1

OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460

MEMORANDUM

DATE: June 20, 2011

SUBJECT: EFED Registration Review Preliminary Problem Formulation for Permethrin

(PC Code 109701; Case No. 2510; DP Barcode D384703)

FROM: José L. Meléndez, Chemist

Amanda Solliday, Biologist

Keith Sappington, Senior Advisor 

Environmental Risk Branch V

Environmental Fate and Effects Division (7507P) 

THROUGH: Mah T. Shamim, Ph.D., Branch Chief

Environmental Risk Branch V

Environmental Fate and Effects Division (7507P)

TO: Kaitlin Keller, Chemical Review Manager

Kathryn Jacob, Team Leader

Michael Goodis, Branch Chief

Risk Management and Implementation Branch III

Pesticide Re-evaluation Division (7508P)

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

formulation for the ecological risk, environmental fate, endangered species, and drinking water 

assessment to be conducted as part of the Registration Review of the pyrethroid insecticide

permethrin (attached). 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 environmental fate and ecological effects associated with permethrin use. 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 of permethrin.

Use and Usage

The Agency has limited use and usage information relevant to urban exposures and residential 

uses of pyrethroids, including permethrin. The Agency intends to use available non-agricultural 
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use and usage data, such as the Kline database, the California Department of Pesticide 

Regulation’s (CDPR) Pesticide Use Reporting Data and Pest Control Operator’s usage survey, 

and the Residential Joint Venture Task Force homeowner survey data (2003), to inform

reasonable assumptions regarding various applications and information related to 

urban/residential use and potential environmental exposure. Additional information on nonagricultural use and usage of pyrethroid products, specifically permethrin, would be useful in 

order to reduce those uncertainties for the final environmental risk assessment for permethrin.

Environmental Fate

Many of the environmental fate properties of permethrin are known. Nonetheless, there is 

uncertainty with respect to some of the laboratory fate studies because they were performed at 

concentrations that exceeded the solubility limit of the chemical, or in the presence of high 

concentrations of a cosolvent. Permethrin is moderately persistent in aerobic environments, but 

appears to be more persistent in anaerobic environments. The fate of permethrin in publiclyowned treatment works is also an uncertainty.

Based on a bioconcentration factor of 570-610x in whole fish, permethrin is moderately 

bioaccumulative and depuration occurs at moderate rates.

Ecological Effects

In addition, there are ecological data gaps that need to be addressed to reduce uncertainties in the 

preliminary risk picture for permethrin. Permethrin is very highly toxic to fish, aquatic 

invertebrates and terrestrial invertebrates. However, some uncertainty exists concerning the 

potential for acute and chronic adverse aquatic effects to listed and non-listed aquatic species. 

Specifically, data are needed for quantifying permethrin toxicity to benthic aquatic invertebrates 

via chronic sediment exposure, chronic effects to estuarine/marine invertebrates via water 

column exposures and acute effects to oyster shell deposition. An additional acute water column 

toxicity test with the freshwater amphipod Hyalella azteca is also requested based on the 

increased sensitivity of this species to pyrethroid insecticides. Acute fish and aquatic invertebrate 

water column studies are also needed to accurately quantify the effects of permethrin used in 

combination with the synergists piperonyl butoxide and MGK-26. Based on information 

available in the open literature, there is some indication that potential exists for temperaturemediated changes in pyrethroid toxicity and this will be examined in the upcoming risk 

assessment for permethrin.

Evaluation of the chemical structure of permethrin degradates (e.g. m-PBA, m-PBAlc, and cisand trans-DCVA) suggests little similarity to the active parent compound, and the cleavage of 

the ester linkage during degradation of the parent structure is expected to result in a significantly 

decreased toxicity of those degradates relative to the parent. Limited aquatic toxicity data that is 

available to the Agency confirms this assumption.

A number permethrin amphibian toxicity tests were identified in the open literature for the 

previous ecological assessment for permethrin. None of these studies provided estimates of 

toxicity that were ultimately used quantitatively in this risk assessment. However, they do 
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provide some information regarding the hazard of permethrin to amphibians and will be used for 

characterization in the upcoming risk assessment.

Although toxicity to avian species is low based on previously submitted studies with upland 

game bird and waterfowl species, uncertainty exists concerning the potential for acute adverse 

effects to listed and non-listed passerine birds. Permethrin is moderately toxic to mammalian 

species on an acute basis. Mammals can exhibit chronic reproductive effects as a result of higher 

levels of permethrin exposure. 

No data has been submitted to accurately quantify the potential adverse effects of permethrin to 

terrestrial and aquatic plants. 

EFED does not currently conduct risk assessments on non-target insects, but information from 

standard laboratory tests and permethrin incident reports suggest the potential for risk to honey 

bees and other beneficial insects. In consideration of the available information concerning the 

non-systemic nature of permethrin foliar residues and risk mitigation options, the nature of 

residues reported in pollen, wax and bees, and further development of pollinator risk assessment 

methods and guidelines, the Agency is not requesting additional data on permethrin exposure and 

effects on pollinators as part of this preliminary Problem Formulation. Instead, the Agency is 

placing the need for additional data “In Reserve” pending the outcome of the aforementioned 

scientific activities, comments from stakeholders on the need for additional data and the review 

of additional information concerning this topic.
 Environmental Fate and Ecological Risk 

Assessment Preliminary Problem 

Formulation in Support of 

Registration Review of Permethrin 

DP Barcode D384703

PC Code 109701 

Case No. 2510 

June 20, 2011 

Environmental Fate and Effects Division 

Office of Pesticide Programs 

U.S. Environmental Protection Agency

 Prepared by: 

 Amanda Solliday, Biologist 

 José L. Meléndez, Chemist 

 Secondary Review: 

 Keith Sappington, Senior Advisor 

 Mah T. Shamim, Ph.D., Chief 

 Environmental Risk Branch V
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Table of Contents 

1. Purpose ........................................................................................................................ 3

2. Problem Formulation .................................................................................................. 4

2.1. Nature of Regulatory Action .................................................................................... 4

2.2. Previous Risk Assessments and Scientific Advisory Panels ................................... 4

3. Stressor Source and Distribution ................................................................................ 9

3.1. Mechanism of Action ............................................................................................. 13

3.2. Overview of Pesticide Usage ................................................................................. 14

3.3. Environmental Fate and Transport ......................................................................... 29

4. Receptors................................................................................................................... 37

4.1. Aquatic and Terrestrial Effects .............................................................................. 37

4.2. Incident Database Review ...................................................................................... 50

4.3. Ecosystems Potentially at Risk .............................................................................. 53

5. Assessment Endpoints .............................................................................................. 53

6. Conceptual Model .................................................................................................. 54

6.1. Risk Hypothesis ................................................................................................... 54

6.2. Conceptual Diagram ............................................................................................ 55

7. Analysis Plan ......................................................................................................... 62

7.1. Stressors of Concern .............................................................................................. 63

7.2. Measures of Exposure ............................................................................................ 63

7.3. Measures of Effect ................................................................................................. 66

7.4. Integration of Exposure and Effects ...................................................................... 67

7.5. Deterministic and Probabilistic Assessment Methods ........................................... 67

7.6. Endangered Species Assessments .......................................................................... 68

7.7. Drinking Water Assessment .................................................................................. 68

7.8. Endocrine Disruptor Screening Program ............................................................... 68

7.9. Preliminary Identification of Data Gaps ................................................................ 69

7.9.1. Environmental Fate ......................................................................................... 69

7.9.2 Ecological Effects ............................................................................................ 75

8. References .................................................................................................................... 84

9. Fate and Ecotoxicity Bibliography ............................................................................. 88

Appendix A. Data Request Justification Tables ............................................................ 117

Appendix B. Summaries of the Reported Permethrin Ecological Incidents in the EIIS 

Database .......................................................................................................................... 121 

 
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1. Purpose 

The purpose of this problem formulation is to provide the foundation for the ecological risk 

assessment that will be conducted for the registered uses of permethrin during Registration 

Review. As such, it articulates the purpose and objectives of the risk assessment, evaluates the 

nature of the problem, and provides a plan for analyzing the data and characterizing the risk 

(USEPA, 1998). Additionally, this problem formulation is intended to identify data gaps, 

uncertainties and potential assumptions needed to address those uncertainties in characterizing 

the ecological risk associated with the registered uses of permethrin. 

Permethrin is a Type I synthetic pyrethroid currently registered for numerous diverse uses that 

span a large variety of use sites and geographical regions. Type I pyrethroids do not have a 

cyano group substitution in the alpha position of the alcohol moiety of the ester structure; in 

contrast, Type II pyrethroids have the cyano group. Permethrin is a broad spectrum insecticide 

that targets adults and larvae of many diverse species of biting, chewing, scaling, soil, and flying 

invertebrates. Permethrin is a neurotoxic insecticide with contact and stomach action, having a 

slight repellent effect. The primary biological effects of permethrin on insects and vertebrates 

reflect an inhibition of the correct firing of neurotransmitter deliver signals from one cell to 

another via nerve membrane inhibition of the voltage gated Ca2+ channels coupled with a 

stimulatory effect on the voltage gated Na+

 channels. 

Formulation types registered for permethrin include wettable powders, water dispersible granules 

(dry flowable), emulsifiable concentrates liquid, pressurized gas, pressurized liquid, liquid readyto-use products, granulars, seed treatments and dusts. Application methods include: direct spray, 

aerial spray, ground spray, hand spray, airblast, mist/fogging, soil broadcast, surface spray, soil 

incorporation, soil injection, granular (aerial or ground), chemigation. Application equipments 

include among others, mist sprayer, fogger, aircraft, truck-mounted sprayer, sprinkler irrigation, 

airblast and duster. In addition, spray methods may use ultra-low volume (ULV) nozzles which 

suspend the product in the air for a longer duration, in order to intercept flying insects. Potential 

permethrin uses include agricultural (in/on food/feed crops); nursery uses; home garden uses; 

ornamental uses; forestry uses; turf uses; indoor/outdoor industrial, commercial, and residential 

uses; fire ant control; control of ectoparasites on domestic animals; and public health uses (i.e.

for mosquito abatement) in urban and rural settings. Permethrin may also be used to treat 

clothing, which is used to prevent mosquito bites. For agriculture uses, maximum seasonal rates 

usually range from 0.1 to 0.4 lb a.i./A and, depending on the crop, the maximum number of 

permethrin applications per season usually range from 1 to 8. Permethrin may be applied yearround. Non-agricultural use exceeds that of use on agricultural crops. According to BEAD’s 

Chemical Profile dated 05/11/2011 (Brassard et al. 2011) for permethrin: 

“Approximately 400,000 pounds of permethrin active ingredient (a.i.) is applied to 3 

million acres of agricultural crops annually. Approximately 2.5 million pounds of 

permethrin a.i. is applied annually by consumers, pest control operators, 

nursery/greenhouse operators, and mosquito abatement personnel... Permethrin also has 

non-Federal Insecticide, Fungicide, Rodenticide Act (FIFRA) pharmaceutical uses as a 

pediculicide for the treatment of head lice and scabies. The Food and Drug 
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Administration (FDA) approved use of the pesticide-containing pharmaceutical products 

under the Federal Food, Drug, and Cosmetic Act (FFDCA).” 

2. Problem Formulation 

 2.1. Nature of Regulatory Action 

This report summarizes the Environmental Fate and Effects Division’s (EFED) Problem 

Formulation for the Registration Review of permethrin. The Agency has completed previous 

risk for the use of this chemical, which serve as the basis for this assessment. 

The Food Quality Protection Act (FQPA) of 1996 mandated the EPA to implement a new 

program, i.e., registration review (http://www.epa.gov/oppsrrd1/registration_review/). All 

pesticides distributed or sold in the United States generally must be registered by the EPA. The 

decision to register a pesticide is based on the consideration of scientific data and other factors 

showing that it will not cause unreasonable risks to human health, workers, or the environment 

when used as directed on product labeling. 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 new 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 new Registration Review program pursuant to Section 3(g) 

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

evaluation to determine whether permethrin continues to meet the FIFRA standard for 

registration. This problem formulation for the environmental fate and ecological risk assessment 

chapter in support of the registration review is intended for the initial docket opening the public 

phase of the review process. 

2.2. Previous Risk Assessments and Scientific Advisory Panels 

Recent Agency ecological risk assessments conducted on permethrin indicated risk concerns for 

freshwater and estuarine/marine organisms, including benthic organsims. It was noted that a 

number of studies demonstrated that applications of permethrin technical and formulations of 

permethrin are likely to adversely impact nontarget beneficial insects. Toxicity data are not 

available for terrestrial, aquatic non-vascular and aquatic vascular plants and the potential for 

risk to these taxa remains an uncertainty. 

Most recently, in 2010 the Agency conducted an ecological assessment to evaluate potential 

direct and indirect effects of permethrin use on the Valley Elderberry Longhorn Beetle 

(Desmocerus californicus dimorphus) (VELB) to evaluate concerns with the chemical identified 

in the suit Center for Biological Diversity (CBD) vs. EPA et al., (Case No. 07-2794-JCS). Due to 
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the broad use pattern of permethrin across the state of California, including both agricultural and 

non-agricultural uses, the potential exists for permethrin use in any given area to spatially and 

temporally coincide with the VELB. The Agency made a Likely to Adversely Affect 

determination from the use of permethrin based on direct effects to the VELB. There were 

exceedances of the Agency’s interim level of concern (LOC of 0.05) for listed terrestrial 

invertebrates for all of the modeled spray application scenarios assessed, with risk quotients 

(RQs) ranging from 0.16 to 7400, and the high probability of an individual mortality occurrence 

based on the highest acute RQ for terrestrial invertebrates (~1 in 1). Indirect effects to terrestrial 

prey items and habitat modification were also identified. The Agency determined that there is the 

potential for modification of designated critical habitat from labeled use of permethrin in 

California based on the potential for direct effects to the VELB, adverse effects on terrestrial 

invertebrate pollinators of the elderberry (host plant of the VELB) and reported incidents of 

phytotoxicity following permethrin use (USEPA 2010)1

. 

In October 2008, the Agency conducted a listed species risk assessment to assess the potential 

risks of permethrin to the federally-listed California red-legged frog (Rana aurora draytonii) 

(CRLF), California clapper rail (Rallus longirostris obsoletus) (CCR), Salt marsh harvest mouse 

(Reithrodontomys raviventris) (SMHM), San Francisco garter snake (Thamnophis sirtalis 

tetrataenia) (SFGS), and Bay checkerspot butterfly (Euphydryas editha bayensis) (BCB) 

(USEPA 2008a)2

. In addition, the 2008 assessment evaluated whether these actions can be 

expected to result in modification of designated critical habitat for the CRLF and BCB. The 2008 

risk assessment examined 48 agricultural and non-agricultural permethrin use scenarios, 

including alfalfa, nut trees, avocados, cole crops, corn, forestry, fruit trees, garlic, leafy 

vegetables, cucurbit 

vegetables, nursery uses, onions, potato and turnip, row crops, tomatoes, turf, ant mound 

treatments (residential, agricultural, turf, recreational areas), mosquito control, barrier 

treatment (fence rows, hedge rows, range land, urban and rural structures), residential turf 

and ornamentals, outdoor perimeter treatments, termite treatment, residential garden uses, 

and down-the-drain applications (e.g., pet shampoos). Based on the best available information, 

the Agency made a May Affect and Likely to Adversely Affect (LAA) determination for the 

CRLF, CCR, SFGS, SMHM, and BCB from the use of permethrin based on RQs that exceeded 

levels-of-concern for freshwater fish, aquatic-phase amphibians, freshwater invertebrates, 

estuarine/marine fish and estuarine/marine invertebrates. Potential acute risk beyond Agency 

levels-of-concern was identified for all aquatic taxa in all modeled scenarios, with the exception 

of risk to estuarine/marine fish from exposure to permethrin soil barrier treatment for fencerows 

and hedgerows. Additionally, the Agency determined that there was the potential for 

modification of CRLF designated critical habitat from the use of the chemical, but that there was 

not the potential for modification of BCB designated critical habitat. 

The national-level EFED chapter of the Reregistration Eligibility Decision Document (RED) for 

permethrin (Dated April 5th 2006; DP Barcode D326784, USEPA 2006b) and the subsequent 

 

1

 Available at http://www.epa.gov/oppfead1/endanger/litstatus/effects/redleg-frog/index.html

(accessed 01/27/11). 

2

 Available at http://www.epa.gov/oppfead1/endanger/litstatus/effects/redleg-frog/index.html

(accessed 01/27/11). 
 6

Addendum to the Revised EFED RED Chapter for Permethrin (Dated April 5th 2006; DP 

Barcode D328142, USEPA 2006c) found that permethrin exposure in aquatic media (water 

column and sediment/ porewater), can potentially occur at levels that exceed the Agency’s levels 

of concern (LOCs). Risks were identified for listed and non-listed aquatic organisms (fish and 

water-column and sediment-dwelling invertebrates) with acute and chronic LOC exceedances. 

For terrestrial organisms, the potential for chronic risk to mammalian species was also identified, 

with dose-based chronic RQs exceeding the LOC for all but one of the scenarios tested. 

Although risk was not quantified for terrestrial invertebrates, risk could not be precluded and it 

was noted that a number of studies demonstrated that applications of formulations of permethrin 

are likely to reduce the numbers and possibly eliminate populations of beneficial insects. Acute 

risk to mammalian species and acute and chronic risk to avian species appeared to be low, and no 

exceedances of the Agency’s LOCs were identified. Finally, toxicity data were not available for 

terrestrial or aquatic plant species and the potential for risk remains an uncertainty. However, 

additional data were not requested in the 2006 RED because “information from other pyrethroids 

suggest no direct toxic concern to plants from exposure to this family of compounds.” 

In addition to the assessment associating risks with mosquito abatement uses and agricultural 

uses, the same EFED chapter of the Reregistration Eligibility Decision document also raised the 

concern that the greatest volume of permethrin is used on non-agricultural sites. There was 

concern with the potential for permethrin runoff from residential areas and the applications such 

as perimeter treatments in and around buildings and lawn care use that could potentially result in 

residues being transported to adjacent aquatic areas. It was indicated that residues of permethrin 

and other synthetic pyrethroids at levels that are toxic to aquatic organisms have been found in 

aquatic areas that receive runoff from suburban developments. 

1999 Scientific Advisory Panel 

A FIFRA Scientific Advisory Panel (SAP) in 1999 examined the sediment toxicity and fate of 

synthetic pyrethroids. In response to a question regarding whether sediment toxicity data on one 

pyrethroid (cypermethrin) could be used to predict sediment toxicity to all pyrethroids, the panel 

generally supported the method of using data from a few pyrethroids to extrapolate information 

on toxicity to other pyrethroids. The panel recommended testing cypermethrin, bifenthrin 

(relatively non-toxic to freshwater aquatic organisms, very insoluble in water, large 

bioconcentration factor) and possibly tefluthrin (highly toxic to freshwater aquatic organisms, 

stable in water, intermediate solubility in water to cypermethrin and bifenthrin) (USEPA 1999). 

Although this agreement was made in 1999, the new Code of Federal Regulations (40 CFR) Part 

158 ecological effects conditional data requirements that include sediment toxicity tests which 

are considered particularly important for assessing ecological risks of synthetic pyrethroids, 

including permethrin. 

In 2003, in response to the comments from the SAP on pyrethroids, EFED requested the 

following studies on cyfluthrin, cypermethrin, esfenvalerate and bifenthrin (Rexrode & 

Meléndez, memorandum dated 12/22/03): 

EPA Guideline (GLN) 850.1735: Acute Sediment (freshwater)

- Test organism: Hyalella azteca and Chironomus dilutus. 

- Duration: 10 days, endpoint is survival. 
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EPA/600/R01/020: Chronic Estuarine/Marine Sediment Testing

- 28 day test on Leptocheirus plumulosus. 

- Percentage of neonates that survive as adults. 

- Growth rate. 

- Reproduction (#eggs/ female, etc.). 

- Behavior. 

A chronic 65-day freshwater test was also requested only for cypermethrin. 

EPA/600/R-991064: Chronic Freshwater Sediment Testing

- 65 day test on Chironomus dilutus. 

- Survival. 

- Growth rate. 

- Reproduction (# eggs/ female, time to oviposition, proportion of females ovipositing, 

percent hatch).

The SAP commented on the use of Kd or KOC to estimate concentrations of synthetic pyrethroids 

in sediments, recommending that the Agency reconsider KOC as a measure of the binding 

potential of synthetic pyrethroids to sediment and soil because the use of Kd alone limits 

extrapolation to experimental conditions while KOC “allows one to estimate partitioning across a 

wide variety of soil/sediment types” (USEPA 1999). The Panel expressed concern that standard 

methods used to measure sorption may not be applicable to highly hydrophobic compounds due 

to high solids to water ratio, consideration of the character of the organic matter, presence of 

dissolved organic carbon, use of non-representative soils and sediments as sorbents, and 

improper methods used to measure organic carbon. 

While the biota-sediment accumulation factor is a widely accepted method of assessment of 

bioaccumulation in sediments, the Panel indicated that the bioconcentration data for Daphnia

magna and Hyalella azteca should be sufficient to predict bioconcentration of pyrethroids. 

Finally, the Panel indicated that use of a solid phase microextraction (SPME) method to 

determine the dissolved concentration in water could be used to account for sorption of 

pyrethroids to organic carbon and colloids present in the water column in the measurement of 

bioconcentration factors. 

2009 Scientific Advisory Panel

For human healt risk assessment, OPP presented a “Proposed Common Mechanism Grouping for 

the Pyrethrins and Synthetic Pyrethroids to a FIFRA SAP in June 2009. OPP proposed two 

subgroups based on Type I or Type II effects related to sodium current tails and neurobehavioral 

impact, with esfenvalerate and fenpropathrin showing symptoms of both types. The panel 

indicated that substances with mixed characteristics could be included in both groups (see p. 18 

of SAP minutes, USEPA 2009). Permethrin is a Type I synthetic pyrethroid. This mechanism of 

action assessment was performed by HED/OPP and presented to the SAP to determine if a 

cumulative assessment is required for the synthetic pyrethroids. Information on the SAP is 

available in the docket (with non-copyright material available at http://www.regulations.gov) 

under EPA-HQ-OPP-2008-0489. 
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EFED does not currently conduct cumulative ecological risk assessments for several reasons. 

Specifically, the Division does not currently have the methodology to conduct similar cumulative 

risk assessments for all of the (non-human) biological entities for which EFED has 

responsibility. In addition to addressing the toxicological aspects of the cumulative effects of 

multiple pyrethroids to multiple biological entities, a cumulative ecological risk assessment 

would likely require consideration of exposure at a watershed scale in order to incorporate spatial 

and temporal variability in pyrethroid applications into cumulative exposure assessment. EFED 

does not have the modeling tools developed for conducting this type of assessment. However, the 

upcoming ecological risk assessment will consider open literature, currently available models 

and other lines-of-evidence (e.g., monitoring data), as available, to address the potential for 

cumulative effects of pyrethroids in the risk description of the ecological risk assessment for 

permethrin. 

Aquatic Toxicity Benchmarks 

For permethrin, the Office of Pesticide Programs has published aquatic life benchmarks for 

freshwater species, based on the most sensitive species from the most recent risk assessments (at 

http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm#benchmarks). The 

aquatic life benchmarks for permethrin are as follows: 

Table 2.1. OPP Aquatic Life Benchmarks (Freshwater) for Permethrin in μg/L 

Fish Invertebrates Non-vascular plants1

Acute Chronic Acute Chronic Acute 

0.395 0.0515 0.01 0.0014 68 

1

There were no available acute benchmarks for vascular plants. 

The Clean Water Act requires the Agency to publish water quality criteria that accurately reflect 

the latest scientific knowledge on the type and extent of all identifiable effects on health and 

welfare which might be expected from the presence of pollutants in any body of water, including 

ground water. While these recommended criteria do not, in themselves, impose any 

requirements, states and authorized tribes can use them to develop water quality standards. No 

US EPA Aquatic Life Ambient Water Quality Criteria document has been published for 

permethrin (at http://www.epa.gov/waterscience/criteria/). 

Impaired Water Bodies 

Permethrin is not individually identified as a cause of impairment for any water bodies listed as 

impaired under section 303(d) of the Clean Water Act, based on information provided at 

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

However, the pyrethroids as a group have been identified as a cause for impairment for three 

water bodies in Central Valley, California: Del Puerto Creek, Ingram Creek Site (from 

confluence with Hospital Creek to Highway 33 crossing) and second Ingram Creek Site (from 

confluence with San Joaquin River to confluence with Hospital Creek). At the present time, 

additional bodies of water are being evaluated to be included into the list of impaired bodies of 
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water; however, they have not been finalized (see 

http://www.waterboards.ca.gov/water_issues/programs/tmdl/integrated2010.shtml and 

http://www.swrcb.ca.gov/rwqcb5/water_issues/tmdl/impaired_waters_list/303d_list.shtml ). The 

2010 proposed 303(d) list for California contains around 10 additional streams due to pyrethroids 

in the sediments. EFED will include relevant information on 303(d) listings in the final 

ecological risk assessment. 

No Total Maximum Daily Load (TMDL) criteria have been developed specifically for 

permethrin, 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. More information on impaired water bodies and 

TMDLs can be found at http://www.epa.gov/owow/tmdl/. The Agency invites submission of 

water quality data for these pesticides. 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 (at

http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm), in order to ensure 

they can be used quantitatively or qualitatively in pesticide risk assessments. 

National Water Quality Assessment (NAWQA)

Permethrin is among the constituents monitored by the National Water Quality Assessment 

(NAWQA), maintained by the U.S. Geological Survey. Sampling parameters include cispermethrin and/ or trans-permethrin in water and/ or bed sediments in units of μg/L or μg/kg. 

EFED will consult the NAWQA database for information on permethrin in water and sediments 

as part of its forthcoming ecological risk assessment. 

3. Stressor Source and Distribution 

Permethrin (Table 3.1a) is a synthetic pyrethroid insecticide. Its structure has three rings, two 

phenyl rings attached to each other by an oxygen atom (phenyl and phenoxy), and a cyclopropyl 

ring. It is a Type I synthetic pyrethroid (meaning that it is not cyano substituted in the alpha

position). The chemistry of permethrin may be dictated by its ester moiety. It would be 

expected to hydrolyze as the pH increases. This is confirmed from the hydrolysis study, where 

permethrin was stable at pH 3 and 6 and hydrolyzed slowly at pH 9. The structure of the 

molecule has two chiral centers which raise the number of possible isomers to 22

 = 4. 

Permethrin consists of a mixture of these isomers (see below). Permethrin has a 2,2-

dichloroethenyl group in the cyclopropane ring. Table 3.1a provides some identification 

information for permethrin, and its structure. 

According to the International Programme on Chemical Safety (IPCS INCHEM), Environmental 

Health Criteria 94, Permethrin, of the World Health Organization (1990):3 “Technical products 

are a mixture of four stereoisomers with the configurations [1R,trans], [1R,cis], [1S,trans], and 

 

3

 Available at http://www.inchem.org/documents/ehc/ehc/ehc94.htm accessed 01/07/11. 
 10

[1S,cis] in the approximate ratio of 3:2:3:2. The ratio of cis:trans is around 2:3 and the ratio of 

1R:1S is 1:1 (racemic). The [1R,cis] isomer is the most insecticidally active of the isomers, 

followed by the [1R,trans] isomer.” 

Table 3.1a. Identification information for permethrin 

PARAMETER VALUE(s) units (chemical name) SOURCES

CAS Chemical Name (3-phenoxyphenyl)methyl 3-(2,2-dichloroethenyl)-2,2-

dimethylcyclopropanecarboxylate Chemical’s data sheeta

 

PC Code 109701 OPP Databases 

Case Number 2510 OPP Databases 

IUPAC Chemical Name 

3-phenoxybenzyl (1RS,3RS;1RS,3SR)-3-(2,2-

dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate 

or 

3-phenoxybenzyl (1RS)-cis-trans-3-(2,2-dichlorovinyl)-

2,2- dimethylcyclopropanecarboxylate 

Chemical’s data sheeta

 

CAS Reg. No. 52645-53-1 Chemical’s data sheeta

 

Chemical Structure 

(unspecified 

stereochemistry, chiral 

centers are marked with 

asterisks) 

Chemical’s data sheeta 

Molecular Formula C21H20Cl2O3 Chemical’s data sheeta

 

Molecular Weight 391.30 EXTOXNET (see below) 

a. The chemical’s data sheet is available at http://www.alanwood.net/pesticides/permethrin.html, accessed 

01/21/11

In the environment, permethrin is slow to hydrolyze and biodegrade. Pyrethroids such as 

permethrin, that have the 2,2-dichloroethenyl group attached to the cyclopropane moiety, are 

more stable to sunlight than earlier pyrethroids like allethrin or resmethrin. Permethrin has a low 

water solubility (0.0055 mg/L, Laskowski, 2002), and its hydrophobic nature leads to strong soil 

adsorption and a tendency to partition to sediment in aquatic systems (KFOC ≥ 28,200 L/kg, 

Hardly Mobile to Immobile, according to FAO Mobility Classification, FAO 2000). The 

reported value of log octanol/ water partition coefficient of 6.1 (KOW = 1.3 x 106

) suggests that 

permethrin has the potential to bioaccumulate in aquatic organisms, assuming that chemical 

metabolism is negligible. However, the measured bioconcentration factor in fish (570-610 L/kg 

wet wt for whole fish, Table 3.5) is much lower than that expected based on KOW alone, which 

suggests that permethrin metabolism by fish is substantial. Permethrin has a high molecular 

weight of 391.30 g/mol and a vapor pressure of 1.48 x 10-8 mm Hg. Due to its very low 

solubility, the calculated Henry’s Law Constant is moderately low (1.4 x 10-6 atm-m3/mol). 

Permethrin’s air/water partition coefficient (KAW) is 5.7 x 10-5, which classifies it as ‘slightly 

volatile from a water surface’ (USEPA 2008b), and the Cwater+soil/Cair = 4.4 x 106

, which classifies 

the chemical as ‘non-volatile from moist soil’ (USEPA 2008b). Based on these properties, 

permethrin would have a slight potential to volatilize from wet surfaces, but not from moist soil. 

The slight potential to volatilize of permethrin is attenuated by its tendency to bind to organic 

matter (e.g., soils, sediments, or organic matter and particulate in natural water). Table 3.1b lists 

various important physicochemical characteristics of the chemical. Table 3.5 lists the other 

environmental fate properties of permethrin, along with information on the major and minor 
 11

degradates detected in the submitted environmental fate and transport studies. 

Table 3.1b. Physicochemical Properties of Permethrin 

Property Permethrin 

Value1 MRID or Source 

Density/ 

Specific Gravity 1.19 – 1.27 g/cm3

Tomlin, C.D.S. (ed.). The Pesticide 

Manual – 11th ed., British Crop 

Protection Council, Surrey, England 

1997, p. 944 4

Melting Point (0C) 34-35; 

cis-isomers, 63-65; trans-isomers, 44-47 

Tomlin, C.D.S. (ed.). The Pesticide 

Manual - World Compendium, 11 th 

ed., British Crop Protection Council, 

Surrey, England 1997, p. 9444

 

Boiling Point (0C) 200 at 0.1 mmHg; >290 at 760 mmHg 

Tomlin, C.D.S. (ed.). The Pesticide 

Manual - World Compendium. 10th 

ed. Surrey, UK: The British Crop 

Protection Council, 1994., p. 7844

Solubility in Organic 

Solvents 

In xylene and hexane >1000, methanol 258 

(all in g/kg at 250C) 

Tomlin, C.D.S. (ed.). The Pesticide 

Manual - World Compendium, 11 th 

ed., British Crop Protection Council, 

Surrey, England 1997, p. 9444

Vapor Pressure 

(mmHg) 

1.48x10-8 (Average of two values) 

(at 25oC) 

MRID No. 42109801 & Laskowski 

20025

2.18x10-8 (at 25oC) USDA, Agric. Res. Service 1995 4

1.9x10-8 (cis), and 1.1x10-8 (trans) Wells et al., 1986 

Henry’s Law Constant 

(atm-m3

/mole at 20-25oC) 

1.4x10-6 Calculated using solubility of 0.0055 

mg/L and VP of 1.5x10-8 mmHg 

1.6x10-7 Calculated using solubility of 0.0055 

mg/L and VP of 2.18x10-8 mmHg 

Water Solubility 

(mg/L) 

0.0055 at 20°C Wollerton, 1987 5

0.175 (Average of 0.22, and 0.13) MRID No. 42109801 

Octanol – water partition 

coefficient (log KOW) 6.1 at 20o

C Wollerton, 1987 5

Dissociation Constant 

(pKa and/or pKb) Not available PPDB 6

Air-water partition 

coefficient (KAW) 

KAW = Cair/Cwater = HLC/RT 

= 5.7 x 10-5

‘Slightly volatile from a water surface’ 

Calculated Value, 

USEPA, 2008b 

Octanol-air partition 

coefficient (KOA) Henry's Law Constant

K RT

K

K

K OW

AW

OW

OA  

= 2.2 x 1010 

Calculated Value 

Cwater/Cair 





 





 

    6

air

water

P GMW 10

S T R 760

C

C = RT/HLC 

= 1/KAW = 17,534 (unitless) 

‘Slightly volatile from a water surface’ 

Calculated 

USEPA, 2008b 

UV/visible light 

absorption 

Peaks at approximately 200 and 275 nm, 

with some tailing (in acetonitrile). 

λmax at 207 and 273 nm at pH 7. 

MRID 40242801 

RD D2741077 

Volatilisation Flux Not available Not available 

Cwater+soil/Cair

Cwater+soil/Cair = (1/KAW) (1/r + Kd) = 

4.4 x 106

‘Non-volatile from moist soil’ 

Calculated Value 

USEPA, 2008b 

OH Radical Reaction 

Half-life 

0.467 days 

(at 12-hr days; 1.5 x 106

 OH/cm3) EPIWEB v.4.0 Estimate 
 12

Table 3.1b. Physicochemical Properties of Permethrin 

Property Permethrin 

Value1 MRID or Source 

Ozone Reaction Half-life 49.3 days EPIWEB v.4.0 Estimate 

Biomagnification 

Potential 

Presumption: If log KOA > 5, log KOW > 2 

and the rate of chemical transformation is 

low, the chemical may biomagnify in 

terrestrial food chains**

For permethrin, log KOA> 5, log KOW> 2 

and therefore is identified as having a 

potential to biomagnify in terrestrial food 

chains. However, its rate of 

biotransformation is moderate in the 

environment, and it appears to be moderate 

in fish. Specifically, bioconcentration 

factors for permethrin are 570-610x, which 

are much lower than would be expected if 

biotransformation was minimal. Further, it 

is depurated relatively rapidly in fish 

(depuration half -life ~4.7 days). 

Additionally, the potential of permethrin to 

biomagnify in terrestrial food chains will 

be reduced substantially should it be 

similarly biotransformed by terrestrial 

organisms 

**Gobas et al. 2003 and Armitage & 

Gobas, 2007 support this presumption, 

utilized here only as a broad reference 

to determine the potential for 

biomagnification. 

1

 When more than one value for a property was available, the bolded one is the one that was deemed the best, 

based on professional judgment (see also Laskowski, 2002, for further details).

2 http://www.alanwood.net/pesticides/permethrin.html (Accessed 01/07/11) 3 http://extoxnet.orst.edu/pips/permethr.htm (Accessed 08/20/10) 4

 Information taken from the Hazardous Substances Data Bank (HSDB) at http://toxnet.nlm.nih.gov/cgibin/sis/htmlgen?HSDB (accessed 01/07/11) 5 As cited in Laskowski, 2002. 

6 http://sitem.herts.ac.uk/aeru/iupac/Reports/515.htm (accessed 08/25/10) 7 As cited by HED in its RED document D357566, 4/1/09 (USEPA 2009a). 

Various degradates were observed in the laboratory studies (e.g. m-PBA, m-PBAlc, and cis- and 

trans-DCVA). These studies indicate that all of the identified degradates were the result of the 

rupture of the ester bond of the parent molecule. It has been believed that the resulting 

molecules are not as toxic as the parent because they presumably have lost the neurotoxic mode 

of action. Table 3.1c shows the chemical structures of permethrin’s major degradation products. 

At this time, the degradates will not be considered stressors of concern in the forthcoming 

environmental fate and ecological risk assessment (see Section 4 Receptors for information on 

degradate toxicity). 

Table 3-1c: Permethrin Major Breakdown Products 

Common 

Name Chemical Name/ CAS # Structure 
 13

Table 3-1c: Permethrin Major Breakdown Products 

Common 

Name Chemical Name/ CAS # Structure 

m-PBA 

m-phenoxybenzoic acid 

CAS # 3739-38-6 

m-PB-alc or 

m-PBalcohol 

m-phenoxybenzyl alcohol 

CAS # 13826-35-2 

cis-DCVA 

cis-permethric acid or 

cis-3-(2,2-dichlorovinyl)-2,2-

dimethylcyclopropanecarboxylic 

acid 

CAS # 59042-49-8 

transDCVA 

trans-permethric acid or 

trans-3-(2,2-dichlorovinyl)-2,2-

dimethylcyclopropanecarboxylic 

acid 

CAS # 59042-50-1 

3.1. Mechanism of Action 

Permethrin is a neurotoxic insecticide with contact and stomach action, having a slight repellent 

effect. The primary biological effects of permethrin on insects and vertebrates reflect an 

inhibition of the correct firing of neurotransmitter deliver signals from one cell to another via 

nerve membrane inhibition of the voltage gated Ca2+ channels (calcium ion channels), coupled 

with a stimulatory effect on the voltage gated Na+

 channels (sodium ion channels). 

The pyrethroids (including permethrin) share similar modes of action and are considered axonic 

poisons. It is now well established that severe neurological symptoms of poisoning with 

pyrethroids in mammals and insects are the result of modification of Na+ channel activity 

(cellular pores through which sodium ions are permitted to enter the axon to cause excitation) 
 14

(Matsamura, 1985). Advanced electrophysiological experiments using voltage clamp and patch 

clamp, together with ligand binding and ionic flux experiments, have unveiled unique actions of 

pyrethroids of keeping the Na+

 channel in the open state for an extremely long period, sometimes 

as long as several seconds. This modification of Na+

 channel properties leads to hyperactivity of 

the nervous system. Pyrethroids have also been shown to suppress GABA (gammaaminobutyric acid) and glutamate receptor-channel complexes and voltage-activated Ca2+

channels. 

Pyrethroids, including permethrin, stimulate repetitive action in the nervous system by binding to 

voltage-gated Na+ channels, prolonging the Na+ ion permeability during the excitatory phase of 

the action potential. This action leads to spontaneous depolarizations, augmented 

neurotransmitter secretion rate and neuromuscular block, which ultimately results in paralysis of 

the insect. 

Relative to physiological responses, researchers have designated two types of pyrethroids, Type I 

(e.g., S-bioallethrin, resmethrin and permethrin) and Type II (e.g., cypermethrin, deltamethrin 

and fenvalerate). Structurally, Type I pyrethroids lack the cyano group that characterizes Type II 

pyrethroids. Physiologically, Type I pyrethroids have shorter periods of sodium channel 

disruption (shorter inactivation time) than that of Type II pyrethroids. 

3.2. Overview of Pesticide Usage 

The Label Use Information System (LUIS) report & Usage/Label Use Reports for permethrin 

were based on a subset of the universe of labels available for the chemical. Section 3 labels or 

major producers’ labels, along with all State and Local Needs (SLNs) labels, are included in the 

LUIS report. The purpose of these data is to represent the major uses of this chemical. This 

method to extract the labels is intended to provide information about the maximum use rates and 

the use patterns for permethrin. The use information presented in this problem formulation was 

obtained from BEAD’s LUIS report, from the Permethrin Chemical Profile for Registration 

Review dated 05/11/2011 (Brassard et al. 2011) (also supplied by BEAD), from various 

evaluated labels, and from the 2009 Revised Reregistration Eligibility Decision Document. 

Permethrin has numerous uses. A summary of agricultural use patterns for permethrin is shown 

in Tables 3.2 and 3.3. Note that Table 3.2 provides information for agricultural as well as some 

of the non-agricultural uses, such as forestry uses, lawns and turf (including gulf courses), 

ornamentals, mosquito control, and others. There are other outdoor non-agricultural uses 

described further in Table 3.5. 

Table 3.2. Summary of use information for agricultural and various other outdoor nonagricultural uses of permethrin, based on a subset of representative labels. 

Use 

Max. Single 

App. Rate 

(lb. a.i./A) 

# Apps. 

at Max 

Rate 

Seasonal 

App. Rate 

(lbs. a.i./A) 

Interval 

Between 

Apps. (days) 

App. Method (for 

abbreviations see the 

footnotes to table) 

Alfalfa 0.2/cutting 5 1.0 30 G, A, C, S 

Almonds 0.25 3 0.75 10 G, A, C, S 

Anise 0.2 5 1.0 7 G, A, C 

Apples 0.25 2 0.5 10 G, C, S, AB 
 15

Table 3.2. Summary of use information for agricultural and various other outdoor nonagricultural uses of permethrin, based on a subset of representative labels. 

