area for 21 days. The current label language 

reads that the treated material needs to be paced in a protected storage area for 14-21 days or 

until a phytotoxicity test is completed. This new label language is contained in the Label Table, 

in Section V. 

Metam-potassium 

The results of the occupational assessment for most antimicrobial uses of metampotassium (i.e., pulp and paper, leather, sugars, and emulsions and cutting fluids) indicated that 

the non-cancer dermal and inhalation risks to handlers were not of concern (i.e., all MOEs are 

greater than the target of 100). However, the occupational assessment results of metampotassium used in water cooling systems exceeded the Agency’s level of concern (i.e., MOEs 

were less than the target of 100) for dermal and inhalation exposures of handlers during openpouring activities. Similarly, the cancer risk for the handlers of liquid open-pour products in 

water cooling facilities was also of concern, and is 2.9e-3. The cancer risks for the rest of the 

metam-sodium and metam-potassium handlers were in the range of 1.1e-4 to 1.6e-8, where the 

target cancer risk level is between 1e-4 to 1e-6 for occupationally exposed workers. 

Because of the short loading and/or application durations (i.e., minutes), handlers (i.e., 

mixers/loaders) are not expected to be exposed to the metam-potassium degradate, MITC. 

However, the Agency has concerns for potential post-application inhalation exposures to MITC 

for workers in the vicinity of metam-potassium applications in the leather, pulp/paper, and sugar 
149

processing industries, as well as in coatings and metal working fluid manufacturing, oil-field 

operations, cooling water towers, and industrial water purification facilities because MITC is a 

highly volatile organic chemical (vapor pressure = 150 mm Hg). Furthermore, since metamsodium and metam-potassium convert to MITC in aqueous media, the Agency also has concerns 

for the potential MITC inhalation exposures for the machinist who works with metal-working 

fluids that were preserved with metam-potassium. 

While industrial workers are not expected to be exposed to MITC while mixing or 

loading paint products containing metam-potassium, bystanders in the vicinity of freshly painted 

areas and occupational/professional workers and residential (do-it-yourself) applicators could 

have potential inhalation exposure to MITC. (It is assumed that all metam-potassium used in 

paint products converts to MITC.) All of the professional painter MOEs for all time durations 

exceeded the Agency's level of concern (target MOE of 10). At the maximum application rate, 

the residential painter MOEs for the 8-hour and 28-day durations also exceed the Agency’s level 

of concern. Furthermore, at the maximum application rate, the post-application bystander MOE 

for all durations also exceeds the Agency’s level of concern. 

The technical registrants have chosen to voluntarily cancel the following uses of metampotassium: (1) the sugar beet/sugar cane use; (2) all leather uses, with the exception of the 

tanning drum leather applications; (3) all paint uses (inclusive of the preservation of protective 

colloids and emulsion resins); (4) all water-based drilling, completion, and packer fluid uses; (5) 

all petroleum secondary recovery operations uses; (6) all once-through cooling water 

applications; and (7) all cutting fluids (metalworking fluids) uses. Those antimicrobial uses of 

metam-potassium that remain include: (1) the tanning drum leather use, (2) pulp and paper, (3) 

recirculating cooling water systems, and (4) industrial water purification systems. 

Mitigation for Cooling Water Tower Use: 

Both the dermal and inhalation risk and the cancer risk to occupational workers during 

open-pour activities for the recirculating cooling water tower use are mitigated by requiring the 

use of a metering pump system for the recirculating cooling tower use. Label requirements will 

include the following, which is also contained in the label table, in Section V. 

• “This antimicrobial product may only be used in recirculating cooling water facilities.” 

• “This antimicrobial product can only be applied to recirculating cooling water systems 

via a metering pump system.” 

• Update PPE to be inclusive of long sleeves, long pants, chemical resistant gloves, and 

goggles or face shield. 

2. Endocrine Disruptor Effects 

EPA is required under the FFDCA, as amended by FQPA, to develop a screening 

program to determine whether certain substances (including all pesticide active and other 

ingredients) “may have an effect in humans that is similar to an effect produced by a naturally 

occurring estrogen, or other such endocrine effects as the Administrator may designate.” 

Following the recommendations of its Endocrine Disruptor Screening and Testing Advisory 

Committee (EDSTAC), EPA determined that there were scientific bases for including, as part of 
150

the program, androgen and thyroid hormone systems, in addition to the estrogen hormone 

system. EPA also adopted EDSTAC’s recommendation that the Program include evaluations of 

potential effects in wildlife. When the appropriate screening and/or testing protocols being 

considered under the Agency’s Endocrine Disrupter Screening Program (EDSP) have been 

developed and vetted, metam-sodium, metam-potassium, and MITC may be subjected to 

additional screening and/or testing to better characterize effects related to endocrine disruption. 

3. Endangered Species Considerations 

 The Agency has not conducted a risk assessment that supports a complete 

endangered species determination. The ecological risk assessment planned during registration 

review will allow the Agency to determine whether metam-sodium, metam-potassium and MITC 

use 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 Services (the Services), as 

appropriate. 

D. Conclusion 

 

The Agency has determined that products containing metam-sodium, metam-potassium 

and MITC are eligible for reregistration provided the risk mitigation measures outlines above are 

adopted and label amendments are made to reflect these measures. Where labeling revisions are 

warranted, specific language is set forth in the label. Table in Section V of the document. 

V. What Registrants Need to Do 

EPA recognizes that the extent of the mitigation needed for metam-sodium and metampotassium and the other soil fumigants will require continued coordination among state 

regulatory agencies, EPA, registrants, growers and other stakeholders to ensure that all 

provisions of the RED are understood, that data are developed and evaluated expeditiously, and 

that bystander and worker protection measures are implemented as soon as practicable. 

When the soil fumigant REDs were issued in July, 2008, EPA specifically requested 

comment on the mechanisms and timing of implementing the provisions of the REDs. After 

considering stakeholder comments largely focused on the challenges of implementing many new 

measures simultaneously, EPA has developed the following schedule: 

July 2008 Metam-sodium and Metam-potassium REDs issued. 

October 2008 Comment period closed. 

May 2009 EPA responds to comments, amends RED as appropriate. 

Mid 2009 EPA issues product and generic DCIs. 

September 1, 2009 Registrants must submit revised labels to EPA, reflecting phase one of 

the mitigation measures as outlined in Table 2: restricted use, GAPs, rate 

reductions, limitations on use sites, new handler protection measures, tarp 

cutting and removal restrictions, extended worker re-entry restrictions, 
151

training information for workers, and relevant portions of the FMP 

requirements. 

December, 2009 EPA reviews/approves new labeling for 2010 use season. 

During 2009-10 EPA works with registrants, states and stakeholders to develop and begin 

implementation of first responder and community outreach, applicator 

training, and compliance assistance and assurance measures. 

September 1, 2010 Registrants must submit revised labels to EPA reflecting all remaining 

mitigation measures outlined in Table 2 including: 

 applicator training, restrictions on applications near sensitive sites, buffer 

zones, buffer credits, buffer zone posting and buffer overlap prohibitions 

and exceptions, and the full FMP requirements. 

2009-2012 Registrants develop data per DCIs. 

2013- EPA begins Registration Review for metam-sodium and metam-potassium 

and other fumigants 

Labeling

Registrants must submit labeling reflecting phase one mitigation measures by September 

1, 2009. All measures will need to be reflected on labels submitted to EPA by September 1, 

2010. Because of the relatively large amounts of product shipped under a single label, e.g., 50 

gallon drums and railroad tank cars, changes to fumigant labeling can be adopted relatively 

quickly. Therefore, the Agency anticipates that labeling approved late in 2009 would begin to 

appear on products used for the 2010 fumigation season. 

The Agency has determined that, with the mitigation measures identified in this document, 

some metam-sodium, metam-potassium, and MITC uses are eligible for reregistration; however, 

additional data are required to confirm this decision. In the near future, the Agency intends to 

issue data call-in (DCI) notices requiring product-specific data and generic (technical grade) 

confirmatory data. Generally, registrants will have 90 days from receipt of a DCI to complete 

and submit response forms or request time extension and/or waiver requests with a full written 

justification. 

A. Manufacturing Use Products 

 

 1. Additional Generic Data Requirements 

The generic data base supporting the reregistration of metam-sodium, metam-potassium, 

and MITC has been reviewed, and data gaps exist. The data listed below are necessary to 

confirm the reregistration eligibility decision documented in this RED and determine whether the 

mitigation measures outlined in this RED are adequate or if additional measures are warranted. 

 The Agency is requiring the following toxicity studies. 
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OPPTS 

Guideline 

Number 

Data Requirement Study 

type 

870.6200 Neurotoxicity Screening Battery - Inhalation TOX 

870.3550 Developmental Toxicity Screening Test - 

Inhalation 

TOX 

870.3800 Reproduction and Fertility Effects - Inhalation TOX 

870.5550 Unscheduled DNA Synthesis in Mammalian 

Cells in Culture 

TOX 

870.4200 Chronic/Carcinogenicity Rats - Inhalation TOX 

870.4200 Chronic/Carcinogenicity Mice - Inhalation TOX 

870.6200 - Neurotoxicity Screening Battery

An acute neurotoxicity study in rat via the inhalation route with pathological evaluation 

of the complete respiratory tract is being requested. The Agency is currently using single day, 

acute exposures in its consideration of buffer zones following applications of metam-sodium and 

metam-potassium. The toxicology data available to inform this decision are limited to an eye 

irritation study in human subjects and an acute inhalation study. The purpose of the acute study 

was to determine the LC50, not for use in hazard identification for human health risk assessment. 

The Agency cannot evaluate the dose response relationship of irritation and systemic effects to 

the nose and lungs using these studies. This information on the respiratory tract is critical for the 

risk assessment as the relative sensitivity of eye irritation and more serious health outcomes is 

unknown. The Agency is open to discussing MITC-specific changes to the standard 

neurotoxicity screening battery to ensure that the appropriate target organs are evaluated and that 

relevant dose-response data would be generated. 

870.3550 - Developmental toxicity screening test - Inhalation 

 

This inhalation developmental toxicity study in rat is being requested to further 

characterize the toxicity profile of this compound via the inhalation route. MITC has been 

shown to travel off fields to areas where the general public lives, works, and plays. As such, it is 

appropriate to evaluate the effects of MITC on pregnant females and their fetuses. 

870.3800 - Reproduction and Fertility Effects 

Two generation reproduction study in rat via inhalation with pathological evaluation of 

the complete respiratory tract in offspring is needed. This inhalation reproductive toxicity study 

is being requested to further characterize the toxicity profile of this compound via the inhalation 

route. MITC has been shown to travel off fields to areas where the general public lives, works, 

and plays. As such, it is appropriate to evaluate the effects of MITC on reproductive 

performance and to pups directly exposed to MITC via the inhalation route. Note: the Agency 

would be open to discussing with the registrant the potential for performing the new enhanced 

one-generation reproductive study instead of the standard two-generation study. 

870.5550 - Unscheduled DNA Synthesis in Mammalian Cells in Culture 
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This study is required to complete the genetic toxicity testing battery. 

870.4200 - Chronic/Carcinogenicity Rats and Mice 

Carcinogenicity studies for MITC per se are insufficient to characterize cancer risk; 

therefore, the carcinogenic potential of MITC cannot be determined at this time. Although there 

are not expected to be exposures of six months or longer in duration in a given year, since the 

same fields are often treated every year, there is potential for exposure to occur annually for 

many years. Moreover, metaplasia of the respiratory epithelium, a lesion often associated 

cancer, was observed after only 28 days of exposure in the subchronic inhalation study in rats 

with MITC. As such EPA is requiring inhalation carcinogenicity studies with MITC in rats and 

mice. 

 

Additional data requirements for metam-sodium and metam-potassium soil uses 

OPPTS 

Guideline 

Number 

Data Requirement Study 

type 

835.8100 Field Volatility from soil ORE 

875.1100 Dermal exposure - outdoor ORE

875.1300 Inhalation exposure - outdoor ORE

Special Avian acute inhalation, MITC ECO 

850.1075 Acute Marine/Estuarine Fish, MITC ECO 

850.1025 Acute Marine/Estuarine Mollusk, MITC ECO 

850.1035 Acute Marine/Estuarine Shrimp, MITC ECO 

850.4225 Seedling Emergence – Tier II, MITC. ECO 

850.4250 Vegetative Vigor – Tier II, MITC ECO 

850.4400 Aquatic Plant Growth – Tier II, MITC (3 

remaining species) ECO 

850.3020 Honeybee Acute Contact ECO 

Special Community Outreach and Education Program Special 

Special Training for Applicators Supervising 

Fumigations Special 

Special Training Materials for Handlers Special 

Special Fumigant Buffer Zone Posting Signs Special 

Data Requirements: 

The Agency is requiring the following volatility and human exposure studies which will 

be used to confirm if bystander and worker risks are below the Agency’s level of concern. They 

will also be used to determine if additional mitigation measures are warranted: 

• GLN 835.8100 - Field volatility from soil (center pivot, spray blade, and rotary tiller) 

• GLN 875.1100 - Dermal exposure - outdoor 

• GLN875.1300 - Inhalation exposure - outdoor 

835.8100 - Field volatility from soil
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Volatility studies are required for metam-sodium and metam-potassium soil uses to 

determine flux for modeling purposes of the breakdown products of metam-sodium and metampotassium, including formaldehyde. Center pivot, spray blade, and rotary tiller application 

methods should be included. 

For center pivot applications the Agency is requiring field volatility studies for all 

application methods including high release, medium release and low release height-solid stream 

application methods. In addition, the field volatility study for low release height-solid stream 

applications should evaluate the cumulative flux from 2 adjacent applications that are occurring 

at the same time. 

875.1100 - Dermal exposure – outdoor and 875.1300 - Inhalation exposure - outdoor

These studies will be used to confirm if bystander and worker risks are below the 

Agency’s level of concern. They will also be used to determine if additional mitigation measures 

are warranted. 

Special - Avian acute inhalation, MITC 

The current estimate of avian risk is based largely on the mammal assessment. This 

study will enable an inhalation risk assessment specific to birds. This is critical, since avian 

exposure to MITC is expected to be largely via inhalation. 

850.1075 - Acute Marine/Estuarine Fish, MITC 

The aquatic risk assessment of metam-sodium and metam-potassium use is based on 

exposure to MITC. Given the use patterns evaluated, marine/estuarine species could also be 

exposed. This study will enable a risk assessment for marine/estuarine species exposure. 

850.1025 - Acute Marine/Estuarine Mollusk, MITC 

The aquatic risk assessment of metam-sodium and metam-potassium use is based on 

exposure to MITC. Given the use patterns evaluated, marine/estuarine species could also be 

exposed. This study will enable a risk assessment for marine/estuarine species exposure. It will 

also improve certainty with the endangered species risk assessment, as this test species may be 

more representative of endangered freshwater mussels than the freshwater Daphnia. 

850.1035 - Acute Marine/Estuarine Shrimp, MITC 

The aquatic risk assessment of metam-sodium and metam-potassium use is based on 

exposure to MITC. Given the use patterns evaluated, marine/estuarine species could also be 

exposed. This study will enable a risk assessment for marine/estuarine species exposure. 

850.4225 - Seedling Emergence – Tier II, MITC 
155

Metam-sodium and metam-potassium are used in part due to the phytotoxicity of MITC 

at the application site. This study will enable the assessment of risk to non-target terrestrial 

plants off site. 

850.4250 - Vegetative Vigor – Tier II, MITC 

Metam-sodium and metam-potassium are used in part due to the phytotoxicity of MITC 

at the application site. This study will enable the assessment of risk to non-target terrestrial 

plants off site. 

850.4400 - Aquatic Plant Growth – Tier II, MITC 

Only one of four tests currently available (on duckweed) is considered to be acceptable 

(Core) (MRID #45919422). The submission of data for remaining test species under this 

guideline will reduce uncertainty and improve the assessment of risk to aquatic plants. For 

example, the blue-green alga and green alga studies are 72-hour OECD studies that are only 

accepted as Tier I screening studies. 

850.3020 – Honeybee acute contact, MITC

Although there is honeybee data for metam-sodium and metam-potassium indicating that 

it is relatively non-toxic to honey bees, there is a concern that MITC could be more toxic to bees. 

Therefore, honeybee acute contact data is required for MITC. 

Special Study - Community Outreach and Education Program 

The Agency is requiring registrants to develop and implement community outreach and 

education programs, including programs for first responders, to address these needs. Community 

outreach and education programs must include the following elements, at minimum: (1) what 

soil fumigants are and how they work, (2) what buffer zones are, (3) early signs and symptoms 

of exposure, (4) appropriate steps to take to mitigate exposures, (5) what to do in case of an 

emergency, and (6) how to report an incident. EPA expects registrants’ proposals for the first 

responder programs described in Section IV will also be designed to integrate with existing local 

first-response and emergency preparedness networks. 

Special Study - Training for Applicators Supervising Fumigations

EPA has determined that training, developed and implemented by registrants to foster 

product stewardship, will help reduce potential risks associated with failure to adequately 

manage the complexities of fumigation, and failure to comply with fumigant product labeling. 

Additionally, EPA believes that providing safety information to other fumigant handlers will 

help them understand and adhere to practices that will help handlers protect themselves from 

risks of exposure. 

Registrants are required to develop and implement training programs for applicators in 

charge of soil fumigations on the proper use of and GAPs for soil fumigants. EPA is requiring 

registrants to submit proposals for these programs. The training programs must address, at 
156

minimum, the following elements: how to correctly apply the fumigant; how to protect handlers 

and bystanders; how to determine buffer zone distances; how to develop a FMP and complete the 

post fumigation application summary; how to determine when weather and other site-specific 

factors are not favorable for fumigant application; how to comply with required GAPs and 

document compliance in the FMP. The training program must be made available to applicators 

at least annually. The registrant shall provide documentation, such as a card or certificate, to 

each applicator that successfully completes the training. This documentation shall include the 

applicator’s name, address, license number, and the date of completion. 

The registrant must be able to provide to federal, state, or local enforcement personnel, 

upon request, the names, addresses, and certified applicator license numbers of persons who 

successfully completed the training program, as well as the date of completion. Applicators 

supervising fumigations must have successfully completed the program within the preceding 12 

months and must document when and where the training program was completed in the FMP. 

The registrants will be required to (1) develop a database to track which certified applicators 

have successfully completed the training and (2) make this database available to state and/or 

federal enforcement entities upon request. In addition, the applicator must provide to federal, 

state, or local enforcement personnel, upon request, documentation that verifies completion of 

the appropriate training program(s). 

