Date: 

Subject: 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

02-DEC-2014 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

Bentazon. Occupational and Residential Exposure and Risk Assessment for 

Registration Review. 

PC Code: 275200, 103901 

Decision Nos.: 486719 

Petition No.: N/ A 

DP Barcode: 0418591 

Registration Nos.: N/ A 

Regulatory Action: Registration Review Risk Assessment 

Risk Assessment Type: Single Case No.: 0182 

Chemical/ Aggregate 

TXRNo.: NA CAS No.: 50723-80-3, 25057-89-0 

MRIDNo.: NA 40 CFR: §180.355 

From: 

Through: 

To: 

Introduction 

Kelly M. Lowe, Environmental Scientist Y C'~ Risk Assessment Branch 1 (RAB 1) 

Health Effects Division (HED; 7509P) 

Charles W. Smith III, Branch Chief C c.)~ §)-

HED I RABl (7509P) 

and 

Casst 

Shal~ L. M 

Walls, 

Shelat, 

Reviewer 

Re':'iewer 

~ 

~~ 

;(. 4)~ 

Exposure Science Advisory Committee (ExpoSAC) I HED 

Carolyn Schroeder 

Pesticide Reevaluation Division (7509P) 

As part of Registration Review, the Pesticide Re-evaluation Division (PRD) of OPP has 

requested that HED evaluate the hazard and exposure data and conduct occupational and 

residential exposure assessments, as needed, to estimate the risk to human health that will result 

from the currently registered uses of pesticides. This memorandum serves as HED's 

Registration Review risk asses.sment of the occupational and residential handler and postapplication exposure and risk from the currently registered uses of bentazon. 

Page I of26 
It is HED policy to use the best available data to assess exposure. Several sources of generic 

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

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

Handler Exposure Task Force (AHETF) database; the Outdoor Residential Exposure Task Force 

(ORETF) database; and the Agricultural Reentry Task Force (ARTF) database. Some ofthese 

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

Fungicide, and Rodenticide Act (FIFRA). 

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

(ExpoSAC) on 25-SEP-2014. 

Page 2 of26 
Page 3 of 26

Table of Contents

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

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

2.1 Summary of Risk Estimates............................................................................................. 5

2.2 Label Recommendations.................................................................................................. 6

2.3 Data Deficiencies and Requirements ............................................................................... 6

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

4.0 Exposure and Use Profile..................................................................................................... 8

5.0 Residential Exposure and Risk Estimates.......................................................................... 11

5.1 Residential Handler Exposure/Risk Estimates............................................................... 11

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

5.3 Residential Risk Estimates for Use in Aggregate Assessment ...................................... 13

5.4 Spray Drift...................................................................................................................... 14

5.5 Residential Bystander Post-Application Inhalation Exposure ....................................... 15

6.0 Occupational Exposure and Risk Estimates ...................................................................... 15

6.1 Occupational Handler Exposure/Risk Estimates............................................................ 15

6.2 Occupational Post-application Exposure/Risk Estimates .............................................. 19

6.2.1 Occupational Post-application Inhalation Exposure/Risk Estimates...................... 19

6.2.2 Occupational Post-application Dermal Exposure/Risk Estimates.......................... 20

Appendix A. Summary of Occupational and Residential Non-cancer Algorithms..................... 21
Page 4 of 26

1.0 Executive Summary

Sodium bentazon (herein referred to as bentazon) is a selective, contact, early post-emergent 

herbicide used to control a variety of broadleaf weeds and sedges. This document assesses 

exposures and risk estimates from the registered uses of bentazon for Registration Review. 

Exposure and Use Profile

There are 11 end-use product labels and 4 special local needs (SLNs) registered with bentazon as 

the active ingredient (ai). All products are liquid formulations. Bentazon is currently registered 

for use on various agricultural crops, non-bearing food crops, non-cropland sites, roadsides, 

rights-of-way, nursery stock, ornamentals, and turf (including athletic fields, 

commercial/residential settings, golf courses (not greens), recreational areas, and sod farms). 

Most of the uses are foliar and are applied via aerial, groundboom, or handheld equipment. The 

maximum application rate supported by the registrants for any use site is 1.5 lb ai/A; however, 

most use sites have a maximum single application rate of 1 lb ai/A (or 0.023 lb ai/gal). Based on 

the registered use patterns, it has been determined that the potential exposure scenarios that will 

need to be assessed include short- and intermediate-term occupational and residential exposures 

(handler and post-application). 

Hazard Profile

The incidental oral and inhalation points of departure (PODs) are based on a study that examined 

the reproduction and fertility effects in the rat, where decreased absolute pup body weights 

during lactation were observed at 62 mg/kg/day. A no-observed-adverse-effect-level (NOAEL) 

was identified at 15 mg/kg/day. In the 28-day dermal toxicity study in rats, no dermal or 

systemic toxicity was seen up to the limit dose (1,000 mg/kg/day). In addition, bentazon exhibits 

low dermal absorption (1-2%); therefore, a dermal exposure assessment is not required for 

bentazon. Bentazon has been classified as a Group “E” chemical (evidence of noncarcinogenicity for humans) based upon lack of evidence of carcinogenicity in rats and mice 

(TXR 010787, J. Rowe, 1/14/92). Therefore, a cancer exposure and risk assessment is not 

required.

The level of concern (LOC) for both occupational and non-occupational risk is margins of 

exposure (MOEs) less than 100. For the non-cancer risk assessment, since no inhalation 

absorption data are available, toxicity by the inhalation route is considered to be equivalent to the 

estimated toxicity by the oral route of exposure. The acute toxicity data for bentazon show that 

this chemical has low acute toxicity by the oral, inhalation, and dermal routes of exposure 

(Toxicity Categories III and IV). It is moderately irritating to the eye (Toxicity Category II) and 

slightly irritating to the skin (Toxicity Category IV). It is also a dermal sensitizer.