Use 

Max. Single 

App. Rate 

(lb. a.i./A) 

# Apps. 

at Max 

Rate 

Seasonal 

App. Rate 

(lbs. a.i./A) 

Interval 

Between 

Apps. (days) 

App. Method (for 

abbreviations see the 

footnotes to table) 

Artichokes 0.3 3 0.9 10 G, A, C, AB 

Asparagus 0.1 4 0.4 7 G, C, S, AB 

Avocados 0.2 4 0.8 7 G, C, S 

Beans (not further characterized) Expressed in 

lb/gal 

8 NS NS Foliar 

Broccoli 0.2 4 0.8 5 G, A, C, S, AB 

Chinese Broccoli (not in CA) 0.2 4 0.8 5 G, A, C, S. AB 

Brussels Sprouts 0.1 4 0.4 5 G, A, C, S, AB 

Cabbage 0.2 2 0.4 

(0.8 in HI) 

5 G, A, C, S, AB 

Chinese Cabbage 0.2 5 1.0 0 G, A, S, C 

Cauliflower 0.1 4 0.4 

(0.6 in HI) 

5 G, A, S, C 

Celery 0.2 5 1.0 

(1.2 in HI) 

7 G, A, C, S, AB 

Cherries 0.2 3 0.6 10 G, A, C, S, AB 

Corn, Field 0.15 3 0.45 7 G, A, S, C, AB, ULV 

Corn, Sweet 0.2 4 0.8 3 G, A, C, S, AB, ULV 

Corn, Pop 0.15 or 0.2 3 or NS 0.45 or NS 7 or 6 G, A, C, S, AB, ULV 

Eggplant 0.15 4 0.6 

(1.0 in HI) 

7 G, A, C, AB, ULV 

Filbert (Hazelnut) 0.25 3 0.75 10 G, A, C, S, AB 

Garlic 0.2 4 0.8 10 G, A, C, AB, ULV 

Horseradish 0.15 3 0.45 10 G, C, AB 

Leafy Vegetables 0.2 NS 1.0 5-7 G, A, C, S 

Leafy Vegetables 0.3 NS NS 5 Foliar 

Lettuce 0.2 4 0.8 

(1.2 in HI) 

7 G, C, A, AB, ULV 

Spinach, New Zealand Spinach 0.2 3 0.6 3 G, A, C, S, AB, ULV 

Amaranth (Chinese), Celtuce, 

Chard (Swiss), Chervil, Chicory, 

Chrysanthemum, Corn Salad, 

Cress (Garden & Upland), 

Dandelion, Dock (Sorrel), Endive 

(Escarole), Orach (Mountain 

Spinach), Cardoon, Parsley, 

Garden Purslane, Winter Purslane, 

Radicchio, Roquette (Arugula) 

0.2 10 2.0 3-7 G, A, C, S, AB, ULV 

Swiss Chard, Garden & Upland 

Cress, Dandelion, Dock (Sorrel), 

Endive (Escarole), Parsley, 

Garden Purslane, Winter Purslane 

0.3 NS NS 5 Foliar 

Collards 0.15 3 0.45 3 G, A, C, S, AB 

Turnip Greens, Turnip Root 0.15 3 0.45 3 G, A, C, S, AB 

Kohlrabi 0.1 8 0.8 5 G, A, C, S 

Okra 0.3 NS NS 5 Foliar 
 16

Table 3.2. Summary of use information for agricultural and various other outdoor nonagricultural uses of permethrin, based on a subset of representative labels. 

Use 

Max. Single 

App. Rate 

(lb. a.i./A) 

# Apps. 

at Max 

Rate 

Seasonal 

App. Rate 

(lbs. a.i./A) 

Interval 

Between 

Apps. (days) 

App. Method (for 

abbreviations see the 

footnotes to table) 

Chinese Okra (Hechma) 0.2 6 1.2 7 G, A, C, ULV 

Onion 0.3 4 1.0 7 G, A, S, C, AB 

Fennel 0.2 10 2.0 7 G, A, C, S, AB 

Papaya 0.15 5 0.75 10 G, A, C, AB 

Peaches 0.25 3 0.75 10 G, A, S, C, AB, ULV 

Nectarines 0.25 3 0.75 10 G, A, C, AB, ULV 

Pears 0.25 

(0.4 dormant 

only) 

1 @ 0.4 

+ 

1 @ 0.25 

0.65 10 G, A, C, AB, ULV 

Peppers 0.2 4 0.8 5 G, A, C, S, AB 

Pecans Expressed in 

lb/gal 

5 NS NS G 

Pistachios 0.3 3 0.9 10 G, A, S, C, AB 

Potatoes 0.2 4 0.8 10 G, A, S, C, AB 

Soybeans 0.2 2 0.4 10 G, A, C, S, ULV 

Raspberries (red and black), 

Blueberries, Strawberries 

0.3 8 NS NS Foliar 

Tomatoes, Tomatillo 0.2 3 0.6 

(0.8 in HI) 

7 G, A, S, C, AB, ULV 

Vegetable Cucurbits 0.2 NS 1.6 NS G, A, C, S 

Vegetable Cucurbits 0.33 8 NS NS Foliar 

Cantaloupe Melons 0.2 4 0.8 

(1.2 in HI) 

7 G, A, C, S, AB, ULV 

Cucumbers 0.2 6 1.2 7 G, A, C, ULV 

Pumpkins 0.2 6 1.2 7 G, A, S, C, AB, ULV 

Summer Squash, Winter Squash 

(Hubbard) 

0.2 6 1.2 7 G, A, C, S, AB 

Watermelon 0.2 6 1.2 7 G, A, C, S, AB 

Chayote, C. Mixta/C.Pepo and 

Cucuzzi (Spaguetti Squash), 

Gherkin, Chinese Gourd (Wax), 

Gourds, Luffa, Melon, Bitter 

Melon (Balsam Pear), Citron 

Melon, Honeydew Melon, Mango 

Melon, Musk Melon, Winter 

Melon (Casaba/ Crenshaw/ 

Honeydew/ Persian), Momordica 

Spp., Squash, Butternut Squash, 

Zuccini Squash 

0.2 6-8 1.2-1.6 7 G, A, C, S, AB 

Gherkin, Chinese Gourd (Wax), 

Gourds, Melon, Bitter Melon, 

Citron Melon, Honeydew Melon, 

Mango Melon, Musk Melon, 

Winter Melon, Squash 

0.3 NS, 8 NS NS Foliar 

English/ Black Walnuts 0.25 3 0.75 10 G, A, C, AB, ULV 

Rhubarb 0.2 5 2.0 5-7 G, A, S, C, ULV 

Rhubarb 0.3 NS NS 5 Foliar 
 17

Table 3.2. Summary of use information for agricultural and various other outdoor nonagricultural uses of permethrin, based on a subset of representative labels. 

Use 

Max. Single 

App. Rate 

(lb. a.i./A) 

# Apps. 

at Max 

Rate 

Seasonal 

App. Rate 

(lbs. a.i./A) 

Interval 

Between 

Apps. (days) 

App. Method (for 

abbreviations see the 

footnotes to table) 

Watercress 0.125 2 1.25 NS G, C 

Multiple agricultural crops, 

mosquito control, including 

mushroom4

0.007 25 0.18 1 G, A (ULV) 

Other Non-Agricultural Uses 

Public Health 0.007 25 0.18 0.5 G, A (ULV) 

Forestry Cottonwood Hybrid 

(Poplar) 

0.2 NS NS 0 A 

Forestry (Softwoods, Conifers) 0.2 NS NS 5 G, A, S, C, AB, ULV 

Forestry (Softwoods, Conifers) 1.3 NS NS NS G, A, C, AB 

Christmas Tree Plantations 0.2 NS NS 5 G, S, C 

Conifers, Pine (seed orchard) 1.6 NS-6 NS NS-28 G, C 

Nursery Stock 0.2 NS NS NS G 

Roses (field grown) 0.2 NS NS NS G, A, C, AB, ULV 

Turf in Recreational/ Commercial/ 

Industrial Areas, Ornamental 

Lawns & Turf, Residential Lawns 

0.89 

1.0 

2-3 2.0 NS-10 G, A, C, S, AB, ULV 

Hose-End Sprayer

Golf Course Turf 0.1 NS NS NS G 

Golf Course Turf, Recreational 

Areas, Urban Areas 

0.8 NS NS NS Directed Spray, 

Brush-on (Paintbrush) 

Barrier Treatment in Residential, 

Industrial, Recreational Areas, 

Urban Areas, Rights-of-Way, 

Wide Area/ General, Zoos 

0.1 NS 0.18 NS G 

Ornamentals Shade Trees, 

Herbaceous Plants 

0.5 NS NS 4-7 G 

Ornamental Non-Flowering 

Plants, Woody Shrubs and Vines 

0.2 NS NS 0 G 

Buildings/ Structures, Recreational 

Areas, Residential, Residential 

Lawns Perimeter Treatment 

20.4 NS NS NS G 

Ant Mound Treatment in 

Agricultural and Several Other 

Areas 

Up to 0.084 

lb/ mound 

NS NS-0.04 NS, 7, 10 Drench 

Rangelands 0.1 NS NS NS G, A, C, AB (in NM) 

Rights-of-Way/ Fencerows/ 

Hedgrows 

0.1; 

0.017 lb/ 

linear ft 

NS; 

NS 

0.18: 

NS 

NS; 

NS 

Barrier Treatment; 

Soil Treatment 

Paths/ Patios and Paved Areas Up to 341 NS NS NS G 

Wood Protection Forest Units in 

lb/gal 

NS NS NS Pressure Treatment 

 

4 Mushroom is not identified as a crop for which typical agricultural applications are performed; however, it is 

identified as a crop for which adulticide applications are allowed. 
 18

Table 3.2. Summary of use information for agricultural and various other outdoor nonagricultural uses of permethrin, based on a subset of representative labels. 

Use 

Max. Single 

App. Rate 

(lb. a.i./A) 

# Apps. 

at Max 

Rate 

Seasonal 

App. Rate 

(lbs. a.i./A) 

Interval 

Between 

Apps. (days) 

App. Method (for 

abbreviations see the 

footnotes to table) 

Wood Protection Forest Products, 

Buildings (Outdoor) 

Up to 181 NS NS NS Soil or Void or 

Perimeter or Pressure 

Treatment, Spray, 

Brush-on, Crack-andCrevice, Foam 

Application, Subslab 

Injection 

Zoos 1.0 NS NS 14 Surface Treatment 

G = Ground, A = Aerial, C = Chemigation, S = Soil Incorporated, AB = Airblast, NA = Not Available; NS = Not 

Specified, ULV = Ultra Low Volume, Bolded crops/ uses are those that were mitigated in the process of reregistration of 

permethrin (USEPA 2009b). 

Agricultural Use

For agricultural products, application methods include aerial or ground spray (foliar) and ULV. 

In addition, soil applications and seed treatments are possible. 

Environmental Hazard Statements 

Permethrin is classified as a restricted use pesticide due to its toxicity to fish and aquatic 

invertebrates. The following Environmental Hazards statements are required (USEPA 2009b): 

“This pesticide is extremely toxic to aquatic organisms, including fish and invertebrates. 

Do not apply directly to water, or to areas where surface water is present or to intertidal 

areas below the mean water mark. Do not apply when weather conditions favor drift 

from treated areas. Drift and runoff from treated areas may be hazardous to aquatic 

organisms in neighboring areas. Do not contaminate water when disposing of equipment 

wash waters.” 

“Under some conditions, it may also have a potential for transport into surface water in 

runoff (primarily adsorbed to suspended soil particles), for several months or more after 

application. These include poorly draining or wet soils with readily visible slopes toward 

adjacent surface waters, frequently flooded areas, and areas overlying extremely shallow 

groundwater, areas with in-field canals or ditches that drain to surface water, areas not 

separated from adjacent surface waters with vegetated filter strips, and areas over-lying 

tile drainage systems that drain to surface waters.” 

“This pesticide is highly toxic to bees exposed to direct treatment on blooming crops or 

weeds. Do not apply this product or allow it to drift to blooming crops or weeds while 

bees are actively visiting the treatment area.” 

Under spray drift precautions, the labels for permethrin require a buffer zone of 10 ft around 

certain bodies of water, such as lakes, reservoirs, rivers, permanent streams, marshes or natural 

ponds, estuaries and commercial fish farm ponds. The agricultural products should not be 
 19

applied by ground equipment within a distance of 25 ft, or by aerial equipment within a distance 

of 150 ft, or by ULV within a distance of 450 ft from freshwater or estuarine/ marine bodies of 

water as described above. Furthermore, restrictions on the droplet size are required in the labels 

as follows: 

“Use only medium or coarser spray nozzles (for ground and non-ULV aerial application) 

according to ASAE (S572) definition for standard nozzles. In conditions of low humidity 

and high temperatures, applicators should use a coarser droplet size.” 

In addition to the liquid formulation applications described in Table 3.2, there are dust 

applications for multiple crops as described in Table 3.3. It is noted that for dust applications, 

the application rate was not provided in the labels or could not be readily calculated; however, 

the maximum number of applications and the minimum interval between applications is stated in 

many instances. Oftentimes, the number of applications for a given application on a crop for a 

dust formulation is greater than for the same crop using a liquid formulation. 

Table 3.3. Summary of use information for dust applications of permethrin, based on a subset 

of representative labels. Information presented is abridged from the LUIS – EFED Label Data 

Report5

Use 

Single App. 

Rate 

(lb. a.i./A) 

Number 

of Apps. 

Seasonal 

App. Rate 

(lbs. a.i./A) 

Interval 

Between 

Apps. (days) App. Method 

Apples NS NS NS NS Dust 

Asparagus NS 4 NS NS Dust 

Broccoli NS 8 NS NS Dust 

Brussel Sprouts NS 8 NS 5 Dust 

Cabbage NS 8 NS 5 Dust 

Cauliflower NS 8 NS 5 Dust 

Celery NS 7 NS 5, NS Dust 

Corn, Field NS 6 NS 5 Dust 

Corn, Sweet NS 6 NS NS Dust 

Corn, Salad NS 7 NS 5 Dust 

Eggplant NS 10, 16 NS NS Dust 

Garlic NS 6 NS NS Dust 

Horseradish NS 3 NS NS Dust 

Lettuce NS 7 NS 5 Dust 

Spinach NS 5-7 NS NS-5 Dust 

Celtuce, Swiss Chard, Chervil, 

Chrysantemum, Garden & Upland 

Cress, Dandelion, Dock (Sorrel), 

Endive (Escarole), Orach 

(Mountain Spinach), Parsley, 

Garden Purslane, Winter Purslane, 

Roquette (Arugula) 

NS 7 NS 5 Dust 

Onion NS 6 NS NS Dust 

Fennel NS 7 NS 5 Dust 

Peppers NS 8 NS NS Dust 

 

5

 Current as of 09/29/10 
 20

Table 3.3. Summary of use information for dust applications of permethrin, based on a subset 

of representative labels. Information presented is abridged from the LUIS – EFED Label Data 

Report5

Use 

Single App. 

Rate 

(lb. a.i./A) 

Number 

of Apps. 

Seasonal 

App. Rate 

(lbs. a.i./A) 

Interval 

Between 

Apps. (days) App. Method 

Potatoes NS 8-12 NS NS Dust 

Tomato NS 6 NS NS Dust 

Cucumbers NS 8 NS NS Dust 

Pumpkin NS 8 NS NS Dust 

Gherkin, Chinese Gourd (Wax), 

Gourds, Melons, Bitter Melon, 

Cantaloupe Melon, Ciron Melon, 

Honeydew Melon, Musk Melon, 

Winter Melon, Squash, Summer 

Squash, Winter Squash (Hubbard) 

NS 8 NS NS Dust 

English/ Black Walnuts NS 8 NS NS Dust 

Rhubarb NS 5-7 NS NS-5 Dust 

Ornamental Shade Trees, 

Herbaceous & Non-Flowering 

Plants, Woody Shrubs and Vines 

NS NS NS NS Dust 

Permethrin has uses for the treatment of several kinds of animals for the control of ectoparasites. 

They include cattle, dairy cattle (lactating, non-lactating or unspecified), dairy goats (lactating, 

non-lactating or unspecified) and wool/ angora animals, dogs/ canines adult/puppies, cats/ 

kittens, animal bedding treatment (presumably for pets), hogs/ pig/ swine treatments, horses 

(show/ race/ special/ ponies), livestock, poultry, and sheep animal treatment. Treatments include 

dips, sprays, sponges, dust, back rubber, spot treatment, and ear treatment. For cattle, typically a 

14 day retreatment interval was specified. Applied amounts vary per label and are often 

estimated in lb a.i./animal. Figure 3.1 shows the cattle and calves inventory as of 2007. Since 

exposure to water bodies due to treatment of cattle and various other animals is possible, this use 

will be assessed in the ecological risk assessment to estimate potential permethrin exposure 

following application to livestock. 
 21

Figure 3.1. Cattle and Calves Inventory as of 20076

The usage of permethrin, from the Screening Level Usage Analysis (SLUA) is provided in Table 

3.4. The table is arranged by crop in alphabetical order. According to the table, the major 

agricultural uses for permethrin are corn (90,000 lb a.i.), followed by lettuce and pistachio 

(40,000 lb a.i. each), and alfalfa, almonds and soybeans (with 30,000 lb a.i. each). Crops with 

relatively high percent crop treated (≥45%) include artichokes, celery, lettuce, pistachios and 

spinach. Their respective average percent crop treated were 45, 60, 45, 65 and 50%. Their 

maximum percent crops treated were 65, 90, 70, 80 and 75%, respectively. Both lettuce and 

pistachio, which are crops with high average and maximum percent crop treated, are among the 

major crops in terms of pounds of active ingredient applied (with ≥30,000 lb a.i. per year). 

Table 3.4. Screening-Level Estimates of Agricultural Uses of Permethrin (SLUA)7

Crop Lbs. A.I. 

Percent Crop Treated 

Average Maximum 

 

6

Information obtained from the following website accessed 02/01/11: 

http://www.agcensus.usda.gov/Publications/2007/Online_Highlights/Ag_Atlas_Maps/Livestock

_and_Animals/Livestock,_Poultry_and_Other_Animals/07-M134.asp 7

 Dated 08/24/10 
 22

Table 3.4. Screening-Level Estimates of Agricultural Uses of Permethrin (SLUA)7

Crop Lbs. A.I. 

Percent Crop Treated 

Average Maximum 

Alfalfa 30,000 <2.5 <2.5 

Almonds 30,000 15 30 

Apples 2,000 5 5 

Artichokes 1,000 45 65 

Asparagus 2,000 15 25 

Avocados 1,000 5 10 

Beans, Green <500 <2.5 <2.5 

Broccoli 3,000 15 30 

Brussels Sprouts* <500 N/C N/C 

Cabbage 3,000 15 20 

Cantaloupes 3,000 15 40 

Carrots + 1,000 5 15 

Cauliflower 1,000 15 30 

Celery 6,000 60 90 

Cherries 2,000 5 20 

Chicory* + <500 N/C N/C 

Corn 90,000 <2.5 5 

Cotton + 5,000 <1 <2.5 

Cucumbers 5,000 10 20 

Dry Beans/Peas <500 N/C N/C 

Eggplant <500 5 10 

Garlic 1,000 10 25 

Grapes 1,000 <1 <2.5 

Hazelnuts (Filbert) + 1,000 5 15 

Lettuce 40,000 45 70 

Nectarines* <500 N/C N/C 

Onions 4,000 10 15 

Oranges + <500 <1 <2.5 

Peaches 8,000 15 25 

Peanuts + 4,000 <1 <2.5 

Pears 1,000 5 10 

Peas, Green + <500 <1 <2.5 

Pecans 1,000 <1 <2.5 

Peppers 3,000 5 15 

Pistachios 40,000 65 80 

Potatoes 10,000 5 10 

Prunes + <500 <1 <2.5 
 23

Table 3.4. Screening-Level Estimates of Agricultural Uses of Permethrin (SLUA)7

Crop Lbs. A.I. 

Percent Crop Treated 

Average Maximum 

Pumpkins 4,000 15 25 

Rice+ 1,000 <1 <2.5 

Sorghum + 1,000 <1 <2.5 

Soybeans 30,000 <1 <2.5 

Spinach 9,000 50 75 

Squash 2,000 10 20 

Strawberries <500 <1 <2.5 

Sweet Corn 10,000 10 15 

Tobacco + 2,000 <1 <2.5 

Tomatoes 6,000 5 10 

Walnuts 4,000 5 10 

Watermelons 4,000 10 15 

All numbers are rounded. '<500' indicates less than 500 pounds of active ingredient. '<2.5' indicates less 

than 2.5 percent of crop is treated. '<1' indicates less than 1 percent of crop is treated. ‘+’ Crops not known 

to be listed on active end use product registrations or as Section 18 emergency exemptions when the report 

was run. ‘N/C’ not calculated. ‘*’ CA data only (95% or more of U.S. acres in California; data only 

available on total lbs.A.I.). The sources of the SLUA include the USDA-NASS, Private Pesticide Market 

Research and California Department of Pesticide Regulation (CDPR) data. The information reflects 

amalgamated data developed by the Agency and are in a releasable format. 

BEAD provided agricultural information by states in its Permethrin Chemical Profile for 

Registration Review: “The states with the most agricultural usage in terms of pounds active 

ingredient applied are: California (35%), Illinois (7%), and Missouri (6%), followed by Arizona 

(5%), Wisconsin (4%), and Iowa, Indiana, and Minnesota, Nebraska with 3% each.” (GfK 

Kynetec, 1998-2008 Proprietary Data) 

The U.S. Geological Survey (USGS) pesticide agricultural use maps show regional scale patterns 

in use intensity within the United States (Fig. 3.2). The USGS pesticide maps are based on State 

level estimates of pesticide use rates for individual crops, which have been compiled by the 

National Center for Food and Agricultural Policy (NCFAP) for 1999 through 2004, and on the 

2002 Census of Agriculture for county crop acreage crop. According to the map, the major 

agricultural use for permethrin as of 2002 was corn, with 48% of the national use; this use was 

followed by lettuce, alfalfa hay and soybeans with 6.8-9.4% of the pounds applied (source: 

http://water.usgs.gov/nawqa/pnsp/usage/maps/show_map.php?year=02&map=m6048, accessed 

01/20/11). General agreement exists between the SLUA and the USGS map data. The map 

shows a generalized use of permethrin for agricultural purposes throughout all of the country, 

with higher use in the Midwest (the cornbelt), California and the Chesapeake Bay region (the 

Delmarva Peninsula). It also shows potential uses in estuarine/ marine regions of the US. 

Multiple agricultural uses are approved for permethrin, besides those shown on the map, as 

indicated above in the Tables 3.2 and 3.3. 
 24

Fig. 3.2 Estimated Use of Permethrin in 2002 

Note of Caution: The pesticide use maps available (http://water.usgs.gov/nawqa/pnsp/usage/maps/compound_listing.php?year=02 ) show the 

average annual pesticide use intensity expressed as average weight (in pounds) of a pesticide applied to each square mile of agricultural land in a 

county. The area of each map is based on state-level estimates of pesticide use rates for individual crops that were compiled by the CropLife 

Foundation, Crop Protection Research Institute during based on information collected during 1999 through 2004 and on 2002 Census of Agriculture 

county crop acreage. The maps do not represent a specific year, but rather show typical use patterns over the five year period 1999 through 2004. Use 

intensity rates are expressed as the pounds applied per square mile of mapped agricultural land in a county. The area of mapped agricultural land for 

each county was obtained from an enhanced version of the 1992 USGS National Land Cover Data (NLCD). The key limitations of the data used to 

produce these maps include the following: (1) state use coefficients represent an average for the entire state and consequently do not reflect the local 

variability of pesticide management practices found within states and counties, (2) pesticide use estimates are not for a specific year, but represent 

typical use patterns for the five year period, (3) state pesticide use coefficients may not have been available for all states where a pesticide may have 

been applied to agricultural land, and therefore, are not displayed on the maps, (4) the county crop acreage is based on the 2002 Census of Agriculture 

and may not represent all crop acreage because of Census nondisclosure rules, and (5) agricultural land area used to calculate the pesticide use 

intensity and display the data was derived from 30-meter satellite remote sensing data that may over estimate or underestimate the actual agricultural 

land area. The maps are not intended for making local-scale estimates of pesticide use, such as estimates at the county level. Please refer to Method for 

Estimating Pesticide Use for a detailed discussion of how the pesticide use data were developed. 

Non-agricultural Use

Besides the classical agricultural use sites, permethrin has multiple non-agricultural uses. 

Examples of uses classified as outdoor residential include ornamental lawns and turf, 

recreational area lawns, residential lawns and paths/ patios. With respect to the non-agricultural 

usage, BEAD’s Permethrin Chemical Profile for Registration Review reveals that, “In terms of 

non-agricultural usage, data are available to address usage by lawn care operators and pest 

control operators, and for uses such as mosquito abatement, golf courses, nursery/ greenhouse, 

and food handling establishments, in addition to consumers for outdoor use. Generally, over the 
 25

reported years (1999 through 2008), the majority of use was by consumers for outdoor use. 

Consumers used 1.6 million pounds active ingredient in 2000, approximately 2.5 million pounds 

active ingredient in 2003, and 1.75 million pounds active ingredient in 2005 for outdoor use. 

This amount is approximately 4-6 times greater than the average agricultural usage of 

permethrin which is approximately 400,000 pounds active ingredient/year, based on private 

market pesticide usage data (Proprietary Data, 1998-2008; based on information provided in 

the Screening-Level Estimates of Agricultural Uses of Permethrin, provided by the 

Biological and Economic Analysis Division on 08/24/10). Pest control operators used 

approximately 580,000 pounds active ingredient in 2000 and 450,000 pounds active ingredient in 

2003. Use for mosquito abatement included approximately 34,000 pounds active ingredient in 

2000, increasing to 100,000 pounds active ingredient in both 2003 and 2005. Nursery/ 

Greenhouse use in 2002 was approximately 25,000 pounds active ingredient with use decreasing 

in 2004 to approximately 14,000 pounds active ingredient and in 2006 to 12,000 pounds active 

ingredient (Kline and Co., Inc., 2000-2005).” 

Table 3.5 provides a summary of several nonagricultural (terrestrial or outdoor) uses for 

permethrin (except for those described in Table 3.2). Application methods vary widely. Note 

that for various uses, the maximum application rate is expressed in units other than lb a.i./A and 

in some instances more than one application rate is provided (for example, see “household 

domestic dwellings outdoor premises”). Many of the uses potentially involve substantive 

exposure to wildlife, especially aquatic organisms, and they will be assessed accordingly (e.g., 

conifers – seed orchard, forest trees, commercial/ industrial lawns, residential lawn, golf course 

turf, ornamental lawns and turf, recreation area lawns and residential lawns). Another use that 

will be evaluated is wood protection treatment (outdoors). 

Table 3.5. Summary of terrestrial non-food uses for permethrin (except for the uses 

identified in Table 3.2) 

Use Max. App. 

Rate/ units

Max. No. 

Applications/ 

Year 

Max. App. 

Rate per 

Year 

Min. App. 

Interval/ 

days 

AGRICULTURAL/FARM PREMISES 1.1 lb/A NS NS 14 

AGRICULTURAL/FARM STRUCTURES/BUILDINGS 

AND EQUIPMENT 

0.8 lb/A NS NS 14 

ANIMAL KENNELS/SLEEPING QUARTERS 

(COMMERCIAL) 

0.2 lb/A NS NS NS 

BARNS/BARNYARDS/AUCTION BARNS 1.1 lb/A NS NS 14 

CABLES/CABLE COVERINGS (VERT. PEST 

CONTROL) 

0.017 

lb/linear ft 

NS NS NS 

COMMERCIAL/INSTITUTIONAL/INDUSTRIAL 

PREMISES/ EQUIPMENT (OUTDOOR) 

.000094 lb/ 

linear ft or 

expressed in 

lb/gal 

NS NS NS 

EATING ESTABLISHMENTS 0.8 lb/A NS NS NS 

FENCEROWS/HEDGEROWS 0.04 lb/hole 

or .016 

lb/linear ft 

NS NS NS 
 26

Table 3.5. Summary of terrestrial non-food uses for permethrin (except for the uses 

identified in Table 3.2) 

Use Max. App. 

Rate/ units

Max. No. 

Applications/ 

Year 

Max. App. 

Rate per 

Year 

Min. App. 

Interval/ 

days 

HOUSEHOLD/DOMESTIC DWELLINGS OUTDOOR 

PREMISES 

0.1 lb/A; 

0.45 lb/A8; 

20 lb/A9

; 

341 lb/A10

or expressed 

in lb/ linear 

ft or lb/gal 

NS; 

NS; 

NS; 

NS 

0.18 lb/A; 

NS; 

NS; 

NS 

NS; 

NS; 

NS; 

NS 

INDUSTRIAL / CONSTRUCTION AREAS 

(OUTDOOR) 

0.1 lb/A; 

182 lb/A11

NS; 

NS 

0.18 lb/A; 

NS 

NS; 

NS 

LIVESTOCK FEED LOTS 0.46 lb/A NS NS 14 

MEAT PROCESSING PLANT PREMISES (NONFOOD 

CONTACT) 

1.6 lb/A NS NS NS-14 

MUSHROOM HOUSES-EMPTY 

PREMISES/EQUIPMENT 

0.32 lb/A NS NS NS 

NONAGRICULTURAL OUTDOOR 

BUILDINGS/STRUCTURES 

18 lb/A; 

180 lb/A12

NS; 

NS 

NS; 

NS 

NS; 

NS 

NONAGRICULTURAL UNCULTIVATED 

AREAS/SOILS 

0.86 lb/A NS NS 7 

RECREATIONAL AREAS 0.1; 

18 lb/A13

NS; 

NS 

0.18; 

NS 

NS; 

NS 

REFUSE/SOLID WASTE CONTAINERS (GARBAGE 

CANS) 

Expressed in 

lb/gal14

NS NS NS 

REFUSE/SOLID WASTE SITES (OUTDOOR) 0.1 lb/A NS 0.18 lb/A NS 

URBAN AREAS 0.8 lb/A NS NS NS 

UTILITY POLES / RIGHT-OF-WAY 0.017 

lb/linear ft 

or expressed 

in lb/gal 

NS NS NS 

WOOD PROTECTION (OUTDOORS) Up to 512 NS NS NS, 30 

NS = Not Specified; AN = As Needed; cc = crop cycle. Data obtained from LUIS Report. 

Other uses are classified as Indoor Food, Indoor Non-Food, Indoor Residential or Indoor 

Medical. They include cattle feedlots, dairy farm milk handling facilities/equipment, milking 

stalls/parlors or storage facilities, poultry processing plant premises (non-food contact), pets 

living/sleeping quarters, eating establishments, food handling areas (non-food contact), food 

serving areas (non-food contact), feed mills/feed processing plants, food processing plants and 

premises non-food handling areas or non-food contact, food stores/ supermarkets/ market 

premises, empty grain/ cereal/flour elevators, hospitals/medical institutions premises (human/ 

veterinary), commercial transportation facilities, household/domestic dwellings (various), human 

 

8

 Hose end sprayer 

9

 Perimeter treatment 

10 Soil treatment (rodding) – injection equipment 

11 Soil treatment (preconstruction) 

12 Soil treatment (preconstruction) 

13 Perimeter treatment 

14 Spot treatment 
 27

bedding/mattresses, meat processing plant premises (non-food contact), mushroom houses empty 

(premises/equipment), non-feed/non-food empty storage areas, non-feed/non-food treatmentsstorage/processing handling equipment, refuse/solid waste sites (indoors), ships and boats. Uses 

on drainage and sewage systems are classified as aquatic non-food industrial. 

Permethrin also has uses to treat clothing to prevent insect bites, including military clothes. 

“Permethrin is registered for use as both an insecticide and a repellent. Permethrin products are 

used on clothing, shoes, bed nets, and camping gear. Permethrin-impregnated clothing such as 

pre-treated shoes, socks, and pants repel and kill ticks, mosquitoes, and other insects and retain 

this effect after repeated laundering. Permethrin is also found in treated tents, tarps, bed nets, 

sleeping bags, and mattresses.” (Source accessed 01/21/11: 

http://www.epa.gov/pesticides/health/mosquitoes/ai_insectrp.htm ). 

BEAD’s Chemical Profile for Registration Review indicates that “Permethrin also has nonFIFRA pharmaceutical uses as a pediculicide for the treatment of head lice and scabies. The 

Food and Drug Administration (FDA) approved use of the pesticide-containing pharmaceutical 

under the Federal Food, Drug, and Cosmetic Act (FFDCA).” Products for such use include both 

over-the-counter (OTC) and prescribed medications. 

The Agency has limited use and usage information relevant to urban exposures and residential 

uses of pyrethroids, including permethrin. The Agency intends to use available non-agricultural 

use and usage data, such as the Kline database, the California Department of Pesticide 

Regulation’s (CDPR) Pesticide Use Reporting Data and Pest Control Operator’s usage survey, 

and the Residential Joint Venture Task Force homeowner survey data (2003), to inform 

reasonable assumptions regarding various applications and information related to 

urban/residential use and potential environmental exposure. Detailed information on nonagricultural use and usage of pyrethroid products, specifically permethrin, would be useful in 

order to reduce those uncertainties for the final environmental risk assessment for permethrin. 

For example, such information could include usage data, maximum and typical application rates, 

minimum and typical intervals between application, timing of application (seasonal or 

throughout the year), number of applications per year, etc., for the numerous non-agricultural 

uses of permethrin. 

For indoor uses, the Division has conducted environmental risk assessments for a few chemicals 

for Re-registration Eligibility Decisions (including permethrin, but also resmethrin, pyrethrins, 

and others). In one open literature study (Weston and Lydy, 2010), several synthetic pyrethroids 

were observed in effluents after secondary treatment from POTWs in the Sacramento-San 

Joaquin Delta. In the study, bifenthrin was the most frequently detected pyrethroid, while 

permethrin was found in 33% of the municipal wastewater treatment plant effluents (POTWs) 

tested in the Sacramento-San Joaquin Delta (18 samples tested), at a maximum concentration of 

17.2 ng/L, and which exceeded the Hyalella azteca EC50 of 21.1 ng/L in 0% of the samples. 

There is the potential for synthetic pyrethroids to reach surface waters via exposure from 

contaminated drains, and even after treatment in plants (POTWs). Furthermore, EFED has an 

unreviewed study which included monitoring of effluents from a plant in Suffern, NY (Cleary 

and McGrath, 2009, study submitted to the California Department of Pesticide Regulation, 

CDPR) that confirms the presence of various pyrethroids in effluents from the plant. There is 
 28

also an Agency report that identified the presence of permethrin in effluents of 2 out of the 9 

POTWs evaluated.15 EFED will evaluate the potential for exposure to aquatic organisms from 

the indoor uses of permethrin through POTWs in the final ecological risk assessment (for further 

details see Section 6, Conceptual Model and Section 7, Analysis Plan). 

Permethrin Use with Synergists 

 

Piperonyl butoxide (PBO) and MGK-264 are synergists that are commonly used in formulations 

with permethrin. Two examples include Biomist® 3+15 ULV which is used for mosquito control 

and is co-formulated with PBO (EPA Reg No. 8329-33) and Enforcer Ant & Roach Killer III® 

which is co-formulated with MGK-264 (EPA Reg. No. 40849-33). 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). Exposure to pyrethroids along with PBO 

increases the toxicity of the pyrethroids to aquatic invertebrates (Amweg & Weston 2007; 

Weston & Lydy 2010). MGK-264, another potentiator/synergist used with pyrethroids, has 

similar effects as those observed for piperonyl butoxide (Hodgson & Smart 2001). Permethrin 

may be co-formulated with either or both synergists, PBO and MGK-264, in numerous products. 

Available literature data also suggest the potential for synergism in the environment (e.g., 

Amweg et al. 2006, Weston et al. 2006). It is important to recognize that 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. 

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 

products when co-applied with PBO or MGK-264. The need for synergist data 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 

on the acute toxicity of pyrethrin and PBO to target insect species, it is known that the degree of 

toxicity enhancement increases at higher PBO:pyrethrin ratios (or absolute concentrations) and 

that this toxicity enhancement is greater than simple additive toxicity.16 The Agency is currently 

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

pyrethrin to the freshwater amphipod, Hyalella azteca, by simultaneous exposure to PBO at 

varying PBO:pyrethrin ratios. It is expected that this comprehensive testing strategy, when 

augmented with similar acute toxicity data with freshwater fish and other selected pesticide 

active ingredients, will facilitate bridging of the synergist toxicity enhancement to other coformulated or co-applied pesticide/synergist activie ingredients that are not tested at varying 

synergist: active ingredient ratios. With respect to evaluating ecological risks from co-applied 

permethrin and synergists (PBO and MGK-264), the Agency is requesting acute toxicity studies 

 

15 USEPA 2009, Occurrence of Contaminants of Emerging Concern in Wastewater From Nine Publicly Owned 

Treatment Works, EPA-821-R-09-009, August 2009.

16 Stewart, D. 1998. The Evaluation of Synergistic Action in the Laboratory and Field. p. 173-

198 In: Piperonyl Butoxide: the Insecticide Synergist. Academic Press. 
 29

of permethrin TEPs that are co-formulated w/ 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 invertebarate. 

Additional discussion of the need for combined permethrin: synergist toxicity data is provided in 

Section 7.9 (Preliminary Data Gaps). 

Environmental Mixtures 

Toxicity data on environmental mixtures of permethrin with other pesticides may be presented, if 

available, as part of the ecological risk assessment. It is expected that the toxic effect of 

permethrin, in combination with other pesticides used in the environment, is likely to be a 

function of many factors including but not necessarily limited to: (1) the exposed species, (2) the 

co-contaminants in the mixture, (3) the ratio of permethrin and co-contaminant concentrations, 

(4) differences in the pattern and duration of exposure among contaminants, and (5) 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 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, a discussion of 

implications of the available pesticide mixture effects data regarding the confidence of risk 

assessment conclusions will be addressed as part of the uncertainty analysis. EFED will consider 

open literature, currently available models and other lines-of-evidence (e.g., monitoring data), as 

available to address the potential for cumulative effects of pyrethroids in the risk description of 

the ecological assessment for permethrin. 

3.3. Environmental Fate and Transport 

Permethrin’s structure has three rings, two phenyl rings attached to each other by an oxygen 

atom, and a cyclopropyl ring. The structure of the molecule has two chiral centers which raise 

the number of possible isomers to 22

 = 4. Permethrin consists of a mixture of these four isomers 

with the configurations [1R,trans], [1R,cis], [1S,trans], and [1S,cis]. The ratio of cis:trans is 

around 2:3 and 1R:1S is 1:1 (racemic). The [1R,cis] isomer is the most insecticidally active of 

the isomers.

Table 3.6 summarizes the environmental fate/transport properties of permethrin. For 

information about the physicochemical properties of this compound, refer to Table 3.1a and

3.1b. 

Table 3.6. Summary of Environmental Fate Properties for Permethrin and Degradates 

Study Value and unit 

Major Degradate 

Minor Degradates

MRID # 

or 

Citation 

Classificatio

nof Study 

Abiotic Hydrolysis 

Half-life1 = 

Stable, pH 3 

Stable, pH 6 

125-350 days, pH 9 

Major: m-PB-alcohol 

(15.5%), 

Minor: cis-/transDCVA (6.5%) 

00102043 Acceptable 

Air Photolysis Not available N/A N/A N/A 
 30

Table 3.6. Summary of Environmental Fate Properties for Permethrin and Degradates 

Study Value and unit 

Major Degradate 

Minor Degradates

MRID # 

or 

Citation 

Classificatio

nof Study 

Atmospheric 

Degradation 

Half-life1 = 

0.467 days, estimated for 

hydroxyl radical 

N/A EPISuite 

v.4.0 N/A 

Direct Aqueous 

Photolysis 

Half-life1 = 

80 days, pH = 5 

Major: None; Note: In 

the supplemental 

article, cis- and transDCVA and m-PBalc 

are major products with 

UV light (λ > 290 nm). 

40242801 Supplementa

l

17

Soil Photolysis Half-life1

 = 

106 days, loam soil 

Major: None, 

Minor: m-PBA (1.5%), 

and m-PBAlc (4.8%) 

40190101 Acceptable 

Aerobic Soil 

Metabolism 

Half-life1 = 

37 days, sandy loam soil 

Major: CO2 (34-40% 

after 6 months), transDCVA (10% at 14 

DAT), and m-PBA (12-

15% at 30 DAT) 

Minor: (3-(2,2-dichloro 

vinyl)-2-methylcyclo 

propane-l,2-

dicarboxylic acid) (8% 

at 60 days) 

42410002 Acceptable18

Anaerobic Soil 

Metabolism 

Half-life1 = 

204 days, sandy loam soil 

Major: trans-DCVA 

(13% at 60 days) and 

m-PBA (12% at 60 

days) 

41970601 Acceptable19

 

17 Additional information evaluated from Holmstead, R.L., J.E. Casida, L.O. Ruzo, and D.G. 

Fullmer. 1978. Pyrethroid photodecomposition: Permethrin. J. Agric. Food Chem. 1978, 26 (3), 

590-595; and Ruzo, L.O., R.L. Holmstead, and J.E. Casida. 1976. Photochemical Reactions of 

Pyrethroid Insecticides. Tett. Lett. 35, 3045, 1976. However, the available study was conducted 

at a concentration of 0.05-0.06 ppm (solubility of permethrin in water 0.0055 ppm), and up to 

91% of AR was in the walls of the test vials during the study. A new study addressing the above 

mentioned deficiencies is being required. 

