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 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

 

Date: 06/18/2014 

 

Subject: Chlorfenapyr. Revised Occupational and Residential Exposure Registration 

Review Assessment 

PC Code: 129093 DP Barcode: D417598 

Decision No.: 485596 Registration No.: NA 

Petition No.: NA Regulatory Action: Reg Review 

Risk Assessment Type: Occupational/Residential Exposure Assessment Case No.: NA 

TXR No.: NA CAS No.: 122453-73-0 

MRID No.: NA 40 CFR: §180.513 

FROM: Lata Venkateshwara, Environmental Scientist 

 Health Effects Division (HED)/Risk Assessment Branch (RAB) 1 (7509P) 

THRU: Bridgett Boboweic, ExpoSAC Designated Reviewer 

 Alexandra LaMay, ExpoSAC Designated Reviewer 

 Exposure Science Advisory Council (ExpoSAC) 

Kelly Lowe, Environmental Scientist 

 Charles Smith III, Branch Chief 

HED/RAB 1 (7509P) 

 

TO: Margaret Hathaway 

 Kevin Costello, Branch Chief

 Pesticide Re-evaluation Division (PRD; 7508P) 

 

The HED of the Office of Pesticide Programs (OPP) is charged with estimating the risk to human 

health from exposure to pesticides. As part of Registration Review, the Pesticide Re-evaluation 

Division (PRD) of OPP has requested that HED evaluate the hazard and exposure data and 

conduct occupational and residential exposure assessments, as needed, to estimate the risk to 

human health that will result from the currently registered uses of pesticides. This memorandum 

serves as HED’s Registration Review risk assessment of the occupational and residential handler 

and post-application exposure and risk from the current registered uses of chlorfenapyr. 

 

It is HED policy to use the best available data to assess exposure. Several sources of generic 

data were used in this assessment as surrogate data in the absence of chemical-specific data, 

including: Pesticide Handlers Exposure Database Version 1.1 (PHED 1.1); the Agricultural 

Handler Exposure Task Force (AHETF) database; the Outdoor Residential Exposure Task Force 
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(ORETF) database; and the Agricultural Reentry Task Force (ARTF) database. Some of these 

data are proprietary, and subject to the data protection provisions of the Federal Insecticide, 

Fungicide, and Rodenticide Act (FIFRA). 

Note: This memorandum was reviewed by the Exposure Science Advisory Committee 

(ExpoSAC) on March 27, 2014 
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Table of Contents 

1.0 Executive Summary ............................................................................................................. 4 

2.0 Risk Assessment Conclusions and Recommendations ........................................................ 5

2.1 Label Recommendations from Occupational/Residential Assessment ............................. 6

2.2 Data Deficiencies and Requirements ................................................................................. 7

3.0 Hazard Characterization ....................................................................................................... 7

4.0 Use Profile ........................................................................................................................... 8

5.0 Residential Exposure and Risk Estimates .......................................................................... 12

5.1 Residential Handler Exposure/Risk Estimates ................................................................ 12

5.2 Residential Post-application Exposure/Risk Estimates ................................................... 12

5.2.1 Post-application Inhalation Exposure and Risk Estimates........................................ 13

5.2.2 Post-application Dermal Exposure and Risk Estimates ............................................ 14

5.2.3 Post-application Incidental Oral Exposure and Risk Estimates ................................ 16

5.2.4 Combined Residential Risk Estimates from the Indoor Surfaces and Bed Bug 

Mattress Use.......................................................................................................................... 19

5.3 Residential Risk Estimates for Use in Aggregate Assessment .................................... 20

5.4 Spray Drift ....................................................................................................................... 20

6.0 Occupational Exposure and Risk Estimates ...................................................................... 21

6.1 Occupational Handler Exposure/Risk Estimates ............................................................. 21

6.2 Occupational Post-application Exposure ......................................................................... 27

6.2.1 Occupational Post-application Inhalation Exposure/Risk Estimates ........................ 27

6.2.2 Occupational Post-application Dermal Exposure/Risk Estimates ............................ 28

Appendix A: Summary of Occupational and Residential Algorithms ......................................... 32

Appendix B. Registered Chlorfenapyr End Use Products ........................................................... 42
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Executive Summary 

The Health Effects Division has conducted an occupational and residential exposure assessment 

for Registration Review of the active ingredient (ai) chlorfenapyr. Chlorfenapyr is an 

insecticide/miticide. The parent compound is converted to the N-dealkylated metabolite in the 

organism. The pesticidal mode of action of this active form functions as an uncoupler of 

oxidative phosphorylation in mitochondria, which disrupts ATP production leading to cell 

dysfunction and subsequent death of the organism. Chlorfenapyr is registered for use on 

greenhouse food and non-food crops, and as an insecticide/termiticide for use on indoor and 

outdoor residential sites, food/feed handling areas, indoor and outdoor commercial sites 

(including sewers), and indoor medical sites. It is currently formulated into soluble concentrate 

(SC), emulsifiable concentrate (EC) and pressurized release liquid end-use products (e.g., total 

release foggers and aerosol cans) containing between 0.05% to 21.45% ai. This memorandum 

contains HED’s occupational and residential exposures and risk estimates to pesticide handlers 

(i.e., mixers, loaders, applicators) and to agricultural workers and residents conducting postapplication activities. 

For short-term (ST) and intermediate-term (IT) dermal exposure, ST and IT inhalation exposure, 

and ST incidental oral exposure for the occupational and residential assessment, a no observable 

adverse effect level (NOAEL) of 5 mg/kg/day was selected from a developmental neurotoxicity 

study. The LOAEL of 10 mg/kg/day is based on increased pup deaths (post-natal days 1-4) and 

decreased motor activity. Chlorfenapyr is classified as “suggestive evidence of carcinogenicity, 

but not sufficient to assess human carcinogenic potential”. A cancer risk assessment is not 

required. A dermal penetration study (MRID 49315901) has been submitted since the most 

recent risk assessment. The dermal absorption was found to be 13% and should be applied for 

converting oral doses to dermal equivalent doses to assess the potential risk associated with 

dermal exposures for chlorfenapyr. Since no inhalation absorption data are available, toxicity by 

the inhalation route is considered to be equivalent to the estimated toxicity by the oral route of 

exposure. A body weight of 69 kg was used in the assessment since the effects were 

developmental and/or fetal effects. The total uncertainty factor (UF) that was applied to 

occupational and residential risk assessments is 100 for short- and intermediate-term risk 

estimates. Since the dermal and inhalation routes of exposure are assessed using the same 

endpoint/point of departure (POD), the exposures from these routes were combined to estimate a 

total (dermal + inhalation) risk estimate. 

An assessment of occupational handler exposure from the use of total release foggers is not 

performed because dermal and inhalation exposure is expected to be negligible based on the use 

pattern for this method of application. Occupational handler exposure from the other 

uses/application methods was assessed. Most occupational handler inhalation risk estimates 

resulted in margins of exposure (MOEs) greater than the level of concern (LOC = MOE ≥100) at 

baseline or label specified personal protective equipment (PPE), and therefore, are not of 

concern. However, there were several exposure scenarios that required additional PPE (some 

beyond what is currently on the registered labels) to reach MOEs greater than the LOC. For 

mixers/loaders/applicators of liquids using a mechanically-pressurized handgun for greenhouse 

applications, there are risks of concern (MOEs < 100) even with maximum PPE (i.e., double 

layer, gloves and PF10 respirator). 
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An occupational post-application assessment was conducted for workers entering greenhouses 

after treatment of crops and/or ornamentals to perform various activities. Risk estimates for all 

activities were not of concern (MOEs ≥ 100). The restricted entry interval (REI) of 12 hours is 

adequate based on the acute toxicity of the active ingredient. Under 40 CFR 156.208 (c) (2) (iii), 

a.i.’s classified as Acute III or IV for acute dermal, eye irritation and primary skin irrigation are 

assigned a 12-hour REI. Only two labels specify a REI. These are Pylon® TR (Total Release 

miticide/insecticide) (TC-307) and Pylon® (241-374). 

Based on the Agency's current practices, a quantitative non-cancer occupational post-application 

inhalation exposure assessment was not performed for chlorfenapyr at this time. If new policies 

or procedures are put into place, the Agency may revisit the need for a quantitative occupational 

post-application inhalation exposure assessment for chlorfenapyr. 

Chlorfenapyr is registered for residential pest control and can be applied as a termiticide and/or a 

crack and crevice/spot spray to indoor surfaces to control various pests. There are currently no 

registered residential uses that permit residential handlers – all labels indicate that products are 

“for sale to, use and storage only by individuals/firms licensed or registered by the state to apply 

termiticide and/or general pest control products.” Therefore, quantitative residential handler 

assessments were not conducted. The residential post-application exposure assessment yielded 

margins of exposure (MOEs) that are not of concern to HED (MOEs ≥ 100) for all scenarios 

except the combined (incidental oral, dermal, and inhalation) MOE for children (1 to <2 years 

old) with coarse-stream applications. However, use of equipment with a pin stream nozzle 

results in a combined MOE for children (1 to <2 years old) that is above the level of concern 

(LOC). 

Human Studies Review 

This risk assessment relies in part on data from studies in which adult human subjects were 

intentionally exposed to a pesticide or other chemical. These data, which include studies from 

PHED 1.1; the AHETF database; the Outdoor Residential Exposure Task Force (ORETF) 

database; the ARTF database; the Residential SOP (Indoor Environments) are (1) subject to 

ethics review pursuant to 40 CFR 26, (2) have received that review, and (3) are compliant with 

applicable ethics requirements. For certain studies, the ethics review may have included review 

by the Human Studies Review Board. Descriptions of data sources, as well as guidance on their 

use, can be found at the Agency website1

. 

2.0 Risk Assessment Conclusions and Recommendations 

 Most occupational handler inhalation risk estimates resulted in MOEs greater than the 

level of concern (LOC = MOE ≥100) at baseline or with additional PPE, and therefore, 

are not of concern. The following is a summary of the occupational handler combined 

 

1 http://www.epa.gov/pesticides/science/handler-exposure-data.html and 

http://www.epa.gov/pesticides/science/post-app-exposure-data.html
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risk estimates: 

o For mixers/loaders/applicators (MLAs) of liquids using an injector for termiticide 

applications, combined MOEs were above the LOC of 100 at baseline (single 

layer of clothing, no gloves, no respirator). 

o For MLAs of liquids using a backpack or manually-pressurized handwand for 

applications to greenhouse ornamentals, combined MOEs were above the LOC of 

100 at baseline. 

o For applicators using ready-to-use aerosol cans, combined MOEs were above the 

LOC of 100 with a single layer of clothing, no respirator and gloves. 

o For MLAs of liquid using a manually-pressurized handwand for application to 

greenhouse vegetables, combined MOEs were above the LOC of 100 with a 

single layer of clothing, no respirator and gloves. 

o For MLAs of liquids using a manually-pressurized handwand for applications to 

indoor environments such as food handling establishments, warehouses, and 

residential living spaces, combined MOEs were above the LOC of 100 with a 

single layer of clothing, gloves and a PF5 respirator. 

o For mixers/loaders/applicators of liquids using a mechanically-pressurized 

handgun for termiticide applications to structures, combined MOEs were above 

the LOC of 100 with a single layer of clothing, gloves and a PF5 respirator. 

o For mixers/loaders/applicators of liquids using a mechanically-pressurized 

handgun for greenhouse applications, combined MOEs did not reach the LOC of 

100 even with maximum PPE (i.e., double layer, gloves and PF10 respirator). 

