UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D

.C

. 20460 

### JUN 07 

### 2012

MEMORANDUM OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION



### SUBJECT: BEAD Chemical Profile for Registration Review: Resmethrin (pC # 

### 097801) FROM: Nikhil Mallampalli, Entomologist 

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# rzBiological Analysis Branch

### ~ Jihad Alsadek, Economist 

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# ! 20 JZScience Information and Analysis Branch ElizabethHill,Economist,

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# "---J] Biological and Economic Analysis Division (7503P) THRU: Arnet Jones, Chief Biological Analysis Branc Diann Sims, Chief •

# {;~~ Science Information and Analysis Branch Timothy Kiely, Chief 

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# (0 Economic Analysis Branch 

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# U**l/("~** Biological and Economic Analysis Division (7503P) TO: Katherine StClair, Chemical Review Manager Risk Management and Implementation Branch 4 Pesticide Re-evaluation Division (7508P)


### ProductReview Panel date: December 7, 2011 INTRODUCTION The purpose ofthis document is to convey usage information and a broad overview ofthe pest management roles ofpesticides that are beginning to 

### undergo registration review. The anticipated audience consists ofthe team ofEPA staffcurrently evaluating the registration status ofresmethrin, and eventually the generalpublic. This document builds upon the data already Page 1 

### ofSprovided inthe "Usage and Label Use DataPackages" that are also providedto Registration Reviewteams by BEAD. The document is based on information and data available to BEAD as ofNovember 2011. Two chemicals are included in the Agency's "resmethrin" chemical review, resmethrin and bioresmethrin. Resmethrin was nrstregistered inthe u.s. in 1967, while bioresmethrin was first registered inthe U

.s. in 1973. Resmethrin and bioresmethrin are inthe same chemical review because oftheir very similar chemical structures anduse patterns. The rest ofthis document will refer to both chemicals under the term "resmethrin". Itunderwent Agency risklbenefIt review in 2006, when a Reregistration Eligibility Decision (RED) was issued (EPA 2006). BEADdid not conduct any formal benefits assessments for this RED. The Insecticide Resistance Action Committee (IRAC), comprised oftechnical personnel from various large agrochemical and public health companies, classifies resmethrin as a member of the 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, itis most toxic to the target pest oncontact, and has a quick "knockdown" effect, which is the initial paralysis and quick intoxication caused by nerve stimulation (DoulI1976). Resmethrin is sometimes formulated with a synergist compound, such as piperonyl butoxide (PBO) orMGK-264, to extend its active life and increase its toxic effect ontarget insects (Jones 1998). Itis also sometimes formulated with pyrethrins or synthetic pyrethroids for the same purpose. Resmethrin is currently classified as a restricted use chemical for wide area mosquito abatement. USE SITES Currently, resmethrin is registered for use onAthletic fields, Camp areas, Domestic dwellings (outdoor), Eating establishments (outdoor inedible), Industrial areas (outdoor), Livestockfeed lots, Marshes (surrounding vegetation-foliar treatment), Marshland (surrounding vegetation), Mosquito abatement districts, Municipalities Ornamental turf(golfcourses), Parks, Playgrounds, Ponds (surrounding vegetation), Recreational areas, Restaurants (outdoor), Roadsides, Shorelines, Stagnant pools (surrounding vegetation-foliar treatment), Stores (outdoor inedible), Swamps/marsheslbogs/standingwater (vegetation), Tidal marshes (surrounding vegetation), Urban outdoor, Warehouses (outdoor), Woodland

. areas, Zoos. All other uses have been voluntarily cancelled bythe registrant (Bayer). COMMON FORMULATIONS AND APPLICATION METHODS Resmethrin is formulated as soluble concentrate. The 2006 RED summarized application methods as follows: ApplicatlOIis [can be] made with hand held equipment such as ready-to-use spray containers, aerosol cans, thermal fog generators, electric foggers, backpack sprayers, and hand held sprayers. Applications are also made with aircraft and ground· equipment such as Page 2 ofStruck-mounted [ultra-low volume (ULV)] sprayers." The RED eliminated use ofresmethrin in residential products intended for use with indoor metered spray systems and automatic misting systems. All other application methods described above remain on current resmethrin labels.


### USAGE BEAD has very limited information onthe use ofresmethrin. Usage for mosquito abatement ranged from 17,000 lbs in 2003 to 34,000 lb in 2005. A small amount ofresmethrin use has also beenreported for containerized nursery applications. There was less than 100 lbs. ofresmethrin used in 2002 innurseries and greenhouses (Kline and Company, Inc. 2003-2005). Itis not clear what the most commonly used application rates or frequencies are for resmethrin. 

