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OFFICE OF

CHEMICAL SAFETY AND

POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

PC Code: 128722

DP Barcode: D396740

MEMORANDUM April 17, 2012

SUBJECT: Registration Review: Preliminary Problem Formulation for Environmental Fate, 

Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments 

for Prallethrin

TO: Wilhelmena Livingston, Chemical Review Manager

Eric Olson, Risk Manager 

Risk Management and Implementation Branch IV

Pesticide Re-evaluation Division (7508P)

FROM: Robin Sternberg, Ph.D., Wildlife Biologist

He Zhong, Ph.D., Biologist

Environmental Risk Branch I

Environmental Fate and Effects Division (7507P)

REVIEWED

BY: Stephen Wente, Ph.D., Biologist

Edward Odenkirchen, Ph.D., Senior Eco Scientist

Environmental Risk Branch I

Environmental Fate and Effects Division (7507P)

APPROVED

BY: Nancy Andrews, Ph.D., Branch Chief

Sujatha Sankula, Ph.D., Lead Biologist

Environmental Risk Branch I

Environmental Fate and Effects Division (7507P)

The Environmental Fate and Effects Division (EFED) has completed the preliminary problem 

formulation (attached) for the environmental fate, ecological risk, endangered species, and 

drinking water exposure assessments to be conducted as part of the Registration Review of the 

synthetic pyrethroid prallethrin ((S)-2-methyl-4-oxo-3-(2-propynyl) cyclopent -2-enyl (1RS)-cis, 

trans-2,2 -dimethyl -3-(2-methylprop-1-enyl) cyclopropanecarboxylate; CAS no. 23031-36-9; 

PC Code 128722). Functioning as the first stage of the risk assessment process for Registration 

Review, this problem formulation provides an overview of what is currently known about the 
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environmental fate and ecological effects associated with prallethrin and its degradates. It also 

describes the preliminary ecological risk hypothesis and analysis plan for evaluating and 

characterizing risk to non-target species in support of the registration review of prallethrin. This 

document also recommends studies that should be included in a generic data call-in (DCI) to 

address uncertainties surrounding the environmental fate and potential ecological effects of 

prallethrin.
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Problem Formulation for the Environmental Fate, Ecological Risk, 

Endangered Species, and Drinking Water Exposure Assessments in 

Support of the Registration Review of Prallethrin

(S)-2-methyl-4-oxo-3-(2-propynyl) cyclopent -2-enyl (1RS)-cis, trans-2,2 -

dimethyl -3-(2-methylprop-1-enyl) cyclopropanecarboxylate

CAS Registry Number: 23031-36-9

PC Code: 128722

Prepared by:

Robin Sternberg, Ph.D., Wildlife Biologist

He Zhong, Ph.D., Biologist

U.S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch I

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington, DC 20460

Reviewed by:

Stephen Wente, Ph.D., Biologist

Edward Odenkirchen, Ph.D., Senior Eco Scientist

William Eckel, Ph.D., Senior Science Advisor

Amanda Solliday, Biologist

April 17, 2012
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Table of Contents

1. Purpose....................................................................................................................................... 6

2. Nature of Regulatory Action...................................................................................................... 6

3. Conclusions from Previous Assessments................................................................................... 7

3.1 Ecological Risk Assessments............................................................................................... 7

3.2 Drinking Water Exposure Assessments............................................................................... 8

4. Stressor Source and Distribution ............................................................................................... 9

4.1 Mechanism of Action........................................................................................................... 9

4.2 Overview of Pesticide Use and Usage ................................................................................. 9

4.2.1 Labeled Uses.................................................................................................................. 9

4.2.2 Prallethrin Use with Synergists.................................................................................... 10

4.2.3 Environmental Mixtures .............................................................................................. 11

4.2.4 Usage............................................................................................................................ 11

4.3 Environmental Fate and Transport..................................................................................... 12

4.3.1 Photodegradation ......................................................................................................... 12

4.3.2 Aerobic Degradation.................................................................................................... 12

4.3.3 Anaerobic Degradation ................................................................................................ 13

4.3.4 Adsorption/Desorption and Leaching.......................................................................... 13

4.3.5 Terrestrial and Aquatic Field Dissipation.................................................................... 13

4.3.6 Bioconcentration in Fish.............................................................................................. 14

4.4 Degradates of Concern....................................................................................................... 17

4.5 Water Quality..................................................................................................................... 17

5. Receptors.................................................................................................................................. 18

5.1 Effects to Aquatic Organisms............................................................................................ 19

5.2 Effects to Terrestrial Organisms........................................................................................ 22

5.3 Incident Databases Review................................................................................................ 25

5.4 Ecosystems Potentially at Risk .......................................................................................... 25

6. Assessment Endpoints ............................................................................................................. 26

7. Conceptual Model.................................................................................................................... 27

7.1 Risk Hypothesis................................................................................................................. 27

7.2 Conceptual Diagrams......................................................................................................... 27

7.2.1 Drinking Water Exposure ............................................................................................ 29

7.2.2 Inhalation Exposure ..................................................................................................... 29

8. Analysis Plan ........................................................................................................................... 30

8.1 Stressors of Concern .......................................................................................................... 30

8.2 Measures of Exposure........................................................................................................ 31

8.2.1 Spray Drift ................................................................................................................... 31

8.2.2 Aquatic Exposure......................................................................................................... 31

8.2.3 Terrestrial Exposure..................................................................................................... 33

8.3 Measures of Effect ............................................................................................................. 34

8.4 Integration of Exposure and Effects .................................................................................. 35

8.5 Deterministic and Probabilistic Assessment Methods....................................................... 35

8.6 Endangered Species Assessments...................................................................................... 35

8.7 Drinking Water Assessment .............................................................................................. 36

8.8 Endocrine Disruptor Screening.......................................................................................... 36
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9. Preliminary Identification of Data Gaps.................................................................................. 37

9.1 Environmental Fate Data ............................................................................................... 37

9.2 Ecological Effects Data.................................................................................................. 39

10. References.............................................................................................................................. 45

Appendix A................................................................................................................................... 52

Appendix B................................................................................................................................... 54

Appendix C................................................................................................................................... 63

Appendix D................................................................................................................................... 71

Appendix E ................................................................................................................................... 74

Appendix F.................................................................................................................................... 76
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1. Purpose

The purpose of this problem formulation is to provide an understanding of the environmental fate 

and ecological effects of prallethrin for registered uses. Prallethrin ((S)-2-methyl-4-oxo-3-(2-

propynyl) cyclopent -2-enyl (1RS)-cis, trans-2,2 -dimethyl -3-(2-methylprop-1-enyl) 

cyclopropanecarboxylate; CAS no. 23031-36-9; PC Code 128722) is a synthetic pyrethroid that

modulates voltage-sensitive sodium channels causing disruption of nerve impulses in target insects. 

It is a broad spectrum, non-systemic insecticide used to control adult nuisance insects (e.g., 

mosquitoes, midges, gnats, black flies, etc.). Formulations of prallethrin often contain additional 

active ingredients including one or two synergists. Mosquito control applications include aerial 

and ground ultra low volume (ULV) applications in residential, commercial, and recreational 

areas. Other applications include space and crack-and-crevice treatment for structure protection 

in a variety of commercial, industrial, residential, and institutional sites; foliar and fogger 

treatment on non-food plants; and direct application to cats, dogs, and horses. There are no

registered crop uses of prallethrin, and this may potentially reduce the environmental loading.

This document provides a plan for analyzing data relevant to prallethrin and for conducting 

environmental fate, ecological risk, endangered species, and drinking water exposure 

assessments for its registered uses. Additionally, this problem formulation identifies data gaps, 

uncertainties, and assumptions that will be used to address those uncertainties relative to 

characterizing the potential ecological risk associated with the registered uses of prallethrin.

2. Nature of Regulatory Action

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), all pesticides distributed 

or sold in the United States generally must be registered by the Environmental Protection 

Agency (Agency). In determining whether a pesticide can be registered in the U.S., the Agency

evaluates its safety to non-target species based on a wide range of environmental and health 

effects studies. In 1996, FIFRA was amended by the Food Quality Protection Act, and the 

Agency was mandated to implement a new program for the periodic review of pesticides, i.e., 

Registration Review (http://www.epa.gov/oppsrrd1/registration_review/). The Registration 

Review program is intended to ensure that, as the ability to assess risk evolves and as policies 

and practices change, all registered pesticides continue to meet the statutory standard of no 

unreasonable adverse effects to human health and the environment. Changes in science, public 

policy, and pesticide use practices will occur over time. Through the Registration Review 

program, the Agency periodically reevaluates pesticides to make sure that as change occurs, 

products in the marketplace can be used safely. 

As part of the implementation of the Registration Review program pursuant to Section 3(g) of 

the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), the Agency is beginning its 

evaluation of prallethrin to determine whether it continues to meet the FIFRA standard for 

registration. This problem formulation for the environmental fate, ecological risk, endangered 

species, and drinking water assessment chapter in support of the registration review of prallethrin

will be posted in the initial docket which will initiate the public phase of the review process.
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3. Conclusions from Previous Assessments

3.1 Ecological Risk Assessments

Prallethrin was first registered in the United States in 1994 for indoor use to control adult 

nuisance insects. Since then, EFED has conducted several ecological risk assessments for 

prallethrin (see Appendix A). A 1997 assessment to evaluate prallethrin use at 0.00025 to 0.002 

lb a.i./A to control adult nuisance insects in domestic outdoor and forestry sites concluded that 

the uses posed minimal risk to terrestrial organisms from acute and chronic exposure and 

minimal risk to aquatic organisms from acute exposure; the lack of fish early-life stage and 

aquatic invertebrate life cycle tests created uncertainty regarding risk to aquatic organisms from 

chronic exposure (D219740, D217877). In 1999, a Section 3 assessment for the use of 

prallethrin in food-handling establishments for all commodities concluded that the use posed

little or no risks to listed and non-listed terrestrial and aquatic organisms (D259553, D239124). 

The most recent prallethrin assessments were conducted from 2003 to 2005 and evaluated a 

prallethrin typical end-use product (TEP), MULTICIDE Fogging Concentrate 2798 (Reg No. 

1021-1795), for use in outdoor residential and recreational areas to control adult nuisance insects 

(D257595, D291569, D239293, D301123, D312733). Collectively, these assessments made the 

following final risk conclusions regarding MULTICIDE Fogging Concentrate 2798 as applied 26 

times (with 7-day intervals) at a rate of 0.0008 lb a.i./A:

 Use is not likely to pose risk to birds or mammals (including listed species) from acute or 

chronic exposure. 

 Given the high toxicity of prallethrin to honey bees and prallethrin’s proposed use to 

control adult insects, there is a potential for adverse effects to listed species of flying 

insects (e.g., butterflies). 

 Risk to non-target aquatic and terrestrial plants as a result of use could not be evaluated 

due to lack of submitted studies.

 Given its aquatic half-life, prallethrin is likely to occur in the water column and sediment. 

 Use is not likely to pose risk to freshwater or estuarine/marine organisms (including 

sediment-dwelling organisms) from acute exposure regardless of depth of water body. 

Risk to terrestrial and aquatic ecosystems will be reevaluated based on the availability of new 

data and refined models. 

The following outstanding data requirements were identified in the 2003-2005 assessments: 

 850.1035/72-3(c): Acute Estuarine/Marine Shrimp Toxicity with TEP MULTICIDE

Fogging Concentrate 2798 (Reg No. 1021-1795); 

 850.1735: Whole Sediment: Acute Freshwater Invertebrates with technical grade active 

ingredient with technical grade active ingredient (TGAI); 

 850.3030/141-2: Honeybee Toxicity of Residues on Foliage with TEP MULTICIDE 

Fogging Concentrate 2798 (Reg No. 1021-1795); 

 850.4100/122-1(a): Seedling Emergence, Tier I with TEP MULTICIDE Fogging 

Concentrate 2798 (Reg No. 1021-1795)

 850.4150/122-1(b): Vegetative Vigor, Tier I with TEP MULTICIDE Fogging 

Concentrate 2798 (Reg No. 1021-1795); and 
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 122-2: Aquatic Plant Growth, Tier I with TEP MULTICIDE Fogging Concentrate 2798 

(Reg No. 1021-1795). 

These studies have since been submitted by the registrant, evaluated by EFED, and classified as 

acceptable (MRIDs 47431601, 47762401, 48055901, 47431602, 47431603, and 48055902, 

respectively). 

The 2003-2005 assessments identified the following studies as data uncertainties but did not 

request them at that time:

 850.1010/72-2(b): Acute Toxicity Freshwater Invertebrate with TEP MULTICIDE 

Fogging Concentrate 2798 (Reg No. 1021-1795);

 850.1075/72-1(b): (Acute) Freshwater Fish Toxicity (Bluegill) with TEP MULTICIDE

Fogging Concentrate 2798 (Reg No. 1021-1795);

 850.1075/72-1(c) or: Acute Freshwater Fish Toxicity (Rainbow Trout) with TEP 

MULTICIDE Fogging Concentrate 2798 (Reg No. 1021-1795);

 850.1075/72-3(a): Acute Estuarine/Marine Fish Toxicity with TEP MULTICIDE

Fogging Concentrate 2798 (Reg No. 1021-1795); and

 850.1075/72-3(b): Acute Estuarine/Marine Mollusk Toxicity with TEP MULTICIDE

Fogging Concentrate 2798 (Reg No. 1021-1795).

The 2003-2005 assessments identified the following studies as data uncertainties that should be 

required if new uses are added for prallethrin:

 850.1350/72-4(b): Estuarine/Marine Invertebrate Life Cycle with TGAI;

 850.1500/72-5: Fish Life Cycle (Freshwater & Saltwater) with TGAI; and

 850.1740: Whole Sediment: Acute Marine Invertebrates with TGAI pending test results

using the amphipod Hyallella azteca.

Finally, the 2003-2005 assessments waived all testing with the major degradates of prallethrin,

ketolone, PGLS, and keto-PGLS. EFED determined that these degradates are the outcome of 

cleavage of the ester linkage of the parent. This breaking of the basic pyrethroid frame or 

backbone may result in lost activity and thus decreased toxicity when compared with the parent. 

3.2 Drinking Water Exposure Assessments

The drinking water assessment (DWA) for MULTICIDE® Fogging Concentrate 2798 (Reg No. 

1021-1795) was completed in June 2003 (DP 274758) to estimate prallethrin environmental 

concentrations. Tier I FIRST 1.0 and SCIGROW 2.2 models were used to estimate prallethrin 

concentrations in surface water and groundwater, respectively (USEPA, 2003). The results of 

this DWA are summarized in Table 3-1.
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Table 3-1. Estimation of Prallethrin Concentrations in Surface Water and Groundwater 

Using FIRST 1.0 and SCIGROW 2.2, Respectively, for a June 2003 DWA

Product Application Rate 

(lb a.i./A)

Acute (peak) Surface 

Water Concentration 

(ppt)

Annual Average 

Surface Water 

Concentration 

(ppt)

Ground Water 

Concentration 

(ppt)

MULTICIDE®0.0008 236 15.0 0.41

RESPONDÉ®0.002 591 37.5 1.04

ppt = parts per trillion

These values generally represent upperbound estimates of the concentrations that might be found 

in surface water and groundwater as a result of prallethrin outdoor usage at the maximum 

application rate. Both models provide estimates suitable for screening purposes. The drinking 

water exposure may be reassessed if it is deemed necessary. 

4. Stressor Source and Distribution

4.1 Mechanism of Action

Prallethrin is a member of a class of pesticides known as synthetic pyrethroids. Pyrethroids are 

synthetic chemicals that were originally developed as modifications of the natural pyrethrum 

structure to produce compounds that had an increased photo-stability while retaining insecticidal 

activity and low acute mammalian toxicity. Prallethrin has been assigned to the Mode of Action 

Group 3 (subgroup 3A) by the Insecticide Resistance Action Committee (IRAC) 

(http://www.irac-online.org/teams/mode-of-action/) which is comprised of technical personnel 

from various large agrochemical and public health companies (USEPA, 2011). Insecticides in 

this group modulate sodium channels and thus cause disruption of nerve impulses in the target 

insects. All pyrethroids "initially stimulate the nerve to produce repetitive discharges and 

subsequently cause paralysis" (Narahashi, 1976). Like other compounds derived from the 

chemical structure of pyrethrum, pyrethroids are most toxic to the target pest on contact and have

a quick "knockdown" effect that is characterized by quick intoxication and initial paralysis 

resulting from nerve stimulation (Doull, 1976).

4.2 Overview of Pesticide Use and Usage

4.2.1 Labeled Uses

Prallethrin is used to control adult nuisance insects (e.g., mosquitoes, midges, gnats, black flies, 

etc.) and is not registered for crop uses according to a recent report by the Biological and 

Economic Analysis Division (BEAD) of the Office of Pesticide Programs (OPP) (USEPA,

2011). Non-crop use sites include farm buildings, factories, food handling, storage areas, grain 

elevators, tobacco warehouses and canneries, domestic dwellings, commercial/institutional/

industrial areas, hospitals, manufacturing plants, office buildings, etc. (USEPA, 2011). In 2005, 

prallethrin was registered for use in mosquito adulticide programs involving outdoor residential 
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and recreation areas, and in vegetation surrounding parks, woodlands, swamps, marshes, 

overgrown areas and golf courses. 

Seventy-six (76) labels are currently registered for use in the United States: fourteen (14) 

technical or formulation intermediate products and sixty-two (62) formulated end-use products

(see Appendix B). Prallethrin is often available in a mixture containing other pyrethroids (e.g., 

cyfluthrin, cypermethrin, cyphenothrin, d-phenothrin, esfenvalerate, lambda-cyhalothrin, 

permethrin, phenothrin, pyrethrins) and with or without a synergist including piperonyl butoxide 

(PBO) and/or MGK 264. Prallethrin may be formulated as a liquid (may be pressurized), 

emulsifiable concentrate, ready-to-use solution, soluble concentrate, and pressurized gas. 

Methods of application include aerosol can (with or without injection tube); fumigation; cloth, 

glove, or sponge; sprayer (hand-held, mechanical, pressure, trigger); space and/or surface 

treatment/spray; crack and crevice and/or spot treatment; injection treatment (including trees and 

mounds); package applicator; and ultra low volume (ULV) aerosol or fog generator (nonthermal, cold fog) that may be aircraft- (fixed-wing or helicopter) or truck-mounted. For 

example, Duet® and MULTICIDE®Fogging Concentrate 2798 are formulated products for aerial 

and ground ULV application over the residential and recreation areas.

The maximum labeled application rates by use site and formulation are provided in Appendix C. 

Additional label information including specific maximum application rate per application and 

per year, maximum number of applications per year, and defined application intervals would

reduce uncertainties in the risk assessment.

4.2.2 Prallethrin Use with Synergists

PBO and MGK 264 are synergists commonly used in formulations with prallethrin. PBO acts as 

a potentiator in both mammals and insects because the pyrethroid is not metabolized and 

excreted as quickly in its presence (Barile, 2004; Hodgson & Smart, 2001). Amweg & Weston 

(2007) and Weston & Lydy (2010) showed increasing toxicity when exposing aquatic 

invertebrates to mixtures of pyrethroids and PBO. Amweg et al. (2006) and Weston et al. (2006) 

also reported the potential for synergism in the environment. In general, active ingredients and 

synergists have differing fate properties and therefore would be expected to occur in the 

environment at different times and at different concentrations than present in the end-use 

product. MGK-264, another potentiator/synergist used with pyrethroids, has similar effects as 

those observed for piperonyl butoxide (Hodgson & Smart, 2001). Prallethrin may be coformulated with either or both PBO and MGK-264 in numerous products (see Appendix B).

Currently, data on the degree to which the toxicity of pyrethroid active ingredients is enhanced 

by varying concentrations of PBO and MGK-264 are needed to address the ecological risk of

pyrethroid products when co-applied with PBO or MGK-264. The data need is discussed in the 

EFED Registration Review Problem Formulation for Piperonyl Butoxide, dated December 13, 

2010 (USEPA, 2010, D378420). The PBO Problem Formulation is available in the PBO 

registration review docket at www.regulations.gov (EPA-HQ-OPP-2010-0498). Based on data 

for the acute toxicity of pyrethrin and PBO to target insect species, the degree of toxicity

enhancement increases at higher PBO:pyrethrin ratios (or absolute concentrations), and this 
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toxicity enhancement is greater than simple additive toxicity (Stewart, 1998). The Agency is 

currently evaluating a proposed study protocol that will quantify the enhancement of acute 

toxicity of active ingredients used with PBO to the freshwater amphipod, Hyalella azteca, by

simultaneous exposure to PBO at varying PBO:active ingredient ratios. This comprehensive 

testing strategy, when augmented with similar acute toxicity data for freshwater fish and other 

selected pesticide active ingredients, should facilitate bridging of the synergist toxicity

enhancement to other co-formulated or co-applied pesticide/synergist active ingredients that are 

not tested at varying synergist:active ingredient ratios. With respect to evaluating ecological 

risks from co-applied prallethrin and synergists, the Agency is requesting acute toxicity studies

of prallethrin TEPs that are co-formulated with PBO and MGK-264 at the highest 

synergist:active ingredient ratio. These TEPs should correspond to those formulated products 

that are labeled for outdoor uses and would be conducted with a freshwater fish and a freshwater 

invertebrate. Additional discussion of the need for combined prallethrin:synergist toxicity data is 

provided in Section 7.9 (Preliminary Data Gaps).

4.2.3 Environmental Mixtures

Toxicity data on environmental mixtures of prallethrin and other pesticides may be presented, if 

available, as part of the ecological risk assessment. The toxic effect of prallethrin, in combination 

with other pesticides used in the environment, is likely to be a function of many factors including 

but not necessarily limited to:

 the exposed species, 

 co-contaminants in the mixture, 

 the ratio of prallethrin and co-contaminant concentrations, 

 differences in the pattern and duration of exposure among contaminants, and

 the differential effects of other physical/chemical characteristics of the receiving waters 

(e.g., organic matter present in sediment and suspended water). 

Quantitatively predicting the combined/cumulative effects of all these variables on mixture 

toxicity to any given taxa with confidence is beyond the capabilities of the available data and 

methodologies. However, the implications of the data gap for pesticide mixture effects on the 

confidence of risk assessment conclusions will be addressed in the uncertainty analysis. 

