Date: 

SUBJECT: 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

July 1, 2014 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

Dimethenamid-P (DMTA-P). Occupational and Residential Exposure 

Assessment for a Proposed New Use on Cotton Subgroup 20C. 

PC Code: 120051 

Decision No.: 482296 

Petition No.: 3F8197 

DP Barcode: 0418 11 7 

Registration No.: 7969-1 56 

Regulatory Action: Amended Section 3 Registration 

Risk Assessment Type: ORE Case No.: 7223 

TXR No.: Not Applicable 

MRID No.: 47901302 

CAS No.: 163515-14-8 

40 CFR: § 180.464 

From: 

Through: 

To: 

Introduction 

Ivan D. Nieves, hemi ~ /,) __:_.-.-

Health Effects Division (7509PUAss~sment Branch IV 

Health 

ElissaReaves,Chief 

Effects Division (7509P)/Risk ~anch 

c/"_ ~ IV 

and 

vO ~ -\tv ~c.~ Margarita Collantes, ExpoSAC Reviewer #1 \~ Q 1 

Alexandra LaMay, ExpoSAC Reviewer #2 ;j ':;2:!. J:f/t.-,/ 

Exposure Science Advisory Committee (ExpoSAC) /HEf) ? 

E. Kraft:JK. Davis (RM 25) 

Herbicide Branch 

Registration Division (7505P) 

The Registration Division (RD) requested that the Health Effects Division (HED) conduct an 

occupational exposure and risk assessment for the proposed new use of dimethenamid-P in/on 

Cotton. For purposes of performing an aggregate assessment, a revised residential exposure 

assessment is also provided for registered turf and garden uses. 

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 

Page I of36 
Handler Exposure Task Force (AHETF) database; the Outdoor Residential Exposure Task Force 

(ORETF) database; the Agricultural Reentry Task Force (ARTF) database; the Residential SOPs 

(Lawns/Turf and Garden/Trees), other registrant-submitted exposure monitoring studies (MRID 

47901302); published literature study, etc]. Some of these data are proprietary, and subject to 

the data protection provisions of the Federal Insecticide, Fungicide, and Rodenticide Act 

(FIFRA). 

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

(ExpoSAC) on 6/19/2014. 

Page 2 of36 
Page 3 of 36

Table of Contents

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

2.0 Data Deficiencies and Requirements................................................................................... 6

3.0 Hazard Characterization....................................................................................................... 6

4.0 Use Profile ........................................................................................................................... 9

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

5.1 Residential Handler Exposure/Risk Estimates............................................................... 10

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

5.3 Residential Risk Estimates for Use in Aggregate Assessment ...................................... 14

5.4 Spray Drift...................................................................................................................... 15

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

6.0 Occupational Exposure and Risk Estimates ...................................................................... 16

6.1 Occupational Handler Exposure/Risk Estimates............................................................ 16

6.2 Occupational Post-application Exposure/Risk Estimates .............................................. 20

6.2.1 Occupational Post-application Inhalation Exposure/Risk Estimates...................... 20

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

Appendix A. Summary of Occupational and Residential Non-cancer Algorithms..................... 24
Page 4 of 36

1.0 Executive Summary

The active ingredient (ai) S-dimethenamid [(S)-2-chloro-N-[( 1-methyl-2-methoxy)ethyl]-N-(2,4-

dimethyl-thien-3-yl) acetamide; common name dimethenamid-P is the herbicidally active isomer 

of R/S-dimethenamid. DMTA-P is a chloroacetamide herbicide (protein synthesis inhibitor) used 

for pre-emergent control or suppression of annual broadleaf and grass weeds in a variety of field 

and vegetable crops. BASF Corporation Crop Protection (hereafter referred to as BASF) is 

requesting an amendment to the Section 3 registration for Outlook® Herbicide (EPA 

Registration Number 7969-156), a 6.0 lb/gal emulsifiable concentrate (EC) formulation of

dimethenamid-P, to add preplant, preemergence and early postemergence broadcast applications 

to members of cottonseed subgroup 20C. 

Proposed Use Profile

Based on the application rate and label information, occupational exposure is expected to occur 

for short- and intermediate-term durations. Chronic exposure is not expected for the proposed 

use pattern. Potential routes of exposure include both dermal and inhalation. Preplant and 

preemergence applications may be made at up to 0.5 lb ai/A and early postemergence 

applications may be made at up to 1.0 lb ai/A. Sequential applications of a preplant or 

preemergence application followed by an early postemergence application at least 14-days after 

the initial application may be made at up to 1.5 lb ai/A/season. No preharvest interval (PHI) is 

specified but the last application may be made two weeks after the R1 initial bloom stage. The 

restricted entry interval for the proposed use is 12 hours. The proposed label requires baseline 

clothing plus chemical-resistant gloves, and protective eyewear as personal protective equipment 

(PPE). Applications for the proposed are expected to be made with an aircraft, groundboom 

truck, chemigation, and/or handheld equipment.

Non-occupational (residential) exposures are not anticipated from the proposed new use, 

although residential exposure is expected for currently registered products. The existing 

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

Residential SOPs1along with policy changes for body weight assumptions. 