Residential Exposure and Risk

There is the potential for residential exposure from the registered uses on ornamentals and turf. 

These uses have been assessed using the most up-to-date exposure policies and data available in 

the 2012 Residential SOPs. Since a dermal hazard was not identified, a quantitative dermal 

assessment was not conducted for the residential uses of bentazon. The inhalation exposure risk 

estimates for residential handlers are not of concern (i.e., MOEs ≥ the LOC of 100) at baseline 

for all scenarios. All residential post-application risk estimates are also not of concern (i.e., 
Page 5 of 26

MOEs ≥ the LOC of 100). A quantitative spray drift assessment for bentazon is not required 

since the turf post-application MOEs are protective for any potential exposures related to spray 

drift for bentazon.

Occupational Exposure and Risk

There is the potential for occupational exposure from the registered uses of bentazon. These uses 

have been assessed using the most up-to-date exposure policies and data available. Since no 

dermal hazard was identified for bentazon, a quantitative dermal assessment was not conducted 

for the occupational uses of bentazon. The occupational handler exposure and risk estimates 

indicate that the short- and intermediate-term inhalation MOEs are not of concern to HED (i.e., 

MOE > the LOC of 100). Occupational post-application dermal exposure and risk estimates 

were not assessed since a dermal hazard was not identified. In this case, the restricted entry 

interval (REI) is based on the acute toxicity of bentazon technical material, which would require 

a 24-hour REI under 40 CFR 156.208 (c) (2). 

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

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

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

post-application inhalation exposure assessment for bentazon.

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 PHED 1.1, the AHETF database, and the ARTF database are (1) subject to ethics review 

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

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

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

can be found at the Agency website1. 

2.0 Risk Assessment Conclusions and Recommendations

2.1 Summary of Risk Estimates

There are no occupational or residential risk estimates of concern for the registered uses of

bentazon. 

 The occupational handler exposure and risk estimates indicate that the short- and 

intermediate-term inhalation combined MOEs are not of concern to HED (i.e., MOE >

100); all MOEs ≥ 3,000. 

 The inhalation exposure risk estimates for residential handlers are not of concern (i.e., 

MOEs ≥ 100) at baseline for all scenarios; all MOEs ≥ 75,000. 

 All residential post-application risk estimates are not of concern (i.e., MOEs ≥ 100); all 

MOEs ≥ 1000 for children.

 

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

http://www.epa.gov/pesticides/science/post-app-exposure-data.html
Page 6 of 26

2.2 Label Recommendations 

There are no label recommendations.

2.3 Data Deficiencies and Requirements

Dislodgeable Foliar Residue (DFR): In accordance with the updated Part 158 data requirements 

(2007), one or more DFR studies are required when a pesticide has residential or occupational 

uses that could result in post-application dermal exposure. Because there is no hazard via the 

dermal route of exposure, a non-cancer dermal post-application risk assessment was not 

performed for bentazon. Therefore, DFR studies are not needed for bentazon at this time. If the 

PODs change, the need for DFR studies may be reevaluated in the future to refine the postapplication assessment. 

Turf Transferable Residue (TTR): In accordance with 40CFR158, 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. In the absence of chemical-specific TTR 

data, EPA uses default values. The 2012 Standard Operating Procedures for Residential 

Pesticide Exposure Assessment includes an analysis of all TTR data, available at the time, which

resulted in the selection of revised liquid and granular default values for the fraction of the 

application rate available for transfer after a turf application (FAR). These values are based on an 

analysis of 59 TTR studies performed with the Modified California Roller Method (36 studies 

using liquids, 11 studies using wettable powders/water dispersible granules, and 12 studies using 

granules). The liquid results (N=131) indicate a range of FAR values from 0.0005% to 6.1% and 

the granular results (N=37) indicate a range of 0.00064% to 0.69%. In both the liquid and 

granular data, a large range of transferability is observed and this variability can potentially be 

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

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

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

TTR data for a single chemical. HED selected 1% and 0.2% as high-end default values for 

liquid and granular products, respectively. Because TTR data are not available for bentazon, 

EPA is using the default value of [appropriate value for liquid or granular product]. Although 

there may be a small degree of uncertainty in the use of the default TTR value for bentazon (i.e., 

there is a small chance that the FAR value may exceed the applicable default value), it is likely 

that the health-protective aspects of EPA’s residential post-application turf assessment 

methodology will more than compensate for this potential uncertainty (i.e., the methodology is 

likely to overestimate exposure by a factor greater than the highest measured FAR values exceed 

the defaults ). For example, when assessing residential post-application turf exposure, EPA 

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

day of the assessed exposure duration (i.e., EPA assumes that no dissipation or degradation 

occurs, it doesn’t rain, the grass is not mowed, etc); individuals perform the same postapplication activities performed in the turf transfer coefficient study day after day (e.g., 

tumbling, playing on turf with toys, etc.); and individuals engage in these post-application 

activities for a high-end amount of time every day that is represented by data reflecting time 

children spend outdoors and not specifically engaged in activities on turf, when in actuality 
Page 7 of 26

children do not spend all of their outdoor time on turf and high-end levels of activity will not 

occur every day.

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

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

exposure is not being underestimated. 

Since the estimated post-application exposure to residential turf using default TTR values for 

bentazon is minimal in comparison to the level of concern (i.e., the calculated MOE is greater 

than 10 times higher than the level of concern, MOE = 1000 compared to the LOC of 100); EPA 

is waiving the 40CFR TTR data requirement. In this instance, it is unlikely that chemicalspecific TTR data would be needed to further refine exposure assessments or would add 

appreciably to our general understanding of the availability of turf transferable pesticide 

residues.