Training programs must also include information on how to develop and implement 

emergency response plans to ensure that applicators are prepared in the event that a problem 

develops during or shortly after the fumigant application. EPA is also requiring registrants to 

incorporate a mechanism for evaluating the effectiveness of their training programs at conveying 

the required information to participants and for determining whether participants have 

successfully completed the training program. 

Special Study - Training Materials for Handlers

 EPA has determined that registrants must prepare and disseminate training information 

and materials for other fumigant handlers, i.e., those working under the supervision of the 

certified applicator in charge of fumigations. The training materials must address, at minimum, 

the following elements: (1) what fumigants are and how they work, (2) safe application and 

handling of soil fumigants, (3) air monitoring and respiratory protection requirements for 

handlers, (4) early signs and symptoms of exposure, (5) appropriate steps to take to mitigate 

exposures, (6) what to do in case of an emergency, and (7) how to report incidents. Registrants 

must provide this training information through channels open to the public (e.g., via a website). 

Pesticide labels will require that applicators supervising fumigations provide this training 

information to handlers under their supervision before they perform any fumigant handling task, 

or they must ensure that handlers have been provided the required information within the 

preceding 36 months. The label will also require that the training information be provided in a 

manner that the handler can understand. Applicators supervising fumigations must ensure the 

FMP includes how and when the required training information was provided to the handlers 

under their supervision. 

Special Study – Fumigant Buffer Zone Posting Signs
157

 EPA has determined that registrants must prepare and disseminate generic buffer zone 

posting signs which meet the following criteria: (1) signs must remain legible during the entire 

posting period (2) signs must meet the general standards outlined in the WPS for text size and 

legibility (see 40 CFR §170.120). The requirements for the contents of the sign are as follows 

The fumigant buffer zone sign must include 

the following: 

-- Do not walk sign 

-- "DO NOT ENTER/NO ENTRE," 

-- “Metam-Sodium or Metam-Potassium [Name of 

product] Fumigant BUFFER ZONE,” 

-- contact information for the certified applicator in 

charge of the fumigation.

Registrants must capture all of the information above, excluding the contact information 

for the certified applicator in charge of fumigating. However, registrants must provide 

appropriate space on the sign, and the sign must be made of material appropriate for applicators 

to write in this information on the buffer zone posting signs. Registrants must provide buffer 

zone posting signs at the point of sale for applicators to use. EPA is requiring registrants to 

submit proposals that must address their strategy for development and dissemination of the 

buffer zone posting signs. 

Additional data requirements for metam-sodium sewer uses

Because chemical-specific exposure data were not available to assess the sewer use of 

metam-sodium, surrogate data for mixers and loaders from the Pesticide Handlers Exposure 

Database (PHED) were used in the risk assessment. To better evaluate exposure and characterize 

risk and to confirm that the mitigation measures included in this RED are adequate and/or 

determine whether additional measures are warranted, the following data will be required for 

metam-sodium: 

• GLN 875.1100 – Dermal exposure – outdoor 

• GLN 875.1700 – Product use information 

Because metam-sodium degrades into MITC, the Agency also needs MITC monitoring 

data in the breathing zone of the mixer/loader/applicator. The following data will be 

required for MITC: 

• GLN 875.1300 – Inhalation exposure - outdoor 

Given the specialized nature of these sewer-use studies, the Agency would like to discuss 

the study design with the registrants before the studies are begun.

Additional data requirements for metam-sodium and metam-potassium antimicrobial uses
158

Because chemical-specific exposure data were not available to assess the antimicrobial 

uses of metam-potassium, surrogate data from both the Pesticide Handlers Exposure Database 

and the Chemical Manufacturers Association (CMA) were used to generate screening-level risk 

assessments. Therefore, the following data are needed to confirm the mitigation measures 

included in this RED are adequate, or if additional measures are warranted. 

• GLN 875.1200 - Dermal exposure - indoor 

• GLN 875.1400 - Inhalation exposure - indoor 

• GLN 875.1600 - Applicator exposure monitoring data reporting 

• GLN 875.1700 - Product use information 

Because metam-sodium degrades into MITC, the Agency needs MITC air concentration 

monitoring data for all enclosed facilities that utilize metam-sodium. For metam-sodium this 

only includes sewage sludge and animal waste treatment facilities as the leather use and sugar 

cane and beet uses are being voluntarily cancelled. The guideline numbers are as follows: 

• GLN 875.2500 - Inhalation exposure study 

• GLN 875.2700 - Product use information 

• GLN 875.2800 - Description of human activity 

• GLN 875.2900 - Post-application data reporting and calculations 

Residue data are needed to support the metam-potassium antimicrobial use in pulp and 

paper manufacturing. The purpose of this confirmatory study is to demonstrate that the paper 

manufacturing processes remove any residual metam-potassium and MITC. 

• GLN 860.1520 

Because metam-potassium degrades into MITC, the Agency needs MITC air 

concentration monitoring data for all enclosed facilities that utilize metam-potassium. For 

metam-potassium this includes pulp and paper facilities, recirculating cooling water facilities, 

leather processing facilities, and industrial water purification facilities. The guideline numbers 

are as follows: 

• GLN 875.2500 - Inhalation exposure study 

• GLN 875.2700 - Product use information 

• GLN 875.2800 - Description of human activity 

• GLN 875.2900 - Post-application data reporting and calculations. 

2. Labeling for Manufacturing-Use Products 

 In order to be eligible for reregistration, amend all product labels to incorporate the risk 

mitigation measures outlined in Section IV. 

B. End-Use Products 

 1. Additional Product-Specific Data Requirements 
159

 

 Section 4(g)(2)(B) of FIFRA calls for the Agency to obtain any needed product-specific 

data regarding the pesticide after a determination of eligibility has been made. The registrant 

must review previous data submissions to ensure that they meet current EPA acceptance criteria 

and, if not, commit to conduct new studies. If a registrant believes that previously submitted 

data meet current testing standards, then the study master record identification numbers (MRIDs) 

must be cited according to the instructions in the Requirement Status and Registrants Response 

Form provided for each product. As a part of the updated Confidential Statement of Formula 

(CSF) that accompanies the product-specific data call-in, the Agency is requiring registrants to 

provide information on the name and concentration of any product contaminants at all 

concentrations about the level of detection. The Agency intends to issue a separate productspecific data call-in (PDCI), outlining specific data requirements. For questions regarding the 

PDCI, contact Karen Jones from OPP/SRRD’s Product Reregistration Branch at (703) 308-8047 

or by e-mail at Jones.Karen@epa.gov. 

2. Labeling for End-Use Products 

 

In order to be eligible for reregistration, amend all product labels to incorporate the risk 

mitigation measures outlined in Section IV. The Label Table, page 160, describes how language 

on the labels should be amended.
160

Label Table

Metam-Sodium and Metam-Potassium and MITC Labeling Changes Summary Table

Summary of Labeling Changes for Metam-Sodium and Metam-Potassium Soil Uses 

Description Amended Labeling Language for Manufacturing Use Products 

Manufacturing Use Products

For all Manufacturing Use Products 

“Only for formulation into a fumigant for the following use(s): Alfalfa, Asparagus (nursery production only), Artichokes, Barley, Basil, Beet, Berries, includes all EPA Crop Group 13, Berries Group, i.e., blackberry (Rubus 

eubatus); bingleberry; black satin berry; boysenberry; Cherokee blackberry; chesterberry; Cheyenne blackberry; coryberry; darrowberry; dewberry; Dirksen thornless berry; Himalayaberry; hullberry; lavacaberry; lowberry; 

lucretiaberry; mammoth blackberry; marionberry; nectarberry; olallieberry; Oregon evergreen berry; phenomenalberry; rangeberry; ravenberry; rossberry; Shawnee blackberry; youngberry, and varieties and/or hybridthese; blueberry (Vaccinium spp.); currant (Ribes spp.); elderberry (Sambucus spp.); gooseberry (Ribes spp.); 

huckleberry (Gaylussacia spp.); loganberry (Rubus loganobaccus); raspberry-black and red (Rubus occidentalis, R

strigosus, Rubus idaeus)], Broccoli, Brussels sprouts, Cabbage, Carrot, Cauliflower, Celeriac, Chineese greens or bchoy, Cilantro, Citrus (orchard replant only), [includes all of EPA Crop Group 10, Citrus Fruits, i.e., calamondin (Citrus mitis X Citrofortunella mitis); citrus citron (Citrus medica); citrus hybrids (Citrus spp.) (includes: chironjatangelo, tangor); grapefruit (Citrus paradisi); kumquat (Fortunella spp.); lemon (Citrus jambhiri, Citrus limon); lim(Citrus aurantiifolia); mandarin (tangerine) (Citrus reticulata); orange, sour (Citrus aurantium); orange, sweet (Citrsinensis); pummelo (Citrus grandis, Citrus maxima); satsuma mandarin (Citrus unshiu)], Collard, Corn, Cover cro(i.e., crops planted between periods of regular crop production to prevent soil erosion, control weeds, and improve quality that are incorporated into the soil before the next crop is planted and may not be harvested for food or feedCrops grown solely for seed, Cucurbits [includes all of EPA Crop Group 9, Cucurbit Vegetables Group, i.e., chayo(fruit) (Sechium edule); Chinese waxgourd (Chinese preserving melon) (Benincasa hispida); citron melon (Citrullulanatus var. citroides); cucumber (Cucumis sativus); gherkin (Cucumis anguria); gourd, edible (Lagenaria spp.) [includes: hyotan, cucuzza (Luffa acutangula, L. cylindrical; includes hechima, Chinese okra)]; Momordica spp. 

(includes balsam apple, balsam pear, bitter melon, Chinese cucumber); muskmelon [hybrids and/or cultivars of Cucumis melo (includes true cantaloupe, cantaloupe, casaba, crenshaw melon, golden pershaw melon, honeydew melon, honey balls, mango melon, Persian melon, pineapple melon, Santa Claus melon, and snake melon)]; pumpk(Cucurbita spp.); squash, summer (Cucurbita pepo var. melopepo) (includes: crookneck squash, scallop squash, straightneck squash, vegetable marrow, and zucchini); squash, winter (Cucurbita maxima; C. moschata) (includes: butternut squash, calabaza, hubbard squash) and (C. mixta; C. pepo) (includes acorn squash, spaghetti squash); an

watermelon (includes hybrids and/or varieties of Citrullus lanatus)], Dill, Eggplant, Forest seedlings, 

Ginger, Grape (vineyard replant only), Kale, Kohlrabi, Leafy greens [includes all of EPA Crop Group 4, Leafy Vegetables (Except Brassica Vegetables), i.e., amaranth (leafy amaranth, Chinese spinach, tampala) (Amaranthus 

spp.); arugula (roquette) (Eruca sativa); cardoon (Cynara cardunculus); celery (Apium graveolens var. dulce); celeChinese (Apium graveolens var. secalinum); celtuce (Lactuca sativa var. angustana); chervil (Anthriscus cerefoliuchrysanthemum, edible-leaved (Chrysanthemum coronarium var. coronarium); chrysanthemum; garland 

(Chrysanthemum coronarium var. spatiosum); corn salad (Valerianella locusta); cress, garden (Lepidium sativum)
161

cress, upland (yellow rocket, winter cress) (Barbarea vulgaris); dandelion (Taraxacum officinale); dock (sorrel) (Rumex spp.); endive (escarole) (Cichorium endivia); fennel, Florence (finochio) (Foeniculum vulgare Azoricum Group); lettuce, head and leaf (Lactuca sativa); orach (Atriplex hortensis); parsley (Petroselinum crispum); purslangarden (Portulaca oleracea); purslane, winter (Montia perfoliata); radicchio (red chicory) (Cichorium intybus); rhu(Rheum rhabarbarum); spinach (Spinacia oleracea); spinach, New Zealand (Tetragonia tetragonioides, T. expansa)spinach, vine (Malabar spinach, Indian spinach) (Basella alba); and swiss chard (Beta vulgaris var. cicla)], Leek, Mint, Mustard, Nursery stock (fruit seedlings and rose bushes only), Onion, Ornamentals (floriculture only), Pome fruit (orchard replant only), [includes all of EPA Crop Group 11, Pome Fruits Group —Commodities, i.e., apple (Malus domestica); crabapple (Malus spp.); loquat (Eriobotrya japonica); mayhaw (Crataegus aestivalis, C. opaca, 

C. rufula); pear (Pyrus communis); pear, oriental (Pyrus pyrifolia); and quince (Cydonia oblonga)], Peanut, PeppePotato, Radish, Rye, Sugar beet, Soybean, Stone fruit (orchard replant only), [includes all of EPA Crop Group 12, Stone Fruits Group —Commodities, i.e., apricot (Prunus armeniaca); cherry, sweet (Prunus avium); cherry, tart 

(Prunus cerasus); nectarine (Prunus persica); peach (Prunus persica); plum (Prunus domestica, Prunus spp.); plumChickasaw (Prunus angustifolia); plum, Damson (Prunus domestica spp. insititia); plum, Japanese (Prunus salicinaplumcot (Prunus. armeniaca X P. domestica); prune (fresh) (Prunus domestica, Prunus spp.)], Strawberries, Sugar 

Sweet potato, Swiss Chard, Tobacco, Tomatoes, Tree nuts (orchard replant only), [includes all of EPA Crop Group Tree Nuts Group (i.e., almond (Prunus dulcis); beech nut (Fagus spp.); Brazil nut (Bertholletia excelsa); butternut (Juglans cinerea); cashew (Anacardium occidentale); chestnut (Castanea spp.); chinquapin (Castanea pumila); filb

(hazelnut) (Corylus spp.); hickory nut (Carya spp.); macadamia nut (bush nut) (Macadamia spp.); pecan (Carya 

illinoensis); and walnut, black and English (Persian) (Juglans spp.) as well as pistachio], Turnip, Turf (including gcourses), Wheat.” “Use in greenhouses is prohibited. Application with handheld equipment is prohibited. Application with cement grinder and shredder equipment is prohibited. Open-our applications are prohibited.” End use products with director use for soil fumigation must specifically prohibit these uses, and all references to such applications must be removed. “Metam-sodium and metam-potassium cannot be formulated into end-use products labeled for pre-plant or pretransplant uses unless the registrant makes available to certified applicators who purchase or apply the end-use proa training program approved by EPA that provides information on how to correctly apply the fumigant, including to protect themselves, other handlers, and bystanders; how to determine buffer zone distances; how to develop a Fumigant Management Plan; how to determine when weather and other site-specific factors are not favorable for fumigant application; and how to develop an emergency response plan. The training program must be made availaat least annually to the certified applicators. Certified applicators must take training at least every 36 months. The 

registrant must be able to provide, upon request, the names, addresses, and certified applicator license number of 

persons who successfully complete the training program.” “Metam-sodium and metam-potassium cannot be formulated into end-use products labeled for pre-plant or pretransplant uses unless the registrant assures warning signs suitable for posting buffer zones are available to end-usproduct users at the point of sale.” 
162

The buffer zone sign must meet the following standards: 

o Signs must remain legible during entire posting period. o The size and type of the buffer zone signs must follow the requirements in the Worker Protection 

Standard for Agricultural Pesticides for treated area posting. 

 Contents of Sign

-- "DO NOT ENTER/NO ENTRE," -- "Metam-Sodium or Metam-Potassium and [Name of product] Fumigant BUFFER ZONE,” -- space for contact information for the certified applicator in charge of the fumigation. 

One of these statements may be added to a label to allow reformulation of the product for a specific use or all additional uses supported by a formulator or user group 

“This product may be used to formulate products for specific use(s) not listed on the MP label if the formulator, usgroup, or grower has complied with U.S. EPA submission requirements regarding support of such use(s).” “This product may be used to formulate products for any additional use(s) not listed on the MP label if the formula

user group, or grower has complied with U.S. EPA submission requirements regarding support of such use(s).” 

Environmental hazards statements 

"This product is toxic to mammals, birds, aquatic invertebrates and fish. Do not discharge effluent containing this product into lakes, streams, ponds, estuaries, oceans, or other waters unless in accordance with the requirements oNational Pollution Discharge Elimination System (NPDES) permit and the permitting authority has been notified iwriting prior to discharge. Do not discharge effluent containing this product to sewer systems without previously 

notifying the local sewage treatment plant authority. For guidance contact your State Water Board or Regional Ofof the EPA." 

End Use Products Intended for Occupational Use 

Restricted Use Requirement for all products that contain soil use and sewer use 

“Restricted Use Pesticide due to acute inhalation toxicity to humans. For retail sale to and use by certified applicaor persons under their direct supervision and only for those uses covered by the certified applicator’s certification.

Certified applicator training program 

“The certified applicator supervising that application must successfully complete a metam-sodium and metampotassium training program made available by the registrant within the last 36 months. The Fumigant Managemen
163

Plan (see details elsewhere on this label) must document when and where the training program was completed.” 

Application site monitoring and Supervision of handlers 

“For all applications except water run: from the start of the application until the fumigant has stopped being delivered/dispensed into the soil, i.e., after the soil is sealed, the certified applicator must be at the fumigation site must directly supervise all persons performing handling activities. For all water-run applications (e.g., sprinkler/chemigation, wheel line, center pivot, lateral move, drip, flood, etc.), certified applicator must be at the fumigation site to start the application including set-up, calibration, and initiatiothe application. The certified applicator may leave the site but must return at least every two hours to visually inspthe equipment to ensure proper functioning and must directly supervise all WPS-trained handlers on-site until the fumigation has stopped being delivered/dispersed into the soil. WPS-trained handlers may perform the monitoring functions in place of the certified applicator but must be under the supervision of the certified applicator and able t

communicate with the certified applicator at all times during monitoring activities via cell phone or other means. Tresults of monitoring activities must be captured in the FMP. For fumigant handling activities that take place after the fumigant has been delivered/dispensed into the soil until tentry restricted period expires, the certified applicator does not have to be on-site, but must have communicated in writing to the site owner/operator and handlers the information necessary to comply with the label and procedures 

described in the FMP (e.g., emergency response plans and procedures). IMPORTANT: this requirement does not override the requirements in the Worker Protection Standard for AgricuPesticides for information exchange between owners/operators of agricultural establishments and commercial pestapplicators. The certified applicator must provide fumigant safe handling information to each handler involved in the applicati

confirm that each handler participating in the application has received fumigant safe handling information in the p

12 months.” 
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Fumigation handlers “The following activities are prohibited from being performed in the fumigant application block or surrounding bu

zone during the buffer zone period by anyone other than persons who have been appropriately trained and equippehandlers in accordance with the requirements in the Worker Protection Standard (40 CFR Part 170), from the start the application until the entry-restricted period ends. Those activities include those persons: 

• Participating in the application as supervisors, loaders, drivers, tractor co-pilots, shovelers, cross ditchers

as other direct application participants (the application starts when the fumigant is first introduced into th

and ends after the fumigant has stopped being delivered/dispensed to the soil); 

• Using devices to take air samples to monitor fumigant air concentrations; • Persons cleaning up fumigant spills (this does not include emergency personnel not associated with the 

fumigation application); 

• Handling or disposing of fumigant containers; • Cleaning, handling, adjusting, or repairing the parts of fumigation equipment that may contain fumigant 

residues; 

• Installing, repairing, or operating irrigation equipment in the fumigant application block or surrounding b

zone during the buffer zone period; 

• Entering the application site or surrounding buffer zone during the buffer zone period to perform scouting

crop advising, or monitoring tasks; 

• Installing, perforating (cutting, punching, slicing, poking), removing, repairing, or monitoring tarps: 

o until 14 days after application is complete if tarps are not perforated and removed during those 1

days, or 

o until tarp removal is complete if tarps are both perforated and removed less than 14 days after 

application; or 

o until 48 hours after tarps perforation is complete if they will not be removed within 14 days after 

application. 

