Docket Number: EPA-HQ-OPP-2009-0054 

www.regulations.gov

Disulfoton 

Registration Review Decision 

January 2010 

TABLE OF CONTENTS 

I. INTRODUCTION........................................................................................4

II. BACKGROUND INFORMATION ...........................................................5 

III. REGISTRATION REVIEW DECISION..................................................5 

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I. INTRODUCTION 

This document is the Environmental Protection Agency’s (EPA or the Agency) 

Registration Review Decision for disulfoton and is being issued pursuant to 40 CFR § 

155.57 and § 155.58. A registration review decision is the Agency’s determination 

whether a pesticide meets, or does not meet, the standard for registration in the Federal 

Insecticide, Fungicide, and Rodenticide Act (FIFRA). 

 FIFRA, as amended by the Food Quality Protection Act (FQPA) of 1996, 

mandated the continuous review of existing pesticides. All pesticides distributed or sold 

in the United States must generally be registered by EPA, based on scientific data 

showing that they will not cause unreasonable risks to human health or the environment 

when used as directed on product labeling. The registration review program is intended 

to make sure that, as the ability to assess risk evolves and as policies and practices 

change, all registered pesticides continue to meet the statutory standard of no 

unreasonable adverse effects to human health or the environment. Through the 

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

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

this program is provided at: http://www.epa.gov/oppsrrd1/registration_review/. 

In 2006, the Agency implemented the registration review program pursuant to 

FIFRA Section 3(g), and will review each registered pesticide every 15 years to 

determine whether it continues to meet the FIFRA standard for registration. 

 Pursuant to 40 CFR § 155.50, the Agency formally initiated registration review 

for disulfoton (case 0102). The following timeline highlights significant events that have 

occurred during the registration review of disulfoton: 

• March 16, 2009 – Publication of the disulfoton Summary Document, Scoping 

Document, and Problem Formulation Document in the docket (EPA-HQ-OPP2009-0054) for a 60-day public comment period. The Summary Document also 

included the preliminary work plan. 

• July 22, 2009 – Published a Notice of Receipt of Requests to Voluntarily Cancel 

Certain Pesticide Registrations for disulfoton in the Federal Register. No 

comments were received during a 30-day comment period. 

• September 23, 2009 – Published a Product Cancellation Order for disulfoton in 

the Federal Register. 

• October 1, 2009 – Publication of the disulfoton Final Work Plan and the 

Agency’s response to a public comment received during the 60-day comment 

period on the disulfoton Summary Document. 

• October 23, 2009 – Publication of the disulfoton Registration Review Proposed 

Decision in the docket and initiation of a 60-day comment period. 

• December 22, 2009 – Closure of the 60-day public comment period on the 

proposed decision. No comments were received. 

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II. BACKGROUND INFORMATION 

Disulfoton is an organophosphate insecticide registered for use on asparagus, 

beans, broccoli, Brussels sprouts, cabbage, cauliflower, cotton, coffee beans, lettuce, 

radish grown for seed, Christmas trees, Easter lilies, and residential ornamentals. 

Disulfoton was the subject of a July 2002 Interim Reregistration Eligibility Decision 

(IRED), and in July 2006, the Reregistration Eligibility Decision (RED) for disulfoton 

was finalized upon completion of the Organophosphate (OP) Cumulative Risk 

Assessment. In 2008, the Disulfoton RED was amended in response to public comments 

received on the Agency’s reregistration decision. The Disulfoton RED Addendum is the 

Agency’s most recent assessment of the human health and ecological risk of disulfoton 

use. 

 At the beginning of the registration review process for disulfoton in 2009, the 

technical product registrant and end-use product registrant, Bayer (Bayer CropScience, 

Bayer Environmental Science, and Bayer Advanced), and the only other end-use product 

registrant, AMVAC Chemical Co., informed the Agency that they were requesting to 

voluntarily cancel all of their disulfoton product registrations. Following publication of a 

Federal Register notice announcing receipt of those requests and the end of the public 

comment period, the Agency issued the product cancellation order on September 23, 

2009 for all disulfoton product registrations. (Copies of those notices are included in the 

docket for this registration review.) Existing stocks provisions included in the order 

allow registrants to sell and distribute the majority of disulfoton products (EPA Reg. Nos. 

264-723, 264-734, 5481-8989, and 432-1286, CA050010, CA810044, CA840192, 

NC860005, NC880001, NC920011, OR040030, OR050024, TX860007, WA040015, 

WA040028, WA920026) until December 31, 2010. The technical registrant may sell and 

distribute the last two disulfoton products (EPA Reg. Nos. 264-725 and 72155-49) until 

June 30, 2011. Persons other than the registrant may continue to sell, distribute, and use 

disulfoton products until exhausted, provided that such sale, distribution, and use is 

consistent with the terms of the previously approved labeling on, or that accompanied, 

the canceled products. 

III. REGISTRATION REVIEW DECISION 

As stated in the Preliminary Work Plan for disulfoton, the Agency had intended to 

revise the existing risk assessments for disulfoton. However, due to the cancellation 

order issued affecting all disulfoton product registrations in the United States, the Agency 

has found that it is not necessary to conduct new risk assessments for disulfoton and is, 

therefore, issuing a decision pursuant to 40 CFR Part 155.53(c)(2) and 40 CFR Part 

155.58. The voluntary cancellation of U.S. disulfoton registrations will become effective 

prior to the previously planned completion dates for the revised disulfoton risk 

assessments. The effective date of the end of the existing stocks provision included in the 

cancellation of the last disulfoton products registered for use in the U.S. is June 30, 2011. 

The Registration Review Timeline introduced in the disulfoton Preliminary Work Plan 

proposed that the Agency would complete the revised risk assessments in October 2013 

and issue a decision in 2015. 

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The Agency does not expect the current risks associated with disulfoton use to 

differ from those identified during the disulfoton reregistration process. In order to 

mitigate the risks identified in the RED, the Agency specified mitigation measures in the 

RED, which are already in effect on disulfoton product labels. The existing stocks sales 

and distribution deadlines included in the September 23, 2009 cancellation order ensure 

that disulfoton sale, distribution, and use will decline and then cease entirely in the 

United States in the future. During this period, given the mitigation measures that are 

specified in the RED and are currently in place, the Agency has determined that existing 

stocks of disulfoton products may be used until depleted without causing unreasonable 

risk to human health and the environment. Pursuant to 40 CFR § 155.57 and 155.58, the 

Agency is issuing the Registration Review Decision, thus concluding the disulfoton 

registration review, for the reasons discussed above. The affected product registrations 

are subject to the terms and conditions of the September 23, 2009 cancellation order.