UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

MEMORANDUM 

DATE: 

SUBJECT: 

December 29,2014 

Cblorpyrifos: Updated Occupational and Residential Exposure Assessment for 

Registration Review 

PC Code: 059101 

Petition No.: NA 

TXRNo.: NA 

DP Barcode: D424484 

Registration Nos.: NA 

Regulatory Action: Registration Review 

Risk Assessment Type: Single 

Chemical Aggregate 

MRIDNo.: NA CAS No.: 2921-88-2 

FROM: Wade Britton, MPH, Industrial Hygienist 

Risk Assessment Branch V (RABV) 

Health Effects Division (HED; 7509P) 

Office of Pesticide Programs 

THROUGH: Michael Metzger, Chief 

TO: 

RABV and RABVII/HED (7509P) 

And 

·-L_ . Kelly O'Rourke, ExpoSAC Reviewer fjl''- Lata Venkateshwara, ExpoSAC Reviewer 

Exposure Science Advisory Committee (ExpoSAC)/ HED 

Kevin Costello, Branch Chief 

Joel Wolf, Chemical Review Manager 

Risk Management and Implementation Branch II (RMIBII) 

Pesticide Re-evaluation Division (PRD; 7508P) 

Office of Pesticide Programs 
Page 2 of 227
Page 3 of 227

The purpose of this memorandum is to update the previous assessment completed June 2011, 

Chlorpyrifos: Occupational and Residential Exposure Assessment (W. Britton, D388165). This 

document reflects the following changes: use of the physiologically based pharmacokinetic and 

pharmacodynamic (PBPK-PD) model submitted by DowAgroSciences to predict the potential risks from 

chlorpyrifos exposures; refinement of use patterns based on a master use summary document developed 

for chlorpyrifos in cooperation with chlorpyrifos registrants (Appendix A); consideration of an updated 

hazard characterization based on the use of the PBPK-PD model; and updates to applicable EPA exposure 

assessment policies.

1

 

Note: This memorandum was reviewed by the Exposure Science Advisory Committee (ExpoSAC) on 

12/11/2014.

 

1 http://www.epa.gov/pesticides/science/handler-exposure-data.html, http://www.epa.gov/pesticides/science/postapp-exposure-data.html, and http://www.epa.gov/pesticides/science/residential-exposure-sop.html
Page 4 of 227

Table of Contents

1.0 Executive Summary............................................................................................................. 6

2.0 Risk Assessment Conclusions and Recommendations...................................................... 12

2.1 Summary of Risk Estimates........................................................................................... 12

2.2 Data Deficiencies and Requirements ............................................................................. 12

3.0 Hazard Characterization..................................................................................................... 13

4.0 Use Profile ......................................................................................................................... 16

5.0 Residential Exposure and Risk Estimates.......................................................................... 17

5.1 Residential Handler Exposure/Risk Estimates............................................................... 18

5.2 Residential Post-application Exposure/Risk Estimates.................................................. 18

5.3 Residential Risk Estimates and Recommendations for Aggregate Assessment ............ 24

5.4 Residential Bystander Post-Application Inhalation Exposure ....................................... 25

5.5 Residential Dose Reconstruction for the Columbia Cohort........................................... 27

6.0 Occupational Exposure and Risk Estimates ...................................................................... 30

6.1 Occupational Handler Exposure/Risk Estimates............................................................ 30

6.2 Commercial Seed Treatment.......................................................................................... 36

6.3 Occupational Post-application Exposure/Risk Estimates .............................................. 37

6.3.1 Occupational Post-application Inhalation Exposure/Risk Estimates.......................... 37

6.3.2 Occupational Post-application Dermal Exposure/Risk Estimates.............................. 38

6.4 Occupational Post-application Dermal Exposure/Risk Estimates: Chlorpyrifos Oxon.... 40

Appendix A: Chlorpyrifos Master Label Use Document ............................................................ 42

Appendix B: Residential Post-Application Dermal Steady State Exposure and Risk Estimates 

from Golfing - Post-application Dermal Algorithm ..................................................................... 88

Appendix C: Residential Post-application Dermal, Inhalation, and Hand-to-Mouth Exposures 

and Risks from Chlorpyrifos Mosquitocide Application - 2012 Residential SOP Algorithms; Use 

of Well Mixed Box Model; AgDisp (V8.2.6) Inputs.................................................................... 92

Appendix D. Summaries of Adult and Children 1 to < 2 Years Old Spray Drift Risk Estimates 

and Buffers for Chlorpyrifos......................................................................................................... 99

Appendix E: Detailed Background Information on Columbia Cohort Dose Reconstruction.... 118

Appendix F: Summary of Occupational Handler Risk Estimates ............................................. 132

Appendix G: Dermal and Inhalation Unit Exposures Use for Chlorpyrifos Occupational Handler 

Assessment.................................................................................................................................. 161

Appendix H: Summary of Chlorpyrifos Seed Treatment and Secondary Handler Exposure and 

Risks............................................................................................................................................ 167
Page 5 of 227

Appendix I: Occupational Post-application Exposure Data Summaries ................................... 179

Appendix J: Summary of Occupational Post-Application Risks............................................... 197
Page 6 of 227

1.0 Executive Summary

Chlorpyrifos (0,0-diethyl-0-3,5,6-trichloro-2-pyridyl phosphorothioate) is a broad-spectrum, 

organophosphate (OP) insecticide that was first registered in 1965 to control foliar- and soil-borne insect 

pests on a variety of food crops (including fruit and nut trees, many types of fruits and vegetables, and 

grain crops) and feed crops. Currently registered uses of chlorpyrifos result in the potential for 

occupational and residential exposures. Chlorpyrifos is formulated as a granular, microencapsulated 

liquid, soluble concentrate liquid, water dispersible granular in water soluble packets (WSP), and as 

wettable powder packaged in WSP. It is also included in paints, cattle ear tags and single use insect bait 

stations. A wide variety of mixing and application techniques have been identified for chlorpyrifos 

associated with its agricultural use such as aerial and tractor-drawn equipment, open and closed 

mixing/loading, and applications via hand held equipment. Applications of chlorpyrifos also include soil 

incorporated/directed uses, drench/dip, and seed treatments. In 2001, all chlorpyrifos residential uses 

were voluntarily cancelled except for ant and roach baits in child-resistant packaging. However, uses 

remain for that could result in non-dietary exposure in the general population including a public health 

mosquito adulticide for aerial and ground-based fogger and for golf course turf applications. 

In addition to including currently labeled exposure scenarios, a separate assessment was conducted to 

consider a retrospective dose reconstruction of the exposures which could have potentially occurred as a 

result of previous chlorpyrifos use in indoor residential environments (e.g., broadcast, aerosol and crack 

and crevice sprays). This is an important element of the interpretation of the results for the Columbia 

University cohort which is discussed in detail in the associated risk assessment document and in the 2012 

FIFRA SAP.

2

Exposure Data

It is agency policy to use the best available data to assess exposure. Chemical-specific dislodgeable foliar 

residue (DFR) studies were used for the assessment of occupational post-application exposure to 

chlorpyrifos including: emulsifiable concentrate formulations on sugarbeets, pecans, citrus, sweet corn, 

cotton, and turf; wettable powder formulations on almonds, apples, pecans, cauliflower, tomato and turf; 

granular formulations on sweet corn and turf; a total release aerosol formulation on ornamentals; and a 

microencapsulated liquid formulation on ornamentals.

Several sources of generic data were used in this assessment as surrogate 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 (ORETF) database; the Agricultural 

Reentry Task Force (ARTF) database; ExpoSAC Policy 14 [Standard Operating Procedures (SOPs) for 

Seed Treatment]; HED’s 2012 Residential SOPs for Residential Pesticide Exposure Assessment: 

Lawns/Turf, Outdoor Fogging/Misting Systems, registrant-submitted exposure monitoring studies MRIDs

44180401, 44301301, 44793301, 44829601, 42974501, 43062701, 44748101, 44748102, 46722701, and 

46722702, and published literature studies. Some of these data are proprietary, and subject to the data 

protection provisions of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). 

Hazard

The hazard assessment for chlorpyrifos has undergone significant change since the 2011 preliminary 

human health risk assessment. While cholinesterase inhibition remains the endpoint of concern for 

chlorpyrifos, how it has been considered has been altered based on the use of the PBPK-PD model. In 

typical risk assessments, points of departure (PoDs) are derived from laboratory animal studies, and inter-

 

2 http://www.epa.gov/scipoly/sap/meetings/2012/041012meeting.html
Page 7 of 227

and intra-species extrapolation is accomplished by use of 10X factors. In the case of chlorpyrifos and the 

oxon, the PBPK-PD model provides the opportunity to use a data-derived approach (USEPA, 2014). 

Specifically, the PBPK-PD model accounts for PK and PD characteristics to derive age, duration, and 

route-specific human equivalent doses or concentrations, depending on the route of exposure, which serve 

as the Points of Departure (PODs) for risk assessment purposes. Consistent with EPA’s cholinesterase 

policy, acetyl cholinesterase (AChE) inhibition at a level of 10% is considered an adverse effect which is 

used as the threshold of regulation. The PBPK-PD model was used to define what dose level results in 

10% red blood cell (RBC) AChE inhibition following 21 sequential days of exposure for a variety of 

occupational and residential scenarios and lifestages. Once defined, margins of exposure (MOEs) were 

calculated using typical exposure assessment methods which use these scenario- and lifestage-specific 

PoDs and direct comparison to applicable exposures. 

Use of the PBPK-PD model also impacts how uncertainty factors are defined for risk assessment; a total 

uncertainty factor of 40X was applied [1X for interspecies extrapolation, 4X for intraspecies variation, 

10X FQPA safety factor] for all populations assessed but adults (females). For adults (females), a total 

uncertainty factor of 100X was applied [1X for interspecies extrapolation, 10X for intraspecies variation, 

10X FQPA safety factor]. Typically, the agency uses animal studies for selection of PoDs and, as such, 

retains a 10X interspecies factor for extrapolation of the animal data to assess human health. However, 

with use of the PBPK-PD model which accounts for the pharmacokinetic and pharmacodynamic 

differences between animals and humans to derive PoDs, it is appropriate to reduce the interspecies factor 

to 1X. 

For all populations but women who may be pregnant, a 4X uncertainty factor has been retained for 

variation within in the human population. Typically, the agency retains a 10X factor to account for this 

variation. However, for this assessment EPA’s Data-Derived Extrapolation Factor (DDEF) guidance 

(USEPA, 2014), in conjunction with the PBPK-PD model, was used to calculate a DDEF intra-species 

extrapolation. In this approach, administered doses leading to the response level of interest (10% change 

in RBC AChE inhibition) are compared between a measure of average response and response at the tail of 

the distribution representing sensitive individuals. Based on the 99th percentile of the distributions, the 

DDEF for intra-species extrapolation is 4X for chlorpyrifos and 5X for the oxon (Dow, 2014b). For this 

revised risk assessment, the 99th percentile is being used to account for variation of sensitivity (i.e., the 

intra-species factor used in the risk assessment is 4X for chlorpyrifos and 5X for the oxon for all groups 

except women who are pregnant or may become pregnant for whom the 10X intra-species factor was 

retained).

While the current PBPK-PD model accounts for age-related growth from infancy to adulthood by using 

polynomial equations to describe tissue volumes and blood flows as a function of age, the model does not 

include any descriptions on physiological, anatomical and biochemical changes associated with 

pregnancy. Due to the uncertainty in extrapolating the current model predictions among women of child 

bearing age, the agency is applying the standard 10X intra-species extrapolation factor for women of 

childbearing age. For all other relevant populations, the agency has reliable data to reduce the standard 

10x intra-species factor.

For all populations assessed including infants, children, youths, and women of childbearing age, the 

FQPA 10X safety factor is retained. The 10X FQPA safety factor was retained based on the conclusion 

that, given the totality of evidence, chlorpyrifos likely played a role in the neurodevelopmental outcomes 

reported by the Columbia University investigators but uncertainties such as the lack of an established 

MOA/AOP for neurodevelopmental effects and the exposure to multiple AChE-inhibiting pesticides 

precludes definitive causal inference. However, there is sufficient uncertainty in the human doseresponse relationship for neurodevelopmental effects which prevents the agency from reducing or 
Page 8 of 227

removing the statutory 10X FQPA Safety Factor.

3

 

Like other OPs, chlorpyrifos exhibits a phenomenon known as steady state AChE inhibition. After 

repeated dosing at the same dose level, the degree of inhibition comes into equilibrium with the 

production of new, uninhibited enzyme. At this point, the amount of AChE inhibition at a given dose 

remains consistent across duration. In general, OPs reach steady state within 2-3 weeks but this can vary 

among OPs. Thus, for most of the human health risk assessments for the OPs, the agency is focusing on 

the critical durations range from a single day up to 21 days (i.e., the approximate time to reach steady 

state for most OPs). 

Residential Handler Exposure and Risk

Based upon review of all chlorpyrifos registered uses, only the roach bait products can be applied by a 

homeowner in a residential setting; however, a quantitative exposure/risk assessment for application of 

the roach bait products was not conducted because the potential for these types of handler exposures are

negligible. With roach bait stations the active ingredient is contained within the bait station, therefore 

limiting contact with the active ingredient in the product. 

Residential Post-application Exposure and Risk

Chlorpyrifos can be used in areas frequented by the general population including ant mounds, golf 

courses, and as an aerial or ground-based mosquito adulticide applied by a public agency made in 

residential areas. As a result, individuals could be exposed by entering these areas if they have been 

previously treated. Post-application exposure from ant mound treatments, which are applied by 

professional only, was not quantitatively assessed because contact with the mound is not anticipated. 

The assessment of steady state golfer post-application exposures (dermal only) to chlorpyrifos treated turf 

for the lifestages adults, children 6 to < 11 years old, and youths 11 to < 16 years old, results in no risks of 

concern (i.e., children 6 to < 11 and youth 11 to < 16 years old, MOEs are ≥ 40; adults, MOEs are ≥ 100). 

For the assessment of post-application exposures from public health mosquitocide applications, no 

combined risks of concern were identified for adults (dermal and inhalation) and children 1 to < 2 years 

old (dermal, incidental oral, and inhalation).

Residential Bystander Post-Application Inhalation Exposure

In the 2011 occupational and residential exposure assessment the potential risks to bystanders from spray 

drift and exposure from volatilization were identified as possible concerns. The potential risks from spray 

drift and the impact of potential risk reduction measures were assessed in July 2012.4 To increase 

protection for children and other bystanders, chlorpyrifos technical registrants voluntarily agreed to lower 

application rates and to other spray drift mitigation measures.5 As of December 2012, spray drift 

mitigation measures and use restrictions appear on all chlorpyrifos agricultural product labels. Because 

the use of the PBPK-PD model impacts spray drift risk estimates, an updated assessment was conducted. 

 

3 The decision on the FQPA safety factor is described in greater detail in the 2014 Chlorpyrifos Final Human Health 

Risk Assessment, D424485. Please also refer to this document regarding how the PBPK-PD model was considered 

and implemented.

4

J. Dawson, W. Britton, R. Bohaty, N. Mallampalli, and A. Grube. Chlorpyrifos: Evaluation of the Potential Risks 

from Spray Drift and the Impact of Potential Risk Reduction Measures. 7/13/12. U.S. EPA Office of Chemical 

Safety and Pollution Prevention. D399483, D399485.

5 R. Keigwin. Spray Drift Mitigation Decision for Chlorpyrifos (059101). 7/2012. U.S. EPA Office of Chemical 

Safety and Pollution Prevention. EPA-HQ-OPP-2008-0850-0103.
Page 9 of 227

The resulting buffer distances (feet) necessary to reach the level of concern for adults and children 1 to < 

2 years old (i.e., adults, MOEs are ≥ 100; children 1 to < 2 years old, MOEs are ≥ 40) with use of certain 

application rates, nozzle droplet types, and application methods range from 0 to 25 feet and are less than 

those previously predicted. 

In January 2013, a preliminary assessment of the potential risks from volatilization was conducted.

6

 The 

assessment evaluated the potential risks to bystanders, or those who live and/or work in proximity to 

treated fields, from inhalation exposure to vapor phase chlorpyrifos and chlorpyrifos-oxon emitted from 

fields following application of chlorpyrifos. The results of the January 2013 assessment indicated that 

offsite concentrations of chlorpyrifos and chlorpyrifos-oxon may exceed the target concentration based on 

the toxicological endpoints used at that time.7

Following the release of the preliminary volatilization assessment, Dow AgroSciences LLC conducted 

two, high quality nose-only vapor phase inhalation studies for both chlorpyrifos and chlorpyrifos-oxon.8 

These data sought to address the uncertainty of using an aerosol based chlorpyrifos toxicity study, as 

was done in the preliminary assessment, to assess the potential risks from field volatization. 

These toxicity studies indicate there is no hazard when exposed to chlorpyrifos or its oxon in its vapor 

phase since at saturated concentrations no statistically significant inhibition of AChE activity was 

measured in RBC, plasma, lung, or brain at any time after the six-hour exposure period in either study. 

Because these new studies demonstrated that no toxicity occurred even at the saturation concentration,

which is the highest physically achievable concentration, then there is no risk potential, as risk is a 

function of both exposure and hazard. By extension, if there is no risk due to exposure to chlorpyrifos or 

chlorpyrifos oxon, only a qualitative risk assessment was completed for volatilization. In June 2014, the 

January 2013 volatilization assessment was revised to reflect these findings.9

Dose Reconstruction for Potential Exposures in Columbia University Cohort

In an effort to better understand the potential exposure patterns in the Columbia University study cohort 

and their influence on the health outcomes identified in the research, a separate dose reconstruction 

residential exposure analysis was conducted for pregnant women and young children (i.e., 1 to < 2 years 

old). The exposure patterns and potential health outcomes could not be adequately defined for EPA’s 

 

6 R. Bohaty, C. Peck, A. Lowit, W. Britton, N. Mallampalli, A. Grube. Chlorpyrifos: Preliminary Evaluation of the 

Potential Risks from Volatilization. 1/31/13. U.S. EPA Office of Chemical Safety and Pollution Prevention. 

D399484, D400781. 

7 EPA MRID# 48139303: Acute Inhalation Exposure of Adult Crl:CD(SD) Rates to Particulate Chlorpyrifos 

Aerosols: Kinetics of Concentration-Dependent Cholinesterase (ACHE) Inhibition in Red Blood Cells, Plasma, 

Brain and Lung; Authors: J. A. Hotchkiss, S. M. Krieger, K. A. Brzak, and D. L. Rick; Sponsor: Dow AgroSciences 

LLC.

8 W. Irwin. Review of Nose-Only Inhalation of Chlorpyrifos Vapor: Limited Toxicokinetics and Determination of 

Time-Dependent Effects on Plasma, Red Blood Cell, Brain and Lung Cholinesterase Activity in Femal CD(SD): Crl 

Rats. U.S. EPA Office of Chemical Safety and Pollution Prevention. 6/25/14. D411959. TXR# 0056694. EPA 

MRID# 49119501.

W. Irwin. Review of Nose-Only Inhalation of Chlorpyrifos-Oxon Vapor: Limited Toxicokinetics and Determination 

of Time-Dependent Effects on Plasma, Red Blood Cell, Brain, and Lung Cholinesterase Activity in Female 

CD(SD):Crl Rats. U.S. EPA Office of Chemical Safety and Pollution Prevention. 6/25/14. D415447. TXR# 

0056869. EPA MRID# 49210101.

9 W. Britton. W. Irwin. J. Dawson. A. Lowit. E. Mendez. Chlorpyrifos: Reevaluation of the Potential Risks from 

Volatilization in Consideration of Chlorpyrifos Parent and Oxon Vapor Inhalation Toxicity Studies. 6/25/2014. U.S. 

EPA Office of Chemical Safety and Pollution Prevention. D417105.
Page 10 of 227

purposes based on the available information presented in the Columbia University research. In order to 

further evaluate the chlorpyrifos exposure potential within the Columbia study cohort, the products likely 

used during the time of study conduct served as the basis for the analysis. EPA’s 2012 Standard 

Operating Procedures for Residential Pesticide Exposure Assessment10 were used as the basis of this 

exercise to estimate exposures. The resulting exposures were then evaluated using the PBPK-PD model 

to quantify peak RBC AChE inhibition for the Columbia study cohort.

Resulting peak RBC AChE inhibition for pregnant women was 0.45%. For children 1 to < 2 years old, 

peak RBC AChE inhibition was 2.7%. Overall, the dose reconstruction results support a conclusion that 

indoor application of chlorpyrifos, when used as allowed prior to cancellation from the residential 

marketplace in 2000, likely would not have resulted in RBC AChE inhibition greater than 10% in 

pregnant women or young children. These findings are pertinent to the weight-of-evidence discussion for 

the FQPA 10X Safety Factor.

Occupational Handler Exposure and Risk

Steady state exposure and risks were calculated for occupational handlers of chlorpyrifos for a variety of 

exposure scenarios at differing levels of personal protection and with engineering controls. PBPK-PD 

modeled PoDs (dermal and inhalation) specific for occupational exposure scenario assessment were used 

to estimate handler risks. For the chlorpyrifos occupational risk assessment, the residue of concern is the 

parent chlorpyrifos. Exposure to the oxon is only an issue under very limited circumstances in 

greenhouses for postapplication workers. 

Current labels generally require that handlers use normal work clothing (i.e., long sleeved shirt and pants, 

shoes and socks) and coveralls, chemical resistant gloves, and dust/mist respirators. Also, some products 

are marketed in engineering controls such as WSPs. In order to determine what level of personal 

protection is required to alleviate risk concerns and to ascertain if label modifications are needed, steady 

state exposure and risk estimates were calculated for occupational handlers of chlorpyrifos for a variety of 

scenarios at differing levels of personal protection including engineering controls. 

Of the 285 total occupational handler exposure scenarios assessed, 132 are not of concern (i.e., MOEs are 

≥ 100) at the levels of personal protection (clothing or equipment) or engineering controls currently 

required by product labeling for these scenarios. Risks of concern for 27 additional exposure scenarios 

could potentially be mitigated if additional personal protective equipment or engineering controls are 

used. Risks of concern were estimated for 126 exposure scenarios and remain a concern regardless of the 

levels of personal protection and engineering controls considered. These risks could be mitigated using 

the highest level of personal protection available and by modification to other label requirements such as 

application rate or, in some cases, deleting certain types of application equipment.

Commercial Seed Treatment

Steady state exposure and risks were calculated for occupational handlers performing seed treatment 

activities in commercial settings and for occupational secondary handlers from planting chlorpyrifostreated seeds. Of the 68 exposure scenarios assessed, 36 resulted in risk estimates which were not of 

concern (i.e., MOEs are ≥ 100) at the level of personal protection currently required by product labels. 

Secondary handler (seed planter) scenarios were also evaluated and none are of concern when compared 

to current label personal protection requirements. For the remaining 32 seed treatment scenarios, MOEs 

were < 100 at all levels of personal protection considered and, therefore, are of potential concern. 

 

10 http://www.epa.gov/pesticides/science/USEPA-OPP-HED_Residential%20SOPs_Oct2012.pdf
Page 11 of 227

Occupational Post-application Exposure and Risk

Steady state occupational post-application exposures and risks were assessed for any crops where hand 

labor is anticipated following applications of chlorpyrifos. The assessment was completed using 7 

chlorpyrifos DFR studies. The studies encompass the use of five different formulations and twelve 

different crops. These data were used to evaluate post-application worker risks from all applicable crops 

and have been extrapolated to other groups based on the nature of the crop and application method. 

Chlorpyrifos parent compound is the residue of concern for occupational post-application exposures; 

however, it may be possible that the formation of the oxon is greater and its deactivation slower in 

greenhouses when compared to the outdoor environment. Occupational post-application assessments 

were performed for: 1) exposures to the parent compound chlorpyrifos in outdoor environments (uses 

other than greenhouse), 2) exposures to the parent chlorpyrifos (only) in greenhouses and 3) exposures to 

both the parent and the oxon metabolite in greenhouses.

Current labels require a Restricted Entry Interval (REI) of 24 hours from most crops and activities, but in 

some cases such as tree fruit, REIs are up to 5 days after application. All post-application worker risks 

have been updated in the current assessment. Results indicate that no REI increase is required for the 

majority of outdoor environment crops and commodities with a labeled REI (i.e., 43 of 55 total). 

However, for 12 crops, activities such as irrigation, hand harvesting, scouting, and thinning result in risks 

of concern up to as many as 10 days following application. For the assessment of post-application 

exposures to parent chlorpyrifos (only) from ornamental production in greenhouses, 4 formulations were 

assessed: emulsifiable concentrate, microencapsulated liquid, wettable powder in WSP, and total release 

fogger. An REI increase of up to 5 days may be needed to alleviate risks from with use of the 

emulsifiable concentrate, wettable powder in WSP, and total release fogger formulations. For the 

microencapsulated liquid formulation, the estimated REIs range from 0 to > 35 days after treatment (the 

completion of the monitoring period) dependent on the exposure activity considered.

Due to uncertainty regarding the formation of chlorpyrifos oxon in greenhouses, HED also estimated risks 

for reentry into treated greenhouses (all 4 formulations) for the parent chlorpyrifos plus chlorpyrifos oxon 

using a total toxic residue approach. The total toxic residue approach was conducted with use of 

chlorpyrifos DFR studies and an assumed daily fraction, 5%, of chlorpyrifos oxon. When the total toxic 

residue approach is used to evaluate risks from exposure to the oxon with use of the emulsifiable 

concentrate, wettable powder in WSP, and total release fogger formulations, results indicate that an REI 

increase up to 6 days may be needed to alleviate risk concerns. For the microencapsulated liquid 

formulation, REIs range from 3 to > 35 days after treatment (the completion of the monitoring period) 

dependent on the exposure activity considered.

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; 

ExpoSAC Policy 14 (SOPs for Seed Treatment); the 2012 Residential SOPs: Lawns/Turf, Outdoor 

Fogging/Misting Systems; registrant-submitted exposure monitoring studies MRIDs 44180401, 

44301301, 44793301, 44829601, 42974501, 43062701, 44748101, 44748102, 46722701, and 46722702; 

and published literature studies 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. 
Page 12 of 227

2.0 Risk Assessment Conclusions and Recommendations

2.1 Summary of Risk Estimates

Residential post-application exposures from golfing and from following public health mosquitocide 

applications are not of concern for all lifestages assessed (i.e., children 6 to < 11 and youth 11 to < 16 

years old, MOEs are ≥ 40; adults, MOEs are ≥ 100). 

For the assessment of residential bystander exposures from spray drift, the resulting buffer distances (feet) 

necessary to reach the level of concern for adults and children 1 to < 2 years old (i.e., adults, MOEs are ≥ 

100; children 1 to < 2 years old, MOEs are ≥ 40) with use of certain application rates, nozzle droplet 

types, and application methods range from 0 to 25 feet. 

Of the 285 total occupational handler exposure scenarios assessed, 132 are not of concern (i.e., MOEs are 

≥ 100) at the levels of personal protection (clothing or equipment) or engineering controls currently 

required by product labeling for these scenarios. Risks of concern for 27 additional exposure scenarios 

could potentially be mitigated if additional personal protective equipment or engineering controls are 

used. Risks of concern were estimated for 126 exposure scenarios and remain a concern regardless of the 

levels of personal protection and engineering controls considered. 

Of the 68 exposure scenarios assessed, 36 resulted in risk estimates which were not of concern (i.e., 

MOEs are ≥ 100) at the level of personal protection currently required by product labels. Secondary 

handler (seed planter) scenarios were also evaluated and none are of concern when compared to current 

label personal protection requirements. For the remaining 32 seed treatment scenarios, MOEs were < 100 

at all levels of personal protection considered and, therefore, are of potential concern. 

For the assessment of occupational post-application exposures, estimated risks indicate that no REI 

increase is required for the majority of outdoor environment crops and commodities with a labeled REI 

(i.e., 43 of 55 total). However, for 12 crops, activities such as irrigation, hand harvesting, scouting, and 

thinning result in risks of concern up to as many as 10 days following application. For the assessment of 

post-application exposures to parent chlorpyrifos (only) from ornamental production in greenhouses, 4 

formulations were assessed: emulsifiable concentrate, microencapsulated liquid, wettable powder in 

WSP, and total release fogger. An REI increase of up to 5 days may be needed to alleviate risks from 

with use of the emulsifiable concentrate, wettable powder in WSP, and total release fogger formulations. 

For the microencapsulated liquid formulation, the estimated REIs range from 0 to > 35 days after 

treatment (the completion of the monitoring period) dependent on the exposure activity considered.

Due to uncertainty regarding the formation of chlorpyrifos oxon in greenhouses, HED also estimated risks 

for reentry into treated greenhouses (all 4 formulations) for the parent chlorpyrifos plus chlorpyrifos oxon 

using a total toxic residue approach. The total toxic residue approach was conducted with use of 

chlorpyrifos DFR studies and an assumed daily fraction, 5%, of chlorpyrifos oxon. When the total toxic 

residue approach is used to evaluate risks from exposure to the oxon with use of the emulsifiable 

concentrate, wettable powder in WSP, and total release fogger formulations, results indicate that an REI 

increase up to 6 days may be needed to alleviate risk concerns. For the microencapsulated liquid 

formulation, REIs range from 3 to > 35 days after treatment (the completion of the monitoring period) 

dependent on the exposure activity considered.

2.2 Data Deficiencies and Requirements

HED has considered all data sources available for the assessment of occupational and residential risks. 
Page 13 of 227

No new data are required for chlorpyrifos; however, data gaps are identified for the evaluation of 

chlorpyrifos oxon. In the 2011 occupational and residential exposure assessment, additional studies were 

recommended to address uncertainties regarding the formation of chlorpyrifos oxon and its decay 

following applications in greenhouses. To date, no additional data have been submitted. 

In accordance with 40CFR158, the following data are required for all occupational or residential pesticide 

uses: 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 

post-application exposure to foliage; and turf transferable residue (TTR) data are required for all 

occupational (e.g., sod farms, golf courses, parks, and recreational areas) or residential turf uses that could 

result in post-application exposure to turf. No DFR and TTR data deficiencies have been identified for 

chlorpyrifos based on the availability of all required studies. 

3.0 Hazard Characterization

Chlorpyrifos is a member of the OP class of pesticides. Like other OPs, the initiating event in the adverse 

outcome pathway (AOP)/ mode of action (MOA) involves inhibition of the enzyme AChE via 

phosphorylation of the serine residue at the active site of the enzyme. This inhibition leads to 

accumulation of acetylcholine and ultimately to neurotoxicity in the central and/or peripheral nervous 

system (see Figure 1). For chlorpyrifos, AChE inhibition is the most sensitive endpoint in the toxicology 

database in multiple species, durations, lifestages, and routes of exposure. 

Figure 1. Adverse outcome pathway for OPs

Like other OPs, chlorpyrifos exhibits a phenomenon known as steady state AChE inhibition. After 

repeated dosing at the same dose level, the degree of inhibition comes into equilibrium with the 

production of new, uninhibited enzyme. At this point, the amount of AChE inhibition at a given dose 

remains consistent across duration. In general, OPs reach steady state within 2-3 weeks but this can vary 

among OPs. Thus, for most OPs, the agency believes that the critical exposure durations range from a 

single day up to 21 days (i.e., the approximate time to reach steady state for most OPs). 

 

The hazard assessment for chlorpyrifos has undergone significant change since the 2011 preliminary 

human health risk assessment. While RBC AChE inhibition remains the endpoint of concern for 

chlorpyrifos, how it has been considered has been altered based on the use of the PBPK-PD model. In 

typical risk assessments, points of departure (PoDs) are derived directly from laboratory animal studies, 

and inter- and intra-species extrapolation /variation is accounted for by use of 10X factors. In the case of 

chlorpyrifos and the oxon, the PBPK-PD model provides the opportunity to use a data-derived approach 

(USEPA, 2014). Specifically, the PBPK-PD model accounts for PK and PD characteristics to derive age, 

duration, and route specific human equivalent doses (Table 3.0 below). Consistent with risk assessments 

for other AChE-inhibiting chemicals, AChE inhibition at a level of 10% is considered an adverse effect. 

The PBPK-PD model was run to determine the exposure level (dose), or PoD, resulting in 10% RBC 

AChE inhibition following 21-day exposures for a variety of occupational and residential exposure 

scenarios and lifestages. Once defined, a margin of exposure (MOE) was calculated with use this 

scenario- and lifestage-specific PoD by comparison to exposure estimates (doses) quantified with use of 

standard occupational and residential exposure assessment methodologies. 

Target 

Tissue Dose

Phosphorylation 

of the Active Site 

of AChE

Neurotoxicity Accumulation of 

Acetylcholine
Page 14 of 227

Separate PoDs have been calculated for occupational and residential exposures by varying inputs on types 

of exposures and populations exposed. Specifically, the following characteristics have been evaluated: 

exposure duration; exposure route; body weights which vary by lifestage; exposure duration (hours per 

day, days per week); and dermal surface area exposed. The following summarizes the inputs used for 

derivation of PBPK-PD modeled occupational and residential age, duration, and route specific PoDs:

 Exposure duration: 21-day (steady state);

 Exposure route: occupational, dermal and inhalation; residential, dermal, incidental oral, and 

inhalation;

 Body weights: children 1 to < 2 years old, 11 kg; children 6 to < 11 years old, 32 kg; youth 11 to < 16 

years old, 57 kg; adults (females), 69 kg. For adults when an endpoint is not sex-specific (i.e., the 

endpoints are based on developmental or fetal effects) a body weight of 80 kg is typically used in risk 

assessment; however, in this case, a female-specific body weight was used. While the endpoint of 

concern, RBC AChE inhibition, is not sex-specific, the female body weight was used due to concerns 

for pregnant women related to the application of the 10X FQPA safety factor based on findings in the 

Columbia University cohort and the related uncertainty;

 Exposure duration: occupational, 8 hours/day, 5 days/week; residential golfer, 4 hours/day, 7 

days/week; residential exposures following public health mosquitocide application, 1.5 hours/day 

(dermal and incidental oral exposures from turf), 1.0 hours/day (inhalation exposures), 7 days/week;

 Dermal surface area exposed: residential, 50% (t-shirt and shorts); occupational, 100% (even 

distribution across the entire body surface area); and

 a daily shower is assumed following occupational and residential exposures. 
Table 3.0. Points of Departure Calculated Using PBPK-PD Model Corresponding to 10% RBC AChE Inhibition

RA Type

Exposure Pathway

(all chlorpyrifos 

unless noted)

Infants < 1 yr old Children 

1 to < 2 years old

Children 

6 to < 11 years old

Children 

11 to < 16 years old

Females 

13 – 49 yrs old

Acute

Steady 

State

(21 day)

Acute

Steady 

State 

(21 day)

Acute

Steady 

State 

(21 day)

Acute

Steady 

State 

(21 day)

Acute

Steady 

State

(21 day)

Dietary

Drinking Water

(oxon conc, ppb)

1,183 217 3,004 548 7,700 1,358 4,988 878 5,285 932

Food (ug/kg/day) 600 103 581 99 530 90 475 80 467 78

Residential

(Golfers)

Dermal (ug/kg/day)

22,750 13,950 11,890

Residential

(Mosquitocide 

Application)

Dermal 

(ug/kg/day)

134,250 23,600

Oral 

(ug/kg/day)

101

Inhalation 

(concn. in air 

mg/m3)

2.37 6.15

Occupational 

Dermal 

(ug/kg/day)

3,630

Inhalation

(ug/kg/day)

138
Use of the PBPK-PD model also impacts how uncertainty factors are defined for risk assessment; a total 

uncertainty factor of 40X was applied [1X for interspecies extrapolation, 4X for intraspecies variation, 

10X FQPA safety factor] for all populations assessed but adults (females). For adults (females), a total 

uncertainty factor of 100X was applied [1X for interspecies extrapolation, 10X for intraspecies variation, 

10X FQPA safety factor]. Typically, the agency uses animal studies for selection of PoDs and, as such, 

retains a 10X interspecies factor for extrapolation of the animal data to assess human health. However, 

with use of the PBPK-PD model which accounts for the pharmacokinetic and pharmacodynamic 

differences between animals and humans to derive PoDs, it is appropriate to reduce the interspecies factor 

to 1X. 

For all populations but women who may be pregnant, a 4X uncertainty factor has been retained for 

variation within in the human population. Typically, the agency retains a 10X factor to account for this 

variation. However, for this assessment EPA’s Data-Derived Extrapolation Factor (DDEF) guidance 

(USEPA, 2014), in conjunction with the PBPK-PD model, was used to calculate a DDEF intra-species 

extrapolation. In this approach, administered doses leading to the response level of interest (10% change 

in RBC AChE inhibition) are compared between a measure of average response and response at the tail of 

the distribution representing sensitive individuals. Based on the 99th percentile of the distributions, the 

DDEF for intra-species extrapolation is 4X for chlorpyrifos and 5X for the oxon (Dow, 2014b). For this 

revised risk assessment, the 99th percentile is being used to account for variation of sensitivity (i.e., the 

intra-species factor used in the risk assessment is 4X for chlorpyrifos and 5X for the oxon for all groups 

except women who are pregnant or may become pregnant for whom the 10X intra-species factor was 

retained).

While the current PBPK-PD model accounts for age-related growth from infancy to adulthood by using 

polynomial equations to describe tissue volumes and blood flows as a function of age, the model does not 

include any descriptions on physiological, anatomical and biochemical changes associated with 

pregnancy. Due to the uncertainty in extrapolating the current model predictions among women of child 

bearing age, the agency is applying the standard 10X intra-species extrapolation factor for women of 

childbearing age. For all other relevant populations, the agency has reliable data to reduce the standard 

10x intra-species factor.

For all populations assessed including infants, children, youths, and women of childbearing age, the 

FQPA 10X safety factor is retained. The 10X FQPA safety factor was retained based on the conclusion 

that, given the totality of evidence, chlorpyrifos likely played a role in the neurodevelopmental outcomes 

reported by the Columbia University investigators but uncertainties such as the lack of an established 

MOA/AOP for neurodevelopmental effects and the exposure to multiple AChE-inhibiting pesticides 

precludes definitive causal inference. However, there is sufficient uncertainty in the human doseresponse relationship for neurodevelopmental effects which prevents the agency from reducing or 

removing the statutory 10X FQPA Safety Factor.

11

 

4.0 Use Profile 

Chlorpyrifos is a broad-spectrum, OP insecticide that was first registered in 1965 to control foliar- and 

soil-borne insect pests on a variety of food and feed crops. Targeted pests include aphids, cockroaches, 

cutworms, fleas, grasshoppers, ticks, etc. Chlorpyrifos is manufactured as granular (G), 

microencapsulated liquid (ME), soluble concentrate/liquids (EC or LC), water dispersible granular

(WDG) in WSP and wettable powder (WP) packaged in WSP formulations, as well as impregnated 

 

11 The decision on the FQPA safety factor is described in greater detail in the 2014 Chlorpyrifos Final Human 

Health Risk Assessment, D424485. Please also refer to this document regarding how the PBPK-PD model was 

considered and implemented.
Page 17 of 227

paints, cattle ear tags, insect bait stations and total release foggers. Registered use sites include the 

following uses: food crops, including fruit and nut trees, many types of fruits and vegetables, and grain 

crops; and non-food crops such as forage, golf course turf, industrial sites, greenhouse and nursery 

production, sod farms, and wood products. Public health uses include aerial and ground-based fogger 

treatments to control mosquitoes. There are a wide range of application rates. 

In order to seek clarification of chlorpyrifos usage, the agency collaborated with chlorpyrifos registrants 

to compile a master use summary document reflective of the use profile of all active product labels. The 

document, among other information, presents all registered uses of chlorpyrifos and corresponding 

maximum single application rates, equipment types, re-entry intervals (REIs), etc. HED believes that the 

detailed information on application rates and use patterns presented in Appendix A will be implemented 

on all chlorpyrifos labels and is the basis of the occupational and residential risk assessment. If, for any 

reason, the final chlorpyrifos labels contained higher application rates, the actual risks posed by those 

products may exceed the risk estimated in this assessment.

5.0 Residential Exposure and Risk Estimates

The 2011 residential assessment has been updated to reflect the use of the PBPK-PD modeling approach 

and HED’s 2012 Residential SOPs for Residential Pesticide Exposure Assessment. In 1997, the 

registrant, Dow AgroSciences, voluntarily agreed to cancel chlorpyrifos registrations for indoor broadcast 

use and direct pet treatments, except pet collars. In December 2001, the majority of the remaining 

chlorpyrifos residential products, except for fully contained ant baits in child resistant packaging and 

limited public health uses, were subject to voluntary phase out/cancellation. Current chlorpyrifos 

homeowner uses include a granular ant mound use and roach bait in child-resistant packaging. 

Additionally, chlorpyrifos is labeled for public health aerial and ground-based fogger ULV mosquito

adulticide applications and for golf course turf applications. 

A residential assessment was conducted in 2011 due to the potential for post-application exposure from 

entering areas previously treated with chlorpyrifos. Post-application exposure is anticipated from playing 

golf on chlorpyrifos-treated courses and from exposures which can occur following aerial and groundbased ULV mosquito adulticide use. The potential for residential exposure from the roach bait product is 

negligible. Residential exposures from the ant mound use are also negligible since these products can 

only be applied professionally and direct exposure with treated ant mounds is not anticipated. 

In addition to the assessment of residential exposure, the potential for post-application exposures to 

residential bystanders who live on, work in, or frequent areas adjacent to treated fields from spray drift 

and volatilization were also considered previously in 2011. The potential risks from spray drift and the 

impact of potential risk reduction measures were assessed in a July 2012 memorandum. To increase 

protection for children and other bystanders, chlorpyrifos technical registrants voluntarily agreed to lower 

application rates and other spray drift mitigation measures. The spray drift risk assessment results have 

be updated herein because of the implications associated with the use of the PBPK-PD modeling 

approach. In January 2013, a preliminary assessment of the potential risks from volatilization was 

conducted. However, this assessment was revised following submission of two vapor phase inhalation 

toxicity studies which indicate no adverse effects occurred even at the saturation concentration for 

chlorpyrifos and chlorpyrifos oxon. 

This assessment also includes a retrospective dose reconstruction of the exposures which could have 

potentially occurred as a result of previous widespread chlorpyrifos uses in indoor residential 

environments.
Page 18 of 227

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.

Based upon review of all chlorpyrifos registered uses, only the roach bait products can be applied by a

homeowner in a residential setting but the application of roach bait products has not quantitatively 

assessed because these exposures are negligible. The roach bait product is designed such that the active 

ingredient is contained within a bait station which eliminates the potential for contact with the 

chlorpyrifos containing bait material. 

5.2 Residential Post-application Exposure/Risk Estimates

There is the potential for post-application exposures as a result of being in an environment that has been 

previously treated with chlorpyrifos. Chlorpyrifos can be used in areas frequented by the general 

population including golf courses and as an aerial and ground-based ULV mosquito adulticide 

applications made directly in residential areas. The 2011 document assessed these uses. Post-application 

exposure from residential ant mound treatment was assessed qualitatively as addressed above because 

negligible exposures are anticipated. 

The residential post-application exposure scenarios and application rates assessed in 2011 remain 

unchanged. However, the PBPK-PD model has been used for PoD derivation and the methods used to 

assess these exposure scenarios have changed and, as a result, post-application exposures have been 

updated. The updated post-application exposure assessment reflects the following changes including: 1) 

use of the 2012 Standard Operating Procedures for Residential Pesticide Exposure Assessment12, 2) use 

of the AgDISP model for estimation of airborne concentrations and residue dissipation following 

chlorpyrifos mosquito adulticide applications, 3) updated methodology for determining the airborne 

concentration of active ingredient following ground-based mosquito adulticide applications, and 4) use of 

updated body weights for all residential populations assessed. 

The lifestages selected for each post-application scenario are based on an analysis provided in the 2012 

Residential SOPs. 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 all who are potentially exposed.

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

following scenarios: 

Golf Course Use (EC and G formulations)

 Adult post-application dermal exposure from contact with treated turf while golfing. 

 Youth 11 to < 16 years old post-application dermal exposure from contact with treated turf while 

golfing.

 Children 6 to < 11 years old post-application dermal exposure from contact with treated turf 

while golfing.

 

12 http://www.epa.gov/pesticides/science/USEPA-OPP-HED_Residential%20SOPs_Oct2012.pdf
Page 19 of 227

Public Health Mosquito Adulticide Use (aerial and ground applications)

 Adult post-application dermal exposure from contact with turf following the deposition of 

chlorpyrifos residues from public health mosquito adulticide application.

 Adult post-application inhalation exposure from airborne chlorpyrifos following public health 

mosquito adulticide application.

 Children 1 to < 2 years old post-application dermal exposure from contact with turf following the 

deposition of chlorpyrifos residues from public health mosquito adulticide application.

 Children 1 to < 2 years old post-application incidental oral (hand-to-mouth) exposure from 

contact with turf following the deposition of chlorpyrifos residues from public health mosquito 

adulticide application.

 Children 1 to < 2 years old post-application incidental oral (object-to-mouth) exposure from 

contact with toys containing residues from turf following the deposition of chlorpyrifos residues 

from public health mosquito adulticide application.

 Children 1 to < 2 years old post-application inhalation exposure from airborne chlorpyrifos 

following public health mosquito adulticide application.

Residential Post-application Exposure Data and Assumptions

A series of assumptions and exposure factors served as the basis for completing the residential postapplication risk assessment. Each assumption and factor used for the assessment of exposures to golfers, 

and from public health mosquitocide applications can be found in Appendix B and C, respectively. 

Exposure Duration: Residential post-application exposures to chlorpyrifos are assumed to be steady state 

(i.e., 21 days or longer). 

The application of mosquitocide in residential areas may result in the potential for post-application 

inhalation exposures. The aerosolized particulate remaining following application is assumed to persist 

for no longer than one hour in proximity of the application source and, accordingly, would be most 

appropriately defined as acute in duration. However, this assessment assumes that post-application 

inhalation exposures are steady state which is a highly conservative approach given how infrequently 

mosquitocides are repeatedly applied to the same locations and how rapidly aerosols dissipate after these 

types of applications. The parameters used to define this exposure scenario in the PBPK-PD model 

conservatively reflect daily, repeated one hour exposures for 21 days. 

Body Weights: The body weights assumed for this assessment differ from those used in 2011

occupational and residential exposure assessment and are based on the recommendations of the 2012 

Residential SOPs. 

The standard body weights are as follows: youth 11 to < 16 years old, 57 kg; children 6 to < 11 years old, 

32 kg; and children 1 to < 2 years old, 11 kg. For adults when an endpoint is not sex-specific (i.e., the 

endpoints are based on developmental or fetal effects) a body weight of 80 kg is typically used in risk 

assessment. However, in this case, a female-specific body weight of 69 kg was used. While the endpoint 

of concern, RBC AChE inhibition, is not sex-specific, the female body weight was used due to concerns 

for pregnant women related to the application of the 10X FQPA safety factor based on findings in the 

Columbia University cohort and the related uncertainty.
Page 20 of 227

Golf Course Use 

Post-application exposures from golfing have been assessed using the 2012 Residential SOPs and with 

use of exposure data from a chemical-specific TTR study. The study was conducted with an emulsifiable 

concentrate, a granular, and a wettable powder formulation. Only the emulsifiable concentrate and 

granular data were used because there are no currently registered wettable powder formulations. The 

study was conducted in 3 states, California, Indiana and Mississippi, with use of the emulsifiable 

concentrate and wettable powder formulations. The granular formulation was used in California only. 

The liquid applications were made at a nominal application rate of 4 lb ai/A, and the granular applications 

were made at a nominal application rate of 2 lb ai/A. Exposure was estimated by normalizing Day 0 TTR 

measures from study application rates to the current maximum application rate allowable by the label. 

Single applications were made to the treatment plots using tractor mounted boom sprayers for the liquid 

applications and either a tractor mounted air spreader or tractor mounted spreader for the granular 

applications. Duplicate samples were collected using the California roller technique at the following 

intervals: one day prior to the application, just after the application (-2.5 hours after application), and days 

1, 2, 4, and 7 after application. Samples were analyzed for residues of chlorpyrifos. Chlorpyrifos oxon 

residues were not analyzed. The overall average concurrent recovery was 98% ±3%. The LOD and LOQ 

were reported as 0.001 μg/cm2and 0.003 μg/cm2respectively. The field study samples did not require 

correction for field fortification recovery since average field fortification recoveries (corrected for 

concurrent recovery), at each fortification level were greater than 90% at all sites. 

Average TTR values are provided below in Table 5.2.1. 

Table 5.2.1. Summary of Actual Average TTR Values on Turf After One Broadcast Foliar 

Application of Chlorpyrifos

Sampling 

Interval 

(Days)

Actual Average TTR (μg/cm2)

Dursban® Pro

(Emulsifiable Concentrate)

Dursban® 2.5G

(Granular)

Dursban® 1F

(Granular)

CA IN MS CA IN MS CA IN MS

After 1st (Only) Application

0 0.124 0.090 0.146 <LOQ <LOQ <LOQ 0.052 <LOQ <LOQ

1 0.039 0.011 0.009 <LOQ <LOQ <LOQ 0.02 <LOQ <LOQ

2 0.01 0.005 <LOQ <LOQ <LOQ <LOQ 0.011 0.003 0.01

4 0.004 <LOQ <LOQ <LOQ <LOQ <LOQ 0.004 0.003 <LOQ

7 <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ

Notes:

<LOQ reported when all samples at the reported location and time met that criteria. LOQ = 0.003 μg/cm2

Residues were corrected for concurrent recoveries.

Application rates were a nominal 4 lb ai/A for liquid applications (Dursban® Pro and Dursban® 50W ) and 2.0 lb ai/A for 

granular applications (Dursban® 2.5G and Dursban® 1F).

Public Health Mosquito Adulticide Use

The post-application exposure potential from public health mosquito adulticide applications has been 

considered for both ground based truck foggers and also from aerial applications. For assessment of the 

mosquito adulticide use, the algorithms and inputs presented in the 2012 Residential SOPs, Lawns/Turf 

section were used coupled with the available TTR data described above. The deposition of chlorpyrifos 

from these applications are not based on the application rate alone, but also using the AgDISP (v8.2.6)

model or empirical data to determine how much pesticide is deposited on residential lawns as a result of 

mosquito adulticide treatments at the maximum application rates for each. The TTR data are then used to 

determine the fraction of the total residue deposited following the mosquitocide application which can 

result in exposures to impacted individuals. Inhalation exposures are estimated using AgDrift for aerial 

applications, and a recently developed, Well Mixed Box Model approach based on the Residential SOPs 
Page 21 of 227

for outdoor foggers.

