Page 2 of 22 

there are two uses that could potentially result in environmental exposures: (1) 

distribution of composted material from greenhouses that use chlorfenapyr; and (2) 

application of chlorfenapyr to soil underlying a concrete slab prior to the slab being 

poured (during construction). All other uses occur indoors, underground (termiticide), or 

involve small quantities (crack and crevice treatment) and are not expected to result in 

significant ecological exposure because greenhouse/indoor and underground uses have 

limited opportunity for outdoor residues, drift, runoff, and wildlife exposure. 

The following is a discussion of the current use patterns and potential exposure pathways for 

currently registered uses of chlorfenapyr. 

Greenhouse Uses: The chlorfenapyr label (EPA Reg. No. 000241-00374) for fruiting 

vegetables grown in a greenhouse states, “Compost any discarded plant material that has 

been treated.” EFED concludes exposure is possible because the label does not preclude 

the distribution of chlorfenapyr treated compost material outside of the greenhouse. To 

assess this potential risk, additional data will be required (as specified in section 7) and a 

subsequent risk assessment will be performed. 

Construction: Chlorfenapyr may be applied to soil underlying a concrete slab prior to 

the slab being poured (during construction) (EPA 000241-00392). In the event that a 

major rain event occurs after treatment and prior to pouring of the concrete slab, there is a 

potential for exposure to chlorfenapyr in adjacent areas via runoff from the use site. 

EFED concludes that such exposure is possible because the label does not specify that the 

amount of time between application of chlorfenapyr and the pouring of the concrete slab 

be minimized. To assess this potential risk, additional data will be required (as specified 

in section 7) and a subsequent risk assessment will be performed. 

2. Current Chlorfenapyr Uses 

The currently registered crop/sites, use groups, and registration numbers for chlorfenapyr 

are listed in Table 1. These uses are taken from the LUIS report (dated: July 23, 2009) 

prepared by the Biological and Economic Analysis Division (BEAD) of the U.S. EPA 

Office of Pesticide Programs. 

Table 1. Complete List of Chlorfenapyr Uses by Registration Number.

Crop/Site Use Group Reg.No 

Commercial Storages/Warehouses Premises Indoor Non-Food 

000241-00392 

007969-00285 

MS02002300 

Commercial/Institutional/Industrial Premises/Equip. 

(Indoor) Indoor Non-Food 

000241-00392 

007969-00285 

MS02002300 

Dairies/Cheese Processing Plant Equipment (Food 

Contact) Indoor Food 

000241-00392 

007969-00285 

MS02002300 

Eating Establishments Indoor Food 

000241-00392 

007969-00285 

MS02002300 
Page 3 of 22 

Table 1. Complete List of Chlorfenapyr Uses by Registration Number.

Crop/Site Use Group Reg.No 

Egg Packing Plants (Commercial) Indoor Food 

000241-00392 

007969-00285 

MS02002300 

Eggplant Greenhouse Food Crop 000241-00374 

Feed Mills/Feed Processing Plants Indoor Food 

000241-00392 

007969-00285 

MS02002300 

Food Processing Plant Equipment (Food Contact) Indoor Food 000241-00392 

MS02002300 

Food Processing Plant Premises (Nonfood Contact) Indoor Food 007969-00285 

Food Stores/Markets/Supermarkets Premises Indoor Food 000241-00392 

MS02002300 

Food/Grocery/Marketing/Storage/Distribution Facility 

Premise Indoor Food 

000241-00392 

007969-00285 

MS02002300 

Fruiting Vegetables Greenhouse Food Crop 000241-00374 

Greenhouses-In Use Greenhouse Food Crop 000241-00374 

Groundcherry (Strawberry Tomato/Tomatillo) Greenhouse Food Crop 000241-00374 

Hospitals/Medical Institutions Premises 

(Human/Veterinary) Indoor Medical 

000241-00392 

007969-00285 

MS02002300 

Household/Domestic Dwellings Indoor Residential 

000241-00392 

007969-00285 

MS02002300 

Household/Domestic Dwellings Indoor Premises Indoor Residential 

000241-00392 

007969-00285 

MS02002300 

Household/Domestic Dwellings Outdoor Premises Outdoor Residential 

000241-00392 

007969-00285 

MS02002300 

Meat Processing Plant Premises (Nonfood Contact) Indoor Non-Food 

000241-00392 

007969-00285 

MS02002300 

Nonagricultural Outdoor Buildings/Structures Terrestrial Non-Food Crop* 000241-00392 

