Page 3 of 27

Table of Contents

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

2.0 Summary of Conclusions and Data Requirements .............................................................. 5

3.0 Hazard Characterization....................................................................................................... 5

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

5.0 Residential Exposure and Risk Estimates............................................................................ 9

5.1 Spray Drift...................................................................................................................... 10

5.2 Residential Bystander Post-Application Inhalation Exposure ....................................... 11

Appendix A. Summary of Residential Handler and Post-application Algorithms...................... 12

1.0 Residential Handlers.......................................................................................................... 12

1.1 Residential Handler Exposure Calculations................................................................... 12

1.1.1 Turf and Indoor Environments................................................................................ 12

1.2 Residential Handler Dose Calculations.......................................................................... 12

2.0 Residential Post-application............................................................................................... 12

2.1 Turf/Physical Activities on Turf .................................................................................... 12

2.2 Turf/Mowing .................................................................................................................. 18

2.3 Turf/Golfing ................................................................................................................... 19

2.4 Indoor Environments...................................................................................................... 20
Page 4 of 27

1.0 Executive Summary

As a result of a petition by the thiamethoxam registrant, Syngenta, requesting an increased 

tolerance for residues of thiamethoxam and its metabolite, CGA-322704 (chlothianidin), in or on 

coffee from use of new formulations and higher maximum seasonal use rates on imported coffee, 

HED has conducted a residential exposure/risk assessment for existing residential uses of 

thiamethoxam in order to address potential aggregate (dietary + non-dietary) risks. There are no 

new thiamethoxam residential uses associated with this regulatory action. This document 

presents the re-evaluation of existing thiamethoxam residential uses – home lawn/turf and indoor 

crack-and-crevice uses – following updated policies and guidance in place since previous risk 

assessments.

Thiamethoxam is a broad spectrum nitroguanidine insecticide which belongs to the pesticidal 

class of compounds known as the neonicotinoids (Group 4A; Insecticide Resistance Action 

Committee). It has activity against sucking and chewing insects on a wide variety of crops. 

Thiamethoxam appears to interfere with the nicotinic acetylcholine receptors of the insect’s 

nervous system, but the specific receptor site is unknown at this time. It does not inhibit 

cholinesterase or interfere with sodium channels and, therefore, has a different mode of action 

than organophosphate, carbamate, and pyrethroid insecticides.

Thiamethoxam is classified as Toxicity Category III for acute oral toxicity and Category IV for

acute dermal and acute inhalation toxicity and for skin and eye irritation potential. 

Thiamethoxam is not a dermal sensitizer. Thiamethoxam has been classified as “Not Likely to 

be Carcinogenic to Humans”, therefore, there is no concern over cancer risk with the proposed or 

existing uses.

The incidental oral point of departure (POD) for all durations is a no observed adverse effect 

level (NOAEL) of 8.23 mg/kg/day, and is based on effects seen in the kidney, liver, testis, ovary, 

and hematopoietic system in a 90-day oral study in the dog. The adult dermal POD for all 

durations is a NOAEL of 1.2 mg/kg/day, and is based on sperm abnormalities and testicular 

effects observed after in utero and post-natal exposure in the rat reproduction studies. Although 

a 21-day dermal toxicity study in rats is available, HED selected a reproductive NOAEL because 

the reproductive parameters are not evaluated in the dermal toxicity study and thus, the 

consequences of these effects cannot be ascertained for the dermal route of exposure. Since the 

adult dermal endpoint was based on an oral study, a 5% dermal absorption factor was used to 

estimate dermal exposure for all durations. The infants and children’s (1-6 years) dermal POD 

for all durations is a NOAEL of 60 mg/kg/day, and is based on liver effects seen in a 28-day 

dermal toxicity study in rats. The inhalation POD for all durations is a NOAEL of 1.2 

mg/kg/day and is based on the same study used for the adult dermal POD. Other than acute 

toxicity, no inhalation studies are available; therefore, the reproductive endpoint is selected for 

inhalation exposure. Inhalation toxicity is assumed to be equivalent to oral toxicity. 

Since the dermal and inhalation toxicological endpoints of concern for adults are based on a 

reproductive study, the body weight of an adult female (69 kg) is used to estimate dermal and 

inhalation doses. Resulting dermal and inhalation risk estimates were combined into total risk 

estimates because the same endpoint was chosen to evaluate both routes of exposure. For risks 
Page 5 of 27

to children, the dermal and incidental oral exposures were combined due to a common 

toxicological endpoint. For all exposure scenarios, uncertainty factors (UF) of 10X for 

interspecies and 10X for intraspecies variation (total UF of 100X) were used. Therefore, for all 

residential exposure scenarios, the level of concern for the margin of exposure (MOE) is 100. 

