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metabolism study, conducted in one sediment system should be submitted. Chemical 

stability will be assumed in the absence of data. 

 Anaerobic aquatic metabolism study (835.4400) There are no acceptable anaerobic 

aquatic metabolism studies. A new anaerobic aquatic metabolism study should be 

submitted. Two sediment systems are required. Submission of an acceptable anaerobic 

aquatic metabolism study is necessary to understand the degradation of tefluthrin in 

oxygen-limiting environments. Chemical stability will be assumed in the absence of data 

 The environmental chemistry analytical methods and independent laboratory (ILV)

portions (only) of the terrestrial field dissipation (835.6100) and the aquatic field 

dissipation study (835.6200) rather than the full field dissipation study. 

The available effects dataset is considered incomplete for the purposes of risk assessment. The 

following data gaps exist: 

 Freshwater and estuarine/marine spiked whole-sediment chronic tests, TGAI. 

Test Method 100.4 (OCSPP 850.1770, in prep.); Whole sediment: chronic invertebrates 

freshwater (Hyalella azteca) 

Test Method 100.5 (OCSPP 850.1760, in prep.); Whole sediment: chronic invertebrates 

freshwater (Chironomus dilutus) 

EPA 600/R-01/020 (OCSPP 850.1780, in prep.); Whole sediment: chronic invertebrates 

marine (Leptocheirus plumulosus). There are no data available regarding chronic toxicity 

of tefluthrin to benthic organisms, an exposure compartment of concern. For pyrethroids, 

spiked whole sediment chronic toxicity data for Hyalella azteca, Chironomus dilutus, and 

Leptocheirus plumulosus are necessary for risk assessment. 

 Aquatic Invertebrate TGAI Acute Toxicity with Hyalella azteca (Non-guideline 

special study). Available information indicates that the freshwater amphipod, H. azteca, 

is substantially more sensitive to pyrethroids than Daphnia magna, the commonly tested 

freshwater invertebrate (e.g., Anderson et al. 2006; Maund et al., 2002). Therefore, in 

order to ensure that risks to sensitive aquatic invertebrates are appropriately quantified 

additional acute toxicity testing of H. azteca is needed (water-only exposure tests, no 

sediment present). 

 Mysid Chronic Toxicity study (GLN 850.1350). As discussed in the document, mysids 

are generally far more acutely sensitive to tefluthrin than daphnids and exposure to 

estuarine/marine environments is likely. In the absence of these data, an acute-to-chronic 

ratio based on the daphnid data would be used; however this may result in 

underestimation of potential risk. 

 Avian acute oral study with a passerine (GLN 850.2100). Data on the toxicity of 

tefluthrin to passerines are necessary for risk assessment. A registrant submission 

examining the potential toxicity of tefluthrin to the house sparrow (Passer domesticus; 

MRID 40161123) is being reviewed to determine if it can be used to fulfill this data 

requirement. Provisionally, the study indicates passerines as more sensitive to tefluthrin 

than bobwhite or mallard. 
-3 of 50-

 Honey bee acute contact toxicity study (GLN 850.3020). No data are available to 

assess the potential toxicity of tefluthrin to beneficial invertebrates. As an insecticide, 

effects to terrestrial invertebrates are expected, but a hazard threshold has not been 

established. 

 Aquatic vascular plant study (GLN 850.4400). There are no data available regarding 

the toxicity of tefluthrin to aquatic vascular plants. Aquatic ecosystems are likely to be 

exposed to tefluthrin through erosion of treated soil particles to which it is sorbed. These 

data are necessary for risk assessment. 

 Aquatic non-vascular plant testing: one for each of 4 species (GLN 850.5400). There 

are no data available regarding the toxicity of tefluthrin to aquatic non-vascular plants. 

Aquatic ecosystems are likely to be exposed to tefluthrin through erosion of treated soil 

particles to which it is sorbed. These data are necessary for risk assessment. 

 Terrestrial Plant Toxicity-Seedling Emergence (GLN 850.4100). No data on the 

toxicity of tefluthrin to terrestrial plants is available. Because tefluthrin may runoff the 

treated field to nontarget areas, effects to terrestrial plant seedling emergence may occur. 

Due to the current use patterns, spray drift is not expected therefore a vegetative vigor 

study is not necessary at this time. 

Additional detail on the current data gaps for environmental fate and effects for tefluthrin is 

provided in Section 8.0. 

Additional data needed for the risk assessment include label clarification. According to the 

LUIS report, tefluthrin use is not limited in number of applications. While it appears that 

tefluthrin is only applied at planting, verification and appropriate label statements will clarify this 

issue. Additionally, rates are provided only as lbs ai/linear foot or lbs ai/lb of seed. The 

registrant indicated in a Focus Meeting on August 14, 2012 that the labels would be updated to 

limit applications to once per year and specify the maximum amount of active ingredient on a per 

acre basis. The risk assessment will be based on the stamped labels current at the time of the 

assessment. 
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Problem Formulation for the Environmental Fate and Ecological Risk, 

Endangered Species, and Drinking Water Assessments in Support of the 

Registration Review of Tefluthrin 

CAS Registry Number: 79538-32-2 

PC Code: 128912 

Prepared by:

Brian D. Kiernan, Biologist

Ibrahim Abdel-Saheb, Ph.D., Environmental Scientist

U. S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch VI

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington, DC 20460

Reviewed by:

Elizabeth Riley, Biologist

Reuben Baris, Environmental Scientist

Stephanie Syslo, RAPL

William Eckel, PhD, Acting Branch Chief, ERB 6

August 30, 2012 
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1. Purpose 

The purpose of this problem formulation is to provide an understanding of what is known about 

the environmental fate and ecological effects of the registered uses of tefluthrin (PC Code 

128912). Tefluthrin is a synthetic pyrethroid insecticide. Its structure has two rings, one phenyl 

ring and a cyclopropyl ring. It is not substituted in the alpha position (thus, it is a type 1 synthetic 

I . pyrethroid). 

Currently, tefluthrin is registered for use on corn as a granular formulation as well as a seed 

treatment and on sugar beet as a seed treatment. Tefluthrin is formulated as a granular and 

emulsifiable concentrate. 

The granular formulation may be applied either at-plant or layby (during cultivation). The atplant applications may be made via band treatment or furrow treatment (required for highly 

erodible soils). For the band treatment, the granules must be incorporated into the top 1 inch of 

soil. Layby applications may be made by placing the granules at the base of the plant and then 

covering them with 2-3 inches of soil on each side. 

Tefluthrin's mode of action, like other pyrethroids, is to prevent the sodium channels in an 

organism's neuronal membranes from closing, causing paralysis as the nerves cannot revert to a 

de-excited state. 

This document will provide a plan for analyzing data relevant to tefluthrin and for conducting 

environmental fate and ecological risk, endangered species, and drinking water assessments for 

its registered uses. Additionally, this problem formulation is intended to identify data gaps, 

uncertainties, and potential assumptions used to address those uncertainties relative to 

characterizing the ecological risk associated with the registered uses of tefluthrin. 

2. Problem Formulation 

2.1. Nature of Regulatory Action 

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

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

Agency (EPA). As part of determining whether a pesticide can be registered in the U.S., the 

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

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

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

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

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

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

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

policy, and pesticide use practices occur over time. Through the Registration Review program, 
-6 of 50-

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

the marketplace can be used safely. 

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

FIFRA, the Agency is beginning its evaluation of tefluthrin to determine whether it continues to 

meet the FIFRA standard for registration. This problem formulation for the environmental fate, 

ecological risk, endangered species, and drinking water assessment chapter in support of the 

Registration Review will be posted in the initial docket, which will open the public phase of the 

review process. 

2.2. Previous Assessments 

 Tefluthrin was registered by the US Environmental Protection Agency (EPA) as an 

insecticide for use in corn in 1989. 

 Drinking Water Assessment for the Proposed New Use of Tefluthrin (Force@ SB) as a 

Seed Treatment for Sugar Beets (DP Barcode D369420; August 11, 2010). The 

document reports EDWCs for corn to be 259 ppt (surface water acute), 8.74 ppt (noncancer chronic) and 6.06 ppt (cancer chronic), respectively, and the SCI-GROW 

groundwater concentration as 1.0 ppt, suitable for both acute and chronic exposures. The 

new use on sugar beets resulted in negligible EDWCs. 

 Environmental Fate and Ecological Risk Assessment for the Proposed New Use of 

Tefluthrin on Sugar Beet as a Seed Treatment (DP Barcode: 374771; June 16, 2010). In 

this assessment, acute and chronic risks for avian and mammalian species were 

determined to be above the Agency’s level of concern (LOC) for listed and non-listed 

species. Risks could not be estimated for terrestrial and aquatic plants as no studies were 

submitted that characterized toxicity to these taxa. However, as tefluthrin was being 

proposed as a seed treatment with an incorporation of soil of at least 1 inch, leaching 

from the seed was not expected. With a very high KOC value of ≥100,000 mL/gOC and a 

classification as hardly mobile to immobile, low risk to these taxa is expected due to the 

chemical likely remaining adsorbed to the seed. For aquatic organisms in both the water 

column and sediment pore water, risk was determined to be several orders of magnitude 

below the LOC. Despite high toxicity to fish and aquatic invertebrates, the chemical has 

a high KOC value and is not expected to leach off of the seed and enter the aquatic 

environment. No LOCs were exceeded for all freshwater and marine/estuarine fish and 

invertebrates. 

2009 Scientific Advisory Panel 

OPP presented a “Proposed Common Mechanism Grouping for the Pyrethrins and Synthetic 

Pyrethroids to a FIFRA SAP in June 2009. OPP proposed two subgroups based on Type I or 

Type II effects related to sodium current tails and neurobehavioral impact, with esfenvalerate and 

fenpropathrin showing symptoms of both types. The panel indicated that substances with mixed 

characteristics could be included in both groups (see p. 18 of SAP minutes, USEPA 2009). The 

natural pyrethrins are Type I pyrethroid insecticides, with no cyano-substitution in the alpha-
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position. This mechanism of action assessment was performed by HED/OPP and presented to 

the SAP to determine if a cumulative assessment is required for the synthetic pyrethroids. 

Information on the SAP is available in the docket (with non-copyright material available at 

http://www.regulations.gov) under EPA-HQ-OPP-2008-0489. 

EFED does not currently conduct cumulative ecological risk assessments for several reasons. 

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

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

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

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

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

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

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

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

monitoring data) as available, to address the potential for cumulative effects of pyrethroids in the 

risk description of the ecological risk assessment for tefluthrin. 

3. Stressor Source and Distribution 

3.1. Mechanism of Action 

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

poisons that affect both the peripheral and central nervous system. It is now well established that 

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

result of modification of Na+

 channel activity (cellular pores through which sodium ions are 

permitted to enter the axon to cause excitation). Advanced electrophysiological experiments 

using a voltage clamp and a patch clamp, together with ligand-binding and ionic flux 

experiments, have unveiled unique actions of pyrethroids of keeping the Na+ channel in the open 

state for an extremely long period, sometimes as long as several seconds. This modification of 

Na+

 channel properties leads to hyperactivity of the nervous system. Pyrethroids have also been 

shown to suppress GABA 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., 

pyrethrins, bioallethrin, d-phenothrin, resmethrin, tefluthrin) and Type II (e.g., cypermethrin, 

deltamethrin). In Type I pyrethroids, such as tefluthrin, the 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. 

3.2. Overview of Pesticide Use and Usage 

Tefluthrin is a synthetic pyrethroid insecticide formulated as a granular and emulsifiable 

concentrate. Tefluthrin is registered for use on corn and sugar beet. 
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One of the liquid formulation products is only for use by commercial seed treaters. It may be 

applied to corn seeds using either liquid seed treating equipment or seed coating equipment. In 

the field, tefluthrin may be applied as a spray at the time of planting. Spray applications may be 

made as either a T-band or furrow treatment, both requiring soil incorporation to 1 inch. 

The granular formulation may be applied either at-plant or layby (during cultivation). The atplant applications may be made via band treatment or furrow treatment (required for highly 

erodible soils). For the band treatment, the granules must be incorporated into the top 1 inch of 

soil. Layby applications may be made by placing the granules at the base of the plant and then 

covering them with 2-3 inches of soil on each side. 

The application rate varies with the formulation used, stage of weed growth, and application 

timing (Table 1). 