3.0 Hazard Characterization

Bentazon is a benzothiadiazinone contact herbicide that is manufactured by BASF Corporation. 

The acute toxicity data for bentazon show that this chemical has low acute toxicity by the oral, 

inhalation, and dermal routes of exposure (Toxicity Categories III and IV). It is moderately 

irritating to the eye (Toxicity Category II) and slightly irritating to the skin (Toxicity Category 

III). It is also a dermal sensitizer.

The Hazard and Science Policy Council (HASPOC) met on September 11, 2014 (TXR 0057054) 

to discuss the need for a subchronic inhalation toxicity study for bentazon. Based on a weight of 

evidence approach, the HASPOC concluded that a subchronic inhalation toxicity study is not 

needed for bentazon at this time for the following reasons: 1) the well characterized hazard 

profile of bentazon which considered the chemical’s metabolic and toxicokinetic, and acute 

inhalation toxicity profiles; 2) the physiochemical properties of bentazon which were expected to 

result in negligible inhalation exposure; and 3) the predicted MOEs are higher than the agency’s 

levels of concern for residential and occupational exposure.

The incidental oral and inhalation PODs are based on a study that examined the reproduction and 

fertility effects in the rat, where decreased absolute pup body weights during lactation were 

observed at 62 mg/kg/day. A NOAEL was identified at 15 mg/kg/day. In the 28-day dermal 

toxicity study in rats, no dermal or systemic toxicity was seen up to the limit dose (1,000 

mg/kg/day). In addition, bentazon exhibits low dermal absorption (1-2%); therefore, a dermal 

non-cancer exposure assessment is not required for bentazon. Bentazon has been classified as a 

Group “E” chemical (evidence of non-carcinogenicity for humans) based upon lack of evidence 

of carcinogenicity in rats and mice (TXR 010787, J. Rowe, 1/14/92). Therefore, a cancer 

exposure and risk assessment is not required.

The Agency’s LOC for risks (i.e., target level for MOE) is defined by the uncertainty factors that 

are applied to the assessment. The Agency applies a factor of 10X to account for interspecies 

extrapolation to humans from the animal test species and another factor of 10X to account for

intra-species sensitivity. The total uncertainty factor that has been applied to occupational and 
Page 8 of 26

residential risk assessments is 100 for short- and intermediate-term incidental oral and inhalation 

exposures. 

Table 3.1. Summary of Toxicological Doses and Endpoints for Bentazon for Use in Human Health Risk 

Assessments

Exposure/ 

Scenario

Point of 

Departure

(POD)

Uncertainty/FQP

A Safety Factors

RfD, PAD, 

Level of 

Concern for 

Risk 

Assessment

Study and Toxicological Effects

Incidental 

Oral Short-

(1-30 days) 

and 

Intermediate –

Term (1-6 

months)

NOAEL= 15 

mg/kg/day

UFA= 10x

UFH= 10x

FQPA SF= 1x

Residential 

LOC for 

MOE = 100

Reproduction and fertility effects - Rat

Offspring LOAEL = 62 mg/kg/day based 

on decreased absolute pup body weights 

during lactation.

Dermal Short-

(1-30 days) 

and 

IntermediateTerm (1-6 

months)

Based upon a lack of dermal toxicity in the 21-day dermal study, and the low absorption values 

for bentazon (1-2%), a dermal risk assessment is not required.

Inhalation 

Short- (1-30

days) and 

IntermediateTerm (1-6 

months)

NOAEL= 15 

mg/kg/day

UFA= 10x

UFH=10x

FQPA SF= 1x

Residential 

LOC for 

MOE = 100

Reproduction and fertility effects - Rat

Offspring LOAEL = 62 mg/kg/day based 

on decreased absolute pup body weights 

during lactation.

Cancer (oral, 

dermal, 

inhalation)

Classification: Group “E” chemical (evidence of non-carcinogenicity for humans) based upon 

lack of evidence of carcinogenicity in rats and mice (TXR 010787, J. Rowe, 1/14/92). A cancer 

exposure and risk assessment is not required.

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

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

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

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

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

Absorption: For the non-cancer risk assessment, inhalation exposure is assumed to be equivalent 

to oral absorption. 

Body Weight: The inhalation PODs are not based on developmental and/or fetal effects; 

therefore, the body weight appropriate for inhalation assessments is 80 kg.

4.0 Exposure and Use Profile 

There are 11 end-use product labels, and 4 SLNs, registered with bentazon as the active 

ingredient. All products are liquid formulations. The labeled use sites include various 

agricultural crops, non-bearing food crops, non-cropland sites, roadsides, rights-of-way, nursery 

stock, ornamentals, and turf (including athletic fields, commercial/residential settings, golf 

courses (not greens), recreational areas, and sod farms). Most of the uses are foliar and are 

applied via aerial, groundboom, or handheld equipment. The maximum application rate 
Page 9 of 26

supported by the registrants for any use site is 1.5 lb ai/A; however, most use sites have a 

maximum single application rate of 1 lb ai/A (or 0.023 lb ai/gal). 

Based on the registered use patterns, it has been determined that the potential exposure scenarios 

that will need to be assessed include short- and intermediate-term occupational and residential 

exposures (handler and post-application). A summary of the current use pattern is included in 

Table 4.1. 

Table 4.1. Summary of Proposed Directions for Use of Bentazon.