Hazard Characterization 

The existing toxicological database is primarily comprised of studies conducted with [RS]-

dimethenamid (50:50, S:R). However, bridging studies indicate that the dimethenamid 

toxicology database is adequate for the risk assessment of DMTA-P. The acute toxicity data 

indicate that [S]-dimethenamid-P is in Category II via the oral route of exposure, and Category 

III for exposure via the dermal and inhalation routes. It is moderately irritating to the eye 

(Category III) and slightly irritating to the skin (Category IV). DMTA-P is a mild skin 

sensitizer. The short- and intermediate-term point of departure (POD) for dermal exposure (300 

mg/kg/day) was based on decreased body weight on a 21 day dermal study in rabbits. The 

inhalation and incidental oral toxicity endpoint (10 mg/kg/day) was selected from a subchronic 

and chronic oral toxicity study in dogs based on decreased body weight in females, increased 

relative to body liver weight in both sexes, increased periportal cytoplasmic vacuolation in liver 

in both sexes, and dilation of liver sinusoids in females. A subchronic inhalation toxicity study is 

not available, however, the Hazard and Science Policy Council (HASPOC), using a weight of the 

 

1 Available: http://www.epa.gov/pesticides/science/residential-exposure-sop.html
Page 5 of 36

evidence (WOE) approach, concluded that a subchronic inhalation study is not required for 

dimethenamid-P at this time (TXR# 0056993).

Combining Exposures/Risk Estimates

Dermal and inhalation exposures to workers were not aggregated because the toxicity endpoints 

for these exposure routes are not based on common toxicity effects in/of the liver. Dermal 

effects (body weight gain) were considered to be non-specific.

Summary of Residential Exposure and Risk Estimates

All existing residential exposures have been reassessed to reflect updates to HED’s 2012 

Residential SOPs along with policy changes for body weight assumptions. No registered 

products resulted in residential handler or post-application risk estimates of concern. All risk

estimates are greater than HED’s Level of Concern (LOC) of 100 and therefore not of concern.

(Dermal Margins Of Exposure (MOEs) ranged from 250 to 5,300,000; Inhalation MOEs range 

from 7,700 to 1,500,000; and post-application MOEs range from 310 to 200,000).

Summary of Occupational Exposure and Risk Estimates

Occupational handler dermal and inhalation exposure and risk assessment are not of concern (i.e.

all MOEs ≥ 100) at baseline mitigation (no PPE), with one exception. The dermal exposure 

scenario of mixing and loading a liquid formulation of DMTA-P for aerial applications resulted

in an MOE of 92. However, with the use of additional PPE (i.e., gloves) the risk estimate was 

mitigated to an MOE of 540. Dermal MOEs ranged from 92 to 9,100. Inhalation MOEs ranged 

from 3,100 to 140,000. Note that only engineering control (enclosed cockpit) data are available 

to assess risks to handlers operating aircrafts. Short- and intermediate-term post-application risk 

estimates were not a concern on day 0 (12 hours following application) for all post-application 

activities (MOEs ranged from 5,100 to 15,000). 

Restricted Entry Interval (REI)

Under 40 CFR 156.208 (c) (2) (iii), ai’s classified as Toxicity Category III or IV for acute 

dermal, eye irritation and primary skin irritation are assigned a 12-hour REI. Therefore, the label 

required REI of 12 hours is adequate to protect agricultural workers from post-application 

exposures to DMTA-P. 

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

inhalation exposure assessment was not performed for DMTA-P 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 DMTA-P.

Human Studies Review

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

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

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

database; the ARTF database; the Residential SOPs (Lawns/Turf and Garden/Trees); other 

registrant-submitted exposure monitoring studies (MRID 47901302); published literature study, 

etc], 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 
Page 6 of 36

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 website2. 

2.0 Data Deficiencies and Requirements

None.

3.0 Hazard Characterization

Acute Toxicity

The acute toxicity for DMTA-P is summarized in Table 3.1.

Table 3.1. Acute Toxicity Profile for Dimethenamid-P [PC 120051]

Guideline No. Study Type MRID(s) Results Toxicity Category

870.1100 Acute oral/rats [Sprague 

Dawley]

44097603

(1996)

LD50 = 429 mg/kg males 

LD50 = 531 mg/kg females

LD50 =480 mg/kg both sexes

II

870.1200 Acute dermal/rabbits 

[NZW]

44332234

(1996) LD50 = >2000 mg/kg III

870.1300 Acute inhalation 

[Sprague Dawley]

44332235

(1996) LC50 = 2.2 mg/L III

870.2400 Acute eye irritation 

[NZW]

44332238

(1996) Minimally irritating III

870.2500 Acute dermal irritation 

[NZW]

44332239

(1996) Minimally irritating IV

870.2600 Skin sensitization 

[Guinea Pigs] 44097604 Mild skin sensitizer Sensitizer

Toxicological PODs Used for Risk Assessment

The primary target organ for dimethenamid (enriched (P) and racemic (RS) mixtures) is the liver 

and is displayed throughout the database and in all species tested. Chronic studies performed 

with [RS]-dimethenamid in the rat, mouse and dog showed decreases in body weight and food 

efficiency as accompanying effects over time. At higher dose levels, liver pathology, stomach 

hyperplasia, and some indications of kidney effects were noted. In some of the studies, liver 

enzymes coupled with increased cholesterol levels at high doses resulted in liver pathology. In,

two 21-day dermal toxicity studies in rabbits were conducted on [RS]-dimethenamid and in one 

of those studies minor skin irritation was observed at all doses tested and a decrease in body 

weight gain was also seen at the lowest effect level. Together these studies are considered cocritical for dermal short and intermediate-term exposures. A summary of the toxicological 

endpoints and doses chosen for the relevant exposure scenarios for human risk assessment are 

found in Table 3.2. 

