Docket Number: EPA-HQ-OPP-2008-0723

www.regulations.gov

Methidathion

Registration Review Final Decision

September 2010

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TABLE OF CONTENTS

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

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

III. REGISTRATION REVIEW FINAL DECISION.....................................5
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I. INTRODUCTION

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

Registration Review Final Decision for methidathion 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 methidathion (case 0034). The following timeline highlights significant events that 

have occurred during the registration review of methidathion:

March 18, 2009 – Publication of the methidathion Summary Document, Scoping 

Document, and Problem Formulation Document in the docket (EPA-HQ-OPP2008-0723) for a 60-day public comment period. The Summary Document also 

included the preliminary work plan.

August 28, 2009 – Publication of the methidathion Final Work Plan and the 

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

period on the methidathion Summary Document. The comments received did not 

change the work plan set out in the preliminary work plan.

April 7, 2010 – Published a Notice of Receipt of requests to voluntarily cancel all 

pesticide registrations containing methidathion in the Federal Register (75 FR 

17735) (FRL-8819-1). No comments were received during the 30-day comment 

period.

June 2, 2010 – Published the Product Cancellation Order for all pesticide 

registrations containing methidathion in the Federal Register (75 FR 30824) 

(FRL-8828-4).

July 28, 2010 - Publication of the methidathion Registration Review Proposed 

Final Decision Notice of Availability in the Federal Register (75 FR 44253).
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September 27, 2010 – Closure of the 60-day public comment period on the 

proposed decision. One comment was received. The comment did not change the 

proposed registration review final decision for methidathion.

II. BACKGROUND INFORMATION

Methidathion is a non-systemic, organophosphate (OP) used as an 

insecticide/acaricide on a wide variety of terrestrial food and feed crops and terrestrial 

non-food crops with the majority of use occurring on almonds, artichokes, and oranges. 

The pesticide acts through inhibition of acetylcholinesterase and is used to control a 

broad range of insects and mites. There are no residential uses. Methidathion was the 

subject of an April 2002 Interim Reregistration Eligibility Decision (IRED), and in July 

2006, the Reregistration Eligibility Decision (RED) for methidathion was finalized upon 

completion of the Organophosphate (OP) Cumulative Risk Assessment. The most recent 

human health assessment and ecological risk assessment for methidathion were

completed in 2002 in support of the IRED.

After the Final Work Plan was published in August 2009 as part of the 

registration review process for methidathion, the technical and end-use product 

registrants, Gowan Company and Syngenta Crop Protection informed the Agency that 

they were each requesting to voluntarily cancel all of their methidathion product 

registrations. A Notice of Receipt of requests to voluntarily cancel all pesticide 

registrations containing methidathion published in the Federal Register on April 7, 2010. 

There were no comments submitted during the 30-day comment period. The Agency 

then issued the product cancellation order on June 2, 2010 for all methidathion product 

registrations. (Copies of those documents are included in the docket for this registration 

review.) As specified in the Cancellation Order, registrants are prohibited from selling or

distributing end-use products containing methidathion as of December 31, 2012. All sale 

and distribution of end-use products containing methidathion by persons other than the 

registrants will be prohibited as of December 31, 2014. After December 31, 2014, 

existing stocks of products containing methidathion labeled for all uses, already in the 

hands of users can be used legally until they are exhausted, provided that the use 

complies with the EPA approved label and labeling of the affected product.

III. REGISTRATION REVIEW FINAL DECISION

As stated in the Preliminary Work Plan for methidathion, the Agency had 

intended to revise the existing risk assessments for methidathion. However, due to the 

cancellation order issued affecting all methidathion product registrations in the United 

States, the Agency has found that it is not necessary to conduct new risk assessments for 

methidathion and is, therefore, issuing a proposed decision pursuant to 40 CFR Part 

155.53(c)(2) and 40 CFR Part 155.58. The voluntary cancellation of all U.S. 

methidathion registrations will become effective prior to the previously planned 

completion dates for the revised methidathion risk assessments. The Registration Review 

Timeline introduced in the methidathion preliminary work plan proposed that the Agency 
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would issue the preliminary risk assessments in December 2013, issue the revised risk 

assessments in June 2014 with a final registration review decision scheduled for 2015.

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

differ from those identified during the methidathion 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 methidathion product labels. The existing stocks 

sales and distribution deadlines included in the June 2, 2010 cancellation order ensure 

that methidathion sale, distribution, and use will decline and eventually 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 believes that existing stocks 

of methidathion 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 Final Decision, thus concluding the 

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

registrations are subject to the terms and conditions of the June 2, 2010 cancellation 

order.