Additional data needed for the risk assessment include label clarification. According to the 

LUIS report, tefluthrin use is not limited in number of applications. While it appears that 

tefluthrin is only applied at planting, verification and appropriate label statements will clarify this 

issue. Additionally, rates are provided only as lbs ai/linear foot or lbs ai/lb of seed. The 

registrant indicated in a Focus Meeting on August 14, 2012 that the labels would be updated to 

limit applications to once per year and specify the maximum amount of active ingredient on a per 

acre basis. The risk assessment will be based on the stamped labels current at the time of the 

assessment. 
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Table 1. Registered products containing tefluthrin. 

MCAP: Microencapsulate 

NS: Not specified 

Reg# AI

% 

For

mul

atio

n 

Product Name Max App 

Rate 

Max 

# 

Apps 

Season

al Max 

Rate 

Min. 

Retreat

ment 

Interval 

Appl. 

Method 

Type 

Appl. 

Method 

Appl. 

Timing 

100-1075 3 G 

FORCE 3G 

INSECTICIDE 

.00000938 

lb / linear ft NS NS NS 

Soil band 

treatment 

Soil infurrow 

treatment 

Soil 

treatment 

(Tbanding). 

Soil 

incorporation 

equipment. 

At 

emergence 

through 

seedling 

stage. 

At planting 

Layby 

100-1087 26.8 EC FORCE ST 

INSECTICIDE 

.00526871 

lb / lb 

to 

.00078055 

lb / lb 

NS NS NS Seed 

treatment 

Coating 

machine 

Liquid seed 

treater 

Slurry-type 

seed treater 

At planting 

Preplanting 

100-1253 23.4 MC

AP 

FORCE CS 

INSECTICIDE 

.00000911 

lb / linear ft 

 to 

.00000927 

lb / linear ft 

NS NS NS Soil infurrow 

treatment

. 

Soil 

treatment 

(Tbanding). 

Microtube. 

Sprayer 

Soil 

incorporation 

equipment 

At planting 

100-

XXXX 

(Registrati

on status 

uncertain) 

19.1 EC FORCE SB 0.0161 lbs 

ai/A 

NS NS NS Seed 

treatment 

Coating 

machine 

Liquid seed 

treater 

Slurry-type 

seed treater 

Pre-plant 
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Figure 1 spatially represents tefluthrin use intensity in the United States. Figure 2 presents the 

States with highest tefluthrin use as a percent of total use. 

Figure 1. Tefluthin Usage by Crop Reporting District from 2006-2010 (USDA, 2010). 

According to the Biological and Economic Analysis Division’s (BEAD), the states with the most 

agricultural usage in terms of pounds a.i. applied for the years 2006-2010 are Illinois (47%), 

Indiana (15%), Nebraska (12%), Iowa (8%), Minnesota (5%) and Wisconsin (5%) (Figure 2). 

These states ranked similarly in terms of the total area treated (BEAD Chemical Profile for 

Registration Review: Tefluthrin, March 21, 2012). 
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Figure 2. States with Highest Use (Percent of Total Pounds AI Applied) 2006-2010 

3.3. Environmental Fate and Transport 

Tefluthrin is a soil incorporated or seed treatment chemical for use on corn (at plant). When 

applied to the field, tefluthrin is likely to mostly partition to the soil. 

Tefluthrin appears to bind strongly to soil and organic matter (Kow= 3.16 x 106 , and Koc and 

KFOC on the order of, or greater than 100,000 mL/goc (hardly mobile to immobile, FAO 2000). 

Thus, it is not expected to substantially leach into subsurfaces. It may reach aquatic 

environments via runoff events accompanied by erosion occurring after large rainfall events. 

Upon hydrolysis, tefluthrin is stable at pHs 5 and 7, and relatively persistent at pH 9 (2:70% was 

parent compound after 0 days). 

Under aqueous and soil photolysis, the major photoproduct is the trans-isomer of tefluthrin 

(~37% isomerization after 31 days upon aqueous photolysis). Aqueous photolysis is expected in 

shallow clear waters. If this happened, the trans-isomer of tefluthrin will have same toxicity of 

the parent. On the other hand, soil photodegradation is not expected to be an important route of 

dissipation for tefluthrin due to its method of application. Tefluthrin appears to be moderately 

persistent in terrestrial environments (aerobic soil metabolism 17.4 -75.3 days; terrestrial field 

dissipation 12 -124 days). It has the potential to persist in aquatic environments, where it may 

partition to the sediment and has the potential to affect benthic and epibenthic. 

 

Tefluthrin has molecular weight of 418.7 g/mol. With a relatively low solubility (0.02 ppm, it is 

considered as 'not soluble' according to the FAO solubility classification, FAO 2000) and a high 

octanol/water partition coefficient (Kow= 3.16 x 106

 ). Based on it octanol/water partition 

coefficient, it appears that tefluthrin has the potential to bioaccumulate, which will be explored 

more thoroughly in the risk assessment. With a vapor pressure of 1.9 x 10-5 mmHg, and low 
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solubility (0.02 ppm), its calculated Henry's Law Constant is moderate (5.2 x 10-4 atm-m3/mol). 

In addition, its Cwater//Cair is 45, which classifies it as "rapidly lost from a water surface" 

(USEPA 2008). 

Tefluthrin may be bioaccumulative. In a bioaccumulation in fish study, BCFs reached as high as 

12,800~(f or viscera) and the estimated depuration half-life was ca. 14 days. In the edible tissue, 

61-66% of the total [14c] residues were tefluthrin and 17-24% of the residues were 

unextractable. 

Even though various degradates were observed in the laboratory studies, it was found that 

several of them were the result of the rupture of the ester bond of the parent molecule. It has 

generally been believed that the resulting molecules are not as toxic as the parent because they 

presumably have lost the neurotoxic mode of action. 

Table 2 Summary of physicochemical properties of tefluthrin.

PARAMETER VALUE(S) (units) SOURCE

CAS Chemical 

Name 

(2,3,5,6-tetrafluoro-4-methylphenyl)methyl (1R,3R)-rel-3-[(1Z)-2-

chloro-3,3,3-trifluoro-1-propenyl]-2,2-

dimethylcyclopropanecarboxylate Tefluthrin data sheet: 

http://www.alanwood.net/

pesticides/tefluthrin.html

IUPAC Chemical Accessed 4/14/10. 

Name 

2,3,5,6-tetrafluoro-4-methylbenzyl (1RS,3RS)-3-[(Z)-2-chloro-3,3,3-

trifluoroprop-1-enyl]-2,2-dimethylcyclopropanecarboxylate 

or 

2,3,5,6-tetrafluoro-4-methylbenzyl (1RS)-cis-3-[(Z)-2-chloro-3,3,3-

trifluoroprop-1-enyl]-2,2-dimethylcyclopropanecarboxylate 

PC Code 128912 OPP Databases 

Chemical 

Structure 

Tefluthrin data sheet: 

http://www.alanwood.net/

pesticides/tefluthrin.html

Accessed 4/14/10. 

CAS Reg. No. 79538-32-2 Tefluthrin data sheet: 

http://www.alanwood.net/

pesticides/tefluthrin.html

Accessed 4/14/10. 

Chemical 

Formula C17H14ClF7O2
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PARAMETER VALUE(S) (units) SOURCE

Molecular Weight 418.7 g/mol TOXNET database: 

http://toxnet.nlm.nih.gov/

Accessed 4/14/10. 

Appearance Colorless solid. 

Melting Point 44.6oC 

Solubility (20oC) 0.02 ppm 

according to FAO solubility classification. 

MRID 47813004 

FAO, 2000 

Vapor Pressure 

(20oC) 

1.9 x 10-5 mmHg 

The vapor pressure is between the two classifications: ‘Nonvolatile’ and ‘Intermediate to high volatility’ under field condition. 

MRID 47813004 

USEPA, 2008 

Henry’s Law 

Constant (20oC) 5.2 x 10-4 atm-m3

/mol Reviewer calculated from 

VP and water solubility 

Octanol-Water 

Partition 

Coefficient (20oC) 

KOW = 3.16 x 106

 and log KOW = 6.50 

TOXNET database: 

http://toxnet.nlm.nih.gov/

Accessed 4/14/10. 

Octanol-Air 

Partition 

Coefficient 

KOA (log KOA) 

Henry's Law Constant

K RT

K

K

K OW

AW

OW

OA   = 1.5 x 108

 (8.2), 

4.68 x 107

 (7.67) 

Calculated Value vs. 

EPISuite v.4.0 Estimate 

KAW (log KAW) 

KAW = Cair/Cwater = HLC/(RT) = 0.022 (-1.7), 

0.0675 (-1.17) 

‘Rapidly lost from a water surface.’ 

Calculated Value vs. 

EPISuite v.4.0 Estimate 

Cwater/Cair 





 





 

    6

air

water

P GMW 10

S T R 760

C

C = 1/KAW = 45 (unitless) 

‘Rapidly lost from a water surface.’ 

Calculated 

USEPA, 2008 

OH Radical 

Reaction Half-life 0.628 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 tefluthrin, log KOA> 5 (actual 8.2), log KOW > 2 (actual 6.50) 

and rate of transformation is moderate in the environment and 

appears to be relatively slow in fish, with relatively slow 

depuration; it appears that tefluthrin has a potential to biomagnify in 

terrestrial food chains. 

Maximum BCFs: 750x for edible, 12,761x for viscera, 2,051x for 

whole fish. In edible tissue, 61-66% of the residues were parent 

compound, and 17-24% was unextracted residues. The halfdepuration time for the whole fish was ca. 14 days. 

**Gobas et al. 2003 and 

Armitage & Gobas, 2007 

support this presumption 

utilized here only as a 

broad reference to 

determine the potential 

for biomagnification. 

Table 3 shows the chemical structures of tefluthrin’s major and minor degradation products. At 

this time, at least two of them may be considered stressors (see the first two transformation 

products, which preserve the ester moiety of the parent compound). Of them, only transtefluthrin was a major transformation product, and it was observed in the aqueous and soil 
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photolysis studies. Due to the method of application (incorporated to at least 1 inch), soil 

photolysis is not expected to be significant for tefluthrin. 

1Table 3. Major Transformation Products of Tefluthrin 

Chemical Name Structure 

trans-tefluthrin 

2,3,5,6-tetrafluoro-4-methylbenzyl-trans-3-(Z-2-

chloro-3,3,3-trifluoroprop-l-enyl)-2,2-

dimethylcyclopropanecarboxylate 

NA; includes the (Z)-(1R)-trans-acid and the (Z)-(1S)-transacid isomers 

4-carboxy-2,3,5,6-tetrafluorobenzyl (1R,3R;1S,3S)-

3-(Z-2-chloro-3,3,3-trifluoroprop1-eny1)-2,2-dimethylcyclo-propanecarboxylate 

F3C Cl

H3C CH3

O

O

O

OH

F

F

F

F

cis-3-(Z-2-chloro-3,3,3-trifluoroprop-l-eny1)-2,2-

dimethylcyclopropanecarboxylic acid 

F3C Cl

H3C CH3

O

O

OH

2,3,5,6-tetrafluoro-4-methylbenzyl alcohol 

HO

CH3

F

F

F

F

2,3,5,6-tetrafluoro-4-methylbenzoic acid 

HO

CH3

F

F

F

F

O

2,3,5,6-tetrafluoro-1,4-benzenedicarboxylic acid 

HO

O

OH

F

F

F

F

O
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Table 4 shows summary of the environmental fate and transport properties for tefluthrin. 
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3.4. Bioaccumulation 

In a bioaccumulation in fish study, BCFs reached a high as 12,800x (for viscera) and the 

estimated depuration half-life was ca. 14 days. In the edible tissue, 61-66% of the total [14C] 

residues were tefluthrin and 17-24% were unextractable (MRID# 40141333). The potential 

impact of bioaccumulation in ecosystems will be explored in the risk assessment. However, the 

EPA’s PBT Profiler (http://www.pbtprofiler.net/) does not support the supposition that tefluthrin 

is likely to bioaccumulate. The model indicates that tefluthrin meets the criteria for persistence 

and toxicity, but not bioaccumulation. 
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4. Receptors 

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

assessment for tefluthrin relies on a surrogate species approach. Toxicological data generated 

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

are used to extrapolate the potential effects on a variety of species (receptors) included under 

these taxonomic groupings. 

