(freshwater and estuarine/marine) on an acute basis. No data were available to access 

toxicity or risk to plant species. 

The major uncertainty in the environmental fate database is the difference between the 

results in laboratory studies and in the field. There is also uncertainty with respect to the 

aquatic metabolism of fenpropathrin. Uncertainties also exist concerning the potential for 

adverse aquatic effects, including organisms living in the benthos, for acute, chronic and 

endangered species risk based on fate transport involving drift and run-off, and 

persistence. There is uncertainty concerning the potential for adverse terrestrial effects 

for acute and endangered species risk to terrestrial organisms based on fate transport, 

drift, binding to the soil and persistence. In addition, there are ecological data gaps that 

need to be addressed which increase uncertainties in the risk picture for fenpropathrin. 

2
Environmental Fate and Ecological Risk 

Assessment Problem Formulation in 

Support of Registration Review 

for Fenpropathrin 

June 16, 2010 

Environmental Fate and Effects Division 

Office of Pesticide Programs 

US Environmental Protection Agency 

3
Prepared by: 

N.E. Federoff, Wildlife Biologist 

José L. Meléndez, Chemist 

Secondary Review: 

Amanda Solliday, Biologist 

Keith Sappington, Senior Scientist 

Branch Chief 

Mah T. Shamim, Ph.D. 

Environmental Risk Branch V 

4
Table of Contents 

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

2. Problem Formulation .............................................................................................................. 6 

2.1 Nature of Regulatory Action................................................................................................ 6 

2.2. Previous Risk Assessments.................................................................................................. 7 

3. Stressor Source and Distribution .......................................................................................... 10 

3.1. Mechanism of Action........................................................................................................ 12 

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

3.3. Environmental Fate and Transport.................................................................................... 18 

 3.4. Literature Search............................................................................................................... 18

4. Receptors............................................................................................................................... 31 

4.1. Aquatic and Terrestrial Effects......................................................................................... 31 

4.2. Incident Database Review................................................................................................. 22 

4.3. Ecosystems Potentially at Risk ......................................................................................... 35 

6. Conceptual Model.............................................................................................................. 36 

6.1. Risk Hypothesis............................................................................................................... 37 

6.2. Conceptual Diagram ........................................................................................................ 37 

7. Analysis Plan ..................................................................................................................... 40 

7.1. Stressors of Concern ......................................................................................................... 41 

7.2. Measures of Exposure....................................................................................................... 41 

7.3. Measures of Effect ............................................................................................................ 43 

7.4. Integration of Exposure and Effects ................................................................................. 44 

7.5. Deterministic and Probabilistic Assessment Methods...................................................... 44 

7.6. Endangered Species Assessments..................................................................................... 44 

7.7. Drinking Water Assessment ............................................................................................. 45 

7.8. Preliminary Identification of Data Gaps........................................................................... 46 

7.8.1. Fate............................................................................................................................. 46 

7.8.2 Effects......................................................................................................................... 51 

8. References................................................................................................................................ 57

9. Bibliography........................................................................................ 

Appendix A. PRD data request justification tables .................................................................... 73 

5
1. Purpose 

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

risk assessment being conducted for the registered uses of fenpropathrin. 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 (EPA, 

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 fenpropathrin. 

Fenpropathrin is a synthetic pyrethroid insecticide that is registered for a variety of 

agricultural and non-agricultural uses, including head & stem brassica, citrus, cotton, 

cucurbit & fruiting vegetables, grapes, peanut, tree nut, stone & pome fruits, strawberries, 

bushberries, caneberries, currant, peas, olives, barley, tropical fruits, agricultural 

uncultivated areas, deciduous fruit trees, forest trees, ornamental and/ or shade trees, 

ornamental herbaceous plants, ornamental non-flowering plants, and ornamental woody 

shrubs and vines. 

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 fenpropathrin. Previous risk assessments 

were completed for the uses of the chemical, which serve as the basis for this assessment. 

The Food Quality Protection Act 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 fenpropathrin 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. 

 6
2.2. Previous Risk Assessments, Scientific Advisory Panels and Background 

Previous Assessments 

In 2008, EFED issued a risk assessment for the Section 3 registration of the new uses of 

fenpropathrin on bushberries, caneberries (Subgroup 13A), olives, currant, peas, fruiting 

vegetables, stone fruit, tree nuts and pistachio, certain tropical fruits, and barley (DP 

Barcode 301100+). Single application rates ranged from 0.2 to 0.4 lb a.i./A and seasonal 

application rates were 0.2 to 0.8 lb a.i./A/season. Prior to the assessment, the uses for 

fenpropathrin included cotton, grapes, peanuts, pome fruits, citrus, and strawberries, 

among others. The ecological risk assessment indicated chronic risk to birds and 

mammals, and acute and chronic risk to fish and aquatic invertebrates. In addition, the 

risk quotients (RQs) exceeded the levels of concern (LOCs) for endangered species, 

including chronic RQs for birds and mammals, and acute and chronic RQs for aquatic 

organisms that live in the water columns, and organisms living in the benthos. Due to the 

fact that birds are considered surrogates for reptiles and terrestrial phase amphibians and 

fish are surrogates for aquatic phase amphibians, the same risks were assumed for nonendangered and listed reptiles and amphibians. The risk profile was based on available 

ecotoxicity data and predicted environmental exposures. Fenpropathrin is toxic to bees, 

therefore, risk to beneficial insects was assumed. Toxicity to honeybees from residues on 

foliage suggested that fenpropathrin is toxic and produces high mortality to non-target 

insects. 

In the assessment, it was also concluded that fenpropathrin is resistant to degradation in 

biotic and abiotic processes, but exhibited variable persistence under field conditions. It 

had low mobility (hardly mobile, FAO 2000), and leaching was not expected. Also, 

based on its vapor pressure and Henry’s Law Constant, volatilization was not considered 

important. Fenpropathrin and its major degradate, CONH2-fenpropathrin were 

considered likely to remain in the upper layers of the soil, but they could reach surface 

waters bound to soil particles during rain events accompanied by erosion. Due to its high 

level of binding, fenpropathrin would generally remain bound to the sediment for 

prolonged periods of time and would be available by slow dissolution into the water 

column. Organisms that live near or in the sediments were considered to be particularly 

at risk. 

Prior to that assessment, in 1999, the EFED issued an incremental risk assessment for the 

use of fenpropathrin on apples, pears, citrus fruits, grapes, cucurbits & melons, and head 

& stem brassica (DP Barcode D257858+). The risk assessment was based on a previous 

1996 review. Five issues were stressed in the review. First, it was stated that there was a 

potential for acute and chronic toxicity to freshwater and estuarine/ marine fish and 

aquatic invertebrates. RQs exceeded the LOCs for all aquatic organisms. Due to its 

potential to move to surface waters, and its binding tendency to soils/ sediments, 

fenpropathrin could also pose adverse effects to benthic organisms. Secondly, minimal 

acute risk to avian species was expected, but there may be chronic risk. Third, similar 

conclusions were reached for mammalian species (low acute risk, but with the possibility 

of chronic risk). Fourth, honeybees, exposed to fenpropathrin could be adversely 

impacted from the proposed use of the chemical. And, finally, endangered birds and 

 7
mammals could show chronic effects and endangered freshwater and estuarine/ marine 

organisms could be also at acute and chronic risk. 

In the 1996 review, for the use of fenpropathrin on pears, apples, citrus and grapes (DP 

Barcode D223864), EFED concluded the following: "The proposed uses of 

fenpropathrin should pose very minimal acute risks to avian and mammalian species. 

However, these uses may present chronic risks to endangered and non-endangered birds 

and mammals. Also, there is a high potential that freshwater and estuarine/ marine fish 

and invertebrates and beneficial insects may be significantly adversely impacted from 

acute and chronic exposures of fenpropathrin applied by ground spray equipment. In 

addition, endangered species can be jeopardized by acute and chronic exposure to the 

chemical. Alterations in aquatic invertebrate populations at any time could affect certain 

fish life stages, as well as birds that rely on this food base." 

In addition to the registered uses, there are new uses pending registration at the time this 

problem formulation is written that may also need to be re-evaluated. The uses are as 

follows: additional tropical and subtropical fruits (like guava, acerola, feijoa, jaboticaba, 

passion fruit, starfruit, wax jambu, lychee, longan, Spanish lime, pulasan, rambutan, 

sugar apple, atemoya, biriba, cherimoya, custard apple, ilama, soursop). 

1999 Scientific Advisory Panel 

A 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 fenpropathrin)” (USEPA, 1999). Although this 

agreement was made in 1999, the new CFR Part 158 requirements include sediment 

toxicity tests and these studies are considered particularly important for ecological risk 

assessment of all synthetic pyrethroids, including fenpropathrin. 

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 nonrepresentative soils and sediments as sorbents, and improper methods used to measure 

organic carbon. 

 8
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 and Hyalella 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. 

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

the following studies on four synthetic pyrethroids (that did not include fenpropathrin) 

(memorandum dated 12/22/93, Rexrode & Meléndez 1993): 850.1735: Acute Sediment 

(freshwater), conducted for 10 days with Hyalella azteca and Chironomus dilutus, 

endpoint is survival; EPA/600/R-99/064: Chronic Freshwater Sediment Testing 

conducted for 65 days on Chironomus dilutus (survival, growth rate and reproduction (# 

eggs/ female, time to oviposition, proportion of females ovipositing, % hatch); and 

EPA/600/R01/020: Chronic Estuarine/ Marine Sediment Testing conducted for 28 days 

on Leptocheirus plumulosus (percentage of neonates that survive as adults, growth rate, 

reproduction (#eggs/ female, etc.) and behavior. 

2009 Scientific Advisory Panel

OPP’s Health Effects Division (HED) 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.1

 This mechanism of action assessment was performed 

by HED to determine if a cumulative assessment is required for the synthetic pyrethroids; 

however, the EFED does not conduct cumulative assessments. Fenpropathrin is usually 

considered a Type II synthetic pyrethroid because it is cyano substituted in the alpha 

position. 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. 

Open Literature Information 

There are multiple articles in the open literature that indicate concern for fenpropathrin 

and other synthetic pyrethroids’ toxicity towards benthic and other non-target aquatic 

organisms. Also, the articles illustrate fenpropathrin’s prevalence in the environment. 

Please, refer to Section 3.4 for further details. 

Aquatic Life Criteria and Aquatic Life Benchmarks 

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

reflect the latest scientific knowledge on the kind 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. An Aquatic Life Ambient Water Quality Criteria 

 

1

 See Page 18 of the SAP meeting minutes (USEPA 2009). 

 9
document has not been published for fenpropathrin (refer to url: 

http://www.epa.gov/waterscience/criteria/). 

Based on toxicity values revised by the EPA, the OPP publishes aquatic life benchmarks 

for freshwater species, based on the most sensitive species from the most recent risk 

assessments. For fenpropathrin, no aquatic life benchmarks have been published (see url: 

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

Impaired Water Bodies 

Fenpropathrin is not 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_grou

p_id=885. However, the pyrethroids as a group have been identified as a cause for 

impairment for three water bodies in Central Valley, CA: Del Puerto Creek, Ingram 

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

Creek Site (confluence with San Joaquin River to confluence with Hospital Creek). 

Nonetheless, no Total Maximum Daily Load (TMDL) criteria have been developed for 

fenpropathrin, based on information provided at the following url: 

http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_gr

oup_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 this pesticide. To the extent possible, data 

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

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

Registration Review Risk Assessment and Management Process (refer to: 

http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1-sop.pdf), in order to 

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

3. Stressor Source and Distribution

Fenpropathrin (Table 3.1) is a synthetic pyrethroid insecticide and acaricide. Its structure 

has three rings, two phenyl rings attached to each other by an oxygen atom, and a 

cyclopropyl ring. It is a Type II synthetic pyrethroid (it is cyano-substituted in the alpha 

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

be expected to hydrolyze as the pH increases; this is confirmed by the hydrolysis study 

results. The structure of the molecule has one chiral center that could result in 2 

stereoisomers. Chemically, it is the racemic mixture of both stereoisomers. 

Fenpropathrin is 2,2,3,3-tetramethyl substituted in the cyclopropyl ring. 

A summary of physicochemical properties of fenpropathrin is included in Table 3.1. 

Table 3.1. Summary of physicochemical properties of fenpropathrin.

PARAMETER VALUE(S) (units) SOURCE

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

tetramethylcyclopropanecarboxylate 

Fenpropathrin data sheet: 

http://www.alanwood.net/pe

 10
Table 3.1. Summary of physicochemical properties of fenpropathrin.

PARAMETER VALUE(S) (units) SOURCE

IUPAC Chemical Name (RS)-α-cyano-3-phenoxybenzyl 2,2,3,3-

tetramethylcyclopropanecarboxylate 

sticides/fenpropathrin.html 

accessed 01/05/10 

PC Code 127901 OPP Databases 

Chemical Structure 

(from chemical’s data 

sheet) 

CAS Reg. No. 64257-84-7 Laskowski, 2002 

Molecular Weight 349.4 Laskowski, 2002 

Appearance Yellowish brown liquid or solid 

with faint characteristic odor 

Melting Point 25-50oC 

Boiling Point 377oC 

Fenpropathrin Chemical 

Fact Sheet Available at 

http://pmep.cce.cornell.edu/

profiles/insectmite/fenitrothionmethylpara/fenpropathrin/in

sect-proffenpropathrin.html 

Solubility (25oC) 1.03x10-2 ppm or 0.0103 ppm or 10.3 ppb 

‘Not Soluble’ according to FAO solubility classification. 

Laskowski, 2002 

FAO, 2000 

Vapor Pressure (25oC) 1.39 x 10-8 mmHg (by extrapolation) 

‘Not volatile under field conditions.’ 

Laskowski, 2002 

USEPA, 2008 

Henry’s Law Constant 6.2 x 10-7 atm-m3

/mol 

(from vapor pressure and water solubility) Laskowski, 2002 

Octanol-Water Partition 

Coefficient 

(log KOW and KOW) 

6.00 and 1.00 x 106 Laskowski, 2002 

Octanol-Air Partition 

Coefficient 

KOA (log KOA) 

Constant Law sHenry'

RTK

K

K

K OW

AW

OW

OA == = 3.9 x 1010 (10.6) vs.

3.19 x 109

 (9.505) 

Calculated Value vs. 

EPISuite v.4.0 Estimate 

Cwater/Cair 

⎟

⎠

⎞ ⎜

⎝

⎛

××

××× = 6

air

water

10GMW P

760RT S

C

C = 38,752 (unitless) 

‘Slightly volatile from a water surface.’ 

Calculated 

USEPA, 2008 

OH Radical Reaction 

Half-life 0.599 days EPISuite 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 fenpropathrin, log KOA> 5, log KOW>2 

and rate of transformation appears to be 

relatively low in the environment and 

moderate in fish; it appears that 

fenpropathrin has a potential to biomagnify 

in terrestrial food chains. 

**Gobas et al. 2003 

and Armitage & 

Gobas, 2007 support 

this presumption 

utilized here only as 

a broad reference to 

determine the 

potential for 

biomagnification. 

Fenpropathrin has a moderately high molecular weight of 349.4 g/mol. It shows a small 

solubility (0.0103 ppm) and a high octanol/ water partition coefficient (KOW = 1.00x106). 

Based on it octanol/water partition coefficient, it appears that fenpropathrin has the 

 11
potential to bioaccumulate/ bioconcentrate. With a relatively low vapor pressure (1.39 x 

10-8 mmHg), combined with its solubility, its calculated Henry’s Law Constant is 

relatively low (6.2 x 10-7 atm-m3/mol). In addition, its Cwater/Cair is 38,752, which 

classifies it at “slightly volatile from a water surface” (USEPA 2008). The potential to 

volatilize for fenpropathrin may be attenuated by its tendency to bind to organic matter 

(e.g., soils, sediments or organic matter in the water). For fenpropathrin, the log KOA is 

9.5 to 10.6 (EPISuite v.4.0 estimate to calculated), the log KOW is 6.00 and the rate of 

transformation appears to be low in the environment and moderate in fish; it appears that 

fenpropathrin could have a potential to biomagnify in terrestrial food chains, based on the 

presumption made by Gobas et al. and Armitage & Gobas in articles published in 2003 

and 2007, respectively (refer to Table 3.1). Even though EFED has not adopted an 

official reference or guideline to distinguish chemicals that biomagnify, Gobas et al. and 

Armitage & Gobas’ presumption was utilized here as a general or broad reference to 

detect the potential for biomagnification in terrestrial food chains. 

Even though various degradates were observed in the laboratory studies (e.g. 3-PBA and 

TMPA), it was found that they were the result of the rupture of the ester bond of the 

parent molecule. It is believed that the resulting molecules are not as toxic as the parent 

because they presumably have lost the neurotoxic mode of action. Furthermore, some 

other degradates were observed in certain laboratory studies at concentrations exceeding 

10% of the applied. Table 3.2 shows the chemical structures of fenpropathrin’s 

degradation products. At this time, they may be considered stressors. 

Table 3.2. Major Transformation Products of Fenpropathrin 

Common 

Name Chemical Name Structure 

m-PBA, mPBAc, 3-PBA 

or PBA 

3-phenoxybenzoic acid 

(CAS No. 3739-38-6) 

O

OH

O

TMPA 2,2,3,3-tetramethylcyclopropane 

carboxylic acid 

OH

CH3

CH3

CH3

CH3

O

Desphenylfenpropathrin 

(RS)-α-cyano-3-hydroxybenzyl 

2,2,3,3-tetramethylcyclopropane 

carboxylate 

(CAS No. 96475-59-1) 

OH

O

CH3

CH3

CH3

CH3

O

N

 12
Table 3.2. Major Transformation Products of Fenpropathrin 

Common 

Name Chemical Name Structure 

4’OHfenpropathrin 

α-cyano-3-(4-hydroxy 

phenoxy)benzyl 2,2,3,3-

tetramethylcyclopropane 

carboxylate 

(CAS No. 66280-02-2)

O

O

N

CH3

CH3

CH3

CH3

O

OH

COOHfenpropathrin 

α-carboxy-3-phenoxybenzyl2,2,3,3-tetramethylcyclopropane 

carboxylate

O

O

CH3

CH3

CH3

CH3

O

O

OH

CONH2-

fenpropathrin 

α-carbamoyl-3-phenoxybenzyl 

2,2,3,3-tetramethylcyclopropane 

carboxylate

O

O

CH3

CH3

CH3

CH3

O

O

2NH

3.1. Mechanism of Action 

Fenpropathrin is a neural toxic insecticide acting through direct contact and ingestion. 

The pyrethroids (including fenpropathrin) share similar modes of action, and are 

considered axonic poisons that affect both the peripheral and central nervous system. 

The insecticidal effect of pyrethroids is characterized by a rapid “knock down,” or 

paralysis, of insects. The primary biological effects of fenpropathrin and other 

pyrethroids 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+ (calcium ion) channels coupled with a stimulatory effect on the 

voltage-gated Na+ (sodium ion) channels. It is now well established that severe 

neurological symptoms of poisoning with pyrethroids in mammals and insects are the 

result of modification of the Na+

 channels activity (cellular pores through which Na+ ions 

are permitted to enter the axon to cause excitation) (Matsumura, 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 

 13
hyperactivity of the nervous system. This action leads to spontaneous depolarizations, 

augmented neurotransmitter secretion rate and neuromuscular block, which ultimately 

results in paralysis of the insect. 

Pyrethroids have also been shown to suppress GABA and glutamate receptor-channel 

complexes and voltage-activated Ca2+ channels, but the toxicological significance of 

these actions is uncertain. Relative to physiological responses, researchers have 

designated two types of pyrethroids, Type I (e.g., bifenthrin, resmethrin, permethrin) and 

Type II (e.g., fenpropathrin, cypermethrin, deltamethrin, fenvalerate). Type I pyrethroids 

action is mainly associated with compounds that cause nerve excitation symptoms 

typified by the appearance of repetitive firing of axons in the peripheral nervous system 

and a negatively correlated temperature reversible knockdown property (Clark and 

Matsumura, 1987). Fenpropathrin is classified as a type II synthetic pyrethroid, with a 

cyano group at the α-carbon position of the alcohol moiety, and is more light-stable and 

persistent in the environment than early pyrethroids like allethrin, phenothrin (also 

commonly known as sumithrin) and resmethrin. Fenpropathrin has one optically active 

center and is composed of 2 isomers, and like all pyrethroids, is a contact poison that can 

quickly penetrate the nervous system and have an effective “knockdown” action 

(induction of temporary paralysis) for most flying insects. 

3.2. Overview of Pesticide Usage

Fenpropathrin has numerous uses. A summary of agricultural use patterns for 

fenpropathrin, based on the label for DANITOL® 2.4 EC Spray, is shown in Table 3.3. 

Table 3.3. Summary use information for fenpropathrin agricultural uses, based on label for 

DANITOL® 2.4 EC Spray (Reg. No. 59639-35). 

USE 

SINGLE 

APP. 

RATE 

(lbs. a.i./A) 

NUMBER 

OF APPS.

SEASONAL 

APP. RATE 

(lbs. a.i./A) 

INTERVAL 

BETWEEN 

APPS. (days) 

APP. 