Ground-based Foggers

In the study conducted by Moore et al., [Downwind Drift and Deposition of Malathion on Human Targets 

From Ground Ultra-Low Volume Mosquito Sprays: J.C. Moore, J.C. Dukes, J.R. Clark, J. Malone, C.F. 

Hallmon, and P.G. Hester; Journal of the American Mosquito Control Association; Vol. 9, No. 2 (June, 

1993)] both human exposure and deposition was quantified over 5 separate application events. A 91 

percent formulation of malathion was applied in April and May of 1989 in the early evening (a time of 

day for relative atmospheric stability). A Leco HD ULV cold aerosol generator (Lowndes Engineering 

Company, Valdosta Georgia) was used to make each application. The application parameters included a 

fluid flow rate of 4.3 fluid ounces per minute, a vehicle ground speed of 10 mph, and a nominal 

application rate of 0.05 lb ai/acre (i.e., equates to a deposition rate of 0.51 μg/cm2). Deposition was 

monitored at three locations downwind from the treatment area (i.e., 15.2 m, 30.4 m, and 91.2 m). For the 

events considered in the deposition calculations, “average amounts of malathion deposited on ground 

level at 15.2, 30.4, and 91.2 m were not significantly different.” The percentage of the application rate 

reported to have deposited ranged from 1 to 14 percent. The mean deposition value for all measurements 

was 4.3 percent (n=35, CV=98).

In the study conducted by Tietze et al., [Mass Recovery of Malathion in Simulated Open Field Mosquito 

Adulticide Tests: N.S. Tietze, P.G. Hester, and K.R. Shaffer; Archives of Environmental Contamination 

and Toxicology; 26: 473-477 (1994)] only deposition was quantified over 6 separate application events 

(i.e., one event was not included in deposition calculations “due to negative air stability”). The 

application parameters were similar to that used by Moore et al. A 95 percent formulation of malathion 

was applied from May to August of 1993. A Leco 1600 ULV cold aerosol generator (Lowndes 

Engineering Company, Valdosta Georgia) was also used to make each application. The application 

parameters included a fluid flow rate of 4.3 fluid ounces per minute, a vehicle ground speed of 10 mph, 

and a nominal application rate of 0.057 lb ai/acre (i.e., equates to a deposition rate of 0.58 μg/cm2). 

Deposition was monitored at four locations downwind from the treatment area (i.e., 5 m, 25 m, 100 m and 

500 m). For the events considered in the deposition calculations, “malathion mass deposited differed 

significantly between the 500 m site and the three closer sites (df = 3; F-value = 3.42; P<0.05).” The 

percentage of the application rate reported to have deposited (not including 500 m samples which were 

much less) ranged up to 5.8 percent. The mean deposition value for all measurements was 3.8 percent.

After considering the data that are available in the Tietze et al. and Moore et al. papers, an off-target 

deposition rate of 5 percent of the application rate was used by HED to evaluate ground-based ULV 

applications (i.e., 5 percent of the target application rate deposits on turf). A value slightly higher than the 

mean values for both studies was selected because of the variability in the data and the limited number of 

data points. The adjusted application rate was then used to define TTR levels by scaling the available 

TTR data as appropriate.

In order to calculate airborne concentrations from ULV truck fogger applications, HED used the 2012 

Residential SOPs for Outdoor Fogging/Misting Systems, with minimal modification to the well-mixed 

box (WMB) model. The WMB model allows for the estimation of air concentrations in the breathing 

zones of adults and children for use in calculating the post-application inhalation exposure to individuals 

residing in areas being treated by ground application of chlorpyrifos. This methodology is a modification 

of the previous method used in the 2011 occupational and residential exposure assessment to evaluate 

post-application inhalation exposure resulting from truck mounted mosquito fogger. The revised 

methodology more accurately accounts for dilution using the WMB model. The WMB model input 

parameters and the algorithms used to estimate residential post-application exposures can be found in 

Appendix C.
Page 22 of 227

Aerial Application

Deposition and air concentrations from aerial ULV applications was modeled using the AgDISP (v8.2.6) 

model which is currently recommended for assessment of mosquito adulticide applications. AgDISP 

predicts the motion of spray material released from aircraft, and determines the amount of application 

volume that remained aloft and the amount of the resulting droplets deposited on the surfaces in the 

treatment area, as well as downwind from the treatment area. The model also allows for the estimation of 

air concentrations in the breathing zones of adults and children for use in calculating the post-application 

inhalation risks to individuals residing in areas being treated by aerial application of chlorpyrifos. The 

input parameters used as the basis for AgDISP (v8.2.6) calculations are presented in Appendix C of this 

document. 

The following outputs of the AgDISP (v8.2.6) model were used in conjunction with the 2012 Residential 

SOPs to assess post-application exposures following mosquito adulticide application: the aerial fraction 

of the mosquito adulticide application rate applied (0.010 lb ai/A) is 0.35 (i.e., 35 percent of application 

rate is deposited on turf); and the airborne concentration at the breathing height of adults and children of 

chlorpyrifos 1 hour following aerial mosquito adulticide application is 0.00060 mg/m3. Figures 2 and 3

below present the estimated aerial chlorpyrifos residue fraction deposited on turf, and aerial airborne 

concentration for the 1 hour following mosquito adulticide applications, respectively. 

Figure 2. Estimated chlorpyrifos deposition downwind from the field edge from aerial treatment of mosquito 

adulticide at release height of 300 feet.
Page 23 of 227

Figure 3. Estimated chlorpyrifos air concentration at the field edge from aerial treatment of mosquito 

adulticide at a release height of 300 feet. 

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

Residential post-application risk estimates for the golf course and public health mosquitocide uses can be 

found in Appendices B and C, respectively. A summary of risk estimates is presented in Table 5.2.2 

below. 

The assessment of steady state golfer post-application exposures (dermal only) to chlorpyrifos treated turf 

for the lifestages adults, children 6 to < 11 years old, and youths 11 to < 16 years old, results in no risks of 

concern (i.e., children 6 to < 11 and youth 11 to < 16 years old, MOEs are ≥ 40; adults, MOEs are ≥ 100). 

For the assessment of post-application exposures from public health mosquitocide applications, no 

combined risks of concern were identified for adults (dermal and inhalation) and children 1 to < 2 years 

old (dermal, incidental oral, and inhalation).

Table 5.2.2. Residential Post-application Non-cancer Exposure and Risk Estimates for Chlorpyrifos.

Lifestage

Post-application Exposure 

Scenario Application 

Rate1

State

(TTR

Data)

Dose 

(mg/kg/day)3 MOEs4 Combined

Routes5

Combined 

MOEs6

Use Site Route of 

Exposure

Adult

(Females)

Golf Course 

Turf Dermal

1.0

(Emulsifiable

Concentrate)

CA 0.010 1,200

NA NA

IN 0.0069 1,700

MS 0.012 1,000

Mean 0.0095 1,200

Youths 11 

to < 16 

years old

CA 0.010 1,400

IN 0.0069 2,000

MS 0.012 1,200

Mean 0.0096 1,500

Children

6 to < 11 

CA 0.012 1,900

IN 0.0082 2,800
Page 24 of 227

Table 5.2.2. Residential Post-application Non-cancer Exposure and Risk Estimates for Chlorpyrifos.

Lifestage

Post-application Exposure 

Scenario Application 

Rate1

State

(TTR

Data)

Dose 

(mg/kg/day)3 MOEs4 Combined

Routes5

Combined 

MOEs6

Use Site Route of 

Exposure

years old MS 0.014 1,600

Mean 0.011 2,000

Adult

(Females)

1.0

(Granular) CA

0.0088 1,400

Youths 11 

to < 16 

years old

0.0088 1,600

Children

6 to < 11 

years old

0.010 2,200

Adult

(Females)

Aerial and 

Ground Based 

ULV

Mosquitocide 

Applications

Dermal

0.010

(Aerial)

MS 0.00052 46,000 X

8,400 Inhalation NA 0.00060

(mg/m3)

10,300 X

Children

1 to < 2

years old

Dermal MS 0.00088 150,000 X

Inhalation NA 2,300 2

0.00060

(mg/m3)

4,000 X

Hand-to-Mouth MS 0.000018 5,600 X

Object-to-Mouth MS 6.1x10-6 180,000 NA NA

Soil Ingestion NA2 1.3x10-6 4,900,000 NA NA

Adult

(Females)

Dermal

0.010

(Ground)

MS 0.000074 320,000 X

1,200 Inhalation NA 0.0051

(mg/m3)

1,200 X

Children

1 to < 2

years old

Dermal MS 0.00013 1,100,000 X

Inhalation NA 460 2

0.0051

(mg/m3)

460 X

Hand-to-Mouth MS 2.8x10-6 39,000 X

Object-to-Mouth MS 8.6x10-7 1,300,000 NA NA

Soil Ingestion NA2 1.7x10-8 34,000,000 NA NA

1 Based on the maximum application rates registered for golf course turf and ULV mosquito adulticide uses. 

2 The airborne concentrations of chlorpyrifos following ULV mosquito adulticide applications was determined with use of the 

AgDISP (v8.2.6) model.

3 Dose (mg/kg/day) equations for golfing and mosquitocide applications are provided in Appendices B and C, respectively. For 

calculation of doses (i.e., dermal, hand-to-mouth, and object-to-mouth) from exposure to ULV mosquito adulticide, TTR data 

was used. The MS TTR data was selected for use because it is the worst case and, as a result, most protective of human health. 

Additionally, the fraction of chlorpyrifos residue deposited following mosquitocide application, 35% (0.35), was determined 

with use of the AgDISP (v8.2.6) model and used for dose calculation. The fraction of chlorpyrifos deposited following ground 

ULV application, 5% (0.050), is based on surrogate exposure data (malathion). For dose estimation from exposures to golfing 

on treated turf, on the TTR data was used. Doses have been presented for all State sites, including the mean of all State sites. 

4 MOE = POD (mg/kg/day) ÷ Dose (mg/kg/day).

5 X indicates the exposure scenario is included in the combined MOE.

6 Combined MOE = 1 ÷ (1/dermal MOE) + (1/inhalation MOE) + (1/incidental oral MOE), where applicable.

NA = Not applicable.

5.3 Residential Risk Estimates and Recommendations for Aggregate Assessment

In accordance with the Food Quality Protection Act (FQPA), HED must consider and aggregate (add) 

pesticide exposures and risks from three major sources: food, drinking water, and residential exposures. 

Table 5.3 below presents the residential risk estimates that are recommended for use in the aggregate 

assessment for chlorpyrifos. 

Under FQPA, the use of chlorpyrifos as a mosquito adulticide protects public health from disease vectors 
Page 25 of 227

and, thus, is considered a use of significant public health importance. While FQPA requirements 

encourage the safe and necessary use of methods to combat and control pests of public health importance, 

public health uses are subject to special consideration (i.e., benefits assessment) and, as a matter of policy, 

not recommended for aggregate risk assessment. 

 The recommended residential exposure for use in the adult aggregate assessment is dermal postapplication exposure from golfing on treated turf. 

 The recommended residential exposure for use in the youth 11 to < 16 years old aggregate 

assessment is dermal post-application exposure from golfing on treated turf. 

 The recommended residential exposure for use in the children 6 to < 11 years old aggregate 

assessment is dermal post-application exposure from golfing on treated turf. 

Table 5.3. Recommendations for the Residential Steady State Exposures for the Chlorpyrifos Aggregate 

Assessment

Lifestage Exposure 

Scenario

Dose (mg/kg/day)1 MOE2

Dermal Inhalation Oral Total Dermal Inhalation Oral Total

Adult 

Females

Golfing on 

Treated Turf

0.012 NA NA 0.012 1,000 NA NA 1,000

Youth 11 to 

< 16 years 

old

0.012 NA NA 0.012 1,200 NA NA 1,200

Children 6 to 

< 11 years 

old

0.014 NA NA 0.014 1,600 NA NA 1,600

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.

5.4 Residential Bystander Post-Application Inhalation Exposure

In the 2011 occupational and residential exposure assessment the potential risks to bystanders from spray 

drift and exposure from volatilization were identified as possible concerns. Spray drift is the movement 

of aerosols and volatile components away from the treated area during the application process. The 

potential risks from spray drift and the impact of potential risk reduction measures were assessed in July 

2012.13 This evaluation supplemented the 2011 assessment where limited monitoring data indicate risks 

to bystanders. To increase protection for children and other bystanders, chlorpyrifos technical registrants 

voluntarily agreed to lower application rates and to other spray drift mitigation measures.14 As of 

December 2012, spray drift mitigation measures and use restrictions appear on all chlorpyrifos 

agricultural product labels. Because the use of the PBPK-PD model impacts the PoDs, and thus spray 

drift risk estimates, an updated assessment was conducted. 

Table 5.4 presents the buffer distances (feet) necessary to reach the level of concern for adults and 

children 1 to < 2 years old (i.e., adults, MOEs are ≥ 100; children 1 to < 2 years old, MOEs are ≥ 40) with 

use of certain application rates, nozzle droplet types, and application methods. The estimated buffer 

distances are less than those agreed to by the technical registrants in July 2012. All drift risk estimates are 

presented in Appendix D. 

 

13 J. Dawson, W. Britton, R. Bohaty, N. Mallampalli, and A. Grube. Chlorpyrifos: Evaluation of the Potential Risks 

from Spray Drift and the Impact of Potential Risk Reduction Measures. 7/13/12. U.S. EPA Office of Chemical 

Safety and Pollution Prevention. D399483, D399485.

14 R. Keigwin. Spray Drift Mitigation Decision for Chlorpyrifos (059101). 7/20/12. U.S. EPA Office of Chemical 

Safety and Pollution Prevention. EPA-HQ-OPP-2008-0850-0103.
Page 26 of 227

Table 5.4. Summary of Spray Drift Buffers for Chlorpyrifos1

Application 

Rate

(lb ai/A)

Nozzle 

Droplet 

Type

Adult Buffer Summary

Children 1 to < 2 Years Old Buffer 

Summary 

(Dermal + Incidental Oral)

Buffers Necessary to reach MOE of 100

(Feet)

Buffers Necessary to reach MOE of 40 

(Feet)

Aerial Groundboom Airblast Aerial Groundboom Airblast

6.0

Medium or 

Coarse

NA2 NA 0 NA NA 25

4.3 NA 0 0 NA 0 10

4.0 NA 0 0 NA 0 10

3.76 NA 0 0 NA 0 10

3.0 Coarse or 

Very Coarse NA 0 0 NA 0 0

3.0 Medium NA 0 0 NA 0 0

2.3 Coarse or 

Very Coarse 50 0 0 0 0 0

2.3 Medium 100 0 0 10 0 0

2.0 Coarse or 

Very Coarse 25 0 0 0 0 0

2.0 Medium 75 0 0 0 0 0

1.5 Coarse or 

Very Coarse 25 0 0 0 0 0

1.5 Medium 50 0 0 0 0 0

1.0 Coarse or 

Very Coarse 10 0 0 0 0 0

1.0 Medium 25 0 0 0 0 0

1 Per December 2012 spray drift mitigation memorandum, aerial application of greater than 2 lb ai/A is only 

permitted for Asian Citrus Psylla control, up to 2.3 lb ai/A.

2 NA is not allowable. 

In January 2013, a preliminary assessment of the potential risks from volatilization was conducted.

15

 The 

assessment evaluated the potential risks to bystanders, or those who live and/or work in proximity to 

treated fields, from inhalation exposure to vapor phase chlorpyrifos and chlorpyrifos-oxon emitted from 

fields following application of chlorpyrifos. The results of the January 2013 assessment indicated that 

offsite concentrations of chlorpyrifos and chlorpyrifos-oxon may exceed the target concentration based on 

the toxicological endpoints used at that time.16

One significant area of uncertainty described in the preliminary assessment was the use of the aerosolized 

chlorpyrifos inhalation toxicity study -- as opposed to chlorpyrifos vapor -- for evaluation of lung AChE 

resulting from field volatilization. Because field volatilization is the production and release of vapor into 

the atmosphere after sprays have settled on treated soils and plant canopies, it is well accepted that the 

vapor, rather than the aerosol, is the relevant form for evaluation of bystander volatilization exposures. 

However, EPA lacked chlorpyrifos vapor data at the time it conducted the preliminary volatilization 

assessment in 2013. Following the release of the preliminary volatilization assessment, Dow 

AgroSciences LLC conducted two, high quality nose-only vapor phase inhalation studies for both 

 

15 R. Bohaty, C. Peck, A. Lowit, W. Britton, N. Mallampalli, A. Grube. Chlorpyrifos: Preliminary Evaluation of the 

Potential Risks from Volatilization. 1/31/13. U.S. EPA Office of Chemical Safety and Pollution Prevention. 

D399484, D400781. 

16 EPA MRID# 48139303: Acute Inhalation Exposure of Adult Crl:CD(SD) Rates to Particulate Chlorpyrifos 

Aerosols: Kinetics of Concentration-Dependent Cholinesterase (ACHE) Inhibition in Red Blood Cells, Plasma, 

Brain and Lung; Authors: J. A. Hotchkiss, S. M. Krieger, K. A. Brzak, and D. L. Rick; Sponsor: Dow AgroSciences 

LLC.
Page 27 of 227

chlorpyrifos and chlorpyrifos-oxon17 to address this uncertainty. 

In June 2014, a re-evaluation of the 2013 preliminary volatilization assessment was conducted to present 

the results of the vapor studies and their impact. In the vapor studies, female rats were administered a 

saturated vapor, meaning that the test subjects received the highest possible concentration of chlorpyrifos 

or chlorpyrifos-oxon which can saturate the air in a closed system. At these saturated concentrations, no 

statistically significant inhibition of AChE activity was measured in RBC, plasma, lung, or brain at any 

time after the six-hour exposure period in either study. Under actual field conditions, indications are that 

exposures to vapor phase chlorpyrifos and its oxon would be much lower as discussed in the January 

2013 preliminary volatilization assessment. 

Because these new studies demonstrated that no toxicity occurred even at the saturation concentration, 

which is the highest physically achievable concentration, then there is no risk potential, as risk is a 

function of both exposure and hazard. By extension, if there is no risk due to exposure to chlorpyrifos or 

chlorpyrifos oxon, only a qualitative risk assessment was completed for volatilization. In June 2014, the 

January 2013 volatilization assessment was revised to reflect these findings.18 

5.5 Residential Dose Reconstruction for the Columbia Cohort

The information presented by researchers associated with the Columbia University cohort indicate that 

pregnant women and children were exposed to chlorpyrifos. The researchers have attributed 

neurodevelopmental effects to chlorpyrifos exposures, perhaps at levels lower than those at which AChE 

inhibition would be experienced. As such, one of the resulting key uncertainties is whether or not these 

individuals could also have experienced AChE inhibition at levels exceeding 10%, which is the regulatory 

threshold for adverse effects for cholinesterase inhibiting pesticides. Whether these exposures occurred is 

key for informing the decision to retain the 10X FQPA safety factor. EPA has completed this dose 

reconstruction exercise to quantify the exposures possibly experienced in the cohort and the associated 

level of RBC AChE inhibition. It should also be noted that in 2012, the FIFRA SAP recommended the 

agency conduct a dose reconstruction analysis to aid in informing this science question. This section 

summarizes the dose reconstruction analysis which was conducted. 

The Columbia University studies included some information regarding the potential for residential 

exposures, but they were incomplete regarding details of individual exposure events. To further inform 

the Columbia investigator’s exposure analyses, the dose reconstruction analysis estimated the possible 

exposure patterns for those in the cohort based on the then allowable indoor uses of chlorpyrifos at the 

time. Where available, chemical-specific information was used in conjunction with the 2012 Residential 

SOPs. Chlorpyrifos-specific exposure data included post-application air monitoring used to quantify 

inhalation exposures from indoor broadcast and crack and crevice applications. Also, chlorpyrifosspecific residue data representing a number of exposure pathways were used including from carpets and 

 

17 W. Irwin. Review of Nose-Only Inhalation of Chlorpyrifos Vapor: Limited Toxicokinetics and Determination of 

Time-Dependent Effects on Plasma, Red Blood Cell, Brain and Lung Cholinesterase Activity in Femal CD(SD): Crl 

Rats. U.S. EPA Office of Chemical Safety and Pollution Prevention. 6/25/14. D411959. TXR# 0056694. EPA 

MRID# 49119501.

W. Irwin. Review of Nose-Only Inhalation of Chlorpyrifos-Oxon Vapor: Limited Toxicokinetics and Determination 

of Time-Dependent Effects on Plasma, Red Blood Cell, Brain, and Lung Cholinesterase Activity in Female 

CD(SD):Crl Rats. U.S. EPA Office of Chemical Safety and Pollution Prevention. 6/25/14. D415447. TXR# 

0056869. EPA MRID# 49210101.

18 W. Britton. W. Irwin. J. Dawson. A. Lowit. E. Mendez. Chlorpyrifos: Reevaluation of the Potential Risks from 

Volatilization in Consideration of Chlorpyrifos Parent and Oxon Vapor Inhalation Toxicity Studies. 6/25/2014. U.S. 

EPA Office of Chemical Safety and Pollution Prevention. D417105.
Page 28 of 227

hard surfaces. These were used for estimation of post-application dermal and incidental oral exposures. 

The algorithms, assumptions, and inputs used to conduct the dose reconstruction analysis are detailed in 

Appendix E. 

Prior to 2000, chlorpyrifos was one of the most widely used insecticides for indoor pest control, so there 

are many possible ways which exposures could have occurred as a result of its use. Based on a review of 

residential products available at the time, it is likely that those in the Columbia study cohort could 

potentially have experienced exposures from the following chlorpyrifos products/uses: broadcast ready to 

use (RTU) sprays; surface sprays ; crack and crevice sprays; and foggers/bombs. Some of these were 

specifically intended for use by pest control operators while others were products marketed for personal 

use. These chlorpyrifos residential products were registered as either a 0.5% or 1% active ingredient 

formulation and the1 % formulation was assumed for all to ensure the assessment was health protective. 

Exposure estimates for all applicable scenarios were calculated and used as the basis for determining the 

level of possible RBC AChE associated with each. The scenarios which were considered include:

 Pregnant mothers who may have purchased a chlorpyrifos consumer aerosol can product and 

applied it in their homes;

 Exposures to pregnant mothers who may have had contact with chlorpyrifos residues in their 

homes following an indoor application; and

 Exposures to children 1 to < 2 years old who may have contact with residues in their homes 

following an indoor application.

Use of the PBPK-PD model

The PBPK-PD model was used to estimate the potential level of cholinesterase inhibition (% RBC AChE) 

attributable to the daily dose estimates that result in the highest exposure potential. In order to model the 

potential health outcomes in a manner reflective of these exposures, a series of inputs were used that 

correspond to those used to quantify the daily dose estimates. The following exposure characteristics 

were used: number of days exposed; body weights which vary by lifestage; daily exposure duration 

(hours per day, days per week); and the fraction of the dermal surface area exposed. 

The dose reconstruction exercise was modeled for a subsequent 14 day post-application duration. The 

daily dose estimated with the 2012 Standard Operating Procedures for Residential Pesticide Exposure 

Assessment for the day of application was inputted into the PBPK-PD model. Dermal exposure was 

modeled assuming that chlorpyrifos residues dissipated at a rate of 10% per day. A 14 day period was 

used as the basis of the PBPK-PD modeling to ensure it adequately addressed the time it takes for the 

ACHE enzyme inhibition to reach a steady state. 

For the adult and children 1 to < 2 years old age groups, the appropriate body weights were obtained for 

modeling purposes from the Exposure Factors Handbook19 (USEPA, 2011). The mean adult female 

bodyweight reflective of all trimesters of pregnancy, 75 kg, was assumed for pregnant women to reflect 

the population of interest from the Columbia cohort being evaluated (Exposure Factors Handbook: adult 

and adult female: Tables 8-3 through 8-5; body weight of pregnant women: Table 8-29). For children 1 to 

< 2 years old, the body weight was set to 11 kg (Exposure Factors Handbook, Table 8-3, mean body 

weight for the 1 to < 2 year old age group). 

For the evaluation of adult handler exposures (dermal and inhalation) it was assumed that the application 

event continued for 1 hour daily and that it occurred each day of the 14 day exposure period. The 2012 

Residential SOPs makes no recommendation regarding the daily exposure duration for handlers. It was 

 

19 http://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=236252
Page 29 of 227

assumed that 1 hour is a high end estimate of the time required to make an aerosol can application. For 

the evaluation of adults and children 1 < 2 years old post-application exposures (i.e., adults: dermal; 

children: dermal and incidental oral), the daily exposure duration was assumed to be 2 hours daily and 

that it occurs each day in the 14 day exposure period. This exposure duration is consistent with that 

recommended in the 2012 Residential SOPs for exposures on hard surfaces. For adults and children 1 to 

< 2 years old inhalation exposures, it was assumed that the exposure duration was 2 hours on the day of 

application (Day 0) and was not repeated because the exposure source (i.e., aerosols from an application 

event) occurred only once on the first day of the exposure period. This is consistent with the available 

monitoring data and consistent with the 2012 Residential SOPs, the Day 0 air monitoring measures were 

followed by a marked drop to negligible levels by the following day. 

For all dose reconstruction dermal exposures to chlorpyrifos, the fraction of skin in contact with 

chlorpyrifos was 50% which reflected uncovered skin areas for children wearing shorts and a tee shirt. 

No shower (i.e., washing off the chlorpyrifos) was assumed to occur for the 14 day exposure duration 

modeled. 

Summary of Dose Reconstruction Risk Estimates

The exposure scenarios with the highest associated risks are presented below. For residential handler 

assessment, the application of an aerosol can resulted in the greatest risk potential. Results for pregnant 

women who applied a 1% formulation aerosol spray can are presented in Table 5.5.1. Peak % RBC 

AChE inhibition estimated for pregnant women from combined dermal and inhalation exposures 

occurring from product application is 0.0012%. 

For the assessment of indoor post-application exposures for adults and children 1 to < 2 years old, 

exposures from indoor broadcast applications result in the highest risk estimates. Results for pregnant 

women and children 1 to < 2 years old exposed from contact to residues following broadcast applications 

to hard surfaces in their homes are presented in Table 5.5.2 and Table 5.5.3, respectively. Peak 

cholinesterase inhibition for pregnant women resulting from combined dermal and inhalation exposures

occurring from contact with previously treated indoor areas is 0.45%. For children 1 to < 2 years old, 

peak cholinesterase inhibition associated with combined dermal, incidental oral, and inhalation exposures 

from being in previously treated areas is 2.7%. 

Overall, the dose reconstruction results support a conclusion that indoor application of chlorpyrifos, when 

used as allowed prior to cancellation from the residential marketplace in 2000, likely would not have 

resulted in RBC AChE inhibition greater than 10% in pregnant women or young children. These findings 

are pertinent to the weight-of-evidence discussion for the FQPA 10X Safety Factor. 

Table 5.5.1. Residential Handler (Pregnant Women in the Columbia Cohort) Estimated Exposures and Predicted 

% ChE Inhibition (Route-specific and Combined)

Exposure 

Scenario Formulation Amount Handled

Dermal Dose

(mg/kg/day)

Dermal:

Peak

% ChE 

Inhibition

Inhalation 

Dose

(mg/kg/day)

Inhalation:

Peak

% ChE 

Inhibition

Combined 

Peak

% ChE 

Inhibition

Broadcast 

Ready to Use:

1 % Aerosol 

Spray Can

1 can 0.049 0.0007% 0.030 0.0008% 0.0012%

a. Dermal Dose = Dermal Unit Exposure (370 mg/lb ai) × Application Rate (0.010 lb ai/can) × Area Treated or Amount Handled 

(cans/day)

b. Inhalation Dose = Inhalation Unit Exposure (3.0 mg/lb ai) × Application Rate (0.010 lb ai/can) × Area Treated or Amount 

Handled (cans/day)
Page 30 of 227

Table 5.5.2. Residential Post-application (Pregnant Women in the Columbia Cohort) Estimated Dermal and 

Inhalation Exposures and Predicted % ChE Inhibition (Route-specific and Combined)

Exposure 

Scenario Formulation Dermal Dose (mg/kg/day)

Dermal: 

Peak

% ChE 

Inhibition

Airborne 

Concentration of 

Chlorpyrifos

(mg/m3)

Inhalation:

Peak 

% ChE 

Inhibition

Combined: 

Peak 

% ChE 

Inhibition

Broadcast

(Hard 

Surfaces)

1% PCO 

Application 

or RTU 1 16 

oz can

0.71 0.45% 0.092 0.0049% 0.45% 

* See Appendix E for the algorithms and inputs used to estimate post-application dermal exposures. 

Table 5.5.3. Residential Post-application (Children 1 to < 2 years old in the Columbia Cohort) Estimated Dermal 

and Inhalation Exposures and Predicted % RBC AChE Inhibition (Route-specific and Combined)

Exposure 

Scenario

Formulatio

n

Dermal 

Dose 

(mg/kg/day)

Dermal:

Peak

% ChE 

Inhibition

HTM

Dose

(mg/kg/day)

HTM Peak

% ChE 

Inhibition

(mg/day)

Airborne 

Concn. of 

Chlorpyrifos

(mg/m3)

Inhalation:

Peak

% ChE 

Inhibition

Combined:

Peak

% ChE 

Inhibition

Broadcast

(Hard 

Surfaces)

1% PCO 

Application 

or RTU 1 16 

oz can

1.3 0.14% 0.10 2.2% 0.092 0.014% 2.7%

* See Appendix E for the algorithms and inputs used to estimate post-application dermal, (HTM) hand-to-mouth, and (OTM) 

object-to-mouth exposures/doses. 

6.0 Occupational Exposure and Risk Estimates

6.1 Occupational Handler Exposure/Risk Estimates

The term handlers is used to describe those individuals who are involved in the pesticide application 

process. 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 a 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 exposure is expected from chlorpyrifos use. Current labels 

generally require that handlers use normal work clothing (i.e., long sleeved shirt and pants, shoes and 

socks) and coveralls, chemical resistant gloves, and dust/mist respirators. Also, some products are 

marketed in engineering controls such as water soluble packets. In order to determine what level of 

personal protection is required to alleviate risk concerns and to ascertain if label modifications are needed, 

steady state exposure and risk estimates were calculated for occupational handlers of chlorpyrifos for a 

variety of scenarios at differing levels of personal protection including engineering controls. 

The 2011 occupational exposure assessment has been updated based on a number of changes that have 

occurred since that time, including the following: 1) use of the PBPK-PD model submitted by 

DowAgroSciences for prediction of the potential risks from occupational chlorpyrifos exposures 2) 

inclusion of use patterns based on a master use summary document developed for chlorpyrifos in 

cooperation with chlorpyrifos registrants 3) use of revised guidance for all of the currently recommended 
Page 31 of 227

unit exposures for standard EPA occupational handler exposure scenarios20, Occupational Pesticide 

Handler Unit Exposure Surrogate Reference Table – Revised March 2013 4) use of the revised seed 

treatment policy, Interim Guidance (SOP 15.1) Amount of Commercial Seed Treated per Day, as was 

updated March 21, 2013 and 5) use of updated adult (female) body weight. 

The updated quantitative exposure/risk assessment developed for occupational handlers is based on the 

following scenarios:

Mixer/Loaders:

(1a) Liquids for Aerial/ Chemigation Applications

(1b) Liquids for Airblast Applications

(1c) Liquids for Groundboom Applications

(1d) Liquids for Wide Area Aerial Applications

(1e) Liquids for Wide Area Ground Applications

(2a) Wettable Powder (in WSP) for Aerial/ Chemigation Applications

(2b) Wettable Powder (in WSP) for Airblast Applications

(2c) Wettable Powder (in WSP) for Groundboom Applications

(3a) Granulars for Aerial Applications

(3b) Granulars for Tractor Drawn Spreader Applications

(3c) Granulars with SmartBox® for Aerial Applications

(3d) Granulars with SmartBox® for Tractor Drawn Spreader Applications

(4a) Water Dispersible Granulars (in WSP) for Aerial/ Chemigation Applications

(4b) Water Dispersible Granulars (in WSP) for Airblast Applications

(4c) Water Dispersible Granulars (in WSP) for Groundboom Applications

Applicators:

(5a) Aerial Liquid Applications

(5b) Wide Area Aerial Applications

(5c) Aerial Granular Applications

(6a) Airblast Applications

(6b) Wide Area Ground Applications

(7a) Groundboom Applications

(7b) Tractor Drawn Granular Applications

(7c) Tractor Drawn Granular Spreader Applications with SmartBox®

(8) Paint Brush/Roller Applications

(9) Cattle Ear Tag Applications

(10) Bait Station Applications

(11) Total Release Fogger

Mixer/Loader/Applicators:

(12a) Liquid: Manually Pressurized Handwand

(12b) Liquid: Wettable Powder (in WSP) for Manually Pressurized Handwand

(12c) Liquid: Microencapsulated for Manually Pressurized Handwand

(12d) Liquid: Backpack Sprayer

(12e) Liquid: Wettable Powder (in WSP) for Backpack Sprayer

(12f) Liquid: Microencapsulated for Backpack Sprayer

 

20 http://www.epa.gov/opp00001/science/handler-exposure-data.html
Page 32 of 227

(12g) Liquid: Mechanically Pressurized Handgun

(12h) Liquid: Wettable Powder (in WSP) for Mechanically Pressurized Handgun

(12i) Liquid: Microencapsulated for Mechanically Pressurized Handgun

(13a) Granulars: Hand Dispersal

(13b) Granulars: Rotary Spreader

(13c) Granulars: Spoon

(13d) Granulars: Belly Grinder

(14a) Water Dispersible Granular (in WSP): Manually Pressurized Handwand

(14b) Water Dispersible Granular (in WSP): Backpack Sprayer

(14c) Water Dispersible Granular (in WSP): Mechanically Pressurized Handgun

Flaggers:

(15a) Flagging for Aerial Spray Applications

(15b) Flagging for Aerial Granular Applications

Occupational Handler Exposure Data and Assumptions

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

risk assessments.

Application Rates: HED assumes the maximum application rates allowed by labels in its risk 

assessments. The updated occupational assessment was conducted with use of the maximum labeled rates 

for all registered uses assessed. The master use summary document can be referenced in Appendix A.

Body weights: For adults when an endpoint is not sex-specific a body weight of 80 kg is typically used in 

risk assessment. However, in this case, a female-specific body weight of 69 kg was used. While the 

endpoint of concern, RBC AChE inhibition, is not sex-specific, the female body weight was used due to 

concerns for pregnant women related to the application of the 10X FQPA safety factor based on findings 

in the Columbia University cohort and the related uncertainty.

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 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 updated assessment, known as “unit exposures”, are outlined in the 

“Occupational Pesticide Handler Unit Exposure Surrogate Reference Table21”, 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 website.

22

Area Treated or Amount Handled: For the updated assessment, the daily areas treated were defined for 

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

single day (e.g., acres, square feet, or gallons per day). When possible, the assumptions for daily areas 

treated are taken from the HED Science Advisory Committee on Exposure (ExpoSAC) Policy 9.1: 

Standard Values for Daily Acres Treated in Agriculture, which was completed on July 5, 2000. However, 

standard values are not available for numerous scenarios. The area treated assumptions identified in the 

2011 occupational and residential exposure assessment as largely the same as used for the updated except 

 

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

22 Available: http://www.epa.gov/pesticides/science/handler-exposure-data.html
Page 33 of 227

for the following changes:

 Paint Roller/Brush: the 2011 assessment assumed 110 gallons for treatment of sewer manhole 

covers, the current assumes 20 gallons for coverage of 50 manholes; 3 gallons applied for all 

other uses as was done previously;

 Fire Ant Mounds: the previous assessment assumed 25 mounds were treated, the current assumes 

that an area of 1,000 square feet is treated. 

Exposure Duration: As described previously, the steady state approach is used and is appropriate for 

chlorpyrifos given the toxicological and exposure profile. The steady state approach accounts for the

short-term exposure duration, as well as for workers that are exposed over longer periods of time (i.e., 

intermediate-term exposures).

Mitigation/Personal Protective Equipment: Estimates of dermal and inhalation exposure were calculated 

for various levels of personal protective equipment (PPE). The lowest tier is designated as the baseline 

exposure scenario (i.e., long-sleeve shirt, long pants, shoes, socks, and no respirator). If risks are of 

concern at baseline attire, then increasing levels of PPE (e.g., gloves, double-layer body protection, and 

respirators) are evaluated. If risks remain a concern with maximum PPE, then engineering controls (e.g., 

enclosed cabs or cockpits, water-soluble packaging, and closed mixing/loading systems) are evaluated. 

This approach is used to ensure that the lowest level of risk mitigation that provides adequate protection is 

selected, since the addition of PPE and engineering controls involves an additional expense to the user 

and – in the case of PPE – also involves an additional burden to the user due to decreased comfort and 

dexterity and increased heat stress and respiratory stress.

An assessment of handler exposure from the use of chlorpyrifos 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, the total release fogger product (EPA Reg. No. 499-405) directions state that once cans are 

activated to, “leave greenhouse at once,” and that, “all human occupants must be removed before 

treatment.” In accordance with a common integrated pest management (IPM) and preventive safety 

practice, if multiple foggers are to be activated, the chlorpyrifos total release fogger label directs the use 

to “start with the can farthest away from the exit door.” 

The assessment of handler exposure from the use of chlorpyrifos ear tag and roach bait stations were also 

not conducted. Dermal exposure is expected to be negligible if gloves are worn, and inhalation exposure 

from these uses is not anticipated. 

Exposure Data for Handler Exposure Scenarios: HED uses unit exposures to assess handler exposures to 

pesticides. Unit exposures are estimates of the amount of exposure to an active ingredient a handler 

receives while performing various handler tasks and are expressed in terms of micrograms or milligrams 

of active ingredient per pounds of active ingredient handled. HED has developed a series of unit 

exposures that are unique for each scenario typically considered in our assessments (i.e., there are 

different unit exposures for different types of application equipment, job functions, and levels of 

protection). The current assessment make sue of the document, Occupational Pesticide Handler Unit

Exposure Surrogate Reference Table – Revised March 2013, was publically released to provide guidance 

for all of the currently recommended unit exposures for standard EPA occupational handler exposure 
Page 34 of 227

scenarios.

23 A summary of all exposure data used to conduct the occupational handler risk assessment is 

presented in Appendix G. 

In addition to this surrogate data, one non-chemical specific exposure study was used for the updated 

assessment. The exposure study was used to assess the use of SmartBox® technology for the 

mixing/loading of granular formulations for aerial and ground applications, and the application by ground 

equipment. Separate data evaluation records (DERs) were completed for the mixing/loading24 and

applicator25 studies. A summary of the study is presented below. 

MRID 44180401 - Chlorethoxyfos Loader Exposure Study During Loading of Fortress 5G Granular 

Insecticide Using the SmartBox® System During Planting in the Midwest: The purpose of the study 

was to determine the exposure to chlorethoxyfos from workers performing loading operations using 

Fortress 5G/SmartBox® product containers in the Midwest. The 5G product is delivered solely through 

closed-handling and application SmartBox® system. Loader exposure to Fortress 5G in the SmartBox®

is based on the use of a long-sleeved shirt, long pants, shoes plus socks and chemical-resistant gloves. 

The study monitored occupational handlers preparing and applying Chlorethoxyfos to corn at planting in 

the Midwest. In the study, loaders set up one load of twelve Smartbox® systems each containing 50 

pounds of formulation for a single twelve row corn planter set on 30” row spacing. The complete work 

cycle for each monitoring unit included removing twelve used Smartbox® product containers from the 

planter, the replacement of twelve full product containers, and opening the valves to fill the Smartbox® 

reservoirs from the full product containers. Each loader monitoring unit (MU) was exposed to 600 pounds 

of product formulation or 30 pounds of active ingredient.

During loading operations, using twelve row planters, three individual workers were monitored for 

dermal and respiratory exposure to chlorethoxyfos. A total of 15 MUs were obtained at 3 sites. All 

participants were local farmers or farm workers and were previously experienced in the ground 

application of pesticides.

Results indicate loader dermal exposure below the level of detection (LOD) and negligible respiratory 

exposure to chlorethoxyfos regardless of wind direction or work habits. The majority of dosimeter 

samples had no detectable residues; therefore, actual exposures may be significantly less than calculated 

exposures since samples below the level of quantitation (LOQ) were assumed to be 1⁄2 the LOQ. 

Respiratory chlorethoxyfos exposure was estimated to be 0.003 μg/lb ai handled, and dermal exposure 

was estimated to be 0.2 μg/lb ai handled.

MRID 44301301 - Chlorethoxyfos Applicator Exposure Study during Application of Fortress® 5G 

Granular Insecticide using the Smartbox® System during Corn Planting in the Midwest: The purpose 

of this study was to monitor chlorethoxyfos exposure to applicators who were operating enclosed-cab 

tractors while applying Fortress 5G/SmartBox®. The granular insecticide was applied at the maximum 

label rate of 3.25 lb of formulation per acre of corn. Indvidual workers were monitored for dermal and 

inhalation exposure to chlorethoxyfos. The experiment was conducted at three sites as required by the 

guidelines. All sites were in Illinois; two of the three are at the same street address. The sites are 

reported to be typical of sites where Fortress® 5G is used. The study was conducted in the time-frame of 

 

23 http://www.epa.gov/opp00001/science/handler-exposure-data.html

24 L. LaSota. Evaluation of Loader Exposure Data Submitted as a Part of the Conditional Registration of Fortress 

5G (Chlorethoxyfos). EPA MRID: 44180401. 1/23/1997. D232274. 

25 J. Arthur. Review of “Chlorethoxyfos Applicator Exposure Study during Application of Fortress® 5G Granular 

Insecticide using the Smartbox System during Corn Planting in the Midwest.” EPA MRID: 443013-01. 7/27/1998. 

D238361.
Page 35 of 227

the typical corn-planting season in the midwestern corn belt (mid-april through late May).

Applicators primarily remained in the enclosed cab tractors and wore appropriate personal protective 

clothing; long sleeve shirt, long pants, shoes and socks. In addition, under their work clothes, each 

applicator wore a long-sleeved t-shirt and ankle-length underwear tights as whole-body dosimeters. 

Those occasions where the worker exited the enclosed cab to perform routine, but non-pesticide-loading 

functions (eg, to perform seed corn loading) were recorded, including a description of the activity and 

duration. 

The average corn-planting acreage per day is reported to be 125 to 150, with a maximum of 180 acres. 

This estimate is based on the use of a 12-row planter set for 30-inch wide rows. At this setting, the 

recommended rate of formula application is 3.25 lb per acre. If 180 acres are covered at 3.25 lb per acre 

with a formulation containing 5% active ingredient (a.i.), then a maximum potential chlorethoxyfos 

exposure could amount to 29.25 lb a.i./day. In this study, an average of 45.3 acres were covered per 

monitoring unit (MU).

Applicator inhalation exposure was monitored with a standard personal air sampling pump (Gilian Model 

HFS-133A) calibrated at a standard 2 liters per minute. One such sampler was attached to each worker to 

collect breathing zone samples during all applicator activities (including outside the enclosed cab), while 

another identical pump always remained inside the cab collecting samples.

No measurable dermal residues were found from the monitoring of chlorethoxyfos applicators. All 

samples were below the level of quantitation (LOQ) for the matrix used. Calculations used one half the 

LOQ. Using dermal residue values based on one half of the LOQ for samples of hands, neck/face, lower 

body and upper body results in a total of 6 ug per MU. Combining this residue amount with the average 

amount applied per MU (147 lb formulation, or 7.4 lb a.i.) results in a dermal unit exposure of 0.81 ug 

a.i./lb a.i. applied. 

Estimated Inhalation Chlorethoxyfos Exposure. The average calculated pump filter residue from airborne 

chlorethoxyfos was 0.06 ug per sample (see table below). When adjusted to a breathing rate of 29 liters 

per minute (lpm), this residue value results in a total of 0.87 ug per MU ( [0.06 ug  2 lpm] x 29 lpm = 

0.87 ug). Combining this residue amount with the average amount applied per MU (147 lb formulation, 

or 7.4 lb a.i.) results in a respiratory unit exposure of 0.12 ug a.i./lb a.i. applied.

Summary of Occupational Handler Exposure Data Gaps: Consistent with the 2011 occupational and 

residential exposure assessment, no new data gaps have been identified for the assessment of occupational 

handler exposure/risk in addition to those identified in the Registration Eligibility Decision (RED) for 

chlorpyrifos (finalized 7/31/06; IRED issued 2/2002). Based on a 90-day progress report submitted 

(August 28, 2003) by the technical registrant, Dow AgroSciences, many of the data requirements are 

anticipated to be supported by the generation of data by the Agricultural Handlers Exposure Task Force 

(AHETF). These data requirements include exposure data for: 

 seed treatment uses;

 mixing wettable powders for aerial/chemigation application;

 loading and applying granulars for aerial application; 

 groundboom application; and 

 human flaggers for aerial application. 

AHETF data for groundboom application and for mixing/loading liquid formulations have been submitted 

and reviewed by HED and used to estimate exposure/risk for occupational handlers from the exposure 
Page 36 of 227

scenario and, therefore, satisfy the data requirement. AHETF data for seed treatment and planting treated 

seed has been submitted and is currently under review by HED. The requirement for exposure data for 

mixing wettable powders for aerial/chemigation applications should be waived because the formulation is 

no longer supported by the registrant. An exposure study for loading granular formulations is being 

planned under AHETF. A study protocol was submitted and reviewed by the Human Studies Review 

Board (HSRB) November 2014. It does not appear, however, that flaggers are being supported by DAS 

as part of their prior response to the data requirements. 

Occupational Handler Non-Cancer Exposure and Risk Estimate Equations

The algorithms used to estimate non-cancer exposure and dose for occupational handlers are the same as 

those presented in the 2011 occupational and residential exposure assessment (Section 2.1.4). 

Combining Exposures/Risk Estimates:

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

RBC AChE inhibition, for these exposure routes were similar. 

Summary of Occupational Handler Non-Cancer Exposures and Risk Estimates

Steady state exposure and risks were calculated for occupational handlers of chlorpyrifos for a variety of 

exposure scenarios at differing levels of personal protection and with engineering controls and are 

presented in Appendix F of this document. PBPK-PD modeled PoDs (dermal and inhalation) specific for 

occupational assessment were used to estimate handler risks. Of the 285 total occupational handler 

exposure scenarios assessed, 132 are not of concern (i.e., MOEs are ≥ 100) at the levels of personal 

protection (clothing or equipment) or engineering controls currently required by product labeling for these 

scenarios. Risks of concern for 27 additional exposure scenarios could potentially be mitigated if 

additional personal protective equipment or engineering controls are used. Risks of concern were 

estimated for 126 exposure scenarios and remain a concern regardless of the levels of personal protection 

and engineering controls considered. These risks could be mitigated using the highest level of personal 

protection available and by modification to other label requirements such as application rate or, in some 

cases, deleting certain types of application equipment.

6.2 Commercial Seed Treatment

Based upon the registered seed treatment uses of chlorpyrifos, occupational handler exposure is expected 

for individuals involved in commercial seed treatment. Post-application exposure to agricultural workers 

is not expected. No chemical-specific handler exposure data were submitted in support of this use 

pattern. 

An assessment of chlorpyrifos commercial seed treatment was conducted in 2011. All occupational 

exposure scenarios assessed, algorithms, and unit exposures used (taken from HED ExpoSAC Policy 14: 

SOPs for Seed Treatment) are the same as were used previously in the 2011 occupational and residential 

exposure assessment (Section 2.3) for the assessment of commercial seed treatment. However, the 

assessment of occupational seed treatment uses has been updated to reflect the use of the guidance 

document, Interim Guidance (SOP 15.1) Amount of Commercial Seed Treated per Day, updated March 

21, 2013, as well as the updated default adult (female) body weight. Also, seed treatment risk was 

estimated with use of PBPK-PD modeled PoDs (dermal and inhalation) specific for occupational 

assessment. 

The steady state approach is appropriate for the assessment of commercial seed treatment with 
Page 37 of 227

chlorpyrifos given the toxicological and exposure profile. The steady state endpoint selection for 

chlorpyrifos accounts for HED’s traditional short-term exposure duration endpoint selection, as well as 

being appropriately health protective for workers that are exposed over longer periods of time (i.e., 

intermediate-term exposures).

Summary of Commercial Seed Treatment Exposures and Risk Estimates

Steady state exposure and risks calculated for occupational handlers performing seed treatment activities 

in commercial settings and for occupational secondary handlers from planting chlorpyrifos-treated seeds 

are presented in Appendix H which accompanies this document. 

Of the 68 exposure scenarios assessed, 36 resulted in risk estimates which were not of concern (i.e., 

MOEs are ≥ 100) at the level of personal protection currently required by product labels. Secondary 

handler (seed planter) scenarios were also evaluated and none are of concern when compared to current 

labels. For the remaining 32 seed treatment scenarios, MOEs were < 100 at all levels of personal 

protection considered and, therefore, are of potential concern. 

6.3 Occupational Post-application Exposure/Risk Estimates

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 re-entry 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. Chlorpyrifos parent compound is the residue of concern for occupational 

post-application dermal exposures; however, it may be possible that the formation of the oxon is greater 

and its deactivation slower in greenhouses when compared to the outdoor environment and that an 

assessment may be needed for exposure to the oxon in greenhouse settings. Occupational postapplication assessments were performed for: 1) exposures to the parent compound chlorpyrifos in outdoor 

environments (uses other than greenhouse), 2) exposures to the parent chlorpyrifos (only) in greenhouses 

and 3) exposures to both the parent and the oxon metabolite in greenhouses.

An update of the occupational post-application exposure assessment is required based on use of the

following: 1) a PBPK-PD modeled dermal PoD specific for occupational assessment 2) the master use 

summary document 3) the updated adult (female) default body weight 4) the changes relating to 

agricultural transfer coefficients (TC) as described in the Science Advisory Council for Exposure 

(ExpoSAC) Policy 3 – Revised March 2013.

26

6.3.1 Occupational Post-application Inhalation Exposure/Risk Estimates

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. As described in Section 

5.4, a quantitative risk assessment is not required for chlorpyrifos or chlorpyrifos oxon due to the lack of 

toxicity from the vapor phase of these chemicals, even at the saturation concentration. 

 

26 http://www.epa.gov/opp00001/science/exposac-policy-3-march2013.pdf
Page 38 of 227

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)].

6.3.2 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 postapplication risk assessments. The majority of assumptions and exposure factor detailed in the 2011 

exposure assessment are the same, except for changes relating to agricultural transfer coefficients (TC) as 

described in the Science Advisory Council for Exposure (ExpoSAC) Policy 3 – Revised March 2013 and 

the standard adult body weight assumptions. 