Based upon the hazard data and the methods used to estimate exposure, it is recommended that 

the 10X FQPA SF for the protection of infants and children be reduced to 1X.

Thiamethoxam has existing registrations for home uses on lawns/turf and indoor crack-andcrevice uses. Short-term dermal and inhalation handler exposures are expected for those making 

applications at their homes and short-term dermal, inhalation, and incidental oral exposures are 

expected via contact with residues following applications in outdoor and indoor home

environments. No risks of concern were identified for any scenario – all MOEs were greater 

than 100.

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

the Residential SOPs (Turf SOP and Indoor Environments SOP), are (1) subject to ethics review 

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

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

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

can be found at the Agency website1. 

2.0 Summary of Conclusions and Data Requirements

Based on a re-evaluation using the 2012 Residential SOPs, no existing thiamethoxam residential 

use presents a risk of concern. 

Residue Data Requirements

Turf Transferable Residue: In accordance with the updated Part 158 data requirements (2007), a 

turf transferable residue (TTR) study is required for all occupational (e.g., sod farms, golf 

courses, parks, and recreational areas) or residential turf uses. An existing thiamethoxam TTR 

study (“Determination of Transferable Turf Residues on Turf Treated with Granular and Water 

Dispersible Granular Formulation of Thiamethoxam”, L. Rosenheck; EPA MRID 46402915)

was used and continues to provide reliable information for residential turf use risk assessments. 

No additional data are required.

3.0 Hazard Characterization

The database for acute toxicity for thiamethoxam is complete and is summarized below in Table 

3.1. Thiamethoxam is classified as Toxicity Category III for acute oral toxicity and Category IV 

for acute dermal and acute inhalation toxicity, and for skin and eye irritation potential. 

Thiamethoxam is not a dermal sensitizer. 

 

1

http://www.epa.gov/opp00001/science/residential-exposure-sop.html
Page 6 of 27

The incidental oral POD for all durations is a NOAEL of 8.23 mg/kg/day, and is based on 

slightly prolonged prothrombin times and decreased plasma albumin and A/G ratio (both sexes); 

decreased calcium levels and ovary weights and delayed maturation in the ovaries; decreased 

cholesterol and phospholipid levels, testis weights, spermatogenesis, and spermatic giant cells in 

testes from a 90-day oral study in the dog. The lowest-observed-adverse-effect-level (LOAEL)

ranged from 32 mg/kg/day in males to 33.9 mg/kg/day in females.

The adult dermal POD for all durations is a NOAEL of 1.2 mg/kg/day, and is based on sperm 

abnormalities and testicular effects observed after in utero and post-natal exposure in the rat 

reproduction studies. Since no data are available to indicate how much exposure will induce the 

effects, the effects are considered to be appropriate for all exposure durations. Although a 21-

day dermal toxicity study in rats is available, HED selected a reproductive NOAEL because the 

reproductive parameters are not evaluated in the dermal toxicity study and thus, the 

consequences of these effects cannot be ascertained for the dermal route of exposure. Since the 

adult dermal endpoint was based on an oral study, a 5% dermal absorption factor was used to 

estimate dermal exposure for all durations. 

The infants and children’s (1-6 years) dermal POD for all durations is a NOAEL of 60 

mg/kg/day and is based on increased plasma glucose, triglyceride levels, and alkaline 

phosphatase activity and inflammatory cell infiltration in the liver and necrosis of single 

hepatocytes in females from a 28-day dermal toxicity study in rats. The LOAEL is 250 

mg/kg/day (females).

The inhalation POD for all durations is a NOAEL of 1.2 mg/kg/day and is based on sperm 

abnormalities and testicular effects observed after in utero and post-natal exposure in the rat 

reproduction studies. Since no data are available to indicate how much exposure will induce the 

effects, the effects are considered to be appropriate for all exposure durations. Other than acute 

toxicity, no inhalation studies are available. Therefore, the reproductive endpoint is selected for 

inhalation exposure. Inhalation toxicity is assumed to be equivalent to oral toxicity. 