MS02002300 

Ornamental and/or Shade Trees Greenhouse Non-Food Crop 000241-00374 

Ornamental Herbaceous Plants Greenhouse Non-Food Crop 000241-00374 

Ornamental Non-flowering Plants Greenhouse Non-Food Crop 000241-00374 

Ornamental Woody Shrubs And Vines Greenhouse Non-Food Crop 000241-00374 

Pepino (Melon Pear) Greenhouse Food Crop 000241-00374 

Pepper Greenhouse Food Crop 000241-00374 

Pets (Unspecified) Indoor Non-Food 

000241-00392 

007969-00285 

MS02002300 

Poultry Processing Plant Premises (Nonfood Contact) Indoor Food 

000241-00392 

007969-00285 

MS02002300 

Sewage Systems Aquatic Non-Food Industrial 

000241-00392 

007969-00285 

MS02002300 

Tomatillo Greenhouse Food Crop 000241-00374 

Tomato Greenhouse Food Crop 000241-00374 
Page 4 of 22 

Table 1. Complete List of Chlorfenapyr Uses by Registration Number.

Crop/Site Use Group Reg.No 

Zoos Indoor Non-Food 

000241-00392 

007969-00285 

MS02002300 

* The Use Group designation, Terrestrial Non-Food Crop, is confusing because it refers to use on building 

and structures below concrete slabs, within the soil around foundations, and in and around cracks and 

crevices. It is probably meant to indicate “some terrestrial application that is not to a food crop.” However, 

a literal interpretation would be “application to some crop other than food.” 

The majority of these uses occurs in enclosed indoor environments; and therefore, is 

assumed by EFED to have no complete exposure pathways to ecological receptors and, 

therefore, pose no risk to these receptors. However, several of the uses in Table 1 merit 

further explanation because these use group names may appear to result in outdoor 

exposures to ecological receptors: 

• Household/Domestic Dwellings Outdoor Premises (Outdoor Residential) and 

Nonagricultural Outdoor Buildings/Structures (Terrestrial Non-Food Crop) – 

refers to uses that form a zone or barrier in the soil surrounding a building or 

structure (under concrete slab flooring and adjacent to basement walls) during 

construction and crack and crevice treatments that are used on existing buildings 

and structures. Pre-construction uses of chlorfenapyr result in the pesticide 

sequestered by soils under the floor of, or adjacent to the basement walls of, a 

building. Post-construction and crack and crevice treatments are limited to a 9.4 x 

10-5 lbs ai per 2 sq. feet every four weeks. Therefore, assuming 4 sides of a 

building are treated with sides 10’ high by 100’ long (4000 ft2) would result in a 

maximum treatment of 0.18 lbs ai to the building. However, EFED believes such 

applications would be unlikely to create a significant exposure pathway to 

ecological receptors because: most structurally sound buildings have far fewer 

cracks and crevices than the maximum application rate allows; much of the 

applied pesticide would be retained inside the crevice or crack; and much of the 

pesticide that was dislodged from its application site would be retained in any soil 

and/or landscaping at the base of the treated wall. 

• Sewage Systems (Aquatic Non-Food Industrial) – is a crack and crevice 

treatment that is used in cracks in the concrete slab flooring around floor drains. 

The intent is not to discharge the chemical to the sewer system but, rather, to 

prevent ground-dwelling insects from entering a building through cracks in the 

flooring around the drain. The label specifies that the drain must lead to a sewage 

system (and thus presumably, would be greatly diluted if some of the pesticide 

went down the drain) to prevent the use of the chemical around drains that may 

discharge to the outside of the building (where relatively little dilution might 

occur). 

• Zoos (Indoor Non-Food) – is also a crack and crevice use that is used on 

buildings enclosing zoo animals. 