Post-application Exposure Data: The 2011 occupational and residential exposure assessment made use of 

7 Chemical-specific DFR studies in support of the re-registration of chlorpyrifos that encompass the use 

of 5 different formulations and 12 different crops. Specifically, the DFR studies examine the use of 1) 

emulsifiable concentrate formulations on sugarbeets, pecans, citrus, sweet corn, cotton, and turf; 2) 

wettable powder formulations on almonds, apples, pecans, cauliflower, tomato and turf; 3) granular 

formulations on sweet corn and turf; 4) a total release aerosol formulation on ornamentals; and 5) a 

microencapsulated liquid formulation on ornamentals. The submitted studies were reviewed by HED. 

Despite limitations, HED recommended the use of all or some of the data in the studies to assess postapplication risks to chlorpyrifos except for the tomato DFR data. Summaries for all DFR studies can be 

referenced in Appendix I of this document. 

The current assessment makes use of the same DFR data and crop pairings as was done for the 2011 

occupational and residential exposure assessment. For example, DFR data for an individual crop was 

applied to that specific crop, as well as to crops in the same crop grouping (e.g., cauliflower data was used 

for cauliflower and all other cole crops). For other crops in which no crop-specific or crop group-specific 

data are available, the DFR data for the crop deemed the closest match were used as surrogates to 

calculate potential exposure (e.g., cauliflower data were also used for strawberries, cranberries, and leafy 

vegetables). Additionally, whenever possible, a label use was assessed using DFR data for the same 

formulation type. A full description of the criteria for selection of DFR data for assessment of postapplication exposures to individual crops/crop groupings can be referenced in Section 2.4.3 of the 2011 

occupational and residential exposure assessment. 

The DFR data were extrapolated to the currently labeled crops as follows:

Cauliflower (MRID 42974501):

Berry: Low

Vegetable: Head and Stem Brassica

Vegetable: Leafy

Citrus (MRID 43062701):

Tree Fruit: Evergreen

Ornamental/Nurseries 

Vine/Trellis

Apple (MRID 44748101):

Tree Fruit: Deciduous (Pome and Stone Fruit)
Page 39 of 227

Forestry

Ornamentals/Nurseries 

Almond and Pecan (MRID 44748101):

Tree Nuts

Cotton (MRID 44748102):

Field and Row Crops: Low to Medium (Fiber, Legume Vegetable, Non-grass Animal Feeds) 

Vegetable: Fruiting

Stalk and Stem Vegetable

Sugarbeet (MRID 44748102):

Field and Row Crops: Low to Medium

Ornamentals (Outdoor Only)

Vegetable: Root and Tuber

Stalk and Stem Vegetable

Sweet Corn – Emulsifiable Concentrate and Granular Formulation (MRID 44748102):

Field and Row Crops: Tall

Turf (MRID 44829601):

Turf

Greenhouse Ornamentals – Total Release Aerosol Formulation (MRID 46722701):

Greenhouse Use (All Liquid Formulations)

Greenhouse Ornamentals – Microencapsulated Liquid Formulation (MRID 46722702):

Greenhouse Use (Microencapsulated Liquid Formulation Only)

Summary of Occupational Post-application Dermal Exposure and Risk Estimates

Steady state occupational post-application dermal risk estimates are presented in Appendix J which 

accompanies this document based on the PBPK-PD model predicted dermal PoD. 

Current labels require a Restricted Entry Interval (REI) of 24 hours from most crops and activities, but in 

some cases such as tree fruit, REIs are up to 5 days after application. The post-application worker 

assessment results indicate that no REI increase is required for the majority of outdoor environment crops 

and commodities with a labeled REI (i.e., 43 of 55 total). However, for 12 crops, activities such as 

irrigation, hand harvesting, scouting, and thinning result in risks of concern up to as many as 10 days 

following application. 

For the assessment of post-application exposures to parent chlorpyrifos (only) from ornamental 

production in greenhouses, 4 formulations were assessed: emulsifiable concentrate, microencapsulated 

liquid, wettable powder in WSP, and total release fogger. An REI increase of up to 5 days may be needed 

to alleviate risks from with use of the emulsifiable concentrate, wettable powder in WSP and total release 

fogger formulations. For the microencapsulated liquid formulation, the estimated REIs range from 0 to > 

35 days after treatment (the completion of the monitoring period) dependent on the exposure activity 

considered.
Page 40 of 227

6.4 Occupational Post-application Dermal Exposure/Risk Estimates: Chlorpyrifos Oxon

Chlorpyrifos is activated by desulfuration, reacting in bioactivation to the more toxic and potent acetyl 

cholinesterase (AAhE) inhibitor, chlorpyrifos oxon. The oxon is highly unstable due to rapid deactivation 

through hydrolytic cleavage by a process called dearylation which releases TCP. In the 2011 

occupational and residential exposure assessment, the exposure potential for post-application 

occupational and residential exposures to chlorpyrifos oxon was considered. Workers reentering an 

indoor environment (i.e., greenhouses) previously treated with chlorpyrifos could potentially be exposed 

to the oxon as chlorpyrifos degrades. Available exposure data indicate chlorpyrifos oxon may form in 

indoor environments.27 Toxicity adjustment factors (TAFs), were developed for the 2011 preliminary 

human health risk assessment28 to estimate the potency of chlorpyrifos oxon relative to chlorpyrifos. 

HED determined the oxon to be between 11.9 (acute) and 18X (chronic) times more toxic than the parent. 

Dermal exposure to the oxon on foliar surfaces from reentry into an outdoor environment (e.g., field crops 

and orchards) previously treated with chlorpyrifos is not anticipated and, therefore, has not been assessed. 

No occupational exposure studies (handler, post-application, or DFR) were identified that quantified the 

levels of oxon present in the environment. However, a search of open literature for the 2011 assessment 

resulted in 4 plant metabolism studies which measured surface residues. Three plant metabolism studies29

measured leaf surface residues of the oxon in outdoor environments that were either well below the 

parent, not detectable, or detected at a level just above the level of detection (LOD). The potential for 

exposure to the oxon is further minimized due to rapid deactivation of the oxon to TCP. Further, the 

dietary exposure risk assessment30 conducted in support of registration review concludes the following, 

“all residues in food are assumed to be parent chlorpyrifos since the chlorpyrifos oxon is not typically 

found in foods, in monitoring data, or crop field trials.” 

The 4

th plant metabolism study, a tomato and green bean greenhouse metabolism study, was less 

definitive than the other three plant metabolism studies regarding oxon presence. HED is concerned that 

the formation of the oxon may be greater and its deactivation to TCP slower in greenhouses when 

compared to the outdoor environment. The study results indicate that oxon is from 9 to 14X less than the 

parent from fruit analyzed on the day of application in flat and asymmetric roof greenhouses. The 

proportion of oxon to parent is less for all days which measurable levels were observed (all but 8 and 15 

days after application). The oxon was detected until day 5 with levels between 5 and 6X below that of the 

parent. It should be noted that residues of chlorpyrifos and oxon were measured from analysis of whole 

fruit samples. HED typically assesses occupational post-application exposure and risk based upon the 

potential for transfer from surface residues. The whole fruit samples, which include surface residues, as 

well as residues which may have been contained within the fruit sample, likely impact the oxon presence. 

Regardless, the 2011 occupational and residential exposure assessment recommended additional data to 

measure the chlorpyrifos and oxon residues on leaf surfaces following treatment with a liquid formulation 

in greenhouses in order to address these uncertainties and more accurately address the risk potential for 

 

27 J.L. Martinez Vidal, et al. 1998. Diminution of Chlorpyrifos and Chlorpyrifos Oxon in Tomatoes and Green 

Beans Grown in Greenhouses. J. of Agric. and Food Chem. 46 (4), 1440–1444.

28 D. Drew. Chlorpyrifos: Preliminary Human Health Risk Assessment for Registration Review. 6/30/11. U.S. 

EPA Office of Chemical Safety and Pollution Prevention. D388070.

29 29 Iwata, Y. et al. 1983. Chlorpyrifos Applied to California Citrus: Residue Levels on Foliage and On and In 

Fruit. J. Agric. Food Chem. 31(3), 603-610. 

H. Jin and G.R. Webster. 1997. Persistence, Penetration, and Surface Availability of Chlorpyrifos, Its Oxon, and 

3,5,6-Trichloro-2-pyridinol in Elm Bark. 45(12), 4871-4876.

R. Putnam, et al. 2003. The Persistence and Degradation of Chlorthalonil and Chlorpyrifos in a Cranberry Bog. J. 

Agric. Food Chem. 51(1), 170-176.

30 D. Drew. Chlorpyrifos: Acute and Steady State Dietary (Food Only) Exposure Analysis to Support Registration 

Review. 12/18/2014. U.S. EPA Office of Chemical Safety and Pollution Prevention. D424486.
Page 41 of 227

exposure from occupational reentry into greenhouses treated with chlorpyrifos. To date, no data has been 

submitted to address these uncertainties. As a result, HED has conducted an assessment of occupational 

post-application exposures in greenhouses that uses conservative assumptions of oxon formation. 

In order to account for the formation of and potential increased toxicity from exposure to chlorpyrifos 

oxon, a total toxic residue approach was applied which combines chlorpyrifos and chlorpyrifos oxon 

(expressed as toxicity equivalents). The total toxic residue approach31 estimates the chlorpyrifos oxon 

equivalent residues by 1) assuming a specific fraction of the measured chlorpyrifos dislodgeable foliar 

residues are available as the oxon and 2) factoring in the relative potency of chlorpyrifos oxon with use of 

a TAF. It was conservatively assumed that 5% (0.05) of the total chlorpyrifos present as DFR in 

greenhouses is available for worker contact during post-application activities. This assumption is based 

on a review of available TTR and DFR data for other OPs where both the parent and metabolite were 

measured in residue samples. Five percent was found to be the high-end value for the percent of parent 

that metabolized during the course of the residue studies. The chronic TAF (which is appropriate for 

steady state assessment) of 18 was derived from BMD analysis of inhibition of RBC AChE in adult 

female rats (adult male rats not examined) observed in the repeated phase of the CCA study. Once 

predicted, these total toxic (dislodgeable foliar) residues are used to estimate exposures from postapplication activities in greenhouse and risks are estimated with used of the steady state PoD for 

occupational exposures, 4.9 mg/kg/day. 

Summary of Occupational Post-application Dermal Exposure and Risk Estimates with Use of Total Toxic 

Residue Approach

Due to uncertainty regarding the formation of chlorpyrifos oxon in greenhouses, HED also estimated risks 

for reentry into treated greenhouses (all 4 formulations) for the parent chlorpyrifos plus chlorpyrifos oxon 

using a total toxic residue approach. When the total toxic residue approach is used to evaluate risks from 

exposure to the oxon with use of the emulsifiable concentrate, wettable powder in WSP, and total release 

fogger formulations, results indicate that an REI increase up to 6 days may be needed to alleviate risk 

concerns. For the microencapsulated liquid formulation, REIs range from 3 to > 35 days after treatment 

(the completion of the monitoring period) dependent on the exposure activity considered. 

 

31 Total DFR (μg/cm2

) = [ Chlorpyrifos DFR (μg/cm2) * TAF] + [ Chlorpyrifos DFR (μg/cm2)] 
Page 42 of 227

Appendix A: Chlorpyrifos Master Label Use Document
Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

AGRICULTURAL FARM 

PREMISES

Livestock housing 

and holding areas 

(such as hog 

barns, empty 

chicken houses, 

dairy areas, 

milkrooms, calf 

hutches, calving 

pens and parlors).



Indoor 

general 

surface spray

backpack 

sprayer; high 

and low sprayer 

(pressure or 

volume)

0.075 lb a.i./ 

1000 ft sq

1.2 

EC, ME

[14.4]

NS NA 12 NA NA NS NS

Only permitted 

for use in 

poultry houses

ALFALFA

 At plant groundboom 1.0 

G

1.0 1.0 [1]

NS 1 21 24 [10]NS

Missouri 

only

Lower PHI 

permitted for 

EC rates 0.33 lb 

a.i./A (7 d) and 

0.67 lb a.i./A 

(14 d) e.g. Reg. 

No. 62719-591

Stand is in 

production 3-5 

years. Planted 

1⁄4” to 1⁄2” deep. 

 Foliar

aerial or 

ground/ 

broadcast, 

chemigation

1.0 

EC

[4.0]

NS 4.0 [4]NS 4 21 24 10

Lower PHI 

permitted for 

EC rates 0.33 lb 

a.i./A (7 d) and 
Page 44 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

0.67 lb a.i./A 

(14 d) e.g., Reg. 

No. 62719-591

Multiple 

harvests (or 

cuttings) per 

year when used 

for feed/fodder 

and 1 harvest 

per year when 

grown for seed. 

Cuttings occur 

about every 30 

days.

Only 1 crop 

cycle per year 

but up to 9 

cuttings, varies 

by geography.

Total 1.0 5.0 5.0 [5]

NS 5 21 24 [10]NS

Represents 

Missouri 

scenario 

otherwise 4.0 lb 

a.i./A per is 

max. 

ALMOND



dormant/

delayed 

dormant;

broadcast

aircraft, airblast 2.0 

WDG, WP 2.0 NA 1 NA NA 24 10

Restricted 

use in 

California.
Page 45 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2



foliar;

broadcast aircraft, airblast 2.0WDG,WP 6.0 NA 3 NA 14 10



pre-plant, 

foliar;

trunk 

spray/drenc

h or preplant dip

handheld, 

backpack, 

drench/dip, 

handgun, and 

low pressure

hand wand

2.5

(3.0/100 gal)

WDG

2.5 NA 1 NA 14 NS



Dormant/ 

delayed 

dormant; 

foliar; 

orchard 

floors 

broadcast 

ground boom, 

handgun, 

chemigation

4.0

EC* 4.0 NA 2 NA 14 10

Restricted 

use in 

California. 

Only one 

dormant 

application 

can be made.

Total -- 4.0 14.5 NA 7 NA 14 NS

Excludes 

nursery 

applications 

(See general 

“Fruits” listing)

APPLE



dormant/

delayed 

dormant;

broadcast

aircraft, airblast

2.0 

EC

2.0

WDG

1.5

WP

2 2.0 1 1 NA 24/ 

4 d 10d

Reflects spray 

drift mitigation 

measures.



pre-plant, 

foliar;

trunk 

spray/drenc

handheld, 

backpack, 

drench/dip, 

handgun, and 

1.5

(1.5 lb ai/100 

gal)

WDG 

1.5 NA 1 1 28 4d NS

Use 

permitted in 

states east of 

the Rockies 
Page 46 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

h or preplant dip;

ground

low pressure 

hand wand

except 

Mississippi.

Total 2.0 3.5 2

ASPARAGUS 

Foliar, preharvest; 

broadcast

aircraft, ground 

boom

1.0 

EC, WDG 1.0 1.0 1 1 1 24 10



Postharvest, 

broadcast

aircraft, ground 

boom

1.0 

EC, WDG 2.0 2.0 2 1 1 24 10

granular soil 

band treatment 

ground boom

1.5 

G

3.0 3.0 2 2 180 24 [10]

NS

Permitted in 

California, 

the Midwest, 

and the 

Pacific 

Northwest 

19713-505, 

19713-521, 

5481-525, 

62719-34, 

83222-34

Do not apply 

more than 3.0 lb 

a.i./A between 

harvests.

Total 1.5 

G

3.0 G

2.0

3.0 G

2.0 3 3 1 24 10

BEANS



Preplant; 

Seed 

treatment

Seed Treatment

0.016-0.348

0.000798 lb 

ai/lb seed 

ME

NS [0.348]

NS NS [1]NS NS NS NS

ME is SLN 

only for ID

Italics highlight 

the range of 

application 

rates depending 
Page 47 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

0.013-0.272

0.000625 lb 

ai/lb seed 

WP

0.012-0.253

0.00058 lb 

ai/lb seed 

EC

on the number 

of seeds per lb 

and the number 

of seeds planted 

per acre. 

Seeding rate 

information 

provide by 

BEAD.4

BEEF/RANGE/ 

FEEDER 

CATTLE 

(MEAT)/

DAIRY 

CATTLE (NONLACTATING)

Summer, late 

fall, spring; 

impregnated 

collar/tag

Animal 

treatment (ear 

tag)

0.0066

lb/animal

[0.0099

]

NS

NA 3 NA NS NS NS

Reg. No. 

39039-6

Cattle ear tags 

are assumed to 

last 4-6 months 

Two tags per 

animal at 

0.0033 lb 

a.i./tag in the 

summer and 

one tag per 

animal at 

0.0033 lb a.i./A.

BEETS 

(UNSPECIFIED; 

TABLE OR 

SUGAR)

“grown for seed”



At plant, soil 

band 

treatment

Ground boom 1.0 

EC NS 1 NS 1 24

Allowed in 

Oregon

Court 

ordered 

buffer of 60 

ft for ground 

chlorpyrifos 

application 

Minimum 

Incorporation: 2 

inches
Page 48 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

is required 

for “affected 

waterways”.



Preplant, soil 

incorporated 

treatment

Broadcast/ 

ground boom

1.9

EC

NS

(2.8 ID) NS 1 NS

Allowed in 

Oregon and 

Idaho

OR-09007; 

62719-591

ID-090002; 

62719-591

Total 1.9 NS NS NS NS 24

One or the other 

type of 

application.

SUGAR BEETS 

Preplant, soil 

incorporated 

treatment

Broadcast/ 

ground boom

1.0 

EC

2.0 

G

3.0 2.0 1

1

NA 24 10

Minimum 

Incorporation: 1 

inch



At plant, soil 

band 

treatment

Broadcast/ 

ground boom

1.0

EC, WDG

2.0 

G

3.0 2.0 1 1 30 24 10



Postplant, 

soil band

Broadcast/ 

ground boom

2.0 

G

3.0 2.0 1 1 30 24 10



Postemergence 

band 

treatment; 

broadcast

Broadcast/ 

ground boom

1.0 

EC, WDG 3.0 1.0 3 1 30 24 10

 broadcast

Aircraft, ground 

boom, 

chemigation

1.0 

EC, WDG 3.0 1.0 3 1 30 24 10

EC is not for 

use in MS

Total 1.0 4.0 [4.0] 3 [3] 30 24 10 One granular 
Page 49 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

EC

2.0 

G

NS NS application at 

2.0 a.i./A and 

two liquid 

applications at 

1.0 a.i./A per 

year. Also 

assumed per 

crop cycle.

CARROT 

Grown for Seed 

(INCLUDING 

TOPS)



Foliar prebloom 

broadcast

aircraft, ground 

boom

0.94 

EC 0.94 1 1 1 7 24 NA

Oregon and 

Washington 

Court 

ordered 

buffer of 60 

ft for ground 

and 300 ft 

for aerial 

application 

is required 

for “affected 

waterways”.

OR090011

SLN Expires: 

12/31/2018 

WA090011 

SNL Expires: 

12/31/2016 

Carrots take 

two years to 

produce seed. 

All commercial 

production of 

the carrot 

(vegetable) 

takes place in 

the first year 

when the plant

is nowhere near 

blooming.

CHERRIES dormant/

delayed aircraft, airblast 2.0

WDG, EC 2.0 NA 1 NA NS 24 10
Page 50 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

dormant;

broadcast

1.5

WP



foliar;

broadcast 

airblast 4.0

EC 10.0 NA 5 NA 14 24 10

Tart cherry only

aircraft 2.0 Reflects spray 

drift mitigation



Foliar, post 

harvest;

trunk 

spray/drenc

h 

handheld, 

backpack, 

drench/dip, 

handgun, and 

low pressure 

hand wand

2.5

(3.0/100 gal)

WDG, EC

2.5 NA 1 NA 2 24 [10]

NS

Only some 

labels specify a 

10 d MRI. 

Total

--

4.0

4.5 

(sweet)

14.5 

(tart 

only)

6

Excludes 

nursery 

applications 

(See general 

“Fruits” listing)

The foliar 

applications 

only apply to 

tart cherries, 

thus, sweet 

cherry scenarios 

(e.g., Pacific 

NW) annual 

application rate 

would be 4.5 lb 

total a.i./year.

CHRISTMAS  foliar; helicopter, 1.0 3.0 NA 3 NA [0] 24 7 Aerial 
Page 51 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

TREE 

PLANTATIONS

broadcast orchard blast EC, WDG, WP NS applications 

via 

helicopter 

are only 

permitted in 

Washington 

and Oregon.



post harvest;

Stump 

Treatment

handheld, 

backpack, 

drench/dip, 

handgun, and 

low pressure 

hand wand

2.5

(3.0/100 gal)

EC, WDG

2.5 NA 1 NA NA 7

Total 2.5 5.5 4

CITRUS 



foliar;

broadcast

airblast, ground 

boom

6.0 

WP, WSP, EC 7.5 NA 2 NA

35 

(21 

for 

low 

rate

s)

5d

30 

(10 

for 

low 

rates

)

6.0 lb a.i. /A 

is only 

permitted in 

California 

and Arizona.

The max 

single rate in 

other states 

is restricted 

to 4 lb a.i./A.

 aircraft 2.3

WP, WSP, EC 21 5 10

Florida, 

California, 

and 

potentially 

Texas

Aerial 

application used 

to control 

psyllid, the 

vector for citrus 

greening.
Page 52 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

Reflects spray 

drift mitigation



foliar; 

orchard 

floors 

broadcast

ground boom, 

chemigation, 

handheld, 

backpack, 

drench/dip, 

handgun, and 

low pressure 

hand wand

1.0

G*, WSP, EC 3.0 NA 3 NA 28 24/ 5 d 10

Total -- 6.0 10.5 5

Registered 

labels permit 

both foliar and 

soil applications 

in the same 

orchard.

Total excludes 

nursery 

applications 

(See general 

“Fruits” listing)

CLOVER 

(GROWN FOR 

SEED)

 Preplant Ground boom 1.9 

EC 1.9 1.9 1 1 NS 24 NA

Use only 

permitted in 

Oregon.

OR-0900100; 

master label: 

62719-591



Post-Plant 

Foliar

aircraft and 

ground boom

Either a 

preplant or post 

plant 

application is 

allowed.
Page 53 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

COLE CROPS 

(EXCLUDES 

CAULIFLOWE

R AND 



Preplant, soil 

incorporated 

treatment

Ground boom

2.0

EC, WDG, G 4.0 2.0 2

1

30

24

10

Min. 

incorporation: 

2 inches

BRUSSELS 

SPROUTS) 

At plant, soil 

band 

treatment

Ground boom 1

One granular 

application 

permitted per 

year.

 Post plant Ground boom 1 



Foliar 

Established 

Plantings, 

soil sidedress 

treatment

Ground boom 1



Foliar, 

broadcast

Aircraft, ground 

boom, 

chemigation

1.0

EC, WDG, WP 4.0 3.0 4 3 21 10

Multiple crops 

per year are 

possible in 

some locations.

Total 8.0 5 6

4

Some labels 

restrict the 

yearly 

application rate 

to 3 lb a.i./A.

The maximum 

number of crops 

per year is 2.

BRUSSELS 

SPROUTS



At plant, soil 

band 

treatment

Ground boom 2.0

EC; G

2.0 [2.0]

NS 2 1 21
Page 54 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2



Preplant, soil 

incorporated 

treatment

Ground boom

24 10 Minimum 

incorporation is 

2 inches



Postplant, 

soil 

application

Ground boom 2.25 EC, G 2.25 [2.25]

NS



Foliar 

broadcast

Aircraft, 

Ground boom

1.0

EC

[5.3]

NS 3.0 NS 3 10

83222-20, 

84930-7, 

86363-3 specify 

a 7 day MRI. 

All other labels 

specify a 10 day 

MRI.

The PHI stated 

84930-7 is 

conflicting [p. 4 

(21 days and p. 

19 (30 days)]

Total 2.3 5.3 NS 21 24 7

Assume one 

application of 

either at plant, 

preplant, or 

postplant

followed with 

additional foliar 

applications.

CAULIFLOWER



At plant, soil 

band 

treatment

Ground boom

2.0 

EC

2.3 

G

2.0 

EC

2.25 

G

NS [1]

NS 1 21 3d 10

Only one 

granular 

application.
Page 55 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2



Preplant, soil 

incorporated 

treatment

Ground boom 2.3 

G

2.0 

EC

2.3 NS [1]

NS 1

30, 

EC,

21 

G

Minimum 

incorporation is 

2 inches



Postplant, 

soil 

application

Ground boom



Foliar 

broadcast

aircraft, ground 

boom

1.0 

EC

[5.3]

NS 3.0 NS 3 21 10

Total 2.3 5.3 [5.3]

NS NS [4]NS 21 24 10

Assume one 

application at 

either plant, 

preplant, or 

postplant 

followed with 

additional foliar 

applications.

COMMERCIAL

/INSTITUTIONAL/ 

INDUSTRIAL 

PREMISES/ 

EQUIP. 

(INDOOR)

Non-food areas of 

manufacturing, 

industrial, and 

food processing 

plants; 

warehouses; ship 

holds; railroad 

Broadcast Product 

Container

0.4373 lb 

a.i./100 sq ft

190.5 

G

NS NA NS NA NA NS NS For treatment of 

fire ants

Crack and 

Crevice/Void

Sprayer/ 

Injection

0.0625 lb 

a.i./1000 sq ft

2.7 

ME

NS NA NS NA NA NS NS 499-419

Crack and 

Crevice/Spot

Sprayer/ 

Injection

0.0424 lb/gal 

ME NS NA NS NA NA NS 7
Page 56 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

boxcars.

COMMERCIAL

/INSTITUTION

AL 

/INDUSTRIAL 

PREMISES/EQ

UIP. 

(OUTDOOR)

Outdoor 

commercial use 

around non-food 

areas of manufacturing, industrial, 

and food 

processing plants; 

warehouses; ship 

holds; railroad 

boxcars

Soil 

broadcast

Low and High 

Pressure, 

Backpack, 

Handgun 

Sprayers

0.0247 lb 

a.i./1000 sq ft

1.1 

ME

NS NA NS NA NA NS NS

Directed 

spray

0.1132 lb 

a.i./1000 sq ft

4.9 

ME

NS NA NS NA NA NS NS

Specific to: 

Inside and 

outside 

dumpsters and 

other trash 

holding 

containers, trash 

corrals and 

other trash 

storage areas.

Crack and 

Crevice/void/

general 

outdoor

0.0424 lb/gal 

ME NS NA NS NA NA NS 7

CONIFERS 

AND 

DECIDUOUS 

TREES; 

 ?

foliar;

broadcast Ground boom 1.0 EC 3 NA 6 NA 7 24 7

PLANTATION, 

NURSERY  ?

foliar; stump 

treatment

backpack, 

drencher, low 

pressure hand 

wand

0.3 

EC 0.3 NA 1 NA 7 24 7

Total 1.0 3 NA 6 NA 7 24 7

The total 

number of 

applications 
Page 57 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

assumed is 

either 3 foliar 

applications or 

2 foliar 

applications 

with one stump 

treatment.

CORN (ALL)  Preplant

ground/ soil 

incorporated

conservation 

tillage, in 

furrow, 

broadcast, 

chemigation, 

soil band

3.0 

EC

2.0 

G

3.0 3.0 NS 3 NA

24/ 

5 

EC

10

19713-520, 

19713-599, 

33658-26, 

34704-857, 

72693-11, 

83222-20

The minimum 

incorporation 

depth is 2 

inches.

soil 

incorporated 

aerial

conservation 

tillage

2.0

EC, G



ground/ 

conservation 

tillage, in 

furrow, 

broadcast, 

chemigation, 

soil band

1.0

EC

2.0 

G

3.0 3.0 NS 3 21 10 19713-520
Page 58 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2



Storage or 

preplant seed 

treatment

Seed treatment

0.001-0.021

0.000625 lb 

a.i./ lb seed 

WP

0.1-1.9

0.058 lb a.i./ lb 

seed 

FC

[?]

NS

[1.9]

NS

[?]

NS 1 NS NS NS

Italics highlight 

the range of 

application 

rates depending 

on the number 

of seeds per lb 

and the number 

of seeds planted 

per acre. 

Seeding rate 

information 

provide by 

BEAD.4

 At plant

soil 

incorporated, 

conservation 

tillage

2.0 

G

[?]

NS 3.0 [?]NS 3 21 24 10



Post 

emergence

Aerial or 

ground, 

broadcast, 

chemigation

1.5 

EC

1.0 

WDG

NS 3.0 NS 3 21

24/ 

5d 

(EC

10

A brush on max 

single rate is 

permitted at 1.0 

lb ai/a (72693-

11)

 Foliar

Aerial or 

ground/ 

broadcast, 

granule, seed 

and 

chemigation

1.5 

EC 3.0 3.0 NS 3 21 10

Total 3.0 8.1 8.1 NS 4 21 10 Two granular 

applications are 
Page 59 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

allowed with a 

maximum 

single rate of 

1.0 lb a.i./A or 

one granular 

application at 2 

lb a.i./A.

Total with seed 

treatment

PHI: 21 d 

except 

Delaware and 

Florida (7 d)

COTTON 

Storage or 

preplant seed 

treatment

Seed treatment

0.8-2.2

0.00116 lb/lb 

seed 

EC

[2.2] 

NS

[2.2] 

NS

[1]

NS 1 NS NS NS

264-932

Rates in italics 

highlight the 

potential range 

of application 

rates depending 

on the number 

of seeds per lb 

and the number 

of seeds planted 

per acre. 

Seeding rate 

information 

provide by 

BEAD.2

 Foliar aerial, 

chemigation, 

1.0 

EC, WDGP 3 3.0 3 3 14 24 10 Except MS
Page 60 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

ground boom 

Total 1.0 3.2 3.2 3 3 14 24 10

1.6 lb a.i./A is 

max single rate 

(seed treatment)

Total with seed 

treatment

1 crop cycle per 

year assumed

CRANBERRY  Foliar

aircraft, ground 

boom/ 

broadcast and 

chemigation

1.5 

EC, WDG 3.0 NA 2 NA 60 24 10

Not for use 

in 

Mississippi.

Do not apply to 

bogs when 

flooded.

CUCUMBER 

Storage or 

preplant seed 

treatment

Commercial

seed treatment

0.4

0.00058 lb/lb 

seed

EC

NS 0.1 2 1 NS NS NS

Seeding rate 

information 

provide by 

BEAD.2

264-932, 

62719-221, 

CA040004

Per registrant 2 

CCs per year

FIGS 

dormant/

delayed 

dormant; 

soil 

application

ground boom 2.0

WDG, EC 2.0 NA 1 NA 217 4 d NS

Use is 

restricted to 

California 

only.

Incorporation to 

3 inches is 

suggested but 

not required 

following 

application.

FILBERTS/ 

HAZELNUT



dormant/ 

delayed 

dormant;

aircraft, airblast 2.0 

WP 2.0 NA 1 NA 14 24 10
Page 61 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

broadcast



foliar;

broadcast aircraft, airblast 2.0WDG, WP, EC 6.0 NA 3 NA 14 10

Some labels 

specify a 

retreatment 

interval of 10 

days.

Total 2.0 6.0 NS 3.0 NA 14 24 10

Excludes 

nursery 

applications 

(See general 

“Fruits” listing)

FOOD 

PROCESSING 

PLANT 

PREMISES 

(NONFOOD 

CONTACT)

When 

needed, crack 

and crevice 

treatment, 

spot 

treatment

0.0424 lb/ gal 

ME NS NA NS NA NA NS 7

53883-264, 

84575-3 

Spot Treatment: 

Do not exceed 

two square feet 

per individual 

spot.

FOREST 

PLANTINGS 

(REFORESTAT

ION 

PROGRAMS)

(TREE FARMS, 

TREE 



Foliar, 

broadcast ground boom 1.0 EC 6.0 NA 6 NA

24

7

PLANTATION, 

ETC.)



Foliar, stump 

treatment

direct spray,

drencher

0.34 

EC 6.0 NA [18]NS NA 7

FOREST 

TREES 

(SOFTWOODS, 



Foliar, 

broadcast

ground boom, 

drencher

0.61

EC 3.6 NA NS NA 24 7
Page 62 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

CONIFERS)



Foliar, stump 

treatment direct spray

[3.6]

2.4 lb a.i./100 

gal 

EC

3.6 NA NS NA 7

Application rate 

is provided as a 

dilution factor.

FRUITS & 

NUTS 

Non-bearing (not 

to bear fruit 

within 1 year) 

fruit trees in 

nurseries 

(includes: 

almonds, citrus, 

filbert, apple, 

cherry, nectarine, 

peach, pear, plum, 

prune).



Foliar-Nonbearing 

nursery 

broadcast

High/low 

volume spay/ 

hand held 

sprayer/power 

sprayer

4.0 

EC 4.0 NA NS NA 14 NS 7

For nectarines 

and peaches, 

the use is 

restricted to one 

application of 

no more than 3 

lb a.i./A per cc. 

For apples, the 

max rate is 2 lb 

a.i./A per crop 

cycle and the 

use is restricted 

to 1 application 

(either canopy 

or trunk drench) 

per year. 

Example label, 

62719-254



Foliar-Nonbearing 

nursery trunk 

drench

drencher, high 

and low 

pressure sprayer

2.0

WDG 2.0 NA NS 1 14 7

Total 4.0 6.0

Maximum 

Single Rates: 

3.0 (nectarines 
Page 63 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

and peaches)

2.0 (apples)

Maximum 

Yearly Rates: 

3.0 (nectarines 

and peaches)

2.0 (apples)

GINSENG 

(MEDCINAL)



Preplant, 

postemergence

Ground, soil 

broadcast

2.0 

G

2.0 NA 1 NA 365 24 NA

Permitted in 

Michigan 

and 

Wisconsin

MI110006,WI1

10003)

Minimum 

incorporation: 4 

inches 

Application 

should be 

followed by 

rainfall or 

overhead 

watering.

Valid until June 

29, 2016.

GOLF COURSE 

TURF

When 

needed, soil 

broadcast/ 

spot 

treatment

Ground, low 

pressure

1.0

EC 2.0 NA 2 NA

24

NS

Foliar, 

broadcast, 

Ground boom, 

handgun, low 

pressure and 

backpack

1.0 

EC, G, B 2.0 NA 2 NA NS

Chemigation 

not allowed for 

the EC 

formulation.
Page 64 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

Tractor drawn 

spreader, push 

type spreader, 

belly grinder

1.0 

G

[24

]

NS

7

Mound 

treatment

Granule 

applicator

1.0

G

2.0 NS 2 NS NS 7

Total 2.0 2.0 NA 2 NA NS NS

GRAPES



Dormant/ 

Delayed 

Dormant 

(pre-bloom)

Ground boom, 

broadcast, 

drench

high/low spray 

volume

1.0 

WDG, EC 1.0 1 1 NA 35

24

NS

East of the 

continental 

divide only.

Do not use in 

conjunction 

with soil 

surface 

applications for 

grape borer 

control.



2.0

EC 2.0 1 1 NA 35

Permitted in 

Colorado, 

Idaho, and 

Washington

CO080008, 

ID090004, 

WA090002

Master label: 

62719-591

 Foliar

Ground/ 

broadcast, basal 

spray and 

drench (soil 

treatment)

2.25 

EC 2.25 1 1 NA 35 NS

Permitted 

east of the 

continental 

divide.



1.0 

EC 3.0 3 3 NA 35 NS California CA080010



Postharvest, 

dormant/ 

Ground boom, 

broadcast

2.0 

EC 2.0 1 1 NA NS NS California CA080009
Page 65 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

delayed 

dormant

Total 2.25 2.25 1 35 24 NS

Permitted 

east of the 

continental 

divide.

2.0 5.0 4 NS NS California

GRASS 

FORAGE/ 

FODDER/HAY 

Foliar, 

broadcast

Aircraft, ground 

boom, 

chemigation

1.0 

EC 3.0 NA 3 NA NS 24

Permitted in 

Nevada, 

Oregon, 

Washington, 

and Idaho

NV080004, 

NV940002, 

OR090009, 

WA090010,

ID090003

GREENHOUSE



early 

evening, 

aerosol, fog 

or fumigation

Total release 

fogger

0.029 

0.0066 lb 

a.i./1000 sq. ft

PL

NS NA NS NA NS NS 2

HOUSEHOLD/

DOMESTIC 

DWELLINGS 

INDOOR 

PREMISES

 When needed Bait station 0.0003 lb/bait 

station NS NA NS NA NA NS NS 9688-67

HYBRID 

COTTONWOO

D/ POPLAR 

PLANTATIONS



Foliar, 

dormant, 

delayed 

dormant; 

broadcast

High volume 

(dilute)

Low volume 

(concentrate)

1.9 

EC

[2.0]

NS 6.0 [1]NS 3 24 7 Washington

WA090004

Energy wood 

plantations may 

be harvested as 

often as every 

2-3 years; 

pulpwood 5-10 

years; and saw 
Page 66 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

timber 15-20 

years. 

(Arkansas 

production 

guide). In 

Washington the 

crop takes 2-8 

years

LEGUME 

VEGETABLES



Preplant, soil 

treatment Ground boom 1.0 EC, WDG 1.0 NA 1 NA NS

24

NA No MRI 

because 

application only 

once a year



At planting, 

soil treatment Ground boom 1.0 EC, WDG 1.0 NA 1 NA NS NA

Total 1.0 1.0 NA 1 NA NS 24 NS

Assumed either 

a preplant or an 

at plant 

treatment.

MINT/ 

PEPPERMINT/ 

SPEARMINT



Preplant soil 

incorporated

Aerial or 

ground/ 

broadcast

2.0 

EC, WDG

[2.0]

NS 2.0 [1]NS 1 90

24

NA No use in 

Mississippi.

19713-599, 

33658-26, 

34704-857, 

67760-28, 

84229-25, 

84930-7, 

OR940027

MRI NA due to 

once per crop 

cycle 

application



Postemergence, Chemigation, 

ground/ airblast

2.0 

EC 2.0 2.0 [1]NS 2 90 NS No use in Mississippi.

Postharvest 

application 
Page 67 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

Postharvest, 

Foliar

retreatment not 

specified on 

some labels.

Total 2.0 4.0 4.0 2.0 3 90 24 NS

Labels allow 

one growing 

season 

application 

including preplant and one 

post-harvest 

application per 

season.

MOSQUITO 

CONTROL; 

HOUSEHOLD/

DOMESTIC 

DWELLINGS 

OUTDOOR 

PREMISES;

RECREATION

AL AREAS



When 

needed; 

broadcast

Ultra low 

volume air and 

ground

0.01

EC 0.26 NA 26 NS NA NS 24 h

In Florida: 

Do not apply 

by aircraft 

unless 

approved by 

the Florida 

Dept of Ag.

Aerial 

applications 

may be made at 

altitudes 

ranging from 

75-300 ft (see 

labels for 

specifics).

For use by 

federal, state, 

tribal or local 

government 

officials or by 

persons 

certified in the 

appropriate 

category or 

authorized by 
Page 68 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

the state or 

tribal lead 

regulatory 

agency.

NECTARINE



dormant/

delayed 

dormant

broadcast

airblast, 

handgun

3.0

WDG, EC

3.0 NA 1 NA NS

24/

4d

10

83222-20 others 

at 2 lb a.i./a

Aircraft 2.0

WDG, EC

Updated to 

reflect spray 

drift mitigation.



pre-plant, 

foliar;

trunk 

spray/drenc

h or preplant dip

Handgun, low 

pressure 

backpack, dip

2.5

(3.0/100 gal)

WDG, EC

2.5 NA 1 NA 14 5

There is no 

application 

retreatment 

interval 

specified on 

some of the 

label. The 

application rate 

is provided as a 

dilution factor.

Total 3.0 5.5 NA 2 NA

Some labels 

limit the 

amount a.i./A 

per year. 

Multiple types 

of applications 

can occur such 

as preplant, 

trunk drench 

and dormant, 

delayed 
Page 69 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

dormant 

applications. 

Excludes 

nursery 

applications 

(See general 

“Fruits” listing)

NONAGRICUL

TURAL 

OUTDOOR 

BUILDINGS/ST

RUCTURES

to and around 

outside surfaces 

of nonresidential 

buildings and 

structures. 

Permitted areas of 

use include 

fences, preconstruction 

foundations, 

refuse dumps, 

outside of walls, 

and other areas 

where pests 

congregate or 

have been seen

Outdoor 

general 

surface/ Band 

(may be 

better if 

called 

perimeter)

Ground sprayer/ 

band sprayer

1.0 

EC NS NA NS NA NA NS NS

NURSERYSTOCK: : 

Dormant/ 

Delayed high spray 3.0EC 3.0 NA 1 NA 24 NS
Page 70 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

Ornamental 

nursery stock 

annuals, 

perennials and 

woody plants 

being grown in 

the field, in ball 

and burlap or in 

containers 

outdoor and in 

greenhouses

Dormant

Preplant

Ground boom, 

soil 

incorporated

4.0

EC, WP NS NA NS NA

foliar, soil 

directed

Tractor drawn 

spreader, push 

type spreader, 

belly grinder, 

gravity fed 

backpack, 

spoon

1.1 

G

Total 4.0 CBD 3

ONIONS 

Post plant 

(seeding) 

Broadcast

Ground boom 1.0 

EC 1.0

NS

2

NS 60 24 NS



At plant, soil 

drench or 

basal spray

Ground boom 1.0 

EC, WDG, G 1.0 1 2 inch incorporation

Total 2.0 2.0 2 60 24 NS

ORNAMENTAL  Foliar Ground boom, 2.0 2.0 NA [2] NA NS 24 NS Some labels 
Page 71 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

AND/OR 

SHADE TREES, 

HERBACEOUS 

PLANTS

broadcast air blast, 

handgun, low 

and high 

pressure hand 

wands

EC, WP

1.0 

G, B

NS include a MRI 

of 7 days.



Dormant 

/Delayed 

Dormant

Handgun, low 

pressure and 

backpack

3.0 

EC 3.0 NA 1 NA NS 7

Low volume 

spray permitted 

for concentrated 

solutions and 

lower rates.

ORNAMENTAL 

LAWNS AND 

TURF, SOD 

FARMS (TURF)



When 

needed, 

broadcast, 

soil or spot 

treatment

ground boom 

(WP only), high 

pressure hand 

wand

3.76

EC, WP 7.52 NA 2 NA NS 24 NS

 NS

Tractor drawn 

spreader, push 

type spreader, 

belly grinder

1.0 

B

2.0 NA 2 NA NS 24 NS Bait is used for 

fire ant control.

ORNAMENTAL 

NONFLOWERING 

PLANTS



Foliar, 

broadcast, 

soil drench

Chemigation, 

ground boom, 

low and high 

pressure 

handwand, 

handgun, 

backpack 

sprayer, 

sprinkling can

0.007/gal 

ME NS NA 12 NA NA 24 NS

Application rate 

provided as a 

dilution factor.

Restricted 

use—

occupational 

only

ORNAMENTAL 

WOODY 

Foliar 

broadcast

Ground boom, 

air blast, 

2.0 

EC, WDG

2.0 NA [1]

NS NA NS 24 NS Several labels do not restrict 
Page 72 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

SHRUBS AND 

VINES

handgun, low 

and high 

pressure 

sprayer, 

backpack

0.01 lb/gal 

EC

0.01 

lb/gal

the application 

rate in lb a.i./A. 

Examples 

include 16.5 

lb/100 gal (228-

625) and 1.0 

lb/100 gal (829-

280).

Dormant/ 

delayed 

dormant

1.0 

EC

0.005 lb/gal 

EC

1.0 NA [1]

NS NA

Preharvest

Tractor drawn 

spreader, push 

type spreader, 

belly grinder

6.0 

G

6.0 NA [1]

NS NA

Preplant, 

potted, 

bailed-and 

burlapped, 

containerized

groundboom, 

handgun, low 

and high 

pressure 

sprayer, 

backpack, 

drench

1.0

EC NS 1 NS 1

Pretransplant groundboom 4.0 

WP

[48.0]

NS 4 12 4

Total

6.0

G

4.0

WP

CBD CBD

PEACH  dormant/ airblast 3.0 3.0 NA 1 NA 10 24/ NS 83222-20 (all 
Page 73 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

delayed 

dormant

broadcast

EC

2.0

WDG

4d other labels 

restrict to 2 lb 

ai/a)

aircraft,

2.0

EC

2.0

WDG

NS

Updated to 

reflect spray 

drift mitigation.



Post-harvest

broadcast

airblast

2.5

(3.0/100 gal)

EC

2.5

NA 1 NA NA NS

Permitted in 

Georgia and 

South 

Carolina

GA0400001, 

SC040001

SLN Expires:

aircraft

2.0

(3.0/100 gal)

EC

2.0

GA0400001, 

SC040001

SLN Expires:

Updated to 

reflect spray 

drift mitigation



pre-plant, 

foliar;

trunk 

spray/drenc

h or preplant dip;

ground

handheld, 

backpack, 

drench/dip, 

handgun, and 

low pressure 

hand wand

2.5

(3.0/100 gal) 

WDG

2.5 NA 1 NA 14 5 NS

Some labels do 

not specify 

minimum 

retreatment 

interval. 

Total

3.0 5.5 NA 3 NA NA 24 NS It is possible 

that multiple 

types of 

applications can 

occur such as 

soil, foliar 

and/or post3.0 8.0 NA 3 NA NA 24 NS

Permitted in 

Georgia and 

South 

Carolina
Page 74 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

harvest and 

dormant/ 

delayed 

dormant 

applications.

Excludes 

nursery 

applications 

(See general 

“Fruits” listing)

PEANUT

 Preplant

Aerial or 

ground/ 

broadcast

2.0 

EC, WDG

[4.0]

NS 4.0 [2]NS 2 NA 24 10

Do not apply 

aerial in 

Mississippi Assumes one 

crop cycle per 

year.



At plant, 

postplant

4.0 

G

[4.0]

NS 4.0 2 2 21 24 10

 At pegging

2.0 

G

EC, WDG

[4.0]

NS 4.0 2

[2]

NS 21 24 10

Total

4.0 

G

2.0 

EC, WDG

4.0 4.0 2 2 10 24 10

PEAR



dormant/

delayed 

dormant

broadcast

aircraft, airblast 2.0

WDG, EC 2.0 NA 1 NA NA 24 NA

Restricted 

use in 

California. 

83222-20 

allows 3.0 lb 

a.i./ A; 

however, this 

does not match 

the 2001 RED.



Post-harvest

broadcast aircraft, airblast 2.0WDG, EC 2.0 NA 1 NA NA 24 NS Permitted in California, 
Page 75 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

Oregon and 

Washington.

Total 2.0

WDG, EC 4.0 NA 2 NA NA 24 NS

Multiple types 

of applications 

may occur in 

within a year in 

California, 

Oregon and 

Washington 

such as a postharvest 

application and 

a dormant, 

delayed 

dormant.

Excludes 

nursery 

applications 

(See general 

“Fruits” listing)

PEAS



Preplant Seed 

treatment Seed Treatment

0.30

0.000625 lb/lb 

seed 

WP

0.28

0.00058 lb/lb 

seed 

EC

NS NS NS NS NS NS NS

There is a range 

of potential 

application 

rates depending 

on the number 

of seeds per lb 

and the number 

of seeds planted 

per acre. 

Seeding 
Page 76 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

information 

provide by 

BEAD.2

PECANS



dormant/

delayed 

dormant

broadcast

aircraft, airblast 2.0

EC, WDG 2.0 NA 1 NA 14

24

10 66222-19 and 

66222-233



foliar;

broadcast

airblast 4.3

EC, WDG

6.3 NA 3 NA 14 10

Some labels 

require a 28 d 

PHI

aircraft 2.0

EC, WDG

Updated to 

reflect spray 

drift mitigation.



foliar; 

orchard 

floors 

broadcast

Ground boom, 

chemigation

4.3

EC, WDG 4.3 NA 2 NA 14 10

Total 4.3 12.6 NA 6 NA 14 24 10

Considers 

multiple type of 

applications 

(e.g., dormant, 

foliar broadcast, 

and orchard 

floor) but 

excluding 

nursery 

For nursery 

applications 

(See general 

“Fruits” listing)
Page 77 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

PEPPER  Foliar Ground 

broadcast

1.0 

WDG

[8]

NS 8.0 [8]NS 8 7 24 10 Permitted in Florida

FL040005; 1 

crop cycle per 

year.

PINEAPPLE  Postplant Ground boom, 

broadcast

2.0 

EC 6.0 6.0 3 NA 365 24 30 Permitted in Hawaii

HI090001 

SNL Expires: 

March 29, 

2014.

Do not make 

applications 

beyond three 

months after 

planting. 

PLUM/

PRUNE 

dormant/ 

delayed 

dormant;

broadcast

Aircraft, 

airblast

2.0

EC, WDG 2.0 NA 1 NA NA

24/

4d

10



foliar;

trunk 

spray/drenc

h

handheld, 

backpack, 

drench/dip, 

handgun, and 

low pressure 

hand wand

2.5

3.0/100 gal

WDG

2.5 NA 1 NA NA 10

Total 2.5 4.5 NA 2 NA

Excludes 

nursery 

applications 

(See general 

“Fruits” listing)

POULTRY 

LITTER 

When 

needed,

animal 

Sprayer

0.07126 

a.i./1000 sq ft

3.1 

NS NA NS NA NA NS 53883-264, 

84575-3
Page 78 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

bedding/litter 

treatment. 

ME

PUMPKIN



Preplant Seed 

treatment Seed treatment

0.3

0.00058 lb /lb 

seed

WP

[0.3]

NS

[1]

NS

[1]

NS 1 NS NS NS

California 

maximum 

single rate 

0.000625 lb 

a.i./lb.

There is a range 

of potential 

application 

rates depending 

on the number 

of seeds per lb 

and the number 

of seeds planted 

per acre. 

Seeding 

information 

provide by 

BEAD.4

RADISH

 Foliar Broadcast 

ground

1.0 

EC NS 1 NS 1 NS 24 NS permitted in Oregon

OR090012 on 

radish grown 

for seed.

Label valid 

until December 

31, 2012. (per 

registrant SLN 

still valid)

 Preplant

Soil 

incorporation 

ground

3.0 

EC 12.0 3 4 1 NS NS 10



At plant/postplant

In furrow 

drench/ 

treatment

3.0 

EC

2.8 

G

[15.0]

NS 3

[5]

NS 1

30, 

EC,

7, 

24 10

Only one 

granular 

application 

permitted.
Page 79 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

G

Total 3.0 [22.0]

NS 2

[9]

NS

Only one 

preplant or at 

plant 

application is 

assumed.