The POD for short- and intermediate-term dermal occupational and non-occupational exposures 

is 300 mg/kg/day based on decreased body weight gain at the LOAEL of 500 mg/kg/day per co-

 

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

http://www.epa.gov/pesticides/science/post-app-exposure-data.html
Page 7 of 36

critical 21-day dermal toxicity studies in rabbits (MRID 41662414, MRID 41951301). Since the 

short- and intermediate-term dermal POD was based on a route-specific toxicity study, no 

absorption factor was necessary to estimate exposure. It was also noted that the effects seen are 

considered non-specific. 

The POD for short- and intermediate- term inhalation occupational and non-occupational 

exposures is 10 mg/kg/day based on decreased body weight in females, increased relative to 

body liver weight in both sexes, increased periportal cytoplasmic vacuolation in liver in both 

sexes, and dilation of liver sinusoids in females at the LOAEL of 33.6 mg/kg/day per co-critical 

(MRID 41615902, MRID 41615903). No inhalation absorption data are available, therefore, 

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

route of exposure. The same POD (10 mg/kg/day) was selected for incidental oral exposure in 

children. A subchronic inhalation toxicity study is not available. However, the Hazard and 

Science Policy Council (HASPOC), using a weight of the evidence (WOE) approach, concluded 

that a subchronic inhalation study is not required for dimethenamid-P at this time (TXR#

0056993)

Dermal and inhalation exposures to workers were not aggregated because the toxicity endpoints 

for these exposure routes are not based on common toxicity effects in/of the liver. Dermal 

effects (body weight gain) were considered to be non-specific.

The standard body weight for the general population (80 kg) was used for all exposure scenarios 

covered in this risk assessment since the endpoints selected were not developmental and/or fetal 

effects.

Classification of Carcinogenic Potential

The Carcinogenicity Peer Review of dimethenamid on 23/MAR/1995 (TXR# 012143) and 

15/JUN/1992 (TXR# 012831) stated that the weight of evidence classification was Group C -

possible human carcinogen. The chronic point of departure (cPOD) is protective for potential 

carcinogenic effects. This decision was based on a statistically significant increasing trend for 

liver cell tumors (benign and malignant combined) in male rats. Dimethenamid has shown 

positive results in some genotoxicity tests and is structurally related to other chloroacetanilide

carcinogens (i.e., acetochlor, metolachlor). An acceptable study in mice showed no dose related 

tumors. [Note: The cancer classification has not been updated based on the EPA’s 2005 

Guidelines for Carcinogen Risk Assessment. However, any reclassification would not affect the 

conclusion that the cPOD is protective for carcinogenic effects and would therefore not affect the 

risk assessment.]

Food Quality Protection Act (FQPA) and Uncertainty Factors

HED’s level of concern for risks (i.e., target level for MOE) is defined by the uncertainty factors 

that are applied to the assessment. HED 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 FQPA safety factor was previously reduced to 1X based on 

toxicological considerations by the HIARC (12/2/03; TXR # 0052260). RAB IV toxicologists 

reviewed the data available for DMTA-P for the current action and supported the previous 

decision to reduce the FQPA safety factor. The total uncertainty factor that has been applied to 
Page 8 of 36

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

and inhalation exposures.

Table 3.2. Summary of Toxicological Doses and Endpoints for Dimethenamid-P

Exposure/Scenario Point of 

Departure

Uncertainty/FQPA 

SF

RfD, PAD, 

LOC for Risk 

Assessment

Study and Toxicological Effects

Acute Dietary (General 

Population, including 

Infants and Children)

NOAEL = 200

UFA= 10x

UFH=10x

FQPA SF= 1x

aRfD = 2.0

aPAD = 2.0

LOAEL= 600 mg/kg from ACN study based on 

lacrimation, salivation, irregular and accelerated 

respiration, slight tremors, reduced exploration, 

unsteady gait, significantly reduced rearing 

(females) and strongly constricted pupils 

(males)

Incidental Oral ShortTerm (1-30 days) and 

Intermediate-Term (1-6 

months)

NOAEL= 10 

mg/kg/day

UFA = 10 X

UFH = 10 X LOC for MOE 

= 100

Subchronic/chronic oral dog studies (MRIDs 

41615902 & 41615903)

NOAEL is from the chronic dog study

Chronic dog LOAEL = 48.7 mg/kg/day

Subchronic NOAEL = 4.72 mg/kg day

Subchronic LOAEL = 33.6 mg/kg/day from the 

subchronic dog study based on decreased body 

weight in females, increased relative to body 

liver weight in both sexes, increased periportal 

cytoplasmic vacuolation in liver in both sexes, 

and dilation of liver sinusoids in females.