3. Chlorfenapyr Persistence

Chlorfenapyr and its degradates have been shown to be highly persistent. Chlorfenapyr's 
Page 5 of 22 

persistence is typified by a laboratory aerobic soil metabolism half-life of 1.4 years and 

its observed comparable field dissipation "half-life" of 1.3 years (MRID 44452621, 

43492850). Chlorfenapyr is essentially stable to laboratory hydrolysis and anaerobic soil 

metabolism. Chlorfenapyr also has an organic carbon partition coefficient (Koc) of 11,500 

L/kg and thus binds to organic particulates and is generally immobile in soil. Sediment 

would be its principle latent reservoir in aquatic systems where it would remain available 

for extended periods. 

Because of the persistence of parent and relatively short study durations, only small 

amounts of structurally similar metabolites or degradates were identified in soil in field or 

lab studies. However, AC 312,094 has been detected at 10% to 16% of parent in the 

radiolabeled North Carolina study (MRID 44452623). This metabolite has intermediate 

mobility characteristics (median Koc around 2200). Coupled with its persistence, this 

means that it has high potential for runoff into surface water with comparable amounts in 

solution and eroding soil if chlorfenapyr is used in outdoor environments. 

In general, transformation products appear to approximate or exceed the persistence of 

the parent. Structurally similar metabolites or degradates (AC 312,094, AC 303,267, AC 

303,268, AC 322,118, AC 322,250, AC 325,195, some of which exhibit ecotoxicity) 

were identified in soil in field or lab studies. Concentrations of these, when detected 

were typically a few percent each or less of the applied chlorfenapyr. 

4. Chlorfenapyr Toxicity 

Available toxicity data are summarized below and are further discussed in Appendix A. 

These data were obtained from previous assessments (EFED 1998, DP Barcode: 241963). 

In general, chlorfenapyr has demonstrated high acute toxicity to terrestrial and aquatic 

organisms, and has demonstrated chronic toxicity at concentrations in the low μg/L 

range. 

Chlorfenapyr is very highly toxic to birds on an acute basis. The LD50 values for redwinged blackbird (Agelaius phoneiceus), mallard (Anas platyrhynchus), and bobwhite 

quail (Colinus virginianus) are 2.2, 8.3, and 34 mg/kg, respectively (MRIDs 43887004, 

42770227, and 42770228). It is also very highly toxic to waterfowl and passerine species 

and highly toxic to upland gamebirds on an acute dietary basis (MRID 42770229, 

42770230, and 44452613). Chlorfenapyr has also resulted in reproductive and growth 

effects to birds at low concentrations of 1.5 mg/kg-diet. The mallard duck NOAEC value 

of 0.5 mg/kg-diet, which is based on reduced body weight, serves as the chronic toxicity 

endpoint for avian long-term exposure risk calculations (MRID 434928-13). 

Chlrofenapyr has been shown to be less toxic to mammals compared with birds. Acute 

LD50 values in mammals range from approximately 45 mg/kg-bw to 1152 mg/kg-bw 

(MRIDs 43492828, 42770201, 42770207). A 2-generation mammalian study (MRID 

43492836) produced a NOAEC value of 60 mg/kg-diet (5 mg/kg-bw). 

Chlorfenapyr is highly toxic to honey bees (Apis mellifera) on an acute contact exposure 

basis with a corresponding LD50 value of 0.12 μg/bee. 
Page 6 of 22 

In aquatic organisms, acute LC50 values for chlorfenapyr range from 7 μg/L to 12 μg/L in 

freshwater fish (MRIDs 42770231 and 42807801), 60 μg/L in saltwater fish (MRID 

43492816), 6 μg/L to 18 μg/L in freshwater invertebrates (MRIDs 42770232, 43887009), 

2 μg/L in saltwater invertebrates (MRID 43492818), and 0.2 mg/kg to 20 mg/kg sediment 

in benthic organisms (MRIDs 44452619, 44560002). Therefore, on an acute exposure 

basis, chlorfenapyr is very highly toxic to freshwater and estuarine/marine fish and 

invertebrates. Also, a degradate (CL 357,806) has shown to be more toxic than the parent 

chemical. However, the study on which this conclusion is based is invalid. 

Chronic NOAEC values range from 0.2 μg/L in estuarine/marine inverterbrates (MRID 

43492821) to 4 μg/L (freshwater fish and invertebrates; MRIDs 43492819 and 

43492822). Additional information from the 1998 EFED assessment is presented in 

Appendix A. 