RIGHTS OF 

WAY, ROAD 

MEDIANS

When 

needed, soil 

broadcast

Granular or low 

pressure wand

1.0 

EC, G, Bait

[2.0]

NS NA 2 NA NA NS 7

Apply when 

needed

RUTABAGA

 Preplant

Chemigation, 

Groundboom

2.4

EC, WDG [4.8]

NS

2.4

[2]

NS 1 30 24 10

Aerial 2.0

EC, WDG 2.0

Updated to 

reflect spray 

drift mitigation.



At plant/postplant

In furrow 

drench/ 

treatment

2.4

EC, G WDG 4.8 2.4 [2]NS 1 7 24 10

Disallowed 

in California 

and Arizona.

Two crop 

cycles per year

Total 2.4 [9.6]

NS 4.8 [4]NS 2 24 10

SEWER 

MANHOLE 

COVERS AND 

WALLS

When needed Low pressure

0.31 

lb/manhole 

RTU

NS NA NS NA NA NA NS 3 pints product/ 

manhole

SEED 

ORCHARD 

TREES



foliar;

broadcast Ground boom 1.0EC 3.0 3.0 NS NA 30 24 7

62719-575, 

62719-615



High volume 

sprayer

2.5

0.01

a.i./tree

2.5 NS [1]

NS NA 30 24 7

Cone worm 

treatment 

(62719-575 and 
Page 80 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

0.02 EC 62719-615)

Treatment of 

1000 trees per 

acre would 

results in an 

single 

application rate 

of 10 lb a.i./a.

DAS: 1000 is a 

bit high, 

typically for 

orchards 312 

trees per acre



foliar; stump 

treatment

backpack, 

drencher, low 

pressure hand 

wand,

0.3

EC 0.3 1.0 NS NA 30 24 7

62719-575, 

62719-615

Total 1.0 5.8 3 NS NA 30 24 7

The total 

number of 

applications 

assumed is 

either three 

foliar 

applications or 

two foliar 

applications 

with one stump 

treatment.

SORGHUM 

GRAIN



Seed 

Treatment Seed treatment [0.0009]0.01-

0.01 0.01 [1]

NS 1 NA NS NS 264-932
Page 81 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

0.0024 lb ai/ 

100 lbs seed 

EC



Preplant Soil 

Directed

Ground 

Spreader/T 

Band

1.5

G

1.5 1.5 [1]

NS 1 60 24 10



Foliar/Post 

emergent

Ground, Aerial, 

Chemigation

1.0 

EC, WDG 1.5 [1.5]NS

[1]

NS 3 30 24 10 PHI varies across labels

Total

3.3

G

1.0

EC, WDG

3.01 3.01 [3]

CBD 3 30 24 10 One crop cycle 

per year.

SOYBEAN 

foliar , postemergence 

soil broadcast

broadcast 

ground, aerial, 

chemigation

1.0 

EC, WDG 3.0 3.0 3 3 28 24 14 One crop cycle per year.



At plant/post 

plant 

treatment;

soil band

ground boom

2.2

G

1.0 EC

3.0 3.0 1 (G), 

3 (EC)

1 (G), 

3 

(EC)

28 24 10

Total

1.0

EC, WDG

2.2

G

3.0 3.0 3 3

One crop cycle 

per year.

STRAWBERRIES 

 Pre-plant

Aerial or 

ground/ 

broadcast

2.0

EC 2.0 NS 1 NS NA 24 10 No use in Mississippi 33658-26
Page 82 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

 Foliar

Aerial or 

ground/

broadcast, foliar 

spray

1.0

EC, WDG 2.0 NS 2 NS 21

24

10

Two 

applications (2 

lb ai) for all 

products per cc.

 Post harvest Ground directed 

spray

1.0

EC, WDG 2.0 NS 2 NS 21 14

Total 2.0 4.0 3

One preplant 

application and 

two foliar 

and/or 

postharvest 

application 

permitted per 

year.

SUNFLOWER  At plant

Aerial/ground

2.0 

G

3.0 3.0 [1]

NS 1 42

24

10 Per registrant 1 

cc per year

 Preplant 2.0 

EC, WDG 3.0 3.0 [1]NS 1 42 10 2 inches min incorporation 



Post 

emergent or 

foliar

1.5 

EC, WDG 3.0 3.0 [2]NS 2 42 10

Total 2.0 5.0 5.0 3 3

Assumed either 

an at plant or 

preplant 

application 

followed with 

two foliar 

applications. 
Page 83 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

One crop cycle 

per year

SWEET 

POTATO



Preplant, soil 

broadcast

Aircraft, ground 

boom

2.1

G, EC, WDG

2.1 NS 1 1 125 24

LA090002,

MS080007, 

NC090001 

permits 60 

PHI

Aircraft 2.0

G, EC, WDG

Updated to 

reflect spray 

drift mitigation.

TOBACCO  Preplant Aircraft, ground 

boom

2.0

EC, G, WDG 2.0 NS 1 1 7 24 NA

TRITICALE 

Storage 

Commercial 

Slurry Seed 

Treatment

Seed treatment

0.003

0.0024 lb ai/ 

100 lbs seed 

EC

[0.003]

NS

[1]

NS

[1]

NS

[1]

NS NA

[10

]

NS

[10]

NS

264-932

Seeding 

information 

provide by 

BEAD.4

One crop cycle 

per year.

TURNIP  Preplant

soil 

incorporation/ 

ground boom, 

handgun

2.3 

G, WDG

[4.6]

NS 2.3 [2]NS 1 30 24 10

Minimum 

incorporation: 

2 inches.

 Postplant

Soil 

incorporation/ 

ground boom, 

handgun

2.3

G, WDGP

[4.6]

NS 2.3 [2]NS 1 30 24 10

Minimum 

incorporation: 

2 inches.

Total 2.3 4.6 2.3 2 1 30 24 10

Assumed either 

a preplant or 

postplant 

application.

Two crop 

cycles per year
Page 84 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

UTILITIES

For use in and 

around 

telecommunicatio

ns, power, utilities 

and railroad 

systems 

equipment: 

Buried cables, 

cable television 

pedestals, cables, 

pad-mounted 

electric power 

transformers, 

telephone cables, 

underground 

vaults, 

telecommunicatio

ns equipment, 

power and utilities 

equipment 

When 

needed, 

broadcast

Product 

container

190.5

G

0.44 lba.i./100 

sq ft

(see 

comments)

NS NS NS NS NS NS NS

Applications 

permitted as 

needed. Reg. 

Nos. 13283-14, 

13283-17

Broadcast 

product onto the 

ground 

covering the 

area of the pad 

location, plus a 

two foot 

perimeter 

around the 

outside of the 

pad location.

WALNUTS



dormant/

delayed 

dormant;

broadcast

Aircraft, 

airblast

2.0

EC, WDG 2.0 NA 1 NA 14

24

10 62719-301 (12 

lb a.i./A)



foliar;

broadcast

aircraft, 

airblast, 

chemigation

2.0

EC, WDG 4.0 NA 2 NA 14 10

Some labels do 

not specify 

retreatment 

interval.

 foliar; Ground boom, 4.0 4.0 NA 1 NA 14 10
Page 85 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

orchard 

floors 

broadcast

chemigation EC, WDG

Total 4.0 10.0 4

Excluding 

nursery 

applications; 

includes 

dormant, foliar 

broadcast, and 

orchard floor.

For nursery 

applications 

(See general 

“Fruits” listing)

WIDE AREA/ 

GENERAL 

OUTDOOR 

TREATMENT 

For ants and other 

misc. pests.

 

when needed, 

Broadcast Ground sprayer

0.5084 lb 

ai/100 gal 

EC

[1.02]

NS NA 2 NA NA

NS

NS 66222-19 

when needed, 

Drench Drench

1 NS NA NS NA NA NS 228-624

[1]

8.2 lb a.i/100 

gal EC

NS NA NS NA NA NS 228-625 

Total [1] NS NA NS NA NA

WHEAT



Slurry Seed 

Treatment Seed treatment

0.003

0.0024 lb ai/ 

100 lbs seed 

EC

[0.006]

NS 1

[2]

NS 1 NA NA NA

Only for use 

in AZ, CA, 

CO, ID, KS, 

MN, MO, 

NE, NM, 

NV, ND, 

OK, OR, 

Seeding 

information 

provide by 

BEAD.4



Foliar, soil 

treatment

Ground, 

broadcast

0.5 

EC

[8.0]

NS 4.0 [2]NS 1

14/

28 24 14

PHI: 14 forage 

or hay, 28 grain 

or straw
Page 86 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2



Postemergence 

foliar

Ground, Aerial, 

Chemigation

1.0 

EC

[4.0]

NS 2.0 [4]NS 2

14/

28 NS

SD, TX, UT, 

WA and WY

Label states 1.0 

lb ai/A for 

cereal leaf 

beetles and then 

state max rate 

0.5 lb ai/A in 

restriction). 

Some labels 

restrict no more 

than 2 

applications per 

crop/season

PHI 14 forage 

or hay, 28 grain 

or straw

Total

[1]

4.0

EC

[12.006

]

[6.003]

5.0

[8]

NS

[4]

2

MO otherwise

2.0 plus seed 

treatment

WOOD 

PROTECTION 

TREATMENT 

TO 

BUILDINGS/

PRODUCTS 

OUTDOOR

When 

needed, 

Wood 

surface 

treatment

Low pressure 

handwand, 

backback 

sprayer, 

paintbrush

16.65 

lb/10,000 sq ft

0.17 lb a.i./gal

EC

NS NA NS NA NS NS NS

0.08 lb ai/gal

EC, RTU EC, 

ME

NS NA NS NA NS NS NS

Apply 1 gal per 

100 sq ft of 

wood
Page 87 of 227

Table A.1. Summary of Current Chlorpyrifos Usage

Crop/Site

Residential

Agricultural

Forestry

Timing;

Application 

Type 

Method/

Equipment

Maximum 

Single 

Application 

Rate by 

Formulation1

(lb a.i./A)

Maximum 

Application Rate

Maximum 

Application 

Number 

PHI (days)

3

REI (hours)

3

MRI (days)

3

Geographic 

Restrictions Comments

Per 

Year

lb 

a.i./A

Per 

CC2

lb a.i./A

Per 

Year

Per 

CC2

1. EC - emulsifiable concentrate; WDG – water dispersible granular in water soluble packet; WP – wettable power in water soluble packet; B – bait (granular), G – granular; ME –

microencapsulated; RTU – ready to use.

2. Reported as per crop cycle or per season

3. PHI – Preharvest interval; REI – reentry interval; MRI – Minimum retreatment interval

4. Becker, J.; Ratnayake, S. Acres Planted per Day and Seeding Rates of Crops Grown in the United States, U.S. EPA OPP/BEAD, 2011; example calculations provided below:

Beans: 0.00058 lb a.i./lb seed / 960 seeds/lb seed x 418,176 seeds/A [pgs. 19, 81 (beans, succulent)]

Corn: 0.000625 lb a.i./lb seed / 1,800 seeds/lb seed x 59,739 seeds/A [pgs. 24, 81 (corn, sweet)]

Cotton: 0.00116 lb a.i./lb seed / 4,500 seeds/lb seed x 85,00 seeds/A [pgs. 13, 81]

Cucumber: 0.00058 lb a.i./lb seed / 12,000 seeds/lb seed x 80,418 seeds/A [pgs. 25, 81]

Peas: 0.000625 lb a.i./lb seed / 1,361 seeds/lb seed x 653,400 seeds/A [pgs. 34, 82]

Pumpkin: 0.00058 lb a.i./lb seed / 1,600 seeds/lb seed x 7,260 seeds/A [pgs. 37, 82]

Sorghum: 0.001 lb a.i./lb seed / 11,000 seeds/lb seed x 100,000 seeds/A [pgs. 16, 39]

Triticale: 0.003 lb a.i./100 lb seed / 109 lb seed/A [pg.16]

Wheat: 0.003 lb a.i./100 lb seed /116 lb seed/A [pg. 16]

[ ] indicate assumptions that are made when the information is not specified but can be inferred
Appendix B: Residential Post-Application Dermal Steady State Exposure and Risk 

Estimates from Golfing - Post-application Dermal Algorithm
Page 89 of 227

Table B.1. Residential Post-Application Dermal Steady State Exposure and Risk Estimates from Golfing

Scenario

App. 

Rate 

(lb ai/A)

State TTR1

(μg/cm2)

Exposure

Time (hr) Population TC (cm2/hr)

Daily 

Exposure2

(mg/kg/day)

MOE

Emulsifiable Concentrate Formulation 

Golfing on 

Treated Turf 1.0

CA 0.029

1.0

Adults 5,300 0.010 1,200

Youths 11 to 

<16 yr old 4,400 0.010 1,400

Children 6 to 

<11 yr old 2,900 0.012 1,900

IN 0.023

Adults 5,300 0.0069 1,700

Youths 11 to 

<16 yr old 4,400 0.0069 2,000

Children 6 to 

<11 yr old 2,900 0.0082 2,800

MS 0.038

Adults 5,300 0.012 1,000

Youths 11 to 

<16 yr old 4,400 0.012 1,200

Children 6 to 

<11 yr old 2,900 0.014 1,600

Mean 

All 

States

0.031

Adults 5,300 0.0095 1,200

Youths 11 to 

<16 yr old 4,400 0.0096 1,500

Children 6 to 

<11 yr old 2,900 0.011 2,000

Granular Formulation

Golfing on 

Treated Turf

1.0

CA

0.029

1.0

Adults 5,300 0.0088 1,400

Youths 11 to 

<16 yr old 4,400 0.0088 1,600

Children 6 to 

<11 yr old 2,900 0.010 2,200

0.25 0.0071

Adults 5,300 0.0022 5,400

Youths 11 to 

<16 yr old 4,400 0.0022 6,300

Children 6 to 

<11 yr old 2,900 0.0026 8,800

1 TTR derived by using average Day 0 turf TTR residue data from TTR study (MRID 44829601). The study was conducted using emulsifiable 

concentrate application rates of 3.8 lb a.i./A, CA; 3.98 lb ai/A, IN; 3.83 lb ai/A, MS; and a mean value of 3.83 lb ai/A. The granular formulation 

(CA only) was conducted at a rate of 1.8 lb ai/A. Application rates have been adjusted for TTR calculation Adjusted TTR (μg/cm2) = [(Product 

Application Rate (lb ai/A)) ÷ (TTR Study Application Rate (lb ai/A) x (Measured Study TTR (μg/cm2)]

2 Daily Exposure = [Adjusted TTR (μg/cm2) x (0.001 mg/μg) x Dermal Transfer Coefficient x Dermal Absorption Factor (100%) x Exposure 

Time (4 hr)] 

3 MOE = PBPK-modeled PoD (mg/kg/day) ÷ Dose (mg/kg/day).
Page 90 of 227

Post-application Dermal Exposure Algorithm – Physical Activities on Turf

Exposure resulting from contacting previously treated turf while performing physical activities is 

calculated as shown below. Residential post-application exposure assessment must include 

calculation of exposure on the day of application. Therefore, though an assessment can present 

exposures for any day “t” following the application, it must include “day 0” exposure.

E = TTRt * CF1 * TC * ET

where:

E = exposure (mg/day);

TTRt = turf transferable residue on day t (μg/cm2);

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

TC = transfer coefficient (cm2/hr); and

ET = exposure time (hr/day).

If chemical-specific TTR data are available, then surface residues from the day of application 

should be used (assume that individuals could be exposed to residues immediately after 

application). TTR data available for the liquid and granular formulations of chlorpyrifos were 

used. 

Dermal absorbed doses are calculated as:

BW

E AF D*



where:

D = dose (mg/kg-day);

E = exposure (mg/day);

AF = absorption factor (dermal); and

BW = body weight (kg).

Table B.2. Turf (Physical Activities) -- Inputs for Residential Post-application Dermal Exposure

Algorithm Notation Exposure Factor

(units) Point Estimate(s)

AR

Application rate

(lb ai/A) - Liquid 1.0

Application rate

(lb ai/A) - Granular 1.0 and 0.25

TTR

The measured residue 

level anticipated to 

transfer from treated turf 

to the exposed individual

EC (Mississippi) 0.146

EC (California) 0.124

EC (Indiana) 0.090

EC (Mean) 0.120

Granules (California) 0.052

TC

Transfer 

Coefficient 

(cm2/hr)

L/WP/WDG

Adults 180,000

Children 1 < 2 years old 49,000

Granules Adults 200,000
Page 91 of 227

Table B.2. Turf (Physical Activities) -- Inputs for Residential Post-application Dermal Exposure

Algorithm Notation Exposure Factor

(units) Point Estimate(s)

Children 1 < 2 years old 54,000

ET Exposure Time

(hours per day)

Adults 1.5

Children 1 < 2 years old 1.5

BW Body Weight

(kg)

Adults 69

Children 1 < 2 years old 11

L/WP/WDG = Liquids/Wettable Powders/Water-dispersible Granules
Page 92 of 227

Appendix C: Residential Post-application Dermal, Inhalation, and Hand-to-Mouth 

Exposures and Risks from Chlorpyrifos Mosquitocide Application - 2012 Residential SOP 

Algorithms; Use of Well Mixed Box Model; AgDisp (V8.2.6) Inputs
Page 93 of 227

Table C.1. Residential Post-application Inhalation Steady State Exposure Estimates 

Resulting from Chlorpyrifos Mosquitocide Application

Population Air Concentration Estimate 

(mg/m3)

MOE2

Aerial ULV (100 ft release height) – AGDISP Model

Adults

0.000601

10,300

Children 1 to <2 years old 3,800

ULV Truck Fogger – WMB Model

Adults

0.0051

1,200

Children 1 to <2 years old 460

1 Air concentration estimate produced from AGDISP model v8.2.6 at breathing height of adults and children.

2 MOE = PoD (mg/kg/day) ÷ Dose (mg/kg/day).

3 PoD determined with use of PBPK modeling.

Table C.2: Residential Post-application Dermal Steady State Exposure Estimates 

Resulting from Chlorpyrifos Mosquitocide Application

Use

Site Application 

Rate

(lb ai/A)

AGDISP 

Deposition 

Fraction1

TTR 

Deposition 

Fraction2

Adjusted 

TTR3

(ug/ cm2)

Transfer 

Coefficient4

(cm2/hr)

Dermal Dose5

(mg/kg/day) MOE6,7

Adults

Air

0.010

0.35

0.0034

0.00013

180,000

0.00052 46,000

Ground 0.05 0.000019 0.000074 320,000

Children 1 to < 2 years old

Air

0.010

0.35

0.0034

0.00013

49,000

0.00088 150,000

Ground 0.05 0.000019 0.00013 1,100,000

1 Aerial fraction of mosquitocide application rate deposited on turf as determined using AgDISP model v8.2.6. Ground 

fraction of mosquitocide application rate deposited on turf as determined using two literature studies conducted to 

determine residue transfer following ground applications of malathion mosquitocide. 

2 Fraction of deposited chlorpyrifos anticipated to transfer to exposed individual as determined from chlorpyrifos TTR 

study. The recommended fraction, 0.34% (0.0034), is representative of the maximum residue transfer observed for all 

sites (MS data is highest) for the liquid (EC) formulated product. 

3 TTRt = AR (0.010 lb ai/A) x TTR Deposition Fraction (0.0034) x (1-FD)

t x CF2(4.54 x 108 μg/lb) x CF3(2.47 x 10-8

A/cm2) x AgDISP Deposition Fraction (0.35 or 0.05)

4 Transfer Coefficient (cm2/hr) = See Turf SOP In Appendix B

5 Dermal Dose (mg/kg/day) = [ (TTRt * CF1 (0.001 mg/μg) * TC * ET (1.5 hrs)) ] ÷ BW (kg)

6 MOE = POD (mg/kg/day) ÷ Dose (mg/kg/day)

7 PoD determined with use of PBPK modeling.
Page 94 of 227

Table C.3: Residential Post-application Steady State Incidental Oral Exposure Estimates Resulting

from Chlorpyrifos Mosquitocide Application

Lifestage

Post-application Exposure Scenario Application 

Rate

(mg ai)

Dermal 

Exposure 

(mg/day)1

Exposure 

Time

(hours/day)2

Incidental Oral 

Dose (mg/kg/day)3 MOE4

Use Site Route of Exposure

Children 

1 to < 2 

Years Old

Aerial 

Mosquitocide 

Application

Hand-to-Mouth

0.010

0.010

1.5

0.000018 5,600

Object-to-Mouth 5.5x10-7 180,000

Soil Ingestion 1.2x10-7 4,900,000

Ground 

Mosquitocide 

Application

Hand-to-Mouth

0.0014

2.6x10-6 39,000

Object-to-Mouth 7.9x10-8 1,300,000

Soil Ingestion 1.7x10-8 34,000,000

1 Dermal exposure (mg/day) as calculated for children’s aerial and ground based ULV applications using the algorithms 

described in Table XX above, and as described below in this Appendix. 

2 Daily exposure time as recommended in the 2012 Residential SOPs for time spent outdoors on treated turf. 

3 Incidental Oral Dose estimated using the algorithms as described below in this Appendix. 

4 MOE = POD (mg/kg/day) ÷ Dose (mg/kg/day)

Post-application Dermal and Incidental Oral Exposure Algorithms

Post-application Dermal Exposure Algorithm – Physical Activities on Turf

Exposure resulting from contacting turf while performing physical activities following 

deposition from aerial and ground based ULV mosquitocide applications is calculated as shown 

below. 

E = TTRt * CF1 * TC * ET

where:

E = exposure (mg/day);

TTRt = turf transferable residue on day t (μg/cm2);

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

TC = transfer coefficient (cm2/hr); and

ET = exposure time (hr/day).

Chemical-specific TTR data are available. Surface residues from the day of application were 

used (assuming that individuals could be exposed to residues immediately after application). 

TTRt= AR * F * (1-FD)t * CF2 * CF3

where:

TTRt = turf transferable residue on day t (μg/cm2);

AR = application rate (lbs ai/ft2or lb ai/acre);

F = fraction of ai as transferable residue following application (unitless);

FD = fraction of residue that dissipates daily (unitless);

t = post-application day on which exposure is being assessed;

CF2 = weight unit conversion factor (4.54 x 108 μg/lb); and

CF3 = area unit conversion factor (1.08 x 10-3ft2/ cm2or 2.47 x 10-8acre/cm2).
Page 95 of 227

Dermal absorbed doses are calculated as:

BW

E AF D*



where:

D = dose (mg/kg-day);

E = exposure (mg/day);

AF = absorption factor (dermal); and

BW = body weight (kg).

Table C.4: Turf (Physical Activities) -- Inputs for Residential Post-application Dermal Exposure

Algorithm Notation Exposure Factor

(units) Point Estimate(s)

AR Application rate

(mass active ingredient per unit area) 0.010 lb ai/A

FD

Fraction of ULV ground-based application deposited on 

turf (malathion data) 0.05

Fraction of fixed wing ULV application deposited on turf 

(AgDISP (v8.2.6)) 0.35

FAR

Fraction of AR as TTR following application (per 

chlorpyrifos specific TTR data – MS data set provides 

the most protective fraction)

0.0034 (0.34%)

TC

Transfer 

Coefficient 

(cm2/hr)

L/WP/WDG

Adults 180,000

Children 1 < 2 years old 49,000

Granules

Adults 200,000

Children 1 < 2 years old 54,000

ET Exposure Time

(hours per day)

Adults 1.5

Children 1 < 2 years old 1.5

BW Body Weight

(kg)

Adults 69

Children 1 < 2 years old 11

L/WP/WDG = Liquids/Wettable Powders/Water-dispersible Granules

Post-application Hand-to-Mouth Exposure Algorithm– Physical Activities on Turf

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

the SHEDS-Multimedia model):

E = [HR * (FM * SAH) * (ET * N_Replen) * (1- (1- SE)

(Freq_HtM/N-Replen))]

where:

E = exposure (mg/day);

HR = hand residue loading (mg/cm2);

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

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

ET = exposure time (hr/day);
Page 96 of 227

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

SA * 2

Fai *DE

HR

H

hands



where:

HR = hand residue loading (mg/cm2);

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

coefficient study (unitless);

DE = dermal exposure (mg); and

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

Dose, normalized to body weight, is calculated as:

BW

E

D 

where:

D = dose (mg/kg-day);

E = exposure (mg/day); and

BW = body weight (kg).

Table C.5: Turf (Physical Activities) – Inputs for Residential Post-application Hand-to-Mouth 

Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

Faihands

Fraction of ai on hands 

from dermal transfer 

coefficient study

(unitless)

Liquid formulations 0.06

DE Dermal exposure (mg) Calculated

SAH

Typical surface area of one hand (cm2), children 1 < 

2 years old 150

HR Residue available on the hands (mg/cm2) Calculated via (DE * Faihands)/SAH

FM

Fraction hand surface area mouthed

(fraction/event) 0.127

N_Replen Replenishment intervals per hour

(intervals/hr) 4

ET Exposure time 

(hrs/day) 1.5

SE Saliva extraction factor

(unitless) 0.48

Freq_HtM Hand-to-mouth events per hour

(events/hr) 13.9
Page 97 of 227

Table C.5: Turf (Physical Activities) – Inputs for Residential Post-application Hand-to-Mouth 

Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

BW Body Weight

(kg)

Children 1 < 2 years 

old 11

Post-application Inhalation Exposure Algorithm for Truck Mounted ULV – Well 

Mixed Box Model

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

mounted fogger sprays:

Q T

AR Air

*

[ ] 

where:

[Air] = air concentration (mg/m3);

AR = application rate (mg ai/day); 

Q = airflow through the treated area (m3/hour); and

T = time (duration) of exposure (hours).

Application rate for WMB analysis can be calculated as follows: 

AR* = AR * CF1* CF2 * CF3 

where:

AR* = application rate (mg ai/400 ft2)

AR = application rate (lb ai/A)

CF1 = unit conversion factor (454 g/lb)

CF2 = unit conversion factor (400ft2/43560 ft2 per acre)

 CF3 = unit conversion factor (1000mg/g) 

The airflow through the treated space can be calculated as follows:

Q = AV *CF1* CF2 * Across-section

where:

Q = airflow through treated space (m3/hr);

AV = air velocity (m/s);

CF1 = time unit conversion factor (60 seconds/1 minute);

CF2 = time unit conversion factor (60 minutes / hour); and

Across-section = cross-section of outdoor space treated (m2).
Page 98 of 227

Table C.6: Truck Mounted Mosquito Vector Control Fogger –Inputs for Residential Post-application 

Inhalation Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

AR Application rate (lb ai/A) 0.010

Across-section

Cross sectional area of area treated

(m2)

15

AV Air velocity

(m/s) 0.1

Q

Airflow through treated area

(m3/hr) 5,400

A.I. Percent ai in product

(%) 19.4%

T

Exposure duration (hours)

[equivalent to duration of inhalation toxicity 

study]

1.5

AgDisp Inputs (v8.2.6): 

 Application method: Aerial

 Aircraft: Air Tractor AT-401

 Release height: 300 ft

 Spray lines: 20 reps

 Application technique: 

o Nozzles: 3; vertical distance of nozzles from wing: 0 ft; horizontal distance from 

wing, 0, -18.7 ft; and horizontal distance limit: 76.3 percent. 

o Drop size distribution: User defined, DV0.5: 60.2 μm; and relative span: 1.4.

 Swath width: 500 ft

 Meteorology:

o Wind type: single height

o Wind speed: 1 mph

o Wind direction: -90 deg

o Temperature: 85 F°

o Relative humidity: 90%

 Spray material: chlorpyrifos; spray volume rate: 0.0068 gal/A; Active solution: 19.36 % 

of tank mix; fraction of solution that is nonvolatile: 1. 

 Atmospheric stability: overcast

 Surface:

o Upslope angle: 0 deg

o Sideslope angle: 0 deg

 Transport: 

o Distance: 0 ft.
Page 99 of 227

Appendix D. Summaries of Adult and Children 1 to < 2 Years Old Spray Drift Risk 

Estimates and Buffers for Chlorpyrifos
Table D.1. Summary of Adult Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC is an MOE = 100

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 

125 

Feet 150 Feet 200 Feet 

250 

Feet 

300 

Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Airblast

Sparse

6.0 0.23

180 320 600 1,300 2,400 3,900 5,900 8,200 15,000 24,000 33,000

Normal 8,800 13,000 20,000 29,000 44,000 53,000 66,000 88,000 88,000 130,000 130,000

Dense 620 950 1,500 2,600 3,900 5,400 6,800 8,200 11,000 15,000 18,000

Vineyard 3,300 6,400 12,000 22,000 33,000 44,000 53,000 66,000 88,000 130,000 130,000

Ground

-boom

High 

Boom Very 

fine to 

Fine

4.3 0.16

200 400 660 1,100 1,500 1,800 2,200 2,600 3,300 4,600 5,300

Low Boom 

Very fine 

to Fine

430 1,100 1,800 2,800 3,700 4,600 5,300 6,100 7,400 9,200 12,000

High Boom 

Fine to 

Medium/

Coarse

750 1,900 2,800 4,100 5,300 6,100 7,400 7,400 9,200 12,000 12,000

Low Boom 

Fine to 

Medium/

Coarse

1,100 3,100 4,600 6,100 7,400 9,200 12,000 12,000 18,000 18,000 18,000

Airblast

Sparse 260 440 830 1,800 3,300 5,400 8,200 11,000 20,000 33,000 46,000

Normal 12,000 18,000 28,000 41,000 61,000 74,000 92,000 120,000 120,000 180,000 180,000

Dense 870 1,300 2,100 3,700 5,500 7,500 9,400 11,000 16,000 20,000 25,000

Vineyard 4,600 9,000 17,000 31,000 46,000 61,000 74,000 92,000 120,000 180,000 180,000
Page 101 of 227

Table D.1. Summary of Adult Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC is an MOE = 100

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 

125 

Feet 150 Feet 200 Feet 

250 

Feet 

300 

Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Ground

-boom

High 

Boom Very 

fine to 

Fine

4.0 0.15

210 430 710 1,100 1,600 2,000 2,300 2,800 3,600 4,900 5,700

Low Boom 

Very fine 

to Fine

470 1,200 2,000 3,000 4,000 4,900 5,700 6,600 7,900 9,900 13,000

High Boom 

Fine to 

Medium/

Coarse

810 2,100 3,000 4,400 5,700 6,600 7,900 7,900 9,900 13,000 13,000

Low Boom 

Fine to 

Medium/

Coarse

1,200 3,300 4,900 6,600 7,900 9,900 13,000 13,000 20,000 20,000 20,000

Airblast

Sparse 280 470 890 2,000 3,600 5,800 8,800 12,000 22,000 36,000 49,000

Normal 13,000 20,000 30,000 44,000 66,000 79,000 99,000 130,000 130,000 200,000 200,000

Dense 940 1,400 2,300 4,000 5,900 8,100 10,000 12,000 17,000 22,000 26,000

Vineyard 4,900 9,600 18,000 33,000 49,000 66,000 79,000 99,000 130,000 200,000 200,000

Ground

boom

High 

Boom Very 

fine to 

Fine

3.76 0.14

230 450 750 1,200 1,700 2,100 2,500 3,000 3,800 5,300 6,000

Low Boom 

Very fine 

to Fine

500 1,300 2,100 3,200 4,200 5,300 6,000 7,000 8,400 11,000 14,000

High Boom 

Fine to 

Medium/

Coarse

860 2,200 3,200 4,700 6,000 7,000 8,400 8,400 11,000 14,000 14,000

Low Boom 

Fine to 

Medium/

Coarse

1,300 3,500 5,300 7,000 8,400 11,000 14,000 14,000 21,000 21,000 21,000
Page 102 of 227

Table D.1. Summary of Adult Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC is an MOE = 100

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 

125 

Feet 150 Feet 200 Feet 

250 

Feet 

300 

Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Airblast

Sparse 290 500 950 2,100 3,800 6,200 9,400 13,000 23,000 38,000 53,000

Normal 14,000 21,000 32,000 47,000 70,000 84,000 110,000 140,000 140,000 210,000 210,000

Dense 1,000 1,500 2,400 4,200 6,300 8,600 11,000 13,000 18,000 23,000 28,000

Vineyard 5,300 10,000 19,000 35,000 53,000 70,000 84,000 110,000 140,000 210,000 210,000

Ground

-boom

High 

Boom Very 

fine to 

Fine

3.0 0.11

280 570 940 1,500 2,100 2,600 3,100 3,800 4,800 6,600 7,500

Low Boom 

Very fine 

to Fine

620 1,600 2,600 4,100 5,300 6,600 7,500 8,800 11,000 13,000 18,000

High Boom 

Fine to 

Medium/

Coarse

1,100 2,800 4,100 5,900 7,500 8,800 11,000 11,000 13,000 18,000 18,000

Low Boom 

Fine to 

Medium/

Coarse

1,600 4,400 6,600 8,800 11,000 13,000 18,000 18,000 26,000 26,000 26,000

Airblast

Sparse 370 630 1,200 2,600 4,800 7,800 12,000 16,000 29,000 48,000 66,000

Normal 18,000 26,000 41,000 59,000 88,000 110,000 130,000 180,000 180,000 260,000 260,000

Dense 1,200 1,900 3,000 5,300 7,900 11,000 14,000 16,000 23,000 29,000 35,000

Vineyard 6,600 13,000 24,000 44,000 66,000 88,000 110,000 130,000 180,000 260,000 260,000

Aerial

Fine to 

Medium

2.3 0.088

270 330 410 530 700 910 1,100 1,300 1,700 2,000 2,500

Medium to 

Coarse 330 440 600 840 1,200 1,600 2,000 2,400 3,300 4,300 5,300

Coarse to 

Very 

Coarse

380 550 840 1,300 1,900 2,500 3,100 3,800 5,300 6,900 8,600
Page 103 of 227

Table D.1. Summary of Adult Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC is an MOE = 100

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 

125 

Feet 150 Feet 200 Feet 

250 

Feet 

300 

Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Very Fine 

to Fine 180 200 230 260 300 350 390 440 540 640 720

AT401, M, 

10 mph, 

37% SD

290 380 480 660 880 1,100 1,400 1,600 2,100 2,600 3,300

WASP, M, 

10 mph, 

37% SD

320 400 530 800 1,100 1,400 1,700 2,000 2,600 3,300 3,800

AT401, C, 

10 mph, 

25% SD

350 490 690 1,000 1,500 1,900 2,400 2,900 4,000 5,300 6,300

WASP, C, 

10 mph, 

25% SD

400 570 820 1,300 1,800 2,500 3,000 3,800 5,300 6,900 7,600

AT401, 

VC, 10 

mph, 20% 

SD

390 600 960 1,600 2,200 3,000 3,800 4,900 6,900 8,600 11,000

WASP, 

VC, 10 

mph, 20% 

SD

500 780 1,200 1,900 2,800 3,600 4,900 5,700 8,600 9,800 11,000

Ground

boom

High 

Boom Very 

fine to 

Fine

370 740 1,200 2,000 2,800 3,400 4,000 4,900 6,300 8,600 9,800

Low Boom 

Very fine 

to Fine

810 2,100 3,400 5,300 6,900 8,600 9,800 11,000 14,000 17,000 23,000

High Boom 

Fine to 

Medium/

Coarse

1,400 3,600 5,300 7,600 9,800 11,000 14,000 14,000 17,000 23,000 23,000

Low Boom 

Fine to 

Medium/

Coarse

2,100 5,700 8,600 11,000 14,000 17,000 23,000 23,000 34,000 34,000 34,000
Page 104 of 227

Table D.1. Summary of Adult Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC is an MOE = 100

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 

125 

Feet 150 Feet 200 Feet 

250 

Feet 

300 

Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Airblast

Sparse 480 820 1,600 3,400 6,300 10,000 15,000 21,000 38,000 63,000 86,000

Normal 23,000 34,000 53,000 76,000 110,000 140,000 170,000 230,000 230,000 340,000 340,000

Dense 1,600 2,500 3,900 6,900 10,000 14,000 18,000 21,000 30,000 38,000 46,000

Vineyard 8,600 17,000 31,000 57,000 86,000 110,000 140,000 170,000 230,000 340,000 340,000

Aerial

Fine to 

Medium

2 0.076

310 380 470 610 810 1,000 1,300 1,500 1,900 2,300 2,800

Medium to 

Coarse 370 510 690 960 1,400 1,800 2,300 2,700 3,800 4,900 6,100

Coarse to 

Very 

Coarse

430 640 960 1,500 2,100 2,800 3,600 4,400 6,100 7,900 9,900

Very Fine 

to Fine 210 230 260 300 350 400 450 510 620 730 830

AT401, M, 

10 mph, 

37% SD

340 430 560 750 1,000 1,300 1,600 1,900 2,500 3,000 3,800

WASP, M, 

10 mph, 

37% SD

360 460 610 920 1,300 1,600 2,000 2,300 3,000 3,800 4,400

AT401, C, 

10 mph, 

25% SD

400 560 800 1,200 1,700 2,200 2,700 3,300 4,700 6,100 7,200

WASP, C, 

10 mph, 

25% SD

460 650 940 1,500 2,100 2,800 3,400 4,400 6,100 7,900 8,800

AT401, 

VC, 10 

mph, 20% 

SD

450 690 1,100 1,800 2,600 3,400 4,400 5,700 7,900 9,900 13,000

WASP, 

VC, 10 

mph, 20% 

570 900 1,400 2,200 3,200 4,200 5,700 6,600 9,900 11,000 13,000
Page 105 of 227

Table D.1. Summary of Adult Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC is an MOE = 100

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 

125 

Feet 150 Feet 200 Feet 

250 

Feet 

300 

Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

SD

Ground

boom

High 

Boom Very 

fine to 

Fine

420 850 1,400 2,300 3,200 4,000 4,700 5,700 7,200 9,900 11,000

Low Boom 

Very fine 

to Fine

930 2,500 4,000 6,100 7,900 9,900 11,000 13,000 16,000 20,000 26,000

High Boom 

Fine to 

Medium/

Coarse

1,600 4,200 6,100 8,800 11,000 13,000 16,000 16,000 20,000 26,000 26,000

Low Boom 

Fine to 

Medium/

Coarse

2,400 6,600 9,900 13,000 16,000 20,000 26,000 26,000 40,000 40,000 40,000

Airblast

Sparse 550 950 1,800 4,000 7,200 12,000 18,000 25,000 44,000 72,000 99,000

Normal 26,000 40,000 61,000 88,000 130,000 160,000 200,000 260,000 260,000 400,000 400,000

Dense 1,900 2,800 4,500 7,900 12,000 16,000 20,000 25,000 34,000 44,000 53,000

Vineyard 9,900 19,000 36,000 66,000 99,000 130,000 160,000 200,000 260,000 400,000 400,000

Aerial

Fine to 

Medium

1.5 0.057

410 500 620 820 1,100 1,400 1,700 2,000 2,600 3,100 3,800

Medium to 

Coarse 500 680 920 1,300 1,800 2,400 3,000 3,600 5,000 6,600 8,100

Coarse to 

Very 

Coarse

580 850 1,300 2,000 2,900 3,800 4,800 5,900 8,100 11,000 13,000

Very Fine 

to Fine 280 310 350 400 470 540 600 680 830 980 1,100

AT401, M, 

10 mph, 

37% SD

450 580 740 1,000 1,400 1,800 2,200 2,500 3,300 4,100 5,000
Page 106 of 227

Table D.1. Summary of Adult Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC is an MOE = 100

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 

125 

Feet 150 Feet 200 Feet 

250 

Feet 

300 

Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

WASP, M, 

10 mph, 

37% SD

480 620 820 1,200 1,700 2,200 2,600 3,100 4,100 5,000 5,900

AT401, C, 

10 mph, 

25% SD

530 750 1,100 1,600 2,200 2,900 3,600 4,400 6,200 8,100 9,600

WASP, C, 

10 mph, 

25% SD

620 870 1,300 2,000 2,800 3,800 4,600 5,900 8,100 11,000 12,000

AT401, 

VC, 10 

mph, 20% 

SD

600 920 1,500 2,400 3,400 4,600 5,900 7,500 11,000 13,000 18,000

WASP, 

VC, 10 

mph, 20% 

SD

760 1,200 1,900 2,900 4,200 5,600 7,500 8,800 13,000 15,000 18,000

Ground

boom

High 

Boom Very 

fine to 

Fine

560 1,100 1,900 3,000 4,200 5,300 6,200 7,500 9,600 13,000 15,000

Low Boom 

Very fine 

to Fine

1,200 3,300 5,300 8,100 11,000 13,000 15,000 18,000 21,000 26,000 35,000

High Boom 

Fine to 

Medium/

Coarse

2,200 5,600 8,100 12,000 15,000 18,000 21,000 21,000 26,000 35,000 35,000

Low Boom 

Fine to 

Medium/

Coarse

3,200 8,800 13,000 18,000 21,000 26,000 35,000 35,000 53,000 53,000 53,000

Airblast

Sparse 740 1,300 2,400 5,300 9,600 16,000 23,000 33,000 59,000 96,000 130,000

Normal 35,000 53,000 81,000 120,000 180,000 210,000 260,000 350,000 350,000 530,000 530,000

Dense 2,500 3,800 6,000 11,000 16,000 22,000 27,000 33,000 46,000 59,000 70,000
Page 107 of 227

Table D.1. Summary of Adult Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC is an MOE = 100

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 

125 

Feet 150 Feet 200 Feet 

250 

Feet 

300 

Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Vineyard 13,000 26,000 48,000 88,000 130,000 180,000 210,000 260,000 350,000 530,000 530,000

Aerial

Fine to 

Medium

1 0.038

620 760 940 1,200 1,600 2,100 2,500 2,900 3,900 4,700 5,700

Medium to 

Coarse 750 1,000 1,400 1,900 2,700 3,600 4,500 5,500 7,500 9,900 12,000

Coarse to 

Very 

Coarse

860 1,300 1,900 3,000 4,300 5,700 7,200 8,800 12,000 16,000 20,000

Very Fine 

to Fine 420 470 520 600 700 800 900 1,000 1,200 1,500 1,700

AT401, M, 

10 mph, 

37% SD

680 860 1,100 1,500 2,000 2,600 3,200 3,800 4,900 6,100 7,500

WASP, M, 

10 mph, 

37% SD

730 930 1,200 1,800 2,500 3,200 4,000 4,700 6,100 7,500 8,800

AT401, C, 

10 mph, 

25% SD

800 1,100 1,600 2,400 3,400 4,400 5,500 6,600 9,300 12,000 14,000

WASP, C, 

10 mph, 

25% SD

930 1,300 1,900 3,000 4,200 5,700 6,900 8,800 12,000 16,000 18,000

AT401, 

VC, 10 

mph, 20% 

SD

900 1,400 2,200 3,600 5,100 6,900 8,800 11,000 16,000 20,000 26,000

WASP, 

VC, 10 

mph, 20% 

SD

1,100 1,800 2,800 4,400 6,300 8,300 11,000 13,000 20,000 23,000 26,000

Ground

boom

High 

Boom Very 

fine to 

Fine

850 1,700 2,800 4,500 6,300 7,900 9,300 11,000 14,000 20,000 23,000

Low Boom 1,900 4,900 7,900 12,000 16,000 20,000 23,000 26,000 32,000 40,000 53,000
Page 108 of 227

Table D.1. Summary of Adult Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC is an MOE = 100

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 

125 

Feet 150 Feet 200 Feet 

250 

Feet 

300 

Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Very fine 

to Fine

High Boom 

Fine to 

Medium/

Coarse

3,200 8,300 12,000 18,000 23,000 26,000 32,000 32,000 40,000 53,000 53,000

Low Boom 

Fine to 

Medium/

Coarse

4,800 13,000 20,000 26,000 32,000 40,000 53,000 53,000 79,000 79,000 79,000

Airblast

Sparse 1,100 1,900 3,600 7,900 14,000 23,000 35,000 49,000 88,000 140,000 200,000

Normal 53,000 79,000 120,000 180,000 260,000 320,000 400,000 530,000 530,000 790,000 790,000

Dense 3,700 5,700 9,000 16,000 24,000 32,000 41,000 49,000 69,000 88,000 110,000

Vineyard 20,000 39,000 72,000 130,000 200,000 260,000 320,000 400,000 530,000 790,000 790,000
Table D.2. Summary of Children 1 to < 2 Years Old Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC 

is an MOE = 40

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet 150 Feet 

200 

Feet 250 Feet 300 Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Airblast

Sparse

6.0 0.23

22 37 70 160 280 460 690 970 1,700 2,800 3,900 

Normal 1,000 1,600 2,400 3,500 5,200 6,200 7,800 10,000 10,000 16,000 16,000 

Dense 74 110 180 310 460 630 800 970 1,400 1,700 2,100 

Vineyard 390 760 1,400 2,600 3,900 5,200 6,200 7,800 10,000 16,000 16,000 

Ground

-boom

High 

Boom Very 

fine to 

Fine

4.3 0.16

23 47 77 120 170 220 260 310 390 540 620 

Low Boom 

Very fine 

to Fine

51 140 220 330 430 540 620 720 870 1,100 1,400 

High Boom 

Fine to 

Medium/

Coarse

89 230 330 480 620 720 870 870 1,100 1,400 1,400 

Low Boom 

Fine to 

Medium/

Coarse

130 360 540 720 870 1,100 1,400 1,400 2,200 2,200 2,200 

Airblast

Sparse 30 52 98 220 390 640 960 1,400 2,400 3,900 5,400 

Normal 1,400 2,200 3,300 4,800 7,200 8,700 11,000 14,000 14,000 22,000 22,000 

Dense 100 160 250 430 650 890 1,100 1,400 1,900 2,400 2,900 

Vineyard 540 1,100 2,000 3,600 5,400 7,200 8,700 11,000 14,000 22,000 22,000 

Ground

-boom

High 

Boom Very 

fine to 

Fine

4.0 0.15 25 50 83 130 190 230 270 330 420 580 670
Page 110 of 227

Table D.2. Summary of Children 1 to < 2 Years Old Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC 

is an MOE = 40

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet 150 Feet 

200 

Feet 250 Feet 300 Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Low Boom 

Very fine 

to Fine

55 150 230 360 470 580 670 780 930 1,200 1,600

High Boom 

Fine to 

Medium/

Coarse

95 250 360 520 670 780 930 930 1,200 1,600 1,600

Low Boom 

Fine to 

Medium/

Coarse

140 390 580 780 930 1,200 1,600 1,600 2,300 2,300 2,300

Airblast

Sparse 32 56 110 230 420 690 1,000 1,500 2,600 4,200 5,800

Normal 1,600 2,300 3,600 5,200 7,800 9,300 12,000 16,000 16,000 23,000 23,000

Dense 110 170 270 470 700 950 1,200 1,500 2,000 2,600 3,100

Vineyard 580 1,100 2,100 3,900 5,800 7,800 9,300 12,000 16,000 23,000 23,000

Ground

boom

High 

Boom Very 

fine to 

Fine

3.76 0.14

27 53 89 140 200 250 290 350 450 620 710

Low Boom 

Very fine 

to Fine

58 160 250 380 500 620 710 830 990 1,200 1,700

High Boom 

Fine to 

Medium/

Coarse

100 260 380 550 710 830 990 990 1,200 1,700 1,700

Low Boom 

Fine to 

Medium/

Coarse

150 410 620 830 990 1,200 1,700 1,700 2,500 2,500 2,500
Page 111 of 227

Table D.2. Summary of Children 1 to < 2 Years Old Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC 

is an MOE = 40

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet 150 Feet 

200 

Feet 250 Feet 300 Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Airblast

Sparse 35 59 110 250 450 730 1,100 1,600 2,800 4,500 6,200

Normal 1,700 2,500 3,800 5,500 8,300 9,900 12,000 17,000 17,000 25,000 25,000

Dense 120 180 280 500 740 1,000 1,300 1,600 2,200 2,800 3,300

Vineyard 620 1,200 2,300 4,100 6,200 8,300 9,900 12,000 17,000 25,000 25,000

Ground

-boom

High 

Boom Very 

fine to 

Fine

3.0 0.11

33 67 110 180 250 310 370 440 570 780 890

Low Boom 

Very fine 

to Fine

73 190 310 480 620 780 890 1,000 1,200 1,600 2,100

High Boom 

Fine to 

Medium/

Coarse

130 330 480 690 890 1,000 1,200 1,200 1,600 2,100 2,100

Low Boom 

Fine to 

Medium/

Coarse

190 520 780 1,000 1,200 1,600 2,100 2,100 3,100 3,100 3,100

Airblast

Sparse 43 75 140 310 570 910 1,400 1,900 3,500 5,700 7,800

Normal 2,100 3,100 4,800 6,900 10,000 12,000 16,000 21,000 21,000 31,000 31,000

Dense 150 220 360 620 930 1,300 1,600 1,900 2,700 3,500 4,100

Vineyard 780 1,500 2,800 5,200 7,800 10,000 12,000 16,000 21,000 31,000 31,000

Aerial

Fine to 

Medium

2.3 0.088

32 39 48 63 83 110 130 150 200 240 290

Medium to 

Coarse 38 52 71 99 140 180 230 280 390 510 620

Coarse to 

Very 

Coarse

44 65 99 150 220 290 370 450 620 810 1,000
Page 112 of 227

Table D.2. Summary of Children 1 to < 2 Years Old Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC 

is an MOE = 40

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet 150 Feet 

200 

Feet 250 Feet 300 Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Very Fine 

to Fine 22 24 27 31 36 41 46 52 64 75 85

AT401, M, 

10 mph, 

37% SD

35 44 57 77 100 140 170 190 250 310 390

WASP, M, 

10 mph, 

37% SD

37 47 63 94 130 170 200 240 310 390 450

AT401, C, 

10 mph, 

25% SD

41 58 82 120 170 230 280 340 480 620 740

WASP, C, 

10 mph, 

25% SD

47 67 97 150 210 290 350 450 620 810 900

AT401, 

VC, 10 

mph, 20% 

SD

46 71 110 180 260 350 450 580 810 1,000 1,400

WASP, 

VC, 10 

mph, 20% 

SD

59 92 140 230 320 430 580 680 1,000 1,200 1,400

Ground

boom

High 

Boom Very 

fine to 

Fine

43 87 140 230 320 410 480 580 740 1,000 1,200

Low Boom 

Very fine 

to Fine

95 250 410 620 810 1,000 1,200 1,400 1,600 2,000 2,700

High Boom 

Fine to 

Medium/

Coarse

170 430 620 900 1,200 1,400 1,600 1,600 2,000 2,700 2,700

Low Boom 

Fine to 

Medium/

250 680 1,000 1,400 1,600 2,000 2,700 2,700 4,100 4,100 4,100
Page 113 of 227

Table D.2. Summary of Children 1 to < 2 Years Old Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC 

is an MOE = 40

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet 150 Feet 

200 

Feet 250 Feet 300 Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Coarse

Airblast

Sparse 57 97 180 410 740 1,200 1,800 2,500 4,500 7,400 10,000

Normal 2,700 4,100 6,200 9,000 14,000 16,000 20,000 27,000 27,000 41,000 41,000

Dense 190 290 460 810 1,200 1,700 2,100 2,500 3,500 4,500 5,400

Vineyard 1,000 2,000 3,700 6,800 10,000 14,000 16,000 20,000 27,000 41,000 41,000

Aerial

Fine to 

Medium

2 0.076

36 45 55 72 95 120 150 170 230 270 330

Medium to 

Coarse 44 60 81 110 160 210 270 320 440 580 720

Coarse to 

Very 

Coarse

51 75 110 180 250 330 420 520 720 930 1,200

Very Fine 

to Fine 25 27 31 36 41 47 53 60 73 86 98

AT401, M, 

10 mph, 

37% SD

40 51 66 89 120 160 190 220 290 360 440

WASP, M, 

10 mph, 

37% SD

43 55 72 110 150 190 230 270 360 440 520

AT401, C, 

10 mph, 

25% SD

47 66 94 140 200 260 320 390 550 720 850

WASP, C, 

10 mph, 

25% SD

55 77 110 180 250 330 410 520 720 930 1,000

AT401, 

VC, 10 

mph, 20% 

SD

53 81 130 210 300 410 520 670 930 1,200 1,600

WASP, 68 110 160 260 370 490 670 780 1,200 1,300 1,600
Page 114 of 227

Table D.2. Summary of Children 1 to < 2 Years Old Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC 

is an MOE = 40

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet 150 Feet 

200 

Feet 250 Feet 300 Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

VC, 10 

mph, 20% 

SD

Ground

boom

High 

Boom Very 

fine to 

Fine

50 100 170 270 370 470 550 670 850 1,200 1,300

Low Boom 

Very fine 

to Fine

110 290 470 720 930 1,200 1,300 1,600 1,900 2,300 3,100

High Boom 

Fine to 

Medium/

Coarse

190 490 720 1,000 1,300 1,600 1,900 1,900 2,300 3,100 3,100

Low Boom 

Fine to 

Medium/

Coarse

280 780 1,200 1,600 1,900 2,300 3,100 3,100 4,700 4,700 4,700

Airblast

Sparse 65 110 210 470 850 1,400 2,100 2,900 5,200 8,500 12,000

Normal 3,100 4,700 7,200 10,000 16,000 19,000 23,000 31,000 31,000 47,000 47,000

Dense 220 330 530 930 1,400 1,900 2,400 2,900 4,100 5,200 6,200

Vineyard 1,200 2,300 4,200 7,800 12,000 16,000 19,000 23,000 31,000 47,000 47,000

Aerial

Fine to 

Medium

1.5 0.057

48 60 74 96 130 160 200 230 300 370 440

Medium to 

Coarse 59 80 110 150 210 280 360 430 590 780 960

Coarse to 

Very 68 100 150 230 340 440 570 690 960 1,200 1,600
Page 115 of 227

Table D.2. Summary of Children 1 to < 2 Years Old Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC 

is an MOE = 40

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet 150 Feet 

200 

Feet 250 Feet 300 Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Coarse

Very Fine 

to Fine 33 37 41 47 55 63 71 80 98 120 130

AT401, M, 

10 mph, 

37% SD

53 68 88 120 160 210 250 300 390 480 590

WASP, M, 

10 mph, 

37% SD

57 73 96 140 200 250 310 370 480 590 690

AT401, C, 

10 mph, 

25% SD

63 88 130 190 260 350 430 520 730 960 1,100

WASP, C, 

10 mph, 

25% SD

73 100 150 230 330 440 540 690 960 1,200 1,400

AT401, 

VC, 10 

mph, 20% 

SD

71 110 170 280 400 540 690 890 1,200 1,600 2,100

WASP, 

VC, 10 

mph, 20% 

SD

90 140 220 350 500 650 890 1,000 1,600 1,800 2,100

Ground

boom

High 

Boom Very 

fine to 

Fine

67 130 220 360 500 620 730 890 1,100 1,600 1,800

Low Boom 

Very fine 

to Fine

150 390 620 960 1,200 1,600 1,800 2,100 2,500 3,100 4,100

High Boom 

Fine to 

Medium/

Coarse

250 650 960 1,400 1,800 2,100 2,500 2,500 3,100 4,100 4,100
Page 116 of 227

Table D.2. Summary of Children 1 to < 2 Years Old Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC 

is an MOE = 40

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet 150 Feet 

200 

Feet 250 Feet 300 Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Low Boom 

Fine to 

Medium/

Coarse

380 1,000 1,600 2,100 2,500 3,100 4,100 4,100 6,200 6,200 6,200

Airblast

Sparse 87 150 280 620 1,100 1,800 2,800 3,900 6,900 11,000 16,000

Normal 4,100 6,200 9,600 14,000 21,000 25,000 31,000 41,000 41,000 62,000 62,000

Dense 290 450 710 1,200 1,900 2,500 3,200 3,900 5,400 6,900 8,300

Vineyard 1,600 3,000 5,700 10,000 16,000 21,000 25,000 31,000 41,000 62,000 62,000

Aerial

Fine to 

Medium

1 0.038

73 89 110 140 190 250 300 350 450 550 670

Medium to 

Coarse 88 120 160 230 320 420 530 640 890 1,200 1,400

Coarse to 

Very 

Coarse

100 150 230 350 500 670 850 1,000 1,400 1,900 2,300

Very Fine 

to Fine 50 55 61 71 83 95 110 120 150 170 200

AT401, M, 

10 mph, 

37% SD

80 100 130 180 240 310 380 440 580 720 890

WASP, M, 

10 mph, 

37% SD

86 110 140 220 300 380 470 550 720 890 1,000

AT401, C, 

10 mph, 

25% SD

94 130 190 280 400 520 640 780 1,100 1,400 1,700

WASP, C, 

10 mph, 

25% SD

110 150 220 350 490 670 810 1,000 1,400 1,900 2,100

AT401, 

VC, 10 

mph, 20% 

SD

110 160 260 420 600 810 1,000 1,300 1,900 2,300 3,100
Page 117 of 227

Table D.2. Summary of Children 1 to < 2 Years Old Spray Drift Risk Estimates and Required Buffers for Chlorpyrifos: LOC 

is an MOE = 40

Crop/

Rate 

Group

Spray 

Type/ 

Nozzle 

Configurat

ion 

App.

