United States Chemical Safety June 2011 

Environmental Protection and Pollution Prevention 

Agency (7510P) 

 

Dimethoxane 

Registration Review: 

Final Work Plan 

June 2011 

Docket Number: EPA-HQ-OPP-2010-0686 

www.regulations.gov

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Dimethoxane Registration Review Team

Human Health & Environmental Effects

Timothy Dole 

Srinivas Gowda 

Risk Management

Monisha Harris 

Lance Wormell 

Office of General Counsel

Philip Ross 

________________________________________ 

Supporting documents for the dimethoxane case may be found in the registration review docket

EPA-HQ-OPP-2010-0686 located on the internet at www.regulations.gov. 
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Introduction

This is the Final Work Plan (FWP) of the Environmental Protection Agency (EPA or “the 

Agency”) for the registration review of dimethoxane (case 3064). The work plan includes the 

expected registration review timeline. The work plan also addresses public comments received 

concerning the Preliminary Work Plan (PWP) in the Summary Document which was posted in 

the dimethoxane registration review docket, and any other comments concerning the initial 

docket postings. The Summary Document provided information on what EPA knows about the 

pesticide and what additional risk analyses and data or information the Agency believes are 

needed to make a registration review decision. 

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

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

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

registration. Changes in science, public policy and pesticide use practices will occur over time. 

The registration review program is intended to make sure that, as the ability to assess risk 

evolves and as policies and practices change, all registered pesticides continue to meet that 

statutory standard. The public phase of registration review begins when the initial docket is 

opened for each case. Information on this program is provided at: 

http://www.epa.gov/oppsrrd1/registration_review/. 

The first product containing dimethoxane (PC Code 001001) as an active ingredient was 

registered in the United States in 1962. Currently, there is only one product registered with EPA. 

Dimethoxane is a bacteriostat/fungistat used for the preservation of materials such as industrial 

adhesives (tape joint compounds, silicone based adhesives, starch based adhesives, and other 

adhesives), paints, emulsions (latex, polyvinyl alcohol, silicone, oil, acrylic, polyethylene, 

polyvinyl chloride), coatings, specialty industrial products (pigment slurries, dyestuffs, inks, 

thickeners, gums, lingosulfonates), textile chemicals and finishes (dye levelers, textile 

auxiliaries, softeners, lubricants, antistats, sizings, print pastes), leather processing liquors (dyes, 

wet processing leather finishes), and distillation fuels against microbial degradation during 

manufacture, storage, and service life. There are no tolerances or exemptions from tolerances for 

dimethoxane. 

The Dimethoxane Preliminary Work Plan (PWP) (PC Code 001001) was published on December 

22, 2010 and the 60-day comment period ended on February 22, 2010. The Preliminary Work 

Plan document is available on www.regulations.gov docket number EPA-HQ-OPP-2010-0686. 

Comments Received on the Preliminary Work Plan

The Agency received no comments during the public comment period on the initial docket. In 

the PWP, the Agency solicited comments on specific topics: environmental justice, water body 

impairment, trade irritants, and structure activity relationships. No comments or information 

were received during the public comment period concerning these issues. 

Therefore, the data needs, work plan, and timeline described in the PWP remain as they were 

presented initially. Further, this document makes final the work plan for the dimethoxane 

registration review process. 
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Risk Assessments and Data Needs

The Agency will not conduct an ecological risk assessment. The Agency will conduct a human 

health risk assessment. The Agency will require additional data to conduct the registration 

review for dimethoxane. 

Ecological Risk Assessment Status and Data Needs 

• No ecological risk assessment has been performed for dimethoxane. An ecological risk 

assessment was not performed at the time of the RED because the use patterns were expected 

to result in minimal exposure to the environment and because dimethoxane is not more than 

slightly toxic to fish and aquatic invertebrates, and slightly toxic to practically nontoxic to 

birds. 

• The Agency does not anticipate the need to require additional ecological data for the 

registration review at this time. 

• The Agency anticipates the need to require the following additional environmental fate data 

to conduct the registration review of dimethoxane. 

835.1110 -- Activated Sludge Sorption Isotherm 

835.3110 -- Ready Biodegradability 

• For more information, please refer to Summary of Product Chemistry, Environmental Fate, 

and Ecotoxicity Data for the Dimethoxane Registration Review Decision Document, located 

in the docket. 

Human Health Risk Assessment Status and Data Needs 

• The most recent human health risk assessments for dimethoxane were completed in 2009, in 

support of a new use in household, industrial, and institutional water based products. The 

application for the new use was withdrawn in 2010. 

Dietary Assessment

• Dimethoxane is not registered for any direct or indirect food uses, nor does it have any FDA 

approvals for such uses. Product labeling does not permit use in the manufacture of coatings 

that may come in contact with food. However, there is a potential for drinking water 

exposure from the material preservative uses. The Agency expects that the environmental 

fate data that are being required through registration review will be useful to evaluate this 

potential. Therefore, the need for a drinking water assessment will be determined after the 

environmental fate data are received and reviewed. 

