UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C

. 20460


## DEC 28 2011

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION MEMORANDUM



### SUBJECT: BEAD Chemical Profile for Registration Review: Prallethrin (PC # 128722) FROM: Nikhil Mallampalli, Entomologist 

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### TO: Sepehr Haddad, Environmental Protection Specialist;/!AAd

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### ~y~~ Branch Timothy Kiely, Chief 

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### rJ f.:>r -t.1tI**t,".e~** Biological and Economic Analysis Division (7503P) (J WilhelminaLivingston, Chemical Review Manager Risk Management and Implementation Branch 4 Pesticide Reevaluation Division (7508P)



### ProductReview Panel date: November 16, 2011 

### INTRODUCTION The purpose ofthis document is to convey usage information and a broad overview ofthe pest managementroles ofpesticides that are beginning to undergo registration review. The anticipated audience consists ofthe team ofEPA staffcurrently evaluating the registration status ofprallethrin, and eventually the general public. This documentbuilds upon the data already provided inthe "Usage and Label Use Data Packages" that are also providedto Registration Page 

### 1 of4Review teams by BEAD. The document is based on infonnation and data available to BEAD as ofNovember 2011. Prallethrin was first registered in 1994. Registrationreview is the first time the Agency is reassessing prallethrinrisks andbenefits. The Insecticide Resistance Action Committee (IRAC), comprised oftechnical personnel from various large agrochemical and public health companies, classifies prallethrin as a member ofthe Mode ofAction Group 3 (subgroup 3A). This group ofinsecticides acts as sodium channel modulators, thus causing disruption ofnerve impulses inthe target insects. All pyrethroids "initially stimulate nerve to produce repetitive discharges and subsequently cause paralysis" (Narahashi, 1976). Like other compounds derived from the chemical structure ofpyrethrum, it is mosttoxic to the targetpest oncontact, andhas a quick "knockdown" effect, which is the initial paralysis and quick intoxication caused by nerve stimulation (Doull 1976). In at least some products, prallethrin is fonnulated with a synergist (e.g. piperonyl butoxide, also known as PBO) alone or in combinationwith other synthetic pyrethroid. Forexample, the product Duet 

### ® consists ofprallethrin, PBO, and D-phenothrin (aka sumithrin). This product is among a small set recommended as a mosquito adulticideby Rutgers University (Brattsten and Hamilton 2011). Prallethrin is also available as a mixture containing other pyrethroids (e.g., esfenvalerate) without a synergist.



### USE SITES Agricultural Use Sites There are no agricultural uses, international tolerances (CODEX) orU.S. Maximum Residue Limits (MRLs) for prallethrin. However, there is a food tolerance of 1.0 ppm established in or on food commodities in U.s. food handling establishments where food and food products are held, processed, prepared, or served. Non-Agricultural Use Sites Non-agricultural sites include food handling establishments, storage areas, grain elevators, tobacco warehouses, canneries, commerciallinstitutional!industrial areas, domestic dwellings, factories, farm buildings, animal treatment, hospitals, manufacturing plants, office buildings, among others. There are also several products intended to control mosquitoes, cockroaches and otherurban pests, available for bothhomeowners and pest control operators, in which prallethrin is a component ofa mixture containing otherpyrethroids and/or a synergist (for example, the Duetbrandmentioned earlier). 

### COMMONFORMULATIONS AND APPLICATION METHODS Prallethrin is fonnulated as pressurized liquid and gas, soluble and emulsifiable concentrate. It may be fonnulated alone orin mixtures with otherpyrethroids, as mentioned earlier. BEAD speculates thathomeownerproducts are probably most often applied as pre-mixed pressurized Page 2 of4aerosol sprays. Application methods include crack and crevice, spot, space and general surface treatments indoors and outdoors. Space spray indoors can include misters/foggers. Pressurizedproducts for prallethrin are used fqr general insect control and in wasp and hornet sprays. Wide-area application for mosquito control is by ground or aircraft spray equipment. USAGE Typical sources ofnon-agricultural data available to BEAD (Kline & Co.) did notreport any usage ofprallethrin intheirpublished reports. However, the company did prepare a special study in 2006 for EPAwhich estimated non-agricultural usage ofprallethrin for households to be approximately 28,000 lbs. This studyprobably underestimates non-agricultural use since it does not include any non-household sites, such as food handling establishments and warehouses, etc. (Kline & Co., Household and Houseplant Insecticide Active Ingredients from a Consumer Markets for Pesticides andFertilizers Study conducted in 2006 for EPA 2006).