Rate (lb 

ai/A)

Est. or 

Adjusted 

TTR 

(ug/cm2)

At 

Edge 10 Feet 25 Feet 50 Feet 75 Feet 100 Feet 125 Feet 150 Feet 

200 

Feet 250 Feet 300 Feet 

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

Dermal 

MOE

WASP, 

VC, 10 

mph, 20% 

SD

140 210 330 520 750 980 1,300 1,600 2,300 2,700 3,100

Ground

boom

High 

Boom Very 

fine to 

Fine

100 200 330 530 750 930 1,100 1,300 1,700 2,300 2,700

Low Boom 

Very fine 

to Fine

220 580 930 1,400 1,900 2,300 2,700 3,100 3,700 4,700 6,200

High Boom 

Fine to 

Medium/

Coarse

380 980 1,400 2,100 2,700 3,100 3,700 3,700 4,700 6,200 6,200

Low Boom 

Fine to 

Medium

/Coarse

570 1,600 2,300 3,100 3,700 4,700 6,200 6,200 9,300 9,300 9,300

Airblast

Sparse 130 220 420 930 1,700 2,700 4,100 5,800 10,000 17,000 23,000

Normal 6,200 9,300 14,000 21,000 31,000 37,000 47,000 62,000 62,000 93,000 93,000

Dense 440 670 1,100 1,900 2,800 3,800 4,800 5,800 8,100 10,000 12,000

Vineyard 2,300 4,500 8,500 16,000 23,000 31,000 37,000 47,000 62,000 93,000 93,000
Appendix E: Detailed Background Information on Columbia Cohort Dose Reconstruction
Page 119 of 227

Introduction

In order to better understand the possible exposure patterns in the Columbia University study 

cohort and their influence on the health outcomes identified in the research, an analysis was 

conducted to supplement the exposure metrics reported by the Columbia investigators. The goal 

was to predict potential exposures which could have occurred to pregnant women and young 

children who may have been exposed to chlorpyrifos through other pathways not addressed in 

the research then determine their potential for associated cholinesterase inhibition. 

Chlorpyrifos, at the time, was one of the most widely used insecticides for indoor pest control so 

there are many possible ways which exposures could have occurred as a result of these types of 

uses (e.g., use of a total release fogger, aerosol can sprays, or crack and crevice treatment by a 

pest control operator). This analysis was based on the Agency’s SOPs for Residential Exposure 

Assessment32 which describe, on a scenario basis, specific algorithms and data used to predict the 

potential exposures which could have occurred to individuals in the cohort. Once complete, the 

resulting dose estimates were used to evaluate the potential level of cholinesterase inhibition 

which could be attributed to them using the PBPK-PD model. The scenarios which were 

considered include:

 Pregnant mothers who may have purchased a consumer aerosol can product and applied 

it in their homes;

 Exposures to pregnant mothers who may have had contact with residues in their homes 

after a previous treatment which leads to exposure; and

 Exposures to young children (aged 1 to 2 years old) who may have contact with residues 

in their homes after a previous treatment which leads to exposure.

This appendix describes the details of those calculations.

Use Profile

In order to evaluate the chlorpyrifos exposure potential for the Columbia study cohort, it was 

first necessary to define what chlorpyrifos products would have been in use during the time of 

study conduct which spanned from 1998 to 2004. In 1997, the registrant, Dow AgroSciences, 

voluntarily agreed to cancel chlorpyrifos registrations for indoor broadcast use and direct pet 

treatments, except pet collars. In December 2001, the majority of the remaining chlorpyrifos 

residential products -- except for fully contained ant baits in child resistant packaging and limited 

public health uses -- were subject to voluntary phase out/cancellation. This analysis 

reconstructed the potential exposures for those in the cohort between the years 1997-2001 based 

on the chlorpyrifos uses that remained after the voluntary cancellation in 1997 and the phase out 

in 2001. The exposure questionnaire-based reported use from the Columbia publications was 

also used to inform this process. Per the publications, pest control measures were used by 92% 

of respondents, whether by housing superintendent, pest control operator (PCO), or by 

themselves. Of these, respondents reported that 39% were by PCO, 26% by spray can, and 5% 

foggers/bombs. The majority reported regular use of a pesticide product, at least once per 

 

32 http://www.epa.gov/pesticides/science/residential-exposure-sop.html
Page 120 of 227

month. Unfortunately, while these data help inform the types of products used, they do not allow 

for the determination of what pesticide active ingredient(s) were used. Multiple active 

ingredients were in regular use during this time period including, chlorpyrifos, diazinon, and 

propoxur, among others. For the purpose of the dose reconstruction exercise, it was assumed 

that only chlorpyrifos applications occurred. Considering all the available information, the 

potential for chlorpyrifos exposures from use of the following chlorpyrifos product types were 

assessed: broadcast ready to use (RTU) sprays applied by individual themselves and not 

professional applicators; surface sprays applied by individuals; crack and crevice sprays applied 

by individuals themselves or professional pest control applicators; and foggers/bombs applied by 

individuals. These chlorpyrifos residential products contained either 0.5% or 1% active 

ingredient. The latter was assumed to ensure an assessment reflective of the highest potential 

exposures, or those most likely to result in the greatest % RBC AChE inhibition. 

Exposure Assessment Methods

With the products and application rates defined, the 2012 Standard Operating Procedures for 

Residential Pesticide Exposure Assessment33 were used to assess the exposures that may have 

occurred from these indoor residential chlorpyrifos uses. Based on the use patterns of the 

defined products, it is expected that exposures occurred either from the application (handling) of 

products by those in the cohort or after applications from being in contact with previously treated 

indoor environments. 

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

handler and post-application exposure assessment:

 maximum application rates allowed by labels in its risk assessments are assumed;

 the use of personal protective equipment is not considered in residential risk 

assessments; 

 residential assessments are based on the assumption that individuals are wearing shorts, 

short-sleeved shirts, socks, and shoes;

 adults are assumed to perform all pesticide applications;

 the mean female bodyweight reflective of all trimesters of pregnancy, 75 kg, was 

assumed for pregnant women to reflect the population of interest from the Columbia 

cohort being evaluated which was derived from the EPA Exposure Factors Handbook 

2011 Edition34 (adult and adult female: Tables 8-3 through 8-5; body weight of pregnant 

women: Table 8-29). 

 the most protective index lifestage which serves as the basis for evaluating young 

children’s indoor exposures are children 1 to < 2 years old as described in in the 2012 

Residential SOPs;

 the body weight used to evaluate exposures to children 1 to < 2 years old is 11 kilograms.

For residential handler exposure assessment, the following assumptions and exposure factors 

apply:

 

33 http://www.epa.gov/pesticides/science/USEPA-OPP-HED_Residential%20SOPs_Oct2012.pdf

34 http://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=236252
Page 121 of 227

 a broadcast application of an aerosol can is considered and the entire contents of the can 

(16 oz.) are applied at once, half the contents of the spray can are applied for crack and 

crevice applications, and a quarter of the can contents for a space spray application.

For residential post-application exposure assessment, the following assumptions and exposure 

factors apply:

 inhalation exposures are expected to occur up to 2 hours following application by which 

time the aerosolized particulate is assumed to have settled and, as a result, after that time 

frame exposures are assumed to be negligible;

Use of the PBPK-PD Model

Once complete, the PBPK-PD model was used to estimate the potential level of cholinesterase 

inhibition (% RBC AChE) attributable to the daily dose estimates that result in the highest 

exposure potential. In order to model the potential health outcomes in a manner reflective of 

these exposures, a series of inputs were used that correspond to those used to quantify the daily 

dose estimates. The following exposure characteristics were used: number of days exposed; 

body weights which vary by lifestage; daily exposure duration (hours per day, days per week); 

and the fraction of the dermal surface area exposed.

The dose reconstruction exercise was modeled for a subsequent 14 day post-application duration. 

The daily dose estimated with the 2012 Standard Operating Procedures for Residential Pesticide 

Exposure Assessment for the day of application was inputted into the PBPK-PD model. Dermal 

exposure was modeled assuming that chlorpyrifos residues dissipated at a rate of 10% per day. 

A 14 day period was used as the basis of the PBPK-PD modeling to ensure it adequately 

addressed the time it takes for the ACHE enzyme inhibition to reach a steady state. 

For the adult and children 1 to < 2 years old age groups, the appropriate body weights were 

obtained for modeling purposes from the Exposure Factors Handbook35 (USEPA, 2011). The 

mean adult female bodyweight reflective of all trimesters of pregnancy, 75 kg, was assumed for 

pregnant women to reflect the population of interest from the Columbia cohort being evaluated 

(Exposure Factors Handbook: adult and adult female: Tables 8-3 through 8-5; body weight of 

pregnant women: Table 8-29). For children 1 to < 2 years old, the body weight was set to 11 kg 

(Exposure Factors Handbook, Table 8-3, mean body weight for the 1 to < 2 year old age group). 

For the evaluation of adult handler exposures (dermal and inhalation) it was assumed that the 

application event continued for 1 hour daily and that it occurred each day of the 14 day exposure 

period. The 2012 Residential SOPs makes no recommendation regarding the daily exposure 

duration for handlers. It was assumed that 1 hour is a high end estimate of the time required to 

make an aerosol can application. For the evaluation of adults and children 1 < 2 years old postapplication exposures (i.e., adults: dermal; children: dermal and incidental oral), the daily 

exposure duration was assumed to be 2 hours daily and that it occurs each day in the 14 day 

exposure period. This exposure duration is consistent with that recommended in the 2012 

Residential SOPs for exposures on hard surfaces. For adults and children 1 to < 2 years old 

 

35 http://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=236252
Page 122 of 227

inhalation exposures, it was assumed that the exposure duration was 2 hours on the day of 

application (Day 0) and was not repeated because the exposure source (i.e., aerosols from an 

application event) occurred only once on the first day of the exposure period. This is consistent 

with the available monitoring data and consistent with the 2012 Residential SOPs, the Day 0 air 

monitoring measures were followed by a marked drop to negligible levels by the following day.

 

For all dose reconstruction dermal exposures to chlorpyrifos, the fraction of skin in contact with 

chlorpyrifos was 50% which reflected uncovered skin areas for children wearing shorts and a tee 

shirt. No shower (i.e., washing off the chlorpyrifos) was assumed to occur for the 14 day 

exposure duration modeled. 

Residential Handler Exposure Scenarios

The residential handling of chlorpyrifos residential products are expected to have occurred for 

some percentage of the Columbia cohort population, these are anticipated to have resulted in 

dermal and inhalation exposures. Dermal and inhalation residential handler exposures are 

predicted by use of a factor known as the unit exposure. Unit exposure is the ratio, for a given 

formulation and application equipment, of an individual’s exposure the amount of active 

ingredient handled (AaiH), expressed as mass active ingredient exposure per mass active 

ingredient handled (e.g., mg/lb ai). For the dose reconstruction assessment, unit exposure data 

were used as recommended in the 2012 Residential SOPs for ready-to-use (RTU) aerosol cans

(dermal, 370 mg/ lb ai; inhalation, 3.0 mg/lb ai). Residential handler exposures from application 

of fogger formulations were not assessed which is consistent with the 2012 Residential SOPs. 

Fogger product labels typically direct the user to activate the device and evacuate the treated area 

and not to re-enter for several hours. Therefore, it is assumed that handler exposure from fogger 

application is not expected. 

The exposure assessment for chlorpyrifos Columbia cohort handler exposures is based on the 

following exposure scenarios:

 Adult dermal exposure from broadcast application of a RTU spray can;

 Adult inhalation exposure from broadcast application of a RTU spray can;

 Adult dermal exposure from crack and crevice application of a RTU spray can;

 Adult inhalation exposure from crack and crevice application of a RTU spray can;

 Adult dermal exposure from space spray application of a RTU spray can;

 Adult inhalation exposure from space spray application of a RTU spray can.

Handler Exposure Algorithm

Daily dermal and inhalation exposure (mg/day) for residential pesticide handlers, for a given 

formulation-application method combination, is estimated by multiplying the formulationapplication method-specific unit exposure by an estimate of the amount of active ingredient 

handled in a day, using the equation below:

E = UE * AR * A

where:
Page 123 of 227

E = exposure (mg/day);

UE = unit exposure (dermal, 370 mg/ lb ai; inhalation, 3.0 mb/lb ai);

AR = application rate (e.g., lb ai/can); and

A = area treated or amount handled (broadcast, 1 can/day; crack and crevice, 0.5 can/day; 

space spray, 0.25 can/day).

Residential Handler Exposure/Cholinesterase Inhibition Summary 

Worst-case results of this analysis are presented below representing pregnant women who 

potentially made a broadcast application of an aerosol spray can (Table E.1). Peak % RBC 

AChE inhibition estimated for pregnant women from combined dermal and inhalation exposures 

occurring from product application is 0.0012%. 

Table E.1. Residential Handler (Pregnant Women in the Columbia Cohort) Estimated Exposures and 

Predicted % ChE Inhibition (Route-specific and Combined)

Exposure 

Scenario Formulation Amount Handled

Dermal Dose

(mg/kg/day)

Dermal:

Peak

% ChE 

Inhibition

Inhalation 

Dose

(mg/kg/day)

Inhalation:

Peak

% ChE 

Inhibition

Combined 

Peak

% ChE 

Inhibition

Broadcast 

Ready to Use:

1 % Aerosol 

Spray Can

1 can 0.049 0.0007% 0.030 0.0008% 0.0012%

a. Dermal Exposure = Dermal Unit Exposure (370 mg/lb ai) × Application Rate (0.010 lb ai/can) × Area Treated or Amount 

Handled (cans/day)

b. Inhalation Exposure = Inhalation Unit Exposure (3.0 mg/lb ai) × Application Rate (0.010 lb ai/can) × Area Treated or Amount 

Handled (cans/day)

Residential Post-application Exposure Scenarios

The use of indoor residential chlorpyrifos products are anticipated to have resulted in the 

potential for post-application exposures from public housing residents in the Columbia study 

cohort being in a previously treated environment. Based on the product use profile, residents 

may have been exposed via inhalation to the aerosols resulting from application or by means of 

contact following settling of product contents following settling on indoor surfaces or flooring. 

The exposure assessment for chlorpyrifos Columbia cohort post-application exposures is based 

on the following exposure scenarios:

 Adult dermal contact with residues deposited on flooring (carpeted and hard) from 

broadcast application of RTU spray can;

 Adult inhalation of aerosolized particulates following broadcast application of RTU spray 

can;

 Adult dermal contact with residues deposited on flooring (carpeted and hard) from space

spray application of RTU spray can;

 Adult inhalation of aerosolized particulates following space spray application of RTU 

spray can;

 Adult dermal contact with residues deposited on flooring (carpeted and hard) from crack 

and crevice RTU spray can or PCO application;
Page 124 of 227

 Adult inhalation of aerosolized particulates following crack and crevice application of 

RTU spray can;

 Children 1 to < 2 years old dermal contact with residues deposited on flooring (carpeted 

and hard) from broadcast application of RTU spray can;

 Children 1 to < 2 years old incidental oral (hand-to-mouth) ingestion of residues 

deposited on flooring (carpeted and hard) from broadcast application of RTU spray can 

that have transferred to children’s hands;

 Children 1 to < 2 years old incidental oral (object-to-mouth) ingestion of residues 

deposited on toys in contact with flooring (carpeted and hard) treated by broadcast 

application of RTU spray can;

 Children 1 to < 2 years old inhalation of aerosolized particulate following broadcast 

application of RTU spray can;

 Children 1 to < 2 years old dermal contact with residues deposited on flooring (carpeted 

and hard) from space spray application of RTU spray can;

 Children 1 to < 2 years old incidental oral (hand-to-mouth) ingestion of residues 

deposited on flooring (carpeted and hard) from space spray application of RTU spray can 

that have transferred to children’s hands;

 Children 1 to < 2 years old incidental oral (object-to-mouth) ingestion of residues 

deposited on toys in contact with flooring (carpeted and hard) treated by space spray 

application of RTU spray can;

 Children 1 to < 2 years old inhalation of aerosolized particulate following space spray 

application of RTU spray can;

 Children 1 to < 2 years old dermal contact with residues deposited on flooring (carpeted 

and hard) from crack and crevice RTU spray can or PCO applications;

 Children 1 to < 2 years old incidental oral (hand-to-mouth) ingestion of residues 

deposited on flooring (carpeted and hard) from crack and crevice RTU spray can or PCO 

applications that have transferred to children’s hands;

 Children 1 to < 2 years old incidental oral (object-to-mouth) ingestion of residues 

deposited on toys in contact with flooring (carpeted and hard) treated by crack and 

crevice RTU spray can or PCO applications;

Since all exposure routes (dermal, inhalation, and incidental oral) share a common toxicological 

endpoint, RBC AChE inhibition, risk estimates should been combined. 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 exposure scenario would be unrealistic 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 and hand-to-mouth scenarios. This 

combination should be considered a protective estimate of children’s exposure to pesticides used 

indoors.

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

Appendix in the 2012 Residential SOPs. 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.
Page 125 of 227

Post-application Exposure Data

The 2012 Residential SOPs relied on exposure data from Agency submitted studies in order to 

establish many of the inputs necessary for estimation of post-application indoor exposures. 

Where chemical-specific exposure data are available, these data were relied upon as a more 

accurate measure of exposures from chlorpyrifos and are described below. In the absence of 

these data, exposure inputs are based on the use of available exposure data as recommended in 

the 2012 Residential SOPs. 

Exposure Data Used for Dermal and Incidental Oral Exposure Assessment: No chemicalspecific deposition data were available for the indoor chlorpyrifos products assessed. Therefore, 

as recommended by the 2012 Residential SOPs, default deposited residue values were used 

based on the type of application to be made whether it be a broadcast, crack and crevice, or space 

spay application. For broadcast applications only, residue values were influenced by the percent 

spray applied (i.e., the higher the percent spray, the higher the residue values). The higher, 1% 

chlorpyrifos spray formulation was assumed for post-application assessment of broadcast 

exposures. The default values used are based on an analysis of available residue deposition data 

from Agency submitted studies and literature studies. A summary of the recommended values 

are presented in the 2012 Residential SOPs. 

The transfer coefficent (TC) input used for calculation of post-application exposures is a measure 

of surface-to-skin residue transfer derived from concurrent measures of exposure and surface 

residue. Per the 2012 Residential SOPs, no studies were available that measure both exposure 

and surface residue with subjects performed typical indoor activities. Therefore, the transfer 

coefficients used for indoor scenarios are derived from information provided in three different 

studies: 1) two studies which measured exposure and surface residues while subjects performed a 

Jazzercise routine (Krieger, 2000 and Selim, 2004) and 2) a study which measured 

biomonitoring doses which adults performed scripted activities for 4 hours on carpets (Vaccaro, 

1991). Of these studies, the Krieger study was conducted using chlorpyrifos. 

As for the fraction of residue available for transfer input, a complete dataset was compiled for 

chlorpyrifos based on available chemical-specific data (Beamer et al., 2009). Therefore, the 

chlorpyrifos-specific residue fractions anticipated to transfer for both carpets and hard surfaces 

were used for estimation of post-application dermal and incidental oral exposures. 

Exposure Data Used for Inhalation Exposure Assessment: In order to best represent the potential 

for inhalation exposures following use of the indoor chlorpyrifos products assessed, a review of 

available literature studies and registrant-submitted exposure data was conducted. The following 

exposure data sources were identified and used: 

Indoor broadcast applications –

 Fenske, R., et al (1990). Potential Exposure and Health Risks of Infants 

following Indoor Residential Pesticide Applications. American Journal of Public 

Health. 80 (6): 689-693. 

 Lu, C. and Fenske, R (1998). Air and Surface Chlorpyrifos Residues following 

Residential Broadcast and Aerosol Pesticide Applications. Environmental Science 
Page 126 of 227

and Technology. 32 (10): 1386 -1390. 

 EPA MRID: 42887201. Contardi, J. (1993). An Evaluation of the Appropriate 

Drying Time via Air Monitoring, Dislodgable Residue Determination, and Carpet 

Weight Loss, After Applying Dursban LO Insecticide to a Carpeted Surface: 

Unpublished study prepared by Dow Chemical Co., Health and Environmental 

Sciences. 29 pp.

Indoor crack and crevice applications –

 Byrne, S.L., Shurdut, B.A. and Saunders, D.G. (1998). Potential Chlorpyrifos 

Exposure to Residents following Standard Crack and Crevice Treatment. 106 

(11): 725 -731. 

 Hore, P. et al. (2005). Children’s Residential Exposures to Chlorpyrifos: 

Application of CPPAES Field Measurements of Chlorpyrifos and TCPy within 

MENTOR/SHEDS – Pesticides Model. Science of the Total Environment. 336 (2 

-3): 525-537. 

 Stout II, D.M. and Mason, M.A. (2003). The Distribution of Chlorpyrifos 

following a Crack and Crevice Type Application in the US EPA Indoor Air 

Quality Research House. Atmospheric Environment. 37 (39 -40): 5539 -5549.

 EPA MRID 44458201: Byrne, S.; Saunders, D.; Cook, W. et al. (1998) 

Residential Exposure to Chlorpyrifos from Reentry to Structures Treated with 

Crack and Crevice and Spot Applications of Dursban Pro. Unpublished study 

prepared by Dow AgroSciences. 133 pp.

Based on a review of the available data and consistent with the 2012 Residential SOPs, the day 

of application (Day 0) air monitoring measures were significant, followed by a marked drop to 

negligible levels by the following day. Therefore, HED made use only of day of application air 

monitoring measures for purpose of post-application exposure assessment. All studies 

referenced were based on 0.5% chlorpyrifos formulated products. In order to address the 

potential for use of the 1% chlorpyrifos product formulations available at the time, all air 

monitoring measures were doubled. The broadcast exposure data are intended for use in 

assessing the potential inhalation exposures/doses anticipated to occur from both broadcast and 

space spray applications; the crack and crevice exposure data were used only for that application 

type. The resulting mean day of application air monitoring measures are presented in Table E.2

below. 

Table E.2. Airborne Concentrations of Chlorpyrifos from Open Literature and Registrant-submitted 

Studies Resulting from Indoor Broadcast and Crack and Crevice Applications

Study Chlorpryrifos Concentration (mg/m3)

Broadcast

Fenske, R., et al (1990) 0.18

Lu, C. and Fenske, R (1998) 0.088

EPA MRID: 42887201 0.031

Average (All Studies) 0.092

Crack and Crevice

Byrne, S.L., Shurdut, B.A. and Saunders, D.G. (1998) 0.0010

Hore, P. et al. (2005). 0.00057

Stout II, D.M. and Mason, M.A. (2003) 0.00086

EPA MRID 44458201 0.0011
Page 127 of 227

Table E.2. Airborne Concentrations of Chlorpyrifos from Open Literature and Registrant-submitted 

Studies Resulting from Indoor Broadcast and Crack and Crevice Applications

Study Chlorpryrifos Concentration (mg/m3)

Average (All Studies) 0.00089

Post-Application Algorithms for All Scenarios

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

The algorithm to calculate exposure is as follows:

E = TR ∗ TC ∗ ET ∗ CF1

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:

TR = DepR ∗ Fai

where:

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:

D =

E ∗ AF

BW

where:

D = dose (mg/kg-day);

E = exposure (mg/day);

AF = absorption factor; and

BW = body weight (kg).
Page 128 of 227

Table E.3. 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 0.020a

Hard surfaces 0.13a

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 80

Children 1 < 2 years old 11

a. Chlopyrifos-specific as identified (Table 7-8) in the 2012 Residential SOPs. 

Post-application Hand-to-Mouth Exposure Algorithm

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

SHEDS-Multimedia):

E = [HR ∗ (FM ∗ SAH) ∗ (ET ∗ N_Replen) ∗ (1 − (1 − SE)

Freq_HtM

N_Replen )]

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

HR =

Faihands ∗ DE

SAH ∗ 2
Page 129 of 227

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).

Table E.4. Indoor Environments – Inputs for Residential Post-application Hand-toMouth 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 Error! Reference source 

not found.

(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) 1% formulation

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

Post-application Object-to-Mouth Exposure Algorithm

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

SHEDS-Multimedia):

E = OR ∗ CF1 ∗ SAMO ∗ (ET ∗ N_Replen) ∗ (1 − (1 − SE)

Freq_OtM

N_Replen )
Page 130 of 227

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

OR = DepR ∗ FO

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).

Table E.5. Indoor Environments – Inputs for Residential Post-application Object-toMouth 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 0.020a

Hard surfaces 0.13a

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

a. Chlopyrifos-specific as identified (Table 7-8) in the 2012 Residential SOPs. 
Page 131 of 227

Residential Post-Application Exposure/Cholinesterase Inhibition Summary 

The results of this analysis are presented below for pregnant who were potentially exposed from 

contact to residues which occur in previously treated areas such as their homes (Table E.6). 

Results for young children (aged 1 to < 2 years old) who are also exposed to residues which 

occur in previously treated areas such as their homes are presented in Table E.7. Peak 

cholinesterase inhibition for pregnant women resulting from combined dermal and inhalation 

exposures occurring from contact with previously treated indoor areas is 0.45%. For children 1 

to < 2 years old, peak cholinesterase inhibition associated with combined dermal, incidental oral, 

and inhalation exposures from being in previously treated areas is 2.7%. 

Table E.6. Residential Post-application To Pregnant Women in the Columbia Cohort Estimated Dermal and 

Inhalation Exposures and Predicted % ChE Inhibition (Route-specific and Combined)

Exposure 

Scenario Formulation Dermal Dose (mg/kg/day)

Dermal: 

Peak

% ChE 

Inhibition

Airborne 

Concentration of 

Chlorpyrifos

(mg/m3)

Inhalation:

Peak 

% ChE 

Inhibition

Combined: 

Peak 

% ChE 

Inhibition

Broadcast

(Hard 

Surfaces)

1% PCO 

Application 

or RTU 1 16 

oz can

0.71 0.45% 0.092 0.0049% 0.45% 

* See algorithms and inputs above used to estimate post-application dermal exposures. 

Table E.7. Residential Post-application (Children 1 to < 2 Years Old in the Columbia Cohort) Estimated Dermal 

and Inhalation Exposures and Predicted % RBC AChE Inhibition (Route-specific and Combined)

Exposure 

Scenario Formulation

Dermal 

Dose 

(mg/kg/day)

Dermal:

Peak

% ChE 

Inhibition

HTM

Dose

(mg/kg/day)

HTM Peak

% ChE 

Inhibition

(mg/day)

Airborne 

Concn. of 

Chlorpyrifos

(mg/m3)

Inhalation:

Peak

% ChE 

Inhibition

Combined:

Peak

% ChE 

Inhibition

Broadcast

(Hard 

Surfaces)

1% PCO 

Application 

or RTU 1 16 

oz can

1.3 0.14% 0.10 2.2% 0.092 0.014% 2.7%

* See algorithms and inputs above used to estimate post-application dermal, (HTM) hand-to-mouth, and (OTM) object-to-mouth 

exposures/doses. 
Page 132 of 227

Appendix F: Summary of Occupational Handler Risk Estimates
Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Mixer/Loaders

Mixing/

Loading

Liquids

for 

Aerial 

and/or

Chemigation

Applications

(1a)

Tree Nut Orchard 

Floors (Pecans) 4.3 350

(Chem. 

Only)

0.74 3.8 4.8 0.76 4.3 5.5 0.76 4.3 5.6 15

Tree Nut Orchard 

Floors (Almonds,

Walnuts)

4.0 0.79 4.2 5.2 0.81 4.7 6 0.81 4.7 6.1 17

Corn (pre-plant) 3.0

350

(Chem. 

Only)

1.1 5.5 6.8 1.1 6.1 7.9 1.1 6.2 8 22

Citrus 2.3

350

1.4 7.2 9.1 1.4 8.1 11 1.4 8.2 11 29

Non-bearing Fruit and 

Nut Trees (Nursery), 

Radish (pre-plant), 

Turfgrass (sod or seed)

2.1 1.5 7.9 10 1.5 8.8 12 1.5 9 12 32

Cherries, Hybrid 

Cottonwood/ Poplar 

Plantations Grown for 

Pulp, Mint 

(Peppermint and 

Spearmint), Peanut, 

Rutabaga, 

Strawberries (preplant), Sunflower (preplant), Sweet Potato, 

Tobacco, Tree Fruits 

(Apple, Fig (CA only), 

Nectarine, Peach, 

Pear, Plum/Prune), 

Tree Nuts (Almonds, 

Filberts, Hazelnuts, 

Pecans, Walnuts), 

Turfgrass (Ornamental 

and Sod Farms)

2.0 1.6 8.2 10 1.6 9.2 12 1.6 9.4 12 33

Clover (grown for 

seed; foliar), 

Cranberry, Sunflower 

(post-emergence/ 

foliar)

1.9 1.7 8.7 11 1.7 9.7 13 1.7 9.8 13 35
Page 134 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Corn (post-emergence) 1.5

1,200

(Aerial) 0.61 3.2 4 0.63 3.6 4.6 0.63 3.6 4.7 13

350

(Chem.) 2.1 11 13 2.2 13 15 2.2 13 16 44

Asparagus, Brussel 

Sprouts, Cauliflower, 

Cole Crops, 

Strawberries, 

Sugarbeets, Radish

1.5 350 2.1 11 13 2.2 13 15 2.2 13 16 44

Alfalfa, Corn (preplant), Cotton (except 

MS), Sorghum, 

Soybean, Wheat 

1.0 1,200 0.93 4.8 6 0.95 5.4 6.9 0.95 5.5 7.1 19

Alfalfa, Citrus 

Orchard Floor, Corn 

(pre-plant), Cotton 

(except MS), 

Sorghum, Soybean, 

Wheat

1.0 350

(Chem.) 3.1 16 21 3.2 18 24 3.2 19 24 66

Christmas Tree 

Plantations 1.0 350 3.1 16 21 3.2 18 24 3.2 19 24 66

Carrots 0.94 3.4 17 22 3.5 19 25 3.5 20 25 71

Ornamental NonFlowering Plants

-

Microencapsulated

0.0070 60

(Chem.) 2600 14000 17000 2700 16000 20000 2700 16000 21000 55,000

Mixing/

Loading 

Liquids for 

Airblast 

Application 

(1b)

Citrus (CA and AZ) 6.0

40

4.6 24 30 4.7 27 35 4.7 28 35 96

Citrus, Non-bearing 

Fruit and Nut Trees 

(Nurseries)

4.0 6.9 36 45 7.1 41 52 7.1 41 53 140

Tree Fruits (Nectarine, 

Peach – dormant, 

delayed dormant)

3.0 9.3 48 60 9.5 54 69 9.5 55 71 190

Cherries, Tree Fruits 

(Pear; Plum/Prune -

dormant, delayed 

dormant), Tree Nuts 

2.0 14 72 91 14 81 110 14 82 110 290
Page 135 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

(Almonds, Filberts, 

Hazelnuts, Pecans, 

Walnuts)

Ornamental and/or 

Shade Trees, 

Ornamental Woody 

Shrubs and Vines, 

Herbaceous Plants

2.0 20 27 150 180 28 160 210 28 170 220 580

Christmas Tree 

Plantations, Grapes 1.0 40 27 150 180 28 160 210 28 170 220 580

Mixing/

Loading 

Liquids for 

Ground-boom 

Application 

(1c)

Tree Nut Orchard 

Floors (Pecans) 4.3

80

3.2 17 21 3.3 18 24 3.3 19 25 68

Tree Nut Orchard 

Floors (Almonds, 

Walnuts)

4.0 3.5 18 23 3.6 20 26 3.6 21 26 73

Nursery Stock -

preplant (see master 

label description)

4.0 40 6.9 36 45 7.1 41 52 7.1 41 53 140

Ornamental Lawns 

and Turf, Sod Farms 3.76 80 3.7 19 24 3.8 21 28 3.8 22 28 77

Corn (pre-plant) 3.0 200 1.9 9.6 12 1.9 11 13 1.9 11 14 39

Radish (pre-plant) 3.0

80

4.6 24 30 4.7 27 35 4.7 28 35 96

Rutabaga 2.4 5.8 30 38 5.9 34 43 5.9 34 44 120

Brussel Sprouts (PostPlants), Grapes (foliar) 2.25 6.1 32 40 6.3 36 46 6.3 36 47 130

Sweet Potato (Preplant, Soil Broadcast) 2.1 6.6 35 43 6.8 39 49 6.8 39 50 140

Cotton (except MS)

2.0

200 2.7 15 18 2.8 16 21 2.8 17 22 58

Brussel Sprouts (at 

plant), Cole Crops, 

Cauliflower, Figs (CA 

only), Grapes 

(dormant, delayed 

dormant), Mint 

(Peppermint, 

Spearmint), Peanut, 

Pineapple, 

Strawberries (pre80 6.9 36 45 7.1 41 52 7.1 41 53 140
Page 136 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

plant), Sunflower (preplant), Tobacco (preplant)

Ornamental and/or 

Shade Trees, 

Herbaceous Plants, 

Ornamental Woody 

Shrubs and Vines

40 14 72 91 14 81 110 14 82 110 290

Beets (Table, Sugar; 

At Plant), Clover 

(Grown for Seed; 

foliar), Hybrid 

Cottonwood/Poplar 

Plantations

1.9 80 7.3 38 48 7.5 43 55 7.5 43 56 150

Corn (post-emergence) 1.5 200 3.7 19 24 3.8 21 28 3.8 22 28 77

Cranberry 1.5 80 9.3 48 60 9.5 54 69 9.5 55 71 190

Alfalfa, Cotton, 

Sorghum Grain, 

Soybean, Wheat

1.0

200 5.6 29 36 5.7 32 41 5.7 33 42 120

Asparagus, Beets 

(Table, Sugar - at

plant), Citrus Orchard 

Floors, Forest 

Plantings 

(reforestation, 

plantation, tree farm), 

Grass 

(forage/fodder/hay), 

Legume Vegetables, 

Nonagricultural 

Outdoor Buildings and 

Structures, Onions

80 14 72 91 14 81 110 14 82 110 290

Conifers and 

Deciduous Trees, Seed 

Orchard Trees

60 19 96 120 19 110 130 19 110 140 390

Golf course (fairways, 

tees, greens) 40 27 150 180 28 160 210 28 170 220 580

Carrots 0.94 80 15 77 92 15 86 110 15 88 110 310
Page 137 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Ornamental NonFlowering Plants

-

Microencapsulated

0.0070 40 4000 21000 26000 4100 23000 30000 4100 24000 30000 80000

Mixing/

Loading 

Liquids for 

Wide Area 

Aerial 

Applications 

(1d)

Mosquitocide (not in 

FL) 0.01 7,500 15 77 92 15 86 110 15 88 110 310

Mixing/

Loading 

Liquids for 

Wide Area 

Ground 

Applications 

(1e)

Mosquitocide (not in 

FL) 0.01 3,000 37 190 240 38 210 280 38 220 280 770

Mixing/

Loading 

Wettable 

Powder (in 

WSP) for 

Aerial 

Applications 

(2a)

Nursery Stock –

preplant (see master 

label description)

4.0 60 No Data No Data No Data No Data No Data No Data No Data No Data No Data 67

Citrus 2.3 350 No Data No Data No Data No Data No Data No Data No Data No Data No Data 19

Tree Nuts (Almonds, 

Filberts/Hazelnuts) 2.0 350 No Data No Data No Data No Data No Data No Data No Data No Data No Data 22

Ornamental and/or 

Shade Trees, 

Herbaceous Plants

2.0 60 No Data No Data No Data No Data No Data No Data No Data No Data No Data 130

Tree Fruit (Apples, 

Cherries) 1.5

350

No Data No Data No Data No Data No Data No Data No Data No Data No Data 30

Cole Crops (excludes 

Brussel Sprouts and 

Cauliflower), 

Christmas Tree 

Plantations 

1.0 No Data No Data No Data No Data No Data No Data No Data No Data No Data 44

Mixing/

Loading 

Wettable 

Citrus (CA and AZ) 6.0 40 No Data No Data No Data No Data No Data No Data No Data No Data No Data 67

Citrus 4.0 No Data No Data No Data No Data No Data No Data No Data No Data No Data 98

Ornamental and/or 2.0 20 No Data No Data No Data No Data No Data No Data No Data No Data No Data 390
Page 138 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Powder (in 

WSP) for 

Airblast 

Applications 

(2b)

Shade Trees, 

Herbaceous Plants

Tree Nuts (Almonds, 

Filberts/Hazelnuts) 2.0

40

No Data No Data No Data No Data No Data No Data No Data No Data No Data 200

Tree Fruit (Apples, 

Cherries) 1.5 No Data No Data No Data No Data No Data No Data No Data No Data No Data 260

Christmas Tree 

Plantations 1.0 No Data No Data No Data No Data No Data No Data No Data No Data No Data 390

Mixing/

Loading 

Wettable 

Powder (in 

WSP) for 

Groundboom 

Applications 

(2c)

Ornamental Woody 

Shrubs and Vines (pretransplant)4.0 60 No Data No Data No Data No Data No Data No Data No Data No Data No Data 67

Ornamental Lawns 

and Turf, Sod Farms 

(Turf)

3.76 80 No Data No Data No Data No Data No Data No Data No Data No Data No Data 51

Citrus Orchard Floors, 

Cole Crops (excludes 

Brussel Sprouts and 

Cauliflower) 

1.0 80 No Data No Data No Data No Data No Data No Data No Data No Data No Data 200

Mixing/

Loading 

Granulars for 

Aerial 

Applications 

(3a)

Peanuts 4.0 350 3.4 3.5 3.7 10 11 15 14 16 23 17

Sweet Potato 2.1 6.4 6.6 7.1 20 21 28 27 30 43 32

Corn (pre-plant) 2.0 1,200 1.9 2 2.1 6 6.7 8.7 7.9 9.1 13 9.6

Sunflower, Tobacco 2.0

350

6.7 6.9 7.5 21 23 29 28 32 46 33

Sod Farms (Turf) 1.0 13 14 15 41 44 58 56 62 91 66

Mixing/

Loading 

Granulars for 

Tractor 

Drawn 

Spreader 

Applications 

(3b)

Ornamental Woody 

Shrubs and Vines 6.0 60 13 14 15 40 44 57 55 62 91 65

Rutabaga 2.4 80 25 25 27 77 84 110 100 110 160 120

Soybean 2.2 200 11 11 12 33 36 46 45 50 74 53

Sweet Potato 2.1 80 28 29 31 87 96 120 120 130 190 140

Corn 2.0 200 12 12 13 36 40 50 49 55 79 58

Cole Crops (Excludes 

Brussel Sprouts and 

Cauliflower), Ginseng, 

Sugarbeets, 

Sunflower, Tobacco

2.0 80 30 30 33 92 100 130 120 140 200 140

Sorghum Grain 1.5 200 16 16 18 48 52 68 65 74 110 77

Asparagus 1.5 80 40 41 44 120 130 170 160 180 270 190

Nursery Stock (see 1.1 60 71 74 79 220 240 300 290 330 480 350
Page 139 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

master label 

description)

Alfalfa 1.0 200 24 24 26 72 79 100 98 110 160 120

Citrus Orchard Floors, 

Onions, Ornamental 

Lawns and Turf, Sod 

Farms (Turf)

1.0 80 59 61 65 180 200 250 240 270 400 290

Golf Course (Turf), 

Rights of Way/ Road 

Medians

1.0 40 120 120 130 360 400 500 490 550 790 580

Mixer/

Loader 

Granulars 

with 

SmartBox®

for Aerial 

Applications 

(3c)

Corn 1.0 1,200 No Data No Data No Data No Data No Data No Data No Data No Data No Data 720

Mixer/

Loader 

Granulars 

with 

SmartBox® 

for Tractor 

Drawn 

Spreader 

Applications 

(3d)

Peanuts 4.0

80

No Data No Data No Data No Data No Data No Data No Data No Data No Data 2800

Radish 2.8 No Data No Data No Data No Data No Data No Data No Data No Data No Data 4000

Brassica Vegetables,

Rutabaga, Radish, 

Turnip

2.3 No Data No Data No Data No Data No Data No Data No Data No Data No Data 4900

Sunflowers 2.2 No Data No Data No Data No Data No Data No Data No Data No Data No Data 5100

Soybeans 2.0 200 No Data No Data No Data No Data No Data No Data No Data No Data No Data 2200

Sugarbeet, Sweet 

Potato, Tobacco 2.0 80 No Data No Data No Data No Data No Data No Data No Data No Data No Data 5600

Sorghum 1.5 200 No Data No Data No Data No Data No Data No Data No Data No Data No Data 3000

Asparagus 1.5 80 No Data No Data No Data No Data No Data No Data No Data No Data No Data 7200

Alfalfa, Soybeans 1.0 200 No Data No Data No Data No Data No Data No Data No Data No Data No Data 4500

Citrus, Onion 1.0 80 No Data No Data No Data No Data No Data No Data No Data No Data No Data 11000

Mixer/

Loader Water 

Dispersable 

Granulars (in 

WSP) for 

Tree Nut Orchard 

Floors (Pecans) 4.3

350

(Chem.)

No Data No Data No Data No Data No Data No Data No Data No Data No Data 10

Tree Nut Orchard 

Floors (Almonds, 

Walnuts)

4.0 No Data No Data No Data No Data No Data No Data No Data No Data No Data 11
Page 140 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Aerial and/or 

Chem. 