18 Partially fulfills the data requirement. Only one soil system was tested. Data on three other 

soil systems are required as per current guidelines. 

19 Partially fulfills the data requirement. Study only lasted 60 days anaerobic incubation, at 

which time, 65-72% AR was parent permethrin. Furthermore, it was conducted using only one 

soil. Data on three other soil systems are required as per current guidelines. 
 31

Table 3.6. Summary of Environmental Fate Properties for Permethrin and Degradates 

Study Value and unit 

Major Degradate 

Minor Degradates

MRID # 

or 

Citation 

Classificatio

nof Study 

Aerobic Aquatic 

Metabolism 

Half-life1 = 

Pond water test system 

from Wilson, NC: 

38.2 days (acid label) total 

system 

42.9 days (alcohol label) 

total system 

Major: trans-DCVA 

(20% at 21 DAT) 

Minor: cis-DCVA 

(3.7%) and m-PBA 

(5.7%) 

43938201 Acceptable20

Anaerobic Aquatic 

Metabolism 

Half-life1 = 

Pond water/sediment 

system from Lucama, NC: 

175 days (acid label) total 

system 

113 days (alcohol label) in 

total system 

Overall half-life1 for the 

isomers 

cis-permethrin 179 days 

trans-permethrin 114 days 

Major: trans-DCVA 

(20.8% at 90 days), 

CO2 (33.8-43.6% by 

367 DAT) 

Minor: cis-DCVA 

(6.6%), m-PBA (3.2% 

at 30 days), m-PBalc 

(0.45% at 30 days) 

43982001 Acceptable21

 

20 Partially fulfills the data requirement. Treatment rate was 1 ppm, which greatly exceeds the 

solubility limit of permethrin; furthermore, the study lasted only 30 days, at which time 56-59% 

AR was permethrin (sum of cis and trans). Data for two additional water/ sediment systems, one 

of marine origin are required. The new studies should address the above mentioned deficiencies 

besides fulfilling current guidelines which indicate that at least two water/sediment systems are 

required. 

21 Partially fulfills the data requirement. The study was performed at a concentration that greatly 

exceeded the solubility limit of permethrin (1 ppm v. 0.0055 ppm). In order to promote 

anaerobicity, glucose was added to the sediment/water system; however, no redox potential was 

measured to confirm that the system was fully anaerobic. Furthermore, only one sediment 

system was evaluated while current guidelines require at least two. A new study is required; 

since there is the potential to use permethrin near marine/estuarine areas, one of the test systems 

should be conducted with water/sediment of marine origin. The new studies should address the 

above mentioned deficiencies besides fulfilling current guidelines which indicate that at least two 

water/sediment systems are required. 
 32

Table 3.6. Summary of Environmental Fate Properties for Permethrin and Degradates 

Study Value and unit 

Major Degradate 

Minor Degradates

MRID # 

or 

Citation 

Classificatio

nof Study 

Permethrin, 

Solid-water 

distribution 

coefficient (Kd) 

Kd, soil texture 

140 L/kg, sand 

217 L/kg, sandy loam 

236 L/kg, silty loam 

246 L/kg, clay loam 

401 L/kg, sandy loam 

sediment 

N/A 41868001 Supplementa

l

22

Permethrin, 

Freundlich solidwater distribution 

coefficient (KF) 

KF, 1/n, soil texture 

446 L/kg, 1.32, sand 

355 L/kg, 1.12, sandy loam 

344 L/kg, 1.09, silty loam 

378 L/kg, 1.10, clay loam 

1,517 L/kg, 1.29, sandy 

loam sediment 

N/A 41868001 Supplementa

l 

Permethrin, 

Organic-carbon 

normalized 

distribution 

coefficient (KOC) 

KOC, soil texture 

60,900 L/kg, sand 

20,900 L/kg, sandy loam 

19,300 L/kg, silty loam 

20,500 L/kg, clay loam 

25,500 L/kg, sandy loam 

sediment 

N/A 41868001 Supplementa

l 

 

22 Study was performed at concentrations of 0.05 to 0.55 ppm, compared to a solubility limit of 

0.0055 ppm in water. Furthermore, a cosolvent concentration of 5% (acetonitrile) was used, 

compared to a recommended ≤0.1%. Even though correlations were good (r2 ≥ 0.966), the 1/n 

values varied from 1.09 to 1.32, with only one of them within the recommended range of 0.9-1.1. 

Extensive degradation occurred particularly for the aquatic sediment. In another study, 

considered supplemental (MRID No. 45170102, not reported in the Table 3.6), the adsorption 

coefficients were much higher than for the supplemental study. For the later study, for three of 

the soils the texture was the same (sandy loam), the soils were sterilized using gamma 

irradiation, and the test was performed at above the solubility limit. However, the cosolvent used 

was also acetonitrile at a lower concentration of 0.25% (recommended ≤0.1%). And the highest 

test concentration was 0.2 ppm (solubility in water of 0.0055 ppm), which may promote 

adsorption. A new study addressing all the above mentioned deficiencies is being required for 

permethrin. 
 33

Table 3.6. Summary of Environmental Fate Properties for Permethrin and Degradates 

Study Value and unit 

Major Degradate 

Minor Degradates

MRID # 

or 

Citation 

Classificatio

nof Study 

Permethrin, 

Freundlich 

organic-carbon 

normalized 

distribution 

coefficient (KFOC) 

KFOC, 1/n, soil texture 

194,000 L/kg, 1.32, sand 

34,100 L/kg, 1.12, sandy 

loam 

28,200 L/kg, 1.09, silty 

loam 

31,500 L/kg, 1.10, clay 

loam 

96,600 L/kg, 1.29, sandy 

loam sediment 

N/A 41868001 Supplementa

l 

m-PBA, 

Freundlich solidwater distribution 

coefficient and 

organic carbon 

normalized 

distribution 

coefficient (KF and 

KFOC) 

KF = 0.98 to 3.11 L/kg 

KFOC = 118 to 215 L/kg 

In sand, silt clay, clay, 

sandy loam, and another 

sandy loam soils 

N/A 43424901 Acceptable 

trans-DCVA, 

Freundlich solidwater distribution 

coefficient and 

organic carbon 

normalized 

distribution 

coefficient (KF and 

KFOC) 

KF = 0.16 to 0.54 L/kg 

KFOC = 18 to 48 L/kg 

In sand, silt clay, clay, 

sandy loam, and another 

sandy loam soils 

N/A 43424901 Acceptable 

Volatility from 

Soil (Laboratory) Study was waived N/A N/A Waived 

Volatility from 

Soil (Field) Study was waived N/A N/A Waived 

Terrestrial Field 

Dissipation 

Dissipation Half-life1,2 = 

Bareground plots 

17 days, NC silt loam soil, 

and 

43 days IL silty clay soil 

Observed: trans-DCVA 

and m-PBA at both NC 

and IL sites 

42359109 Acceptable 
 34

Table 3.6. Summary of Environmental Fate Properties for Permethrin and Degradates 

Study Value and unit 

Major Degradate 

Minor Degradates

MRID # 

or 

Citation 

Classificatio

nof Study 

Aquatic Field 

Dissipation 

Dissipation Half-life1,2 = 

Pond water, California 

1.8/ 1.4 days from the 

pond water for cis-/ transpermethrin; 

118/ 18 days from the 

sediment top 2” for cis-/ 

trans-permethrin 

Observed: cis-DCVA, 

trans-DCVA and mPBA dissipated from 

the water with halflives of 28, 22 & 7.5 

days, respectively. Not 

detected in sediment. 

44030501 Acceptable 

Dissipation Half-life1,2 = 

Pond water, North 

Carolina 

3.1/ 1.4 days from the 

pond water for cis-/ transpermethrin; 

156/ 62 days from the 

sediment top 2” for cis-/ 

trans-permethrin 

Observed: cis-DCVA, 

trans-DCVA and mPBA dissipated from 

the water with halflives of 33, 23 & 14 

days, respectively. Not 

detected in sediment. 

44034101 Acceptable 

Bioconcentration 

Factor (BCF) – 

Bluegill Sunfish 

(Lepomis 

macrochirus) 

Steady State BCF= 

570-610 L/kg wet wt 

whole fish 

180-230 L/kg wet wt 

edible tissue 

950-1,100 L/kg wet wt 

nonedible tissue 

Depuration: 4.7 days for 

50% depuration 

Only trans-DCVA was 

identified, at 4-10% of 

the total radioactivity 

41300401, 

41300402, 

41300403 

Acceptable 

Abbreviations: wt=weight; NA=Not Available; N/A=Not Applicable. 1Half-lives were 

calculated using the single-first order equation and nonlinear regression, unless otherwise 

specified. 2The value may reflect both dissipation and degradation processes. 

As shown in Table 3.6, permethrin is stable to hydrolysis at pHs 3-6, and it degrades at a slow 

rate (t1⁄2 = 125-350 days) in alkaline solutions (pH 9) at 25°C in the dark. The hydrolysis 

products were m-PB-alcohol and cis-DCVA/trans-DCVA. In contrast, permethrin did not 

appear to degrade substantially for a period of 30 days (extrapolated half-life 106 days) on a 

loam soil following irradiation with a xenon arc lamp at 25°C. The reported half-life of 14Cpermethrin in soil under aerobic soil conditions was 37 days, with 14CO2, trans-DCVA and mPBA being the major degradation products. It was noted that the trans-isomer of permethrin 

degraded at a faster rate when compared to the cis-isomer. Furthermore, the degradation of 

permethrin was biphasic, with faster degradation from 0-90 days; however, a half-life for the 

second phase was not provided. A separate supplemental aerobic biodegradation study showed 

that of three factors: application rate, moisture percent and application volume, the first one had 

the greatest effect on the rate of dissipation of permethrin (in the review, it was speculated that 
 35

possibly the microbial activity was inhibited due to toxicity or the solubility may have been 

exceeded) when permethrin was applied to aerobic soil at fortification levels similar to the 

maximum application rate for terrestrial non-food uses (MRID No. 41970602, results not shown 

in Table 3.6). The study lasted a short time (32 days) and only three sampling points were taken 

(0, 14 and 32 days). In an aerobic aquatic metabolism study, the reported half-life ranged from 

38 to 43 days (the study lasted only 30 days). In this study, trans-permethrin yielded shorter 

half-lives than the cis-permethrin. The half-life in the anaerobic soil metabolism study was 204 

days (in a study that lasted 30 aerobic and 60 anaerobic days) and major degradates were transDCVA and m-PBA. The half-lives reported for permethrin in an anaerobic aquatic study ranged 

from 113 days to 175 days, which indicates that the degradation in soil and water/sediment 

systems is slower as the oxygen levels are reduced. Inspection of the available metabolism 

studies shows that high levels of non-extracted residues were observed in some studies (e.g. nonextracted residues reached ~15-35% in the aerobic soil metabolism study at or after 30 days 

posttreatment; however, adequate attempts were made to extract the residues in such instance). 

Permethrin was hardly mobile to immobile (according to the FAO mobility classification) in 

several soils tested, both sterile and viable (KFOC > 10,000 L/kg). KFOC values in the range of 

28,000 to 194,000 L/kg were measured in four soils and one sediment sample. Even though the 

study was found to be acceptable, several deficiencies were found upon a cursory inspection and 

it was downgraded to supplemental (see footnote in Table 3.6). Various literature articles 

document the possibility of desorption of pyrethroids from impervious surfaces despite 

pyrethroids strong sorption (e.g. see Jiang et al. (2010), Jorgenson and Young (2010), and Jiang 

et al. (2011)). In the latter article, the model pyrethroid permethrin was used on concrete 

surfaces. Among their findings, the authors reported that the permethrin desorption from such 

surfaces decreases with sorption time. This was attributed to the possible alkaline decomposition 

of the test substance on the concrete surface. The authors indicated that there is the potential for 

extended contamination due to permethrin treated surfaces. 

In contrast, the main degradates of permethrin, m-PBA and trans-DCVA were shown to have a 

much higher potential for mobility in the soils tested [KFOCs for m-PBA range = 118 to 215 L/kg 

(moderately mobile) and for trans-DCVA range = 18 to 48 L/kg (mobile)]. Based upon its low 

Henry’s Law constant and vapor pressure, permethrin is expected to have a relatively low 

potential for volatilization from soil and water surfaces. 

Acceptable terrestrial field dissipation studies showed that permethrin degraded in the field with 

half-lives ranging from 17 days in a North Carolina field to 43 days for a field located in Illinois. 

These studies were conducted at the terrestrial food use rate of 0.4 lb a.i./A. Neither parent nor 

its two principal soil degradates (trans-DCVA and m-PBA) were detected (detection limits 2.5 

μg/kg) below a depth of 6-inches at either site. More rapid dissipation rates of permethrin were 

reported in a study measuring permethrin concentrations in environmental components of a 

boreal plantation forest in Ontario, Canada treated with an aerial spray of permethrin. 

Permethrin concentrations in soil and forest floor litter ranged from 25 to 7 μg/kg and 33 to 18 

μg/kg, respectively, during the 4 days after application (Sundaram, et al., 1992). These 

concentrations represent measurements taken 1 hour to 4 days after the application of 0.06 lb of 

permethrin per acre (detection limits 2 μg/kg) Permethrin appeared to persist in forest litter 

longer than in soil. Ten days after application, permethrin was not detected in soil while 8 μg/kg 
 36

of permethrin were detected in forest litter. 

An acceptable aquatic field dissipation study employing a site in North Carolina, and a second 

site in California showed that permethrin dissipated (moved) rapidly from the water column by 

binding to suspended solids and sediment. At both sites cis-/trans-permethrin appeared to be 

immobile and remained in the uppermost layer (0-2-inch fraction) of the sediment. There were 

no detects of metabolites in sediment. In North Carolina, cis- and trans-permethrin were 

removed from the water surface with half-lives of 3.1 and 1.9 days, respectively. In sediment the 

reported degradation half-lives for cis- and trans-permethrin were 256 and 62 days, respectively. 

In California, cis- and trans-permethrin were removed from the water surface with half-lives of 

1.8 and 1.4 days, respectively. In sediment the reported degradation half-lives for cis- and transpermethrin were 118 and 18 days, respectively. 

Acceptable fish bioconcentration studies, conducted in bluegill sunfish, showed that permethrin 

bioconcentrated with factors of 950 – 1100x in viscera, 570 – 610x in the whole fish, and 180 – 

230x in the fillet. Depuration occurred at a moderate rate, with 73-83% depuration occurring 

after 14 days and 4.7 days for 50% depuration.

Potential transport mechanisms for a pesticide include surface water runoff, spray drift, and 

secondary drift of volatilized or soil-bound residues leading to deposition onto nearby or more 

distant ecosystems. Surface water runoff and spray drift are expected to be the major routes of 

exposure for permethrin to non-target organisms. The magnitude of transport via secondary drift 

depends on the permethrin’s ability to be mobilized into air and its eventual removal through wet 

and dry deposition of gases/ particles and photochemical reactions in the atmosphere. Therefore, 

physicochemical properties of permethrin that describe its potential to enter the air from water or 

soil (e.g., Henry’s Law constant and vapor pressure), pesticide use data, modeled estimated 

concentrations in water and air, and available air monitoring data are considered in evaluating 

the potential for atmospheric transport of permethrin. Permethrin has a low vapor pressure (1.48 

x 10-8 mmHg) and Henry’s Law constant (1.4x10-6 atm-m3

/mol); thus, volatilization from water 

and soil surfaces is expected to be very low. Permethrin’s potential for volatilization is also 

reduced significantly because it adsorbs strongly to soils. Permethrin’s estimated atmospheric 

half-life is short (~0.5 days for the hydroxyl radical reaction), indicating a low potential for 

transport via volatilized active substance (as opposed to present in suspended solids). 

Limited atmospheric monitoring in California23 was conducted in Butte, Monterey and Santa 

Barbara Counties. Application air monitoring was conducted in Butte County and ambient air 

monitoring was conducted in Monterey County (both in 1997). Of 24 application samples in 

Butte County, three were above the LOQ (LOQ = 0.33 μg/sample, equivalent to 0.015 μg/m3

 for 

24 hour sampling at 15 L/min). The highest concentration was 0.57 μg/m3

. Ambient samples 

were taken in populated areas of Monterey County that coincided with the use of permethrin on 

lettuce and celery. Of the 115 samples collected, six were reported as “detected” and 109 

samples were below the LOD (LOD = 0.10 μg/sample). Monitoring samples were taken in 

Lompoc, an agricultural city in Santa Barbara County in 2000, for a total of 31 pesticides. 

Permethrin was detected at trace levels to 4.3 ng/m3

 (highest 1-day air concentration). 

 

23 http://www.cdpr.ca.gov/docs/emon/pubs/tac/permthrn.htm (accessed 02/04/11). 
 37

4. Receptors 

4.1. Aquatic and Terrestrial Effects 

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

outdoor uses of permethrin, 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 & aquatic invertebrates and terrestrial & aquatic 

plants. This list may not be comprehensive. Spray drift and runoff exposures are expected for 

both ground and aerial applications of permethrin. Consistent with the process described in the 

Overview Document (USEPA, 2004), this risk assessment uses a surrogate species approach in 

its evaluation of permethrin. Toxicological data generated from surrogate test species, which are 

intended to be representative of broad taxonomic groups, are used to extrapolate to potential 

effects on a variety of species (receptors) included under these taxonomic groupings. 

Tables 4.1, 4.2 and 4.3 provide a summary of the taxonomic groups and the surrogate species 

tested to help understand potential acute ecological effects of pesticides to these non-target 

taxonomic groups. In addition, the tables provide a preliminary overview of the potential acute 

toxicity of permethrin, by providing the acute toxicity classifications. 

Terrestrial Species 

Acute toxicity to terrestrial birds and mammals is categorized using the following classification 

system (U.S. EPA, 2004). Toxicity categories for terrestrial plants have not been defined. 

Toxicity Category Oral LD50 Dietary LC50

Very highly toxic < 10 mg/kg < 50 ppm 

Highly toxic 10 - 50 mg/kg 50 – 500 ppm 

Moderately toxic 51 - 500 mg/kg 501 - 1000 ppm 

Slightly toxic 501 - 2000 mg/kg 1001 - 5000 ppm 

Practically non-toxic > 2000 mg/kg > 5000 ppm 

Acute toxicity to terrestrial invertebrates is categorized using the following classification system 

(USEPA, 2004). 

Toxicity Category Acute LD50

Highly toxic < 2 μg ai/bee 

Moderately toxic 2 – 10.99 μg ai/bee 

Practically non-toxic ≥ 11 μg ai/bee 
 38

Table 4.1 Summary of most sensitive endpoints from submitted terrestrial toxicity studies for 

permethrin. 

Species 

(common 

name)

Taxa 

Represented

Endpoint Concentration 

Test 

Substance 

(% a.i.) 

MRID/ 

Citation 

Acute 

Toxicity 

Classification 

Rattus 

norvegicus 

(Laboratory 

Rat) Mammals 

LD50 340.5 mg/kg bw 94 

Cantalamessa

1993 

(ECOTOX 

Ref. # 74863) 

Moderately 

Mouse 

(Mus 

musculus) 

NOAEL 4.9 mg ai/kg bw/day 

94 

Farag et al. 

2006 

(ECOTOX 

Ref. # 100119) 

Not 

Applicable LOAEL 9.8 mg ai/kg bw/day 

Mallard duck 

(Anas 

platyrynchos) 

Birds, terrestrialphase 

amphibians, and 

reptiles 

LD50 >2000 mg ai/kg bw 94.4 

41888401 

Acceptable 

 Practically 

non-toxic 

Bobwhite quail 

(Colinus 

virginianus) 

LC50 >5200 mg ai/kg diet 93.4 

41888403 

Acceptable 

Practically 

non-toxic 

Mallard duck 

(Anas 

platyrynchos) 

NOAEC 125 mg ai/kg diet 

95.2 

42322902 

Acceptable 

Not 

Applicable 

LOAEC 500 mg ai/kg diet 

Apis mellifera

(Honey bee) 

Terrestrial 

invertebrates 

Contact 

LD50

0.024 μg a.i./bee 93.1 

42674501 

Acceptable Highly toxic 

Mammals

Typically, mammalian toxicity data from the Agency's Health Effects Division (HED) are used 

to approximate toxicity to mammals. Wild mammal toxicity tests may be required on a case-bycase basis, depending on the results of the lower tier studies such as acute and sub-acute testing, 

intended use pattern, and pertinent environmental fate characteristics. No studies evaluating 

toxicity to wild mammal species have been submitted by the registrants for permethrin. 

There is one registrant submitted acceptable rat acute oral toxicity study discussed in the HED 

chapter of the Reregistration Eligibility Decision Document (RED) for permethrin (Dated April 

4th 2006; DP Barcode D324993). The reported laboratory rat LD50 value for the technical active 

ingredient of permethrin for females was 2280 mg a.i./kg-bw (3580 mg a.i./kg-bw for males) 

(MRID 00242899). In addition to the data reported to HED, an LD50 value of 8900 mg a.i./kg-bw 

for acute oral toxicity of the permethrin technical active ingredient to laboratory rats was 
 39

reported in the EFED chapter of the RED for permethrin (Dated April 5th 2006; DP Barcode 

D326784). No additional information could be found in the chapter or in the EFED files (No 

MRID; Document Reference No. 279-GNRU, 1978). 

Following the completion of the EFED and HED chapters written for the RED in 2006, 

additional acceptable acute oral toxicity data with the technical active ingredient of permethrin 

(92% a.i.) have been submitted to the Agency (MRID 44707301). The reported laboratory LD50

value for the technical active ingredient of permethrin for female rats (6-8 weeks old) in this 

study was 570 mg a.i./kg-bw (703 mg a.i./kg-bw for males; 614 mg a.i./kg-bw combined). 

In addition to the registrant data, more sensitive acute toxicity data for mammals were identified 

in the open literature were used for quantitative risk estimation purposes in the 2008 endangered 

species assessment (EPA, 2008a). Cantalamessa (1993; ECOTOX Ref # 74863) reported 24-

hour LD50 values of 340.5 (95% CL = 308.8-375.6), 399.0 (95% CL = 346.1-460.0), 471.0 (95% 

CL = 384.5-577.0), and 1500.0 (95% CL = 938.0-2345.3) mg/kg-bw for 8-day old, 16-day old, 

21-day old, and adult rats. LD50 values and associated confidence intervals were determined by 

using ten animals per dose level, with individuals in four or more dose levels being exposed to 

permethrin (94% purity). Based on the range of reported laboratory rat LD50 values from this 

study, permethrin can be classified as moderately toxic to slightly toxic to small mammals on an 

acute oral basis. 

In the HED chapter of the RED for permethrin (Dated April 4th 2006; DP Barcode D324993) one 

registrant-submitted acceptable/guideline three generation reproduction study (MRID 92142092, 

120271, 92142037) with rats was discussed. In this study, permethrin (purity, 94.0-98.8%) was 

administered to groups of 12 male and 24 female rats in the diet at concentrations of 0, 500, 

1000, or 2500 ppm (0, 25, 50, and 125 mg/kg/day, respectively, using a standard conversion 

factor of 0.05). The LOAEL for systemic toxicity is 2500 ppm (125 mg/kg/day) based on 

tremors observed in the F0 females, and the F1 and F2 males and females. The systemic toxicity 

NOAEL is 1000 ppm (50 mg/kg/day). The reproductive toxicity NOAEL is ≥2500 ppm (125 

mg/kg/day) and the reproductive toxicity LOAEL is not identified. The NOAEL for offspring 

growth and development is ≥2500 ppm (125 mg/kg/day) and the offspring LOAEL is not 

identified. However, one of the major deficiencies noted for this study was a lack of 

homogeneity and stability of the compound in the test diets, suggesting that the estimated 

exposure levels may be unreliable. 

In addition to the three generation rat reproduction study, the other studies were discussed in the 

HED RED chapter that demonstrated adverse effects on growth or reproduction of mammals at 

more sensitive quantifiable levels. These studies included an acceptable/guideline prenatal 

developmental study with rats (MRID 40943603) and an acceptable/guideline chronic oral 

toxicity study with dogs (MRID 00129600). In the developmental study with rats, the maternal 

toxicity NOAEL and LOAEL were 50 mg/kg/day and 150 mg/kg/day, respectively, based on 

clinical signs of toxicity and decreased body weight gain and food consumption. The dog chronic 

oral toxicity NOAEL and LOAEL were 50 mg/kg/day and 150 mg/kg/day, respectively, based 

on decreased fetal body weight. However, mean litter weight of the150 mg/kg/day group was 3% 

(n.s.) greater than that of the controls. Therefore, the reduced fetal body weights were considered 

a questionable toxic response. 
 40

In addition to the registrant-submitted data, more sensitive mammalian reproduction toxicity data 

considered for quantitative risk estimation purposes for mammals were identified in the open 

literature in the 2008 endangered species assessment (EPA, 2008a). Farag et al. (2006; ECOTOX 

Ref # 100119) reported a NOAEL of 4.9 mg/kg-bw/day in mice based on increased number of 

dead pups, decreased number of live pups, decreased body weight and body weight gain in pups, 

and decreased maternal body weights. While no significant effects were noted in the lowest test 

group of 4.9 mg/kg-bw/day as compared to the control, significant adverse effects were noted in 

both the 9.8 mg/kg-bw/day and 19.6 mg/kg-bw/day treatment groups. At the LOAEL of 9.8 

mg/kg-bw/day, maternal body weight gain decreased during gestation (↓57% from controls) and 

lactation (↓187% from controls), the number of dead pups increased (↑64% from controls), the 

number of live pups decreased (↓10% from controls), and body weight gain of pups was 

decreased (↓52% from controls). 

Birds

The results of the acute oral toxicity studies available for permethrin indicate that it can be 

classified as practically non-toxic to avian species on an acute oral basis. The acute oral LD50

values for mallard ducks (Anas platyrhynchos), Japanese quail (Coturnix coturnix) and ringnecked pheasants (Phasianus colchicus) range from >2,000 to >23,000 mg a.i./kg-body weight 

(MRIDs 41888401, 00042142, 00042121, 00042120). 

One study has been submitted to the Agency examining the effects of permethrin on passerine 

species of birds. A permethrin (PP 557, 92% w/v active ingredient) acute oral limit test was 

conducted on starlings (Sturnus vulgaris) (MRID 00042144). The test consisted of a vehicle 

control (3 mL corn oil) and a 29,440 mg a.i./kg body weight dose level (32,000 mg PP 557/kg 

body weight). The OSCPP 850.2100 guideline for avian acute oral testing states that a limit test 

may be conducted in lieu of a definitive test at 2,000 mg a.i./kg bw level, if 10 birds are dosed 

and no mortality occurs. No mortality was observed in the control or treatment group during the 

test, nor any differences in food consumption or body weight. No regurgitation was reported, and 

all birds appeared to remain in good health. This study was previously classified as invalid 

because only a summary of the test was submitted. Upon additional review of the full study 

report, this test is classified as invalid due to lack of information in the full study report, 

including documentation that regurgitation was examined after the initial dose and that food was 

withheld prior to dosing. Therefore, this test does not meet the Agency data requirements for a 

passerine acute oral study with permethrin. 

The results of the sub-acute dietary toxicity studies available for permethrin indicate that it can 

be classified as practically non-toxic to avian species on an subacute dietary basis with LC50

values for mallard ducks (Anas platyrhynchos), Northern bobwhite quail (Colinus virginianus), 

Japanese quail (Coturnix japonica) and ring-necked pheasants (Phasianus colchicus) ranging 

from >5,200 to >23,000 mg a.i./kg-diet (MRID 00112939, 41888403, 41888402, 00072845, 

00042123, and 00043733, and ACC# 227722). 

Four avian reproduction studies with mallard ducks (Anas platyrhynchos) and Northern bobwhite 

quail (Colinus virginianus) have been submitted to the Agency for permethrin (MRID 00110670, 
 41

00110671, 42322901, and 42322902). In three of the four studies, there were no observed 

adverse effects on any of the endpoints including food consumption, number of eggs laid, eggs 

cracked, egg shell thickness, viable embryos, live three-week embryos, normal hatchlings, 14-

day-old survivors and offspring body weight (MRID 00110670, 00110671, 42322901). One 

study with bobwhite quail (MRID 42322901) established a LOAEC at the highest tested 

concentration of 500 mg a.i./kg-diet (LOAEC>500 mg a.i./kg-diet). The other two studies with 

no observed adverse effects on bobwhite quail (MRID 00110671) and mallards (MRID 

00110670) only tested up to 25 mg a.i./kg-diet (NOAEC=25 mg a.i./kg-diet, LOAEC>25 mg 

a.i./kg-diet). 

In a permethrin avian reproduction study with mallard ducks, there was a decrease in food 

consumption and an overall decrease in egg production (↓13.2%) at 500 mg a.i./kg-diet (MRID 

42322902). Although these effects were not statistically significant, they were associated with an 

apparent increase in the number of hens with a regressed ovary. The NOAEC and LOAEC for 

this study are 125 and 500 mg a.i./kg-diet, respectively. The results of this study indicate that 

permethrin may have adverse effects on avian reproduction at higher levels of chronic exposure. 

Terrestrial Invertebrates

The Agency guideline terrestrial invertebrate toxicity tests are for honey bees (Apis mellifera). A 

total of six studies that include acute contact, acute oral, and acute contact with treated foliage 

LD50 values for permethrin technical grade active ingredient (TGAI) and formulated permethrin 

and honey bees (MRIDs 42674501, 00045044, 00045046, 42674501, 42009301) have been 

submitted for permethrin. The acute contact LD50 values range from 0.024 (with TGAI) to 0.16 

μg a.i./bee (with formulation), the acute oral LD50 ranges from 0.13 to 0.19 μg a.i./bee (both with 

TGAI), and the single treated foliage study (treated with formulation Ambush 25W) reports an 

LD50 value of < 0.2 lb a.i./A. Based on these results, permethrin is classified as ‘highly toxic’ to 

honey bees on an acute exposure basis. 

In addition to the guideline studies with honey bees, a number of other older studies with 

terrestrial invertebrates and formulated permethrin are available to the Agency. Many of the 

studies have little information reported and the results are presented below as they are in the 

studies. One acute contact 5-day study with various species of parastitic wasps (MRID 

05009995) demonstrates a range in sensitivity of the five tested species (Apanteles sp., Opius 

bruneipus, Telenomus remus, Copidosoma truncatellum, and Diglyphus intermedius), with 

mortality ranging from 0% to 85% at 0.1 lb a.i./A, and 40% to 100% at 0.2 lb a.i./A. A study 

with alkali bees (Nomia melanderi) exposed to foliage treated with formulated permethrin 

reported mortality ranging from 25% to 78% at rates ranging from 0.5 oz. a.i./A to 2 o.z. a.i./A, 

respectively (NR 1975). Another study with alfalfa leafcutter bees (Megachile rotundata 

pacifica), exposed to foliage treated with formulated permethrin reported mortality ranging from 

24% to 88% at rates ranging from 0.5 oz. a.i./A to 2 o.z. a.i./A, respectively (ICI US1975). In 

other studies with mites (Amblyseium fallacis), convergent ladybeetles (Hippodamia 

convergens), and predatory mites (Metaseiulus occidentalis) acutely exposed to formulated 

permethrin, LD50 values ranging from <0.5 to 15.5 ppm a.i. were reported (MRID 00045048, 

05009995, 00045048, ICI US 1975, ICI US 1976, ICI US NR). 
 42

Open literature studies on permethrin acute contact toxicity to terrestrial insects were obtained 

via the USEPA ECOTOX database and screened for acute toxicity endpoints that were more 

sensitive than the acute LD50 endpoint obtained from submitted data on the honeybee (i.e., 0.024 

ug a.i./organism or 0.1875 ug a.i./g-organism; MRID 42674501). The ECOTOX database 

contained laboratory-based, acute contact LD50 results for species in four Orders in the Class 

Insecta: Hymenoptera, Coleoptera, Lepidoptera, and Diptera.. Based on this information, it 

appears that honeybee represents reasonably the sensitivity of the more sensitive terrestrial 

invertebrates in the context of acute, contact permethrin toxicity (US EPA 2010). 

Based on several considerations, the need for additional permethrin toxicity or exposure data for 

pollinators was evaluated. First, permethrin is a non-systemic insecticide with respect to its 

uptake and distribution in terrestrial plants. Therefore, concerns over potential exposure of 

pollinators to permethrin can be mitigated for crops with flowering via restrictions on the timing 

of application in relation to bee foraging activity. 

Second, data from the open literature were reviewed for estimating potential exposure and effects 

of permethrin to pollinators, particularly for residues in hives and effects on endpoints other than 

mortality (e.g., reproduction, behavior effects per 40 CFR Part 158). Specifically, Mullin et al. 

(2010) recently reported pesticide residues in bee, pollen and wax samples from managed 

apiaries with unknown pesticide exposure history. In their study, Mullin et al reported residues 

of permethrin ranging from 12 to 19600 ppb in immature and adult bees (5.7% detection in 140 

samples), 9.6 to 92 ppb in pollen (2.6% detection in 350 samples) and 31-372 ppb in wax (1.9 % 

detection in 258 samples). Based on pollen consumption estimates of 6.5 mg pollen/bee/day for 

nurse bees obtained from the open literature (Rotais et al 2005), these maximum concentrations 

reported in pollen and wax result in estimated 2-day exposures of about 1/100th to 1/25th the 

acute 48-h oral LD50 value of 0.13 μg ai/bee. The extraordinarily high permethrin residues 

reported in worker bees (nearly 20 mg ai/kg bee) are reportedly derived from a permethrin bee 

kill incident, according to the author’s study. Under greenhouse conditions, Cox and Wilson 

(1984) reported that abdominally-administered permethrin at 0.009 ug ai/bee resulted in 

mortality and failure of worker bees to return to the hive when simultaneiously exposed to 

naturally fluctuating temperatures (15-35C). The authors also reported behavorial changes of 

worker bees when exposed abdominally to permethrin at 0.001 ug ai/bee. In another study, Dai 

et al. (2010) examined the sublethal effects of two other synthetic pyrethroids, i.e., deltamethrin 

and bifenthrin, on bee colony health when administered via water:sucrose solution for worker 

bees (6.1 and 29.6 mg ai/L) and directly to queens (5 ul/queen) for 20 days. The authors 

concluded that exposure to each of these chemicals (at approximately the LD05) adversely 

impacted bee reproduction by reducing bee fecundity and decreasing the rate of bee development 

into adulthood. 

A third consideration for the need for additional pollinator data is the current state of the science 

regarding pollinator risk assessment. Specifically, the Agency acknowledges that several 

scientific activities related to pollinator risk assessment practices and data needs are currently 

pending or under development (e.g., the report from the 2011 SETAC-Pellston workshop on 

pollinator risk assessment and a FIFRA Scientific Advisory Panel (SAP) review of this same 

topic planned for spring of 2012). 
 43

Therefore, in consideration of the aforementioned information concerning the non-systemic 

nature of permethrin foliar residues and subsequent risk mitigation options, the nature of residues 

reported in pollen, wax and bees, and further development of pollinator risk assessment methods 

and guidelines, the Agency is not requesting additional data on permethrin exposure and effects 

on pollinators as part of this preliminary Problem Formulation. Instead, the Agency is placing the 

need for additional data “In Reserve” pending the outcome of the aforementioned scientific 

activities, comments from stakeholders on the need for additional data, and the review of 

additional information concerning this topic. Specifically, the Agency requests that stakeholders 

submit additional scientific information on the exposure and effects of permethrin to pollinators 

not considered in this preminalry problem formulation. 

Aquatic Species 

Toxicity to fish and aquatic invertebrates is categorized using the the following system (U.S. 

EPA, 2004). Toxicity categories for aquatic plants have not been defined. 

LC50 (ppm) Toxicity Category 

< 0.1 Very highly toxic 

> 0.1 - 1 Highly toxic 

> 1 - 10 Moderately toxic 

> 10 - 100 Slightly toxic 

> 100 Practically nontoxic 

Table 4.2 Summary of most sensitive endpoints from submitted aquatic toxicity studies for 

permethrin. 

Species 

(common 

name)

Taxa 

Represented Endpoint Concentration (ug 

a.i./L) 

MRID Acute Toxicity 

Classification 

Bluegill 

Sunfish 

(Lepomis 

macrochirus) Freshwater Fish 

and Aquaticphase 

Amphibians 

LC50 0.79 

00042128 

Supplemental Very highly toxic 

Fathead 

Minnow 

(Pimephales 

promelas) 

NOAEC 0.301

00110666 

Acceptable Not Applicable 

LOAEC 0.41 

Waterflea 

(Daphnia 

magna) Freshwater 

Invertebrates 

EC50 0.0392 MRID 00043736 

Acceptable Very highly toxic 

Waterflea 

(Daphnia 

magna) 

NOAEC 0.0393

MRID 43745701 

Acceptable Not Applicable 

LOAEC 0.084 
 44

Table 4.2 Summary of most sensitive endpoints from submitted aquatic toxicity studies for 

permethrin. 

Species 

(common 

name)

Taxa 

Represented Endpoint Concentration (ug 

a.i./L) 

MRID Acute Toxicity 

Classification 

Atlantic 

Silverside 

(Menidia 

menidia) Estuarine/Marine 

Fish 

LC50 2.2 

40228401 

Supplemental Very highly toxic 

Sheepshead 

Minnow 

(Cyprinodon 

variegatus) 

NOAEC 104 

41068007 

Unreviewed Not Applicable 

LOAEC 22 

Stone crab 

(Menippe 

mercenaria) Estuarine/Marine 

Invertebrates 

EC50 0.018 

40228401 

Supplemental Very highly toxic 

Mysid shrimp 

(Americamysis 

bahia) 

NOAEC 0.0115 41315701 

Acceptable Not Applicable 

LOAEC 0.024 

1

 In the latest Agency risk assessment that looked at permethrin effects to aquatic species (US EPA 2008a), the chronic 

NOAEC for freshwater fish was estimated to be 0.0515 μg a.i./L using an acute-to-chronic ratio (based on fathead 

minnow ACR=15.34) with the most sensitive species in submitted acute freshwater fish studies, bluegill sunfish 

(Lepomis macrochirus). 2 In the latest Agency risk assessment that looked at permethrin effects to aquatic species (US EPA 2008a), the most 

sensitive acute EC50 value of 0.0212 μg a.i./L (Anderson et al., 2005; ECOTOX Ref. # 90039) for amphipods (Hyalella 

azteca). Upon further review, this study is determined to be supplemental information that is not suitable for quantitative 

purposes. The most sensitive acceptable freshwater aquatic invertebrate acute toxicity study is displayed here. 3

 In the latest Agency risk assessment that looked at permethrin effects to aquatic species (US EPA 2008a), the chronic 

NOAEC for freshwater invertebrates was estimated to be 0.0014 μg a.i./L using an acute-to-chronic ratio (based on 

fathead minnow ACR=15.34) with the most sensitive species in available acute freshwater invertebrate studies, the 

amphipod Hyalella azteca. Note that the empirical chronic NOAEC is similar to the most sensitive acute EC50 in the 

previously submitted studies. 

4

 In the latest Agency risk assessment that looked at permethrin effects to aquatic species (US EPA 2008a), the chronic 

NOAEC for estuarine/marine fish was estimated to be 0.1434 μg a.i./L using an acute-to-chronic ratio (based on fathead 

minnow ACR=15.34) with the most sensitive species in submitted acute estuarine/marine fish studies, Atlantic silverside 

(Menidia menidia). 5

 This mysid life cycle study did not evaluate the effects of permethrin exposure on reproduction due to poor control 

performance. Note that the empirical chronic NOAEC is similar to the most sensitive acute LC50 in the available 

registrant-submitted studies. In the latest Agency risk assessment that looked at permethrin effects to aquatic species (US 

EPA 2008a), the chronic NOAEC for estuarine/marine invertebrates was estimated to be 0.0012 μg a.i./L using an acuteto-chronic ratio (based on fathead minnow ACR=15.34) with the most sensitive species in submitted acute 

estuarine/marine invertebrate studies, stone crab (Menippe mercenaria). 

Freshwater Fish

The acute toxicity studies available to the Agency demonstrate that permethrin can be classified 

as very highly toxic to freshwater fish on an acute basis, with LC50 values ranging from 0.79 to 

72 μg a.i./L for a number of different species. The LC50 values ranging from 0.79 to 17.0 μg 

a.i./L for permethrin TGAI, and from 2.3 to 72.0 μg a.i./L for formulated permethrin. Bluegill 
 45

sunfish (Lepomis macrochirus) exhibited the most sensitive acute LC50 value of 0.79 μg a.i./L 

for freshwater fish (MRID 00042128). 