NOTE: see Tarp Perforation and Removal section on this labeling for requirements about when tarps are 

allowed to be perforated. 

• In addition, to the above, persons outside the perimeter of the buffer zone who visually monitor applicatio

equipment to ensure proper functioning and monitor fumigant air concentrations must also be trained and equipped as handlers in accordance with the requirements in the WPS (40 CFR Part 170).” 

Exclusion of nonhandlers from application block and buffer zone 

“The certified applicator supervising the application and the owner/operator of the establishment where the fumiga

is taking place must make sure that all persons who are not trained and PPE-equipped and who are not performing of the handling tasks defined in this labeling are: 

• excluded from application block during the entry restricted period, and • excluded from the buffer zone during the buffer zone period.” 

Providing, cleaning, and maintaining PPE 

“The employer of any fumigant handler (as stated in this label) must make sure that all handlers are provided and correctly wear the required PPE. The PPE must be cleaned and maintained as required by the Worker Protection Standard for Agricultural Pesticides.” 
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Respirator availability “The fumigation handler employer must confirm and document in the FMP that an air purifying respirator and 

appropriate cartridges of the type specified in the PPE section of this labeling are immediately available for each 

handler who will wear one. At least one handler must have the appropriate respirator and cartridges available and they must be fit-tested, train

and medically examined.” 

PPE requirements established by the REDfor all soil fumigants1

“Personal Protective Equipment (PPE): Some materials that are chemical-resistant to this product are [registrant inserts correct chemical-resistant materia

For more options, follow the instructions for category [registrant inserts A,B,C,D,E,F,G,or H] on an EPA chemicaresistance category selection chart. Handlers applying via weed sprayer while irrigation sprinklers are running or handlers who may be exposed to liquspray while repairing a malfunctioning chemigation system or shutting off equipment must wear: 

• chemical-resistant coveralls over long-sleeve shirt and long pants, • chemical-resistant gloves, • chemical-resistant footwear plus socks, • chemical-resistant headgear, • protective eyewear, and • respirator of the type specified in the respiratory protection section in the PPE requirements on this label. 

Handlers wearing chemical-resistant attire are limited to 15 minutes of exposure in any 30 minute period and, as required by the Worker Protection Standard for Agricultural Pesticides, employers of these handlers must take any necessary steps to avoid heat illness. Except as required above, handlers transferring or loading liquid formulations, handlers operating motorized grounequipment with open cabs, handlers repairing or inactivating irrigation or chemigation equipment during applicatioand handlers cleaning up spills or equipment, must wear:-- coveralls over long-sleeve shirt and long pants, -- chemical resistant gloves, -- chemical resistant footwear plus socks, -- chemical-resistant apron if transferring or loading the fumigant or cleaning up spills or equipment, -- protective eyewear, and -- respirator of the type specified in the PPE requirements for respiratory protection section in the PPE requirementhis label if triggered. All other handlers (except for fumigant handlers who set up and calibrate chemigation and irrigation equipment an
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start the application from inside the buffer zone) as stated in this labeling must wear: -- long-sleeve shirt and long pants, -- shoes plus socks, and -- respirator of the type specified in the eye and respiratory protection section in the PPE requirements on this labetriggered. All fumigant handlers who set-up and calibrate chemigation and irrigation equipment and start the application from inside the buffer zone must wear: -- long-sleeve shirt and long pants, -- shoes plus socks, -- protective eyewear, and -- respirator of the type specified in the respiratory protection section in the PPE requirements on this label if triggered.” 

PPE requirements established by the REDfor all soil fumigants –respiratory protection section. 

“Personal Protective Equipment (PPE) for respiratory protection When respiratory protection is required, in lieu of protective eyewear, handlers must wear: > at least a NIOSH-approved full-face, or helmet/hood style respirator with either 

• an organic-vapor-removing cartridge with a prefilter approved for pesticides (MSHA/NIOSH approval 

number prefix TC-23C), or 

• a respirator with a canister approved for pesticides (MSHA/NIOSH approval number prefix TC-14G).” 

For all soil fumigants - respiratory protection and stop work triggers 

“Respiratory Protection and Stop Work Triggers: The following procedures must be followed to determine whethrespiratory protection is required or if operations must cease for any person performing a fumigant handling task a

defined in this labeling. 

• If at any time any handler experiences sensory irritation (tearing, burning of the eyes or nose) then either: 

o An air-purifying respirator must be worn by all handlers who remain in the application block and 

surrounding buffer zone, or 

o Operations must cease and handlers not wearing respiratory protection must leave the applicatio

block and surrounding buffer zone. 

• Handlers can remove respirators or resume operations if two consecutive breathing-zone samples taken a

handling site at least 15 minutes apart show that levels of MITC have decreased to less than 600 ppb, provided that handlers do not experience sensory irritation. Samples must be taken where the irritation is experienced. 

• When using monitoring devices to monitor air concentration levels, a direct reading detection device, suc

a Draeger or Sensidyne device must be used. The devices must have a sensitivity of at least 600 ppb for 

MITC. 

• When respirators are worn, then air monitoring samples must be collected at least every 2 hours in the 

breathing zone of a handler performing a representative handling task. 

• If at any time: (1) a handler experiences any sensory irritation when wearing a respirator, or (2) an air sam
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is greater than or equal to 6,000 ppb, then all handler activities must cease and handlers must be removed from the application block and surrounding buffer zone. If operations cease the emergency plan detailed the FMP must be implemented. 

• Handlers can resume work activities without respiratory protection, if two consecutive breathing zone 

samples taken at the handling site at least 15 minutes apart show levels of MITC have decreased to less th600 ppb, provided that handlers do not experience sensory irritation. During the collection of air samples air-purifying respirator must be worn by the handler taking the air samples. Samples must be taken wherthe irritation is experienced. 

• Work activities can resume if the following conditions exist provided that the appropriate respiratory 

protection is worn: 

o Two consecutive breathing zone samples for MITC taken at the handling site at least 15 minutes 

apart must be less than 6,000 ppb, 

o Handlers do not experience sensory irritation while wearing the air-purifying respirator, and o Cartridges have been changed. o During the collection of air samples an air-purifying respirator must be worn by the handler taki

the air samples. Samples must be taken where the irritation is first experienced.” 

User safety requirements “Follow manufacturer's instructions for cleaning/maintaining PPE. If no such instructions for washables exist, use 

detergent and hot water. Keep and wash PPE separately from other laundry.” “Discard clothing and other absorbent materials that have been drenched or heavily contaminated with this produc

concentrate. Do not reuse them.” 

PPE requirements established by the RED for all formulations 

“Respirator fit testing, medical qualification, and training. Employers must ensure that any handler that uses a respirator is: 

• Fit-tested and fit-checked using a program that conforms to OSHA’s requirements (see 29CFR Part 1910• Trained using a program that confirms to OSHA’s requirements (see 29 CFR Part 1910.134) • Examined by a qualified medical practitioner to ensure physical ability to safely wear the style of respirat

be worn. A qualified medical practitioner is a physician or other licensed health care professional who will evaluthe ability of a worker to wear a respirator. The initial evaluation consists of a questionnaire that asks about medicconditions (such as a heart condition) that would be problematic for respirator use. If concerns are identified, then additional evaluations, such as a physical exam, might be necessary. The initial evaluation must be done before 

respirator use begins. Handlers must be reexamined by a qualified medical practitioner at least annually or if their health statue or respirator style or use-conditions change.” 

Application requirements when tarps are used: Tarp Perforation and/or Removal 

 “Tarp Perforation and/or Removal IMPORTANT: Persons perforating, repairing, removing, and/or monitoring tarps are defined, within certain time limitations, as fumigant handlers (see definition of fumigant handlers in this labeling) and must be provided the PP
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and other protections for handlers as required on this labeling and in the Worker Protection Standard for Agricultu

Pesticides. 

• Tarps must not be perforated until a minimum of 5 days (120 hours) have elapsed after the fumigant injec

into the soil is complete (e.g., after injection of the fumigant product and tarps have been laid or after drip lines have been purged and tarps have been laid), unless a weather condition exists which necessitates the need for early perforation or removal See Early Tarp Removal for Broadcast Applications Only and Early Tarp Perforation for Flood Prevention Activities sections. 

• If tarps will be removed before planting, tarp removal must not begin until at least 2 hours after tarp 

perforation is complete. 

• If tarps will not be removed before planting, planting or transplanting must not begin until at least 48 hou

after the tarp perforation is complete. 

• If tarps are left intact for a minimum of 14 days after fumigant injection into the soil is complete, planting 

transplanting may take place while the tarps are being perforated. 

• Each tarp panel used for broadcast fumigation must be perforated. • Tarps used for fumigations may be perforated manually ONLY for the following situations: 

o At the beginning of each row when a coulter blade (or other device which performs similarly) is 

on a motorized vehicle such as an ATV. 

o In fields that are 1 acre or less. o During flood prevention activities. 

• In all other instances tarps must be perforated (cut, punched, poked, or sliced) only by mechanical metho• Tarp perforation for broadcast fumigations must be completed before noon. • For broadcast fumigations tarps must not be perforated if rainfall is expected within 12 hours. 

• Early Tarp Removal for Broadcast Applications Only: 

o Tarps may be removed before the required 5 days (120 hours) if adverse weather conditions hav

compromised the integrity of the tarp, provided that the compromised tarp poses a safety hazard

Adverse weather includes high wind, hail, or storms that blow tarps off the field and create a haze.g., tarps blowing into power lines and onto roads. A compromised tarp is a tarp that due to an 

adverse weather condition is no longer performing its intended function and is creating a hazard

o If tarps are removed before the required 5 days have elapsed due to adverse weather, the events 

be documented in the post fumigation summary section of the FMP. 

• Early Tarp Perforation for Flood Prevention Activities 

o Tarp perforation is allowed before the 5 days (120 hours) have elapsed if rain necessitates field 

drainage. 

o Tarps must be immediately retucked and packed after soil removal.” 

Agriculture Use Requirements box 

Agricultural Use Requirements After the standard paragraphs for the Agricultural Use Requirements box, substitute the following text for the stanrestricted-entry interval and double notification requirements: 
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“For entry restricted period and notification requirements, see the Entry Restricted Period section of this labeling.”

Entry restricted period “Entry Restricted Period: Entry (including early entry that would otherwise be permitted under the WPS) by any 

person – other than a correctly trained and PPE-equipped handler who is performing a handling task listed on this labeling – is PROHIBITED from the start of the application until: 

• 5 days (120 hours) after the application is complete for untarped applications, or

• 5 days (120 hours) after application is complete if tarps are not perforated and removed for at least 14 day

following application, or 

• 48 hours after tarps perforation is complete if they will not be removed for at least 14 days following 

application, or 

• until tarp removal is completed if tarps are both perforated and removed less than 14 days after applicatio

NOTE: see Tarp Perforation and Removal section on this labeling for requirements about when tarps are allowed be perforated.” 

Notification requirement “Notification: Notify workers of the application by warning them orally and by posting fumigant treated area signs

The signs must bear the skull and crossbones symbol and state: -- " DANGER/PELIGRO," -- "Area under fumigation, DO NOT ENTER/NO ENTRE," -- "[Name of fumigant] Fumigant BUFFER ZONE," 

-- the date and time of fumigation, -- the date and time entry prohibition period is lifted, -- brand name of this product, and -- name, address, and telephone number of the certified applicator in charge of the fumigation. Post the fumigant warning sign instead of the WPS sign for this application but follow all WPS requirements pertaining to location, legibility, size, and timing of posting and removal. Post the fumigant warning signs at all entrances to the application block ( i.e., the field or portion of a field treated a fumigant in any 24-hour period).” 

Mandatory Good Agricultural Practices for all soil fumigation NOTE: In the Label Table, all GAPs are separated by the various application methods. 

“Mandatory Good Agricultural Practices (GAPs): The following GAPs must be followed during all fumigant applications. All measurements and other documentatplanned to ensure that the mandatory GAPs are achieved must be recorded in the FMP and/or the post application summary report. 

Wind Speed • Wind speed at the application site must be a minimum of 2 mph at the start of the application or forecaste
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reach at least 5 mph during the application. 

Weather conditions • Prior to fumigation the weather forecast for the day of the application and the 48-hour period following th

fumigation must be checked to determine if unfavorable weather conditions exist or are predicted (see Identifying Unfavorable Weather Conditions section) and whether fumigation should proceed. 

• Do not apply if a shallow, compressed (low-level) temperature inversion is forecast to persist for more th

18 consecutive hours for the 48-hour period after the start of application, or if there is an air-stagnation 

advisory in effect for the area in which the fumigation is planned. 

• Detailed local forecasts for weather conditions, wind speed, and air stagnation advisories may be obtained 

line at: http://www.nws.noaa.gov. For further guidance, contact your local National Weather Service 

Forecasting Office. 

Identifying Unfavorable Weather Conditions • Unfavorable weather conditions block upward movement of air, which results in trapping fumigant vapor

near the ground. The resulting air mass can move off-site in unpredictable directions and cause injury to humans, animals or property. These conditions typically exist prior to sunset and continue past sunrise anpersist as late as noontime. Unfavorable conditions are common on nights with limited cloud cover and lto no wind and their presence can be indicated by ground fog or smog and can also be identified by smokfrom a ground source that flattens out below a ceiling layer and moves laterally in a concentrated cloud.

Soil Conditions, Injection Depth and Soil Sealing 

• Soil must be in good tilth and free of large clods at the surface. If subsurface soil compaction layers (hardpan

are present within the intended fumigation treatment zone, a deep tillage to fracture these layers must occur prto the soil fumigant application. 

• Field residue and stubble must be worked into the soil with little or no crop residue present on the soil surface

Crop residue that is present must not interfere with the soil seal. Removing the crop residue prior to fumigatioimportant to limit the natural “chimneys” that will occur in the soil when crop residue is present. These “chimneys” allow the soil fumigants to move through the soil quickly and escape into the atmosphere. This mcreate potentially harmful conditions for workers and bystanders and will limit the efficacy of the fumigant. However, crop residue on the field serves to prevent soil erosion from both wind and water and is an importanconsideration. To accommodate erosion control, fumigant efficacy, and human health protection, clear fields crop residue as close to the timing of the fumigation as possible to limit the length of time that the soil would exposed to potentially erosive weather conditions. 
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• For shank injection applications: The injection point for bedded and broadcast shank injection applications sha

a minimum of 3 inches from the post-application soil surface. Chisel traces must be eliminated following an application and the soil surface must be compacted immediately with a culti-packer, ring roller, coil packer, socrumbler basket, bed-shaper, or other similar equipment. 

• For spray blade and rotary tiller applications: Spray or drip the product mixture on the soil immediately ahead 

the bed-shaping equipment or tiller. The soil surface must be compacted immediately after application using culti-packer, ring roller, soil-crumbler basket, bed-shaper, or other similar equipment. 

Soil temperature 

• For all ground-rig applications, the maximum soil temperature measured throughout the treatment area at a thr

inch soil depth must be between 40-90 degrees F. Soil moisture 

• Soil moisture, at the start of an application, must be at 60-80% field capacity two to six inches below the soil 

surface. 

• To achieve soil moisture at 60-80% field capacity, water treatments before or during the application, or tillage 

before or during the application may be necessary. 

• To conserve soil moisture, pretreatment water or tillage should be done as close to the time of application as 

possible. 

• The soil shall contain at the time of application enough moisture two to six inches below the surface to meet th

Feel Method test as appropriate for the soil texture. 

coarse textured soils (fine sand and loamy fine sand) there must be enough moisture (50 to 75 percent 

available soil water moisture) to form a weak ball with loose and clustered sand grains on fingers, darkencolor, moderate water staining on fingers, will not ribbon. moderately coarse textured soils (sandy loam and fine sandy loam) there must be enough moisture (50 to percent available soil water moisture) to form a ball with defined finger marks, very light soil/water stainon fingers, darkened color will not stick. medium textured soils (sandy clay loam, loam, and silt loam) there must be enough moisture (50 to 75 percent available soil water moisture) to form a ball, very light staining on fingers, darkened color, pliabl
172

and forms a weak ribbon between the thumb and forefinger. 

fine textured soils (clay, clay loam, and silty clay loam) there must be enough moisture (50 to 75 percent available soil water moisture) to form a smooth ball with defined finger marks, light soil/water staining ofingers, ribbons between thumb and forefinger. 

 For fields with more than one soil texture, soil moisture content in the lightest textured (most sandy) ar

must comply with this soil moisture requirement. Whenever possible, the field should be divided into areas of simsoil texture and the soil moisture of each area should be adjusted as needed. Coarser textured soils can be fumigatunder conditions of higher soil moisture than finer textured soils; however, if the soil moisture is too high, fumiganmovement will be retarded and effectiveness of the treatment will be reduced. Previous and/or local experience wthe soil to be treated or the crop to be planted can often serve as a guide to conditions that will be acceptable. If th

is uncertainty in determining the soil moisture content of the area to be treated, a local extension service or soil conservation service specialist or pest control advisor (agriculture consultant) should be consulted for assistance. Prevention of Spillage 

• Do not apply or allow fumigant to drain onto the soil surface. Application and Equipment Considerations • Injectors must be placed below the soil surface before product flow begins. • Clear lines before lifting injectors from the soil. • Each injection line must have a check valve located as close as possible to the final injection point. • Use only tanks, hoses and fittings approved for metam.

• Dry connect fittings (closed transfer system) must be installed on all tanks and transfer hoses. 