Table 3.1. Acute Toxicity Profile of Thiamethoxam

Guideline No. Study Type MRID Results Toxicity Category

870.1100 Acute oral [rat] 44703314 LD50: 1563 mg/kg III

870.1200 Acute dermal [rabbit] 44703316 LD50 = 13.3 g/kg IV

870.1300 Acute inhalation [rat] 44703317 LC50 > 3.72 mg/L IV

870.2400 Acute eye irritation [rabbit] 44703318 PIS = 10 at 1 hr

PIS = 0 at 24 hr

Minimally irritating

IV

870.2500 Acute dermal irritation 44703319 PIS = 0 IV

870.2600 Skin sensitization 44710401 Is not a sensitizer using 

method of Magnusson and 

Kligman

N/A
Page 7 of 27

On April 27, 2005, the Cancer Assessment Review Committee (CARC) of the Health Effects 

Division of the Office of Pesticide Programs met to re-evaluate the carcinogenic potential of 

thiamethoxam. In accordance with the EPA’s Final Guidelines for Carcinogen Risk Assessment 

(March, 2005), the CARC classified Thiamethoxam as “Not Likely to be Carcinogenic to 

Humans” based on convincing evidence that a non-genotoxic mode of action for liver tumors 

was established in the mouse and that the carcinogenic effects are a result of a mode of action 

dependent on sufficient amounts of a hepatotoxic metabolite produced persistently. 

Quantification of cancer risk is not required.

A summary of the toxicological doses and endpoints is provided in Table 3.2.

Table 3.2 Summary of Toxicological Doses and Endpoints for Thiamethoxam for Use in Non-Occupational 

Human Health Risk Assessments

Exposure/ 

Scenario

Point of 

Departure

Uncertainty/

FQPA Safety 

Factors

Level of 

Concern for 

Risk 

Assessment

Study and Toxicological Effects

Incidental Oral 

(all durations)

NOAEL= 

8.23 

mg/kg/day

UFA= 10x

UFH= 10x

FQPA SF =1

MOE= 100 

(residential)

90-day Dog study 

LOAEL= 32 (males) 33.9 (females) 

mg/kg/day based on slightly prolonged 

prothrombin times and decreased plasma 

albumin and A/G ratio (both sexes); 

decreased calcium levels and ovary 

weights and delayed maturation in the 

ovaries (females); decreased cholesterol 

and phospholipid levels, testis weights, 

spermatogenesis, and spermatic giant 

cells in testes (males).

Dermal (all 

durations) 

(Adults)

Oral study 

NOAEL= 1.2

mg/kg/day

(dermal 

absorption 

rate = 5%)

UFA= 10x

UFH= 10x

FQPA SF =1

MOE= 100 

(residential)

2-Generation reproduction study 

LOAEL = 1.8 mg/kg/day based on 

increased incidence and severity of 

tubular atrophy in testes of F1 generation 

males.

2-Generation reproduction study 

LOAEL = 3 (males), not determined 

(females) mg/kg/day based on sperm 

abnormalities in F1 males.

Dermal (all 

durations) 

(infants/

children 1-6 

yrs)

Dermal 

Study

NOAEL=60 

mg/kg/day

UFA= 10x

UFH= 10x

FQPA SF =1

MOE= 100 

(residential)

Rat 28-Day Dermal Toxicity Study

LOAEL = 250 (females) mg/kg/day 

based on increased plasma glucose, 

triglyceride levels, and alkaline 

phosphatase activity and inflammatory 

cell infiltration in the liver and necrosis 

of single hepatocytes in females. 

Inhalation (all 

durations)

Oral study 

NOAEL= 1.2 

mg/kg/day

(inhalation 

toxicity = 

oral toxicity)

UFA= 10x

UFH= 10x

FQPA SF =1x

MOE= 100 

(residential)

2-Generation reproduction study 

LOAEL = 1.8 mg/kg/day based on 

increased incidence and severity of 

tubular atrophy in testes of F1 generation 

males.

2-Generation reproduction study 

LOAEL = 3 (males), not determined 

(females) mg/kg/day based on sperm 

abnormalities in F1 males.
Page 8 of 27

Table 3.2 Summary of Toxicological Doses and Endpoints for Thiamethoxam for Use in Non-Occupational 

Human Health Risk Assessments

Exposure/ 

Scenario

Point of 

Departure

Uncertainty/

FQPA Safety 

Factors

Level of 

Concern for 

Risk 

Assessment

Study and Toxicological Effects

Cancer (oral, 

dermal, 

inhalation)

“Not Likely to be Carcinogenic to Humans” based on convincing evidence that a nongenotoxic mode of action for liver tumors was established in the mouse. Quantification of 

cancer risk is not required. 

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

mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures. NOAEL 

= no observed adverse effect level. LOAEL = lowest observed adverse effect level. UF = uncertainty factor. UFA = 

extrapolation from animal to human (interspecies). UFH = potential variation in sensitivity among members of the human 

population (intraspecies). FQPA SF = FQPA Safety Factor. MOE = margin of exposure. LOC = level of concern. 