Inhalation Short- Term 

(1-30 days) and 

Intermediate-Term (1-6 

months)

NOAEL= 10 

mg/kg/day

UFA = 10 X

UFH = 10 X LOC for MOE 

= 100

Subchronic/chronic oral dog studies (MRIDs 

41615902 & 41615903)

NOAEL is from the chronic dog study

Chronic dog LOAEL = 48.7 mg/kg/day

Subchronic NOAEL = 4.72 mg/kg day

Subchronic LOAEL = 33.6 mg/kg/day from the 

subchronic dog study based on decreased body 

weight in females, increased relative to body 

liver weight in both sexes, increased periportal 

cytoplasmic vacuolation in liver in both sexes, 

Dermal Short- Term (1-

30 days) and 

Intermediate-Term (1-6 

months)

NOAEL= 300 

mg/kg/day

UFA = 10X

UFH =10X LOC for MOE 

= 100

21 Day dermal rabbit study (MRIDs 

41662414/419513010)

LOAEL = 500 mg/kg/day based on decreased 

body weight gain only (non-specific)

Cancer (oral, dermal, 

inhalation) “C” Possible human carcinogen. (No Q1*). The cRfD is considered protective of the cancer effects.

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

extrapolation to determine risk associated with lower environmentally relevant human exposures; NOAEL = no observed adverse effect level; LOAEL = 

lowest observed adverse effect level; UF = uncertainty factor; UFA = extrapolation from animal to human (interspecies); UFH = potential variation in 

sensitivity among members of the human population (intraspecies); FQPA SF = FQPA Safety Factor; PAD = population adjusted dose (a = acute, c = 

chronic); RfD = reference dose; MOE = margin of exposure; LOC = level of concern
Page 9 of 36

4.0 Use Profile 

BASF has submitted a Section B of the petition proposing an amendment to the Section 3 

registration for Outlook® Herbicide (EPA Registration Number 7969-156), a 6.0 lb/gal 

emulsifiable concentrate (EC) formulation of dimethenamid-P, to add preplant, preemergence 

and early postemergence applications to members of cottonseed subgroup 20C. Preplant surface 

or preemergence applications may be made at up to 0.47 lb ai/A and an early postemergence 

application may be made at up to 0.98 lb ai/A. Sequential applications of a preplant or 

preemergence application followed by an early postemergence application at least 14-days after 

the initial application may be made at up to 1.45 lb ai/A/season. No preharvest interval (PHI) is 

specified but the last application may be made two weeks after the R1 initial bloom stage. 

Section B of the petition is draft supplemental labeling to the current Outlook® Herbicide label 

(EPA Registration Number 7969-156). The use directions of the draft supplemental labeling to 

the subject end-use product under consideration provided in Section B are summarized in Table 

4.1.

Table 4.1. Summary of Directions for Use of Dimethenamid-P.

Appl. Timing, 

Type, and 

Equip.

Formulation

[EPA Reg. 

No.]

Max. Appl. 

Rate

(lb ai/A)

Max. 

No. 

Appl. 

per 

Season

Max. 

Seasonal 

Appl. 

Rate

(lb ai/A)

PHI

(days)

Use Directions and 

Limitations

Cottonseed subgroup 20C: Cotton.

Preplant surface, 

preemergence 

and/or 

postemergence 

foliar broadcast.

Ground, aerial 

or chemigation

6.0 lb/gal

EC

[7969-156]

0.47

preplant 

surface or 

preemergence

1

1.45 Not 

Specified

May be applied as single 

application or in sequential 

applications (preplant or 

preemergence followed by 

postemergence). Sequential 

applications must be 

separated by at least 14 

days. No PHI is specified; 

however, postemergence 

applications may be made 

from first true leaf stage to 

the mid-bloom stage (i.e., 

two weeks after R1 initial 

bloom stage).

0.98

postemergence 1

PHI = preharvest interval.

5.0 Residential Exposure and Risk Estimates

There are no proposed residential uses at this time; however, there are existing residential uses 

that have been reassessed in this document to reflect updates to HED’s 2012 Residential SOPs3

along with policy changes for body weight assumptions. The revision of residential exposures 

will impact the human health aggregate risk assessment for dimethenamid-P.

 

3 Available: http://www.epa.gov/pesticides/science/residential-exposure-sop.html
Page 10 of 36

DMTA-P is registered for residential use on turfgrass, ornamentals, and tree plantations, and is 

formulated as an emulsifiable concentrate (EC) and granule (G). The currently registered enduse products (EPs) available for residential use include:

1. Tower Herbicide EC (EPA Reg. No. 7969-239; 63.9% DMTA-P), ,

2. Freehand 1.75G Herbicide (EPA Reg. No. 7969-273; 0.75% DMTA-P), and

3. Freehand CA 1.75G Herbicide (EPA Reg. No. 7969-358; 0.75% DMTA-P).

BASF Corporation is the registrant of all three products. 

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 various 

exposure scenarios that involve mixing/loading/applying various formulations with manually 

pressurized handguns, hose-end sprayers, backpack sprayers, push-type rotary spreaders and 

belly grinders.

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 SOPs4.

Combining Exposures/Risk Estimates

Dermal and inhalation exposures to workers were not aggregated because the toxicity endpoints 

for these exposure routes are not based on common toxicity effects in/of the liver. Dermal 

effects (body weight gain) were considered to be non-specific.

Summary of Residential Handler Non-Cancer Exposure and Risk Estimates

Summaries of the short-term dermal and inhalation risk estimates for residential handlers are 

included in Table 5.1.1. The maximum application rate for each exposure scenario is presented 

as the worst case scenario. All risk estimates are greater than the LOC of 100 and therefore not 

of concern (Dermal MOEs range from 250 to 5,300,000; Inhalation MOEs range from 7,700 to 

1,500,000). 