Applications 

(4a) 

Rutabaga 2.4 No Data No Data No Data No Data No Data No Data No Data No Data No Data 19

Citrus 2.3

350

No Data No Data No Data No Data No Data No Data No Data No Data No Data 19

Sweet Potato (preplant, soil broadcast) 2.1 No Data No Data No Data No Data No Data No Data No Data No Data No Data 21

Cherries, Tree Nuts 

(Almond, 

Filberts/Hazelnuts, 

Pecans, Walnuts), Tree 

Fruit (Apple, 

Nectarines, Peach, 

Pear, Plum/Prune), 

Mint (Peppermint, 

Spearmint), Peanut, 

Sunflowers, Tobacco

2.0 No Data No Data No Data No Data No Data No Data No Data No Data No Data 22

Cranberry 1.5 No Data No Data No Data No Data No Data No Data No Data No Data No Data 30

Corn, Sorghum Grain, 

Soybean 1.0 1,200 No Data No Data No Data No Data No Data No Data No Data No Data No Data 13

Asparagus, Sugarbeet, 

Cole Crops (Except 

Brussel Sprouts and 

Cauliflower), Cotton, 

Strawberries

1.0 350 No Data No Data No Data No Data No Data No Data No Data No Data No Data 44

Corn, Sorghum Grain, 

Soybean, Sugarbeets 1.0 350 (Chem.) No Data No Data No Data No Data No Data No Data No Data No Data No Data 44

Mixer/

Loader Water 

Dispersable 

Granulars (in 

WSP) for 

Airblast 

Applications 

(4b)

Citrus (CA and AZ) 6.0

40

No Data No Data No Data No Data No Data No Data No Data No Data No Data 67

Tree Nuts (Pecans) 4.3 No Data No Data No Data No Data No Data No Data No Data No Data No Data 91

Citrus 4.0 No Data No Data No Data No Data No Data No Data No Data No Data No Data 98

Tree Fruits (Nectarines 

and Peaches) 3.0 No Data No Data No Data No Data No Data No Data No Data No Data No Data 130

Tree Nuts (Almond, 

Filberts/Hazelnuts, 

Walnuts), Tree Fruits 

(Apples, Cherries, 

Pears, Plums/Prunes)

2.0 No Data No Data No Data No Data No Data No Data No Data No Data No Data 200

Ornamental Woody 

Shrubs and Vines 2.0 20 No Data No Data No Data No Data No Data No Data No Data No Data No Data 390

Asparagus, Christmas 

Tree Plantations, 1.0 40 No Data No Data No Data No Data No Data No Data No Data No Data No Data 390
Page 141 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Sugarbeets

Mixer/

Loader Water 

Dispersable 

Granulars (in 

WSP) for 

Ground-boom 

Applications 

(4c)

Tree Nut Orchard 

Floors (Pecans) 4.3

80

No Data No Data No Data No Data No Data No Data No Data No Data No Data 46

Tree Nut Orchard 

Floors (Almonds, 

Walnuts)

4.0 No Data No Data No Data No Data No Data No Data No Data No Data No Data 48

Rutabaga 2.4 No Data No Data No Data No Data No Data No Data No Data No Data No Data 80

Turnip 2.3 No Data No Data No Data No Data No Data No Data No Data No Data No Data 86

Sweet Potato (preplant, soil broadcast) 2.1 No Data No Data No Data No Data No Data No Data No Data No Data No Data 92

Cole Crops (Excludes 

Brussel Sprout and 

Cauliflower), Figs 

(CA only), Mint 

(Peppermint, 

Spearmint), Peanut, 

Sunflower, Tobacco

2.0 No Data No Data No Data No Data No Data No Data No Data No Data No Data 98

Ornamental Woody 

Shrubs and Vines 2.0 60 No Data No Data No Data No Data No Data No Data No Data No Data No Data 130

Cranberry 1.5 80 No Data No Data No Data No Data No Data No Data No Data No Data No Data 130

Corn, Sorghum Grain, 

Soybean 1.0 200 No Data No Data No Data No Data No Data No Data No Data No Data No Data 79

Asparagus, Citrus, 

Cotton, Grapes 

(dormant, delayed 

dormant), Legume 

Vegetables, Onions, 

Peppers, Strawberries, 

Sugarbeets

1.0 80 No Data No Data No Data No Data No Data No Data No Data No Data No Data 200

Applicators
Page 142 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Aerial Liquid 

Application 

(5a)

Citrus 2.3

350

No Data No Data No Data No Data No Data No Data No Data No Data No Data 140

Non-bearing Fruit and 

Nut Trees (Nursery), 

Radish (pre-plant), 

Sweet Potato (preplant)

2.1 No Data No Data No Data No Data No Data No Data No Data No Data No Data 150

Cherries, Mint 

(Peppermint and 

Spearmint), Peanut, 

Rutabaga, 

Strawberries (preplant), Sunflower (preplant), Tobacco, Tree 

Fruits (Apple, Fig (CA 

only), Nectarine, 

Peach, Pear, 

Plum/Prune), Tree 

Nuts (Almonds, 

Filberts/Hazelnuts, 

Pecans, Walnuts), 

Turfgrass (Ornamental 

and Sod Farms)

2.0

350 No Data No Data No Data No Data No Data No Data No Data No Data No Data 160

Ornamental and/or 

Shade Trees, 

Herbaceous Plants

60 No Data No Data No Data No Data No Data No Data No Data No Data No Data 940

Clover (grown for 

seed; foliar), 

Cranberry, Hybrid 

Cottonwood/ Poplar 

Plantations Grown for 

Pulp , Sunflower 

(post-emergence/ 

foliar) 

1.9 350 No Data No Data No Data No Data No Data No Data No Data No Data No Data 170

Corn (post-emergence) 1.5 1,200 No Data No Data No Data No Data No Data No Data No Data No Data No Data 63

Asparagus, Brussel 

Sprouts, Cauliflower, 

Cole Crops, 

1.5 350 No Data No Data No Data No Data No Data No Data No Data No Data No Data 220
Page 143 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Strawberries, 

Sugarbeets, Radish

Alfalfa, Corn (preplant), Cotton (except 

MS), Sorghum, 

Soybean, Wheat

1.0

1,200 No Data No Data No Data No Data No Data No Data No Data No Data No Data 94

Christmas Tree 

Plantations, Cole 

Crops (excludes 

Brussel Sprouts and 

Cauliflower)

350 No Data No Data No Data No Data No Data No Data No Data No Data No Data 320

Carrots 0.94 350 No Data No Data No Data No Data No Data No Data No Data No Data No Data 350

Wide Area 

Aerial 

Applications 

(5b)

Mosquitocide (not in 

FL) 0.010 7,500 No Data No Data No Data No Data No Data No Data No Data No Data No Data 1500

Aerial 

Granular 

Applications 

(5c)

Peanuts 4.0

350

No Data No Data No Data No Data No Data No Data No Data No Data No Data 5

Sweet Potato 2.1 No Data No Data No Data No Data No Data No Data No Data No Data No Data 9.4

Sunflower, Tobacco 2.0 No Data No Data No Data No Data No Data No Data No Data No Data No Data 9.5

Sod Farms (Turf) 1.0 No Data No Data No Data No Data No Data No Data No Data No Data No Data 20

Airblast 

Applications 

(6a) 

See Table F.2 below.

Wide Area 

Ground 

Applications 

(6b)

Mosquitocide (not in 

FL) 0.010 3,000 4.4 4.9 5.2 4.4 4.9 5.2 4.7 5.3 5.6 510

Ground-boom 

Applications 

(7a)

Tree Nut Orchard 

Floors (Pecans) 4.3

80

8.3 29 34 9.1 41 51 9.2 43 54 110

Tree Nut Orchard 

Floors (Almonds, 

Walnuts) 4.0

8.9 31 36 9.7 44 54 9.8 46 58 120

Nursery Stock – preplant (see master label 

description)

40 18 63 72 20 87 110 20 92 110 250
Page 144 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Ornamental Lawns 

and Turf, Sod Farms 

(Turf)

3.76 80 9.8 33 39 11 47 58 11 49 62 130

Corn (pre-plant) 3.0 200 4.8 17 19 5.2 23 29 5.2 25 31 67

Radish (pre-plant)

80

12 42 49 13 58 73 13 62 78 170

Rutabaga 2.4 15 53 60 17 73 88 17 77 94 210

Turnip 2.3 15 54 63 17 76 96 17 80 100 220

Brussel Sprouts (PostPlant), Grapes (foliar) 2.25 16 56 65 18 77 96 18 82 100 220

Sweet Potato (preplant, soil broadcast) 2.1 17 60 70 19 84 110 19 88 110 240

Cotton (except MS) 2.0 200 7.2 25 29 7.8 35 44 7.9 37 47 99

Brussel Sprouts (At 

Plant), Cole Crops, 

Cauliflower, Figs (CA 

only), Grapes 

(dormant, delayed 

dormatnt), Mint 

(Peppermint, 

Spearmint), Peanut, 

Pineapple, 

Strawberries (Preplant), Sunflower (Preplant), Tobacco (Preplant)

2.0 80 18 63 72 20 87 110 20 92 110 250

Ornamental and/or 

Shade Trees, 

Herbaceous Plants, 

Ornamental Woody 

Shrubs and Vines

2.0 40 36 120 150 39 170 220 40 180 230 500

Beets (table, sugar; 

pre-plant), Clover 

(grown for seed; 

foliar), Hybrid 

Cottonwood/Poplar 

Plantations

1.9 80 19 64 75 21 90 110 21 95 120 260

Corn (post-emergence) 1.5 200 9.8 33 39 11 47 58 11 49 62 130

Cranberry 1.5 80 23 83 98 25 120 150 26 120 160 330
Page 145 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Alfalfa, Cotton, 

Sorghum Grain, 

Soybean, Wheat

1.0

200 14 50 58 16 70 87 16 74 92 200

Asparagus, Beets 

(table, sugar; at plant), 

Citrus Orchard Floors, 

Cole Crops (excludes 

brussel sprouts and 

cauliflower), Cotton, 

Forest Plantings 

(reforestation, 

plantation, tree farm), 

Grapes (dormant, 

delayed dormant), 

Grass 

(forage/fodder/hay), 

Legume Vegetables, 

Nonagricultural 

Outdoor Buildings and 

Structures, Onions, 

Peppers, Strawberries

80 36 120 150 39 170 220 40 180 230 500

Conifers and 

Deciduous Trees, Seed 

Orchard Trees

60 48 170 190 52 230 290 52 250 310 670

Golf Course (fairways, 

tees, greens) 40 72 250 290 78 350 440 79 370 470 990

Carrots 0.94 80 38 130 150 41 190 230 42 200 240 530

Forest Trees 

(softwoods, conifers) 0.61 80 78 250 280 64 290 360 64 300 380 820

Tractor 

Drawn 

Granular 

Spreader 

Applications 

(7b)

Ornamental Woody 

Shrubs and Vines 6.0 60 17 18 19 43 52 67 53 67 96 89

Peanuts 4.0

80

19 20 22 48 57 74 60 76 110 100

Radish 2.8 27 29 31 68 85 110 84 110 150 140

Rutabaga 2.4 31 33 36 80 97 130 99 130 180 170

Cauliflower (postplant), Turnip 2.3 33 35 38 86 100 130 110 130 180 180

Brussel Sprouts (postplant) 2.25 33 36 39 86 100 130 110 130 190 180
Page 146 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Soybean 2.2 200 14 15 16 35 42 55 43 55 79 73

Sweet Potato 2.1 80 36 38 42 92 110 140 110 150 200 190

Corn 2.0 200 15 16 18 39 46 60 48 61 86 81

Cole Crops (Except 

Cauliflower), Ginseng, 

Sugarbeets, 

Sunflower, Tobacco

2.0 80 38 41 44 98 120 150 120 150 210 200

Sorghum Grain 1.5 200 20 21 23 51 62 79 63 82 110 110

Asparagus 1.5 80 50 54 58 130 150 200 160 200 280 260

Nursery Stock (see 

Master Label 

description)

1.1 60 91 98 110 230 280 360 290 370 520 490

Alfalfa 1.0 200 31 32 35 79 92 120 98 120 170 160

Citrus Orchard Floors, 

Onions, Ornamenal 

Lawns and Turf, Sod 

Farms (Turf)

1.0 80 76 80 87 200 230 300 240 300 430 400

Golf Course (Turf), 

Rights-of-way, Road 

Medians

1.0 40 150 160 180 390 460 600 480 610 860 810

Tractor 

Drawn 

Granular 

Spreader 

Applications 

With 

SmartBox®

(7c)

Peanuts 4.0

80

No Data 200 No Data No Data No Data No Data No Data No Data No Data No Data

Radish 2.8 No Data 280 No Data No Data No Data No Data No Data No Data No Data No Data

Brassica Vegetables,

Rutabaga, Radish, 

Turnip

2.3

No Data

340

No Data No Data No Data No Data No Data No Data No Data No Data

Sunflowers 2.2 No Data 360 No Data No Data No Data No Data No Data No Data No Data No Data

Soybeans 2.0 200 No Data 160 No Data No Data No Data No Data No Data No Data No Data No Data

Sugarbeet, Sweet 

Potato, Tobacco 2.0 80 No Data 400 No Data No Data No Data No Data No Data No Data No Data No Data

Sorghum 1.5 200 No Data 210 No Data No Data No Data No Data No Data No Data No Data No Data

Asparagus 1.5 80 No Data 530 No Data No Data No Data No Data No Data No Data No Data No Data

Alfalfa, Soybeans 1.0 200 No Data 320 No Data No Data No Data No Data No Data No Data No Data No Data

Citrus, Onion 1.0 80 No Data 790 No Data No Data No Data No Data No Data No Data No Data No Data

Paint 

Brush/Roller 

Applications 

Wood Protection 

Treatment

0.17

(lb ai/

gallon)

3

gallons 2.6 16 17 2.7 20 21 2.7 20 21 No Data
Page 147 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

(8)

Sewer Manhole Walls 0.080

(lb ai/

gallon)

20

gallons 0.84 5 5.3 0.86 6.1 6.7 0.87 6.3 6.9 No Data

Structural 

(warehouses, FHE) 3 gallons 5.6 33 35 5.8 41 44 5.8 42 45 No Data

Ear Tag 

Applications 

(9)

Cattle 0.0030 100 Exposures assumed to be negligible.

Bait Station 

Applications 

(10)

Roach Control 0.00040 100 Exposures assumed to be negligible.

Total Release 

Fogger (11) 

Greenhouse 

Production (Bedding 

Plants, Cut Flowers, 

Flowering Hanging 

Baskets, Potted 

Flowers, Ornamentals)

0.029 4 cans Exposures assumed to be negligible.

Mixers/Loaders/Applicators

Exposure 

Scenario

Crop or Target App. 

Ratea

(lb ai/

gallon)

Area 

Treatedb

(gallon/

day)

SL/No

G

No R

SL/G

NoR

DL/G

No R

SL/No G

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No

G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Liquid: 

Manually 

Pressurized 

Handwand –

Concentrate 

(12a)

Wood Protection 

Treatment 0.17

40

0.37 30 32 0.37 63 70 0.37 73 82 No Data

Nursery

(Pine Seedlings) 0.16 0.39 32 34 0.39 67 76 0.39 77 90 No Data

Wide Area/ General 

Outdoor Treatment 0.082 0.75 63 66 0.76 130 150 0.76 150 170 No Data

Christmas Tree 

Plantations, Conifers 

and Deciduous Trees; 

Grapes, Plantation 

Nurseries, Seed 

0.030 2.1 170 180 2.1 360 400 2.1 410 470 No Data
Page 148 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Orchard Trees

Forest Trees 

(softwoods, conifers) 0.024 2.6 210 230 2.6 450 510 2.6 510 590 No Data

Golf Course Turf, 

Mounds/Nests, NonAgricultural Outdoor 

Buildings and 

Structures, Ornamental 

Woody Shrubs and 

Vines

0.010 6.3 520 540 6.3 1100 1200 6.3 1300 1400 No Data

Ornamental Lawns 

and Turf, Sod Farms 

(Turf)

3.76

(lb 

ai/A)

0.023 A

(spot 

treatment)

29 2400 2500 29 4900 5500 29 5700 6500 No Data

Ornamental and/or 

Shade Trees, 

Herbaceous Plants

2

(lb 

ai/A)

54 4500 4700 54 9500 11000 54 11000 12000 No Data

Golf Course Turf, 

Non-Agricultural 

Outdoor Buildings and 

Structures

1

(lb 

ai/A)

110 9000 9500 110 18000 21000 110 21000 25000 No Data

Liquid: 

Manually 

Pressurized 

Handwand -

Wettable 

Powder in 

WSP (12b)

Ornamental Lawns 

and Turf, Sod Farms 

(Turf)

3.76

(lb 

ai/A) 0.023 A

(spot 

treatment)

29 2400 2500 29 4900 5500 29 5700 6500 No Data

Ornamental and/or 

Shade Trees, 

Herbaceous Plants

2

(lb 

ai/A)

54 4500 4700 54 9500 11000 54 11000 12000 No Data

Liquid: 

Manually 

Pressurized 

Handwand –

Microencapsulated 

(12c)

Indoor and Outdoor 

Commercial/

Institutional/

Industrial (C&C)

0.042

40

2.6 3.9 4.2 4.3 10 12 4.6 13 16 No Data

Ornamental Woody 

Shrubs and Vines 0.010 6.3 520 540 6.3 1100 1200 6.3 1300 1400 No Data

Ornamental NonFlowering Plants 0.0070 8.8 720 760 8.9 1500 1700 8.9 1800 2000 No Data

Outdoor 

Commercial/Institutio

nal/Industrial Premises 

0.00011

(lb ai/

1,000 

22 1800 1900 22 3800 4200 22 4400 5000 No Data
Page 149 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

(direct spray) sq ft)

Agricultural Farm 

Premises

0.00007

5 (lb ai/

1,000 

sq ft)

33 2700 2900 33 5700 6300 33 6600 7500 No Data

Poultry Litter

0.00007

1(lb ai/

1,000 

sq ft)

35 2900 3100 35 6000 6700 35 6900 7900 No Data

Liquid: 

Backpack 

Sprayers -

Liquid 

Concentrate 

(12d)

Wood Protection 

Treatment, Rights-ofway 0.17

40

11 11 15 14 14 21 15 15 22 No Data

Wide Area/ General 

Outdoor Treatment 0.082 9.1 9.1 19 9.2 9.2 19 9.2 9.2 19 No Data

Christmas Tree 

Plantations, Tree Fruit 

(Cherries) – foliar, 

stump treatment

0.030

12 14 21 15 18 30 16 18 32 No Data

Seed Orchard Trees –

foliar, stump treatment 12 14 21 15 18 30 16 18 32 No Data

Tree Fruit (Cherries) –

drench/soil-, grounddirected25 25 50 25 25 51 25 25 51 No Data

Forest Trees 

(softwoods, conifers) -

foliar

0.024

16 17 26 19 22 38 19 22 40 No Data

Forest Trees 

(softwoods, conifers) -

drench/soil-, grounddirected

32 32 62 32 32 63 32 32 63 No Data

Grapes - foliar 

0.023

16 18 28 20 23 39 20 23 42 No Data

Grapes - drench/soil-, 

ground-directed 33 33 65 33 33 66 33 33 66 No Data

Golf Course Turf 0.010 37 42 63 45 53 89 46 54 94 No Data
Page 150 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Ornamental Lawns 

and Turf, Sod Farms 

(Turf)

3.76

(lb 

ai/A)

0.023 A 350 350 690 350 350 700 350 350 700 No Data

Ornamental and/or 

Shade Trees, 

Herbaceous Plants

2.0

(lb 

ai/A)

5 A 1.5 1.7 2.5 1.8 2.1 3.6 1.8 2.1 3.8 No Data

0.023 A

(spot 

treatment)

320 370 550 390 460 780 400 470 820 No Data

Outdoor 

Commercial/Institutio

nal/Industrial Premises 

(see master label 

description), NonAgricultural Outdoor 

Buildings and 

Structures

1.0

(lb 

ai/A)

5 A 6.1 6.1 12 6.1 6.1 12 6.1 6.1 12 No Data

0.023 A

(spot 

treatment)

1300 1300 2600 1300 1300 2600 1300 1300 2600 No Data

Liquid: 

Backpack 

Sprayer –

Wettable 

Powder in 

WSP (12e)

Onramental Woody 

Shrubs and Vines 0.00040 40 930 1100 1600 1100 1300 2200 1200 1400 2400 No Data

Onramental Woody 

Shrubs and Vines (pretransplant), 

4.0

(lb 

ai/A) 0.023 A

(spot 

treatment)

330 330 650 330 330 660 330 330 660 No Data

Ornamental Lawns 

and Turf, Sod Farms 

(Turf)

3.76 

(lb 

ai/A)

350 350 690 350 350 700 350 350 700 No Data

Ornamental and/or 

Shade Trees, 

Herbaceous Plants

2.0

(lb 

ai/A)

5 A 1.93 1.64 0.923 2.4 2.8 4.7 2.5 3 5.1 No Data

Liquid: 

Backpack 

Sprayer –

Microencapsu

lated (12f)

Ornamental Woody 

Shrubs and Vines 0.10

40

37 42 63 45 53 89 46 54 94 No Data

Ornamental Nonflowering Plants 0.0070 53 60 88 64 75 130 66 77 130 No Data

Outdoor 

Commercial/Institutio

nal/Industrial Premises 

0.00013

(lb ai/

1,000 

1,000 sq ft 230 230 460 230 230 470 230 230 470 No Data
Page 151 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

(see master label 

description)

sq ft)

Agricultural Farm

Premises (see master 

label description)

0.00007

5

(lb ai/

1,000 

sq ft)

400 400 800 400 400 810 400 400 810 No Data

Poultry Litter

0.00007

1(lb ai/

1,000 

sq ft)

1100 1100 1500 1300 1300 2000 1400 1400 2100 No Data

Liquid: 

Mechanically 

Pressurized 

Handgun –

Concentrate 

(12g)

Wide Area/ General 

Outdoor Treatment 0.082

1,000 sq ft

2.1 6.2 8 2.3 7.4 10 2.3 7.6 11 No Data

Christmas Tree 

Plantations, Conifers 

and Deciduous Trees; 

Plantation, Nursery, 

Nectarines, Seed 

Orchard Trees – foliar, 

stump treatment

0.03 5.9 17 21 6.3 20 27 6.3 20 28 No Data

Grapes, Ornamental 

Woody Shrubs and 

Vines - foliar

0.03 5.9 17 21 6.3 20 27 6.3 20 28 No Data

Tree Fruit (Nectarines) 

– drench/soil-, grounddirected0.03 5.9 17 21 6.3 20 27 6.3 20 28 No Data

Forest Trees 

(softwoods, conifers) –

foliar, stump treatment

0.024 7.4 21 26 7.9 26 34 7.9 26 35 No Data

Golf Course Turf 0.010 21 27 50 22 28 55 22 28 55 No Data

Tree Nuts (Almonds) 

– foliar, orchard floors

4.0

(lb 

ai/A)

8.9 25 32 9.5 30 40 9.5 31 42 No Data

Ornamental Lawns 

and Turf, Sod Farms 

(Turf) - foliar

3.76

(lb 

ai/A) 5 A

11 30 27 12 33 29 12 34 30 No Data

Tree Fruit (Nectarines) 

- foliar 3.0 12 34 43 13 41 54 13 42 56 No Data
Page 152 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Grapes – drench/soil-, 

ground-directed 2.25 16 45 57 17 54 72 17 56 74 No Data

Ornamental and/or 

Shade Trees 

Herbaceous Plants

2.0 18 51 63 19 61 80 19 62 83 No Data

Seed Orchard Trees 0.020 1800 5100 6300 1900 6100 8000 1900 6200 8300 No Data

Liquid: 

Mechanically 

Pressurized 

Handgun –

Wettable 

Powder in

WSP (12h)

Ornamental Woody 

Shrubs and Vines 0.00040 1,000 sq ft 440 1300 1600 470 1500 2100 480 1600 2100 No Data

Ornamental Lawns 

and Turf, Sod Farms 

(Turf)

3.76

(lb 

ai/A)

5 Acres

9.3 27 34 9.8 32 43 9.9 33 44 No Data

Ornamental and/or 

Shade Trees, 

Herbaceous Plants

2.0

(lb 

ai/A)

18 51 63 19 61 80 19 62 83 No Data

Liquid: 

Mechanically 

Pressurized 

Handgun –

Microencapsu

lated (12i)

Outdoor 

Commercial/Institutio

nal/Industrial Premises 

(see master label 

description)

0.042

1000

4.2 12 15 4.4 14 19 4.5 15 19 No Data

Ornamental Nonflowering Plants 0.010 18 51 63 19 61 80 19 62 83 No Data

Granule: 

Hand 

Dispersal 

(13a)

Commercial/Institutio

nal/Industrial 

Premises, Utilities 

(Pad)

191

(lb 

ai/A) 0.023 A

(spot 

treatment)

0.49 0.68 1.1 0.54 0.77 1.3 0.54 0.79 1.4 No Data

Golf Course (Turf), 

Sod Farm (Turf)

1

(lb 

ai/A)

90 130 210 98 150 250 99 150 260 No Data

Granule: 

Rotary 

Spreader 

(13b)

Ornamental Woody 

Shrubs and Vines

6.0

(lb 

ai/A)

5

Acres

12 17 21 17 29 46 18 32 53 No Data

Nursery Stock (see 

master label 

description)

1.1

(lb 

ai/A)

63 90 110 90 160 250 94 170 290 No Data

Golf Course Turf, 

Ornamental and/or 

1.0

(lb 70 100 130 99 170 280 100 190 320 No Data
Page 153 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Shade Trees, 

Herbaceous Plants, 

Ornamental Lawns 

and Turf, Sod Farms 

(Turf)

ai/A)

Granule: 

Spoon (13c)

Nursery Stock (see 

master label 

description)

1.1

(lb 

ai/A)

1400 1600 2100 2100 2700 4500 2200 3000 5200 No Data

Golf Course Turf 

(Mounds), Ornamental 

and/or Shade Trees, 

Herbaceous Plants, 

Sod Farm (Turf)

1.0

(lb 

ai/A)

1500 1700 2300 2300 3000 4900 2400 3300 5700 No Data

Granule: 

Belly Grinder 

(13d)

Ornamental Woody 

Shrubs and Vines

6.0

(lb 

ai/A)

1

Acre

3.6 3.8 5.7 4.1 4.3 6.9 4.1 4.4 7.1 No Data

Nursery Stock (see 

master label 

description)

1.1

(lb 

ai/A)

20 21 31 22 24 38 23 25 39 No Data

Golf Course Turf, 

Ornamental and/or 

Shade Trees, 

Herbaceous Plants, 

Ornamental Lawns 

and Turf, Sod Farms 

(Turf)

1.0

(lb 

ai/A)

21 23 34 24 26 42 25 27 43 No Data

Water 

Dispersable 

Granule in 

WSP: 

Manually 

Pressurized 

Handwand 

(14a)

Christmas Tree 

Plantations, Tree 

Fruits (Cherries, 

Nectarines, Peaches, 

Plum/Prunes); Tree 

Nuts (Almonds) – preplant

0.030

40

2.1 170 180 2.1 360 400 2.1 410 470 No Data

Tree Nuts (Apple) -

pre-plant 0.015 4.2 340 360 4.2 710 770 4.2 820 910 No Data

Ornamental Woody 

Shrubs and Vines -

foliar

2.0

(lb a/A)

0.023 A

(spot 

treatment)

54 4500 4700 54 9500 11000 54 11000 12000 No Data
Page 154 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Fruits and Nuts (nonbearing, see master 

label description) –

foliar, trunk spray, 

drench

54 4500 4700 54 9500 11000 54 11000 12000 No Data

Grapes (Pre-Bloom)

1.0

(lb 

ai/A)

110 9000 9500 110 18000 21000 110 21000 25000 No Data

Water 

Dispersable 

Granule in 

WSP: 

Backpack 

(14b)

Christmas Tree 

Plantations, Tree 

Fruits (Cherries), Tree 

Nuts (Almond), Tree 

Fruit (Nectarine, 

Peach, Plum/Prune) -

foliar

0.030

40

12 14 21 15 18 30 16 18 32 No Data

Christmas Tree 

Plantations, Tree 

Fruits (Cherries), Tree 

Nuts (Almond), Tree 

Fruit (Nectarine, 

Peach, Plum/Prune) –

drench/ soil-, grounddirected

25 25 50 25 25 51 25 25 51 No Data

Fruit and Nut (Nonbearing, Nursery) -

foliar

0.020

19 21 31 23 26 45 23 27 47 No Data

Fruit and Nut (Nonbearing, Nursery) -

drench/ soil-, grounddirected

38 38 75 38 38 76 38 38 76 No Data

Tree Fruits (Apple) -

foliar 0.015

25 28 42 30 35 60 31 36 63 No Data

Tree Fruits (Apple) –

trunk spray, drench 50 50 98 50 50 100 50 50 100 No Data

Grapes (pre-bloom) -

foliar 0.010

37 42 63 45 53 89 46 54 94 No Data

Grapes (pre-bloom) –

drench/ soil-, ground75 75 150 76 76 150 76 76 150 No Data
Page 155 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

directed

Ornamental Woody 

Shrubs and Vines

2.0

(lb 

ai/A)

5 A 1.5 1.7 2.5 1.8 2.1 3.6 1.8 2.1 3.8 No Data

Water 

Dispersable 

Granule in 

WSP: 

Mechanically 

Pressurized 

Handgun 

(14c)

Christmas Tree 

Plantations, Tree 

Fruits (Cherries), Tree 

Nuts (Almond), Tree 

Fruit (Nectarine, 

Peach, Plum/Prune) –

foliar, drench/ soil-, 

ground-directed

0.030

1000

5.9 17 21 6.3 20 27 6.3 20 28 No Data

Tree Fruit (Apples) 0.015 12 34 43 13 41 54 13 42 56 No Data

Grapes 0.010 18 51 63 19 61 80 19 62 83 No Data

Ornamental Woody 

Shrubs and Vines

2.0

(lb 

ai/A)

5 A 18 51 63 19 61 80 19 62 83 No Data

Flaggers

Citrus 2.3

350

15 15 16 24 23 25 26 24 27 No Data

Non-bearing Fruit and 

Nut Trees (Nursery), 

Radish (pre-plant), 

Sweet Potato (preplant)

2.1 17 16 17 26 24 27 29 26 29 No Data

Cherries, Mint 

(Peppermint and 

Spearmint), 

Ornamental and/or 

Shade Trees, 

Herbaceous Plants, 

Peanut, Rutabaga, 

Strawberries (preplant), Sunflower (preplant), Tobacco, Tree 

Fruits (Apple, Fig (CA 

only), Nectarine, 

2 18 17 18 27 26 29 30 28 31 No Data
Page 156 of 227

Table F.1. Chlorpyrifos Occupational Handler Non-Cancer Risk Estimates

Exposure 

Scenario

Crop or Target App. 

Ratea

(lbai/A)

Area 

Treatedb

(A/ day)

Total MOE (LOC is an MOE = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Peach, Pear, 

Plum/Prune), Tree 

Nuts (Almonds, 

Filberts/Hazelnuts, 

Pecans, Walnuts), 

Turfgrass (Ornamental 

and Sod Farms), 

Ornamental and/or 

Shade Trees, 

Herbaceous Plants

Clover (grown for 

seed; foliar), 

Cranberry, Hybrid 

Cottonwood/ Poplar 

Plantations Grown for 

Pulp, Sunflower (postemergence/ foliar)

1.9 19 18 19 29 27 31 31 29 33 No Data

Asparagus, Brussel 

Sprouts, Cauliflower, 

Cole Crops, Corn 

(post-emergence), 

Strawberries, 

Sugarbeets, Radish

1.5 24 23 24 37 35 38 40 37 41 No Data

Alfalfa, Christmas 

Tree Plantations, Cole 

Crops (excludes 

Brussel Sprouts and 

Cauliflower), Corn 

(pre-plant), Cotton 

(except MS), 

Sorghum, Soybean, 

Wheat 

1 35 34 36 56 52 57 60 56 62 No Data

Carrots 0.94 38 36 39 59 55 61 64 59 66 No Data

Flagger: 

Granule (15b)

Peanuts 4.0

350

27 27 32 51 51 74 57 58 88 No Data

Sweet Potato 2.1 50 50 62 94 94 140 110 110 170 No Data

Corn (pre-plant), 

Sunflower, Tobacco 2.0 54 54 65 100 100 150 110 110 180 No Data

Turf (Sod Farms) 1.0 110 110 130 200 200 300 230 230 360 No Data
SL/NoG/NoR = single layer clothing, no glove, no respirator; SL/G/NoR = single layer clothing, gloves, no 

respirator; DL/G/NoR = double layer clothing, gloves, no respirator; SL/NoG/PF5R = single layer clothing, no 

gloves, PF5 respirator; SL/G/PF5R = single layer, gloves, PF respirator; D/G/PF5R = double layer clothing, gloves, 

PF5 respirator; SL/NoG/PF10R = single layer clothing, no gloves, PF10 respirator; SL/G/PF10R = single layer 

clothing, gloves, PF10 respirator; DL/G/PF10R = double layer clothing, gloves, PF10 respirator; EC = engineering 

controls
Table F.2. Chlorpyrifos Occupational Handler Airblast Non-Cancer Risk Estimates

Exposure 

Scenario Crop or Target

App. 

Rate1

(lbai/A)

Area

Treated2

(A/ day)

Total MOE3(LOC = 100)

SL/NoG

No R

SL/G

NoR

DL/G

No R

SL/NoG

PF5 R

SL/G

PF5 R

DL/G

PF5 R

SL/No G

PF10 R

SL.G

PF10 R

DL/G

PF10 R EC

Applicators

Airblast

Applications 

(6a)

Citrus (CA and AZ) 6.0

40

0.55 0.61 0.65 0.55 0.61 0.65 0.59 0.65 0.7 64

Tree Nuts (Pecans) 4.3 0.77 0.85 0.91 0.77 0.85 0.91 0.81 0.91 0.97 89

Citrus 4.0 0.83 0.92 1 0.83 0.92 1 0.88 0.98 1.1 98

Tree Fruits 

(nectarines, peaches 

– dormant, delayed 

dormant)

3.0 1.1 1.2 1.3 1.1 1.2 1.3 1.2 1.3 1.4 1100

Tree Nuts (almonds, 

filberts/hazelnuts, 

walnuts), Tree Fruits 

(apples, cherries, 

pears, plums/prunes)

2.0

1.7 1.9 1.9 1.7 1.9 1.9 1.8 2 2.1 190

Ornamental Woody 

Shrubs and Vines, 

Ornamental and/or 

Shade Trees, 

Herbaceous Plants

20 3.3 3.6 3.9 3.3 3.6 3.9 3.5 3.9 4.2 380

Asparagus, 

Christmas Tree 

Plantations, Grapes, 

Sugarbeets

1.0 40 3.3 3.6 3.9 3.3 3.6 3.9 3.5 3.9 4.2 380
Page 159 of 227

Table F.2. Chlorpyrifos Occupational Handler Airblast Non-Cancer Risk Estimates

Exposure 

Scenario Crop or Target

App. 

Ratea

(lbai/A)

Area

Treatedb

(A/ day)

Total MOE (LOC = 100)

SL/G/ 

CRH

No R

DL/G

CRH

No R

SL/G

CRH

PF5 R

DL/G

CRH

PF5 R

SL/G

CRH

PF10 R

DL/G

CRH

PF10R

Airblast

Applications 

(6a)

Citrus (CA and AZ) 6.0

40

3.1 3.9 3.1 3.9 4.6 6.8

Tree Nuts (Pecans) 4.3 4.3 5.5 4.3 5.5 6.4 9.2

Citrus 4.0 4.7 6 4.7 6 6.9 10

Tree Fruits 

(nectarines, peaches 

– dormant, delayed 

dormant)

3.0 6.2 8 6.2 8 9.2 14

Tree Nuts (almonds, 

filberts/hazelnuts, 

walnuts), Tree Fruits 

(apples, cherries, 

pears, plums/prunes) 2.0

9.4 12 9.4 12 14 20

Ornamental Woody 

Shrubs and Vines, 

Ornamental and/or 

Shade Trees, 

Herbaceous Plants

20 18 24 18 24 27 41

Asparagus, 

Christmas Tree 

Plantations, Grapes, 

Sugarbeets

1.0 40 18 24 18 24 27 41
SL/NoG/NoR = single layer clothing, no glove, no respirator; SL/G/NoR = single layer clothing, gloves, no 

respirator; DL/G/NoR = double layer clothing, gloves, no respirator; SL/NoG/PF5R = single layer clothing, no 

gloves, PF5 respirator; SL/G/PF5R = single layer, gloves, PF respirator; D/G/PF5R = double layer clothing, gloves, 

PF5 respirator; SL/NoG/PF10R = single layer clothing, no gloves, PF10 respirator; SL/G/PF10R = single layer 

clothing, gloves, PF10 respirator; DL/G/PF10R = double layer clothing, gloves, PF10 respirator; EC = engineering 

controls
Page 161 of 227

Appendix G: Dermal and Inhalation Unit Exposures Use for Chlorpyrifos Occupational 

Handler Assessment
Table G.1. Dermal and Inhalation Unit Exposures Used for Chlorpyrifos Occupational Handler Exposure and Risk Assessment

Exposure Scenario Dermal Unit Exposures (μg/lb ai) Inhalation Unit Exposures (μg/lb ai)

SL/No G SL/G DL/G SL/G/CRH DL/G/CRH EC No-R PF5 R PF10 R EC

Mixing/Loading

Liquids for Aerial and/or

Chemigation Applications 

(1a)

220 37.6 29.1 No Data No Data 8.6 0.219 0.0438 0.0219 0.083

Mixing/Loading Liquids for 

Airblast Application (1b)

Mixing/Loading Liquids for 

Groundboom Application 

(1c)

Mixing/Loading Liquids for 

Wide Area Aerial 

Applications (1d)

Mixing/Loading Liquids for 

Wide Area Ground 

Applications (1e)

Mixing/Loading Wettable 

Powder (in WSP) for Aerial 

Applications (2a)

No Data No Data No Data No Data No Data 9.8 No Data No Data No Data 0.24

Mixing/Loading Wettable 

Powder (in WSP) for 

Airblast Applications (2b)

Mixing/Loading Wettable 

Powder (in WSP) for 

Groundboom Applications 

(2c)

Mixing/Loading Granulars

for Aerial Applications (3a)

Mixing/Loading Granulars 8.4 6.9 3.4 No Data No Data 8.6 1.7 0.34 0.17 0.083

for Tractor Drawn Spreader 

Applications (3b)

Mixer/Loader Granulars 

with SmartBox® for Aerial 

Applications (3c) No Data No Data No Data No Data No Data 0.20 No Data No Data No Data 0.003 Mixer/Loader Granulars 

with SmartBox® for Tractor 

Drawn Spreader 
Page 163 of 227

Table G.1. Dermal and Inhalation Unit Exposures Used for Chlorpyrifos Occupational Handler Exposure and Risk Assessment

Exposure Scenario Dermal Unit Exposures (μg/lb ai) Inhalation Unit Exposures (μg/lb ai)

SL/No G SL/G DL/G SL/G/CRH DL/G/CRH EC No-R PF5 R PF10 R EC

Applications (3d)

MRID: 44180401

Mixer/Loader Water 

Dispersable Granulars (in 

WSP) for Aerial and/or 

Chem. Applications (4a)

No Data No Data No Data No Data No Data 9.8 No Data No Data No Data 0.24

Mixer/Loader Water 

Dispersable Granulars (in 

WSP) for Airblast 

Applications (4b)

Mixer/Loader Water 

Dispersable Granulars (in 

WSP) for Ground-boom 

Applications (4c)

Aerial Liquid Application 

(5a) No Data No Data No Data No Data No Data 2.08 No Data No Data No Data 0.0049 Wide Area Aerial 

Applications (5b)

Aerial Granular 

Applications (5c) No Data No Data No Data No Data No Data 1.7 No Data No Data No Data 1.3

Airblast Applications (6a)

Wide Area Ground 1,770 1,590 1,480 215 141 14.6 4.71 0.942 0.471 0.068

Applications (6b)

Ground-boom Applications 

(7a) 78.6 16.1 12.6 No Data No Data 5.1 0.34 0.068 0.034 0.043

Tractor Drawn Granular 

Spreader Applications (7b) 9.9 7.2 4.2 No Data No Data 2 1.2 0.24 0.12 0.22

Tractor Drawn Granular 

Spreader Applications with 

SmartBox® (7c)

MRID 44301301

No Data 0.81 No Data No Data No Data No Data 0.12 No Data No Data No Data

Paint Brush/Roller 

Applications (8) 180,000 24,000 22,000 No Data No Data No Data 280 56 28 No Data

Ear Tag Applications (9)

Bait Station Applications Exposures assumed to be negligible.

(10)
Page 164 of 227

Table G.1. Dermal and Inhalation Unit Exposures Used for Chlorpyrifos Occupational Handler Exposure and Risk Assessment

Exposure Scenario Dermal Unit Exposures (μg/lb ai) Inhalation Unit Exposures (μg/lb ai)

SL/No G SL/G DL/G SL/G/CRH DL/G/CRH EC No-R PF5 R PF10 R EC

Total Release Fogger (11)

Liquid: Manually 

Pressurized Handwand –

Concentrate (12a)

100,000 430 365 No Data No Data No Data 30 6 3 No Data

Liquid: Manually 

Pressurized Handwand -

Wettable Powder in WSP 

(12b)

Liquid: Manually 

Pressurized Handwand –

Microencapsulated (12c)

- Crack and Crevice

29,000 8,600 6,200 No Data No Data No Data 1,100 220 110 No Data

Liquid: Manually 

Pressurized Handwand –

Microencapsulated (12c) - -

- Broadcast

100,000 430 365 No Data No Data No Data 30 6 3 No Data

Liquid: Backpack Sprayers -

Liquid Concentrate (12d)

- Spot, 

Drench/Soil/GroundDirected

8,260 8,260 4,120 No Data No Data No Data 2.58 0.516 0.258 No Data

Liquid: Backpack Sprayers -

Liquid Concentrate (12d)

- Broadcast, Foliar

13,200 11,200 6,230 No Data No Data No Data 140 28 14 No Data

Liquid: Backpack Sprayer –

Wettable Powder in WSP 

(12e)

8,260 8,260 4,120 No Data No Data No Data 2.58 0.516 0.258 No Data

Liquid: Backpack Sprayer –

Microencapsulated (12f)

- Ornamentals

13,200 11,200 6,230 No Data No Data No Data 140 28 14 No Data

Liquid: Backpack Sprayer –

Microencapsulated (12f)

- Outdoor Premises

8,260 8,260 4,120 No Data No Data No Data 2.58 0.516 0.258 No Data

Liquid: Backpack Sprayer –

Microencapsulated (12f)

- Poultry

2,510 2,500 1,600 No Data No Data No Data 30 6 3 No Data
Page 165 of 227

Table G.1. Dermal and Inhalation Unit Exposures Used for Chlorpyrifos Occupational Handler Exposure and Risk Assessment

Exposure Scenario Dermal Unit Exposures (μg/lb ai) Inhalation Unit Exposures (μg/lb ai)

SL/No G SL/G DL/G SL/G/CRH DL/G/CRH EC No-R PF5 R PF10 R EC

Liquid: Mechanically 

Pressurized Handgun –

Concentrate (12g)

- Ornamentals, Golf Course

1,140 880 450 No Data No Data No Data 1.9 0.38 0.19 No Data

Liquid: Mechanically 

Pressurized Handgun –

Concentrate (12g)

- Broadcast, Foliar

1,300 390 290 No Data No Data No Data 3.9 0.78 0.39 No Data

Liquid: Mechanically 

Pressurized Handgun –

Wettable Powder in WSP 

(12h)

Liquid: Mechanically 

Pressurized Handgun –

Microencapsulated (12i)

Granule: Hand Dispersal 

(13a) 104,000 71,000 40,280 No Data No Data No Data 470 94 47 No Data

Granule: Rotary Spreader 

(13b) 440 240 130 No Data No Data No Data 10 2 1 No Data

Granule: Spoon (13c) 4,170 3,030 1,580 No Data No Data No Data 121 24.2 12.1 No Data

Granule: Belly Grinder 

(13d) 10,000 9,300 5,700 No Data No Data No Data 62 12.4 6.2 No Data

Water Dispersable Granule 

in WSP: Manually 

Pressurized Handwand 

(14a)

100,000 430 365 No Data No Data No Data 30 6 3 No Data

Water Dispersable Granule 

in WSP: Backpack (14b)

- Drench/Soil/GroundDirected

8,260 8,260 4,120 No Data No Data No Data 2.58 0.516 0.258 No Data

Water Dispersable Granule 

in WSP: Backpack (14b)

- Broadcast, Foliar

13,200 11,200 6,230 No Data No Data No Data 140 28 14 No Data

Water Dispersable Granule 

in WSP: Mechanically 

Pressurized Handgun (14c)

1,300 390 290 No Data No Data No Data 3.9 0.78 0.39 No Data
Page 166 of 227

Table G.1. Dermal and Inhalation Unit Exposures Used for Chlorpyrifos Occupational Handler Exposure and Risk Assessment

Exposure Scenario Dermal Unit Exposures (μg/lb ai) Inhalation Unit Exposures (μg/lb ai)

SL/No G SL/G DL/G SL/G/CRH DL/G/CRH EC No-R PF5 R PF10 R EC

Flagger: Liquid Sprays 

(15a) 11 12 10.6 No Data No Data No Data 0.35 0.07 0.035 No Data

Flagger: Granule (15b) 2.75 2.73 1.59 No Data No Data No Data 0.15 0.03 0.015 No Data
Appendix H: Summary of Chlorpyrifos Seed Treatment and Secondary Handler Exposure 

and Risks
Table H.1. Summary of Chlorpyrifos Commercial Seed Treatment Steady State Combined (Dermal and Inhalation) Exposure/Risk

Exposure 

Scenario 

Crop App. 

Ratea

(lb ai/

lb seed)

Amount 

Treatedb 

(lb seed/ 

per day)

Amount 

Handled 

per Dayc

(lb 

ai/day)

Level of Personal Protection – LOC is an MOE = 100

SL/NG/

NRd

SL/G/

NRe

SL/G/

PF5f

SL/G/

PF10g

DL/G/

NRh

DL/G/

PF5i

DL/G/

PF10j

Liquid (EC)

Loader/Applicator

Loading/ 

Applying

Liquid for

Seed 

Treatment 

(1)

Beans (Field, 

Green, 

Kidney, Corn 

(Sweet), 

Lima, Navy, 

Snap, String, 

Wax), Peas

0.00058

281,250

(ST)

163 No Data 48 57 62 64 78 81

200,000

(IT)

116 No Data 68 80 87 90 109 114

Corn (All) 0.00058

339,500

(ST)

197 No Data 40 47 51 53 64 67

240,000

(IT)

139 No Data 56 67 73 75 91 95

Cotton 

(Delinted) 0.0012

339,500

(ST)

407 No Data 19 23 25 26 31 33

240,000

(IT)

288 No Data 27 32 35 36 44 46

Cucumber 0.00058

3,000

(S/IT)

1.7 No Data 4,500 5,300 5,800 6,000 7,300 7,600

Pumpkin 0.00058

3,000

(S/IT)

1.7 No Data 4,500 5,300 5,800 6,000 7,300 7,600

Sorghum 

Grain, 

0.000024

360,000

(ST)

9 No Data 910 1,100 1,200 1,200 1,500 1,500
Page 169 of 227

Table H.1. Summary of Chlorpyrifos Commercial Seed Treatment Steady State Combined (Dermal and Inhalation) Exposure/Risk

Exposure 

Scenario 

Crop App. 

Ratea

(lb ai/

lb seed)

Amount 

Treatedb 

(lb seed/ 

per day)

Amount 

Handled 

per Dayc

(lb 

ai/day)

Level of Personal Protection – LOC is an MOE = 100

SL/NG/

NRd

SL/G/

NRe

SL/G/

PF5f

SL/G/

PF10g

DL/G/

NRh

DL/G/

PF5i

DL/G/

PF10j

Triticale, 

Wheat 180,000

(IT)

4 No Data 1,800 2,200 2,300 2,400 2,900 3,100

Sewer

Sewing 

Seeds after 

Seed 

treatment 

(2)

Beans (Field, 

Green, 

Kidney, 

Lima, Navy, 

Snap, String, 

Wax), Corn 

(Sweet), Peas

0.00058

281,250

(ST)

163 130 No Data No Data No Data No Data No Data No Data

200,000

(IT)

116 180 No Data No Data No Data No Data No Data No Data

Corn (All) 0.0058

339,500

(ST)

197 100 No Data No Data No Data No Data No Data No Data

240,000

(IT)

139 150 No Data No Data No Data No Data No Data No Data

Cotton 

(Delinted) 0.0012

339,500

(ST)

407 50 No Data No Data No Data No Data No Data No Data

240,000

(IT)

288 71 No Data No Data No Data No Data No Data No Data

Cucumber 0.00058

3,000

(S/IT)

1.7 12,000 No Data No Data No Data No Data No Data No Data

Pumpkin 0.00058

3,000

(S/IT)

1.7 12,000 No Data No Data No Data No Data No Data No Data

Sorghum 

Grain, 

0.000024

360,000

(ST)

9 2,400 No Data No Data No Data No Data No Data No Data
Page 170 of 227

Table H.1. Summary of Chlorpyrifos Commercial Seed Treatment Steady State Combined (Dermal and Inhalation) Exposure/Risk

Exposure 

Scenario 

Crop App. 

Ratea

(lb ai/

lb seed)

Amount 

Treatedb 

(lb seed/ 

per day)

Amount 

Handled 

per Dayc

(lb 

ai/day)

Level of Personal Protection – LOC is an MOE = 100

SL/NG/

NRd

SL/G/

NRe

SL/G/

PF5f

SL/G/

PF10g

DL/G/

NRh

DL/G/

PF5i

DL/G/

PF10j

Triticale, 

Wheat

180,000

(IT)

4 4,700 No Data No Data No Data No Data No Data No Data

Bagger 

Bagging 

Seeds after 

Seed 

treatment 

(3)

Beans (Field, 

Green, 

Kidney, 

Lima, Navy, 

Snap, String, 

Wax), Corn 

(Sweet), Peas

0.00058

281,250

(ST)

163 120 No Data No Data No Data No Data No Data No Data

200,000

(IT)

116 160 No Data No Data No Data No Data No Data No Data

Corn (All) 0.0058

339,500

(ST)

197 96 No Data No Data No Data No Data No Data No Data

240,000

(IT)

139 140 No Data No Data No Data No Data No Data No Data

Cotton 

(Delinted) 0.0012

339,500

(ST)

407 46 No Data No Data No Data No Data No Data No Data

240,000

(IT)

288 65 No Data No Data No Data No Data No Data No Data

Cucumber 0.00058

3,000

(S/IT)

1.7 11,000 No Data No Data No Data No Data No Data No Data

Pumpkin 0.00058

3,000

(S/IT)

1.7 11,000 No Data No Data No Data No Data No Data No Data

Sorghum 

Grain, 

Triticale, 

0.000024

360,000

(ST)

9 2,200 No Data No Data No Data No Data No Data No Data
Page 171 of 227

Table H.1. Summary of Chlorpyrifos Commercial Seed Treatment Steady State Combined (Dermal and Inhalation) Exposure/Risk

Exposure 

Scenario 

Crop App. 

Ratea

(lb ai/

lb seed)

Amount 

Treatedb 

(lb seed/ 

per day)

Amount 

Handled 

per Dayc

(lb 

ai/day)

Level of Personal Protection – LOC is an MOE = 100

SL/NG/

NRd

SL/G/

NRe

SL/G/

PF5f

SL/G/

PF10g

DL/G/

NRh

DL/G/

PF5i

DL/G/

PF10j

Wheat 180,000

(IT)

4 4,400 No Data No Data No Data No Data No Data No Data

Multiple Activities Worker 

Multiple 

Activities 

for Seed 

treatment 

(4)

Beans (Field, 

Green, 

Kidney, 

Lima, Navy, 

Snap, String, 

Wax), Corn 

(Sweet), Peas

0.00058

281,250

(ST)

163 No Data 18 24 30 33 52 61

200,000

(IT)

116 No Data 26 34 43 47 73 86

Corn (All) 0.00058

339,500

(ST)

197 No Data 15 20 25 28 43 50

240,000

(IT)

139 No Data 21 29 36 39 61 71

Cotton 

(Delinted) 0.0012

339,500

(ST)

407 No Data 7 10 12 13 21 24

240,000

(IT)

288 No Data 10 14 17 19 30 34

Cucumber 0.00058

3,000

(S/IT)

1.7 No Data 1,700 2,300 2,900 3,100 4,900 5,700

Pumpkin 0.00058

3,000

(S/IT)

1.7 No Data 1,700 2,300 2,900 3,100 4,900 5,700

Sorghum 

Grain, 

0.000024

360,000

(ST)

9 No Data 350 460 580 630 1,000 1,200
Page 172 of 227

Table H.1. Summary of Chlorpyrifos Commercial Seed Treatment Steady State Combined (Dermal and Inhalation) Exposure/Risk

Exposure 

Scenario 

Crop App. 