 The short-and intermediate-term occupational post application scenarios resulted in 

MOEs greater than the LOCs of 100 on day 0 (12 hours after application) ranging from 

150 to 300 and therefore, are not of concern to HED. 

 All residential post-application scenarios results in risk estimates that were greater than 

the LOC, except for the combined MOE for children 1 to <2 years old from dermal and 

incidental oral exposure to treated indoor surfaces and mattresses from a coarse perimeter 

or spot treatment (MOE = 69). If the application method is restricted to equipment with a 

pin stream nozzle, the MOEs are greater than the LOC and not of concern. 

2.1 Label Recommendations from Occupational/Residential Assessment 

 For several occupational scenarios, HED recommends that additional PPE be placed on 

the Phantom® label (EPA Reg. No. 241-392) to reach the LOC of 100 (see Section 9.1). 

 For mixers/loaders/applicators of liquids using a mechanically-pressurized handgun for 

greenhouse applications, there are risks of concern (MOEs = 15-26) even with maximum 

PPE (i.e., double layer, gloves and PF10 respirator). 

 Based on the combined residential estimates for indoor perimeter/spot/bed bug and 

mattress applications, as well as aggregate risk incorporating these estimates, there are 

risks of concern with coarse-stream applications for children (1 to <2 years old). 

Therefore, HED recommends the Phantom® labels (EPA Reg. No. 241-392) should 

prohibit the use of coarse-stream equipment and only allow for the use of equipment with 

a pin-stream nozzle. 
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2.2 Data Deficiencies and Requirements 

Dislodgeable Foliar Residue (DFR): In accordance with 40 CFR Part 158, dislodgeable foliar 

residue (DFR) data are required for all occupational or residential uses that could result in postapplication exposure to foliage. As part of the recent revision to the Health Effects Division’s 

2012 Standard Operating Procedures for Residential Pesticide Exposure Assessment, HED 

analyzed a number of DFR studies and selected a new default value for the fraction of the 

application rate available to be dislodged after a foliar application (FAR). This default value is 

25% and is based on an analysis of 19 DFR studies where the FAR value ranged from 2% to 47%. 

This value is recommended for use in both residential and occupational post-application 

assessments. Of the analyzed DFR studies, the maximum FAR value seen was 47% or 

approximately two times higher than the default residue transfer value. Therefore, the HED has 

decided that a calculated margin of exposure (MOE) of approximately two times higher than the 

LOC (e.g., an MOE ≥ 200 if the LOC = 100) using the default dislodged residue values would 

provide an adequate margin of safety for any potentially higher residues seen in a chemicalspecific DFR study. A DFR study is required for chlorfenapyr at this time since the dermal 

MOEs are less than two times the LOC (i.e., < 200) based on default values for the fraction 

of application rate available for transfer after a foliar application. 

3.0 Hazard Characterization 

Chlorfenapyr is classified as having moderate acute toxicity via the oral route (Toxicity Category 

II) and low acute toxicity via the dermal and inhalation routes of exposure (Toxicity Category 

III). It is a mild eye irritant, but it is not a dermal irritant or sensitizer. Table 3.1 presents a 

summary of the acute toxicity information for chlorfenapyr. 

Table 3.1. Acute Toxicity Profile – Chlorfenapyr.

Guideline 

No. Study Type MRID(s) Results Toxicity Category 

870.1100 Acute oral (rat) 42770207 

42884201 

441 mg/kg, males 

1152 mg/kg, females 

626 mg/kg, combined 

II* 

870.1200 Acute dermal (rabbit) 42770208 >2000 mg/kg III 

870.1300 Acute inhalation (rat) 42770209 

0.83 mg/L, males 

>2.7 mg/L, females 

1.9 mg/L, combined 

III 

870.2400 Acute eye irritation (rabbit) 42770210 

Corneal opacity, iritis, 

and conjunctivitis 

present at 48 hours. All 

rabbits normal by Day 7. 

III 

870.2500 Acute dermal irritation (rabbit) 42770211 Non-irritating IV 

870.2600 Skin sensitization (guinea pig) 42770212 Non-sensitizer Not applicable 

*Based on most sensitive sex 

A summary of the toxicological PODs and doses chosen for the relevant exposure scenarios for 

human risk assessment are found in Table 3.2. A cancer assessment is not required. 
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Table 3.2. Summary of Toxicological Doses and Endpoints for Chlorfenapyr for Use in Human-Health Risk 

Assessments. 

Exposure/ 

Scenario POD 

Uncertainty/ 

FQPA Safety 

Factors 

RfD, PAD, LOC 

for Risk 

Assessment 

Study and Toxicological Effects

Incidental Oral 

Short-Term 

(1-30 days) and 

IntermediateTerm 

(1-6 months) 

NOAEL = 

5 mg/kg/day 

UFA = 10X 

UFH = 10X 

FQPA SF = 1X 

Residential LOC 

for MOE = 100 

Developmental Neurotoxicity Study 

LOAEL = 10 mg/kg/day based on 

increased pup deaths (post-natal days 

1-4) and decreased motor activity 

Dermal ShortTerm 

(1-30 days) and 

IntermediateTerm 

(1-6 months) 

NOAEL = 

5 mg/kg/day 

Dermal absorption 

factor = 13% 

UFA = 10X 

UFH = 10X 

FQPA SF = 1X 

Occupational and 

Residential LOC 

for MOE = 100 

Developmental Neurotoxicity Study 

LOAEL = 10 mg/kg/day based on 

increased pup deaths (post-natal days 

1-4) and decreased motor activity 

Inhalation ShortTerm 

(1-30 days) and 

Intermediateterm 

(1-6 months) 

NOAEL = 

5 mg/kg/day 

Inhalation 

absorption assumed 

equivalent to oral 

absorption. 

UFA = 10X 

UFH = 10X 

FQPA SF = 1X 

Occupational and 

Residential LOC 

for MOE = 100 

Developmental Neurotoxicity Study 

LOAEL = 10 mg/kg/day based on 

increased pup deaths (post-natal days 

1-4) and decreased motor activity 

Cancer (oral, 

dermal, 

inhalation) 

Classified as “Suggestive Evidence of Carcinogenicity, but Not Sufficient to Assess Human 

Carcinogenic Potential”. A cancer risk assessment is not required. 

Point of departure (POD) = A data point or an estimated point that is derived from observed dose-response data and used to mark the beginning 

of extrapolation to determine risk associated with lower environmentally relevant human exposures. NOAEL = no-observed adverse-effect 

level. LOAEL = lowest-observed adverse-effect level. UF = uncertainty factor. UFA = extrapolation from animal to human (interspecies). UFH

= potential variation in sensitivity among members of the human population (intraspecies). FQPA SF = FQPA Safety Factor. PAD = populationadjusted dose (a = acute, c = chronic). RfD = reference dose. MOE = margin of exposure. LOC = level of concern. 

Absorption 

A dermal penetration study (MRID 49315901) has been submitted since the most recent risk 

assessment. The dermal absorption was found to be 13% and should be applied for converting 

oral doses to dermal equivalent doses to assess the potential risk associated with dermal 

exposures for chlorfenapyr. Inhalation exposure is assumed to be equivalent to oral exposure. 

Body Weight 

A body weight of 69 kg was used in the assessment since the effects were developmental and/or 

fetal effects. 

4.0 Use Profile 

Chlorfenapyr is registered for use on greenhouse food and non-food crops, and as an 

insecticide/miticide for use on indoor and outdoor residential sites, food/feed handling areas, 

indoor and outdoor commercial sites (including sewers), and indoor medical sites. A summary 

of occupational uses is presented in Table 4.1. The pre-harvest interval (PHI) and maximum 

seasonal application rates are not specified on most of the labels.
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Table 4.1. Existing Use Patterns/ Exposure Scenarios for Chlorfenapyr.

Registration Number and 

Product Name Formulationa Application Equipment Maximum Application Rates Max. No. Applications Per Season Use Directions and Limit

Greenhouse ornamentals including Bedding Plants, Cut Flowers, Evergreens, Flowering plants, Foliage Plants, Fruiting Vegetables, Containeri

Non-Bearing Nut Trees, Non-Bearing Vines, Ornamental Trees and Shrubs 

499-544 

TC-307 Pylon® TR (Total 

Release miticide/ 

insecticide)b 

PRL Total release fogger 0.011 lb ai/3000 ft2 (0.163 lb ai/A) 3 

Do not make more than 2 con

applications. 

Not for indoor, residential use (e

apartments, mobile hom

Re-treatment for fruiting vegeta

days. 

Greenhouse (roses, cut flowers, container stock) 

241-374 

Pylon® SCb

Backpack 

Manuallypressurized 

handwand 

Mechanicallypressurized 

handgun 

0.0016 lb ai/gal 3 

Wait at least 5 to 7 days betw

application. 

Do not apply this product through 

irrigation system. 

Greenhouse (vegetable, fruiting, group 8-10d) 

241-374 

Pylon® SCb

Backpack 

Manuallypressurized 

handwand 

 Mechanicallypressurized 

handgun 

0.20 lb ai/A 

0.04 lb ai/gal 

3 

This product can be applied u

including the day of harv

Wait at least 5 to 7 days betw

application. 

Do not apply this product through 

irrigation system. 

Do not apply this product as an 

volume spray. 

Do not use on tomato varieties wi

of less than one inch when m
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Residential and Nonagricultural Uses 

Commercial and Food Use Site c and Household/domestic dwellings (indoor and outdoor) 

7969-285 

Prescription Treatment®

brand Phantom®

(General Pest-Control 

including bed bugs) 

PRL 17.5 oz Aerosol 

can 

0.5% ai = 

0.005 lb ai/can Not specified 

Spot and/or crack and crevice ap

For sale to, use and storage 

individuals/firms licensed or regi

state to apply termiticide and/or g

control products. 

Do not use in schools when o

Do not apply directly to food, foo

or food contact surface

Do not make surface applications 

or bedding. Mattress treatmen

confined to the seams, folds, and 

Do not use to use to treat soil 

Do not reapply to treated area mo

four weeks. 

499-548 

TC-314 (Phantom®

Pressurized Insecticide 

Formula 2) 

(General Pest-Control, 

including bed bugs, and 

Subterranean Termite 

Control) 

499-556 

TC-326 (Phantom®

Pressurized Insecticide 

with IGR) 

(General Pest-Control, 

including bed bugs, and 

Subterranean Termite 

Control) 

241-392 

Phantom®

(General Pest-Control 

including bed bugs) 

EC 

2 lb ai/gal 

Manual- or 

Mechanicallypressurized 

handwand/gun 

0.5% dilution = 0.05 

lb ai/gal 

Limited exterior 

applications to 

doors, windows, 

eaves, attic vents: 

0.00023 lb ai/ft2

Not specified 

For sale to, use and storage 

individuals/firms licensed or regi

state to apply termiticide and/or g

control products. 

Do not reapply more often than 

weeks. 

Do not make surface applica

mattresses. Mattress treatmen

confined to the seams folds and 
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Nonagricultural outdoor buildings/structures 

241-392 

Phantom®

(Pre-construction and Postconstruction Termiticide 

Soil Treatments) 

EC 

2 lb ai/gal 

Manual- or 

Mechnicallypressurized 

handwand/gun 

Inline injection 

with lateral 

dispersal nozzle 

Trenching and 

rodding 

0.25% dilution = 

0.0234 lb ai/gal 

0.0936 lb ai/ft2

Not Specified 

For sale to, use and storage 

individuals/firms licensed or regi

state to apply termiticide and/or g

control products. 