5. Composting Concerns 

There is a concern for potential environmental exposure through composting and land 

application of treated material after composting. The chlorfenapyr label (EPA Reg. No. 

000241-00374) for fruiting vegetables grown in a greenhouse states “Compost any 

discarded plant material that has been treated.” Given chlorfenapyr’s persistence in 

aerobic soils and very high toxicity to avian species, there is a concern that outdoor 

composting of treated plant material may provide a potential route of exposure for avian 

species as well as other ecological receptors (Figure 1). 
Page 7 of 22 

Figure 1. Potential exposure pathways from chlorfenapyr-treated compost. 

Persistence in compost is a concern because the degradation of chlorfenapyr is likely to 

be slower than the degradation of the plant material. Therefore, the potential exists for 

chlorfenapyr residues to increase in compost over time. Soils enriched with chlorfenapyrtreated compost may also have the potential to result in exposure to birds, mammals, and 

honey bees or other pollinators possibly resulting in impaired survival, reproduction, 

and/or growth. 

6. Treatment Prior to Pouring Concrete Slabs 

Based on EFED’s review of the label for use of chlorfenapyr as a termiticide, 

chlorfenapyr may be applied to soil underlying a concrete slab prior to the slab being 

poured (during construction). In the event that a major rain event occurs after treatment 

and prior to pouring of the concrete slab, there is a potential for exposure to chlorfenapyr 

in adjacent areas via runoff from the use site. 

7. Data Requirements 

Justification for additional data needed to perform an ecological risk assessment for 

chlorfenapyr is presented below. EFED is currently requesting a composting study as 

part of this problem formulation. The study protocol must be submitted and reviewed by 

the Agency prior to conducting this study. 

Chlorfenapyr applied to plants 

grown in greenhouse. 

Edible portion harvested from 

plants (Health Effects Division 

assessment). 

Treated plant material discarded 

into outdoor compost pile 

Compost material possibly 

degrading more rapidly than 

persistent parent and degradates 

resulting in higher concentrations in 

compost. 

Birds and other animals exposed to, 

or feed on, discarded plant 

material/compost and organisms 

exposed to chlorfenapyr. 

Chlorfenapyr contaminated 

compost spread in field or yard. 

Run-off to water bodies exposes 

aquatic receptors. 

Plants and animals exposed to 

compost contaminated soils. 
Page 8 of 22 

Also, 40 CFR Part 158 criteria requires chronic sediment data if the aerobic soil or 

aquatic metabolism half-life > 10 days and any one of the following conditions exist: 1) 

Kd > 50; 2) log Kow > 3; or 3) Koc > 1000. Chlorfenapyr meets these criteria. In 

addition, several studies were identified previously as data gaps in the RED (DP 241963). 

These studies remain data gaps. 

Study Title: Evaluation of Chlorfenapyr Degradation in Compost 

Non-Guideline 

Rationale for Requiring the Data 

The current labels recommend composting plant materials treated with chlorfenapyr. The composted 

material may then be distributed into the environment outside of the greenhouse environment resulting in 

potential exposures to non-target organisms. Therefore, understanding the fate of chlorfenapyr in 

compost is necessary to allow for an assessment of potential exposures to non-target organisms resulting 

from distribution of the compost material. 

Practical Utility of the Data 

How will the data be used? 

The data would be used to derive exposure concentrations to be used in the risk assessment for terrestrial 

and aquatic organisms and to evaluate the time needed to result in sufficient degradation of chlorfenapyr 

such that the concern for potential effects is mitigated. 

How could the data change the Agency’s decision or impact the Agency’s future decision-making? 

These data would serve as the basis for risk assessments resulting from distribution of composted 

material outside of the greenhouse. If future endangered species risk assessments are performed without 

these data, the Agency would have to assume that chlorfenapyr “may affect” listed species and use of 

chlorfenapyr may need to be restricted in areas where listed species could be exposed. The lack of these 

data will limit the flexibility the Agency and registrants have in coming into compliance with the 

Endangered Species Act and could result in use restrictions for chlorfenapyr which are unnecessary. 