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

available open literature, will be used to evaluate the potential direct and indirect effects of 

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

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

literature studies were identified through EPA’s publically available ECOTOXicology 

(ECOTOX) database (November 2010), which employs a literature search engine for locating 

chemical toxicity data for aquatic and terrestrial plants and wildlife. The evaluation of both 

sources of data may also provide insight into the direct and indirect effects of tefluthrin usage 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. 

A brief summary of the aquatic and terrestrial toxicity data available for the species most 

sensitive to tefluthrin is provided in Sections 4.1 and 4.2, respectively. In addition, a summary of 

ecological incidents associated with tefluthrin and a description of ecosystems potentially at risk 

are provided in Sections 4.3 and 4.4, respectively. There are also no data on the potential 

toxicity of any degradates. In the absence of data, a total toxic residue (TTR) approach (for 

relevant degradates) will be employed in the risk assessment. While degradate data are not 

required for risk assessment, the submission of degradate studies could potentially be used to 

refine the upcoming Registration Review risk assessment. 

Toxicity to fish and aquatic invertebrates is categorized using the system shown in Table 5 (US 

EPA, 2004). Toxicity to terrestrial fauna (birds and mammals) is categorized using the system 

shown in Table 6. Toxicity categories for plants have not been defined. 

Table 5. Categories of Acute Toxicity for Aquatic Animals 

LC50 (ppm) Toxicity Category 

< 0.1 Very highly toxic 

> 0.1 – 1 Highly toxic 

> 1 – 10 Moderately toxic 

> 10 – 100 Slightly toxic 

> 100 Practically nontoxic 

Table 6. Categories of Acute Toxicity for Terrestrial Animals 

LD50 (mg/kg) LC50 (ppm) Toxicity Category 

<10 <50 Very highly toxic 

10-50 50-500 Highly toxic 

51-500 501 - 1000 Moderately toxic 

501-2000 1001 - 5000 Slightly toxic 

>2000 >5000 Practically nontoxic 
-19 of 50-

4.1. Effects to Aquatic Organisms 

The most sensitive of the available aquatic toxicity data from registrant-submitted studies are 

provided in Table 7. If there are any relevant studies available in ECOTOX, they will be 

reviewed for the risk assessment. Based on the available information, tefluthrin is classified as 

very highly toxic to fish and invertebrates on an acute exposure basis. The NOAECs in the 

available chronic exposure studies are as low as 4 ng ai/L. More data on aquatic taxa are 

necessary for risk assessment as outlined below. There are no guideline vascular and 

nonvascular aquatic plants available for tefluthrin; however given the use patterns and the 

physical/chemical properties of tefluthrin, exposure to terrestrial plants is expected to be 

minimal. 

There are no data on the toxicity of tefluthrin degradates to aquatic organisms. In the absence of 

data, a TTR (total toxic residue) approach (for relevant degradates) may be employed in the risk 

assessment. The uncertainty in exposure estimates induced by taking a TTR approach could be 

reduced if specific toxicity data for degradates retaining the ester are submitted. 

In summary, aquatic data needed or under review: 

 Aquatic vascular plant study (GLN 850.4400). There are no data available regarding 

the toxicity of tefluthrin to aquatic vascular plants. Aquatic ecosystems are likely to be 

exposed to tefluthrin through erosion of treated soil particles to which it is sorbed. These 

data are necessary for risk assessment. 

 Aquatic non-vascular plant testing: one for each of 4 species (GLN 850.5400). There 

are no data available regarding the toxicity of tefluthrin to aquatic non-vascular plants. 

Aquatic ecosystems are likely to be exposed to tefluthrin through erosion of treated soil 

particles to which it is sorbed. These data are necessary for risk assessment. 

 Freshwater and estuarine/marine spiked whole-sediment chronic tests, TGAI. 

Test Method 100.4 (OCSPP 850.1770, in prep.); Whole sediment: chronic invertebrates 

freshwater (Hyalella azteca) 

Test Method 100.5 (OCSPP 850.1760, in prep.); Whole sediment: chronic invertebrates 

freshwater (Chironomus dilutus) 

EPA 600/R-01/020 (OCSPP 850.1780, in prep.); Whole sediment: chronic invertebrates 

marine (Leptocheirus plumulosus). There are no data available regarding chronic toxicity 

of tefluthrin to benthic organisms, an exposure compartment of concern. For pyrethroids, 

spiked whole sediment chronic toxicity data for Hyalella azteca, Chironomus dilutus, and 

Leptocheirus plumulosus are necessary for risk assessment. 

 Aquatic Invertebrate TGAI Acute Toxicity with Hyalella azteca (Non-guideline 

special study). Available information indicates that the freshwater amphipod, H. azteca, 

is substantially more sensitive to pyrethroids than Daphnia magna, the commonly tested 

freshwater invertebrate (e.g., Anderson et al. 2006; Maund et al., 2002). Therefore, in 

order to ensure that risks to sensitive aquatic invertebrates are appropriately quantified 

additional acute toxicity testing of H. azteca is needed (water-only exposure tests, no 

sediment present). 
-20 of 50-

 Mysid Chronic Toxicity study (GLN 850.1350). As discussed in the document, mysids 

are generally far more acutely sensitive to tefluthrin and exposure to estuarine/marine 

environments is likely. In the absence of these data, an acute-to-chronic ratio based on 

the daphnid data would be used. 

Table 7. Aquatic Toxicity Profile for Tefluthrin 

MRID# Toxicity Test Endpoint (ppb) Toxicity Study 

Classification 

00156769 

00156770 

Rainbow trout – 

Acute toxicity test 96-h LC50: 0.06 Very highly toxic Acceptable 

Bluegill sunfish – 

Acute toxicity test 96-h LC50: 0.13 Very highly toxic Acceptable 

40161137

Sheepshead 

minnow – Acute 

toxicity test 

96-h LC50: 0.13 Very highly toxic Acceptable 

41705101 

Fathead minnow – 

Chronic early life 

stage test

NOAEC: 0.004 

LOAEC: 0.008 - Acceptable 

40161132 Daphnia magna – 

Acute toxicity test 48-h EC50: 0.07 Very highly toxic Acceptable 

41229501 

Daphnia magna – 

Chronic life cycle 

test 

NOAEC: 0.008 

LOAEC: 0.024 - Acceptable 

40161136 Mysid shrimp 

(Mysidopsis bahia) 

96-h LC50: 

0.053 Very highly toxic Acceptable 

4.2. Effects to Terrestrial Organisms 

Table 8 summarizes the most sensitive terrestrial toxicity endpoints for tefluthrin, based on an 

evaluation of the submitted data. If open literature studies are identified through ECOTOX, they 

will be reviewed for the risk assessment. Tefluthrin is classified as practically nontoxic to 

slightly toxic to birds based on the available acute oral and subacute dietary exposure studies; 

however, an acute oral study with the house sparrow (under review) provisionally indicates 

tefluthrin is more toxic to passerines. The NOAECs for birds are the highest dose tested, as no 

effects were observed. Tefluthrin is classified as highly nontoxic to mammals on an acute oral 

exposure basis. Effects on pup weights were observed in the chronic exposure study with a 

NOAEC of 2.5 mg ai/kg/day. There are no data regarding the potential effects of tefluthrin to 

honey bees. Honey bees may be used as surrogates for other nontarget insects, including native 

pollinators. 
-21 of 50-

There are no phytotoxicity data for terrestrial plant species; a minimum of Tier 1 studies are 

required under 40 CFR Part 158. Two incident reports filed with the EPA involved adverse 

effects to terrestrial plants, but these were reported to be from unincorporated broadcast 

applications, which are not allowed by label. It is possible that tefluthrin may exhibit 

phytotoxicity to certain sensitive plant species, and a seedling emergence study should be 

submitted. Given the labeled application methods (seed treatment/soil treatment), exposure to 

emerged terrestrial plants off the target area is expected to be negligible, thus a vegetative vigor 

study is not necessary. 

In summary, terrestrial data needed or under review: 

 Avian acute oral study with a passerine (GLN 850.2100). Data on the toxicity of 

tefluthrin to passerines are necessary for risk assessment. A registrant submission 

examining the potential toxicity of tefluthrin to the house sparrow (Passer domesticus; 

MRID 40161123) is under review. Until the review is complete, it is unknown whether 

the study can be used to fulfill this data requirement; however, taken at face-value, it 

indicates passerine species are more sensitive to tefluthrin than either bobwhite quail or 

mallard duck. 

 Honey bee acute contact toxicity study (GLN 850.3020). No data are available to 

assess the potential toxicity of tefluthrin to beneficial invertebrates. As an insecticide, 

effects to terrestrial invertebrates are expected, but a hazard threshold has not been 

established. 

 Terrestrial Plant Toxicity-Seedling Emergence (GLN 850.4100). No data on the 

toxicity of tefluthrin to terrestrial plants is available. Because tefluthrin may runoff the 

treated field to nontarget areas, effects to terrestrial plant seedling emergence may occur. 

Due to the current use patterns, spray drift is not expected therefore a vegetative vigor 

study is not necessary at this time. 

The guideline numbers for terrestrial plants in the 40 CFR Part 158 were updated to reflect final 

850 guidelines and do not reflect the numbers of the Public Draft 850 guidelines. Part 158 lists 

850.4100 and 850.4150 (seedling emergence and vegetative vigor, respectively) for both Tier 1 

and Tier 2 studies. The Public Draft guidelines 850.4100 and 850.4150 are for Tier 1 and 

850.4225 and 850.4250 are for Tier 2. 

Table 8. Terrestrial Toxicity Profile for Tefluthrin. 

MRID# Toxicity Test Endpoint (mg 

ai/kg) Toxicity Study Classification 

00156766 

40161123 

00156767 

00156768 

Mallard duck - 

Avian Oral 

Toxicity 

LD50: 4190 Practically non-toxic Acceptable 

House Sparrow - 

Avian Oral 

Toxicity 

LD50: 267 Moderately toxic Under review 

Mallard duck - 

Avian Dietary 

Toxicity 

LC50: 2317 Slightly toxic Acceptable 

Bobwhite quail - LC50: 15000 Practically non-toxic Acceptable 
-22 of 50-

MRID# Toxicity Test Endpoint (mg 

ai/kg) Toxicity Study Classification 

Avian Dietary 

Toxicity 

40161124 

40161125 

Mallard duck – 

Avian reproduction NOAEL: 25 - Acceptable 

Bobwhite quail – 

Avian reproduction NOAEL: 25 - Acceptable 

00261401 

Laboratory rat – 

Acute Oral 

Toxicity 

LD50: 45.6 Highly toxic Acceptable 

40141311 

Laboratory rat – 

Multigenerational 

reproduction study 

NOAEL: 2.5 - Acceptable 

4.3. Incident Database Review 

A review of the Ecological Incident Information System (EIIS), maintained by the Agency’s 

Office of Pesticide Programs (OPP) indicates several reported ecological incidents reported with 

the use of tefluthrin. Aggregated incidents and the American Bird Conservancy’s AIMS 

database will also be reviewed for the risk assessment. 

As shown in Table 9 all reported ecological incidents with the exception of one, affected aquatic 

animals, as most were fish kills. The two incidents listed at the top of the table, incidents 

I001081-001 and I001081-02, were classified as highly probable, although there are currently no 

broadcast spray registrations. Incident ID I001081-001 in particular listed sediment tefluthrin 

environmental residues between 4 and 21 ppb in the report. In the majority of the incidents that 

were listed as “Probable,” or “Highly probable,” misuse was the most common listed reason with 

the pesticide being applied as a broadcast instead of the label recommended in-furrow 

application with the granules not being fully incorporated in the soil. In the majority of incidents 

listed, heavy rain was cited as the primary trigger of the occurrence and when coupled with the 

fact that the tefluthrin granules were not fully incorporated (as required by label), it resulted in 

fish kill incidents. 