One acceptable life-cycle study on fathead minnows (Pimephales promelas) was available to the 

Agency to evaluate the effects of chronic exposure to permethrin (95.7% a.i.) on freshwater fish 

(MRID 00110666). The study demonstrated that chronic exposure to concentrations as low 0.41 

μg a.i./L has the potential to cause reproductive toxicity. A significant reduction in the number of 

surviving fry at 0.41 μg a.i./L relative to the controls was observed (8% vs. 85-95% survival in 

controls). No other adverse effects were noted on growth or number of eggs produced. 

Therefore, the NOAEC and LOAEC for this study are 0.30 μg a.i./L and 0.41 μg a.i./L, 

respectively. 

In the latest Agency risk assessment that looked at permethrin effects to aquatic species (US 

EPA 2008a), the chronic NOAEC for freshwater fish was estimated to be 0.0515 μg a.i./L using 

an acute-to-chronic ratio (based on fathead minnow ACR=15.34) with the most sensitive species 

in submitted acute freshwater fish studies, bluegill sunfish (Lepomis macrochirus). 

Estuarine/Marine Fish

The acute toxicity studies available to the Agency demonstrate that permethrin can be classified 

as highly toxic to very highly toxic to estuarine/marine fish, with LC50 values ranging from 2.2 to 

>300 μg a.i./L. The studies also demonstrate that the technical grade active ingredient can be 

classified as very highly toxic, with LC50 values ranging from 2.2 to 7.8 μg a.i./L. Formulated 

permethrin is classified as highly toxic to estuarine/marine fish with a single reported LC50 value 

of >300 μg a.i./L. The most sensitive acute LC50 value in an estuarine/marine fish study was 2.2 

μg a.i./L (MRID 40228401) for Atlantic silversides (Menidia menidia). 

One early life-stage study with sheepshead minnows (Cyprinodon variegatus) was available to 

the Agency to evaluate the effects of chronic exposure to permethrin (93% a.i.) on 

estuarine/marine fish (USEPA Gulf Breeze 1983, MRID 41068007 [unreviewed]). The study 

demonstrated that chronic exposure to concentrations as low 22 μg a.i./L has the potential to 

cause reduced survival in hatched fish. No effects were observed on weight, length or survival of 

hatched fish at 10 μg a.i./L. However, the chronic NOAEC in this study is higher than the most 

sensitive acute LC50 in submitted estuarine/marine fish studies. In the latest Agency risk 

assessment that looked at permethrin effects to aquatic species (US EPA 2008a), the chronic 

NOAEC for estuarine/marine fish was estimated to be 0.1434 μg a.i./L using an acute-to-chronic 

ratio (based on fathead minnow ACR=15.34) with the most sensitive species in submitted acute 

estuarine/marine fish studies, Atlantic silverside (Menidia menidia). 

Freshwater Invertebrates

The acute toxicity studies available to the Agency demonstrate that permethrin can be classified 

as slightly toxic to very highly toxic to freshwater invertebrates, with EC50 values ranging from 
 46

0.039 to <25,000 μg a.i./L. Formulated permethrin is classified as slightly toxic to very highly 

toxic, with EC50 values ranging from 0.76 to <25,000 μg a.i./L. 

Evidence in open literature suggests that Hyalella azteca is among the most sensitive aquatic 

invertebrates to permethrin based on acute water column tests (Weston and Lydy, 2010; Brander 

et al., 2009). For the 2008 Agency California red-legged frog and San Francisco Bay species risk 

assessment (USEPA 2008a), a study was identified in the open literature which reported a more 

sensitive EC50 value (Anderson et al., 2005; ECOTOX Ref. # 90039). This study was conducted 

to determine the toxicity of permethrin to the baetid mayfly Procloeon sp., the amphipod 

Hyalella azteca, and the midge Chironomus dilutus. The determined 48-hour (Procloeon sp.) 

and 96-hour (H. azteca and C. dilutus) EC50 values for the mayfly, amphipod, and midge were 

0.0896, 0.0212, and 10.45 μg a.i./L, respectively. Specifically, the estimated EC50 value for H. 

azteca is of interest because it is more sensitive than the most sensitive toxicity value from the 

other studies available to the Agency. This study has been reviewed and the most sensitive acute 

EC50 value of 0.0212 μg a.i./L (Anderson et al., 2005; ECOTOX Ref. # 90039) for amphipods 

(Hyalella azteca). However, upon additional review, the study previously used for permethrin 

toxicity to Hyallela azteca is determined to be acceptable for supplemental (not quantitative) use 

in the upcoming Agency ecological risk assessment for permethrin. This decision is based on 

concerns with test substance stability during the study and high solvent control mortality (the 

solvent used was at levels approximately 20 times higher than Agency guideline 

recommendations for aquatic toxicity tests). 

There are a total of two chronic exposure studies with technical-grade permethrin involving 

freshwater invertebrates. These two guideline life-cycle studies with waterfleas (Daphnia 

magna) report NOAEC values ranging from 0.039 to 0.28 μg a.i./L. The first study reported the 

NOAEC and LOAEC as 0.039 and 0.084 μg a.i./L, respectively, based on 14% and 4% 

reductions in the number of young produced per female and length, respectively (MRID 

43745701). Decreased adult survival was also observed at 0.34 μg a.i./L. In the second life cycle 

study, total production of young per adult and adult survival were decreased by 13% and 4%, 

respectively, at 0.56 μg a.i./L (EPA Beltsville TN 2420, 1979). The NOAEC was reported as 

0.28 μg a.i./L. The available information indicates that daphnids are not as sensitive as other 

freshwater invertebrates. Therefore, chronic effects to these more sensitive species will need to 

be addressed in the forthcoming risk assessment, either through the use of open literature data or 

through toxicity extrapolations (acute-chronic ratios using amphipod data). 

In the latest Agency risk assessment that looked at permethrin effects to aquatic species (US 

EPA 2008a), the chronic NOAEC for freshwater invertebrates was estimated to be 0.0014 μg 

a.i./L using an acute-to-chronic ratio (based on fathead minnow ACR=15.34) with the most 

sensitive species in available acute freshwater invertebrate studies, the amphipod Hyalella 

azteca. Note that the empirical chronic NOAEC is similar to the most sensitive acute EC50 in the 

previously submitted studies. 

No toxicity studies have been submitted to the Agency that examine the effects of permethrin to 

freshwater benthic organisms. Chronic sediment toxicity data for the freshwater midge 

Chironomus dilutus (Formerly Chironomus tentans) were identified as an outstanding data 

requirement in the permethrin Reregistration Eligibility Document (US EPA 2009b). The 
 47

registrant has submitted protocols for chronic sediment tests with both Chironomus dilutus

(MRID 48035202) and the freshwater amphipod Hyalella azteca (no MRID assigned) and the 

Agency has provided protocol reviews (DPs 379360 and 382674). 

Estuarine/Marine Invertebrates

The acute toxicity studies available to the Agency demonstrate that permethrin can be classified 

as moderately toxic to very highly toxic to estuarine/marine invertebrates, with EC50 values 

ranging from 0.018 to 6500 μg a.i./L. For bivalves, EC50 values ranged from >407 to 6500 μg 

a.i./L (none of these tests were determined to be acceptable) and 0.018 to 7.6 μg a.i./L for the 

rest of the estuarine/marine invertebrates. The studies also demonstrate that both the technical 

grade active ingredient and formulated permethrin can be classified as moderately toxic to very 

highly toxic, with EC50 values ranging from 0.018 to >1050 μg a.i./L and 0.51 to 6500 μg a.i./L, 

respectively. The most sensitive acute EC50 value for estuarine/marine invertebrates is 0.018 μg 

a.i./L (MRID 40228401) for stone crabs (Menippe mercenaria). 

Two estuarine/marine invertebrate chronic exposure studies with permethrin are available to the 

Agency. The first life-cycle study with mysids (Americamysis bahia) reports NOAEC and 

LOAEC values of 0.011 and 0.024 μg a.i./L, respectively, based on a 20% increase in mortality 

at the LOAEC relative to the control (MRID 41315701). While no adverse effects on growth 

were noted based on adult body weight (length measurements were not taken), the effects of 

chronic exposure to permethrin on reproduction of mysids could not be evaluated in this study 

due to significant study limitations (i.e., poor reproductive performance of controls). Therefore, 

the utility of this study for risk assessment purposes is severely limited. The other chronic 

permethrin study conducted with mysids was determined to be invalid because no raw data was 

reported to enable verification of results, stock solution mix-ups and excessive deaths related to 

the mysids jumping from the test containers (MRID 40102001). 

This mysid life cycle study did not evaluate the effects of permethrin exposure on reproduction 

due to poor control performance. Note that the empirical chronic NOAEC is similar to the most 

sensitive acute LC50 in the available registrant-submitted studies. In the latest Agency risk 

assessment that looked at permethrin effects to aquatic species (US EPA 2008a), the chronic 

NOAEC for estuarine/marine invertebrates was estimated to be 0.0012 μg a.i./L using an acuteto-chronic ratio (based on fathead minnow ACR=15.34) with the most sensitive species in 

submitted acute estuarine/marine invertebrate studies, stone crab (Menippe mercenaria). 

No toxicity studies have been submitted to the Agency that examine the effects of permethrin to 

estuarine/marine benthic organisms. Chronic sediment toxicity data for Leptocheirus plumulosus

were identified as an outstanding data requirement in the permethrin Reregistration Eligibility 

Document (US EPA 2009b). The registrant has submitted a protocol for a chronic sediment test 

with Leptocheirus plumulosus (MRID 48035201) and the Agency has provided reviews (DPs 

379360). 

Aquatic-phase Amphibians
 48

Previously for the 2008 listed species assessment, a number of studies involving amphibian 

toxicity testing and permethrin were identified in the open literature for the previous ecological 

assessment for permethrin (US EPA 2008a). None of these studies provided estimates of toxicity 

that were ultimately used quantitatively in this risk assessment. However, they do provide some 

information regarding the hazard of permethrin to amphibians and will be used for 

characterization in the upcoming risk assessment. 

Effects of degradates on aquatic organisms 

Various degradates were observed in the laboratory studies (e.g. m-PBA, m-PBAlc, and cis- and 

trans-DCVA). These studies indicate that all of the identified degradates were the result of the 

rupture of the ester bond of the parent molecule. It has been believed that the resulting 

molecules are not as toxic as the parent because they presumably have lost the neurotoxic mode 

of action. Table 3.1c (above) shows the chemical structures of permethrin’s major degradation 

products. 

Evaluation of the chemical structure of permethrin degradates suggests little similarity to the 

active parent compound, and the cleavage of the ester linkage during degradation of the parent 

structure is expected to result in a significantly decreased toxicity of those degradates relative to 

the parent. Limited data are available for the acute effects of DCVA on aquatic invertebrates. 

Acute 48-hour studies examining effects of DCVA on Daphnia magna resulted in an EC50 = 25 

mg a.i./L (MRID 00158556), which shows much lower toxicity to aquatic invertebrates than the 

parent compound permethrin (Daphnia magna 48-hour EC50s range from 0.04 to 9.9 μg a.i./L for 

the parent compound permethrin; MRIDs 00043736, 00110662, 00043736, 40098001, 

00110663, 00110662, 00042139, 43740602 and 42584002). Based on these lines of evidence, 

this assessment focuses only on the parent, cis- and trans-permethrin. 

These conclusions are in agreement with EPA’s Health Effects Division’s (HED) approach of 

considering only the parent as the residue of concern for purposes of tolerance expression and 

risk assessment (HED chapter of the Reregistration Eligibility Decision Document (RED) for 

permethrin, 6th revision dated April 1st 2009; DP Barcode D357566, see Appendix I). At this 

time, the degradates will not be considered stressors of concern in the forthcoming 

environmental fate and ecological risk assessment. 

Temperature-based effects on permethrin toxicity to aquatic organisms

The effect of temperature on permethrin toxicity is discussed by Weston et al. (2009a). 

Sediment toxicity tests were performed at various temperatures (13, 18, 23 and 28oC). The 10-

day LC50s to Hyalella azteca were determined in lab tests conducted on four pyrethroids 

(lambda-cyhalothrin, permethrin, bifenthrin and esfenvalerate). The toxicity approximately 

doubled when the temperature was decreased from 23 to 18oC, and approximately tripled when 

the temperature was further decreased to 13oC. This effect has implications for aquatic organisms 

that inhabit water bodies in colder climates (Weston et al. 2011). The potential for temperaturemediated changes in pyrethroid toxicity will be examined in the upcoming risk assessment for 

permethrin. 
 49

Plants

Table 4.3. Permethrin Toxicity Profile for Plant Species 

Species % A.I. 

Toxicity Endpoint 

μg a.i. /L 

Study 

Classification 

MRID/ 

Reference 

Freshwater Non-vascular Plants 

Marine algae 

Selenastrum 

costatum 

Not 

reported1 

EC50 96 hr : 68 and 72 μg a.i./L 

Yield (Cell count)

EC50 96 hr: 68 μg a.i./L 

NOAEC: Not reported 

Absorbance

EC50 96 hr: 72 μg a.i./L 

NOAEC: Not reported 

Supplemental ECOTOX 

Ref #5297 

(Walsh and 

Alexander, 

1980) 

Marine algae 

Selenastrum 

costatum 

93 EC50 96 hr : 92 μg a.i./L 

NOAEC: Not reported 

Supplemental 40228401 

Blue-green 

algae, 

Anabaena 

inequalis

14.7 Yield (Cell density)

EC50: 1.6 mg a.i./L 

NOAEC: Not reported 

Growth rate

EC50: 5.0 mg a.i./L 

NOAEC: Not reported 

Photosynthesis

EC50: >100 mg a.i./L 

NOAEC: Not reported 

Acetylene reduction

EC50: >100 mg a.i./L 

NOAEC: Not reported 

Supplemental ECOTOX 

Ref #4684 

(Stratton et al., 

1980) 

No studies evaluating the toxicity of permethrin to terrestrial plants have been submitted to the 

Agency. 

Only one study examining the toxicity of permethrin to non-vascular aquatic plants is available 

to the Agency (MRID 40228401). This study involving technical permethrin (93% a.i.) and the 

marine diatom (Skeletonema costatum) reports an EC50 value of 92 μg a.i./L However, no 

NOAEL, raw data, or additional information were reported. 
 50

For the 2008 California red-legged frog and San Francisco Bay species (USEPA 2008a) and the 

2010 Valley Elderberry Longhorn Beetle (Desmocerus californicus dimorphus) permethrin 

assessments (USEPA 2010), only two other studies establishing EC50 values for non-vascular 

plants were identified in the open literature. The first (Stratton et al., 1980; ECOTOX Ref # 

4684) laboratory toxicity assay was conducted to determine the effects of permethrin on the 

growth (yield and rate), 14CO2 uptake, and acetylene reduction of the blue-green alga, Anabaena 

inequalis. The study determined the EC50 of permethrin towards growth yield, growth rate, 

photosynthesis (uptake of 14CO2 and NaH14CO3), and acetylene reduction to be 1.6, 5.0, >100 

and >100 mg a.i./L, respectively. However, no NOAEL or raw data were reported. 

The second open literature study (Walsh and Alexander, 1980; ECOTOX Ref # 5297) was 

conducted to evaluate methodologies of marine algal bioassays and to determine the effects of 

permethrin on the marine alga, Skeletonema costatum. The 96-hour static toxicity test yielded 

growth EC50 values of 68 and 72 μg a.i./L, based on cell counts and absorbance, respectively. 

However, no NOAEL or raw data were reported. 

No acceptable data from registrant-submitted studies or the open literature on the toxicity of 

permethrin to aquatic vascular plants were available to the Agency for this assessment. 

ECOTOX 

Available open literature will be used to evaluate the potential direct effects of permethrin to the 

terrestrial receptors identified in this section. This includes toxicity data on the technical grade 

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

The open literature studies will be identified through EPA’s ECOTOX database 

(http://cfpub.epa.gov/ecotox/), which employs a literature search engine for locating chemical 

toxicity data for aquatic life, terrestrial plants, and wildlife. The evaluation of data can also 

provide insight into the direct and indirect effects of permethrin 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. Open literature toxicity data for other ‘target’ insect 

species (not including bees, butterflies, beetles, and non-insect invertebrates including soil 

arthropods and worms), which include efficacy studies, are not currently considered in deriving 

the most sensitive endpoint for terrestrial insects. Efficacy studies do not typically provide 

endpoint values that are useful for risk assessment (e.g., NOAEC, EC50, etc.), but rather are 

intended to identify a dose that maximizes a particular effect (e.g., EC100). Therefore, efficacy 

data and non-efficacy toxicological target insect data will not be included in the ECOTOX open 

literature search. 

4.2. Incident Database Review 

A review of the Ecological Incident Information System (EIIS, v. 2.1) and Aggregate Incident 

databases for ecological incidents involving permethrin was completed on January 4, 2011. This 

database consists of exposure incident reports submitted to the EPA from 1994 to present. A 
 51

search for incidents involving permethrin was also conducted in the American Bird 

Conservancy’s Avian Incident Monitoring System (AIMS). 

The reports are listed in order of certainty, from highly probable to unrelated. Incidents listed in 

EIIS are categorized by the likelihood that a particular pesticide is associated with that particular 

incident. These classifications include highly probable, probable, possible, unlikely or unrelated. 

“Highly probable” incidents usually require carcass residues or clear circumstances regarding the 

exposure. “Probable” incidents include those where residue information was not available or 

circumstances were less clear than those for “highly probable”. “Possible” incidents occur when 

multiple chemicals may have been involved and the contribution of an individual chemical is not 

obvious. An “unlikely” incident classification is given when a given chemical is considered 

nontoxic to the type of organism involved or the chemical was analyzed and not detected in 

samples. The “unrelated” category is used for incidents confirmed not to involve pesticides. No 

unrelated incidents were listed for permethrin. 

The number of reports listed in the EIIS database is believed to be only a small fraction of the 

total incidents involving organismal mortality and damage caused by pesticides. Few resources 

are assigned to incident reporting. Reporting by states is only voluntary, and individuals 

discovering incidents may not be informed on the procedure of reporting these occurrences. 

Additionally, much of the database is generated from registrant-submitted incident reports. In 

addition, incident reports for non-target organisms typically provide information only on 

mortality events and plant damage incidents. Except for phytotoxic effects in terrestrial plants, 

sublethal effects for organisms such as reduced growth or impaired reproduction are rarely 

reported. Because of these logistical difficulties, EIIS is most likely a minimal representation of 

all pesticide-related ecological incidents. 

Registrants are legally required to provide detailed reports of only “major” ecological incidents 

involving pesticides, while “minor” incidents are reported aggregately. Based on 40 CFR 

§159.184, an ecological incident is considered “major” and must be submitted to the Agency by 

the registrant if any of the following criteria are met:

Fish or wildlife: 

(A) Involves any incident caused by a pesticide currently in Formal Review24 for 

ecological concerns. 

(B) Fish: Affected 1,000 or more individuals of a schooling species or 50 or more 

individuals of a non-schooling species. 

(C) Birds: Affected 200 or more individuals of a flocking species, or 50 or more 

individuals of a songbird species, or 5 or more individuals of a predatory species. 

(D) Mammals, reptiles, amphibians: Affected 50 or more individuals of a 

relatively common or herding species or 5 or more individuals of a rare or solitary 

species. 

 24 Formal Review means Special Review, Rebuttable Presumption Against Registration 

(RPAR), FIFRA section 6(c) suspension proceeding, or FIFRA section 6(b) cancellation 

proceeding, whether completed or not. 
 52

(E) Involves effects to, or illegal pesticide treatment (misuse) of a substantial tract 

of habitat (greater than or equal to 10 acres, terrestrial or aquatic). 

Plants: 

(A) The effect is alleged to have occurred on more than 45 percent of the acreage 

exposed to the pesticide. 

All other incidents are considered “minor”. All ecological incidents considered “minor” only 

need to be aggregately reported as quarterly counts of incidents by the registrant(s). Ecological 

incidents reported in aggregate reports include those categorized as ‘minor fish and wildlife’ (WB), ‘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 permethrin, 

registrants have reported 14 minor fish and wildlife incidents, 149 minor plant incidents, 

and 4 other non-target incidents. Unless additional information on these aggregated incidents 

become available, they will be assumed to be representative of registered uses of permethrin in 

the risk assessment. 

The EIIS database contained 41 incidents involving permethrin. The reports included 26 

aquatic animal incidents, 8 terrestrial animal permethrin-related incidents and 8 plant 

incidents (one terrestrial incident involved both plants and animals). 

The AIMS database contains no avian incidents involving permethrin. 

A summary of ecological incidents involving permethrin included in the EIIS database are listed 

in Appendix B. 

Aquatic Incidents

The majority of ecological incidents involving permethrin occurred in aquatic environments. 

Twenty-six aquatic incidents caused by permethrin have been reported to the EPA since 1994. 

Of these incidents, nine are listed as highly probable, ten as probable, and seven under possible. 

Twenty-three incidents affected fish species, and the other three reports involved crayfish. 

Approximately half (thirteen) of the incidents resulted from registered use of permethrin. Many 

of these incidents originate with permethrin application to residences or other buildings, 

followed by permethrin runoff into nearby water bodies. 

One case listed as a possible permethrin-related event involved frogs. A mosquito control 

employee of the Maryland Department of Agriculture sprayed permethrin within 100 feet of a 

pond, and one day later many frogs, fish and crayfish were found dead. Although the applicator’s 

certificate was suspended, permethrin is implicated as only a possible cause because no tissues or 

water samples were analyzed. 

Plant Incidents

Seven permethrin incident reports were recorded for terrestrial plant species. All incidents were 

only listed as possible or unlikely. Two reports involved registered use. The first registered-use 

incident involved both permethrin and piperonyl butoxide, and the plant damage could not be 

solely attributed to either chemical. In the second registered-use incident, many pesticides were 

involved and imazethapyr was suspected to be the cause of any plant injuries, not permethrin. 
 53

Terrestrial Incidents

Six permethrin incidents involving terrestrial animals exist in the EIIS database. Two incidents 

were listed as highly probable, and four as possible. One of the highly probable incidents 

resulted from registered use. A municipality was sprayed with permethrin, and hundreds to 

thousands of dead butterflies were found by residents of the area shortly after application. 

Species listed in these reports included bee, monarch butterfly, other unknown butterflies, 

parakeet, dog, unknown birds, unknown trees and ornamental plants. . 

In the forthcoming ecological risk assessment, these incidents will be further evaluated to 

determine if they represent current patterns of use for permethrin. Examples of additional 

considerations are mitigation (e.g., reduced application rates), product cancellations, and changes 

in use patterns that have occurred since the date of the reported incidents. In addition, any known 

incidents that occur between the time the PF document is issued and the final risk assessment 

will be included in the risk assessment. 

4.3. Ecosystems Potentially at Risk 

Permethrin may be applied on a variety of food/feed crops, including (but not limited to), alfalfa, 

nut trees, corn, leafy vegetables, stone fruits, pome fruits, fruiting vegetables, cucurbit 

vegetables, cole crops, onion and soybean. In addition, it may be used on numerous non-food 

sites (e.g. conifers, forest trees, ornamentals, golf courses, and ornamental lawns and turf, 

rangeland, as an adulticide and for wood protection). Thus, the ecosystems at risk may be 

extensive in scope, and as a result it may not be possible to identify specific ecosystems during 

the development of a baseline risk assessment. In general terms, terrestrial ecosystems 

potentially at risk due to the use of permethrin, could include the treated field and areas 

immediately adjacent to the treated field that may receive drift or runoff. Areas adjacent to the 

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

grasslands, woodlands, riparian habitats and other uncultivated areas. Due to the potential 

persistence of permethrin, it is expected to drift and/ or runoff due to application to food crops 

and certain non-crop sites, resulting in possible exposure to aquatic ecosystems. Aquatic 

ecosystems potentially at risk due to the use of permethrin include water bodies adjacent to, or 

down stream from the treated field and might include impounded bodies such as ponds, lakes and 

reservoirs, or flowing waterways such as streams or rivers. For uses in coastal areas, aquatic 

habitat also includes marine ecosystems, such as estuaries. 

5. 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 
 54

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 

permethrin. 

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

maximum application rate to fields that have vulnerable soils. 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 

permethrin. More sensitive endpoints from acceptable open literature studies will be included in 

the ecological risk assessment. 

 6. Conceptual Model 

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

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

environment from a source to an ecological receptor. For an ecological 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. 

A conceptual model provides a written description and visual representation of the predicted 

relationships between permethrin, 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). 

6.1. Risk Hypothesis 

Risk hypotheses are specific assumptions about potential adverse effects (i.e., changes in 

assessment endpoints) and may be based on theory and logic, empirical data, mathematical 

models, or probability models (USEPA 1998). For this assessment, the risk is stressor-initiated, 

where the stressor is the release of permethrin into the environment. The following risk 

hypotheses are presumed for this screening-level assessment: 
 55

Permethrin, when used outdoors in accordance with registered labels, will likely lead to 

off-site movement of the compound via agricultural and urban runoff, spray drift, and 

eroded soil leading to exposure of nontarget plants and animals Based on information 

on the environmental fate, mode of action, direct toxicity and potential indirect effects, 

EFED assumes that registered uses of permethrin have the potential to cause reduced 

survival, growth, and reproduction to non-target terrestrial and/ or aquatic animals and 

plants. 

Permethrin, when used indoors for numerous uses, including pre-treated clothing, pet 

shampoos, prescribed or over-the-counter products, etc., in accordance with current 

labels, may result in off-site movement of the compound via wash-off into surface waters 

via drains and municipal wastewater treatment plants, leading to exposure of nontarget 

aquatic plants and animals. This potential exposure pathway may result in adverse 

effects upon the survival, growth, and/or reproduction of non-target aquatic animals and 

plants. 

Permethrin, when used for the treatment of cattle (and certain other animals), in 

accordance with current labels, may result in off-site movement of the compound via 

wash-off of cattle and calves into surface waters, leading to exposure of nontarget 

aquatic plants and animals. This potential exposure pathway may result in adverse 

effects upon the survival, growth, and/or reproduction of non-target aquatic animals and 

plants.

 

The conceptual model is a generic graphic depiction of the risk hypothesis. It includes the 

potential pesticide or stressor (permethrin and possible metabolites, as well as synergists), the 

source of the pesticide and/or transport pathways, exposure media, exposure point, biological 

receptor types, and attribute changes. 

6.2. Conceptual Diagram 

The conceptual site model is a generic graphic depiction of the risk hypothesis, and assumes that 

the insecticide permethrin, which is a Type I synthetic pyrethroid, having multiple outdoor 

agricultural and non-agricultural uses, is capable of affecting aquatic and terrestrial animals 

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

uses. Based on an examination of the physicochemical properties of permethrin, the fate and 

disposition in the environment, and mode of application, a conceptual model was developed that 

represents the possible relationships between the stressors, ecological receptors, and the 

assessment endpoints. Through a preliminary iterative process of examining available data, the 

conceptual model (i.e., the representation of the risk hypothesis) may be refined to reflect the 

likely exposure pathways and the organisms that are most relevant and applicable to this 

assessment (Figures 6.1a and 6.1b). They include the potential pesticide or stressor (permethrin, 

but the presence of toxicologically important metabolites and/ or synergists cannot be ruled out), 

the sources and/ or transport pathways, exposure media and exposure points, biological receptor 

types and attribute changes. 
 56

In order for a chemical to pose an ecological risk, it must reach ecological receptors in 

biologically significant concentrations. An exposure pathway is the means by which a pesticide 

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 for the chemical, its metabolites/ transformation products are of greater 

toxicological concern than the parent compound. The assessment of ecological exposure 

pathways, therefore, includes an examination of the source and potential migration pathways for 

constituents, and the determination of potential exposure routes. 

Under the possible uses of permethrin, the sources and mechanisms of release of the compounds 

are from ground or aerial spray or ULV applications. Note that this conceptual model considers 

agricultural applications as well as certain non-agricultural applications. Surface runoff from the 

areas of application is assumed to depend on factors such as topography, irrigation, and rainfall 

events. Direct deposition may result in contamination of food items that may be consumed by 

terrestrial organisms. Spray drift results in contaminated adjacent areas, including bodies of 

water. Leaching to groundwater is not considered an important source because permethrin, like 

many other pyrethroids, shows low mobility in a variety of soils. Permethrin appear to have a 

low potential for volatilization, with a low vapor pressure and Henry’s Law Constants. Further, 

the hydroxyl radical reaction half-life for permethrin is ~0.5 days (EPI Suite v.4.0 estimate). The 

short (atmospheric) half-life, the low vapor pressure (~10-8 mmHg) and relatively low Henry’s 

Law constant (~10-6 atm/m3-mol), and its binding capacity, suggest that the potential for 

atmospheric transport for permethrin is relatively low and that this source of the chemical is of 

low importance, compared to spray drift, runoff and/ or direct contact after application. 

For aquatic receptors, the major point of exposure is through direct contact with the water 

column, sediment, and pore water (gill/ integument) contaminated with spray drift (from spray 

application) and/or runoff and flow (e.g., piped storm drains) from treated areas. Indirect effects 

to aquatic organisms (both fish and aquatic invertebrates) can also occur through impact to 

various food chains. The representative aquatic receptors are certain freshwater and estuarine/ 

marine fish, invertebrates, and, in certain cases, aquatic plants. The major point of exposure for 

terrestrial animals is consumption of food contaminated with residues such as grass, foliage, and 

small insects. For plants, the point of exposure is direct contact or root uptake. The 

representative terrestrial receptors are mammals, birds and terrestrial plants. The attribute 

changes used to assess risk to terrestrial receptors depend on the type of test (e.g., reduced 

survival, growth, or reproduction for animals and seedling emergence and vegetative vigor for 

plants). It should be noted, that these species do not cover all the possible species in the animal 

and plant kingdoms; certain taxa are considered as surrogates for other taxa. For example, fish 

are considered surrogates for aquatic phase amphibians. 

This conceptual model also shows details about biomagnification for a chemical (see piscivorous 

birds and mammals in Fig. 6.1b). It was established earlier in this document that permethrin 

may have some potential to bioaccumulate/ bioconcentrate. The reported value of log octanol/ 
 57

water partition coefficient of 6.1 (KOW = 1.3 x 106) suggests that permethrin has the potential to 

bioaccumulate in aquatic organisms, assuming that chemical metabolism is negligible. However, 

the measured bioconcentration factor in fish (Table 3.5) is much lower than that expected based 

on KOW alone, which suggests that permethrin metabolism by fish is substantial. However, there 

appears to be some potential for bioaccumulation/ bioconcentration in aquatic organisms, and 

biomagnification in terrestrial organisms. 

Permethrin shows a very low solubility, a very high KOW and also high KOCs. These properties 

suggest that the chemicals partition with the sediments, and with organic matter, suspended in 

the water bodies. Permethrin is likely to concentrate in the sediments, especially after repeated 

exposures (applications), where it could persist. Such sediments could serve as repositories of 

the chemical for extended periods of time and could potentially be toxic to sediment dwelling 

organisms, affecting the food chain. These issues will also be assessed in the risk assessment for 

permethrin. 

Figure 6.1a. Aquatic conceptual model depicting stressors, exposure pathways, and 

potential effects to aquatic organisms from the use of permethrin on agricultural and 

certain non-agricultural sites 

1

 Includes flow across vegetation and vegetated drainage systems (e.g., swales) and flow across 

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

Stressor 

Source 

Receptors 

Attribute 

Change 

Permethrin applied to agricultural or non-agricultural use site 

Spray drift

Aquatic animals 

Invertebrates 

Vertebrates 

**Piscivorous mammals 

 and birds 

Individual organisms 

Reduced survival (2)

Reduced growth

Reduced reproduction 

Food chain 

Reduction in algae and 

 vascular plants 

Reduction in prey 

Modification of PCEs 

 related to prey

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 6.1b 

Impervious 

Surfaces

Flow (1)
 58

impervious surfaces and through impervious (piped) storm drains. 

2

 Immobilization is considered equivalent to mortality in toxicity tests for aquatic invertebrates.

Dotted lines indicate exposure pathways that have a low likelihood of contributing to ecological 

risk. 

Figure 6.1b. Terrestrial conceptual model depicting stressors, exposure pathways, and 

potential effects to terrestrial organisms from the use of permethrin on agricultural and 

certain non-agricultural sites 

Dotted lines indicate exposure pathways that have a low likelihood of contributing to ecological 

risk. 

*See Figure 6.1c for drinking water and inhalation exposure pathways for terrestrial vertebrates 

and ingestion of residues in dew by terrestrial invertebrates. 

Drinking water, inhalation and dermal exposure pathways to terrestrial species

Drinking water 

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

Stressor 

Source 

Attribute 

Change 

Permethrin applied to agricultural or non-agricultural use sites 

Direct 

application Spray drift 

Terrestrial 

vertebrates* 

Terrestrial 

Invertebrates* 

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 
 59

upper bound estimate of exposure using permethrin’s solubility (0.0055 mg/L; Laskowski, 

2002), the most sensitive acute and chronic avian toxicity endpoints (LD50 > 2000 mg ai/kg bw 

and NOAEC = 125 mg ai/kg diet, respectively) and the most sensitive acute and chronic 

mammalian toxicity endpoints (LD50 = 340.5 mg/kg bw; NOAEL = 4.9 mg ai/kg bw/day, 

respectively). Drinking water exposure alone was not determined to be a potential pathway 

of concern for avian or mammalian species on an acute or chronic basis. 

Although drinking water exposure alone does not appear to be of concern, this does not take into 

account that when aggregated with other exposure pathways (dietary food sources, dermal, 

inhalation) drinking water may contribute to a total exposure that has a potential for effects on 

non-target animals and should be explored further. Because there is a high degree of 

conservatism in the SIP 1.0 exposure estimate, there is limited expectation that use scenarios not 

triggering a SIP 1.0 concern would contribute significantly to aggregate risks from water plus 

diet when a refined water exposure model is incorporated in the actual quantitative risk 

assessment. Detailed information about 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. 

Inhalation 

Screening Tool for Inhalation Risk v.1.0 (STIR) was used to provide an upper bound estimate of 

permethrin exposure of birds and mammals to pesticides through inhalation of spray drift or 

vapor. It also provides an estimate of avian inhalation toxicity in the absence of such data based 

on available acute inhalation and oral mammalian toxicity endpoints as well as acute avian oral 

toxicity endpoints. The 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, the chemical specific avian 

allometric scaling factor to adjust toxicity based on body weight for the chemical (if available), 

the weight of the tested bird, a rat acute oral LD50 value, a rat acute inhalation LC50 value, the 

duration of the rat inhalation study, and the weight of the tested rat. 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. Risk quotients (RQs) for inhalation exposure are not derived, and this tool will 

not be used to make risk determinations. Instead, the tool compares the ratio of exposure and 

toxicity to a threshold of 0.1, similar to the Agency’s LOC for listed terrestrial animals, and 

determines whether inhalation from spray drift or vapor phase pesticide alone may be a concern 

for mammals and/or birds. 

The model tool is also available online on the OPP models web page at the following address: 

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

STIR could not be utilized for permethrin due to the absence of acute mammalian inhalation 

toxicity data (USEPA, 2009a). However, inhalation exposure alone was not determined to be 

a potential pathway of concern for avian or mammalian species, based upon permethrin’s 

low vapor pressure (1.48 x 10-8 mm Hg) and low acute avian toxicity (LD50 > 2000 mg ai/kg 

bw) and acute mammalian toxicity (LD50 = 340.5 mg/kg bw). 
 60

Dermal Exposure 

Potential exists for permethrin dermal exposure to terrestrial wildlife. At the present time, the 

Agency does not have a method to quantify levels of dermal exposure from chemical 

applications, but is actively working on a screening tool to account for this route of exposure. 

Figure 6.1c. Terrestrial conceptual model depicting stressors, drinking water and 

inhalation exposure pathways, and potential effects to terrestrial organisms from the use of 

permethrin on agricultural and certain non-agricultural sites 

Dotted lines indicate exposure pathways that have a low likelihood of contributing to ecological 

risk.

Down-the-Drain Exposure 

The conceptual model for potential risks of permethrin to aquatic organisms due to various 

indoor uses of the chemical that could potentially end up in a “drain” is depicted in Fig. 6.2. The 

stressor is the chemical of concern, permethrin. It is noted that the transport pathway is 

wastewater flow, the exposure media is the treatment facility and the exposure point or route, 
 61

receptor, and attribute changes for aquatic organisms are similar to the conceptual model for 

agricultural applications. 

Figure 6.2. Conceptual model for potential risks of permethrin to aquatic organisms for 

various indoor uses of the chemical that could potentially end up in the “drain.” 

 

The conceptual model for potential risks of permethrin to terrestrial and aquatic organisms as a 

result of the treatment on cattle or calves is depicted in Fig. 6.3. The stressor is the chemical of 

concern, permethrin, and potentially interactions caused by applications with the synergist PBO. 

The organisms that could be expected to be affected are terrestrial plants, aquatic plants and 

aquatic animals. It is noted that the potential transport pathway, the exposure media and the 

exposure point or route, receptor, and attribute changes for plant and aquatic organisms are 

similar to the conceptual model for agricultural applications Fig. 6.1a. 

 

Stressor Permethrin applications that could potentially end up “downthe-drain”

Source/ 

Transport 

Pathways 

Wastewater flow 

Source/ 

Exposure 

Media 

Treatment facility 

discharges into surface 

waters 

Exposure 

Route 

Gill/ 

 Integument 

Uptake 

Receptors 

Attribute 

Changes 

Aquatic 

Invertebrates, 

Vertebrates

Individual 

Vertebrates and 

Invertebrates

Reduced 

survival or 

Plant 

Population

Reduced 

population 

th

Aquatic 

Plants

Uptake/ 

Adsorption
 62

Figure 6.3: Conceptual model for potential risks of permethrin to aquatic organisms as a 

result of the treatment on cattle or calves. 

 

7. Analysis Plan 

In order to address the risk hypothesis, the potential for adverse effects on the environment is 

estimated. Usage, environmental fate and transport, and ecological effects of permethrin are 

characterized and integrated to assess the risks. This is accomplished using a risk quotient (ratio 

of exposure concentration to effects concentration) approach. Although risk is often defined as 

the likelihood and magnitude of adverse ecological effects, the risk quotient-based approach does 

not provide a quantitative estimate of likelihood and/ or magnitude of an adverse effect. 

However, 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 doseresponse 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 on the data available in the 

Stressor Permethrin and PBO Used as for theTreatment of Cattle and Other Animals 

(Immersion in Surface Water Body or Washoff Transported Nearby or to Surface Waters) 

Source/ 

Transport 

Pathways 

Surface waters 

Source/ 

Exposure 

Media 

Riparian/ 

Wetland 

Foliage/Soil Receiving Water Body/ 

Sediment 

Exposure 

Route 

Direct Contact/ 

Root Uptake Gill/ 

 Integument 

Uptake 

Receptors 

Attribute 

Changes 

Aquatic 

Invertebrates, 

Vertebrates 

Wetland/ 

Riparian 

Plants 

Individual Plants

Reduced survival, 

growth, or reproduction 

Individual 

Vertebrates and 

Invertebrates

Reduced survival 

or reproduction 

Plant Population

Reduced 

population 

growth 

Aquatic 

Plants 

Uptake/ 

Adsorption
 63

open literature and the information submitted by the public or the registrant in response to the 

opening of the Registration Review docket. 

7.1. Stressors of Concern 

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

review open literature to identify degradate(s) of potential toxicological concern (e.g., cis- and 

trans-DCVA, m-PBA and m-PBalc). Also, risk resulting from use of permethrin with the 

synergist PBO will be assessed for cattle treatments. 

Toxicity data for environmental mixtures of permethrin with other pesticides (those mixtures 

occurring in the environment following application), if available, may be presented as part of the 

ecological risk assessment. Permethrin may be applied in tank mixtures with other products 

approved for use on registered crops. It is expected that the toxic effect of permethrin, in 

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

factors including, but not necessarily limited to (1) the exposed species, (2) the co-contaminants 

in the mixture, (3) the ratio of permethrin and co-contaminant concentrations, (4) differences in 

the pattern and duration of exposure among contaminants, and (5) the differential effects of other 

physical/ chemical characteristics of the receiving waters (e.g. organic matter present in sediment 

and suspended water). A discussion of 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. 

7.2. Measures of Exposure 

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

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

rates for the current use patterns. Available aquatic monitoring data, from sources such as the US 

Geological Survey and the California Stormwater Quality Association, will also be considered 

when describing potential environmental exposure to non-target organisms. 

Measures of exposure are based on aquatic and terrestrial models that predict estimated 

environmental exposure concentrations (EECs) of permethrin using maximum labeled 

application rates and methods, as well as any mitigation measures specifically indicated on the 

label. The models used to predict aquatic EECs are the Pesticide Root Zone Model coupled with 

the Exposure Analysis Model System (PRZM/EXAMS). Also, to estimate aquatic exposure 

related to releases of permethrin from domestic wastewater treatment plants, the Exposure and 

Fate Assessment Screening Tool’s (E-FAST2) down-the-drain module will be used. For the 

treatment of cattle, measures of exposure will be calculations assuming direct applications to 

water considering living habits of cattle livestock. The model used to predict terrestrial exposure 

is T-REX. The model used to derive EECs relevant to terrestrial and wetland plants is TerrPlant. 