METHOD 

PREHARVEST 

INTERVAL 

(days) 

Head and stem brassica (broccoli, brussel 

sprouts, cabbage, cauliflower, cavalo 

broccolo, Chinese broccoli-gal lon, Chinese 

cabbage-napa, Chinese mustard cabbage-gal 

choy, Kohlrabi, Brussels sprouts, 

cauliflower)

0.2-0.3 3-4 0.8 7 G, A 7 

Citrus 0.2-0.4 2-4 0.8 10 G, Airblast, A 1 

Cotton 0.15-0.3 3-5 0.8 7 G, A 21 

Cucurbits (balsam apple, balsam pear, 

bitter melon, chayote, Chinese cucumber, 

Chinese waxgourd, citron melon, cucumber, 

edible gourd, gherkin, honeydew, 

Momordica spp., muskmelon, pumpkin, 

summer squash, watermelon, winter squash) 

0.2-0.3 3-4 0.8 7 G, A 7 

 14
Table 3.3. Summary use information for fenpropathrin agricultural uses, based on label for 

DANITOL® 2.4 EC Spray (Reg. No. 59639-35). 

SINGLE PRESEASONAL INTERVAL 

USE 

APP. HARVEST 

RATE NUMBER 

(lbs. a.i./A) OF APPS.

APP. RATE 

(lbs. a.i./A) 

BETWEEN APP. INTERVAL 

APPS. (days) METHOD (days) 

Fruiting vegetables (bell pepper, chili 

pepper, cooking pepper, eggplant, ground 

cherry-Physalis spp., pepino, pimento, sweet 

pepper, tomatillo, tomato) 

0.15-0.2 4-5 0.8 7 G, A 3 

Grape 0.1-0.4 2-8 0.8 7 G, A 21 

Peanut 0.1-0.3 3-8 0.8 7 G, A 14 

Pome fruit (apple, crabapple, loquat, 

mayhaw, quince, oriental pear, pear) 

0.2-0.4 2-4 0.8 10 Airblast 14 

Strawberry 0.2-0.4 2-4 0.8 30 G 2 

Pea (English pea, garden pea, green pea, 

pigeon pea)

0.2 4 0.8 7 G, A 7 

Currant 0.2-0.3 3 0.8 7 G 21 

Bushberries (blueberry-highbush and 

lowbush, elderberry, gooseberry, 

huckleberry, juneberry, lingonberry, 

rabbiteye, salal) 

0.2-0.3 2 0.6 14 G, A 3 

Caneberries (blackberry-including 

bingleberry, boysenberry, dewberry, 

lowberry, marionberry, olallieberry and 

youngberry; loganberry; black raspberry; 

red raspberry) 

0.2-0.3 2 0.6 14 G, A 3 

Olive 0.2-0.3 3-4 0.8 14 G 7 

Stone fruits (such as apricot, cherry, 

nectarine, peach, plum and prune)

0.2-0.4 2-4 0.8 10 Airblast 14 

Tree nut (such as almond, beechnut, 

cashew, chestnut, chinquapin, filbert 

(hazelnut), hickory, macadamia, pecan, 

pistachio, walnut)

0.2-0.4 2-4 0.8 10 Airblast 14 

Barley 0.2 1 0.2 N/A G 14 

Tropical and subtropical fruits (inedible 

peel, including but not limited to avocado, 

canistel, mango, papaya, sapodilla, black 

and mamey sapote, star apple)

0.3-0.4 2 0.8 14 G 1 

In addition to the uses listed in the table, new uses pending registration at the time this problem formulation is written may also need to 

be re-evaluated. The uses are as follows: additional tropical and subtropical fruits (guava, acerola, feijoa, jaboticaba, passion fruit, starfruit, 

wax jambu, lychee, longan, Spanish lime, pulasan, rambutan, sugar apple, atemoya, biriba, cherimoya, custard apple, ilama, soursop), the application 

parameters are the same than for the tropical fruits listed in the row above. 

DANITOL® 2.4EC is an emulsifiable concentrate. The chemical may be applied by 

 15
ground or aerial methods. The uses are for treatment of crops at the rate of 0.1-0.4 lb 

a.i./A/application to be applied at a maximum of 8 times per year at 7-14 day intervals 

with a maximum of 0.2-0.8 lb ai/A/season. The labels for fenpropathrin require a buffer 

zone of 10 ft within certain bodies of water, such as lakes, reservoirs, rivers, permanent 

streams, marshes or natural ponds, estuaries and commercial fish farm ponds, so as to 

allow growth of a maintained vegetative filter strip. The agricultural products should not 

be applied by ground equipment within 25 ft, by aerial equipment within 150 ft, or by 

ULV within 450 ft of freshwater or estuarine/ marine bodies of water. 

The usage of fenpropathrin, from the Screening Level Usage Analysis (SLUA) is 

provided in Table 3.4. The table is arranged in alphabetical order of crops. According to 

the table, the major agricultural uses for fenpropathrin are apples, grapes and oranges, 

followed by strawberries, tomatoes and cotton, in that order. For apples and strawberries, 

the average percent crop treated are the highest, with 10 and 25%, respectively, while for 

other crops, the average percent crop treated is ≤5%. The highest maximum percent crop 

treated is for strawberries (50%), followed by oranges (30%), and grapes and pears (with 

20%). 

Table 3.4. Screening-Level Estimates of Agricultural Uses of Fenpropathrin (SLUA, 

dated 08/07/09). 

Percent Crop Treated 

Crop lb a.i. Avg. Max. 

Apples 20,000 10 15 

Asparagus + <500 <1 <2.5 

Broccoli <500 <1 <2.5 

Cabbage <500 <1 <2.5 

Cantaloupes <500 <2.5 10 

Cauliflower <500 <1 <2.5 

Cherries <500 <1 <2.5 

Cotton 4,000 <1 <2.5 

Cucumbers <500 <1 <2.5 

Grapefruit 2,000 5 20 

Grapes 20,000 5 10 

Lemons <500 <1 <2.5 

Oranges 20,000 5 30 

Peanuts 1,000 <1 <2.5 

Pears 2,000 5 20 

Peppers 2,000 5 10 

Pumpkins <500 <1 <2.5 

Squash <500 <1 <2.5 

Strawberries 7,000 25 50 

Tomatoes 3,000 5 10 

Watermelons <500 <1 <2.5 

 16
Table 3.4. Screening-Level Estimates of Agricultural Uses of Fenpropathrin (SLUA, 

dated 08/07/09). 

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. The 

sources of the SLUA include the USDA-NASS, Private Pesticide Market Research, the 

National Pesticide Use Database (NPUD 2002) of the CropLife America Foundation and 

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

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

The U.S. Geological Survey (USGS) pesticide use maps (Fig. 3.1) show regional scale 

patterns in use intensity within the United States. 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 USGS map, the crops of highest use for fenpropathrin were apples, 

grapes and cotton in 2002 (12,961-18,572 lb applied nationwide). These crops were 

followed in importance by citrus fruits, strawberries, peanuts, tomatoes, and pears (2,104-

6,711 lb applied nationwide). It is noted that there are potential estuarine/ marine areas 

of concern in the East and West coast as well as the Gulf. As expected, there is a general 

agreement between the SLUA and the USGS map. The map shows a generalized use of 

fenpropathrin for agricultural purposes throughout the country, with highest uses in the 

east and west coasts, and the Midwest. The map also shows the potential for use in areas 

near estuarine/ marine environments. Multiple agricultural uses are approved for the 

chemical, other than the ones in the map, as indicated above in the Table 3.2. 

 17
Fig. 3.1. Estimated Use of Fenpropathrin 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. 

In addition to the classical agricultural use sites, fenpropathrin has various other uses. 

These uses include food/feed use sites, non-food/ non-feed use sites and greenhouses. 

Examples of these uses include agricultural uncultivated areas, deciduous fruit trees, 

forest trees, ornamental and/ or shade trees, ornamental herbaceous plants, ornamental 

non-flowering plants, and ornamental woody shrubs and vines. Table 3.5 provides a 

summary of the terrestrial nonagricultural uses for fenpropathrin. Application methods 

vary. Many of these uses could involve substantive exposure to wildlife, specifically, 

aquatic organisms, and they will be assessed accordingly. The greenhouse uses are not 

assessed. 

 18
Table 3.5. Nonagricultural Uses for Fenpropathrin 

Use Max. App. Rate/ units

Max. No. 

Apps./ 

Year 

Max. App. 

Rate per 

Year 

Min. App. 

Int./ days 

agricultural uncultivated areas 0.4 lb a.i./A NS 0.8 lb a.i./A NS 

deciduous fruit trees (unspecified) 0.3 lb a.i./A; 0.0069 lb 1K sq.ft NS NS 7 

forest trees (softwoods, conifers) 0.3 lb a.i./A NS NS 7 

ornamental and/or shade trees 0.3 lb a.i./A; 0.0055 lb 1K sq.ft NS NS NS or 2 

ornamental herbaceous plants 0.3 lb a.i./A; 0.0055 lb 1K sq.ft NS NS NS or 2 or 7 

ornamental nonflowering plants 0.3 lb a.i./A; 0.0055 lb 1K sq.ft NS NS NS or 2 or 7 

ornamental woody shrubs and vines 0.3 lb a.i./A; 0.0055 lb 1K sq.ft NS NS NS or 2 or 7 

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

According to the agricultural label for fenpropathrin (i.e. for DANITOL® 2.4 EC 

Insecticide/ Miticide, EPA Reg. No. 59639-35), the product mixes readily with water and 

can be tank mixed with Orthene® 90 S (a product which contains the active ingredient 

acephate, an insecticide for use on cotton only, Reg. No. 5481-8974). There are two 

coformulated products of fenpropathrin with other active ingredients. One product is 

coformulated with acephate (Reg. No. 499-441), and it is for indoor uses only on 

ornamental plants in commercial greenhouses. The spray drift associated with this indoor 

use will be minimal. The other product (named V-10141 2.8EC) is coformulated with 

etoxazole (Reg. No. 59639-137), for certain outdoor uses (apples, cotton, pears and 

strawberries).

Toxicity data on environmental mixtures of fenpropathrin with other pesticides may be 

presented, if available, as part of the ecological risk assessment. It is expected that the 

toxic effect of fenpropathrin, 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 

fenpropathrin 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 qualitative 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. 

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

certain pyrethroids. 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 piperonyl butoxicide 

increases the toxicity of the pyrethroids (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). 

The Agency routinely assesses potential exposure to formulations by examining acute 

exposure due to spray drift. Acute toxicity data on the formulation is compared to 

potential exposure to spray drift. There are no fenpropathrin registration products that 

 19
contain PBO or MGK-264. However, piperonyl butoxide and/or MGK-264 from other 

pyrethroid applications (e.g. the application of an adulticide containing PBO), could 

interact with fenpropathrin in the environment. Therefore, potential interactions will be 

discussed qualitatively in the risk assessment. 

3.3. Environmental Fate and Transport 

A summary of environmental fate/ transport properties of fenpropathrin is included in 

Table 3.6. 

Table 3.6. Summary of environmental fate/ transport properties of fenpropathrin. 

PARAMETER VALUE(S) (units) SOURCE (MRID) COMMENT 

Hydrolysis Half-life 

[pH 5, 7, 9; (25 oC)] 

Relatively stable at pHs 6-8 & 25oC; 

vs. pH 5 and pH 7 stable 

pH 9 14.3-17.1 days 

131438, 141320, 

42599901 

*Half-lives reported by Laskowski 

2002: relatively stable at pH 5 and 7, 

and 13.8 days at pH 9. 

Aqueous Photolysis 

Half-life 

Stable (buffer contained 8% 

acetonitrile). Samples exposed to 

sunlight in CA. 

43917227 Limited supplemental data (MRID 

137769): 16.2 weeks (~113 days) in 

distilled water containing an 

emulsifier (PBA, TMPA and 

decarboxy-fenpropathrin were 

major). 2-7 weeks in natural river 

and sea waters fortified with 1 ppm 

humic acid. 1.6 days in 2% acetone 

solution. *Half lives reported by 

Laskowski 2002: in unbuffered 

solution, in the presence of an 

emulsifier 14.6 and 87.5 days. 

Soil Photolysis Halflife 

Relatively stable in SL (≤10% 

degradation in 30 days; samples 

were irradiated with natural sunlight 

in CA) 

137769, 42546402 In a supplemental study, 3.8-10.3 

days in irradiated samples vs. 36.6-

155 days in dark controls (light clay, 

SL & SCL). CONH2-fenpropathrin 

observed in both irradiated and dark 

control samples. Samples were 

irradiated with natural sunlight. 

*Half-lives reported by Laskowski 

2002: 3.77, 9.16, 9.42 days in air dry 

soil correspond, presumably, to the 

same study listed above. 

 20
Table 3.6. Summary of environmental fate/ transport properties of fenpropathrin. 

PARAMETER VALUE(S) (units) SOURCE (MRID) COMMENT 

Aerobic Soil 

Metabolism Half-life 

152 days (SiL) 42525902 33-35 days (light clay), 34-39 days 

(SCL) from MRIDs 126823, 

130869, 142547, provide limited 

supplemental data. 

Sakata et al. 1990 11 and 17 days 

for SCL and light clay from Japan. 

Half-lives reported by Li et al. 2009: 

15.3-16.2 in alkaline loam and 31.1 

in acidic loam (soils from China). 

See notes below in Section 3.4). 

*Half-lives reported by Laskowski 

2002: 34.1, 32.1, 34.8, 36.5, 39.4, 

133, 34.7, 51.3, 221, 186 days for 

SCL, C, SCL, C, SL, C, SL, SC, SC, 

L, respectively. 

Anaerobic Soil 

Metabolism Half-life 

186 days (L) 

Soil was incubated in aerobic 

condition for 30 days and made 

anaerobic for 2 months. 

42546403 Akhtar et al. 2004 relatively 

persistent in a Pakistan soil. 

*Half-lives reported by Laskowski 

2002: 283 & 383 days for C & SCL, 

respectively. 

Aerobic Aquatic 

Metabolism Half-life 

Not available N/A Half-lives reported by Gan et al.

2008: 89 and 152, from two 

sediments (see notes below in 

Section 3.4) 

Anaerobic Aquatic 

Metabolism Half-life 

78 and 67 days in CA loam; 

formation of PBA and TMPA (data 

screened and currently in review). 

44370003, 

44370004 

*Half-lives reported by Laskowski 

2002: 93.4, 85, 57.8 days for L, L, 

SL, respectively. 

Adsorption/ 

Desorption - Batch 

Equilibrium 

Soil Partition 

Coefficient 

(Kd & KOC) 

Soil Type Kd KOC

sandy loam 267 33746 

silt loam 810 85263 

clay loam 266 23340 

loam 64 13870 

aq. sediment 779 34453 

Measurements made at a single 

concentration; test solutions 

contained 0.2% v/v acetonitrile. 

Screened data from an update/ 

upgrade of the study (currently in 

review), shows the following 

Freundlich adsorption coefficients: 

Soil Type KF KFOC

sandy loam 184 23300 

silt loam 486 51100 

clay loam 252 22100 

loam 212 46200 

aq. sediment 662 29300 

42584101, 

44370002 

5x105 – mean of two sediments 

(reported by Gan et al. 2008, 

refer to Section 3.4). 

Terrestrial Field 

Dissipation 

144 days WA (apples) 

8 days NY (apples) 

14 days CA (grapes) 

95 days MS (cotton) 

17 days CA (bare) 

41679601, 

41525905, 

41525904, 

42311401, 

42311402 

– 

 21
Table 3.6. Summary of environmental fate/ transport properties of fenpropathrin. 

PARAMETER VALUE(S) (units) SOURCE (MRID) COMMENT 

Bioaccumulation in 

Fish (BCF) 

200x, 830x, 1400x for fillet, whole 

fish and viscera, respectively. 

65 and 5% depurated after 3 days, 

for viscera and fillet respectively. 

By day 21, 78-84% of the residues 

had been eliminated from fillet. 

00153802, 

00161672, 

00161673, 

00163521 

Residues were characterized as 42-

81% parent; also present were 3-

PBA, 3-(4-hydroxyphenoxy) 

benzoic acid, TMPA, α-cyano-3-

phenoxybenzyl 2-hydroxymethyl2,3,3-trimethylcyclopropane 

carboxylate, 2-carboxy-2,3,3-

trimethylcyclo propanecarboxylic 

acid & 2-hydroxymethyl-2,3,3-

trimethylcyclopropanecarboxylic 

acid. [Study 161773 screened only.]

Studies conducted on fenpropathrin indicate that it is mostly persistent under laboratory 

conditions but degrades with varying rates under field conditions. Fenpropathrin is stable 

to hydrolysis at lower pHs but undergoes degradation in alkaline media. It appears to be 

stable to aqueous and soil photolysis conditions and degrades slowly under both aerobic 

and anaerobic soil metabolism conditions. Field studies show varying degradation rates 

and relatively low mobility of the chemical in soil. Fenpropathrin shows very low 

mobility in soils. Based on the available data, the major routes of dissipation for 

fenpropathrin are likely microbial degradation and soil binding. New laboratory studies 

requested in this document, in particular, the photolysis and aerobic soil metabolism 

studies, will shed more light on the possible routes of dissipation for the chemical. 

Fenpropathrin can be spray applied by ground or aerially on agricultural settings. A 

buffer region is label recommended (e.g. 150 ft. for aerial applications that do not use 

ULV); however, under a high end drift scenario (e.g. small droplets and/ or high wind 

speed), substantial amounts of the chemical can reach adjacent bodies of water via spray 

drift. Substantial fractions of the chemical may be available in the soils once it is applied 

for the first few weeks to several months after application. Due to its low solubility (10.3 

ppb) and high level of binding (KOC values were 13900 to 85300) it appears that 

fenpropathrin would remain bound to the soils during run-off events and it may reach 

surface waters if the run-off event is accompanied by erosion. Once fenpropathrin 

reaches surface waters, the fate of the chemical is of concern since fenpropathrin is very 

toxic to fish. EFED believes that fenpropathrin, due to its high level of binding, would 

generally remain bound to the sediment for prolonged periods of time and will be 

available by slow dissolution into the water column. Organisms that live near or in the 

sediments may be particularly at risk. 

Fenpropathrin has low mobility, and is not likely to reach subsurface soil environments 

(with lower microbial activity) or ground waters. Five terrestrial field dissipation studies 

confirm that fenpropathrin and its degradate CONH2-fenpropathrin remain in the upper 

soil level. 

Degradation and Metabolism

Fenpropathrin was stable to hydrolysis in pH 5 and 7 aqueous solutions, but degraded at 

pH 9 with half-lives of 14.3-17.1 days. Four degradates were present in the pH 9 

 22
solution: TMPA comprised 39.4-42.8% of the applied at 21-30 days; CONH2–

fenpropathrin was ≤8.9% of the applied at all test intervals; TMPA-carboxamide was 8.8-

13.3% of the applied at 15-30 days; and PBA reached a maximum of 61.2-63.5% of the 

applied at 30 days. 

Fenpropathrin did not degrade under aqueous photolysis conditions and was relatively 

stable under soil photolysis condition. No major metabolites were identified in the 

aqueous photolysis study. The metabolite identified in the photolysis on soil study in the 

irradiated and dark control was CONH2–fenpropathrin at 5.9 and 10.9%, respectively. 

Fenpropathrin degraded slowly under both aerobic and anaerobic soil metabolism 

conditions, with calculated half-lives of 152 and 186 days, respectively. In the aerobic 

soil metabolism study the major degradate was carbon dioxide, which was 59.9% of the 

applied after one year. Several minor metabolites were identified (refer to table below). 

In the anaerobic soil metabolism study, the major metabolites were PBA and COOH–

fenpropathrin (both at ≤11.5% of the applied). 

Based on the submitted data, most of the laboratory studies indicate that fenpropathrin is 

highly persistent. In the case of hydrolysis, only under alkaline conditions, two major 

degradates – TMPA, and PBA – were formed at a maximum of 42.6% and 63.5% of the 

applied, respectively, in a period of 30 days. These degradates were not only persistent, 

but appear to be highly mobile in the soil due to the presence of a carboxylic acid moiety. 

However, both these degradates were not monitored in any of the terrestrial field 

dissipation studies. 

Although the degradation of fenpropathrin could follow a number of parallel degradation 

pathways, it appears more likely that the major route of dissipation is microbial 

dissipation in soil. Aerobic and anaerobic soil metabolism studies indicate that 

fenpropathrin is resistant to microbial degradation; however, a closer look at the two 

studies reveals that the dose rate in both studies exceeded the solubility of the chemical 

(10.3 ppb, see Laskowsky 2002); there is a strong possibility that this could have 

precipitated the chemical on the soil which would have erroneously led to the conclusion 

that the chemical was stable. The same appears to be true for the photodegradation on 

soil study. Additional aerobic soil metabolism and anaerobic soil metabolism studies 

would provide more reliable data that could help in defining the major route of 

dissipation of fenpropathrin in the field. EFED believes that these studies will shed more 

light on the significance of these degradation processes and more clearly define the major 

route of dissipation of fenpropathrin in the environment. 