Ratea

(lb ai/

lb seed)

Amount 

Treatedb 

(lb seed/ 

per day)

Amount 

Handled 

per Dayc

(lb 

ai/day)

Level of Personal Protection – LOC is an MOE = 100

SL/NG/

NRd

SL/G/

NRe

SL/G/

PF5f

SL/G/

PF10g

DL/G/

NRh

DL/G/

PF5i

DL/G/

PF10j

Triticale, 

Wheat

180,000

(IT)

4 No Data 690 920 1,200 1,300 2,000 2,300

Liquid (Microencapsulated)

Loader/ Applicator

Loading/ 

Applying

Liquid 

(Microencaps.)

for

Seed 

Treatment 

(5)

Beans (Field, 

Green, 

Kidney, 

Lima, Navy, 

Snap, String, 

Wax)

0.000798

281,250

(ST) 224 No Data 35 41 45 47 56 59

200,000

(IT) 160 No Data 49 58 63 66 79 83

Sewer

Sewing 

Seeds after

Seed 

Treatment 

(6)

Beans (Field, 

Green, 

Kidney, 

Lima, Navy, 

Snap, String, 

Wax)

0.000798

281,250

(ST) 224 91 No Data No Data No Data No Data No Data No Data

200,000

(IT) 160 130 No Data No Data No Data No Data No Data No Data

Bagger

Bagging 

Seeds after

Seed 

Treatment 

(7)

Beans (Field, 

Green, 

Kidney, 

Lima, Navy, 

Snap, String, 

Wax)

0.000798

281,250

(ST) 224 84 No Data No Data No Data No Data No Data No Data

200,000

(IT) 160 120 No Data No Data No Data No Data No Data No Data
Page 173 of 227

Table H.1. Summary of Chlorpyrifos Commercial Seed Treatment Steady State Combined (Dermal and Inhalation) Exposure/Risk

Exposure 

Scenario 

Crop App. 

Ratea

(lb ai/

lb seed)

Amount 

Treatedb 

(lb seed/ 

per day)

Amount 

Handled 

per Dayc

(lb 

ai/day)

Level of Personal Protection – LOC is an MOE = 100

SL/NG/

NRd

SL/G/

NRe

SL/G/

PF5f

SL/G/

PF10g

DL/G/

NRh

DL/G/

PF5i

DL/G/

PF10j

Multiple Activities Worker

Multiple 

Activities

for

Seed 

Treatment 

(8)

Beans (Field, 

Green, 

Kidney, 

Lima, Navy, 

Snap, String, 

Wax)

0.000798

281,250

(ST) 224 No Data 13 18 22 24 38 44

200,000

(IT) 160 No Data 19 25 31 34 53 62

Wettable Powder in Water Soluble Packaging (WSP)

Loader/ Applicator

Loading/ 

Applying

Liquid 

(Microencaps.)

for

Seed 

Treatment 

(9)

Beans (Field, 

Green, 

Kidney, 

Lima, Navy, 

Snap, String, 

Wax), Peas

0.00063

281,250

(ST)

176 No Data 45 53 57 60 72 75

200,000

(IT)

125 No Data 63 74 81 84 101 106

Corn (All)

339,500

(ST)

212 No Data 37 44 48 49 60 62

240,000

(IT)

150 No Data 52 62 67 70 84 88

Cucumber,

Pumpkin

3,000

(S/IT)

1.9 No Data 4,200 5,000 5,400 5,600 6,800 7,100
Page 174 of 227

Table H.1. Summary of Chlorpyrifos Commercial Seed Treatment Steady State Combined (Dermal and Inhalation) Exposure/Risk

Exposure 

Scenario 

Crop App. 

Ratea

(lb ai/

lb seed)

Amount 

Treatedb 

(lb seed/ 

per day)

Amount 

Handled 

per Dayc

(lb 

ai/day)

Level of Personal Protection – LOC is an MOE = 100

SL/NG/

NRd

SL/G/

NRe

SL/G/

PF5f

SL/G/

PF10g

DL/G/

NRh

DL/G/

PF5i

DL/G/

PF10j

Sewer

Sewing 

Seeds after

Seed 

Treatment 

(10)

Beans (Field, 

Green, 

Kidney, 

Lima, Navy, 

Snap, String, 

Wax), Peas

0.00063

281,250

(ST)

176 120 No Data No Data No Data No Data No Data No Data

200,000

(IT)

125 160 No Data No Data No Data No Data No Data No Data

Corn (All)

339,500

(ST)

212 96 No Data No Data No Data No Data No Data No Data

240,000

(IT)

150 140 No Data No Data No Data No Data No Data No Data

Cucumber,

Pumpkin

3,000

(S/IT)

1.9 11,000 No Data No Data No Data No Data No Data No Data

Bagger

Bagging 

Seeds after

Seed 

Treatment 

(11)

Beans (Field, 

Green, 

Kidney, 

Lima, Navy, 

Snap, String, 

Wax), Peas

0.00063

281,250

(ST)

176 110 No Data No Data No Data No Data No Data No Data

200,000

(IT)

125 150 No Data No Data No Data No Data No Data No Data

Corn (All)

339,500

(ST)

212 89 No Data No Data No Data No Data No Data No Data
Page 175 of 227

Table H.1. Summary of Chlorpyrifos Commercial Seed Treatment Steady State Combined (Dermal and Inhalation) Exposure/Risk

Exposure 

Scenario 

Crop App. 

Ratea

(lb ai/

lb seed)

Amount 

Treatedb 

(lb seed/ 

per day)

Amount 

Handled 

per Dayc

(lb 

ai/day)

Level of Personal Protection – LOC is an MOE = 100

SL/NG/

NRd

SL/G/

NRe

SL/G/

PF5f

SL/G/

PF10g

DL/G/

NRh

DL/G/

PF5i

DL/G/

PF10j

240,000

(IT)

150 130 No Data No Data No Data No Data No Data No Data

Cucumber,

Pumpkin

3,000

(S/IT)

1.9 10,000 No Data No Data No Data No Data No Data No Data

Multiple Activities Worker

Multiple 

Activities

for

Seed 

Treatment 

(12)

Beans (Field, 

Green, 

Kidney, 

Lima, Navy, 

Snap, String, 

Wax), Peas

0.00063

281,250

(ST)

176 No Data 17 23 28 31 48 57

200,000

(IT)

125 No Data 24 32 40 43 68 79

Corn (All)

339,500

(ST)

212 No Data 14 19 23 26 40 47

240,000

(IT)

150 No Data 20 26 33 36 57 66

Cucumber,

Pumpkin

3,000

(S/IT)

1.9 No Data 1,600 2,100 2,700 2,900 4,500 5,300
a. Application rates based on registered labels for chlorpyrifos seed treatment uses. 

b. HED default for Amount Treated (lbs seed treated per day) from HED Interim Guidance (SOP 15.1) Amount of 

Commercial Seed Treated per Day, updated March 21, 2013.

c. Amount Handled per Day (lb ai/ day) = application rate (lb ai/lb seed) x amount treated (lb seed treated/ day)

d. SL/NG/NR = Single layer clothing (long pants, long-sleeved shirt) no gloves, and no respirator

e. SL/G/NR = Single layer clothing with gloves and no respirator

f. SL/G/PF5 = Single layer clothing with gloves, protection factor 5 (PF5) respirator

g. SL/G/PF10 = Single layer clothing with gloves, protection factor 10 (PF10) respirator

h. DL/G/NR = Double layer clothing (coveralls over SL) with no gloves or respirator

i. DL/G/PF5 = Double layer clothing (coveralls over SL) with gloves, protection factor 5 (PF5) respirator

j. DL/G/PF10 = Double layer clothing (coveralls over SL) with gloves, protection factor 10 (PF10) respirator
Table H.2. Summary of Chlorpyrifos Steady State Combined (Dermal and Inhalation) Exposure/Risk from Planting Previously Treated Seeds (All 

Formulations)

Crop Max. 

Pounds 

Seed 

per 

Acrea

Acres 

Treated 

per Day

Pounds 

of Seed 

Treated 

per Day

App. 

Rate

(lb ai/

lb seed)b

Amount 

Handled 

per Day 

(lb ai/ 

day)c

Level of Personal Protection – LOC is an MOE = 100

SL/NG/

NRd

SL/G/

NRe

SL/G/

PF5f

SL/G/

PF10g

DL/G/

NRh

DL/G/

PF5i

DL/G/

PF10j

Beans 100

80

8,000

0.00058 4.6 No Data No Data 200 210 No Data No Data No Data

0.00063 5.0 No Data No Data 190 190 No Data No Data No Data

0.000798 6.4 No Data No Data 150 150 No Data No Data No Data

Peas 150 12,000 0.00058 6.96 No Data No Data 130 140 No Data No Data No Data

0.00063 7.5 No Data No Data 120 130 No Data No Data No Data

Corn (All) 15 200 3,000 0.00058 1.7 No Data No Data 540 560 No Data No Data No Data

0.00063 1.9 No Data No Data 500 520 No Data No Data No Data

Cotton 18 3,600 0.0012 4.3 No Data No Data 220 220 No Data No Data No Data

Cucumber 5

80

400 0.00058 0.23 No Data No Data 4,000 4,200 No Data No Data No Data

Pumpkin 4 320 0.00063 0.020 No Data No Data 4,700 4,800 No Data No Data No Data

Sorghum 10

200

2,000

0.000024

0.05 No Data No Data 19,000 20,000 No Data No Data No Data

Triticale 100 20,000 0.48 No Data No Data 1,900 2,000 No Data No Data No Data

Wheat 150 30,000 0.72 No Data No Data 1,300 1,300 No Data No Data No Data
a. Maximum pounds of seed per acre is based on HED SOP 15: Amount of Seed Treated or Planted per Day.

b. Application rates based on registered labels for chlorpyrifos seed treatment uses. 

c. Amount Handled per Day (lb ai/ day) = application rate (lb ai/lb seed) x amount treated (lbs seed treated/ day)

d. SL/NG/NR = Single layer clothing (long pants, long-sleeved shirt) no gloves, and no respirator

e. SL/G/NR = Single layer clothing with gloves and no respirator

f. SL/G/PF5 = Single layer clothing with gloves, protection factor 5 (PF5) respirator

g. SL/G/PF10 = Single layer clothing with gloves, protection factor 10 (PF10) respirator

h. DL/G/NR = Double layer clothing (coveralls over SL) with no gloves or respirator

i. DL/G/PF5 = Double layer clothing (coveralls over SL) with gloves, protection factor 5 (PF5) respirator

j. DL/G/PF10 = Double layer clothing (coveralls over SL) with gloves, protection factor 10 (PF10) respirator
Page 179 of 227

Appendix I: Occupational Post-application Exposure Data Summaries
Page 180 of 227

MRID 42974501 (Cauliflower and Tomato)

This DFR study (MRID 42974501), performed in conjunction with a passive dosimetry and 

biomonitoring study, examined the residues of chlorpyrifos on cauliflower and tomato. Three 

test sites were established in Arizona for the cauliflower trials and three tests sites were 

established in Florida for the tomato trials. Each test plot received a single application of 

Lorsban 50W (a wettable powder formulation) using tractor-mounted spray equipment at a 

nominal rate of 1 lb ai/A. Samples were taken from the control plot and treated plots using a 

Birkenstrand leaf punch (producing leaf discs approximately 2.5 cm2in area) at the following 

nominal sampling intervals: the day prior to application, following the application, and at day 1, 

2, 3, 5, 7, 14, 21, and 30 after the application. A total of 50 leaf discs were collected for each 

sample, totalling 250 cm2(front and back of 2.5 cm2singe puch x 50 leaf punches). The residues 

found within a given plot at a given time interval was the average of 3 samples collected within 

that plot. Samples were analyzed for residues of chlorpyrifos. A validated LOQ or LOD was not 

provided. Concurrent and method validation samples were analyzed. The average recoveries 

were 110±15.4% and 104±10.3%, respectively. The study corrected the field study samples for 

method validation recoveries, only if the recoveries were <100%. Field fortification data for the 

tomato sites were extremely variable, with a range of 12.7% to 990%. The study report suggests 

that either unknown interferences or poor techniques were responsible for the variability. For 

cauliflower, the overall average recovery was 99.2%. The field study samples were not 

corrected for field fortification recovery. 

The DFR values for cauliflower and tomatoes were reported as an average of three samples. 

Raw data was not provided. The DFR data for tomatoes were not used in the assessment due to 

uncertainty in the results based on the extremely variable field fortification recoveries and also 

because data from two of the sites were erratic. The three cauliflower sites were located in 

Arizona and have similar dissipation rates, therefore average daily DFR values were combined 

for the three sites and the regression was performed on the combined DFR values. The result of 

statistical analysis of the Arizona cauliflower data is presented in Table 

Actual average DFR values are provided in Table I.1. Predicted values calculated from the 

regressions are provided in Table I.2 for cauliflower. 

Table I.1. Summary of Actual DFR Values on Cauliflower After One Broadcast Foliar 

Application Chlorpyrifos

Sampling 

Interval 

(Days)

Actual Average DFR (μg/cm2)

Lorsban50W (Wettable Powder)

AZ - Site ABC AZ - Site DEF AZ - Site GHI

0 0.392 0.5270 1.24

1 0.508 0.4840 0.769

2 0.501 0.2560 0.341

3 0.368 0.2080 0.40

5 0.169 0.0900 0.304

7 0.142 0.0640 0.118
Page 181 of 227

Table I.1. Summary of Actual DFR Values on Cauliflower After One Broadcast Foliar 

Application Chlorpyrifos

Sampling 

Interval 

(Days)

Actual Average DFR (μg/cm2)

Lorsban50W (Wettable Powder)

AZ - Site ABC AZ - Site DEF AZ - Site GHI

14 0.026 0.0340 0.012

21 0.008 0.002 0.002

30 0.002 0.002 0.002

Notes:

1.LOD and LOQ were not reported. 

2.Residues did not require correction for field fortification recovery.

3.The nominal application rate was 1 lb ai/A.

Table I.2. Summary of Predicted DFR Values on Cauliflower After One Broadcast

Foliar Application

Time (Days)

Predicted DFR (μg/cm2)

Lorsban50W (Wettable Powder)

AZ - Site ABC AZ - Site DEF AZ - Site GHI AZ – All Sites

0 0.5319 0.3769 0.724 (1.2340) 0.526 (0.719)

1 0.5080 0.3090 0.574 (0.7690) 0.427 (0.587)

2 0.361 (0.501) 0.2533 0.4546 0.347 (0.366)

3 0.298 0.2077 0.360 0.281 (0.325)

4 0.245 0.1703 0.285 0.229

5 0.202 0.1396 0.226 0.186

6 0.167 0.1145 0.1792 0.1507

7 0.137 0.0939 0.1420 0.1224

8 0.113 0.0769 0.1125 0.0994

9 0.0934 0.0631 0.0892 0.0807

10 0.0770 0.0517 0.0707 0.0655

11 0.0634 0.0424 0.0560 0.0532

12 0.0523 0.0348 0.0444 0.0432

13 0.0431 0.0285 0.0352 0.0351

14 0.0355 0.0234 0.0279 0.0285

15 0.0293 0.0192 0.0221 0.0231

16 0.0241 0.0157 0.0175 0.0188

17 0.0199 0.0129 0.0139 0.0153

18 0.0164 0.0106 0.0110 0.0124

19 0.0135 0.0087 0.0087 0.0101

20 0.0111 0.0071 0.0069 0.0082

21 0.00918 0.3769 0.00546 0.0066

22 0.00756 0.3090 0.00433 0.0054

23 0.00623 0.2533 0.00343 0.0044
Page 182 of 227

Table I.2. Summary of Predicted DFR Values on Cauliflower After One Broadcast

Foliar Application

Time (Days)

Predicted DFR (μg/cm2)

Lorsban50W (Wettable Powder)

AZ - Site ABC AZ - Site DEF AZ - Site GHI AZ – All Sites

24 0.00514 0.2077 0.00272 0.00355 

25 0.00424 0.1703 0.00215 0.00288

26 0.00349 0.1396 0.00171 0.00234

27 0.00288 0.1145 0.00135 0.00190

28 0.00237 0.0939 0.00107 0.00154

29 0.00195 0.0769 0.00085 0.00125

30 0.00161 0.0631 0.00067 0.00102

r

2 0.99 0.93 0.93 0.93 

slope -0.19 -0.198 -0.23 -0.21

half-life (days) 3.59 3.49 2.98 3.33

Notes:

1. For the risk analysis, the predicted value shown was replaced with the actual value in parentheses (from 

Table 1) when the actual DFR data from either after the first or second application was higher than the 

predicted DFR data.

2. The nominal application rate was 1 lb ai/A. 

MRID 43062701 (Citrus)

This DFR study (MRID 43062701), performed in conjunction with a worker exposure and 

biomonitoring study, examined the residues of chlorpyrifos on citrus. Three test sites were 

established in California (Site No. 2 and 5 in Tulare County and Site No. 6 in Kern County). 

Lorsban 4E Insecticide (an emulsifiable concentrate formulation), was applied using an airblast 

spray application to citrus trees. One application was made at each test site at a nominal rate of 6 

lb ai/A. At each sampling interval, duplicate samples were taken from the control plots and 

duplicate samples from three subplots were taken from the treated plots using a Birkenstrand leaf 

punch. Leaf samples were collected prior to and following the application and at 1, 4, 5, 7, 14, 

21, 35, and 43 days after the application for Site No. 2, prior to and following the application and 

at 1, 2, 7, 14, and 40 days after the application for Site No. 5 and prior to and following the 

application and at 1, 2, 7, 14, 21, and 35 days after the application for Site No. 6. Samples were 

analyzed for residues of chlorpyrifos. The overall average concurrent recovery for Site No. 2 was 

101% ± 17.2% with recoveries ranging from 67.8% to 126% (n=26). The overall average 

concurrent recovery for Site No. 5 and No. 6 was 91.8% ± 10.1% with recoveries ranging from 

76.6% to 112% (n=29). A validated LOQ was not provided. The limit of detection (LOD) was 

set at approximately three (3) times the signal noise ratio for an analytical run. The LOD ranged 

from 0.0032 to 0.016 μg/cm2. The field study samples did not require correction for field 

fortification recovery. Average field fortification recoveries were greater than 100% for Site No. 

5 and No. 6. Field fortification data from Site No. 2 indicated that the spiking solutions had 

degraded causing erratic data for field fortification recoveries, therefore, these recoveries were 

not used to correct the raw residue data, and Site No. 5 and Site No. 6 field fortification 

recoveries were applied to Site No. 2 DFRs. 
Page 183 of 227

Actual average DFR values are provided in Table I.3. The chlorpyrifos residues on leaves 

demonstrated a biphasic pattern of dissipation. Residue levels dropped dramatically in the first 

two days, and then dissipation of chlorpyrifos was gradual. 

Since all the sampling sites are located in California, the average DFR values for each day at 

each site were used to plot a regression for all the sites combined. Table I.4 provides the 

predicted values calculated from the regression of the combined sites. 

Table I.3. Summary of Actual Average DFR Values on Citrus After One Broadcast 

Foliar Application of Chlorpyrifos

Sampling 

Interval 

(Days)

Actual Average DFR (μg/cm2)

Lorsban 4EC (Emulsifiable Concentrate)

CA - Site No. 2 CA - Site No. 5 CA - Site No. 6

After 1st (Last) application

0 1.46 1.82 1.48

1 0.212 0.547 0.367

2 -- 0.157 0.082

4 0.096 -- --

5 0.079 -- --

7 0.074 0.008 0.013

14 0.023 0.004 0.005

21 <LOD -- --

35 <LOD -- 0.004

40 -- <LOD --

43 <LOD -- --

Notes: 

1.LOQ not provided. LOD ranged from 0.0032 to 0.016 μg/cm2.

2.Residues did not require correction for field fortification recovery.

3.The nominal application rate was 6 lb ai/A.

Table I.4. Summary of Predicted DFR Values on Citrus After One Broadcast Foliar 

Application of Chlorpyrifos

Time

(Days)

Predicted DFR (μg/cm2)

Lorsban 4EC (Emulsifiable Concentrate)

CA - Site No. 2 CA - Site No. 5 CA - Site No. 6 Combined CA Sites 2, 5, & 

6

0

0.171*

(1.46)

0.189*

(1.82)

0.227*

(1.48)

0.228*

(1.59)

1

0.150*

(0.212)

0.164*

(0.547)

0.195*

(0.367)

0.197*

(0.375)

2 0.131 0.142 0.168 0.170

3 0.115 0.123 0.144 0.147
Page 184 of 227

Table I.4. Summary of Predicted DFR Values on Citrus After One Broadcast Foliar 

Application of Chlorpyrifos

Time

(Days)

Predicted DFR (μg/cm2)

Lorsban 4EC (Emulsifiable Concentrate)

CA - Site No. 2 CA - Site No. 5 CA - Site No. 6 Combined CA Sites 2, 5, & 

6

4 0.101 0.106 0.124 0.127

5 0.088 0.0920 0.106 0.110

6 0.078 0.0797 0.0913 0.095

7 0.068 0.0690 0.07842 0.082

8 0.060 0.0598 0.0674 0.071

9 0.052 0.0518 0.0579 0.061

10 0.046 0.0449 0.0497 0.053

11 0.0402 0.0389 0.0427 0.0458

12 0.0352 0.0337 0.0367 0.0396

13 0.0309 0.0292 0.0315 0.0342

14 0.0271 0.0253 0.0271 0.0296

15 0.0237 0.0219 0.0233 0.0256

16 0.0208 0.0190 0.0200 0.0221

17 0.0182 0.0164 0.0172 0.0191

18 0.0160 0.0142 0.0148 0.0165

19 0.0140 0.0123 0.0127 0.0143

20 0.0123 0.0107 0.0109 0.0123

21 0.0108 0.0092 0.00936 0.0107

22 0.0095 0.0080 0.0080 0.0092

23 0.0083 0.0069 0.0069 0.0080

24 0.0073 0.0060 0.0059 0.0069

25 0.0064 0.0052 0.0051 0.0060

26 0.0056 0.0045 0.0044 0.0051

27 0.0049 0.0039 0.0038 0.0045

28 0.0043 0.0034 0.0032 0.0038

29 0.0038 0.0029 0.0028 0.0033

30 0.0033 0.0025 0.0024 0.0029

r

2 0.58 0.55 0.61 0.67

slope -0.13 -0.14 -0.15 -0.15

half-life 

(days) 5.27 4.83 4.56 4.76

Notes:
Page 185 of 227

1. For the risk analysis, the predicted value shown was replaced with the actual value in parentheses (from 

Table 1) when the actual DFR data from either after the first or second application was higher than the 

predicted DFR data.

2. The nominal application rate was 6 lb ai/A.

MRID 44748101 (Apples, Almonds, Pecans)

This DFR study (MRID 44748101) examined the residues of chlorpyrifos on apple, almond, and 

pecan trees. Three test sites were established for each crop in the major crop production areas (1 

apple trial each in CA, NY and WA; 3 almond trials in CA; 1 pecan trial each in GA, LA and 

TX). One treatment plot for the application of Lorsban 50W (wettable powder) was established 

at all trial sites. For pecans, an additional treatment plot was established for application of 

Lorsban 4E (emulsifiable concentrate). The test products were applied as two airblast spray 

applications, each at a nominal rate of 1.5 lb ai/A for apple trees and at 2.0 lb ai/A for almond 

and pecan trees. The re-treatment intervals were 7 days for apple trees, 15 days for almond trees, 

and 7 days for pecan trees. Applications were made in a spray volume rate of approximately 89-

109 gallons per acre. At each sampling interval a sample was taken from the control plot and 

triplicate samples were taken from the treated plot using a Birkenstrand leaf punch. Leaf 

samples were collected at nominal sampling intervals of prior to each application, at days 0, 2, 

and 5 days after the first application, and at 0, 1, 2, 4, 7, 14, 21, 28 and 35 days after the second 

application. Samples were analyzed for residues of chlorpyrifos. Concurrent recoveries fell 

within the acceptable range of 70 - 120 percent. The LOD and LOQ were reported as 0.001 

μg/cm2and 0.003 μg/cm2respectively. The overall average recoveries of field fortified samples 

for apple, almond, and pecan leaves ranged from 73 to 77 percent for the 5 μg/sample level and 

from 79 to 87 percent for the 50 μg/sample level. DFR values were calculated by adjusting the 

residues for site-specific field fortification recoveries when the recoveries were less than 90%. 

The adjustment was made using the average recovery for the fortification level closest to the 

residue level. 

Actual average DFR values are provided in Table I.5. Two of the almond sites (CA2 and CA3) 

were located in California and have similar dissipation rates. Therefore, average daily DFR 

values were combined for those two sites and the regression was performed on the combined 

DFR values. The remaining almond site (CA4) was also located in California, but had much 

slower rate of dissipation from the other two almond sites. Since this may be reflect of different 

climatological conditions (i.e., more arid climate), the DFR values from this site were not 

combined with the other two almond sites. The predicted values calculated from the regressions 

are provided in Table I.6.

Table I.5. Summary of Actual Average DFR Values on Apples, Almonds, and Pecans 

After Two Broadcast Foliar Applications of Chlorpyrifos

Sampling 

Interval

(Days)

Actual Average DFR (μg/cm2)

Lorsban WP

(Wettable Powder)

Lorsban 4EC

(Emulsifiable Concentrate)

Apples Almonds Pecans Pecans

CA NY WA CA2 CA3 CA4 GA LA TX GA LA TX

After 1st application
Page 186 of 227

Table I.5. Summary of Actual Average DFR Values on Apples, Almonds, and Pecans 

After Two Broadcast Foliar Applications of Chlorpyrifos

Sampling 

Interval

(Days)

Actual Average DFR (μg/cm2)

Lorsban WP

(Wettable Powder)

Lorsban 4EC

(Emulsifiable Concentrate)

Apples Almonds Pecans Pecans

CA NY WA CA2 CA3 CA4 GA LA TX GA LA TX

0 1.34 1.90 2.70 3.13 3.95 3.63 0.150 0.587 0.100 0.0604 0.3985 0.263

2 0.0937 0.124 0.263 0.645 1.12 0.132 0.010 0.024 0.052 0.0140 0.0226 0.0454

5 0.0123 0.016 0.093 0.082 0.105 0.053 0.0038 0.009 0.026 0.0049 0.0098 0.0239

After 2nd (last) application

0 0.488 1.97 2.56 1.36 3.09 2.20 1.01 0.148 0.097 0.1929 0.1239 0.137

1 0.074 0.806 0.642 0.685 1.48 0.16 0.095 0.041 0.055 0.0170 0.0335 0.0661

2 0.029 0.370 0.221 0.234 0.538 0.243 0.014 0.016 0.045 0.0139 0.0165 0.0396

4 0.0151 0.038 0.0166 0.022 0.119 0.092 <LOQ 0.015 0.025 0.0027 0.0157 0.0207

7 0.0104 0.004 0.0040 0.025 0.008 0.063 <LOQ 0.0081 0.0069 0.0008 0.0070 0.0088

14 <LOQ <LOQ <LOQ <LOQ 0.0057 0.049 <LOQ <LOQ <LOQ 0.0012 0.0030 0.0015

21 <LOQ <LOQ <LOQ <LOQ <LOQ 0.040 <LOQ <LOQ <LOQ 0.0005 0.0005 0.0008

28 <LOQ <LOQ <LOQ <LOQ <LOQ 0.022 <LOQ <LOQ <LOQ 0.0005 0.0005 0.0008

35 <LOQ <LOQ <LOQ <LOQ <LOQ 0.017 0.0051 <LOQ <LOQ 0.0012 0.0005 0.0005

Notes:

1. LOQ = 0.003 μg/cm2

2. Residues were corrected for field fortification recoveries <90%.

3. The nominal application rate was 1.5 lb ai/A for apple trees (total of 3 lb ai/A) and 2.0 lb ai/A for almond and pecan 

trees (total of 4 lb ai/A).

Table I.6. Summary of Predicted DFR Values on Apples, Almonds, and Pecans After Two 

Broadcast Foliar Applications of Chlorpyrifos

Time 

(Days)

Predicted DFR (μg/cm2)

Lorsban WP

(Wettable Powder)

Lorsban 4EC

(Emulsifiable Concentrate)

Apple Almonds Pecans Pecans

CA NY WA CA2 & CA3 CA4 GA LA TX GA LA TX

0

0.115

(0.488)

1.10

(1.97)

0.614

(2.70)

0.624

(2.22)

0.246

(3.63)

0.621

(1.01)

0.055

(0.587)

0.093

(0.097)

0.0832

(0.1929)

0.0486

(0.3985)

0.0911

(0.263)

1 0.084 0.595

(0.806)

0.367

(0.642)

0.448

(1.08) 0.225 0.114 0.043 0.064 0.0319 0.0383 0.0669

2 0.061 0.322

(0.370)

0.219

(0.221)

0.321

(0.386) 0.206 0.021 0.033 0.044 0.0122 0.0302 0.0492

3 0.045 0.174 0.131 0.230 0.189 0.00380 0.026 0.030 0.00468 0.02387 0.03612

4 0.033 0.094 0.078 0.165 0.173 0.00070 0.020 0.021 0.00179 0.01884 0.02653

5 0.024 0.051 0.047 0.119 0.159 1.27E-04 0.016 0.015 0.00069 0.01487 0.01949

6 0.018 0.028 0.028 0.085 0.146 2.33E-05 0.012 0.010 0.000263 0.0117 0.0143

7 0.013 0.015 0.017 0.061 0.133 4.27E-06 0.010 0.007 0.000101 0.00926 0.01051

8 0.00944 0.00805 0.0100 0.044 0.1223 7.8E-07 0.00742 0.005 3.87E-05 0.007309 0.00772
Page 187 of 227

Table I.6. Summary of Predicted DFR Values on Apples, Almonds, and Pecans After Two 

Broadcast Foliar Applications of Chlorpyrifos

Time 

(Days)

Predicted DFR (μg/cm2)

Lorsban WP

(Wettable Powder)

Lorsban 4EC

(Emulsifiable Concentrate)

Apple Almonds Pecans Pecans

CA NY WA CA2 & CA3 CA4 GA LA TX GA LA TX

9 0.00691 0.00435 0.0059 0.0314 0.1121 1.4E-07 0.00578 0.003 1.48E-05 0.005768 0.00567

10 0.00506 0.00235 0.0036 0.0225 0.1027 2.6E-08 0.00451 0.002 5.68E-06 0.004553 0.00417

11 0.00370 0.00127 0.0021 0.0161 0.0941 4.8E-09 0.00351 0.002 2.18E-06 0.003593 0.00306

12 0.00271 0.00069 0.0013 0.0116 0.0862 8.8E-10 0.00274 0.001 8.34E-07 0.002836 0.00225

13 0.00198 0.00037 7.6E-04 0.00831 0.0790 1.6E-10 0.00213 7.4E-04 3.19E-07 0.002238 0.00165

14 0.00145 0.00020 4.5E-04 0.00596 0.0724 2.9E-11 0.00166 5.1E-04 1.22E-07 0.001766 0.00121

15 0.00106 0.00011 2.7E-04 0.00428 0.0664 5.4E-12 0.00130 3.5E-04 4.69E-08 0.001394 0.000891

16 7.8E-04 5.9E-05 1.6E-04 0.00307 0.0608 9.8E-13 0.00101 2.4E-04 1.8E-08 0.0011 0.000654

17 5.7E-04 3.2E-05 9.6E-05 0.00220 0.0558 1.8E-13 7.9E-04 1.7E-04 6.89E-09 0.000868 0.000481

18 4.2E-04 1.7E-05 5.8E-05 0.00158 0.0511 3.3E-14 6.1E-04 1.2E-04 2.64E-09 0.000685 0.000353

19 3.0E-04 9.3E-06 3.4E-05 0.00113 0.0468 6.0E-15 4.8E-04 8.0E-05 1.01E-09 0.000541 0.000259

20 2.2E-04 5.0E-06 2.1E-05 8.1E-04 0.0429 1.1E-15 3.7E-04 5.5E-05 3.87E-10 0.000427 0.000190

21 1.6E-04 2.7E-06 1.2E-05 5.8E-04 0.0393 2.0E-16 2.9E-04 3.8E-05 1.48E-10 0.000337 0.000140

22 1.2E-04 1.5E-06 7.3E-06 4.2E-04 0.0360 3.7E-17 2.3E-04 2.6E-05 5.69E-11 0.000266 0.000103

23 8.7E-05 8.0E-07 4.4E-06 3.0E-04 0.0330 6.7E-18 1.8E-04 1.8E-05 2.18E-11 0.00021 7.55E-05

24 6.4E-05 4.3E-07 2.6E-06 2.2E-04 0.0303 1.2E-18 1.4E-04 1.3E-05 8.35E-12 0.000166 5.55E-05

25 4.7E-05 2.3E-07 1.6E-06 1.5E-04 0.0277 2.3E-19 1.1E-04 8.6E-06 3.2E-12 0.000131 4.07E-05

26 3.4E-05 1.3E-07 9.3E-07 1.1E-04 0.0254 4.1E-20 8.3E-05 6.0E-06 1.23E-12 0.000103 2.99E-05

27 2.5E-05 6.8E-08 5.6E-07 7.9E-05 0.0233 7.6E-21 6.5E-05 4.1E-06 4.7E-13 8.14E-05 2.2E-05

28 1.8E-05 3.7E-08 3.3E-07 5.7E-05 0.0213 1.4E-21 5.1E-05 2.8E-06 1.8E-13 6.43E-05 1.61E-05

29 1.3E-05 2.0E-08 2.0E-07 4.1E-05 0.0196 2.5E-22 3.9E-05 2.0E-06 6.9E-14 5.07E-05 1.19E-05

30 9.8E-06 1.1E-08 1.2E-07 2.9E-05 0.0179 4.6E-23 3.1E-05 1.3E-06 2.64E-14 4.0E-05 8.71E-06

31 7.2E-06 5.8E-09 7.1E-08 2.1E-05 0.0164 8.5E-24 2.4E-05 9.3E-07 1.01E-14 3.16E-05 6.4E-06

32 5.3E-06 3.1E-09 4.2E-08 1.5E-05 0.0151 1.6E-24 1.9E-05 6.4E-07 3.88E-15 2.49E-05 4.7E-06

33 3.8E-06 1.7E-09 2.5E-08 1.1E-05 0.0138 2.8E-25 1.5E-05 4.4E-07 1.49E-15 1.97E-05 3.45E-06

34 2.8E-06 9.2E-10 1.5E-08 7.8E-06 0.0126 5.2E-26 1.1E-05 3.1E-07 5.7E-16 1.55E-05 2.54E-06

35 2.1E-06 5.0E-10 9.0E-09 5.6E-06 0.0116 9.5E-27 8.8E-06 2.1E-07 2.18E-16 1.23E-05 1.86E-06

r

2 0.77 0.93 0.80 0.82 0.6047 0.99 0.80 0.97 0.65 0.80 0.95

slope -0.31 -0.61 -0.52 -0.33 -0.0873 -0.37 -0.25 -1.70 -0.96 -0.24 -0.61

half-life 

(days) 2.22 1.13 1.35 2.09 7.94 1.87 2.78 0.41 0.72 2.93 2.25

Notes:

1. For the risk analysis, the predicted value shown was replaced with the actual value in parentheses (from 

Table 1) when the actual DFR data from either after the first or second application was higher than the 

predicted DFR data.
Page 188 of 227

2. The nominal application rate was 1.5 lb ai/A for apple trees (total of 3 lb ai/A) and 2.0 lb ai/A for almond 

and pecan trees (total of 4 lb ai/A).

MRID 447481-02 (Cotton, Sugarbeet, Sweet Corn)

This DFR study (MRID 44748102) examined the residues of chlorpyrifos on cotton, sugar beet, 

and sweet corn after application of either Lorsban 4E (emulsifiable concentrate), Lock-on 

(emulsifiable concentrate), or Lorsban 15G (granular). Lorsban 4E trials were conducted on all 

crops. Lock-on trials were conducted on cotton only and Lorsban 15G trials were conducted on 

sweet corn only. Three test sites were established for each crop for each formulation tested. 

Cotton trials were conducted in California, Texas, Mississippi (Lorsban 4E only) and Arizona

(Lock-on only). Sugar beet trials were conducted in California, Oregon, and Minnesota. Sweet 

corn trials were conducted in Oregon, Minnesota, and Illinois. Each test site received two 

broadcast foliar applications of a test product spaced five days apart. The application rate used 

for Lorsban 4E on all crops was 1 lb ai/A. Lock-on was applied to cotton at 0.5 lb ai/A and 

Lorsban 15G was applied to sweet corn at 1 lb ai/A. At each sampling interval a sample was 

taken from the control plot and triplicate samples were taken from the treated plot using a 

Birkenstrand leaf punch. Leaf samples were collected at sampling intervals of prior to the first 

application, immediately following the application (within 1-2 hours or as soon as the spray had 

completely dried or dust had settled on the foliage), and at 1, 2, and 4 days after the first 

application. Leaf punch samples were also collected immediately following the second 

application and at 1, 2, 4, 7, 14, 21, and 28 days after the second (final) application. Samples 

were analyzed for residues of chlorpyrifos. Concurrent recoveries fell within the acceptable 

range of 70 - 120 percent. The LOD and LOQ were reported as 0.001 μg/cm2and 0.003 μg/cm2

respectively. Field fortifications were collected on three sampling events at each test. Average 

field fortification recoveries (not corrected for laboratory recovery), ranged from 82% to 117%. 

DFR values were calculated by adjusting the residues for site-specific field fortification 

recoveries when the recoveries were less than 90%. The adjustment was made using the average 

recovery for the fortification level closest to the residue level. 

Actual average DFR values are provided in Table I.7 and predicted values calculated from the 

regressions are provided in Table I.8. A regression was not conducted for the granular 

application on sweet corn at the Minnesota site because all DFR values were <LOQ. 

Table I.7. Summary of Actual Average DFR Values on Cotton, Sugarbeet, and Sweet Corn After

Two Broadcast Foliar Applications of Chlorpyrifos

Sampling 

Interval

(Days)

Actual Average DFR (μg/cm2)

Cotton Sugar beet Sweet Corn

Lorsban 4EC

(Emulsifiable 

Concentrate)

Lock-On

(Emulsifiable 

Concentrate)

Lorsban 4E

(Emulsifiable 

Concentrate)

Lorsban 4E 

(Emulsifiable 

Concentrate)

Lorsban 15G

(Granular)

CA TX MS CA AZ TX CA OR MN OR MN IL OR MN IL

After 1st application
Page 189 of 227

Table I.7. Summary of Actual Average DFR Values on Cotton, Sugarbeet, and Sweet Corn After

Two Broadcast Foliar Applications of Chlorpyrifos

Sampling 

Interval

(Days)

Actual Average DFR (μg/cm2)

Cotton Sugar beet Sweet Corn

Lorsban 4EC

(Emulsifiable 

Concentrate)

Lock-On

(Emulsifiable 

Concentrate)

Lorsban 4E

(Emulsifiable 

Concentrate)

Lorsban 4E 

(Emulsifiable 

Concentrate)

Lorsban 15G

(Granular)

CA TX MS CA AZ TX CA OR MN OR MN IL OR MN IL

0 1.11 0.734 2.93 0.483 0.372 0.831 0.743 0.766 2.32 1.73 2.39 0.330 <LOQ <LOQ 0.0258

1 0.0530 0.0239 0.0147 0.0316 0.0255 0.0179 0.0273 0.0766 0.0666 0.0444 0.0438 0.0121 <LOQ <LOQ <LOQ

2 0.0165 0.0167 0.0087 0.00770 0.010 0.0076 0.0172 0.0166 0.0274 0.0134 0.0148 0.0070 <LOQ <LOQ 0.0043

4 0.0067 0.0090 0.0033 <LOQ 0.0056 <LOQ 0.0090 0.0038 0.0066 <LOQ 0.0040 <LOQ 0.0111 <LOQ 0.0094

After 2nd (last) application

0 0.602 2.38 0.936 0.424 0.191 1.21 0.870 0.464 0.667 0.527 0.568 2.98 0.213 <LOQ 0.0853

1 0.347 0.0205 0.0046 0.0370 0.0212 0.0222 0.063 0.002 0.044 0.016 0.041 0.019 <LOQ <LOQ <LOQ

2 0.136 0.0061 <LOQ 0.0116 0.0097 0.0048 0.034 0.008 0.030 0.0061 0.0281 0.0083 0.0119 <LOQ <LOQ

4 0.0211 0.0054 <LOQ 0.0061 0.0045 <LOQ 0.016 0.005 0.008 <LOQ 0.0032 0.0041 <LOQ <LOQ 0.0036

7 0.0068 <LOQ <LOQ <LOQ 0.0057 <LOQ 0.006 <LOQ 0.004 <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ

14 <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ

21 <LOQ <LOQ 0.200 <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ

28 <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ

Notes:

1. LOQ = 0.003 μg/cm2

2. Residues were corrected for field fortification recoveries <90%.

3. Application rates were 1.0 lb ai/A for Lorsban 4E and Lock-On (total of 2 lb ai/A) and 0.5 lb ia/A for 

Lorsban 15G (total of 1 lb ai/A).

Table I.8. Summary of Predicted DFR Values on Cotton, Sugarbeet, and Sweet Corn After Two 

Broadcast Foliar Applications of Chlorpyrifos

Time

(Days)

Predicted DFR (μg/cm2)

Cotton Sugar beet Sweet Corn

Lorsban 4E (Emulsifiable 

Concentrate)

Lock-On (Emulsifiable 

Concentrate)

Lorsban 4E (Emulsifiable 

Concentrate)

Lorsban 4E (Emulsifiable 

Concentrate)

Lorsban 15G

(Granular)

CA TX MS CA AZ TX CA OR MN IL MN OR IL OR

0

0.227

(1.11)

0.207

(2.38)

0.456

(2.93)

0.0438

(0.483)

0.287

(0.372)

0.0255

(1.21)

0.137

(0.87)

0.0320 

(0.766)

0.113

(2.32)

0.232

(2.98)

0.170

(2.39)

0.165

(1.73)

0.0112

(0.0853)

0.0332

(0.213)

1

0.152

(0.347) 0.0832 0.0185 0.0327(0.037) 0.0668 0.0215(0.0222) 0.0961 0.0173(0.077) 0.0736 0.0898 0.0781 0.044 0.00679 0.0120

2 0.1018 0.0335 0.00075 0.02435 0.0155 0.01814 0.0675 0.0094 0.0480 0.0348 0.0359 0.0117 0.00413 0.00437

(0.0119)

3 0.0681 0.0135 3.03E-05 0.01815 0.0036 0.01530 0.0475 0.0051 0.0313 0.0135 0.0165 0.0031 0.00251 0.0016

4 0.0456 0.00542 1.23E-06 0.01353 0.00084 0.01291 0.0334 0.0028 0.0205 0.00522 0.00757 0.00082 0.00152 0.0006

5 0.0305 0.00218 4.96E-08 0.01009 0.00020 0.01089 0.0235 0.0015 0.0134 0.00202 0.00348 0.00022 0.00093 0.0002

6 0.0204 0.00088 2.01E-09 0.00752 4.55E-05 0.00919 0.0165 0.00082 0.0087 0.00078 0.00160 5.8E-05 0.00056 7.56E-05

7 0.0137 0.00035 8.13E-11 0.00560 1.06E-05 0.00775 0.0116 0.00044 0.0057 0.00030 0.00073 1.5E-05 0.00034 2.74E-05

8 0.00916 0.00014 3.29E-12 0.00418 2.47E-06 0.00654 0.00815 0.00024 0.00371 0.00012 3.4E-04 4.1E-06 0.00021 9.96E-06
Page 190 of 227

Table I.8. Summary of Predicted DFR Values on Cotton, Sugarbeet, and Sweet Corn After Two 

Broadcast Foliar Applications of Chlorpyrifos

Time

(Days)

Predicted DFR (μg/cm2)

Cotton Sugar beet Sweet Corn

Lorsban 4E (Emulsifiable 

Concentrate)

Lock-On (Emulsifiable 

Concentrate)

Lorsban 4E (Emulsifiable 

Concentrate)

Lorsban 4E (Emulsifiable 

Concentrate)

Lorsban 15G

(Granular)

CA TX MS CA AZ TX CA OR MN IL MN OR IL OR

9 0.00613 5.73E-05 1.33E-13 0.00311 5.74E-07 0.00551 0.00573 0.00013 0.00242 4.54E-05 1.5E-04 1.1E-06 0.00013 3.61E-06

10 0.00410 2.31E-05 5.40E-15 0.00232 1.34E-07 0.00465 0.00403 7.07E-05 0.00158 1.76E-05 7.1E-05 2.9E-07 7.68E-05 1.31E-06

11 0.00275 9.28E-06 2.19E-16 0.00173 3.11E-08 0.00392 0.00283 3.84E-05 0.00103 6.81E-06 3.3E-05 7.7E-08 4.7E-05 4.75E-07

12 0.00184 3.73E-06 8.85E-18 0.00129 7.23E-09 0.00331 0.00199 2.08E-05 0.00067 2.64E-06 1.5E-05 2.0E-08 2.8E-05 1.72E-07

13 0.00123 1.50E-06 3.59E-19 0.00096 1.68E-09 0.00279 0.00140 1.13E-05 0.00044 1.02E-06 6.9E-06 5.4E-09 1.7E-05 6.26E-08

14 0.00082 6.05E-07 1.45E-20 0.00072 3.92E-10 0.00235 0.00098 6.13E-06 0.00029 3.95E-07 3.2E-06 1.4E-09 1.0E-05 2.27E-08

15 0.00055 2.43E-07 5.88E-22 0.00053 9.11E-11 0.00199 0.00069 3.32E-06 0.00019 1.53E-07 1.5E-06 3.8E-10 6.4E-06 8.24E-09

16 0.00037 9.80E-08 2.38E-23 0.00040 2.12E-11 0.00168 0.00049 1.80E-06 0.00012 5.93E-08 6.7E-07 1.0E-10 3.9E-06 2.99E-09

17 0.00025 3.94E-08 9.64E-25 0.00030 4.93E-12 0.00141 0.00034 9.79E-07 7.99E05 2.30E-08 3.1E-07 2.7E-11 2.4E-06 1.08E-09

18 0.00017 1.59E-08 3.90E-26 0.00022 1.15E-12 0.00119 0.00024 5.31E-07 5.22E05 8.89E-09 1.4E-07 7.2E-12 1.4E-06 3.93E-10

19 0.00011 6.39E-09 1.58E-27 0.00016 2.67E-13 0.00101 0.00017 2.88E-07 3.41E05 3.44E-09 6.5E-08 1.9E-12 8.7E-07 1.43E-10

20 7.41E05 2.57E-09 6.40E-29 0.00012 6.22E-14 0.00085 0.00012 1.56E-07 2.22E05 1.33E-09 3.0E-08 5.1E-13 5.3E-07 5.18E-11

21 4.96E05 1.04E-09 2.59E-30 9.17E-05 1.45E-14 0.00072 4.89E05 8.49E-08 1.45E05 5.16E-10 1.4E-08 1.4E-13 3.2E-07 1.88E-11

22 3.32E05 4.17E-10 1.05E-31 6.83E-05 3.37E-15 0.00060 3.45E05 4.60E-08 9.47E06 2.00E-10 6.3E-09 3.6E-14 1.9E-07 6.82E-12

23 2.22E05 1.68E-10 4.25E-33 5.09E-05 7.83E-16 0.00051 2.43E05 2.50E-08 6.18E06 7.74E-11 2.9E-09 9.5E-15 1.2E-07 2.47E-12

24 1.49E05 6.75E-11 1.72E-34 3.80E-05 1.82E-16 0.00043 1.71E05 1.36E-08 4.03E06 3.00E-11 1.3E-09 2.5E-15 7.2E-08 8.97E-13

25 9.96E06 2.72E-11 6.97E-36 2.83E-05 4.24E-17 0.00036 1.21E05 7.35E-09 2.63E06 1.16E-11 6.1E-10 6.7E-16 4.4E-08 3.25E-13

26 6.67E06 1.09E-11 2.82E-37 2.11E-05 9.87E-18 0.00031 8.50E06 3.99E-09 1.72E06 4.50E-12 2.8E-10 1.8E-16 2.7E-08 1.18E-13

27 4.46E06 4.40E-12 1.14E-38 1.57E-05 2.30E-18 0.00026 5.99E06 2.17E-09 1.12E06 1.74E-12 1.3E-10 4.8E-17 1.6E-08 4.28E-14

28 2.99E06 1.77E-12 4.63E-40 1.17E-05 5.34E-19 0.00022 4.22E06 1.17E-09 7.33E07 6.74E-13 5.9E-11 1.3E-17 9.8E-09 1.55E-14

29 2.00E06 7.13E-13 1.87E-41 8.74E-06 1.24E-19 0.00018 2.97E06 6.37E-10 4.78E07 2.61E-13 2.7E-11 3.4E-18 6.0E-09 5.64E-15

30 1.34E06 2.87E-13 7.58E-43 6.52E-06 2.89E-20 0.00015 2.09E06 3.46E-10 3.12E07 1.01E-13 1.2E-11 8.9E-19 3.6E-09 2.05E-15

r

2 0.82 0.69 0.87 0.65 0.767 0.539 0.74 0.36 0.83 0.69 0.83 0.82 0.440 0.645

slope -0.40 -0.91 -3.21 -0.29 -1.458 -0.170 -0.35 -0.61 -0.43 -0.95 -0.78 -1.33 -0.498 -1.014

half-life 

(days) 1.73 0.76 0.22 2.36 0.475 4.073 1.97 1.13 1.62 0.73 0.89 0.52 1.392 0.684

Notes:

1. For the risk analysis, the predicted value shown was replaced with the actual value in parentheses (from 

Table 1) when the actual DFR data from either after the first or second application was higher than the 

predicted DFR data.

2. Application rates were 1.0 lb ai/A for Lorsban 4E and Lock-On (total of 2 lb ai/A) and 0.5 lb ia/A for 

Lorsban 15G (total of 1 lb ai/A).

MRID 44829601 (Turf) 
Page 191 of 227

This DFR study (MRID 44829601) examined the residues of chlorpyrifos on turf after 

application of Dursban Pro (an emulsifiable concentrate), Dursban 50W (wettable powder), 

Dursban 2.5G (granular) and Dursban 1F (flowable granular). Three test sites were established 

in California, Indiana, and Mississippi, with one test plot for each test substance. Single 

applications of the test products were made to the treatment plots using tractor mounted boom 

sprayers for the liquid applications and either a tractor mounted air spreader or tractor mounted 

spreader for the granular applications. The liquid applications were made at a nominal 

application ate of 4 lb ai/A and the granular applications were made at a nominal application rate 

of 2 lb ai/A. Actual application rates, determined by analyzing filter paper anchored to the test 

plots for liquid applications and placing plastic pans in the test plots for granular applications,

ranged from 95% to 100% for the Dursban Pro application, 97% to 102% for the Dursban 50W 

application, 91% to 95% for the Dursban 2.5G application and 77% to 86% for the Dursban 1F 

application. Duplicate samples were collected using the California roller technique at the 

following intervals: one day prior to the application, just after the application (-2.5 hours after 

application), and days 1, 2, 4, and 7 after application. Samples were analyzed for residues of 

chlorpyrifos. The overall average concurrent recovery was 98%±3%. The LOD and LOQ were 

reported as 0.001 μg/cm2and 0.003 μg/cm2respectively. The field study samples did not require 

correction for field fortification recovery. Average field fortification recoveries (corrected for 

concurrent recovery), at each of three fortification levels were greater than 90% at all sites. 