### BIOLOGICALASPECTS RELEVANT TO RESMETHRIN Resmethrin is one ifseveral synthetic pyrethroids thatwere commercially developed early in the history ofthis class ofinsecticides (Casida 1980, Wickham 1995). It is one ofa group ofolder pyrethroids that are used in "muchthe same manner as pyrethrum extract", the crude mixture of pyrethrins that is derived from chrysanthemum flowers (Casida 1980). As such, resmethrin is "highly insecticidal but not [environmentally] persistent enough for [outdoor] agricultural use" (Casida 1980). Resmethrin, like cismethrin and D-phenothrin (aka sumithrin) has "poor stability

. in sunlight" but continues to playarole as an indoor space spray option for controlling urban pests such as cockroaches (Wickham 1995). It continues to be one ofa small set ofinsecticides recommended by some state-level experts for suppressing populations ofadult mosquitoes (Brattsten and Hamilton 2011). Interestingly, beekeepers dealing with infestations ofAmerican foulbrood (Paenibacillus larvae), a bacterial disease, sometimes have had to depopulate the colony with an over-thecounter formulation ofresmethrin, applied with aerosol spray cans (synthetic pyrethroid) (USDA 2004,2006). No otherpesticide appears to berecommended for this purpose, although other control strategies, such as treatment ofhives with an antibiotic such as terramycin, are among recommended options (USDA 2004, 2006). Note that this use is no longer possible since overthe-counter products have been cancelled bythe registrant. A search ofthe database on arthropods resistant to pesticides (maintained online by Michigan State University and accessible at www.pesticideresistance.org) indicates that many insects have evolved resistance to resmethrin (formulated with and without synergists) overthe many years that the products have been inuse. The list is diverse, covers both cases within and outside the U.S., and includes urban pests such as German cockroaches and houseflies, as well as widespread agricultural and stored commoditypests such as the the diamondback moth (Plodia interpuncte/la) and red flour beetle (Tribolium castaneum). BEAD's initial assessment, based on a scan ofthe literature mentioned inthe database and other internet accessible sources, is that such resistance has not become consistently widespread inthe U.S.; rather, itdevelops repeatedly in isolated instances-.

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### mSTORY OF BEAD ASSESSMENTS FORRESMETHRIN In 2005 and 2006, the California Environmental Protection Agency, Department ofPesticide Regulation (CADPR) requested a Public Health Exemption for the use ofresmethrin on all crops grown inthe state except for almonds, pasture, rice, and walnut to control for mosquitoes vectoring the West Nile virus (see Attachment 1). In bothyears Californiawas granted use- of resmethrin for this purpose, as the rapid spread ofthe West Nile virus coupled with the lack of effective aerially applied insecticides for adult mosquito control resulted in an urgent, nonroutine situation. Resmethrin is currently registered for use as a wide area mosquito abatement insecticide. No other assessments for resmethrin have been conducted by BEAD. In addition, according to the EPA's Official Section 18 Action Database, no other emergency exemptions have been issued for this chemical (EPA, 2011).


### INFORMATION THAT MAY BE USEFUL FORBEAD'S FUTURE WORK ON RESMETHRIN Obtaining additional information onthe following items would improve future BEAD assessments ofthe importance ofresmethrin and may be required as part ofthe registration review ofthis pesticide. Usage data (ideally, in GIS-mappable format) onrecent (post 2006) use ofresmethrinas a mosquito adulticide. 

### REFERENCES: Brattsten, L.B. and G.C. Hamilton. 2011. Insecticides**Reco~ended** for Mosquito Control in NewJersey in 2011. NewJersey Agricultural Experiment Station PublicationNo. P08001-01-11. Casida. J. 1980. Pyrethrum Flowers and Pyrethroid Insecticides. Environmental Health Perspectives Vol. 34, pp. 189-202. Doull, J. 1976. The Treatment ofInsecticide Poisoning. Ch. 16 in: C.F. Wilkinson (ed.),

- Insecticide Biochemistry and Physiology. 753 pp. Plenum Press, New York. EPA. 2006. Reregistration Eligibility Decisionfor Resmethrin. Available at http://wWw.epa

.gov/oppsrrdlIREDs/resmethrin red.pdf

. [Accessed November 16,2011]. Environmental Protection Agency (EPA). 2011. Section 18 Action Database. Located at: http://cfpub1.epa.gov/oppref/section18/search.cfm.

Page 4 of5Jones, D.G (ed.). 1998. Piperonyl Butoxide: The Insecticide Synergist. 323 pp. Academic Press, San Diego, CA. Kline and Company, Inc. 2002-2005. 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. USDA. 2004. Crop Profile for Honey Bees inNewJersey. Available on the web at www.ipmcenters.org [Accessed November 16,2011]. USDA. 2006. Crop Profile for Honey in Virginia. Available onthe web at www.ipmcenters.org [AccessedNovember 16,2011]. Wickham, J.C. 1995. Conventional Insecticides. 

### In: Understanding and Controlling the German Cockroach

. M.K. Rust, lM. Owens, and D.A. Reierson (eds). 430 pp. Oxford Univ. Press, NewYork.



### ATTACHMENT 1 EPA Section 18 Actions for Resmethrin**~** ""**al!B~e** 

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### Date Date**seS§n!.ents, ~**  

### ff@o..tmuefed VARIOUS MOSQUITO CALIFORNIA 9/12/2005 7/1112006 ISSUED 321734 VARIOUS ' MOSQUITO CALIFORNIA 5/1112006 7/1112006 ISSUED Source: EPA (2011); BEAD OffiCIal Records.

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