Transport and Mobility 

Supplemental data from an Adsorption/ Desorption (batch equilibrium) study indicate 

that fenpropathrin was adsorbed strongly to soils and was hardly mobile in silt loam 

sediment, sandy loam, silt loam, and clay loam soils (FAO mobility classification). The 

adsorption Kd values were 64-810, and the KOC values were 13870-85260 (measured at 

the highest concentration only, which constitutes an uncertainty). The registrant 

submitted additional data to upgrade this study (MRID# 44370002). These results have 

 23
not been fully reviewed, but they were screened and found to be reviewable. The 

additional data supports the conclusion that fenpropathrin is strongly adsorbed to soils 

and is not expected to leach substantially. Results are as follows: 

Table 3.7. Freundlich Adsorption and Desorption Constants for Fenpropathrin 

Soil Type %OC KF (adsorption) KFOC (adsorption) KF (desorption) KFOC (desorption) 

sandy loam 0.79 184 23300 314 39700 

silt loam 0.95 486 51100 283 29800 

clay loam 1.14 252 22100 278 24400 

loam 0.46 212 46200 381 82800 

aquatic sediment 2.26 662 29300 912 40400 

Fenpropathrin is relatively insoluble in water (reported solubility 10 ppb) and nonvolatile (vapor pressure 1.39x10-8 mmHg). It Henry’s Law Constant is relatively low 

(6.2 x 10-7 atm-m3/mol). The chemical is unlikely to volatilize substantially. The rate of 

volatilization is further attenuated by the high adsorption that the chemical shows to soils, 

sediment and organic matter. 

Bioaccumulation in Fish

Fenpropathrin residues accumulated in bluegill sunfish, with bioconcentration factors of 

200x, 830x, and 1400x in fillet, whole fish and viscera, respectively. Accumulated 

residues depurated rapidly from the viscera, but relatively slowly from the fillet (65 and 

5% depurated after 3 days, respectively). 

In the tissue, [14C]-residues were 42-81% fenpropathrin, 3.6-6.5% α-cyano-3-

phenoxybenzyl-2-hydroxymethyl-2,3,3-trimethylcyclo-propanecarboxylate, 0.9-13.4% 

PBA, 0.8-7.8% 3-(4-hydroxyphenoxy)benzoic acid, 2.9-15.4% TMPA, 2.2-12.6% 2-

carboxy-2,3,3-trimethylcyclopropanecarboxylic acid, and 0.3-2.5% 2-hydroxymethyl2,3,3-trimethylcyclopropanecarboxylic acid. 

Field Dissipation

Results from five terrestrial field dissipation studies conducted in Washington, California, 

New York and Mississippi showed that fenpropathrin remains in the upper layers of soil 

(upper 7.5 or 15 cm). However, reported half-lives showed a wide range from 8 to 144 

days. The registrant has provided no valid reason for the differences in the persistence of 

fenpropathrin under laboratory and field conditions or between similar terrestrial field 

dissipation studies. Detailed comparison of two apple orchard studies conducted in 

Washington and New York did not provide conclusive evidence for the differences in 

reported half-lives. The different half-lives for the field dissipation studies might be due 

to different environmental conditions that affect dissipation or degradation mechanisms 

such as soil photolysis or aerobic soil metabolism. 

Although the major route of dissipation of fenpropathrin in the field remained 

unidentified, terrestrial field dissipation studies indicate that fenpropathrin dissipates at 

moderate rates in the field; fairly quickly in some instances (half-lives 8, 14 and 17 days, 

for studies conducted on cropped apple orchard, grapes and bareground, respectively) and 

more slowly in other instances (95 and 144 days in two other studies, on cotton and 

 24
apples, respectively). The observed differences in the rate of dissipation of fenpropathrin 

in the field could be due to a number of variables such as geographical location, climatic 

conditions, and microbial population of the soil at different test sites; these variables 

affect the dissipation processes (such as photolysis, microbial degradation, and 

irreversible binding to the soil) some or all of which could be involved in the dissipation 

of the chemical in the field. 

The data from the field studies clearly indicate that fenpropathrin and its degradate 

CONH2-fenpropathrin are likely to remain in the upper layers of the soil and show no 

potential to leach in ground waters due to their high adsorption and low mobility in soil. 

However, residues of fenpropathrin and its major degradate may reach surface waters 

bound to soil particles during rain events accompanied by erosion. 

Degradate Formation

Table 3.8 is a summary of degradate formation for fenpropathrin. Note that, despite the 

fact that fenpropathrin is persistent under various conditions, or dissipates very slowly in 

all studies, various transformation products comprised ≥10% of the applied. 

Table 3.8. Summary of degradate formation from degradation of fenpropathrin. 

STUDY TYPE SOURCE DEGRADATE and MAXIMUM CONCENTRATION 

DEG1 (% applied) DEG2 (% applied) DEG3 (% applied) 

Hydrolysis 131438, 141320, 

42599901 

At pH 9, PBA at a maximum of 63.5% at 30 days; CONH2-

fenpropathrin, was ≤12.6% of the applied at all test intervals. 

TMPA-carboxamide increased to 8.8-13.3% of the applied at 

15-30 days. 

Aqueous 

Photolysis 

43917227 NO aqueous photolysis product exceeded 10% of the applied 

during the study. Unidentified [14C] compounds totaled ≤4.4% 

of the applied in all solutions at all sampling intervals. 

Soil Photolysis 137769, 42546402 CONH2-fenpropathrin was a maximum of 5.6 and 10.9% of the 

applied. 

Aerobic Soil 

Metabolism 

126823, 130869, 

142547, 42525902 

PBA (maximum 1.25% of the applied), CONH2-fenpropathrin 

(0.21%), desphenylfenpropathrin (0.55%), and 4'-OHfenpropathrin (0.039%). 

Anaerobic Soil 

Metabolism 

42546403 PB-acid to 11.5% by day 60 postflooding; COOH-fenpropathrin 

increased to 6.36% at 60 days postflooding; 4'-OHfenpropathrin comprised ≤0.35% through the study; and, 

CONH2-fenpropathrin was ≤0.67% during the anaerobic phase.

Aerobic Aquatic 

Metabolism 

N/A Not available 

Anaerobic Aquatic 

Metabolism 

44370003, 

44370004 (screened 

and in review) 

Based on screened data, TMPA and PBA are the major 

degradates. 

 25
Table 3.8. Summary of degradate formation from degradation of fenpropathrin. 

STUDY TYPE SOURCE DEGRADATE and MAXIMUM CONCENTRATION 

DEG1 (% applied) DEG2 (% applied) DEG3 (% applied) 

Terrestrial Field 

Dissipation 

41679601, 

41525905, 

41525904, 

42311401, 

42311402 

4’-OH-fenpropathrin, CONH2-fenpropathrin and desphenylfenpropathrin detected in certain studies. 

Degradation products observed in the laboratory studies or in the field included 4’-OHfenpropathrin, CONH2-fenpropathrin and desphenyl-fenpropathrin (which preserve the 

basic structure profile of the parent molecule (the ester bond), and PBA and TMPA, 

which are the product of rupture of the ester bond. 

Uncertainties

The major uncertainties with respect to the environmental fate studies on fenpropathrin 

are related to the extremely low solubility of fenpropathrin and the problems found when 

the registrant performed these studies. The aqueous photolysis study was performed in 

unusually high concentrations of acetonitrile. However, no substantial photolysis was 

observed. The cosolvent may have had an effect on the results. Furthermore, the batch 

equilibrium studies were performed at a single concentration (a Freundlich isotherm was 

not developed). EFED has had to rely on single point results. An additional source of 

uncertainty is the absence of aerobic and anaerobic (only one soil available) aquatic 

metabolism studies. The persistence of fenpropathrin in aquatic environments is 

uncertain. 

Another source of uncertainty for this chemical is the difference observed in laboratory 

studies, compared to the field. Results from five terrestrial field dissipation studies 

showed that fenpropathrin remains in the upper layers of soil, but reported half-lives 

showed a wide range from 8 to 144 days. The registrant has provided no valid reason for 

the differences in the persistence of fenpropathrin under laboratory and field conditions 

or between similar terrestrial field dissipation studies. The observed differences in the 

rate of dissipation of fenpropathrin in the field could be due to a number of variables such 

as geographical location, climatic conditions, and microbial population of the soil at 

different test sites; these variables affect the dissipation processes (such as photolysis, 

microbial degradation, and irreversible binding to the soil) some or all of which could be 

involved in the dissipation of the chemical in the field. Although the degradation of 

fenpropathrin could follow a number of parallel degradation pathways, it appears more 

likely that the major route of dissipation is microbial dissipation in soil. However, the 

aerobic and anaerobic soil metabolism studies indicate that fenpropathrin is resistant to 

microbial degradation. EFED believes that the metabolism studies required in this 

document will shed more light on the significance of these degradation processes and 

more clearly define the major routes of dissipation of fenpropathrin in the environment. 

 26
3.4. Open Literature Information 

The following is a cursory search of the available literature on fenpropathrin and 

synthetic pyrethroids in general, mostly about their prevalence/occurrence, and about 

their toxicity to aquatic invertebrates and sediment dwelling organisms (which also 

pertains to Section 4.1). It is not intended to be exhaustive. In the relatively recent past 

there has been an increased awareness of the prevalence and toxicity of fenpropathrin, 

and other synthetic pyrethroids, in sediment environments of urban and agricultural sites, 

particularly in California. 

Two major factors affect the toxicity of the synthetic pyrethroids: the presence of the 

synergist piperonyl butoxide (PBO) and the temperature. Amweg and Weston, 2007, 

documented the effects of the presence of PBO in sediments containing the representative 

synthetic pyrethroid, bifenthrin and other chemicals [cadmium (a metal), chlorpyrifos (an 

organophosphate), DDT (an organochlorine), and flouranthene (a polycyclic aromatic 

hydrocarbon)]. The 10-day Hyalella azteca LC50 was 0.26 μg/gOC vs. 0.12 μg/gOC in the 

presence of PBO in the overlying water at 25 μg/L (increased toxicity by a factor of 2.2). 

For the other chemicals, the factor was around or less than 1 (implicating no synergism) 

with no statistical difference in toxicity for all but chlorpyrifos. Eight field collected 

sediments, containing a variety of synthetic pyrethroids, or synthetic pyrethroids and 

chlorpyrifos (except for one sediment that contained only chlorpyrifos), that were 

previously tested and found to be toxic to Hyalella azteca, were examined with and 

without the presence of PBO. All the sediments exhibited higher toxicity in the presence 

of PBO except for the sediment that contained only chlorpyrifos. 

The effect of temperature was documented by Weston et al., 2009a. In an effort to 

identify factors affecting the toxicity identification evaluation (TIE) of the synthetic 

pyrethroids (i.e. “manipulating a sample in a manner that alters the toxicity of some 

toxicants but not others”), they performed sediment toxicity tests at various temperatures 

(13, 18, 23, or 28oC). 10-day LC50’s to Hyalella azteca were determined for four 

pyrethroids (not including fenpropathrin), also for chlorpyrifos, cadmium and DDT 

(which were representative of other classes of pesticides). For the four pyrethroids, the 

toxicity approximately doubled when the temperature was decreased from 23 to 18oC, 

and approximately tripled when the temperature was further decreased to 13oC. The 

results at 28oC were mixed, but for some of the control samples, survival was low, which 

could indicate that the test species was not tolerant of the changes to high temperature. 

DDT presented a similar response profile with temperature, but not as pronounced as for 

the synthetic pyrethroids. For chlorpyrifos and cadmium, the responses with temperature 

were nearly independent of temperature, and opposite to the one for the pyrethroids, 

respectively. Various field samples with known amounts of pyrethroids also showed 

similar responses to those of the tested pyrethroids (as indicated above), with a few 

exceptions. The authors discussed the possible repercussions of the temperature 

dependence of the synthetic pyrethroids during the winter season, when the temperatures 

of the waters and sediments are lower. Even though these studies did not include 

fenpropathrin, they illustrate the effects of the presence of PBO and temperature on 

certain synthetic pyrethroids and, by extrapolation, may apply to fenpropathrin as well. 

 27
In a recent study (Stout II, et al. 2009), conducted by the US Department of Housing and 

Urban Development, in collaboration with the Agency, several chemicals were surveyed 

on floors of occupied homes. The survey included fenpropathrin and several other 

synthetic pyrethroids. Fenpropathrin was detected with a frequency of 4% (mean and 

standard deviation not calculated, maximum value = 1.1 ng/cm2), illustrating that this 

chemical is detected and present in homes. The synthetic pyrethroids more frequently 

detected were cis- and trans-permethrin (88-89% frequency). Fenpropathrin is not 

among the constituents monitored by the National Water Quality Assessment (NAWQA), 

maintained by the U.S. Geological Survey. 

Holmes et al. 2008 presented the occurrence and toxicity of the synthetic pyrethroids 

throughout the state of California’s urban creek sediment samples. First, 90 samples 

were screened for toxicity to Hyalella azteca, of which around one third caused 

significant toxicity to the organisms. Later, 30 sample locations were selected for the 

final study. Of the 30 samples, 25 were toxic to Hyalella azteca at 23oC and all 30 

samples were toxic at 15oC (the synthetic pyrethroids often show higher toxicity at lower 

temperatures, see above). Seven of eight pyrethroids were detected in the sediment 

samples. Fenpropathrin was not detected in any of the samples, but bifenthrin was 

present in all the 30 samples (2.19 to 219 ng/g dry weight). Permethrin was the second 

most detected pyrethroid. The results suggest an important role of the synthetic 

pyrethroids in California’s urban creeks sediment toxicity. Bifenthrin accounted for 

around two thirds of the toxicity on an average basis. These are just a few examples that 

illustrate the high use of synthetic pyrethroids in urban settings and potential ecological 

ramifications. 

Budd et al. 2007 sampled sediments in mixed land (urban and agricultural) in the San 

Diego Creek in Newport Bay Watershed in southern California. Bifenthrin and 

fenpropathrin were among the most frequently detected synthetic pyrethroids, with 

bifenthrin found in 95-100% of the samples. According to the study...“Fenpropathrin 

was the second most frequently detected pyrethroid, found in 68% of the dry season 

samples and 90% of the wet season samples.” The highest concentrations were 

associated with commercial nurseries. The authors found in this case that the 

concentration of synthetic pyrethroids was generally lower in residential or commercial 

areas as opposed to agricultural sites. Also, the frequency of detections of pyrethroids 

was higher during the wet season but the total concentration was not statistically different 

between the wet and dry seasons. 

In addition, Weston et al. 2004 studied the presence of 26 pesticides, including five 

pyrethroids (but not including fenpropathrin), in 70 sediment samples taken from the 

agriculture dominated Central Valley in California. Ten-day sediment tests were 

conducted for Hyalella azteca and Chironomus dilutus (formerly known as Chironomus 

tentans), for some of the samples. Synthetic pyrethroids were found in 75% of the 

sediment samples; also they were found, based on a toxicity unit basis, to be sufficiently 

high to cause toxicity in 40% of the samples toxic to C. dilutus and around 70% of the 

samples toxic to H. azteca. The most commonly found pyrethroids were permethrin > 

 28
esfenvalerate > bifenthrin > lambda-cyhalothrin. This study illustrates the high 

frequency of detections of synthetic pyrethroids in sediments from agriculture dominated 

regions. 

In a study, Gan et al. 2005 monitored the spatial distribution and enrichment (enrichment 

ratio, ER, or ratio of the concentration of a substance in eroded sediment to that of the 

source matrix) of the synthetic pyrethroids permethrin and bifenthrin, along a 260-m 

runoff path. A sedimentation pond was used as the source point for the study (permethrin 

and bifenthrin had been used extensively at the site, for ant control, in a nursery 

environment). It was observed that, in general, the sediment concentration of permethrin 

and bifenthrin increased with distance (downstream from the source). Using the source 

as the reference value, ERs were calculated for these chemicals. The ER reached 25.7-

32.2 for bifenthrin at 145 m and beyond, and they were lower for permethrin. This article 

illustrates the possibility of enrichment of synthetic pyrethroids in sediment samples 

downstream from the source. 

Ding et al. 2010 conducted monitoring for 29 pesticides, including pyrethroids like 

bifenthrin and fenpropathrin, from both urban and agricultural sites in central and 

southern counties in the state of Illinois in 2008. Most of the urban samples were from 

constructed storm drains, while the agricultural samples were from small waterways 

between farmlands in areas where mostly corn and soybeans were grown and the major 

pesticides used were tefluthrin and atrazine. Furthermore, sediment toxicity tests towards 

Hyalella azteca were performed. In the urban samples, the synthetic pyrethroids were 

detected in 95% of the samples. Bifenthrin was detected in 80% of the samples, while 

permethrin, lambda-cyhalothrin and fenpropathrin were also frequently detected. In the 

agricultural samples, bifenthrin, permethrin, cypermethrin and tefluthrin were detected 

(frequency of detection 47%), while fenpropathrin and lambda-cyhalothrin were not 

detected. Ten of 17 urban sediment samples tested, were significantly more toxic to H. 

azteca than the controls. Only one of the agricultural sediment samples was significantly 

more toxic than the control. The major source of toxicity units (TUs) were the 

pyrethroids (in particular, bifenthrin). It was indicated that the detections of 

fenpropathrin in the urban samples was unexpected because it is a pesticide primarily 

used in agriculture. 

In a very recent article, Weston & Lydy 2010 studied the possible sources of pyrethroids 

in California’s Sacramento – San Joaquin River Delta, including urban runoff, municipal 

wastewater treatment plants (or Publicly Owned Treatment Works, POTWs), and 

agricultural discharges, in a study that focused on water samples (as opposed to most of 

the studies above that are related to sediments). Samples were taken during the wet and 

dry seasons. Urban runoff samples were taken from concrete sumps, from which pumps 

lift waters to adjacent rivers over levees. POTWs with secondary treatment were 

sampled just prior to discharge to surface waters. Agricultural discharges were collected 

at pump stations, where the runoff is lifted over the levees. Samples were tested for 8 

pyrethroids and chlorpyrifos (LOQ around 1 ng/L for most samples). Tests to Hyalella 

azteca were also performed at the temperature measured in the rivers. Fenpropathrin was 

found in 3, 0 and 5% of the samples of urban runoff, POTWs and agricultural drains, 

 29
respectively. The H. azteca EC50 for fenpropathrin was not available for comparison 

with the concentrations. The maximum measured fenpropathrin concentration was 6.1 

ng/L, for an urban runoff sample. Through TIE, it was found that the toxicity was 

increased for most samples in the presence of PBO. A similar effect was observed when 

the temperature of the samples was decreased. In the presence of the enzyme E3, which 

is capable to degrade the pyrethroids, the effect was a decreased toxicity of the samples 

towards H. azteca. In the presence of bovine serum albumin (BSA), no effect on the 

toxicity of the samples towards H. azteca, was observed. The pyrethroid presence in 

POTWs was unexpected because the effluents had low suspended material and the 

possible partitioning with biosolids within the plants. The authors indicated that possible 

sources of pyrethroids are sewer disposal of household insecticides, lice control 

shampoos, pet products and permethrin treated clothing. 

Sakata et al. 1990 studied the aerobic and anaerobic metabolism of fenpropathrin in two 

Japanese soils for 24 weeks at 25oC in the dark. The reported half-lives were 11 and 17 

days for the SCL and the light clay. In contrast, fenpropathrin was relatively stable in 

anaerobic and in sterile (autoclave) conditions. The degradates COOH-fenpropathrin and 

CONH2–fenpropathrin were observed. It appears that sampling occurred only at 4, 8 and 

24 weeks. Katagi 1993 studied the effect of soil moisture on soil surfaces containing the 

chemical and irradiated with a xenon lamp (wavelengths above 290 nm, simulating 

natural sunlight), using three soils (CL, L and L), at 25oC for 14 days. Similar products 

were observed. The light appeared to enhance the rate of reaction. Akhtar et al. 2004 

studied the persistence of chlorpyrifos and fenpropathrin alone and in combination with 

various fertilizers at 28-30oC using soils from Pakistan in the dark and in flooded 

condition. Fenpropathrin was persistent under the testing conditions. 

Gan et al. 2008, calculated half-lives of fenpropathrin and three other synthetic 

pyrethroids in two sediments under aerobic conditions. The half-lives for the total system 

were 89 and 152 days (for the SDC and BM sediments).2 Furthermore, they provided 

KOC’s for several synthetic pyrethroids obtained using the solid phase microextraction 

sampling technique (SPME). For fenpropathrin, the mean corrected KOC, using the 

SPME was 12 times higher than the one published by Laskowski 2002. The mean 

corrected KOC is 0.5x106

 (vs. 0.4x105 from Laskowski 2002). Li et al. 2009 studied the 

degradation of fenpropathrin and fenvalerate in an alkaline and in an acidic sterile 

(autoclave) and viable loam soils from China at 22oC in the dark, using enantioselective 

HPLC. The degradation of fenpropathrin was slightly enantioselective. S-fenpropathrin 

degraded slightly faster under alkaline conditions. The calculated half-lives were 15.3 

days and 16.2 days for S-fenpropathrin and R-fenpropathrin, respectively. In contrast, in 

the control, fenpropathrin dissipated very slowly (≤10% after 55 days). One experiment 

used the S-fenpropathrin enantiomer only. The analysis showed formation of Rfenpropathrin (racemization of the alpha carbon). This occurred both in the sterile and 

viable alkaline soils. In the acidic soils, the half-life for S-fenpropathrin was 31.1 days, 

with almost no degradation in the sterile soils. No racemization was observed in the 

acidic soils. 