The potential for bioaccumulation for the chemical is assessed using the KABAM model, as well 

the results from bioconcentration in fish studies (e.g. the bioconcentration factors). These 

models are parameterized using relevant reviewed registrant-submitted environmental fate and 

transport data. 
 64

PRZM (v.3.12.2, May 2005) and EXAMS (v.2.98.4.6, April 2005) are screening simulation 

models coupled with the input shell PE5.pl (August, 2007) to generate daily exposures and 1-in10 year EECs of permethrin, that may occur from spray drift and runoff to surface water bodies 

adjacent to application sites. PRZM simulates pesticide application, movement and 

transformation on an agricultural field and the resultant pesticide loadings to a receiving water 

body via runoff, erosion and spray drift. The EXAMS model simulates the fate of the pesticide 

and resulting concentrations in the water body. The standard scenario 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 cubic meters volume) with no outlet. 

PRZM/ EXAMS is used to estimate screening-level exposure of aquatic organisms to permethrin 

and/ or its transformation products, should they be of concern. The measure of exposure for 

aquatic species is the 1-in-10 year return 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 chronic exposure to fish and aquatic-phase amphibians. 

The 1-in-10-year 21-day mean is used for assessing aquatic invertebrate chronic exposure. 

At the present time, EFED considers the use of the impervious scenario (a PRZM modeling 

scenario) 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 the residential or other suitable scenario 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 in order 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 publicized studies on this occurrence have been found in the open 

literature); however, the assumption is consistent with the standard assumption of 1% spray drift 
 65

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 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 permethrin and its likelihood to occur in sediment, the Agency will 

also consider the potential exposures resulting from benthic/ sediment concentrations (EECs). 

Pore water concentrations are commonly used to predict toxicity of non-ionic substances in 

sediments and characterize exposure to organisms that spend time in or near sediments (Di Toro 

et al. 1991; US EPA 2002). PRZM/ EXAMS estimates 1-in-10-year peak and 21-day mean 

EECs for pore water. 

To estimate exposure related to releases of permethrin 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 permethrin that could 

potentially be exposed 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). 

There are two possible scenarios whereby permethrin residues can enter the aquatic ecosystem 

due to treatment to cattle. First, multiple cattle that are treated with permethrin can directly enter 

a water body, and second, rainfall can cause washoff of permethrin residues to be transported 

from treated multiple cattle to water bodies via runoff. For these cases, surface water 

concentrations will be calculated using the maximum mass of permethrin per animal, spilling 

into a standard farm pond of 1 ha area and 2 m depth or a volume of 2.0 x 107

 L. Surface water 

EECs will be calculated utilizing a suitable program which considers the soil-water partition 

coefficient and the depth of the sediment layer such as the KdCalc (v.1.0 10/02/02). Certain 

assumptions are required for these scenarios. For example, for the first scenario, 20 treated cattle 

may be assumed to enter the water and for the second scenario, a 1000 treated cattle feedlots may 

be assumed (USDA NASS data).25 A maximum of 100% of the active ingredient is assumed to 

wash-off cow hide for pour on products. 

 

25 http://www.nass.usda.gov/Surveys/Guide_to_NASS_Surveys/Cattle_On_Feed/index.asp

(accessed 02/01/11) “Feedlots with 1,000 or more head capacity represent about 85 percent of all 

fed cattle in the U.S.” 
 66

Exposure estimates for terrestrial animals assumed to be in the target area are derived using the 

T-REX model (version 1.3.1, 12/07/2006). This spreadsheet-based model calculates the residues 

on avian and mammalian food items along with the dissipation rate of a chemical applied to 

foliar surfaces (for single or multiple applications) in order to estimate acute and reproductive 

risk quotients. T-REX calculates EECs and risk quotients based on both the upper bound and 

mean residue concentrations as presented by Hoerger and Kenaga (1972) and modified by 

Fletcher et al. (1994). These concentrations are determined using nomograms that relate 

application rate of a pesticide to residues remaining on dietary items of terrestrial organisms. 

EECs for terrestrial plants inhabiting dry and wetland areas are derived using TerrPlant (version 

1.2.2, 12/26/2006). 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. 

As indicated in Table 3.1 and its associated text in Section 3, permethrin appears to have some 

potential to bioconcentrate in aquatic organisms and it appears that there is also some potential to 

biomagnify in terrestrial organisms. The potential for bioaccumulation of permethrin will also 

be examined in the risk assessment. Because permethrin has a fairly high KOW (1.3 x 106

) and 

the chemical may be persistent in water and sediments, there is a potential for bioaccumulation. 

The maximum bioconcentration factor was 570-610x for whole fish and depuration rate is 

moderate (half depuration time of 4.7 days, MRID Nos. 41300401, 41300402 and 41300403). 

Bioaccumulation will 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 which have bioaccumulated these pesticides. Monitoring data and 

biotransformation rates in terrestrial species will also be evaluated, to assess the potential for 

bioaccumulation in terrestrial food webs. 

7.3. Measures of Effect 

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

Data are typically 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 Mid-Continent 

Ecology Division. 

The acute measures of effect used for animals in this assessment are the LD50, LC50 and EC50. 

LD stands for "Lethal Dose", and LD50 is the amount of a material, given all at once, that is 

estimated to cause the death of 50% of the test organisms. LC stands for “Lethal Concentration” 

and LC50 is the concentration of a chemical that is estimated to kill 50% of the test organisms. 

EC stands for “Effective Concentration” and the EC50 is the concentration of a chemical that is 
 67

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 NOAEL/NOAEC 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 

NOAEC (i.e., “No-Observed-Adverse-Effect-Concentration”) is the highest test concentration at 

which none of the observed effects were statistically different from the control. 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 NOAEC or EC05 is used. 

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

the Ecological Incident Information System (EIIS) and Aggregrate Incident Reports. 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. Information on incidents involving 

avian species is also provided through the Avian Monitoring Information System (AIMS), which 

is maintained by the American Bird Conservancy. 

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 the 

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

assumption is made for fish and aquatic-phase amphibians. 

7.4. Integration of Exposure and Effects 

Risk characterization is the integration of exposure and ecological effects to determine the 

potential ecological risk from the use of pesticides and the likelihood of direct and indirect 

effects to non-target organisms in aquatic and terrestrial habitats. The exposure and toxicity 

effects data are integrated in order to evaluate the risks of adverse ecological effects on nontarget species. For the assessment of risks, the risk quotient (RQ) method is used to compare 

exposure and measured toxicity values. EECs are divided by acute and chronic toxicity values. 

The resulting RQs are then compared to the Agency’s Levels of Concern (LOCs) (USEPA 

2004). These criteria will be used to indicate when permethrin uses, as directed on the label, 

have the potential to cause adverse direct or indirect effects to non-target organisms. In addition, 

incident data from the EIIS will be considered as part of the risk characterization. 

. 

7.5. Deterministic and Probabilistic Assessment Methods 

The quantitative assessment of risk will primarily depend on the deterministic point-estimate 

based approach described in the risk assessment. An effort may also be made to further 

qualitatively describe risk using probabilistic tools that the Agency has developed. These tools 
 68

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. 

7.6. 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 permethrin. 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 permethrin 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 permethrin 

application occurs), plus all areas where offsite transport 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/ or cellular level of 

organization. In situations where it is not possible to determine the threshold for an observed 

effect, the action area is not spatially limited and is assumed to be the entire United States. 

7.7. Drinking Water Assessment 

A drinking water assessment will be conducted to support future human health risk assessments 

of permethrin should it be required, based on all the available environmental fate information. 

The drinking water assessment will incorporate model estimates of permethrin in surface and 

ground waters. Concentrations in surface waters will be estimated using FQPA Index Reservoir 

Screening Tool (FIRST, v.1.1.1, 12/18/07) (or subsequently using PRZM/ EXAMS, with the 

Index Reservoir – for description see above – if refinements are required). Ground water 

estimates of concentrations will be obtained using the Screening Concentration In GRound 

Water (SCI-GROW) model (v.2.3, July 2003). The drinking water assessment will also include 

a summary of available surface and ground water monitoring data. 

7.8. Endocrine Disruptor Screening Program 

As required under FFDCA section 408(p), EPA has developed the Endocrine Disruptor 
 69

Screening Program (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, and 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. 

 

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. 

This list of chemicals was selected based on the potential for human exposure through pathways 

such as food and water, residential activity, and certain post-application agricultural scenarios. 

This list should not be construed as a list of known or likely endocrine disruptors. 

Permethrin is among the group of 58 pesticide active ingredients on the initial list to be screened 

under the EDSP. The Agency will review the EDSP Tier 1 data and any “other scientifically 

relevant information” submitted in response to test orders. Based on this review the Agency will 

determine the need for additional testing. For further information on the status of the EDSP, the 

policies and procedures, the list of chemicals, the test guidelines and the Tier 1 screening battery, 

please refer to the following website: http://www.epa.gov/endo/ . 

7.9. Preliminary Identification of Data Gaps 

The California Department of Pesticide Regulation (CDPR) placed permethrin and other 

synthetic pyrethroids into reevaluation in 2006. Certain data requirements were imposed to those 

pyrethroids. EPA is already in communication with CDPR and their data should also be 

submitted to the Agency. More information on the CDPR reevaluation program for pyrethroids 

is located at http://www.cdpr.ca.gov/docs/registration/reevaluation/chemicals/pyrethroids.htm. 

7.9.1. Environmental Fate 

After evaluation of the available data for permethrin, the following data gaps for registration 

review have been identified. 

Guideline Studies: 

835.2240 Aqueous Photolysis - The solubility of permethrin in water is 0.0055 ppm and the 

available study was conducted at a concentration of 0.05-0.06 ppm, which is around 10 times 

higher. Furthermore, up to 91% of AR was adsorbed to the walls of the test vials during the 
 70

study. After initially found to be unacceptable, the registrant submitted two literature articles on 

the aqueous photodegradation of permethrin, and a previous review indicated that a good faith 

effort was made to provide information regarding this data requirement; however,the review did 

not appear to explain clearly the problems found in the study . The study does not provide a 

reliable half-life value, since a large percentage AR was in the walls of the test vial. 

Furthermore, there is uncertainty regarding the possibility of formation of major degradates. 

This study was previously considered acceptable; however, upon further inspection, EFED has 

downgraded it to supplemental. In order to provide reliable data on the aqueous photolysis 

behavior of permethrin, a new study is required. The study should address the above mentioned 

deficiencies, provide a reliable aqueous photolytic half-life value, and information about possible 

degradates of permethrin. 

835.4100 Aerobic Soil Metabolism - There is an aerobic soil metabolism study, conducted on a 

single soil system, which is deemed acceptable. Due to the fact that only one soil half-life is 

available, there is uncertainty related to the magnitude of the half-life for permethrin in soils. 

According to current guidelines, aerobic soil metabolism studies with one soil type are generally 

sufficient for the evaluation of transformation pathways. Rates of transformation should be 

determined in at least three additional soils (per Fate, Transport and Transformation Test 

Guidelines – OCSPP Guideline 835.4100 & 835.4200). At this time, aerobic soil metabolism 

studies are required to be conducted in three additional different soils in order to fulfill current 

OCSPP guideline requirements. The new studies will provide three additional half-lives in 

different soils, resulting in more knowledge and certainty related to the behavior and persistence 

of permethrin in aerobic soils. For metabolism studies, domestic soils are preferred. 

835.4200 Anaerobic Soil Metabolism – The available study, which was considered acceptable, 

only lasted 60 days of anaerobic incubation, at which time 65-72% AR remained as undegraded 

parent permethrin. Furthermore, it was performed on a single soil system. Thus, it supplies only 

very limited information, with only a few sampling periods. According to current guidelines, 

anaerobic studies with one soil type are generally sufficient for the evaluation of transformation 

pathways. Rates of transformation should be determined in at least three additional soils (per 

Fate, Transport and Transformation Test Guidelines – OCSPP Guideline 835.4100 & 835.4200). 

The registrant is required to perform new anaerobic soil metabolism studies in three different 

soils in order to fulfill current OCSPP guidelines and to address the above mentioned 

deficiencies. The new studies will provide three additional half-lives in different soil systems, 

resulting in more knowledge and certainty related to the behavior and persistence of permethrin 

in anaerobic soils. For metabolism studies, domestic soils are preferred. 

835.4300 Aerobic Aquatic Metabolism - In the available study, which was considered 

acceptable, the treatment rate was 1 ppm, which greatly exceeds the solubility limit of 

permethrin; furthermore, the study lasted only 30 days, at which time ≥56% AR was undegraded 

permethrin (sum of cis- plus trans-isomers); and finally, only one water/ sediment system (from 

Wilson, NC) was analyzed. According to the OCSPP Fate, Transport and Transformation Test 

Guidelines (835.4300 & 835.4400) “At least two sediments and their associated waters are used 

for both the aerobic and the anaerobic studies respectively... However, there may be cases where 

more than two aquatic sediments should be used, for example, for a chemical that may be present 

in freshwater and/or marine environments. Sediments should be representative of intended use 
 71

sites.” Since permethrin has a high potential for use near estuarine/ marine areas, one of the 

required sediment systems should be from estuarine/ marine environment. EFED is requiring 

two additional different sediment systems for permethrin, one of which should be of marine 

origin and the other of freshwater origin, in order to fulfill current OCSPP guideline 

requirements, to provide two additional half-lives in different aquatic sediments, resulting in 

more knowledge and certainty related to the behavior and persistence of permethrin in aerobic 

aquatic environments, and to address the above mentioned deficiencies found during the 

screening of the available study. For the metabolism studies, domestic sediments are preferred. 

835.4400 Anaerobic Aquatic Metabolism – A study is available in one soil/ sediment system 

which was considered acceptable. However, upon examination of the study, it was found that it 

was conducted at a concentration that greatly exceeded the solubility limit of permethrin (study 

conducted at 1 ppm, compared to a solubility of 0.0055 ppm). This could promote the 

partitioning of the chemical with the sediment phase. Furthermore, the system was amended 

with D-(+)-glucose to promote anaerobicity; however, no redox potential and/ or oxygen content 

were measured during the study to confirm that the system was fully anaerobic. Due to the 

above mentioned problems, there is uncertainty regarding the behavior of permethrin in typical 

anaerobic aquatic environments. According to OCSPP Fate, Transport and Transformation Test 

Guidelines (835.4300 & 835.4400) “At least two sediments and their associated waters are used 

for both the aerobic and the anaerobic studies respectively... However, there may be cases where 

more than two aquatic sediments should be used, for example, for a chemical that may be present 

in freshwater and/or marine environments. Sediments should be representative of intended use 

sites.” At this time, EFED is requiring anaerobic aquatic metabolism studies conducted with two 

water/ sediment systems. Since permethrin has a high potential for use near estuarine/ marine 

areas, one of the required sediment systems should be from estuarine/ marine origin, and the 

other of freshwater areas, in order to fulfill current OCSPP guideline requirements, to provide 

confirmatory data and two additional half-lives in different aquatic sediments, resulting in more 

knowledge and certainty regarding the behavior and persistence of permethrin in anaerobic 

aquatic environments, and to address the above mentioned deficiencies found during the 

screening of the available study. For all the metabolism studies, domestic sediments are 

preferred. 

835.1230 Mobility – Adsorption/ Desorption Batch Equilibrium – One available study, which 

was originally considered acceptable, was performed at concentrations ranging from 0.05 to 0.55 

ppm, compared to a solubility limit of permethrin in water of 0.0055 (up to 100 times the 

solubility limit of permethrin). Furthermore, a cosolvent concentration of 5% (acetonitrile) was 

used, compared to a recommended ≤0.1% (up to 50 times the maximum recommended cosolvent 

concentration). Even though Freundlich correlations were good (r2 ≥ 0.966), the 1/n values 

varied from 1.09 to 1.32, with only one of the values within the recommended range of 0.9-1.1. 

Furthermore, extensive degradation occurred, particularly for the aquatic sediment. In another 

supplemental study, the adsorption constants (Kd and KOC) were much higher than for the 

previously mentioned study. For the later study, three of the soils had the same texture (sandy 

loam), the soils were sterilized using gamma irradiation, and the test was performed at above the 

solubility limit (the highest test concentration was 0.2 ppm, or ~36 times permethrin’s solubility 

limit), which may promote adsorption. However, it was noted that the cosolvent concentration 

used was lower at 0.25% acetonitrile (recommended ≤0.1%). EFED has reevaluated the 
 72

acceptable study, and due to the above mentioned problems, has downgraded it to supplemental. 

There is a high degree of uncertainty with respect to the magnitude of the Kd and KOC values for 

this chemical due to the observed differences from one study to the other, and they are thus, not 

considered reliable. EFED believes that a new study will greatly improve the understanding of 

the mobility of permethrin, and provide suitable information about the level of partitioning of 

permethrin in soil and water. Therefore, a new study addressing all these deficiencies is 

required. 

835.6100 & 835.6200 Environmental Chemistry Methods (ECMs), and Independent 

Laboratory Validations (ILVs), for Soil, Water and Sediment. ECMs associated with the 

Terrestrial Field Dissipation studies (Field dissipation §158.1300; OCSPP guidelines 835.6100 & 

835.6200), along with successful confirmatory method trials (validation) by an independent 

laboratory (i.e. ILVs), are required. If there is risk concern for a given taxon, ECMs should be 

available for the environmental media in which organisms of the taxon reside. These ECMs 

should have limits of quantitation for the residues of concern that are lower than the relevant 

toxicological levels of concern. Previous reviews on permethrin indicate that there is high 

concern for acute and chronic toxicity to aquatic animals, including those living in the benthos. 

Certain scenarios triggered acute and chronic levels of concern for freshwater and/ or estuarine/ 

marine aquatic invertebrates and/ or for fish and/ or organisms living in the benthos. Therefore, 

ECMs for water and sediment are required in addition to the ECM for soil. The ECMs should 

include parent and those residues found in the laboratory studies that exceeded 10% of the 

applied. Based on the available data at this time, the following appear to be the residues of 

concern for each media, but this could change, based upon the results of newly submitted 

environmental fate studies: 

Soil – parent, m-PBA and trans-DCVA 

Water and Sediment – parent, m-PBA, m-PBalc, cis-DCVA and trans-DCVA 

The registrant is encouraged to submit state-of-the-art environmental chemistry methods; further, 

multi-residue methods (MRMs) for soil, water and sediment are preferred, if applicable. There is 

no method for permethrin published in the Agency’s ECM website.26 One ECM/ILV 

combination has been submitted to the Agency, which is currently in review (MRID# 47053001 

and 47053002). The Agency will verify the suitability of this method and the appropriateness of 

its levels of quantitation. At this time, no specific methods have been identified for the analysis 

of m-PBA, cis- or trans-DCVA. A full description of the method validation procedures 

performed by an independent laboratory should also be submitted. It should include the 

following information (Corbin et al. 2006): (a) Recovery level(s) of the test compound(s) from 

the soil, water and sediment (substrates) at various relevant fortification level(s) using the residue 

analytical methodology; (b) a validated method sensitivity level; (c) results of the study and 

statistical test applied, including a stepwise presentation of the procedure for calculating percent 

recovery from the raw data; (d) all the data/ information necessary to independently verify the 

results; (e) summary of the results; and, (f) discussion and conclusions of the results. 

Non-Guideline Studies: 

Leachability from Treated Wood – A study is required for permethrin. It should be conducted 

 

26 Available at url: http://www.epa.gov/oppbead1/methods/ecmindex.htm
 73

using TEP and applied to the wood as indicated in the label, following the American Wood 

Preservers Association Standard Method of Determining the Leachability of Wood Preservatives 

(E11, edition 06 or E1106). The registrant should provide a protocol to be evaluated by the 

Agency prior to performing the study. 

POTW Treatability Study – The Agency has recently requested and provided comments on a 

protocol developed by the Pyrethroid Working Group (PWG) for a bench scale study of waste 

water treatment, to assess the percentage removed in the biosolids by the treatment, the amount 

that would degrade during treatment, and the amount that would remain in the waste water. 

These data would be used to inform removal percentages by waste water treatment, which is an 

input to the Exposure and Fate Assessment Screening Tool’s (E-FAST) down-the-drain module. 

The Office of Pesticide Programs will continue to confer with the Office of Water with the goal 

of refining our down-the-drain assessment for registration review. It is the responsibility of the 

registrant to ensure that permethrin is included in the study completed by the PWG or conduct a 

similar study on its own (following submission of a protocol for review). 

The Agency received comments from stakeholders with concerns regarding the value of a 

POTW Treatability Study and its representativeness of numerous treatment plant designs. EFED 

recognizes that such differences in plant design and operation may affect removal efficiencies, 

which is why it is proposing to require a POTW treatability study for permethrin, to support its 

EFAST2 down-the-drain modeling. EFED is currently working with the registrant on the design 

of this study to best meet the Agency’s environmental risk assessment needs. Part of the design 

of this study will need to address factors that the commenters present (i.e., the effect of 

differences in POTW design and operation on removal efficiencies) to the extent practicable. 

This may involve differences in experimental conditions and/ or the use of POTW simulation 

models to address these concerns. The ability to extrapolate the bench scale results to results 

from available POTW monitoring data will also be evaluated. The forthcoming environmental 

risk assessment would address the uncertainty involved in the interpretation and extrapolation of 

results from the POTW treatability study to the national scale. 

The Agency is actively evaluating the extent to which ecological risk from permethrin via land 

application of biosolids should be addressed in its forthcoming environmental fate and ecological 

risk assessment and by extension, any additional data that may be required. As part of this 

evaluation, OPP is working closely with the Office of Water which regulates land application of 

biosolids under the Clean Water Act. 

EFED is unaware of any studies that suggest inhibition of POTW treatment processes is a 

significant risk due to documented pyrethroid exposures, including permethrin. Furthermore, 

EFED considers effects on POTW treatment processes to be beyond the scope of its 

environmental risk assessments. 

Table 7.1 lists the status of the environmental fate data requirements for permethrin. 

Table 7.1. Summary of Environmental Fate Data Requirements for Permethrin 
 74

Study Identification 

Use 

Pattern1

Does EPA Have 

Data To Satisfy 

This Requirement? Bibliographic Citation 

Must Additional 

Data Be Submitted 

Under FIFRA 

3(c)(2)(B)? 

§158.1300 ENVIRONMENTAL FATE

Degradation Studies-Lab:

835.2120 Hydrolysis 1,2,3 Yes 00102043 No 

835.2240 Photodegradation in 

Water 

1,2,3 Partially 40242801 Yes2

835.2410 Photodegradation on 

Soil 

1,2,3 Yes 40190101 No 

835.2370 Photodegradation in 

Air 

1,2,3 No Not Available No3

Metabolism Studies-Lab:

835.4100 Aerobic Soil 1,2,3 Partially 42410002 Yes4

835.4200 Anaerobic Soil 1,2,3 Partially 41970601 Yes5 

835.4300 Aerobic Aquatic 1,2,3 Partially 43938201 Yes6

835.4400 Anaerobic Aquatic 1,2,3 Partially 43982001 Yes7 

Mobility Studies:

835.1230 Leaching – 

Adsorption/ Desorption 

1,2,3 Partially 41868001, 45170102, 

43424901 

Yes8 

835.1410 Volatility (Lab) 1,2,3 No Not Available No3

835.8100 Volatility (Field) 1,2,3 No Not Available No3

Dissipation Studies-Field:

835.6100 Terrestrial Field 

Dissipation 

1,2,3 Yes 42359109 No

835.6200 Aquatic Field 

Dissipation 

1,2,3 Yes 44030501 No 

835.6300 Forestry Dissipation 1,2,3 No Not Applicable Not Applicable 

835.6100 & 835.6200 

Environmental Chemistry 

Methods (ECMs) and 

Independent Laboratory 

Validations (ILVs) 

1,2,3 Partially 47053001, 47053002 Yes10

Ground Water Monitoring Studies:

835.7100 Ground Water 

Monitoring 

1,2,3 No Not Available No 
 75

Table 7.1. Summary of Environmental Fate Data Requirements for Permethrin 

Study Identification 

Use 

Pattern1

Does EPA Have 

Data To Satisfy 

This Requirement? Bibliographic Citation 

Must Additional 

Data Be Submitted 

Under FIFRA 

3(c)(2)(B)? 

§158.1100 SPRAY DRIFT

201-1 Droplet Size Spectrum 1,2,3 Yes 40954101, 43173801 No9 

202-1 Drift Field Evaluation 1,2,3 Yes 43173801 No9

Other Studies: 

Leachability from Treated 

Wood 

1,2,3 No Not Available Yes11 

POTW Treatability Study Indoor Uses No Not Available Yes12 

1. Use Patterns: 1=Terrestrial/Food; 2=Terrestrial/Feed; 3=Aquatic/Food or Non-Food. 

2. The solubility of permethrin in water is 0.0055 ppm and the study was conducted at a concentration of 0.05-0.06 ppm; 

furthermore, up to 91% of AR was in the walls of the test vials during the study. The registrant should conduct a new 

confirmatory study addressing these issues. 

3. Data requirement was waived based on the low vapor pressure and Henry’s Law Constant for permethrin. 

4. The registrant conducted studies with only one soil system. According to current OCSPP guidelines, four soils are 

required. 

5. The available study only lasted 60 days anaerobic incubation, at which time, 65-72% AR remained as undegraded parent 

permethrin. Furthermore, it was conducted using only one soil, while the current OCSPP guideline requires four soils. A 

new study should be conducted. 

6. In the available study, the treatment rate was 1 ppm, which greatly exceeds the solubility limit of permethrin; the study 

lasted only 30 days, at which time ≥56% AR was undegraded permethrin (sum of cis and trans-isomers); and only one 

water/ sediment system (from Wilson, NC) was analyzed. The registrant should conduct a new study, using two water/ 

sediment systems, one of which should be of marine origin. 

7. Only one sediment system was evaluated while current guidelines require at least two. Furthermore, for the available 

study, various deficiencies were found: the study was conducted at a concentration that exceeded the solubility limit (1 ppm 

vs. solubility limit of 0.0055 ppm) and no redox potential or oxygen content measurements were performed to confirm that 

the system was fully anaerobic. A new study, performed with two water/sediment systems is required, one of which should 

be of marine origin. 

8. Two studies conducted with the parent compound had deficiencies (described above). A new study, addressing those 

deficiencies, is required. 

9. Data requirements covered by submission of the Spray Drift Task Force. 

10. The data requirement remains unfulfilled for permethrin, pending evaluation of available studies. 

11. It is preferred that the registrant provided a protocol to be evaluated by the Agency prior to performing the study. 

12. A protocol for this study was submitted by the Pyrethroid Working Group and comments have been provided by EFED. 

7.9.2 Ecological Effects 

For registration review, the following studies are being requested to fulfill any data gaps: 

Guideline Numbers: 850.2100 

Study Title: Avian acute oral toxicity test (passerine species) 

Acute avian oral toxicity data are required for either one waterfowl or one upland game species 
 76

and one passerine species under the 40 CFR Part 158 (CFR 40 2008) data requirements for 

conventional pesticides. In the latest Agency ecological risk assessment for permethrin, acute 

estimates of risk for birds were not generated for because the acute oral avian effects data show 

no treatment-related mortality to either mallard ducks (Anas platyrhynchos), Japanese quail 

(Coturnix coturnix) or ring-necked pheasants (Phasianus colchicus) at levels ranging from 

>2,000 to >42,706 mg a.i./kg-body weight (USEPA 2008a; MRIDs 00112938, 41888401, 

00042142, 00042121). Because passerine species have higher metabolic rates due to their 

smaller sizes than either waterfowl or upland game bird species and because they may utilize 

different metabolic pathways, they may be more or less sensitive to permethrin. In addition, an 

open literature study has documented the increased sensitivity of canaries (Serinus sp.) to another 

pyrethroid, beta-cyfluthrin (Addy-Orduna et al, 2011). 

One study examining the toxic effects of permethrin to a passerine species has been submitted to 

the Agency. A permethrin (PP 557, 92% w/v active ingredient) acute oral limit test was 

conducted on starlings (Sturnus vulgaris) (MRID 00042144). This study was classified as invalid 

due to lack of information in the study report, including documentation that regurgitation was 

examined after the initial dose and that food was withheld prior to dosing. In order to properly 

characterize risk to passerines, an avian oral toxicity test is required for passerine birds. A 

passerine study protocol must be submitted for review by the Agency prior to initiation of the 

study. 

Guideline Number: 850.1020 

Study Title: Acute Freshwater Invertebrate Toxicity (TEP) 

Because there are registered outdoor uses of permethrin that may result in significant exposure to 

water bodies, acute toxicity data of permethrin TEPs with the synergist PBO and MGK-264 is 

requested for freshwater invertebrates. Products with these synergists are likely to cause 

increased toxicity to nontarget aquatic species. Currently, no data is available to quantify the 

difference in toxicity for fish or invertebrates that may be concurrently exposed to permethrin 

and these synergists compared to the active ingredients alone. Therefore, the Agency is 

requesting acute toxicity studies of permethrin TEPs that are co-formulated w/ PBO and MGK264. Because available information indicates that greater toxicity enhancement can occur at 

higher synergist-to-a.i. ratios, selection of the TEPs for testing should include those TEPs with 

the highest synergist-to-a.i. 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 permethrin expected in the 

aquatic environment may be much greater than those used in the formulated products, due in part 
 77

to the different fate properties of the synergists and permethrin. As available data suggest greater 

toxicity enhancement can occur at higher synergist-to-a.i. ratios, it is possible that greater 

toxicity enhancement may occur in the natural environment compared to that measured for 

formulated products. Therefore, to address this concern, the Agency will attempt to bridge results 

from ongoing “comprehensive” synergist testing at varying synergist-to-a.i. ratios to address 

varying ratios of PBO/MGK-264 to permethrin 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 permethrin ecological risk assessment, the Agency 

may apply a “conservative” toxicity enhancement factor to address the uncertainty regarding 

differences in synergist-to-permethrin ratios in the aquatic environment vs. those tested using 

formulated products. The registrant may wish to submit additional data on permethrin/synergist 

toxicity at varying ratios that would be expected to occur in the aquatic environment to address 

this potential uncertainty. 

Guideline Number: 850.1075 

Study Title: Acute Freshwater Fish Toxicity (TEP) 

Because there are registered outdoor uses that may result in significant exposure to water bodies, 

acute toxicity data of permethrin TEPs with the synergist PBO and MGK-264 is requested for 

freshwater fish. Products with these synergists are likely to cause increased toxicity to nontarget 

aquatic species. Currently, no data is available to quantify the difference in toxicity for fish or 

invertebrates that may be concurrently exposed to permethrin and these synergists compared to 

the active ingredients alone. Therefore, the Agency is requesting acute toxicity studies of 

permethrin TEPs that are co-formulated w/ PBO and MGK-264. Because available information 

indicates that greater toxicity enhancement can occur at higher synergist-to-a.i. ratios, selection 

of the TEPs for testing should include those with the highest synergist-to-a.i. 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 permethrin 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 permethrin. As available data suggest greater 

toxicity enhancement can occur at higher synergist-to-a.i. ratios, it is possible that greater 

toxicity enhancement may occur in the natural environment compared to that measured for 

formulated products. Therefore, to address this concern, the Agency will attempt to bridge 

results from ongoing “comprehensive” synergist testing at varying synergist-to-a.i. ratios to 

address varying ratios of PBO/MGK-264 to permethrin 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 permethrin ecological risk 

assessment, the Agency may apply a “conservative” toxicity enhancement factor to address the 

uncertainty regarding differences in synergist-to-permethrin ratios in the aquatic environment vs. 

those tested using formulated products. The registrant may wish to submit additional data on 

permethrin/synergist toxicity at varying ratios that would be expected in the aquatic environment 

to address this potential uncertainty. 

Guideline Number: 850.1020 
 78

Study Title: Acute Freshwater Invertebrate Toxicity (Hyalella azteca)

Acute water column tests with Hyallela azteca have been requested in other pyrethroid problem 

formulations based on the increased sensitivity of this species to pyrethroid insecticides. In the 

most recent permethrin assessment that looked at effects to aquatic invertebrates (USEPA 

2008a), Hyallela azteca open literature data was used to calculate risk quotients for aquatic 

invertebrates (Anderson et al., 2005; ECOTOX Ref. #90039). This acute toxicity endpoint was 

more sensitive than registrant-submitted aquatic invertebrate tests with water-column exposure to 

Daphnia magna. However, upon additional review, this study with H. azteca is determined to 

supplemental (will not be used quantitatively) in the upcoming Agency ecological risk 

assessment for permethrin. This decision is based on concerns with test substance stability during 

the study and high solvent control mortality (the solvent used was at levels approximately 20 

times higher than Agency guideline recommendations for aquatic toxicity tests). An acute water 

column test examining the toxicity of permethrin to Hyalella azteca is required. 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 protocol prior to test 

initiation or submit any open literature studies that may fulfill this data gap. 

Guideline Numbers: 850.1025 

Study Title: Oyster acute toxicity test (shell deposition) 

No available studies examining the effects of permethrin on mollusks are acceptable for 

quantitative use in the upcoming risk assessment. Therefore, the Agency is requesting an acute 

toxicity test of permethrin in order to appropriately estimate acute toxicity to mollusks. 

Guideline Number: 850.1350 

Study Title: Aquatic Invertebrate Life-Cycle (saltwater) 

Previously submitted studies indicate that estuarine/marine invertebrates are among the most 

chronically sensitive taxa to permethrin, with acute effects expected below 1 μg a.i./L. While 

two estuarine/marine invertebrate chronic exposure studies with permethrin are available to the 

Agency, the toxicity endpoints derived from these studies are considered highly uncertain. 

Specifically, one life-cycle study with mysids (Americamysis bahia) reports NOAEC and 

LOAEC values of 0.011 and 0.024 μg a.i./L based on mortality, but poor reproductive 

performance of the controls hindered the evaluation of permethrin effects on reproduction 

(MRID 41315701). The other chronic permethrin study conducted with mysids was determined 

to be invalid because no raw data was reported to enable verification of results, stock solutions 

were accidentally switched and excessive deaths occurred due to mysids jumping from the test 

containers (MRID 40102001). 

Furthermore, the need for a life cycle chronic toxicity of permethrin to estuarine/marine 

invertebrates is indicated based on its aquatic toxicity and environmental fate properties per 40 

CFR Part 158 data requirements (October 26, 2007). Specifically: 

1. Permethrin is intended for use such that its presence in estuarine/marine 

environment in significant concentrations is expected; 

2. The acute LC/EC50 for permethrin is substantially lower than the 40 Part 158 

trigger value of 1 mg/L (0.019 μg/L for Americamysis bahia, MRID 40228401); 

and 

3. Previous risk assessments have indicated that the aquatic EECs are > 0.01 of the 

acute LC/EC50 values for permethrin, which is another condition for triggering an 
 79

estuarine/marine invertebrate life cycle study. In the 2008 listed species 

assessment for permethrin, acute RQs for estuarine/marine invertebrates range 

from 2.48 (soil barrier treatment on fencerows and hedgerows) to 305.56 (nursery 

uses and residential turf and ornamentals) for the 45 agricultural and nonagricultural scenarios assessed (USEPA 2008a). 

As substantial advances in both analytical and biological test methods have occurred over the 

past two decades (the previously submitted studies were conducted in 1986 and 1989), it is 

highly likely that a repeat of these studies would yield results that are much more scientifically 

defensible. Without this study, estimation of chronic risks to estuarine/marine invertebrates from 

permethrin exposure will involve substantial uncertainty. 

Guideline Numbers and Study Titles: 

 Test Method 100.4 (OCSPP 850.1770, in prep.); Whole sediment: chronic 

invertebrates freshwater (Hyalella azteca) 

 Test Method 100.5 (OCSPP 850.1760, in prep.); Whole sediment: chronic 

invertebrates freshwater (Chironomus dilutus) US EPA 2001, 

 EPA 600/R-01/020 (OCSPP 850.1780, in prep.); Whole sediment: chronic 

invertebrates marine (Leptocheirus plumulosus) 

No chronic sediment toxicity tests for freshwater or marine invertebrates have been submitted to 

satisfy the Agency’s updated data requirements for outdoor uses in 40 CFR Part 158 (October 

26, 2007). For permethrin, available information indicates that benthic organisms may be 

exposed via run-off or spray drift applications used in agricultural, forest, and residential 

settings. Based on calculations in the most recent EFED assessment for permethrin where 

estimated sediment concentrations were calculated, the peak sediment porewater EECs predicted 

for permethrin ranged from 0.00364 ppm for barrier treatment to 1.62 ppb for nursery-pine seed 

orchard-high rate (US EPA 2008a). The upper end of this range exceeds 0.1 of the most sensitive 

acute LC/EC50 (0.0212 μg a.i./L for the amphipod Hyallela azteca), which satisfies one of the 

criteria for requiring chronic whole sediment toxicity testing under 40 CFR Part 158. Chronic 

reproductive effects were also seen in other aquatic invertebrate taxa (daphnids and mysids), 

although at higher levels than acute effects were observed for amphipods. 

Permethrin has a long expected half-life in sediment, based on submitted soil metabolism and 

aquatic metabolism studies (aerobic soil, 37 days; anaerobic soil, 204 days; aerobic aquatic 

metabolism, 38.2-42.9 days; anaerobic aquatic metabolism, 113-175 days) (MRIDs 42410002, 

41970601, 43938201 and 43982001). These half-life values are substantially greater than 40 

CFR Part 158 criterion of 10 days. The potential for persistent exposure from permethrin in 

sediment is also indicated by open literature studies on pyrethroids (Weston et al., 2004; Holmes 

et al., 2008; Weston and Lydy, 2010; Lao et al., 2010; Ding et al., 2009). 

The third set of trigger criteria for requiring chronic testing (Kd > 50 or log KOW >3 or KOC > 

1000) is also met for permethrin (Kd ranges from 140-401, log KOW is 6.1, and KOC values range 

from 19,300 to 60,900). The physicochemical property triggers (Kd, KOW and KOC) reflect the 

propensity of the chemical to partition onto the particulate or organic matter phases of sediments. 

Exceeding any one of the physicochemical property triggers listed above is sufficient for 

indicating the pesticide has reasonable potential for partitioning to the sediment compartment. 
 80

For sediment studies involving pyrethroids, chronic whole sediment tests on Hyalella azteca, 

Chironomus tentans, and Leptocheirus plumulosus are requested. Although both are freshwater 

species, Hyalella and Chironomus differ substantially in their ecological niche (i.e., epibenthic v. 

infaunal species), physiology. Evidence in open literature suggests that Hyalella azteca is among 

the most sensitive aquatic invertebrates to permethrin based on acute water column tests (Weston 

and Lydy, 2010; Brander et al., 2009). Permethrin has the potential to enter estuarine/marine 

water bodies based on current usuage patterns that include coastal areas. Therefore, testing is 

also required for an estuarine/marine sediment-dwelling invertebrate species. 

Until the final OCSPP guidelines for chronic sediment toxicity tests are published, the registrant 

should submit a protocol to EFED for approval prior to test initiation. 

 Test Method 100.4: Hyalella azteca 42-d Test for Measuring the Effects of Sediment 

Associated Contaminants on Survival, Growth, and Reproduction in USEPA 2000 

Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated 

Contaminants with Freshwater Invertebrates EPA 600/R-99/064 (OCSPP 850.1770, in 

prep.); 

 Test Method 100.5: Life-cycle Test for Measuring the Effects of Sediment-associated 

Contaminants on Chironomus dilutus (formerly known as C. tentans) in USEPA 2000 

Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated 

Contaminants with Freshwater Invertebrates EPA 600/R-99/064 (OCSPP 850.1760, in 

prep.); and 

 Leptocheirus plumulosus in USEPA 2001 Method for Assessing the Chronic Toxicity of 

Marine and Estuarine Sediment-associated Contaminants with the Amphipod 

Leptocheirus plumulosus EPA 600/R-01/020 (OCSPP 850.1780, in prep.). 

Guideline Numbers: 850.4150 and 850.4250 

Study Title: Vegetative vigor and Seedling emergence, Tier II 

No acceptable toxicity data are currently available to assess the risk of permethrin to non-target 

terrestrial plants. Since permethrin has many outdoor uses, vegetative vigor and seedling 

emergence studies are required. In addition, registrants have reported three major terrestrial plant 

incidents involving permethrin alone or permethrin with piperonyl butoxide, a commonly used 

pyrethroid synergist. A total of 149 reported minor plant incidents are attributed to permethrin 

use. Phytotoxicity data are needed to assess the impact of pesticides on endangered and 

threatened non-target terrestrial plants. 

Guideline Numbers: 850.4400 and 850.5400 

Study Title: Aquatic Plant Growth (algal and aquatic vascular plant toxicity), Tier II 

No acceptable toxicity data are currently available to assess the risk of permethrin to non-target 

aquatic nonvascular and vascular plants. Since permethrin has many outdoor uses, algal and 

aquatic vascular plant toxicity studies are requested with either permethrin technical or a typical 

end-use product. 
 81

Table 7.2 lists the status of the ecological effects data requirements for permethrin. 