Since the dermal and inhalation toxicological endpoints of concern for adults are based on a 

reproductive study, the body weight of an adult female (69 kg) is used to estimate dermal and 

inhalation dose in the assessment. Resulting dermal and inhalation risk estimates for adults were 

combined into total risk estimates because the same endpoint was chosen to evaluate both routes 

of exposure. For children, dermal and incidental oral risk estimates are combined because of 

similar toxicological endpoints. For all exposure scenarios, uncertainty factors (UF) of 10x for 

interspecies and 10x for intraspecies variation (total UF of 100x) were used. Therefore, for all 

residential exposure scenarios, the level of concern for the margin of exposure (MOE) is 100. 

Based upon the hazard data and the methods used to estimate exposure, it is recommended that 

the 10X FQPA SF for the protection of infants and children be reduced to 1X. There is no 

quantitative or qualitative evidence of increased susceptibility of rat or rabbit fetuses to in utero

exposure to thiamethoxam in the developmental toxicity studies. The developmental NOAELs 

are either higher than or equal to the maternal NOAELs. The Developmental Neurotoxicity

DNT workgroup concluded there was no evidence of increased susceptibility in the DNT study 

in rats, based on evaluation of additional brain morphometric data for the low- and mid-dose 

pups (January 17, 2007). Although there is evidence of increased quantitative susceptibility for 

male pups of both two generation reproductive studies, NOAELs and LOAELs were established 

in these studies and the Agency selected the NOAEL for testicular effects in F1 pups as the basis 

for risk assessment. The Agency has confidence that the NOAEL selected for risk assessment is 

protective of the most sensitive effect (testicular effects) for the most sensitive subgroup (pups) 

observed in the toxicological database. 

4.0 Use Profile 

A summary of the existing residential uses of thiamethoxam is provided in Table 4.1 below.

Table 4.1. Summary of Use Directions for Existing Residential Uses of Thiamethoxam

Residential Use Formulation Application

Rate Application Equipment HED Reference/Source

Turf (golf courses, 

home lawns, 

recreational fields)

Waterdispersible 

granule

0.266 lb ai/acre; 

0.00133 lb 

ai/gallon

Groundboom

(professional applicators) D359207;

Manually-pressurized handwand D332064

Mechanically-pressurized handgun
Page 9 of 27

Table 4.1. Summary of Use Directions for Existing Residential Uses of Thiamethoxam

Residential Use Formulation Application

Rate Application Equipment HED Reference/Source

(professional applicators)

Backpack sprayer

Granule 0.248 lb ai/acre

Tractor-drawn spreader

(professional applicators)

Rotary spreader

Belly grinder

Indoor (crack-andcrevice)

Liquid 

concentrate

(21.6% ai)

0.5 gallon/1000 

ft2of 0.1% 

solution (0.0084 

lb ai/gallon)

Manually-pressurized handwand

D359207

(rate re-calculated 

from label)

5.0 Residential Exposure and Risk Estimates

There are no proposed residential uses at this time; however, for the purposes of evaluating 

aggregate (dietary and non-dietary) exposure for the current regulatory action, there are existing 

residential uses that have been reassessed in this document to reflect updates to HED’s 2012 

Residential SOPs2along with policy changes for body weight assumptions. The revision of 

residential exposures will impact the human health aggregate risk assessment for the tolerance 

assessment for imported coffee.

Thiamethoxam has existing residential uses on turf and indoor environments (crack-and-crevice 

uses). Both residential handler and post-application exposures are expected. Exposures are 

expected to be short-term (i.e., up to 30 days) in duration. Based on HED’s revised “Residential 

SOPs”, no risks of concern were identified for the existing residential uses of thiamethoxam.

A summary of the risk estimates are provided in Tables 5.1 (residential handler), Table 5.2 

(residential post-application) and 5.3 (residential scenarios recommended for the aggregate 

assessment). Appendix A provides exposure algorithms and descriptions of inputs from HED’s 

revised “Residential SOPs”.

Table 5.1 Residential Handler Non-cancer Exposure and Risk Estimates for Existing Residential Uses of Thiamethoxam.

Scenario Formulation Equipment

Dose

(mg/kg-day)

MOE

Dermal Inhalation Dermal Inhalation Combined

Lawns/Turf

WDG

Manually-pressurized handwand 0.00033 0.00011 3,600 11,000 2,700

Backpack 0.00033 0.00011 3,600 11,000 2,700

Granule

Rotary / push-type spreader 0.000073 0.0000047 16,000 260,000 15,000

Belly grinder 0.0018 0.0000039 670 310,000 670

Indoor 

(crack-andcrevice)

Liquid Manually-pressurized handwand 0.00021 0.000067 5,700 18,000 4,300

 

2 Available: http://www.epa.gov/pesticides/science/residential-exposure-sop.html
Page 10 of 27

Table 5.2: Residential Post-application Non-cancer Exposure and Risk Estimates for Existing Residential Uses of 

Thiamethoxam.