2Table 9. Ecological Incident Results as Listed by EIIS 

Incident 

ID Year Legality Certainty State Taxa Affected Application method Product 

I001081-

002 1994 Undetermined Highly probable IL Aquatic animals, terrestrial plants 

Broadcast, 

unincorporated 

Force 

1.5G 

I001081-

001 1994 Misuse Highly probable IL 

Aquatic animals, 

terrestrial animals, 

terrestrial plants 

Broadcast, 

unincorporated 

Force 

1.5G 

I014597-

026 2003 Registered use Possible IA Terrestrial plants Granular Force 3G 

I005805-

002 1997 Undetermined Possible IL Aquatic animals Unknown Force 

3G 

I005805- 1997 Undetermined Possible IN Aquatic animals Unknown Force 
-23 of 50-

Incident 

ID Year Legality Certainty State Taxa Affected Application method Product 

003 3G 

I009314-

006 1997 Undetermined Possible IL Aquatic animals N/R Force 3G 

I009314-

007 1997 Undetermined Possible IN Aquatic animals N/R Force 

3G 

I007440-

001 1998 Registered use Probable IN Aquatic animals N/R Force 

3G 

I000038-

001 1992 Misuse (accidental) Probable NE Aquatic animals Broadcast, unincorporated 

Force 

1.5G 

I005395-

001 1997 Misuse (accidental) Probable IL Aquatic animals N/R Force 

I000538-

001 1993 Registered use Probable IN Aquatic animals T-band Force 1.5G 

B0000-

501-39 1991 Misuse 

(accidental) Probable OH Aquatic animals Broadcast, 

unincorporated Force 

B0000-

300-79 N/R Misuse (accidental) Probable OH Aquatic animals Broadcast, unincorporated 

Force 

1.5G 

I007206-

001 1998 Registered use Probable KY Aquatic animals T-band Force 3G 

N/R = Not recorded 

4.4. Ecosystems Potentially at Risk 

The ecosystems at risk are often extensive in scope; therefore, it may not be possible to identify 

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

However, in general terms, terrestrial ecosystems potentially at risk could include the treated 

field and immediately adjacent areas that may receive 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. 

Aquatic ecosystems potentially at risk include water bodies adjacent to, or downstream from, the 

treated field and could 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.”1

 Selection of the assessment endpoints is based on valued entities (e.g., fish, 

birds), the ecosystems potentially at risk (e.g., waterbodies, riparian vegetation, and upland 

habitats), the migration pathways of tefluthrin (e.g., runoff), and the routes by which ecological 

receptors are exposed to tefluthrin (e.g., direct contact, etc.). 

Assessment endpoints for tefluthrin include direct toxic effects on the survival, reproduction, and 

growth of the receptors, as well as indirect effects, such as reduction of the prey base or 

modification of habitat. Each assessment endpoint requires one or more “measures of ecological 

 

1

 From U.S. EPA (1992). Framework for Ecological Risk Assessment. EPA/630/R-92/001. 
-24 of 50-

effect,” defined as changes in the attributes of an assessment endpoint or changes in a surrogate 

entity or attribute in response to exposure to a pesticide. Specific measures of ecological effect 

are generally evaluated based on acute and chronic toxicity information from registrantsubmitted guideline tests that are performed on a limited number of organisms. Additional 

ecological effects data from the open literature will also be considered. 

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. 

The conceptual model for tefluthrin provides a written description (risk hypothesis) and visual 

representation (conceptual diagram) of the predicted relationships between tefluthrin, potential 

routes of exposure, and the predicted effects for the assessment endpoint. A conceptual model 

consists of two major components: risk hypothesis and a conceptual diagram (USEPA 1998b). 

Since tefluthrin is an in-furrow, soil incorporated granule or seed treatment insecticide, ingestion 

of treated seed or granules placed in soil at the time of planting is the primary pathway through 

which exposure may occur for terrestrial wildlife (birds, mammals, reptiles, terrestrial-phase 

amphibians and invertebrates). 

Based on its current registered uses, and the use patterns (e.g., granular and banded sprays) and 

how these exposures will only likely occur with eroded sediment rather than spray drift. 

Other exposure routes such as dermal contact with treated seed and soil, inhalation of pesticide 

vapors, and ingestion of contaminated soil and drinking water may be considered in the 

assessment. Potential pathways of exposure to aquatic animals include uptake through gills 

and/or dermal uptake through integument from offsite movement of tefluthrin to nearby water 

bodies. In view of high tendency for tefluthrin to persist and accumulate in soil, potential does 

exist for prolonged exposures to both aquatic and terrestrial organisms. This assessment does 

not consider environmental exposure resulting from root uptake of tefluthrin by plants, as 

pyrethroids are not systemic pesticides. The environmental fate and physicochemical 

characteristics of tefluthrin indicate that it is likely to bind to organic matter (its Kocs are high), 

and little translocation is expected. Therefore, the most conservative exposure estimate will 

result from ingestion of the treated seed rather than movement to foliage and within the plant. 
-25 of 50-

6.1. Risk Hypothesis 

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

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

following ecological risk hypothesis will be employed for the national-level ecological risk 

assessment: 

The registered uses of tefluthrin on corn and seed treatment will likely involve situations 

where terrestrial and aquatic animals will be exposed to the chemical and or its 

transformation products. Based on information on environmental fate, mode of action, 

direct toxicity, and potential indirect effects, EFED assumes that tefluthrin has the 

potential to cause reduced survival, growth, and reproduction to terrestrial and aquatic 

organisms as a result of the registered uses of the pesticide. 

6.2. Conceptual Diagram 

The conceptual model used to depict the potential ecological risk associated with the use of 

tefluthrin (the stressor) assumes that as a pesticide, tefluthrin can adversely affect terrestrial and 

aquatic organisms (the receptors) if environmental concentrations exceed toxic thresholds as a 

result of application according to the label directions (Figure 3). Ecological receptors that may 

potentially be exposed to tefluthrin include terrestrial and semi-aquatic wildlife (e.g., mammals, 

birds, terrestrial-phase amphibians and reptiles), terrestrial and semi-aquatic plants, and 

terrestrial invertebrates (e.g., honey bees). Additionally, given the mobility of tefluthrin, aquatic 

organisms (i.e., freshwater and estuarine/marine fish and invertebrates, aquatic-phase 

amphibians, and aquatic plants) are potential receptors in adjacent water bodies through off-site 

transport of tefluthrin from the application site through runoff and erosion. 
-26 of 50-

Figure 3. Conceptual Diagram Depicting Potential Risks to Terrestrial and Aquatic 

Animals from the Use of Tefluthrin as an insecticide 

7. Analysis Plan 

In order to address the risk hypothesis, the potential for adverse effects on the environment will 

be estimated. The use, environmental fate, and ecological effects of tefluthrin will be 

characterized and integrated to assess the risks. This will be accomplished using a risk quotient 

(ratio of exposure concentration to effects concentration) approach. Although risk is often 

defined as the likelihood and magnitude of adverse ecological effects, the risk quotient-based 

approach does not provide a quantitative estimate of likelihood and/or magnitude of an adverse 

effect. However, as outlined in the Overview Document (USEPA 2004), the likelihood of effects 

to individual organisms from particular uses of tefluthrin may be estimated using the probit doseresponse slope and either the level of concern (discussed below) or the actual calculated risk 

quotient value. 

Stressor 

Source/ 

Transport 

Pathway 

Source/ 

Exposure 

Media 

Exposure 

Method 

Receptors 

Direct 

Effects: 

NonEndangered 

Species 

Indirect 

Effects 

Food Web 

Dynamics 

Perturbed Forage or 

Prey Availability 

Habitat Alteration: impacts on nesting 

ability, ability to seek cover, etc. 

Individual Terrestrial 

Animals

Reduced Survival 

Reduced Growth 

Reduced Reproduction 

Individual Terrestrial 

Plants

Seedling Emergence 

Vegetative Vigor 

Individual Aquatic 

Vertebrates and 

Invertebrates

Reduced Survival 

Reduced Growth 

Reduced Reproduction 

Aquatic Plant 

Population

Reduced 

Growth Rates 

and Biomass 

Terrestrial Animals 

(Birds, Mammals, 

Reptiles, Terrestrialphase Amphibians, Bees) 

Terrestrial 

Upland Plants 

Wetland/ 

Riparian 

Plants 

Runoff and Erosion 

Upland 

Foliage/ 

Soil 

Riparian/ 

Wetland 

Foliage/Soil 

Surface 

Water, 

Sediment 

Direct Contact/ 

Root Uptake 

Gill/ Integument 

Uptake 

Direct Contact/ 

Root Uptake 

Ground

water 

Direct 

Ingestion 

Aquatic Invertebrates 

Aquatic Vertebrates 

Aquatic Plants 

Leaching 

(Infiltration/ 

Percolation)

Terrestrial Food 

Residues 

(foliage, fruit, 

insects)/Soil

Dietary 

uptake 

Tefluthrin
-27 of 50-

This analysis plan will be revisited and may be revised depending upon the information 

submitted by the public in response to the opening of the Registration Review docket for 

tefluthrin. 

7.1. Stressors of Concern 

Tefluthrin is a synthetic pyrethroid insecticide. Its structure has two rings, one phenyl ring and a 

cyclopropyl ring. It is not substituted in the alpha position (thus, it is a type I synthetic 

pyrethroid). The chemistry of tefluthrin may be dictated by its ester moiety; this is substantiated 

by the hydrolysis study, in which the chemical is stable at pH 5 and 7, but it undergoes partial 

hydrolysis at the highest pH of 9. The structure of the molecule has two chiral centers in the 

cyclopropyl group, and a double bond that could result in a total of 8 isomers. Chemically, it is 

the (Z)-(IR)-cis-acid and the (Z)-(1 S)-cis-acid out of eight isomeric esters. Tefluthrin is 

tetrafluoro substituted in the phenyl ring, and it has a trifluoromethyl group in the double bond 

attached to the cyc1opropyl ring. Key et al. 1997 expressed concerns over several polyfluorinated compounds, including tefluthrin's fate in the environment. In the article, it is argued 

that these moieties (the polyfluorinated phenyl ring and the trifluoromethyl group) are persistent 

in the environment. Examples are shown in Table 3, where the last two degradates (2,3,5,6-

tetrafluoro-4-methylbenzoic acid, and 2,3,5,6-tetrafluoro-1,4-benzenedicarboxylic acid) have 

structural similarities with oxons. 

7.2. Measures of Exposure 

In order to estimate risks of tefluthrin exposures in aquatic and terrestrial environments, exposure 

modeling will be based on maximum application rates and methods cited in Table 1. Measures 

of exposure are based on aquatic and terrestrial models that predict estimated environmental 

concentrations (EECs) of tefluthrin. For agricultural uses, exposure concentrations for aquatic 

ecosystems assessments will be estimated based on EFED's Tier II aquatic model 

PRZM/EXAMS. A graphical user interface (PES v. 5.0, November 15, 2006) developed by the 

EPA (http://www.epa.gov/oppefedl/models/water) will be used to facilitate inputting chemical 

and use specific parameters into the appropriate PRZM input files (*.inp) and EXAMS chemical 

files. 

The Pesticide Root Zone Model (PRZM v. 3.12.2, May 12, 2005) field or orchard crop scenario 

is the basic file which describes the local or regional climatological information, soil hydrology 

soil characteristics, crop characteristics, and the pesticide properties necessary to determine 

pesticide loadings to ground or surface water. This basic file constitutes the first part of the 

"exposure scenario." It simulates the processes in the agricultural field, such as runoff and 

erosion, on a daily time step. The runoff and erosion flux output data from PRZM are used as 

chemical loadings to the Exposure Analysis Modeling System (EXAMS v. 2.98.04.06, April 25, 

2005), which simulates surface water, in order to predict the EECs. EECs for ecological risk 

assessment were determined using a pond modeling scenario which describes a standard scenario 

for the EXAMS component of the modeling exercise. 
-28 of 50-

Given the aquatic toxicity of tefluthrin 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 l-in-l0-year peak and 21-day mean EECs 

for pore water. 

The model used to predict terrestrial EECs on food items is the Terrestrial Residue Exposure 

model (T-REX). The model used to derive EECs relevant to terrestrial plants is TerrPlant. These 

models are parameterized using relevant reviewed environmental fate data from registrant 

submissions and the literature. Model input values will be consistent with the most recent version 

of the input parameter guidance (Version 2.1; USEPA 2009). 

Exposure estimates for terrestrial organisms assumed to be in the target area or in an area 

exposed to off-site deposition are derived using the T-REX model (version 1.4.1, 10/09/2008). 

Given that the registered uses are for seed treatment or in-furrow application, the foliar exposure 

portion of T-REX will not apply. The seed treatment and/or LD50/sq ft aspects of the model are 

likely to be used in the risk assessment. 