Actual average DFR values (corrected for concurrent recovery) are provided in Table I.9 and 

predicted values calculated from the regressions are provided in Table I.10. Regression analysis 

could not be conducted for the trials with Dursban 2.5G because all residues were <LOQ and 

with Dursban 1F trials in Indiana and Mississippi because there were not enough data points 

above the LOQ.

Table I.9. Summary of Actual Average DFR Values on Turf After One Broadcast Foliar 

Application of Chlorpyrifos

Sampling 

Interval 

(Days)

Actual Average DFR (μg/cm2)

Dursban Pro

(Emulsifiable Concentrate)

Dursban 50W

(Wettable Powder)

Dursban 2.5G

(Granular)

Dursban 1F

(Granular)

CA IN MS CA IN MS CA IN MS CA IN MS

After 1st (Only) Application

0 0.124 0.09 0.146 0.234 0.657 0.351 <LOQ <LOQ <LOQ 0.052 <LOQ <LOQ

1 0.039 0.011 0.009 0.027 0.155 0.032 <LOQ <LOQ <LOQ 0.02 <LOQ <LOQ

2 0.01 0.005 <LOQ 0.012 0.039 0.006 <LOQ <LOQ <LOQ 0.011 0.003 0.01

4 0.004 <LOQ <LOQ <LOQ 0.005 <LOQ <LOQ <LOQ <LOQ 0.004 0.003 <LOQ

7 <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ <LOQ

Notes:

1. LOQ = 0.003 μg/cm2

2. Residues were corrected for concurrent recoveries.

3. Application rates were a nominal 4 lb ai/A for liquid applications (Dursban Pro and Dursban 50W ) and 2.0 

lb ai/A for granular applications (Dursban 2.5G and Dursban 1F).
Page 192 of 227

Table I.10. Summary of Predicted DFR Values on Turf After One Broadcast 

Foliar Applications of Chlorpyrifos

Time 

(Days)

Predicted DFR (μg/cm2)

Dursban Pro

(Emulsifiable Concentrate) 

Dursban 50W

(Wettable Powder)

Dursban 1F

(Granular)

CA IN MS CA IN MS CA

0

0.0934

(0.124)

0.071

(0.0895) 0.145 0.170(0.234)

0.566

(0.657)

0.312

(0.351)

0.0432

(0.052)

1 0.0397 0.0167 0.00894 0.0385 0.164 0.0386 0.0212

2 0.0169 0.00395 5.50E-04 0.00871 0.0474 0.00478 0.0104

3 0.00718 9.33E-04 3.38E-05 0.0020 0.0137 5.92E-04 0.00511

4 0.00306 2.21E-04 2.08E-06 4.46E-04 0.0040 7.32E-05 0.00251

5 0.00130 5.22E-05 1.28E-07 1.01E-04 0.0011 9.06E-06 0.00123

6 5.52E-04 1.23E-05 7.86E-09 2.29E-05 3.32E-04 1.12E-06 6.04E-04

7 2.35E-04 2.92E-06 4.83E-10 5.17E-06 9.60E-05 1.39E-07 2.97E-04

8 9.99E-05 6.90E-07 2.97E-11 1.17E-06 2.78E-05 1.72E-08 1.46E-04

9 4.25E-05 1.63E-07 1.83E-12 2.65E-07 8.04E-06 2.13E-09 7.15E-05

10 1.81E-05 3.86E-08 1.12E-13 6.00E-08 2.33E-06 2.63E-10 3.51E-05

11 7.68E-06 9.12E-09 6.91E-15 1.36E-08 6.73E-07 3.26E-11 1.72E-05

12 3.27E-06 2.16E-09 4.25E-16 3.07E-09 1.95E-07 4.03E-12 8.45E-06

13 1.39E-06 5.10E-10 2.61E-17 6.95E-10 5.63E-08 4.99E-13 4.15E-06

14 5.91E-07 1.21E-10 1.61E-18 1.57E-10 1.63E-08 6.18E-14 2.04E-06

15 2.51E-07 2.85E-11 9.88E-20 3.56E-11 4.72E-09 7.65E-15 1.00E-06

16 1.07E-07 6.74E-12 6.08E-21 8.06E-12 1.36E-09 9.46E-16 4.91E-07

17 4.54E-08 1.59E-12 3.74E-22 1.82E-12 3.95E-10 1.17E-16 2.41E-07

18 1.93E-08 3.77E-13 2.3E-23 4.13E-13 1.14E-10 1.45E-17 1.18E-07

19 8.22E-09 8.91E-14 1.41E-24 9.35E-14 3.30E-11 1.79E-18 5.80E-08

20 3.49E-09 2.11E-14 8.69E-26 2.12E-14 9.56E-12 2.22E-19 2.85E-08

21 1.49E-09 4.98E-15 5.34E-27 4.79E-15 2.77E-12 2.75E-20 1.40E-08

22 6.32E-10 1.18E-15 3.28E-28 1.08E-15 8.00E-13 3.40E-21 6.86E-09

23 2.69E-10 2.78E-16 2.02E-29 2.45E-16 2.32E-13 4.21E-22 3.37E-09

24 1.14E-10 6.58E-17 1.24E-30 5.55E-17 6.70E-14 5.21E-23 1.65E-09

25 4.86E-11 1.56E-17 7.64E-32 1.26E-17 1.94E-14 6.45E-24 8.12E-10

26 2.07E-11 3.68E-18 4.7E-33 2.84E-18 5.61E-15 7.98E-25 3.98E-10

27 8.79E-12 8.70E-19 2.89E-34 6.44E-19 1.62E-15 9.88E-26 1.96E-10

28 3.74E-12 2.06E-19 1.78E-35 1.46E-19 4.70E-16 1.22E-26 9.60E-11

29 1.59E-12 4.87E-20 1.09E-36 3.30E-20 1.36E-16 1.51E-27 4.71E-11

30 6.76E-13 1.15E-20 6.71E-38 7.46E-21 3.93E-17 1.87E-28 2.31E-11

r2 0.94 0.92 1.00 0.851 0.99 0.98 0.84

slope -0.86 -1.44 -2.79 -1.486 -1.24 -2.09 -0.712

half-life 

(days) 0.81 0.48 0.25 0.467 0.56 0.33 0.97

Notes:
Page 193 of 227

1. For the risk analysis, the predicted value shown was replaced with the actual value in parentheses (from 

Table 1) when the actual DFR data from either after the first or second application was higher than the 

predicted DFR data.

2. Application rates were a nominal 4 lb ai/A for liquid applications (Dursban Pro and Dursban 50W ) and 2.0 

lb ai/A for granular applications (Dursban 2.5G and Dursban 1F).

MRID 46722701 (Greenhouse Ornamental - Total Release Aerosol)

This DFR study (MRID 46722701) examined the residues of chlorpyrifos on smooth leaf and 

hairy leaf ornamentals in greenhouses located in Columbia, Missouri after three applications of 

Duraplex TRTM, a total release aerosol product containing 8.0% chlorpyrifos and 1.6% 

cyfluthrin. The applications were made at a rate of 2.0 oz formulated product per 1,500 ft2(0.008 

lb ai/1,000 ft2), using 7 ± 1-day intervals. The applications were made according to label 

recommendations by placing a single aerosol canister in the greenhouse and releasing the entire 

contents at each application. Treated and control leaf punch samples were collected the 

afternoon of the day prior to each application, four hours after each application, one day after 

application numbers 1 and 2, eight hours after the last (third) application, and on days 1, 2, 3, 5, 

7, 10, 14, 21, 28, and 35 days after the last (third) application. Concurrent laboratory recoveries 

of smooth leaf samples ranged from 93.3% to 153% with an overall mean recovery of 116% ± 

20.4%. Fortification recoveries for hairy leaf samples ranged from 93.9% to 151% with an 

overall mean recovery of 103% ± 13.5%.The overall mean field fortification recoveries for the 

smooth leaf and hairy leaf ornamentals were 96% and 87%, respectively. Only the raw residue 

values for hairy leaf ornamentals required correction for an overall field fortification recovery 

<90%. 

Actual average DFR values are provided in Table I.11 and predicted values calculated from the 

regressions are provided in Table I.12 for hairy ornamentals. For both plant types, dislodgeable 

foliar residues increased initially (to a maximum on 2 days after the last application for the 

smooth leaf ornamentals and 8 hours after the last application for the hairy leaf ornamentals) and 

then declined to a relatively steady state until the end of the monitoring period. The average 

residues on the hairy leaf ornamentals, however, showed a slight increase at the end of the 

monitoring period. The residues for both plants were very similar, with the hairy ornamental 

exhibiting slightly higher DFR values. Therefore, only the hairy ornamental DFR data was using 

for risk assessment purposes.

Table I.11. Summary of Actual DFR Values on Ornamentals (Hairy) After Three 

Applications of Chlorpyrifos

Sampling Interval (Days)

Actual Average DFR (μg/cm2)

Hairy Ornamental

After 1st application

0.167 0.379

1 0.177

7 0.019

After 2nd application

0.167 0.436

1 0.084

7 0.015
Page 194 of 227

Table I.11. Summary of Actual DFR Values on Ornamentals (Hairy) After Three 

Applications of Chlorpyrifos

Sampling Interval (Days)

Actual Average DFR (μg/cm2)

Hairy Ornamental

After 3rd (last) application

0.167 0.363

0.333 0.346

1 0.178

2 0.0399

3 0.0217

5 0.0172

7 0.0105

10 0.00685

14 0.00607

21 0.00396

28 0.00302

35 0.00257

Notes:

1. MQL = 0.002 μg/cm2

2. Residues were corrected for concurrent recoveries.

3. Application rate was a nominal 0.008 lb ai/1000 ft2

Table I.12. Summary of Predicted DFR Values on Ornamentals (Hairy) After Three 

Applications of Chlorpyrifos

Time (Days)

Predicted DFR (μg/cm2)

Duraplex TRTM (Total Release Aerosol)

0 0.0720 (0.436)

1 0.0634 (0.178)

2 0.05594

3 0.04932

4 0.04349

5 0.03835

6 0.03381

7 0.02981

8 0.02628

9 0.02318

10 0.02043

11 0.01802

12 0.01589

13 0.01401

14 0.01235

15 0.01089

16 0.00960
Page 195 of 227

Table I.12. Summary of Predicted DFR Values on Ornamentals (Hairy) After Three 

Applications of Chlorpyrifos

Time (Days)

Predicted DFR (μg/cm2)

Duraplex TRTM (Total Release Aerosol)

17 0.00847

18 0.00746

19 0.00658

20 0.00580

21 0.00512

22 0.00451

23 0.00398

24 0.00351

25 0.00309

26 0.00273

27 0.00240

28 0.00212

29 0.00187

30 0.00165

r

2

0.649

slope -0.127

half-life (days) 5.47

Notes:

1. For the risk analysis, the predicted value shown was replaced with the actual value in parentheses (from 

Table 1) when the actual DFR data from either after the first or second application was higher than the 

predicted DFR data.

2. Application rate was a nominal 0.008 lb ai/1000 ft2

MRID 46722702 (Greenhouse Ornamental - Microencapsulated)

This DFR study (MRID 46722702) examined the residues of chlorpyrifos on smooth leaf 

(Philodendron) and hairy leaf (African Violet) ornamentals in greenhouses located in Columbia, 

Missouri after three applications of DuraGuard METM insecticide, a microencapsulated 

formulation containing 20% (w/w) chlorpyrifos as the active ingredient. The applications were 

made at a rate of 0.5 oz. of DuraGuard METM per gallon of water at a rate of 100 gallons per acre 

(0.626 lbs ai per acre), using 14 ± 1-day intervals. The applications were made using a portable 

gasoline powered sprayer at a height of approximately 24 inches above the canopy. Leaf disk 

samples were collected from the untreated control ornamentals and the treated ornamentals on 

the following schedule: immediately before each application, immediately after the spray had 

dried following each application, one day after application number 1 and 2, and on 0.17 (4 

hours), 0.33 (8 hours), 1, 2, 3, 5, 7, 10, 14, 21, 28, and 35 days after the third application. For 

smooth leaf ornamentals, laboratory recoveries ranged from 73 to 134% with an overall mean 

recovery of 97 ± 19%. For hairy leaf ornamentals, laboratory recoveries ranged from 77 to 

113% with an overall mean recovery of 92 ± 11%. The initial set of field fortification samples 

resulted in poor recoveries (<70%) due to problems associated with the fortification technique. 
Page 196 of 227

Subsequently, control samples were fortified again and analyzed after 15 and 190 days to assess 

storage stability. Since only two samples at one concentration were analyzed, it is uncertain if the 

recoveries obtained from the samples are representative of the field and storage conditions; 

therefore, the field data were not corrected for the recovery results.

Actual average DFR values are provided in Table I.13. Chlorpyrifos persisted on both smooth 

and hairy leaf ornamentals with no rapid decline prior to the completion of the monitoring period 

35 days following the third application. A regression analysis was not performed because the 

data did not follow an exponential decay model.

Table I.13. Summary of Actual DFR Values on Ornamentals (Smooth and Hairy) After 

Three Applications of Chlorpyrifos

Sampling Interval (Days)

Actual Average DFR (μg/cm2)

Microencapsulated

Smooth Hairy

After 1st Application

0 0.201 0.382

1 0.898 0.350

14 (pre-application 2) 0.795 1.085

After 2nd Application

0 0.828 0.446

1 0.862 0.732

14 (pre-application 3) 0.921 0.485

After 3rd (last) application

0 0.609 0.409

0.17 0.818 1.22

0.33 0.514 1.37

1 1.52 0.430

2 2.07 0.424

3 0.234 0.364

5 0.211 0.228

7 0.395 0.394

10 0.345 0.239

14 0.343 0.663

21 0.407 0.648

28 0.249 0.461

35 0.248 0.769

Notes:

1. MQL = 0.00476 μg/cm2

2. Application rate was a nominal 0.626 lbs ai per acre
Page 197 of 227

Appendix J: Summary of Occupational Post-Application Risks 
Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

BERRY: LOW

DFR: MRID

42974501

(cauliflower WP)

Strawberry 1.0 (LC, WDG in 

WSP)

70

(Canopy Management, 

Hand Weeding)

0 620

210 - 230

(Scouting, 

Transplanting)

0 190 1,100

(Hand Harvesting) 4 40

Cranberries 1.5 (LC, WDG in 

WSP)

70

(Hand Weeding, Hand 

Pruning (Shears))

0 410 230 

(Transplanting) 0 130

1,100

(Hand Harvesting, 

Scouting)

5 26

FIELD & ROW 

CROPS: LOW to 

MEDIUM

DFR: MRID

44748102 (sugar 

beet EC)

Location: OR Clover (grown for 

seed) 1.9 (LC) N/A N/A N/A

1,100

(Irrigation,

Scouting)

1 20

N/A N/A N/A

FIELD & ROW 

CROPS: LOW to 

MEDIUM

DFR: MRID

44748102 (sugar 

beet EC)

Location: MN

1 7
Page 199 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

FIELD & ROW 

CROPS: LOW to 

MEDIUM

DFR: MRID 

44748102 (sugar 

beet EC)

Location: OR Perennial Grass Seed 

Crops 1.0 (LC)

70

(Hand Weeding and 

Thinning)

0 580

1,100

(Scouting)

1 37

N/A NA NA

FIELD & ROW 

CROPS: LOW to 

MEDIUM

DFR: MRID 

44748102 (sugar 

beet EC)

Location: MN

0 190 1 12

FIELD & ROW 

CROPS: LOW to 

MEDIUM

(Nongrass 

Animal Feeds)

DFR: MRID

44748102 (cotton 

EC)

Location: TX 

Alfalfa 1.0 (LC, WDG in 

WSP) N/A N/A N/A

1,100

(Scouting) 1 12

N/A NA NA

1,900

(Irrigation) 1 7

FIELD & ROW 

CROPS: LOW to 

MEDIUM

(Fiber)

Cotton 1.0 (LC, WDG in 

WSP)

70 

(Hand Weeding) 0 400 Mechanical harvesting (tramper) activies are not anticipated to result in significant chlorpyrifos exposures due to the 14 day pre-harvest interval (PHI). 
Page 200 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DFR: MRID 

44748102 (cotton 

EC)

Location: CA

210

(Scouting) 0 130

FIELD & ROW 

CROPS: LOW to 

MEDIUM

(Fiber)

DFR: MRID 

44748102 (cotton 

EC)

Location: TX

70 

(Hand Weeding) 0 190

210

(Scouting) 1 63

FIELD & ROW 

CROPS: LOW to 

MEDIUM

(Fiber)

DFR: MRID 

44748102 (cotton 

EC)

Location: MS

70 

(Hand Weeding) 0 150

210

(Scouting) 1 51

FIELD & ROW 

CROPS: LOW to 

MEDIUM

DFR: MRID

44748102 (sugar 

beet EC)

Location: OR

Peppermint, 

Spearmint

2.0 (LC, WDG in 

WSP)

70 

(Hand Weeding) 0 290

1,100

(Scouting) 1 19

1,900 N/A N/A N/A

(Irrigation) 1 11

FIELD & ROW 

CROPS: LOW to 

70 

(Hand Weeding) 1 96 1,100(Scouting) 1 6
Page 201 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

MEDIUM

DFR: MRID

44748102 (sugar 

beet EC)

Location: MN

1,900

(Irrigation) 1 4

FIELD & ROW 

CROPS: LOW to 

MEDIUM

DFR: MRID

44748102 (sugar 

beet EC)

Location: CA

Wheat 1.0 (LC)

70

(Hand Weeding) 0 510 1,100(Scouting) 1 33

N/A N/A N/A

FIELD & ROW 

CROPS: LOW to 

MEDIUM

DFR: MRID

44748102 (sugar 

beet EC)

Location: MN

70

(Hand Weeding) 0 190 1,100(Scouting) 1 12

FIELD & ROW 

CROPS: LOW to 

MEDIUM

(Legume 

Vegetable)

DFR: MRID

44748102 (cotton 

EC)

Location: MS

Soybean 1.0 (LC, WDG in 

WSP)

70

(Hand Weeding) 0 150 1,100(Scouting) 1 10 N/A N/A N/A
Page 202 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

FIELD & ROW 

CROPS: LOW to 

MEDIUM

DFR: MRID

44748102 (sugar 

beet EC)

Location: CA

Sugar beet 1.0 (LC, WDG in 

WSP)

70

(Hand Weeding) 0 510

1,100

(Hand Harvest)

1 33

N/A N/A N/A

210

(Scouting) 0 170

FIELD & ROW 

CROPS: LOW to 

MEDIUM

DFR: MRID

44748102 (sugar 

beet EC)

Location: OR

70

(Hand Weeding) 0 580

1,100

(Hand Harvest)

1 37

210

(Scouting) 1 190

FIELD & ROW 

CROPS: LOW to 

MEDIUM

DFR: MRID

44748102 (sugar 

beet EC)

Location: MN

70

(Hand Weeding) 0 190

1,100

(Hand Harvest)

1 12

210

(Scouting) 1 64

FIELD & ROW 

CROPS: TALL

Corn: Sweet, Field, 

including Grown for 

Seed

1.5 (LC) 70 

(Hand Weeding) 0 100 1,100(Scouting)

1 6

8,800

(Detasseling, Hand 

Harvesting)

3 1
Page 203 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DFR: MRID 

44748102 (sweet 

corn EC)

Location: IL

1,900

(Irrigation) 1 4

FIELD & ROW 

CROPS: TALL

DFR: MRID

44748102 (sweet 

corn EC)

Location: MN

70 

(Hand Weeding) 0 120

1,100

(Scouting)

1 8

8,800

(Detasseling, Hand 

Harvesting) 3 1

1,900

(Irrigation) 1 5

FIELD & ROW 

CROPS: TALL

DFR: MRID

44748102 (sweet 

corn EC)

Location: OR

70 

(Hand Weeding) 0 170

1,100

(Scouting)

1 11

8,800

(Detasseling, Hand 

Harvesting) 2 1

1,900

(Irrigation) 1 6

FIELD & ROW 

CROPS: TALL

DFR: MRID

44748102 (sweet 

corn EC)

Location: IL

Corn: Sweet, Field, 

including Grown for 

Seed

1.0 (WDG in 

WSP)

70 

(Hand Weeding) 0 150

1,100

(Scouting)

1 10

8,800

(Detasseling, Hand 

Harvesting) 2 1

1,900

(Irrigation) 1 6

FIELD & ROW 

CROPS: TALL 70 

(Hand Weeding) 0 190 1,100(Scouting)

1 12

8,800

(Detasseling, Hand 

Harvesting)

2 2
Page 204 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DFR: MRID

44748102 (sweet 

corn EC)

Location: MN

1,900

(Irrigation) 1 7

FIELD & ROW 

CROPS: TALL

DFR: MRID

44748102 (sweet 

corn EC)

Location: OR

70 

(Hand Weeding) 0 260

1,100

(Scouting)

1 16

8,800

(Detasseling, Hand 

Harvesting) 2 2

1,900

(Irrigation) 1 10

FIELD & ROW 

CROPS: TALL

DFR: MRID

44748102 (sweet 

corn EC)

Location: IL

Sorghum 1.0 (LC, WDG in 

WSP)

70 

(Hand Weeding) 0 150

N/A N/A N/A N/A N/A N/A

210

(Scouting) 1 50

FIELD & ROW 

CROPS: TALL

DFR: MRID

44748102 (sweet 

corn EC)

Location: MN

70 

(Hand Weeding) 0 190

210

(Scouting) 1 62

FIELD & ROW 

CROPS: TALL

DFR: MRID

44748102 (sweet 

corn EC)

Location: IL

Sunflowers 1.5 (LC, WDG in 

WSP)

90

(Bird Control, Scouting) 1 33 N/A N/A N/A N/A N/A N/A
Page 205 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

FIELD & ROW 

CROPS: TALL

DFR: MRID

44748102 (sweet 

corn EC)

Location: MN

90

(Bird Control, Scouting) 1 42

TREE FRUIT: 

DECIDUOUS

(Pome Fruits)

DFR: MRID

44748101 (apple 

WP)

Location: CA

Cherries 

(Sour)

4.0

(LC)

230 

(Transplanting) 1 38

1,400

(Hand Harvesting 1 6

3,600

(Thinning Fruit) 5 2

580

(Hand Pruning, Scouting, 

Transplanting)

1 15

TREE FRUIT: 

DECIDUOUS

(Pome Fruits)

DFR: MRID

44748101 (apple 

WP)

Location: WA

230 

(Transplanting) 2 19

1,400

(Hand Harvesting 4 3

3.600 

(Thinning Fruit) 6 1

580

(Hand Pruning, Scouting, 

Transplanting)

3 8

TREE FRUIT: 

DECIDUOUS

(Pome Fruits)

DFR: MRID

44748101 (apple 

WP)

Location: NY

230 

(Transplanting) 2 26

1,400

(Hand Harvesting 5 4

3,600 

(Thinning Fruit) 6 2

580

(Hand Pruning, Scouting, 

Transplanting)

3 10

TREE FRUIT: 

DECIDUOUS

Nectarine, Peach

(dormant, delayed 

3.0

(Nectarine, LC 

230 

(Transplanting) 1 51 No exposure anticipated during N/A N/A N/A N/A N/A
Page 206 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

(Pome Fruits)

DFR: MRID

44748101 (apple 

WP)

Location: CA

dormant) and WDG in 

WSP; Peach, LC 

only) 580

(Hand Pruning, Scouting, 

Transplanting)

1 20

dormant period

TREE FRUIT: 

DECIDUOUS

(Pome Fruits)

DFR: MRID

44748101 (apple 

WP)

Location: WA

230 

(Transplanting) 1 25

580

(Hand Pruning, Scouting, 

Transplanting)

2 10

TREE FRUIT: 

DECIDUOUS

(Pome Fruits)

DFR: MRID

44748101 (apple 

WP)

Location: NY

230 

(Transplanting) 2 35

580

(Hand Pruning, Scouting, 

Transplanting)

3 14

TREE FRUIT: 

DECIDUOUS

(Pome Fruits)

DFR: MRID

44748101 (apple 

WP)

Location: CA

Apples, Cherries, 

Peaches, Pears, 

Plums, Prunes and 

Nectarines

(dormant, delayed 

dormant)

2.0 (LC, WDG in 

WSP)

2.0 (WP in WSP, 

apples only)

230 

(Transplanting) 1 76

No exposure 

anticipated during 

dormant period

N/A N/A N/A N/A N/A

580

(Hand Pruning, Scouting, 

Transplanting)

1 30

TREE FRUIT: 

DECIDUOUS

230 

(Transplanting) 1 38
Page 207 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

(Pome Fruits)

DFR: MRID

44748101 (apple 

WP)

Location: WA

580

(Hand Pruning, Scouting, 

Transplanting)

2 15

TREE FRUIT: 

DECIDUOUS

(Pome Fruits)

DFR: MRID

44748101 (apple 

WP)

Location: NY

230 

(Transplanting) 1 52

580

(Hand Pruning, Scouting, 

Transplanting)

2 21

TREE FRUIT: 

EVERGREEN

(Pine trees)

DFR: MRID 

43062701 (citrus 

EC) Conifers and 

Christmas Trees in 

Plantations

1.0 (Christmas 

Tree, LC, WDG 

in WSP, WP in 

WSP; 

Conifers, LC 

only)

580

(Scouting, Shaping) 0 200

1,400

(Harvesting) 1 84

NA NA NA

1,900 

(Irrigation) 1 62

TREE FRUIT: 

EVERGREEN

(Pine trees)

TTR: MRID 

44829601 

(turf EC)

NA NA NA NA NA NA

6,700

(Harvesting, 

Seedling Production)

0 130

TREE FRUIT: 

EVERGREEN

DFR: MRID 

43062701 (citrus 

EC)

Citrus

6.0 - CA and AZ 

(LC, WDG in 

WSP, WP in 

WSP)

100

(Hand Weeding, Orchard 

Maintenance)

0 200

580

(Scouting, Hand 

Pruning)

1 34

NA NA NA

230 

(Transplanting) 1 86 1,400(Hand Harvesting) 2 14
Page 208 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

4.0 (LC, WDG in 

WSP)

100

(Irrigation, Hand 

Weeding)

0 300

580

(Scouting, Hand 

Pruning)

1 51

NA NA NA

230 

(Transplanting) 0 130 1,400(Hand Harvesting) 2 21

Forestry

DFR: MRID 

44748101 (apple 

WP)

Location: WA Hybrid Cottonwood/ 

Poplar Planations

(dormant, delayed 

dormant)

1.9 (LC)

580

(Scouting) 2 16

1,900

(Irrigation (hand 

set)) 

4 5

NA NA NA

Forestry

DFR: MRID 

44748101 (apple 

WP)

Location: NY

580

(Scouting) 2 22

1,900

(Irrigation (hand 

set))

4 7

Forestry

DFR: MRID 

44748101 (apple 

WP)

Location: CA

Deciduous trees 

(plantations)

1.0 (LC)

100

(Hand Weeding) 0 350

NA NA NA N/A N/A N/A

580

(Scouting) 1 61

Forestry

DFR: MRID 

44748101 (apple 

WP)

Location: WA

100

(Hand Weeding) 0 170

580

(Scouting) 1 30
Page 209 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

Forestry

DFR: MRID 

44748101 (apple 

WP)

Location: NY

100

(Hand Weeding) 0 240

580

(Scouting) 1 41

TREE NUTS

DFR: MRID

44748101

(almond WP)

Location: CA 

(Arid)

Almonds

2.0 (WDG in 

WSP, WP in 

WSP)

100

(Orchard Maintenance, 

Poling)

0 140

NA NA NA

Mechanical 

Sweeping

Mechanical 

Windrowing1

NA NA

190

(Mechanical harvesting –

shaking)

1 74

230 

(Transplanting) 1 61

580

(Scouting)

2 24

TREE NUTS

DFR: MRID

44748101

(almond WP)

Location: CA 

(Arid)

Almonds (dormant 

and delayed 

dormant)

4.0 (LC)

100

(Orchard Maintenance, 

Poling)

1 71

N/A N/A N/A

Pruning, Hand 

230 (dormant)2 NA NA

(Transplanting) 2 31

580

(Scouting)

3 12

TREE NUTS

DFR: MRID

44748101 (pecan 

EC)

Filberts, Pecans, 

Walnuts

2.0 (Pecans, 

Walnuts- LC, 

WDG in WSP; 

Filbert - LC, 

WDG in WSP, 

and WP in WSP)

100

(Orchard Maintenance, 

Poling)

0 1,200

N/A N/A N/A

Mechanical 

Sweeping

Mechanical 

Windrowing1

NA NA

190

(Mechanical harvesting –

tree shaker)

0 630
Page 210 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

Location: TX 230

(Transplanting) 0 520

580

(Hand Pruning, Scouting)

0 210

TREE NUTS

DFR: MRID

44748101 (pecan 

EC)

Location: LA

 100

(Orchard Maintenance, 

Poling)

0 790

190

(Mechanical harvesting –

tree shaker)

0 410

230

(Transplanting) 0 340

580

(Hand Pruning, Scouting)

0 140

TREE NUTS

DFR: MRID

44748101 (pecan 

EC)

Location: GA

 100

(Orchard Maintenance, 

Poling)

0 1,600

190

(Mechanical harvesting –

tree shaker)

0 850

230

(Transplanting) 0 710

580

(Hand Pruning, Scouting)

0 280

TREE NUTS

DFR: MRID

44748101 (pecan 

EC)

Location: TX

Filberts, Walnuts

(dormant and 

delayed dormant)

Walnuts: 

2.0 (LC. WDG in 

WSP)

Filberts: 

2.0 (WP in WSP)

100

(Orchard Maintenance, 

Poling)

0 1,200

N/A N/A N/A Pruning, Hand 

(dormant) 230 2 NA NA

(Transplanting) 0 520

580

(Scouting) 0 210
Page 211 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

TREE NUTS

DFR: MRID

44748101 (pecan 

EC)

Location: GA

100

(Orchard Maintenance, 

Poling)

0 1,600

230 N/A N/A N/A NA NA

(Transplanting) 0 710

580

(Scouting) 0 280

ORNAMENTAL

/ NURSERIES

DFR: MRID

44748101 (apple 

WP) 

Location: CA

Deciduous Trees; 

Plantation, Nursery 1.0 (LC)

230

(Container Moving, Hand 

Pruning, Tying/Training)

0 150

NA NA NA NA NA NA

ORNAMENTAL

/ NURSERIES

DFR: MRID

44748101 (apple 

WP) 

Location: WA

230

(Container Moving, Hand 

Pruning, Tying/Training)

1 76

ORNAMENTAL

/ NURSERIES

DFR: MRID

44748101 (apple 

WP) 

Location: NY

230

(Container Moving, Hand 

Pruning, Tying/Training)

0 100
Page 212 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

ORNAMENTAL

/ NURSERIES

DFR: MRID 

43062701 (citrus 

EC) 

Nonbearing Fruits 

and Nut Trees

(almonds, citrus, 

filbert, cherry, pear, 

plum/prune)

4.0 (LC)

230

(Container Moving, Hand 

Pruning, Tying/Training)

0 130 NA NA NA N/A N/A N/A

ORNAMENTAL

/ NURSERIES

DFR: MRID

44748101 (apple 

WP) 

Location: CA Nonbearing Fruit 

Trees

(peach & nectarine)

3.0 (LC)

230

(Container Moving, Hand 

Pruning, Tying/Training)

1 51

NA NA NA N/A N/A N/A

ORNAMENTAL

/ NURSERIES

DFR: MRID

44748101 (apple 

WP) 

Location: NY

230

(Container Moving, Hand 

Pruning, Tying/Training)

2 35

ORNAMENTAL

/ NURSERIES

DFR: MRID

44748101 (apple 

WP) 

Location: CA

Nonbearing Fruit 

Trees

(apple)

2.0 

(EC)

230

(Container Moving, Hand 

Pruning, Tying/Training)

1 76

NA NA NA N/A N/A N/A

ORNAMENTAL

/ NURSERIES

DFR: MRID

44748101 (apple 

230

(Container Moving, Hand 

Pruning, Tying/Training)

0 100
Page 213 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

WP) 

Location: NY

ORNAMENTAL

/ NURSERIES

DFR: MRID 

43062701 (citrus 

EC) 

Conifer in Nurseries 1.0 (LC)

230

(Container Moving, Hand 

Pruning, Pinching, 

Tying/Training)

0 510 NA NA NA N/A N/A N/A

FIELD & ROW 

CROPS: LOW to 

MEDIUM

DFR: MRID 

44748102 (sugar 

beet EC)

Location: CA

Ornamentals –

Nurseries and 

Greenhouses

2.0 (LC, WP in 

WSP)

230

(Container Moving, Hand 

Pruning, Pinching, 

Tying/Training)

1 78 1,900

(Irrigation) 2 10

4800

(Hand Harvest 

Flowers)

5 4

FIELD & ROW 

CROPS: LOW to 

MEDIUM

DFR: MRID 

44748102 (sugar 

beet EC)

Location: OR

230

(Container Moving, Hand 

Pruning, Pinching, 

Tying/Training)

1 89 1,900

(Irrigation) 1 11

4800

(Hand Harvest 

Flowers)

2 4

FIELD & ROW 

CROPS: LOW to 

MEDIUM

DFR: MRID 

44748102 (sugar 

beet EC)

Location: MN

230

(Container Moving, Hand 

Pruning, Pinching, 

Tying/Training)

1 29 1,900

(Irrigation) 1 4

4800

(Hand Harvest 

Flowers)

3 1

VEGETABLE: Radish 1.0 70 0 510 1,100 1 33 N/A N/A N/A
Page 214 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

ROOT & 

TUBER

DFR: MRID 

44748102 (sugar 

beet EC)

Location: CA

(LC) (Hand Weeding) (Hand Harvesting)

210 

(Scouting) 0 170 1,900(Irrigation) 1 19

VEGETABLE: 

ROOT & 

TUBER

DFR: MRID 

44748102 (sugar 

beet EC)

Location: MN

70

(Hand Weeding) 0 190 1,100(Hand Harvesting) 1 12

210 

(Scouting) 1 64 1,900(Irrigation) 1 7

VEGETABLE: 

ROOT & 

TUBER

DFR: MRID 

44748102 (sugar 

beet EC)

Location: CA Carrot 0.94 (LC)

70

(Hand Weeding) 0 550 1,100(Hand Harvesting) 1 35

N/A N/A N/A

210 

(Scouting) 0 180 1,900(Irrigation) 1 20

VEGETABLE: 

ROOT & 

TUBER

DFR: MRID 

44748102 (sugar 

beet EC)

Location: MN

70

(Hand Weeding) 0 210 1,100(Hand Harvesting) 1 13

210 

(Scouting) 1 68 1,900(Irrigation) 1 8
Page 215 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

VEGETABLE: 

FRUITING

DFR: MRID

44748102 (cotton 

EC)

Location: CA

Pepper 1.0 (WDG in 

WSP)

210

(Scouting) 0 130

1,100

(Hand Harvesting, 

Tying)

2 26

N/A N/A N/A

230

(Transplanting) 0 120 1,900(Irrigation) 2 15

VEGETABLE: 

FRUITING

DFR: MRID

44748102 (cotton 

EC)

Location: TX

210

(Scouting) 1 63

1,100

(Hand Harvesting, 

Tying)

1 12

N/A N/A N/A

230

(Transplanting) 1 57 1,900(Irrigation) 1 7

VEGETABLE: 

FRUITING

DFR: MRID

44748102 (cotton 

EC)

Location: MS

210

(Scouting) 0 51

1,100

(Hand Harvesting, 

Tying)

1 10

230

(Transplanting) 0 46 1,900(Irrigation) 1 6

VEGETABLE: 

HEAD AND 

STEM 

BRASSICA

DFR: MRID 

Cole Crops 

(Broccoli, Brussel 

Sprouts, Cabbage, 

and Cauliflower)

Broccoli: 

1.0 (WP in WSP, 

WDG in 

WSP)

Brussel Sprouts: 

230

(Transplanting – Pruning)

0 190

1,400 

(Hand Weeding) 5 31

4,200 

(Scouting, Hand 

Harvesting)

10 10
Page 216 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

42974501 

cauliflower WP)

Location: AZ

1.0 (LC)

Cabbage: 

1.0 (LC, WP in 

WSP, WDG 

in WSP)

Cauliflower:

1.0 (LC)

1,900

(Irrigation) 6 23

VEGETABLE: 

LEAFY

DFR: MRID 

42974501 

(cauliflower WP)

Cole Crops

(Bok Choy, Collards, 

Kale, Kohlrabi)

1.0 (LC, WP in 

WSP, WDG in 

WSP)

210

(Scouting)

0 210 1,100

(Hand Harvesting) 4 40

N/A N/A N/A

230

(Transplanting) 0 190 1,900(Irrigation) 6 23

STALK & 

STEM 

VEGETABLE

DFR: MRID 

44748102 (sugar 

beet EC) for 

asparagus

Asparagus 1.0 (LC, WDG in 

WSP)

210

(Scouting) 0 170 1,100(Hand Harvesting) 1 33

N/A N/A N/A

230

(Transplanting) 0 160 1,900(Irrigation) 1 19
Page 217 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

Location: CA

STALK & 

STEM 

VEGETABLE

DFR: MRID 

44748102 (sugar 

beet EC) for 

asparagus

Location: OR

210

(Scouting) 0 190 1,100(Hand Harvesting) 1 37

230

(Transplanting) 0 180 1,900(Irrigation) 1 22

STALK & 

STEM 

VEGETABLE

DFR: MRID 

44748102 (sugar 

beet EC) for 

asparagus

Location: MN

210

(Scouting) 1 64 1,100(Hand Harvesting) 1 12

230

(Transplanting) 1 59 1,900(Irrigation) 1 7

STALK & 

STEM 

VEGETABLE

DFR: MRID

44748102 (cotton 

EC MS) data for 

pineapple data

Nonbearing 

pineapple 2.0 (LC)

70

(Hand Weeding) 0 76

N/A N/A N/A N/A N/A N/A

210

(Scouting) 1 25

VINE/ TRELLIS

DFR: MRID 

Grapes

(dormant and 

dormant delayed)

2.0 (LC)

640

(Hand Weeding, 

Scouting)

1 92 N/A N/A N/A N/A N/A N/A
Page 218 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

43062701 (citrus 

EC)

Because citrus is 

LC and apples 

are WP

Grapes (postharvest 

& prior to budbreak)

N/A N/A N/A N/A N/A N/A

TURF

DFR: MRID 

448296-01 (turf 

EC and WP)

Location: CA

Turf for Golf Course 1.0 (LC) NA NA NA NA NA NA

2,500

(Maintenance –

Greens Only)

0 400

 3,700

(Maintenance) 0 270

TURF

DFR: MRID 

448296-01 (turf 

EC and WP)

Location: IN

2,500

(Maintenance –

Greens Only)

0 560

 3,700

(Maintenance) 0 380

TURF

DFR: MRID 

448296-01 (turf 

EC and WP)

Location: MS

2,500

(Maintenance –

Greens Only)

0 340

 3,700

(Maintenance) 0 230

TURF

DFR: MRID 

448296-01 (turf 

EC and WP)

Location: CA

Sod Farm (Turf) 3.76 (LC, WP in 

WSP) NA NA NA NA NA NA

6,700

(Maintenace, 

Harvesting, Slab, 

Transplanting/

Planting)

1 40

TURF

DFR: MRID 

448296-01 (turf 

EC and WP)

Location: IN

6,700

(Maintenace, 

Harvesting, Slab, 

Transplanting/

Planting)

1 56
Page 219 of 227

Table J.1: Spray Applications - Summary of Steady State Post-application Risk Assessment for Chlorpyrifos Using 

Chlorpyrifos-Specific DFR Data (Dermal LOC = 100)

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Estimated Risks 

(LOC=100)

Transfer Coefficient 

(cm2/hr)

(and Activity)

Estimated Risks

(LOC=100)

DATc MOE at 

Day 0

DATc MOE at 

Day 0

DATc MOE at 

Day 0

TURF

DFR: MRID 

448296-01 (turf 

EC and WP)

Location: MS

6,700

(Maintenace, 

Harvesting, Slab, 

Transplanting/

Planting)

1 34
1. Exposure during nut sweeping and windrowing results from contact with soil, for which transfer coefficients are 

currently unavailable. Assessment options include requesting exposure data or a qualitative comparison with a postapplication exposure scenario assumed to result in higher exposure. Note that dislodgeable soil residue would be 

needed for an exposure assessment, as this would be the media contacted by worker’s performing this activity. A 

study monitoring such exposure is available (Exposure of Workers During Reentry into Pecan Groves Treated with 

Super-Tim 80WP, Griffin Corporation, 1994; EPA MRID 43557401), however has yet to be evaluated for 

derivation of transfer coefficients. 

2. Transfer coefficients for dormant pruning are unavailable. Assessment options include requesting exposure data 

or a qualitative comparison with a postapplication exposure scenario assumed to result in higher exposure. Note that dislodgeable branch or bark residue 

would be needed for an exposure assessment, as this would be the surface contacted by workers performing this 

activity.
Table J.2: Granular - Summary of Post-application Risk Assessment for Chlorpyrifos Using Chlorpyrifos-Specific DFR Data

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

Transfer 

Coefficient 

(cm2/hr) 

(and Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

Transfer 

Coefficient 

(cm2/hr)

(and 

Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

DAT

c

MOE at 

Day 0 DATc

MOE 

at Day 

0

DAT

c

MOE at 

Day 0

FIELD & ROW 

CROPS: LOW 

to MEDIUM

(Legume 

Vegetable)

DFR:

MRID 

44748102 

(sweet corn G)

Location: IL

Soybean 1.0 70 

(Hand Weeding) 0 5,200 1,100(Scouting) 0 330 N/A N/A N/A

FIELD & ROW 

CROPS: LOW 

to MEDIUM

DFR: MRID 

44748102 

(sweet corn G)

Location: IL Sugar beet 2.0

70

(Hand Weeding) 0 2,600

1100

(Hand 

Harvesting)

0 170

N/A N/A N/A

210

(Scouting) 0 870

FIELD & ROW 

CROPS: LOW 

to MEDIUM

DFR: MRID 

44748102 

(sweet corn G)

Location: OR

70

(Hand Weeding) 0 1,000

1100

(Hand 

Harvesting)

1 67 210

(Scouting) 0 350

FIELD & ROW 

CROPS: LOW 

to MEDIUM

DFR: MRID 

44748102 

(sweet corn G)

Location: IL

Peanuts 4.0

70

(Hand Weeding) 0 1,300

1900

(Irrigation) 1 48 N/A N/A N/A

210

(Scouting) 0 440
Page 222 of 227

Table J.2: Granular - Summary of Post-application Risk Assessment for Chlorpyrifos Using Chlorpyrifos-Specific DFR Data

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

Transfer 

Coefficient 

(cm2/hr) 

(and Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

Transfer 

Coefficient 

(cm2/hr)

(and 

Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

DAT

c

MOE at 

Day 0 DATc

MOE 

at Day 

0

DAT

c

MOE at 

Day 0

FIELD & ROW 

CROPS: TALL

DFR: MRID 

44748102 

(sweet corn G)

Location: IL Corn, Sweet, 

Field, and Grown 

for Seed

2.0

70 

(Hand Weeding) 0 2,600

1,100

(Scouting) 0 170

8,800

(Detasseling

, Hand 

Harvesting)

1 21

1,900

(Irrigation) 1 97

 FIELD & 

ROW CROPS: 

TALL

DFR: MRID 

44748102 

(sweet corn G)

Location: OR

70 

(Hand Weeding) 0 1,000

1,100

(Scouting) 0 67

8,800

(Detasseling

, Hand 

Harvesting

1 8

1900

(Irrigation) 1 39

NURSERY

DFR: MRID 

44748102 

(sweet corn G)

Location: IL

Ornamental 

Woody Shrubs 

and Vines

- Preharvest

6.0

(Note: All 

other 

ornamental 

applications 

are either 1.1 

or 1.0)

230

(Container Moving) 0 270

N/A N/A N/A N/A N/A N/A NURSERY

DFR: MRID 

44748102 

(sweet corn G)

Location: OR

230

(Container Moving) 0 110
Page 223 of 227

Table J.2: Granular - Summary of Post-application Risk Assessment for Chlorpyrifos Using Chlorpyrifos-Specific DFR Data

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer Coefficient 

(cm2/hr) 

(and Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

Transfer 

Coefficient 

(cm2/hr) 

(and Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

Transfer 

Coefficient 

(cm2/hr)

(and 

Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

DAT

c

MOE at 

Day 0 DATc

MOE 

at Day 

0

DAT

c

MOE at 

Day 0

TURF

DFR: MRID 

448296-01 (turf 

G and fertilizer)

Location: CA

Turf for Sod or 

Seed 1 N/A N/A N/A N/A N/A N/A

6,700

(Maintenan

ce, 

Harvesting

Slab, 

Transplanti

ng/ 

Planting)

0 180

Golf Course. 1 N/A N/A N/A N/A N/A N/A

2,500

(Maintenan

ce – Greens 

Only)

0 480

 3,700

(Maintenan

ce)

0 330
Table J.3: Microencapsulated - Summary of Post-application Risk Assessment for Chlorpyrifos Using Chlorpyrifos -Specific DFR Data

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer 

Coefficient 

(cm2/hr) 

(and Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

Transfer 

Coefficient 

(cm2/hr) 

(and 

Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

Transfer 

Coefficient 

(cm2/hr)

(and Activity)

Short- and 

Intermediate-Term 

Risks (LOC=100)

DAT

c

MOE at 

Day 0 DATc MOE at Day 0 DATc MOE at Day 0

NURSERY 

DFR: MRID 

46722702

(smooth

ornamentals 

ME)

Ornamentals –

Nurseries and 

Greenhouses

0.0070 lb ai/gal

1.4 lb ai/A

230

(Container 

Moving, Hand 

Pruning, Pinching

0 74 1,900

(Irrigation) > 35 9

4800

(Hand Harvest 

of Cut Flowers 

or Foliage)

> 35 4
Table J.4: Fogger - Summary of Postapplication Risk Assessment for Chlorpyrifos Using Chlorpyrifos -Specific

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer 

Coefficient 

(cm2/hr) 

(and Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

Transfer 

Coefficient 

(cm2/hr) 

(and 

Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

Transfer 

Coefficient 

(cm2/hr)

(and Activity)

Short- and 

Intermediate-Term 

Risks (LOC=100)

DAT

c

MOE at 

Day 0 DATc MOE at Day 0 DATc MOE at Day 0

NURSERY 

DFR: MRID 

46722701

(hairy 

ornamentalsaerosol)

Ornamentals -

Greenhouse 0.29

230

(Container 

Moving, Hand 

Pruning, Pinching

0 370 1,900

(Irrigation) 1 45

4800

(Hand Harvest 

of Cut Flowers 

or Foliage)

2 18
Table J.5: All Formulations - Summary of Post-application Risk Assessment for Total Toxic Residue (Chlorpyrifos + Chlorpyrifos Oxon) 

Using Chlorpyrifos -Specific DFR Data

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer 

Coefficient 

(cm2/hr) 

(and Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

Transfer 

Coefficient 

(cm2/hr) 

(and 

Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

Transfer 

Coefficient 

(cm2/hr)

(and Activity)

Short- and 

Intermediate-Term 

Risks (LOC=100)

DAT

c

MOE at 

Day 0 DATc MOE at Day 0 DATc MOE at Day 0

NURSERY 

DFR: MRID 

46722702

(smooth

ornamentals 

ME)

Ornamentals –

Nurseries and 

Greenhouses

0.0070 lb ai/gal

1.4 lb ai/A

230

(Container 

Moving, Hand 

Pruning, Pinching

3 39 1,900

(Irrigation) > 35 5

4800

(Hand Harvest 

of Cut Flowers 

or Foliage)

> 35 2

FIELD & ROW 

CROPS: LOW 

to MEDIUM

DFR: MRID 

44748102 

(sugar beet EC)

Location: CA

Ornamentals –

Nurseries and 

Greenhouses

2.0 (LC, WP in 

WSP)

230

(Container 

Moving, Hand 

Pruning, 

Pinching, 

Tying/Training)

1 41 1,900

(Irrigation) 4 5

4800

(Harvesting 

flowers or 

foliage grown 

for cutting)

6 2

FIELD & ROW 

CROPS: LOW 

to MEDIUM

DFR: MRID 

44748102 

(sugar beet EC)

Location: OR

230

(Container 

Moving, Hand 

Pruning, 

Pinching, 

Tying/Training)

1 31 1,900

(Irrigation) 2 4

4800

(Harvesting 

flowers or 

foliage grown 

for cutting)

2 2

FIELD & ROW 

CROPS: LOW 

to MEDIUM

DFR: MRID 

44748102 

(sugar beet EC)

Location: MN

230

(Container 

Moving, Hand 

Pruning, 

Pinching, 

Tying/Training)

1 10 1,900

(Irrigation) 4 1

4800

(Harvesting 

flowers or 

foliage grown 

for cutting)

6 0
Page 227 of 227

Table J.5: All Formulations - Summary of Post-application Risk Assessment for Total Toxic Residue (Chlorpyrifos + Chlorpyrifos Oxon) 

Using Chlorpyrifos -Specific DFR Data

Crop Groupa Use Site App Rates (lbs. 

ai/ acre)b

Low Medium High

Transfer 

Coefficient 

(cm2/hr) 

(and Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

Transfer 

Coefficient 

(cm2/hr) 

(and 

Activity)

Short- and 

IntermediateTerm Risks 

(LOC=100)

Transfer 

Coefficient 

(cm2/hr)

(and Activity)

Short- and 

Intermediate-Term 

Risks (LOC=100)

DAT

c

MOE at 

Day 0 DATc MOE at Day 0 DATc MOE at Day 0

NURSERY 

DFR: MRID 

46722701

(hairy 

ornamentalsaerosol)

Ornamentals -

Greenhouse 0.29

230

(Container 

Moving, Hand 

Pruning, Pinching

0 200 1,900

(Irrigation) 2 24

4800

(Hand Harvest 

of Cut Flowers 

or Foliage)

5 9