EFED will consider open literature, current models, and other lines-of-evidence (e.g., monitoring 

data), as available, to address the potential for cumulative effects of prallethrin in the risk 

description of the ecological assessment.

4.2.4 Usage

There is limited information available for prallethrin usage. BEAD reported that Kline & Co. 

prepared a special study in 2006 for EPA which estimated non-agricultural usage of prallethrin 

for households to be approximately 28,000 lbs and suggested the study probably underestimates 

non-agricultural usage since it did not include any non-household sites such as food handling 

establishments and warehouses (USEPA, 2011). There is no prallethrin usage information for 

mosquito and other public health pest control. Previous risk assessments were based on the 

labeled uses at the time the assessments were conducted. Obtaining additional information will 

improve future EFED risk assessment for these uncertainties. We concur with BEAD’s analysis
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that the following data deficiencies should be considered as part of the registration review of 

prallethrin: 

 Usage data (pounds a.i. applied, application methods frequently used, and area treated) 

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

establishment, and use in and around commercial and institutional facilities.

 Usage data (pounds a.i. applied, application methods frequently used, and area treated) 

for structural treatment at agricultural and commodity-processing facilities.

 GIS-mapping data (e.g., frequency of application, pounds a.i. applied) on use of 

prallethrin as a mosquito adulticide.

4.3 Environmental Fate and Transport

The structure of prallethrin has a phenyl ring and a cyclopropyl ring. Prallethrin (also known as 

ETOC) consists mainly of [1R,trans; S] and [1R,cis; S] isomers in a ratio of approximately 4:1 

(http://www.who.int/whopes/quality/en/prallethrin_spec_eval_Nov_2004.pdf). Prallethrin 

dissipation appears to be dependent on photodegradation in aqueous environments, hydrolysis, 

microbially mediated degradation, and soil binding. Data show that ETOC has low solubility

and appears to be stable at pH’s 5 and 7. However, at an elevated pH of 9, it hydrolyzes with a 

calculated half-life of 4.9 days with two isomeric bicyclic ketones (1A+2A, totaling 82.2 –

93.7%) and PGLS (totaling 4.3 - 14%) as the major degradates (MRID 42838602). A diagram of 

prallethrin degradation or metabolic pathway is provided in Appendix G. In aqueous 

environments, the compound breaks at the ester bond to yield d-t-CRA (MRIDs 44861001, 

44366601) and PGLS (MRIDs 44861002, 44366602). PGLS can undergo hydration and 

subsequent keto-enol tautomerism, resulting in ketolone (MRID 43797601). It can also undergo 

double bond rearrangement, resulting in PGL-allene, or hydroxylation at C-1, resulting in PGLOH (MRIDs 44366601, 44366602). Finally, PGLS can undergo oxidation of the alcohol group 

to yield keto-PGLS, then keto-ketolone, and ultimately these degradates yield CO2 (MRID 

43797601).

4.3.1 Photodegradation

Photodegradation is the primary route of prallethrin transformation with a pseudo first-order 

half-life of 0.57 days (13.6 hrs) in the aqueous environment (MRID 43797601). The major 

degradates are ketolone, 37.3% ,and PGLS, 26.0%, in 8 days and keto-PGLS, 16.5%, in 1 day of 

irradiation. In a sandy loam soil environment, the half-lives of prallethrin photodegradation were 

24.8 and 26.9 days respectively with CO2, chrysanthemic acid, and PGLS as the major 

degradates, but the percentages of formation were unclear from the studies (MRIDs 43797602, 

43797603). 

4.3.2 Aerobic Degradation

The observed half-life of prallethrin in aerobic soil was approximately 3 days with CO2 as a 

major degradate, totaling 42.8 – 44.4% at 112 days post-treatment (MRID 42838601). The 

aerobic aquatic metabolism studies (MRIDs 44860101, 44861002) were considered 
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supplemental. The systems may be partly aerobic and partly anaerobic because they were 

flooded prior to application of the test material, which may have caused anaerobic conditions. 

The registrant showed that dissolved oxygen was measured in the water phase (resulting in 40-

73% relative dissolved oxygen, providing an indirect measure of the aerobicity of the water 

phase; however, the aerobicity of the sediment is uncertain). For studies conducted in darkness 

at 25°C for up to 91 days, prallethrin degraded with calculated half-lives of 16 and 17 days for 

the 14C radiolabeled at cyclopropyl and cyclopentenyl positions, respectively. In the cyclopropyl

label study, two major degradates, d-t-CRA and t-COOH-CA, reached a maximum of 42.3% at 

14 days and 31.1% at 60 days post-treatment, respectively. In the cyclopentenyl label study, the 

major degradate PGLS reached a maximum of 24.2% at 7 days post-treatment. Nonextractable 

14C residues reached a maximum of 52.3% at 60 days, and 46.5% at 91 days post-treatment. 

CO2 production reached a maximum 23.3% at 91 days post-treatment (MRIDs 44861001, 

44861002). 

4.3.3 Anaerobic Degradation

No study was found for anaerobic soil metabolism. Two anaerobic aquatic metabolism studies 

(MRIDs 44366601, 44366602) were considered as supplemental. They partially satisfy the data 

requirement although a large portion of the radioactivity was not extracted or identified, which

may create uncertainties for the risk assessment. However, EFED has determined that the 

deficiency will not affect the prallethrin half-life in anaerobic aquatic conditions. The studies

were conducted in a water-sediment system (water pH 7.0, sediment texture: loam, pH 4.6, 

organic matter 6.02%, temperature 25 oC) for up to 181 days. The first order half-lives of 

prallethrin in the entire system were 33 and 35 days in two separate studies using [acid 14C]-dtrans-ETOC and [alc14C]-d-trans-ETOC. The only major degradate in the first study was d-tCRA which reached a maximum of 55.2% at 57 days, and the total unidentified radioactivity

reached a maximum of13.3 %. In the second study, four transformation products were identified 

with a maximum of 14.6% PGL-OH and ketolone at 59 days, 20.7% PGLS at 59 days, 10% 

PGL-allene at 181 days and 4.7% Keto-PGLS at 181 days (MRIDs 44366601, 44366602). 

4.3.4 Adsorption/Desorption and Leaching 

The submitted adsorption/desorption and leaching study (MRID 42810801) was unacceptable 

because the test soils were autoclaved before use, thus possibly altering the physical and 

chemical properties of the soils. The data cited in Table 4-1 are for reference only. The 

registrant must demonstrate that autoclaving the soil did not influence the results of this study, 

and that the observed results are an accurate representation of prallethrin adsorption / desorption 

from soil or submit a new study. The Agency has a limited knowledge of how prallethrin 

behaves in the environment once applied by aerial ULV spray for mosquito control. Depending 

on the mobility of the compound and soil characteristics in the environment, prallethrin may or 

may not be transported to surface water and/or ground water bodies used by organisms in the 

environment and/or by humans for drinking water.

4.3.5 Terrestrial and Aquatic Field Dissipation 
No terrestrial and aquatic field dissipation

is not registered for agricultural use, data on terrestrial and aquatic field dissipation will be 

waived at this time.

4.3.6 Bioconcentration in Fish

Fish bioaccumulation was studied

of [Alc14C]-d-trans-ETOC (parent prallethrin)

radioactivity in the fish were 1.3-

to 1070 ppb, and the bioconcentration factors (B

maximum BCFs in non-edible tissue were at 2210

tissues were ETOC-Alc (96.3 ppb) and its glucuronide conjugate (1,070 ppb)

conjugate of ETOC-Acid (787 ppb) at day 28 of exposure. 

Registrant-submitted data defining the physical, chemical, fate and transport characteristics 

associated with prallethrin are summarized in 

Table 4-1. Physical, Chemical, 

Major Degradates.

Parameter

Prallethrin

Chemical 

Chemical Family

Empirical Formula

SMILES

IUPAC

CAS Number

Structure

Selected Physical/Chemical Parameters

Molecular mass

Boiling point

Solubility (25°C)

Vapor pressure (23.1°C)

Henry’s law constant (20°C, pH 7)

-14 of 79-

No terrestrial and aquatic field dissipation studies are available for prallethrin. Since prallethrin 

ural use, data on terrestrial and aquatic field dissipation will be 

.3.6 Bioconcentration in Fish

Fish bioaccumulation was studied by exposing bluegill sunfish to 0.937 ppb water concentration 

(parent prallethrin) (MRIDs 42810802, 43758001). The half

-2.5 days. The 14C concentrations in whole fish ranged from 

and the bioconcentration factors (BCFs) ranged from 787 to 1160 whereas the 

edible tissue were at 2210-3130. The major metabolites

Alc (96.3 ppb) and its glucuronide conjugate (1,070 ppb) as well as a

Acid (787 ppb) at day 28 of exposure. 

submitted data defining the physical, chemical, fate and transport characteristics 

associated with prallethrin are summarized in Table 4-1.

, and Environmental Fate Properties of Prallethrin

Value Reference Comments

Prallethrin / ETOC MRID 41321801 Product Chemistry

Synthetic pyrethroid MRID 41321800 Product Chemistry

C19H24O3 MRID 41321801 Product Chemistry

O=C2C(=C(C)C(OC(=O)C1

C(C=C(C)C)C1(C)C)C2)CC

#C

EPI V4.10

(S)-2-methyl-4-oxo-3-(2-

propynyl) cyclopent -2-enyl 

(1RS)-cis, trans-2,2 -

dimethyl -3-(2-methylprop1-enyl) 

cyclopropanecarboxylate

MRID 41321801 Product Chemistry

23031-36-9 MRID 41321801 Product Chemistry

MRID 41321801 Product Chemistry

Selected Physical/Chemical Parameters

300.4 MRID 41321801 Product Chemistry

313.5 oC MRID 41321803 Product Chemistry

8.03 ppm MRID 41321803 Product Chemistry

<1.0x10-7 mm Hg MRID 41321803 Product Chemistry

4.92x10-9atm·m3/mol Calculated (VP/760)/(SOL/MWT) 

(per EFED Guidance ver 

2.1, Oct 22, 2009)

Since prallethrin 

ural use, data on terrestrial and aquatic field dissipation will be 

by exposing bluegill sunfish to 0.937 ppb water concentration 

43758001). The half-lives of 

ranged from 708

whereas the 

The major metabolites in non-edible 

as well as a taurine 

submitted data defining the physical, chemical, fate and transport characteristics 

rallethrin and Its 

Comments

Product Chemistry

Product Chemistry

Product Chemistry

Product Chemistry

Product Chemistry

Product Chemistry

Product Chemistry

Product Chemistry

Product Chemistry

Product Chemistry

(VP/760)/(SOL/MWT) 

(per EFED Guidance ver 

2.1, Oct 22, 2009)
-15 of 79-

Parameter Value Reference Comments

Octanol-water partition coefficient 

(KOW) (25°C)

4.49 MRID 41321803 Product Chemistry

Organic carbon partition coefficient 

(median Koc)

2004* MRID 42810801 *The study was 

unacceptable because the 

test soils were autoclaved 

before use. 

(Data gap)

Bioconcentration factor (BCF) 1160 MRID 43758001 Based on total 14C 

bioconcentration in whole 

fish at 7 days

Persistence

Hydrolysis pH 5

pH 7

 pH 9

 stable

stable

4.9 days 

MRID 42838602

Aqueous Photolysis (t 1⁄2 ) 0.57 days MRID 43797601

Soil Photolysis (t 1⁄2 ) 29 days MRID 43797602

MRID 43797603

Upperbound value 

calculated based on 24.8 

and 26.9 days (n=2), as 

per EFED guidance

Aerobic Soil Metabolism (t 1⁄2 ) 9 days MRID 42838601 Upperbound value, 

calculated based on 3x 3 

days (n=1), as per EFED 

guidance

Anaerobic Soil Metabolism N/A N/A (Data gap)

Anaerobic Aquatic Metabolism (t 1⁄2 ) 37 days MRID 44366601 

MRID 44366602

Upperbound value, 

calculated based on 33 

and 35 days (n=2), as per 

EFED guidance

Aerobic Aquatic Metabolism 18 days MRID 44861001

MRID 44861002

Upperbound value, 

calculated based on 16 

and 17 days (n=2), as 

per EFED guidance

Bioaccumulation in Fish (Depuration 

half-life)

1.3 – 2.5 days MRID 42810802

MRID 43758001

Mobility

Soil/Water partition coefficient (The 

lowest on non-sand Kd)

51.51* MRID 42810801 *The study was 

unacceptable because the 

test soils were autoclaved 

before use. 

(Data gap)

Field Dissipation

Terrestrial Field Dissipation (t 1⁄2 ) N/A N/A (Data gap)

PGLS (Major degradate)

Chemical PGLS MRID 42838602

MRID 43797601

MRID 44366602

MRID 44861002

Empirical Formula C9H10O2 EPI V4.10
Parameter

SMILES

Structure

Selected Physical/Chemical Parameters

Molecular mass

Boiling point

Solubility (25°C)

Vapor pressure (30°C)

Henry’s law constant (20°C, pH 7)

Octanol-water partition coefficient 

(KOW) (25°C)

Organic carbon partition coefficient 

(median Koc)

BCF

Water Half-Life

Soil Half-Life

d-t-CRA (Major degradate)

Chemical 

Empirical Formula

SMILES

Structure

Selected Physical/Chemical Parameters

Molecular mass

Boiling point

Solubility (25°C)

Vapor pressure (30°C)

Henry’s law constant (20°C, pH 7)

Octanol-water partition coefficient 

(KOW) (25°C)

Organic carbon partition coefficient 

(median Koc)

BCF

Water Half-Life

Soil Half-Life

-16 of 79-

Value Reference Comments

C1(=C(C(C[C@@H]1O)=O

)CC#C)C.

EPI V4.10

MRID 42838602

MRID 43797601

MRID 44366602

MRID 44861002

Selected Physical/Chemical Parameters

150.18 EPI V4.10

275.57 oC EPI V4.10

9.63e+004 ppm EPI V4.10

2.51x10-4 mm Hg EPI V4.10

5.15x10-10 atm·m3/mol EPI V4.10

0.48 EPI V4.10

9.435 ml/g EPI V4.10

3.162 L/Kg EPI V4.10 BCFBAF v3.01

15 days EPI V4.10 Level III 

30 days EPI V4.10 Level III Fugacity Model

d-t-CRA MRID 44366601 

MRID 44861001

C10H16O2 EPI V4.10

O=C(O)C1C(C)(C)C1C=C(

C)C

EPI V4.10

MRID 44366601

MRID 44861001

Selected Physical/Chemical Parameters

164.24 EPI V4.10

264 oC EPI V4.10

164 ppm EPI V4.10

5.87 x10-3 mm Hg EPI V4.10

2.42x10-6atm·m3/mol EPI V4.10

3.49 EPI V4.10

59.47 ml/g EPI V4.10

3.162 L/Kg EPI V4.10 BCFBAF v3.01

15 days EPI V4.10 Level III 

30 days EPI V4.10 Level III Fugacity Model

Comments

BCFBAF v3.01

Level III Fugacity Model

Level III Fugacity Model

BCFBAF v3.01

Level III Fugacity Model

Level III Fugacity Model
-17 of 79-

4.4 Degradates of Concern

Two prallethrin degradates, PGLS and d-t-CRA, are formed as the result of cleavage of the ester 

linkage of the prallethrin structure through hydrolysis. The d-t-CRA will yield CO2 and polar 

products. The PGLS (14-26%) is predicted to have higher water solubility (9.63e+004 ppm), 

higher mobility (Koc: 9.435 ml/g), and a longer half-life than its parent based on structure 

estimation (EPI Suite v.4.10; Appendix D). In addition, PGLS is a precursor for other 

metabolites and conjugates (Appendix G). However, PGLS is expected to lose its activity as a 

sodium channel inhibitor and is probably less toxic than the parent. Therefore, no additional data 

on PGLS will be requested at this time. Should the registrant wish to add new uses of this 

chemical, the data requirement may be reassessed. 

4.5 Water Quality

Prallethrin is not identified as a cause of impairment for any water bodies under section 303(d) of 

the Clean Water Act1. In addition, no Total Maximum Daily Load (TMDL) has been developed 

for prallethrin2, and there are no aquatic life criteria for prallethrin3. More information on 

impaired water bodies and TMDL can be found at http://www.epa.gov/owow/tmdl/.

No monitoring data are available for prallethrin. Neither the USGS’s National Water Quality

Assessment (NAWQA) program nor the California Department of Pesticide Regulation’s

monitoring programs included prallethrin as an analyte.

During the risk assessment process, the following databases and sources will be searched for 

current monitoring information on prallethrin:

 The United States Environmental Protection Agency (USEPA) STORET Database 

(http://www.epa.gov/storet/dbtop.html)

 The United States Geological Survey (USGS) National Water-Quality Assessment 

(NAWQA) Program Data Warehouse 

(http://infotrek.er.usgs.gov/traverse/f?p=NAWQA:HOME:1405517206944567) 

 The USGS National Stream Quality Accounting Network (NASQAN) program 

(http://water.usgs.gov/nasqan/)

 Sampling for Pesticides Residues in California Well Water Cumulative Report; EEH03-

08; December 2003 (http://www.cdpr.ca.gov/docs/emon/pubs/ehapreps/eh0308.pdf) 

 

1

based on information provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885, 

accessed January 24, 2012

2

based on information provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant_

group_name=PESTICIDES, accessed January 24, 2012

3

based on information provided at http://water.epa.gov/scitech/swguidance/standards/criteria/aqlife/index.cfm, 

accessed 24, 2012
-18 of 79-

 California Department of Pesticide Regulation (DPR) Surface Water Database 

(http://www.cdpr.ca.gov/docs/emon/surfwtr/surfdata.htm)

The Agency invites submission of water quality data for this pesticide. To the extent possible, 

data should conform to the quality standards in Appendix A of the OPP Standard Operating 

Procedure: Inclusion of Impaired Water Body and Other Water Quality Data in OPP’s 

Registration Review Risk Assessment and Management Process (see: 

http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1-sop.pdf) to ensure they can be 

used quantitatively or qualitatively in pesticide risk assessments.

5. Receptors

The receptor is the biological entity that is exposed to the stressor (EPA, 1998). Due to the 

outdoor uses of prallethrin, the types of receptors that may be exposed include both aquatic and 

terrestrial receptors, such as birds, reptiles, mammals, amphibians, freshwater and

estuarine/marine fish, non-target terrestrial and aquatic invertebrates, and terrestrial and aquatic 

plants, etc. Spray drift and runoff exposures are expected for both ground and aerial applications 

of prallethrin. Consistent with the process described in the Overview Document (USEPA, 2004), 

the risk assessment for prallethrin relies on a surrogate species approach. Toxicological data 

generated from surrogate test species, which are intended to be representative of broad 

taxonomic groups, are used to extrapolate the potential effects on a variety of species (receptors) 

included under these taxonomic groupings.

Acute and chronic toxicity data from studies submitted by pesticide registrants along with the 

available open literature are used to evaluate the potential direct and indirect effects of prallethrin

to aquatic and terrestrial receptors. This includes toxicity on the technical grade active 

ingredient, degradates, and when available, formulated products (e.g., “Six-Pack” studies). The 

open literature studies are identified through EPA’s ECOTOXicology (ECOTOX) database 

which employs a literature search engine for locating chemical toxicity data for aquatic life,

terrestrial plants, and wildlife (USEPA, 2007b). The evaluation of both sources of data will

provide insight into the direct and indirect effects of prallethrin on biotic communities from loss 

of species that are sensitive to the chemical and from changes in structure and functional 

characteristics of the affected communities. Data from an ECOTOX database for prallethrin will

be evaluated for possible quantitative and/or qualitative inclusion in the risk assessment in 

support of Registration Review. At that time, endpoints more sensitive than those available from

guideline studies will be reviewed from the open literature studies.

A brief summary of the aquatic and terrestrial toxicity data available for prallethrin is provided in 

Sections 5.1 and 5.2, respectively. In addition, ecological incidents associated with prallethrin 

use and a description of ecosystems potentially at risk are summarized in Sections 5.3 and 5.4, 

respectively. 

Acute toxicity to aquatic animals (i.e., fish and aquatic invertebrates), terrestrial vertebrates (i.e., 

birds and mammals), and terrestrial invertebrates (i.e., honeybees) is categorized using the 

system shown in Table 5-1 (USEPA, 2004). Toxicity categories for plants have not been 

defined.
-19 of 79-

Table 5-1. Categories of Acute Toxicity for Aquatic and Terrestrial Animals

Aquatic 

Vertebrates & Invertebrates

Terrestrial 

Vertebrates

Terrestrial 

Invertebrates

Toxicity Category

LC50

(ppm)

Oral LD50

(mg/kg)

Dietary LC50

(ppm)

LD50

(μg a.i./bee)

< 0.1 < 10 < 50 Very highly toxic

> 0.1 - 1 10-50 50-500 < 2 Highly toxic

> 1 - 10 51-500 501-1000 2-10.99 Moderately toxic

> 10 - 100 501-2000 1001-5000 Slightly toxic

> 100 > 2000 > 5000 ≥ 11 Practically non-toxic

5.1 Effects to Aquatic Organisms

A summary of aquatic toxicity data for prallethrin from registrant-submitted studies is provided 

in Table 5-2 (animals) and Table 5-3 (plants). There are no toxicity data for the two major 

degradates of prallethrin, PGLS and d-t-CRA. 

Two acute studies with freshwater fish have been submitted: one with bluegill sunfish (MRID 

41321808) and one with rainbow trout (MRID 41321809). Both studies indicate that prallethrin

is very highly toxic to freshwater fish. A single fish toxicity study with an estuarine/marine 

species has been submitted (MRID 44729602); this acute toxicity study indicates that prallethrin

is also very highly toxic to sheepshead minnow. The only submitted chronic toxicity study with 

a fish species, an early-life stage study with rainbow trout (MRID 44729604), yielded a NOEC 

of 3.0 μg a.i./L which was the highest treatment level in the study; a LOEC could not be 

determined using the selected treatment concentrations. 