Use/Target Lifestage Post-application 

Exposure Scenario

Dose

(mg/kg-day) MOE3

Combined Routes

(X indicates included 

in Combined MOE)

Combined 

MOE

Turf

(spray application)1

Adult Dermal

High-contact 

(playing) 0.0024 500 --

NA Mowing 0.000049 25,000 --

Golfing 0.00019 6,400 --

Child 11<16 Dermal Mowing 0.000048 25,000 NA Golfing 0.00019 6,400 --

Child 6<11 Dermal Golfing 0.00022 5,400 -- NA

Child 1<2

Dermal (high-contact 

play) 0.082 740 X

Hand to Mouth 0.0017 4,900 X 640

Object to Mouth 0.00005 160,000 --

Incidental Soil Ingestion 9.0E-06 910,000 --

Indoor

(crack-and-crevice)

Adult

Dermal (playing on 

carpet)2 0.00049 2,500 X

2500

Inhalation 9.1E-07 1,300,000 X

Child 1<2

Dermal (playing on 

carpet)3 0.0081 7,400 X

Inhalation 3.4E-06 360,000 -- 3500

Hand to Mouth (playing 

on carpet)2 0.0012 6,800 X

1 Risk estimates are based on the maximum day-of-application value from a submitted turf transferable residue study (MRID 

46402915) conducted at the maximum application. Risks from liquid spray applications are presented and are considered healthprotective of granule formulation uses as most measured TTR values for granule formulations were < LOD.

2 Risk estimates presented only in this table from contacting treated carpets, as risks from contacting other surfaces are lower.

3 MOEs are for short-term exposures only.

Table 5.3 Recommendations for the Residential Exposures for the Thiamethoxam Aggregate Assessment.1

Lifestage

Handler Exposure 

(mg/kg/day)2 Residential 

Handler 

Total 

Exposure 

(mg/kg/day)3

Residential 

Handler 

Total MOE

Post-application Exposure 

(mg/kg/day)4

Residential 

Postapplication 

Total 

Exposure 

(mg/kg/day)

Residential 

Postapplication 

MOE Dermal Inhalation Dermal Inhalation Oral 5

Short-/Intermediate-Term

Adult 0.0018 0.0000039 0.0018 670 0.0024 N/A N/A 0.0024 500

Child 1<2 N/A 0.082 N/A 0.0017 0.083 640

1 Bolded risk estimates should contribute to the residential exposure portion of the aggregate assessment. 

2 Residential Handler Dose = the highest handler dose for each applicable lifestage of all scenarios assessed from Table 5.1 (i.e., belly grinder). 

Total = dermal + inhalation.

3 Residential Handler MOE = the MOEs associated with the highest doses identified in Table 5.1 (i.e., belly grinder). Total = 1/ (1/Dermal MOE) 

+ (1/Inhalation MOE).

4 Residential Post-application Dose = the highest post-application dose for each applicable lifestage of all scenarios assessed from Table 5.2

(adults: turf post-application; children 1< 2: turf post-application). Total = dermal + inhalation + incidental oral, where applicable.

5 Residential Post-application MOE = the MOEs associated with the highest doses identified in Table 5.2 (adults: turf post-application; children 

1< 2: turf post-application). Total = 1/ (1/Dermal MOE) + (1/Inhalation MOE) + (1/Incidental oral MOE).

5.1 Spray Drift

Spray drift is always a potential source of exposure to residents nearby to spraying operations. 

This is particularly the case with aerial applications, but, to a lesser extent, could also be a 
Page 11 of 27

potential source of exposure from ground application methods employed for thiamethoxam. The 

Agency has been working with the Spray Drift Task Force, EPA Regional Offices and State 

Lead Agencies for pesticide regulation and other parties to develop the best spray drift 

management practices (see the Agency’s Spray Drift website for more information)

3

. On a 

chemical by chemical basis, the Agency is now requiring interim mitigation measures for aerial 

applications that must be placed on product labels/labeling. The Agency has completed its 

evaluation of the new database submitted by the Spray Drift Task Force, a membership of U.S. 

pesticide registrants, and is developing a policy on how to appropriately apply the data and the 

AgDRIFT computer model to its risk assessments for pesticides applied by air, orchard airblast 

and ground hydraulic methods. After the policy is in place, the Agency may impose further 

refinements in spray drift management practices to reduce off-target drift with specific products 

with significant risk estimates associated with drift.

Note that an application rate of 0.266 lb ai/acre was used in the updated assessment of the 

existing lawn/turf registration to estimate post-application residential exposure of children. As 

this rate is equal to or higher than those from other thiamethoxam uses, exposures resulting from 

direct application to lawns/turf are likely protective of any exposure via spray drift from other 

thiamethoxam uses.