 

4 Available: http://www.epa.gov/pesticides/science/residential-exposure-sop.html
Page 11 of 36

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

Exposure 

Scenario

Application 

Equipment/

Method

Dermal Unit 

Exposure 

(mg/lb ai)

Inhalation Unit 

Exposure 

(mg/lb ai)

Maximum 

Application 

Rate1

Area Treated 

or Amount 

Handled Daily2

Dermal Inhalation

Dose 

(mg/kg/day)3

MOE4

(LOC=100)

Dose 

(mg/kg/day)5

MOE6

(LOC=100)

Liquid Formulation

Lawns/Turf

Hose-end 

Sprayer 13.4 0.022 1.5 lb ai/acre 0.5 acres 0.13 2,400 0.00021 49,000

Manuallypressurized 

handwand

63 0.018

0.15 lb ai/gal 5 gallons

0.59 510 0.00017 60,000

Backpack 130 0.14 1.2 250 0.0013 7,700

Gardens/Trees

Sprinkler can

58 0.0014 0.15 lb ai/gal

5 gallons 0.54 550 0.000013 770,000

Hose-end 

Sprayer 11 gallons 0.13 2,400 0.00021 49,000

Granular Formulation

Lawns/Turf

Push-type rotary 

spreader 0.81 0.0026 1.5 lb ai/acre 0.5 acres 0.0076 40,000 0.000024 410,000

Belly grinder 360 0.039 3.4x10-5

lb ai/ 

ft2 1,200 ft2 0.19 1,600 0.000020 500,000

Gardens/Trees

Hand Dispersal 160 0.38

3.4x10-5lb ai/ 

ft2 1,200 ft2

0.083 3,600 0.00020 52,000

Shaker can /Cup 0.0045 0.00054 0.000057 5,300,000 0.0000067 1,500,000

Spoon 6.2 0.087 0.0032 94,000 0.000045 220,00

1 Based on registered residential uses for dimethenamid-P.

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

3 Dermal Dose = Dermal Unit Exposure (mg/lb ai) × Application Rate (lb ai/acre or gal or ft2) × Area Treated or Amount Handled (A/day or gallons/day or 

ft2/day) × Dermal Absorption Factor (100 %) ÷ Body Weight (80 kg).

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

5 Inhalation Dose = Inhalation Unit Exposure (mg/lb ai) × Application Rate (lb ai/acre or gal or ft2) × Area Treated or Amount Handled (A/day or 

gallons/day or ft2/day) ÷ Body Weight (80 kg).

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

7 Total MOE = NOAEL (mg/kg/day) ÷ (Dermal Dose + Inhalation Dose) OR Total MOE = 1 ÷ [(1 / Dermal MOE) + (1 /Inhalation MOE)].
Page 12 of 36

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 dimethenamid-P. The quantitative 

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

scenarios: 

The scenarios, routes of exposure and lifestages of potential exposure include:

1. Physical activities on turf: adults (dermal) and children 1 to < 2 years old (dermal and 

incidental oral);

2. Mowing: adults (dermal) and children 11 to < 16 years old (dermal);

3. Golfing: adults (dermal), children 11 to < 16 years old (dermal), and children 6 to < 11

years old (dermal); and

4. Contact with Treated Gardens and Trees: adults (dermal) and children 6 to <11 years old 

(dermal).

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

Appendix in the 2012 Residential SOPs5. 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

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 

SOPs5: Lawns/Turf, and Gardens and Trees. 

Furthermore, a chemical specific Transferable Turf Residue (TTR) Study was submitted by the 

registrant (MRID# 47901302), reviewed by HED (D376733, I. Nieves, 3/16/11) and found to be 

acceptable for use in exposure and risk assessments. This study was designed to determine the 

transferable turf residue (TTR) of dimethenamid-P dislodged from turf treated with an 

emulsifiable concentrate formulation containing 63.9% dimethenamid-P as the active ingredient

(Tower® Herbicide) and a spreadable granule formulation containing 0.75% dimethenamid-P 

(FreeHand® 1.75 G Herbicide) at three locations in the United States (Florida, New Jersey, and 

California). Transferable residues were sampled using the Modified California Roller technique. 

The TTR values used to quantify potential exposure risk by performing residential postapplication activities on lawns/turf were taken from the aforementioned study. For liquid 

formulations, the highest predicted dimethenamid-P TTR level detected was 0.0312 μg/cm2

(California site). For granular formulations, since DMTA-P TTR values were not detected above 

the LOQ at any sampling interval after application a TTR value of 0.00090 μg/cm2, equivalent 

to 1⁄2 the LOQ value (0.00179 μg/cm2) is being used for human health exposure assessments.

 

5 Available: http://www.epa.gov/pesticides/science/residential-exposure-sop.html
Page 13 of 36

For post-application dermal exposure resulting from contact with previously treated gardens and 

trees, the default Dislodgeable Foliar Residue (DFR) calculation was done in the absence of 

chemical-specific data.

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 SOPs5.

Combining Exposure and Risk Estimates

HED combines risk estimates resulting from separate post-application exposure scenarios when 

it is likely they can occur simultaneously based on the use pattern and the behavior associated 

with the exposed population and when the toxicological effects are similar. However, the 

incidental oral scenarios (i.e., hand-to-mouth, object-to-mouth, soil ingestion, and granule 

ingestion) should be considered inter-related and it is likely that they occur interspersed amongst 

each other across time. Combining all three of these scenarios would be overly-conservative 

because of the conservative nature of each individual assessment. Therefore, the hand-to-mouth 

post-application exposure scenario for children 1 to < 2 years old is considered a protective 

estimate of children’s exposure to pesticides used on turf. 