Crop/Use Site

Application 

Timing and 

Type of 

Application

Registered 

Formulations

Maximum 

Application 

Rate

Limitation and Restrictions1 Personal 

Protective 

Equipment 

(PPE) 

Max # 

apps/year

Min RTI 

(days)

REI 

(hours)

PHI 

(days)

Alfalfa (grown for 

seed production)

Prior to flower 

bud formation

Aerial, 

Groundboom

Liquid

1.5 lb ai/A

2

5

48

NA

Longsleeved 

shirt, long 

pants, 

gloves, 

shoes and 

socks; 

some 

labels 

require 

protective 

eyewear

Beans (dry and 

succulent)

Early 

Postemergence

Aerial, 

Groundboom

1.5 lb ai/A NA 30

Clover (grown for 

seed)

Early 

postemergence

Aerial, 

Groundboom

1.0 lb ai/A 5 36

Corn

Early 

postemergence

Aerial, 

Groundboom

1.5 lb ai/A NA 12

Non-bearing food 

crops (almonds, 

apples, apricots, 

avocados, 

blackberries, 

blueberries, cherries, 

crabapples, dates, figs, 

grapes, grapefruit, 

lemons, limes, 

macadamias, 

nectarines, olives, 

oranges, peaches, 

pears, pecans, 

pistachios, plums, 

pomegranates, prunes, 

raspberries, tangelos, 

tangerines, walnuts)

Postemergence 

directed 

Groundboom

1.0 lb ai/A NA NA
Page 10 of 26

Table 4.1. Summary of Proposed Directions for Use of Bentazon.

Crop/Use Site

Application 

Timing and 

Type of 

Application

Registered 

Formulations

Maximum 

Application 

Rate

Limitation and Restrictions1 Personal 

Protective 

Equipment 

(PPE) 

Max # 

apps/year

Min RTI 

(days)

REI 

(hours)

PHI 

(days)

Non-cropland sites, 

Roadsides, Rights-ofway

Postemergence 

Groundboom, 

Handheld

1 lb ai/A; 

0.023 lb 

ai/gal

7 NA

Nursery stock

Postemergence 

Groundboom, 

Handheld

1 lb ai/A; 

0.023 lb 

ai/gal

7 NA

Ornamentals 

Postemergence 

Groundboom, 

Handheld

1 lb ai/A; 

0.023 lb 

ai/gal

7 NA

Peanuts

Range from 

cracking 

through 

pegging

Aerial, 

Groundboom

1.5 lb ai/A NA 50

Peas (dry and 

succulent)

After 3 pairs of 

leaves are 

present, do not 

apply when 

peas are in 

bloom

Aerial, 

Groundboom

1.5 lb ai/A NA

dry peas 

= 30, 

succulent 

peas = 

10

Peppermint/ 

Spearmint

Postemergence

Aerial, 

Groundboom

1.5 lb ai/A NA 20

Rice

Postemergence

Aerial, 

Groundboom

1.0 lb ai/A NA NA

Sorghum

Postemergence, 

but not during 

crop heading or 

blooming

Aerial, 

Groundboom

1.0 lb ai/A NA 12

Soybeans

Postemergence

Aerial, 

Groundboom

1.5 lb ai/A NA 30
Page 11 of 26

Table 4.1. Summary of Proposed Directions for Use of Bentazon.

Crop/Use Site

Application 

Timing and 

Type of 

Application

Registered 

Formulations

Maximum 

Application 

Rate

Limitation and Restrictions1 Personal 

Protective 

Equipment 

(PPE) 

Max # 

apps/year

Min RTI 

(days)

REI 

(hours)

PHI 

(days)

Turf (athletic fields, 

commercial/residential 

settings, golf courses 

(not greens), 

recreational areas, sod 

farms)

Postemergence 

Groundboom, 

Handheld

1 lb ai/A; 

0.023 lb 

ai/gal

21 

(perennial 

ryegrass)

NA

1. RTI = retreatment interval; REI = restricted entry interval; PHI = Preharvest interval

5.0 Residential Exposure and Risk Estimates

There is the potential for residential handler and post-application exposure from the registered 

uses on turf and ornamentals.

 

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.

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

following scenarios: 

(1) mixing/loading/applying liquids to turf and gardens/trees with manually-pressurized 

handwand, 

(2) mixing/loading/applying liquids to turf and gardens/trees with hose-end sprayer, and

(3) mixing/loading/applying liquids turf and gardens/trees with backpack.

Residential Handler Exposure Data and Assumptions

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

handler risk assessments. Each assumption and factor is detailed below.

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

Unit Exposures and Area Treated or Amount Handled: Unit exposure values and estimates for 

area treated or amount handled were taken from HED’s 2012 Residential SOPs2. 

Exposure Duration: Residential handler exposure is expected to be short-term in duration. 

Intermediate-term exposures are not likely because of the intermittent nature of applications by 

homeowners.

 

2 Available: http://www.epa.gov/pesticides/science/residential-exposure-sop.html
Page 12 of 26

Residential Handler Non-Cancer Exposure and Risk Estimate Equations

The algorithms used to estimate exposure and dose for residential handlers can be found in 

Appendix A and/or the 2012 Residential SOPs3.

Summary of Residential Handler Non-Cancer Exposure and Risk Estimates

Table 5.1.1 provides a summary of the residential handler exposures and risk estimates for 

bentazon. Since there is no dermal hazard, a quantitative residential handler dermal assessment 

has not been conducted. The inhalation exposure risk estimates for residential handlers are not 

of concern (i.e., MOEs ≥ 100) at baseline for all scenarios; all MOEs ≥ 75,000.

Table 5.1.1. Residential Handler Non-cancer Exposure and Risk Estimates for Bentazon.

