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 Nt t U ~ 1'2../ 't OS / '1...() I r 

Biological Analysis Branch .:----

THRU: 

TO: 

Sepehr Haddad, Environmental Protection Specialist;/!AAd f.v f ~ ~ Science Information and Analysis Branch tiT 0'--1.-

Elizabeth Hill, Economist I 

Economic Analysis Branch 1 z-r 7 g 7. a I , 

Biological and Economic Analysis DivIsIon 

Arnet Jones, Chief /I tAU;: ' 

Biological Analysis Branch ~"'! . 

Diann 

Science 

Sims, 

Information 

Chief 

and ~y~~ 

i!JAhJJ 

Branch 

A ~ ~ 

Timothy Kiely, Chief --rtf tU,oJ;I- ZB )}.CLN(,if 2of( 

Economic Analysis Branch rJ f.:>r -t.1tI t,".e~ 

Biological and Economic Analysis Division (7503P) (J 

Wilhelmina Livingston, Chemical Review Manager 

Risk Management and Implementation Branch 4 

Pesticide Reevaluation Division (7508P) 

Product Review Panel date: November 16, 2011 

INTRODUCTION 

The purpose of this document is to convey usage information and a broad overview of the pest 

management roles of pesticides that are beginning to undergo registration review. The 

anticipated audience consists of the team of EPA staff currently evaluating the registration status 

of prallethrin, and eventually the general public. This document builds upon the data already 

provided in the "Usage and Label Use Data Packages" that are also provided to Registration 

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Review teams by BEAD. The document is based on infonnation and data available to BEAD as 

of November 2011. 

Prallethrin was first registered in 1994. Registration review is the first time the Agency is reassessing prallethrin risks and benefits. 

The Insecticide Resistance Action Committee (IRAC), comprised of technical personnel from 

various large agrochemical and public health companies, classifies prallethrin as a member of the 

Mode of Action Group 3 (subgroup 3A). This group of insecticides acts as sodium channel 

modulators, thus causing disruption of nerve impulses in the 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 of pyrethrum, it is 

most toxic to the target pest on contact, and has 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 combination with other synthetic pyrethroid. For example, the 

product Duet ® consists ofprallethrin, PBO, and D-phenothrin (aka sumithrin). This product is 

among a small set recommended as a mosquito adulticide by 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) or U.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 

other urban pests, available for both homeowners and pest control operators, in which prallethrin 

is a component of a mixture containing other pyrethroids and/or a synergist (for example, the 

Duet brand mentioned earlier). 

COMMON FORMULATIONS AND APPLICATION METHODS 

Prallethrin is fonnulated as pressurized liquid and gas, soluble and emulsifiable concentrate. It 

may be fonnulated alone or in mixtures with other pyrethroids, as mentioned earlier. BEAD 

speculates that homeowner products are probably most often applied as pre-mixed pressurized 

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aerosol sprays. Application methods include crack and crevice, spot, space and general surface 

treatments indoors and outdoors. Space spray indoors can include misters/foggers. 

Pressurized products 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 of non-agricultural data available to BEAD (Kline & Co.) did not report any 

usage of prallethrin in their published reports. However, the company did prepare a special 

study in 2006 for EPA which estimated non-agricultural usage of prallethrin for households to be 

approximately 28,000 lbs. This study probably 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 and Fertilizers Study conducted in 2006 for EPA 2006). 

BIOLOGICAL ASPECTS RELEVANT TO PRALLETHRIN 

Due perhaps to its relatively recent registration and commercialization (at least in the United 

States), pest insect resistance to prallethrin has apparently not been reported in the scientific 

literature, for either the U.S.A. and globally. For example, the Arthropod Pesticide Resistance 

Database maintained by Michigan State University (on the web at 

http://www.pesticideresistance.orgD states that "no resistance has been reported" for this 

insecticide: BEAD's search of the accessible technical literature (primarily the referredjoumals 

published by the Entomological Society of America) also did not show any reports of resistance 

to prallethrin. While cross-resistance stemming from the development of resistance to another 

synthetic pyrethroid is certainly plausible, since all have the same mode of action, it is not clear 

to BEAD exactly how quickly or widely such a phenomenon might spread if and when it 

develops. 

Regarding the utility of prallethrin 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 thought to have a strong excitatory component .... 

These properties make prallethrin a good candidate as a flushing agent." Chemicals that, at sublethal levels, irritate target insects enough to make them 'move about are often called "flushing 

agents." This property is useful in adult mosquito control because it increases the exposure of 

the insects to insecticide spray droplets (Cooperband et al. 2010). 

HISTORY OF BEAD ASSESSMENTS FOR PRALLETHRIN 

To date, BEAD has not conducted any assessments for prallethrin. In addition, according to the 

EP A's Official Section 18 Action Database, no emergency exemptions have been issued for this 

chemical (EPA, 2011). 

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INFORMATION THAT MAY BE USEFUL FOR BEAD'S FUTURE WORK ON 

PRALLETHRIN 

Obtaining additional infonnation on the following items would improve future BEAD 

assessments of the importance of prallethrin and may be required as part of the registration 

review of this pesticide. 

1) Usage data (pounds AI applied, application methods frequently used, and area treated) for 

indoor/outdoor consumer use, use in food handling establishments/food processing 

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 of application, pounds AI applied) on use of 

prallethrin as a mosquito adulticide. 

REFERENCES 

Brattsten, L.B. and G.C. Hamilton. 2011. Insecticides Recommended for Mosquito Control in 

New Jersey in 2011. New Jersey Agricultural Experiment Station Publication No. 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 wind tunnel. 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 on Nervous Conduction and Synaptic Transmission. 

Ch. 9 in: C.F. Wilkinson (ed.), Insecticide Biochemistry and Physiology. 753 pp. Plenum 

Press, New York. 

Environmental Protection Agency (EPA). 2011. Section 18 Action Database. Located at: 

http://cfpubl.epa.gov/oppref/sectionI8/search.cfm. 

Kline & Co., 2006. 

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