• All systems must be equipped with an individual tank monitoring system to detect flow problems in each 

individual tank.

• Each nozzle must be equipped with a flow monitor, e.g. mechanical, electronic, or Red-ball type monitor

• Prior to applications, the applicator must ensure that: 

• Application equipment is in good working order, 
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• All tanks, hoses, fittings, valves and connections are tightened, sealed and not leaking, • Tank monitoring equipment, flow monitoring equipment and check valves are functioning properly, • There is no damage to hoses or piping, • Sight gauges and pressure gauges are working, • Nozzles and metering devices are of correct size and are sealed and unobstructed, 

• All shields are in place. 

Tarps 

• When tarps are used in tractor applications, the tarps must be installed immediately after application. • Only approved tarps identified in this document, in the section titled “Buffer Zone Reduction Credits”, ma

used for credits towards reducing the buffer. 

• A written tarp plan must be developed and included in the FMP that includes: 

o Schedule and procedures for checking tarpaulins for damage, tears, and other problems, o Plans for determining when and how repairs to tarp will be made, and by whom, o Minimum time following injection that tarp will be repaired, o Minimum size of damage that will be repaired, o Other factors used to determine when tarp repair will be conducted, o Schedule, equipment and methods used to cut tarp, 

o Aeration plans and procedures following cutting and /or slitting prior to tarp removal or planting, and o Schedule, equipment, and procedures for tarp removal. 

GAPS for Sprinkler and Chemigation Applications 

Wind Speed 

• For mid-release, high-release and end-gun sprinkler or chemigation applications as defined by U.S. EPA, 

speed at the application site must be a minimum of 2 mph at the start of the application or forecasted to re

5 mph during the application and the maximum wind speed is 8 mph. 

• For low release height-solid stream sprinkler or chemigation applications as defined by U.S. EPA, wind sp

at the application site must be a minimum of 2 mph at the start of the application or forecasted to reach 5 during the application and the maximum wind speed is 25 mph. 

Wind Speed 
174

• Wind speed at the application site must be a minimum of 2 mph at the start of the application or forecasted to 

reach at least 5 mph during the application. Weather conditions 

• Prior to fumigation the weather forecast for the day of the application and the 48-hour period following the 

fumigation must be checked to determine if unfavorable weather conditions exist or are predicted and whether 

fumigation should proceed. 

• Do not apply if a shallow, compressed (low-level) temperature inversion is forecast to persist for more than 18 

consecutive hours for the 48-hour period after the start of application, or if there is an air-stagnation advisory effect for the area in which the fumigation is planned. 

• Detailed local forecasts for weather conditions, wind speed, and air stagnation advisories may be obtained on-

at: http://www.nws.noaa.gov. For further guidance, contact your local National Weather Service Forecasting 

Office. Identifying Unfavorable Weather Conditions 

• Unfavorable weather conditions block upward movement of air, which results in trapping fumigant vapors ne

the ground. The resulting air mass can move off-site in unpredictable directions and cause injury to humans, animals or property. These conditions typically exist prior to sunset and continue past sunrise and persist as lnoontime. Unfavorable conditions are common on nights with limited cloud cover and light to no wind and thpresence can be indicated by ground fog or smog and can also be identified by smoke from a ground source thflattens out below a ceiling layer and moves laterally in a concentrated cloud. Soil Conditions 

• Soil must be in good tilth and free of large clods at the surface. If subsurface soil compaction layers 

(hardpans) are present within the intended fumigation treatment zone, a deep tillage to fracture these layemust occur prior to the soil fumigant application. 

• Field residue and stubble must be worked into the soil with little or no crop residue present on the soil sur

Crop residue that is present must not interfere with the soil seal. Removing the crop residue prior to fumigation is important to limit the natural “chimneys” that will occur in the soil when crop residue is present. These “chimneys” allow the soil fumigants to move through the soil quickly and escape into the atmosphere. This may create potentially harmful conditions for workers and bystanders and will limit thefficacy of the fumigant. However, crop residue on the field serves to prevent soil erosion from both win

and water and is an important consideration. To accommodate erosion control, fumigant efficacy, and huhealth protection, clear fields of crop residue as close to the timing of the fumigation as possible to limit tlength of time that the soil would be exposed to potentially erosive weather conditions. 
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Air Temperature 

• The maximum air temperature is 90 degrees F. 

Soil temperature 

• The maximum soil temperature, measured at a three-inch soil depth, is 90 degrees F. 

Soil Moisture 

• Apply sufficient water before or during the application to ensure soil moisture at 60-80% field capacity at 

minimum of two to six inches below the soil surface at the start of the application. 

Flushing Irrigation Lines 

• Do not allow fumigant to remain in the irrigation system after the application is complete. After applicat

of the fumigant, flush the injection and irrigation system with untreated water. The flush time must be adequate to purge the fumigant from the injection and irrigation system, but should be less than the amouthat could over-saturate the beds. If common lines are used for both the fumigant application and a water treatment/seal (if applied), these lines must be adequately flushed before starting the water treatment/seal

Set-up, Repair and Maintenance of Equipment 

• Anti-siphon and back-flow prevention devices must be installed and in working order. • Storage tanks must be inspected, in good condition, and not past their life expectancy to ensure product d

not spill or leak. 

• Storage tanks must have proper pesticide labels on them. • Install a shut-off valve on the tank outlet to secure the bulk storage tank when not in use. - Use only tanks constructed with materials approved for handling metam-sodium and metam-potassiu

- Inter-connect the pump power supply and injection pump so that, if the center pivot or linear move st

the injection pump shuts off. 

GAPs for Drip Application 

Wind Speed 

• Wind speed at the application site must be a minimum of 2 mph at the start of the application or forecasted to 
176

reach at least 5 mph during the application. Weather conditions 

• Prior to fumigation the weather forecast for the day of the application and the 48-hour period following the 

fumigation must be checked to determine if unfavorable weather conditions exist or are predicted and whether 

fumigation should proceed. 

• Do not apply if a shallow, compressed (low-level) temperature inversion is forecast to persist for more than 18 

consecutive hours for the 48-hour period after the start of application, or if there is an air-stagnation advisory effect for the area in which the fumigation is planned. 

• Detailed local forecasts for weather conditions, wind speed, and air stagnation advisories may be obtained on-

at: http://www.nws.noaa.gov. For further guidance, contact your local National Weather Service Forecasting 

Office. Identifying Unfavorable Weather Conditions 

• Unfavorable weather conditions block upward movement of air, which results in trapping fumigant vapors ne

the ground. The resulting air mass can move off-site in unpredictable directions and cause injury to humans, animals or property. These conditions typically exist prior to sunset and continue past sunrise and persist as lnoontime. Unfavorable conditions are common on nights with limited cloud cover and light to no wind and thpresence can be indicated by ground fog or smog and can also be identified by smoke from a ground source thflattens out below a ceiling layer and moves laterally in a concentrated cloud. Soil Conditions 

• Soil must be in good tilth and free of large clods at the surface. If subsurface soil compaction layers 

(hardpans) are present within the intended fumigation treatment zone, a deep tillage to fracture these layermust occur prior to the soil fumigant application. 

• Field residue and stubble must be worked into the soil with little or no crop residue present on the soil sur

Crop residue that is present must not interfere with the soil seal. Removing the crop residue prior to fumigation is important to limit the natural “chimneys” that will occur in the soil when crop residue is preThese “chimneys” allow the soil fumigants to move through the soil quickly and escape into the atmospheThis may create potentially harmful conditions for workers and bystanders and will limit the efficacy of thfumigant. However, crop residue on the field serves to prevent soil erosion from both wind and water and an important consideration. To accommodate erosion control, fumigant efficacy, and human health protection, clear fields of crop residue as close to the timing of the fumigation as possible to limit the lengtime that the soil would be exposed to potentially erosive weather conditions. 

Soil Temperature 
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• The maximum soil temperature is 90 degrees F, measured at three inches in depth. 

Set-up, Repair and Maintenance of Equipment 

• Properly label metam-sodium storage tanks. • Install a shut-off valve to secure the bulk storage tank when not in use. • Use only tanks constructed with materials approved for handling metam products. • The drip irrigation system (main lines, headers, drip tape) must be thoroughly checked for leaks before th

start of the application. An adequate run-time and pressure are needed to detect leaks. Look for puddling 

along major pipes (holes on pipes or leaky joints), at the top and ends of rows (leaky connections, open drtape), in the furrows and on the bed surface (damaged drip tape, malfunctioning emitters). 

• To inject fumigant, use a metering system, effectively designed and constructed of materials that are 

compatible with the fumigant and capable of being fitted with system interlocking controls. 

• The system must contain a functional back-flow/check valve and low-pressure drain appropriately located 

the irrigation pipeline to prevent water source contamination and backflow. 

• The fumigant injection system must contain a functional, automatic, quick-closing check valve to prevent 

flow of fumigant back toward the fumigant container. 

• The fumigant injection system must contain a functional, normally closed valve located on the intake side 

the injection point and connected to the system interlock to prevent fumigant from being withdrawn from 

supply tank when the irrigation system is either automatically or manually shut down. 

• The system must contain functional interlocking controls to automatically shut off the fumigant injection 

the irrigation water flow stops or decreases to the point where fumigant distribution is adversely affected. 

Tarps 

• When tarps are used in drip irrigation the tarps must be installed immediately after application. • Only tarps mentioned previously in this document (in the subsection titled “Buffer Zone Reduction Credit

may be used for credits towards reducing the buffer. 
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• A written tarp plan must be developed and included in the FMP that that includes: 

o Schedule and procedures for checking tarpaulins for damage, tears, and other problems, o Plans for determining when and how repairs to tarp will be made, and by whom, o Minimum time following injection that tarp will be repaired, o Minimum size of damage that will be repaired, o Other factors used to determine when tarp repair will be conducted, o Schedule, equipment and methods used to cut tarp, o Aeration plans and procedures following cutting and /or slitting prior to tarp removal or planting, and 

o Schedule, equipment, and procedures for tarp removal. 

Flushing Drip Irrigation Lines 

• After application of the fumigant, flush the injection and irrigation system with untreated water. Do not a

fumigant to remain in the irrigation system after the application is complete. The total volume of water mbe adequate to completely remove the fumigant from the irrigation system. If common lines are used for the fumigant application and a water treatment/seal (if applied), these lines must be adequately flushed bestarting the water treatment/seal.” 

Site-Specific Fumigation Management Plans for all metam-sodium and metam-potassium enduse products containing directions for use for soil fumigation 

“Site-Specific Fumigation Management Plan (FMP): Prior to the start of fumigation, the certified applicator supervising the application must verify that a site-specific fumigation management plan (FMP) exists for each application block. Agricultural operations fumigating multiple application blocks as part of a larger fumigation maformat their FMP in a manner whereby all of the information that is common to all the application blocks is captur

once, and any information unique to a particular application block or blocks is captured in subsequent, separate sections. The FMP may be prepared by the certified applicator, the site owner/operator, registrant, or other party. The certifapplicator must verify in writing the site-specific FMPs reflects current site conditions before the start of fumigatioEach site specific FMP must contain the following elements:  Applicator information (name, phone number, license number, employer name, employer address, date of 

completing registrant metam sodium/potassium training program) 

 General site information 

3⁄4 Application block location, address, or global positioning system (GPS) coordinates 

3⁄4 Name, address, and, phone number of owner/operator of the application block 3⁄4 Map, aerial photo, or detailed sketch showing field location, dimensions, buffer zones, property lines, roa

rights-of-ways, walkways/sidewalks/paths, bus stops, water bodies, wells, state licensed daycare facilities

nearby application blocks, surrounding structures (occupied and non-occupied), locations of posted signs buffers, and sites requiring 1⁄4 or 1⁄8 mile buffer zones (e.g., schools, state licensed day care centers, nursinhomes, assisted living facilities, hospitals, in-patient clinics and prisons) with distances from the applicatisite labeled 
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 General application information (target application date/window, brand name of fumigant, EPA registration 

number) 

 Tarp Information and procedures for repair, perforation and removal (if tarp is used) 

3⁄4 Brand name, lot number, thickness 3⁄4 Name and phone number of person responsible for repairing tarps 

3⁄4 Schedule for checking tarps for damage, tears, and other problems 3⁄4 Maximum time following notification of damage that the person(s) responsible for tarp repair will respon

3⁄4 Minimum time following application that tarp will be repaired 3⁄4 Minimum size of damage that will be repaired 3⁄4 Other factors used to determine when tarp repair will be conducted 3⁄4 Name and phone number of person responsible for cutting and/or removing tarps (if other than certified 

applicator) 

3⁄4 Equipment/methods used to cut tarps 3⁄4 Schedule and target dates for cutting tarps 3⁄4 Schedule and target dates for removing tarps 

 Soil conditions (description of soil texture in application block, method used to determine soil moisture) 

 Weather conditions (summary of forecasted conditions for the day of the application and the 48-hour period 

following the fumigant application) 

3⁄4 Wind speed 3⁄4 Inversion conditions (e.g., shallow, compressed (low-level) temperature inversion) 3⁄4 Air stagnation advisory 

 Buffer zones 

3⁄4 Application method 3⁄4 Application rate from lookup table on label (lb ai/A) 3⁄4 Application block size from lookup table on label (acres) 3⁄4 Credits applied 3⁄4 Buffer zone distance 3⁄4 Description of areas in the buffer zone that are not under the control of the owner/operator of the applicat

block 

 Respirators and other personal protective equipment (PPE) for handlers (handler task, protective clothing, 

respirator type, respirator cartridge type, respirator cartridge replacement schedule, eye protection, gloves, othPPE) 

 Emergency procedures (evacuation routes, locations of telephones, contact information for first responders, 

local/state/federal contacts, key personnel and emergency procedures/responsibilities in case of an incident, equipment/tarp/seal failure, odor complaints or elevated air concentration levels outside buffer zone suggestin

potential problems, or other emergencies). 

 Posting procedures (name, address, and phone number of person(s) who will post signs, location of posting s

procedures for sign removal) 

 Site-specific response and management (if applicable) 

3⁄4 Fumigant site monitoring (if applicable) 
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 Description of who, when, where, and procedures for monitoring buffer zone perimeter 

3⁄4 Response information for neighbors (if applicable) 

 List of residences, businesses, and neighboring property owners informed  Name, address, and phone number of person doing notification  Method of sharing information 

 State and tribal lead agency notification (If state and/or tribal lead agency requires notice, provide a list of con

that were notified and date notified.) 

 Plan describing how communication will take place between applicator, land owner/operator, and other on-sit

handlers (e.g., tarp cutters/removers, irrigators) for complying with label requirements (e.g., buffer zone locatbuffer zone start/stop times, timing of tarp cutting and removal, PPE). 

3⁄4 Name and phone number of persons contacted 3⁄4 Date contacted 

 Authorized on-site personnel 

3⁄4 Names, addresses and phone numbers of all handlers 3⁄4 Employer name, addresses, and phone numbers for all handlers 3⁄4 Tasks that each handler is authorized and trained to perform 3⁄4 Date of PPE training for each handler 3⁄4 For handlers designated to wear respirators when respiratory protection is required (minimum of one hand

date of medical qualification to wear a respirator and date of fit testing for respirator. 

 Air monitoring 

3⁄4 For buffer zone monitoring (if applicable): 

 Name, address, and phone number of handler to perform monitoring activities  Location and timing of monitoring for the buffer zone 

3⁄4 For handlers without respiratory protection: 

 If sensory irritation is experienced, indicate whether operations will be ceased or operations will con

with respiratory protection 

 If intend to cease operations when sensory irritation is experienced, provide the name, address, and p

number of the handler that will perform monitoring activities prior to operations resuming 

3⁄4 For handlers with respiratory protection: 

 Representative handler tasks to be monitored  Monitoring equipment to be used and timing of monitoring 

 Good Agricultural Practices (GAPs) 

3⁄4 Description of applicable mandatory GAPs (registrants may also include optional GAPs) 3⁄4 Measurements and documentation to ensure GAPs are achieved (e.g., measurement of soil and other site 

conditions) 

 Description of hazard communication. (The buffer zone around the application block has been posted in 

accordance with the label. Pesticide product labels and material safety data sheets are on-site and readily avaifor employees to review.) 

 Record keeping procedures (the owner/operator of the application block as well as the certified applicator, mu

keep a signed copy of the site-specific FMP and the post application summary for 2 years from the date of 
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application). 

For situations where an initial FMP is developed and certain elements do not change for multiple fumigation sites applicator information, authorized on-site personnel, record keeping procedures, emergency procedures, etc.) only 

elements that have changed need to be updated in the site-specific FMP provided the following: 

3⁄4 The certified applicator supervising the application has verified that those elements are current and applic

to the application block before it is fumigated and has documented the verification in the site-specific FMand 

3⁄4 Recordkeeping requirements are followed for the entire FMP (including elements that do not change) 

The employer of fumigant handlers must make the FMP available to each of their handler employees involved in tfumigation. The certified applicator or the owner/operator of the application block must provide a copy of the FMP to any fede

state, tribal, or local enforcement personnel who request the FMP. In the case of an emergency, the FMP must be 

made available when requested by federal/state/local emergency response and enforcement personnel. Within 30 days of completing the application portion of the fumigation process, the certified applicator supervisinapplication must complete a post-fumigation application summary that describes any deviations from FMP that haoccurred, measurements taken to comply with GAPs as well as any complaints and/or incidents that have been reported to him/her. The summary must include the actual date of the application, application rate, and size of 

application block fumigated. The Post-Application Summary must contain the following elements:  Actual date of the application, application rate, and size of application block fumigated  Summary of weather conditions on the day of the application and during the 48-hour period following the 

fumigant application 

 Tarp damage and repair information (if applicable) 

3⁄4 Location and size of tarp damage 3⁄4 Description of tarp/tarp seal/tarp equipment failure 3⁄4 Date and time of tarp repair 

 Tarp perforation/removal details (if applicable) 

3⁄4 Description of tarp removal (if different than in the FMP) 3⁄4 Date tarps were perforated 3⁄4 Date tarps were removed 

 Complaint details (if applicable) 

3⁄4 Person filing complaint (e.g., on-site handler, person off-site) 3⁄4 If off-site person, name, address, and phone number of person filing complaint 3⁄4 Description of control measures or emergency procedures followed after complaint 
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 Description of incidents, equipment failure, or other emergency and emergency procedures followed (if 

applicable) 

 Details of elevated air concentrations monitored on-site (if applicable) 

3⁄4 Location of elevated air concentration levels 3⁄4 Description of control measures or emergency procedures followed 3⁄4 Air monitoring results 

 When sensory irritation experienced: 

• Date and time of sensory irritation • Handler task/activity • Handler location where irritation was observed • Resulting action (e.g., cease operations, continue operations with respiratory protection) 

 When using a direct read instrument: 

• Sample date and time • Handler task/activity • Handler location • Air concentration • Sampling method 

 Date of buffer zone sign removal  Any deviations from the FMP The certified applicator who supervised the fumigation and the owner/operator of the agricultural establishment wthe fumigation took place must keep a signed copy of the site-specific FMPs and the post-application summary recfor at least 2 years following the application and must make them available, upon request, to Federal, state, tribal, and/or local enforcement personnel.” 