Scenario Application 

Equipment/Method Application Rate1

Area Treated 

or Amount 

Handled 

Daily

Inhalation 

Unit 

Exposure 

(mg/lb ai)2

Inhalation 

Dose 

(mg/kg/day)3

Inhalation 

MOE4

Mixer/Loader/Applicator for Liquid Formulations

Gardens / Trees Manually-pressurized 

handwand 0.023 lb ai/gallon 5 gallons 0.018 0.000026 580,000 Lawns / Turf

Gardens / Trees Hose-end Sprayer 0.023 lb ai/gallon 11 gallons 0.0014 0.0000044 3,400,000

Lawns / Turf 1 lb ai/acre 0.5 acres 0.022 0.00014 110,000

Gardens / Trees Backpack 0.023 lb ai/gallon 5 gallons 0.14 0.0002 75,000 Lawns / Turf

1. Based on registered labels (see table 4.1).

2. Based on HED’s 2012 Residential SOPs (http://www.epa.gov/pesticides/science/residential-exposure-sop.html).

3. Inhalation Dose = Inhalation Unit Exposure (mg/lb ai) × Application Rate (lb ai/acre or gal) × Area Treated or Amount Handled (A/day or 

gallons/day) ÷ Body Weight (80 kg).

4. Inhalation MOE = Inhalation NOAEL (15 mg/kg/day) ÷ Inhalation Dose (mg/kg/day).

5.2 Residential Post-application Exposure/Risk Estimates

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

an environment that has been previously treated with bentazon. Since there is no dermal hazard 

identified for bentazon, a quantitative dermal post-application assessment has not been 

conducted. The quantitative exposure/risk assessment for residential post-application exposures 

is based on the following scenarios: 

 Physical activities on turf: children 1 to < 2 years old (incidental oral).

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

Appendix in the 2012 Residential SOPs4. 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.

Residential Post-application Exposure Data and Assumptions

 

3 Available: http://www.epa.gov/pesticides/science/residential-exposure-sop.html

4 Available: http://www.epa.gov/pesticides/science/residential-exposure-sop.html
Page 13 of 26

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

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

SOPs4.

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

Exposure Duration: Residential post-application exposure is expected to be short-term in 

duration. While multiple applications may be possible, it is anticipated that these applications 

will be intermittent in nature and dissipation due to rainfall/irrigation, grass growth, and grass 

mowing is expected. 

Residential Post-application Non-Cancer Exposure and Risk Equations

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

Appendix A and/or the 2012 Residential SOPs4.

Combining Exposure and Risk Estimates

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 would be overly-conservative because of the conservative nature of 

each individual assessment. Therefore, these scenarios have not been combined.

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

Table 5.2.1 provides a summary of the residential post-application exposures and risk estimates 

for bentazon. All risk estimates for post-application exposure are not of concern (i.e., MOEs ≥ 

100); all MOEs ≥ 1000 for children. 

Table 5.2.1. Short-Term Residential Post-application Exposure and Risk Estimates for Bentazon.

Lifestage Post-application Exposure Scenario Dose (mg/kg/day)1 MOEs2

Liquid formulation

Child 

1 to< 2 year old

Turf

Liquid formulation

1 lb ai/A

Hand to Mouth 0.0152 1,000

Object to Mouth 0.000456 32,000

Short- and Intermediate-term Incidental Soil Ingestion 0.000034 440,000

1 Dose (mg/kg/day) equations provided in Appendix A.

2 MOE = POD (Incidental oral = 15 mg/kg/day) ÷ Dose (mg/kg/day). LOC = 100.

5.3 Residential Risk Estimates for Use in Aggregate Assessment

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

assessment for bentazon.

 The recommended residential exposure for use in the adult short-term aggregate 

assessment reflects inhalation exposure from handler applications using a backpack 

sprayer.

 The recommended residential exposure for use in the children 1<2 years old short-term 

aggregate assessment reflects hand-to-mouth exposures from post-application exposure to 

turf applications.
Page 14 of 26

Table 5.3.1. Recommendations for the Residential Exposures for the Bentazon Aggregate Assessment.

Lifestage Exposure 

Scenario

Dose (mg/kg/day)1 MOE2

Dermal Inhalation Oral Total Dermal Inhalation Oral Total

Short-term

Adult

Handler 

application 

via 

backpack 

sprayer

NA 0.0002 NA 0.0002 NA 75,000 NA 75,000

Child 1 < 2 

year old

Hand-tomouth NA NA 0.0152 0.0152 NA NA 1,000 1,000

1 Dose = the highest dose for each applicable life stage of all residential scenarios assessed. Total = dermal + inhalation + incidental 

oral (where applicable).

2 MOE = the MOEs associated with the highest residential doses. 

5.4 Spray Drift

Off-target movement of pesticides can occur via many types of pathways and it is governed by a 

variety of factors. Sprays that are released and do not deposit in the application area end up offtarget and can lead to exposures to those it may directly contact. They can also deposit on 

surfaces where contact with residues can eventually lead to exposures (e.g., children playing on 

lawns where residues have deposited next to treated fields). The potential risk estimates from 

these residues can be calculated using drift modeling coupled with methods employed for 

residential risk assessments for turf products.

The approach to be used for quantitatively incorporating spray drift into risk assessment include 

assessing exposures for children (1 to <2 years old) and adults who have contact with turf where 

residues are assumed to have deposited via spray drift thus resulting in an exposure scenario. 

Aside from the predicted residues available for transfer, the routes of exposure and assessment 

methodology is analogous to how exposures to turf products are considered in risk assessment. 