In order to determine if inhalation is a potential pathway of concern for terrestrial organisms, the 

Screening Tool for Inhalation Risk (STIR v.1.0) was used to calculate an upper bound estimate 

of exposure using tefluthrin’s vapor pressure and molecular weight for vapor phase exposure as 

well as the maximum application rate and method of application for spray drift. STIR 

incorporates results from several toxicity studies including acute oral and inhalation rat toxicity 

endpoints obtained from the “six-pack” of core studies, which are a series of six guideline studies 

that are submitted to the Registration Division of the Office of Pesticide Programs for technical 

and formulated products of a pesticide as well as the most sensitive acute oral avian toxicity 

endpoint. A per-acre application rate of 2.0 lbs ai/A was assumed for tefluthrin, as the labels 

give application rates in lbs ai/linear foot. This assumed rate uses a 660 foot row and 330 rows 

per acre. Based on the results of the STIR model, inhalation exposure alone was not determined 

to be a potential pathway of concern for avian or mammalian species on an acute exposure basis. 

Inhalation exposure via vapor-phase of the pesticide alone does not appear to be of concern. The 

analysis of the inhalation route in STIR does not consider that aggregation with other exposure 

pathways such as dietary, dermal, or drinking water may contribute to a total exposure that has a 

potential for effects to non-target animals. However, the Agency does consider the relative 

importance of other routes of exposure in situations where data indicate that pesticide exposures 

through other routes may be potentially significant contributors to wildlife risk (USEPA, 2004). 

The risk assessment will discuss the impact of consideration of other routes of exposure that 

have been identified as potentially important and the degree of certainty associated with 

screening-level risk assessment conclusions. Detailed information about STIR v.1.0, as well as 

the tool, can be found on the EPA’s website 

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

The Screening Imbibition Program (SIP v.1.0) was used to calculate an upper bound estimate of 

exposure using tefluthrin’s solubility, the most sensitive acute and chronic avian and mammalian 
-29 of 50-

toxicity endpoints. Drinking water exposure alone was determined to be a not to be a potential 

pathway of concern for avian or mammalian species on an acute or chronic exposure basis. 

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

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

EECs for terrestrial plants are derived using TerrPlant (v.1.2.2). This model uses estimates of 

pesticides in runoff and in spray drift to calculate EECs. EECs are based upon solubility, 

application rate and minimum incorporation depth. 

The KABAM (KOW (based) Aquatic BioAccumulation Model v1.0) may be used to estimate 

potential bioaccumulation of hydrophobic organic pesticides in freshwater aquatic food webs and 

subsequent risks to mammals and birds via consumption of contaminated aquatic prey. 

7.3. Measures of Effect 

 

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

Effects data are obtained from registrant-submitted studies or from literature studies identified by 

the ECOTOX database. 

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. NOAEL stands 

for “No Observed-Adverse-Effect-Level” and refers to the highest tested dose of a substance that 

has been reported to have no harmful (adverse) effects on test organisms. The NOAEC (i.e., 

“No-Observed-Adverse-Effect-Concentration”) is the highest test concentration at which none of 

the observed effects were statistically different from the control. For non-listed plants, only acute 

exposures are assessed (i.e., IC25 for terrestrial plants and IC50 for aquatic plants); for listed 

plants either the NOAEC or EC05 is used. 

Where available, sublethal 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). However, quantitative assessments of risks are limited to 

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

survival, growth and reproduction. 

In the absence of taxon-specific data, the assessment of risk for direct effects to non-target 

organisms makes the assumption that toxicity of tefluthrin to birds is similar to terrestrial-phase 

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

the absence of data for either acute or chronic effects, the conservative assumption will be to 

presume that tefluthrin is toxic. 
-30 of 50-

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 registered uses of tefluthrin 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 tefluthrin 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 are used to indicate when tefluthrin use, as 

directed on the labels, has the potential to cause adverse direct or indirect effects to non-target 

organisms. In addition, incident data from the EIIS will be considered as part of the risk 

characterization. 

7.5. Deterministic and Probabilistic Assessment Methods 

The quantitative assessment of risk will primarily depend on the deterministic point-estimate 

(RQ) based approach described in the risk assessment. An effort will be made to further 

qualitatively describe risk using probabilistic tools that the Agency has developed. These tools 

have been reviewed by FIFRA Scientific Advisory Panels 

(http://www.epa.gov/scipoly/sap/index.htm) and have been deemed as appropriate means of 

refining assessments where deterministic approaches have identified risks. Newer tools may be 

available to assess the routes of exposure (e.g. TIM and SWAMP models) and will be applied as 

appropriate in Registration Review. 

7.6. Endocrine Disruptor Screening Program

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of registration review decision, EPA will review these data and select 

the most sensitive endpoints for relevant risk assessment scenarios from the existing hazard 

database. However, as required by FFDCA section 408(p), tefluthrin is subject to the endocrine 

screening part of the Endocrine Disruptor Screening Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 

may designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 
-31 of 50-

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine-related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between 

October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 

chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. Tefluthrin is 

not among the group of 58 pesticide active ingredients on the initial list to be screened under the 

EDSP. Accordingly, as part of registration review, EPA will issue future EDSP orders/data callins, requiring the submission of EDSP screening assays for tefluthrin. For further information on 

the status of the EDSP, the policies and procedures, the list of 67 chemicals, future lists, the test 

guidelines and the Tier 1 screening battery, please visit our website: http://www.epa.gov/endo/. 

7.7. Endangered Species Assessment 

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 tefluthrin. 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 tefluthrin 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 tefluthrin application 

occurs), plus all areas where offsite transport (i.e., spray drift, runoff, etc.) may result in potential 

exposure that exceeds the Agency’s LOCs. Specific measures of ecological effect that define the 

action area for listed species include any direct and indirect effects and/or potential modification 

of its critical habitat, including reduction in survival, growth, and reproduction as well as the full 

suite of sublethal effects available in the effects literature. Therefore, the action area extends to a 

point where environmental exposures are below any measured lethal or sublethal effect threshold 

for any biological entity at the whole organism, organ, tissue, and cellular level of organization. 

In situations where it is not possible to determine the threshold for an observed effect, the action 

area will initially be assumed to include all counties where tefluthrin is used in the United States. 
-32 of 50-

7.8. Drinking Water Assessment 

In order to bring the drinking water exposure assessment up to date with current data, models 

and simulation model guidance, a new drinking water assessment will be conducted to support 

future human health dietary risk assessments of tefluthrin. The drinking water exposure 

assessment will be conducted for the maximum labeled use in support of the human health 

dietary risk assessment. The drinking water assessment will incorporate model estimates of 

tefluthrin alone in surface water and ground water including any residues that are determined to 

be of toxicological concern. Concentrations of tefluthrin in surface waters (Estimated Drinking 

Water Concentrations, or EDWCs) will be estimated using PRZM/EXAMS (see description 

above) but using the Index Reservoir scenario rather than the standard pond used for assessment 

of exposure in drinking water. 

EFED does not anticipate conducting a new DWA. 

An EDWC of tefluthrin in groundwater will be estimated using EFED’s Tier I aquatic model 

SCIGROW (Screening Concentration in GROundWater, version 2.3; 8/8/2003). SCIGROW is a 

regression model used as a screening tool to estimate pesticide concentrations found in ground 

water used as drinking water. The output of SCIGROW represents the concentrations that might 

be expected in shallow unconfined aquifers under sandy soils, which is representative of the 

ground water most vulnerable to pesticide contamination likely to serve as a drinking water 

source. 

7.9. Environmental Monitoring Data 

A query of the United States Geological Survey’s (USGS) National Water Quality Assessment 

Program (NAWQA) for detections of tefluthrin in surface water, groundwater, and sediments 

samples collected nationwide during the period of 2008 to 2011 (2001-2002 for groundwater 

samples) are shown in Table 10. 

Table 10. NAWQA Tefluthrin monitoring results for surface water, groundwater, and 

sediments.

SURFACE WATER GROUNDWATER SEDIMENTS 

Form No. 

Samples 

concentrations 

range 

(ug/l) 

No. Samples concentrations 

range 

(ug/l) 

No. 

Samples 

concentratio

ns range 

(ug/kg) 

Tefluthrin 6525 No detection 3879 No detection 78 No detection 

Tefluthirn Acid 

benzyl ester 

202 No detection 235 No detection Not 

analyzed 

for 

Not analyzed 

for 

Tefluthirn Acid 

pentaflourobenzyl 

ester 

202 No detection 235 No detection Not 

analyzed 

for 

Not analyzed 

for 

7.10. Water Quality 

Aquatic Life Criteria and Aquatic Life Benchmarks 
-33 of 50-

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. US 

EPA Aquatic Life Ambient Water Quality Criteria document has not been published for 

tefluthrin (at http://www.epa.gov/waterscience/criteria/ accessed 06/08/12). 

For tefluthrin, OPP has not published aquatic life benchmarks for freshwater species, based on 

the most sensitive species from the most recent risk assessments (refer to the following site 

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

06/08/12). 

Impaired Water Bodies 

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

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

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

(accessed 06/08/12). However, the pyrethroids as a group have been identified as a cause for 

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

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

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

bodies of water were evaluated and included into the list of impaired bodies of water by October 

2011 (see http://www.waterboards.ca.gov/water_issues/programs/tmdl/integrated2010.shtml, 

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

http://www.epa.gov/region9/water/tmdl/303d-pdf/Final-DecisLtrEnclosResponsSumCA2008-10-

303d.pdf accessed 06/08/12). The 2010 303(d) list for California contains 10 additional streams 

due to pyrethroids in the sediments. EFED will include relevant information on 303(d) listings 

in the final ecological risk assessment as appropriate. The Division will also evaluate whether 

tefluthrin was involved as one of the causes of impairment. 

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

based on information provided at 

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

=885&p_pollutant_group_name=PESTICIDES (accessed 06/08/12). It appears that a TMDL 

was established for pyrethroids and specifically for bifenthrin, another synthetic pyrethroid (Rio 

de Santa Clara/Oxnard Drain No. 3). 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 (at

http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm accessed 06/08/12), in 

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

8.0. Preliminary Identification of Data Gaps 
-34 of 50-

Additional data needed for the risk assessment include label clarification. According to the 

LUIS report, tefluthrin use is not limited in number of applications. While it seems clear that 

tefluthrin is only applied at planting, verification and appropriate label statements will clarify this 

issue. Additionally, rates are provided only as lbs ai/linear foot or lbs ai/ lb of seed. Unless 

these rates are put onto labels as maximum mass per unit area, conservative assumptions will 

need to be employed at the time of the risk assessment. 

 8.1. Environmental Fate 

The studies submitted to fulfill environmental fate data requirements for tefluthrin are not 

sufficient to conduct an exposure assessment; three requirements have not been met as stipulated 

in 40 CFR part 158 Subpart N §158.1300 for all pesticides with use patterns for aquatic food and 

nonfood applications: 

 Aerobic aquatic metabolism (GLN 835.4300). There is one unacceptable study 

for this guideline (MRID# 47813003). An additional aerobic aquatic metabolism 

study, conducted in one sediment system should be submitted. 

 Anaerobic aquatic metabolism (GLN 835.4400). There is one unacceptable 

study for this guideline (47813004). 

A new anaerobic aquatic metabolism study should be submitted. Two sediment 

systems are required. Submission of an acceptable anaerobic aquatic metabolism 

study is necessary to understand the degradation of tefluthrin in oxygen-limiting 

environments. 

 The environmental chemistry analytical methods and independent 

laboratory (ILV) portions (only) of the of the terrestrial field dissipation 

(835.6100) and the aquatic field dissipation study (835.6200) rather than the full 

field dissipation study. 

The registrant of tefluthrin submitted various aerobic and anaerobic soil and aquatic metabolism 

studies, and an adsorption/ desorption (batch equilibrium) study. The EFED evaluated all the 

information available and the results are summarized in Table 11. 
-35 of 50-

Table 11. Environmental Fate Data Requirements for Tefluthrin 

Guideline 

Number Data Requirement MRID 

Study 

Classification1

Are Additional 

Data Needed 

for Risk 

Assessment

835.4100 

835.4300 

Aerobic Soil Metabolism

Aerobic Aquatic Metabolism 

47813003 Supplemental 

Unacceptable 

No

Yes2 

835.4300 

835.4400 

Aerobic Aquatic Metabolism 

Anaerobic Aquatic Metabolism 

47813004 Supplemental 

Unacceptable 

Yes2

Yes3 

835.4300 Aerobic Aquatic Metabolism 47813005 Unacceptable Yes2

835.1230 Adsorption/ Desorption (Batch Equilibrium) 47813006 Supplemental No 

1

Acceptable: study satisfies guideline; Supplemental: study is scientifically sound, but does not satisfy guideline; 

Unacceptable: study is not scientifically sound and does not satisfy guideline. 2

 An additional aerobic aquatic metabolism study, conducted in one sediment system should be submitted. 3

 A new anaerobic aquatic metabolism study should be submitted. Two sediment systems are required. 