BIOLOGICALASPECTS RELEVANT TO PRALLETHRIN Due perhaps to its relatively recentregistration and commercialization (at least in the United States), pest insect resistance to prallethrin has apparently not been reported inthe scientific literature, for eitherthe U.S.A. and globally. For example, the Arthropod Pesticide Resistance Database maintainedby Michigan State University (on the web at http://www.pesticideresistance.orgD states that "no resistance has been reported" for this insecticide: BEAD's search ofthe accessible technical literature (primarily the referredjoumals publishedby the Entomological Society ofAmerica) also did not show any reports ofresistance to prallethrin. While cross-resistance stemming from the development ofresistance to another synthetic pyrethroid is certainly plausible, since all have the same mode ofaction, it is not clear to BEAD exactly howquickly orwidely such a phenomenonmight spread ifand when it develops. Regarding the utility ofprallethrin as a control option for mosquito adults, Cooperband et al. (2010) state that "prallethrin is a relatively volatile pyrethroid with repellent properties against mosquitoes. Moreover, this pyrethroid is thoughtto have a strong excitatory component
.... These properties make prallethrin a good candidate as a flushing agent." Chemicals that, at sublethal levels, irritate target insects enoughto make them' move about are often called "flushing agents." This property is useful in adult mosquito control because it increasesthe exposure of the insects to insecticide spray droplets (Cooperband et al. 2010). HISTORY OF BEAD ASSESSMENTS FORPRALLETHRIN To date, BEAD has not conducted any assessments for prallethrin. In addition, according to the EPA's Official Section 18 Action Database, no emergency exemptions have been issued for this chemical (EPA, 2011).

Page 3 of4INFORMATION THAT MAY BE USEFUL FORBEAD'S FUTURE WORK ON PRALLETHRIN Obtaining additional infonnation onthe following items would improve future BEAD assessments ofthe importance ofprallethrin and may be required as part ofthe registration review ofthispesticide. 1) Usage data (pounds AI applied, application methods frequently used, and areatreated) for indoor/outdoor consumer use, use in food handling establishments/foodprocessing establishments, and use in and around commercial and institutional facilities. 2) Usage data (pounds AI applied, application methods frequently used, and area treated) for structural treatment at agricultural and commodity-processing facilities. 3) GIS-mappable data (e.g., frequency ofapplication, pounds AI applied) onuse of prallethrin as a mosquito adulticide.
REFERENCES Brattsten, L.B. and G.C. Hamilton. 2011. Insecticides Recommended for Mosquito Control in NewJersey in 2011. NewJersey Agricultural Experiment Station PublicationNo. P08001-01-11. Cooperband, M.F., F.V

. Golden, G.G. Clark, W. Jany, and S.A. Allan. 2010. Prallethrin-Induced excitation increases contact between sprayed ultralow volume droplets and flying mosquitoes (Diptera: Culicidae) in a windtunnel. J. Med. Entomol. 47(6): 109?-1106. Doull, J. 1976. The Treatment ofInsecticide Poisoning. Ch. 16 in: C.F. Wilkinson (ed.), Insecticide Biochemistry and Physiology

. 753 pp. Plenum Press, New York. Narahashi, T. 1976. Effects ofInsecticides onNervous Conduction and Synaptic Transmission. Ch. 9 in: C.F. Wilkinson (ed.), Insecticide Biochemistry and Physiology. 753 pp. Plenum Press, New York. Environmental ProtectionAgency (EPA). 2011. Section 18 Action Database. Located at: http://cfpubl.epa.gov/oppref/sectionI8/search.cfm. Kline & Co., 2006.

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