 

2

 SDC is a sediment from the San Diego Creek (OC=1.4%) and BM is a sediment from a pond in Black 

Mountains in Paso Robles (Central CA) (OC=5.0%). 

 30
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 fenpropathrin, 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 fenpropathrin. 

Consistent with the process described in the Overview Document (EPA, 2004), this risk 

assessment uses a surrogate species approach in its evaluation of fenpropathrin. 

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 and 4.2 provide a summary of the taxonomic groups and the surrogate species 

tested to help understand potential acute ecological effects of pesticides to these nontarget taxonomic groups. In addition, the tables provide a preliminary overview of the 

potential acute toxicity of fenpropathrin by providing the acute toxicity classifications. 

Terrestrial Species 

In general, fenpropathrin appears to be slightly toxic to avian species but highly toxic to 

mammalian species on an acute level (LD50 = 1089 mg/kg for avian species and 48.5 

mg/kg for mammals) and also practically non-toxic to birds on a subacute level (LC50s

>5000 ppm). Chronic toxicity data show that exposure can result in reproductive effects 

(NOAEC/LOAEC = 25/125 ppm for Quail and 125/500 ppm for Mallard duck). 

Reproductive effects to mammals were noted with an LOAEL of 250 ppm and a NOAEL 

of 25 ppm. Toxicity to honeybees from residues on foliage suggests that fenpropathrin is 

toxic and produces high mortality to non-target insects (at 0.2 lbs ai/A mortality was 

>80% within the first 8-24 hrs of exposure). 

Table 4.1 Summary of most sensitive endpoints from submitted terrestrial toxicity studies for 

fenpropathrin. 

Species 

(common 

name)

Taxa 

Represented

Endpoint 

Mean 

Concentration 

Test 

Substance 

(% a.i.) 

Citation 

MRID 

Acute 

Toxicity 

Classification 

Mouse LD50 48.5 mg/kg/bw Tech 127345 Highly Toxic 

Rattus NOAEL 25 ppm 

norvegicus 

(Laboratory 

Rat) 

Mammals 

LOAEL 250 ppm 

Tech HED N/A 

 31
Table 4.1 Summary of most sensitive endpoints from submitted terrestrial toxicity studies for 

fenpropathrin. 

Citation Species Test Acute Taxa End- Mean 

(common 

name)

Represented point Concentration Substance 

(% a.i.) 

MRID Toxicity 

Classification 

Anas 

platyrynchos 

(Mallard duck) 

LD50 1089 mg/kg bw 89 249939 Slightly toxic 

Anas 

platyrynchos 

(Mallard duck) 

LC50 9026 mg/kg diet 89 249939 

Colinus NOAEC 25 mg/kg diet 

virginianus 

(Bobwhite 

quail)

Birds, terrestrialphase 

amphibians, and 

reptiles 

LOAEC 125 mg/kg diet 

Tech 265374 

Practically 

nontoxic 

Apis mellifera

(Honey bee) 

Terrestrial 

invertebrates Residue Extended residual toxicity 30 133103 High mortality 

Aquatic Species 

In general, fenpropathrin is considered to be very highly toxic to fish and invertebrates 

(freshwater and estuarine/marine) on an acute basis. Acute toxicity studies on freshwater 

fish (LC50s of 2.2 ppb for Bluegill and 5.5 ppb for Catfish) and invertebrates (EC50 = 0.53 

ppb) show that this compound is acutely very highly toxic to these organisms. In acute 

tests with estuarine fish and invertebrates, fenpropathrin was also considered very highly 

toxic to sheepshead (LC50 = 3.1 ppb) and to mysid (LC50 = 21 pptr) and fiddler crabs 

(EC50 = 5.2 ppb). Chronic effects were noted in mysids (NOAEC = 0.012 ppb) as well as 

in fathead minnow (MATC = 0.091 ppb). A study (Pan and Liang 1993) using bog frog 

tadpoles (Rana limnocharis) found fenpropathrin to be very highly toxic on a subacute 

basis (LC50 = 2.2 ppb). Studies using 2.4 EC spray (30% ai) resulted in very highly toxic 

LC50s of 7.7 ppb for Sunfish, 10 ppb for Rainbow trout, 22 ppb for Catfish, 2.9 ppb for 

Daphnia, 15 ppb for Sheepshead minnow and 0.33 ppb for Mysid shrimp. All submitted 

aquatic TEP toxicity studies were less toxic than the parent TGAI. 

 32
Table 4.2. Summary of most sensitive endpoints from submitted aquatic toxicity studies 

for fenpropathrin. 

Species 

(common name) 

Taxa 

Represented 

Endpoint Duration 

(hours) 

 Mean 

concentration 

(μg a.i./L) 

Citation 

MRID 

Acute 

Toxicity 

Classification 

 Lepomis 

macrochirus

(Bluegill sunfish) 

LC50 96 2.2 249939 Very highly 

toxic 

NOAEC Pimephales 0.06 

promelas 

(Fathead Minnow)

Freshwater fish 

and aquaticphase 

amphibians

MATC 

28 (days) 0.091 415259-01 N/A 

EC50 48 0.53 249939 Very highly 

toxic 

NOAEC 0.064 

Daphnia magna 

(Water Flea) 

Freshwater 

Invertebrates 

LOAEC 

 21 (days) 0.35 259678 N/A 

Cyprinodon 

variegatus

(Sheepshead 

minnow) 

Estuarine/ 

Marine Fish LC50 96 3.1 249939 Very highly 

toxic 

LC50 96 0.021 409744-04 Very highly 

toxic 

NOAEC 0.012 Mysidopsis bahia 

(Mysid shrimp) 

Estuarine/ 

Marine 

Invertebrates 

LOAEC 

28 (days) 0.024 409744-07 N/A 

Plants 

No aquatic or terrestrial plant data are available to the Agency for fenpropathrin. 

ECOTOX 

Available open literature will be used to evaluate the potential direct effects of 

fenpropathrin 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). 

At this time, a full and complete ECOTOX search has not been performed, but will be 

conducted prior to issuance of any Data Call-in. 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 fenpropathrin 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’ 

 33
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 preliminary review on January 27, 2010 of the Ecological Incident Information System 

(EIIS, version 2.1), which is maintained by the Agency’s Office of Pesticide Programs,

and the Avian Monitoring Information System (AIMS), which is maintained by the 

American Bird Conservancy, indicates one reported ecological incident associated with 

the use of fenpropathrin. These incidents are summarized in Table 4.3. This total 

excludes incidents classified as ‘unlikely’ and only includes those incidents with certainty 

categories of ‘highly probable’, and ‘probable’ and ‘possible’ (for EIIS) and ‘certain’, 

‘highly likely’, ‘likely’, ‘probable’, and ‘possible’ (for AIMS). In the EIIS and AIMS 

databases, the “unlikely” category is used when a chemical is not likely to be responsible 

for the incident. For example, an ‘unlikely’ classification might be applied in situations 

where a given chemical is practically nontoxic to the category of organism killed and/or 

there is evidence that another pesticide or stressor likely caused the incident. Incidents 

classified as ‘unlikely’ for fenpropathrin will not be included in this Problem Formulation 

or the ecological risk assessment conducted for Registration Review. 

One incident was reported for fenpropathrin (Danitol 2.4 EC) that occurred in Imperial 

CA in 1996 and involved a fish kill. The incident (I004215-006 was classified as “highly 

probable”) involved hundreds of fish mortalities (shad, catfish and carp) after application 

of Fenpropathrin to cotton. Residue data were collected. 

Table 4.3 Wildlife Incidents Associated with Fenpropathrin

Chemical 

Name 

Incident 

Number 

(Source) 

Taxa 

Involved Magnitude Year 

Location 

(County, 

State) Use 

Legality 

of Use 

Certainty 

Category1 Residues 

Fenpropathrin 

EIIS 

I004215-

006 

Fish 

(Shad, 

Catfish & 

Carp) 

200 1996 Imperial, 

CA Cotton Registered use 

Highly 

Probable 

36 ppb in 

gills 

68 ppb in 

tissue 

1300 ppb 

in soil 

sample 

from bank 1

Incidents classified as ‘unlikely’ are excluded. 

Although only a total of one incident for fenpropathrin has been reported to the Agency, 

the absence of reported incidents should not be construed as the absence of incidents. 

Incident reports for non-target organisms typically provide information only on mortality 

events and plant damage incidents. Except for phytotoxic effects in terrestrial plants, 

 34
sublethal effects for organisms such as reduced growth or impaired reproduction are 

rarely reported. EPA’s changes in the registrant reporting requirements for incidents in 

1998 may account for a reduced number of reported incidents. Registrants are now only 

required to submit detailed information on ‘major’ fish, wildlife, and plant incidents. 

Minor fish, wildlife, and plant incidents, as well as all other nontarget incidents, are 

generally reported aggregately and are not included in EIIS. In addition, there have been 

changes in state monitoring efforts due to lack of resources. 

In the risk assessment, the incident will be further evaluated to determine if it represents 

current patterns of use for fenpropathrin. 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. 

As it has been indicated earlier, fenpropathrin is not among the constituents monitored by 

the National Water Quality Assessment Data Warehouse, (NAWQA) maintained by the 

U.S. Geological Survey; however, multiple articles from the literature document the 

presence of synthetic pyrethroids like fenpropathrin in both urban and agricultural 

sediments (refer to Section 3.4). 

4.3. Ecosystems Potentially at Risk 

Fenpropathrin may be applied on a variety of food crops, including head & stem brassica, 

citrus, cotton, cucurbit & fruiting vegetables, grapes, peanut, tree nut, stone & pome 

fruits, strawberries, bushberries, caneberries, currant, peas, olives, barley and tropical 

fruits. In addition, it may be used in various non-food sites (e.g. agricultural uncultivated 

areas, deciduous fruit trees, forest trees, ornamental and/ or shade trees, ornamental 

herbaceous plants, ornamental non-flowering plants, and ornamental woody shrubs and 

vines). 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 

fenpropathrin, 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 persistence of fenpropathrin, it is expected to drift and/ or runoff due to 

application to food crops, resulting in possible exposure to aquatic ecosystems. Aquatic 

ecosystems potentially at risk due to the use of fenpropathrin 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, including 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) 

 35
identifying the valued attributes of the environment that are considered to be at risk; and 

2) operationally defining the assessment endpoint in terms of an ecological entity (i.e., a 

community of fish and aquatic invertebrates) and its attributes (i.e., survival and 

reproduction). Therefore, selection of the assessment endpoints is based on valued 

entities (i.e., ecological receptors), the ecosystems potentially at risk, the migration 

pathways of pesticides, and the routes by which ecological receptors are exposed to 

pesticide-related contamination. The selection of clearly defined assessment endpoints is 

important because they provide direction and boundaries in the risk assessment for 

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

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

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

such as fenpropathrin. 

To estimate exposure concentrations, the ecological risk assessment considers a single 

application 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 fenpropathrin. More sensitive endpoints from acceptable open literature studies 

will be included in this 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 fenpropathrin, 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 (EPA, 1998). 

 36
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 (EPA 1998). For this assessment, the risk is 

stressor-initiated, where the stressor is the release of fenpropathrin into the environment. 

The following risk hypothesis is presumed for this screening-level assessment: 

Fenpropathrin and its residues, when used in accordance with registered labels, 

will likely lead to off-site movement of the compound via 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 fenpropathrin 

have the potential to cause reduced survival, growth, and reproduction to nontarget terrestrial and/ or aquatic animals and plants.

 

The conceptual model is a generic graphic depiction of the risk hypothesis. It includes 

the potential pesticide or stressor (fenpropathrin and its possible residues of concern), 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 fenpropathrin, a Type II synthetic pyrethroid, having 

multiple 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 fenpropathrin, 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 (see 

Figures 6.1a and 6.1b, below). They include the potential pesticide or stressor 

(fenpropathrin, but the presence of toxicologically important metabolites cannot be ruled 

out), the sources and/ or transport pathways, exposure media and exposure points, 

biological receptor types and attribute changes. 

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 

 37
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 (note, that for fenpropathrin, at this time, no major metabolites 

have been identified). 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 fenpropathrin, the sources and mechanisms of release of the 

compound are from ground or aerial spray 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 fenpropathrin is highly immobile. Due to 

fenpropathrin’s physicochemical properties (vapor pressure and Henry’s Law constant), 

atmospheric transport appears unlikely. Furthermore, the estimated hydroxyl radical 

reaction half-life estimated by EpiSuite v.4.0 is only 0.599 days. It appears that 

fenpropathrin would not persist in the environment for extended periods of time. 

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 from treated areas. Indirect effects to aquatic organisms 

(both fish and aquatic invertebrates) can also occur through impact to various food chains 

(it was established earlier in this document that fenpropathrin has the potential to 

bioaccumulate/bioconcentrate). 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. 6.1a). Fenpropathrin has a very high KOW and 

according to its physicochemical and fate properties, there is a potential for 

bioaccumulation/ bioconcentration in aquatic organisms, and biomagnification in 

terrestrial organisms. 

Fenpropathrin shows a very low solubility, a very high KOW and also high KOC’s. These 

 38
properties suggest that the chemical partitions with sediments, and with organic matter 

suspended in the water bodies. Fenpropathrin is likely to concentrate in the sediments, 

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. This potential for toxicity will also be assessed in the risk 

assessment for fenpropathrin. 

**Route of exposure includes only ingestion of fish and aquatic inverts. 

Stressor 

Source 

Receptors 

Attribute 

Change 

Fenpropathrin applied to agricultural or non-agricultural use sites 

Spray drift 

Aquatic animals 

Invertebrates 

Vertebrates 

**Piscivorous mammals 

 and birds 

Individual 

organisms 

Reduced survival 

Reduced growth 

Food chain 

Reduction in algae and 

 vascular plants 

Reduction in prey 

Modification of PCEs 

 related to prey availability 

Habitat integrity 

Reduction in primary 

 productivity

Reduced cover 

Community change 

Modification of PCEs related to 

 habitat 

Surface water/ 

Sediment 

Runoff

Aquatic Animals

Invertebrates 

Vertebrates 

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 

Exposure 

Media 

Figure 6.1a. Conceptual model depicting stressors, exposure pathways, and 

potential effects to aquatic organisms from the use of fenpropathrin on agricultural 

and certain non-agricultural sites 

Dotted lines indicate exposure pathways that have a low likelihood of contributing to ecological risk. 

 39
Stressor 

Source 

Attribute 

Change 

Fenpropathrin applied to agricultural or non-agricultural use sites 

Direct 

application Spray drift 

Terrestrial 

vertebrates 

Terrestrial 

invertebrates 

Individual 

organisms 

Exposure Media 

& Receptors 

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 

Soil 

Ingestion 

Ingestion 

Ingestion

Dermal uptake/Ingestion

Atmospheric 

transport 

Root uptake/contact 

Wet/dry deposition

Ingestion

Leaching to

Groundwater Irrigation 

water 

Figure 6.1b. Conceptual model depicting stressors, exposure pathways, and 

potential effects to terrestrial organisms from the use of fenpropathrin on 

agricultural and certain non-agricultural sites 

Dotted lines indicate exposure pathways that have a low likelihood of contributing to ecological risk. 

 

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 fenpropathrin 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 (i.e., for assessing risks to listed species) from particular uses of a 

chemical is estimated using the probit dose-response slope and either the level of concern 

(discussed below) or the actual calculated risk quotient value. 

 40
This analysis plan will be revisited and may be revised depending on the data available in 

the open literature and the information submitted by the public 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, fenpropathrin. However, the 

Agency will review open literature to identify degradate(s) of potential toxicological 

concern (e.g. 4’-OH-fenpropathrin and other transformation products were observed in 

certain terrestrial field dissipation studies). If degradates of toxicological concern are 

identified, they will also be considered as part of the stressor of concern. 

Toxicity data for environmental mixtures of fenpropathrin with other pesticides (those 

mixtures occurring in the environment following application), if available, may be 

presented as part of the ecological risk assessment. Fenpropathrin may be applied in tank 

mixtures with other products approved for use on registered crops. It is expected that the 

toxic effect of fenpropathrin, 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 

fenpropathrin 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 qualitative discussion 

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

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

7.2. Measures of Exposure 

In order to estimate risks of fenpropathrin 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. Measures of exposure are 

based on aquatic and terrestrial models that predict estimated environmental 

concentrations of fenpropathrin 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). 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 (the 

bioconcentration factors). These models are parameterized using relevant reviewed 

registrant-submitted environmental fate and transport data. 

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 

 41
exposures and 1-in-10 year EECs of fenpropathrin, 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 m3 volume) with no outlet. PRZM/ EXAMS is used 

to estimate screening-level exposure of aquatic organisms to fenpropathrin 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. 

Given the aquatic toxicity of fenpropathrin 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. 

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). For pesticides such as 

fenpropathrin, which can be applied as a dust, this includes the amount of pesticide per 

square foot, used in LD50 per square foot risk assessment calculations. 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 

(assumed to be 0% for granulars) 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, fenpropathrin appears to 

have a potential to bioconcentrate in aquatic organisms & biomagnify in aquatic and 

terrestrial organisms. The potential for bioaccumulation of fenpropathrin will also be 

examined in the risk assessment. Because fenpropathrin has a fairly high KOW (1.00 x 

106

) and the chemical may be persistent in water and sediments, there is a potential for 

bioaccumulation. The bioconcentration factors ranged from 200x (fillet) to 1400 (viscera) 

and depuration rate is moderate (by day 21 of depuration, 78-84% of the residues had been 

eliminated from the fillet, MRID 161672, 163521). 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. 

 42
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 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 ObservedAdverse-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., “NoObserved-Adverse-Effect-Concentration”) is the highest test concentration at which none 

of the observed effects were statistically different from the control. The NOEC is the NoObserved-Effects-Concentration. For non-listed plants, only acute exposures are 

assessed (i.e., EC25 for terrestrial plants and EC50 for aquatic plants); for listed plants 

either the NOAEC or EC05 is used. 

Information on the potential effects of fenpropathrin on non-target animals is also 

collected from the Ecological Incident Information System (EIIS). 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 fenpropathrin to birds is similar to terrestrial-phase amphibians and 

reptiles. The same assumption is made for fish and aquatic-phase amphibians. 

 43
7.4. Integration of Exposure and Effects 

Risk characterization is the integration of exposure and ecological effects characterization 

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 non-target 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 fenpropathrin’s 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 pointestimate 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 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 fenpropathrin. 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 fenpropathrin 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 fenpropathrin 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 sublethal 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 

 44
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. 

Probit Slope Analysis 

The probit slope response relationship is evaluated to calculate the chance of an 

individual event corresponding to the listed species acute LOCs. If information is 

unavailable to estimate a slope for a particular study, a default slope assumption of 4.5 is 

used as per original Agency assumptions of typical slope cited in Urban and Cook 

(1986). 

a. Terrestrial Species 

Terrestrial acute toxicity studies for fenpropathrin did provide raw data and estimates of 

slopes for avian species. Analysis of raw data provided a slope of 2.0 from an acute 

toxicity study using the Mallard Duck. Based on this slope, the corresponding estimate 

chance of individual mortality following exposure is 1 in 44. 

b. Aquatic Species 

Acute toxicity studies for fenpropathrin did provide raw data and estimates of slopes for 

fish and aquatic invertebrate species. Analysis of raw data from the aquatic acute toxicity 

studies provided slopes of 3.1 for freshwater fish, 2.75 for freshwater invertebrates 

(daphnia) and 2.69 for estuarine/marine invertebrates (mysid). Based on these slopes, the 

corresponding estimate chance of individual mortality following exposure is 1 in 3.63 x 

104

 for freshwater fish, 1 in 5.77 x 103 for freshwater invertebrates, and 1 in 4.24 x 103

for estuarine/marine invertebrates. 

7.7. Drinking Water Assessment 

A drinking water assessment will be conducted to support future human health risk 

assessments of fenpropathrin should it be required. The drinking water assessment will 

incorporate model estimates of fenpropathrin 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 - see description above, if refinements are required). Ground water 

estimates of concentrations will be estimated 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 

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 

 45
statutorily required determinations. Tier 1 consists of a battery of 11 screening assays to 

identify the potential of a chemical substance to interact with the estrogen, androgen, or 

thyroid (E, A, or T) hormonal systems. Chemicals that go through Tier 1 screening and 

are found to have the potential to interact with E, A, or T hormonal systems will proceed 

to the next stage of the EDSP where EPA will determine which, if any, of the Tier 2 tests 

are necessary based on the available data. Tier 2 testing is designed to identify any 

adverse endocrine related effects caused by the substance, and establish a dose-response 

relationship between the dose and the E, A, or T effect. 

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 postapplication agricultural scenarios. This list should not be construed as a list of known or 

likely endocrine disruptors. 

Fenpropathrin is not among the group of 58 pesticide active ingredients on the initial list 

to be screened under the EDSP. Under FFDCA sec. 408(p) the Agency must screen all 

pesticide chemicals. Accordingly, EPA anticipates issuing future EDSP test orders/data 

call-ins for all pesticide active ingredients. 

For further information on the status of the EDSP, the policies and procedures, the list of 

67 chemicals, the test guidelines and the Tier 1 screening battery, please visit our 

website: http://www.epa.gov/endo/ . 