Do not reapply more often than 

weeks. 

Liquid and foam applications can 

foam applications are made, 75

application must be liquid and 2

foam. 

All applications are to soil. Drille

be plugged following appli

a. PRL = pressurized release liquid; SC= soluble-concentrate; EC = emulsifiable-concentrate. b. HED assumes the product Chlorfenapyr SC (assessed in D288704) to be similar in formulation and application to Pylon, the product listed for use o

and Economics Analysis Division’s (BEAD’s) Label Data Report. 

c. This includes commercial storages/warehouse premises, apartments, food storage areas, homes, hospitals, hotels, meat packing and food processing 

homes, restaurants, and other food handling establishments, schools, hospitals/medical institutions, supermarkets, warehouses and other commercial asewage systems, and zoos. Food handling establishments include dairies/cheese processing plant equipment (food contact), eating establishments, egg (commercial), feed mills/ feed processing plants, and food/grocery/marketing/storage/distribution facility premise. d See 40 CFR §180.513.
Page 12 of 42 

5.0 Residential Exposure and Risk Estimates 

Chlorfenapyr is registered for residential (indoor and outdoor) and medical (indoor) uses. The 

representative residential use patterns, application rates and formulations are provided in Table 

4.1. 

5.1 Residential Handler Exposure/Risk Estimates 

HED uses the term “handlers” to describe those individuals who are involved in the pesticide 

application process. HED believes that there are distinct tasks related to applications and that 

exposures can vary depending on the specifics of each task. Residential handlers are addressed 

somewhat differently by HED as homeowners are assumed to complete all elements of an 

application without use of any protective equipment. 

Four labels [7969-285 Prescription Treatment® brand Phantom®, 499-548 TC-314 (Phantom®

Pressurized Insecticide Formula 2), 499-556 TC-326 (Phantom® Pressurized Insecticide with 

IGR), and 241-392 Phantom®] have residential uses. These residential uses are for general pest 

control (including bed bugs) and allow for spot and crack/crevice applications in residential sites 

(for example, surfaces beneath cabinets and sinks, windows, and mattress seams). However, 

there are currently no registered residential uses that permit residential handlers – all labels 

indicate that products are “for sale to, use and storage only by individuals/firms licensed or 

registered by the state to apply termiticide and/or general pest control products.” Therefore, 

residential handler assessments were not conducted. 

5.2 Residential Post-application Exposure/Risk Estimates 

 

There is the potential for post-application exposure for individuals exposed as a result of being in 

an environment that has been previously treated with chlorfenapyr. The quantitative 

exposure/risk assessment for residential post-application exposures is based on the following 

scenarios: 

 Post-application inhalation exposure to adults and children (1 to <2 years old) after 

indoor perimeter/spot/crack and crevice applications. 

 Post-application dermal exposure to adults and children (1 to <2 years old) after indoor 

perimeter/spot/crack and crevice applications. 

 Post-application incidental oral exposure to children (1 to <2 years old) after indoor 

perimeter/spot/crack and crevice applications. 

The lifestages selected for each post-application scenario are based on an analysis provided as an 

Appendix in the 2012 Residential SOPs2

. While not the only lifestage potentially exposed for 

these post-application scenarios, the lifestage that is included in the quantitative assessment is 

health protective for the exposures and risk estimates for any other potentially exposed lifestage. 

 

2

 Available: http://www.epa.gov/pesticides/science/residential-exposure-sop.html
Page 13 of 42 

Based on the suggested retreatment interval for the proposed product and the use pattern, it is 

anticipated that exposures will be short-term in duration only. The short-term assessment has 

assumed no dissipation (i.e., day zero residues) for the entire exposure duration (up to 30 days). 

In addition, the short- and intermediate-term PODs are the same; therefore, the short-term 

assessment is expected to be protective of any repeated exposure for longer than 30 days. 

5.2.1 Post-application Inhalation Exposure and Risk Estimates 

Post-application inhalation exposure occurs while occupying living spaces within a residence 

after a pesticide treatment has occurred. Post-application inhalation exposure to chlorfenapyr 

can result from the registered perimeter/spot/crack and crevice pest control use (including control 

of bed bugs) from the volatilization of the pesticide after application. 

Residential Post-application Inhalation Exposure Data and Assumptions 

A series of assumptions and exposure factors served as the basis for completing the residential 

post-application inhalation risk assessment. Each assumption and factor is detailed in the 2012 

Residential SOPs2. 

Application Rate: The application rate for general residential indoor pest control was used to 

estimate post-application inhalation exposure (0.05 lb ai /gal). To determine the mass of 

pesticide applied for use in the post-application inhalation equation, it was assumed that 0.5 

gallons of spray would be applied in one residence. This value is taken from the assumptions for 

amount handled for residential handlers making indoor applications (see Residential 

SOPs/Indoor Environments). Using these assumptions results in an estimated mass of pesticide 

applied of 11,350 mg ai. 

Residential Post-application Non-Cancer Inhalation Exposure and Risk Equations 

The algorithms used to estimate residential post-application inhalation exposure and dose can be 

found in Appendix A and/or the 2012 Residential SOPs2. 

Summary of Residential Post-application Non-Cancer Inhalation Exposure and Risk Estimates 

All post-application inhalation scenarios resulted in MOEs greater than the Agency’s level of 

concern (LOC = MOE ≥ 100) for children and adults and, therefore, are not of concern. Table 

5.2.1 summarizes the post-application inhalation exposure and risk from the indoor uses of 

chlorfenapyr. 

Table 5.2.1. Post-application Inhalation Exposure and Risk Estimates for Children and Adults. 

Lifestage MLabel

(mg)a

ACH 

(1/hr) k (1/hr)b Vol (m3) 

ET 

(hr) 

Inhalation Dose 

(mg/kg/day)c, d

Short-term 

Inhalation 

MOEe

Adult 

11,350 0.45 1.02E-06 33 

16 0.0001 50,000 

Child 1 to < 2 

years old 18 0.00037 13,000 

a. Mass of active ingredient applied determined from product label (mg). 

b. k (1/hr) = [ln(0.1)*CF1] /EvapT, where EvapT = 10[7.3698-0.9546*log10(Csat)] and Csat = [Vapor pressure (1x10-7

 mm Hg) * Conversion factor (atm/760 mm Hg) * Molecular Weight (g/mol) * Conversion factor (103 mg/g) * Conversion factor 

(103 L/m3)] / [R (0.0821 L-atm/mol-K)* Temperature (296 K)] 

c. Inhalation Dose (mg/kg/day) = Exposure (mg/day) * Inhalation absorption factor (unitless) / Body Weight (kg). 

d. Exposure (mg/day) = IR*MLabel * 1 - [((ACH * e-k*ET) – (K e-ACHET))] 
Page 14 of 42 

 ACH * Vroom ACH-k 

e. Inhalation MOE = NOAEL (5 mg/kg/day) / Inhalation dose (mg/kg/day)). 

5.2.2 Post-application Dermal Exposure and Risk Estimates 

Post-application dermal exposure can result from pesticide residue transfer to the skin of 

individuals who contact previously treated indoor surfaces (e.g., carpets, floors, furniture, and 

other surfaces) during standard activities. For purposes of assessing dermal post-application 

exposure resulting from the use of chlorfenapyr to treat indoor pests (including bed bugs), HED 

has performed an indoor surface (i.e., perimeter/spot/bedbug and crack and crevice) assessment 

in addition to performing an assessment for treated mattresses. For the bed bug use, applications 

are allowed for mattresses (seams, folds and edges). The label does not allow for surface 

applications to mattresses. The assessment for the mattress application is based on an 

assumption regarding the amount of product applied per area (i.e., a twin size bed). 

Residential Post-application Dermal Exposure Data and Assumptions 

A series of assumptions and exposure factors served as the basis for completing the residential 

post-application dermal risk assessment. Each assumption and factor is detailed in the 2012 

Residential SOPs2. 

Application Rate: An application rate in units of mass per area was not provided on the labels 

registered for general pest control, which is necessary for estimation of deposited residue for 

indoor surfaces. Therefore, default assumptions for deposited residue (ug/cm2

) were used for 

this assessment based on the HED Residential SOPs/Indoor Environments. For 

perimeter/spot/bedbug (coarse) applications, a default assumption of 4.5 ug/cm2 was used; for 

perimeter/spot/bedbug (pin stream) applications, a default assumption of 1.1 ug/cm2

 was used; 

and for crack and crevice applications, a default of 0.3 ug/cm2 was used. For the mattress 

application, using the application rate of 0.05 lb ai/gal and assuming that 20% of the mattress is 

treated and 0.005 gallons of spray is used per area of the mattress, the resulting deposited residue 

value is 24.3 ug/cm2. 

Residential Post-application Non-Cancer Dermal Exposure and Risk Equations 

The algorithms used to estimate residential post-application dermal exposure and dose can be 

found in Appendix A and/or the 2012 Residential SOPs2. 

Summary of Residential Post-application Non-Cancer Dermal Exposure and Risk Estimates 

Table 5.2.2.1 summarizes the dermal post-application exposure and risk estimates from the 

perimeter/spot/bed bug use of chlorfenapyr. All post-application dermal scenarios resulted in 

MOEs greater than the Agency’s level of concern (LOC = MOE ≥ 100) for children and adults 

and, therefore, are not of concern. 

 
Page 15 of 42 

Table 5.2.2.1. Post-application Dermal Exposure and Risk Estimates for Adults and Children 1 to < 2 years old for 

the Use of Chlorfenapyr.

Surface 

Type Lifestage DepRa (ug/cm2) 

Fai

Fraction 

transferredb

TC 

Transfer 

Coefficient 

(cm2/hr) 

ET 

Exposure 

time 

(hr/day) 

E 

Exposure 

(mg/day) 

Dermal Dose b

(mg/kg/day) 

Dermal 

MOE c

Perimeter/Spot/Bedbug (coarse) 

Carpet 

Adult 

4.5 

0.06 

6,800 8 14.7 0.028 180 

Child 1 to < 

2 years old 1,800 4 1.9 0.023 220 

Hard 

Surfaces 

Adult 

0.08 

6,800 

2 

4.9 0.0092 540 

Child 1 to < 

2 years old 1,800 1.3 0.015 330 

Perimeter/Spot/Bedbug (pin stream) 

Carpet 

Adult 

1.1 

0.06 

6,800 8 3.6 0.0068 740 

Child 1 to < 

2 years old 1,800 4 0.5 0.0056 890 

Hard 

Surfaces 

Adult 

0.08 

6,800 

2 

1.2 0.0023 2,200 

Child 1 to < 

2 years old 1,800 0.3 0.0037 1,300 

Crack and Crevice 

Carpet 

Adult 

0.3 

0.06 

6,800 8 1.0 0.0018 2,700 

Child 1 to < 

2 years old 1,800 4 0.1 0.0015 3,300 

Hard 

Surfaces 

Adult 

0.08 

6,800 

2 

0.3 0.00061 8,100 

Child 1 to < 

2 years old 1,800 0.1 0.001 4,900 

a. DepR = = Deposited residue based on default assumptions in HED’s Residential SOPs. 

b. Fraction transferred is based on the Revised Residential SOP (2012) Default Value. 

c. Dose (mg/kg/day) = Deposited residue (ug/cm2) * Fraction transferred * Transfer coefficient (cm2/hr) * Exposure time 

(hr/day) * Conversion factor (0.001 mg/ug) * Dermal Absorption Factor (13 %) / Body Weight (69 kg for adults and 11 kg 

for children 1 to < 2 years old). 

d. MOE = PoD (mg/kg/day) / Dose (mg/kg/day), where Short-term dermal PoD = NOAEL of 5 mg/kg/day and level of 

concern = 100 for adults and children 1 to < 2 years old). 

