ADMINISTRATIVE ORDER Exemption of Polybutene from the Requirements of Endocrine Disruptor Screening Program Pursuant to the requirements ofSection 408(p) ofthe Federal Food, Drug, and Cosmetic Act (FFDCA), EPA has developed an Endocrine Disrupter Screening Program (EDSP) to be used to determine whether certain chemicals, such as pesticide active and inert ingredients, may have an effect in humans or wildlife simi lar to an effect produced by a "naturally occurring estrogen, or other such endocrine effects as the Administrator may designate." Section 408(p)(4) ofthe FFDCA authorizes EPA, by order, to exempt from the requirements of the endocrine screening program required by Section 408(p)(l) "a biologic substance or other substance ifthe Adm inistrator determines the substance is anticipated not to produce any effect in humans similar to an effect produced by a naturally occurring estrogen." Pursuant to the requirements of FFDCA Section 408(p), EPA has evaluated polybutene, the active ingredient involved in Registration Review Case 4076 [(EPA-HQ-OPP-2009-0649) available at www.regulations.gov

. Based on the analysis and rationale that follow, EPA has determined that the polymer polybutene has a chemical structure that has no biological activity due to its physical and chemical characteristics. Therefore, is not anticipated to produce in humans or any other organ ism an effect similar to that produced by a naturally occurring estrogen, androgen, or thyroid hormone. Pursuant to FFDCA Section 408(p), EPA hereby exempts polybutene from the requirements ofthe EDSP. Description of pesticide products Polybutene is considered the pesticide active ingredient in certain registered pesticide products used primarily as nuisance bird (such as pigeons and starlings) repellent and a repellent to mammals (such as beavers)

. The product is a very sticky, non-drying gel that acts as a tactile repe llent. When birds land on treated objects or surfaces, they are deterred by the sticky tactile sensation, tending not to return; beavers prefer gnawing on tree trunks that are not sticky. The physically tacky nature ofthis product provides the repellent action, which unlike many pesticide products is not intended to be ingested by the pest species to be effective. Physical and chemical characteristics of polybutene Polybutene, a copolymer of isobutene and n-butene, is the active ingredient serving as the tacti le component ofthe repellent product. It is a light-colored viscous liquid that is non-drying, with adhesive ortacky characteristics. The viscosity is proportional to its polymeric molecular weight (increasing as the polymeric chain lengthens). It is stable to light and is not reactive. Although it may soften in heat, once the product is 

### set, it does not liquefy and run at temperatures likely to be encountered in the outdoor or indoor environment. Polybutene is insoluble in water and has a specific gravity of 0.89 g/ml at

# 3rc. The boiling point is 160°C an·d

.·the vapor pressure is 0.13 mm Hg at 25oC. The active ingredient in the pesticide product is high ly viscous polybutene with a molecular weight greater than 1000 Daltons. Pesticidal Mode ofAction of Polybutene The pesticidal mode of action is mechanical in nature, producing an adhesive/sticky surface which upon contact discourages animals from roosting, perching, walking, or gnawing on treated surfaces. The contact is both brief and involves an extremely low surface area. No ingestion is requ ired. There is no chemica l reaction or interaction involved (or expected) in the use of polybutene as an active ingredient for current registered pesticide uses. Rationale for Exemption of Polybutene Section 408(p)(4) ofthe FFDCA authorizes EPA, by order, to exempt from the requirements of the screening program required by Section 408(p)(1) "a biologic substance or other substance if the Administrator determines that the substance is anticipated not to produce any effect in humans similar to an effect produced by a naturally occurring estrogen." The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP) held an open meeting on January 29-31, 2013 to discuss issues associated with prioritizing the universe ofchem icals considered underthe EDSP using computational toxicology tools which included the exemption of certain chemicals from EDSP screening on the basis oftheir physical and chemical properties. Specifically, the SAP made severa l recommendations concerning polymers that pertain to polybutene. "The Panel stated that there are several general reasons why certain compounds with inherent physico-chemical properties that are outside particular ranges will not be active as endocrine disrupters or be su itable for 

### in vitro testing. These reasons include: 1) 

### Some compounds are notbiologically available to cause effects in whole organisms, e.g., notsusceptible topassive transport or absorption due tophysico-chemical properties. Compounds that are not transported across a concentration gradient or · otherwise not absorbed due to physico-chemical properties will not be bioavai lable. These include molecular size (compounds that are too large are unable to migrate through membranes) or bulky, 

### i.e., the molecular dimensions in terms of breadth and width are too great). Compounds lacking in appropriate aqueous or lipid solubility w ill be unable to be absorbed"

... 