General Buffer Zones requirements for all formulations 

“General Buffer Zone Requirements: A “buffer zone” must be established for every fumigant application. The following describes the general buffer zone requirements: • “Buffer zone” is an area established around the perimeter of each application block or greenhouse where a soi

fumigant is applied. The buffer zone must extend from the edge of the application block or greenhouse perimeequally in all directions. 

• All non-handlers including field workers, nearby residents, pedestrians, and other bystanders, must be exclude

from the buffer zone during the buffer zone period except for transit (see exemptions section). 

• The “buffer zone period” starts at the moment when any fumigant is delivered/dispensed to the soil within the 

application block and lasts for a minimum of 48 hours after the fumigant has stopped being delivered/dispensthe soil. 

• An “application block” is a field or portion of a field treated with a fumigant in any 24-hour period. See exce

provided in the “Buffer zone proximity” section below. 

Buffer zone proximity - Exception to Allow Buffer Zone Overlap 
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• Before the application begins, the certified applicator must determine whether the application block or its resu

buffer will overlap with a buffer that is already in effect. 

• To reduce the potential for off-site movement from multiple fumigated fields, buffer zones from multiple met

sodium and metam potassium application blocks may not overlap UNLESS: 

• A buffer zone may NOT overlap buffer zones from other application blocks that are already in effect UNL

a minimum of 12 hours has elapsed from the time the first application ends until the second application be

• Emergency preparedness and response measures specified in the label have been implemented if there are 

homes, businesses, or property not within the control of the fumigator within 300 feet of each buffer zone.

In addition, only for Low Release Height-Solid Stream Center Pivot Applications: 

• Before the application begins, the certified applicator must determine whether the application block or its resul

buffer will overlap with a buffer that is already in effect. 

• To reduce the potential for off-site movement from multiple fumigated fields, buffer zones from multiple met

sodium and metam potassium application blocks may not overlap UNLESS: 

• A buffer zone may NOT overlap buffer zones from other application blocks which are already in effect 

UNLESS both application blocks are treated using low release height-solid stream center pivot systems. T12 hour waiting period does not apply in this instance. 

• Emergency preparedness and response measures specified in the label have been implemented if there are 

homes, businesses, or property not within the control of the fumigator within 300 feet of each buffer zone.

 Buffer zone distances

• Buffer zone distances must be based on look-up tables on product labels. Twenty-five feet is the minimum bu

distance regardless of site-specific application parameters. 

• If the buffer zone after applying all applicable buffer zone credits is larger than 1⁄2 mile then the application is 

prohibited. 

Authorized entry to buffer zones

• Only authorized handlers who have been properly trained and equipped according to EPA’s Worker Protectio

Standard (WPS) and label requirements may be in the buffer zone during the buffer zone period. 

Exemptions for transit through buffer zones 

• Vehicular and bicycle traffic on public and private roadways through the buffer zone is permitted. "Roadway" 

means that portion of a street or highway improved, designed or ordinarily used for vehicular travel, exclusive the sidewalk or shoulder even if such sidewalk or shoulder is used by persons riding bicycles. In the event a highway includes two or more separated roadways, the term "roadway" shall refer to any such roadway separa(This definition is based on the definition of roadway in the Uniform Vehicle Code prepared by the National Committee on Uniform Traffic Laws and Ordinances. See http://www.ncutlo.org/ for more details) 

• Bus stops or other locations where persons wait for public transit are not permitted within the buffer zone. 

• See the Posting Section of this document for additional requirements that may apply. 
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Structures under the control of owner/operator of the application block 

• Buffer zones may not include buildings used for storage such as sheds, barns, garages, etc., UNLESS,

1. The storage buildings are not occupied during the buffer zone period, and 2. The storage buildings do not share a common wall with an occupied structure. 

• See the Posting Section of this document for additional requirements that may apply. 

Areas not under the control of owner/operator of the application block

• Buffer zones may not include residential areas (including employee housing, private property, buildings, 

commercial, industrial, and other areas that people may occupy or outdoor residential areas, such as lawns, gardens, or play areas) UNLESS, 

3. The occupants provide written agreement that they will voluntarily vacate the buffer zone during the entir

buffer zone period, and 

4. Reentry by occupants and other non-handlers must not occur until, 

° The buffer zone period has ended, and; ° Sensory irritation is not experienced 

• Buffer zones may not include agricultural areas owned/operated by persons other than the owner/operator of t

application block, UNLESS, 

3. The owner/operator of the application block can ensure that the buffer zone will not overlap with a buffer 

zone from any adjacent property owners, except as provided for above, and 

4. The owner/operator of the adjacent areas (i.e., areas that are not under the control of the owner/operator o

application block) provides written agreement to the applicator that they, their employees, and other persowill stay out of the buffer zone during the entire buffer zone period. 

• Buffer zones must not include roads and rights of way UNLESS, 

1. The area is not occupied during the buffer zone period, and 2. Entry by non-handlers is prohibited during the buffer zone period. 3. Applicators must comply with all local laws and regulations. 

• For all other publicly owned and/or operated areas such as parks, side walks, walking paths, playgrounds, and 

athletic fields, buffer zones must not include these areas UNLESS, 

1. The area is not occupied during the buffer zone period, 2. Entry by non-handlers is prohibited during the buffer zone period, and 3. Written permission to include the public area in the buffer zone is granted by the appropriate state and/or local authorities responsible for management and operation of the area. 

4. Applicators must comply with all local laws and regulations.” 

Buffer Zone Distances for all formulations 

“Buffer zone distances must be calculated using the application rate and the size of the application block. 
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Figure 1. Broadcast Application Figure 2. Bedded Application 

In Figures 1 and 2, the dashed line represents the perimeter of the field, the shaded area is the portion of the field ttreated, and the un-shaded area is the area of the field that is untreated. Assuming both fields are 10 acres, and onl

50% of field in figure 2 is fumigated, the labeled rate per treated acre is 400 lbs ai/A for both Figure 1 and 2. The 

broadcast rate for figure 1 is 400 lb ai/A but the effective broadcast equivalent rate for Figure 2 is 200 lbs ai/A. T

minimum buffer zone distances must be based on the broadcast or effective broadcast equivalent rates.” Note to registrant: Labels may express rates as lbs per treated acre under the application instructions but they must identify buffer zone distances based on the broadcast or effective broadcast equivalent rates. “For all metam-sodium and metam-potassium soil applications, the tables following this Label Table (Tables 13-1must be used to determine the minimum buffer distances. Round-up to the nearest rate and block size, where applicable.” 

Buffer Zone Credits “Buffer Zone Credits 

The buffer zone distances for metam-sodium and metam-potassium applications may be reduced by the percentagelisted below. Credits may be added, but credits cannot exceed 80%. Also the minimum buffer zone distance is 25 regardless of buffer zone credits available. • 30% reduction in buffer zone distance, IF the organic content of soil in the application block is greater than 3%

20% reduction in buffer zone distance, IF the organic content of soil in the application block is between 3% an2%. 10% reduction in buffer zone distance, IF the organic content of soil in the application block is between and 1%. Record the measurements taken to verify the organic content in the FMP. 

• 10% reduction in buffer zone distance, IF the clay content of the soil in the application block is greater than 2

Record the measurements taken to verify the clay content in the FMP. 

• For center pivot irrigation and shank applications: 20% reduction in buffer zone distance, IF the soil temperatu

in the application block is less than 50 degrees Fahrenheit. 10% reduction in buffer zone distance, IF the soil temperature in the application block is between 50 and 70 degrees Fahrenheit. Record the measurements taken 

verify the soil temperature in the FMP. 

• For drip irrigation, flood irrigation, and rotary tiller and spray blade applications: 10% reduction in buffer zon

distance, If the soil temperature in the application block is between 50 and 70 degrees Fahrenheit. Record the 

measurements taken to verify the soil temperature in the FMP. 

• A 30% buffer credit is appropriate for the following high-barrier tarps: Olefinas Embossed VIF, Klerks VIF, P
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Blockade, Bromostop® (1.38 mil), Eval/Mitsui TIF (1.38 mil), Hytiblock 7 Black (0.00125”), XL Black Bloc(0.00125”), Hytibar (1.5 mil), and IPM Clear VIF (1.38 mil). A 15% buffer credit is appropriate for the follow

high-barrier tarps: Canslit Heatstrip Silver and Canslit Metalized. Record the information to verify the tarp typthe FMP. 

Example of credit calculation For example, if the buffer zone is 50 feet and the application qualifies for a buffer zone reduction credit since the s

organic content is greater than 3%. Then the buffer zone can be reduced by 10%, i.e., reduced by 5 feet based on tfollowing calculation: 50 feet – (50 feet x 10%) = 45 feet” 

Posting “Posting Fumigant Buffer Zones 

• Posting of a buffer zone is required unless there is a physical barrier that prevents bystander access to the 

buffer zone. 

• Buffer zone posting signs must: 

o Be placed at all usual points of entry and along likely routes of approach from areas where people no

under the land operator’s control may approach the buffer zone. 

o Some examples of points of entry include, but are not limited to, roadways, sidewalks, paths, and bik

trails. 

o Some examples of likely routes of approach are the area between a buffer zone and a roadway, or the 

between a buffer zone and a housing development. 

• Buffer zone posted signs must meet the following criteria: 

o The printed side of the sign must face away from the treated area toward areas from which people co

approach. 

o Signs must remain legible during entire posting period and must meet the general standards outlined 

the WPS for text size and legibility (see 40 CFR §170.120). 

o Signs must be posted before the application begins and remain posted until the buffer zone period ha

expired. 

o Signs must be removed within 3 days after the end of the buffer zone period. o Registrants must provide generic buffer zone posting signs which meet the criteria above at points of 

for applicators to use. 

Exception: If multiple contiguous blocks are fumigated within a 14-day period, the entire periphery of the contigublocks’ buffer zones may be posted. The signs must remain posted until the last buffer zone period expires and sig

may remain posted until 3-days after the buffer zone period for the last block has expired. Additional requirements for treated area posting: 

• The treated area posted signs must remain posted for no less than the duration of the entry restricted perio

after treatment. 

• Treated area signs must be removed within 3 days after the end of the entry-restricted period. 
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• Signs must meet the general standards in the WPS for placement, text size, and location (40 CFR §170.12

 Contents of SignsThe fumigant treated area sign must state the following: -- Skull and crossbones symbol 

-- "DANGER/PELIGRO," -- "Area under fumigation, DO NOT ENTER/NO ENTRE," -- "Metam-Sodium or Metam-Potassium Fumigant in USE," 

-- the date and time of fumigation, -- the date and time entry prohibition is lifted -- brand name of this product, and -- name, address, and telephone number of the certified applicator in charge of the fumigation. The fumigant buffer zone sign must state the following: -- Do not walk sign 

-- "DO NOT ENTER/NO ENTRE," -- "Metam-Sodium or Metam-Potassium and [Name of product] Fumigant BUFFER ZONE,” 

-- contact information for the certified applicator in charge of the fumigation. 

Application restrictions “Restrictions for Schools and Other Difficult To Evacuate Sites 

• Difficult-to-evacuate sites include schools (preschool to grade 12), state licensed day care centers, nursing 

homes, assisted living facilities, hospitals, in-patient clinics, and prisons. 

• No fumigant application with a buffer zone greater than 300 feet is permitted within 1/4 mile (1320 feet) 

the sites listed above unless the site is not occupied during the application and the 36-hour period followi
188

the start of application. 

• No fumigant application with a buffer zone of 300 feet or less is permitted within 1/8 mile (660 feet) of th

sites listed above unless the site is not occupied during the application and the 36-hour period following tstart of application.” 

Emergency preparedness and response 

“Emergency Preparedness and Response • If the buffer zone is greater than 25 feet or less than or equal to 100 feet, and there are residences and busines

within 50 feet from the edge of the buffer zone 

• If the buffer zone is greater than 100 feet but less than or equal to 200 feet, and there are residences and 

businesses within 100 feet from the edge of the buffer zone 

• If the buffer zone is greater than 200 feet but less than or equal to 300 feet, and there are residences and 

businesses within 200 feet from the edge of the buffer zone 

• If the buffer zone is greater than 300 feet or the buffer zones overlap, and there are residences and businesse

within 300 feet from the edge of the buffer zone 

Then the certified applicator must either follow the directions under the “fumigant site monitoring” section or follothe directions under the “response information for neighbors” section below. If the buffer zone is 25 feet then the Emergency Preparedness and Response requirements are not applicable. 

From the beginning of the fumigant application until the buffer zone period expires, a certified applicator or someounder his/her supervision must: 

• Monitor for air concentrations of MITC in areas between the buffer zone perimeter and the areas (such as 

residences and businesses) that trigger this requirement. 

• Monitoring the air concentration levels must begin the evening on the day of application and continue until th

buffer zone period expires with a minimum of at least 8 samples during the buffer zone period, including thesperiods: 

- once, 1 hour before sunset, - once, during the night, - once, 1 hour after sunrise, and - once, during the day. 

If at any time the person monitoring the air concentrations experiences sensory irritation, then the emergency respoplan stated in the FMP must be immediately implemented. If other problems occur, such as a tarp coming loose, tthe appropriate control plan must be activated. The location and results of the air monitoring must be recorded in FMP. Response Information for Neighbors 
189

The certified applicator (or someone under his/her supervision) supervising the fumigation must ensure that resideand owners/operators of businesses that meet the criteria have been provided the emergency response information least 1 week before fumigation occurs. The information provided may include application dates that range for no than 4 weeks. After 4 weeks, the information must be delivered again. Information that must be included: 

• The general location of the application block • Fumigant(s) applied including the active ingredient, name of the fumigant product(s), and the EPA Registration 

number 

• Contact information for the applicator and property owner/operator • Time period in which the fumigation is planned to take place (must not range more than 4 weeks) • Early signs and symptoms of exposure to the fumigant(s) applied, what to do, and who to call if you believe yo

being exposed (911 in most cases). 

• How to find additional information about fumigants. 

The method used to share the response information for neighbors must be described in the FMP and may be accomplished through mail, door hangers, or through other methods that will effectively inform people in residencand businesses within the required distance from the edge of the buffer zone.” 

Notice to State and Tribal Lead Agencies 

“Notice to State and Tribal Lead Agencies If your state and/or tribal lead agency requires notice, information must be provided to the appropriate state or trib

lead agency prior to the application. Please refer to http://www.epa.gov/pesticides/reregistration/soil_fumigants/ f

list of states and tribal lead agencies that require notice and information on how to submit the information. The information that must be provided to state and trial lead agencies includes the following: 

o Location of the application blocks, o Fumigant(s) applied including EPA Registration #, o Applicator and property owner/operator contact information, 

o Time period that fumigation may occur.” 

Pre-plant application restrictions “Maximum application rate is 320 lbs ai/A.” 
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Environmental hazards “This pesticide is toxic to mammals, birds, aquatic invertebrates and fish. Do not apply directly to water, or to are

where surface water is present or to intertidal areas below the mean high water mark. Do not contaminate water wdisposing of equipment wash waters or rinsate. Metam-sodium and metam-potassium has certain properties and characteristics in common with chemicals that ha

been detected in groundwater (highly soluble in water and has low adsorption to soil). To reduce the potential for leaching to groundwater, especially in soils with shallow groundwater, for broadcast ta

applications, the tarps must be perforated (cut, punched, etc.) before noon and only when rainfall is not expected within 12 hours. For raised-bed, tarped applications, rainfall is not a factor since planting occurs with the tarp in place. 

For untarped applications, leaching and runoff may occur if there is heavy rainfall after soil fumigation.” 