All post-application dermal scenarios for the bed bug use on mattresses resulted in MOEs greater 

than the LOC and are not of concern. Table 5.2.2.2 summarizes the post-application dermal 

exposure and risk from the bed bug use on mattresses. 

Table 5.2.2.2. Post-application Dermal Exposure and Risk Estimates for Adults and Children 1 to < 2 years old for 

Bed Bug Mattress Use.

Surface 

Type Lifestage 

Deposited

Residue 

(ug/cm2)a

Surface 

area / 

Body 

Weight 

Ratio 

(cm2/kg) 

Fraction of 

skin in 

contact 

with 

surface 

Fai

Fraction 

transferred 

Protection 

factor 

Dermal Dose 

(mg/kg/day)b

Dermal 

MOEc 

Mattress 

Adult 

24.3 

280 

0.5 0.06 0.5 

0.013 380 

Child 1 to 2 

years old 640 0.03 160 

a. Residue value determined based on application rate (0.05 lb ai/gal) and assumptions for area treated and amount 

applied (see Appendix and Residential SOPs). 

b. Dermal dose (mg/kg/day) = Surface residue (μg/cm2) * Surface area / Body weight Ratio (cm2/kg) * Fraction of body 

that contacts residue (0.5) * Conversion factor (0.001 mg/ug) * Fraction transferred (0.06) * Protection factor (0.5) * 

Dermal Absorption Factor (13 %). 

c. MOE = PoD (NOAEL = 5 mg/kg/day) / Dose (mg/kg/day), mg/kg/day and level of concern = 100 for adults and 

children 1 to < 2 years old). 
Page 16 of 42 

5.2.3 Post-application Incidental Oral Exposure and Risk Estimates 

Post-application incidental oral exposure resulting from hand-to-mouth and object-to-mouth 

activities can occur as a result of the indoor perimeter/spot/bed bug application and the bed 

bug/mattress use. Only incidental oral exposures resulting from the indoor surface application 

have been assessed here since they are considered to be protective of the mattress application for 

the following reasons: (1) a protection factor of 0.5 is assumed for the mattress exposures due to 

the presence of a bed sheet over the mattress, and (2) the replenishment interval for hand-tomouth activity is assumed to be less while a child is sleeping than while they are awake. 

Table 5.2.3.1 summarizes the MOEs for hand-to-mouth transfer of pesticide residues from the 

indoor perimeter/spot/bed bug use. All hand-to-mouth post-application exposure scenarios 

resulted in MOEs higher than 100 and are therefore not of concern. 

Table 5.2.3.2 summarizes the MOEs for object-to-mouth exposure of pesticide residues from the 

indoor perimeter/spot/bed bug use. All object-to-mouth post-application exposure scenarios 

resulted in MOEs higher than 100 and are therefore not of concern. 
Page 17 of 42 

Table 5.2.3.1. Post-application Incidental Oral (Hand-to-Mouth) Exposure and Risk Estimates for Children for Perimeter/SpoChlorfenapyr. 

Surface 

Type 

 Dermal 

Exposurea

(mg/day) 

Faihandsb SAH c 

 (cm2) 

Exposure 

Frequency d

(events/hr) 

Fm e SE f ET g

 hours/day) 

Replen_ Interval h

(min) 

N_ 

Replenish i 

HR j

(mg/cm2

Perimeter/Spot/Bedbug (coarse) 

Carpet 

4.5 0.15 150 20 0.13 0.48 

4 

15 4 

0.0010 

Hard 

Surfaces 2 0.0006 

Perimeter/Spot/Bedbug (pin stream) 

Carpet 

1.1 0.15 150 20 0.13 0.48 

4 

15 4 0.0002 

Hard 

Surface 

2 

Crack and crevice – Carpets

Carpet 

0.3 0.15 150 20 0.13 0.48 

4 

15 4 0.0001 

Hard 

Surface 2 

a. Dermal Exposure value from Table 5.2.2.1. 

b. Fraction of ai on hands. c. Surface area of the hand (cm2). 

d. Number of hand-to-mouth contacts events per hour (events/hr). 

e. Fraction of hand mouthed. 

f. Saliva Extraction Factor. g. Exposure Time. h. Replenishment Interval. i. Number of Replenishment Intervals per hour. j. Hand Residue Loading (mg/cm2) = (Faihands * Dermal exposure) / (SAH * 2). 

k. Oral Dose (mg/kg/day) = Exposure (mg/day)/ Body Weight (11 kg); where Exposure (mg/day) = HR * *FM * SAH) * (ET * N_Replen) * [1-(1-SE)(Freq_Replen / 

l. MOE = PoD (mg/kg/day) / Daily Dose (mg/kg/day); incidental oral PoD = NOAEL = 5 mg/kg/day and level of concern =100. 
Page 18 of 42 

Table 5.2.3.2. Post-application Incidental Oral (Object-to-Mouth) Exposure and Risk Estimates for Perimeter/Spot/Bed Bug Use 

Surface Type DepRa (ug/cm2) Fob ORc SAMO d (cm2) 

Freq_Reple

n Exposure 

Frequency e 

(events/hr)

SE f ET g

 (hours/day) 

Replen_ 

Interval h

(min) 

N_Replen i Exposu

(mg/da

Perimeter/Spot/Bedbug (coarse) 

Carpet 

4.5 

0.06 0.270 

10 4 0.48 

4 

15 14 

0.04 

Hard Surfaces 0.08 0.360 2 0.03 

Perimeter/Spot/Bedbug (pin stream) 

Carpet 

1.1 

0.06 0.066 

10 4 0.48 

4 

15 14 

0.009

Hard Surface 0.08 0.088 2 0.006

Crack and crevice – Carpets

Carpet 

0.3 

0.06 0.018 

10 4 0.48 

4 

15 14 

0.002

Hard Surface 0.08 0.024 2 0.001

a. DepR = Deposited residue 

b. Fraction of residue transferred to an object (unitless). 

c. Chemical residue loading on the object (μg/cm2) = Deposited residue (ug/cm2) * Fo. 

d. Area of the object surface that is mouthed (cm2). 

e. Number of object-to-mouth contact events per hour (events/hr). 

f. Saliva Extraction Factor. g. Exposure Time (hours/day) h. Interval between object-to-mouth contact events (minutes). i. Number of Replenishment Intervals per hour. j. Exposure (mg/day) = ܱܴ ∗ ܨܥ1 	 ∗ ܵܯܣை ∗ 	൫ܧܶ ∗ ܰோ௘௣௟௘௡൯ ∗ 	ቆ1 െ ሺ1 െ ܵܧሻಷೝ೐೜ೃ೐೛೗೐೙ ಿೃ೐೛೗೐೙ ቇ

k. Oral Dose (mg/kg/day) = Exposure (mg/day)/ Body Weight (11 kg). l. MOE = PoD (mg/kg/day) / Daily Dose (mg/kg/day); incidental oral PoD = NOAEL = 5 mg/kg/day and level of concern = 100. 
Page 19 of 42 

5.2.4 Combined Residential Risk Estimates from the Indoor Surfaces and Bed Bug 

Mattress Use 

There is the potential for post-application dermal, oral, and inhalation exposure for children and 

post-application dermal and inhalation exposure for adults resulting from use of chlorfenapyr as 

an indoor perimeter/spot/bed bug and bed bug/mattress use. As indicated previously, the dermal, 

incidental oral, and inhalation endpoints are the same and have the same LOCs; therefore, these 

routes were combined for a total MOE. 

The incidental oral scenarios (i.e., hand-to-mouth and object-to-mouth) should be considered 

inter-related and it is likely that they occur interspersed amongst each other across time. 

Combining these scenarios with the dermal and inhalation exposure scenarios would be overlyconservative because of the conservative nature of each individual assessment. Therefore, the 

post-application exposure scenarios that were combined for children 1 < 2 years old are the 

dermal, inhalation and hand-to-mouth scenarios. This combination should be considered a 

protective estimate of children’s exposure to pesticides used indoors. 

A summary of the combined MOEs for the bed bug scenario is provided in Table 5.2.4. 

Table 5.2.4. Combined Residential Exposure and Risk Estimates from the Indoor Perimeter/Spot/Bed Bug and Bed Bug 

Mattress Use 

Population Post-application Scenarios Daily Dose 

(mg/kg/day)a MOEb Combined MOEc

Short-and Intermediate-term 

Adult 

Dermal – 

Perimeter/Spot/Bed Bug (coarse) 0.028 180 

120 Inhalation – Perimeter/Spot/Bed Bug 0.0001 50,000 

Dermal - bed bug/mattress 0.013 380 

Adult 

Dermal – 

Perimeter/Spot/Bed Bug (pin-stream) 0.0068 740 

250 Inhalation – Perimeter/Spot/Bed Bug 0.0001 50,000 

Dermal - bed bug/mattress 0.013 380 

Child (1 to <2 

years old) 

Dermal - Perimeter/Spot/Bed Bug 

(coarse) 0.023 220 

62 Inhalation – Perimeter/Spot/Bed Bug 0.00037 13,000 

Hand-to-Mouth – Perimeter/Spot/Bed 

Bug (coarse) 0.027 190 

Dermal – bed bug/mattress 0.03 160 

Child (1 to <2 

years old) 

Dermal - Perimeter/Spot/Bed Bug 

(pin-stream) 0.0056 890 

120 Inhalation – Perimeter/Spot/Bed Bug 0.00037 13,000 

Hand-to-Mouth – Perimeter/Spot/Bed 

Bug (pin-stream) 0.0065 770 

Dermal – bed bug/mattress 0.03 160 

Bolded values are below the LOC of 100. 

a. For calculations of Daily Dose, see Tables 6.2.2.1, 6.2.2.2, 6.2.3.1, and 6.2.3.2. 

b. MOE = NOAEL (5 mg/kg/day) / Dose (mg/kg/day). 

c. Adult Combined MOE = 1/ [(1/MOEDermal – Perimeter/Spot/Bed Bug) + (1/MOEDermal – bed bug mattress) + (1/MOEInhalation)] 

Child (1 to <2 years old) Combined MOE = 1/ [(1/MOEDermal – Perimeter/Spot/Bed Bug) + (1/MOEDermal – bed bug mattress) + (1/MOEInhalation) + 

(1/MOEHand-to-Mouth)] 
Page 20 of 42 

5.3 Residential Risk Estimates for Use in Aggregate Assessment 

Table 5.3.1 reflects the residential risk estimates that are recommended for use in the aggregate 

assessment for chlorfenapyr. 

 The recommended residential exposure for use in the adult aggregate assessment reflects 

combined post-application dermal and inhalation exposure from indoor applications 

(surfaces and mattresses) to control bed bugs. 

 The recommended residential exposure for use in the children 1<2 years old aggregate 

assessment reflects combined post-application dermal, inhalation, and hand-to-mouth 

exposures from indoor applications (surfaces and mattresses) to control bed bugs. 

 Table 5.3.1. Recommendations for the Residential Exposures for the Chlorfenapyr Aggregate Assessment. 