Table 12 identifies studies by MRID that offer data for each guideline requirement, as well as 

study classifications and whether or not further data are needed in order to support risk 

assessment (i.e., whether there is a data gap). 

Table 12. Summary of available environmental fate data. 

Guideline Study Title MRID / 

ACC No. Classification Data Gap? Comments 

835.2120 Hydrolysis 40141332 Acceptable No 

835.2240 Photodegradation 

in Water 

40161141 Acceptable No 

835.2410 Photodegradation 

on Soil 

40161142 Acceptable No 

835.4100 Aerobic Soil 

Metabolism 

40161143 

47813003 

Acceptable 

Supplemental No 

835.4200 Anaerobic Soil 

Metabolism 40161143 Acceptable No 

835.4300 Aerobic Aquatic 

Metabolism 

47813004 

47813005 

Supplemental 

Unacceptable Yes 

An additional aerobic aquatic metabolism study, 

conducted in one sediment system should be 

submitted. 

835.4400 

Anaerobic 

Aquatic 

Metabolism 

47813004 Unacceptable Yes New anaerobic aquatic metabolism study should be 

submitted. Two sediment systems are required. 

835.1240, 

835.1230 

Mobility - 

Adsorption / 

Desorption 

261402 

40161144 

47813006 

Acceptable 

Acceptable 

Supplemental 

No 

835.6100 Terrestrial Field 

Dissipation 

40161145 

40161147 Supplemental 

Acceptable No 
-36 of 50-

Guideline Study Title MRID / 

ACC No. Classification Data Gap? Comments 

850.1730 Fish 

Accumulation 

40141333 

Acceptable Acceptable No 

8.2. Ecological Effects 

The available ecological effects dataset for tefluthrin is incomplete (Tables 13-15). Acute avian 

toxicity data (850.2100) on a passerine species are necessary, as is a honeybee acute contact 

study (850.2030). Guideline chronic exposure studies with estuarine/marine fish and 

invertebrates are not available for tefluthrin and are necessary for risk assessment, as are a suite 

of studies specific to pyrethroids including Hyallela spp water column and multiple species 

sediment testing as listed below. 

Given the use patterns and chemical properties of tefluthrin, aquatic plant species are expected to 

be exposed to tefluthrin through erosion of treated soil particle. Therefore, data on the effects (or 

lack thereof) to aquatic species are necessary for risk assessment. 

There are no phytotoxicity data for terrestrial plant species. Two incident reports filed with the 

EPA involved adverse effects to terrestrial plants, but these were reported to be from 

unincorporated broadcast applications, which are not allowed by label. It is possible that 

tefluthrin may exhibit phytotoxicity to certain sensitive plant species, but given the labeled 

application methods (seed treatment/soil treatment), exposure to terrestrial plants is expected to 

be negligible. 

The available effects dataset is considered incomplete for the purposes of risk assessment. The 

following data gaps exist: 

 Freshwater and estuarine/marine spiked whole-sediment chronic tests, TGAI. 

Test Method 100.4 (OCSPP 850.1770, in prep.); Whole sediment: chronic invertebrates 

freshwater (Hyalella azteca) 

Test Method 100.5 (OCSPP 850.1760, in prep.); Whole sediment: chronic invertebrates 

freshwater (Chironomus dilutus) 

EPA 600/R-01/020 (OCSPP 850.1780, in prep.); Whole sediment: chronic invertebrates 

marine (Leptocheirus plumulosus). There are no data available regarding chronic toxicity 

of tefluthrin to benthic organisms, an exposure compartment of concern. For pyrethroids, 

spiked whole sediment chronic toxicity data for Hyalella azteca, Chironomus dilutus, and 

Leptocheirus plumulosus are necessary for risk assessment. 

 Aquatic Invertebrate TGAI Acute Toxicity with Hyalella azteca (Non-guideline 

special study). Available information indicates that the freshwater amphipod, H. azteca, 

is substantially more sensitive to pyrethroids than Daphnia magna, the commonly tested 

freshwater invertebrate (e.g., Anderson et al. 2006; Maund et al., 2002). Therefore, in 

order to ensure that risks to sensitive aquatic invertebrates are appropriately quantified 
-37 of 50-

additional acute toxicity testing of H. azteca is needed (water-only exposure tests, no 

sediment present). 

 Mysid Chronic Toxicity study (GLN 850.1350). As discussed in the document, mysids 

are generally far more acutely sensitive to tefluthrin than daphnids and exposure to 

estuarine/marine environments is likely. In the absence of these data, an acute-to-chronic 

ratio based on the daphnid data would be used; however this may result in 

underestimation of potential risk. 

 Avian acute oral study with a passerine (GLN 850.2100). Data on the toxicity of 

tefluthrin to passerines are necessary for risk assessment. A registrant submission 

examining the potential toxicity of tefluthrin to the house sparrow (Passer domesticus; 

MRID 40161123) is being reviewed to determine if it can be used to fulfill this data 

requirement. Provisionally, the study indicates passerines as more sensitive to tefluthrin 

than bobwhite or mallard. 

 Honey bee acute contact toxicity study (GLN 850.3020). No data are available to 

assess the potential toxicity of tefluthrin to beneficial invertebrates. As an insecticide, 

effects to terrestrial invertebrates are expected, but a hazard threshold has not been 

established. 

 Aquatic vascular plant study (GLN 850.4400). There are no data available regarding 

the toxicity of tefluthrin to aquatic vascular plants. Aquatic ecosystems are likely to be 

exposed to tefluthrin through erosion of treated soil particles to which it is sorbed. These 

data are necessary for risk assessment. 

 Aquatic non-vascular plant testing: one for each of 4 species (GLN 850.5400). There 

are no data available regarding the toxicity of tefluthrin to aquatic non-vascular plants. 

Aquatic ecosystems are likely to be exposed to tefluthrin through erosion of treated soil 

particles to which it is sorbed. These data are necessary for risk assessment. 

 Terrestrial Plant Toxicity-Seedling Emergence (GLN 850.4100). No data on the 

toxicity of tefluthrin to terrestrial plants is available. Because tefluthrin may runoff the 

treated field to nontarget areas, effects to terrestrial plant seedling emergence may occur. 

Due to the current use patterns, spray drift is not expected therefore a vegetative vigor 

study is not necessary at this time. 

TABLE 13. Available ecological effects data for terrestrial animals exposed to tefluthrin 

Guideline 

# Data Requirement Test Species MRID Study Classification 

More Data Needed 

for Risk Assessment? 

850.2100 

(71-1) Avian Oral LD50

Mallard Duck 00156766 Acceptable No 

House Sparrow 

(Passer 

domesticus) 

40161123 Under review Yes1
-38 of 50-

Guideline 

# Data Requirement Test Species MRID Study Classification 

More Data Needed 

for Risk Assessment? 

850.2200 

(71-2) Avian Dietary LC50

Mallard duck 00156768 Acceptable No 

Bobwhite quail 00156767 Acceptable No 

850.2300 

(71-4) 

Avian 

Reproduction 

Mallard duck 40161124 Acceptable No 

Bobwhite quail 40161125 Acceptable No 

850.3020 

(141-1) 

Honeybee acute 

contact toxicity 

Honeybee (Apis 

mellifera) 

No data 

received N/A Yes 

1

data are under review; until the review is complete EFED cannot be certain the data are sufficient for risk 

assessment. 

TABLE 14. Available ecological effects data for aquatic animals exposed to tefluthrin. 

Guideline 

# Data Requirement Test Species MRID Study Classification 

More Data Needed 

for Risk 

Assessment? 

850.1075 

(72-1) Freshwater Fish LC50

Rainbow trout 00156769 Acceptable No 

Bluegill sunfish 00156770 Acceptable 

850.1010 

(72-2) 

Freshwater Invertebrate 

Acute LC50

Water flea 

(Daphnia 

magna) 

40161132 Acceptable No 

850.1075 

(72-3a) 

Estuarine/Marine Fish 

Acute LC50

Sheepshead 

minnow 40161137 Acceptable No 

850.1300 

(72-4) 

Freshwater Invertebrate 

Life Cycle 

Water flea 

(Daphnia 

magna) 

41229501 Acceptable No 

850.1055 

(72-3) 

Marine/Estuarine 

Bivalve Acute Toxicity 

Test 

Pacific oyster 

(Crassotrea 

gigas)

40161135 Acceptable No 

850.1053 

(72-4) 

Estuarine/Marine 

Invertebrate Acute LC50

Mysid shrimp 40161136 Acceptable No 

850.1350 

(72-4) 

Estuarine/Marine 

Invertebrate Life Cycle Mysid shrimp No data 

received N/A Yes1

850.1400 

(72-4) 

Freshwater Fish Early 

Life Stage Fathead minnow 41705101 Acceptable No 

850.1400 

(72-4) 

Estuarine/Marine Fish 

Early Life Stage(1) -- No data 

received N/A No 

1

fish data are insufficient for an acute-to-chronic ratio (ACR) to be reliably calculated. 

TABLE 15. Available ecological effects data for plants exposed to tefluthrin. 

Guideline # Data Requirement Test Species MRID Study 

Classification 

More Data Needed for 

Risk Assessment? 

850.4110 

(121-1) 

(123-1) 

Seedling Emergence Multiple 

species 

No data 

received N/A Yes 
-39 of 50-

850.4150 

(121-1) 

(123-1) 

Vegetative Vigor Multiple 

species 

No data 

received N/A No 

850.4400 

(122-2) 

(123-2) 

Aquatic Vascular 

Plant Toxicity 

Duckweed 

(Lemna gibba) 

No data 

received N/A Yes 

850.5400 

(122-2) 

(123-2) 

Aquatic Nonvascular 

Plant Toxicity 

Multiple 

species 

No data 

received N/A Yes 

9. References 

Open Literature Citations 

Armitage, J. M., & Gobas, F. A P. e. 2007. A terrestrial food-chain bioaccumulation model for 

POPs. Environmental Science and Technology, 41,4019-4025. 

Di Toro, DM, CS Zarba, DJ Hansen, WJ Berry, RC Swartz, CE Cowan, SP Pavlou, HE Allen, 

NA Thomas and PR Paquin. 1991. Technical basis for establishing sediment quality criteria for 

nonionic organic chemicals using equilibrium partitioning. Environ. Toxicol. Chem. 10:1541-

1583. 

Fletcher, J.S., J.E. Nellessen, and T.G. Pfleeger. 1994. Literature review and evaluation of the 

EPA food-chain (Kenaga) nomogram, an instrument for estimating pesticide residues on plants. 

Environ. Tox. Chem. 13:1383-1391. 

Gobas, F. A P. e., Kelly, B. e., & Arnot, J. A 2003. Quantitative structure activity t:elationships 

for predicting the bioaccumulation of POPs in terrestrial food-webs. QSAR Comb. Sci, 22, 

329-336

Hoerger, F., and E.E. Kenaga. 1972. Pesticide residues on plants: Correlation of representative 

data as a basis for estimation of their magnitude in the environment. In F. Coulston and F. Korte, 

eds., Environmental Quality and Safety: Chemistry, Toxicology, and Technology, Georg Thieme 

Publ, Stuttgart, West Germany, pp. 9-28. 

Key, B., R Howell and C. Criddle. 1997. Fluorinated Organics in the Biosphere. Environ. Sci. 

& Technol. 31(9), 1997, pp. 2445-2454.

U.S. Fish and Wildlife Service (USFWS) and National Marine Fisheries Service (NMFS). 1998. 

Endangered Species Consultation Handbook: Procedures for Conducting Consultation 

and Conference Activities Under Section 7 of the Endangered Species Act. Final Draft. 

March 1998. 

USEPA. 2007. Bradbury, S. Guidance for Tier I Estimation of Aqueous Pesticide 

Concentrations in Rice Paddies. U.S. Environmental Protection Agency, Office of 

Prevention, Pesticides and Toxic Substance, Environmental Fate and Effects Division. 