Guideline Number: 850.4100, 4150, 4400, 5400 

Study Title: Aquatic and Terrestrial Plant Toxicity 

Rationale for Requiring the Data 

Data regarding the toxicity of chlorfenapyr to aquatic and terrestrial plants have not been submitted to 

the Agency. These data are required under the 40 CFR Part 158 (2008) data requirements for pesticides 

with outdoor uses. These data are necessary to determine whether the outdoor use of chlorfenapyr could 

adversely affect aquatic and terrestrial plants. 

Practical Utility of the Data 

How will the data be used? 

These data will be used to determine the potential for chlorfenapyr to affect non-target plant species in 

the aquatic and terrestrial environments. In the absence of data specific for these plants, risk to 

terrestrial and aquatic plants will be assumed. Because plants are primary producers, providing the 

foundation of food sources for all animal species and habitat for most, the lack of these data would result 

in the Agency presuming indirect affects to all species. 

How could the data impact the Agency’s future decision-making? 

If endangered species risk assessments are performed without these data, the Agency would have to 

presume direct risk to non-target plants and indirect risk to all animal species from use of chlorfenapyr. 

Therefore, use of chlorfenapyr and its formulated products may need to be restricted in areas where 

listed species could be exposed. The lack of these data will limit the flexibility the Agency and 

registrants have in coming into compliance with the Endangered Species Act and could result in use 

restrictions for chlorfenapyr that are unnecessarily severe. 
Page 9 of 22 

Guideline Numbers: 850.1735 & 850.1740; EPA 600/R-99/064 Method 100.5 

Study Title: Whole sediment: Freshwater and Marine Invertebrates 

Rationale for Requiring the Data 

No sediment toxicity tests for freshwater or marine invertebrates have been submitted to satisfy the 

Agency’s updated data requirements for outdoor uses in 40 CFR Part 158 (October 26, 2007). 

o Benthic organisms inhabit sediment environments that may be exposed to run-off or spray drift from 

chlorfenapyr applications used in agricultural, forest, and residential settings 

o Previous studies have identified a potential adverse effect for freshwater and estuarine/marine 

aquatic organisms based on water column toxicity values. Therefore, there is uncertainty associated 

with that estimate that can be reduced using data from a toxicity test with benthic organisms. 

o There is the potential for persistent exposure from chlorfenapyr in sediment indicated by the fate 

properties. 

Practical Utility of the Data 

How will the data be used? 

Data from sediment toxicity studies will be used to estimate potential risks to benthic organisms 

associated with uses of chlorfenapyr. The data will reduce uncertainties associated with the current risk 

assessment for benthic species and will improve our understanding of the potential effects of 

chlorfenapyr. 

How could the data impact the Agency’s future decision-making? 

Acceptable data for benthic organisms will reduce the uncertainty from the previous assessment. If the 

data indicates that registered chlorfenapyr usage may pose a risk of adverse effects to non-target benthic 

organisms above the Agency Level of Concern, the Agency may explore decision options to mitigate 

this risk. The lack of these data will limit the flexibility the Agency and registrants have in coming into 

compliance with the Endangered Species Act, and could result in use restrictions for chlorfenapyr which 

may otherwise be avoided, or which are unnecessarily severe. 

In addition to the new data requirements presented above, several data requirements 

listed in the RED (1998; DP241963) have not yet been fulfilled, and remain data gaps. 

These studies are listed below. 

Guideline Number: 850.1075 

Test Substance: Photolysis degradate CL 357,806) 

Study Title: Fish Acute LC50 (Rainbow Trout) 

Rationale for Requiring the Data 

This degradate has been shown to be more toxic than chlorfenapyr to fish. However, the studies on 

which this conclusion was based are invalid. An acceptable study is needed to allow for an evaluation of 

the potential risks to fish from exposure to this degradate.

Practical Utility of the Data

How will the data be used? 

These data would allow for a quantitative assessment of potential risk to freshwater fish, providing a 

basis for viable mitigation options to reduce potential exposure and effects (if needed). 

How could the data impact the Agency’s future decision-making? 