Lifestage Exposure 

Scenario 

Dose (mg/kg/day)1 MOE2

Dermal3 Inhalation Oral Total Dermal Inhalation Oral Total 

Adult 

Male/Female 

Postapplication 

exposure 

from indoor 

bed bug 

applications 

(coarse) 

0.041 0.0001 N/A 0.041 120 50,000 N/A 120 

Postapplication 

exposure 

from indoor 

bed bug 

applications 

(pin-stream) 

0.020 0.0001 N/A 0.020 250 50,000 N/A 250 

Child 

Postapplication 

exposure 

from indoor 

bed bug 

applications 

(coarse) 

0.053 0.00037 0.027 0.08 90 13,000 190 62 

Postapplication 

exposure 

from indoor 

bed bug 

applications 

(pin-stream) 

0.0356 0.00037 0.0065 0.042 140 13,000 770 120 

1

Dose = the highest dose for each applicable lifestage of all residential scenarios assessed. Total = dermal + inhalation + incidental oral (where 

applicable). 

2

MOE = the MOEs associated with the highest residential doses. Total = 1 ÷ (1/Dermal MOE) + (1/Inhalation MOE) + (1/Incidental Oral MOE), 

where applicable. 

3

Dermal values represent the sum of post-application exposure from perimeter/spot/bed bug and bed bug/mattress. 

5.4 Spray Drift 

A spray drift assessment is not included in this memo because chlorfenapyr is not registered on 

use sites that are likely to result in spray drift. As stated above, chlorfenapyr is registered for use 

only on greenhouse food and non-food crops, and as an insecticide/termiticide for use on indoor 
Page 21 of 42 

and outdoor residential sites, food/feed handling areas, indoor and outdoor commercial sites 

(including sewers), and indoor medical sites. 

6.0 Occupational Exposure and Risk Estimates 

6.1 Occupational Handler Exposure/Risk Estimates 

HED uses the term handlers to describe those individuals who are involved in the pesticide 

application process. HED believes that there are distinct job functions or tasks related to 

applications and exposures can vary depending on the specifics of each task. Job requirements 

(amount of chemical used in each application), the kinds of equipment used, the target being 

treated, and the level of protection used by a handler can cause exposure levels to differ in a 

manner specific to each application event. 

Based on the anticipated use patterns and current labeling, types of equipment and techniques 

that can potentially be used, occupational handler dermal and inhalation exposures are expected 

from the existing uses of chlorfenapyr. The quantitative exposure/risk assessment developed for 

occupational handlers is based on the following scenarios which cover all the registered uses of 

chlorfenapyr: 

 Mixing/loading/applying liquids via injector (termiticide) 

 Mixing/loading/applying liquids via mechanically-pressurized handgun 

 Applying pressurized liquids via ready-to-use aerosol cans 

 Mixing/loading/applying liquids via manually-pressurized handwand 

 Mixing/loading/applying liquids via backpack sprayer 

In addition to the above exposure scenarios, there is also a total release fogger product registered 

for use in greenhouses. An assessment of handler exposure from the use of total release foggers 

was not performed because dermal and inhalation exposure is expected to be negligible based on 

the use pattern for this method of application. A total release fogger is an aerosol pesticide 

device designed to automatically release its total content in one operation for the purpose of 

creating a permeating fog within a space to deliver the pesticide throughout the space. 

Therefore, total release aerosols do not need any other application equipment (PR NOTICE 98-6, 

1998). Furthermore, most product labels for total release foggers include directions for use that 

limit exposure to the handler, such as: 1) “tilt can away from face and depress tab,” 2) “aim spray 

away from face and set fogger in treatment area,” and 3) “immediately leave the treatment area 

and close the door.” As a common integrated pest management (IPM) and preventive safety 

practice, if multiple foggers are to be activated, the labels typically recommend that the handler 

“start at the far end of the area, opposite from the exit door, activating and placing cans as you 

move across the area until you have reached the exit door.” Once the handler has left the area, 

the labels also direct users to stay out of the treated area for a certain amount of time and to 

ventilate the area before re-entry. HED recommends that RD ensure the appropriate safety 

directions and re-entry restrictions are included in the label. 
Page 22 of 42 

Occupational Handler Exposure Data and Assumptions 

A series of assumptions and exposure factors served as the basis for completing the occupational 

handler risk assessments. Each assumption and factor is detailed below on an individual basis.

Application Rate: A summary of the maximum application rates for each crop or use site are 

provided in Table 4.1. 

Unit Exposures: It is the policy of HED to use the best available data to assess handler exposure. 

Sources of generic handler data, used as surrogate data in the absence of chemical-specific data, 

include PHED 1.1, the AHETF database, the Outdoor Residential Exposure Task Force 

(ORETF) database, or other registrant-submitted occupational exposure studies. Some of these 

data are proprietary (e.g., AHETF data), and subject to the data protection provisions of FIFRA. 

The standard values recommended for use in predicting handler exposure that are used in this 

assessment, known as “unit exposures”, are outlined in the “Occupational Pesticide Handler Unit 

Exposure Surrogate Reference Table3”, which, along with additional information on HED policy 

on use of surrogate data, including descriptions of the various sources, can be found at the 

Agency website4. 

Area Treated or Amount Handled: The daily areas treated or amounts handled were defined for 

each handler scenario (in appropriate units) by determining the amount that can be reasonably 

treated by an individual in a single day. When possible, the assumptions for daily areas treated 

or amounts handled are taken from the HED’s ExpoSAC Policy 9.1: “Standard Values for Daily 

Acres Treated in Agriculture”. Values used for area treated or amount handled include the 

following: 

 124 gallons/day for mixing/loading/applying of liquids via injector (see note below) 

 1,000 gallons/day for mixing/loading/applying liquids via mechanically pressurized 

handgun 

 20 cans/day for applicator for ready-to-use aerosol cans (see note below) 

 40 gallons for backpack and manually-pressurized handwand applications 

Note: 

 Since there is no information with regards to “typical” applications of ready-to-use 

aerosol cans for termiticide, HED has assumed an applicator is exposed to the entire 

contents of a 17.5 fl ounce spray can. HED does not have information with regards to 

how many cans might be used (i.e., applied by an individual) in a given work day. 

Further, there is no information as to what fraction of a container might typically be used 

in a given work day. Therefore, for purposes of a Tier I or “screening” level assessment, 

HED presented estimates of exposure and risk that might result from applying 20 cans in 

a given work day. 

 For the termiticide assessment, HED assumed 124 gallons for mixing/loading/applying 

liquids via injector based on a previous assessment (D266562, D, Smegal et al., 20-

JUNE- 2000). This is the average amount applied per residence for termiticide 

treatments. 

 

3

 Available: http://www.epa.gov/opp00001/science/handler-exposure-table.pdf 4

 Available: http://www.epa.gov/pesticides/science/handler-exposure-data.html
Page 23 of 42 

Exposure Duration: HED classifies exposures from 1 to 30 days as short-term and exposures 30 

days to six months as intermediate-term. Exposure duration is determined by many things, 

including the exposed population, the use site, the pest pressure triggering the use of the 

pesticide, and the cultural practices surrounding that use site. For most agricultural uses, it is 

reasonable to believe that occupational handlers will not apply the same chemical every day for 

more than a one-month time frame; however, there may be a large agribusiness and/or 

commercial applicators who may apply a product over a period of weeks (e.g., completing 

multiple applications for multiple clients within a region). 

For chlorfenapyr, based on the existing labeled use patterns, short- and intermediate-term 

exposures are expected. The greenhouse ornamentals and vegetables allow multiple applications 

with most having a 5 to 7 day retreatment interval. The labels for the nonagricultural uses do not 

specify a frequency. Since chlorfenapyr is an insecticide it is not expected that the number of 

applications will be more than a handful of times per year. Long-term exposure is therefore not 

expected. 

Mitigation/Personal Protective Equipment: Occupational handler exposure assessments are 

completed by HED using different levels of risk mitigation. Typically, HED uses a tiered 

approach. The lowest tier is designed as the baseline exposure scenario (i.e., long-sleeve shirt, 

long pants, shoes, socks, no respirator). If risk estimates are of concern at baseline attire, then 

increasing levels of PPE (i.e., gloves, respirators) are evaluated. This approach is used to ensure 

that the lowest level of risk mitigation that provides adequate protection is selected. Estimates of 

inhalation exposure were calculated for “baseline,” defined as a single layer of clothing 

consisting of a long sleeved shirt, long pants, shoes plus socks, no protective gloves, and no 

respirator. The chlorfenapyr product labels direct mixers, loaders, applicators and other handlers 

to wear long-sleeved shirt and long pants, chemical resistant gloves, shoes plus socks. Some of 

the labels (499-544, 499-556) require additional PPE, including protective eyewear. The 

Phantom® Termiticide-Insecticide label (241-292) also requires all handlers to wear a dust/mist 

filtering respirator (MSHA/NIOSH Approved Number Prefix TC-21C) or a NIOSH approved 

respirator with any N, R, P or HE filter when working in a non-ventilated space, including but 

not limited to crawl-spaces and basements. All termiticide handlers must wear protective 

eyewear when working in a non-ventilated space when applying termiticide by rodding or subslab injection. 

Occupational Handler Non-Cancer Exposure and Risk Estimate Equations 

The algorithms used to estimate non-cancer exposure and dose for occupational handlers can be 

found in Appendix A. 

Combining Exposures/Risk Estimates: 

Dermal and inhalation risk estimates were combined in this assessment, since the toxicological 

effects for these exposure routes were similar. Dermal and inhalation risk estimates were 

combined using the following formula: 

Total MOE = Point of Departure (mg/kg/day) ÷ Combined dermal + inhalation dose (mg/kg/day)

 
Page 24 of 42 

Summary of Occupational Handler Non-Cancer Exposure and Risk Estimates 

Most occupational handler inhalation risk estimates resulted in MOEs greater than the level of 

concern (LOC = MOE ≥100) at baseline or with additional PPE, and therefore, are not of 

concern. The following is a summary of the occupational handler combined risk estimates: 

 For mixers/loaders/applicators (MLAs) of liquids using an injector for termiticide 

applications, combined MOEs were above the LOC of 100 at baseline (single layer of 

clothing, no gloves, no respirator). 

 For MLAs of liquids using a backpack or manually-pressurized handwand for 

applications to greenhouse ornamentals, combined MOEs were above the LOC of 100 at 

baseline. 

 For applicators using ready-to-use aerosol cans, combined MOEs were above the LOC of 

100 with a single layer of clothing and gloves, but no respirator. 

 For MLAs of liquid using a manually-pressurized handwand for application to 

greenhouse vegetables, combined MOEs were above the LOC of 100 with a single layer 

of clothing and gloves, but no respirator. 

 For MLAs of liquids using a manually-pressurized handwand for applications to indoor 

environments such as food handling establishments, warehouses, and residential living 

spaces, combined MOEs were above the LOC of 100 with a single layer of clothing, 

gloves and a PF5 respirator. 

 For mixers/loaders/applicators of liquids using a mechanically-pressurized handgun for 

termiticide applications to structures, combined MOEs were above the LOC of 100 with a 

single layer of clothing, gloves and a PF5 respirator. 

 For mixers/loaders/applicators of liquids using a mechanically-pressurized handgun for 

greenhouse applications, combined MOEs did not reach the LOC of 100 even with 

maximum PPE (i.e., double layer, gloves and PF10 respirator). 

 
Page 25 of 42 

Table 6.1. Occupational Handler Non-Cancer Exposure and Risk Estimates for Chlorfenapyr. 