For aquatic invertebrates, five acute toxicity studies have been submitted: one with daphnids

(MRID 41321810), one with Eastern oyster (MRID 44729601), two with mysid shrimp (MRIDs

44729603 and 48055901), and one with an amphipod in sediment (MRID 47762401). The latter 

sediment toxicity study with Hyalella azteca has been classified as supplemental due to 

uncertainty regarding the accuracy of the LC50 values given potential interference from the 

solvent. Collectively, the four former studies indicate that prallethrin is highly toxic to very

highly toxic to aquatic invertebrates. It should be noted that one of the studies with mysid 

shrimp was conducted with TGAI (MRID 44729603) whereas the other (MRID 48055901) was 

conducted with the TEP MULTICIDE Fogging Concentrate 2798 (Reg No. 1021-1795) which 

also contains two other active ingredients, the synthetic pyrethroid d-phenothrin (PC Code 

069005) and the synergist PBO (PC Code 067501). Results of the study with the TEP indicate

that MULTICIDE Fogging Concentrate 2798 is three orders of magnitude more toxic than 

prallethrin TGAI (96-hr LC50 = 3.9 μg a.i./L with TGAI; LC50 = 0.0079 μg a.i./L with TEP). 

The only submitted chronic toxicity study with an aquatic invertebrate species, a life cycle test 

with daphnids (MRID 44729605), yielded a 21-day NOEC of 0.65 μg a.i./L based on number of 

offspring per female.

A single aquatic plant toxicity study (MRID 48055902) has been submitted: a Tier II test with an 

aquatic vascular plant using the TEP MULTICIDE Fogging Concentrate 2798 (Reg No. 1021-
-20 of 79-

1795). This study yielded no effects on duckweed up to 1.324 μg a.i./L prallethrin. No data are 

available for non-vascular aquatic plants.

Table 5-2. Summary of the Endpoints from Submitted Aquatic Animal Toxicity Studies for 

Prallethrin

Study Type &

TGAI (%)/TEP Species Toxicity Value &Toxicity Classification 

MRID & 

Classification

Freshwater Fish

Acute

TGAI 92.9%

Bluegill sunfish 

(Lepomis 

macrochirus)

Mean-measured concentrations

96-hr LC50 = 22 μg a.i./L

96-hr NOEC = 8.6 μg a.i./L 

(based on mortality)

Very highly toxic

41321808

Acceptable

Acute

TGAI 92.6%

Rainbow trout 

(Oncorhynchus 

mykiss)

Mean-measured concentrations

96-hr LC50 = 12 μg a.i./L

96-hr NOEC = 4.3 μg a.i./L 

(based on mortality)

Very highly toxic

41321809

Acceptable

Early-life stage

TGAI 94.2%

Rainbow trout 

(Oncorhynchus 

mykiss)

Mean-measured concentrations

90-day NOEC = 3.0 μg a.i./L

90-day LOEC > 3.0 μg a.i./L

(no effects)

44729604

Acceptable

Estuarine/Marine Fish

Acute

TGAI 94.2%

Sheepshead minnow

(Cyprinodon 

variegates)

Mean-measured concentrations

96-hr LC50 = 26 μg a.i./L

95% C.I.: 23-31 μg a.i./L

96-hr NOEC = 11 μg a.i./L

96-hr LOEC = 16 μg a.i./L

(based on lethargy and erratic swimming 

behavior)

Very highly toxic

44729602

Acceptable 

Freshwater Invertebrates

Acute

TGAI 92.9%

Water flea 

(Daphnia magna)

Mean-measured conentrations

48-hr EC50 = 6.2 μg a.i./L

48-hr NOEC = 4.6 μg a.i./L

(based on mortality)

Very highly toxic

41321810

Acceptable

Life cycle

TGAI 94.2%

Water flea 

(Daphnia magna)

21-day NOEC = 0.65 μg a.i./L

21-day LOEC = 1.3 μg a.i./L

21-day MATC = 0.93 μg a.i./L

(based on number of offspring per female)

44729605

Acceptable

Acute: whole 

sediment

TGAI

97.4% radiochemical purity

93.4% nonradioactive purity

Amphipod

(Hyalella azteca)

Mean-measured bulk sediment concentrations

10-day LC50 = 14.9 mg TRR/kg-dw

10-day NOEC = 5.9 mg TRR/kg-dw

10-day LOAEC = 12 mg TRR/kg-dw

(based on mortality)

Organic carbon-normalized mean-measured 

sediment concentrations

10-day LC50 = 339 mg TRR/kg-dw

10-day NOEC = 134.09 mg TRR/kg-dw

10-day LOAEC = 272.7 mg TRR/kg-dw

(based on mortality)

Mean-measured pore water concentrations

47762401

Supplemental
-21 of 79-

Study Type &

TGAI (%)/TEP Species Toxicity Value &Toxicity Classification 

MRID & 

Classification

10-day LC50 = 0.55 mg TRR/L

10-day NOEC = 0.25 mg TRR/L

10-day LOAEC = 0.44 mg TRR/L

(based on mortality)

Mean-measured overlying water concentrations

10-day LC50 = 0.018 mg TRR/L

10-day NOEC = 0.0082 mg TRR/L

10-day LOAEC = 0.014 mg TRR/L

(based on mortality)

Estuarine/Marine Invertebrates

Acute

TGAI 94.2%

Eastern oyster 

(Crassostrea 

virginica)

Mean-measured concentrations

96-hr EC50 = 0.64 mg a.i./L

95% C.I.: 0.58-0.69 mg a.i./L

Probit slope: 10.5±1.39

96-hr NOEC = 0.41 mg a.i./L 

96-hr LOEC = 0.57 mg a.i./L

(based on shell deposition)

Highly toxic

44729601

Acceptable

Acute

TGAI 94.2%

Mysid shrimp 

(Mysidopsis bahia)

Mean-measured concentrations

96-hr LC50 = 3.9 μg a.i./L

95% C.I.: 3.4-4.3 μg a.i./L

96-hr NOEC = 2.1 μg a.i./L

(based on mortality)

96-hr LOEC = 3.1 μg a.i./L

(based on lethargy and erratic swimming)

Very highly toxic

44729603

Acceptable

Acute

TEP*

Mysid shrimp 

(Americamysis bahia)

Mean-measured concentrations

96-hr LC50 = 0.0079 μg a.i./L

95% C.I.: 0.0017-0.14 μg a.i./L

96-hr NOEC = 0.002 μg a.i./L

Probit Slope: N/A

48055901

Acceptable

TGAI = technical grade active ingredient; TEP = typical end-use product; TRR = total radioactive residue; N/A = 

not applicable; dw = dry weight

*conducted with MULTICIDE Fogging Concentrate 2798 (Reg No. 1021-1795), a typical end-use product 

containing 0.995% prallethrin, 4.98% d-phenothrin (PC Code 069005), and 4.97% piperonyl butoxide (PC Code 

067501)

Table 5-3. Summary of the Endpoints from Submitted Aquatic Plant Toxicity Studies for 

Prallethrin

Study Type &

TGAI (%)/TEP Species Toxicity Value*

MRID & 

Classification

Tier II, Aquatic 

plant growth

TEP*

Duckweed 

(Lemna gibba)

Measured (TWA) Concentrations

7-day EC50 > 1.324 μg a.i./L

7-day EC05 > 1.324 μg a.i./L

7-day NOEC ≥ 1.324 μg a.i./L

48055902

Acceptable

TGAI = technical grade active ingredient; TEP = typical end-use product; TWA = time-weighted average

*conducted with MULTICIDE Fogging Concentrate 2798 (Reg No. 1021-1795), a typical end-use product 

containing 0.995% prallethrin, 4.98% d-phenothrin (PC Code 069005), and 4.97% piperonyl butoxide (PC Code 

067501)
-22 of 79-

5.2 Effects to Terrestrial Organisms

Tables 5-4 and 5-5 summarize the terrestrial toxicity data for animals and plants, respectively, 

for prallethrin based on an evaluation of submitted studies. There are no toxicity data for the two 

major degradates of prallethrin, PGLS and d-t-CRA. 

No data are available for a passerine species. Single oral dose, dietary, and reproductive toxicity

studies have been submitted for bobwhite quail (MRIDs 41321805, 41321806, 43773403) and 

mallard ducks (MRIDs 41321804, 41321807, 43797604). The single oral dose study with 

mallard ducks (MRID 41321804) has been classified as supplemental because three birds in the 

highest dosage group regurgitated their doses. The results of the acute and subacute tests

indicate that prallethrin is slightly toxic and practically non-toxic to birds via acute oral and 

dietary exposures, respectively. The avian reproductive toxicity studies yielded NOECs of 360 

and 120 mg a.i./kg-diet for bobwhite quail and mallard ducks, respectively.

An acute oral toxicity study with rats (MRID 42030903) yielded a toxicity classification of 

moderately toxic. A two-generation reproductive study yielded a NOEL of 600 mg a.i./kg-diet 

and a LOEL of 3000 mg a.i./kg-diet (MRID 42077006). 

An acute contact toxicity study with honeybees yielded a toxicity classification of highly toxic 

(MRID 41321823). In addition, two alfalfa foliage residue studies with honeybees have been 

submitted: one with TGAI (MRID 41321823) and one with the TEP MULTICIDE Fogging 

Concentrate 2798 (Reg No. 1021-1795). Both studies showed no effects at the tested 

concentration (i.e., 0.005 lb a.i./A TGAI and 0.0008 lb a.i./A TEP).

Two Tier I terrestrial plant toxicity studies (i.e., seedling emergence and vegetative vigor) with 

the TEP MULTICIDE Fogging Concentrate 2798 (Reg No. 1021-1795) have been submitted for 

four monocots and six dicots (MRIDs 47431602, 47431603). Both studies tested the maximum 

rate for a single application for MULTICIDE Fogging Concentrate 2798. In the tier I vegetative 

vigor study (MRID 47431603), there were no significant effects. Therefore, the most sensitive 

species of monocots and dicots could not be determined. In the Tier I seedling emergence study

(MRID 47437602), an inhibition of greater than 25% was observed for sugarbeet emergence 

(32.4%). In the same study, the mean of the treated group was significantly less than that of the 

control group for the following species and endpoints: tomato emergence; wheat dry weight; and 

soybean dry weight. Therefore, a definitive NOEC could not be determined for these species. 
-23 of 79-

Table 5-4. Summary of the Endpoints from Submitted Terrestrial Animal Toxicity Studies 

for Prallethrin

Study Type &

TGAI (%)/TEP Species Toxicity Value &Toxicity Classification 

MRID & 

Classification

Birds

Single dose oral

TGAI 92.6%

Bobwhite quail 

(Colinus 

virginianus)

Nominal concentrations

14-day LD50 = 1171 mg a.i./kg-bw

95% C.I.: 835-1835 mg a.i./kg-bw

Probit slope = 3.7

(based on mortality)

14-day NOEC = 125 mg a.i./kg-bw

(based on signs of toxicity including lethargy, 

reduced reaction to sound and movement, 

ruffled appearance, wing droop, depression, 

loss of coordination, lower limb weakness, 

fasciculation, tremors, convulsions, panting, 

loss of righting reflex, and prostrate posture)

Slightly toxic

41321805

Acceptable

Single dose oral

TGAI 92.9%

Mallard duck

(Anas 

platyrhynchos)

Nominal concentrations

14-day LD50 > 1000 mg a.i./kg-bw

14-day NOEC = 250 mg a.i./kg-bw

(based on signs of toxicity including lethargy, 

reduced reaction to sound and movement, loss 

of coordination, lower limb weakness, 

fasciculation, tremors, convulsions, panting, 

loss of righting reflex, prostrate posture, and 

dorsal head curl)

Slightly toxic

41321804

Supplemental

Dietary

TGAI 92.9%

Bobwhite quail 

(Colinus 

virginianus)

Nominal concentrations

8-day LC50 > 5620 mg a.i./kg-diet

8-day NOEC = 3160 mg a.i./kg-diet

(based on reductions in feed consumption and 

body weight gain)

Practically non-toxic

41321806

Acceptable

Dietary

TGAI 92.9%

Mallard duck 

(Anas 

platyrhynchos)

Nominal concentrations

8-day LC50 > 5620 mg a.i./kg-diet

8-day NOEC = 1780 mg a.i./kg-diet

(based on reductions in body weight and feed 

consumption)

Practically non-toxic

41321807

Acceptable

Reproduction

TGAI 92.9%

Bobwhite quail 

(Colinus 

virginianus)

Nominal concentrations

10 week NOEL = 360 mg a.i./kg-diet

10-week LOEL = 600 mg a.i./kg-diet

(based on reduction in percentage of live 3-

week embryos)

43773403

Acceptable

Reproduction

TGAI 92.9%

Mallard duck

(Anas 

platyrhynchos)

Nominal concentrations

21-week NOEC = 120 mg a.i./kg-diet

21-week LOEC = 360 mg a.i./kg-diet

(based on eggs laid, eggs set, viable embryos, 

live 3-week embryos, 14-day survivor weight)

43797604

Acceptable

Mammals

Acute oral

TGAI 92.0%

Rat 

(Rattus norvegicus)

Nominal concentrations

14-day LD50 (M) = 640 mg a.i./kg

14-day LD50 (F) = 460 mg a.i./kg

Moderately toxic

42030903

Guideline
-24 of 79-

Study Type &

TGAI (%)/TEP Species Toxicity Value &Toxicity Classification 

MRID & 

Classification

Two generation 

reproduction

TGAI 92.9-93.6%

Rat 

(Rattus norvegicus)

Nominal concentrations

Parental NOEL = 600 mg a.i./kg-diet

Parental LOEL = 3000 mg a.i./kg-diet

(based on decreased body weight)

Reproductive NOEL = 600 mg a.i./kg-diet

Reproductive LOEL = 3000 mg a.i./kg-diet

(based on decreased pup weight)

42077006

Minimum

Invertebrates

Acute contact

TGAI 92.9%

Honeybee 

(Apis mellifera)

Nominal concentrations

48-hr LD50 = 0.028 μg a.i./bee

95% C.I.: 0.025-0.033

Probit slope = 4.8 (95% C.I.: 3.7-5.9)

48-hr NOED = 0.0125 μg a.i./bee 

(based on mortality)

Highly toxic

41321823

Acceptable

Foliage residue

(alfalfa)

Formulation 2.45%

Honeybee 

(Apis mellifera)

Nominal concentrations

24-hr NOEC = 0.005 lb a.i./A

(no effects)

43749301

Acceptable

Foliage residue

(alfalfa)

TEP*

Honeybee 

(Apis mellifera L.)

Nominal concentrations

24-hr NOEC ≥ 0.0008 lb a.i./A

(no effects)

47431601

Acceptable

TGAI = technical grade active ingredient; TEP = typical end-use product

*conducted with MULTICIDE Fogging Concentrate 2798 (Reg No. 1021-1795), a typical end-use product 

containing 1% prallethrin, 5% d-phenothrin (PC Code 069005), and 5% piperonyl butoxide (PC Code 067501)

Table 5-5. Summary of the Endpoints from Submitted Terrestrial Plant Toxicity Studies 

for Prallethrin

Study Type &

TGAI (%)/TEP Species Toxicity Value (Nominal) MRID & Classification

Seedling 

emergence Tier 1

TEP*

Monocots

Onion (Allium cepa) 

Ryegrass (Lolium perenne) 

Wheat (Triticum aestivum) 

Corn (Zea mays)

Dicots

Sugarbeet (Beta vulgaris) 

Cabbage (Brassica oleracea) 

Soybean (Glycine max) 

Lettuce (Lactuca sativa) 

Tomato (Lycopersicon esculentum)

Radish (Raphanus sativus)

Monocots

Most sensitive monocot: Wheat

Most sensitive parameter: Dry 

weight

21-day EC25/IC25 > 0.0008 lb a.i./A

21-day EC05/IC05 < 0.0008 lb a.i./A

21-day NOEC < 0.0008 lb a.i./A

Dicots

Most sensitive dicots: Sugarbeet, 

tomato, soybean

Most sensitive parameters: 

Emergence and dry weight

21-day EC25/IC25 < 0.0008 lb a.i./A

21-day EC05/IC05 < 0.0008 lb a.i./A

21-day NOEC < 0.0008 lb a.i./A

47431602

Acceptable
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Study Type &

TGAI (%)/TEP Species Toxicity Value (Nominal) MRID & Classification

Vegetative vigor 

Tier 1 

TEP*

Monocots

Onion (Allium cepa) 

Ryegrass (Lolium perenne) 

Wheat (Triticum aestivum) 

Corn (Zea mays)

Dicots

Sugarbeet (Beta vulgaris) 

Cabbage (Brassica oleracea) 

Soybean (Glycine max) 

Lettuce (Lactuca sativa) 

Tomato (Lycopersicon esculentum)

Radish (Raphanus sativus)

Monocots

Most sensitive monocot: Could not 

be determined at tested 

concentration

Most sensitive parameter: Could not 

be determined at tested 

concentration

21-day EC25/IC25 > 0.0008 lb a.i./A

21-day EC05/IC05 < 0.0008 lb a.i./A

21-day NOEC ≥ 0.0008 lb a.i./A

Dicots

Most sensitive dicot: Could not be 

determined at tested concentration

Most sensitive parameter: Could not 

be determined at tested 

concentration

21-day EC25/IC25 > 0.0008 lb a.i./A

21-day EC05/IC05 < 0.0008 lb a.i./A

21-day NOEC ≥ 0.0008 lb a.i./A

47431603

Acceptable

TGAI = technical grade active ingredient; TEP = typical end-use product

*conducted with MULTICIDE Fogging Concentrate 2798 (Reg No. 1021-1795), a typical end-use product 

containing 1% prallethrin, 5% d-phenothrin (PC Code 069005), and 5% piperonyl butoxide (PC Code 067501)

5.3 Incident Databases Review

Preliminary reviews of the Ecological Information System (EIIS, version 2.1.1), which is 

maintained by the Agency’s Office of Pesticide Programs, and the Avian Monitoring 

Information System (AIMS), which is maintained by the American Bird Conservatory, on 

January 5, 2012 did not yield any reported ecological incidents associated with the use of 

prallethrin. 

In addition to the incidents recorded in EIIS and AIMS, additional incidents are reported to the 

Agency in aggregated form. Pesticide registrants report certain types of incidents to the Agency

as aggregate counts of incidents occurring per product per quarter. Ecological incidents reported 

in aggregate reports include those categorized as ‘minor fish and wildlife’ (W-B), ‘minor plant’ 

(P-B), and ‘other non-target’ (ONT) incidents. ‘Other non-target’ incidents include reports of 

adverse effects to insects and other terrestrial invertebrates. For prallethrin, registrants have

reported one minor plant incident (P-B) as of January 5, 2012. 

The total number of actual incidents associated with the use of prallethrin may be higher than 

what is reported to the Agency. Incidents may go unreported since effects may not be 

immediately apparent and/or readily attributed to the use of a chemical. As such, the absence of 

incident reports cannot be construed as the absence of incidents.

5.4 Ecosystems Potentially at Risk
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Prallethrin may be applied to a variety of terrestrial environments for adult mosquito control. In

addition, it may be used on numerous non-agricultural, residential, and commercial sites.

Therefore, the ecosystems at risk are often extensive in scope, and it may not be possible to 

identify specific ecosystems during the development of a nation-wide ecological risk assessment. 

However, in general terms, terrestrial ecosystems potentially at risk from prallethrin exposure

could include the treated area and adjacent areas that may receive drift or runoff from outdoor 

spray, especially during aerial ULV applications for mosquito control. Areas adjacent to the 

treated area could include cultivated fields, fencerows and hedgerows, meadows, fallow fields or 

grasslands, woodlands, riparian habitats, ecological preserves, and national wildlife refuges. 

Prallethrin residues may deposit into various water bodies resulting in possible exposure to 

aquatic species. Aquatic ecosystems potentially at risk include water bodies adjacent to or 

downstream from the treated area and could include impounded bodies such as marshes, 

wetlands, ponds, lakes, and reservoirs, or flowing waterways such as streams or rivers. For uses 

in coastal areas, aquatic habitats could also consist of marine ecosystems, including estuaries. 

6. Assessment Endpoints

Assessment endpoints are defined as “explicit expressions of the actual environmental value that 

is to be protected.” Defining an assessment endpoint involves two steps: 1) identifying the 

valued attributes of the environment that are considered to be at risk; and 2) operationally

defining the assessment endpoint in terms of an ecological entity (i.e., a community of fish and

aquatic invertebrates) and its attributes (i.e., survival and reproduction). Therefore, selection of

the assessment endpoints is based on valued entities (i.e., ecological receptors), the ecosystems

potentially at risk, the migration pathways of pesticides, and the routes by which ecological

receptors are exposed to pesticide-related contamination. The selection of clearly defined

assessment endpoints is important because they provide direction and boundaries in the risk 

assessment for addressing risk management issues of concern. Changes to assessment endpoints

are typically estimated from the available toxicity studies which are used as the measures of 

effects to characterize potential ecological risks associated with exposure to pesticides, such as 

prallethrin.

To estimate exposure concentrations, the ecological risk assessment considers applications at the 

maximum application rate. The most sensitive toxicity endpoints are used from surrogate test 

species to estimate treatment-related direct effects on acute mortality and chronic reproductive, 

growth, and survival assessment endpoints. Toxicity tests are intended to determine effects of 

pesticide exposure on birds, mammals, fish, terrestrial and aquatic invertebrates, and plants. 

These tests include short-term acute, sub-acute, and reproduction studies and are typically 

arranged in a hierarchical or tiered system that progresses from basic laboratory tests to applied 

field studies. The toxicity studies are used to evaluate the potential of a pesticide to cause 

adverse effects, to determine whether further testing is required, and to determine the need for 

precautionary label statements to minimize the potential adverse effects to non-target animals 

and plants.

An open literature search will be conducted to determine any relevant endpoints. The search will 

focus on survival, growth and reproductive effects for aquatic and terrestrial effects of 
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prallethrin. More sensitive endpoints from acceptable open literature studies will be included in 

the ecological risk assessment.

7. Conceptual Model

The conceptual model for prallethrin provides a written description and visual representation of 

the predicted relationships between prallethrin, potential routes of exposure, and the predicted 

effects for the assessment endpoint. A conceptual model consists of two major components: risk 

hypothesis and a conceptual diagram (USEPA, 1998).