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

Table 5.2.1 presents the post-application MOE values calculated for adults and children after turf 

applications of DMTA-P. HED considers this liquid formulation risk estimates for postapplication exposure to be protective of the granular product, because of its lower transferability 

properties compared to that observed for the liquid formulation, Tower Herbicide (0.64% 

transferability for the liquid compared to 0.005% for the granular). This phenomena can be 

observed in the TTR study (MRID# 47901302) submitted by the registrant, BASF, where TTR 

values were not detected above the LOQ at any sampling interval for the granular formulation 

product. Post-application non-cancer risks do not exceed HED’s level of concern for any of the 

scenarios assessed (MOEs range from 310 to 200,000; LOC = 100). 

Table 5.2.1 DMTA-P (Tower Herbicide EC) Residential Risk Estimates for Turf Post-application Exposure.

Site Activity Route of 

Exposure

TC 

(cm2/hr)

TTR (Study)

/DFR (Default)

(μg/cm2)

Exposure 

Time

(hrs/day)

Short-Term

Average Daily 

Dose2

(mg/kg/day)

MOE3

(LOC=100)

Adults

Max single application rate: 1.5 lbs ai/A1

Treated 

Lawns

High Contact Activities

Dermal

180,000

TTR 

(Lawns/Turf): 

0.0312

1.5 0.11 2,900

Mowing 5,500 1 0.0021 140,000

Golf 

Course 

Turf

Golfing 5,300 4 0.0083 36,000

Gardens

High Contact Activities 

(liquid and granular formulations)

8,400

DFR 

(Gardens/Trees): 

4.2

2.2 0.96 310

Trees and 

Retail 

Plants

1,700 1 0.089 3,400

Indoor 

Plants 220 1 0.011 26,000

Children
Page 14 of 36

Table 5.2.1 DMTA-P (Tower Herbicide EC) Residential Risk Estimates for Turf Post-application Exposure.

Site Activity Route of 

Exposure

TC 

(cm2/hr)

TTR (Study)

/DFR (Default)

(μg/cm2)

Exposure 

Time

(hrs/day)

Short-Term

Average Daily 

Dose2

(mg/kg/day)

MOE3

(LOC=100)

Max single application rate: 1.5 lbs ai/A1

Treated 

Residential 

Areas

High Contact Activities (1<2 years)

Dermal

49,000

0.0312

1.5 0.21 1,400

Mowing (11<16 years) 4,500 1 0.0025 120,000

Golfing (6<11 years) 2,900 4 0.011 27,000

Hand to Mouth Transfer of 

Pesticide Residue (1<2 years)

Oral N/A

Hand Residue 

(mg/cm2) 1.5 0.0043 2,300

0.00046

Object to Mouth Transfer of 

Pesticide Residue (1<2 years)

Object Residue 

(mg/cm2) 1.5 0.00013 77,000

0.031

Incidental Ingestion of Soil with 

Pesticide Residue (1<2 years)

Soil Residue 

(mg/cm2) N/A 0.000051 200,000

11.17

Incidental Granule Ingestion 

(episodic)

(1<2 years)

Ingestion Rate 

(g/day; 0.8% ai) N/A 0.20 980

0.3

Gardens

High Contact Activities 

(6<11 years)

(liquid and granular formulations)

Dermal

4,600

DFR 

(Gardens/Trees): 

4.2

1.1 0.66 460

Trees and 

Retail 

Plants

930 0.5 0.061 5,000

Indoor 

Plants 120 0.5 0.0078 38,000

1 Based on registered labels (Refer to Section 5).

2 Dose (mg/kg/day) equations provided in Appendix [A].

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

5.3 Residential Risk Estimates for Use in Aggregate Assessment

Table 5.3.1 reflects the residential exposure scenarios and associated risk estimates that are 

recommended for use in the aggregate assessment for DMTA-P. 

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

handler inhalation exposure from liquid applications to turf via backpack sprayer.

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

assessment reflects incidental oral exposure from post-application hand-to-mouth 

pesticide transfer from liquid application to residential turf.

Since it was determined that the dermal POD have no common toxicity effects with the 

incidental oral and/or inhalation PODs (same POD) the values recommended to be used for the 

aggregate assessment are based on the worst-case residential exposure estimates via the 

inhalation (adult male) and oral (child 1<2 years old) routes. Only short-term residential 

exposures are expected based on the Residential SOPs (2012). All residential handler and postapplication exposure estimate resulted in MOEs greater than 100, and are not of concern.
Page 15 of 36

Table 5.3.1. Recommendations for the Residential Exposures for the dimethenamid-P Aggregate Assessment.

Lifestage Exposure Scenario

Dose (mg/kg/day)1 MOE2

Dermal Inhalation Oral Total Dermal Inhalation Oral Total

Adult

Male

Handler: Backpack

Sprayer application of liquid 

formulation to turf

N/A 0.0013 N/A 0.0013 N/A 7,700 N/A 7,700

Child (1<2 

years old)

Post-application: High 

Contact Activities

From liquid application to 

residential turf

N/A N/A 0.0043 0.0043 N/A N/A 2,300 2,300

1 Dose = the highest dose for each applicable lifestage of all residential scenarios assessed. Note: Only inhalation and oral exposure had 

common effects and therefore aggregated. Values were not presented for dermal exposure as they were not relevant for aggregate (i.e., no 

common effects).