Several bentazon products have existing labels for use on turf, thus it was considered whether the 

risk assessment for turf may be considered protective of any type of exposure resulting from 

spray drift. If the maximum application rate on crops adjusted by the amount of drift expected is 

less than or equal to existing turf application rates, the existing turf assessment is considered 

protective of spray drift exposure. The maximum single application rate registered for bentazon

is 1.5lb ai/A. The highest fraction of spray drift noted for any application method immediately 

adjacent to a treated field results in a deposition fraction of 0.265of the application rate. A 

quantitative spray drift assessment for bentazon is not required because the maximum application 

rate for a crop/target site multiplied by the adjustment factor for drift of 0.26 is less than the 

maximum direct spray residential turf application rate (1 lb ai/A)6for any bentazon products. 

The turf post-application MOEs are protective for any potential exposures related to spray drift 

for bentazon and have previously been discussed in Section 5.2. 

 

5 Tier 1 output from the aerial application using fine to medium spray quality based on AgDrift output files

6 1.5 lb ai/A x 0.26 = 0.39 ≤ 1 lb ai/A
Page 15 of 26

5.5 Residential Bystander Post-Application Inhalation Exposure

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, 2010 (http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The 

agency has evaluated the SAP report and has developed a Volatilization Screening Tool and a 

subsequent Volatilization Screening Analysis 

(http://www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2014-0219). During Registration 

Review, the agency will utilize this analysis to determine if data (i.e., flux studies, route-specific 

inhalation toxicological studies) or further analysis is required for bentazon.

6.0 Occupational Exposure and Risk Estimates

6.1 Occupational Handler Exposure/Risk Estimates

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

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

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

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

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

manner specific to each application event. 

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

following scenarios which cover all the registered and proposed uses of bentazon: 

 Mixing/loading liquids to support aerial applications,

 Mixing/loading liquids to support groundboom applications, 

 Applying sprays with aircraft,

 Applying sprays with groundboom equipment,

 Flagging to support aerial spray applications, 

 Mixing/loading/applying liquids via backpack,

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

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

Occupational Handler Exposure Data and Assumptions

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

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

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

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

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

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

(ORETF) database, or other registrant-submitted occupational exposure studies. Some of these 
Page 16 of 26

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

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

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

Exposure Surrogate Reference Table7”, 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 website8.

Area Treated or Amount Handled: The inputs for area treated were mostly based on information 

in ExpoSAC Policy 9.1. The following summarizes the inputs used for estimating handler 

exposures: 

 1200 acres for aerial application to high acreage crops

 350 acres for aerial application to typical acreage crops

 60 acres for aerial and groundboom applications to nurseries

 200 acres for ground application to high acreage crops

 80 acres for ground application to typical acreage crops

 80 acres for ground application to sod farms

 40 acres for ground application to golf courses and field ground ornamentals

 60 or 350 acres for flaggers

 5 acres or 40 gallons for backpack and manually-pressurized handwand applications

 5 acres or 1000 gallons for mechanically-pressurized handgun

 

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

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

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

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

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

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

commercial applicators who may apply a product over a period of weeks. 

For the registered use pattern, short- and intermediate-term exposures are anticipated for the 

following reasons: (1) up to two applications can be made anywhere from 5 to 21 days apart; and 

(2) commercial applicators may apply this product at various locations within a region over a 

period of weeks. The same exposure durations are anticipated for all registered bentazon uses, 

and it should be noted that the short- and intermediate-term PODs are the same; therefore, shortterm risk estimates are protective of longer-term exposures.

Mitigation/Personal Protective Equipment: Estimates of dermal and inhalation exposure were 

calculated for various levels of personal protective equipment (PPE). Results are presented for 

“baseline,” defined as a single layer of clothing consisting of a long sleeved shirt, long pants, 

shoes plus socks, no protective gloves, and no respirator, as well as baseline with various levels 

of PPE as necessary (e.g., gloves, respirator, etc). Most of the bentazon registered labels require 

 

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

8 Available: http://www.epa.gov/pesticides/science/handler-exposure-data.html
Page 17 of 26

handlers to wear a single layer of clothing (long sleeved shirt and long pants), gloves, shoes and 

socks, and some labels require protective eyewear. 

Occupational Handler Non-Cancer Exposure and Risk Estimate Equations

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

found in Appendix A.

Summary of Occupational Handler Non-Cancer Exposure and Risk Estimates

The occupational handler exposure and risk estimates indicate that the short- and intermediateterm inhalation combined MOEs are not of concern to HED (i.e., MOE > 100) at baseline (no 

respirator). MOEs are all greater than or equal to 3,000.

HED has no data to assess exposures to pilots using open cockpits. The only data available is for 

exposure to pilots in enclosed cockpits. Therefore, risks to pilots are assessed using the 

engineering control (enclosed cockpits) and baseline attire (long-sleeve shirt, long pants, shoes, 

and socks); per the Agency’s Worker Protection Standard stipulations for engineering controls, 

pilots are not required to wear protective gloves for the duration of the application. With this 

level of protection, there are no risk estimates of concern for applicators.

The Agency matches quantitative occupational exposure assessment with appropriate 

characterization of exposure potential. While HED presents quantitative risk estimates for human 

flaggers where appropriate, agricultural aviation has changed dramatically over the past two 

decades. According the 2012 National Agricultural Aviation Association (NAAA) survey of 

their membership, the use of GPS for swath guidance in agricultural aviation has grown steadily 

from the mid 1990’s. Over the same time period, the use of human flaggers for aerial pesticide 

applications has decreased steadily from ~15% in the late 1990’s to only 1% in the most recent 

(2012) NAAA survey. The Agency will continue to monitor all available information sources to 

best assess and characterize the exposure potential for human flaggers in agricultural aerial 

applications.

Table 6.1.1. Occupational Handler Non-Cancer Exposure and Risk Estimates for Bentazon.