7.9. Preliminary Identification of Data Gaps 

7.9.1. Fate 

After evaluation of the available data for fenpropathrin, the following are the data gaps 

for registration review: 

835.2240 Aqueous Photolysis – The available study was performed in the presence of 

high levels of cosolvent acetonitrile (around 8%). The study indicated that fenpropathrin 

was stable under the testing conditions. Supplemental data from other previously 

reported studies, indicated half-lives ranging from 1.6 to around 113 days (data reported 

by Laskowski 2002, half-lives ranging from 14.6 to 87.5 days). There is a high level of 

uncertainty with respect to the levels of photolysis and there are no reliable data related to 

the possible transformation products. A new study is required to clarify these 

uncertainties. 

835.4100 Aerobic Soil Metabolism – At this time the Agency has studies performed in 

one soil (152 days, SiL). Further supplemental data indicated the following estimates of 

half-lives: 33-35 days (light clay) and 34-39 days (SCL). This early study was conducted 

for only 30 days (required 365 days). High variability in the results from the 

 46
supplemental study conducted earlier (with shorter half-lives) vs. the most recent study 

brings uncertainty to the environmental fate assessment. Furthermore, aerobic soil 

metabolism half-lives, reported by Laskowski 2002, are 34.1, 32.1, 34.8, 36.5, 39.4, 133, 

34.7, 51.3, 221 & 186 days for SCL, C, SCL, C, SL, C, SL, SC, SC & L soils. Rates of 

transformation should be determined in four soils. The registrant should submit a study 

conducted in three soils; a sandy loam soil should be included. 

835.4200 Anaerobic Soil Metabolism – The available study was performed with only 

one soil and for a period of roughly 2 months of anaerobic incubation (with a reported 

half-life of 186 days, for a L soil). Other half-lives, reported by Laskowski 2002, are 283 

& 383 days for C & SCL, respectively. 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 (from Fate, 

Transport and Transformation Test Guidelines – OPPTS Guideline 835.4100 & 

835.4200). The study indicates that after the soil was flooded (converted to anaerobic), 

the metabolism was very low. Data performed for a longer period of time will help the 

Agency to determine rates of transformation and presence of possible metabolites. 

835.4300 Aerobic Aquatic Metabolism – No study has been submitted. Gan et al.

2008, calculated half-lives of fenpropathrin and three other synthetic pyrethroids in two 

sediments under aerobic conditions. The half-lives for the total system were 89 and 152 

days (for the San Diego Creek – SDC, and a pond in Black Mountains – BM, sediments). 

According to OPPTS Guideline 835.4300 and 835.4400, “At least two sediments and 

their associated waters are used for both the aerobic and the anaerobic studies 

respectively (see paragraph (h)(10) of this guideline). 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.” As discussed in Section 3.2, on pesticide use and 

usage, there is the potential for use of fenpropathrin near estuarine/ marine environments. 

The study is required. 

835.4400 Anaerobic Aquatic Metabolism – Two studies are available, performed in 

only one soil type (yielding half-lives of 78 and 67 days in a CA L). These studies are 

currently in review. Other half-lives, reported by Laskowski 2002, are 93.4, 85 & 57.8 

days for L, L & SL, respectively. According to OPPTS Guideline 835.4300 and

835.4400, “For the strictly anaerobic study, two sediments (including their associated 

waters) should be sampled from the anaerobic zones of surface water bodies...” A study 

is available in only one soil system. A study conducted in at least one additional 

sediment type is required. 

835.1230 Mobility Adsorption/ Desorption – The available study was performed at a 

single concentration and no Freundlich correlations are available. An update or upgrade 

of the study is currently in review; it contains data on one additional soil (a loam). This 

data requirement is considered unfulfilled until the update/ upgrade study is reviewed and 

deemed acceptable. 

 47
Environmental Chemistry Methods (ECMs), and Independent Laboratory 

Validations (ILVs), for Soil, Water and Sediment. ECMs associated with the 

Terrestrial Field Dissipation study (Field dissipation §158.1300; OPPTS guidelines 

835.6100, 835.6200, and 835.6300), 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 quantization for 

the residues of concern that are lower than the relevant toxicological levels of concern. 

Previous reviews on fenpropathrin indicate that there is high concern for acute and 

chronic aquatic toxicity. Certain scenarios may have triggered acute and chronic levels 

of concern for freshwater and/ or estuarine/ marine aquatic invertebrates and/ or for fish. 

In addition, the latter risk assessments conducted on fenpropathrin, indicated risk 

concerns for 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, the following appear to be the residues of concern for each media, but this 

could change, based upon the results of the other environmental fate studies: 

Soil – parent, PBA, CONH2-fenpropathrin and COOH-fenpropathrin 

Water – parent, PBA, CONH2-fenpropathrin 

Sediment – parent and possible metabolites 

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. The registrant submitted one method for soil (MRID 41679601, LOD 0.01 

ppm, published in the Agency’s ECM website)3 is available, that could quantify 

fenpropathrin and its metabolites 4’-OH-fenpropathrin and desphenylfenpropathrin in 

soil, using GC with a nitrogen/ phosphorous flame ionization detector. These levels of 

quantization may not be appropriate. Furthermore, the following studies have been 

located and are currently in review: MRIDs 71368 & 100138, 126817, 126818, 43958802 

and 43958803 (the latter two studies are ILVs), and 47053001 and 47053002 (ECM and 

ILV). A full description of the method validation procedures performed by an 

independent laboratory should also be submitted. These reports will be evaluated by 

EFED. According to NAFTA Guidance (Corbin et al. 2006), they should include the 

following information: (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. This data requirement is considered unfulfilled until the 

studies mentioned above are reviewed. 

 

3 Available at url: http://www.epa.gov/oppbead1/methods/ecmindex.htm

 48
Table 7.1 lists the status of the environmental fate data requirements for fenpropathrin. 

Table 7.1. Summary of Environmental Fate Data Requirements for Fenpropathrin 

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 Yes 131438, 141320, 

42599901 

No

835.2240 Photodegradation in 

Water 

1,2 Yes 43917227 Yes2

835.2410 Photodegradation on 

Soil 

1,2 Yes 137769, 42546402 No 

835.2370 Photodegradation in 

Air 

1,2 No Not Available Waived3

Metabolism Studies-Lab:

835.4100 Aerobic Soil 1,2 Yes 126823, 130869, 

142547, 42525902 

Yes4

835.4200 Anaerobic Soil 1,2 Yes 42546403 Yes5

835.4300 Aerobic Aquatic 1,2 No N/A Yes6

835.4400 Anaerobic Aquatic 1,2 Yes 44370003, 44370004 Yes7

Mobility Studies:

835.1230 Leaching – 

Adsorption/ Desorption 

1,2 Yes 42584101, 44370002 In review8

835.1410 Volatility (Lab) 1,2 Yes Not Available Waived3

835.8100 Volatility (Field) 1,2 No Not Available Waived3

Dissipation Studies-Field:

835.6100 Terrestrial Field 

Dissipation 

1,2 Yes 41679601, 41525905, 

41525904, 42311401, 

42311402 

No 

835.6200 Aquatic Field 

Dissipation 

1,2 No Not Applicable N/A 

835.6300 Forestry Dissipation 1,2 No Not Applicable N/A 

Ground Water Monitoring Studies:

835.7100 Ground Water 

Monitoring 

1,2 No NA Reserved 

 49
Table 7.1. Summary of Environmental Fate Data Requirements for Fenpropathrin 

Must Additional 

Does EPA Have Data Be Submitted 

Study Identification 

Use Data To Satisfy Under FIFRA 

Pattern1

This Requirement? Bibliographic Citation 3(c)(2)(B)? 

§158.1100 SPRAY DRIFT

201-1 Droplet Size Spectrum 1,2 Yes 40024621 No9 

202-1 Drift Field Evaluation 1,2 No Not Available No10

Other Studies: 

Environmental Chemistry 

Methods (ECMs) and 

Independent Laboratory 

Validations (ILVs) 

1,2 Partially 71368 & 100138, 

126817, 126818, 

41673103, 43958802, 

43958803, 47053001, 

47053002 

In review9

1. Use Patterns: 1=Terrestrial/Food; 2=Terrestrial/Feed. 

2. The available study was performed in the presence of around 8% acetonitrile. A new study is required to clarify 

uncertainties related to the rate of the process and the possible transformation products. 

3. Waived, based on the low vapor pressure and Henry’s Law Constant for fenpropathrin. 

4. High variability in the results from the study conducted earlier (with shorter half-lives) vs. the most recent study brings 

uncertainty to the environmental fate assessment. The registrant should submit a study conducted in three additional soils; a 

sandy loam soil should be included. 

5. The available study was performed with only one soil and for a period of only 2 months of anaerobic incubation. Data 

performed for a longer period of time will help the Agency to determine rates of transformation and presence of possible 

metabolites. Three additional soils are also required, for rate of transformation determination. 

6. No study has been submitted. The study is required. 

7. Two studies are available, performed in only one soil type (yielding half-lives of 78 and 67 days in a CA L). These 

studies are currently in review. A study conducted in one additional sediment type is required. 

8. There are available studies currently in review. The data requirement is considered unfulfilled until the study (studies) is 

(are) reviewed and deemed acceptable. 

9. Data requirement covered by submission of the Spray Drift Task Force. 

 50
7.9.2 Effects

For registration review, the following studies are being requested to fulfill any data gaps: 

Guideline Number: Non-Guideline 

Study Title: Endocrine Disruptor Screening Program

As required under FFDCA section 408(p), EPA has developed the Endocrine Disruptor 

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, 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 postapplication agricultural scenarios. This list should not be construed as a list of known or 

likely endocrine disruptors. 

Fenpropathrin is not among the group of 58 pesticide active ingredients on the initial list 

to be screened under the EDSP. Under FFDCA sec. 408(p) the Agency must screen all 

pesticide chemicals. Accordingly, EPA anticipates issuing future EDSP test orders/data 

call-ins for all pesticide active ingredients. 

For further information on the status of the EDSP, the policies and procedures, the list of 

67 chemicals, the test guidelines and the Tier 1 screening battery, please visit our 

website: http://www.epa.gov/endo/ . 

Guideline Number: 850-2100 

Study Title: Passerine Acute Avian Oral 

Although an acute avian oral study was received for the mallard duck, the Agency 

updated its data requirements in 40 CFR Part 158 (October 26, 2007) to include an acute 

oral toxicity study for both a passerine species and either a waterfowl or an upland game 

species. Prior to starting toxicity testing, a protocol will need to be provided for review. 

Many passerine species utilize agricultural fields, forests, residential areas and 

surrounding areas, and, therefore, have the potential to be exposed to pesticides used in 

agricultural, forest, and residential settings. It is likely that, for most pesticide use 

patterns, passerines are more likely to be exposed to pesticides than upland game species 

 51
and waterfowl. Passerines are smaller and have faster metabolisms than the waterfowl 

and upland game bird species traditionally used in avian toxicity tests which could impact 

their sensitivity to chemicals. 

Guideline Number: 850-1400 

Study Title: Fish Early Life Stage (Saltwater) 

No acceptable chronic studies for fenpropathrin have been submitted for marine fish. The 

acute toxicity of fenpropathrin to estuarine/marine fish and environmental fate properties 

indicates the potential for chronic exposure and effects to animals in this taxon, per 40 

CFR Part 158 data requirements (October 26, 2007). For example, the acute LC50 for 

freshwater fish (2.2 μg ai/L) is well below the 1.0 mg/L criterion specified in 40 CFR 

Part 158 for conditionally requiring this study. Furthermore, the persistence of 

fenpropathrin in water is expected to substantially exceed the 4-day half life criterion. 

Without this study, the Agency would have to presume chronic risk to listed and nonlisted estuarine/marine fish, but would not be able to quantify the risk. 

Guideline Numbers: Non-Guideline 

Study Title: Whole sediment chronic toxicity: invertebrates freshwater and marine 

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 fenpropathrin, available information indicates that 

benthic organisms may be exposed via run-off or spray drift applications used in 

agricultural, forest, and residential settings. Specifically, the peak sediment porewater 

EECs predicted for fenpropathrin (0.06 – 0.76 ppb) all exceed 0.1 of the acute LC/EC50 

(0.021 ppb for M. bahia), which satisfies one of the criteria for requiring chronic whole 

sediment toxicity testing under 40 CFR Part 158. Further, the expected half-life of 

fenpropathrin in sediment (67-78 days for anaerobic aquatic metabolism) is substantially 

greater than 40 CFR Part 158 criterion of 10 days. The third set of trigger criteria for 

requiring chronic testing (Kd > 50, or log KOW >3 or KOC > 1000) is also met for 

fenpropathrin (e.g., Kd values are 64-810, log KOW is 6, and KOC values are 13870-

85260). Finally, there the potential for persistent exposure from fenpropathrin in 

sediment is also indicated by open literature studies on pyrethroids (Weston et al. 2005, 

Amweg et al. 2006 and Ding et al. 2009). 

For sediment studies involving pyrethroids, 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 vs. infaunal species), physiology, and there is some evidence suggesting 

Hyalella is among the more sensitive invertebrates to some pyrethroids based on water 

column tests (Anderson et al. 2006, Maund et al., 2002). Fenpropathrin has the potential 

to enter estuarine/marine water bodies based on current usuage patterns that include 

coastal areas. Therefore, testing is required for Leptocheirus plumulosus, an 

estuarine/marine sediment-dwelling invertebrate species.

 52
Guideline Numbers: 850.4150 and 850.4250 

Study Title: Vegetative vigor and Seedling emergence, Tier I/Tier II 

No acceptable toxicity data are currently available to assess the risk of fenpropathrin to 

non-target terrestrial plants. Since fenpropathrin has residential outdoor uses, vegetative 

vigor and seedling emergence studies are required (40 CFR Part 158). These 

phytotoxicity data are needed to evaluate the level of pesticide exposure to non-target 

terrestrial and aquatic plants and to assess the impact of pesticides on endangered and 

threatened plants. 

Guideline Number: 850.4400 

Study Title: Aquatic Vascular Plant Growth-Lemna spp. Tier I/Tier II 

No acceptable studies for fenpropathrin have been submitted for vascular aquatic plants. 

The Agency has finalized its update to the data requirements in 40 CFR Part 158. In 

these updated data requirements, which were promulgated on October 26, 2007, vascular 

plant testing is required for pesticides such as fenpropathrin with outdoor uses. 

Guideline Number: 850.5400 

Study Title: Algal toxicity test, Tier I/Tier II 

No toxicity data are currently available to assess the risk of fenpropathrin to aquatic 

nonvascular plants. Since fenpropathrin has residential outdoor uses, Tier I/II aquatic 

nonvascular plant studies are required (40 CFR Part 158). These phytotoxicity data are 

needed to evaluate the level of pesticide exposure to non-target aquatic plants and to 

assess the impact of pesticides on endangered and threatened plants. 

Guideline Numbers: 850.1010 

Study Title: Aquatic Invertebrate Acute Toxicity (Hyalella)

Available information in the ECOTOX database indicates that the freshwater amphipod, 

Hyalella azteca, is substantially more sensitive to pyrethroids than Daphnia magna, the 

commonly tested freshwater invertebrate. Information on the acute toxicity of 

fenpropathrin to H. azteca was not identified in this problem formulation. Therefore, in 

order to ensure that risk to sensitive aquatic invertebrates are appropriately quantified, 

additional acute toxicity testing of H. azteca is needed (water column exposure, not 

sediment-spiked).

 53
Table 7.2 lists the status of the ecological effects data requirements for fenpropathrin. 

Table 7.2. Ecological Effects Data Requirements for Fenpropathrin

Data Requirement 

Use 

Pattern 

Does EPA Have 

Data To Satisfy 

This 

Requirement? 

(Yes, No, or 

Partially) 

Bibliographic 

Citation 

Must 

Additional 

Data Be 

Submitted 

Under FIFRA 

3(c)(2)(B)? 

§158.490 TERRESTRIAL ORGANISMS

71-1(a) Acute Avian Oral, Duck 1,2 Partially 249939 Yes1 

71-2(a) Acute Avian Diet, Quail 1,2 Yes 249939 No

71-2(b) Acute Avian Diet, Duck 1,2 Yes 249939 No 

71-3 Wild Mammal Toxicity 1,2 N/A 

71-4(a) Avian Reproduction Quail 1,2 Yes 425140-04, 265374 No 

71-4(b) Avian Reproduction Duck 1,2 Yes 265373 No 

71-5(a) Simulated Terrestrial Field Study 1,2 N/A 

71-5(b) Actual Terrestrial Field Study 1,2 N/A 

§158.630 AQUATIC ORGANISMS TESTING

72-1(a) Acute Fish Toxicity Bluegill 

 Acute Fish Toxicity Catfish 

1,2 

1,2 

Yes 

Yes 

249939 

249939 

No 

No 

72-1(b) Acute Fish Toxicity (TEP) * 1,2 Yes 250159 No

72-1(c) Acute Fish Toxicity Rainbow 

Trout 

1,2 Yes 249939 No 

72-2(a) Acute Aquatic Invertebrate 1,2 Yes 249939 No 

72-2(b) Acute Aquatic Invertebrate (TEP) * 1,2 Yes 250159 No 

72-3(a) Acute Est/Mar Toxicity Fish 1,2 Yes 249939 No 

72-3(b) Acute Est/Mar Toxicity Mollusk 1,2 Yes 409744-05 No 

72-3(c) Acute Est/Mar Toxicity Shrimp 1,2 Yes 409744-04 No 

72-3(d) Acute Est/Mar Toxicity Fish 

(TEP)* 

1,2 Yes 409744-06 No 

72-3(e) Acute Est/Mar Toxicity Mollusk 

(TEP) 

1,2 Yes 412952-01 No 

72-3(f) Acute Est/Mar Toxicity Shrimp 

(TEP) 

1,2 Yes 409744-05 No 

 54
Table 7.2. Ecological Effects Data Requirements for Fenpropathrin

Does EPA Have Must 

Data Requirement 

Use 

Pattern 

Data To Satisfy Additional 

This Data Be 

Requirement? Submitted 

(Yes, No, or 

Partially) 

Bibliographic Under FIFRA 

Citation 3(c)(2)(B)? 

72-4(a) Early Life Stage Fish 1,2 Yes (freshwater) 

No (saltwater) 

415259-01 

N/A 

No 

Yes 

72-4(b) Life Cycle Aquatic Invertebrate 

(freshwater) 

1,2 Yes 259678 No 

850.1350 Life Cycle Aquatic Invertebrate 

(saltwater) 

1,2 Yes 409744-07 No 

72-5 Life Cycle Fish 1,2 N/A N/A No 

72-6 Aquatic Organism Accumulation 1,2 NA 

72-7(1) Simulated Aquatic Field Study 1,2 NA 

72-7(b) Actual Aquatic Field Study 1,2 NA 

850.1730 Bioaccumulation in Fish 1,2 Yes 00153802, 00161672, 

00161673, 00163521 

No 

850.1950 Accumulation in Aquatic Nontarget Organisms 1,2 No NA No 

850.1010 Aquatic Invertebrate Acute 

Toxicity (Hyalella azteca) 

1, 2 No NA Yes 

850.1735 Whole sediment: acute freshwater 

invertebrates 

1, 2 Yes 470838-01 No 

850.1740 Whole sediment: acute marine 

invertebrates 

1, 2 No NA Held in reserve 

Whole sediment: chronic invertebrates 

freshwater (Hyalella azteca) 

1, 2 No NA Yes 

Whole sediment: chronic invertebrates 

freshwater (Chironomus dilutus) 

1, 2 No NA Yes 

Whole sediment: chronic invertebrates 

freshwater & marine (L. plumulosus) 

1, 2 No NA Yes 

§158.540 PLANT PROTECTION

122-1(a) Seed Germ, Seedling Emergence 1,2 No NA Yes 

122-2 Aquatic Plant Growth 1,2 No NA Yes 

122-1(b) Vegetative Vigor 1,2 No NA Yes 

123-1(a) Seed Germ./Seedling Emerg. 1,2 NA NA No2 

 55
Table 7.2. Ecological Effects Data Requirements for Fenpropathrin

Does EPA Have Must 

Data Requirement 

Use 

Pattern 

Data To Satisfy Additional 

This Data Be 

Requirement? Submitted 

(Yes, No, or 

Partially) 

Bibliographic Under FIFRA 

Citation 3(c)(2)(B)? 

123-1(b) Vegetative Vigor 1,2 NA NA No2 

123-2 Aquatic Plant Growth 1,2 NA NA No3 

124-1 Terrestrial Field Study 1,2 NA 

124-2 Aquatic Field Study 1,2 NA 

§158.490 NONTARGET INSECT TESTING

141-1 Honey Bee Acute Contact 1,2 Yes Atkins 1984 No 

141-2 Honey Bee Residue on Foliage 

(TEP) 

1,2 Yes 133103 No 

141-5 Field Test for Pollinators 1,2 NA 

1

 Data are required for one passerine species and either on waterfowl or one upland game bird species. At this time, only an 

acute oral test for a waterfowl species has been submitted. 

2

 Required if a tested terrestrial species exhibits a 25 percent or greater detrimental effect in the Tier I study. 3

 Required if a tested aquatic species exhibits a 50 percent or greater detrimental effect in a Tier I study. 

*Note: No further aquatic toxicity formulation (TEP) testing is required because sufficient data has been submitted and no 

outdoor use formulations contain known synergists. 