5.2 Residential Bystander Post-Application Inhalation Exposure

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

assessment was not performed at this time for the agricultural thiamethoxam uses primarily 

because of the low acute inhalation toxicity (Toxicity Category IV) and low vapor pressure (6.6

x 10-9 mmHg). However, volatilization of pesticides may be a source of post-application 

inhalation exposure to individuals nearby pesticide applications. The Agency sought expert 

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

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

received the SAP’s final report on March 2, 20104. The Agency is in the process of evaluating 

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

and, subsequently, the way to incorporate post-application inhalation exposure into the Agency's 

risk assessments. If new policies or procedures are developed, the Agency may revisit the need 

for a quantitative post-application inhalation exposure assessment for the existing uses of 

thiamethoxam.

Note, however, that inhalation exposure from volatilization of thiamethoxam following indoor 

uses was assessed and no risks of concern were identified.

 

3 Available: http://www.epa.gov/opp00001/factsheets/spraydrift.htm 

4 Available: http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html
Page 12 of 27

Appendix A. Summary of Residential Handler and Post-application Algorithms

1.0 Residential Handlers

1.1 Residential Handler Exposure Calculations

1.1.1 Turf and Indoor Environments

Dermal and Inhalation 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:

E = exposure (mg/day);

UE = unit exposure (mg/lb ai);

AR = application rate (e.g., lb ai/ft2, lb ai/gal); and

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

1.2 Residential Handler Dose Calculations

Dermal and/or inhalation absorbed doses normalized to body weight are calculated as:

D = E *AF / BW

where:

D = dose (mg/kg-day);

E = exposure (mg/day);

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

BW = body weight (kg).

2.0 Residential Post-application

2.1 Turf/Physical Activities on Turf

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.
Page 13 of 27

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). However, if data are not available, then TTRt can be calculated using the following 

formula:

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 108μg/lb); and

CF3 = area unit conversion factor (1.08 x 10-3ft2/ cm2or 2.47 x 10-8acre/cm2).

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 A-1: 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) [input]

F

Fraction of AR as TTR 

following application (if 

chemical-specific data is 

unavailable)

L/WP/WDG 0.01

Granules 0.002
Page 14 of 27

Table A-1: Turf (Physical Activities) -- Inputs for Residential Post-application Dermal Exposure

Algorithm Notation Exposure Factor

(units) Point Estimate(s)

FD

Daily residue dissipation 

(if chemical-specific data 

is unavailable)

(fraction)

L/WP/WDG 0.1

Granules 0.1

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 80

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);

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).
Page 15 of 27

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 A-2: 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

Granular formulations 0.027

DE Dermal exposure (mg) Calculated

SAH

Typical surface area of one hand (cm2), children 1 < 

2 years old 150

AR Application rate

(mass active ingredient per unit area) [input]

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

BW Body Weight

(kg) Children 1 < 2 years old 11

Post-application Object-to-Mouth Exposure Algorithm– Physical Activities on Turf

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

in SHEDS-Multimedia):

E = [OR* CF1 * SAMO * (ET * N_Replen) * (1- (1- SEO)

(Freq_OtM/N_Replen))]

where:

E = exposure (mg/day);

OR = chemical residue loading on the object on day “t” (ug/cm2);

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

SAMO = area of the object surface that is mouthed (cm2/event);
Page 16 of 27

ET = exposure time (hr/day);

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

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

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

and

OR = AR * FO * CF2 * CF3

where:

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

AR = application rate (lbs ai/ft2or lb ai/acre);

FO = fraction of residue available on the object (unitless);

CF2 = weight unit conversion factor (4.54 x 108μg/lb); and

CF3 = area unit conversion factor (1.08 x 10-3ft2/cm2or 2.47 x 10-8acre/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 A-3: Turf (Physical Activities) – Inputs for Residential Post-application Object-to-Mouth Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

AR Application rate (to turf)

(mass active ingredient per unit area) [input]

FO Fraction of AR as OR following application 10.01

SAMO

Surface area of object mouthed 

(cm2/event) 10

N_Replen Replenishment intervals per hour (intervals/hour) 4

SEO

Saliva extraction factor

(fraction) 0.48

ET Exposure time 

(hours per day) 1.5

Freq_OtM Object-to-mouth events per hour (events/hr) 8.8

BW Body Weight (kg) Children 1 < 2 years old 11

1 This SOP assumes that all of the residue on the turf could be transferred to the object (e.g., object residue is 

equal to turf transferable residue).