Table 7.2. Ecological Effects Data Requirements for Permethrin. 

Data Requirement 

Does EPA Have 

Data To Satisfy 

This 

Requirement? 

(Yes, No, or 

Partially) 

Bibliographic 

Citation (MRID) 

Must Additional 

Data Be Submitted 

Under FIFRA 3(c)(2)(B)? 

§158.630 TERRESTRIAL ORGANISM TESTING

850.2100 Acute Avian Oral, 

Quail/Duck/Passerine 

Partially 00112938, 41888401, 

00042142, 00042144 

Yes1 

850.2200 Acute Avian Diet, Quail Yes 41888402, 00072845 No

850.2200 Acute Avian Diet, Duck Yes 00112939, 41888403 No 

850.2400 Wild Mammal Toxicity N/A 

850.2300 Avian Reproduction Quail Yes 42322901, 00110671 No 

850.2300 Avian Reproduction Duck Yes 42322902, 00110670 No 

§158.630 AQUATIC ORGANISM TESTING

850.1075 Acute Fish Toxicity Bluegill Yes 00110663, 00110657, 

00097445 

No 

850.1075 Acute Fish Toxicity Rainbow 

Trout 

Yes 00110657 No 

850.1075 Acute Fish Toxicity (TEP) Partially 00110705, 42584004 Yes 2 

850.1010 Acute Aquatic Invertebrate Yes 0043736, 00110662, 

00043736, 00110663 

No 

850.1010 Acute Aquatic Invertebrate 

(TEP) 

Partially 00110662, 43740602, 

42584002 

Yes 2

850.1075 Acute Est/Mar Toxicity Fish Yes 41874901 No 

850.1025 Acute Est/Mar Toxicity 

Mollusk 

No N/A Yes 

850.1035 Acute Est/Mar Toxicity Shrimp Yes 43492902 No 

850.1075 Acute Est/Mar Toxicity Fish 

(TEP) 

No N/A No 

850.1025 Acute Est/Mar Toxicity Mollusk 

(TEP) 

No N/A No 

850.1035 Acute Est/Mar Toxicity Shrimp 

(TEP) 

No N/A No 

850.1400 Early Life Stage Fish Yes N/A No 
 82

Table 7.2. Ecological Effects Data Requirements for Permethrin. 

Data Requirement 

Does EPA Have 

Data To Satisfy 

This 

Requirement? 

(Yes, No, or 

Partially) 

Bibliographic 

Citation (MRID) 

Must Additional 

Data Be Submitted 

Under FIFRA 3(c)(2)(B)? 

850.1300 Life Cycle Aquatic Invertebrate 

(freshwater) 

Yes 43745701 No 

850.1350 Life Cycle Aquatic Invertebrate 

(saltwater) 

No N/A Yes 

850.1500 Life Cycle Freshwater Fish Yes Accession #263993 No 

850.1730 Bioaccumulation in Fish Yes 41300401, 41300402, 

41300403 No 

Test Method 100.4 (OCSPP 850.1770, in 

prep.); Whole sediment: chronic 

invertebrates freshwater (Hyalella azteca) 

No N/A Yes3

Test Method 100.5 (OCSPP 850.1760, in 

prep.); Whole sediment: chronic 

invertebrates freshwater (Chironomus 

dilutus) 

No N/A Yes3

US EPA 2001, EPA 600/R-01/020 (OCSPP 

850.1780, in prep.); Whole sediment: 

chronic invertebrates marine 

(Leptocheirus plumulosus) 

No N/A Yes3

850.1020 Aquatic Invertebrate Acute 

Toxicity (Hyalella) 

No NA Yes4

§158.660 PLANT PROTECTION TESTING

850.4100 Seedling Emergence (Tier II) No NA Yes5 

850.4150 Vegetative Vigor (Tier II) No NA Yes5 

850.4400 Aquatic Plant Toxicity using 

Lemna spp. (Tier II) 

No NA Yes5

850.5400 Algal Toxicity (Tier II) No NA Yes5

§158.490 INSECT POLLINATOR TESTING

850.3020 Honey Bee Acute Contact Yes 42674501 No 

850.3030 Honey Bee Residue on Foliage Yes 42009301 No 

850.3040 Field Test for Pollinators No NA In Reserve6 

 
 83

NA = Not applicable because no citation is available. 

1

 One study examining the toxic effects of permethrin to a passerine species has been submitted to the Agency. A 

permethrin (PP 557, 92% w/v active ingredient) acute oral limit test was conducted on starlings (Sturnus vulgaris) (MRID 

00042144). This study was classified as invalid due to lack of information in the study report, including documentation that 

regurgitation was examined after the initial dose and that food was withheld prior to dosing. An acute oral test examining 

the toxicity of permethrin to passerine species is required. A passerine study protocol must be submitted for review by the 

Agency prior to initiation of the study. 

2

 TEP studies on freshwater invertebrates and freshwater fish are required on a product containing permethrin and the 

synergist piperonyl butoxide in addition to a product containing permethrin and the synergist MGK-264. Permethrin may be 

co-formulated with either or both synergists, PBO and MGK-264, in numerous products. Because available information 

indicates that greater toxicity enhancement can occur at higher synergist-to-a.i. ratios, selection of the TEPs for testing 

should include those with the highest synergist-to-a.i. ratio and are registered for outdoor uses. The preferred freshwater 

invertebrate test species is the amphipod, Hyalella azteca (using 850.1020 guideline for Gammarid amphipods with 

apporiate modifications). Freshwater fish tesing should follow the 850.1075 test guideline. The registrant should submit a 

test protocol prior to conducting these TEP studies that documents the rationale for the TEP selection.3

 Test Method 100.4: 

Hyalella azteca 42-d Test for Measuring the Effects of Sediment-associated Contaminants on Survival, Growth, and 

Reproduction in USEPA 2000 Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated 

Contaminants with Freshwater Invertebrates EPA 600/R-99/064. 

Test Method 100.5: Life-cycle Test for Measuring the Effects of Sediment-associated Contaminants on Chironomus dilutus 

(formerly known as C. tentans) in USEPA 2000 Methods for Measuring the Toxicity and Bioaccumulation of Sedimentassociated Contaminants with Freshwater Invertebrates, EPA 6001R-99/064.

USEPA 2001: Method for Assessing the Chronic Toxicity of Marine and Estuarine Sediment-associated Contaminants with 

the Amphipod Leptocheirus plumulosus, EPA 6001R-0l/020. 

Protocol must be submitted to the Agency for review and approval prior to study inception. 

4

 Acute water column tests with Hyallela azteca have been requested in other pyrethroid problem formulations based on the 

increased sensitivity of this species to pyrethroid insecticides. The registrant should submit a protocol prior to test initiation 

or submit any open literature data that may fulfill this data gap. 

5 A Tier II study is expected to be required. The upcoming DCI will provide that a Tier I plant study may be conducted in 

lieu of a Tier II study with the understanding that any adverse effects observed by the Tier I study would necessitate conduct 

and submission of a Tier II study as well. The purpose of a Tier II study is to establish both a definitive No Observed 

Adverse Effect Concentration (NOAEC), or alternatively, a concentration at which there is a 5% observed inhibition effect 

(IC05) to be used in a risk assessment and effects determination for endangered or threatened species (listed species), and a 

definitive IC25 (concentration at which there is a 25% observed inhibition effect) for assessing risk to non-listed nontarget 

plants. 

6. As discussed in Section 4.1, the Agency is holding the requirement for additional data on pollinator exposure and effects 

in reserve pending the outcome of the FIFRA SAP on Pollinator Risk Assessment (scheduled for spring 2012) and receipt of 

additional data concerning permethrin risks to pollinators during public review of this Preliminary Problem Forumulation 

document. 

 
 84

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2011, Article ID 803451: 10 pages. 

Amweg, E.L., D.P. Weston, C.S. Johnson, J. You and M.L. Lydy. 2006a. Effect of Piperonyl 

Butoxide on Permethrin Toxicity in the Amphipod Hyalella azteca. Environ. Tox. & Chem. 25 

(7): 1817-1825. 

Amweg, E.L. D.P. Weston, J. You and M.J. Lydy. 2006b. Pyrethroid Insecticides and Sediment 

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Amweg, E.L. and D.P. Weston. 2007. Whole-Sediment Toxicity Identification Evaluation Tools 

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Brassard, D., S. Haddad and D. Berwald. 2011. BEAD Chemical Profile for Registration 

Review: Permethrin (109701). Memorandum to K. Keller dated 05/11/2011. Office of 

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Brander, S.M., Werner, I., White, J.W. and L.A. Deanovic. 2009. Toxicity of a dissolved 

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Mathew, and I. Nicholson. 2006. NAFTA Guidance Document for Conducting Terrestrial Field 

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http://www.epa.gov/oppefed1/ecorisk_ders/terrestrial_field_dissipation.htm (accessed 01/26/11). 

Cox, R. and Wilson, W. 1984. Effects of Permethrin on the Behavior of Individually Tagged 

Honey Bees, Apis mellifera L. (Hymenoptera: Apidae). Environmental Entomology 13(2):375-

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Dai, P-L, Q Wang, J-H Sun, F Liu, X Wang, Y-Y Wu and T Zhou. 2010. Effects of sublethal 

concentrations of bifenthrin and deltamethrin on fecundity, growth, and development of the 

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 88

9. Fate and Ecotoxicity Bibliography 

Permethrin Environmental Fate Bibliography 

161-1 Hydrolysis 

MRID Citation Reference 

42146 Holmstead, R.L.; Casida, J.E.; Ruzo, L.O. (1976?) Photochemical Re- actions 

of Pyrethroid Insecticides. (Unpublished study received Aug 22, 1977 under 

10182-3; prepared by Univ. of California, Dept. of Entomological Sciences, 

Pesticide Chemistry and Toxicology Laboratory, submitted by ICI Americas, 

Inc., Wilmington, Del.; CDL:096330-A) 

65822 Allsup, T.L. (1976) Letter sent to Route List dated Apr 14, 1976: Hydrolysis of 

the FMC 33297 Insecticide: Analytical Report W-0103. (Unpublished study 

received Dec 29, 1980 under 10182-EX-19; prepared by FMC Corp., submitted 

by ICI Americas, Inc., Wilmington, Del.; CDL: 244018-E) 

97453 Rickett, F.E.; Knight, P.J. (1976) Photostability of Permethrin Isomers: 

Document Code HCDF 76-1. (Unpublished study received Mar 17, 1982 under 

59-200; prepared by Wellcome Foundation Ltd., England, submitted by 

Burroughs Wellcome Co., Research Triangle Park, N.C.; CDL:247048-A) 

102043 Allsup, T.; Russell, K.; Fullmer, O. (1976) Hydrolysis of FMC 33297 

Insecticide: W-0103. (Unpublished study received Dec 1, 1976 under 7G1891; 

prepared by FMC, submitted by ICI United States, Inc., Wilmington, DE; 

CDL:096431-G) 

102045 Holmstead, R.; Casida, J.; Ruzo, L. (1976) Photochemical Reactions of 

Pyrethroid Insecticides. Taken from: 172nd ACS National Meeting of the 

American Chemical Society; Aug 30, 1976, San Francisco, CA. (S.l.: s.n.). 

(Abstract; PEST 32; also In unpublished submission received Dec 1, 1976 

under 7G1891; submitted by ICI United States, Inc., Wilmington, DE; CDL: 

096431-K) 

110613 Elliott, M.; Farnham, A.; Janes, N.; et al. (1973) NRDC 143: A More Stable 

Pyrethroid. Pages 721-728, In Proceedings, 7th British Insecticide and 

Fungicide Conference. ?S.l: s.n.|. (Also In unpublished submission received 

Dec 30, 1976 under unknown ad- min. no.; submitted by ICI Americas, Inc., 

Wilmington, DE; CDL: 095685-B) 

110627 Fujie, G.; Cardenas, B.; Torre, A.; et al. (1975) Hydrolysis of FMC 33297 

Insecticide (Phase I): W-0047. (Unpublished study received Jan 3, 1978 under 

279-3013; submitted by FMC Corp., Philadelphia, PA; CDL:096695-C) 

110628 Holmstead, R.; Casida, J.; Ruzo, L.; et al. (1977) Pyrethroid 

Photodecomposition: Permethrin. (Unpublished study received Jan 3, 1978 
 89

under 279-3013; prepared by Univ. of California-- Berkeley, Dept. of 

Entomological Sciences, Pesticide Chemistry and Toxicology Laboratory, 

submitted by FMC Corp., Philadelphia, PA; CDL:096695-F) 

110675 Brandau, E.; Goertler, M.; Robinson, R. (1975) Determination of Partition 

Coefficients for Carbofuran, FMC 33297, FMC 25213, certain Potential 

Metabolites and Two Benchmark Chemicals: Ana- lytical Report M-3779. 

(Unpublished study received Jan 3, 1978 under 279-3013; submitted by FMC 

Corp., Philadelphia, PA; CDL: 096697-N) 

112936 Alvarez, M.; Dziedzic, J.; Durbetaki, A.; et al. (1977) Hydrolysis of FMC 

33297: Report No. CGP-77-12. (Unpublished study re- ceived Jan 3, 1978 

under 279-3013; submitted by FMC Corp., Philadelphia, PA; CDL:096695-E) 

45369732 Burri, R. (1995) Hydrolysis Determination of (Inert Ingredients) at pH 5, 7, and 

9: Lab Project Number: 340290: M9419. Unpublished study prepared by RCC 

Umweltchemie AG. 67 p. 

92142047 Leung, L. (1990) ICI Americas Inc. Phase 3 Summary of MRID 00102043 and 

Related MRIDs 00112936. Pounce Insecticide Permethrin (FMC 33297)- 

Hydrolysis Study. Prepared by FMC CORP. 10 p. 

161-2 Photodegradation-water 

MRID Citation Reference 

149595 Gronberg, R. (1984) Photodecomposition of [Phenyl-UL-[Carbon 14]] 

Baythroid in Aqueous Solution by Sunlight: Mobay Report 88598. 

Unpublished study prepared by Mobay Chemical Corp. 13 p. 

40242801 Amos, R.; Donelan, R. (1987) Permethrin: Photolysis in Sterile Water at pH5: 

Laboratory Project ID RJ0577B. Unpublished study prepared by ICI Plant 

Protection Div, Jealott's Hill Research Station. 66 p. 

42394706 Tanaka, F. (1992) Aqueous Photolysis of ?carbon-14| Vinclozolin at pH 5: Lab 

Project Number: 91153: M9205: 92-5098. Unpublished study prepared by 

BASF Corp. 56 p. 

45369737 Burri, R. (1995) Photodegradation Study (Inert Ingredient) in Water at pH 5: 

Lab Project Number: 340312: M9420. Unpublished study prepared by RCC 

Umweltchemie AG. 59 p. 

92142048 Leahey, J. (1990) ICI Americas Inc. Phase 3 Summary of MRID 40242801. 

Permethrin: Photolysis in Sterile Water at ph5: Report No. RJ0577B; Study 

No. PP557AG02. Prepared by ICI AGROCHEMICALS JEALOTT'S HILL 

RES. STATION. 14 p. 

161-3 Photodegradation-soil 
 90

MRID Citation Reference 

42146 Holmstead, R.L.; Casida, J.E.; Ruzo, L.O. (1976?) Photochemical Re- actions 

of Pyrethroid Insecticides. (Unpublished study received Aug 22, 1977 under 

10182-3; prepared by Univ. of California, Dept. of Entomological Sciences, 

Pesticide Chemistry and Toxi- cology Laboratory, submitted by ICI Americas, 

Inc., Wilmington, Del.; CDL:096330-A) 

60035 Elliott, M.; Farnham, A.W.; Janes, N.F.; et al. (1973) NRDC 145: A more 

stable pyrethroid. Proceedings of the 7th British Insecticide Conference :721-

728. (Also~In~unpublished submission received Feb 3, 1977 under 10182-EX8; submitted by ICI Ameri- cas, Inc., Wilmington, Del.; CDL:228194-B) 

65820 Hill, I.R.; Harvey, B.R.; Weissler, M.S. (1977) Permethrin: Degradation in 

River Sediments, River Water and in Flooded Soils: RJ0008 A. (Unpublished 

study received Dec 29, 1980 under 10182- EX-19; prepared by Imperial 

Chemical Industries, Ltd., England, submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL:244018-C) 

66649 Elliott, M.; Farnham, A.W.; Janes, N.F.; et al. (1973) NRDC 143: A more 

stable pyrethroid. Pages 721-728,~In Proceedings, 7th British Insecticide and 

Fungicide Conference. N.P. (Also~In~ unpublished submission received Feb 3, 

1977 under 10182-EX-7; submitted by ICI Americas, Inc., Wilmington, Del.; 

CDL:228608-B) 

89996 Arnold, D.J.; Hill, I.R. (1977) Permethrin: Extraction and Identi- fication of the 

Bound Residues of the Pesticide in Soil: Report Series TMJ 1513B; 5B 1/5. 

(Unpublished study received Dec 30, 1981 under 10182-64; prepared by 

Imperial Chemical Industries, Ltd., England, submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL:070559-G) 

110628 Holmstead, R.; Casida, J.; Ruzo, L.; et al. (1977) Pyrethroid 

Photodecomposition: Permethrin. (Unpublished study received Jan 3, 1978 

under 279-3013; prepared by Univ. of California-- Berkeley, Dept. of 

Entomological Sciences, Pesticide Chemistry and Toxicology Laboratory, 

submitted by FMC Corp., Philadelphia, PA; CDL:096695-F) 

110630 Kaufman, D.; Jordan, E.; Kayser, A.; et al. (1977) The Effect of Soil 

Temperature on the Degradation of 14C-Carbonyl-cis, trans- Permethrin in 

Soil: Report No. 8. (Unpublished study received Jan 3, 1978 under 279-3013; 

prepared by U.S. Agricultural Re- search Service, Agricultural Environmental 

Quality Institute and Univ. of Maryland, Dept. of Botany, submitted by FMC 

Corp., Philadelphia, PA; CDL:096695-J) 

110631 Arnold, D.; Cleverley, B.; Hill, I. (1976) Permethrin: Laboratory Studies of the 

Degradation of the Pesticide in Soil: Report Series TMJ 1287 B. (Unpublished 

study received Jan 3, 1978 under 279-3013; submitted by FMC Corp., 

Philadelphia, PA; CDL: 096695-K) 
 91

110632 Arnold, D.; Hill, I. (1977) Permethrin: Extraction and Identifi- cation of the 

Bound Residues of the Pesticide in Soil: Report Series 1513B. (Unpublished 

study received Feb 14, 1978 under 279-3013; submitted by FMC Corp., 

Philadelphia, PA; CDL: 096695-M) 

110633 Kaufman, D.; Jordan, E.; Kayser, A.; et al. (1977) Degradation of 14CCarbonyl Cis- and Trans-, and 14C-Methylene cis-Permethrin in Flooded Soil: 

Report No. 9. (Unpublished study received Jan 3, 1978 under 279-3013; 

prepared by U.S. Agricultural Research Service, Agricultural Environmental 

Quality Institute and Univ. of Maryland, Dept. of Botany, submitted by FMC 

Corp., Phila- delphia, PA; CDL:096695-N) 

110637 Elliot, M.; Faanram, A.; Janer, N.; et al. (1973) A photostable pyrethroid. 

Nature 248(Nov):169-170. (Also In unpublished submission received on 

unknown date under 279-EX-60; submitted by FMC Corp., Philadelphia, PA; 

CDL:226420-L) 

110676 Cleverly, B.; Hill, I. (1977) Permethrin: The Degradation of the Pesticide in 

Flooded Soils Incubated under Laboratory Condi- tions: Report Series TMJ 

1527B. (Unpublished study received Jan 3, 1978 under 279-3013; prepared by 

Imperial Chemical Indus- tries, Ltd., Eng., submitted by FMC Corp., 

Philadelphia, PA; CDL:096696-A) 

40190101 Brown, P.; Leahey, J. (1987) Permethrin: Photolysis on a Soil Sur- face: 

Laboratory Project ID: RJ0581B. Unpublished study pre- pared by ICI Plant 

Protection Division. 53 p. 

40201601 Brown, P.; Leahey, J. (1987) Supplement to MRID #40190101 (Missing Page): 

Permethrin: Photolysis on a Soil Surface: Laboratory Project ID: RJ0581B. 

Unpublished study prepared by ICI Plant Protection Division. 3 p. 

45369734 Burri, R. (1996) Photodegradation Study of (Inert Ingredient) on Soil: Lab 

Project Number: 370247: M9425. Unpublished study prepared by RCC 

Umweltchemie AG. 81 p. 

92142049 Leahey, J. (1990) ICI Americas Inc. Phase 3 Summary of MRID 40190101 and 

Related MRIDs 00073990, 40201601. Permethrin: Photolysis on a Soil Surface 

and a Comparison of the Microflora and Physicochemical Properties of Soils 

Used in UK Laboratory Studies with Those of USA Soils: Report No. RJ0581B 

and RJ0429B; Study PP557AG01 and PP000CK10. Prepared by ICI 

AGROCHEMICAL. 15 p. 

162-1 Aerobic soil metabolism 

MRID Citation Reference 

45538 Arnold, D.J.; Cleverley, B.A.; Hill, I.R. (1976) Permethrin: Labo- ratory 

Studies of the Degradation of the Pesticide in Soil: Report No. TMJ 1287 B. 

(Unpublished study received Aug 22, 1977 under 10182-EX-3; prepared by 
 92

Imperial Chemical Industries, Ltd., submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL: 096331-B) 

45539 Arnold, D.J.; Cleverly, B.A.; Hill, I.R. (1977) Permethrin: The Degradation of 

the Pesticide in Soil under Laboratory Conditions, III: Report No. TMJ 1512 B. 

(Unpublished study received Aug 22, 1977 under 10182-EX-3; prepared by 

Imperial Chemical Industries, Ltd., submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL:096331-C) 

45540 Arnold, D.J.; Cleverly, B.A.; Hill, I.R. (1976) Permethrin: Degra- dation in Soil 

under Laboratory Conditions (II): Report No. TMJ 1427 B. (Unpublished study 

received Aug 22, 1977 under 10182- EX-3; prepared by Imperial Chemical 

Industries, Ltd., submitted by ICI Americas, Inc., Wilmington, Del.; 

CDL:096331-D) 

110631 Arnold, D.; Cleverley, B.; Hill, I. (1976) Permethrin: Laboratory Studies of the 

Degradation of the Pesticide in Soil: Report Series TMJ 1287 B. (Unpublished 

study received Jan 3, 1978 under 279-3013; submitted by FMC Corp., 

Philadelphia, PA; CDL: 096695-K) 

110632 Arnold, D.; Hill, I. (1977) Permethrin: Extraction and Identifi- cation of the 

Bound Residues of the Pesticide in Soil: Report Series 1513B. (Unpublished 

study received Feb 14, 1978 under 279-3013; submitted by FMC Corp., 

Philadelphia, PA; CDL: 096695-M) 

110633 Kaufman, D.; Jordan, E.; Kayser, A.; et al. (1977) Degradation of 14CCarbonyl Cis- and Trans-, and 14C-Methylene cis-Permethrin in Flooded Soil: 

Report No. 9. (Unpublished study received Jan 3, 1978 under 279-3013; 

prepared by U.S. Agricultural Research Service, Agricultural Environmental 

Quality Institute and Univ. of Maryland, Dept. of Botany, submitted by FMC 

Corp., Phila- delphia, PA; CDL:096695-N) 

110636 Kaufman, D.; Jordan, E. (1976) Preliminary Soil Metabolism Investi- gations 

with FMC-33297: Report No. 2. (Unpublished study re- ceived on unknown 

date under 279-EX-60; prepared by U.S. Dept. of Agriculture, Agricultural 

Environmental Quality Institute, Pesticide Degradation Laboratory in 

cooperation with Univ. of Maryland, Botany Dept., submitted by FMC Corp., 

Philadelphia, PA; CDL:226420-C) 

110668 Kaufman, D.; Jordan, E.; Kayser, A.; et al. (1976) Permethrin Degradation in 

Soil and Microbial Cultures. (Unpublished study received Jan 3, 1978 under 

279-3013; prepared by U.S. Agricul- tural Research Service, Agricultural 

Environmental Quality In- stitute and Univ. of Maryland, Dept. of Botany, 

submitted by FMC Corp., Philadelphia, PA; CDL:096699-U) 

110676 Cleverly, B.; Hill, I. (1977) Permethrin: The Degradation of the Pesticide in 

Flooded Soils Incubated under Laboratory Condi- tions: Report Series TMJ 

1527B. (Unpublished study received Jan 3, 1978 under 279-3013; prepared by 

Imperial Chemical Indus- tries, Ltd., Eng., submitted by FMC Corp., 

Philadelphia, PA; CDL:096696-A) 
 93

110677 Kaufman, D.; Barnett, E.; Jordan, E.; et al. (1977) Microbial Deg- radation of 

Permethrin: Report No. 10. (Unpublished study re- ceived Jan 3, 1978 under 

279-3013; prepared by U.S. Agricultural Research Service, Agricultural 

Environmental Quality Institute and Univ. of Maryland, Dept. of Botany, 

submitted by FMC Corp., Philadelphia, PA; CDL:096696-B) 

149594 Lord, K.; McKinley, M.; Walker, N. (1982) Degradation of permethrin in soils. 

Environmental Pollution A(29):81-90. 

158880 Kaufman, D.; Jordan, E.; Kayser, A. (1977) Degradation of [Carbon 14]-

Carbonyl-cis- and trans-Permethrin in soil: Report No. 6. Unpublished study 

prepared by US Agricultural Research Service, Agricultural Environmental 

Quality Institute and Univ. of Mary- land, Dept. of Botany. 31 p. 

42004602 

41970602 

Hakins, B.; Kirkpatrick, D.; Shaw, D. (1991) The Effect of Applica- tion Rate 

and Soil Moisture Content on the Rate of Degradation of ?Carbon 14| 

Permethrin in Aerobic Sandy Loam Soil: Lab Pro- ject Number: HRC/ISN 

247/91296. Unpublished study prepared by Huntingdon Research Centre, Ltd. 

40 p. 

42410002 Hawkins, D.; Kirkpatrick, D.; Shaw, D.; et al. (1992) The Aerobic Soil 

Metabolism of ?carbon 14|-Permethrin: Lab Project Number: HRC/ISN 

251/911499. Unpublished study prepared by Huntingdon Research Centre, Ltd. 

92 p. 

45369735 Wyss-Benz, M.; Tschech, A. (1995) (Inert Ingredient): Degradation and 

Metabolism in One U.S. Soil Incubated Under Aerobic COnditions: Lab Project 

Number: 340334: M9421. Unpublished study prepared by RCC Umweltchemie 

AG. 81 p. 

45369736 Fluckiger, J. (1995) (Inert Ingredient): Degradation in Three Soils Incubated 

Under Aerobic Conditions: Lab Project Number: 340345: M9422. Unpublished 

study prepared by RCC Umweltchemie AG. 83 p. 

 

162-2 Anaerobic soil metabolism 

MRID Citation Reference 

149594 Lord, K.; McKinley, M.; Walker, N. (1982) Degradation of permethrin in soils. 

Environmental Pollution A(29):81-90. 

41970601 Hawkins, D.; Kirkpatrick, D.; Shaw, D.; et al. (1991) The Metaboli- sm of 14CPermethrin in Sandy Loam Soil Under Anaerobic Conditi- ons: Lab Project 

Number: HRC/ISN236/91107. Unpublished study prepared by Huntingdon 

Research Centre, Ltd. 75 p. 

41970602 Hawkins, D.; Kirkpatrick, D.; Shaw, D.; et al. (1991) The Effects of 

Application Rate and Soil Moisture Content on the Rate of Degradation of 

?14C|-Permethrin: Lab Project Number: HRC/ISN247/ 91296. Unpublished 
 94

study prepared by Huntingdon Research Centre Ltd. 40 p. 

42004601 Hakins, B.; Kirkpatrick, D.; Shaw, D. (1991) The Metabolism of ?Carbon 14| 

Permethrin in Sandy Loam Soil under Anaerobic Condi- tions: Lab Project 

Number: HRC/ISN 236/91107. Unpublished study prepared by Huntingdon 

Research Centre, Ltd. 75 p. 

162-3 Anaerobic aquatic metab. 

MRID Citation Reference 

43982001 Robinson, R. (1996) Anaerobic Aquatic Metabolism of (carbon 14)-Permethrin: 

Lab Project Number: XBL94091: RPT00252. Unpublished study prepared by 

Xenobiotic Labs, Inc. 225 p. 

162-4 Aerobic aquatic metab. 

MRID Citation Reference 

43938201 Robinson, R.; Ryan, J. (1996) Aerobic Aquatic Metabolism of (carbon 14)-

Permethrin: Lab Project Number: XBL94092: RPT00220. Unpublished study 

prepared by XenoBiotic Labs, Inc. 220 p. 

163-1 Leach/adsorp/desorption 

MRID Citation Reference 

42151 Clarke, G.E.; Morrod, R.S. (1977) PP 557: Adsorption of PP 557 and Its 

Hydrolysis Products, R 110074 and R 79406, by Soil: TMJ 1472B. 

(Unpublished study received Aug 22, 1977 under 10182-3; prepared by 

Imperial Chemical Industries, Ltd., submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL:096330-F) 

42152 Prashad, S.; Stevens, J.E.; Newby, S.E. (1977) Permethrin: Mobility of 

Permethrin and its Degradation Products in Soil: AR 2716B. (Unpublished 

study received Aug 22, 1977 under 10182-3; prepared by Imperial Chemical 

Industries, Ltd., submitted by ICI Ameri- cas, Inc., Wilmington, Del.; 

CDL:096330-G) 

45541 Arnold, D.J.; Hill, I.R. (1977) Permethrin: Extraction and Identification of the 

Bound Residues of the Pesticide in Soil: Report No. TMJ 1518B. (Unpublished 

study received Aug 22, 1977 under 10182-EX-3; prepared by Imperial 

Chemical Industries, Ltd., sub- mitted by ICI Americas, Inc., Wilmington, Del.; 

CDL:096331-E) 

58861 Kaufman, D.D.; Russell, B.A.; Helling, C.S.; et al. (1978) Movement of 

Decamethrin, Cypermethrin, Permethrin and Their Degradation Products in 

Soil. (Unpublished study received Nov 13, 1980 under 8340-EX-6; prepared by 

U.S. Dept. of Agriculture, Agri- cultural Environmental Quality Institute, 
 95

Pesticide Degradation Laboratory and Univ. of Maryland, Botany Dept., 

submitted by American Hoechst Corp., Somerville, N.J.; CDL:099744-H) 

90052 Prashad, S.; Stevens, J.E.; Newby, S.E. (1977) Permethrin: Mobility of 

Permethrin and Its Degradation Products in Soil: AR 2716B; 5B 1/3. 

(Unpublished study received Dec 30, 1981 under 10182-64; prepared by 

Imperial Chemical Industries Ltd., England, submit- ted by ICI Americas, Inc., 

Wilmington, Del.; CDL:070560-A) 

90054 Clarke, G.E.; Morrod, R.S. (1977) PP 557: Adsorption of PP 557 and Its 

Hydrolysis Products, R 110074 and R 79406, by Soil: Report Series TMJ 

1472B. (Unpublished study received Dec 30, 1981 un- der 10182-64; prepared 

by Imperial Chemical Industries, Ltd., England, submitted by ICI Americas, 

Inc., Wilmington, Del.; CDL: 070560-C) 

93684 Brandau, E.G.; Goertler, M.G.; Otsa, H.L.; et al. (1975) Carbofuran, FMC 

33297, FMC 25213 and Endosulfan Soil Adsorption/ Desorption Studies: M3785. (Unpublished study received Jan 8, 1982 under 279-2712; submitted by 

FMC Corp., Philadelphia, Pa.; CDL:246582-G) 

97454 Williams, I.H.; Brown; M.J. (1979) Persistence of permethrin and WL 43775 in 

soil. Journal of Agricultural and Food Chemistry 27(1):130-132. 

(Also~In~unpublished submission received Mar 17, 1982 under 59-200; 

submitted by Burroughs Wellcome Co., Re- search Triangle Park, N.C.; 

CDL:247048-B) 

99038 Kaufman, D.D.; Russell, B.A.; Helling, C.S.; et al. (1981) Movement of 

cypermethrin, decamethrin, permethrin, and their degradation products in soil. 

Journal of Agricultural and Food Chemistry 29 (2):239-245. 

(Also~In~unpublished submission received Dec 30, 1981 under 10182-64; 

submitted by ICI Americas, Inc., Wilming- ton, Del.; CDL:070559-S) 

102042 Brandau, E.; Goertler, M.; Robinson, R. (1975) Mobility of FMC 33297 in Soil: 

M-3703. (Unpublished study received Dec 1, 1976 under 7G1891; prepared by 

FMC, submitted by ICI United States, Inc., Wilmington, DE; CDL:096431-F) 

110681 Brandau, E.; Goertler, M.; Robinson, R. (1975) Mobility of FMC 33297 in Soil: 

M-3703. (Unpublished study received Jan 3, 1978 under 279-3013; submitted 

by FMC Corp., Philadelphia, PA; CDL: 096696-G) 

110682 Prashad, S.; Stevens, J.; Newby, S. (1977) Permethrin: Mobility of ... and Its 

Degradation Products in Soil: AR 2716B. (Unpub- lished study received Jan 3, 

1978 under 279-3013; prepared by Imperial Chemical Industries, Ltd., Eng., 

submitted by FMC Corp., Philadelphia, PA; CDL:096696-H) 

112937 Brandau, E.; Goertler, M.; Otsa, H.; et al. (1975) Carbofuran, FMC 33297, 

FMC 25213 and Endosulfan Soil Adsorption/Desorption Studies: Analytical 

Report M-3785. (Unpublished study received Jan 3, 1978 under 279-3013; 

submitted by FMC Corp., Philadel- phia, PA; CDL:096699-T) 
 96

129016 Kaneko, H.; Ohkawa, H.; Miyamoto, J. (1978) Degradation and move- ment of 

permethrin isomers in soil. J. Pesticide Sci. 3:43-51. (Also In unpublished 

submission received Jun 8, 1983 under 20954-EX-19; submitted by Zoecon 

Corp., Palo Alto, CA; CDL:250536-E) 

41868001 Davis, M. (1991) Sorption/Desorption of ?Carbon 14| Permethrin on Soils by 

the Batch Equilibrium Method: Lab Project Number: SC900 199: 

138E329OE1. Unpublished study prepared by Battelle Memori- al Institute. 98 

p. 

42196701 Cranor, W. (1991) Leaching Characteristics of Soil Incorporated Permethrin 

Following Aerobic Aging: Lab Project Number: 39227: 138E3190E1: PC0162. Unpublished study prepared by ABC Labs., Inc. 183 p. 

43424901 Gravelle, W. (1994) Adsorption/Desorption of (carbon 14)- mPBAcid and 

(carbon 14)-trans-DCVA on Four Soils: Lab Project Number: 138E2394E1: P2960. Unpublished study prepared by FMC Corp. 93 p. 

45170102 Hurt, A.; Hand, L. (2000) Permethrin: Adsorption and Desorption Properties in 

Four Soils: Lab Project Number: 00JH005: RJ2978B. Unpublished study 

prepared by Zeneca Agrochemicals. 60 p. 

45369733 Volkl, S.; Morgenroth, U. (1995) Adsorption/Desorption of (Inert Ingredients) 

on Four Soils: Lab Project Number: 340356: M9423. Unpublished study 

prepared by RCC Umweltchemie AG. 77 p. 

164-1 Terrestrial field dissipation 

MRID Citation Reference 

45546 Ussary, J.P. (1977) Dissipation of Permethrin in Soil, Champaign, Illinois: 

Report No. TMU0262/75B. (Unpublished study received Aug 22, 1977 under 

10182-EX-3; submitted by ICI Americas, Inc., Wilmington, Del.; 

CDL:096331-K) 

65809 Ussary, J.P. (1981) Permethrin Residues in Samples from a 1980 Ala- bama 

Runoff Study: Report Series TMUO540/B. (Unpublished study received Jan 

15, 1981 under 279-3014; prepared by ICI Americas, Inc., submitted by FMC 

Corp., Philadelphia, Pa.; CDL:244090-B) 

79260 ICI Americas, Incorporated (1981) ?Permethrin Residue--Soil and Cotton|. 

(Compilation; unpublished study received Jan 15, 1981 under 10182-18; 

CDL:245647-A) 

102040 Leppert, B.; Chow, J.; Grana, B.; et al. (1976) Determination of FMC 33297 

Insecticide Residues in Soil from Cotton Field Trials: W-0061. (Unpublished 

study received Dec 1, 1976 under 7G1891; prepared by FMC, submitted by 

ICI United States, Inc., Wil- mington, DE; CDL:096431-D) 
 97

102041 Leppert, B.; Chow, J.; Grana, B.; et al. (1976) Determination of Dissipation 

Rate of FMC 33297 Residues in Soil: W-0065. (Un- published study received 

Dec 1, 1976 under 7G1891; prepared by FMC, submitted by ICI United States, 

Inc., Wilmington, DE; CDL:096431-E) 

102101 Markle, J.; Allsup, T.; Fujie, G.; et al. (1976) Determination of FMC 33297 in 

Soil and Rotational Crop Samples: W-0144. (Un- published study received Jan 

27, 1978 under 10182-17; prepared by FMC, submitted by ICI Americas, Inc., 

Wilmington, DE; CDL: 096765-J) 

110664 Union Carbide Corp. (1977) The Application of Two Permethrin Formulations on a Cotton Field Adjacent to an Aquatic Ecosystem: ?Submitter| 

ACT 060.81. (Unpublished study received Jan 3, 1978 under 279-3013; 

submitted by FMC Corp., Philadelphia, PA; CDL: 096699-N) 

110665 U.S. Agricultural Research Service (1976) Synthetic Pyrethroid (FMC 33297) 

in Soil and in Surface Runoff from Cotton Plots, 1976. (Unpublished study; 

CDL:096699-P) 

110683 Leppert, B.; Chow, J.; Grana, B.; et al. (1976) Determination of Dissipation 

Rate of FMC 33297 Residues in Soil: W-0065. (Unpub- lished study received 

Jan 3, 1978 under 279-3013; submitted by FMC Corp., Philadelphia, PA; 

CDL:096696-K) 

110684 Markle, J.; Kalb, E.; Fullmer, O. (1977) Dissipation of FMC 33297 Residues 

in Soil: W-0182. (Unpublished study received Jan 3, 1978 under 279-3013; 

submitted by FMC Corp., Philadelphia, PA; CDL:096696-L) 

110685 Leppert, B.; Grana, B.; Russell, K.; et al. (1976) Dissipation of FMC 33297 

Residues in Soils following Multiple Applications: W-0116. (Unpublished 

study received Jan 3, 1978 under 279-3013; submitted by FMC Corp., 

Philadelphia, PA; CDL:096696-M) 

110702 ICI United States, Inc. (1976) Ambush Pyrethroid Insecticide: Residue 

Chemistry. (Unpublished study received Jan 17, 1977 under 10182-EX-6; 

CDL:230167-C) 

155291 Stearns, J. (1985) Dissipation of Cyperamide and m-Phenoxybenzalde- hyde 

Residues in Soil Treated with Ammo Insecticide: RAN-0149. Unpublished 

study prepared by FMC Corp. with review of previous- ly submitted soil 

studies appended. 39 p. 

155793 Chapman, R.; Harris, C. (1981) Persistence of four pyrethroid insecticides in a 

mineral and an organic soil. J. Environ. Sci. Health B16(5):605-615. 

42359101 Becker, J. (1992) Pounce 3.2 EC Insecticide--Terrestrial Field Dissipation: 

Lab Project Number: 138E4191R1. Unpublished study prepared by FMC 

Corp. 180 p. 

42394707 Eubanks, M. (1992) Ronilan Fungicide (BAS 352 12 F) Soil Dissipation in 

Orchard and Strawberry Use Patterns: Analysis through 360 Days: Lab Project 
 98

Number: EP9001: 92-5093: ER92026. Unpublished study prepared by Stewart 

Ag Research Services, Inc.; Morse Labs, Inc.; Horizon Labs, Inc. 856 p. 

164-2 Aquatic field dissipation 

MRID Citation Reference 

44030501 Hatfield, M. (1996) Aquatic Dissipation of Permethrin in California and North 

Carolina: Interim Final Report: Lab Project Number: AA940907: 94-0024: P2703M. Unpublished study prepared by EN-CAS Analytical Laboratories and 

American Agricultural Services, Inc. 2044 p. 

44157101 Hatfield, M. (1996) Addendum to Aquatic Dissipation of Permethrin in 

California and North Carolina: MRID 44030501: Final Report: Lab Project 

Number: AA940907: 94-0024. Unpublished study prepared by EN-CAS 

Analytical Labs. and American Agricultural Services, Inc. 266 p. 