### Further, "Polymers with an average molecular weight >1,000 Daltons basedon its lack of ability to interact andbind to the ER, initiate the ER pathwayand initiate systemic effects are excluded; and,"
...

### "Exclusion of polymers. The Panel agreed that the exclusion of polymers from EDSP testing is justified for the most part. Such compounds are typically high molecular weight and subsequently, are likely to have limited bioavailability. The assumption that they will not triggerthe ER-alpha molecular initiating event (MIE) is reasonable. However, the Panel also noted that proteins and peptides, which are polymers, are able to influence estrogenic actions. Thus, the recommendation was made to more rigorously define the term "polymer" for the purposes of categorization. The exclusion of polymers should be reconsidered when prioritizing for other (MIEs)." The pesticide active ingredient, polybutene, is an insoluble organic polymer with a molecular weight >1000 Daltons that is highly stable. It is composed of only hydrogen and carbon, unlike biological polymeric macromolecules (e.g. proteins and nucleic acids). Polybutene for repellent uses is a viscous and tacky high molecular weight polymer such that systemic absorption _is extremely improbable. Based on the physical and chem ical characteristics alone, polybutene Registration Review case 4076 is not anticipated to produce in humans or any other organism an effect similar to that produced by a naturally occurring estrogen, androgen, or thyroid hormone. 

### Conclusion Based on the structure and physical nature ofthe isomer, polybutene is not anticipated to produce in humans or any other organism an effect similar to that produced by a naturally occu rring estrogen, androgen, or thyroid hormone.

Date: I James J. 1 V

ones

### Assistan**~** Administrator Office of Chemical Safety and Pollution Prevention

### References: US EPA, Scientific Advisory Panel MeetingJanuary 29-21, 2013: Prioritization ofthe Endocrine DisruptorScreening Program Universe ofChemicals for an Estrogen ReceptorAdverse Outcome Pathway Using Computational Toxicology Tools, SAP Minutes No. 2013-01, May 1, 3013, 98 pages. http://www.epa.gov/scipoly/sap/meetings/2013/january/012913minutes.pdf US EPA, Preliminary Environmental Fate and Ecological Risk Assessment in Support of Registration Review of Polybutene. Memorandum from F. Mastrota to J. Wolf. February 28, 2013. Supporting Materials. [EPA-HQ-OPP-2009-0649] U

.S Environmental Protection Agency, Washington DC. Accessed online at http://www.regulations.gov

. US EPA. Polybutene. Human Health Risk Assessment to Support Final Registration Review Decision. Memorandum from L. Hansen to 

### J. Wolf. June 13, 2012. Supporting Materials. [EPAHQ-OPP-2009-0649] U.S Environmental Protection Agency, Washington DC. 2013. Accessed online at http://www.regulations.gov

. US EPA. Administrative Order. Exemption ofAgrobacterium radiobacterstrains K84 and K1026 from the Requirements ofthe Endocrine Disruptor Screening Program. [EPA-HQ-OPP-2009- 0878] U.S Environmental Protection Agency, Washington, DC. Accessed online at http://www.regulations.gov

. US EPA. End Use Product Chemistry Review. Memorandum from I. Gairola to J. Gains dated May, 21, 2013. U.S Environmental Protection Agency, Washington, DC. US EPA. De Minimis Subgroup Opin ion on Polybutene Resins. Memorandum from Science Policy Panel/Risk Management Forum De Minimis Subgroup to J. Wolf dated January 4, 2013. [EPAHQ-OPP-2009-0878] U.S Environmental Protection Agency, Washington, DC. Accessed online at http://www.regulations.gov

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