General application restrictions 

“Do not apply this product in a way that will contact workers or other persons, either directly or through drift. On

protected handlers may be in the area during application.” 
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Center Pivot Irrigation Application (High Release Height*) 

Buffer Zone Distance in Feet 

Application Rate (lb ai/A) 

Block Size (A) 

32 56 80 100 120 140 160 180 200 220 240 260 280 300 320 

1 50 80 125 160 185 205 220 235 250 262 275 288 300 312 325 5 50 100 150 188 225 263 300 313 325 338 350 363 375 389 400 10 50 100 150 200 250 300 350 375 400 425 450 488 525 563 600 20 75 138 200 250 300 350 400 450 500 550 600 650 700 750 800 30 75 138 200 269 338 407 475 557 638 719 800 850 900 950 1000 40 100 200 300 363 425 488 550 638 725 813 900 975 1050 1125 1200 50 100 200 300 382 463 544 625 719 813 907 1000 1100 1200 1300 1400 60 200 300 400 475 550 625 700 825 950 1075 1200 1300 1400 1500 1600 70 200 300 400 488 575 663 750 888 1025 1163 1300 1400 1500 1600 1700 80 200 300 400 500 600 700 800 950 1100 1250 1400 1500 1600 1700 1800 90 250 350 450 550 650 750 850 1000 1150 1300 1450 1563 1675 1788 1900 100 300 400 500 600 700 800 900 1050 1200 1350 1500 1625 1750 1875 2000 110 350 450 550 650 750 850 950 1100 1250 1400 1550 1688 1825 1963 2100 120 400 500 600 700 800 900 1000 1150 1300 1450 1600 1750 1900 2050 2200 140 600 700 800 900 1000 1100 1200 1350 1500 1650 1800 1950 2100 2250 2400 160 800 900 1000 1100 1200 1300 1400 1550 1700 1850 2000 2150 2300 2450 2600 

* This buffer zone distance table is for center pivot irrigation equipment in which the: 1) release height OR spray height greater tha

> 30 lbs psi at the sprinkler head. 
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Center Pivot Irrigation Application (Medium Release Height**) 

Buffer Zone Distance in Feet

Application Rate (lb ai/A) 

Block Size (A) 

32 56 80 100 120 140 160 180 200 220 240 260 280 300 320 

1 25 25 25 37 50 62 75 87 100 112 125 138 150 162 175 5 25 38 50 63 75 88 100 113 125 138 150 263 175 188 200 10 25 50 75 94 113 132 150 175 200 225 250 288 325 363 400 20 25 50 75 107 138 169 200 250 300 350 400 450 500 550 600 30 25 50 75 125 175 225 275 357 438 519 600 650 700 750 800 40 50 75 100 163 225 288 350 438 525 613 700 775 850 925 1000 50 50 75 100 182 263 344 425 519 613 707 800 900 1000 1100 1200 60 75 138 200 275 350 425 500 625 750 875 1000 1100 1200 1300 1400 70 75 138 200 288 375 463 550 688 825 963 1100 1200 1300 1400 1500 80 75 138 200 300 400 500 600 750 900 1050 1200 1300 1400 1500 1600 90 88 169 250 350 450 550 650 800 950 1100 1250 1363 1475 1588 1700 100 100 200 300 400 500 600 700 850 1000 1150 1300 1425 1550 1675 1800 110 150 250 350 450 550 650 750 900 1050 1200 1350 1488 1625 1763 1900 120 200 300 400 500 600 700 800 950 1100 1250 1400 1550 1700 1850 2000 

** This buffer zone distance table is for center pivot irrigation equipment in which the: 1) release height AND spray height is less t

29lbs. or less PSI at the sprinkler head, AND 3) there are no end guns. 
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Center Pivot Irrigation Application (Low Release Height-Solid Stream***) 

Buffer Zone Distance in Feet

Application Rate (lb ai/A) 

Block Size (A) 

32 56 80 100 120 140 160 180 200 220 240 260 280 300 320 

1 25 25 25 30 35 40 50 60 70 85 105 125 145 165 185 5 25 25 25 35 50 63 75 94 113 132 150 163 175 188 200 10 25 38 50 63 75 88 100 125 150 175 200 225 250 275 300 20 25 38 50 70 89 107 125 157 188 438 250 288 325 363 400 30 25 38 50 75 100 125 150 188 225 263 300 350 400 450 500 40 25 50 75 107 138 169 200 238 275 313 350 413 475 538 600 50 25 50 75 119 163 207 250 294 338 382 425 494 563 632 700 60 50 75 100 150 200 250 300 363 425 488 550 613 675 738 800 70 63 100 138 192 244 297 350 419 488 557 625 694 763 832 900 80 75 125 175 232 288 344 400 475 550 625 700 775 850 925 1000 90 88 138 188 254 319 385 450 532 613 694 775 857 938 1019 1100 100 100 150 200 275 350 425 500 588 675 763 850 938 1025 1113 1200 110 125 188 250 325 400 475 550 644 738 832 925 1019 1113 1207 1300 120 150 225 300 375 450 525 600 700 800 900 1000 1100 1200 1300 1400 

*** This buffer zone distance table is for center pivot irrigation equipment in which the: 1) release height AND spray height is less 29lbs. or less PSI at the sprinkler head, AND 3) solid stream nozzle (e.g. drizzle boom, Smart Drop, etc.), AND 4) there are no end 
194

All Chemigation Except Center Pivot 

and Flood Applications Buffer Zone Distance In Feet

Application Rate (lb ai/A) 

Block Size (A) 

32 56 80 100 120 140 160 180 200 220 240 260 280 300 320 

1 25 38 50 55 62 68 75 80 87 93 100 115 125 137 150 2 25 38 50 57 65 73 81 88 97 104 113 152 138 150 163 3 25 38 50 58 67 78 88 97 106 116 125 189 150 163 175 4 25 38 50 60 70 83 94 105 116 127 138 226 163 175 188 5 25 38 50 63 75 88 100 113 125 138 150 263 175 188 200 6 25 40 55 69 83 97 110 125 131 155 170 268 205 223 240 7 25 43 60 75 90 106 120 138 140 173 190 273 235 258 280 8 25 45 65 81 98 114 130 150 146 190 210 278 265 293 320 9 25 48 70 87 105 123 140 163 155 208 230 283 295 328 360 10 25 50 75 94 113 132 150 175 200 225 250 288 325 363 400 20 25 50 75 107 138 169 200 250 300 350 400 450 500 550 600 30 25 50 75 125 175 225 275 357 438 519 600 650 700 750 800 40 50 75 100 163 225 288 350 438 525 613 700 775 850 925 1000 50 50 75 100 182 263 344 425 519 613 707 800 900 1000 1100 1200 60 75 138 200 275 350 425 500 625 750 875 1000 1100 1200 1300 1400 70 75 138 200 288 375 463 550 688 825 963 1100 1200 1300 1400 1500 80 75 138 200 300 400 500 600 750 900 1050 1200 1300 1400 1500 1600 90 88 169 250 350 450 550 650 800 950 1100 1100 1363 1475 1588 1700 100 100 200 300 400 500 600 700 850 1000 1150 1300 1425 1550 1675 1800 110 150 250 350 450 550 650 750 900 1050 1200 1350 1488 1625 1763 1900 120 200 300 400 500 600 700 800 950 1100 1250 1400 1550 1700 1850 2000 
195

Shank Injection Applications-Tarped and Untarped 

Buffer Zone Distance In Feet

Application Rate (lb ai/A)

Block Size (A) 

32 44 56 68 80 100 120 140 160 180 200 220 240 260 280 300 320 

1 25 25 25 25 25 25 25 25 25 32 38 44 50 56 63 69 75 2 25 25 25 25 25 25 25 25 25 32 38 44 50 58 66 74 81 3 25 25 25 25 25 25 25 25 25 32 38 44 50 60 69 79 88 4 25 25 25 25 25 25 25 25 25 32 38 44 50 61 72 83 94 5 25 25 25 25 25 25 25 25 25 32 38 44 50 63 75 88 100 6 25 25 25 25 25 26 28 29 30 38 45 53 60 75 90 105 120 7 25 25 25 25 25 28 30 33 35 44 53 62 70 88 105 123 140 8 25 25 25 25 25 29 33 36 40 51 60 70 80 100 120 140 160 9 25 25 25 25 25 31 35 40 45 57 68 79 90 113 135 158 180 10 25 25 25 25 25 32 38 44 50 63 75 88 100 125 150 175 200 20 25 25 25 25 25 32 38 44 50 69 88 132 175 207 238 269 300 30 25 32 38 44 50 57 63 69 75 113 150 188 225 257 288 319 350 40 25 32 38 44 50 57 63 69 75 119 163 207 250 288 325 363 400 50 25 38 50 63 75 82 88 94 100 150 200 250 300 350 400 450 500 60 25 38 50 63 75 82 88 94 100 163 225 288 350 413 475 538 600 70 38 51 63 76 88 104 119 135 150 207 263 319 375 444 513 582 650 80 50 63 75 88 100 125 150 175 200 250 300 350 400 475 550 625 700 90 63 76 88 100 113 138 163 188 213 266 319 372 425 500 575 650 725 100 75 88 100 113 125 150 175 200 225 282 338 394 450 525 600 675 750 110 75 91 107 123 138 163 188 213 238 298 357 416 475 550 625 700 775 120 75 94 113 132 150 175 200 225 250 313 375 438 500 575 650 725 800 
196

Rotary Tiller and Spray Blade Applications 

Buffer Zone Distance In Feet 

Application Rate (lb ai/A) 

Block Size (A) 

32 56 80 100 120 140 160 180 200 220 240 260 280 300 320 

1 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 5 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 6 25 25 25 25 25 25 25 25 25 25 25 27 29 30 32 7 25 25 25 25 25 25 25 25 25 25 25 29 32 36 39 8 25 25 25 25 25 25 25 25 25 25 25 30 36 41 46 9 25 25 25 25 25 25 25 25 25 25 25 32 39 47 53 10 25 25 25 25 25 25 25 25 25 25 25 34 43 52 60 20 25 25 25 25 25 25 25 25 25 25 25 49 73 97 120 30 25 25 25 25 25 25 25 25 25 25 25 64 103 142 180 40 25 25 25 25 25 25 25 25 25 25 25 75 125 275 225 50 25 25 25 25 25 25 25 42 58 74 90 135 180 225 270 60 25 25 25 25 25 25 25 57 88 119 150 188 225 263 300 70 25 25 25 25 25 25 25 64 103 142 180 218 255 293 330 80 25 25 25 25 25 25 25 72 118 164 210 248 285 323 360 
197

Drip Irrigation Applications-Tarped and Untarped 

Buffer Zone Distance in Feet 

Application Rate (lb ai/A) 

Block Size (A) 

32 56 80 100 120 140 160 180 200 220 240 260 280 300 320 

1 25 25 25 25 25 25 25 25 25 25 25 32 38 44 50 2 25 25 25 25 25 25 25 27 28 30 31 37 41 46 50 3 25 25 25 25 25 25 25 29 32 35 38 41 44 47 50 4 25 25 25 25 25 25 25 30 35 39 44 46 47 49 50 5 25 25 25 25 25 25 25 32 38 44 50 50 50 50 50 6 25 25 25 26 28 29 30 37 43 49 55 56 58 59 60 7 25 25 25 28 30 33 35 42 48 54 60 63 65 68 70 8 25 25 25 29 33 36 40 47 53 59 65 69 73 76 80 9 25 25 25 31 35 40 45 52 58 64 70 76 80 85 90 10 25 25 25 32 38 44 50 57 63 69 75 82 88 94 100 20 25 38 50 57 63 69 75 82 88 94 100 125 150 175 200 30 25 38 50 57 63 69 75 94 113 132 150 188 225 263 300 40 25 50 75 82 88 94 100 113 125 138 150 200 250 300 350 50 25 50 75 82 88 94 100 125 150 175 200 250 300 350 400 60 25 63 100 113 125 138 150 175 200 225 250 300 350 400 450 70 25 76 125 140 150 163 175 207 250 269 300 350 400 450 500 80 25 88 150 163 175 188 200 238 275 313 350 400 450 500 550 
198

 Summary of Labeling Changes for all Metam-Sodium Sewer Use PPE Requirements Established by the REDfor all Sewer Fumigants1

“All fumigant handlers who apply or may be exposed to either liquid spray or vapors must wear: -- coveralls over long-sleeve shirt and long pants, -- chemical resistant gloves, -- chemical resistant footwear plus socks, -- a NIOSH-approved full-face, or helmet/hood style respirator with either 

• an organic-vapor-removing cartridge with a prefilter approved for pesticides (MSHA/NIOSH approval 

number prefix TC-23C), or 

• a respirator with a canister approved for pesticides (MSHA/NIOSH approval number prefix TC-14G). 

All mixers and loaders must wear: -- long-sleeved shirt, long pants, -- chemical resistant gloves, -- chemical resistant footwear plus socks, -- chemical-resistant apron if transferring or loading the fumigant or cleaning up spills or equipment, and -- be provided, have immediately available, and must wear in an emergency a respiratory of the type required in th

section. All support personnel who remain outside the treatment zone and who are not exposed to either liquid spray or vapmust wear: -- long-sleeved shirt, long pants, shoes, and socks, and  -- be provided, have immediately available, and must wear in an emergency, such when they may be exposed to l

spray or vapors, the handler PPE listed in this section.” “See the engineering control section for additional requirements.” 

Engineering Controls and Application Restrictions 

“Engineering Controls and Application Restrictions Mixers and loaders must use a system that is capable of removing the pesticide from the shipping container and transferring it into mixing tanks and/or application equipment. At any disconnect point, the system must be equippwith a dry disconnect or dry couple shut-off device that is warranted by the manufacturer to minimize drippage. Handlers must wear the personal protective equipment required in the PPE section of this labeling for mixers and 

loaders. Applicators must use an application nozzle designed to propel the application hose through the sewer using waterjetting capabilities. The nozzle should be designed to allow water to escape under pressure and thereby creating a rocket like effect that both propels the nozzle forward while preparing the roots and pipe for the application of 

herbicide. Once the hose and nozzle have arrived at the beginning of the herbicide application location the applicawill turn off the water pressure and the spring-loaded nozzle will switch to the foaming application. 
199

The applicator must retrieve the hose hydraulically while applying foaming herbicide within the pipe. A clean water rinse hose must be positioned to continuously rinse off the application hose as it is extracted from thpipe. The applicator must shut off the foaming herbicide 50 feet before the applicator nozzle reaches the manhole in ord

purge the last of the foaming herbicide from the hose prior to it exiting the manhole.” 

Notification Requirements 

Applicators must notify downstream waste water treatment facilities prior to the start of metam-sodium applicationthat they may monitor the operations of the wastewater treatment plant. Applicators must report how much product will be applied to the sewer system to operators of downstream water 

treatment plants and to inform these operators that high concentrations of these chemicals in wastewater may adve

affect the biological sewage breakdown process in wastewater treatment plants. 

1 PPE that is established on the basis of Acute Toxicity of the end-use product must be compared to the active ingredient PPE in this document

protective PPE must be placed in the product labeling. For guidance on which PPE is considered more protective, see PR Notice 93-7. 

Labeling Changes Summary Table for the Antimicrobial Uses of MITC, Metam-Sodium and Metam-Potass

Description Amended Labeling Language 

MITC 
200

Labeling Changes Summary Table for the Antimicrobial Uses of MITC, Metam-Sodium and Metam-Potass

All End Use Products For remedial treatment of wooden poles/timbers: 

1. Plug the pre-drilled holes immediately after applications; 2. Do not treat structures/beams indoors; 

3. Do not drill an application hole through seasoning checks to apply product. If the 

hole intersects a check, plug the hole and drill another. If more than 2 treatment holes intersect an internal void or rot pocket, redrill the holes farther up the pole into relatively solid wood. 

Directions 

Metam-Sodium All End Use Products For remedial treatment of wooden poles/timbers: 

1. Plug the pre-drilled holes immediately after applications; 

2. Do not treat structures/beams indoors; 

3. Do not drill an application hole through seasoning checks to apply product. If the 

hole intersects a check, plug the hole and drill another. If more than 2 treatment holes intersect an internal void or rot pocket, redrill the holes farther up the pole into relatively solid wood. 

Directions 

Update language for treatment of sewage sludge/animal waste to replace current language which reads that material needs to be placed for 14-21 days or until a phytotoxicity test is done (registration 5481-477) 

“Treated material must be placed in a protected storage area for 21 days.” Directions 
201

Labeling Changes Summary Table for the Antimicrobial Uses of MITC, Metam-Sodium and Metam-Potass

Update language for treatment of sewage sludge/animal waste to replace current language which reads that material needs to be placed for 14-21 days or until a phytotoxicity test is done (registration 5481-477) 

“A closed system is used when applying this product.” Directions 

Update PPE language for treatment of sewage sludge/animal waste (registration 5481-477) 

“Appropriate PPE (long pants, long-sleeved shirts and chemical-resistant gloves) must be used when applying this product. 

Personal Pr

Metam-Potassium Update application method language for cooling water system use 

“A metering pump system must be used when applying this product.” Directions 

Update PPE language for cooling water system use “Appropriate PPE (long pants, long-sleeved shirts, and chemical resistant gloves) must be used when applying this product.” 

Personal Pr
202

Appendix A: Uses Eligible for Reregistration 

Metam Sodium (PC Code 039003) and Metam Potassium (PC Code 039002) Soil Fumigant Uses Eligible For 

Use Site Formulation 

Annua

Applicat

Rate 

Soil Pre-Plant Alfalfa, Asparagus (nursery production only), Artichokes, Barley, Basil, Beet, Berries, [includes all EPA Crop Group 13, Berries Group, i.e., blackberry (Rubus eubatus); bingleberry; black satin berry; boysenberry; Cherokee blackberry; chesterberry; Cheyenne blackberry; coryberry; darrowberry; dewberry; Dirksen thornless berry; Himalayaberry; hullberry; lavacaberry; lowberry; lucretiaberry; mammoth blackberry; marionberry; nectarberry; olallieberry; Oregon evergreen berry; phenomenalberry; rangeberry; ravenberry; rossberry; Shawnee blackberry; youngberry, and varieties and/or hybrids of these; blueberry (Vaccinium spp.); currant (Ribes spp.); elderberry (Sambucus spp.); gooseberry (Ribes spp.); huckleberry (Gaylussacia spp.); loganberry (Rubus loganobaccus); raspberry-black and red (Rubus occidentalis, Rubus strigosus, Rubus idaeus)], Broccoli, Brussels sprouts, Cabbage, Carrot, Cauliflower, Celeriac, Chineese greens or bok choy, Cilantro, Citrus (orchard replant only), [includes all of EPA Crop Group 10, Citrus Fruits, i.e., calamondin (Citrus mitis X Citrofortunella mitis); citrus citron (Citrus medica); citrus hybrids (Citrus spp.) (includes: chironja, tangelo, tangor); grapefruit (Citrus paradisi); kumquat (Fortunella spp.); lemon (Citrus jambhiri, Citrus limon); lime 

Liquid, Soluble Concentrate 

320 lbs. a.i./Acre 
203

Use Site Formulation 

Annua

Applicat

Rate 

(Citrus aurantiifolia); mandarin (tangerine) (Citrus reticulata); orange, sour (Citrus aurantium); orange, sweet (Citrus sinensis); pummelo (Citrus grandis, Citrus maxima); satsuma mandarin (Citrus unshiu)], Collard, Corn, Cover crops (i.e., crops planted between periods of regular crop production to prevent soil erosion, control weeds, and improve soil quality that are incorporated into the soil before the next crop is planted and may not be harvested for food or feed), Crops grown solely for seed, Cucurbits [includes all of EPA Crop Group 9, Cucurbit Vegetables Group, i.e., chayote (fruit) (Sechium edule); Chinese waxgourd (Chinese preserving melon) (Benincasa hispida); citron melon (Citrullus lanatus var. citroides); cucumber (Cucumis sativus); gherkin (Cucumis anguria); gourd, edible (Lagenaria spp.) [includes: hyotan, cucuzza (Luffa acutangula, L. cylindrical; includes hechima, Chinese okra)]; Momordica spp. (includes balsam apple, balsam pear, bitter melon, Chinese cucumber); muskmelon [hybrids and/or cultivars of Cucumis melo (includes true cantaloupe, cantaloupe, casaba, crenshaw melon, golden pershaw melon, honeydew melon, honey balls, mango melon, Persian melon, pineapple melon, Santa Claus melon, and snake melon)]; pumpkin (Cucurbita spp.); squash, summer (Cucurbita pepo var. melopepo) (includes: crookneck squash, scallop squash, straightneck squash, vegetable marrow, and zucchini); squash, winter (Cucurbita maxima; C. moschata) (includes: butternut squash, calabaza, hubbard squash) and (C. mixta; C. pepo) (includes acorn squash, spaghetti squash); and watermelon (includes hybrids and/or varieties of Citrullus lanatus)], Dill, Eggplant, Forest seedlings, Ginger, Grape (vineyard replant only), Kale, 
204