 56
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U.S. Environmental Protection Agency. 2000. Risk Characterization Handbook. 

Science Policy Council, U.S. Environmental Protection Agency, Washington, D.C. 

20460. EPA 100-B-00-002. December 2000. 

U.S. Environmental Protection Agency. 2002. Technical Basis for the derivation of 

Equilibrium Partitioning Sediment Guidelines (ESGs) for the Protection of Benthic 

Organisms: Nonionic Organics [Draft]. EPA Document No. 822R02041. October 2002. 

U.S. Environmental Protection Agency. 2004. Overview of the Ecological Risk 

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Agency. Endangered and Threatened Species Effects Determinations. Office of 

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U.S. Environmental Protection Agency. 2005. Generic Format and Guidance for the 

Level I Screening Ecological Risk Assessments Conducted in the Environmental Fate 

and Effects Division. Office of Pesticide Programs, Washington, D.C. January 24, 2005. 

U.S. Environmental Protection Agency. 2008. OPPTS 835.6100 Terrestrial Field 

Dissipation. EPA 712-C-08-020. October 2008. Office of Prevention, Pesticides, and 

Toxic Substances. United States Environmental Protection Agency. Available at 

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U.S. Environmental Protection Agency. 2009. A Set of Scientific Issues Being 

Considered by the EPA Regarding: Evaluation of the Common Mechanism of Action of 

Pyrethroid Pesticides. SAP Minutes No. 2009-07. FIFRA SAP Meeting held 6/16/09 in 

Arlington, VA. Meeting Minutes dated 9/9/09. 

U.S. Fish and Wildlife Service (USFWS) and National Marine Fisheries Service 

(NMFS). 1998. Endangered Species Consultation Handbook: Procedures for 

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Weston, D.P., J. You and M.J. Lydy. 2004. Distribution and Toxicity of SedimentAssociated Pesticides in Agriculture-Dominated Water Bodies of California’s Central 

Valley. Environ. Sci. Technol. 38, 2752-2759. 

Weston, D.P., R.W. Holmes, J. You and M.J. Lydy. 2005. Aquatic Toxicity Due to 

Residential Use of Pyrethroid Insecticides. Environ. Sci. Technol., 39 (24), pp 9778–

9784. 

Weston, D. 2007. Impacts of Pyrethroid Pesticides on Water Quality from Urban and 

Agricultural Sectors. Conference Proceedings; California Plant and Soil Conference: 

Opportunities for California Agriculture. California Chapter of the American Society of 

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pyrethroid pesticides to urban creeks. Environmental Pollution 157 (2009) 287–294. 

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Insecticides to the Sacramento-San Joaquin Delta of California. Environ. Sci. Technol. 

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9. Bibliography 

161-1 Hydrolysis 

MRID Citation Reference 

131438 Takahashi, N.; Mikami, N.; Yamada, H.; et al. (1983) Hydrolysis of 

Fenpropathrin in Aqueous Media: Doc. Code FM-30-0010. (Unpublished 

study received Oct 3, 1983 under 39398-16; prepared by Sumitomo 

Chemical Co., Ltd., Japan, submitted by Sumitomo Chemical America, 

Inc., New York, NY; CDL:251415-B) 

141320 Takahashi, N.; Mikami, N. (1984) The Response to EPA's Requirement 

Concerning Hydrolysis Studies of Fenpropathrin in aqueous Media. Ref. 

No. FM-30-0010. Unpublished study prepared by Sumitomo Chemical 

Co., Ltd. 32 p. 

42599901 Concha, M.; Shepler, K.; Ruzo, L. (1992) Hydrolysis of (Carbon 14- acid) 

and (Carbon 14-alcohol) Fenpropathrin at pH 5, 7 and 9: Lab Project 

Number: 334W. Unpublished study prepared by PTRL-West, Inc. 130 p. 

161-2 Photodegradation-water 

MRID Citation Reference 

42546401 Jalai-Araghi, K.; Ruzo, L.; Shepler, K. (1992) Photodegradation of carbon 

14|-acid and carbon 14|-alcohol Fenpropathrin in a Buffered Aqueous 

Solution at pH 5 by Natural Sunlight: Lab Project Number: 336W-1: 336W. 

Unpublished study prepared by PTRL-West, Inc. 103 p. 

137769 Takahashi, N.; Mikami, N.; Yamada, H.; et al. (1983) Photodegradation of 

Fenpropathrin in Water, and on Soil and Plant Foliage: Doc. Code Fm-30; 

Ref. No. -0011. (Unpublished study received Jan 15, 1984 under 39398-

17; prepared by Sumitomo Chemical Co., Ltd., Japan, submitted by 

Sumitomo Chemical America, Inc., New York, NY; CDL:252780-B) 

 161-3 Photodegradation-soil 

MRID Citation Reference 

137769 Takahashi, N.; Mikami, N.; Yamada, H.; et al. (1983) Photodegradation of 

Fenpropathrin in Water, and on Soil and Plant Foliage: Doc. Code Fm-30; 

Ref. No. -0011. (Unpublished study received Jan 15, 1984 under 39398-

17; prepared by Sumitomo Chemical Co., Ltd., Japan, submitted by 

Sumitomo Chemical America, Inc., New York, NY; CDL:252780-B) 

42546402 Concha, M.; Ruzo, L.; Shepler, K. (1992) Photodegradation of carbon 14|-

acid and carbon 14|-alcohol Fenpropathrin in/on Soil by Natural Sunlight: 

Lab Project Number: P344W-1: P344W. Unpublished study prepared by 

PTRL-West, Inc. 117 p. 

162-1 Aerobic soil metabolism 

MRID Citation Reference 

126821 or 

130867 

Noble, A.; Loveridge, D. (1976) Soil Percolation and Aqueous Die- away 

Studies with WL 41706: Group Research Report WKGR.0127.76. 

(Unpublished study received Apr 8, 1983 under 39398-16; prepared by 

Shell Research Ltd., Eng., submitted by Sumitomo Chemical American, 

Inc., New York, NY; CDL:249936-F) 

 62
126822 Roberts, T.; Standen, M.; Dutton, A. (1976) The Degradation of the 

Insecticide WL 41706 in Soil under Laboratory Conditions: Group 

Research Report WKGR.0061.76; Doc. Code FR-61-0014. (Unpublished 

study received Apr 8, 1983 under 39398-16; prepared by Shell Research 

Ltd., Eng., submitted by Sumitomo Chemical America, Inc., New York, 

NY; CDL:249936-G) 

126823 Mikami, N.; Sakata, S.; Yamada, H.; et al. (1983) Degradation of 

Fenpropathrin in Soil: Doc. Code FM-30-0008. (Unpublished study 

received Apr 8, 1983 under 39398-16; prepared by Sumitomo Chemical 

Co., Ltd., Japan, submitted by Sumitomo Chemical America, Inc., New 

York, NY; CDL:249936-H) 

129015 Roberts, T.; Standen, M. (1977) Degradation of the pyrethroid insecticide 

WL 41706 (~+?)-alpha-cyano-3-phenoxybenzyl 2,2,3,3- tetramethylcyclopropanecarboxylate, in soils. Pestic. Sci. 8: 600-610. (Also In unpublished 

submission received Jun 8, 1983 under 20954-EX-19; submitted by 

Zoecon Corp., Palo Alto, CA; CDL:250536-B) 

130868 Roberts, T.; Standen, M.; Dutton, A. (1980) The Degradation of the 

Insecticide WL 41706 in Soil under Laboratory Conditions: 

WKGR.0061.76. (Unpublished study received Sep 21, 1983 under 39398-

16; prepared by Shell Research, Ltd., Eng., submitted by Sumitomo 

Chemical America, Inc., New York, NY: CDL:251317-F) 

130869 Mikami, N.; Sakata, S.; Yamada, H.; et al. (1983) Degradation of 

Fenpropathrin in Soil: Doc. Code FM-30. (Unpublished study received 

Sep 21, 1983 under 39398-16; prepared by Sumitomo Chemical Co., Ltd., 

Japan, submitted by Sumitomo Chemical America, Inc., New York, NY; 

CDL:251317-G) 

142547 Mikami, N; Sakata, S.; Yamada, H. (1984) The Response to EPA's Requirement Concerning Soil Studies of Fenpropathrin (Danitol): Data on 

Degradation in Soils under Aerobic Conditions at Shorter Time Points: 

FM-40-0014 Unpublished study prepared by Sumitomo Chemical Co., 

LTD. 5 p. 

41525902 Cranor, W. (1990) Aerobic Soil Metabolism of Benzyl-(Carbon 14)|-- 

Fenpropathrin: Lab Project I.D.: 34586. Unpublished study pre- pared by 

Analytical Bio-Chemistry Laboratories, Inc. 98 p. 

162-2 Anaerobic soil metabolism 

MRID Citation Reference 

42546403 Daly, D.; Williams, M. (1990) Anaerobic Soil Metabolism of carbon 14|-

Fenpropathrin: Lab Project Number: 38182. Unpublished study prepared 

by Analytical Bio-Chemistry Labs, Inc. 687 p. 

162-3 Anaerobic aquatic metab. 

MRID Citation Reference 

126821 Noble, A.; Loveridge, D. (1976) Soil Percolation and Aqueous Die- away 

Studies with WL 41706: Group Research Report WKGR.0127.76. 

(Unpublished study received Apr 8, 1983 under 39398-16; prepared by 

Shell Research Ltd., Eng., submitted by Sumitomo Chemical American, 

Inc., New York, NY; CDL:249936-F) 

44370003 Kaman, R. (1995) An Anaerobic Aquatic Soil Metabolism Study with 

(Phenoxyphenyl-(carbon 14))-Fenpropathrin: Lab Project Number: 92-0010: 

5164-92-0010-EF-001: 5164-92-0010-EF-000. Unpublished study prepared 

by Ricerca, Inc. 191 p. 

44370004 Kaman, R. (1994) An Anaerobic Aquatic Soil Metabolism Study with 

 63
(Cyclopropyl-1-(carbon 14))-Fenpropathrin: Lab Project Number: 92-0011: 

5164-92-0011-EF-002: 5164-92-0011-EF-000. Unpublished study prepared 

by Ricerca, Inc. 232 p. 

163-1 Leach/adsorp/desorption 

MRID Citation Reference 

126819 Roberts, T.; Hitchings, E.; Jackson, C. (1976) The Leaching Behaviour of 

WL 41706 in Laboratory Soil Columns: Group Research Re- port 

WKGR.0070.76; Doc. Code FR-61-0012. (Unpublished study received Apr 8, 

1983 under 39398-16; prepared by Shell Research Ltd., Eng. submitted by 

Sumitomo Chemical America, Inc., New York, NY; CDL:249936-D) 

126820 Mikami, N.; Yoshimura, J.; Yamada, H.; et al. (1983) Leaching Behaviour of 

Fenpropathrin in Soil: Doc. Code FM-30-0007. (Unpublished study received 

Apr 8, 1983 under 39398-16; prepared by Sumitomo Chemical Co., Ltd., 

Japan, submitted by Sumitomo Chemi- cal America, Inc., New York, NY; 

CDL:249936-E) 

126821 or 

130867 

Noble, A.; Loveridge, D. (1976) Soil Percolation and Aqueous Die- away 

Studies with WL 41706: Group Research Report WKGR.0127.76. 

(Unpublished study received Apr 8, 1983 under 39398-16; prepared by Shell 

Research Ltd., Eng., submitted by Sumitomo Chemical American, Inc., New 

York, NY; CDL:249936-F) 

130866 Roberts, T.; Hitchings, E.; Jackson, C.; et al. (1980) The Leadhing Behavior 

of WL 41706 in Laboratory Soil Columns: WKGR.0070.76. (Unpublished 

study received Sep 21, 1983 under 39398-16; prepared by Shell Research 

Ltd., Eng., submitted by Sumitomo Chemical America, Inc., New York, NY; 

CDL:251317-C) 

42584101 Lee, D. (1992) Adsorption and Desorption of Fenpropathrin to Soils: Lab 

Project Number: 5057-91-0317-EF-001. Unpublished study prepared by 

Ricerca, Inc. 108 p. 

44370002 Shelby, D. (1996) Report Amendment to: Adsorption and Desorption of 

Fenpropathrin to Soils MRID #42584101: Lab Project Number: 5057-91-

0317-EF-001-001: 91-0317. Unpublished study prepared by Ricerca, Inc. 89 

p. 

164-1 Terrestrial field dissipation 

MRID Citation Reference 

151204 Fujie, G. (1985) Fenpropathrin Dissipation in Citrus Orchard Soil. 

Unpublished study prepared by Chevron Chemical Co. 32 p. 

163828 Fujie, G.; Leary, J.; Abell, J. (1985) Fenpropathrin Dissipation in Citrus 

Orchard Soil. Unpublished study prepared by Chevron Chemical Co. 35 p. 

163829 Fujie, G.; Leary, J.; Abell, J. (1986) Field Dissipation of Fenpropathrin in 

Michigan, Mississippi, and New York Soils. Unpublished study prepared by 

Chevron Chemical Co. 204 p. 

41525904 Fujie, G. (1990) Field Dissipation Study with Fenpropathrin on Grapes in 

California: Lab Project I.D.: 1641-88-7209. Unpublished study prepared by 

Chevron Chemical Co., Agricultural Chemical Div. 481 p. 

41525905 Fujie, G. (1990) Field Dissipation Study with Fenpropathrin on Apples in New 

York: Lab Project I.D.: 1641-88-7208. Unpublished study prepared by 

Chevron Chemical Co., Agricultural Chemicals Div. 342 p. 

41679601 Fujie, G. (1990) Field Dissipation Study with Fenpropathrin on Apples in 

Washington: Lab Project Number: 1641/88/7207. Un- published study 

prepared by Chevron Chemical Co. 455 p. 

42311401 Fujie, G. (1992) Field Dissipation Study with Fenpropathrin on Cotton in 

 64
Mississippi: Lab Project Number: 1641/89/7341. Unpublished study prepared 

by Chevron Chemical Co. 587 p. 

42311402 Fujie, G. (1991) Field Dissipation Study with Fenproppathrin on Bare Ground 

in California: Lab Project Number: 1641/89/7340. Unpublished study prepared 

by Chevron Chemical Co. 411 p. 

42311403 Fujie, G. (1992) Discussion on Dississipation of Fenpropathrin in Soil Under 

Field Conditions: Lab Project Number: 1641/10435. Unpublished study 

prepared by Chevron Chemical Co. 13 p. 

Dissipation on vineyard soils, citrus orchard soils 

165-4 Bioaccumulation in fish 

MRID Citation Reference 

153802 Forbis, A.; Shaffer, S. (1985) Uptake, Depuration and Bioconcentration of 

[Cyclopropyl-1-(Carbon-14)] and [Benzyl-1-(Carbon-14)] Fenpropathrin by 

Bluegill Sunfish (Lepomis macrochirus): ABC Final Report #32007. 

Unpublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 65 

p. 

161672 Forbis, A.; Shaffer, S. (1986) Uptake, Depuration and Bioconcentra- tion of 

[Cyclopropyl-1-[carbon 14]] and [Benzyl-1-[carbon 14]] Fenpropathrin by 

Bluegill Sunfish (Lepomis macrochirus): ABC Final Report # 32007: [Includes 

Comments of Sumitomo Chemical Co. and Revised Residue Data by Chevron 

Chemical Co.]. Unpub- lished study prepared by Analytical Bio-Chemistry 

Laboratories, Inc. 72 p. 

161673 Takimoto, Y.; Ohshima, M.; Matsuda, T.; et al (1985) Accumulation and 

Metabolism of [Benzyl-1-[carbon 14]]-fenpropathrin in Carp (Cyprinus carpio). 

Unpublished study prepared by Sumitomo Chemical Ltd., Laboratory of 

Biochemistry and Toxicology. 20 p. 

163521 Cheng, H. (1986) Characterization of [Carbon 14] Residues in Blue- gill 

Sunfish Treated with [Carbon 14]-Fenpropathrin (Revised). Unpublished study 

prepared by Chevron Chemical Co. 15 p. 

201-1 Droplet size spectrum 

MRID Citation Reference 

40024621 Akesson, N. (1986) Danitol 2.4 EC Spray Drift Determination Droplet Size 

Spectrum Study: Laboratory Project Identification 8613397. Unpublished study 

prepared by Univ. of California, Davis. 35 p. 

Non Guideline Selections 

71368 Shell Development Company (1975) Determination of Individual or Combined 

Residues of the Cyano Pyrethroids on Soil: GLC-Alkali Flame Ionization 

Detector. Method MMS-R-425-1 dated Apr 1975. (Unpublished study received 

Feb 1, 1976 under 6G1755; CDL: 099958-I) 

97456 Tu, C.M. (1980) Influence of five pyrethroid insecticides on microbial populations 

and activities in soil. Microbial Ecology 5:321-327. (Also In unpublished 

submission received Mar 17, 1982 under 59-200; submitted by Burroughs 

Wellcome Co., Research Triangle Park, N.C.; CDL:247048-D) 

100138 Shell Development Co. (1975) Determination of Individual or Combined 

Residues of the Cyano Pyrethroids on Soil: GLC-alkal: Flame Ionization 

Detector: MMS-R-425-1. (Unpublished study re- ceived May 9, 1978 under 201-

401; CDL:097083-L) 

126817 Akutu, S.; Matsuo, M.; Miyamoto, J. (1980) Method of Analysis of S- 3206 in 

Water: Doc. Code FA-00-0008. (Unpublished study re- ceived Apr 8, 1983 under 

 65
39398-16; prepared by Sumitomo Chemical Co., Ltd., Japan, submitted by 

Sumitomo Chemical America, Inc., New York, NY; CDL:249936-B) 

126818 Shell Research Ltd. (19??) Determination of Residues of WL 41706 in Soil: 

WAMS 228-1. (Unpublished study received Apr 8, 1983 under 39398-16; 

submitted by Sumitomo Chemical America, Inc., New York, NY; CDL:249936-C) 

126824 Miyamoto, J. (1980) Comments on the Metabolic Fate of 3-Phenoxybenzoic Acid 

and 2,2,3,3-Tetramethylcyclopropanecarboxylic Acid in the Soil: Doc. Code FM00-0006. (Unpublished study received Apr 8, 1983 under 39398-16; prepared by 

Sumitomo Chemical Co., Ltd., Japan, submitted by Sumitomo Chemical 

America, Inc., New York, NY; CDL:249936-I) 

130870 Miyamoto, J. (19??) Comments on the Metabolic Fate of 3-Phenoxybenzoic Acid 

and 2,2,3,3-Tetramethylcyclopropanecarboxylic Acid in Soil. (Unpublished study 

received Sep 21, 1983 under 39398-16; submitted by Sumitomo Chemical 

America, Inc., New York, NY; CDL: 251317-H) 

43958802 Wiens, A. (1995) Independent Lab Validation of the Methods for Quantitation of 

Fenproprathrin (sic) in Hydrosoil and Pond Water: Lab Project Number: 1466-B: 

1466-B-1: RM-22S-5. Unpublished study prepared by Analytical Development 

Corp. 115 p. 

43958803 Wiens, A. (1995) Independent Lab Validation of the Method for Quantitation of 

Fenproprathrin (sic) in Soil: Lab Project Number: 1466-A: 1466-A-1: RM-22S-4. 

Unpublished study prepared by Analytical Development Corp. 57 p. 

126816 Sumitomo Chemical America, Inc. (1983) Physico-chemical Proper- ties, 

Stability, Decomposition Rate in Alkaline Solution, Active Ingredient, 

Manufacturing Process, GLC Determination and Analytical Method for the 

Determination of Impurities: S-3206|. (Compilation; unpublished study received 

Apr 8, 1983 under 39398-16; CDL:249936-A) 

130865 Sumitomo Chemical America, Inc. (1983) Physico-chemical Properties of S-3206 

T.G. (Compilation; unpublished study received Sep 21, 1983 under 39398-16; 

CDL:251317-A) 

131437 Sumitomo Chemical Co., Ltd. (1983) Partition Coefficient (n-Octanol/Water) of 

Fenpropathrin: Doc. Code FP-30-0016. (Unpublished study received Oct 3, 1983 

under 39398-16; submitted by Sumitomo Chemical America, Inc., New York, NY; 

CDL:251415-A) 

137768 Mikami, N.; Miyamoto, J. (1983) The Response to EPA's Requirement 

Concerning Soil Studies of Fenpropathrin (Danitol): Data on the Half-life and Kd 

Calculations, and 0.33 Bar Soil Moisture: Doc. Code FM-30; Ref. No. -0013. 