Post-application Incidental Soil Ingestion Exposure Algorithm– Physical Activities on Turf

Exposure from incidental soil ingestion is calculated as follows:
Page 17 of 27

E = SRt * SIgR * CF1

where:

E = exposure (mg/day);

SRt = soil residue on day "t" (μg/g);

SIgR = ingestion rate of soil (mg/day); and

CF1 = weight unit conversion factor (1 x 10-6g/μg).

and

SRt = AR * FS * (1-FD)

t

* CF2 * CF3 * CF4

where:

SRt = soil residue on day "t" (μg/g);

AR = application rate (lbs ai/ft2or lb ai/acre);

FS = fraction of ai available in uppermost cm of soil (fraction/cm);

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 108μg/lb);

CF3 = area unit conversion factor (1.08 x 10-3ft2/cm2 or 2.47 x 10-8acre/cm2); and

CF4 = soil volume to weight unit conversion factor (0.67 cm3/g soil).

Dose, normalized to body weight, are calculated as:

BW

E

D

where:

D = dose (mg/kg-day);

E = exposure (mg/day); and

BW = body weight (kg).

Table A-4: Turf (Physical Activities) – Inputs for Residential Post-application Incidental Soil Ingestion 

Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

AR Application rate

(mass active ingredient per unit area) [input]

FS Fraction of AR available in uppermost 1 cm of soil

(unitless) 1

FD

Daily residue dissipation

(fraction) 0.1

SIgR Soil ingestion rate (mg/day) 50

BW Body weight (kg) Children 1 < 2 years old 11
Page 18 of 27

2.2 Turf/Mowing

Post-application Dermal Exposure Algorithm – Mowing

Exposure resulting from contacting previously treated turf while mowing is calculated as 

follows:

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).

and

TTRt = AR * FAR * (1-FD)

t

* CF2 * CF3

where:

TTRt = turf transferable residue on day "t" (μg/cm2);

AR = application rate (lbs ai/ft2or lb ai/acre);

FAR = fraction of ai retained on turf (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 108μg/lb); and

CF3 = area unit conversion factor (1.08 x 10-3ft2/cm2or 2.47 x 10-8acre/cm2).

Absorbed dose, normalized to body weight, 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 A-5: Turf (Mowing) – Inputs for Residential Post-application Dermal Exposure 

Algorithm Notation Exposure Factor

(units) Point Estimate(s)

AR Application rate

mass active ingredient per unit area [input]

FAR Fraction of AR as L/WP/WDG 0.01
Page 19 of 27

Table A-5: Turf (Mowing) – Inputs for Residential Post-application Dermal Exposure 

TTR following 

application Granules 0.002

FD

Daily residue 

dissipation

L/WP/WDG 0.1

Granules 0.1

TC Transfer Coefficient

(cm2/hr)

Adult 5,500

Children 11 < 16 years 

old 4,500

ET Exposure time 

(hours per day) 1

BW Body Weight 

(kg)

Adults 80

Children 11 < 16 years 

old 57

L/WP/WDG = liquid/wettable powder/water dispersible granule

2.3 Turf/Golfing

Post-application Dermal Exposure Algorithm – Golfing

Exposure resulting from contacting previously treated turf while golfing is calculated as follows:

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).

and

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 retained on turf (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 108μg/lb); and

CF3 = area unit conversion factor (1.08 x 10-3ft2/cm2or 2.47 x 10-8acre/cm2).

Absorbed dose, normalized to body weight, is calculated as:
Page 20 of 27

BW

E AF D*

where:

D = dose (mg/kg-day);

E = exposure (mg/day); 

AF = absorption factor (dermal); and

BW = body weight (kg).

Table A-6: Turf (Golfing) – Inputs for Residential Post-application Dermal Exposure 

Algorithm 

Notation

Exposure Factor

(units)

Point Estimate(s)

AR Application rate

(mass active ingredient per unit area)

[input]

F Fraction of AR as TTR 

following application

L/WP/WDG 0.01

Granules 0.002

FD Daily residue dissipation L/WP/WDG 0.1

Granules 0.1

TC Transfer Coefficient

(cm2/hr)

Adult 5,300

Children 11 < 16 years old 4,400

Children 6 < 11 years old 2,900

ET Exposure time

(hours per day)

Pesticides used on greens, tees, 

and fairways 

4

Pesticides used only on greens 

and tees

1

BW Body Weight

(kg)

Adults 80

Children 11 < 16 years old 57

Children 6 < 11 years old 32

NA = not applicable

L/WP/WDG = liquid/wettable powder/water dispersible granule

2.4 Indoor Environments

Exposure to pesticide vapors 

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

surface-directed sprays:

where:

E = exposure (mg/day);

IR = inhalation rate (m3/hr);

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

Vroom = volume of room (m3);

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

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

ET = exposure time (hr).
Page 21 of 27

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

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

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

ingredient applied can be calculated using the following formula:

where:

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

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

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

CF1 = conversion factor (4.54x105 mg/lb).

