Docket Number: EPA-HQ-OPP-2008-0767

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Table of Contents

1 Introduction............................................................................................................................. 3

2 Background Information......................................................................................................... 4

3 Registration Review Case Closure.......................................................................................... 4
Docket Number: EPA-HQ-OPP-2008-0767

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1 Introduction

The Food Quality Protection Act (FQPA) of 1996 mandated a registration review program. All 

pesticides distributed or sold in the United States generally must be registered by the U.S. 

Environmental Protection Agency (USEPA, EPA, or the agency) based on scientific data 

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

used as directed on product labeling. The registration review program is intended to make sure 

that, as the ability to assess risk evolves and as policies and practices change, all registered 

pesticides continue to meet the statutory standard of no unreasonable adverse effects to human 

health or the environment. Changes in science, public policy, and pesticide use practices will 

occur over time. Through the registration review program, the agency periodically reevaluates 

pesticides to make sure that as change occurs, products in the marketplace can be used safely. 

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

The agency is implementing the registration review program pursuant to Section 3(g) of the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and will review each registered 

pesticide every 15 years to determine whether it continues to meet the FIFRA standard for 

registration. The regulations governing registration review begin at 40 CFR 155.40. The agency

will consider benefits information and data as required by FIFRA. The public phase of 

registration review begins when the initial docket is opened for each case. The docket is the 

agency’s opportunity to state what it knows about the pesticide and what additional risk analyses 

and data or information it believes are needed to make a registration review decision. 

Pursuant to 40 CFR Part 155.50, the agency formally initiated registration review for 4,5-

Dichloro-1,2-dithiol-3-one (RYH-86), case# 5033, in December 2008. The following timeline 

highlights significant events that have occurred during the registration review of RYH-86:

 December 19, 2008 – Publication of the 4,5-Dichloro-1,2-dithiol-3-one (RYH-86)

Summary Document, including the Preliminary Work Plan, Human Health Effects, 

Summary of Product Chemistry, Environmental Fate, and Ecotoxicity documents in the 

docket (EPA-HQ-OPP-2008-0767) for a 90-day public comment period. The agency 

received one public comment which did not affect the registration review schedule of 

RYH-86.

 June 1, 2009 – Publication of the 4,5-Dichloro-1,2-dithiol-3-one (RYH-86) Final Work 

Plan and the agency’s response to the public comment received during the 90-day 

comment period on the RYH-86 Summary Document. No modifications were made to the 

Final Work Plan from the Preliminary Work Plan based on the one public comment

received.

 July 24, 2009- EPA Published the July 13, 2009 Cancellation of Pesticides for NonPayment of Year 2009 Registration Maintenance Fees in the Federal Register (74 FR 

36699) (FRL-8427-4), which included among other products, the only two active U.S. 

registration for RYH-86, EPA Reg. No. 63898-1, Ryh-86NA, and EPA Reg. No. 74655-

18, Spectrum RX7816. A copy of the 2009 cancellation order will be available in the 

docket at EPA-HQ-OPP-2008-0767. 
Docket Number: EPA-HQ-OPP-2008-0767

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2 Background Information

RYH-86 is an antimicrobial pesticide which was previously registered for use as an industrial 

slimicide for closed system injection into pulp and paper slurry in paper mills. A Reregistration 

Eligibility Decision (RED) was not completed for RYH-86 because it was registered after 

November 1, 1984. The final two registrations have been cancelled as discussed below. 

The agency had anticipated issuing the RYH-86 Data Call-In (DCI) in June of 2010, however 

due to the cancellation of the two remaining RYH-86 registrations in the U.S., the agency did not 

issue the DCI. 

Existing stocks provisions included in the July 13, 2009 cancellation order for non-payment of 

maintenance fees allowed the registrant to sell and distribute Ryh-86NA (EPA Reg. No. 63898-

1), and Spectrum RX7816 (EPA Reg. No. 74655-18), the only two registered products

containingRYH-86 until January 15, 2010, one year after the date on which the maintenance fee 

was due. Persons other than the registrant could continue to sell, distribute, and use RYH-86

products until exhausted, provided that such sale, distribution, and use was consistent with the 

terms of the previously approved labeling on, or that accompanied, the cancelled product.

3 Registration Review Case Closure 

As stated in the RYH-86 Preliminary Work Plan and Final Work Plan, the agency had 

anticipated needing additional data to complete the risk assessment for RYH-86 as part of 

registration review. However, due to the issuance of the July 13, 2009 cancellation order for the 

two remaining RYH-86 United States product registrations, the agency has found that it is not 

necessary to complete new risk assessments for RYH-86 and is, therefore, closing the 

registration review case for RYH-86 pursuant to 40 CFR § 155.42(c), which provides that the 

agency ''will close a registration review case if all products in the case are cancelled." 

The existing stocks, sales and distribution deadlines included in the July 13, 2009 cancellation

order anticipate that RYH-86 sale, distribution, and use will decline and eventually cease entirely 

in the United States. During the interim period, the agency anticipates that existing stocks of 

RYH-86 products may be used until depleted without causing unreasonable risk to human health 

and the environment.

Pursuant to 40 CFR § 155.42(c), the agency is closing the registration review case for RYH-86, 

thus concluding the RYH-86 registration review, for the reasons discussed above.