Use Site Formulation 

Annua

Applicat

Rate 

Kohlrabi, Leafy greens [includes all of EPA Crop Group 4, Leafy Vegetables (Except Brassica Vegetables), i.e., amaranth (leafy amaranth, Chinese spinach, tampala) (Amaranthus spp.); arugula (roquette) (Eruca sativa); cardoon (Cynara cardunculus); celery (Apium graveolens var. dulce); celery, Chinese (Apium graveolens var. secalinum); 

celtuce (Lactuca sativa var. angustana); chervil (Anthriscus cerefolium); chrysanthemum, edible-leaved (Chrysanthemum coronarium var. coronarium); chrysanthemum; garland (Chrysanthemum coronarium var. spatiosum); corn salad (Valerianella locusta); cress, garden (Lepidium sativum); cress, upland (yellow rocket, winter cress) (Barbarea vulgaris); dandelion (Taraxacum officinale); dock (sorrel) (Rumex spp.); endive (escarole) (Cichorium endivia); fennel, Florence (finochio) (Foeniculum vulgare Azoricum Group); lettuce, head and leaf (Lactuca 

sativa); orach (Atriplex hortensis); parsley (Petroselinum crispum); purslane, garden (Portulaca oleracea); purslane, winter (Montia perfoliata); radicchio (red chicory) (Cichorium intybus); rhubarb (Rheum rhabarbarum); spinach (Spinacia oleracea); spinach, New Zealand (Tetragonia tetragonioides, T. expansa); spinach, vine (Malabar spinach, Indian spinach) (Basella alba); and swiss chard (Beta vulgaris var. cicla)], Leek, Mint, Mustard, Nursery stock (fruit seedlings and rose bushes only), Onion, Ornamentals (floriculture only), Pome fruit (orchard replant only), [includes all of EPA Crop Group 11, Pome Fruits Group —Commodities, i.e., apple (Malus domestica); crabapple (Malus spp.); loquat (Eriobotrya japonica); mayhaw (Crataegus aestivalis, C. opaca, and C. rufula); pear (Pyrus communis); pear, oriental (Pyrus pyrifolia); and quince (Cydonia oblonga)], Peanut, Pepper, 
205

Use Site Formulation 

Annua

Applicat

Rate 

Potato, Radish, Rye, Sugar beet, Soybean, Stone fruit (orchard replant only), [includes all of EPA Crop Group 12, Stone Fruits Group—Commodities, i.e., apricot (Prunus armeniaca); cherry, sweet (Prunus avium); cherry, tart (Prunus cerasus); nectarine (Prunus persica); peach (Prunus persica); plum (Prunus domestica, Prunus spp.); plum, Chickasaw (Prunus angustifolia); plum, Damson (Prunus domestica spp. insititia); plum, Japanese (Prunus salicina); plumcot (Prunus. armeniaca X P. domestica); prune (fresh) (Prunus domestica, Prunus spp.)], Strawberries, Sugar beet, Sweet potato, Swiss Chard, Tobacco, Tomatoes, Tree nuts (orchard replant only), [includes all of EPA Crop Group 14, Tree Nuts Group (i.e., almond (Prunus dulcis); beech nut (Fagus spp.); Brazil nut (Bertholletia excelsa); butternut (Juglans cinerea); cashew (Anacardium occidentale); chestnut (Castanea spp.); chinquapin (Castanea pumila); filbert (hazelnut) (Corylus spp.); hickory nut (Carya spp.); macadamia nut (bush nut) (Macadamia spp.); pecan (Carya illinoensis); and walnut, black and English (Persian) (Juglans spp.) as well as pistachio], Turnip, Turf (including golf courses), and Wheat 

Metam Sodium (PC Code 039003) Uses Eligible For Reregistration 
206

Use Site Formulation Method of 

Application 

Application Rate/ No. of 

applications 

Use Limitat

Sewer Use Root Control in Sewer Lines 

liquid, soluble concentrate (SC), ready-to-use (RTU) 

Foam application equipment 

For sewers and drains, the maximum application rate is 0.212 lbs ai/gallon of solution. 

Agricultural Premises & Equipment Sewage Sludge & Animal Waste Treatment 

Sewage Sludge & Animal Waste Treatment 

Sewage Sludge & Animal Waste Treatment 

Sewage Sludge & Animal Waste Treatment 

Sewage Sludge & Animal W

Wood Preservatives 
207

Timbers and Wood Poles/Pilings 

Ready to Use Liquid 

Fumigant is poured into holes that have been drilled into section of poles where decay is detected 

Wood Poles: Drill holes at a 45 degree angle to a length of approximately 2 1⁄2 times the radius of the wood. The first hole should be at the ground line and succeeding holes approximately 6-8 inches higher and 90 degrees rotated from the next lower hole. The amount of fumigant to be used per pole is based on the pole circumference at the ground line. Plug holes with treated wood plugs. 

None Listed 
208

Metam Potassium (PC Code 039002) Uses Eligible For Reregistration

Use Site Formulation Method of 

Application 

Application Rate/ No. of 

applications 

Use Limitat

Industrial Processes and Water Systems Recirculating Cooling Tower Water 

Ready to Use Chemical 

metering pumps 

Initial Slug: 5.1 to 10.2 fluids ounces of product per 1000 gallons of water. Subsequent Dose: 1.7 to 10.2 fluid ounces per 1000 gallons of water every 1 to 5 days or as needed; or Initial Dose: 6.9 to 13.9 fl. Oz. of product per 1000 gallons of system water (56-115 ppm). Subsequent Dosage: 2.3 to 9.8 fl. Oz per 1000 gallons of water (20-115 ppm); or Initial Dose: 1.5 to 3.0 fl. Oz. of product per 1000 gallons of system water (15-30 ppm). Subsequent Dosage: 0.5 to 3.0 fl. Oz per 1000 gallons of water (5-30 ppm); or Initial Dose: 3.3 to 6.6 fl. Oz. of product per 1000 gallons of system water 
209

Use Site Formulation Method of 

Application 

Application Rate/ No. of 

applications 

Use Limitat

(30-60 ppm). Subsequent Dosage: 1.1 to 6.6 fl. Oz per 1000 gallons of water (10-60 ppm). 
210

Use Site Formulation Method of 

Application 

Application Rate/ No. of 

applications 

Use Limitat

Industrial Water Purification systems (including reverse osmosis systems, filters, clarifiers and ion exchange equipment) 

Ready to Use Chemical 

metering pumps 

24.5 to 49.0 fl. Oz per 1000 gallons of water (200-400 ppm) for 4 to 6 hours. Online Maintenance treatment: 4.9 to 9.8 fl. Oz. of product per 1000 gallons of water (40 to 80 ppm) for 6 – 12 hours, once a week or as needed; or 5.0 to 10.0 fl. Oz per 1000 gallons of water (50-100 ppm) for 4 to 8 hours. Online Maintenance treatment: 1.0 to 2.0 fl. Oz. of product per 1000 gallons of water (10 to 20 ppm) for 6 – 12 hours, once a week or as needed. 

Not intended for use in pota
211

Use Site Formulation Method of 

Application 

Application Rate/ No. of 

applications 

Use Limitat

Pulp & Paper Mills Ready to Use Chemical 

metering pumps 

0.25 to 1lb.of product per short ton; or 0.8-5.0 lbs of product per ton for six hours; or 0.2 to 0.4 lb of product per ton. 

None Listed

Materials Preservatives Paper making (preservation) 

Ready to Use Chemical 

metering pumps 

75 to 400 ppm depending on PH level. 

None Listed 

Tanning Drum Leather Ready to Use Open pour To preserve tannery glue 

solutions, add to glue at rates of 100-250 ppm, based on the total weight of the glue solution 

None Listed 
212

 MITC (068103) Uses Eligible For Reregistration 

Use Site Reg. no./ 

Formulation 

Method of 

Application 

Application Rate/ No. of 

applications 

Use Limitat

Wood preservatives Remedial Treatment: Utility poles, piling, bridge timbers, and laminated wood products (located outdoors). 

Ready to Use Manually 

insert tube into pre-drilled hole 

Dosage Rate: 1 tube (30 grams) per drill hole; Pole Circumference in 

inches/No. of Tubes Installed : 35” or less - 3 holes beginning at ground line spaced 120 degrees apart and 6”to 8” higher than the previous hole. 36” to 49” - 4 holes beginning at the ground line spaced 90 degrees apart and 6” to 8” higher than the previous hole. 50” to 59”- 5 holes beginning at the ground line spaced 70 degrees apart and 6”to 8” higher than the previous pole. 60” to 70” – 6 holes beginning at ground line spaced 60 degrees apart and 4” to 6” higher than 

Do not contaminate water, storage or disposal. Do not use, pour, spill or stflame. 
213

Use Site Reg. no./ 

Formulation 

Method of 

Application 

Application Rate/ No. of 

applications 

Use Limitat

the previous hole. 70” to 80”- 7 holes. The first 2 at ground line 160 degrees apart and the remaining 5 spaced 60 degrees apart and 4” to 6” higher than the previous hole. 80” to 90”- 8 holes. The first 2 at ground line 180 degrees apart and the remaining 6 spaced 50 degrees apart and 4” to 6” higher than the previous hole. Over 90”– 9 holes. The first 2 at ground line 180 degrees apart and the remaining 7 spaced 45 degrees apart and 4” to 6” higher than the previous hole. 
214

Appendix B: Studies Used to Make the Reregistration Decision 

This section not currently available.
215

Appendix C: Technical Support Documents 

Additional support of this RED is maintained in the OPP docket at: http://www.regulations.gov

at EPA-HQ-OPP-2005-0125. This docket may be accessed in the OPP docket room located at S4900, One Potomac Yard 2777 S. Crystal Drive, Arlington, VA. It is open Monday through 

Friday, excluding federal holidays, from 8:30-4:00 pm. All documents may be view in the OPP 

docket room or downloaded or viewed via the internet. 

Health Effects Support Documents 

• “Metam Sodium: Third Revision of the HED Human Health Risk Assessment;” May 

2009; Charles Smith; Health Effects Division, U.S. EPA. 

• Methyl Bromide, 1,3-Dichloropropene, Chloropicrin, Dazomet, Metam 

Sodium/Potassium, MITC: Health Effects Division (HED) Component of Agency 

Response To Comments On 2008 Reregistration Eligibility Documents (Date May 14, 

2009). 

• “Methyl Bromide, 1,3-Dichloropropene, Chloropicrin, Dazomet, Metam 

Sodium/Potassium, MITC; PC Codes 053201, 029001, 081501, 035602, 039003, 

039002, 068103; Health Effects Division (HED) Component of Agency Response To 

Comments On 2008 Reregistration Eligibility Documents;” May 2009; Charles Smith 

and Jeff Dawson; Health Effects Division; U.S. EPA. 

• EPA-HQ-OPP-2007-0350-0172, MOA Mode of Action, Eye Irritation, and the IntraSpecies Factor: Comparison of Chloropicrin and MITC. June 25, 2008. DP Barcode 

293356. 

• “Methyl Bromide (PC Code 053201), Chloropicrin (PC Code 081501), Dazomet (PC 

Code 035602), Metam Sodium and Potassium (PC Codes 039003 & 039002), MITC (PC 

Code 068103), Updated Health Effects Division Recommendations for Good Agricultural 

Practices and Associated Buffer Credits;” May 2009; Charles Smith and Jeff Dawson; 

Health Effects Division; U.S. EPA. 

• EPA-HQ-OPP-2007-0350-0173, Factors Which Impact Soil Fumigant Emissions - 

Evaluation For Use In Soil Fumigant Buffer Zone Credit Factor Approach. June 9, 2008. 

(DP Barcode 306857). 

Biological and Economical Analysis Support Documents 

• Evaluation of Potential Impacts to Wastewater Treatment Plant Microorganisms...”; PC 

Code: 039003; DP Barcode: 364230; April 2009; Pat Jennings; Antimicrobials Division; 

U.S. EPA. 

• Response to comments on use site restrictions included in the Reregistration Eligibility 

Decision (RED) for Metam-Sodium and Metam-Potassium (DP Barcode: 363544); May 

2009; Nikhil Mallampalli, Chism, Becker; Biological and Economic Analysis Division; 

U.S. EPA. 

• Revised Alternatives Assessment on Root Control Use of Metam-Sodium in Sewer Lines 

(DP # 358321) and Response to Public Comments Received (EPA Docket No. EPA-HQOPP-2005-0125);” May 2009; Sunil Ratnayake and Tara Chandgoyal; Biological and 

Economic Analysis Division; U.S. EPA. 

• Identification of High-Use Fumigation Areas at State and County Levels (DP#364647);” 

May 2009; Monisha Kaul and Jenna Carter; Biological and Economic Analysis Division; 

U.S. EPA. 
216

• Response to BEAD Related Public Comments Received on the Reregistration Eligibility 

Decision for Chloropicrin, Dazomet, Metam Potassium, Metam Sodium, and Methyl 

Bromide (DP# 363545) May 14, 2009. 

• Analysis of Soil Fumigant Risk Management Requirements using Geographic 

Information Systems: Case Studies based on a Forest Seedling Nursery (DP#363546). 

May 13, 2009. 

• Process for Defining High-Use Fumigation Areas at the State and County Levels 

(DP#364647) May 14, 2009. 

• EPA-HQ-OPP-2007-0350-0168, Review of Stakeholder Submitted Impact Assessments 

of Proposed Fumigant Buffers, Comments on Initial Buffer Zone Proposal, and Case 

Studies of the Impact of a Flexible Buffer System for Managing By-Stander Risks of 

Fumigants. June 25, 2008. DP Barcode 353940. 

• EPA-HQ-OPP-2007-0350-0169, Response to Phase 5 BEAD Related Public Comments 

Received on the Reregistration of Chloropicrin, Dazomet, Metam Potassium, Metam 

Sodium, and Methyl Bromide. June 25, 2008. DP Barcode 353940. 

• EPA-HQ-OPP-2007-0350-0018, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin, Methyl Bromide, and Metam Sodium in Cucurbit Production. 

• EPA-HQ-OPP-2007-0350-0019, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin, Methyl Bromide, and Metam Sodium in Eggplant Production. 

• EPA-HQ-OPP-2007-0350-0020, Assessment of the Benefits Soil Fumigants (Methyl 

Bromide, Chloropicrin, Metam-Sodium, Dazomet) Used by Forest Tree Seedling 

Nurseries. 

• EPA-HQ-OPP-2007-0350-0021, Assessment of the Benefits of Soil Fumigation with 

Methyl Bromide, Chloropicrin, Dazomet, and Metam Sodium for Use in Raspberry 

Nurseries, Fruit and Nut Deciduous Tree Nurseries, and Rose Bush Nurseries in 

California. 

• EPA-HQ-OPP-2007-0350-0022, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin and Metam-sodium in Onion Production. 

• EPA-HQ-OPP-2007-0350-0023, Assessment of the Benefits of Soil Fumigation with 

Methyl Bromide, Chloropicrin, and Metam Sodium in Grape Production. 

• EPA-HQ-OPP-2007-0350-0024, Assessment of the Benefits of Soil Fumigation with 

Methyl Bromide, Chloropicrin and Metam Sodium in Tree Nut Production. 

• EPA-HQ-OPP-2007-0350-0025, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin and Metam Sodium in Pome Fruits Production. 

• EPA-HQ-OPP-2007-0350-0026, Assessment of the Benefits of Soil Fumigation with 

Methyl Bromide, Chloropicrin, and Metam Sodium in Stone Fruit Production. 

• EPA-HQ-OPP-2007-0350-0027, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin, Methyl Bromide, and Metam Sodium in Bell Pepper Production. 

• EPA-HQ-OPP-2007-0350-0028, Assessment of the Benefits of Soil Fumigation with 

Metam Sodium in Potato Production. 

• EPA-HQ-OPP-2007-0350-0029, Assessment of Soil Fumigation with Chloropicrin, 

Methyl Bromide and Metam-sodium in Strawberry Production. 

• EPA-HQ-OPP-2007-0350-0030, Assessment of the Benefits of Chloropicrin, Methyl 

Bromide, Metam-sodium and Dazomet Use In Strawberry Nursery Runner Production. 

• EPA-HQ-OPP-2007-0350-0031, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin, Methyl Bromide, and Metam-sodium on Sweet Potato Production. 

• EPA-HQ-OPP-2007-0350-0032, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin in Tobacco Production. 

• EPA-HQ-OPP-2007-0350-0033, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin, Methyl Bromide, and Metam Sodium in Tomato Production. 
217

• EPA-HQ-OPP-2007-0350-0034, Assessment of the Benefits of Soil Fumigation with 

Metam-Sodium in Carrot Production. 

• EPA-HQ-OPP-2007-0350-0035, Assessment of the Benefits of Soil Fumigation with 

Metam Sodium in Peanut Production. 

• EPA-HQ-OPP-2007-0350-0036, Assessment of the Benefits of Soil Fumigation with 

Chloropicrin, Methyl Bromide, Metam Sodium and Dazomet in Ornamental Production. 

• EPA-HQ-OPP-2007-0350-0037, BEAD's Planned Impact Assessments on Agricultural 

Sites with Significant Use of Soil Fumigants (Chloropicrin, Dazomet, Methyl Bromide, 

Metam Potassium, and Metam Sodium. 

Environmental Fate and Ecological Effects Support Documents 

• EPA-HQ-OPP-2004-0159-0117 – Transmittal Memo for the Revised Environmental Fate 

and Ecological Effects Risk Assessment for Metam Sodium and Metam Potassium. 

• EPA-HQ-OPP-2004-0159-0118 Revised Environmental Fate and Ecological Effects Risk 

Assessment for Metam Sodium and Metam Potassium. 

Antimicrobial Assessment Support Documents 

• EPA-HQ-OPP-2007-0350-1066, Phase 6 Response to Substantive Public Comments on 

Antimicrobials Division’s Occupational and Residential Assessments for the 

Reregistration Eligibility Decision (RED) Documents for the following chemicals: 

Methylisothiocyanate (MITC), Metam Sodium, Dazomet, and Chloropicrin. 

Buffer Zone Credits Support Document

• Methyl Bromide (PC Code 053201), Chloropicrin (PC Code 081501), Dazomet (PC 

Code 035602), Metam Sodium and Potassium (PC Codes 039003 &039002), MITC (PC 

Code 068103), DP Barcode 362369, Updated Health Effects Division Recommendations 

for Good Agricultural Practices and Associated Buffer Credits. May 14, 2009. 

• EPA-HQ-OPP-2007-0350-1073, Factors Which Impact Soil Fumigant Emissions - 

Evaluation for Use in Soil Fumigant Buffer Zone Credit Factor Approach. Dawson, J. 

and Smith, C.; D306857; June 9, 2008. 