65820 Hill, I.R.; Harvey, B.R.; Weissler, M.S. (1977) Permethrin: Degradation in 

River Sediments, River Water and in Flooded Soils: RJ0008 A. (Unpublished 

study received Dec 29, 1980 under 10182- EX-19; prepared by Imperial 

Chemical Industries, Ltd., England, submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL:244018-C) 

 164-3 Forest field dissipation 

MRID Citation Reference 

158536 Kingsbury, P. (1984) Environmental impact assessment of insecti- cides used 

in Canadian forests. P. 365-376 in Chemical and Bio- logical Controls in 

Forestry, ACS Symposium Series No. 238, edited by W. Garner and J. Harvey. 

American Chemical Society. 

165-0 Accumulation Studies -- General 

MRID Citation Reference 

32136 Kuc, W.J. (1980) Preliminary 14C-Permethrin Model Aquatic Ecosystem 

Study: UCES Project No. 11507-62. (Unpublished study received May 2, 1980 

under 279-3014; prepared by Union Carbide Corp., submitted by FMC Corp., 

Philadelphia, Pa.; CDL:242372-A) 

42169 Ells, S.J. (1977) Kinetics of Aged ^14IC-PP557 in a Model Aquatic 

Ecosystem. (Unpublished study received Aug 22, 1977 under 10182-3; 

prepared by EG&G, Bionomics, submitted by ICI Americas, Inc., Wilmington, 

Del.; CDL:096330-Y) 

65810 Vilkas, A.G.; Kuc, W.J. (1980) FMC Corporation (Carbon -14)-Permethrin 
 99

Model Aquatic Ecosystem Study: UCCES Study 11507-98. (Unpublished 

study received Jan 15, 1981 under 279-3014; prepared by Union Carbide 

Corp., submitted by FMC Corp., Philadelphia, Pa.; CDL:244090-C) 

102097 Fujie, G.; Markle, J.; Gana, B. (1977) Determination of FMC 33297 Residues 

in Pond Study Samples from a FMC 33297 Cotton Environmental Impact 

Study: W-0204. (Unpublished study received Jan 27, 1978 under 10182-17; 

submitted by ICI Americas, Inc., Wil- mington, DE; CDL:096765-B) 

165-4 Bioaccumulation in fish 

MRID Citation Reference 

41300401 Burgess, D. (1989) Uptake, Depuration and Bioconcentration of ?Carbon-14|-

permethrin by Bluegill Sunfish (Lepomis macrochirus): ABC Lab Project 

Number PC-0117; FMC No.138E5489E1; ABC Final Report 37676. 

Unpublished study prepared by Analyti- cal Bio-chemistry Laboratories, Inc. in 

cooperation with FMC Corp. 54 p. 

41300402 Tullman, R. (1989) Accumulation Studies: Laboratory Studies of Pesticide 

Accumulation in Fish: Acid (Cyclopropyl)-?carbon-14| Labelled Permethrin in 

the Bluegill Sunfish: Lab Project Number P-2314; 138E5489E1-1. Unpublished 

study prepared by FMC Corp. in cooperation with Analytical Biochemistry 

Labora- tories, Inc. 96 p. 

41300403 Singer, S. (1989) Accumulation Studies: Laboratory Studies of Pesticide 

Accumulation in Fish: ?Carbon-14|-alcohol (Phenyl) Labelled Permethrin in the 

Bluegill Sunfish: Lab Project Number P-2262; 138E5489E1-2. Unpublished 

study prepared by FMC Corp. in cooperation with Analytical Biochemistry 

Laboratories, Inc. 83 p. 

92142050 Czochor, L. (1990) ICI Americas Inc. Phase 3 Summary of MRID 41300401 

and Related MRIDs 41300402, 41300403. Permethrin (Pounce) Insecticide 

Bioaccumulation in Fish: Project I.D.: 135E5489E1, 138E5489E1-1, 

138E5489E1-2. Prepared by FMC CORP. 20 p. 

201-1 Droplet size spectrum 

MRID Citation Reference 

40954101 Lindsay, A. (1988) Droplet Size Spectrum. Mist Blower Applicator: 

Laboratory Study No. FORM-1. Unpublished study prepared by FMC Corp. 

65 p. 

45486202 Zhai, J.; Groome, M. (1995) Study to Determine the Spray Drift, Droplet Size 

Spectrum and Droplet Deposition of Aqua-Permanone: Lab Project Number: 

GD95-0031. Unpublished study prepared by Aventis Environmental Science 

USA LP. 120 p. 
 100

45486203 Zhai, J. (1996) AquaPermanone Droplet Assessment with Common ULV 

Sprayers: Lab Project Number: 92034. Unpublished study prepared by Aventis 

Environmental Science USA LP. 8 p. 

202-1 Drift field evaluation 

MRID Citation Reference 

41336401 Hall, F.; Downer, R. (1989) Permethrin: A Review of Permethrin Orchard 

Spray Data. Unpublished study prepared by Ohio State Univ., Laboratory for 

Pest Control Application Technology. 38 p. 

43173801 Groome, J.; Mooney, M.; Bassler, M.; et al. (1992) Permanone 10 EC Spray 

Drift Study: Lab Project Number: HTRE/92/C1. Unpublished study prepared 

by Wellcome Berkhamsted, United Kingdom Fairfield America Co. 137 p. 

45486202 Zhai, J.; Groome, M. (1995) Study to Determine the Spray Drift, Droplet Size 

Spectrum and Droplet Deposition of Aqua-Permanone: Lab Project Number: 

GD95-0031. Unpublished study prepared by Aventis Environmental Science 

USA LP. 120 p. 

Non Guideline 

110698 ICI Americas, Inc. (1976) ?Environmental Effects of Ectiban Pyre- throid 

Insecticide 25% Wettable Powder|. (Compilation; unpub- lished study received 

Feb 3, 1977 under 10182-EX-8; CDL: 228187-A) 

110702 ICI United States, Inc. (1976) Ambush Pyrethroid Insecticide: Residue 

Chemistry. (Unpublished study received Jan 17, 1977 under 10182-EX-6; 

CDL:230167-C) 

110702 ICI United States, Inc. (1976) Ambush Pyrethroid Insecticide: Residue 

Chemistry. (Unpublished study received Jan 17, 1977 under 10182-EX-6; 

CDL:230167-C) 

137900 Hu, H; Weiner, P.; Ferraro, C. (1975) Vapor Pressure of FMC 33297: Report 

No. CGP-75-14. (Unpublished study received Jan 3, 1978 under 279-3013; 

submitted by FMC Corp., Philadelphia, PA; CDL: 096696-I) 

110698 ICI Americas, Inc. (1976) ?Environmental Effects of Ectiban Pyre- throid 

Insecticide 25% Wettable Powder|. (Compilation; unpublished study received 

Feb 3, 1977 under 10182-EX-8; CDL: 228187-A) 

44396502 Travis, K. (1997) A Modified Tier II Aquatic Exposure Analysis of Cotton 

Pyrethroids, Incorporating Landscape-Level Exposure Factors: Lab Project 

Number: PYRETHROIDS\3. Unpublished study prepared by Zeneca 

Agrochemical (Zeneca Ltd). 221 p. 
 101

44396504 Ritter, A.; Williams, W.; Cheplick, J. (1997) Tier 1 and Tier 2: Modeling of 

Pyrethroid Exposure to Aquatic Nontarget Organisms Associated with Use on 

Cotton: Lab Project Number: WEI 794.01: PWG. Unpublished study prepared 

by Waterborne Environmental, Inc. (WEI). 80 p. 

47164602 Holmes, C.; Vamshi, R. (2007) Data and Methodology Used for Spatial 

Analysis of California Red Legged Frog Observations and Proximate Land 

Cover Characteristics. Project Number: 3152007, WEI/252/03. Unpublished 

study prepared by Waterborne Environmental, Inc. (WEI). 19 p. 

Permethrin Ecotoxicity Bibliography 

71-1 Avian Single Dose Oral Toxicity 

MRID Citation Reference 

42119 Ross, D.B.; Cameron, D.M.; Roberts, N.L. (1976) The Acute Oral Tox- icity 

(LD^50I) of PP 557 (Permethrin) to Mallard Ducks: ICI 68/ WL/7639. 

(Unpublished study received Aug 22, 1977 under 10182- EX-3; prepared by 

Huntingdon Research Centre, England, submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL:096325-B) 

42120 Ross, D.B.; Cameron, D.M.; Roberts, N.L. (1976) The Acute Oral Tox- icity 

(LDI50^) of PP 557 (Permethrin) to Japanese Quail: ICI 68/ WL/7640. 

(Unpublished study received Aug 22, 1977 under 10182- EX-3; prepared by 

Huntingdon Research Centre, England, submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL:096325-C) 

42121 Ross, D.B.; Cameron, D.M.; Roberts, N.L. (1977) The Acute Oral Tox- icity 

(LDI50^) of PP 557 (Permethrin) to the Pheasant: ICI 68 WL/77154. 

(Unpublished study received Aug 22, 1977 under 10182- EX-3; prepared by 

Huntingdon Research Centre, England, submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL:096325-E) 

42142 Ross, D.B.; Cameron, D.M.; Roberts, N.L. (1977) The Acute Oral Toxicity 

(LD^50I) of PP 557 (Permethrin) to the Mallard Duck According to E.P.A. 

Guidelines: ICI 68 WL/77205. (Unpublished study received Aug 22, 1977 

under 10182-EX-3; prepared by Hunt- ingdon Research Centre, England, 

submitted by ICI Americas, Inc., Wilmington, Del.; CDL:096325-AE) 

42143 Ross, D.B.; Cameron, D.M.; Roberts, N.L. (1977) The Acute Oral Toxicity 

(LD^50I) of PP 557 (Permethrin) to the Japanese Quail According to E.P.A. 

Guidelines: ICI 68 WL/77207. (Unpublished study received Aug 22, 1977 

under 10182-EX-3; prepared by Hunt- ingdon Research Centre, England, 

submitted by ICI Americas, Inc., Wilmington, Del.; CDL:096325-AF) 

42144 Ross, D.B.; Cameron, D.M.; Roberts, N.L. (1977) The Acute Oral Toxicity 

(LDI50^) of PP 557 (Permethrin) to the Starling: ICI/68 WL/76499. 
 102

(Unpublished study received Aug 22, 1977 under 10182- EX-3; prepared by 

Huntingdon Research Centre, England, submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL:096325-AG) 

42145 Ross, D.B.; Cameron, D.M.; Roberts, N.L. (1977) The Acute Oral Toxicity 

(LDI50^) of PP 557 (Permethrin) to the Ring-Necked Phe- asant According 

to E.P.A. Guidelines: ICI 68 WL/77207. (Unpub- lished study received Aug 

29, 1977 under 1082-EX-3; prepared by Huntingdon Research Center, 

England, submitted by ICI Americas, Inc., Wilmington, Del.; CDL:096325-

AH) 

72844 Ross, D.B.; Cameron, D.M.; Roberts, N.L. (1976) The Acute Oral Toxicity 

(LDI50^) of PP 557 (Permethrin) to Starlings: ICI 68/ WL/7637. 

(Unpublished study received Dec 2, 1976 under 10182- EX-3; prepared by 

Huntingdon Research Centre, England, submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL:095995-B) 

73686 Fink, R. (1975) Final Report: Acute Oral LD^50~--Mallard Duck: Project 

No. 104-115. (Unpublished study received on unknown date under 279-EX60; prepared by Truslow Farms, Inc., submitted by FMC Corp., Philadelphia, 

Pa.; CDL:226419-X) 

110669 FMC Corp. (1976) Wildlife Toxicology Studies: ?FMC 33297|. Summary of 

studies 096699-W through 096699-AA. (Unpublished study re- ceived Jan 3, 

1978 under 279-3013; CDL:096699-V) 

112938 Fink, R. (1975) Acute Oral LD50--Mallard Duck: FMC 33297: Project No. 

104-115; NCT 601.62. Final rept. (Unpublished study re- ceived Jan 3, 1978 

under 279-3013; prepared by Truslow Farms, Inc., submitted by FMC Corp., 

Philadelphia, PA; CDL:096699-W) 

157306 ICI United States, Inc. (1976) [Acute Oral Toxicity to Rats Using PP557]. 

Unpublished study. 8 p. 

41888401 Hakin, B.; Rodgers, M.; Dawe, I. (1991) Permethrin: Acute Oral Tox- icity 

(LD50) to Mallard Duck: Lab Project Number: ISN 244/91362. Unpublished 

study prepared by Huntingdon Research Centre, Ltd. 29 p. 

45369711 Grau, R. (1994) (Inert Ingredient) Acute Oral Toxicity to Bobwhite Quail: 

Lab Project Number: VB-024: E2920732. Unpublished study prepared by 

Bayer AG. 37 p. 

71-2 Avian Dietary Toxicity 

MRID Citation Reference 

42122 Ross, D.B.; Cameron, D.M.; Roberts, N.L. (1976) The Subacute Toxic- ity 

(LDI50^) of PP 557 (Permethrin) to Mallard Ducks: ICI 68 WL/ 75837. 

(Unpublished study received Aug 22, 1977 under 10182-EX- 3; prepared by 
 103

Huntingdon Research Centre, England, submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL:096325-F) 

42123 Ross, D.B.; Cameron, D.M.; Roberts, N.L. (1976) The Subacute Toxic- ity 

(LDI50^) of PP 557 (Permethrin) to Japanese Quail: ICI 68/ WL/7638. 

(Unpublished study received Aug 22, 1977 under 10182- EX-3; prepared by 

Huntingdon Research Centre, England, submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL:096325-G) 

43733 Ross, D.B.; Cameron, D.M.; Roberts, N.L. (1976) The Subacute Toxicity 

(LCI50^) of PP 557 (Permethrin) to Pheasants: ICI/68WL/ 75839. 

(Unpublished study received Dec 2, 1976 under 10182- EX-3; prepared by 

Huntingdon Research Centre, England, submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL:095995-D) 

43734 Ross, D.B.; Cameron, D.M.; Roberts, N.L. (1976) The Subacute Tox- icity 

(LCI50^) of PP 557 (Permethrin) to Adult Starlings: ICI68/ WL/7636. 

(Unpublished study received Dec 2, 1976 under 10182- EX-3; prepared by 

Huntington Research Centre, England, submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL:095995-E) 

72845 Fink, R. (1975) Final Report: Eight-Day Dietary LCI50^--Bobwhite Quail: 

Project No. 104-113. (Unpublished study received Dec 2, 1976 under 10182-

EX-3; prepared by Truslow Farms, Inc., submit- ted by ICI Americas, Inc., 

Wilmington, Del.; CDL:095995-C) 

83717 Fink, R. (1975) Final Report: Eight-Day Dietary LCI50^--Mallard Duck: 

Project No. 104-114. (Unpublished study received on un- known date under 

279-EX-60; prepared by Truslow Farms, Inc., submitted by FMC Corp., 

Philadelphia, Pa.; CDL:226419-Y) 

88741 Fink, R. (1975) Final Report: Eight-Day Dietary LCI50^--Bobwhite Quail: 

Project No. 104-113. (Unpublished study received on unknown date under 

279-EX-60; prepared by Truslow Farms, Inc., submitted by FMC Corp., 

Philadelphia, Pa.; CDL:226419-Z) 

 

112939 Fink, R. (1975) Eight-day Dietary LC50--Mallard Duck: FMC 33297: 

Project No. 104-114; NCT 600.62. Final rept. (Unpublished study received 

Jan 3, 1978 under 279-3013; prepared by Truslow Farms, Inc., submitted by 

FMC Corp., Philadelphia, PA; CDL: 096699-X) 

112940 Fink, R. (1975) Eight-day Dietary LC50--Bobwhite Quail: FMC 33297: 

Project No. 104-113; NCT 600.62. Final rept. (Unpublished study received 

Jan 3, 1978 under 279-3013; prepared by Truslow Farms, Inc., submitted by 

FMC Corp., Philadelphia, PA; CDL: 096699-Y) 

41888402 Hakin, B.; Rodgers, M.; Dawe, I.; et al. (1991) Permethrin: Subacute Dietary 

Toxicity (LC50) to Bobwhite Quail: Lab Project Number : ISN245/91262. 
 104

Unpublished study prepared by Huntingdon Research Centre, Ltd. 29 p. 

41888403 Hakin, B.; Rodgers, M.; Dawe, I.; et al. (1991) Permethrin: Subacu| te 

Dietary Toxicity (LC50) to Mallard Duck: Lab Project Number: 

ISN246/912632. Unpublished study prepared by Huntingdon Research 

Centre, Ltd. 29 p. 

71-4 Avian Reproduction 

MRID Citation Reference 

42124 Fink, R. (1976) Final Report: One Generation Reproduction Study-- Mallard 

Duck: Project No. 123-113. (Unpublished study received Aug 22, 1977 under 

10182-EX-3; prepared by Wildlife Internation- al, Ltd., submitted by ICI 

Americas, Inc., Wilmington, Del.; CDL:096325-J) 

42125 

Or 

110671 

Fink, R. (1976) Final Report: One-Generation Reproduction Study-- Bobwhite 

Quail: Project No. 123-112. (Unpublished study re- ceived Aug 22, 1977 under 

10182-EX-3; prepared by Wildlife In- ternational, Ltd., submitted by ICI 

Americas, Inc., Wilmington, Del.; CDL:096325-K) 

110669 FMC Corp. (1976) Wildlife Toxicology Studies: ?FMC 33297|. Summary of 

studies 096699-W through 096699-AA. (Unpublished study re- ceived Jan 3, 

1978 under 279-3013; CDL:096699-V) 

110670 Fink, R. (1976) One-generation Reproduction Study--Mallard Duck: PP 557: 

Project No. 123-113; ACT 125.71. Final rept. (Unpub- lished study received Jan 

3, 1978 under 279-3013; prepared by Wildlife International Ltd., submitted by 

FMC Corp., Philadel- phia, PA; CDL:096699-Z) 

110671 Fink, R. (1976) One-generation Reproduction Study--Bobwhite Quail: PP 557: 

Project No. 123-112; ACT 125.71. Final rept. (Unpub- lished study received Jan 

3, 1978 under 279-3013; prepared by Wildlife International Ltd., submitted by 

FMC Corp., Philadel- phia, PA; CDL:096699-AA) 

42322901 Beavers, J.; Foster, J.; Lynn, S.; et al. (1992) Permethrin: A One-Generation 

Study with the Northern Bobwhite (Colinus virginianus): Lab Project Number 

104-166: A90-3330. Unpublished study prepared by Wildlife Intl. 157 p. 

42322902 Beavers, J.; Foster, J.; Lynn, S.; et al. (1992) Permethrin: A One-Generation 

Reproduction Study with the Mallard (Anas platyrhynchus): Lab Project Number 

104-167: A90-3328. Unpublished study prepared by Wildlife Intl. 161 p. 

72-1 Acute Toxicity to Freshwater Fish 

MRID Citation Reference 

43263 LeBlanc, G.A.; Sousa, J.; Sleight, B.H., III. (1979) Acute Toxicity of FMC 

33297 to Bluegill (Lepomis macrochirus): Re- port # BW-79-12-582. 
 105

(Unpublished study received Jul 24, 1980 under 279-3013; prepared by 

EG&G, Bionomics, submitted by FMC Corp., Philadelphia, Pa.; 

CDL:242902-A) 

43265 LeBlanc, G.A.; Sousa, J.; Sleight, B.H., III. (1979) Acute Tox- icity of FMC 

33297 to Rainbow Trout (Salmo gairdneri): Re- port # BW-79-12-584. 

(Unpublished study received Jul 24, 1980 under 2789-3013; prepared by 

EG&G, Bionomics, submitted by FMC Corp., Philadelphia, Pa.; 

CDL:242902-C) 

65816 Hill, R.W.; Young, B.E. (1978) The Acute Toxicity of Permethrin Acid and 

3-Phenoxy Benzyl Alcohol to Rainbow Trout (Salmo gairdneri): BL/B/1918. 

(Unpublished study received Dec 29, 1980 under 10182-EX-19; prepared by 

Imperial Chemical Industries, Ltd., England, submitted by ICI Americas, 

Inc., Wilmington, Del.; CDL:244017-J) 

97444 Maddock, B.G. (1978) Determination of the Acute Toxicity of Compound 

212 (WRL) to Bluegill Sunfish (Lepomis macrochirus) Using Dimethyl 

Sulphoxide as the Solvent: Doc. No. HEFG 28- 13. (Unpublished study 

received Mar 17, 1982 under 59-200; pre- pared by Wellcome Foundation 

Ltd., England, submitted by Burroughs Wellcome Co., Research Triangle 

Park, N.C.; CDL: 247045-A) 

97445 Maddock, B.G. (1978) Determination of the Acute Toxicity of 21Z (WRL) 

to Bluegill Sunfish (?~Lepomis macrochirus~?) Using Ace- tone as the 

Solvent: Doc. No. HEFG 78-17. (Unpublished study received Mar 17, 1982 

under 59-2; prepared by Wellcome Founda- tion Ltd., England, submitted by 

Burroughs Wellcome Co., Research Triangle Park, N.C.; CDL:247045-B) 

97446 Maddock, B.G. (1978) Determination of the Acute Toxicity of Compound 

21Z (WRL) to Rainbow Trout (Salmo gairdneri) Using Di- Methyl 

Sulphoxide as the Solvent: Doc. No. HEFG 78-11. (Un- published study 

received Mar 17, 1982 under 59-200; prepared by Wellcome Foundation 

Ltd., England, submitted by Burroughs Wellcome Co., Research Triangle 

Park, N.C.; CDL:247045-C) 

97447 Maddock, B.G. (1978) Determination of the Acute Toxicity of Com- pound 

21Z (WRL) to Rainbow Trout (?~Salmo gairdneri~?) Using Ac- etone as the 

Solvent: Doc. No. HEFG 78-12. (Unpublished study received Mar 17, 1982 

under 59-200; prepared by Wellcome Founda- tion Ltd., England, submitted 

by Burroughs Wellcome Co., Re- search Triangle Park, N.C.; CDL:247045-

D) 

110657 or 

73687 

Bentley, R. (1974) Acute Toxicity of FMC-33297 Technical to Blue- gill 

(Lepomis macrochirus) and Rainbow Trout (Salmo gairdneri): (Submitter) 

NCT 551.61. (Unpublished study received Jan 3, 1978 under 279-3013; 

prepared by Bionomics, EG & G Environmental Consultants, submitted by 

FMC Corp., Philadelphia, PA; CDL: 096699-B) 

110663 Union Carbide Corp. (1976) Acute Toxicity of FMC 33297 to Bluegill 
 106

Sunfish, Lepomis macrochirus Rafinesque and the Water Flea, Daphnia 

magna Straus: (Submitter) ACT 29.11, .12. (Unpublished study received Jan 

3, 1978 under 279-3013; submitted by FMC Corp., Philadelphia, PA; 

CDL:096699-J) 

110705 Hill, R.; Maddock, B.; Hart, B.; et al. (1977) Acute Toxicity of JFU 5054 to 

Bluegill Sunfish ...: BL/B/1832. (Unpublished study received Nov 30, 1977 

under 10182-EX-7; prepared by Imperial Chemical Industries, Ltd., Eng., 

submitted by ICI Americas, Inc., Wilmington, DE; CDL:232533-A) 

110706 ICI Americas, Inc. (1977) Summary: ?Environmental Data on PP 557|. 

(Compilation; unpublished study received Oct 25, 1977 under 10182-EX-7; 

CDL:233029-A) 

141977 Coulon, D. (1982) Toxicity of Ambush and Pydrin to Red Crawfish, 

Procambarus clarkii (Girard) and Channel Catfish, Ictaluras pun- ctatus 

rafinesque in Laboratory and Field Studies and the Accum- ulation and 

Dissipation of Associated Residues. Unpublished dissertation study prepared 

by Louisiana State Univ. 56 p. 

155779 Kumaraguru, A.; Beamish, F. (1981) Lethal toxicity of permethrin (NRDC143) to rainbow trout, Salmo gairdneri, in relation to body weight and water 

temperature. Water Research 15:503-505. 

155781 Holcombe, G.; Phipps, G.; Tanner, D. (1982) The acute toxicity of kelthane, 

dursban, disulfoton, pydrin, and permethrin to fathead minnows Pimephales 

promelas and rainbow trout Salmo gairdneri. Environmental Pollution 

29:167-178. 

41068002 Coats, J.; O'Donnell-Jeffery, N. (1979) Toxicity of four synthetic pyrethroid 

insecticides to rainbow trout. Bulletin of Enviro- mental Contamination and 

Toxicology 23:250-255. 

41068003 McLeese, D.; Metcalfe, C.; Zitko, V. (1980) Lethality of permethrin, 

cypermethrin and fenvalerate to salmon, lobster and shrimp. Bulletin of 

Environmental Contamination and Toxicology 25:950-955. 

00110705 Adams, D. (1990): Permethrin (PF557): Determination of a 24% w/w 

Formulation to Bluegill Sunfish (Lepomis macrochirus): Lab Project 

Number: BL/B/1832. Unpublished study prepared by ICI Brixham Lab. 11 p. 

 

 

42584003 Sankey, S.; Morris, D.; Caunter, J. et al. (1992) Permethrin: Acute Toxicity 

to Rainbow Trout of a 10% EC Formulation: Lab Project Number: 

BL4529/B. Unpublished study prepared by ICI, PLC. 21 p. 

42584004 Sankey, S.; Morris, D.; Caunter, J.; et al. (1992) Permethrin: Acute Toxicity 

to Bluegill Sunfish of a 10% EC Formulation: Lab Project Number: 
 107

BL4570/B. Unpublished study prepared by ICI, PLC. 21 p. 

43740601 Kent, S.; Morris, D.; Caunter, J. et al. (1995) Permethrin: Acute Toxicity to 

Rainbow Trout (Oncorhynchus mykiss) of a 2 lb./gallon (25%) Formulation: 

Fish Toxicity in Rainbow Trout (TEP): Lab Project Number: BL5427/B: 

AB0015/A. Unpublished study prepared by Brixham Environmental Lab. 24 

p. 

110663 Union Carbide Corp. (1976) Acute Toxicity of FMC 33297 to Bluegill 

Sunfish, Lepomis macrochirus Rafinesque and the Water Flea, Daphnia 

magna Straus: (Submitter) ACT 29.11, .12. (Unpublished study received Jan 

3, 1978 under 279-3013; submitted by FMC Corp., Philadelphia, PA; 

CDL:096699-J) 

42126 Hill, R.W.; Maddock, B.G.; Hart, B. (1976) Determination of the Acute 

Toxicity of PP557 to Rainbow Trout (Salmo gairdnerii): BL/B/1700. 

Includes undated method entitled: Determination of low levels of PP557 in 

water samples from fish bioassay tests. (Unpublished study received Aug 22, 

1977 under 10182-EX-3; pre- pared by Imperial Chemical Industries, Ltd., 

submitted by ICI Americas, Inc., Wilmington, Del.; CDL:096325-L) 

42127 Hill, R.W.; Maddock, B.G.; Hart, B.; et al. (1976) Determination of Acute 

Toxicity of PP557 to Brook Trout (?~Salvelinus fonti?~- ?~nalis?~): 

BL/B/1712. Includes undated method entitled: Deter- mination of low levels 

of PP557 in water samples from fish bio- assay tests. (Unpublished study 

received Aug 22, 1977 under 10182-EX-3; prepared by Imperial Chemical 

Industries, Ltd., sub- mitted by ICI Americas, Inc., Wilmington, Del.; 

CDL:096325-M) 

42128 Hill, R.W.; Maddock, B.G.; Hart, B. (1976) Determination of the Acute 

Toxicity of PP 557 to Bluegill Sunfish (?~Lepomis macro?- ?~chirus~?): 

BL/B/1701. Includes undated method entitled: De- termination of low levels 

of PP 557 in water samples from fish bioassay tests. (Unpublished study 

received Aug 22, 1977 under 10182-EX-3; prepared by Imperial Chemical 

Industries, Ltd., sub- mitted by ICI Americas, Inc., Wilmington, Del.; 

CDL:096325-P) 

42129 Hill, R.W.; Maddock, B.G.; Hart, B.; et al. (1976) Determination of the 

Acute Toxicity of PP 557 to Fathead Minnow (?~Pimephales ?~promelas~?): 

Report BL/B/1726. Includes undated method en- titled: Determination of low 

levels of PP 557 in water samples from fish bioassay tests. (Unpublished 

study received Aug 22, 1977 under 10182-EX-3; prepared by Imperial 

Chemical Industries, Ltd., submitted by ICI Americas, Inc., Wilmington, 

Del.; CDL: 096325-R) 

42130 Hill, R.W.; Maddock, B.G.; Hart, B.; et al. (1976) Determination of the 

Acute Toxicity of PP 557 to Mirror Carp (?~Cyprinus car~?- ?~pio~?): 

BL/B/1715. Includes undated method entitled: Determi- nation of low levels 

of PP 557 in water samples from fish bio- assay tests. (Unpublished study 
 108

received Aug 22, 1977 under 10182-EX-3; prepared by Imperial Chemical 

Industries, Inc., sub- mitted by ICI Americas, Inc., Wilmington, Del.; 

CDL:096325-S) 

42132 Hill, R.W.; Maddock, B.G.; Hart, B.; et al. (1977) Determination of the 

Acute Toxicity of Formulation JFU 5054 to Rainbow Trout (?~Salmo 

gairdnerii~?): BL/B/1798. Includes undated method en- titled: Determination 

of low levels of JFU 5054 in water samples from fish bioassay tests. 

(Unpublished study received Aug 22, 1977 under 10182-EX-3; prepared by 

Imperial Chemical Industries, Ltd., submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL: 096325-U) 

42133 Hill, R.W.; Maddock, B.G.; Hart, B.; et al. (1977) Determination of the 

Acute Toxicity of Formulation JFU 5054 to Bluegill Sunfish (?~Lepomis 

macrochirus?~): BL/B/1799. Includes undated method entitled: The 

determination of low levels of JFU 5054 in water samples from fish bioassay 

tests. (Unpublished study received Aug 22, 1977 under 10182-EX-3; 

prepared by Imperial Chemical In- dustries, Ltd., submitted by ICI Americas, 

Inc., Wilmington, Del.; CDL:096325-V) 

43735 Buccafusco, R.J. (1976) Acute Toxicity of PP-557 Technical to Channel 

Catfish (?~Ictalurus punctatus~?). (Unpublished study received Dec 2, 1976 

under 10182-EX-3; prepared by EG&G, Bio- nomics, submitted by ICI 

Americas, Inc., Wilmington, Del.; CDL:095995-H) 

72846 Buccafusco, R.J. (1976) Acute Toxicity of PP-557 Technical to Coho 

Salmon (~Oncorhynchus kisutch~). (Unpublished study received Dec 2, 

1976 under 10182-EX-3; prepared by EG&G, Bionomics, sub- mitted by ICI 

Americas, Inc., Wilmington, Del.; CDL:095995-G) 

73685 Bentley, R.E. (1974) Acute Toxicity of FMC-33297 Technical to Blue- gill 

(~Lepomis macrochirus~) and Rainbow Trout (~Salmo~ ?~gairdneri~). 

(Unpublished study received on unknown date under 279-EX-60; prepared 

by Bionomics, EG&G Environmental Consultants, submitted by FMC Corp., 

Philadelphia, Pa.; CDL: 226419-W) 

73687 Bentley, R.E. (1975) Acute Toxicity of FMC-33297 3.2 EC to Bluegill 

(Lepomis macrochirus) and Rainbow Trout (Salmo gairdneri). (Unpublished 

study received on unknown date under 279-EX-60; prepared by EG&G, 

Bionomics, submitted by FMC Corp., Philadel- phia, Pa.; CDL:226419-AA) 

83085 Buccafusco, R.J. (1976) Acute Toxicity of PP-557 Technical to Atlantic 

Salmon (~Salmo salar~). (Unpublished study received Dec 2, 1976 under 

10182-EX-3; prepared by EG&G, Bionomics, sub- mitted by ICI Americas, 

Inc., Wilmington, Del.; CDL:095995-F) 

 72-2 Acute Toxicity to Freshwater Invertebrates 

MRID Citation Reference 
 109

43267 Surprenant, D.C. (1979) Acute Toxicity of FMC 33297 to the Water Flea 

(?~Daphnia magna~?): Report # BW-79-12-574. (Unpublished study 

received Jul 24, 1980 under 279-3013; prepared by EG&G, Bionomics, 

submitted by FMC Corp., Philadelphia, Pa.; CDL: 242902-E) 

65817 Getty, C.; Wilkinson, W.; Davies, P.J.; et al. (1978) Permethrin Acid and 3-

Phenoxybenzyl Alcohol: Toxicity to First Instar Daphnia magna: Report 

Series RJ 0042B. (Unpublished study received Dec 29, 1980 under 10182-

EX-19; prepared by Imperial Chemical Industries, Ltd., submitted by ICI 

Americas, Inc., Wilmington, Del.; CDL:244017-K) 

97448 Maddock, B.G. (1979) Determination of the Acute Toxicity of WRL 21Z to 

the Freshwater Shrimp (Gammarus pulex) Using Acetone as the Solvent: 

Doc. No. HEFG 79-4. (Unpublished study received Mar 17, 1982 under 59-

200; prepared by Wellcome Foundation Ltd., England, submitted by 

Burroughs Wellcome Co., Research Triangle Park, N.C.; CDL:247045-E) 

97449 Thompson, R.S.; Williams, T.D. (1978) Determination of the Acute Toxicity 

of Compound 21Z (WRL) to Daphnia magna Using Acetone as the Solvent: 

Doc. No. HEFG 78-10. (Unpublished study re- ceived Mar 17, 1982 under 

59-200; prepared by Wellcome Founda- tion Ltd., England, submitted by 

Burroughs Wellcome Co., Re- search Triangle Park, N.C.; CDL:247045-F) 

110658 or 

43736 

Bentley, R. (1975) Acute Toxicity of FMC-33297 Technical to Water Flea 

(Daphnia magna): ?Submitter| NCT 624.61. (Unpublished study received Jan 

3, 1978 under 279-3013; prepared by EG & G, Bionomics, submitted by 

FMC Corp., Philadelphia, PA; CDL: 096699-D) 

110659 Bentley, R. (1975) Acute Toxicity of FMC-33297 3.2 EC to Water Flea 

(Daphnia magna): ?Submitter| NCT 623.61. (Unpublished study re- ceived 

Jan 3, 1978 under 279-3013; prepared by EG & G, Bio- nomics, submitted 

by FMC Corp., Philadelphia, PA; CDL:096699-E) 

141970 Anderson, R. (1982) Toxicity of Fenvalerate and permethrin to sev- eral 

nontarget aquatic invertebrates. Environmental Entomology. 11(6): 1251-

1257. 

152736 Getty, C.; Wilkinson, W. (1978) PP557: Ecological Effects on Three Ponds, 

U.K. 1976-77. Observations on Invertebrates and Amphibia up to 1 Year 

after Treatment: Report No. RJ0041B. Unpublished study prepared by 

Imperial Chemical Industries PLC. 21 p. 

42584002 Kent, S.; Sankey, S.; Grinell, A. (1992) Permethrin: Acute Toxicity to 

Daphnia magna of a 10% EC Formulation: Lab Project Number: BL4530/B. 

Unpublished study prepared by ICI, PLC. 19 p. 

43740602 Kent, S.; Morris, D.; Banner, A. et al. (1995) Permethrin: Acute Toxicity to 

Daphnia magna of a 2 lb/gallon (25%) Formulation: Invertebrate Toxicity--
 110

Freshwater LC50 (TEP): Lab Project Number: BL5382/B: AB0015/B: 

AG240. Unpublished study prepared by Brixham Environmental Lab. 21 p. 

42136 Buccafusco, R.J. (1977) Acute Toxicity of Permethrin Technical (PP 557) to 

Crayfish (?~Procambarus blandingi?~). (Unpublished study received Aug 

22, 1977 under 10182-EX-3; prepared by EG&G, Bionomics, submitted by 

ICI Americas, Inc., Wilmington, Del.; CDL:096325-Y) 

42137 Doma, S.; Evered, P. (1976) PP557: Acute Toxicity and Reproduction 

Studies on First Instar and Ephippia of~Daphnia magna?~: Report Series 

TMJ 1455B. (Unpublished study received Aug 22, 1977 un- der 10182-EX3; submitted by ICI Americas, Inc., Wilmington, Del.; CDL:096325-Z) 

42138 Doma, S.; Evered, P. (1976)~Daphnia magna?~: Determination of Acute 

Toxicity of Pesticides: TMJ 1405A. (Unpublished study received Aug 22, 

1977 under 10182-EX-3; prepared by Imperial Chemical In- dustries, Ltd., 

submitted by ICI Americas, Inc.; Wilmington, Del.; CDL:096325-AA) 

42139 Evered, P.; Doma, S. (1977) PP 557: Acute Toxicity of Emulsifiable 

Concentrate (JFU 5054) to First Instar~Daphnia magna?~: Report Series 

TMJ 1504 B. (Unpublished study received Aug 22, 1977 un- der 10182-EX3; prepared by Imperial Chemical Industries, Ltd., submitted by ICI 

Americas, Inc., Wilmington, Del.; CDL: 096325-AB) 

42141 Doma, S. (1976) PP557: Acute Toxicity and Reproduction Studies on the 

Large Pond Snail,?~Limnaea stagnalis?~: Report Series TMJ 1395B. 

(Unpublished study received Aug 22, 1976 under 10182- EX-3; prepared by 

Imperial Chemical Industries, Ltd., submitted by ICI Americas, Inc., 

Wilmington, Del.; CDL:096325-AD) 

43736 Bentley, R.E. (1975) Acute Toxicity of FMC-33297 Technical to Water Flea 

(?~Daphnia magna~?): NCT 624.61. (Unpublished study received Dec 2, 

1976 under 10182-EX-3; prepared by EG&G, Bio- nomics, submitted by ICI 

Americas, Inc., Wilmington, Del.; CDL:095995-I) 

47039 Forbis, A.D.; McAllister, W.A.; Thompson, C.M.; et al. (1980) Chronic 

Toxicity of ^14IC-Permethrin to~Daphnia magna~under Flow-Through Test 

Conditions: Chronic Toxicity Final Report # 23647. (Unpublished study 

including letters dated Apr 25, 1979 from M.J. Jaber to William A. 

McAllister; Jan 14, 1980 from A.D. Forbis to Mark Jaber; Sep 9, 1980 from 

A.D. Forbis to Mark Jab- er, received Oct 10, 1980 under 279-3014; 

prepared by Analytical Bio Chemistry Laboratories, Inc., submitted by FMC 

Corp., Phila- delphia, Pa.; CDL:243505-A) 

47040 Forbis, A.D.; McAllister, W.A.; Thompson, C.M.; et al. (1980) Dy- namic 

Acute Toxicity of ^14IC-Permethrin to Mayfly Nymphs (~Hexagenia 

bilineata~) in a Flow-Through Diluter System: Fi- nal Report No. 23648. 

(Unpublished study including letters dated Oct 30, 1979 from M.J. Jaber to 

William McAllister; Dec 4, 1979 from A.D. Forbis to Mark Jaber; Dec 12, 

1979 from M.J. Jaber to Alan Forbis, received Oct 10, 1980 under 279-3014; 
 111

pre- pared by Analytical Bio chemistry Laboratories, Inc., submitted by FMC 

Corp., Philadelphia, Pa.; CDL:243505-B) 

 72-3 Acute Toxicity to Estuarine/Marine Organisms 

MRID Citation Reference 

110660 Heitmuller, T. (1975) Acute Toxicity of FMC 33297 Technical (95.7%) to 

Eastern Oysters (Crassostrea virginica), Pink Shrimp (Penaeus duorarum), 

and Fiddler Crabs (Uca pugilator): ?Submitter| NCT 619.61. (Unpublished 

study received Jan 3, 1978 under 279- 3013; prepared by Bionomics, EG 

& G, Inc., submitted by FMC Corp., Philadelphia, PA; CDL:096699-F) 

110661 Heitmuller, T. (1975) Acute Toxicity of FMC 33297 3.2 EC to Eastern 

Oysters (Crassostrea virginica), Pink Shrimp (Penaeus duorarum), and 

Fiddler Crabs (Uca pugilator): (Submitter) NCT 620.61. (Unpublished 

study received Jan 3, 1978 under 279-3013; prepared by Bionomics, EG & 

G, Inc., submitted by FMC Corp., Philadel- phia, PA; CDL:096699-G) 

141967 Borthwick, P.; Walsh, G. (1981) Initial Toxicological Assessment of 

Ambush, Bolero, Bux, Dushan, Fentrifanil, Larvin, and Pydrin: Static 

Acute Toxicity Tests with Selected Estuarine Algae, In- vertebrates, and 

Fish: EPA-600/4-81-076. Unpublished study pre- pared by Environmental 

Protection Agency, Environmental Research Laboratory. 9 p. 

155767 Zitko, V.; Carson, W.; Metcalffe, C. (1977) Toxicity of pyrethroids to 

juvenile Atlantic salmon. Bull. Environ. Contam. Toxicol. 18:35-41. 

155788 Zitko, V.; McLeese, W.; Metcalfe, C. (1979) Toxicity of permethrin, 

decamethrin, and related pyrethroids to salmon and lobster. Bull. 

Environm. Contam. Toxicol. 21:338-343. 