(Unpublished study received Jan 15, 1984 under 39398-17; prepared by 

Sumitomo Chemical Co., Ltd., Japan, submitted by Sumitomo Chemical 

America, Inc., New York, NY; CDL:252780-A) 

71-1 Avian Single Dose Oral Toxicity 

MRID Citation Reference 

127370 Fink, R. (1975) Acute Oral LD50: Mallard Ducks: SD 41706: Project No. 109-

110; Doc. Code FW-51-0003. Final rept. (Unpublished study received Apr 8, 

1983 under 39398-16; prepared by Truslow Farms, Inc., submitted by 

Sumitomo Chemical America, Inc., New York, NY; CDL:249939-D) 

71-2 Avian Dietary Toxicity 

MRID Citation Reference 

127371 Fink, R. (1975) Eight-day Dietary LC50: Mallard Ducks: SD 41706: Project No. 

 66
109-109; Doc. Code FW-51-0001. Final rept. (Un- published study received Apr 

8, 1983 under 39398-16; prepared by Truslow Farms, Inc., submitted by 

Sumitomo Chemical America, Inc., New York, NY; CDL:249939-E) 

127787 Fink, R. (1975) Eight-day Dietary LD50: Bobwhite Quail: SD 41706: Project No. 

109-108; Doc. Code FW-51-0002. Final rept. (Un- published study received Apr 

8, 1983 under 39398-16; prepared by Truslow Farms, Inc., submitted by 

Sumitomo Chemical America, Inc., New York, NY; CDL:249939-F) 

71-4 Avian Reproduction 

MRID Citation Reference 

127788 Fink, R. (1975) One-generation Reproduction Study: Mallard Duck: SD 41706: 

Project No. 109-116; FW-51-0004. Final rept. (Un- published study received 

Apr 8, 1983 under 39398-16; prepared by Truslow Farms, Inc., submitted by 

Sumitomo Chemical America, Inc., New York, NY; CDL:249939-G) 

127789 Fink, R. (1975) One-generation Reproduction Study: Bobwhite Quail: SD 

41706: Project No. 109-115; FW-51-0005. Final rept. (Unpublished study 

received Apr 8, 1983 under 39398-16; prepared by Truslow Farms, Inc., 

submitted by Sumitomo Chemical America, Inc., New York, NY; CDL:249939-

H) 

163810 Beavers, J. (1986) Fenpropathrin Technical: A One-generation Reproduction 

Study with the Mallard (Anas platyrhyrchos) Final Report: Laboratory Project Id. 

162-158. Unpublished study prepared by Wildlife International Ltd. in 

cooperation with Chevron Chemical Co. 121 p. 

163811 Beavers, J. (1986) Fenpropathrin Technical: A One-generation Re- production 

Study with the Bobwhite (Colinus Virginianus) Final Report: Laboratory Project 

Id. 162-157. Unpublished study prepared by Wildlife International Ltd. in 

cooperation with Chevron Chemical Co. 140 p. 

42514001 Beavers, J.; Lattin, A.; Smith, G. et al. (1990) Fenpropathrin: A One-generation 

Reproduction Study with the Northern Bobwhite (Colinus virginianus) Danitol 

2.4 EC Spray|: Lab Project Number: 203-102. Unpublished study prepared by 

Wildlife Int'l Ltd. 110 p. 

71-5 Simulated or Actual Field Testing 

MRID Citation Reference 

42514002 Johnson, G.; Krueger, H.; Jaber, M. (1987) Danitol 2. 4 EC Spray: A Residue 

Monitoring Study in Apple Orchards in the Hudson River Valley of New York 

State to Assess Exposure to Avian Species under Standard Agricultural Use 

Conditions: Lab Project Number: 162-178. Unpublished study prepared by 

Wildlife Int'l Ltd. 105 p. 

42514003 Johnson, G.; Krueger, H.; Jaber, M. (1987) Danitol 2. 4 EC Spray: A Residue 

Monitoring Study in Apple Orchards in the Yakima Valley of Washington State 

to Assess Exposure to Avian Species under Standard Agricultural Use 

Conditions: Lab Project Number: 162-179. Unpublished study prepared by 

Wildlife Int'l Ltd. 93 p. 

 67
72-1 Acute Toxicity to Freshwater Fish 

MRID Citation Reference 

71642 Shell Chemical Company (1975) Toxicity of the Pyrethroid Insecticides, SD 

43775 and SD 41706, to Fish. (Unpublished study received Apr 9, 1981 under 

6G1755; CDL:099983-S) 

74131 Shell Chemical Company (1975) Toxicity of the Pyrethroid Insecticides, SD 

43775 and SD 41706, to Fish. (Compilation; unpublished study received Jan 

15, 1979 under 201-401; CDL:099947-E) 

100108 Shell Oil Co. (1975) SD 43775: Toxicity in Fish|. (Compilation; unpublished 

study received Jan 15, 1979 under 201-401; CDL: 097755-C) 

109833 Shell Chemical Co. (1975) Toxicity of the Pyrethroid Insecticides, SD 43775 

and SD 41706, to Fish. (Compilation; unpublished study received Mar 8, 1976 

under 201-EX-50; CDL:095407-P) 

121829 Shell Chemical Co. (1975) Toxicity of SD 43775 and SD 41706 to Fish|. 

(Compilation; unpublished study received Oct 6, 1977 under 201-401; 

CDL:096385-Y) 

127790 LeBlanc, G.; Sousa, J. (1981) Acute Toxicity of S-3206 TG to Rainbow Trout 

(Salmo gairdneri): Report #BW-81-8-987; Doc. Code FW- 11-0017. 

(Unpublished study received Apr 8, 1983 under 39398- 16; prepared by EG & 

G, Bionomics, submitted by Sumitomo Chemical America, Inc., New York, NY; 

CDL:249939-I) 

127791 LeBlanc, G.; Sousa, J. (1981) Acute Toxicity of S-3206 TG to Bluegill (Lepomis 

macrochirus): Report #BW-81-8-988; Doc. Code FW- 11-0020. (Unpublished 

study received Apr 8, 1983 under 39398- 16; prepared by EG & G, Bionomics, 

submitted by Sumitomo Chemi- cal America, Inc., New York, NY; CDL:249939-

J) 

127792 LeBlanc, G.; Sousa, J. (1981) Acute Toxicity of S-3206 TG to Channel Catfish 

(Ictalurus punctatus): Report #BW-81-8-989; Doc. Code FW-11-0018. 

(Unpublished study received Apr 8, 1983 under 39398-16; prepared by EG & 

G, Bionomics, submitted by Sumitomo Chemical America, Inc., New York, NY; 

CDL:249939-K) 

128349 LeBlanc, G.; Sousa, J. (1981) Acute Toxicity of S-3206 2.4 Lb/G EC to Bluegill 

...: Report #BW-81-8-985; Doc. Code FW-11-0019. (Unpublished study 

received May 11, 1983 under 39398-16; pre- pared by EG & G, Bionomics, 

submitted by Sumitomo Chemical America, Inc., New York, NY; CDL:250159-L) 

128350 LeBlanc, G.; Sousa, J. (1981) Acute Toxicity of S-3206 2.4 Lb/G EC to Channel 

Catfish .Report #BW-81-8-979; Doc. Code FW-11- 0022. (Unpublished study 

received May 11, 1983 under 39398-16; prepared by EG & G, Bionomics, 

submitted by Sumitomo Chemical America, Inc., New York, NY; CDL:250159-

M) 

128471 LeBlanc, G.; Sousa, J. (1981) Acute Toxicity of S-3206 2.4 Lb/G EC to 

Rainbow Trout . Report #BW-81-8-984; Doc. Code FW-11-0021. (Unpublished 

study received May 11, 1983 under 39398-16; pre- pared by EG & G, 

Bionomics, submitted by Sumitomo Chemical America, Inc., New York, NY; 

CDL:250159-K) 

41068002 Coats, J.; O'Donnell-Jeffery, N. (1979) Toxicity of four synthetic pyrethroid 

insecticides to rainbow trout. Bulletin of Environmental Contamination and 

Toxicology 23:250-255. 

 68
72-2 Acute Toxicity to Freshwater Invertebrates 

MRID Citation Reference 

127795 LeBlanc, G.; Surprenant, D. (1981) Acute Toxicity of S-3206 TG to the Water 

Flea (Daphnia magna): Report #BW-81-8-996; Doc. Code FW-11-0015. 

(Unpublished study received Apr 18, 1983 under 39398-16; prepared by EG & 

G, Bionomics, submitted by Sumitomo Chemical America, Inc., New York, NY; 

CDL:249939-N) 

128472 LeBlanc, G.; Surprenant, D. (1981) Acute Toxicity of S-3206 2.4 Lb/ G EC to 

the Water Flea ...: Report #BW-81-8-997; Doc. Code FW- 11-0016. 

(Unpublished study received May 11, 1983 under 39398- 16; prepared by EG & 

G, Bionomics, submitted by Sumitomo Chemical America, Inc., New York, NY; 

CDL:250159-N) 

72-3 Acute Toxicity to Estuarine/Marine Organisms 

MRID Citation Reference 

127793 Ward, G. (1981) Acute Toxicity of S-3206 T.G. to Sheepshead Minnows 

(Cyprinodon variegatus): Report No. BP-81-7-114; Doc. Code FW- 11-0013. 

(Unpublished study received Apr 8, 1983 under 39398- 16; prepared by EG & 

G Bionomics, submitted by Sumitomo Chemical America, Inc., New York, NY; 

CDL:249939-L) 

127796 Ward, G. (1981) Acute Toxicity of S-3206 T.G. to Pink Shrimp (Penaeus 

duorarum): Report No. BP-81-7-124; Doc. Code FW-11-0012. (Unpublished 

study received Apr 8, 1983 under 39398-16; prepared by EG & G Bionomics, 

submitted by Sumitomo Chemical America, Inc., New York, NY; CDL:249949-

O) 

127797 Ward, G. (1981) Acute Toxicity of S-3206 T.G. to Fiddler Crabs (Uca pugilator): 

Report No: BP-81-7-112; Doc. Code FW-11-0014. (Un- published study 

received Apr 8, 1983 under 39398-16; prepared by EG & G Bionomics, 

submitted by Sumitomo Chemical America, Inc., New York, NY; CDL:249939-

P) 

40974403 Dionne, E. (1988) Acute Toxicity of Danitol Technical to Eastern Oysters 

(Crassostrea virginica): Study # 981.0287.6119.504; Rept. #87-9-2465. 

Unpublished study prepared by Springborn Life Sciences, Inc. 54 p. 

40974404 Hoberg, J. (1987) Acute Toxicity of Carbon 14|-Danitol Technical to Mysid 

Shrimp (Mysidopsis bahia): Study #981.0287.6117.510; Rept. #87-8-2470. 

Unpublished study prepared by Springborn Life Sciences, Inc. 53 p. 

40974405 Hoberg, J. (1987) Acute Toxicity of Danitol 2.4 EC to Mysid Shrimp (Mysidopsis 

bahia): Study #981.0287.6116.510: Rept. #87-7-2522. Unpublished study 

prepared by Springborn Life Sciences, Inc. 48 p. 

40974406 Nicholson, R. (1987) Acute Toxicity of Danitol 2.4 EC to Sheepshead Minnow 

(Cyprinodon variegatus): Study #981.0287.6115.500; Rept. # 87-7-2447. 

Unpublished study prepared by Springborn Life Sciences, Inc. 45 p. 

41295201 Dionne, E. (1988) Acute Toxicity of Danitol 2.4 EC to Eastern Oysters 

(Crassostrea virginica) under Flow-through Conditions: Lab Project Number: 

981-0278-6118-504. Unpublished study prepared by Chevron Chemical Co. 63 

p. 

 69
72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle 

Study 

MRID Citation Reference 

153801 Forbis, A.; Burgess, D.; Bunch, B. (1985) Chronic Toxicity of [Cyclopropyl-1-

(Carbon-14)] Fenpropathrin to Daphnia magna under Flow-through Test 

Conditions: Final Report #32547. Unpublished study prepared by Analytical 

Bio-Chemistry Laboratories, Inc. 26 P. 

40974407 Hoberg, J.; Surprenant, D. (1988) Chronic Toxicity of Carbon 14|- Danitol 

Technical to Mysid Shrimp (Mysidopsis bahia): Study # 981.0287.6120.530; 

Rept. #87-11-2544. Unpublished study pre- pared by Springborn Life Sciences, 

Inc. 74 p. 

72-5 Life cycle fish 

MRID Citation Reference 

41525901 Dionne, E.;Surprenant, D. (1990) The Chronic Toxicity of Fenpropathrin to the 

Fathead Minnow (Pimephales promelas): Lab Study No.: 981-0687-6122-122: 

CEHC Reference No. 87-155. Unpublished study prepared by Springborn 

Laboratories, Inc., Environmental Sciences Div. 158 p. 

42360001 Dionne, E.; Suprenant, D. (1992) The Chronic Toxicity of Fenpropathrin to the 

Fathead minnow (Pimephales promelas): Supplement to: Lab Project Number: 

89-1-2913. Unpublished study prepared by Springborn Labs., Inc. 328 p. 

43605301 Dionne, E. (1995) The Chronic Toxicity of Fenpropathrin to the Fathead 

Minnow (Pimephales promelas): Supplement II: Raw Data for "Fish Length and 

Reproduction, Diluter Calibration, and Control Solutions Analytical 

Measurements": Lab Project Numbers: 981.0687.6122.122: 981-6122: 981-

6122-122. Unpublished study prepared by Springborn Labs., Inc. 72 p. 

43605302 Ginevan, M. (1995) The Chronic Toxicity of Fenpropathrin to the Fathead 

Minnow (Pimephales promelas): Supplement III: A Statistical Reevaluation of 

Data From the Study: Lab Project Number: V-11106. Unpublished study 

prepared by M.E. Ginevan & Associates. 61 p. 

72-7 Simulated or Actual Field Testing 

MRID Citation Reference 

71642 Shell Chemical Company (1975) Toxicity of the Pyrethroid Insecticides, SD 

43775 and SD 41706, to Fish. (Unpublished study received Apr 9, 1981 under 

6G1755; CDL:099983-S) 

42378701 Flanagan, J. (1992) Letter Sent to Office of Pesticide Programs, dated June 24, 

1992: Regarding an Ongoing Study Indicating Fenpropathrin may have Caused 

Effects on Aquatic Organisms in a Simulated Aquatic Field Study (Mesocosm). 

Prepared by Valent. 9 p. 

42800101 Springer, T. (1993) Simulated Aquatic Field Study Guideline Reference No. 72-

2 Preliminary Summary Biological Data: Fenpropathrin: Lab Project Number: 

263-125. Unpublished study prepared by Wildlife International, Ltd. 111 p. 

43958801 Springer, T.; Anderson, D.; Krueger, H. (1996) An Evaluation of the Impact of 

Fenpropathrin Insecticide Exposure on Aquatic Mesocosm Ecosystems: 

Amended Report: Lab Project Number: 263-125: VP-10056: 

263/031292/DT2A/CYA9. Unpublished study prepared by Wildlife International 

Ltd. 2169 p. 

 70
81-1 Acute oral toxicity in rats 

MRID Citation Reference 

127342 Hiromori, T.; Misaki, Y.; Seki, T.; et al. (1983) Acute Oral Toxicity of S-3206 

(91.8%) in Rats: Doc. Code FT-30-0081. (Unpublished study received Apr 8, 

1983 under 39398-16; prepared by Sumitomo Chemical Co., Ltd., Japan, 

submitted by Sumitomo Chemical America, Inc., New York, NY; CDL:249937-

A) 

127343 Kohda, H.; Miyamoto, J. (1975) Acute Oral Toxicity of S-3206 in Rats: Doc. 

Code FT-50-0018. (Unpublished study received Apr 8, 1983 under 39398-16; 

prepared by Sumitomo Chemical Co., Ltd., Japan, submitted by Sumitomo 

Chemical America, Inc., New York, NY; CDL:249937-B) 

127344 Hiromori, T.; Misaki, Y.; Ito, S.; et al. (1982) Acute Oral Toxicity of S-3206 in 

Rats: Doc. Code FT-20-0076. (Unpublished study received Apr 8, 1983 under 

39398-16; prepared by Sumitomo Chemical Co., Ltd., submitted by Sumitomo 

Chemical America, Inc., New York, NY; CDL:249937-C) 

127345 Kohda, H.; Kadota, T.; Miyamoto, J. (1980) Acute Oral Toxicity of S-3206 

Technical in Mice: Doc. Code FT-50-0035. (Unpublished study received Apr 8, 

1983 under 39398-16; prepared by Sumitomo Chemical Co., Ltd., Japan, 

submitted by Sumitomo Chemical America, Inc., New York, NY; CDL:249937-

D) 

127346 Hara, S.; Suzuki, T.; Miyamoto, J. (1980) Acute Oral Toxicity of S-3206 in 

Rabbits: Doc. Code FT-00-0039. (Unpublished study received Apr 8, 1983 

under 39398-16; prepared by Sumitomo Chemical Co., Ltd., Japan, submitted 

by Sumitomo Chemical America, Inc., New York, NY; CDL:249937-E) 

127347 Pence, D.; Cameron, J.; Weatherholtz, W. (1979) Oral Dose Range Finding 

Study in Dogs: S-3206: Project No. 343-123; Doc. Code FT-91-0025. Final rept. 

(Unpublished study received Apr 8, 1983 under 39398-16; prepared by 

Hazleton Laboratories America, Inc., submitted by Sumitomo Chemical 

America, Inc., New York, NY; CDL:249937-F) 

127348 Misaki, Y.; Kohda, H.; Suzuki, T.; et al. (1981) Acute Oral Toxicity of Two 

Impurities of S-3206 (Technical) in Mice: Doc. Code FT-00-0044. (Unpublished 

study received Apr 8, 1983 under 39398-16; prepared by Sumitomo Chemical 

Co., Ltd., Japan, sub- mitted by Sumitomo Chemical America, Inc., New York, 

NY; CDL: 249937-G) 

127349 Misaki, Y.; Kohda, H.; Suzuki, T.; etal. (1981) Acute Oral Toxicity of 2,2,3,3-

Tetramethylcyclopropane Carboxylic Anhydride in Mice: Doc. Code FT-90-

0045. (Unpublished study received Apr 8, 1983 under 39398-16; prepared by 

Sumitomo Chemical Co., Ltd., Japan, submitted by Sumitomo Chemical 

America, New York, NY; CDL: 249937-H) 

127353 Kohda, H.; Miyamoto, J. (1979) Acute Oral Toxicity of S-3206 10% Emulsifiable 

Concentrate in Mice: Doc. Code FT-80-0020. (Unpublished study received Apr 

8, 1983 under 39398-16; prepared by Sumitomo Chemical Co., Ltd., Japan, 

submitted by Sumitomo Chemical America, Inc., New York, NY; CDL:249937-L) 

127361 Stevenson, D.; Hend, R.; Butterworth, S. (1976) Toxicity Studies on the 

Insecticide WL 41706: A Short-term Feeding Study in Rats: TLGR.0041.76. 

(Unpublished study received Apr 8, 1983 under 39398-16; prepared by Shell 

Research Ltd., Eng., submitted by Sumitomo Chemical America, Inc., New 

York, NY; CDL:249937-T) 

128341 Johnson, D.; Myer, J.; Moxon, P.; et al. (1981) Acute Oral (LD50) Toxicity Study 

in Rats (EPA 8/78): (S-3206 2.4 Lb/G EC): IRDC Study No. 491-003; Doc. 

Code FT-11-0052. (Unpublished study received May 11, 1983 under 39398-16; 

prepared by International Research and Development Corp., submitted by 

Sumitomo Chemical America, Inc., New York, NY; CDL:250159-C) 

42799801 Kiplinger, G. (1992) Acute Oral Toxicity Study in Albino Rats with Danitol 2.4 

 71
EC (Formulation CC-17228): Lab Project Number: WIL-194002. Unpublished 

study prepared by WIL Research Labs., Inc. 114 p. 

43758602 Gabriel, D. (1995) Acute Oral Toxicity, LD50--Rats: TC-136 (Danitol/Orthene 

GH TR) Concentrate: Formula #147-043: Lab Project Numbers: 94-8126A: 

AOT-200. Unpublished study prepared by Biosearch Inc. 24 p. 

141-1 Honey bee acute contact 

MRID Citation Reference 

164240 Atkins, E. (1984) Honey Bee Bioassays of Valencia Orange Foliage Residues 

of Fenpropathrin, Danitol, Sprays on Citrus. Unpublished study prepared by 

University of California. 4 p. 

141-2 Honey bee residue on foliage 

MRID Citation Reference 

164240 Atkins, E. (1984) Honey Bee Bioassays of Valencia Orange Foliage Residues 

of Fenpropathrin, Danitol, Sprays on Citrus. Unpublished study prepared by 

University of California. 4 p. 

142-3 Simulated or Actual Field Testing 

MRID Citation Reference 

71647 Johansen, C. (1975) Cooperator Performance Report|. (Unpublished study 

received Apr 9, 1981 under 6G1755; submitted by Shell Chemical Co., 

Washington, D.C.; CDL:099983-Y) 

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) 

143-2 Toxicity to Predators and Parasites in Fruit and Nut 

Crops 

MRID Citation Reference 

40024620 Whitehead, C. (1986) The Effect of Danitol 2.4 EC on Several Beneficial 

Insects and Mites in Various Crops: Laboratory Project Identification 8613400. 

Unpublished study prepared by Chevron Chemical Co. 104 p. 

850.1735 Whole sediment: acute freshwater invertebrates 

MRID Citation Reference 

47083801 Pearson, F. (2007) Pyrethroid Working Group (PWG) Summary of Results from 

California Sediment Samples Analyzed for Pyrethroids. Project Number: 

PWG/2007/001. Unpublished study prepared by Morse Laboratories. 10 p. 