Internal Memorandum. May 8, 2007. 
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USEPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and 

Toxic Substances, Office of Pesticide Programs, Washington DC. January 23, 2004. 

USEPA. 1998. Guidelines for Ecological Risk Assessment. Risk Assessment Forum, Office of 

Research and Development, Washington, D.C. EPA/630/R-95/002F. April 1998. 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=30759 

USDA, 2006-2010. NASS Crop Reporting Districts. Online: 

http://www.ers.usda.gov/briefing/arms/resourceregions/resourceregions.htm#nass. 

Willis, G.H. and L.L. McDowell. 1987. Pesticide Persistence on Foliage in Reviews of 

Environmental Contamination and Toxicology. 100:23-73. 
-41 of 50-

Submitted Fate Studies 

161-1 Hydrolysis 

MRID Citation Reference 

156762 Hall, J.; Leahey, J. (1983) PP993: Hydrolysis in Sterile Distilled Water at 3 

Different pH's: Report Series RJ 0335B. Unpublished study prepared by ICI 

Plant Protection Div. 18 p. 

40141332 Steward, J.; Leahey, J. (1986) Tefluthrin: Hydrolysis at pH5, 7 and 9 in Sterile 

Aqueous Solutions: Laboratory Project ID: RJ0512B. Unpublished study 

prepared by ICI Plant Protection Div., Jealott's Hill Research Station. 30 p. 

161-2 Photodegradation-water 

MRID Citation Reference 

156763 Woods, T.; Leahey, J. (1984) PP993:- Photolysis in Water at pH7: Report 

Series RJ 0346B. Unpublished study prepared by ICI Plant Protection Div. 28 

p. 

40161141 Amos, R.; Leahey, J. (1987) Tefluthrin: Photodegradation in Sterile Water at 

pH7: Laboratory Project ID: RJ0562B. Unpublished study prepared by ICI 

Plant Protection Div., Jealott's Hill Research Station. 64 p. 

161-3 Photodegradation-soil 

MRID Citation Reference 

40161142 Amos, R.; Leahey, J. (1987) Tefluthrin: Photolysis on a Soil Sur- face: 

Laboratory Project ID: RJ0563B. Unpublished study pre- pared by ICI Plant 

Protection Div., Jealott's Hill Research Sta- tion. 61 p. 

40161148 Hill, I. (1987) Tefluthrin: Comparison of Results from Soil Degra- dation and 

Dissipation Studies: Laboratory Project ID: M4418B. Unpublished study 

prepared by ICI Plant Protection Div., Jea- lott's Hill Research Station. 33 p. 

162-1 Aerobic soil metabolism 

MRID Citation Reference 

40161143 Pluckrose, J.; Bewick, D. (1986) Tefluthrin: Further Studies on Degradation in 

Soil: Laboratory Project ID: RJ0525B. Unpub- lished study prepared by ICI 
-42 of 50-

Plant Protection Div., Jealott's Hill Research Station. 43 p. 

47813003 Bewick, D.; Weissler, M. (1985) Tefluthrin: PP993 - Degradation in Soil: Final 

Report. Project Number: RJ/0423B, T000311/09. Unpublished study 

prepared by Jealott's Hill Research Station. 54 p. 

Not 

provided 

 Bharty, H., D.W. Bewick, and R.D. White PP563 and PP321 Degradation in 

Soil 

162-2 Anaerobic soil metabolism 

MRID Citation Reference 

40161143 Pluckrose, J.; Bewick, D. (1986) Tefluthrin: Further Studies on Degradation in 

Soil: Laboratory Project ID: RJ0525B. Unpub- lished study prepared by ICI 

Plant Protection Div., Jealott's Hill Research Station. 43 p. 

162-3 Anaerobic aquatic metab. 

MRID Citation Reference 

47813004 Dean, G. (1995) (Carbon 14) Tefluthrin: Degradability and Fate in a WaterSediment Under Aerobic, Anaerobic and Sterile Conditions: Final Report. 

Project Number: ISN/3321/950441, T000312/09. Unpublished study prepared 

by Huntingdon Research Center. 121 p. 

162-4 Aerobic aquatic metab. 

MRID Citation Reference 

47813003 Bewick, D.; Weissler, M. (1985) Tefluthrin: PP993 - Degradation in Soil: Final 

Report. Project Number: RJ/0423B, T000311/09. Unpublished study 

prepared by Jealott's Hill Research Station. 54 p. 

47813004 Dean, G. (1995) (Carbon 14) Tefluthrin: Degradability and Fate in a WaterSediment Under Aerobic, Anaerobic and Sterile Conditions: Final Report. 

Project Number: ISN/3321/950441, T000312/09. Unpublished study prepared 

by Huntingdon Research Center. 121 p. 

47813005 Vonk, J. (1990) Tefluthrin: Biodegradation of Tefluthrin in a Static 

Water/Sediment System: Final Report. Project Number: R/89/382A, 

T000313/09. Unpublished study prepared by TNO. 46 p. 

163-1 Leach/adsorp/desorption 

MRID Citation Reference 
-43 of 50-

156765 Stevens, J.; Bewick, D. (1985) PP993: Leaching of PP993 and Its 

Degradation Products in Soil Columns: Report Series RJ 0428B. 

Unpublished study prepared by ICI Plant Protection Div. 17 p. 

40161144 Pluckrose, J.; Vickers, J.; Bewick, D. (1987) Tefluthrin: Adsorp- tion and 

Desorption in Soil: Laboratory Project ID: RJ0542B. Unpublished study 

prepared by ICI Plant Protection Div., Jea- lott's Hill Research Station. 31 

p. 

42201601 Travis, K.; Wadley, A. (1992) The Distribution of Tefluthrin Between the 

Adsorbed and Dissolved Phase in Runoff. Unpublished study prepared by 

ICI Agrochemicals, Jeallott's Hill Research Station. 29 p. 

42201602 Brusseau, M.; Rao, P. (1989) Sorption nonideality during organic 

contaminant transport in porous media. Critical Reviews in Environmental 

Control 19(1): 33-99. 

42201603 DiToro, D. (1985) A particle interaction model of reversible organic 

chemical sorption. Chemosphere 14(10):1503-1538. 

42201606 Wallach, R.; Jury, W.; Spencer, W. (1988) Transfer of chemicals from soil 

solution to surface runoff: A diffusion- based soil model. Soil Science Soc 

AM. J., 52(1988):612-618. 

42201608 Ahuja, L. (1990) Modeling soluble chemical transfer to runoff with rainfall 

impact as a diffusion process. Soil Science Soc. AM. J., 54(1990):312-321. 

42201609 Ahuja, L. (1986) Characterization and modeling of chemical transfer to 

runoff. Adv. Soil Science 4(1986):149-188. 

42201610 Hillel, D. (1992) Introduction to Soil Physics: Force 1.5G. Unpublished 

study prepared by ICI Americas Inc. 5 p. 

42201611 Hartley, ?. (1980) Solubility, partition and adsorption. Physical Properties of 

Pesticides Behavior, Academic Press pp. 11-109. 

47813006 Dean, G. (2001) Tefluthrin: Adsorption and Desorption Properties in Four 

Soils: Final Report. Project Number: GZR/001/013274, T000310/09. 

Unpublished study prepared by Huntingdon Research Center. 92 p. 

164-1 Terrestrial field dissipation 

MRID Citation Reference 

40161145 Fitzpatrick, R. (1987) Tefluthrin: Dissipation in U.S. Soils: Labo- ratory Project 

ID: TMU3086/B. Unpublished study prepared by ICI Americas Inc. 100 p. 

40161146 Murnane, D.; Sapiets, A. (1987) Tefluthrin: Soil Dissipation Study (USA, 

1986): Laboratory Project ID: RJ0570B. Unpublished study prepared by ICI 

Plant Protection Div., Jealott's Hill Research Station. 77 p. 

40161147 Hill, I.; Bewick, D.; Bartlett, D.; et al. (1987) Tefluthrin: Fate of Radiolabled 

Material in Soil under Field Conditions: Labo- ratory Project ID: RJ0546B. 

Unpublished study prepared by ICI Plant Protection Div., Jealott's Hill 

Research Station in co- operation with Huntingdon Research Center Ltd. 173 
-44 of 50-

p. 

40161148 Hill, I. (1987) Tefluthrin: Comparison of Results from Soil Degra- dation and 

Dissipation Studies: Laboratory Project ID: M4418B. Unpublished study 

prepared by ICI Plant Protection Div., Jea- lott's Hill Research Station. 33 p. 

41022601 Murnane, D.; Yearsdon, C.; Sapiets, A. (1988) Tefluthrin: Soil Dissipation 

Study (Canada, 1986-87): Laboratory Project ID: RJ0616B. Unpublished 

study prepared by ICI Americas Inc., Jealott's Hill Research Station. 94 p. 

41392201 Hill, I.; Hadfield, S.; Hendley, P.; et al. (1990) ICI Force 1989 Run-off Study 

Site MS04: An Assessment of its Relevance as a Conventional-Tillage Corn 

Growing Site. Unpublished study prepared by ICI Agrochemicals. 38 p. 

43862202 Killingsworth, D. (1995) Tefluthrin: Soil/Water Release Study from Force 

Granular Formulation: Lab Project Number: TEFL-93-OT-02: RR 94-063B. 

Unpublished study prepared by Zeneca Ag Products. 98 p. 

43862203 Nett, M. (1995) A Comparison of Agricultural Runoff Between (inert 

ingredients) Force 1.5G Insecticide Formulations Using Simulated Rainfall on 

Small Plots: Lab Project Number: 0993-92-RO-01: RR 94-030B. Unpublished 

study prepared by Zeneca Ag Products and PTRL East, Inc. 94 p. 

43862204 Nett, M. (1995) Analytical Report of the 1992 Small Scale Simulated Runoff 

Comparision of Force 1.5G (inert ingredient) Formulations: Lab Project 

Number: RR 94-031B: 0993-92-RO-01: RR 90-373. Unpublished study 

prepared by Zeneca Ag Products and PTRL East, Inc. 76 p. 

43862205 Coody, P.; White, J. (1995) A Comparison of Agricultural Runoff Between 

(inert ingredients) Force 1.5G Insecticide Formulations Using Simulated 

Rainfall on Small Plots and A Study of the Agricultural Runoff of Dyfonate II 

20 G Corn Insecticide Using Simulated Rainfall on Small Plots: Lab Project 

Number: 0993-92-RO-01: 99KY-92-8070: 716. Unpublished study prepared 

by Zeneca Ag Products and PTRL East, Inc. 105 p. 

43862206 Wadley, A.; Travis, K. (1995) Tefluthrin: Modeling Runoff and Aquatic Fate at 

Tier 2: Lab Project Number: TMJ3541B. Unpublished study prepared by 

Zeneca Agrochemicals. 49 p. 

46766710 Hendley, P.; Nett, M. (2006) Tefluthrin: A Comparison of Agricultural Runoff 

Between Force 3G Granule and Microencapsulated Force 30CS 

Formulations Using Simulated Rainfall on Small Plots: Final Report. Project 

Number: T014248/05, 1273, TEFL/99/RO/01. Unpublished study prepared by 

Syngenta Crop Protection, Inc., PTRL East, Inc. and Zeneca Ag Products 

Inc. 292 p. 

165-4 Bioaccumulation in fish 

MRID Citation Reference 

40141330 See 

40141333 

Hamer, M.; Farrelly, E.; French, D.; et al. (1987) Tefluthrin: Accumulation in 

Bluegill Sunfish in a Flow-through System: Labo- ratory Project ID: RJ0521B. 

Unpublished study prepared by ICI Plant Protection Div., Jealott's Hill 

Research Station. 50 p. 

40141333 2070748 Hamer, M.; Farrelly, E.; French, D.; et al. (1987) Tefluthrin: Accumulation in 
-45 of 50-

Bluegill Sunfish in a Flow-through System: Labo- ratory Project ID: RJ0521b. 

Unpublished study prepared by ICI Plant Protection Div., Jealott's Hill 

Research Station. 50 p. 

Submitted Effects Studies 

71-1 Avian Single Dose Oral Toxicity 

MRID Citation Reference 

156766 Roberts, N.; Fairley, C.; Anderson, A.; et al. (1985) The Acute Oral 

Toxicity of PP993 to the Mallard Duck: HRC Report No. ISN 4BT/84939. 