7.1 Risk Hypothesis

A risk hypothesis describes the predicted relationship among the stressor, exposure, and 

assessment endpoint response along with the rationale for their selection. For prallethrin, the

following ecological risk hypothesis is being employed for this ecological risk assessment:

Based on the application methods, the assumed fate and transport, and the assumed 

sensitivity of non-target aquatic and terrestrial species, prallethrin has the potential to 

reduce survival, reproduction, and/or growth in non-target terrestrial and aquatic 

organisms when used in accordance with the current labels. These non-target organisms 

include Federally-listed threatened and endangered species as well as non-listed species. 

7.2 Conceptual Diagrams

The conceptual site model is a generic graphic depiction of the risk hypothesis. It assumes that

the non-agricultural uses of prallethrin are capable of affecting aquatic and terrestrial animals 

provided environmental concentrations are sufficiently elevated as a result of proposed label 

uses. The environmental fate properties of prallethrin indicate that runoff, spray drift and direct 

spray represent potential transport mechanisms to aquatic and terrestrial habitats where nontarget organisms may be either directly or indirectly exposed. These transport mechanisms (i.e., 

sources) are depicted in the conceptual diagrams below (Figure 7-1 and Figure 7-2) along with 

a broad range of biological receptors of concern and the potential attribute changes (i.e., effects 

such as reduced survival, growth and reproduction) in the receptors due to exposure to

prallethrin. 

For prallethrin to pose an ecological risk, it must reach ecological receptors in biologically 

significant concentrations. An exposure pathway is the means by which prallethrin moves in the 

environment from a source to an ecological receptor. For an ecological exposure pathway to be 

complete, it must have a source, a release mechanism, an environmental transport medium, a 

point of exposure for ecological receptors, and a feasible route of exposure. In addition, the 

potential mechanisms of degradation/ transformation (i.e., which degradation/ transformation 

products may form in the environment, in which media, and how much) must be understood, 

especially if the metabolites/transformation products are of greater toxicological concern than the 

parent compound. Therefore, the assessment of ecological exposure pathways includes an 

examination of the source and potential migration pathways for constituents and the 

determination of potential exposure routes.
-28 of 79-

Figure 7-1. Conceptual Model for Effects of Prallethrin on Aquatic Organisms. Dotted 

Lines indicate Exposure Pathways that Have a Low Likelihood of Contributing to 

Ecological Risk 

** Route of exposure includes only ingestion of fish and aquatic invertebrates

Stressor

Source

Receptors

Attribute

Change

Prallethrin applied to use site

Spray drift

Aquatic animals

Invertebrates 

Vertebrates

**Piscivorous mammals

and birds

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in algae and 

vascular plants

Reduction in prey

Modification of PCEs 

related to prey availability

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Modification of PCEs related to 

habitat

Surface water/

Sediment

Runoff

Aquatic Animals

Invertebrates

Vertebrates

Exposure

Media

Uptake/gills

or integument

Ingestion Ingestion

Atmospheric 

transport

Wet/dry deposition

Soil

Leaching to

Groundwater

Uptake/gills

or integument

Aquatic Plants

Non-vascular

Vascular

Uptake/cell, 

roots, leaves

Riparian plants

terrestrial 

exposure 

pathways see 

Figure 6-2
-29 of 79-

Figure 7-2. Conceptual Model for Effects Prallethrin on Terrestrial Organisms. Dotted 

Lines indicate Exposure Pathways that Have a Low Likelihood of Contributing to 

Ecological Risk 

7.2.1 Drinking Water Exposure

The Screening Imbibition Program (SIP v.1.0, released June 15, 2010) is used to calculate an 

upper bound estimate of drinking water exposure alone using the solubility of prallethrin (8.03 

mg/L at 25°C; MRID 41321803), the most sensitive acute (LD50 = 1171 mg a.i./kg-bw; MRID 

41321805) and chronic (NOEL = 360 mg a.i./kg-diet; MRIDs 43773403, 43797604) avian 

toxicity endpoints and the most sensitive acute (LD50 = 460 mg a.i./kg; MRID 42030903) and 

chronic (NOEL = 600 mg a.i./kg; MRID 42077006) mammalian toxicity endpoints. Appendix 

E provides a description of the model and assumptions in deriving an upper bound exposure 

estimate. Drinking water exposure alone was determined not to be a potential concern for birds 

and mammals on both acute and chronic bases (see Appendix E for model results). Detailed 

information about the SIP v.1.0, as well as the tool, can be found on the EPA’s website at 

http://www.epa.gov/pesticides/science/models_pg.htm#terrestrial. 

7.2.2 Inhalation Exposure

STIR v.1.0, Screening Tool for Inhalation Risk, is used to provide an upper bound estimate of 

exposure of birds and mammals to pesticides through inhalation of spray drift or vapor. The 

Stressor

Source

Attribute

Change

Prallethrin applied to use site

Direct

application

Spray drift

Terrestrial 

vertebrates

Terrestrial 

inverts

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in prey and food

Modification of PCEs 

related to prey availability

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Modification of PCEs related

to habitat

Terrestrial plants

grasses/forbs, fruit, seeds 

(trees, shrubs)

Runoff

Terrestrial 

Vertebrates

Exposure Media

& Receptors Soil

Ingestion

Ingestion

Ingestion

Dermal uptake/Ingestion

Atmospheric 

transport

Root uptake/contact

Wet/dry deposition

Ingestion

Leaching to

Groundwater

Irrigation 

water
-30 of 79-

upper bound exposure estimate requires a number of input parameters including the vapor 

pressure and molecular weight for the vapor-phase pesticide; additionally it requires the 

application rate and method of application (i.e., ground or aerial) for spray drift. The toxicity

aspect of the tool requires an avian acute oral LD50 value (LD50 LD50 = 1171 mg a.i./kg-bw; 

MRID 41321805), the chemical specific avian allometric scaling factor to adjust toxicity based 

on body weight for the chemical (default = 1.15), the weight of the tested bird (default = 0.178 

kg for bobwhite quail), a rat acute oral LD50 value (LD50 = 460 mg a.i./kg; MRID 42030903), a 

rat acute inhalation LC50 value (LC50 = 0.288 mg/L; MRID 42030904), the duration of the rat 

inhalation study (assumed to be 4 hours), and the weight of the tested rat (default = 0.35 kg). 

This tool was designed for use in the Problem Formulation phase of the ecological risk 

assessment process to quantitatively evaluate the need for further analysis of inhalation as a 

potential pathway of concern for birds and mammals. If further analysis of the inhalation 

exposure pathway is recommended, additional data will be requested to address uncertainty

related to this route of exposure. Results from the model indicate that exposure of birds and 

mammals to prallethrin through inhalation of spray drift or vapor is not likely significant 

regardless of use application method (ground or air spray) (see Appendix F for model results). 

Detailed information about the STIR v.1.0, as well as the tool, can be found on the EPA’s 

website (http://www.epa.gov/pesticides/science/models_pg.htm#terrestrial).

8. Analysis Plan

To address the risk hypothesis, the potential for adverse effects on the environment will be 

estimated. Usage, environmental fate, and ecological effects of prallethrin will be characterized 

and integrated to assess the risks. Risk quotients (RQ) will be derived for prallethrin by dividing 

EECs by the most sensitive endpoint from the relevant, available toxicity data for prallethrin. As 

outlined in the Overview Document (USEPA, 2004), the likelihood of effects to individual 

organisms from particular uses of a chemical is estimated using the probit dose-response slope 

and either the level of concern (discussed below) or the actual calculated risk quotient value.

This analysis plan will be revisited and may be revised depending upon a full review of the data 

available in the open literature and the information submitted by the public in response to the 

opening of the Registration Review docket.

8.1 Stressors of Concern

The focus of this assessment is on the parent material, prallethrin. However, the Agency will 

review open literature to identify degradate(s) of potential toxicological concern and use of 

prallethrin with synergists and other pesticides. Data sources that will be used in the future 

assessment include: 1) registrant submissions in support of registration review; 2) publicly

available literature on ecological effects; 3) monitoring data for freshwater streams, lakes, 

reservoirs, and estuarine areas; and 4) incident reports of adverse effects on aquatic and 

terrestrial organisms associated with the use of prallethrin. 

 

Prallethrin may be applied in formulated mixtures with other pesticides and synergists approved 

for registered uses (see Appendix B). Toxicity data for TEPs, if available, may be presented as 
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part of the ecological risk assessment, and the data may be used qualitatively or quantitatively in 

accordance with the Agency’s Overview Document and the Services’ Evaluation Memorandum 

(USEPA, 2004; USFWS/NMFS/NOAA, 2004). Synergistic data for PBO and MGK 264, if 

available, may also be incorporated into the future assessment. The options for doing so include, 

but are not limited to:

 applying a toxicity enhancement factor (TEF) to the prallethrin toxicity endpoint;

 applying a TEF that is specific to the ratio of PBO/MGK 264 and prallethrin that 

corresponds to the EEC for prallethrin;

 applying a ratio-specific TEF for each daily prallethrin concentration; and

 modeling the enhanced toxicity by the synergist(s) and co-formulate active ingredient(s).

A discussion of the implications of the available pesticide mixture effects data on the confidence 

of risk assessment conclusions will be addressed in the risk description of the final ecological 

assessment.

8.2 Measures of Exposure

In order to estimate risks of prallethrin exposures in aquatic and terrestrial environments, all 

exposure modeling and resulting risk conclusions will be made based on maximum application 

rate, number of applications, and minimum application intervals for the currently registered use 

as discussed in Section 3.2. Measures of exposure are based on aquatic and terrestrial models 

that estimate environmental concentrations of prallethrin using the maximum labeled application 

rate and application methods that have the greatest potential for off-site transport of the 

chemical. 

8.2.1 Spray Drift

The AgDRIFT spray drift model (v2.01; May, 2001) or AgDISP model will be used to assess 

exposures of organisms to prallethrin residue deposited on aquatic and terrestrial habitats by

spray drift. Both models also function as tools for evaluating the potential buffer zones to 

protect sensitive aquatic and terrestrial habitats from undesired spray drift exposures. For aerial 

and ground ULV application of formulated prallethrin to control adult mosquitoes, a list of 

parameters such as, droplet size, spray volume, vortex decay rate, wind speed and directions will 

be input into the model for the spray drift and deposit predication. Descriptions of the above 

model can be obtained from http://www.epa.gov/pesticides/science/models_pg.htm#atmospheric.

8.2.2 Aquatic Exposure

For the aquatic assessment, estimated environmental concentrations (EECs) of prallethrin will be 

modeled by the Pesticide Root Zone Model (PRZM, v3.12.2, May 2005 ) coupled with the 

EXposure Analysis Model System (EXAMS, v2.98.4.6, April 2005). Both are Tier 2 screening 

simulation models coupled with the input shell PE5.pl (August, 2007) to generate daily 

exposures and 1-in-10-year EECs of prallethrin (and residues of concern) that may occur in 

surface water bodies adjacent to application sites receiving prallethrin through runoff and spray

drift. PRZM simulates pesticide application, movement and transformation on an agricultural 
-32 of 79-

field and the resultant pesticide loadings to a receiving water body via runoff, erosion, and spray 

drift. EXAMS simulates the fate of the pesticide and resulting concentrations in the water body. 

The standard watershed geometry used for ecological pesticide assessments assumes application 

to a 10-hectare agricultural field that drains into an adjacent 1-hectare water body that is 2 meters 

deep (20,000 m3volume) with no outlet. The PE5 model can also be used for the pesticide 

concentration estimation at different water depth (e.g., 1 m, 0.3 m and 0.1 m) as the Agency

deems it is necessary. The composite model PRZM/EXAMS is used to estimate screening-level 

exposure of aquatic organisms to prallethrin. The measure of exposure for aquatic species is the 

1-in-10-year peak or rolling mean concentration. The 1-in-10-year peak is used for estimating 

acute exposures of direct effects to aquatic organisms. The 1-in-10-year 60-day mean is used for 

assessing the effects to fish and aquatic-phase amphibians from chronic exposure. The 1-in-10-

year 21-day mean is used for assessing the effects on aquatic invertebrates from chronic 

exposure.

At the present time, the use of the impervious scenario (a PRZM modeling scenario) will be 

considered as the most suitable available modeling approach for impervious runoff. The PRZM 

impervious scenario may be used in the Tier 2-coupled aquatic models PRZM/EXAMS along 

with residential or other suitable scenarios such as rights-of-way (ROW) to obtain EECs. The 

conceptual model for the residential scenario integrates simultaneous modeling of the individual 

use scenario with an impervious scenario. This approach assumes that no watershed is 

completely covered by either the 1⁄4 acre lot (the basis for the residential scenario) or 

undeveloped land (the basis for the ROW scenario) for residential and ROW use patterns; 

therefore, differential amounts of runoff will occur within the watershed. The impervious 

scenario was developed to represent the paved areas within a watershed not including roads, 

parking lots, sidewalks, and buildings outside the 1⁄4 acre lot (the 1⁄4 acre lot scenario accounts for 

impervious surfaces such as buildings within the represented area). By modeling a separate 

scenario for impervious surfaces, it is also possible to estimate that amount of exposure that 

could occur when the pesticide is oversprayed onto this surface. Using two scenarios in tandem 

requires post-processing of the modeled output to derive a weighted EEC that represents the 

contribution of both the pervious (i.e., residential and ROW scenarios) and the impervious 

surfaces. A Microsoft Excel spreadsheet has been developed that allows for the weighting and 

aggregation of exposure from both scenarios. The daily time series from each model run should 

be copied from the times series file (NAME_TS.out) generated from the PRZM graphical user 

interface (PE5.pl) into the spreadsheet provided. The time series data are then weighted based 

on percentage of impervious surface, the percentage of the pervious surface treated, and an 

adjusted time series is created. Rolling averages for the relevant durations of exposure (e.g., 21-

day and 60-day averages) are calculated, and the relevant one-in-ten year return EEC is 

generated from these distributions.

For the purposes of risk assessment, it will be assumed that 1% of the application rate could 

reach the impervious surfaces surrounding each residential lot. This amount of overspray is not 

based on empirical data (no published studies on this occurrence have been found in the open 

literature). However, the assumption is consistent with the standard assumption of 1% spray

drift with ground applications in ecological risk assessments. In general, incorporation of 

impervious surfaces into the exposure assessment results in increasing runoff volume in the 

watershed, which tends to reduce overall pesticide exposure assuming 1% overspray to the 
-33 of 79-

impervious surface. Alternative assumptions for percent impervious surfaces, percentage of use 

site treated, and percentage of overspray may be considered in order to characterize the 

assumptions of the ecological risks assessment in the context of the individual exposure 

assessment and risk conclusions. For example, previously tested assumptions used in the 

endangered species assessments may be considered for characterization (i.e., 10% and 30% 

impervious surfaces,10% lot treated, and 0% and 10% overspray) unless other relevant values 

can be determined (i.e., modeling may be completed for the impervious surface with 0% and 

10% overspray to provide lower and upper bound values). The results of these alternate 

modeling exercises may be discussed in the assessment.

Given the aquatic toxicity of prallethrin and its likelihood to occur in sediment, the Agency may

also evaluate the potential toxicological exposures resulting from benthic/sediment 

concentrations (EECs). Pore water concentrations are commonly used to predict toxicity of nonionic substances in sediments and characterize exposure to organisms that spend time in or near 

sediments (Di Toro et al., 1991; USEPA, 2002). PRZM/ EXAMS estimates 1-in-10-year peak 

and 21-day mean EECs for pore water.

To estimate exposure related to releases of prallethrin from domestic wastewater treatment

plants, the Agency will rely on the Office of Pollution Prevention and Toxics (OPPT) model, 

Exposure and Fate Assessment Screening Tool (EFAST, version 2.0, or EFAST2, 2007). From 

this model, the Agency will use the “Down-the-Drain” module, which is designed for releases to 

domestic wastewater treatment. It is suitable for all the sources of prallethrin that could 

potentially occur through a “down-the-drain” scenario. The model provides screening-level 

estimate concentrations of chemicals in surface water that may result from household uses and 

the disposal of consumer products into wastewater using a few simple input parameters 

(production volume and fraction of the chemical removed during wastewater treatment).

8.2.3 Terrestrial Exposure

The model used to produce terrestrial EECs on food items is T-REX. Exposure estimates for 

terrestrial animals assumed to be in the target area or in an area exposed to spray drift are derived 

using the T-REX model (version 1.5, 3/22/2012). This model incorporates the Kenaga 

nomograph, as modified by Fletcher et al. (1994), which is based on a large set of actual field 

residue data. The upper limit values from the nomograph represent the 95th percentile of residue 

values from actual field measurements (Hoerger and Kenaga, 1972). The Fletcher et al. (1994) 

modifications to the Kenaga nomograph are based on measured field residues from 249 

published research papers, including information on 118 species of plants, 121 pesticides, and 17 

chemical classes. For input into T-REX, the default foliar dissipation half-life of 35 days will be 

used if there is insufficient foliar dissipation rate data on prallethrin. 

EECs for terrestrial plants inhabiting dry and wetland areas will be are derived using TerrPlant 

(version 1.2.2, 12/26/2006) using relevant reviewed registrant-submitted environmental fate data. 

This model uses estimates of pesticides in runoff and in spray drift to calculate EECs. EECs are 

based upon solubility, application rate, and minimum incorporation depth. 
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Prallethrin appears to have the potential to bioconcentrate in aquatic organisms. The maximum 

bioconcentration factor was 1160x for whole fish in 7 days and 3130x for non-edible tissue in 14 

days. A depuration study showed half-lives of 1.3-2.5 days (MRIDs 42810812, 43758001). The 

potential for bioaccumulation may be assessed using the results from bioaccumulation in fish 

studies as well as the KABAM model (KOW -based) Aquatic BioAccumulation Model, version 

1.0, 2009), adjusting for biotransformation rates. KABAM is used to estimate potential 

bioaccumulation of hydrophobic organic pesticides in freshwater aquatic ecosystems and risks to 

mammals and birds consuming aquatic organisms that have bioaccumulated these pesticides. 

Monitoring data and biotransformation rates in terrestrial species may also be evaluated to assess 

the potential for bioaccumulation in terrestrial food webs.

8.3 Measures of Effect

Ecological effects data are used as measures of direct and indirect effects to biological receptors. 

As discussed previously, data are obtained from registrant-submitted studies or from literature 

studies identified by ECOTOX. The ECOTOX database provides more ecological effects data in 

an attempt to bridge existing data gaps. ECOTOX is a source for locating single chemical 

toxicity data and potential chemical mixture toxicity data for aquatic life, terrestrial plants, and 

wildlife. ECOTOX was created and is maintained by the USEPA, Office of Research and 

Development, and the National Health and Environmental Effects Research Laboratory's MidContinent Ecology Division.

Information on the potential effects of prallethrin on non-target animals is also collected from the 

Ecological Incident Information System (EIIS; USEPA, 2007a). The EIIS is a database 

containing adverse effect (typically mortality) reports on non-target organisms where such 

effects have been associated with the use of pesticides. Incidents reported in the aggregate 

incident reports and the Avian Incident Monitoring System (AIMS) will also be searched. AIMS 

is a database administered by the American Bird Conservancy with partial funding from EPA. It 

contains publicly available data on reported avian incidents involving pesticides 

(http://www.abcbirds.org/abcprograms/policy/pesticides/aims/aims/index.cfm).

Where available, sub-lethal effects observed in both registrant-submitted and open literature 

studies will be evaluated qualitatively. Such effects may include behavioral changes (e.g., 

lethargy and changes in coloration). Quantitative assessments of risks, though, are limited to 

those endpoints that can be directly linked to the Agency’s assessment endpoints of impaired 

survival, growth and reproduction.

The assessment of risk for direct effects to non-target organisms makes the assumption that 

toxicity of prallethrin to birds is similar to terrestrial-phase amphibians and reptiles. The same 

assumption is made for fish and aquatic-phase amphibians. The acute measures of effect used 

for animals in this assessment are lethal dose (LD), lethal concentration (LC) or effective 

concentration (EC), such as: LD50, LC50, and EC50. The LD50 is the amount of a material, given 

all at once, that is estimated to cause the death of 50% of the test organisms. The LC50 is the 

concentration of a chemical that is estimated to kill 50% of the test organisms. The EC50 is the 

concentration of a chemical that is estimated to produce a specific effect in 50% of the test 

organisms. Endpoints for chronic measures of exposure for listed and non-listed animals are the 
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NOAEL and NOEC. NOAEL stands for “No Observed-Adverse-Effect-Level” and refers to the 

highest tested dose of a substance that has been reported to have no harmful (adverse) effects on 

test organisms. The NOEC is the No-Observed-Effects-Concentration. For non-listed plants, 

only acute exposures are assessed (i.e., EC25 for terrestrial plants and EC50 for aquatic plants); for 

listed plants either the NOEC or EC05 is used.

8.4 Integration of Exposure and Effects

Risk characterization is the integration of exposure and ecological effect characterizations to 

determine the potential ecological risk from the use of prallethrin and the likelihood of direct and 

indirect effects to non-target organisms in aquatic and terrestrial habitats. The exposure and 

effects data are integrated in order to evaluate potential adverse ecological effects on non-target 

species. For the prallethrin risk assessment, the risk quotient (RQ) method will be used to 

compare estimated exposure and measured toxicity values. Acute and chronic EECs will be 

divided by acute and chronic toxicity values. The resulting RQs will then be compared to the 

Agency’s Levels of Concern (LOC) (USEPA, 2004). These criteria are used to indicate when 

prallethrin’s use, as directed on the labels, has the potential to cause adverse direct or indirect 

effects to non-target organisms. In addition, incident data from EIIS, aggregate incident reports, 

and AIMS will be considered as part of the risk characterization.

8.5 Deterministic and Probabilistic Assessment Methods

The quantitative assessment of risk will primarily depend on the deterministic point estimatebased approach described in the risk assessment. Depending on the risk manager’s need for 

additional information regarding risk, an effort will be made to further qualitatively describe risk 

using probabilistic tools that the Agency has developed. These tools have been reviewed by 

FIFRA Scientific Advisory Panels (http://www.epa.gov/scipoly/sap/index.htm) and have been 

deemed as appropriate means of refining assessments where deterministic approaches have 

identified risks.