 72
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 835.2240 

Study Title: Aqueous Photolysis 

Rationale for Requiring the Data 

According to 40 CFR Part 158, Subpart N (Environmental Fate) §158.1300 

(Environmental fate data requirements table), these data are required for all terrestrial use 

patterns. 

The available study was performed in the presence of high levels of cosolvent acetonitrile 

(around 8%). The study indicated that fenpropathrin was stable under the testing 

conditions. Supplemental data from other previously reported studies, indicated halflives ranging from 1.6 to around 113 days (further data reported by Laskowski 2002, 

half-lives 14.6 to 87.5 days). There is a high level of uncertainty with respect to the 

levels of photolysis and there are no reliable data related to the possible transformation 

products. A new study is required to clarify these uncertainties. 

Practical Utility of the Data 

How will the data be used? 

Fenpropathrin is a synthetic pyrethroid with high toxicity towards aquatic organisms, 

including those living in the benthos. Knowledge of its persistence in aquatic 

environments is important. The results of this study will be used in the environmental 

fate assessment, and later on, in the ecological risk characterization. 

The latter studies submitted for fenpropathrin indicate relative stability for the compound, 

when compared to relatively small half-lives in other studies available, and in the field. 

Knowledge of the routes of dissipation with detail is essential for an accurate 

environmental fate assessment. 

In addition, the aqueous photolysis data will be used to derive the rate of reaction input 

parameters to be used in the aquatic models GENEEC2, PRZM/EXAMS and FIRST. 

The results from these models are used for ecological risk estimation and in drinking 

water exposure assessments. 

How could the data impact the Agency’s future decision-making? 

Without these data, the Agency would have to make certain conservative assumptions 

(assume that fenpropathrin is stable to these processes, including the environmental fate 

assessment and the aquatic models). These conservative assumptions could lead to 

higher predicted concentrations (EECs), according to the models, and consequently, 

 73
Guideline Number 835.2240 

Study Title: Aqueous Photolysis 

higher risk quotients. Also, there would be a higher degree of uncertainty in the 

environmental fate assessment. Knowledge of these dissipation pathways in detail is 

essential to perform a better and accurate environmental fate assessment and risk 

assessment. 

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 

fenpropathrin that may be unnecessary. 

 74
Guideline Number: 835.4100 

Study Title: Aerobic Soil Metabolism 

Guideline Number: 835.4200 

Study Title: Anaerobic Soil Metabolism

Rationale for Requiring the Data 

According to 40 CFR Part 158, Subpart N (Environmental Fate) §158.1300 

(Environmental fate data requirements table), these data are required for all terrestrial use 

patterns. 

At this time the Agency has one aerobic soil metabolism study, performed in one soil 

(152 days, SiL). Further supplemental data that has not been used in recent risk 

assessments, but that provides some comparative information, indicated the following 

estimates of half-lives: 33-35 days (light clay) and 34-39 days (SCL). The problem with 

this early study was that it was conducted for only 30 days (required 365 days). High 

variability in the results from the supplemental study conducted earlier (with shorter halflives) vs. the most recent study brings uncertainty to the environmental fate assessment. 

Aerobic soil metabolism half-lives, reported by Laskowski 2002, are 34.1, 32.1, 34.8, 

36.5, 39.4, 133, 34.7, 51.3, 221 & 186 days for SCL, C, SCL, C, SL, C, SL, SC, SC & L 

soils. Rates of transformation should be determined in four soils. The registrant should 

submit a study conducted in three soils; a sandy loam soil should be included. 

The available anaerobic study was performed with only one soil and for a period of only 

roughly 2 months of anaerobic incubation (with a reported half-life of 186 days, for a L 

soil). By way of comparison, other half-lives, reported by Laskowski 2002, are 283 & 

383 days for C & SCL, respectively. 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 (from Fate, Transport and Transformation 

Test Guidelines – OPPTS Guideline 835.4100 & 835.4200). The study indicates that 

after the soil was flooded (converted to anaerobic), the metabolism was very low. Data 

performed for a longer period of time will help the Agency to determine rates of 

transformation and presence of possible metabolites. Studies should be conducted in four 

soils. 

Practical Utility of the Data 

How will the data be used? 

Fenpropathrin is a synthetic pyrethroid with high toxicity towards aquatic organisms, 

including those living in the benthos. Knowledge of its persistence in soil and aquatic 

environments is important. The results of this study will be used in the environmental 

fate assessment, and later on, in the ecological risk characterization. 

In addition, the data will be used to derive the rate of reaction input parameter to be used 

in the aquatic models GENEEC2, PRZM/ EXAMS, FIRST and SCI-GROW. The results 

from these models are used for ecological risk estimation and in drinking water exposure 

assessments. 

 75
Guideline Number: 835.4100 

Study Title: Aerobic Soil Metabolism 

Guideline Number: 835.4200 

Study Title: Anaerobic Soil Metabolism

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. use three times the single available aerobic soil metabolism study half-life as the 

input for the aerobic soil metabolism in various of the models). These conservative 

assumptions could lead to higher predicted concentrations (EECs), according to the 

models, and consequently, higher risk quotients. Also, there would be a higher degree of 

uncertainty in the environmental fate assessment. Knowledge of these dissipation 

pathways in detail is essential to perform a better and accurate environmental fate 

assessment and risk assessment. 

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 

fenpropathrin that may be unnecessary. 

 76
Guideline Number: 835.4300 

Study Title: Aerobic Aquatic Metabolism 

Guideline Number: 835.4400 

Study Title: Anaerobic Aquatic Metabolism

Rationale for Requiring the Data 

According to 40 CFR Part 158, Subpart N (Environmental Fate) §158.1300 

(Environmental fate data requirements table), these data are required for all terrestrial use 

patterns. 

No aerobic aquatic metabolism study has been submitted. The study is required and it 

should be conducted in at least two sediments. 

Two studies are available, performed in only one soil type (currently in review). These 

studies are currently in review. According to OPPTS Guideline 835.4300 and 835.4400, 

“For the strictly anaerobic study, two sediments (including their associated waters) 

should be sampled from the anaerobic zones of surface water bodies...” A study 

conducted in one additional sediment type is required. 

Practical Utility of the Data 

How will the data be used? 

Fenpropathrin is a synthetic pyrethroid with high toxicity towards aquatic organisms, 

including those living in the benthos. Knowledge of its persistence in aquatic 

environments is important. The results of this study will be used in the environmental 

fate assessment, and later on, in the ecological risk characterization. 

In addition, the data will be used to derive the rate of reaction input parameters to be used 

in the aquatic models GENEEC2, PRZM/ EXAMS and FIRST. The results from these 

models are used for ecological risk estimation and in drinking water exposure 

assessments. 

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. use two times the aerobic soil metabolism half-life input value for the aerobic 

aquatic metabolism or two times the anaerobic soil metabolism half-life for the anaerobic 

aquatic metabolism in the aquatic models). These conservative assumptions could lead to 

higher predicted concentrations (EECs), according to the models, and consequently, 

higher risk quotients. Also, there would be a higher degree of uncertainty in the 

environmental fate assessment. Knowledge of these dissipation pathways in detail is 

essential to perform a better and accurate environmental fate assessment and risk 

assessment. 

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 

fenpropathrin that may be unnecessary. 

 77
 

Guideline Number: None 

Study Title: Environmental Chemistry Methods (ECM) and Independent 

Laboratory Validation (ILV) for Soil, Water and Sediment

Rationale for Requiring the Data 

According to the data requirements in 40 CFR Part 158, ECMs are currently required 

along with successful confirmatory method trials (validation) by an independent 

laboratory (i.e. ILVs). The registrant submitted one method for soil (MRID 41679601, 

LOD 0.01 ppm, published in the Agency’s ECM website)4

, that could quantify 

fenpropathrin and its metabolites 4’-OH-fenpropathrin and desphenylfenpropathrin in 

soil, using GC with a nitrogen/ phosphorous flame ionization detector. These levels of 

quantization may not be appropriate. Furthermore, the following studies have been 

located and are currently in review: MRIDs 71368 & 100138, 126817, 126818, 43958802 

and 43958803 (the latter two studies are ILVs), and 47053001 and 47053002 (ECM and 

ILV). The Agency will verify the suitability of these methods and the appropriateness of 

their levels of quantization. In addition to the method for soil, at this time, methods are 

required for water and sediment. The results of previous assessments indicate that there 

is risk for freshwater and estuarine/ marine fish, invertebrates and benthic organisms. 

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 

exceed 10% of the applied (PBA, CONH2-fenpropathrin and COOH-fenpropathrin). 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. 

Practical Utility of the Data 

How will the data be used? 

The data will be used to verify the suitability of the methods. Subsequently the methods 

could be used by states or other enforcement agencies, departments or entities, to monitor 

concentrations of the residues of concern. Validated analytical methods in environmental 

media (a.k.a., ECMs) are useful for conducting and evaluating submitted environmental 

fate and toxicity field and monitoring studies and for addressing potential risks to the 

environment posed by the use and/or accidental release of pesticides. 

How could the data impact the Agency’s future decision-making? 

If monitoring of the chemical is required or performed, the Agency could be able to 

determine if the chemical is present in the environment at concentrations that are 

threatening to wildlife (or to humans, in the case of drinking waters), according to the 

levels of concern (LOCs). If that is the case, measures to prevent these concentrations to 

occur could be taken. The data could also be used by enforcement entities like the states 

or government agencies or departments. Without these data, the potential for the 

determination of residues of fenpropathrin and transformation products (PBA, CONH2-

fenpropathrin and COOH-fenpropathrin) in soil, water and sediment is restricted. 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 

fenpropathrin which may otherwise be avoided, or which are unnecessarily severe. 

 

4 Available at url: http://www.epa.gov/oppbead1/methods/ecmindex.htm

 78
Guideline Number: 850-2100 

Study Title: Passerine Acute Avian Oral 

Rationale for Requiring the Data 

Although an acute avian oral study was received for the Mallard duck, the Agency 

updated its data requirements in 40 CFR Part 158 (October 26, 2007) to include an acute 

oral toxicity study for both a passerine species and either a waterfowl or an upland game 

species. Prior to starting toxicity testing, a protocol will need to be provided for review. 

o Many passerine species utilize agricultural fields, forests, residential areas 

and surrounding areas, and, therefore, have the potential to be exposed to 

pesticides used in agricultural, forest, and residential settings 

 It is likely that, for most pesticide use patterns, passerines are more 

likely to be exposed to pesticides than upland game species and 

waterfowl 

o Passerines are smaller and have faster metabolisms than the waterfowl and 

upland game bird species traditionally used in avian toxicity tests which 

could impact their sensitivity to chemicals. 

Practical Utility of the Data 

How will the data be used? 

Data from passerine toxicity studies will be used to estimate potential risks to birds 

associated with uses of fenpropathrin. The data will reduce uncertainties associated with 

the current risk assessment for passerine species and will improve our understanding of 

the potential effects of fenpropathrin. 

How could the data impact the Agency’s future decision-making? 

Because birds significantly contribute to overall environmental quality, a solid 

understanding of the potential risks to birds, including passerine species, is essential for 

sound environmental management. Without acceptable data for fenpropathrin, the 

Agency cannot determine the levels of fenpropathrin that result in effects to passerine 

species. If the data indicates that registered usage may pose a risk of adverse effects to 

non-target birds 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 for fenpropathrin which may otherwise be avoided, or 

which are unnecessarily severe. 

 79
Guideline Number: 850.1400 

Study Title: Aquatic Fish Early Life Stage (saltwater)

Rationale for Requiring the Data 

The acute toxicity of fenpropathrin to estuarine/marine fish and environmental fate 

properties indicates the potential for chronic exposure and effects to animals in this taxon, 

per 40 CFR Part 158 data requirements (October 26, 2007). For example, the acute LC50

for freshwater fish (2.2 μg ai/L) is well below the 1.0 mg/L criterion specified in 40 CFR 

Part 158 for conditionally requiring this study. Furthermore, the persistence of 

fenpropathrin in water is expected to substantially exceed the 4-d half life criterion 

specified in 40 CFR Part 158. 

The Agency had conditionally required aquatic life stage studies for terrestrial food and 

nonfood, aquatic food and nonfood, forestry, and domestic outdoor uses. 

Practical Utility of the Data 

How will the data be used? 

The estuarine/marine fish early life stage study would allow the Agency to analyze 

chronic effects, including effects on reproductive success and growth, to saltwater species. 

The effects data would be used to determine the likelihood that the chronic risks can 

potentially impact aquatic communities, either by direct effects on fish or by indirect 

effects by reducing their food sources. By refining the assessment, the Agency would be 

able to determine whether the mitigation imposed as part of the registration review 

process was appropriate due to toxicity concerns with fenpropathrin. 

How could the data impact the Agency’s future decision-making? 

If future endangered species risk assessments are performed without these data, the 

Agency would have to assume that fenpropathrin "may affect" estuarine/marine 

endangered fish directly (and endangered species from other taxa indirectly), and use of 

fenpropathrin might need to be restricted in areas where endangered species could be 

exposed. 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 fenpropathrin which are unnecessarily severe. 

 80
Guideline Numbers: Non-Guideline 

Study Title: Chronic whole sediment: Freshwater and marine invertebrates 

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 fenpropathrin, available information indicates that 

benthic organisms may be exposed via run-off or spray drift applications used in 

agricultural, forest, and residential settings. Specifically: 

• The peak sediment porewater EECs predicted for fenpropathrin (0.06 – 0.76 ppb) 

all exceed 0.1 of the acute LC/EC50 (0.021 ppb for M. bahia), which satisfies one 

of the criteria for requiring chronic whole sediment toxicity testing under 40 CFR 

Part 158.

• The expected half-life of fenpropathrin in sediment (67-78 days for anaerobic 

aquatic metabolism) is substantially greater than 40 CFR Part 158 criterion of 10 

days. 

• The Kd values range from 64-810, the log Kow is 6, and KOC values range from 

13870-85260, all of which exceed the third set of trigger criteria for requiring 

chronic testing (Kd > 50, or log Kow >3 or Koc > 1000)

• Finally, the potential for persistent exposure from fenpropathrin in sediment is 

also indicated by open literature studies on pyrethroids (Weston et al. 2005, 

Amweg et al. 2006 and Ding et al. 2009). 

For sediment studies involving pyrethroids, chronic 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 vs. infaunal species), physiology, and potential sensitivities to pyrethroid 

exposure (e.g., Anderson et al. 2006; Maund et al., 2002). Fenpropathrin has the potential 

to enter estuarine/marine water bodies based on current usuage patterns that include 

coastal areas. Therefore, testing is required for Leptocheirus plumulosus, an 

estuarine/marine sediment-dwelling invertebrate species.

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 fenpropathrin. The data will reduce uncertainties 

associated with the current risk assessment for benthic species and will improve our 

understanding of the potential effects of fenpropathrin. 

How could the data impact the Agency’s future decision-making? 

Although there was uncertainty in estimating the effect of fenpropathrin on benthic 

organisms in previous assessments, there was a potential risk associated with adverse 

effects identified for estuarine/marine acute and chronic organisms. Acceptable data for 

benthic organisms will reduce the uncertainty from the previous assessment If the data 

indicates that registered fenpropathrin usage may pose a risk of adverse effects to nontarget 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 

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Act, and could result in use restrictions for fenpropathrin which may otherwise be 

avoided, or which are unnecessarily severe. 

. 

Guideline Numbers: 850.4150 and 850.4250 

Study Title: Vegetative vigor and Seedling emergence, Tier I/Tier II 

Rationale for Requiring the Data 

No acceptable toxicity data are currently available to assess the risk of fenpropathrin to 

terrestrial plants. 

Since fenpropathrin has outdoor uses, vegetative vigor and seedling emergence studies are 

required. These phytotoxicity data are needed to evaluate the level of pesticide exposure 

to non-target terrestrial and aquatic plants and to assess the impact of pesticides on 

endangered and threatened plants. 

Practical Utility of the Data 

How will the data be used? 

Data from terrestrial plant toxicity studies will be used to estimate potential risks to plants 

associated with uses of fenpropathrin. The data will reduce uncertainties associated with 

the current risk assessment for terrestrial plants and will improve our understanding of the 

potential effects of fenpropathrin on plants. 

How could the data impact the Agency’s future decision-making?

Because plants form the basis of most habitats and significantly contribute to overall 

environmental quality, a solid understanding of the potential risks to terrestrial plants is 

essential for sound environmental management. Without acceptable plant growth data for 

fenpropathrin, the Agency cannot determine the levels of fenpropathrin that result in 

effects to terrestrial plants. If the data indicates that registered fenpropathrin usage may 

pose a risk of adverse effects to non-target terrestrial plants plants 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 for 

fenpropathrin which may otherwise be avoided, or which are unnecessarily severe. 

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Guideline Number: 850.4400 

Study Title: Aquatic Vascular Plant Growth-Lemna spp. Tiers I/II 

Rationale for Requiring the Data 

No acceptable studies for fenpropathrin have been submitted for vascular aquatic plants. 

The Agency has finalized its update to the data requirements in 40 CFR Part 158. In 

these updated data requirements, which were promulgated on October 26, 2007, 

vascular plant testing is required for pesticides such as fenpropathrin with outdoor uses. 

Practical Utility of the Data 

How will the data be used? 

Data from aquatic plant toxicity studies will be used to estimate potential risks to plants 

associated with uses of fenpropathrin. The data will reduce uncertainties associated 

with the current risk assessment for aquatic plants and will improve our understanding 

of the potential effects of fenpropathrin on vascular aquatic plants. 

How could the data change the Agency’s decision, or impact the Agency’s future 

decision-making? 

Because plants form the basis of most habitats and significantly contribute to overall 

environmental quality, a solid understanding of the potential risks to aquatic plants is 

essential for sound environmental management. Without plant growth data for 

fenpropathrin, the Agency cannot determine the levels of fenpropathrin that result in 

effects to vascular aquatic plants. If the data indicates that registered fenpropathrin 

usage may pose a risk of adverse effects to non-target aquatic vascular plants above the 

Agency Level of Concern, the Agency may explore decision options to mitigate this 

risk. 

If future endangered species risk assessments are performed without these data, the 

Agency would have to assume that fenpropathrin "may affect" endangered plants and 

use of fenpropathrin might need to be restricted in areas where endangered species could 

be exposed. 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 fenpropathrin that may be unnecessarily severe.

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Guideline Number: 850.5400 

Study Title: Algal toxicity test, Tier I/II 

Rationale for Requiring the Data 

No toxicity data are currently available to assess the risk of fenpropathrin to aquatic 

nonvascular plants. Since fenpropathrin has outdoor uses, Tier I/II aquatic nonvascular 

plant studies are required. These phytotoxicity data are needed to evaluate the level of 

pesticide exposure to non-target aquatic plants and to assess the impact of pesticides on 

endangered and threatened plants. 

Practical Utility of the Data 

How will the data be used? 

Data from Tier I/II nonvascular aquatic plant toxicity studies will be used to estimate 

potential risks to plants associated with uses of fenpropathrin. The data will reduce 

uncertainties associated with the current risk assessment for nonvascular aquatic plants 

and will improve our understanding of the potential effects of fenpropathrin. 

How could the data impact the Agency’s future decision-making?

Because plants form the basis of most habitats and significantly contribute to overall 

environmental quality, a solid understanding of the potential risks to nonvascular aquatic 

plants is essential for sound environmental management. Without plant growth data for 

fenpropathrin, the Agency cannot determine the levels of fenpropathrin that result in 

effects to aquatic plants. If the data indicates that registered usage may pose a risk of 

adverse effects to non-target aquatic nonvascular plants 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 for fenpropathrin 

which may otherwise be avoided, or which are unnecessarily severe. 

 84
Guideline Number: 850.1010 

Study Title: Aquatic Invertebrate Acute Toxicity (Hyalella Azteca)

Rationale for Requiring the Data 

Available information in the ECOTOX database indicates that the freshwater amphipod, 

Hyalella azteca, is substantially more sensitive to pyrethroids than Daphnia magna, the 

commonly tested freshwater invertebrate. Information on the acute toxicity of 

fenpropathrin to H. azteca was not identified in this problem formulation. Therefore, in 

order to ensure that risk to sensitive aquatic invertebrates are appropriately quantified, 

additional acute toxicity testing of H. azteca is needed (water column exposure, not 

sediment-spiked).

Practical Utility of the Data 

How will the data be used? 

The freshwater acute toxicity study with Hyalella would allow the Agency to analyze 

acutely toxic effects to one of the most sensitive species of freshwater aquatic 

invertebrates. The effects data would be used to determine the likelihood that acute risks 

can potentially impact aquatic communities, either by direct effects on invertebrates or by 

indirect effects by reducing the food source for their predators (e.g., fish). By refining the 

assessment, the Agency would be able to determine whether the mitigation imposed as 

part of the registration review process was appropriate due to toxicity concerns with 

fenpropathrin. 

How could the data impact the Agency’s future decision-making? 

If future risk assessments are performed without these data, the Agency would have to 

account for the potential increased sensitivity of Hyalella to fenpropathrin using other 

means which may include using an extrapolation factor based on sensitivity differences 

with other pyrethroids. Since this extrapolation factor would involve uncertainty, it is 

likely that a conservative factor would be applied. This may impinge on the Agency’s 

flexibility in coming into compliance with the Endangered Species Act and could result in 

use restrictions for fenpropathrin which are unnecessarily severe. 

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