If future endangered species risk assessments are performed without these data, the Agency would 

assume that this degradate "may affect" endangered fish directly (and endangered species from other 

taxa which feed on them indirectly), and use of chlorfenapyr might need to be restricted in areas where 
Page 10 of 22 

endangered species could be exposed. The lack of these data will limit the flexibility the Agency and 

registrants have in coming into compliance with the Endangered Species Act and could result in use 

restrictions that are unnecessary or unnecessarily severe.

Guideline Number: 850.1025 

Study Title: Estuarine/Marine Acute Invertebrate LC50 (Eastern Oyster) 

Rationale for Requiring the Data 

Chlorfenapyr is classified as very highly toxic to mysid shrimp. Therefore it is likely that there will be 

some toxicity to mollusks as well. The submitted study in Eastern oysters (MRID 43492817) was 

invalid. Therefore, no reliable data exists to allow for an evaluation of potential risks to mollusks. 

Since the RED was signed, the Agency has worked to finalize its update to data requirements in 40 CFR 

part 158, which were promulgated on October 26, 2007. Now estuarine/marine invertebrate acute 

toxicity studies are required using the TGAI for all outdoor end-use product uses. Chlorfenapyr end use 

products are currently assumed to be registered for outdoor uses. 

Practical Utility of the Data 

How will the data be used? 

These data would allow for a quantitative assessment of potential risk to estuarine/marine invertebrates, 

providing a basis for viable mitigation options to reduce potential exposure and effects to these taxa. 

How could the data impact the Agency’s future decision-making? 

If future endangered species risk assessments are performed without these data, the Agency would have 

to assume that chlolrenapyr “may affect” endangered mollusks directly (and endangered species from 

other taxa which feed on them), and use of chlofenapyr might need to be restricted in areas where 

endangered species could be exposed. The lack of these data will limit the flexibility the Agency and 

registrants have in coming into compliance with the Endangered Species Act and could result in use 

restrictions that are unnecessary or unnecessarily severe.

Guideline Number: 850.1400 

Study Title: Fish Early-life Stage Toxicity Test 

Rationale for Requiring the Data 

The fish early-life stage toxicity test provides the lethal and sublethal effects of the test compound on 

early life stages of fish species. These data are required for all outdoor uses, and some current uses of 

chlorfenapyr are considered outdoor uses, and the available environmental fate data suggests that 

chlofenapyr is persistent in the environment. No valid early life stage studies are available. Without 

these data, the Agency is unable to evaluate the potential risks to freshwater fish and aquatic-phase 

amphibians (for which fish serve as surrogates) to early life stages of fish. 

Practical Utility of the Data 

How will the data be used? 

The data from the fish early life stage test will be used to estimate the chronic risks to freshwater fish 

and amphibians associated with chronic exposures to chlorfenapyr. 

How could the data impact the Agency’s future decision-making? 

The data from the fish early life stage test will be used to estimate potential risks to freshwater 

fish/amphibians associated with chronic exposures to chlorfenapyr. The data will reduce uncertainties 

associated with potential risks to freshwater fish/amphibians thereby facilitating sound environmental 

management of natural resources, particularly, freshwater fisheries. 
Page 11 of 22 

Lastly, this data will allow the Agency to assess the chronic risk to freshwater fish, and should result in 

decisions that are protective of these organisms, including endangered species. 

Guideline Number: 830.6100 

Data requirement: Analytical method 

Rationale for Requiring the Data 

The registrant is required to submit soil and water methods of analysis that are suitable for detecting 

about one-tenth of the concentrations with observed ecological effects for EPA laboratory validation. 

Using this criterion, present procedures for water need to be improved by a factor of ten for sensitive 

species. Validation data for both accuracy and precision should be submitted for all methods. 

Practical Utility of the Data 

This is basic information to characterize and identify the compound and is used to ensure that the 

chemical can be detected at concentrations that may cause adverse effects in the environment. This 

information is usually provided when a product is registered, but the existing data are inadequate. 

References 

USEPA. August 31, 1998. Chlorfenapyr (PIRATETM, ALERTTM, AC 303,630) 

Insecticide-Miticide Environmental Fate and Ecological Effects Assessment and 

Characterization for a Section 3 for Use on Cotton. DP Barcode: D241963, D240108, 

D243556, D245813, D246459, D246093, D246661. 140pp. 
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Appendix A. Guideline Toxicity Data as Presented in Previous Assessments (DP 

241963)
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