8.6 Endangered Species Assessments

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the 

Agency will evaluate risks to Federally-listed threatened and/or endangered (listed) species from 

registered uses of prallethrin. This assessment will be conducted in accordance with the 

Overview Document (USEPA, 2004), provisions of the ESA, and the Services’ Endangered 

Species Consultation Handbook (USFWS/NMFS, 1998).

The assessment of effects associated with the registration of prallethrin is based on an action 

area. The action area is considered to be the area directly or indirectly affected by the federal 

action, as indicated by the exceedance of Agency Levels of Concern (LOCs) used to evaluate 

direct or indirect effects. The Agency’s approach to defining the action area under the provisions 

of the Overview Document (USEPA, 2004) considers the results of the risk assessment process 

to establish boundaries for that action area with the understanding that exposures below the 

Agency’s defined LOCs constitute a no-effect threshold. For the purposes of this assessment, 

attention will be focused on the footprint of the action (i.e., the area where prallethrin application 
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occurs), plus all areas where offsite transport (i.e., spray drift, runoff, etc.) may result in potential 

exposure that exceeds the Agency’s LOCs. Specific measures of ecological effect that define the 

action area for listed species include any direct and indirect effects and/or potential modification 

of its critical habitat, including reduction in survival, growth, and reproduction as well as the full 

suite of sub-lethal effects available in the effects literature. Therefore, the action area extends to 

a point where environmental exposures are below any measured lethal or sub-lethal effect 

threshold for any biological entity at the whole organism, organ, tissue, and cellular level of 

organization. In situations where it is not possible to determine the threshold for an observed 

effect, the action area will be assumed to encompass the entire United States.

8.7 Drinking Water Assessment

A drinking water exposure assessment (DWA) may be conducted using up-to-date models and 

data during the risk assessment phase. The drinking water assessment will incorporate model 

estimates of prallethrin in surface and ground waters. Prallethrin concentrations in surface 

waters will be estimated using Tier II PRZM/EXAMS (see description in Section 7.2). There is 

no national default PCA for mosquito control applications. 

Ground water estimates of prallethrin concentrations will be established using SCI-GROW 

(v.2.3, July 2003, http://www.epa.gov/oppefed1/models/water/) (or PRZM-GW if it is available 

by the time the risk assessment is carried out). This is a regression model by fitting a linear 

model to ground water concentration with the Relative Index of Leaching Potential (RILP) as the 

independent variable. The model is used as a screening tool for ground water. The RILP is 

function of aerobic soil metabolism and the soil-water partition coefficient. The output of 

SCIGROW represents the concentrations that might be expected in shallow unconfined aquifers 

under sandy soils. The DWA will also include available surface and ground water monitoring 

data, with consideration of changes in use patterns since mitigations have been imposed. Ground 

water concentrations will be taken from 90-day average high concentrations from perspective 

ground water studies. States and mosquito control communities are encouraged to submit the 

monitoring data for the water quality risk assessment.

8.8 Endocrine Disruptor Screening

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 the most recent registration decision, 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), prallethrin is subject to the 

endocrine screening part of the Endocrine Disruptor Screening Program (EDSP). 
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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 must screen all pesticide chemicals. Between 

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

chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. Prallethrin 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 callins, requiring the submission of EDSP screening assays for prallethrin. 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/.

9. Preliminary Identification of Data Gaps

The following two sections, 9.1 and 9.2 identify the remaining fate and effect studies needed to 

complete an environmental fate and ecological risk assessment in support of the registration 

review of the labeled uses of prallethrin. Draft Data Call-In (DCI) tables for requested data are 

provided in Appendix G. In addition to providing the guideline number and study title, the DCI 

tables provide a rationale for requiring the data, an explanation of how the data will be used, and 

a brief description of the how the data could impact the Agency’s future decision-making. 

9.1 Environmental Fate Data

Table 9-1 identifies environmental fate studies for prallethrin by MRID that offer data for each 

guideline requirement, as well as study classifications and data deficiencies (i.e., whether there is 

a data gap). Since prallethrin is not registered for agricultural use, no additional data on 

terrestrial and aquatic field dissipation will be requested at this time. Data will be waived for the 

major degradates because they are the result of the cleavage of the ester linkage of the parent. 

This breaking of the basic pyrethroid frame or backbone may result in lost activity and thus 

decreased toxicity when compared with the parent. Should the registrant wish to add new uses 

of this chemical or other new evidence of toxicological issues is raised for the degradates, the 

data requirements may be reassessed. 

The following data are needed to correct data deficiencies for the ecological exposure

assessment:
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 Guideline 835.4200 – Anaerobic Soil Metabolism: No study for anaerobic soil 

metabolism has been found for prallethrin. The registrant is required to perform an 

anaerobic soil metabolism study in three different soils to fulfill current OPPTS 

guidelines 835.4200 and to address the data deficiency for anaerobic soil metabolism. 

The studies will provide half-lives in different soil systems, resulting in more knowledge 

and certainty related to the behavior and persistence of prallethrin in anaerobic soils. 

 Guideline Number 835.1230 – Adsorption/Desorption (Batch Equilibrium): One 

available study was performed in the test soils that were autoclaved before use, thus 

possibly altering the physical and chemical properties of the soils, the registrant must 

demonstrate that autoclaving the soil did not influence the results of this study, and that 

the observed results are an accurate representation of prallethrin adsorption/desorption 

from soil or submit a new study. The registrant is required to perform an 

adsorption/desorption study according to current OPPTS guidelines 835.1230. The 

studies will obtain a sorption value which can be used to predict partitioning under a 

variety of environmental conditions. The data at concentrations resulting from labeled 

application rates will facilitate a better understanding of prallethrin mobility in the 

environment. 

Table 9-1. Environmental Fate Data Requirement Table for Prallethrin.

Guideline Description MRID/

Accession Classification Data Gap? Comments

835.2120 Hydrolysis 42838602 Acceptable No

835.2240 Aqueous photolysis 43797601 Acceptable No

835.2410 Soil photolysis

43797602 

and 

43797603

Acceptable No

835.4100 Aerobic soil metabolism 42838601 Acceptable No

835.4200 Anaerobic soil 

metabolism - - Yes 

Data are needed for sediment-water 

systems, one each at a neutral and an 

acidic pH. 

835.4300 Aerobic aquatic 

metabolism

44861001

and

44861002

Supplemental

and

Supplemental

No

835.4400 Anaerobic aquatic 

metabolism

44366601

and

44366602

Supplemental

and

Supplemental

No

835.1230 Adsorption/ desorption 

and leaching 42810801 Unacceptable Yes

Because the test soils were autoclaved 

before use, thus possibly altering the 

physical and chemical properties of 

the soils, the registrant must 

demonstrate that autoclaving the soil 

did not influence the results of this 

study, and that the observed results 

are an accurate representation of 

prallethrin adsorption/desorption from 

soil. 
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Guideline Description MRID/

Accession Classification Data Gap? Comments

835.6100

Terrestrial field 

dissipation -- -- -- Data are not required at this time.

Freezer storage stability

Analytical method – soil

Analytical method – water

Analytical method -

sediment

850.1730 Fish bioconcentration

42810802

and 

43758001

Acceptable No

9.2 Ecological Effects Data

Tables 9-2, 9-3, and 9-4 identify ecological effects studies by MRID for aquatic animals, 

terrestrial animals, and plants (terrestrial and aquatic), respectively, that offer data for each 

guideline requirement, as well as study classifications and whether or not further data are needed 

in order to support risk assessment (i.e., whether there is a data gap). Data on the major 

degradates of prallethrin will be waived at this time because the Agency considers the degradates 

to be the outcome of cleavage of the ester linkage of the parent. This breaking of the basic 

pyrethroid frame or backbone may result in lost activity and thus decreased toxicity when 

compared with the parent. Should the registrant wish to add new uses of this chemical, the data 

requirement may be reassessed.

Submission of data to eliminate data gaps would reduce uncertainties in the ecological effects 

assessment. Data gaps were assigned either a low or high potential to add value to an ecological 

effects assessment. While still considered data gaps according to 40 CFR Part 158, low potential 

studies are unlikely to change risk determinations because alternate methods and weight of 

evidence may possibly be used in the absence of data. High potential studies would enable the 

Agency to better characterize potential risks by eliminating uncertainties for both non-listed and 

listed species that cannot be accounted for using alternate methods or weights of evidence.

Data from the following guideline studies are considered to have high potential to add value to 

the ecological risk assessment for prallethrin:

 Guideline 850.4225 – Seedling emergence, Tier II (TEP): In the Tier I seedling 

emergence study with MULTICIDE Fogging Concentrate 2798 (Reg No. 1021-1795), an 

inhibition of greater than 25% was observed for sugarbeet emergence (32.4%). 

Therefore, a Tier II seedling emergence test with sugarbeets is requested. In the same 

study, the mean of the treated group was significantly less than the mean of the control 

group for the following species and endpoints: tomato emergence; wheat dry weight; and 

soybean dry weight. Therefore, a NOEC could be determined for these species, and Tier 

II seedling emergence tests are recommended for tomato, wheat, and soybean to reduce 

uncertainty in determining risk to endangered plants.
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 Guideline Number: 850.1020 – Gammarid Acute Toxicity (TEP): Acute toxicity data 

of prallethrin TEPs with the synergists PBO and MGK-264 are requested for freshwater 

invertebrates because there are registered outdoor uses of prallethrin that may result in 

significant exposure to water bodies. Products with these synergists are likely to cause 

increased toxicity to non-target aquatic species. This is supported by an acute toxicity

study with the most sensitive aquatic species, the mysid shrimp, and the TEP 

MULTICIDE Fogging Concentrate 2798 (Reg No. 1021-1795) which contains dphenothrin and PBO. Results indicate that the MULTICIDE Fogging Concentrate 2798

is three orders of magnitude more toxic than TGAI prallethrin (96-hr LC50 = 22 μg a.i./L

with TGAI; LC50 = 0.0079 μg a.i./L with TEP; see Section 4.1). Since available 

information indicates that greater toxicity enhancement can occur at higher synergist-toactive ingredient ratios, selection of the TEPs for testing should include those TEPs with 

the highest synergist-to-active ingredient ratio and are registered for outdoor uses. 

The recommended freshwater invertebrate test species is the amphipod, Hyalella azteca. 

H. azteca is recommended over other standard test species (e.g., Daphnia magna) due to 

its much greater sensitivity to pyrethroids compared to D. magna. Hyalella is also a 

recommended test species for sediment toxicity testing which enables toxicity

extrapolations to be made among water column and benthic exposures within the same 

species. The 850.1020 test guideline for Gammarid amphipods is recommended with 

appropriate modifications to address specific testing needs of H. azteca. The registrant 

should submit a test protocol prior to conducting these TEP studies that documents the 

rationale for the TEP selection and details of the testing procedure for H. azteca. 

The Agency notes that the ratios of synergist (PBO or MGK-264) to prallethrin expected 

in the aquatic environment may be much greater than those used in the formulated 

products, due in part to the different fate properties of the synergists and prallethrin. As 

available data suggest greater toxicity enhancement can occur at higher synergist-toactive ingredient ratios, it is possible that greater toxicity enhancement may occur in the 

natural environment compared to that measured for formulated products. To address this 

concern, the Agency will attempt to bridge results from ongoing “comprehensive” 

synergist testing at varying synergist-to-active ingredient ratios to address varying ratios 

of PBO/MGK-264 to prallethrin that are expected to occur in aquatic ecosystems. 

However, should the available data be insufficient to enable scientifically defensible 

bridging to be conducted at the time of the forthcoming prallethrin ecological risk 

assessment, the Agency may apply a “conservative” toxicity enhancement factor to 

address the uncertainty regarding differences in synergist-to-prallethrin ratios in the 

aquatic environment versus those tested using formulated products. The registrant may

wish to submit additional data on prallethrin/synergist toxicity at varying ratios that 

would be expected to occur in the aquatic environment to address this potential 

uncertainty.

 Guideline Number: 850.1075 – Acute Freshwater Fish Toxicity (TEP): Acute toxicity

data of prallethrin TEPs with the synergists PBO and MGK-264 are requested for 

freshwater invertebrates because there are registered outdoor uses of prallethrin that may 

result in significant exposure to water bodies. Products with these synergists are likely to 
-41 of 79-

cause increased toxicity to non-target aquatic species as demonstrated by the mysid acute 

toxicity study with the TEP MULTICIDE Fogging Concentrate 2798 (Reg No. 1021-

1795). Since available information indicates that greater toxicity enhancement can occur 

at higher synergist-to-active ingredient ratios, selection of the TEPs for testing should 

include those with the highest synergist-to-active ingredient ratio and are registered for 

outdoor uses. The registrant should submit a test protocol prior to conducting these TEP 

studies that documents the rationale for the TEP selection. The Agency notes that the 

ratios of synergist (PBO or MGK-264) to prallethrin in the aquatic environment that may

be much greater than those used in the formulated products, due in part to the different 

fate properties of the synergists and prallethrin. As available data suggest greater toxicity

enhancement can occur at higher synergist-to-active ingredient ratios, it is possible that 

greater toxicity enhancement may occur in the natural environment compared to that 

measured for formulated products. To address this concern, the Agency will attempt to 

bridge results from ongoing “comprehensive” synergist testing at varying synergist-toactive ingredient ratios to address varying ratios of PBO/MGK-264 to prallethrin that are 

expected to occur in aquatic ecosystems. However, should the available data be 

insufficient to enable scientifically defensible bridging to be conducted at the time of the 

forthcoming prallethrin ecological risk assessment, the Agency may apply a 

“conservative” toxicity enhancement factor to address the uncertainty regarding 

differences in synergist-to-prallethrin ratios in the aquatic environment vs. those tested 

using formulated products. The registrant may wish to submit additional data on

prallethrin/synergist toxicity at varying ratios that would be expected in the aquatic 

environment to address this potential uncertainty.

 Guideline 850.1350 – Aquatic invertebrate life cycle (saltwater): Aquatic invertebrate 

life cycle toxicity data have not been submitted for an estuarine/marine species creating 

uncertainty for estimating risk to these organisms from chronic exposure to prallethrin. 

In addition, acute toxicity data show that the mysid shrimp is the most sensitive aquatic 

animal. In the absence of this data, approaches that may be used to estimate toxicity to 

estuarine/marine invertebrates from chronic exposure to prallethrin include using 

estuarine/marine invertebrate toxicity data for other pyrethroids to extrapolate from 

existing acute toxicity data for estuarine/marine invertebrates and/or applying an acute to 

chronic ratio (ACR) for freshwater invertebrates to existing acute toxicity data for 

estuarine/marine invertebrates. 

 Guideline 850.5400 – Aquatic plant growth (algal): Algal toxicity data have not been 

submitted creating uncertainty for estimating risk to algal species from exposure to 

prallethrin. In the absence of this data, algal and aquatic vascular plant toxicity data for 

other pyrethroids may be used to extrapolate from the available toxicity data for aquatic 

vascular plants to aquatic non-vascular species.

Data from the following guideline studies are considered to have low potential to add value to 

the ecological risk assessment for prallethrin:

 Guideline 850.2100 – Avian oral toxicity (passerine species): Acute avian oral toxicity

data are required for either one waterfowl or one upland game species and one passerine 
-42 of 79-

species under the 40 CFR Part 158 (CFR 40 2008) data requirements for conventional 

pesticides. Data have not been submitted for a passerine species. The most recent 

Agency ecological risk assessment to address the risk of prallethrin use to birds found 

that no acute or chronic LOCs for birds were exceeded (D23929, D291569, D257565). 

Estimating EECs in T-REX using conservative estimates for number of applications (i.e., 

142) and application interval (i.e., 1 day) for a typical outdoor individual application rate 

of prallethrin (i.e., 0.0014 lb a.i./A; 142*0.0014 lb a.i./A = ~0.2 lb a.i./A [maximum 

application rate/year]) indicates that passerines would have to be at least 5 times more 

sensitive to prallethrin to alter risk conclusions, and this would only be for acute 

exposures of small birds consuming short grass exclusively. For all other feeding guilds, 

passerines would have to be 10 to 100 times more sensitive to alter risk conclusions. In

the absence of this data, acute passerine oral toxicity data from other pyrethroids may be 

used to extrapolate the toxicity of prallethrin to passerine species.

 Guideline 850.1400 – Fish early-life stage (saltwater): Fish early-life stage toxicity

data have not been submitted for an estuarine/marine species. In the absence of this data, 

an acute to chronic ratio (ACR) for freshwater fish may be applied to existing acute data 

for estuarine/marine fish to estimate toxicity to estuarine/marine fish from chronic 

exposure to prallethrin.

 Guideline 850.1500 – Fish life cycle (freshwater and saltwater): Fish life cycle 

toxicity data have not been submitted for a freshwater species or estuarine/marine 

species. In the absence of this data, data from the acceptable fish early-life stage toxicity

study (MRID 44729604) may be used to characterize risk to fish from chronic exposure 

to prallethrin.

Table 9-2. Available Ecological Effects Data for Aquatic Animals Exposed to Prallethrin

and Remaining Data Gaps.

Guideline Description MRID/ Accession Classification Data 

Gap? Comments

850.1010 Acute toxicity 

freshwater invertebrates 

41321810 (TGAI)

 -- (TEP)

Acceptable

--

No

Yes

Data are requested for a 

TEP with prallethrin and 

synergist, using Hyalella 

azteca as the test species.

850.1025

850.1055

Acute toxicity

estuarine/marine mollusk 44729601 (TGAI) Acceptable No

850.1035

850.1045

Acute toxicity

estuarine/marine 

invertebrate

44729603 (TGAI)

48055901 (TEP)

Acceptable

Acceptable No

850.1075

Acute freshwater fish 

toxicity

(cold water species)

41321809 (TGAI)

 -- (TEP)

Acceptable

--

No

Yes

Data are requested for a 

TEP with prallethrin and 

synergist.
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Guideline Description MRID/ Accession Classification Data 

Gap? Comments

Acute freshwater fish 

toxicity 

(warm water species)

41321808 (TGAI)

 -- (TEP)

Acceptable

--

No

Yes

850.1075 Acute toxicity

estuarine/marine fish 44729602 (TGAI) Acceptable No

850.1300

Aquatic invertebrate

life cycle

(freshwater)

44729605 (TGAI) Acceptable No

850.1350

Aquatic invertebrate

life cycle

(saltwater)

-- -- Yes

Aquatic invertebrate life 

cycle toxicity data for an 

estuarine/marine species 

are required under 40 CFR 

Part 158 if the product is 

expected to enter the 

environment in significant 

concentrations because of 

its expected use or 

mobility patterns. 

Therefore, this is identified 

as a data gap.

850.1400 Fish early-life stage

(freshwater) 44729604 (TGAI) Acceptable No

850.1400 Fish early-life stage

(saltwater) -- -- Yes

Fish life cycle toxicity data 

for an estuarine/marine 

species are required under 

40 CFR Part 158 if the 

product is expected to 

enter the environment in 

significant concentrations 

because of its expected use 

or mobility patterns. 

Therefore, this is identified 

as a data gap.

850.1500 Fish life cycle

(freshwater) -- -- Yes

Fish life cycle toxicity data 

for a freshwater species are 

required under 40 CFR 

Part 158 if the product is 

expected to be transported 

to water from the intended 

use site. Therefore, this is 

identified as a data gap.
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Guideline Description MRID/ Accession Classification Data 

Gap? Comments

Fish life cycle

(saltwater) -- -- Yes

Fish life cycle toxicity data 

for an estuarine/marine 

species are required under 

40 CFR Part 158 if the 

product is expected to 

enter the environment in 

significant concentrations 

because of its expected use 

or mobility patterns. 

Therefore, this is identified 

as a data gap.

850.1735

850.1740

Whole sediment:

acute invertebrates

(freshwater and marine)

47762401 (TGAI) Supplemental No

For MRID 47762401, there 

is uncertainty regarding the 

accuracy of the LC50

values given potential 

interference from the 

solvent. Repeating this 

study has a low potential to 

add value to the ecological 

risk assessment. 

Table 9-3. Available Ecological Effects Data for Terrestrial Animals Exposed to 

Prallethrin and Remaining Data Gaps.

Guideline Description MRID/

Accession

Classification Data 

Gap?

Comments

850.2100

Avian oral toxicity 

(upland game or 

waterfowl species)

41321804 (TGAI)

41321805 (TGAI)

Supplemental

Acceptable No

Avian oral toxicity

(passerine species) -- -- Yes

Avian acute oral toxicity 

data are not available for 

passerines. These data are 

required under the new 40 

CFR Part 158. Therefore, 

this is identified as a data 

gap.

850.2200

Avian dietary toxicity 

(upland game species) 41321806 (TGAI) Acceptable No

Avian dietary toxicity 

(waterfowl species) 41321807 (TGAI) Acceptable No

850.2300

Avian reproduction 

(upland game species) 43773403 (TGAI) Acceptable No

Avian reproduction 

(waterfowl species) 43797604 (TGAI) Acceptable No

850.3020 Honeybee acute contact 

toxicity 41321823 (TGAI) Acceptable No

850.3030 Honeybee toxicity of 

residues on foliage

43749301 (Form)

47431601 (TEP)

Acceptable

Acceptable No
-45 of 79-

Form = formulation

Table 9-4. Available Ecological Effects Data for Plants Exposed to Prallethrin and 

Remaining Data Gaps.

Guideline Description MRID Classification Data 

Gap? Comments

850.4100

Tier I 

Seedling emergence 

(terrestrial plants)

47431602 

(TEP) Acceptable No

In the Tier I seedling emergence 

study, an inhibition of greater than 

25% was observed for sugarbeet 

emergence (32.4%). Therefore, a 

Tier II seedling emergence test 

with sugarbeets is necessary. In the 

same study, the mean of the treated 

group was significantly less than 

the mean of the control group for 

the following species and 

endpoints: tomato emergence; 

wheat dry weight; and soybean dry 

weight. Therefore, a NOEC could 

be determined for these species, 

and Tier II seedling emergence 

tests are recommended for tomato, 

wheat, and soybean to reduce 

uncertainty in determining risk to 

endangered plants.