Exposure Scenario Crop or Target 

Dermal Unit 

Exposure (μg/lb 

ai)1

Inhalation 

Unit Exposure 

(μg/lb ai)1 Maximum 

Application 

Rate2

Area 

Treated or 

Amount 

Handled 

Daily3

Dermal I

Mitigation Level

(Baseline unless 

specified 

otherwise) 

Mitigation Level

(Baseline unless 

specified 

otherwise) 

MOE5 

Dose4

(mg/kg/day)4

Dos

(mg/kg

Mixer/Loader/Applicator 

Injector (termiticide) Structural (termiticide) 1,300 2 0.0234 lb ai/gal 124 gal9 0.0071 700 0.0000

 Backpack 

Greenhouse 

(ornamentals) 13,200 140 0..0016 lb ai/gal 40 gal 0.00159 3,100 0.000

Greenhouse (fruiting 

vegetables) 13,200 140 0.04 lb ai/gal 40 gal 0.0390 130 0.003

Manually-Pressurized 

Handwand 

Greenhouse 

(ornamentals) 100,000 30 0.0016 lb ai/gal 40 gal 0.0121 410 0.0000

Greenhouse (fruiting 

vegetables) 

100,000 

30 0.04 lb ai/gal

40 gal 

0.301 17 

0.000

430 

(SL with G) 0.0013 3,800 

Crack and crevice – 

residential living spaces, 

food handling 

establishments, 

warehouses 

29,000 1,100 

0.05 lb ai/gal 

0.109 46 

0.03

8,600 

(SL with G) 0.0324 150 

220 

(PF5 R) 0.006

MechanicallyPressurized Handgun 

Greenhouse 

(ornamentals) 3,500 120 0.0016 lb ai/gal 1000 gal 0.0106 470 0.002

Greenhouse (fruiting 

vegetables) 

3,500 120 

0.04 lb ai/gal 1000 gal 

0.264 19 0.06

2,500 

(SL with G) 

24 

(PF5R) 0.188 27 0.01

1,600 

(DL with G) 

12 

(PF10R) 0.121 41 0.006

Structural (termiticide) 

1,800 

79 0.0234 lb ai/gal 1000 gal 

0.0793 63 

0.02

640 

(SL with G) 0.0283 180 

365 (DL with G) 0.0161 310 
Page 26 of 42 

Table 6.1. Occupational Handler Non-Cancer Exposure and Risk Estimates for Chlorfenapyr. 

Exposure Scenario Crop or Target 

Dermal Unit 

Exposure (μg/lb 

ai)1

Inhalation 

Unit Exposure 

(μg/lb ai)1 Maximum 

Application 

Rate2

Area 

Treated or 

Amount 

Handled 

Daily3

Dermal I

Mitigation Level

(Baseline unless 

specified 

otherwise) 

Mitigation Level

(Baseline unless 

specified 

otherwise) 

MOE5 

Dose4

(mg/kg/day)4

Dos

(mg/kg

Applicator 

Ready-to-use 

Aerosol cans 0.087 0.0557 Crack and crevice (termiticide) 190,000 1,300 0.005 lb ai/can 20 cans 0.0358 140 0.00

Bolded values are below the LOC of 100. 1 Based on the “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table”; Level of mitigation: Baseline, Eng. Controls. 2 Based on all registered labels (See Appendix B). 3 Exposure Science Advisory Council Policy #9.1. 4 Dermal Dose = Dermal Unit Exposure (μg/lb ai) × Conversion Factor (0.001 mg/μg) × Application Rate (lb ai/gal or can) × Amount Handled Daily (gal or can/day) × 

5 Dermal MOE = Dermal NOAEL (5 mg/kg/day) ÷ Dermal Dose (mg/kg/day). 

6 Inhalation Dose = Inhalation Unit Exposure (μg/lb ai) × Conversion Factor (0.001 mg/μg) × Application Rate (lb ai/gal or can) × Amount Handled Daily (gal or can/

7 Inhalation MOE = Inhalation NOAEL (5 mg/kg/day) ÷ Inhalation Dose (mg/kg/day). 8 Total MOE = 1 ÷ (1/Dermal MOE) + (1/Inhalation MOE) 9 The unit treated for injector are from Memo D. Smegal and T. Leighton, 20 June 2000, D266562 indicates an average of 124 gallons per residence for termiticide trea
Page 27 of 42 

6.2 Occupational Post-application Exposure 

HED uses the term post-application to describe exposures that occur when individuals are 

present in an environment that has been previously treated with a pesticide (also referred to as reentry exposure). Such exposures may occur when workers enter previously treated areas to 

perform job functions, including activities related to crop production, such as scouting for pests 

or harvesting. Post-application exposure levels vary over time and depend on such things as the 

type of activity, the nature of the crop or target that was treated, the type of pesticide application, 

and the chemical’s degradation properties. In addition, the timing of pesticide applications, 

relative to harvest activities, can greatly reduce the potential for post-application exposure. 

6.2.1 Occupational Post-application Inhalation Exposure/Risk Estimates 

Based on the Agency's current practices, a quantitative post-application inhalation exposure 

assessment was not performed for chlorfenapyr at this time primarily because of the low acute 

inhalation toxicity (Toxicity Category III), low vapor pressure 1.0 x 10-7 mm HG @ 25 ̊C, and 

the low registered use rate (0.04 -0.2 lb ai/A). However, there are multiple potential sources of 

post-application inhalation exposure to individuals performing post-application activities in 

previously treated fields. These potential sources include volatilization of pesticides and 

resuspension of dusts and/or particulates that contain pesticides. The Agency sought expert 

advice and input on issues related to volatilization of pesticides from its Federal Insecticide, 

Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP) in December 2009, and 

received the SAP’s final report on March 2, 20105. The Agency is in the process of evaluating 

the SAP report as well as available post-application inhalation exposure data generated by the 

ARTF and may, as appropriate, develop policies and procedures, to identify the need for and, 

subsequently, the way to incorporate occupational post-application inhalation exposure into the 

Agency's risk assessments. If new policies or procedures are put into place, the Agency may 

revisit the need for a quantitative occupational post-application inhalation exposure assessment 

for chlorfenapyr. 

The Worker Protection Standard for Agricultural Pesticides contains requirements for protecting 

workers from inhalation exposures during and after greenhouse applications through the use of 

ventilation requirements [40 CFR 170.110, (3) (Restrictions associated with pesticide 

applications)]. 

Commercial applicators do not typically return to the treated areas after an indoor commercial 

pesticide application (sites such as warehouses, food handling establishments, and hotels, etc.) 

and thus an occupational post-application inhalation exposure assessment was not performed for 

commercial applicators. 

 

5

 Available: http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html
Page 28 of 42 

6.2.2 Occupational Post-application Dermal Exposure/Risk Estimates 

Occupational Post-application Dermal Exposure Data and Assumptions 

A series of assumptions and exposure factors served as the basis for completing the occupational 

post-application risk assessments. Each assumption and factor is detailed below on an individual 

basis. 

Exposure Duration: HED classifies exposures from 1 to 30 days as short-term and exposures 30 

days to six months as intermediate-term. For the registered use pattern, short- and intermediateterm exposures are anticipated for the following reasons only up to three applications can be 

made. The same exposure durations are anticipated for all registered chlorfenapyr uses, and it 

should be noted that the short- and intermediate-term PODs are the same; therefore, short-term 

risk estimates are protective of longer-term exposures. 

Transfer Coefficients: It is the policy of HED to use the best available data to assess postapplication exposure. Sources of generic post-application data, used as surrogate data in the 

absence of chemical-specific data, are derived from ARTF exposure monitoring studies, and, as 

proprietary data, are subject to the data protection provisions of FIFRA. The standard values 

recommended for use in predicting post-application exposure that are used in this assessment, 

known as “transfer coefficients”, are presented in the ExpoSAC Policy 36

” which, along with 

additional information about the ARTF data, can be found at the Agency website7. 

Table 6.2.2.1. Anticipated Post-Application Activities and Dermal Transfer Coefficients. 

Proposed 

Crops 

Policy Crop 

Group 

Category 

Crop 

Height 

Foliage 

Density 

Transfer 

Coefficients 

(cm2/hr)

Activities 

Greenhouse 

Vegetables No subcrop 

Low Min 230 Transplanting, 

High Full Irrigation (hand watering) 

High Full 

1,200 

Hand harvesting, Pinching, Pollination, 

Scouting, Turing, Tying/training, Hand 

Weeding, Hand Pruning, 

Low Full Hand harvesting, Hand Pruning 

Low Min Pinching, Propagating, Hand Pruning 

Scouting, Hand Weeding, 

Greenhouse 

Ornamentals, 

Non-bearing 

Plant 

No subcrop 

High Full 

0 

Mechanical Weeding, Irrigation (non-hand 

Low Full set), Spreading Bins 

Low Min Fertilizing 

High Full 

230 

Hand harvesting, Hand Pruning, Scouting, 

Container Moving, Hand Weeding, 

Transplanting, Pinching,

Low Full 

Hand harvesting, Hand Pruning, Scouting, 

Hand Weeding, Transplanting, Pinching, 

Tying/Training

Low Min Grafting, Propagating, Transplanting 

High Min Hand harvesting, Hand pruning, 

Transplanting 

 

6

 Available: http://www.epa.gov/pesticides/science/exposac_policy3.pdf 7

 Available: http://www.epa.gov/pesticides/science/post-app-exposure-data.html
Page 29 of 42 

Table 6.2.2.1. Anticipated Post-Application Activities and Dermal Transfer Coefficients. 

Proposed 

Crops 

Policy Crop 

Group 

Category 

Crop 

Height 

Foliage 

Density 

Transfer 

Coefficients 

(cm2/hr)

Activities 

Floriculture 

Crop Flowers cut 

Low Full 

230 

Container Moving, Pinching, Hand Pruning, 

Hand Weeding, Scouting, Transplanting 

High Full Hand Pruning, Hand Weeding, Scouting, 

Low Min Hand Weeding, Transplanting, Pinching 

High Full 1,900 Irrigation (hand set) 

High Full 4,800 Hand Harvesting Low Full 

Application Rate: 

The application rates used in this assessment are provided in Table 4.1. 

Exposure Time: The average occupational workday is assumed to be 8 hours. 

Dislodgeable Foliar Residues: In accordance with 40CFR158, DFR data are required for all 

occupational (e.g., crop, nursery, greenhouse use sites) or residential (e.g., ornamental and 

vegetable gardens, pick your own farms, retail tree farms) uses that could result in postapplication exposure to foliage. In the absence of chemical-specific DFR data, EPA uses default 

values. The 2012 Standard Operating Procedures for Residential Pesticide Exposure 

Assessment includes an analysis of a number of DFR studies, which resulted in the selection of a 

revised default values for the fraction of the application rate available for transfer after a foliar 

application (FAR). These values are based on an analysis of 19 DFR studies. Since that time, the 

Agricultural Re-entry Task Force has submitted information (MRID 49299201) that corrects an 

application rate error made in the original submission of “ARF039 – Determination of Dermal 

and Inhalation Exposure to Reentry Workers During Chrysanthemum Pinching in a Greenhouse” 

(EPA MRID 45344501). As a result, the range of FAR values was revised from 2% - 89% to 2% 

- 47%. In the data, a large range of transferability is observed and this variability can potentially 

be attributable to many factors such as active ingredient; formulation; field conditions in the 

studies; weather conditions (e.g., humidity); or many other difficult to quantify factors. 