2 MOE = the MOEs associated with the highest residential doses. Note: Only inhalation and oral exposure had common effects and therefore 

aggregated. Values were not presented for dermal exposure as they were not relevant for aggregate (i.e., no common effects).

5.4 Spray Drift

Spray drift is a potential source of exposure to those nearby pesticide applications. This is 

particularly the case with aerial application, but, to a lesser extent, spray drift can also be a 

potential source of exposure from the ground application methods (e.g., groundboom and 

airblast) employed for DMTA-P. The Agency has been working with the Spray Drift Task Force 

(a task force composed of various registrants which was developed as a result of a Data Call-In 

issued by EPA), 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). 6 The Agency is also taking means to qualitatively and 

qualitatively address spray drift as a potential source of exposure in risk assessments for 

pesticides through existing programs such as Ag Drift and chemical specific properties of 

pesticides. The potential for spray drift will be quantitatively evaluated for each pesticide during 

the Registration Review process which ensures that all uses for that pesticide will be considered 

concurrently. 

5.5 Residential Bystander Post-Application Inhalation Exposure

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

assessment was not performed for dimethenamid-P at this time primarily because of the low 

acute inhalation toxicity (Toxicity Category III). 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, 20107. The Agency is in the 

process of evaluating te 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 dimethenamid-P.

 

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

7 Available: http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html
Page 16 of 36

6.0 Occupational Exposure and Risk Estimates

6.1 Occupational Handler Exposure/Risk Estimates

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

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

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

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

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

manner specific to each application event. 

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

that can potentially be used, occupational handler exposure is expected from the proposed uses. 

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

several scenarios which include mixing/loading/applying the liquid formulation of 

dimethenamid-P. The use profile is summarized in Section 4.0. Methods of application include 

aerial, chemigation, groundboom, and handheld equipment. Flagging for aerial use is also a 

potential source of worker exposure. Refer to Table 6.1.1 for a detailed list of each scenario.

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: Refer to the proposed use pattern table in Section 4.0.

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, or other registrant-submitted occupational exposure 

studies. Some of these data are proprietary (e.g., AHETF data), and subject to the data 

protection provisions of FIFRA. The standard values recommended for use in predicting handler 

exposure that are used in this assessment, known as “unit exposures”, are outlined in the 

“Occupational Pesticide Handler Unit Exposure Surrogate Reference Table8”, 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 website9.

Area Treated or Amount Handled: The area treated or amount handled is based on HED 

ExpoSAC Policy No. 9.1. Refer to Table 6.1.1 for these assumptions for each scenario.

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 

 

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

9 Available: http://www.epa.gov/pesticides/science/handler-exposure-data.html
Page 17 of 36

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

multiple applications for multiple clients within a region). For the proposed use on cotton 

subgroup 20C both short- and intermediate-term exposures are expected from occupational use. 

Since the PODs for short- and intermediate-term exposure are the same, the short-term 

assumptions and risk calculations are protective of both durations.

Mitigation/Personal Protective Equipment: 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). The DMTA-P product labels direct mixers, loaders, applicators and 

other handlers to wear long-sleeved shirts, long pants, shoes plus socks, and chemical-resistant 

gloves made of any waterproof material.

Occupational Handler Non-Cancer Exposure and Risk Estimate Equations

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

found in Appendix A.

Combining Exposures/Risk Estimates:

Dermal and inhalation exposures to workers were not aggregated because the toxicity endpoints 

for these exposure routes are not based on common toxicity effects in/of the liver. Dermal 

effects (body weight gain) were considered to be non-specific.

Summary of Occupational Handler Non-Cancer Exposure and Risk Estimates

The results of the occupational handler exposure and risk assessment indicate that short- and 

intermediate-term dermal and inhalation risk estimates are not of concern (i.e. all MOEs ≥ 100) 

at baseline mitigation (no PPE), except for the dermal exposure scenario of mixing and loading a 

liquid formulation of DMTA-P for aerial applications which resulted in an MOE of 92. With the 

use of additional PPE (i.e., gloves) the risk estimate MOE is mitigated to 540. Inhalation MOEs 

ranged from 3,100 to 140,000 at baseline. Note that only engineering control (enclosed cockpit) 

data are available to assess risks to handlers operating aircrafts.

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.

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, 
Page 18 of 36

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.
Page 19 of 36

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

Exposure Scenario Crop or 

Target

Level of 

Concern

Dermal Unit 

Exposure 

(μg/lb ai)1

Inhalation Unit 

Exposure 

(μg/lb ai)1

Maximum 

Application 

Rate2

Area 

Treated or 

Amount 

Handled 

Daily3

Dermal Inhalation

Mitigation 

Level

Mitigation 

Level

Dose 

(mg/kg/day)4 MOE5 Dose (mg/kg/day)6 MOE7

Mixer/Loader

Mixing/Loading Liquids 

for Aerial Applications

Cotton 

Subgroup 

20C

100

220

(baseline)

37.6

(baseline + 

gloves)

0.219

(baseline: no 

respirator)

1.0 lb ai/A

1,200

3.25 

(baseline)

0.555

(baseline + 

gloves)

92

(baseline)

540

(baseline 

+gloves)

0.0032

(baseline)

3,100

(baseline)

Mixing/Loading Liquids 

for Chemigation 

Applications 

350

0.948

(baseline)

320

(baseline)

0.00094

(baseline)

11,000

(baseline)

Mixing/Loading Liquids 

for Groundboom 

Applications

200

0.541

(baseline)

550

(baseline)

0.00054

(baseline)

19,000

(baseline)

Applicator

Applying Liquids with 

Aerial Equipment Cotton 

Subgroup 

20C

100

2.08

(Eng. Controls)

0.0049

(Eng. Controls)

1.0 lb ai/A

1,200

0.0308

(Eng. 