850.4225

Tier II 

Seedling emergence 

(terrestrial plants)

-- -- Yes

850.4150

Tier I 

Vegetative vigor 

(terrestrial plants) 

47431603 

(TEP) Acceptable No

850.4400

Tier II 

Aquatic plant growth 

(aquatic vascular plant 

toxicity)

48055902 

(TEP) Acceptable No

850.5400

Tier I 

Aquatic plant growth

(algal toxicity)

-- -- Yes

Toxicity data for algal species are 

required under 40 CFR Part 158. 

Therefore, this is identified as a 

data gap.

10. References

Addy-Orduna, L.M., M-E. Zaccagnini, S.B. Canavelli, and P. Mineau. 2001. Formulated betacyfluthrin shows wide divergence in toxicity among bird species. Journal of Toxicology 2011, 

Article ID 803451: 10 pages.

Amweg, E.L., D.P. Weston, C.S. Johnson, J. You, and M.L. Lydy. 2006. Effect of Piperonyl

Butoxide on Permethrin Toxicity in the Amphipod Hyalella azteca. Environ. Tox. Chem. 25 (7): 

1817-1825.
-46 of 79-

Amweg, E.L. and D.P. Weston. 2007. Whole-Sediment Toxicity Identification Evaluation 

Tools for Pyrethroid Insecticides: I. Piperonyl Butoxide Addition. Environ. Toxicol. & Chem., 

Vol. 26, No. 11, pp. 2389–2396, 2007.

Barile, F.A. 2004. Clinical Toxicology: Principles and Mechanisms. Boca Raton, FL: CRC 

Press.

Di Toro, DM, CS Zarba, DJ Hansen, WJ Berry, RC Swartz, CE Cowan, SP Pavlou, HE Allen,

85 NA Thomas and PR Paquin. 1991. Technical basis for establishing sediment quality criteria 

for nonionic organic chemicals using equilibrium partitioning. Environ. Toxicol. Chem. 10:1541-

1583.

Doull, J. 1976. The Treatment of Insecticide Poisoning. Ch. 16 in: C.F. Wilkinson (ed.), 

Insecticide Biochemistry and Physiology. 753 pp. Plenum Press, New York.

Fletcher, J.S., J.E. Nellessen, and T.G. Pfleeger. 1994. Literature review and evaluation of the 

EPA food-chain (Kenaga) nomogram, an instrument for estimating pesticide residues on plants. 

Environ. Tox. Chem. 13:1383-1391.

Hodgson, E., & Smart, R. C. (Eds.). 2001. Introduction to Biochemical Toxicology (Third ed.). 

New York: Wiley-Interscience.

Hoerger, F. and E. E. Kenaga. 1972. Pesticide Residues on Plants: Correlation of 

Representative Data as a Basis for Estimation of their Magnitude in the Environment. In F. 

Coulston and F. Korte, eds., Environmental Quality and Safety: Chemistry, Toxicology, and 

Technology, Georg Thieme Publ., Stuttgart, West Germany, pp. 9-28.

Narahashi, T. 1976. Effects of Insecticides on Nervous Conduction and Synaptic Transmission. 

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

New York.

Stewart, D. 1998. The Evaluation of Synergistic Action in the Laboratory and Field. p. 173-198 

In: Piperonyl Butoxide: the Insecticide Synergist. Academic Press.

USEPA. 1998. Guidelines for Ecological Risk Assessment. Risk Assessment Forum, Office of 

Research and Development, Washington, D.C. EPA/630/R-95/002F. April 1998. 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=30759

USEPA 2003, Tier I Estimated Environmental Concentrations of Prallethrin in Drinking 

Waters, Proposed New Uses in Outdoor Residential and Recreational Areas (PC Code 128722; 

DP Barcode D274758) Trade Names: Fogging Concentration 2798 RESPONDÉ®Insecticide.

USEPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and Toxic 

Substances, Office of Pesticide Programs, Washington D.C. January 23, 2004.
-47 of 79-

USEPA. 2007a. Ecological Incident Information System. 

http://www.epa.gov/espp/consultation/ecorisk-overview.pdf

USEPA. 2007b. ECOTOXicology Database. Office of Research and Development National 

Health and Environmental Effects Research Laboratory’s (NHEERL’s) Mid-Continent Ecology

Division (MED). http://cfpub.epa.gov/ecotox/

USEPA. 2011. BEAD Chemical Profile for Registration Review: Prallethrin (PC # 128722). 

Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, 

Biological and Economic Analysis Division. December 28, 2011.

U.S. Fish and Wildlife Service (USFWS) and National Marine Fisheries Service (NMFS). 1998. 

Endangered Species Consultation Handbook: Procedures for Conducting Consultation and 

Conference Activities Under Section 7 of the Endangered Species Act. Final Draft. March 

1998.

USFWS/NMFS/NOAA. 2004. 50 CFR Part 402. Joint Counterpart Endangered Species Act 

Section 7 Consultation Regulations; Final Rule. Federal Register Volume 69. Number 20.Pages 

47731-47762. August 5, 2004.

Weston, D.P. Amweg, E.L., Mekebri, A., Ogle, R.S. and M.J. Lydy. 2006. Aquatic effects of 

aerial spraying for mosquito control over an urban area. Environ. Sci. Technol. 40(18): 5817-22.

Weston, D.P. and M.J. Lydy. 2010. Urban and Agricultural Sources of Pyrethroid Insecticides 

to the Sacramento-San Joaquin Delta of California. Environ. Sci. Technol. 2010, 44, 1833–1840.
-48 of 79-

SUBMITTED ENVIRONMENTAL FATE STUDIES:

02048544 Fate One-liner Report

42810801 Archer, G. (1991) Adsorption and Desorption of Etoc to Soils: Lab Project 

Number: 90-0403: FFM-11-0007: 3742-90-0403-EF-001. Unpublished study

prepared by Ricerca, Inc. 160 p. 

42810802 Ohshima, M.; Yoshida, S. (1991) Uptake, Depuration and Bioconcentration of 

(Alc-(carbon 14))-d-trans-Etoc by Bluegill Sunfish (Lepomis Macrochirus): Lab 

Project Number: ACC91002: FFM-10-0006: ACC91002-A. Unpublished study

prepared by Environmental Health Science Lab. 78 p. 

42838601 Korsch, B. (1991) An Aerobic Soil Metabolism Study with Etoc: Lab Project 

Number: 90-0404: FFM-11-0008: 3741-90-0404-EF-001. Unpublished study

prepared by Ricerca, Inc. 309 p. 

42838602 Kieatiwong, S.; Shepler, K.; Ruzo, L. (1991) Hydrolysis of (Alc-(carbon 14))-dtrans-Etoc at pH 5, 7 and 9: Lab Project Number: 262W: FFM-11-0005. 

Unpublished study prepared by Pharmacology and Toxicology Research Lab--

West. 82 p. 

43797601 Kieatiwong, S.; Shepler, K.; Ruzo, L. (1995) Sunlight Photodegradation of (AlcCarbon 14)-d-trans-Etoc in a Buffered Aqueous Solution at pH 5: Amended 

Report: Lab Project Number: 263W-1: 263W. Unpublished study prepared by

PTRL-West Inc. and Sumitomo Chemical Co., Ltd. 113 p. 

43797602 Kieatiwong, S.; Shepler, K.; Ruzo, L. (1995) Sunlight Photodegradation of (AcidCarbon 14)-d-trans-Etoc in/on Soil by Natural Sunlight: Amended Report: Lab 

Project Number: 273W-1: 273W. Unpublished study prepared by PTRL-West,Inc. 

and Sumitomo Chemical Co., Ltd. 107 p. 

43797603 Kieatiwong, S.; Shepler, K.; Ruzo, L. (1995) Sunlight Photodegradation of (AlcCarbon 14)-d-trans-Etoc in/on Soil by Natural Sunlight: Amended Report: Lab 

Project Number: 272W-1: 272W. Unpublished study prepared by PTRL-West, Inc. 

and Sumitomo Chemical Co., Ltd. 113 p. 

43758001 Ohshima, M.; Mikami, N. (1993) Characterization of (Carbon 14) Residues in 

Bluegill Sunfish Treated with (Alc-(Carbon 14))-d-trans-Etoc: Lab Project 

Number: ACC91002: ACC91002-B: FFM-30-0012. Unpublished study prepared 

by Sumitomo Chemical Co., Ltd. 102 p. 

44366601 Archer, G. (1996) An Anaerobic Aquatic Soil Metabolism Study with (Acidcarbon 14)-Etoc: Lab Project Number: FFM-0013: 3838-91-0423-EF-001: 3838. 

Unpublished study prepared by Ricerca, Inc. 125 p. 

44366602 Archer, G. (1996) An Anaerobic Aquatic Soil Metabolism Study with ?ALCcarbon-14|-Etoc: Lab Project Number: 3838: 3838-91-0318-EF-001: FFM-0014. 

Unpublished study prepared by Ricerca, Inc. 142 p. 

44861002 Kaman, R. (1999) Aerobic Aquatic Soil Metabolism of (Cyclopentenyl-2-(carbon-
-49 of 79-

14))-d-trans-Prallethrin: Lab Project Number: 7433-98-0012-EF-001: 7433-98-

0012-EF-000: 7433-98-0012-EF-000-001. Unpublished study prepared by Ricerca, 

Inc. 133 p. 

46433101 Habig, C. (2004) AgDrift and PRZM-EXAMS Modeling of Low Alititude 

Applications of Prallethrin For Adult Mosquito Control. Project Number: 

7/000/C0T0/11/04/001. Unpublished study prepared by registrant. 11 p.

SUBMITTED EFFECTS STUDIES:

41321804 Grimes, J.; Jaber, M. (1989) S-4068SF: An Acute Oral Toxicity Study with the 

Mallard: (ETOC): Study ID No. 720001; Project No. 166-127; Report FFW-91-0007. 

Unpublished study prepared by Wildlife International Ltd. 19 p. 

41321805 Grimes, J.; Jaber, M. (1989) S-4068SF: An Acute Oral Toxicity Study with the 

Bobwhite: (ETOC): Final Report: Lab Project No. 166-126; Report FFW-91-0006; 

Study ID No. 710001. Unpublished study prepared by Wildlife International Ltd. 20 

p. 

41321806 Grimes, J.; Jaber, M. (1989) S-4068SF: A Dietary LC50 Study with the Bobwhite: 

(ETOC): Lab Project Number 166-124; Report FFW-91-0008; Study ID No. 730001. 

Unpublished study prepared by Wildlife International Ltd. in cooperation with EnCas Analytical Laboratories. 28 p. 

41321807 Grimes, J.; Jaber, M. (1989) S-4068SF: A Dietary LC50 Study with the Mallard: 

(ETOC): Study ID No. 740001; Report FFW-91-0009; Project No. 166-125. 

Unpublished study prepared by Wildlife International Ltd. in cooperation with EnCas Analytical Laboratories. 27 p. 

41321808 Bowman, J. (1989) Acute Flow-through Toxicity of ETOC (Prallethrin) to Bluegill 

(Lepomis macrochirus): Final Report: Study ID Nos. 37777; 037777; Report No. 

FFW-91-0003. Unpublished study prepared by Analytical Bio-chemistry

Laboratories, Inc. 176 p. 

41321809 Bowman, J. (1989) Acute Flow-through Toxicity of ETOC to Rainbow Trout (Salmo 

gairdneri): Final Report: Study ID Nos. 37778; 037778; Report No. FFW-91-0004. 

Unpublished study prepared by Analytical Bio-chemistry Laboratories, Inc., Aquatic 

Toxicology Div. 183 p. 

41321810 Burgess, D. (1989) Acute Flow-through Toxicity of ETOC to Daphnia magna: Final 

Report: Study ID Nos. 37779; 037779; Report No. FFW-91-0010. Unpublished study

prepared by Analytical Bio-chemistry Laboratories, Inc. 169 p. 

41321828 Hoxter, K.; Thompson, M.; Jaber, M. (1989) S-4068SF: (ETOC): An Acute Contact 

Toxicity Study with the Honey Bee: Lab Project Number 166-130; Ref. No. FFW91-0012. Unpublished study pre- pared by Wildlife International Ltd. 18 p. 

43749301 Harnish, W. (1995) Final Report for the Evaluation of Toxicity of Residues of 

LX119-04 (ETOC) on Alfalfa to Honey Bees (Apis mellifera): Lab Project Number: 

01921F004: FFW-51-0023. Unpublished study prepared by Landis International, Inc. 
-50 of 79-

23 p. 

43773403 Beavers, J.; Sipler, O.; Marselas, G.; et al. (1994) ETOC: A Reproduction Study with 

the Bobwhite: Lab Project Number: 166-148: FFW-41-0019. Unpublished study

prepared by Wildlife International Ltd. 166 p. 

43797604 Beavers, J.; Sipler, O.; Marselas, G. et al. (1994) ETOC: A Reproduction Study with 

the Mallard: Lab Project Number: 166-149: FFW-41-0020. Unpublished study

prepared by Wildlife International, Ltd. 161 p. 

44729601 Dionne, E. (1998) ETOC--Acute Toxicity to Eastern Oyster (Crassostrea virginica) 

Under Flow-Through Conditions: Final Report: Lab Project Number: FFW-0028: 98-

7-7386: 13048.1097.6149.504. Unpublished study prepared by Springborn 

Laboratories, Inc. 78 p. 

44729602 Dionne, E. (1998) ETOC--Acute Toxicity to Sheepshead Minnow (Cyprinodon 

variegatus) Under Flow-Through Conditions: Final Report: Lab Project Number: 

FFW-0027: 98-5-7337: 13048.1097.6147.505. Unpublished study prepared by

Springborn Laboratories, Inc. 76 p. 

44729603 Dionne, E. (1998) ETOC--Acute Toxicity to Mysids (Mysidopsis bahia) Under 

Flow-Through Conditions: Final Report: Lab Project Number: FFW-0025: 98-3-

7288: 13048.1097.6148.515. Unpublished study prepared by Springborn 

Laboratories, Inc. 77 p. 

44729604 Sousa, J. (1998) ETOC--Early Life-Stage Toxicity Test with Rainbow Trout 

(Oncorhynchus mykiss): Final Report: Lab Project Number: 98-4-7295: 

13048.1097.6150.121: FFW-0026. Unpublished study prepared by Springborn 

Laboratories, Inc. 101 p. 

44729605 Putt, A. (1998) ETOC--The Chronic Toxicity to Daphnia magna Under FlowThrough Conditions: Final Report: Lab Project Number: 98-2-7236: 

13048.1097.6151.130: FF-0024. Unpublished study prepared by Springborn 

Laboratories, Inc. 99 p. 

47431601 Sindermann, A.; Porch, J.; Krueger, H. (2008) Multicide Fogging Concentrate 2798: 

A Foliage Residue Toxicity Study with the Honeybee: Final Report. Project Number: 

163/123, 163/080107/BFR/SUB16. Unpublished study prepared by Wildlife 

International Ltd. 37 p.

47431602 Porch, J.; Krueger, H. (2008) Multicide Fogging Concentrate 2798: A Toxicity Test 

to Determine the Effects of the Test Substance on Seedling Emergence of Ten 

Species of Plants: Final Report. Project Number: 163/124. Unpublished study

prepared by Wildlife International Ltd. 58 p.

47431603 Porch, J.; Krueger, H. (2008) Multicide Fogging Concentrate 2798: A Toxicity Test 

to Determine the Effects of the Test Substance on Vegetative Vigor of Ten Species 

of Plants: Final Report. Project Number: 163/125. Unpublished study prepared by

Wildlife International Ltd. 79 p.

47762401 Putt, A. (2007) ETOC - Toxicity to Freshwater Amphipods (Hyalella azteca) During 
-51 of 79-

a 10-Day Sediment Exposure. Project Number: 13048/6522, FFW/0029. 

Unpublished study prepared by Springborn Smithers Laboratories. 94 p.

48055901 Gallagher, S.; Krueger, H. (2009) Multicide 2798: A 96-Hour Flow-Through Acute 

Toxicity Test with the Saltwater Mysid (Americamysis bahia): Final Report. Project 

Number: 163A/101. Unpublished study prepared by Wildlife International, Ltd. 141 

p.

48055902 Porch, J.; Cartee, T.; Krueger, H. (2009) Multicide 2798: A 7-Day Static-Renewal 

Toxicity Test with Duckweed (Lemna gibba G3): Draft Report. Project Number: 

163A/102, 090326. Unpublished study prepared by Wildlife International, Ltd. 147 

p.
-52 of 79-

Appendix A

Previous Actions and Assessed Uses for Prallethrin

Use Application Rate 

(lb a.i./A)

Number of 

Applications 

(Application 

Interval in Days)

Action

DP Barcode

Date

Risk Conclusions

Single Seasonal/ 

Annual

Outdoor residential and 

recreational areas for the 

control of adult nuisance 

insects (e.g., mosquitoes, 

midges, gnats, black flies, 

etc.)

0.0008* NS NS

(7)

Registration

(Reassessment)

D312733

5/26/05

 Use is not likely to pose risk to freshwater or 

estuarine/marine organisms (including sedimentdwelling organisms) from acute exposure regardless of 

depth of water body.

0.0008* NS NS Registration 

(Reassessment)

D301123

6/10/04

 Use is not likely to pose risk to freshwater or 

estuarine/marine organisms from acute exposure 

regardless of depth of water body.

0.0008* 

0.002**

NS

NS

NS

NS

Registration

D239293

D291569

D257565

10/29/03

DWA

D274758

6/30/03

 Use over shallow bodies of water (< 1.0 ft) does not 

pose risk to freshwater fish and invertebrates from acute 

or chronic exposures or risk to estuarine/marine fish and 

invertebrates from acute exposure. 

 Use over water bodies > 1.0 ft in depth (e.g., ponds, 

lakes, estuaries) poses risk to endangered freshwater 

invertebrates and risk to estuarine/marine invertebrates 

(including listed species) from acute exposure. 

 Use is not likely to pose risk to birds or mammals 

(including listed species) from acute or chronic 

exposure. 

 Risk to listed species of flying insects (e.g., butterflies) 

cannot be ruled out. 

 Risk to non-target aquatic and terrestrial plants as a 

result of use could not be evaluated due to lack of 

submitted studies.

Food-handling 

establishments with all 

commodities as indoor 

crack, crevice, and fogger 

insecticide

NS NS NS Section 3

New use

D259553

D239124

11/15/99

 Use should pose little or no risks to endangered and nonendangered terrestrial and aquatic organisms.
-53 of 79-

Use Application Rate 

(lb a.i./A)

Number of 

Applications 

(Application 

Interval in Days)

Action

DP Barcode

Date

Risk Conclusions

Single Seasonal/ 

Annual

Domestic outdoor/forestry 

adulticide to control 

mosquitoes and other 

biting and non-biting 

insects

0.00025 to 

0.002**

NS NS Section 3 

New use

D219740

EUP

D217877

2/4/97

 Use poses minimal risk to terrestrial organisms from 

acute and chronic exposure and minimal risk to aquatic 

organisms from acute exposure.

 Uncertainty exists for assessing risk to aquatic 

organisms from chronic exposure due to the lack of fish 

early-life stage and aquatic invertebrate life cycle tests.

Mosquito adulticide in a 

field situation

0.00025 to

0.002**

NS NS EUP

D217878

D218995

11/4/96

 Use poses relatively low incremental risk to the 

environment due to the low amount of chemical being 

used as well as the environmental fate characteristics of 

low persistency and mobility.

NS = not specified; DWA = drinking water assessment; EUP = experimental use permit

*MULTICIDE®Fogging Concentration 2798 (Reg No. 1021-1795)

** RESPONDÉ®Insecticide
-54 of 79-

Appendix B

Summary of Prallethrin Products Currently Registered in the United States

Product Name

EPA Reg. 

No.

% 

a.i.

Use Group Formulation Method of Application & 

Application Equipment

Use 

Restrictions

Other Active Ingredient (% a.i.)

Ortho Roach, 

Ant and Spider 

Killer

239-2679 0.03 Indoor residential

Outdoor residential

Pressurized 

liquid

Crack and crevice and/or spot 

treatment; outdoor general surface 

treatment

Aerosol can

MGK-264 (0.287)

Esfenvalerate (0.05)

Home Defense 

Max Perimeter 

Insect Killer 

Aerosol (1)

239-2695 0.03 Indoor residential

Outdoor residential

Pressurized 

liquid

Crack and crevice and/or spot 

treatment

Aerosol can

Bifenthrin (0.05)

Farnam X-5368-

99

270-325 0.27 Indoor non-food

Terrestrial non-food

Emulsifiable 

concentrate

Animal treatment (sponge, spray)

Sponge, pressure sprayer

PBO (1)

Farnam X-5306-

98

270-326 0.33 Indoor non-food

Terrestrial non-food

Emulsifiable 

concentrate

Animal treatment (spray); space spray

Cloth, sponge, hand-held sprayer, 

mechanical sprayer

2,5-Pyridinedicarboxylic acid, 

dipropyl ester (2.5)

MGK 264 (3.1)

PBO (1.85)

Permethrin (1)

Farnam X-5369-

99

270-327 0.13 Indoor non-food

Terrestrial non-food

Ready-to-use 

solution

Animal treatment (rub-on)

Package applicator,

Butoxypolypropylene glycol (20)

2,5-Pyridinedicarboxylic acid, 

dipropyl ester (1)

PBO (0.5)

Farnum X-5303-

98

270-328 0.13 Indoor non-food

Terrestrial non-food

Ready-to-use 

solution

Animal treatment (spray)

Cloth, sponge, ready-to-use spray 

container

Butoxypolypropylene glycol (5)

2,5-Pyridinedicarboxylic acid, 

dipropyl ester (1)

MGK 264 (2)

PBO (1.85)

Permethrin (0.2)

Farnam X-5294-

98

270-329 0.033 Indoor food

Indoor non-food

Terrestrial non-food

Ready-to-use 

solution

Animal treatment (spray); indoor 

general surface treatment; space spray

Trigger spray bottle, cloth, glove, 

sponge, sprayer, fog generator

PBO (0.5)

Permethrin (1)
-55 of 79-

Product Name

EPA Reg. 

No.

% 

a.i.

Use Group Formulation Method of Application & 

Application Equipment

Use 

Restrictions

Other Active Ingredient (% a.i.)