Although witnessed across multiple chemicals, this range in FAR values is not expected when 

considering DFR data for a single chemical. At this time, the ARTF submission did not alter the 

selection of 25% as the reasonable, high-end default value. Because DFR data are not available 

for chlorfenapyr, EPA is using the default value of 25%. Although there may be a small degree 

of uncertainty in the use of the default DFR value for chlorfenapyr (i.e., there is a small chance 

that the FAR value may exceed the applicable default value), it is likely that the health-protective 

aspects of EPA’s occupational post-application assessment methodology will more than 

compensate for this potential uncertainty. For example, when assessing residential and 

occupational post-application exposure to gardens and ornamentals, EPA assumes the following: 

exposures occur to zero-day (i.e., day of application ) residues every day of the assessed 

exposure duration (i.e., EPA assumes that no dissipation or degradation occurs, it doesn’t rain, 

etc); individuals perform the same post-application activities performed in the transfer 

coefficient study day after day (e.g., weeding, harvesting, pruning, etc.); and individuals engage 

in these post-application activities for a high-end amount of time every day (represented by data 

reflecting time spent gardening based on survey data). 
Page 30 of 42 

Given the conservatisms discussed above and the potential compounding nature of these 

conservatisms, EPA is able to rely upon the calculated exposure estimates with confidence that 

exposure is not being underestimated. 

Since the highest estimated occupational post-application exposure using default DFR values for 

chlorfenapyr is not minimal in comparison to the level of concern (i.e., the calculated MOE is 

not greater than 2 times higher than the level of concern, MOE = 120 compared to the LOC of 

200); EPA is requiring the 40CFR DFR data. EPA is requiring the 40CFR DFR data 

requirement to facilitate any necessary exposure assessments refinements and to further EPA’s 

general understanding of the availability of dislodgeable foliar pesticide residues.

Occupational Post-application Non-Cancer Dermal Exposure and Risk Estimate Equations 

The algorithms used to estimate non-cancer exposure and dose for occupational post-application 

workers can be found in Appendix A. 

Occupational Post-application Non-Cancer Dermal Risk Estimates 

The short- and intermediate-term post-application exposure scenarios associated with the 

registered uses of chlorfenapyr are summarized in Table 6.2.2.2. All scenarios resulted in MOEs 

greater than the LOC of 100 (ranging from 120 to 2,600) on day 0 (12 hours after application) 

and, therefore, are not of concern to HED. 

Table 6.2.2.2. Occupational Post-application Non-Cancer Exposure and Risk Estimates for Chlorfenapyr.

Crop/Site Activities 

Transfer 

Coefficient 

(cm2/hr) 

DFR/TTR1 Dermal Dose 

(mg/kg/day)2 MOE3

Short and Intermediate-Term 

Floriculture Crop 

(cut flowers) 

Container Moving, Pinching, Hand 

Pruning, Hand Weeding, Scouting, 

Transplanting, 

230 

0.56 

0.002 2,600 

Irrigation (hand set) 1,900 0.016 310 

Hand Harvesting 4,800 0.041 120 

Greenhouse Vegetables 

Transplanting, Irrigation (hand 

watering) 230 0.002 2,600 

Hand harvesting, Pinching, 

Pollination, Hand Pruning, 

Scouting, Turing, Tying/training, 

Hand Weeding, Propagating, Hand 

Pruning, Scouting 

1200 0.010 490 

Greenhouse 

Ornamental, Nonbearing Plant 

Hand harvesting, Hand Pruning, 

Scouting, Container Moving, Hand 

Weeding, Transplanting, Pinching, 

Tying/Training, Grafting, 

Propagating 

230 0.002 2,600 

1 DFR = Application Rate × F × (1-D)t × 4.54E8 μg/lb × 2.47E-8 acre/cm2; where F = 0.25 and D = 0.10 per day 

2 Daily Dermal Dose = [DFR (μg/cm2

) × Transfer Coefficient × 0.001 mg/μg × 8 hrs/day × dermal absorption (%)]  BW (kg).

3 MOE = POD (5 mg/kg/day) / Daily Dermal Dose. Daily Dermal Dose = [DFR (μg/cm2

) × TC × 0.001 mg/μg × 8 hrs/day × dermal 

absorption factor (13 %)]  BW 69 kg).
Page 31 of 42 

Restricted Entry Interval 

The REIs specified on existing labels are based on the acute toxicity of chlorfenapyr. 

Chlorfenapyr is classified as Toxicity Category III or IV via the dermal route and skin irritation 

potential. It is not a skin sensitizer. Under 40 CFR 156.208 (c) (2) (iii), a.i.’s classified as Acute 

III or IV for acute dermal, eye irritation and primary skin irrigation are assigned a 12-hour REI. 

Therefore, the [156 subpart K] Worker Protection Statement interim REI of 12 hours is adequate 

to protect agricultural workers from post-application exposures to chlorfenapyr. Only two labels 

specify a REI. These are Pylon® TR (Total Release miticide/insecticide) (TC-307) and Pylon®

(241-374). 
Page 32 of 42 

Appendix A: Summary of Occupational and Residential Algorithms 

Occupational Non-cancer Handler Algorithms 

Potential daily exposures for occupational handlers are calculated using the following formulas: 

E=UE * AR * A * 0.001 mg/ug

where: 

E = exposure (mg ai/day), 

UE = unit exposure (μg ai/lb ai), 

AR = maximum application rate according to label (lb ai A or lb ai/gal), and 

A = area treated or amount handled (e.g., A/day, gal/day). 

 

The daily doses are calculated using the following formula: 

ADD= 

E * AF

BW

where: 

ADD = average daily dose absorbed in a given scenario (mg ai/kg/day), 

E = exposure (mg ai/day), 

AF = absorption factor (dermal and/or inhalation), and 

BW = body weight (kg). 

Margin of Exposure: Non-cancer risk estimates for each application handler scenario are 

calculated using a Margin of Exposure (MOE), which is a ratio of the toxicological endpoint to 

the daily dose of concern. The daily dermal and inhalation dose received by occupational 

handlers are compared to the appropriate POD (i.e., NOAEL) to assess the risk to occupational 

handlers for each exposure route. All MOE values are calculated using the following formula: 

MOE= 

PODADD

where: 

MOE = margin of exposure: value used by HED to represent risk estimates (unitless), 

POD = point of departure (mg/kg/day), and 

ADD = average daily dose absorbed in a given scenario (mg ai/kg/day). 

Occupational Non-cancer Post-application Algorithms 

Potential daily exposures for occupational post-application workers are calculated using the 

following formulas: 
Page 33 of 42 

DFRt=AR * F* (1-D)t* ቀ4.54E8 ug

lbቁ * ൬2.47E-8

A

cm2൰

where: 

DFRt = dislodgeable foliage residue on day "t" (μg/cm2), 

AR = application rate (lb ai/acre), 

F = fraction of ai retained on foliage or 25% (unitless), 

D = fraction of residue that dissipates daily or 10% (unitless), and 

t = number of days after application day (days). 

E=TC * DFR t

* ET * 0.001 mg

ug

where: 

E = exposure (mg ai/day), 

TC = transfer coefficient (cm2/hr), 

DFRt = dislodgeable foliar residue on day “t” (μg/cm2), and 

ET = exposure time (hours/day). 

 

The daily doses are calculated using the following formula: 

ADD= 

E * AF

BW

where: 

ADD = average daily dose absorbed in a given scenario (mg ai/kg/day), 

E = exposure (mg ai/day), 

AF = absorption factor (dermal and/or inhalation), and 

BW = body weight (kg). 

Margin of Exposure: Non-cancer risk estimates for each scenario are calculated using a Margin 

of Exposure (MOE), which is a ratio of the toxicological endpoint to the daily dose of concern. 

The daily dermal dose received by occupational post-application workers is compared to the 

appropriate POD (i.e., NOAEL) to assess the risk to occupational post-application workers. All 

MOE values are calculated using the following formula: 

MOE= 

POD

ADD

where: 

MOE = margin of exposure: value used by HED to represent risk estimates (unitless), 

POD = point of departure (mg/kg/day), and 

ADD = average daily dose absorbed in a given scenario (mg ai/kg/day). 
Page 34 of 42 

Residential Non-cancer Handler Algorithms 

Residential Non-cancer Post-application Algorithms 

Exposure to pesticide vapors 

The following algorithm is used to determine post-application inhalation exposure from indoor 

surface-directed sprays: 

ൌ ܧ

௟௘௕௔௟ܯ	 ∗ ܴܫ

ܪܥܣ	 ∗ ܸ ௠௢௢௥ቈ1െቆሺܪܥܣ ∗ ݁ି∗௞ா்ሻ െ ሺ݇ ∗ ݁ି஺஼ு∗ா்ܪܥܣ െ ݇ ቇ቉

where: 

E = exposure (mg/day); 

IR = inhalation rate (m3

/hr); 

Mlabel = mass of active ingredient applied, determined from product label (mg); 

Vroom = volume of room (m3); 

ACH = air exchanges per hour (1/hr); 

k = first order decay rate (1/hr); and 

ET = exposure time (hr). 

In the above equation, a mass of pesticide is applied to a surface and the emission of the 

pesticide from the surface is assumed to decline over time due to dissipation of the pesticide (i.e., 

emission from the treated surface and removal due to the air exchange rate). The mass of active 

ingredient applied can be calculated using the following formula: 

1ܨܥ ∗ ܣ ∗ ܴܣ ൌ௟௔௕௘௟ ܯ

where: 

Mlabel = mass of active ingredient applied, determined from product label (mg); 

AR = application rate (e.g., lb ai/ft2

, lb ai/gal); 

A = area treated or amount handled (e.g., ft2/day, gal/day); and 

CF1 = conversion factor (4.54x105

 mg/lb). 

The exposure equation models an emission rate that decreases over time, which is based on a 

first-order decay rate constant (k). Evans (1994) proposed calculating such a decay rate based on 

work done by Chinn (1981). Chinn developed the following relationship between the volatility, 

or saturation concentration (Csat), of a chemical and the time required for 90% of the chemical to 

evaporate (EvapT): 

 

ݒܧܽ݌ܶ ൌ 10ሾ଻.ଷ଺ଽ଼ି଴.ଽହସ଺∗ ௟௢௚భబሺ஼ೞೌ೟ሻሿ

where: 
Page 35 of 42 

EvapT = evaporation time (sec); and 

Csat = saturation concentration (mg/m3). 

Evans proposed the following equation to calculate the decay rate (or dissipation rate) that 

defines the change in the emission rate based on the evaporation time described by Chinn: 

݇ ൌ

lnሺ0.1ሻ ∗ ܨܥ1

ܶ݌ܽݒܧ

where: 

k = first order decay rate (1/hr), 

CF1 = conversion factor (sec/hr), and 

EvapT = evaporation time (sec). 

The exposure equation above is based on the mass of pesticide applied, not the concentration of 

the pesticide in the air; therefore, the reviewer must check that the input for mass applied (Mlabel) 

is predicting an air concentration less than or equal to the saturation concentration. The 

following equation can be used to calculate the theoretical mass applied that would result in an 

air concentration that reaches the saturation concentration for a pesticide (MCsat): 

ܯ஼ೞೌ೟ ൌ ܥ௦௔௧ ∗ ሺܪܥܣ െ ݇ሻ ∗ ܸ

݇

MCsat should be compared to Mlabel. 