Exposure 

Scenarios Crop / Target Category Application Rate1

Amount 

Handled / 

Area 

Treated2

Inhalation 

Unit 

Exposures 

(ug/lb ai)3

Inhalation 

Dose 

(mg/kg/day)4

Inhalation 

MOE5

Baseline 

(unless 

otherwise 

noted)

Baseline 

(unless 

otherwise 

noted)

Baseline 

(unless 

otherwise 

noted)

Mixer/Loader

Aerial 

application of 

liquid 

formulation

Peas, Peppermint, Spearmint 1.5 lb ai/acre

350 acres 0.219

0.00144 10,000

Clover, Non-bearing food crops (almonds, 

apples, apricots, avocados, blackberries, 

blueberries, cherries, crabapples, dates, figs, 

grapes, grapefruit, lemons, limes, 

macadamias, nectarines, olives, oranges, 

peaches, pears, pecans, pistachios, plums, 

pomegranates, prunes, raspberries, tangelos, 

tangerines, walnuts)

1 lb ai/acre 0.000959 16,000
Page 18 of 26

Table 6.1.1. Occupational Handler Non-Cancer Exposure and Risk Estimates for Bentazon.

Exposure 

Scenarios Crop / Target Category Application Rate1

Amount 

Handled / 

Area 

Treated2

Inhalation 

Unit 

Exposures 

(ug/lb ai)3

Inhalation 

Dose 

(mg/kg/day)4

Inhalation 

MOE5

Baseline 

(unless 

otherwise 

noted)

Baseline 

(unless 

otherwise 

noted)

Baseline 

(unless 

otherwise 

noted)

Corn, Peanuts, Beans, Soybeans 1.5 lb ai/acre 0.00493 3,000

Sorghum, Rice, Alfalfa 1 lb ai/acre 0.00329 4,600

Groundboom 

applications 

with liquid 

formulation

Golf course (fairways, tees, greens) 1 lb ai/acre 40 acres 0.00011 140,000

Nursery (ornamentals, vegetables, trees, 

container stock) 1 lb ai/acre 60 acres 0.000164 91,000

Sod 1 lb ai/acre

80 acres

0.000219 68,000

Peas, Peppermint, Spearmint 1.5 lb ai/acre 0.000329 46,000

Clover, Non-bearing food crops (almonds, 

apples, apricots, avocados, blackberries, 

blueberries, cherries, crabapples, dates, figs, 

grapes, grapefruit, lemons, limes, 

macadamias, nectarines, olives, oranges, 

peaches, pears, pecans, pistachios, plums, 

pomegranates, prunes, raspberries, tangelos, 

tangerines, walnuts)

1 lb ai/acre 0.000219 68,000

Corn, Peanuts, Beans, Soybeans 1.5 lb ai/acre 0.000821 18,000

Sorghum, Rice, Alfalfa 1 lb ai/acre 0.000548 27,000

Applicator

Aerial 

application of 

liquid 

formulation

Peas, Peppermint, Spearmint 1.5 lb ai/acre

350 acres 0.0049 

(EC)

0.0000321

(EC)

470,000

(EC)

Clover, Non-bearing food crops (almonds, 

apples, apricots, avocados, blackberries, 

blueberries, cherries, crabapples, dates, figs, 

grapes, grapefruit, lemons, limes, 

macadamias, nectarines, olives, oranges, 

peaches, pears, pecans, pistachios, plums, 

pomegranates, prunes, raspberries, tangelos, 

tangerines, walnuts)

1 lb ai/acre 0.0000215

(EC)

700,000

(EC)

Corn, Peanuts, Beans, Soybeans 1.5 lb ai/acre 0.00011

(EC)

140,000

(EC)

Sorghum, Rice, Alfalfa 1 lb ai/acre 0.0000735

(EC)

200,000

(EC)

Groundboom 

applications 

with liquid 

formulation

Golf course (fairways, tees, greens) 1 lb ai/acre 40 acres

0.34

0.00017 88,000

Nursery (ornamentals, vegetables, trees, 

container stock) 1 lb ai/acre 60 acres 0.000255 59,000

Sod 1 lb ai/acre

80 acres

0.00034 44,000

Peas, Peppermint, Spearmint 1.5 lb ai/acre 0.00051 29,000

Clover, Non-bearing food crops (almonds, 

apples, apricots, avocados, blackberries, 

blueberries, cherries, crabapples, dates, figs, 

grapes, grapefruit, lemons, limes, 

macadamias, nectarines, olives, oranges, 

peaches, pears, pecans, pistachios, plums, 

pomegranates, prunes, raspberries, tangelos, 

tangerines, walnuts)

1 lb ai/acre 0.00034 44,000

Corn, Peanuts, Beans, Soybeans 1.5 lb ai/acre 0.00128 12,000

Sorghum, Rice, Alfalfa 1 lb ai/acre 0.00085 18,000

Mechanically

-pressurized 

Handgun

Rights-of-way (e.g., utilities, railroad, 

roadways)

0.023 lb 

ai/gallon

1000 

gallons 3.9 0.00112 13,000
Page 19 of 26

Table 6.1.1. Occupational Handler Non-Cancer Exposure and Risk Estimates for Bentazon.