F8028-2 Aerosol 279-3365 0.03 Forestry

Indoor food

Indoor medical

Indoor non-food

Indoor residential

Outdoor residential

Terrestrial non-food

Pressurized 

liquid

Crack and crevice and/or spot 

treatment; injection treatment; void 

treatment

Aerosol can (with injection tube)

Bifenthrin (0.05)

Country Vet 

Roach Embargo 

with Growth 

Inhibitor

279-3390 0.04 Indoor non-food

Indoor residential

Pressurized 

liquid

Aerosol, fog or fumigation application

Aerosol can

Esfenvalerate (0.1)

Pyriproxyfen (0.6)

ETOC Flying 

and Crawling 

Insect Killer 

(F9146-1)

279-3428 0.2 Indoor food

Indoor medical

Indoor non-food

Indoor residential

Pressurized 

liquid

Crack and crevice treatment; injection 

treatment

Aerosol can (with injection tube)

MGK 264 (1)

PBO (0.6)

Whitmire TC 161 

Injection System

499-443 0.03 Forestry

Indoor food 

Indoor medical

Indoor non-food

Indoor residential

Outdoor residential

Terrestrial non-food

Pressurized 

liquid

Bore-hole treatment; crack and crevice 

and/or spot treatment; mound 

injection; spray; void treatment

Aerosol can with injection tube

Cyfluthrin (0.1)

Whitmire Microgen TC200 

Injection System

499-471 0.03 Forestry

Indoor food

Indoor medical

Indoor non-food

Indoor residential

Outdoor residential

Terrestrial non-food

Pressurized 

liquid

Crack and crevice and/or spot 

treatment; injection treatment; tree 

injection treatment; void treatment

Aerosol can with injection tube

lambda-Cyhalothrin (0.05)

TC-303 499-540 0.05 Indoor medical

Indoor non-food

Indoor residential

Pressurized 

liquid

Animal bedding/litter treatment; spray

Aerosol can

Dinotefuran (0.25)

Pyriproxyfen (0.1)

TC-323 499-550 0.1 Indoor non-food

Terrestrial non-food

Indoor residential

Outdoor residential

Pressurized 

liquid

Spray

Aerosol can

TC-312 499-559 0.25 Not specified in 

LUIS report

Ready-to-use 

solution

Not specified in LUIS report Pyrethrins (0.25)

PBO (4)
-56 of 79-

Product Name

EPA Reg. 

No.

% 

a.i.

Use Group Formulation Method of Application & 

Application Equipment

Use 

Restrictions

Other Active Ingredient (% a.i.)

Evercide 

Residual Ant and 

Roach Spray 

2543

1021-1601 0.03 Indoor non-food

Indoor residential 

Indoor food

Outdoor residential

Terrestrial non-food 

Pressurized 

liquid

Crack and crevice and/or spot 

treatment; outdoor general surface 

spray

Aerosol can

MGK 264 (0.25)

Esfenvalerate (0.05)

MULTICIDE

ETOC 90% 

Concentrate

1021-1621 90 N/A N/A N/A Technical 

chemical

MULTICIDE

Concentrate 2593

1021-1632 0.72 N/A N/A N/A Technical 

chemical 

(Formulation 

intermediate)

MGK 264 (27.36)

PBO (17.15)

Phenothrin (3.43)

MULTICIDE

Pressurized 

Spray 2594

1021-1633 0.03 Indoor residential

Indoor food

Pressurized 

liquid

Crack and crevice treatment; directed 

spray

Aerosol can

MGK 264 (0.957)

PBO (0.6)

Phenothrin (0.12)

Evercide 

Concentrate 2625

1021-1655 2 N/A N/A N/A Technical 

chemical 

(Formulation 

intermediate)

Esfenvalerate (5)

Evercide Nylar 

Total Release 

Aerosol 2644

1021-1656 0.04 Indoor food

Indoor medical

Indoor non-food

Indoor residential

Terrestrial non-food

Pressurized 

liquid

Fog

Aerosol can

Pyriproxyfen (0.6)

Esfenvalerate (0.1)

MULTICIDE

Intermediate 

2738

1021-1682 1 N/A N/A N/A Technical 

chemical

(Formulation 

intermediate)

MGK 264 (13.34)

Cyphenothrin (13.34)

MULTICIDE

Intermediate 

2737

1021-1683 1 N/A N/A N/A Technical 

chemical

(Formulation 

intermediate)

MGK 264 (13.34)

Cyphenothrin (8.34)

MULTICIDE

Total Release 

Aerosol 27371

1021-1684 0.03 Indoor food

Indoor non-food

Indoor residential

Pressurized 

liquid

Fog

Fogger, aerosol can

MGK 264 (0.4)

Cyphenothrin (0.25)

MULTICIDE

Total Release 

Aerosol 27381

1021-1686 0.03 Indoor food

Indoor non-food

Indoor residential

Pressurized 

liquid

Fog

Fogger, aerosol can

MGK 264 (0.4)

Cyphenothrin (0.4)
-57 of 79-

Product Name

EPA Reg. 

No.

% 

a.i.

Use Group Formulation Method of Application & 

Application Equipment

Use 

Restrictions

Other Active Ingredient (% a.i.)

Evercide 

Concentrate 2595

1021-1690 1.5 N/A N/A N/A (Technical 

chemical)

Formulation 

intermediate

MGK 264 (11.97)

Esfenvalerate (2.5)

Evercide 

Crawling Insect 

Killer 2548

1021-1691 0.03 Indoor residential

Outdoor residential

Pressurized 

liquid

Crack and crevice and/or spot 

treatment

Aerosol can

MGK 264 (0.3)

Esfenvalerate (0.05)

Evercide 

Intermediate

1021-1692 1.2 N/A N/A N/A Technical 

chemical

(Formulation 

intermediate)

MGK 264 (12)

Esfenvalerate (2)

MULTICIDE

Intermediate 

2747

1021-1709 6.67 N/A N/A N/A Technical 

chemical

(Formulation 

intermediate)

MGK 264 (33.4)

PBO (20)

MULTICIDE

Flying Insect 

Killer 27471

1021-1710 0.2 Indoor food

Indoor medical

Indoor non-food

Terrestrial non-food

Pressurized 

liquid

Crack and crevice treatment; indoor 

general surface treatment; space spray; 

spray; void treatment

Aerosol can

MGK 264 (1)

PBO (0.6)

ETOC Fogging 

Concentrate 2764

1021-1718 2 Indoor food

Indoor medical

Indoor non-food

Indoor residential

Liquid Contact and/or surface treatment; 

crack and crevice and/or spot 

treatment; indoor general surface 

treatment; space and contact spray

Sprayer, mechanical sprayer, aerosol 

generator, mechanical fogger, ultra 

low volume

MULTICIDE

Multi-purpose 

Spray 27373

1021-1765 0.03 Indoor non-food

Indoor residential

Pressurized 

liquid

Space spray; spot treatment

Aerosol can; mechanical generator

MGK 264 (0.4)

Cyphenothrin (0.25)

MULTICIDE

Wasp & Hornet 

Spray 27301

1021-1768 0.1 Indoor non-food

Indoor residential

Outdoor residential

Terrestrial non-food

Pressurized 

liquid

Spot treatment

Aerosol can

MGK 264 (0.5)

MULTICIDE

Intermediate 

2730

1021-1769 5 N/A N/A N/A Technical 

chemical

(Formulation

intermediate)

MGK 264 (25)
-58 of 79-

Product Name

EPA Reg. 

No.

% 

a.i.

Use Group Formulation Method of Application & 

Application Equipment

Use 

Restrictions

Other Active Ingredient (% a.i.)

Evercide O.B. 

RTU 28101

1021-1787 0.03 Indoor food

Indoor medical

Indoor non-food

Outdoor residential

Ready-to-use 

solution

Crack and crevice and/or spot 

treatment; outdoor general surface 

spray; space and contact spray

Trigger spray bottle

Esfenvalerate (0.05)

Evercide 

Concentrate 2810

1021-1788 1.5 N/A N/A N/A Technical 

chemical

(Formulation 

intermediate)

Esfenvalerate (2.5)

Evercide 

Concentrate 2801

1021-1789 5 N/A N/A N/A Technical 

chemical

(Formulation 

intermediate)

MGK 264 (23.93)

Permethrin (10)

MULTICIDE

Fogging 

Concentrate 2798

DUET Duelaction Adulticide 

1021-1795 1 Aquatic non-food

Aquatic non-food 

industrial

Outdoor residential

Terrestrial non-food

Emulsifiable 

concentrate

Ultra low volume

Aircraft, truck-mounted ultra low

volume (nonthermal, cold fog), ultra 

low volume backpack (nonthermal)

PBO (5)

Phenothrin (5)

MULTICIDE

Fogging 

Concentrate 2611 

MUP

1021-1811 2 N/A N/A N/A Technical 

chemical

(Formulation 

intermediate)

MGK 264 (6.67)

PBO (4)

MULTICIDE

Fogging 

Concentrate 2651 

1021-1812 2 Indoor food

Indoor medical

Indoor non-food

Indoor residential

Liquid Contact and/or surface treatment; 

crack and crevice and/or spot 

treatment; indoor general surface 

treatment; space and contact spray

Sprayer, mechanical sprayer, aerosol 

generator, mechanical fogger, ultra 

low volume

PBO (4)

MGK 264 (6.67)

MULTICIDE

Crawling Insect 

Killer 28651

1021-1855 0.011 Indoor residential Pressurized 

liquid

Directed spray; indoor general surface 

treatment

Aerosol can

Pyrethrins (0.011)

Cypermethrin (0.03)

MGK-2927 1021-1875 0.67 N/A N/A N/A Technical 

chemical

MGK 264 (3)

PBO (2)
-59 of 79-

Product Name

EPA Reg. 

No.

% 

a.i.

Use Group Formulation Method of Application & 

Application Equipment

Use 

Restrictions

Other Active Ingredient (% a.i.)

MGK 29461 1021-2559 0.011 Indoor residential Pressurized 

liquid

Directed spray; surface treatment

Aerosol can

Alkyl* dimethyl benzyl 

ammonium chloride *(50%C14, 

40%C12, 10%C16) (0.008)

1-Decanaminium, N-decyl-N,Ndimethyl-, chloride (0.003)

1-Octanaminium, N,N-dimethylN-octyl-, chloride (0.003)

1-Decanaminium, N,N-dimethylN-octyl-, chloride (0.006)

Pyrethrins (0.011)

Cypermethrin (0.03)

MULTICIDE

Fogging 

Concentrate 2922

1021-2562 1 Aquatic non-food

Aquatic non-food 

industrial

Outdoor residential

Terrestrial non-food

Emulsifiable 

concentrate

Ultra low volume

Fixed-wing aircraft, helicopter, truckmounted ultra low volume 

(nonthermal, cold fog), ultra low

volume portable backpack 

(nonthermal)

Phenothrin (5)

PBO (5)

MGK Formula 

2964

1021-2574 1.6 Not specified in 

LUIS report

MicroencapsulatedNot specified in LUIS report Esvenvalerate (6.4)

PBO (8)

Speer Total 

Release Aerosol 

III with Nlar

2724-664 0.04 Indoor medical

Indoor non-food

Indoor residential

Pressurized 

liquid

Aerosol, fog or fumigation application

Aerosol can

Esfenvalerate (0.1)

Pyriproxyfen (0.6)

Etofenprox IGR 

Home and Carpet 

Spray 1(2)

2724-701 0.3 Indoor residential Pressurized 

liquid

Spray

Aerosol can

MGK 264 (0.5)

Ethofenprox (1)

Pyriproxyfen (0.02)

Etofenprox IGR 

Home & Carpet 

Spray II

2724-702 0.3 Indoor residential Pressurized 

liquid

Spray

Aerosol can

Pyriproxyfen (0.02)

MGK 264 (0.3)

Ethofenprox (0.5)

Linalool Mousse 2724-776 0.1 Indoor residential Pressurized 

liquid

Animal treatment

Product container

MGK 264 (0.5)

Linolool (1)

Pyriproxyfen (0.07)

RF2104 Carpet 

Spray M

2724-809 0.3 Indoor non-food

Indoor residential

Pressurized 

liquid

Crack and crevice treatment; spray

Aerosol can

MGK 264 (0.5)

Ethofenprox (0.5)

S-methoprene (0.045)

RWH 33 4822-553 0.02 Terrestrial non-food Pressurized 

liquid

Directed spray

Aerosol can

Cypermethrin (0.05)
-60 of 79-

Product Name

EPA Reg. 

No.

% 

a.i.

Use Group Formulation Method of Application & 

Application Equipment

Use 

Restrictions

Other Active Ingredient (% a.i.)

H6A-US 4822-569 0.1 Indoor non-food

Indoor residential

Outdoor residential

Terrestrial non-food

Soluble 

concentrate

Crack and crevice treatment; directed 

spray; space and contact spray

Aerosol can

Phenothrin (0.125)

KJM Y&D 4822-573 0.04 Outdoor residential

Terrestrial non-food

Pressurized 

liquid

Spray

Aerosol can

Cyfluthrin (0.03)

KJM 4822-574 0.04 Outdoor residential

Terrestrial non-food

Ready-to-use 

solution

Spray

Aerosol can

Cyfluthrin (0.03)

RWH 34 4822-581 0.02 Outdoor residential

Terrestrial non-food

Pressurized 

liquid

Spray

Aerosol can

Cyfluthrin (0.05)

Black Jack 

Roach & Ant 

Killer VI

8848-86 0.03 Indoor non-food

Indoor residential

Outdoor residential

Terrestrial non-food

Pressurized 

liquid

Crack and crevice and/or spot 

treatment

Aerosol can

Esfenvalerate (0.05)

MGK 264 (0.25)

Chemisco 

Aerosol 

Insecticide EL-A

9688-187 0.025 Indoor residential

Outdoor residential

Pressurized 

liquid

Crack and crevice and/or spot 

treatment; wood surface treatment

Aerosol can

Lambda-Cyhalothrin (0.01)

Chemisco Wasp 

& Hornet Killer 

LE

9688-190 0.025 Outdoor residential

Terrestrial non-food

Pressurized 

liquid

Spray

Aerosol can

Lambda-Cyhalothrin (0.01)

Chemisco 

Aerosol 

Insecticide AKR

9688-253 0.025 Indoor residential

Outdoor residential

Pressurized 

liquid

Spot treatment; spray

Aerosol can

Lambda-Cyhalothrin (0.03)

Chemisco 

Aerosol 

Insecticide GE

9688-269 0.025 Indoor residential

Outdoor residential

Pressurized 

liquid

Crack and crevice and/or spot 

treatment; wood surface treatment

Aerosol can

gamma-Cyhalothrin (0.005)

Chemisco 

Aerosol 

Insecticide FAF

9688-282 0.025 Outdoor residential Pressurized 

liquid

Mound treatment

Aerosol can with injection tube

Lambda-Cyhalothrin (0.01)

Chemisco 

Aerosol LEG

9688-288 0.025 Indoor residential Pressurized 

liquid

Crack and crevice and/or spot 

treatment

Aerosol can

o-Phenylphenol (NO INERT USE) 

(0.1)

Lambda-Cyhalothrin (0.01)

ETOC Technical 

Grade

10308-12 93 N/A N/A N/A Technical 

chemical
-61 of 79-

Product Name

EPA Reg. 

No.

% 

a.i.

Use Group Formulation Method of Application & 

Application Equipment

Use 

Restrictions

Other Active Ingredient (% a.i.)

Misty Flying 

Insect Killer

10807-429 0.2 Indoor food

Indoor medical

Indoor non-food

Indoor residential

Terrestrial non-food

Pressurized 

liquid

Crack and crevice treatment; indoor 

general surface treatment; space spray; 

spray; void treatment

Aerosol can

MGK 264 (1)

PBO (0.6)

Country Vet 

Fogger with IGR

10807-470 0.04 Indoor medical

Indoor non-food

Indoor residential

Presuurized 

liquid

Aerosol, fog or fumigation 

application.

Aerosol can

Pyriproxyfen (0.6)

Esfenvalerate (0.1)

Rainbow ETOC 

0.2% Wasp & 

Hornet Spray

13283-30 0.2 Indoor medical

Indoor non-food

Indoor residential

Outdoor residential

Terrestrial non-food

Pressurized 

liquid

Spray

Aerosol can

Rainbow 

ETOC(R) 

0.122% Wasp & 

Hornet Spray

13283-31 0.122 Indoor non-food

Indoor residential

Outdoor residential

Terrestrial non-food

Pressurized 

liquid

Spray

Aerosol can

Rainbow 

ETOC(R) 

0.135% Wasp & 

Hornet Spray

13283-32 0.135 Indoor medical

Indoor non-food

Indoor residential

Outdoor residential

Terrestrial non-food

Pressurized 

liquid

Spray

Aerosol can

Rainbow 

ETOC(R) 0.15% 

Wasp & Hornet 

Spray

13283-33 0.15 Indoor medical

Indoor non-food

Indoor residential

Outdoor residential

Terrestrial non-food

Pressurized 

liquid

Spray

Aerosol can

Rainbow 

ETOC(R) 

0.167% Wasp & 

Hornet Spray

13283-34 0.167 Indoor medical

Indoor non-food

Indoor residential

Outdoor residential

Terrestrial non-food

Pressurized 

liquid

Spray

Aerosol can

Rainbow 

ETOC(R) 

0.186% Wasp & 

Hornet Spray

13283-35 0.186 Indoor medical

Indoor non-food

Indoor residential

Outdoor residential

Terrestrial non-food

Pressurized 

liquid

Spray

Aerosol can
-62 of 79-

Product Name

EPA Reg. 

No.

% 

a.i.

Use Group Formulation Method of Application & 

Application Equipment

Use 

Restrictions

Other Active Ingredient (% a.i.)

CS 101 Roach & 

Ant Spray

44446-65 0.03 Indoor non-food

Indoor residential

Outdoor residential

Pressurized 

liquid

Crack and crevice and/or spot 

treatment; outdoor general surface 

spray

Aerosol can

MGK 264 0.25

Esfenvalerate (0.05)

CTX/Cyber Blast 45382-93 0.03 Indoor non-food

Indoor residential

Outdoor residential

Pressurized 

liquid

Crack and crevice and/or spot 

treatment

Aerosol can

MGK 264 (0.25)

Esfenvalerate (0.05)

Bengal Roach & 

Flea Fogger

68543-9 0.1 Indoor food

Indoor medical

Indoor non-food

Indoor residential

Pressurized 

liquid

Aerosol application

Aerosol can

Permethrin (3)

Bengal Roach & 

Ant Spray IV

68543-17 0.03 Indoor residential

Outdoor residential

Pressurized 

liquid

Crack and crevice and/or spot 

treatment; outdoor general surface 

spray

Aerosol can

MGK 264 (0.3)

Esfenvalerate (0.05)

Bengal Yard & 

Patio Spray

68543-25 0.05 Outdoor residential

Terrestrial non-food

Pressurized 

gas

Outdoor general surface spray; space 

spray

Aerosol can

Permethrin (2)

a.i. = active ingredient; LUIS = Label Use Information System; N/A = not applicable; NS = not specified; PBO = piperonyl butoxide
-63 of 79-

Appendix C

Maximum Labeled Application Rates by Use Site and Formulation for Prallethrin

Use Site Food /

Non-food

Formulation Maximum Application 

Rate/Application

Maximum

Number of 

Applications/

Year

Maximum 

Application 

Rate/

Year

Minimum

Retreatment 

Interval

Minimum

Reentry 

Interval

Agricultural/farm premises N Pressurized liquid NDC NS

Agricultural/farm structures/buildings 

and equipment

F

Liquid-ready to use 0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid NDC NS

N Pressurized liquid NDC NS

Animal feedlots N Emulsifiable concentrate 0.0014 lb a.i./A NS 0.2 lb a.i./A 24 hr, 7 d NS

Animal housing premises (indoor) N Pressurized liquid NDC NS

Animal housing premises (outdoor) N Pressurized liquid NDC NS

Animal kennels/sleeping quarters 

(commercial) N

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid

0.00000003 lb a.i./cu ft NS

0.0001 lb a.i./can NS

0.0013 lb a.i./A NS

NDC NS 0, 90 d 2 hr

Automobiles, taxis, limousines, 

recreational vehicles, & tires N

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid NDC NS

Barns/barnyards/auction barns

F

Emulsifiable concentrate 0.00000001 lb a.i./cu ft NS

Liquid-ready to use 0.00000004 lb a.i./cu ft NS

0.015 lb a.i./A NS

Pressurized liquid 0.00000003 lb a.i./cu ft NS

NDC NS

N

Pressurized gas 0.00000001 lb a.i./cu ft NS

NDC NS

Pressurized liquid NDC NS

Bathroom premises/hard surfaces N Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS
-64 of 79-

Use Site Food /

Non-food

Formulation Maximum Application 

Rate/Application

Maximum

Number of 

Applications/

Year

Maximum 

Application 

Rate/

Year

Minimum

Retreatment 

Interval

Minimum

Reentry 

Interval

Pressurized liquid NDC NS

Beverage processing plant premises 

(nonfood contact) N Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Commercial shipping containersfeed/food-empty F Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Commercial storages/warehouses 

premises

F Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

N

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid

0.00000003 lb a.i./cu ft NS

0.0001 lb a.i./can NS

NDC NS 0, 90 d 2 hr

Commercial transportation facilitiesfeed/food-empty F Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Commercial transportation facilitiesnonfeed/nonfood N

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid 0.00000003 lb a.i./cu ft NS NS 2 hr

NDC NS 0, 90 d 2 hr

Commercial/institutional/industrial 

premises/equipment (indoor)

F

Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid NDC NS 10 d NS

N

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid

0.00000003 lb a.i./cu ft NS 2 hr

0.0001 lb a.i./can NS

0.0013 lb a.i./A NS
-65 of 79-

Use Site Food /

Non-food

Formulation Maximum Application 

Rate/Application

Maximum

Number of 

Applications/

Year

Maximum 

Application 

Rate/

Year

Minimum

Retreatment 

Interval

Minimum

Reentry 

Interval

NDC NS 0, 10, 90 d 2 hr

Commercial/institutional/industrial 

premises/equipment (outdoor) N Pressurized liquid NDC NS

Compost/compost piles N Pressurized liquid NDC NS

Dairies/cheese processing plant 

premises (nonfood contact) N Pressurized liquid NDC NS

Dairy farm milk handling 

facilities/equipment F Pressurized liquid NDC NS

Dairy farm milk storage 

rooms/houses/sheds N Pressurized liquid NDC NS

Dairy farm milking stalls/parlors N Pressurized liquid NDC NS

Dogs/canines (adults/puppies) N Pressurized liquid NDC NS 30 d NS

Eating establishments

F

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Liquid-ready to use 0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid NDC NS 21 d NS