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

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

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

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

evaporate (EvapT): 

where:

EvapT = evaporation time (sec); and

Csat = saturation concentration (mg/m3).

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

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

where:

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

CF1 = conversion factor (sec/hr), and

EvapT = evaporation time (sec).

**Saturation concentration verification**

In the vapor emission assessment, post-application inhalation exposure occurs from the release 

of vapors following a surface treatment indoors. The concentration of pesticide in the air is 

modeled over time to calculate exposure. The maximum concentration allowed in the air 

should be the saturation concentration, calculated as a function of the pesticide’s molecular 

weight and vapor pressure. The equation used to model the air concentration is not bound 
Page 22 of 27

by the saturation concentration; therefore, the reviewer must perform a check to make 

sure the exposures being calculated are valid. 

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

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

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

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

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

MCsat should be compared to Mlabel. 

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

concentration. Use MCsat in the exposure calculation. 

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

concentration. Use Mlabel in the exposure calculation. 

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

body weight is calculated as:

where:

D = dose (mg/kg-day);

E = exposure (mg/day);

AF = absorption factor (inhalation); and

BW = body weight (kg).

Table A-7: Indoor Environments – Inputs for Residential Post-application Inhalation Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

Generic Variables Used in Calculating Post-application Inhalation Exposure

IR Inhalation rate 

(m3/hour)

Adult 0.64

Children 1 < 2 years old 0.33

ACH Air changes per hour 

(hr-1)

0.45

BW Body weight

(kg)

Adult 80

Children 1 < 2 years old 11

Vroom

Volume of room 

(m3)

33
Page 23 of 27

Table A-7: Indoor Environments – Inputs for Residential Post-application Inhalation Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

Variables Specific to Post-application Inhalation Exposure to Pesticide Aerosols

Co

Initial air concentration

(mg/m3)

Calculated; concentration at 

time “0”

AR Application rate

(lb ai/ ft3)

[input]

A.I. Percent ai in product

(%) [input]

Vproduct

Volume of product

(mL) [input]

Dproduct

Product density

(g/mL)

Water-based products 1

Solvent-based products 0.8

ET Exposure time 

(hr/day) 2

Variables Specific to Post-application Inhalation Exposure to Pesticide Vapors

Csat

Saturation concentration

(mg/m3)

Calculated

VP Vapor pressure 

(mmHg) [input]

MW Molecular weight 

(g/mol) [input]

R

Gas constant 

(L-atm/mol-K) 0.0821 

T

Temperature of the air

(kelvin, K) 298

Mlabel

Mass of active ingredient applied 

(mg) [input]

K First order decay rate Calculated

ET Exposure time 

(hr/day)

Adult 16

Children 1 < 2 years old 18

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

The algorithm to calculate exposure is as follows:

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:
Page 24 of 27

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:

where:

D = dose (mg/kg-day);

E = exposure (mg/day);

AF = absorption factor; and

BW = body weight (kg).

Table A-8: 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)

(1) Chemical-specific transferable 

residue data OR

(2) Estimated: DepR * Fai

DepR Deposited residue

( g/cm2)

(1) Chemical-specific residue 

deposition data,

(2) Estimated based on application 

rate, or 

(3) Estimated based on default 

residue related to type of application

Fai

Fraction of DepR as TR 

following application

Carpets 0.06

Hard surfaces 0.08

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
Page 25 of 27

Post-application Hand-to-Mouth Exposure Algorithm

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

SHEDS-Multimedia):

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

where:

HR = hand residue loading (mg/cm2);

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

study (unitless);

DE = dermal exposure (mg); and

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

and

Dose, normalized to body weight, is calculated as:

where:

D = dose (mg/kg-day);

E = exposure (mg/day); and

BW = body weight (kg).
Page 26 of 27

Table A-9: Indoor Environments – Inputs for Residential Post-application Hand-to-Mouth Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

Faihands

Fraction of ai on hands from jazzercise study

(unitless) 0.15

DE

Dermal exposure calculated in Section Error! Reference source not 

ound. of the 2012 Residential SOPs

(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) [input]

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):

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).
Page 27 of 27

and

where:

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

DepR = deposited residue (μg/cm2); and

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

and

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

where:

D = dose (mg/kg-day);

E = exposure (mg/day); and

BW = body weight (kg).

Table A-10: Indoor Environments – Inputs for Residential Post-application Object-to-Mouth Exposure

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

AR Application rate

(mass active ingredient per unit area) [input]

FO

Fraction of residue 

transferred to an object

Carpets 0.06

Hard surfaces 0.08

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