Tolerances and International Harmonization

• There are no tolerances or exemptions from tolerances for dimethoxane. 
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Occupational and Residential Assessment and Risk

• Dimethoxane has a high vapor pressure rapidly hydrolyzes to acetaldehyde. Based upon the 

use patterns, physical/chemical properties and hazard data, the following occupational 

exposures will need to be assessed: dermal and inhalation exposure to dimethoxane from the 

open pour application during paint preservation; inhalation exposure to acetaldehyde released 

from dimethoxane during paint preservation; dermal and inhalation exposure from the use of 

dimethoxane treated paints; and inhalation exposure to acetaldehyde from the use of 

dimethoxane treated paints. 

• EPA intends to assess residential dermal and incidental oral exposures to treated textiles and 

leather products, and residential dermal and inhalation exposure to treated paints. 

Aggregate and Cumulative Exposure and Risk

• In examining aggregate exposure, EPA takes into account the available and reliable 

information concerning exposures to pesticide residues in food and drinking water, as well as 

non-occupational pesticide exposures. An aggregate risk assessment may be needed for 

dimethoxane if it is determined that a drinking water exposure could occur based on the 

environmental fate. The Agency will make this determination once the required 

environmental fate data are received and reviewed. 

• EPA does not have, at this time, available data to determine whether dimethoxane has a 

common mechanism of toxicity with other substances or how to include this pesticide in a 

cumulative risk assessment. 

• For the purposes of this Registration Review, EPA has assumed that dimethoxane does not 

have a common mechanism of toxicity with other substances when used as an antimicrobial 

as registered. 

Human Health Data Needs

• The Agency anticipates the need to require the following additional human health data to 

conduct the registration review of dimethoxane. 

870.2600 -- Skin (dermal) sensitization 

870.3465 -- 90-day inhalation toxicity (rat) 

875.1200 -- Dermal indoor exposure 

875.1400 -- Inhalation indoor exposure 

875.1600 -- Application exposure data reporting and calculations 

875.1700 -- Product use information 

Special Study -- Leaching study on textiles 

Special Study -- Leaching study on leather 

• For more information, please refer to Summary of Human Health Effects Data for 

Dimethoxane Registration Review, located in the docket. 
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Product Chemistry Data Needs 

• The Agency does not anticipate the need to require additional product chemistry data for the 

registration review at this time. 

• For more information, please refer to Summary of Product Chemistry, Environmental Fate, 

and Ecotoxicity Data for the Dimethoxane Registration Review Decision Document, located 

in the docket. 

Incidents:

Ecological: 

• No dimethoxane ecological incidents have been reported in the OPP incident database. 

Human Health: 

• No dimethoxane human poisoning incidents have been reported in the OPP incident 

database. 

Endangered Species 

Based on the low hazard and exposure, the Agency concludes that the registered uses of 

dimethoxane will have 'no effect' (NE) on endangered or threatened terrestrial or aquatic species, 

or their designated critical habitats, as listed by the U.S. Fish and Wildlife Service (USFWS) and 

the National Oceanic and Atmospheric Administration's (NOAA) National Marine Fisheries 

Service (NMFS). EPA anticipates conducting no further analysis of potential risks to 

endangered or threatened species unless public comment provides data or information that would 

otherwise inform the Agency's determination. 

Endocrine Disruptor Screening Program 

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of its reregistration decision, EPA reviewed these data and selected 

the most sensitive endpoints for relevant risk assessment scenarios from the existing hazard 

database. However, as required by FFDCA section 408(p), dimethoxane is subject to the 

endocrine screening part of the Endocrine Disruptor Screening Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 
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may designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine-related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between October 

2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 chemicals, 

which contains 58 pesticide active ingredients and 9 inert ingredients. Dimethoxane is not among 

the group of 58 pesticide active ingredients on the initial list to be screened under the EDSP. 

Accordingly, as part of registration review, EPA will issue future EDSP orders/data call-ins, 

requiring the submission of EDSP screening assays for dimethoxane. For further information on 

the status of the EDSP, the policies and procedures, the list of 67 chemicals, future lists, the test 

guidelines and the Tier 1 screening battery, please visit our website: http://www.epa.gov/endo/. 

Timeline

EPA has created the following estimated timeline for the completion of the dimethoxane 

registration review: 

Anticipated Schedule

Activities Estimated Month/Year

Phase 1: Opening the docket 

Open Public Comment Period for Docket Completed 

December 2010

Close Public Comment Period for Docket Completed 

February 2010 

Phase 2: Case Development 

Develop Final Work Plan (FWP) June 2011 

Issue DCI June 2012 

Data Submission June 2014 

Open Public Comment Period for Preliminary Risk Assessments December 2015 

Close Public Comment Period for Preliminary Risk Assessments March 2016 

Phase 3: Registration Review Decision 

Open Public Comment Period for Proposed Reg. Review Decision June 2016 

Close Public Comment Period for Proposed Reg. Review Decision September 2016 

Final Decision and Begin Post-Decision Follow-up December 2016 

Total (years) 6 

Next Steps
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A DCI will be developed regarding the data needs listed under the “Risk Assessments and Data 

Needs” section of this document. The Agency expects to issue the DCI in June 2012. A human 

health assessment will be conducted for all uses.