N Pressurized liquid

0.00000003 lb a.i./cu ft NS NS 2 hr

0.0001 lb a.i./can NS

NDC NS NS 2 hr

Eating establishments food handling 

areas (nonfood contact) N Pressurized liquid

NDC NS 10 d NS

NDC NS 10 d NS

0.00000003 lb a.i./cu ft NS NS 2 hr

0.0001 lb a.i./can NS

NDC NS 0, 90 d 2 hr

Egg handling rooms (commercial)

F Pressurized liquid NDC NS 10 d NS

N

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Pressurized liquid NDC NS 10 d NS

Egg packing plants (commercial)

F Pressurized liquid NDC NS 10 d NS

N

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Pressurized liquid NDC NS 10 d NS

Feed mills/feed processing plants F Liquid 0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS
-66 of 79-

Use Site Food /

Non-food

Formulation Maximum Application 

Rate/Application

Maximum

Number of 

Applications/

Year

Maximum 

Application 

Rate/

Year

Minimum

Retreatment 

Interval

Minimum

Reentry 

Interval

NDC NS

Pressurized liquid NDC NS 10 d NS

N Pressurized liquid NDC NS 10 d NS

Fencerows/hedgerows N Pressurized liquid NDC NS

Food processing plant non-food 

handling areas N Pressurized liquid 0.00000003 lb a.i./cu ft

NS

NS

NS 2 hr

0.0001 lb a.i./can NS

NDC NS

Food processing plant premises 

(nonfood contact)

F

Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid NDC NS 0, 10, 90 d 2 hr

N

Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid

0.00000003 lb a.i./cu ft NS NS 2 hr

0.0001 lb a.i./can NS

NDC NS 10, 21 d 2 hr

Food stores/markets/supermarkets 

premises

F

Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid NDC NS 0, 10, 90 d 2 hr

N

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid 0.00000003 lb a.i./cu ft NS 2 hr

NDC NS 10, 21 d 2 hr

Food/grocery/marketing/storage/distri

bution facility premise N

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Pressurized liquid NDC NS

Forest trees (all or unspecified) N Pressurized liquid NDC NS

Golf course turf N Emulsifiable concentrate 0.0014 lb a.i./A NS 0.2 lb a.i./A 24 hr, 7 d NS

Grain/cereal/flour (bagged/temporary 

storage) F Liquid 0.00000002 lb a.i./cu ft NS 4 d NS

Grain/cereal/flour bins-empty

F Pressurized liquid NDC NS

N Pressurized liquid NDC NS
-67 of 79-

Use Site Food /

Non-food

Formulation Maximum Application 

Rate/Application

Maximum

Number of 

Applications/

Year

Maximum 

Application 

Rate/

Year

Minimum

Retreatment 

Interval

Minimum

Reentry 

Interval

Grain/cereal/flour elevators-empty

F

Liquid 0.00000106 lb a.i./cu ft NS 4 d NS

Liquid 0.2 lb a.i./A NS 4 d NS

Liquid NDC NS

Pressurized liquid NDC NS

N Pressurized liquid NDC NS

Grain/cereal/flour storage areas-empty F Pressurized liquid NDC NS

Horses (show/race/special/ponies) N

Emulsifiable concentrate 0.0012 lb a.i./Animal 1/yr NS 3 d NS

NDC 1/yr NS

Liquid-ready to use 0.0001 lb a.i./Animal 1/yr NS

NDC 1/yr NS

Hospitals/medical institutions 

premises (human/veterinary) N

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid

0.00000003 lb a.i./cu ft NS NS 2 hr

0.0013 lb a.i./A NS

NDC NS 0 d, 90 d 2 hr

Household trash compactor/food 

disposals N Liquid

0.00000007 lb a.i./cu ft NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Household/domestic dwellings N Pressurized liquid

0.00000003 lb a.i./cu ft NS

NDC NS 12 mon NS

NDC NS 90 d 2 hr

Household/domestic dwellings 

contents N Pressurized liquid

0.0013 lb a.i./A NS

NDC 6/yr NS 12 mon, 14 d NS

NDC NS 0 d NS

Household/domestic dwellings indoor 

food handling areas F Pressurized liquid NDC NS 10 d NS

Household/domestic dwellings indoor 

nonfood handling areas N Pressurized liquid 0.00000003 lb a.i./cu ft NS

NDC NS

Household/domestic dwellings indoor 

premises N

Liquid

0.00000007 lb a.i./cu ft NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid 0.00000003 lb a.i./cu ft NS 2 hr
-68 of 79-

Use Site Food /

Non-food

Formulation Maximum Application 

Rate/Application

Maximum

Number of 

Applications/

Year

Maximum 

Application 

Rate/

Year

Minimum

Retreatment 

Interval

Minimum

Reentry 

Interval

0.0001 lb a.i./can NS

0.0013 lb a.i./A NS

NDC 6/yr NS 12 mon, 14 d NS

NDC NS 0, 90 d 2 hr

Household/domestic dwellings 

outdoor premises N

Emulsifiable concentrate 0.0014 lb a.i./A NS 0.2 lb a.i./A 24 hr, 7 d NS

Liquid-ready to use NDC NS 14 d NS

Pressurized gas 0.00000001 lb a.i./cu ft NS

NDC NS

Pressurized liquid

0.0002 lb a.i./can NS 21 d NS

0.034 lb a.i./A NS

NDC NS 0 d NS

NDC

NS

NS 6 mon NS

Intermittently flooded areas/water N Emulsifiable concentrate 0.0014 lb a.i./A NS 0.2 lb a.i./A 24 hr NS

Meat processing plant premises 

(nonfood contact)

F Pressurized liquid NDC NS

N

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Pressurized liquid NDC NS 21 d NS

Morgues/mortuaries/autopsy/embalmi

ng room premises N

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid NDC NS

Mushroom houses-empty

premises/equipment N Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Nonagricultural outdoor 

buildings/structures N Pressurized liquid NDC NS

Nonagricultural rights-ofway/fencerows/hedgerows N Pressurized liquid NDC NS

Nonagricultural uncultivated 

areas/soils N Pressurized liquid NDC NS

Nonfeed/nonfood containers-empty N Pressurized liquid NDC NS

Ornamental and/or shade trees N Pressurized liquid NDC NS

Paths/patios N Pressurized gas 0.00000001 lb a.i./cu ft NS
-69 of 79-

Use Site Food /

Non-food

Formulation Maximum Application 

Rate/Application

Maximum

Number of 

Applications/

Year

Maximum 

Application 

Rate/

Year

Minimum

Retreatment 

Interval

Minimum

Reentry 

Interval

NDC NS

Pressurized liquid

0.0001 lb a.i./can NS 21 d NS

0.034 lb a.i./A NS

NDC NS 0 d NS

NDC NS 6 mon NS

Pet living/sleeping quarters N

Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized liquid

0.00000003 lb a.i./cu ft NS NS 2 hr

0.0001 lb a.i./can NS

NDC 6/yr NS 14 d NS

NDC NS 0, 90 d 2 hr

Poultry processing plant premises 

(nonfood contact) N Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Processing/handling equipment F Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Recreational areas N

Emulsifiable concentrate 0.0014 lb a.i./A NS 0.2 lb a.i./A 24 hr, 7 d NS

Pressurized liquid 0.034 lb a.i./A NS

NDC NS 0, 90 d 2 hr

Refuse/solid waste containers 

(garbage cans) N

Liquid

0.00000007 lb a.i./cu ft NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Pressurized gas 0.00000001 lb a.i./cu ft NS

NDC NS

Pressurized liquid

0.0001 lb a.i./can NS

NDC NS 0 d NS

NDC NS 12 mon NS

Refuse/solid waste sites (indoor) N

Liquid

0.00000007 lb a.i./cu ft NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Pressurized liquid NDC NS

Seed houses/stores/storage 

areas/warehouses N Pressurized liquid NDC NS

Sewage catch basins N Emulsifiable concentrate 0.0007 lb a.i./A NS .094lb / a 7 d NS
-70 of 79-

Use Site Food /

Non-food

Formulation Maximum Application 

Rate/Application

Maximum

Number of 

Applications/

Year

Maximum 

Application 

Rate/

Year

Minimum

Retreatment 

Interval

Minimum

Reentry 

Interval

Sewage disposal areas N Pressurized liquid NDC NS

Sewage systems N Emulsifiable concentrate 0.0014 lb a.i./A NS 0.2 lb a.i./A 24 hr NS

Ships and boats N

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Pressurized liquid 0.00000003 lb a.i./cu ft NS NS 2 hr

NDC NS 90 d 2 hr

Specialized animals N Liquid-ready to use

0.0856 lb a.i./A NS 30 d NS

NDC NS

Storage areas-empty F

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Pressurized liquid NDC NS

Storage areas-full F Pressurized liquid NDC NS

Swamps/marshes/wetlands/stagnant 

water N Emulsifiable concentrate 0.0014 lb a.i./A NS 0.2 lb a.i./A 24 hr, 7 d NS

Swine feedlots N Emulsifiable concentrate 0.0014 lb a.i./A NS 0.2 lb a.i./A 24 hr, 7 d NS

Urban areas N Emulsifiable concentrate 0.0014 lb a.i./A NS 0.2 lb a.i./A 24 hr, 7 d NS

Utilities N

Liquid

0.00000106 lb a.i./cu ft NS 4 d NS

0.2 lb a.i./A NS 4 d NS

NDC NS

Pressurized liquid NDC NS

Utility poles / right-of-way N Pressurized liquid NDC NS

Wide area/general outdoor treatment 

(public health use) N

Emulsifiable concentrate 0.0014 lb a.i./A NS 0.2 lb a.i./A 24 hr NS

Pressurized liquid 0.0002 lb a.i./can NS 21 d NS

Wood protection treatment to 

buildings/products indoor N Pressurized liquid NDC NS 0 d NS

NDC NS

Wood protection treatment to 

buildings/products outdoor N Pressurized liquid NDC NS 0 d NS

NDC NS

Zoos N

Emulsifiable concentrate 0.0014 lb a.i./A NS 0.2 lb a.i./A 24 hr, 7 d NS

Pressurized liquid 0.00000003 lb a.i./cu ft NS NS 2 hr

NDC NS 90 d 2 hr

a.i. = active ingredient; NDC = no dosage conversion; NS = not specified; 
-71 of 79-

Appendix D

EPI Summary (v4.10) for PGLS, a Prallethrin Degradate

CAS Number: (null)

SMILES : O=C1C(CC#C)=C(C)C(O)C1

CHEM : PGLS

MOL FOR: C9 H10 O2 

MOL WT : 150.18

------------------------------ EPI SUMMARY (v4.10) --------------------------

Physical Property Inputs:

 Log Kow (octanol-water): ------

 Boiling Point (deg C) : ------

 Melting Point (deg C) : ------

 Vapor Pressure (mm Hg) : ------

 Water Solubility (mg/L): ------

 Henry LC (atm-m3/mole) : ------

Log Octanol-Water Partition Coef (SRC):

 Log Kow (KOWWIN v1.68 estimate) = 0.48

Boiling Pt, Melting Pt, Vapor Pressure Estimations (MPBPVP v1.43):

 Boiling Pt (deg C): 275.57 (Adapted Stein & Brown method)

 Melting Pt (deg C): 68.12 (Mean or Weighted MP)

 VP(mm Hg,25 deg C): 0.000251 (Modified Grain method)

 VP (Pa, 25 deg C) : 0.0335 (Modified Grain method)

 Subcooled liquid VP: 0.000638 mm Hg (25 deg C, Mod-Grain method)

 : 0.0851 Pa (25 deg C, Mod-Grain method)

Water Solubility Estimate from Log Kow (WSKOW v1.42):

 Water Solubility at 25 deg C (mg/L): 9.625e+004

 log Kow used: 0.48 (estimated)

 no-melting pt equation used

Water Sol Estimate from Fragments:

 Wat Sol (v1.01 est) = 13326 mg/L

ECOSAR Class Program (ECOSAR v1.00):

 Class(es) found:

 Vinyl/Allyl Ketones

 Vinyl/Allyl Alcohols

 a-,b-Ketone alcohol

Henrys Law Constant (25 deg C) [HENRYWIN v3.20]:

 Bond Method : 3.54E-010 atm-m3/mole (3.58E-005 Pa-m3/mole)

 Group Method: Incomplete

For Henry LC Comparison Purposes:

 User-Entered Henry LC: not entered

 Henrys LC [via VP/WSol estimate using User-Entered or Estimated values]:

 HLC: 5.153E-010 atm-m3/mole (5.221E-005 Pa-m3/mole)

 VP: 0.000251 mm Hg (source: MPBPVP)

 WS: 9.63E+004 mg/L (source: WSKOWWIN)

Log Octanol-Air Partition Coefficient (25 deg C) [KOAWIN v1.10]:

 Log Kow used: 0.48 (KowWin est)
-72 of 79-

 Log Kaw used: -7.839 (HenryWin est)

 Log Koa (KOAWIN v1.10 estimate): 8.319

 Log Koa (experimental database): None

Probability of Rapid Biodegradation (BIOWIN v4.10):

 Biowin1 (Linear Model) : 0.8416

 Biowin2 (Non-Linear Model) : 0.8236

Expert Survey Biodegradation Results:

 Biowin3 (Ultimate Survey Model): 3.0048 (weeks )

 Biowin4 (Primary Survey Model) : 3.7383 (days-weeks )

MITI Biodegradation Probability:

 Biowin5 (MITI Linear Model) : 0.6262

 Biowin6 (MITI Non-Linear Model): 0.6419

Anaerobic Biodegradation Probability:

 Biowin7 (Anaerobic Linear Model): 0.4428

Ready Biodegradability Prediction: YES

Hydrocarbon Biodegradation (BioHCwin v1.01):

 Structure incompatible with current estimation method!

Sorption to aerosols (25 Dec C)[AEROWIN v1.00]:

 Vapor pressure (liquid/subcooled): 0.0851 Pa (0.000638 mm Hg)

 Log Koa (Koawin est ): 8.319

 Kp (particle/gas partition coef. (m3/ug)):

 Mackay model : 3.53E-005 

 Octanol/air (Koa) model: 5.12E-005 

 Fraction sorbed to airborne particulates (phi):

 Junge-Pankow model : 0.00127 

 Mackay model : 0.00281 

 Octanol/air (Koa) model: 0.00408 

Atmospheric Oxidation (25 deg C) [AopWin v1.92]:

 Hydroxyl Radicals Reaction:

 OVERALL OH Rate Constant = 124.7093 E-12 cm3/molecule-sec

 Half-Life = 0.086 Days (12-hr day; 1.5E6 OH/cm3)

 Half-Life = 1.029 Hrs

 Ozone Reaction:

 OVERALL Ozone Rate Constant = 48.062370 E-17 cm3/molecule-sec

 Half-Life = 0.024 Days (at 7E11 mol/cm3)

 Half-Life = 34.335 Min

 Fraction sorbed to airborne particulates (phi):

 0.00204 (Junge-Pankow, Mackay avg)

 0.00408 (Koa method)

 Note: the sorbed fraction may be resistant to atmospheric oxidation

Soil Adsorption Coefficient (KOCWIN v2.00):

 Koc : 10 L/kg (MCI method)

 Log Koc: 1.000 (MCI method)

 Koc : 9.435 L/kg (Kow method)

 Log Koc: 0.975 (Kow method)

Aqueous Base/Acid-Catalyzed Hydrolysis (25 deg C) [HYDROWIN v2.00]:

 Rate constants can NOT be estimated for this structure!

Bioaccumulation Estimates (BCFBAF v3.01):

 Log BCF from regression-based method = 0.500 (BCF = 3.162 L/kg wet-wt)
-73 of 79-

 Log Biotransformation Half-life (HL) = -1.6396 days (HL = 0.02293 days)

 Log BCF Arnot-Gobas method (upper trophic) = 0.019 (BCF = 1.044)

 Log BAF Arnot-Gobas method (upper trophic) = 0.019 (BAF = 1.044)

 log Kow used: 0.48 (estimated)

Volatilization from Water:

 Henry LC: 3.54E-010 atm-m3/mole (estimated by Bond SAR Method)

 Half-Life from Model River: 2.027E+006 hours (8.445E+004 days)

 Half-Life from Model Lake : 2.211E+007 hours (9.213E+005 days)

Removal In Wastewater Treatment:

 Total removal: 1.86 percent

 Total biodegradation: 0.09 percent

 Total sludge adsorption: 1.77 percent

 Total to Air: 0.00 percent

 (using 10000 hr Bio P,A,S)

Level III Fugacity Model:

 Mass Amount Half-Life Emissions

 (percent) (hr) (kg/hr)

 Air 0.00665 0.448 1000 

 Water 31.6 360 1000 

 Soil 68.3 720 1000 

 Sediment 0.0711 3.24e+003 0 

 Persistence Time: 593 hr
-74 of 79-

Appendix E

SIP v.1.0 Description, Assumptions, Inputs and Outputs

SIP v.1.0 provides an upper bound estimate of exposure of birds and mammals to pesticides through drinking water 

alone. This model is intended for use in problem formulation to determine whether or not drinking water exposure 

alone is a potential pathway of concern. This does not aggregate drinking water exposure with other exposure routes 

(i.e., diet, inhalation, dermal).

Assumptions:

SIP employs the following conservative assumptions to derive upper bound exposure estimates:

1) The chemical concentration in drinking water is at the solubility limit in water (at 25oC).

2) The assessed animals obtain 100% of their daily water needs through drinking water.

3) The daily water need is equivalent to the daily water flux rate as calculated by Nagy and 

Peterson (1988).

4) The body weight of the assessed bird is equivalent to the smallest generic bird modeled in TREX (i.e., 20 g). This assumption results in the highest ratio of exposure to toxicity for the 3 

assessed avian body weights of T-REX (i.e., 20, 100, 1000 g).

5) The body weight of the assessed mammal is equivalent to the largest generic mammal modeled 

in T-REX (i.e., 1000 g). This results in the highest ratio of exposure to toxicity for the 3 

assessed mammalian body weights of T-REX (i.e., 15, 35, 1000 g). 

Table 1. Inputs

Parameter Value

Chemical name prallethrin

Solubility (in water at 25oC; mg/L) 8.03

Mammalian LD50 (mg/kg-bw) 460

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian 

species

Mammalian NOAEL (mg/kg-bw) 600

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian 

species

Avian LD50 (mg/kg-bw) 1171

Avian test species northern bobwhite quail

Body weight (g) of "other" avian species

Mineau scaling factor 1.15

Mallard NOEC (mg/kg-diet) 360

Bobwhite quail NOEC (mg/kg-diet) 360

NOEC (mg/kg-diet) for other bird species

Body weight (g) of other avian species

NOEC (mg/kg-diet) for 2nd other bird 

species

Body weight (g) of 2nd other avian species
-75 of 79-

Table 2. Mammalian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 1.3812 1.3812

Adjusted toxicity value (mg/kg-bw) 353.8139 461.4963

Ratio of exposure to toxicity 0.0039 0.0030

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Table 3. Avian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 6.5043 6.5043

Adjusted toxicity value (mg/kg-bw) 843.6230 17.8605

Ratio of exposure to acute toxicity 0.0077 0.3642

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for birds

Drinking water exposure 

alone is NOT a potential 

concern for birds

*Conclusion is for drinking water exposure alone. This does not combine all routes of exposure. 

Therefore, when aggregated with other routes (i.e., diet, inhalation, dermal), pesticide exposure through 

drinking water may contribute to a total exposure that has potential for effects to non-target animals.
-76 of 79-

Appendix F

STIR v.1.0 Outputs
-77 of 79-

Use: outdoor at 0.034 lb a.i./A

Spray type: ground

Input

Application and Chemical Information

Enter Chemical Name prallethrin

Enter Chemical Use insecticide

Is the Application a Spray? (enter y or n) y

If Spray What Type (enter ground or air) ground

Enter Chemical Molecular Weight (g/mole) 300.4

Enter Chemical Vapor Pressure (mmHg) 1.00E-07

Enter Application Rate (lb a.i./acre) 0.034

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 1171

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 0.178

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 460

Enter Lowest Rat Inhalation LC50 (mg/L) 0.288

Duration of Rat Inhalation Study (hrs) 4

Enter Rat Weight (kg) 0.35

Output

Results Avian (0.020 kg )

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 1.62E-03

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.03E-04

Adjusted Inhalation LD50 4.09E+00

Ratio of Vapor Dose to Adjusted Inhalation LD50 4.97E-05 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 3.59E-03

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 8.79E-04 Exposure not Likely Significant

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 1.62E-03

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.55E-04

Adjusted Inhalation LD50 1.71E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.49E-05 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 4.52E-03

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 2.63E-04 Exposure not Likely Significant
-78 of 79-

Use: outdoor at 0.034 lb a.i./A

Spray type: aerial

Input

Application and Chemical Information

Enter Chemical Name prallethrin

Enter Chemical Use insecticide

Is the Application a Spray? (enter y or n) y

If Spray What Type (enter ground or air) air

Enter Chemical Molecular Weight (g/mole) 300.4

Enter Chemical Vapor Pressure (mmHg) 1.00E-07

Enter Application Rate (lb a.i./acre) 0.034

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 1171

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 0.178

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 460

Enter Lowest Rat Inhalation LC50 (mg/L) 0.288

Duration of Rat Inhalation Study (hrs) 4

Enter Rat Weight (kg) 0.35

Output

Results Avian (0.020 kg )

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 1.62E-03

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.03E-04

Adjusted Inhalation LD50 4.09E+00

Ratio of Vapor Dose to Adjusted Inhalation LD50 4.97E-05 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 3.27E-03

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 7.99E-04 Exposure not Likely Significant

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 1.62E-03

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.55E-04

Adjusted Inhalation LD50 1.71E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.49E-05 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 4.11E-03

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 2.39E-04 Exposure not Likely Significant
-79 of 79-

Appendix G

Prallethrin Metabolic Pathway