Unpublished study prepared by Huntingdon Research Centre. 40 p. 

40161123 Grimes, J.; Jaber, M. (1986) PP993 Technical: An Acute Oral Toxi- city 

Study with the House Sparrow: Project No. 123-137. Unpub- lished 

study prepared by Wildlife International Ltd. 23 p. 

Accession No. 

261402. 

 Dawe, I.S. and S.F. Johnson (1985) The Acute Oral Toxicity of PP993 

to the Mallard Duck. Prepared by: Huntington Research Centre, 

Cambridgeshire, England. Submitted by Imperial Chemical Industries, 

Cheshire, England. Report No. CTL/C1333. Accession No. 261402.

71-2 Avian Dietary Toxicity 

MRID Citation Reference 

156767 Roberts, N.; Fairley, C.; Anderson, A.; et al. (1985) The Subacute 

Dietary Toxicity of PP993 to the Mallard Duck: HRC Report No. ISN 

6BT/841211. Unpublished study prepared by Huntingdon Reaearch 

Centre. 36 p. 

156768 Roberts, N.; Fairley, C.; Anderson, A.; et al. (1985) The Subacute 

Dietary Toxicity of PP 993 to the Bobwhite Quail: HRC Report No. ISN 

9BT/841205. Unpublished study prepared by Huntingdon Research 

Centre. 39 p. 

71-4 Avian Reproduction 

MRID Citation Reference 

40161124 Roberts, N.; Fairley, C.; Anderson, A.; et al. (1987) The Effect of Dietary 

Inclusion of PP993 on Reproduction in the Mallard Duck: HRC Report 

No. ISN 104BT/861241. Unpublished study prepared by Huntingdon 

Research Center Ltd. 152 p. 
-46 of 50-

40161125 Roberts, N.; Fairley, C.; Anderson, A.; et al. (1987) The Effect of Dietary 

Inclusion of PP993 on Reproduction in the Bobwhite Quail: HRC Report 

No. ISN 103BT/861240. Unpublished study pre- pared by Huntingdon 

Research Center Ltd. 227 p. 

72-1 Acute Toxicity to Freshwater Fish 

MRID Citation Reference 

156769 Hill, R. (1985) PP993: Determination of Acute Toxicity to Rainbow Trout 

(Salmo gairdneri): BL/B/2410. Unpublished study prepared by ICI 

Brixham Laboratory. 19 p. 

156770 Hill, R. (1985) PP993: Determination of Acute Toxicity to Bluegill Sunfish 

(Lepomis macrochirus): BL/B/2411. Unpublished study prepared by ICI 

Brixham Laboratory. 19 p. 

40161126 Hill, R. (1987) Tefluthrin 1.5% Milled Formulation: Determination of 

Acute Toxicity to Rainbow Trout (Salmo gairdneri): Laboratory Project 

ID: BL/B/2957. Unpublished study prepared by ICI Brix- ham 

Laboratory. 16 p. 

40161127 Hill, R. (1987) Tefluthrin 1.5% Milled Formulation: Determination of 

Acute Toxicity to Bluegill Sunfish (Lepomis macrochirus): La- boratory 

Project ID: BL/B/2958. Unpublished study prepared by ICI Brixham 

Laboratory. 15 p. 

40161128 Farrelly, E.; Vincent, J.; Hamer, M.; et al. (1985) PP993: Toxicity to 

Bluegill Sunfish and 3 Aquatic Invertebrates Daphnia, Asellus and 

Mayfly nymphs in the Presence/Absence of Soil: Laboratory Project ID: 

RJ0417B. Unpublished study prepared by ICI Plant Protection Div., 

Jealott's Hill Research Station. 22 p. 

43035102 Farrelly, E.; Vincent, J.; Hamer, M.; et al. (1985) Supplemental 

Information: PP993 (Tefluthrin): Toxicity to Bluegill Sunfish and 3 

Aquatic Invertebrates Daphnia, Asellus and Mayfly Nymphs in the 

Presence/Absence of Soil: Lab Project Number: RJ0417B. Unpublished 

study prepared by Jealotts Hill Research Station. 21 p. 

43862207 Sankey, S.; Holland, M.; Caunter, J. (1992) Tefluthrin: Acute Toxicity to 

Bluegill Sunfish (Lepomis macrochirus) of a 15g/kg GR Formulation: 

Lab Project Number: FT14/92: BL4584/B: W239/B. Unpublished study 

prepared by Zeneca Ltd. 23 p. 

43862208 Sankey, S.; Caunter, J.; Penwell, A. (1992) Tefluthrin: Acute Toxicity to 

Rainbow Trout (Oncorhynchus mykiss) of a 15g/kg GR Formulation: Lab 

Project Number: FT13/92: BL4549/B: W239/A. Unpublished study 

prepared by Zeneca Ltd. 24 p. 
-47 of 50-

72-2 Acute Toxicity to Freshwater Invertebrates 

MRID Citation Reference 

40161128 Farrelly, E.; Vincent, J.; Hamer, M.; et al. (1985) PP993: Toxicity to 

Bluegill Sunfish and 3 Aquatic Invertebrates Daphnia, Asellus and 

Mayfly nymphs in the Presence/Absence of Soil: Laboratory Project ID: 

RJ0417B. Unpublished study prepared by ICI Plant Protection Div., 

Jealott's Hill Research Station. 22 p. 

40161132 Farrelly, E.; Hamer, M.; Hill, I. (1987) Tefluthrin: An Investiga- tion of the 

Toxicity of Granular Formulation: GFU 271 to First Instar Daphnia 

magna: Laboratory Project ID: RJ0531B. Unpub- lished study prepared 

by ICI Plant Protection Div., Jealott's Hill Research Station. 21 p. 

43035103 DER not 

located 

Farrelly, E.; Hamer, M. (1992) Tefluthrin: Acute Toxicity of a 1.5% w/w 

Granular Formulation (GFU524) to First Instar Daphnia Magna: Lab 

Project Number: 92JH083: RJ1214B. Unpublished study prepared by 

Jealotts Hill Research Station. 17 p. 

43035104 DER not 

located 

Farrelly, E.; Hamer, M. (1992) Tefluthrin: Acute Toxicity of a 1.5% w/w 

Granular Formulation (WF1535) to First Instar Daphnia Magna: Lab 

Project Number: 92JH084: RJ1215B. Unpublished study prepared by 

Jealotts Hill Research Station. 17 p. 

156771 DER not 

located 

Farrelly, E.; Hamer, M.; Hill, I. (1984) PP993:- Toxicity to First Instar 

Daphnia magna: Report Series RJ 0377B. Unpublished study prepared 

by ICI Plant Protection Div. 14 p. 

72-3 Acute Toxicity to Estuarine/Marine Organisms 

MRID Citation Reference 

40161135 Thompson, R. (1986) PP993: Determination of the Acute Toxicity to 

Larvae of the Pacific Oyster (Crassostrea gigas): Laboratory Project ID: 

BL/B/2855. Unpublished study prepared by ICI Brix- ham Laboratory. 17 

p. 

40161136 Thompson, R. (1986) Tefluthrin: Determination of Acute Toxicity to 

Mysid Shrimps (Mysidopsis bahia): Laboratory Project ID: BL/B/ 2967. 

Unpublished study prepared by ICI Brixham Laboratory. 17 p. 

40161137 Hill, R. (1986) Tefluthrin: Determination of Acute Toxicity to Sheepshead 

Minnow (Cyprinodon variegatus): Laboratory Project ID: BL/B/2916. 

Unpublished study prepared by ICI Brixham Labo- ratory. 15 p. 
-48 of 50-

72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study 

MRID Citation Reference 

40161138 Hamer, M.; Farrelly, E.; Hill, I. (1987) Tefluthrin: 21 Day Daphnia magna 

Life-cycle Study: Laboratory Project ID: RJ0530B. Unpub- lished study 

prepared by ICI Plant Protection Div., Jealott's Hill Research Station. 32 

p. 

41229501 Farrelly, E.; Hamer, M.; Hill, I. (1989) Tefluthrin: Daphnia magna Lifecycle Study Using 1 Flow-through System: Rept. No. RJ0769B. 

Unpublished study prepared by ICI Agrochemicals, Jealotts Hill 

Research Station. 26 p. 

72-5 Life cycle fish 

MRID Citation Reference 

41705101 Tapp, J; Maddock, B.; Gillings, E. (1990) Tefluthrin (Force ICIA099 3): 

Determination of Chronic Toxicity to Fathead Minnow (Pime- phales 

promelas) Full Lifecycle: Lab Project Number: S001/A (FT 83/88): 

BL3737/B. Unpublished study prepared by Imperial Chemi- cal 

Industries PLC. 266 p. 

41739800 ICI Agriculture Products (1990) Submission of Toxicity Data In 

Response to the EEB Review of the Lambda-cyhalothrin fish life- cycle 

Study. Transmittal of 1 Study. 
-49 of 50-

Appendix A Justification for Studies Requested 

Guideline Number: 835.4300 

Study Title: Aerobic Aquatic Metabolism 

Study Substance: tefluthrin

Rationale for Requiring the Data 

EPA has a limited understanding of how tefluthrin behaves in the environment once 

applied. Depending on how quickly and to what extent the compound degrades, 

tefluthrin may or may not contribute to antibiotic resistance in human pathogens. 

Because tefluthrin degradation in water in aerobic conditions is not well understood, EPA 

is requiring confirmatory data. 

Practical Utility of the Data 

How will the data be used? 

Aerobic aquatic metabolism data will facilitate a better understanding of tefluthrin under 

aqueous conditions. If data indicate that degradation occurs rapidly in water, then EPA 

could potentially determine that tefluthrin e, when exposed to aerobic water, would not 

likely contribute to antibiotic resistance in human pathogens. If data indicate that 

degradation occurs slowly, then EPA could not necessarily conclude that the risk of 

tefluthrin contributing to antibiotic resistance in human pathogens is negligible and 

further study and/or restrictions would be required. 

How could the data change the Agency’s decision, or impact the Agency’s future 

decision-making? 

If data indicate that tefluthrin degrades slowly in water in aerobic conditions, then 

antibiotic resistance may be a public health risk of concern and additional use precautions 

and/or restrictions may be necessary.

Study Title: Anaerobic Aquatic Metabolism 

Guideline Number: 835.4400 

Study Substance: tefluthrin

Rationale for Requiring the Data 

Acceptable data have not been provided to quantify the metabolism of tefluthrin under anaerobic aquatic 

conditions; supplemental data has been submitted. According to 40 CFR Part 158 Subpart N, July, 2009 (data 

requirements for pesticides) anaerobic aquatic metabolism in two water:sediment systems are required for pesticides 

with terrestrial or aquatic food and nonfood uses. Since tefluthrin uses are classified as terrestrial, anaerobic aquatic 

metabolism data for tefluthrin should be submitted to fulfill OCSPP Guideline 835.4400. 

Practical Utility of the Data 
-50 of 50-

How will the data be used? 

Currently there are no acceptable anaerobic aquatic metabolism studies that track the formation and decline of 

tefluthrin and its degradates. The submitted data will be used to characterize and quantify the environmental fate of 

tefluthrin and its degradates in aquatic environments. For quantitative exposure estimation, these data will be used to 

confirm the conceptual model of tefluthrin fate and transport in aquatic environments. 

How could the data impact the Agency’s future decision-making? 

Without these required data, the fate of tefluthrin cannot be fully characterized and exposure to potentially toxic 

degradates cannot be quantified. The persistence of asulam and its degradates to which terrestrial and aquatic 

organisms will be exposed to is uncertain. In the absence of acceptable data, conservative assumptions will be made 

regarding the potential for formation of tefluthrin degradates. Therefore, potential for risk to aquatic organisms 

may be overestimated and the use of tefluthrin 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 complying with the 

Endangered Species Act and could result in use restrictions for tefluthrin which are unnecessarily severe. 

Guideline Number: Non-guideline special study

Study Title: Aquatic Invertebrate Acute Toxicity (Hyalella) 

Rationale for Requiring the Data 

Available information indicates that the freshwater amphipod, Hyalella azteca, is 

substantially more sensitive to pyrethroids than Daphnia magna, the commonly tested 

freshwater invertebrate (e.g., Anderson et al. 2006; Maund et al., 2002). Information on 

the acute toxicity of tefluthrin 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 

tefluthrin. 

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 bifenthrin 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 bifenthrin which are unnecessarily severe.