Exposure 

Scenarios Crop / Target Category Application Rate1

Amount 

Handled / 

Area 

Treated2

Inhalation 

Unit 

Exposures 

(ug/lb ai)3

Inhalation 

Dose 

(mg/kg/day)4

Inhalation 

MOE5

Baseline 

(unless 

otherwise 

noted)

Baseline 

(unless 

otherwise 

noted)

Baseline 

(unless 

otherwise 

noted)

Flagger

Aerial 

application of 

liquid 

formulation

Peas, Peppermint, Spearmint 1.5 lb ai/acre

350 acres 0.35

0.0023 6,500

Clover, Non-bearing food crops (almonds, 

apples, apricots, avocados, blackberries, 

blueberries, cherries, crabapples, dates, figs, 

grapes, grapefruit, lemons, limes, 

macadamias, nectarines, olives, oranges, 

peaches, pears, pecans, pistachios, plums, 

pomegranates, prunes, raspberries, tangelos, 

tangerines, walnuts)

1 lb ai/acre 0.00154 9,700

Corn, Peanuts, Beans, Soybeans 1.5 lb ai/acre 0.0023 6,500

Sorghum, Rice, Alfalfa 1 lb ai/acre 0.00154 9,700

Mixer/Loader/Applicator

Backpack

Rights-of-way (e.g., utilities, railroad, 

roadways)

0.023 lb 

ai/gallon 40 gallons

2.58 0.0000296 510,000 Landscaping, turf (lawns, athletic fields, 

parks, etc.)

Manuallypressurized 

Handwand

Landscaping, turf (lawns, athletic fields, 

parks, etc.) 30 0.000345 43,000

Mechanically

-pressurized 

Handgun

Golf course (fairways, tees, greens)

Landscaping, turf (lawns, athletic fields, 1 lb ai/acre 5 acres 1.9 0.000119 130,000

parks, etc.)

1 Based on registered and proposed labels.

2 Exposure Science Advisory Council Policy #9.1.

3 Based on the “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table” (March 2014); Level of mitigation: Baseline, EC = 

Eng. Controls.

4 Inhalation Dose = Inhalation Unit Exposure (μg/lb ai) × Conversion Factor (0.001 mg/μg) × Application Rate (lb ai/acre) × Area Treated 

(A/day) ÷ BW (80 kg).

5 Inhalation MOE = Inhalation NOAEL (15 mg/kg/day) ÷ Inhalation Dose (mg/kg/day).

6.2 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 reentry exposure). Such exposures may occur when workers enter previously treated areas to 

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

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

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

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

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

6.2.1 Occupational Post-application Inhalation Exposure/Risk Estimates
Page 20 of 26

There are multiple potential sources of post-application inhalation exposure to individuals 

performing post-application activities in previously treated fields. These potential sources 

include volatilization of pesticides and resuspension of dusts and/or particulates that contain 

pesticides. The agency sought expert advice and input on issues related to volatilization of 

pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel 

(SAP) in December 2009, and received the SAP’s final report on March 2, 2010 

(http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The agency has 

evaluated the SAP report and has developed a Volatilization Screening Tool and a subsequent 

Volatilization Screening Analysis (http://www.regulations.gov/#!docketDetail;D=EPA-HQOPP-2014-0219). During Registration Review, the agency will utilize this analysis to determine 

if data (i.e., flux studies, route-specific inhalation toxicological studies) or further analysis is 

required for bentazon.

In addition, the Agency is continuing to evaluate the available post-application inhalation 

exposure data generated by the Agricultural Reentry Task Force. Given these two efforts, the 

Agency will continue to identify the need for and, subsequently, the way to incorporate 

occupational post-application inhalation exposure into the agency's risk assessments.

Although a quantitative occupational post-application inhalation exposure assessment was not 

performed, an inhalation exposure assessment was performed for occupational/commercial 

handlers. Handler exposure resulting from application of pesticides outdoors is likely to result in 

higher exposure than post-application exposure. Therefore, it is expected that these handler 

inhalation exposure estimates would be protective of most occupational post-application 

inhalation exposure scenarios.

6.2.2 Occupational Post-application Dermal Exposure/Risk Estimates

A quantitative dermal post-application assessment was not conducted because a dermal hazard 

for bentazon has not been identified. 

Restricted Entry Interval

The REI specified on the proposed label is based on the acute toxicity of bentazon. Bentazon is 

classified as acute toxicity category III and IV for acute oral, acute dermal, and acute inhalation 

toxicity. It is classified as toxicity category II for eye irritation potential and category III for skin 

irritation potential. It is a dermal sensitizer. Under 40 CFR 156.208 (c) (2), ai’s classified as 

Acute II for acute dermal, eye irritation or primary skin irrigation are assigned a 24-hour REI. 

Therefore, the [156 subpart K] Worker Protection Statement interim REI of 24 hours is adequate 

to protect agricultural workers from post-application exposures to bentazon. 
Page 21 of 26

Appendix A. Summary of Occupational and Residential Non-cancer Algorithms

OCCUPATIONAL NON-CANCER HANDLER ALGORITHMS

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

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

where:

E = exposure (mg ai/day),

UE = unit exposure (μg ai/lb ai),

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

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

The daily doses are calculated using the following formula:

ADD= 

E * AF

BW

where:

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

E = exposure (mg ai/day),

AF = absorption factor (inhalation), and

BW = body weight (kg).

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

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

the daily dose of concern. The daily inhalation dose received by occupational handlers are 

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

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

MOE= 

POD

ADD

where:

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

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

ADD = average daily dose absorbed in a given scenario (mg ai/kg/day).
Page 22 of 26

RESIDENTIAL NON-CANCER HANDLER ALGORITHMS

Inhalation Handler Exposure Algorithm - Turf

Daily inhalation exposure (mg/day) for residential pesticide handlers, for a given formulationapplication method combination, is estimated by multiplying the formulation-application 

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).

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).

RESIDENTIAL NON-CANCER POST-APPLICATION ALGORITHMS

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).
Page 23 of 26

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 A-X: 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) See table 4.1

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
Page 24 of 26

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);

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 108 μg/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-X: 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) See table 4.1

FO Fraction of AR as OR following application 1 0.01
Page 25 of 26

Table A-X: Turf (Physical Activities) – Inputs for Residential Post-application Object-to-Mouth Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

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:

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 108 μg/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
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BW = body weight (kg).

Table A-X: 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) See table 4.1

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