• EPA-HQ-OPP-2007-0350-1078, Health Effects Division Recommendations for Fumigant 

Data to Refine Exposure Assessments. DP Barcode 353724. 

Risk Management Support Documents 

• EPA-HQ-OPP-2007-0350-1077, SRRD’s Response to Phase 5 Public Comments for the 

Soil Fumigants. Rice, M. and McNally, R.; July 2008. 

• EPA-HQ-OPP-2007-0350-0003, Risk Mitigation Options to Address Bystander and 

Occupational Exposures from Soil Fumigant Applications. 
218

Appendix D: FMP Template-MeBr Example

Note: The Agency plans to work with the registrants and other stakeholders to develop a metam-sodium and metampotassium specific FMP that will serve as a template for growers and the States to use for the most common 

application methods prior to the 2010 and 2011 growing season. 

Certified Applicator Supervising the Fumigation 

Name and phone number: License number: 

 Commercial applicator 

 Private applicator 

Employer name and address: Date of completing registrant 

training program: 

General Site Information 

Application block location, address, or global positioning system (GPS) coordinates: 

Name, address, and phone number of owner/operator of application block: 

General Application Information 

Target application date/window: Brand name of fumigant: EPA Registration Number: 

Tarps (check here if section is not applicable  )

Brand name: Lot #: Thickness: 

Name and phone number of contact person responsible for repairing tarps: 

Schedule for checking tarps for damage, tears, and other problems: 

Maximum time following notification of damage that the person(s) responsible for tarp repair will respond: 

Minimum time following application that tarp will be repaired: Minimum size of damage that will be repaired: 

Other factors used to determine when tarp repair will be conducted: 

Name and phone number of contact person responsible for cutting 

and/or removing tarps (if other than certified applicator): 

Equipment/methods used to cut tarps: 

Schedule and target dates for cutting tarps: Schedule and target dates for removing tarps: 

Soil Conditions 

Description of soil texture and moisture in application block: Description of method used to determine soil moisture level: 
219

Weather Conditions 

Summary of the weather forecast for the day of the application and the 48-hour period following the fumigant application (may attach a copy 

of printed forecast to FMP): 

Buffer Zones 

Application method: 

  Bedded 

  Broadcast 

  Hot gas - outdoor 

  Hot gas - greenhouse 

  Hand held probes 

Rate from 

lookup table 

on label (lb 

ai/A): 

Block size 

from lookup 

table on label 

(acres): 

Credits applied: 

 high barrier film _____________ % 

 organic content _____________ % 

 clay content _____________ % 

 other: _____________ % 

Total credits _____________ % 

Buffer zone 

distance: 

__________ ft 

List and describe areas in the buffer zone that are not under the control of owner/operator of the application block: 

Personal Protective Equipment for Handlers 

Handler Task Clothing 

Respirator Type, Filter Cartridge 

Type and Change-out Schedule 

Eye 

Protection Gloves Other 

Emergency Response Plan 

Description of evacuation routes: 

Locations of telephones: 

Contact information for first responders: Local/state/federal contacts: Other contact information for emergencies: 

Emergency procedures/responsibilities in case of an incident, equipment/tarp/seal failure, odor complaints or elevated air concentration levels 

outside buffer zone suggesting potential problems, or other emergencies). 

Posting Signs 

Name and phone number of person that is doing posting: 

Location of posting signs: 

Procedures for posting and sign removal: 

Site Specific Response and Management  Fumigation Site Monitoring or Response Information for Neighbors 

If Response Information for Neighbors has been selected, completed the following: 

If buffer zone is 25-100 ft:  Neighbors within 50 ft of buffer zone  No neighbors within 50 ft of buffer zone 

If buffer zone is 100-200 ft:  Neighbors within 100 ft of buffer zone  No neighbors within 100 ft of buffer zone 
220

If buffer zone is 200-300 ft:  Neighbors within 200 ft of buffer zone  No neighbors within 200 ft of buffer zone 

If buffer zone is > 300 ft:  Neighbors within 300 ft of buffer zone  No neighbors within 300 ft of buffer zone 

If buffer zones overlap  Neighbors within 300 ft of buffer zone  No neighbors within 300 ft of buffer zone

List of residences and businesses informed (neighboring property owners): 

Name, address, and phone number of person providing information: 

Method used to provide information: 

Notice to State Lead Tribal Agencies 

If your state and/or tribal lead agency requires notice, list contacts that were notified: Date notified: 

Communication Between Applicator, Land Owner/Operator, and Other On-site Handlers 

Plan for communicating to the land owner/operator and all on-site handlers (e.g., tarp cutters/removers, irrigators) requirements to comply 

with label including location and start/stop times of buffer zones; timing of tarp cutting/removal, and PPE: 

Names and phone numbers of persons contacted: Date contacted: 

Comments/notes: 
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Site Map 

Location of application block: _______________________________________________________________________________ 

Map Legend 

 Application block Buffer zone Property lines Roads Right-of-way Walkway, sidewalk, path 

B Bus stop WB Water body DC Daycare facility 

Sch

 School 

NAB

 Nearby application block 

 

IPC

 Inpatient clinic P Prison Well Nursing home 

ALF

 Assisted living facility

 NH
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Handler Information 

Handler Name, Address, and Phone 

Number 

Employer Name, Address, and Phone 

Number 

Tasks They are Trained and 

Authorized to Perform 

Date of PPE 

Training 

Qu
223

Air Monitoring Plan 

For Buffer Zone Monitoring: (check here if section is not applicable  ) 

Name of handler 

performing monitoring 

activities Handler address 

Handler phone 

number Location of monitoring Timing 

For Handlers without Respiratory Protection: (check here if section is not applicable  ) 

If sensory irritation is experienced:  Intend to cease operations  Intend to continue operations with respiratory protection 

If intend to continue operations with respiratory protection, complete section for Handlers with Respiratory Protection below. 

If intend to cease operations - Name, address, and phone number of handler to perform monitoring 

activities prior to operations resuming: 

Monitoring equipment: 

For Handlers with Respiratory Protection: (check here if section is not applicable  ) 

Representative Handler Tasks to be Monitored Monitoring Equipment Timing 

Air Monitoring Plan for Methyl Bromide Formulation with < 20% Chloropicrin 

For Buffer Zone Monitoring: (check here if section is not applicable  ) 
224

Name, address, and phone number of person(s) to perform sampling: 

Area or Structure to be Monitored Before Reentry is Permitted Monitoring Equipment Timing

For Handlers with Respiratory Protection: 

Representative Handler Tasks to be Monitored Monitoring Equipment Timing 
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Methyl Bromide FMP Check List

General Site Information 

A map, aerial photo, or detailed sketch is attached to this FMP that shows each of the following with distances from the application site 

labeled: field location, application block dimensions, buffer zones, property lines, roads, bus stops, water bodies, wells, rights-of-ways, 

nearby application blocks, surrounding structures, and sites requiring 1⁄8 and 1⁄4 mile buffer zones. 



Supervision of Handlers 

An on site certified applicator will directly supervise the handlers participating in the application starting when the fumigant is first 

introduced into the soil and ending after the fumigant has stopped being delivered/dispensed to the soil and the soil is sealed. 

After the application is complete, and before leaving the application block, the certified applicator has provided the owner/operator and 

handlers with written information necessary to comply with the label and procedures outlined in the FMP. 

Fumigant safe handling information has been provided to each handler involved in the application or confirm that each handler 

participating in the application has received fumigant safe handling information in the past 12 months. 

For all fumigation handling tasks, at least 2 WPS-trained handlers must be present. 

Weather Conditions 

Wind speed at the application site is a minimum of 2 mph at the start of the application or forecasted to reach at least 5 mph during the 

application. 

A shallow, compressed (low-level) temperature inversion is not forecast to persist for more than 18 consecutive hours during the 48-hour 

period after the application. 

An air-stagnation advisory is not in effect for the area where the application site is located. 

If air temperatures have been above 100 degrees F in any of the 3 days prior to application, then soil temperature will be measured and 

recorded in the post application summary report. 

Soil Conditions 

The soil has been properly prepared and the surface has been checked to ensure that it is free of clods that are golf ball size or larger. 

The area to be fumigated has been tilled to a depth of 5 to 8 inches. 

Field trash has been properly managed (e.g., residue from a previous crop has been worked into the soil to allow for decomposition prior 

to fumigation, little or no crop residue is present on the soil surface, and crop residue that is present does not interfere with the soil seal). 

The soil temperature at the depth of injection ≤ 90 degrees F at the beginning of the application. 

The soil moisture at 9 inches below the surface is sufficient (field capacity is 50 to 80 percent). 

Trash pulled by the shanks to the ends of the field will be covered with tarp or soil before making the turn for the next pass. 

Shank Applications (check here if section is not applicable  )

For tarped-broadcast and -bedded applications, injection points will be at least 8 inches from the nearest final soil/air interface. 

For tarped-bedded applications, the injection depth will not be as deep as the lowest point of the tarp (i.e., the lowest point of the tuck). 

For untarped-bedded applications, the injection points will be at least 12 inches from the nearest final soil/air interface. 

For untarped-broadcast applications, the injection points will be at least 18 inches from the nearest final soil/air interface. 

For broadcast untarped applications, a disc or similar equipment will be used to uniformly mix the soil to at least a depth of 3 to 4 inches 

to eliminate the chisel or plow traces and will following elimination of the chisel trace, the soil surface will be compacted with a 

cultipacker, ring roller, and roller in combination with tillage equipment. 



For performed bed applications, the soil will be sealed by disruption of the chisel trace using press sealers, bed shapers, cultipackers, or 

by re-shaping (e.g., relisting, lifting, replacing) the beds immediately following injection. 

For beds formed at the time of application, the soil will be sealed by disrupting the chisel trace using press sealers, or bed shapers. 

For shanked bedded and broadcast applications, tarps will be installed immediately after fumigant is injected into the soil. 

Applicators have been trained and instructed not to apply or allow fumigant to drain onto the soil surface. 

For each injection line a check valve been located as close as possible to the final injection point, or applicators will drain/purge the line 

of any remaining fumigant prior to lifting injection shanks from the ground. 

Applicators have been trained and instructed not to lift injection shanks from the soil until the shut-off valve has been closed and the 

fumigant has been depressurized (passively drained) or purged (actively forced out via air compressor) from the system. 

Brass, carbon steel, or stainless steel fittings must be used throughout application rigs. 

Polyethylene tubing, polypropylene tubing, Teflon® tubing or Teflon® -lined steel braided tubing have been used for all low pressure 

lines, drain lines, and compressed gas or air pressure lines and is all other tubing Teflon® -lined steel braided. 

Application equipment been inspected to ensure that application rigs do not contain galvanized, PVC, nylon, or aluminum pipe fittings. 

All rigs include a filter to remove any particulates from the fumigant, and a check valve to prevent backflow of the fumigant into the 

pressurizing cylinder or the compressed air system. 

All rigs include a flowmeter or a constant pressure system with orifice plates to insure the proper amount of fumigant is applied. 

Applicators have been trained and instructed to ensure that positive pressure is maintained in the cylinder at not less than 200 psi during 

the entire time it is connected to the application rig, if a compressed gas cylinder is used. (This is not required for a compressed air 

system that is part of the application rig because if the compressor system fails the application rig will not be operable). 


226

Application rigs are equipped with properly functioning check valves between the compressed gas cylinder or compressed air system and 

the fumigant cylinder. 

Applicators have been trained and instructed to always pressurize the system with compressed gas or by use of a compressed air system 

before opening the fumigant cylinder valve. 

Before using a fumigation rig for the first time, or when preparing it for use after storage, applicators have been trained and instructed to: 

° Check the filter, and clean or replace the filter element as required. 

° Check all tubes and chisels to make sure they are free of debris and obstructions. 

° Check and clean the orifice plates and screen checks, if installed. 

° Pressurize the system with compressed gas or compressed air, and check all fittings, valves, and connections for leaks using soap 

solution. 



Applicators have been trained and instructed to: 

° Install the fumigant cylinder, and connect and secure all tubing. Slowly open the compressed gas or compressed air valve, and 

increase the pressure to the desired level. Slowly open the fumigant cylinder valve, always watching for leaks. 

° When the application is complete, close the fumigant cylinder valve and blow residual fumigant out of the fumigant lines into the 

soil using compressed gas or compressed air. At the end of the application, disconnect all fumigant cylinders from the application 

rig. At the end of the season, seal all tubing openings with tape to prevent the entry of insects and dirt. 

° Calibrate all application equipment and ensure that all control systems must be working properly. 



Hot Gas Applications (check here if section is not applicable  )

Tarps have been installed prior to starting the application. 

All delivery tubes have been placed under the tarp in such a way that they do not move during the application of methyl bromide. 

The fumigant will be introduced from outside of the greenhouse. 

All fittings, connections, and valves have been checked for leaks prior to fumigation and if cylinders are replaced during the fumigation 

process, the connections and valves were checked for leaks prior to continuing the job. 

Tree Replant (non-shank) Application (check here if section is not applicable  )

For each individual tree-site, the tree stump and primary root system have been removed and the tree hole has been backfilled with soil 

before application. 

The fumigant will be injected at a depth of at least 18 inches into the soil. 

The wand will be cleared using nitrogen or compressed air before removing it from the soil and after the wand is cleared and removed 

from the soil, the injection hole will be covered with soil and tamp or the soil will be compacted over the injection hole. 

Buffer Zones 

There are no difficult to evacuate sites within 1⁄4 (or 1⁄8) miles of the application block that will be occupied during the buffer zone period. 

There are no bus stops or other locations where persons wait for public transit within the buffer zone. 

There are no buildings used for storage such as sheds, barns, garages, within the buffer zone that are occupied or that share a common 

wall with an occupied structure. 

For areas in the buffer zone that are not under the control of owner/operator of the application block, written agreement has been 

obtained from occupants that they will voluntarily vacate the buffer zone during the entire buffer zone period. 

For nearby agricultural areas that are in the buffer zone the owner/operator of that property provided written agreement that they, their 

employees, or other persons will stay out of the buffer zone during the entire buffer zone period. 

For publicly owned and/or operated areas (e.g., parks, rights of way, side walks, walking paths, playgrounds, athletic fields) written 

permission has been given to include the public area in the buffer zone from the appropriate local and/or state officials. 

Buffer Zones Overlap (check here if section is not applicable  ) 

A minimum of 12 hours has elapsed from the time the 1st application ends until the 2nd application begins. 

If a structure exists within 300 feet of the buffer zone, appropriate emergency preparedness and response procedures are followed. 

Certified applicator has informed handlers of the overlapping buffers and associated health protection requirements. 

Personal Protective Equipment for Handlers

At least 1 air rescue device (e.g., SCBA) is on-site in case of an emergency. 

All of the handler’s PPE has been cleaned and maintained as required by the WPS for Agricultural Pesticides. 

Hazard Communication 

The application area buffer zone has been posted in accordance with the label. 

Pesticide product labels and material safety data sheets are on-site and readily available for employees to review. 

Recordkeeping 

The owner/operator of the application block has been informed that he/she as well as the certified applicator must keep a signed copy of 

the site-specific FMPs and the post-application summary record for 2 years from the date of application. 

I have verified that this site-specific FMP reflects current site conditions and product label directions before beginning the 
227

fumigation. 

_______________________________________________ ___________________________________ 

Signature of certified applicator supervising the fumigation Date
228

Post-Application Summary

General Application Information 

Application date and time: Application rate: Size of application block: 

Weather Conditions 

Summary of the weather on the day of the application: 

Summary of the weather during the 48-hour period following the fumigant application: 

Soil Conditions (check here if section is not applicable  )

Soil temperature if air temperatures were above 100 degrees F in any of the 3 days prior to the application: 

Tarp Damage and Repair (check here if section is not applicable  )

Location and size of tarp damage: 

Description of tarp/tarp seal/tarp equipment failure: 

Date and time of tarp repair: 

Additional comments or other deviations from FMP (if applicable): 

Tarp Removal (check here if section is not applicable  )

Description of tarp removal (if different than in the FMP): 

Date tarps were cut: Date tarps were removed: 

Odor Complaints (check here if section is not applicable  )

Person filing odor complaint: 

 On-site handler 

 Person off-site 

If off-site person, name, address, and phone number of person filing odor complaints: 

Description of control measures or emergency procedures followed after odor complaint: 

Additional comments: 

Description of Incidents (check here if section is not applicable  )

Description of incident, equipment failure, or other emergency: Date and time: 

Description of emergency procedures followed: 
229

Additional comments: 

Elevated Air Concentration Levels (check here if section is not applicable  )

 On-site 

 Outside buffer zone 

Location of elevated air concentration levels: Date and time: 

Description of elevated air concentration levels: (provide air monitoring results on next page) 

Description of control measures or emergency procedures followed: 

Description of deviations from FMP (if applicable): 

Posting Signs 

Date of sign removal: 

Description of deviations from FMP (if applicable): 

Other 

Additional comments/notes: 
230

Air Monitoring Results 

When Respiratory Protection is Not in Use – Sensory Irritation Experienced (check here if section is not applicable  )

Date and Time Handler Task/Activity 

Handler Location Where 

Irritation Was Observed Resulting Action Comments 

  Cease operations 

 Respiratory protection 

  Cease operations 

 Respiratory protection 

  Cease operations 

 Respiratory protection 

  Cease operations 

 Respiratory protection 

  Cease operations 

 Respiratory protection 

When Respiratory Protection is in Use – Direct Read Instrument Air Monitoring (check here if section is not applicable  )

Sample Type 

Sample 

Number 

Sample 

Date/Time 

Handler 

Task/Activity 

(not 

applicable for 

structural 

monitoring) 

Handler 

Location/ 

Structure 

Location 

Air 

Concentration 

Sampling 

Method 

Comments (e.g., 

sensory irritation 

experienced while 

wearing 

respirator) 

Area 

Breathing Zone 

Structure 

 

Area 

Breathing Zone 

Structure 

 

Area 

Breathing Zone 

Structure 

 

Area 

Breathing Zone 

Structure 

 

Area 

Breathing Zone 

Structure 

 

Area 

Breathing Zone 

Structure 

 

Area 

Breathing Zone 

Structure 

 

Area 

Breathing Zone 

Structure 

 

Area 

Breathing Zone 

Structure 

 

Area 

Breathing Zone 

Structure 

 
231

I have verified that this post application summary reflects the actual site conditions during the fumigation and an accurate 

description of deviations from the FMP (if applicable). 

_______________________________________________ ___________________________________ 

Signature of certified applicator supervising the fumigation Date