 If Mlabel > MCsat  Mlabel will predict an air concentration higher than the saturation 

concentration. Use MCsat in the exposure calculation. 

 If Mlabel < MCsat,  Mlabel will not predict an air concentration higher than the saturation 

concentration. Use Mlabel in the exposure calculation. 

Once the post-application inhalation exposure is calculated, the inhalation dose normalized to 

body weight is calculated as: 

ൌ ܦ

ܨܣ ∗ ܧ

ܹܤ

where: 

D = dose (mg/kg-day); 

E = exposure (mg/day); 

AF = absorption factor (inhalation); and 
Page 36 of 42 

BW = body weight (kg).

Table A-X: Indoor Environments – Inputs for Residential Post-application Inhalation Exposure 

Algorithm 

Notation 

Exposure Factor 

(units) Point Estimate(s) 

Generic Variables Used in Calculating Post-application Inhalation Exposure 

IR Inhalation rate 

(m3/hour) 

Adult 0.64 

Children 1 < 2 years old 0.33 

ACH Air changes per hour 

(hr-1) 0.45 

BW Body weight 

(kg) 

Adult 69 

Children 1 < 2 years old 11 

Vroom Volume of room 

(m3) 33 

Variables Specific to Post-application Inhalation Exposure to Pesticide Vapors 

Csat Saturation concentration 

(mg/m3) Calculated 

VP Vapor pressure 

(mmHg) 1.0 x 10-7 mm HG @ 25 ̊C 

MW Molecular weight 

(g/mol) 407.6

R Gas constant 

(L-atm/mol-K) 0.0821 

T Temperature of the air 

(kelvin, K) 298 

Mlabel Mass of active ingredient applied 

(mg) [input]

k First order decay rate Calculated 

ET Exposure time 

(hr./day) 

Adult 16 

Children 1 < 2 years old 18 

Post-Application Dermal Exposure Algorithm (hard surfaces and carpets) 

The algorithm to calculate exposure is as follows: 

1ܨܥ ∗ ܶܧ ∗ ܥܶ ∗ ܴܶ ൌ ܧ

where: 

E = exposure (mg/day); 

TR = indoor surface transferable residue (μg/cm2

); 

TC = transfer coefficient (cm2/hr); 

ET = exposure time (hr/day); and 

CF1 = conversion factor (0.001 mg/μg). 

If chemical-specific TR data are available, this is preferred and should be used to calculate 

exposure. However, if chemical-specific TR data are not available, then TR can be calculated 

using the following formula: 

௜௔ܨ ∗ ܴ݌݁ܦ ൌ ܴܶ

 

where: 
Page 37 of 42 

TR = indoor surface transferable residue (μg/cm2

); 

DepR = deposited residue (g/cm2), based on (in order of preference): 

 (1) Chemical-specific residue deposition data (g/cm2), 

 (2) Application rate (lb ai/area), or 

 (3) Default residue based on type of application (g/cm2

); and 

Fai = fraction of ai available for transfer from carpet or hard surface (unitless). 

Absorbed dermal dose, normalized to body weight, are calculated as: 

ൌ ܦ

ܨܣ ∗ ܧ

ܹܤ

 

where: 

D = dose (mg/kg-day); 

E = exposure (mg/day); 

AF = absorption factor; and 

BW = body weight (kg). 

Table A-X: Indoor Environments (Hard Surfaces and Carpets) – Inputs for Residential Post-application Dermal 

Exposure 

Algorithm 

Notation 

Exposure Factor 

(units) Point Estimate(s) 

TR Transferable residue 

(g/cm2) Estimated: DepR * Fai 

DepR Deposited residue 

(g/cm2) 

 Estimated based on default residue 

related to type of application 

Fai Fraction of DepR as TR 

following application 

Carpets 0.06a

Hard surfaces 0.08a

TC Transfer Coefficient 

(cm2/hr) 

Adult 6,800 

Children 1 < 2 years old 1,800 

ET Exposure Time (hrs/day) 

Adults 

Carpets 8 

Hard 

Surfaces 2 

Children 1 < 2 

years old 

Carpets 4 

Hard 

Surfaces 2 

BW Body weight (kg) Adult 69 

Children 1 < 2 years old 11 

Post-Application Dermal Exposure Algorithm (mattresses) 

The algorithm to calculate absorbed dose is as follows: 

∗ ܴܦ ൌ ܦ

ܣܵ

1ܨܥ ∗ ܨܣ ∗ ܨܲ ∗ ௜௔ܨ∗ܨ∗ ܹܤ

 

where: 

 D = Dermal dose (mg/kg-day); 
Page 38 of 42 

 DR = Deposited residue (mg/cm2

); 

 SA/BW = Surface area / Body Weight Ratio (cm2

/kg); 

 F = Fraction of body that contacts residue; 

 CF1 = Conversion factor (mg/g); 

 AF = Absorption factor; 

 Fai = fraction of ai available for transfer from treated mattress; and 

 PF = Protection factor to account for the presence of a single layer of 

 fabric (e.g. bed sheet) between the treated material and individual. 

Table A-X: Indoor Environments (mattresses) – Inputs for Residential Post-application Dermal Exposure 

Algorithm 

Notation 

Exposure Factor 

(units) Point Estimate(s) 

DR Deposited residue 

(g/cm2) Based on default residue values 

SA/BW 

Surface area / Body Weight 

Ratio 

(cm2/kg) 

Adult 280 

Children 1 < 2 

years old 640 

F Fraction of body that contacts residue 0.5 

Fai Fraction of DR available for transfer 0.06 

PF Protection Factor 0.5 

Post-application Hand-to-Mouth Exposure Algorithm 

Exposure from hand-to-mouth activity is calculated as follows (based on algorithm utilized in 

SHEDS-Multimedia):

ܧ ൌ ቈܪܴ 	∗ ሺܨெ ∗ 	 ܵܣுሻ ∗	 ሺܧܶ ∗ ܰ_ܴ݁݌݈݁݊ሻ ∗ ቆ1 െ ሺ1 െ ܵܧሻ

ி௥௘௤_ு௧ெ

ே_ோ௘௣௟௘௡ ቇ቉

 

where: 

E = exposure (mg/day); 

HR = hand residue loading (mg/cm2

); 

FM = fraction hand surface area mouthed / event (fraction/event); 

ET = exposure time (hr/day); 

SAH = surface area of one hand (cm2); 

N_Replen = number of replenishment intervals per hour (intervals/hour); 

SE = saliva extraction factor (i.e., mouthing removal efficiency); and 

Freq_HtM = number of hand-to-mouth contacts events per hour (events/hour). 

and 

ൌ ܴܪ

ܧܦ ∗ ௗ௦௛௔௡ܽ݅ܨ

2 ∗ ுܣܵ
Page 39 of 42 

where: 

 HR = hand residue loading (mg/cm2

); 

 Faihands = fraction ai on hands compared to total surface residue from jazzercise 

study (unitless); 

 DE = dermal exposure (mg); and 

SAH = typical surface area of one hand (cm2). 

and 

Dose, normalized to body weight, is calculated as: 

ൌ ܦ

ܧ

ܹܤ

 

where: 

D = dose (mg/kg-day); 

E = exposure (mg/day); and 

BW = body weight (kg). 

Table A-X: Indoor Environments – Inputs for Residential Post-application Hand-to-Mouth Exposure 

Algorithm 

Notation 

Exposure Factor 

(units) Point Estimate(s) 

Faihands Fraction of ai on hands from jazzercise study 

(unitless) 0.15 

DE Dermal exposure calculated in Section 5.2.2 (mg) Calculated 

HR Residue available on the hands 

(mg/cm2) Calculated 

SAH Surface area of one hand (cm2) Children 1 < 2 years old 150 

AR Application rate 

(mass active ingredient per unit area) 11,350 

FM Fraction of hand mouthed per event 

(fraction/event) 0.13 

N_Replen Replenishment intervals per hour 

(intervals/hr) 4 

ET Exposure time 

(hours per day) 

Children 1 < 2 

years old 

Carpets 4 

Hard Surfaces 2 

SE Saliva extraction factor 

(fraction) 0.48 

Freq_HtM 

Hand-to-mouth events 

per hour 

(events/hr) 

Children 1 < 2 years old 20 

BW Body Weight 

(kg) Children 1 < 2 years old 11 
Page 40 of 42 

Post-application Object-to-Mouth Exposure Algorithm 

Exposure from object-to-mouth activity is calculated as follows (based on algorithm utilized in 

SHEDS-Multimedia):

ܧ ൌ ܱܴ ∗ ܨܥ1 	∗ ܵܯܣை ∗ 	 ሺܧܶ ∗ ܰ_ܴ݁݌݈݁݊ሻ ∗ ቆ1 െ ሺ1 െ ܵܧሻ

ி௥௘௤_ை௧ெ

ே_ோ௘௣௟௘௡ ቇ

where: 

E = exposure (mg/day); 

OR = chemical residue loading on an object (g/cm2

); 

CF1 = weight unit conversion factor (0.001 mg/g); 

SAMO = area of the object surface that is mouthed (cm2

/event); 

ET = exposure time (hr/day); 

N_Replen = number of replenishment intervals per hour (intervals/hour); 

SE = saliva extraction factor (i.e., mouthing removal efficiency); and 

Freq_OtM = number of object-to-mouth contact events per hour (events/hour). 

and 

ைܨ ∗ ܴ݌݁ܦ ൌ ܱܴ

 

where: 

 

OR = chemical residue loading on the object (μg/cm2); 

 DepR = deposited residue (μg/cm2

); and 

 FO = fraction of residue transferred to an object (unitless). 

and 

Oral dose, normalized to body weight, is calculated as: 

ൌ ܦ

ܧ

ܹܤ

 

where: 

 

D = dose (mg/kg-day); 

 E = exposure (mg/day); and 

 BW = body weight (kg). 
Page 41 of 42 

Table A-X: Indoor Environments – Inputs for Residential Post-application Object-to-Mouth Exposure 

Algorithm 

Notation 

Exposure Factor 

(units) Point Estimate(s) 

AR Application rate 

(mass active ingredient per unit area) input 

FO Fraction of residue 

transferred to an object 

Carpets 0.06a

Hard surfaces 0.08a

SAMO Surface area of object mouthed 

(cm2/event) 10 

N_Replen Replenishment intervals per hour 

(intervals/hour) 4 

SEO Saliva extraction factor 0.48 

ET Exposure Time 

(hours per day) 

Children 1 < 

2 years old 

Carpets 4 

Hard Surfaces 2 

Freq_OtM 

Object-to-mouth events 

per hour 

(events/hour) 

Children 1 < 2 years old 14 

BW Body Weight 

(kg) Children 1 < 2 years old 11 

 
Page 42 of 42 

Appendix B. Registered Chlorfenapyr End Use Products 

Table B.1. Registered Clorfenapyr End Use Products. 

EPA Reg. No. Formulation 

Type 

Product Label Name Company 

241-366 Chlorfenapyr Technical BASF Corporation 

241-374 EC Pylon® Miticide-Insecticide BASF Corporation 

241-392 EC Phantom Termiticide Insecticide BASF Corporation 

499-544 PRL TC-307 Whitmire Micro-Gen Research 

Laboratories, Inc 

499-548 PRL TC-314 Whitmire Micro-Gen Research 

Laboratories, Inc 

499-556 PRL TC-326 Whitmire Micro-Gen Research 

Laboratories, Inc 

7969-285 PRL Prescription Treatment® Brand 

Phantom® Pressurized Insecticide BASF Corporation