Docket Number EPA-HQ-OPP-2011-0910 

www.regulations.gov

Undecylenic Acid Final Work Plan 

Registration Review 

May 2012 

3

Undecylenic Acid Final Work Plan 

Introduction

This is the Environmental Protection Agency’s (EPA or the Agency) Final Work Plan (FWP) for the 

registration review of undecylenic acid. The FWP includes the expected registration review 

timeline. The FWP also addresses any public comments received on the Preliminary Work Plan 

(PWP) in the Summary Document, which was posted in the undecylenic acid registration review 

docket (EPA-HQ-OPP-2011-0910). The Summary Document, dated December 15, 2011, 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 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/. 

Undecylenic acid is an insecticide and miticide registered for use to kill fleas and mites on pets. It is 

an active ingredient in pet shampoos and pet spray products, which are registered in combination 

with dioctyl sodium sulfosuccinate (DSS). As a pesticidal active ingredient, there are no food uses 

and no tolerances established for undecylenic acid. In addition to its pesticidal uses registered by 

EPA, undecylenic has other uses in products unrelated to the EPA registered uses on pets. 

Undecylenic acid has antifungal properties and is approved by the U.S. Food and Drug 

Administration (FDA) as an over-the-counter drug to treat various skin conditions in humans. It can 

also be used as a flavoring ingredient, and is classified as “Generally Recognized as Safe” (GRAS). 

Undecylenic acid is an organic unsaturated fatty acid that has structural similarities to fatty acids 

found in the diet. 

Pesticide products containing undecylenic acid as an active ingredient were first registered in 1986. 

Therefore, it was not subject to the reregistration requirements of FIFRA and a Reregistration 

Eligibility Decision (RED) document was not completed for undecylenic acid. For registration 

review, only the use of undecylenic acid as a pesticide active ingredient (in pet shampoos and pet 

sprays) will be considered. 

Comments Received on the Summary Document 

No comments were received during the 60-day public comment period on the planned ecological 

assessment and human health scoping document discussed in the Preliminary Work Plan. In the 

Preliminary Work Plan, EPA also solicited comments on three specific topics: environmental 
4

justice, water body impairment, and trade irritants. No comments or information were received 

during the comment period concerning these three topics. 

Anticipated Risk Assessment and Data Needs

The Agency does not intend to require additional data on undecylenic acid. The Agency plans to 

conduct a comprehensive ecological risk assessment, including an endangered species risk 

assessment, for the pesticidal uses of undecylenic acid. Below is a summary of the issues relevant to 

the registration review of undecylenic acid. 

Ecological Risk:

 No ecological risk assessment has been completed for undecylenic acid as a pesticidal active 

ingredient. 

 The Agency has not conducted an ecological risk assessment that supports a complete 

endangered species determination for undecylenic acid. The ecological risk assessment 

planned during registration review will allow the Agency to determine whether undecylenic 

acid’s 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 (FWS) and/or National Marine Fisheries 

Service (NMFS) (the Services), as appropriate. 

 Due to the nature of undecylenic acid as a shampoo use on pets (mammals and reptiles), no 

additional data on terrestrial animals (birds, reptiles, and terrestrial-phase amphibians) are 

anticipated as being needed for this registration review. In addition, because undecylenic 

acid is registered for indoor uses, it is anticipated that no additional ecological data will be 

required for this registration review. 

 Please refer to the Registration Review – Preliminary Problem Formulation for the 

Ecological Risk and Drinking Water Exposure Assessments for Undecylenic Acid, dated 

August 9, 2011, located in docket EPA-HQ-OPP-2011-0910 at www.regulations.gov, for a 

more detailed discussion of the anticipated ecological risk assessment.

Human Health Risk: 

 No human health risk assessment has been completed for undecylenic acid as a pesticidal 

active ingredient. 

 Because of the extensive literature data available on undecylenic acid, its low toxicity, 

FDA’s approval of the chemical as a drug for use at much higher doses than would be 

experienced as a result of pesticide-related uses, and the chemical’s classification by FDA as 
5

Generally Recognized as Safe (GRAS) (21 CFR 178.3400), the Agency concludes that 

additional toxicity data will not be needed for this registration review. 

 A quantitative human health risk assessment is not required under registration review for the 

existing uses of undecylenic acid. There are no risks of concern associated with undecylenic 

acid. No dietary or residential exposure assessment or aggregate risk assessment is required. 

 There are no tolerances established for undecylenic acid. 

 Please refer to the Undecylenic acid. Human Health Assessment Scoping Document in 

Support of Registration Review, dated December 14, 2011, located in docket EPA-HQ-OPP2011-0910 at www.regulations.gov, for a detailed discussion of the human health risk 

assessment status. 

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 most recent registration decision for undecylenic acid, 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), undecylenic acid 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 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 may screen all pesticide chemicals. Between October 

2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 chemicals, 
6

which contains 58 pesticide active ingredients and 9 inert ingredients. Undecylenic acid 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 undecylenic acid. 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

 

The projected timeline for the completion of the undecylenic acid registration review is presented in 

Table 1. 

Table 1. Projected Undecylenic Acid Registration Review Timeline 

Activity Estimated Date 

Opening the Docket 

Open Docket and Open Public Comment Period 2011: December 

Close Public Comment Period 2012: February 

Case Development 

Develop Final Work Plan (FWP) 2012: May 

Open Public Comment Period for Draft Risk Assessment 2012: July – Sept. 

Close Public Comment Period 2012: Oct. – Dec. 

Registration Review Decision 

Develop Proposed Registration Review Decision and Open Public 

Comment Period 

 2013: Jan.–March 

Close Public Comment Period 2013: April –June 

Issue Registration Review Decision and Begin Post-Decision Follow-up 2013 

Total (years) 3 

Next Steps

The Agency plans to conduct a comprehensive ecological risk assessment, including an endangered 

species risk assessment, for the pesticide uses of undecylenic acid. The draft of that risk assessment 

is scheduled to be available for public comment in 2012.