41134801 Ward, G.; Rabe, B. (1989) Acute Toxicity of Permethrin Technical to 

Inland Silversides (Menidia beryllina) under Flow-through Con- ditions: 

Laboratory Project ID No. 93008-0200-2130. FMC Corp. Study No. A88-

2747. Unpublished study prepared by Hunter/ESE Inc. 55 p. 

41874901 Ward, G.; Rabe, B. (1989) Acute Toxicity of Permethrin Technical to 

Inland Silversides (Menidia beryllina) Under Flow-through Condi- tions: 

Lab Project Number: 93008/0200/2130. Unpublished study prepared by 

Hunter/ESE, Inc. 55 p. 

42584001 Kent, S.; Williams, T.; Sankey, S.; et al. (1992) Permethrin: Acute 

Toxicity to Mysid Shrimp of a 10% EC Formulation: Lab Project Number: 

BL4566/B. Unpublished study prepared by ICI, PLC. 18 p. 

42608201 Sankey, S.; Morris, D.; Caunter, J.; et al. (1992) Permethrin: Acute 

Toxicity to Sheepshead Minnow (Cyprinodon variegatus) of a 10% EC 
 112

Formulation: Lab Project Number: W420/D (FT31/91): BL4564/B. 

Unpublished study prepared by Imperial Chemical Industries, PLC. 18 p. 

42723301 Thompson, R.; Sankey, S. (1992) Permethrin: Acute Toxicity of a 10% EC 

Formulation to Larvae of the Pacific Oyster (Crassostrea gigas): Lab 

Project Number: BL4689/B. Unpublished study prepared by Zeneca, Ltd. 

19 p. 

42795101 Sankey, S.; Kent, S.; Holland, M. et al. (1993) Permethrin: Acute Toxicity 

to Sheepshead Minnow (Cyprinodon variegatus) of a 2EC Formulation: 

Lab Project Number: BL4748/B: FT15/92. Unpublished study prepared by 

Brixham Environmental Lab. 16 p. 

43394601 Sankey, S. (1994) Addendum to MRID 42608201-Permethrin: Acute 

Toxicity to Sheepshead Minnow (Cyprinodon variegatus) of 10% EC 

formulation: Response to EPA EEB/EFED Review: Lab Project Number: 

BL/4564/B/ADDENDUM. Unpublished study prepared by Brixham 

Environmental Lab. 9 p. 

43394602 Sankey, S. (1994) Addendum to MRID 42795101-Permethrin: Acute 

Toxicity to Sheepshead Minnow (Cyprinodon variegatus) of a 2EC 

formulation: Response to EPA EEB/EFED Review: Lab Project Number: 

BL/4748/B/ADDENDUM. Unpublished study prepared by Brixham 

Environmental Lab. 17 p. 

43492901 Sankey, S. (1994) Addendum to MRID 42584001: Permethrin: Acute 

Toxicity to Mysid Shrimp (Mysidopsis bahia) of a 10 (percent) EC 

Formulation: Response to EPA EEB/EFED Review: Lab Project Number: 

BL4566/B: BL4566/B ADDENDUM. Unpublished study prepared by 

Brixham Environmental Lab. 16 p. 

43492902 Thompson, R. (1986) Supplemental Data in Support of MRID 42584001: 

Permethrin: Determination of Acute Toxicity to Mysid Shrimps 

(Mysidopsis bahia): Lab Project Number: BL/B/2921. Unpublished study 

prepared by Brixham Environmental Lab. 16 p. 

42135 Heitmuller, T. (1977) Acute Toxicity of PP557 to Brown Shrimp (Penqeus 

aztecus) and Fiddler Crabs (Uca pugilator). (Unpub- lished study received 

Aug 22, 1977 under 10182-EX-3; prepared by EG&G, Bionomics, 

submitted by ICI Americas, Inc., Wil- mington, Del.; CDL:096325-X) 

42140 Thompson, R.S.; Hill, R.W.; Cornish, S.K. (1977) Investigation of the 

Acute Toxicity of PP 557 to the Pacific Oyster (Crassostrea gigas?): 

BL/B/1796. Includes undated method entitled: The determination of low 

levels of PP 557 in seawater samples from bioassay tests. (Unpublished 

study received Aug 22, 1977 under 10182-EX-3; prepared by Imperial 

Chemical Industries, Ltd., submitted by ICI America, Inc., Wilmington, 

Del.; CDL: 096325-AC) 

72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study 
 113

MRID Citation Reference 

110662 Doma, S.; Evered, P.; Sealey, C. (1977) PP557: Acute Toxicity and 

Reproduction Studies on First Instar and Ephippia of Daphnia magna: TMJ 

1455B. (Unpublished study received Jan 3, 1978 under 279-3013; prepared 

by Imperial Chemical Industries, Ltd., submitted by FMC Corp., 

Philadelphia, PA; CDL:096699-H) 

141967 Borthwick, P.; Walsh, G. (1981) Initial Toxicological Assessment of 

Ambush, Bolero, Bux, Dushan, Fentrifanil, Larvin, and Pydrin: Static Acute 

Toxicity Tests with Selected Estuarine Algae, In- vertebrates, and Fish: 

EPA-600/4-81-076. Unpublished study pre- pared by Environmental 

Protection Agency, Environmental Research Laboratory. 9 p. 

40102001 Thompson, R. (1986) Permethrin: Determination of Chronic Toxicity to 

Mysid Shrimps (Mysidopsis bahia): Laboratory Project ID: BL/B/2965. 

Unpublished study prepared by Imperial Chemical Industries PLC. 24 p. 

41068007 Hansen, D.; Goodman, L.; Moore, J.; et al. (1983) Effects of the synthetic 

pyrethroid AC 222, 705, permethrin and fenvalerate on sheepshead minnows 

in early life stage toxicity tests. Environ- mental Toxicology and Chemistry 

2:251-258. 

41068008 Spehar, R.; Tanner, D.; Nordling, B. (1983) Toxicity of the synthe- tic 

pyrethroids, permethrin and AC 222, 705 and their accumula- tion in early 

life stages of fathead minnows and snails. Aqua- tic Toxicology 3:171-182. 

41315701 Thompson, R.; Williams, T.; Tapp, J. (1989) Permethrin: Determination of 

Chronic Toxicity to Mysid Shrimps (Mysidopsis bahia) (Run 2): Lab Project 

Number BL/B/3574; FT84/88; Study No. S259/A. Unpublished study 

prepared by Imperial Chemical Industries PLC, Brixham Laboratory. 44 p. 

43745701 Kent, S.; Williams, N.; Gillings, E.; et al. (1995) Permethrin: Chronic 

Toxicity to Daphnia magna: Lab Project Number: BL5443/B. Unpublished 

study prepared by Zeneca Brixham Environmental Lab. 51 p. 

92142020 Swigert, J. (1990) ICI Americas Inc. Phase 3 Summary of MRID 00047039. 

Carbon 14-Permethrin - Determination of the Chronic Toxicity to Daphnia 

magna:Report No. 23647. Prepared by ANALYTICAL BIO-CHEMISTRY 

LABS. INC. 13 p. 

92142021 Hill, R. (1990) ICI Americas Inc. Phase 3 Summary of MRID 41315701 and 

Related MRIDs 40102001. Permethrin: Determination of the Chronic 

Toxicity of Active Ingredient to Mysid Shrimp (Mysidopsis bahia) (Run 2): 

Report No. BL/B/3574; Study No. S259/A. Prepared by ICI Brixham Lab. 

10 p. 

92142136 Smyth, D. (1990) ICI Americas Inc. Phase 3 Summary of MRID 40102001 

and Related MRIDs 41315701. Permethrin: Determination of the Chronic 
 114

Toxicity of Active Ingredient to Mysid Shrimp (Mysidopsis bahia) (Run 1): 

Report No. BL/B/2965; Study No. P131/C. Prepared by ICI Brixham Lab. 17 

p. 

102096 E G & G Bionomics (1977) Chronic Toxicity of FMC 33297 to the Fat- head 

Minnow (Pimephales promelas): ACT 092.72. (Unpublished study received 

Jan 27, 1978 under 10182-17; submitted by ICI Americas, Inc., Wilmington, 

DE; CDL:096764-C) 

110662 Doma, S.; Evered, P.; Sealey, C. (1977) PP557: Acute Toxicity and 

Reproduction Studies on First Instar and Ephippia of Daphnia magna: TMJ 

1455B. (Unpublished study received Jan 3, 1978 under 279-3013; prepared 

by Imperial Chemical Industries, Ltd., submitted by FMC Corp., 

Philadelphia, PA; CDL:096699-H) 

 72-5 Life cycle fish 

MRID Citation Reference 

161436 Smith, W. (1986) Letter sent to R. Stewart dated July 17,1986: Pounce data callin fish life-cycle study. Prepared by FMC Corp. 243 p. 

ACC 

263993 

FMC Corp., 1986, Egg to Egg Fulll Life-cycle 

72-7 Simulated or Actual Field Testing 

MRID Citation Reference 

 Cella, G.E. (1980) Final Report, Potential Aquatic Ecological Ef- fects of 

Aerial Applications of Two Permethrin Formulations on Cotton: UCCES 

Study 11507-36. (Unpublished study received Oct 10, 1980 under 279-3014; 

prepared by Union Carbide Corp., Envi- ronmental Services, submitted by 

FMC Corp., Philadelphia, Pa.; CDL:243505-C) 

 Union Carbide Corporation (1980) Potential Aquatic Ecological Effects of 

Aerial Applications of Two Permethrin Formulations on Cotton: UCCES 

Study 11507-36; A-80-474. Final rept. (Un- published study received May 8, 

1981 under 279-EX-79; submitted by FMC Corp., Philadelphia, Pa.; 

CDL:245051-P) 

92142023 Hamer, M. (1990) ICI Americas Inc. Phase 3 Summary of MRID 00042134 

and Related MRIDs 00102097. The Application of Two Permethrin 

Formulations on a Cotton Field Adjacent to an Aquatic Ecosystem. Prepared 

by UNION CARBIDE CORP. ENVIR. SER. 13 p. 

 

141-1 Honey bee acute contact 
 115

MRID Citation Reference 

149694 Gary, N.; Westerdahl, B. (1983) Effects of Three Synthetic Pyre- throids on 

Honey Bees (Apis mellifera L.): Final Report. Un- published study prepared 

by Univ. of California--Davis, Dept. of Entomology. 66 p. 

41047801 Rothpletz, G. (1977) Ambush: Bee Toxicity Study in Alfalfa (Washington): 

Laboratory Project ID TMUD1796/B. Unpublished study prepared by ICI 

Americas, Inc. 6 p. 

42674501 Gough, H.; Jackson, D.; Lewis, G. (1993) Permethrin: Acute Contact and 

Oral Toxicity to Honey Bees (Apis mellifera) of Technical Material: Lab 

Project Number: 92JH166: RJ1344B. Unpublished study prepared by ICI 

Agrochemicals. 27 p. 

45044 Clark, A.M. (1976) Permethrin: Oral and Contact Toxicity to Honey- bees of 

Technical Material and an Encapsulated Emulsion: TMJ 1273 A. 

(Unpublished study received Dec 20, 1976 under 100- EX-53; prepared by 

Plant Protection, Ltd., submitted by Ciba- Geigy Corp., Greensboro, N.C.; 

CDL:095990-B) 

45045 Stanford, R.L.; Atkins, E.L. (1976) Laboratory Studies of Various Pesticides 

on Honeybees: Report No. 22CA75-013. (Unpublished study received Dec 

20, 1976 under 100-EX-53; prepared by ICI United States, Inc., submitted by 

Ciba-Geigy Corp., Greensboro, N.C.; CDL:095990-C) 

45046 Johansen, C.; Mayer, D.; Madsen, R.; et al. (1975) Bee Research 

Investigations, 1975. (Unpublished study received Dec 20, 1976 under 100-

EX-53; prepared by Washington State Univ., submitted by Ciba-Geigy 

Corp., Greensboro, N.C.; CDL:095990-E) 

102103 Smailes, J.; Wilkinson, W. (1977) Permethrin: Toxicity to Honey- bees ... on 

Oilseed Rape: Report Series TMJ 1578B. (Unpublished study received Jan 

27, 1978 under 10182-17; prepared by Imperial Chemical Industries, Ltd., 

Eng., submitted by ICI Americas, Inc., Wilmington, DE; CDL:096765-M) 

141-2 Honey bee residue on foliage 

MRID Citation Reference 

42009301 Lynn, S.; Hoxter, K. (1991) Permethrin Wettable Powder-Ambush 25 W: A 

Foliage Residue Toxicity Study with the Honey Bee: Lab Project Number: 

WIL 123-165. Unpublished study prepared by Wildlife International Ltd. 28 

p. 

142-3 Simulated or Actual Field Testing 
 116

MRID Citation Reference 

9042 Burkhardt, C.C.; Puterka, G.J.; Michels, G.J., Jr. (1977) Impact of 

Insecticides on Beneficial Insects in an Experimental Plot Used to Control 

Alfalfa Weevil, Lygus Bugs, and Pea Aphids on Alfalfa. (Unpublished study 

received Oct 12, 1978 under 352- 342; prepared by Univ. of Wyoming, 

Agricultural Substation, sub- mitted by E.I. du Pont de Nemours & Co., 

Wilmington, Del.; CDL: 236883-C) 

43717 Smith, F.D. (1976) PP557: Effects on Predatory and Parasitic Arthropods: 

Report Series TMJ 1283 B. (Unpublished study re- ceived Dec 2, 1976 under 

10182-EX-3; prepared by Imperial Chemi- cal Industries, Ltd., submitted by 

ICI Americas, Inc., Wilming- ton, Del.; CDL:095996-G) 

77052 Atkins, L. (1981) Field Trials on Cotton and Alfalfa and Foliage Residue 

Trials To Assess Toxicity to Honeybees: Mavrik 2E. Fi- nal rept. 

(Unpublished study received May 13, 1981 under 20954- EX-18; prepared 

by Univ. of California--Riverside, Dept. of Entomology, submitted by 

Zoecon Corp., Palo Alto, Calif.; CDL: 070100-L) 

102105 Smailes, J.; Wilkinson, W. (1977) Permethrin: Toxicity to Honey- bees ... on 

Top Fruit: Report Series TMJ 1577B. (Unpublished study received Jan 27, 

1978 under 10182-17; prepared by Imperial Chemical Industries, Ltd., Eng., 

ICI Americas, Inc., Wilmington, DE; CDL:096765-O) 

127368 Harris, C.; Turnbull, S. (1978) Laboratory studies on the contact toxicity and 

activity in soil of four pyrethroid insecticides. Canadian Entomologist 

110(Mar):285-288. (Submitter AW-81-0099; also In unpublished submission 

received Apr 8, 1983 under 39398- 16; submitted by Sumitomo Chemical 

America, Inc., New York, NY; CDL:249939-B) 

5008360 Hoy, M.A.; Flaherty, D.; Peacock, W.; Culver, D. (1979) Vineyard and 

laboratory evaluations of methomyl, dimethoate, and permethrin for a grape 

pest management program in the San Joaquin Valley of California. Journal 

of Economic Entomology 72(2):250-255. 

 

 
 117

Appendix A. PRD Data Request Justification Tables 

The following proposed Data Call-In tables include rationales for requiring the data requested in 

this problem formulation, explanations of the utility of the data, and explanations for how the 

data might impact risk assessment, following the format provided by PRD. 

Guideline Number: Non-guideline 

Study Title: Leachability from Treated Wood 

Rationale for Requiring the Data 

A study is required for certain chemicals that are employed to treat wood and that are 

used outdoors. It should be conducted according to the American Wood Preservers 

Association Standard Method of Determining the Leachability of Wood Preservatives 

(E11-06). It is suggested that the registrant provide a protocol to be evaluated by the 

Agency prior to performing the study. 

Practical Utility of the Data 

How will the data be used? 

Permethrin is a synthetic pyrethroid with high toxicity towards aquatic organisms, 

including those living in the benthos. It is used for wood protection treatment to forest 

products and building/ products outdoors. The results of this study will be used in the 

ecological risk characterization, and in particular, for aquatic assessments. At the present 

time, based on the binding capacity of this chemical to soil organic carbon, and its high 

octanol/ water partition coefficient, EFED believes that permethrin binds strongly to the 

wood material to which it is applied, but there are uncertainties as to the degree to which 

this occurs. Knowledge of the leachability from treated wood for this chemical is 

important. 

In addition, the data will be used to derive the equivalent application rate to be used in the 

aquatic models GENEEC2 and PRZM/ EXAMS. The results from these models are used 

for exposure assessment (i.e., to derive estimated environmental exposure concentrations 

or EECs), ecological risk estimation, and ultimately in risk assessment. 

How could the data impact the Agency’s future decision-making? 

Without these data, the Agency would have to make certain conservative assumptions 

(e.g., assume that 100% of the permethrin leaches instantly from the treated wood, to 

estimate the equivalent application rate in GENEEC and PRZM/ EXAMS). These 

conservative assumptions could lead to higher predicted environmental exposure 

concentrations (EECs), according to the models, and consequently, higher risk quotients. 

The application rate input parameter has a major effect in the determination of the aquatic 

EECs and RQs. Also, there would be a higher degree of uncertainty in the overall 

transport assessment for ecological effects. Knowledge of the leachability from treated 

wood of this chemical in detail is essential to perform a better and accurate environmental 

fate/ transport and risk assessment. 
 118

Guideline Number: Non-guideline 

Study Title: Leachability from Treated Wood 

The lack of these data will limit the flexibility the Agency and registrants have in coming 

into compliance with the Endangered Species Act and could result in use restrictions for 

this chemical that may be unnecessary. 

Guideline Number: Non-guideline 

Study Title: POTW Treatability Study

Rationale for Requiring the Data 

POTW Treatability Study – The Agency has recently requested and provided 

comments on a protocol developed by the Pyrethroid Working Group (PWG) for a bench 

scale study of waste water treatment, to assess the percentage removed in the biosolids by 

the treatment, the amount that would degrade during treatment, and the amount that 

would remain in the waste water. These data would be used to inform removal 

percentages by waste water treatment, which is an input to the Exposure and Fate 

Assessment Screening Tool’s (E-FAST) “down-the-drain” module. The Office of 

Pesticide Programs will continue to confer with the Office of Water with the goal of 

refining our down-the-drain assessment for registration review. It is the responsibility of 

the registrant to ensure that permethrin is included in the study completed by the PWG or 

conduct a similar study on its own (following submission of a protocol for review). 

Practical Utility of the Data 

How will the data be used? 

These data would be used to inform removal percentages by waste water treatment, 

which is an input to the Exposure and Fate Assessment Screening Tool’s (E-FAST) 

“down-the-drain” module. This model will yield aquatic estimated environmental 

exposure concentrations (EECs), which will be used to derive risk quotients (RQs); the 

results of the model are used in the ecological risk assessment of permethrin. 

How could the data impact the Agency’s future decision-making? 

Without these data, the Agency will have to make assumptions regarding the level of 

removal of permethrin (e.g., use modeling results from EPIWEB v.4.0). These 

assumptions are likely to be crude and conservative. The lack of these data will limit the 

flexibility the Agency and registrants have in coming into compliance with the 

Endangered Species Act, and could result in use restrictions for permethrin which may 

otherwise be avoided, or which are unnecessarily severe. 
 119

Guideline Numbers and Study Titles: 

 Test Method 100.4 (OCSPP 850.1770, in prep.); Whole sediment: chronic 

invertebrates freshwater (Hyalella azteca) 

 Test Method 100.5 (OCSPP 850.1760, in prep.); Whole sediment: chronic 

invertebrates freshwater (Chironomus dilutus) US EPA 2001, 

 EPA 600/R-01/020 (OCSPP 850.1780, in prep.); Whole sediment: chronic 

invertebrates marine (Leptocheirus plumulosus) 

Rationale for Requiring the Data 

No chronic sediment toxicity tests for freshwater or marine invertebrates have been 

submitted to satisfy the Agency’s updated data requirements for outdoor uses in 40 CFR 

Part 158 (October 26, 2007). For permethrin, available information indicates that benthic 

organisms may be exposed via run-off or spray drift applications used in agricultural, 

forest, and residential settings. Based on calculations in the most recent EFED 

assessment for permethrin where estimated sediment concentrations were calculated, the 

peak sediment porewater EECs predicted for permethrin ranged from 0.00364 ppm for 

barrier treatment to 1.62 ppb for nursery-pine seed orchard-high rate (US EPA 2008a). 

The upper end of this range exceeds 0.1 of the most sensitive acute LC/EC50 (0.0212 μg 

a.i./L for the amphipod Hyallela azteca), which satisfies one of the criteria for requiring 

chronic whole sediment toxicity testing under 40 CFR Part 158. Chronic reproductive 

effects were also seen in other aquatic invertebrate taxa (daphnids and mysids), although 

at higher levels than acute effects were observed for amphipods. 

Permethrin has a long expected half-life in sediment, based on submitted soil metabolism 

and aquatic metabolism studies (aerobic soil, 37 days; anaerobic soil, 204 days; aerobic 

aquatic metabolism, 38.2-42.9 days; anaerobic aquatic metabolism, 113-175 days) 

(MRIDs 42410002, 41970601, 43938201 and 43982001). These half-life values are 

substantially greater than 40 CFR Part 158 criterion of 10 days. The potential for 

persistent exposure from permethrin in sediment is also indicated by open literature 

studies on pyrethroids (Weston et al., 2004; Holmes et al., 2008; Weston and Lydy, 

2010; Lao et al., 2010; Ding et al., 2009). 

The third set of trigger criteria for requiring chronic testing (Kd > 50 or log KOW >3 or 

KOC > 1000) is also met for permethrin (Kd ranges from 140-401, log KOW is 6.1, and 

KOC values range from 19,300 to 60,900). The physicochemical property triggers (Kd, 

KOW and KOC) reflect the propensity of the chemical to partition onto the particulate or 

organic matter phases of sediments. Exceeding any one of the physicochemical property 

triggers listed above is sufficient for indicating the pesticide has reasonable potential for 

partitioning to the sediment compartment. 

For sediment studies involving pyrethroids, chronic whole sediment tests on Hyalella 

azteca, Chironomus tentans, and Leptocheirus plumulosus are requested. Although both 

are freshwater species, Hyalella and Chironomus differ substantially in their ecological 

niche (i.e., epibenthic v. infaunal species), physiology. Evidence in open literature 

suggests that Hyalella azteca is among the most sensitive aquatic invertebrates to 

permethrin based on acute water column tests (Weston and Lydy, 2010; Brander et al., 
 120

2009). Permethrin has the potential to enter estuarine/marine water bodies based on 

current usuage patterns that include coastal areas. Therefore, testing is also required for 

an estuarine/marine sediment-dwelling invertebrate species. 

Until the final OCSPP guidelines for chronic sediment toxicity tests are published, the 

registrant should submit a protocol to EFED for approval prior to test initiation. 

 Test Method 100.4: Hyalella azteca 42-d Test for Measuring the Effects of 

Sediment Associated Contaminants on Survival, Growth, and Reproduction in 

USEPA 2000 Methods for Measuring the Toxicity and Bioaccumulation of 

Sediment-associated Contaminants with Freshwater Invertebrates EPA 600/R99/064 (OCSPP 850.1770, in prep.); 

 Test Method 100.5: Life-cycle Test for Measuring the Effects of Sedimentassociated Contaminants on Chironomus dilutus (formerly known as C. tentans) 

in USEPA 2000 Methods for Measuring the Toxicity and Bioaccumulation of 

Sediment-associated Contaminants with Freshwater Invertebrates EPA 600/R99/064 (OCSPP 850.1760, in prep.); and 

 Leptocheirus plumulosus in USEPA 2001 Method for Assessing the Chronic 

Toxicity of Marine and Estuarine Sediment-associated Contaminants with the 

Amphipod Leptocheirus plumulosus EPA 600/R-01/020 (OCSPP 850.1780, in 

prep.). 

Practical Utility of the Data 

How will the data be used? 

Data from sediment toxicity studies will be used to estimate potential risks to benthic 

organisms associated with uses of permethrin. The data will reduce uncertainties 

associated with the current risk assessment for benthic species and will improve our 

understanding of the potential effects of permethrin. 

How could the data impact the Agency’s future decision-making? 

Although there was uncertainty in estimating the effect of permethrin on benthic 

organisms in previous assessments, there was a potential risk associated with adverse 

effects identified for other aquatic organisms. Acceptable data for benthic organisms will 

reduce the uncertainty from the previous assessment If the data indicates that registered 

permethrin usage may pose a risk of adverse effects to non-target benthic organisms 

above the Agency Level of Concern, the Agency may explore decision options to 

mitigate this risk. The lack of these data will limit the flexibility the Agency and 

registrants have in coming into compliance with the Endangered Species Act, and could 

result in use restrictions which may otherwise be avoided, or which are unnecessarily 

severe. 

 
 121

Appendix B. Summaries of the Reported Permethrin Ecological Incidents in the 

EIIS Database 

Table D-1. Permethrin Incident Reports Involving Aquatic Organisms 

Incident # Organism(s) Affected Certainty of 

Involvement 

Legality of 

Use Description 

I001849-002 Unknown fish Highly probable Registered 

use 

A commercial pesticide applicator 

treated a building with permethrin. 

The next night, a heavy rain caused 

runoff of permethrin to a nearby 

private pond, killing approximately 

300 fish. Louisiana, 4/6/1994. 

I016338-006 Bullhead (Ameiurus sp.), 

flathead minnow 

(Pimephales promelas), and 

rainbow trout 

(Onchorhynchus mykiss) 

Highly probable Registered 

use 

Multiple buildings were sprayed with 

permethrin and bifenthrin, with 

around 100 gallons of pesticides used 

combined. After application, a storm 

carried the pesticides to a nearby 

holding pond and killed hundreds of 

bullheads, flathead minnows, and 

rainbow trout. The pond water 

contained 0.098 - 3.40 ppb bifenthrin 

and 99.8 ppb permethrin. Trout fillets 

contained 34.4 ppb bifenthrin and 406 

ppb permethrin. New York, 5/2/2005. 

I005761-001 Unknown fish Highly probable Unknown A rancher sprayed 120 cattle with 

permethrin and removed the livestock 

from the vicinity of the nearby pond 

for several hours. After the cattle 

returned to the pond, an undetermined 

number of fish died. Iowa, 8/5/1997. 

I001849-003 Unknown fish Highly probable Registered 

use 

Permethrin and terbufos were applied 

to approximately 3,769 acres of corn 

fields, prior to planting. Heavy storms 

during the next month created heavy 

runoff and subsequent death of an 

estimated 1386 fish. The LSU School 

of Veterinary Medicine attributed the 

fishkill to both permethrin and 

terbufos (no data shown). Louisiana, 

4/12/1994. 

I004374-003 Catfish (Ictaluridae) and 

sunfish (Centrarchidae) 

Highly probable Accidental 

misuse 

A fishkill occurred after a home was 

treated with permethrin. The pesticide 

equipment was rinsed in a manner that 

resulted in runoff to a nearby pond. 

Rain occurring after the treatment also 

contributed to runoff. Thousands of 

catfish and sunfish were killed. 

Missouri, 6/10/1995. 

I003402-005 Crayfish (Decapoda) Highly probable Registered 

use 

Permethrin was applied to a residence 

for termite control. A heavy rain 

washed the pesticide into a stream, 

and thousands of dead crayfish were 

found 1-1.5 miles downstream. Soil 

samples taken underneath the house 

contained 46.0 ppm permethrin and 
 122

Table D-1. Permethrin Incident Reports Involving Aquatic Organisms 

Incident # Organism(s) Affected Certainty of 

Involvement 

Legality of 

Use Description 

soil near the drainpipe contained 0.554 

ppm permethrin. Permethrin was not 

detected in water samples, but 

sampling did not occur until two days 

after the incident. Virginia, 

11/14/1995. 

I003653-001 Bass (Centrarchidae spp.), 

carp (Cyprinus carpio) and 

catfish (Ictaluridae spp.) 

Highly probable Registered 

use 

The basement floor and walls of a 

home were treated with permethrin to 

control for termites. A snowstorm 

occurred after the treatment, and the 

following snowmelt washed the 

pesticide into a nearby lake. Tissue 

samples for bass, carp and catfish 

contained 3.27, 3.7 and 3.7 ppm 

permethrin, respectively. 

Pennsylvania, 3/3/1996. 

I004439-038 Unknown fish Highly probable Accidental 

misuse 

A fishkill of unknown magnitude 

occurred in a backyard pond, after the 

lawn was treated with permethrin. 

Massachusetts, 6/20/1996. 

I009136-001 Crayfish (Decapoda) Highly probable Registered 

use 

Heavy rains carried permethrin from a 

residence to a nearby stream. Dead 

crayfish were found one-third of a 

mile away from the home. Soil 

samples contained 10.0 ppb 

permethrin, while water samples had 

no detectable levels of the pesticide. 

Virginia, 4/13/1998. 

I006022-001 Rockfish (Sebastes sp.) Probable Accidental 

misuse 

A state mosquito control truck sprayed 

permethrin within 10 feet of a 

commercial fish pond, killing 3000 

rockfish. Maryland, 6/16/1997. 

I000598-022 Black bullhead catfish 

(Ictalurus melas) and 

bluegill (Lepomis 

macrochirus) 

Probable Accidental 

misuse 

After aerial spraying of permethrin in 

a nearby cornfield, an estimated 500 

fish were killed in a nearby pond. Ten 

days after the accident occurred, 

samples were taken from the water, 

soil and sediment of the pond. 

Residues were below detection levels. 

Nebraska, 7/5/1992. 

I000124-014 Bluegill (Lepomis 

macrochirus) 

Probable Accidental 

misuse 

Treatment of home with permethrin 

entered house sump pump and 

emptied into fish pond, killing an 

unknown number of bluegill. Illinois, 

3/31/1992. 

I001028-010 Unknown fish Probable Registered 

use 

During a light rain, a home and 

outside deck were treated with 

permethrin. The runoff drained into a 

nearby canal, where dead fish were 

later discovered. The species and 

number of fish killed were not 

reported. Florida, 8/1/1993. 

I006261-001 Crayfish (Decapoda) and Probable Accidental After permethrin termiticide 
 123

Table D-1. Permethrin Incident Reports Involving Aquatic Organisms 

Incident # Organism(s) Affected Certainty of 

Involvement 

Legality of 

Use Description 

rainbow trout 

(Onchorhynchus mykiss) 

misuse application to a home, around 230 

dead crayfish and 50 dead rainbow 

trout were reported in a creek 160 feet 

away from the residence. Soil samples 

indicated permethrin levels between 

17.0 – 53.0 ppb. Virginia, 4/16/1997. 

I007226-001 Bass (Centrarchidae sp.) and 

bream 

Probable Registered 

use 

Permethrin was applied within the city 

limits of Greenville, Mississippi for 

vector control. Three days after the 

application, fifteen bass and two 

bream were found dead in a lake. 

Mississippi, 9/2/1998. 

I003582-010 Unknown fish Probable Unknown An unknown number of fish were 

killed as a result of permethrin 

contamination in a stream. 

Pennsylvania, 3/5/1996. 

I003582-042 Unknown fish Probable Unknown Runoff from permethrin treatment 

spray killed fish in a downhill pond. 

Indiana, 5/6/1996. 

I004439-039 Unknown fish Probable Registered 

use 

A home was treated for termites with 

permethrin, and a fishkill of unknown 

magnitude occurred in a pond 20 feet 

away. Tennessee, 6/21/1996. 

I014689-015 Bluegill (Lepomis 

macrochirus) and catfish 

(Ictaluridae) 

Probable Misuse Permethrin was applied 400 feet away 

from a pond. Eight bluegill and 

seventy-two catfish were found dead. 

No further information on treatment 

site or method of application. Indiana, 

5/7/2003. 

I003826-030 Unknown fish Possible Registered 

use 

A fish kill occurred in a commercial 

fish pond. The owner attributed the 

problem to pesticide drift from nearby 

corn and soybean fields. After 

conducting tests for a range of 

pesticides, the NC Department of 

Agriculture stated that pesticides 

could not be determined as the cause 

of the fish kill. However, permethrin 

was found in the soil (0.41 ppm) and 

vegetation (1.4 ppm) of the area. Total 

magnitude of the fish kill was not 

reported. North Carolina, 6/14/1994. 

B000175-

001 

Unknown fish Possible Registered 

use 

Three pesticides (paraquat, permethrin 

and bicep) and fertilizer were applied 

to a corn field. A fishkill in a nearby 

pond occurred after a heavy storm. 

The incident was attributed to the 

fertilizer and low dissolved oxygen, 

but permethrin may be another 

contributing factor due to its high 

toxicity to fish. Kentucky, 1992. 

I004439-121 Unknown fish Possible Unknown A lawn was treated with permethrin. 

After an unspecified time, an 
 124

Table D-1. Permethrin Incident Reports Involving Aquatic Organisms 

Incident # Organism(s) Affected Certainty of 

Involvement 

Legality of 

Use Description 

unknown number of fish located in a 

nearby pond died. New Jersey, 

9/9/1996. 

I004439-119 Unknown fish Possible Unknown A home exterior, 210 feet from a 

pond, was treated with permethrin. 

Four days later, a fish kill was 

observed. Virginia, 9/21/1996. 

I007984-003 Striped bass (Morone 

saxatilis), crayfish 

(Decapoda) and unknown 

frogs 

Possible Accidental 

misuse 

An employee of the Mosquito Control 

section of the Maryland Department 

of Agriculture applied permethrin to a 

residential property. One day later, 

600 fish, crayfish and frogs were 

found dead. The spraying was 74 feet 

away from the pond, while regulations 

require 100 feet. Pond water sampled 

a few days after the incident showed 

low dissolved oxygen. Maryland, 

6/16/1997. 

I014312-001 Goldfish (Carassius 

auratus) 

Possible Registered 

use 

Permethrin was applied to a lawn, and 

runoff caused by rains resulted in an 

estimated 40 – 60 goldfish deaths in a 

proximate pond. Kansas, 4/1/2003. 

I008293-001 

Velvet swords (Xiphophorus 

helleri), oscars (Astronotus 

ocellatus) and discus 

(Symphysodon sp.) 

Possible Registered 

use 

Drift from four pesticides (including 

permethrin) applied to tomato fields 

may have caused a fishkill in ponds 

100 yards away. The species include 

several ornamental fish, including 

velvet swords, oscars, and discus. The 

applicator was observed lifting booms 

at row ends without ceasing spray 

flow. Oily residue was found at pond 

edges, and the ponds contained low 

dissolved oxygen. Dying fish 

exhibited tremors symptomatic of 

pyrethroid or organophosphate 

exposure. Florida, 12/1/1998. 

Table D-2. Permethrin Incident Reports Involving Terrestrial Plant Species 

Incident # Organism(s) Affected Certainty of 

Involvement 

Legality of 

Use Description 

I007340-620 Unknown edible crop Possible Unknown Damage occurred to an edible crop as 

a result of permethrin use. Florida, 

4/22/1998. 

I010927-003 Alfalfa (Medicago sativa) Possible Registered 

use 

An alfalfa field had been previously 

treated with permethrin and 

chlorpyrifos, and damaged occurred 

due to carryover. Both pesticides are 

believed to have contributed to the 

damage. Wisconsin, 4/15/1999. 

I012515-002 Unknown tropical plants Possible Unknown Tropical plants were treated with 

permethrin and piperonyl butoxide. 
 125

Table D-2. Permethrin Incident Reports Involving Terrestrial Plant Species 

Incident # Organism(s) Affected Certainty of 

Involvement 

Legality of 

Use Description 

Plants exhibited burn spots, yellowing 

leaves and defoliation. Plants may 

have been suffering from nutrient 

deficiency, which may have 

compromised the waxy cuticle and 

made the plants more vulnerable to 

exposure. Unknown location, 

8/13/2001. 

I019442-001 Clover (Trifolium sp.), 

timothy-grass (Phleum 

pretense) and unknown 

grasses and legumes 

Possible Intentional 

misuse 

Pesticide application to a right-of-way 

possibly caused chlorosis as far as 200 

feet away in an adjacent hay and 

pasture field. Pesticides involved 

include permethrin, 2,4-D, acetochlor, 

atrazine, glyphosate, metribuzin and 

clomazone. Plant tissue samples from 

the right-of-way contained 9.85 ppm 

of Pendimethalin. None of the 

aforementioned chemicals were 

detected in samples from the hay and 

pasture field. The observed whitening 

of the vegetation is symptomatic of 

clomazone damage, but other 

herbicides present may have 

contributed. Ohio, 7/19/2007. 

I009544-001 Soybean (Glycine max) Possible Unknown A farmer attributes the reduced 

productivity of 142 acres of soybeans 

to permethrin and carboxin 

application. The pesticides are 

believed to have killed the Rhizobium

bacteria in the soil inoculate added at 

the time of planting. The soybeans 

showed stunted growth and a light 

yellow color indicative of nitrogen 

deficiency. Wisconsin, 7/10/1999. 

I015105-005 Unknown nursery trees, 

ornamentals and birds 

Possible Unknown Drift from permethrin, atrazine, 

glyphosate and S-metolachlor 

caused the deaths of three birds and 

damage to trees and ornamentals in 

a nursery. The report did not 

specify which active ingredient 

may have caused the damage. 

Tennessee, 4/27/2004. 

I016138-001 Cauliflower (Brassica 

oleracea) 

Unlikely Registered 

use 

Aerial spraying of pesticides 

damages 70 acres of cauliflower, to 

the extent that the crop is claimed 

to be unfit for human consumption. 

Owner of field claims that the 

mixture of insecticides used was 

“contaminated and adulterated with 

herbicides”. Pesticides involved 
 126

include permethrin, indoxacarb and 

imazethapyr. Imazethapyr is toxic 

to cauliflower and not registered 

for use on this crop, but no 

evidence was presented to show 

that the herbicide was actually 

sprayed in this instance. California, 

10/11/2004. 

I000340-007 Unknown lawn plants Unlikely Unknown Permethrin was applied near a 

residence, and browning of lawn 

plants was reported. However, 

permethrin is not known to cause 

plant damage, and it is unlikely to 

be the cause of the observed 

browning. Florida, 10/7/1992. 

Table D-3. Permethrin Incident Reports Involving Terrestrial Animal Species 

Incident # Organism(s) Affected Certainty of 

Involvement 

Legality of 

Use Description 

I011527-001 Monarch butterfly 

(Danaus plexippus) and 

unknown butterfly 

(Lepidoptera) 

Highly probable Registered 

use 

A municipality was sprayed with 

permethrin and piperonyl butoxide. 

Several hours after application, 

residents began noticing hundreds to 

thousands of dead butterflies (mostly 

monarch). Analysis showed 20 – 37 

ppm permethrin in butterfly samples. 

Minnesota, 8/23/2000. 

I003826-028 Bee (Apidae) Highly probable Accidental 

misuse 

Bee keepers report bee kills in hives 

and attribute the damage to aerial 

application of pesticide to a nearby 

soybean field. A certified aerial 

applicator treated 400 acres of soybean 

fields. Permethrin was found in nearby 

vegetation samples in concentrations 

ranging from 0.32 – 4.1 ppb. The 

applicator paid an $1800 fine to the 

North Carolina Department of 

Agriculture for misuse. North 

Carolina, 8/30/1994. 

I020998-040 Bee (Apidae) Highly probable Intentional 

misuse 

The Washington State Department of 

Agriculture reports that bee mortality 

occurred, caused by permethrin. 

Beekeepers suspect that the hives were 

deliberately sprayed to kill bees. No 

residue data was available. 

Washington, 6/20/2003. 

I004852-015 Parakeet (Psittacidae) Possible Unknown A residence was treated with 

permethrin and four days later, four 

parakeets died. No analytical evidence 

was reported. Oklahoma, 10/29/1996. 

I000340-006 Dog (Canis Familiaris) Possible Unknown A dog was treated with permethrin and 

cypermethrin. The dog then became ill 
 127

Table D-3. Permethrin Incident Reports Involving Terrestrial Animal Species 

Incident # Organism(s) Affected Certainty of 

Involvement 

Legality of 

Use Description 

and incapacitated. Both pyrethroids are 

known toxicants to animals. New 

York, 12/3/1992. 

I016728-007 Unknown butterfly 

(Lepidoptera) 

Probable Unknown Pinellas County Mosquito Control 

received a report of one to two dozen 

commercially-raised butterflies 

following community-wide spraying 

with Biomist 31+66 ULV with active 

ingredients permethrin and piperonyl 

butoxide. Adult and caterpillar 

mortality occurred in a colony 

maintained by a local butterfly 

hobbyist. Florida, 4/1/2005. 

I012515-004 Bee (Apidae) Possible Unknown Apiary damage possibly caused by 

permethrin and piperonyl butoxide. No 

information available on method of 

application or suspected misuse. 

Mississippi, 5/9/2001. 

I015105-005 Unknown nursery trees, 

ornamentals and birds 

Possible Unknown Drift from permethrin, atrazine, 

glyphosate and S-metolachlor caused 

the deaths of three birds and damage to 

trees and ornamentals in a nursery. 

The report did not specify which active 

ingredient may have caused the 

damage. Tennessee, 4/27/2004.