Controls)

9,700

(Eng. 

Controls)

0.0000724

(Eng. Controls)

140,000

(Eng. 

Controls)

Applying Liquids with 

Groundboom Equipment

78.6

(baseline)

0.34

(baseline) 200

0.194

(baseline)

1,500

(baseline)

0.00084

(baseline)

12,000

(baseline)

Flagger

Flagging Liquids for Aerial 

Applicaitons 

Cotton 

Subgroup 

20C

100

11

(baseline)

0.35

(baseline) 1.0 lb ai/A 350

0.047

(baseline)

6,300

(baseline)

0.0015

(baseline)

6,700

(baseline)

1 Based on the “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table” (March 2013); Level of mitigation: Baseline, PPE (i.e., gloves), Eng. Controls.

2 Based on proposed label use (EPA Reg No. 7969-156).

3 Exposure Science Advisory Council Policy #9.1.

4 Dermal Dose = Dermal Unit Exposure (μg/lb ai) × Conversion Factor (0.001 mg/μg) × Application Rate (lb ai/acre or gal) × Area Treated or Amount Handled (A or gal/day) × DAF (%) ÷ BW (kg).

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

6 Inhalation Dose = Inhalation Unit Exposure (μg/lb ai) × Conversion Factor (0.001 mg/μg) × Application Rate (lb ai/acre or gal) × Area Treated or Amount Handled (A or gal/day) ÷ BW (kg).

7 Inhalation MOE = Inhalation NOAEL (mg/kg/day) ÷ Inhalation Dose (mg/kg/day).
Page 20 of 36

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

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

assessment was not performed for DMTA-P at this time primarily because of the low acute 

inhalation toxicity (Toxicity Category III), and the low proposed use rate (1.0 lb ai/A). 

However, there are multiple potential sources of post-application inhalation exposure to 

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

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

contain pesticides. The Agency sought expert advice and input on issues related to volatilization 

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

Panel (SAP) in December 2009, and received the SAP’s final report on March 2, 201010. The 

Agency is in the process of evaluating the SAP report as well as available post-application 

inhalation exposure data generated by the ARTF and may, as appropriate, develop policies and 

procedures, to identify the need for and, subsequently, the way to incorporate occupational postapplication inhalation exposure into the Agency's risk assessments. If new policies or 

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

post-application inhalation exposure assessment for DMTA-P.

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

Occupational Post-application Dermal Exposure Data and Assumptions

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

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

basis.

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

days to six months as intermediate-term. For DMTA-P, since toxicological endpoints are the 

 

10 Available: http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html
Page 21 of 36

same for both durations (short-, and intermediate), short-term risk estimate quantification is 

presented in this memo and considered protective of longer exposure durations. 

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

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

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

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

known as “transfer coefficients”, are presented in the ExpoSAC Policy 311” which, along with 

additional information about the ARTF data, can be found at the Agency website12. Table 

6.2.2.1 provides a summary of the anticipated post-application activities and associated transfer 

coefficients for the proposed crops/use sites.

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

Proposed Crops

Policy Crop 

Group 

Category

Crop 

Height

Foliage 

Density

Transfer 

Coefficients 

(cm2/hr)

Activities

Cotton Subgroup 20C

Field / row 

crop, low / 

medium

Low

Full/Min 210 Scouting

Full/Min 70 Weeding, Hand

Application Rate: Refer to the proposed use pattern table in Section 4.0.

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

Dislodgeable Foliar Residues: Chemical-specific dislodgeable foliar residue data have not been 

submitted for DMTA-P. Therefore, this assessment uses HED’s default assumption that 25% of 

the application is available for transfer on day 0 following the application and the residues 

dissipate at a rate of 10% each following day.

Dislodgeable Foliar Residue (DFR): In accordance with 40CFR158, DFR data are required for 

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

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

values. The 2012 Standard Operating Procedures for Residential Pesticide Exposure 

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

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

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

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

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

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

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

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

 

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

12 Available: http://www.epa.gov/pesticides/science/post-app-exposure-data.html
Page 22 of 36

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

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

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

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

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

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

uncertainty in the use of the default DFR value for DMTA-P (i.e., there is a small chance that the 

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

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

this potential uncertainty. For example, when assessing residential and occupational postapplication exposure to gardens and ornamentals, EPA assumes the following: exposures occur 

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

EPA assumes that no dissipation or degradation occurs, it doesn’t rain, etc); individuals perform 

the same post-application activities performed in the transfer coefficient study day after day (e.g., 

weeding, harvesting, pruning, etc.); and individuals engage in these post-application activities for 

a high-end amount of time every day (represented by data reflecting time spent gardening based 

on survey data).

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

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

exposure is not being underestimated. 

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

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

than 2 times higher than the level of concern, (MOE = 5,100 compared to the LOC of 100); EPA 

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

appreciably to our overall understanding of the availability of dislodgeable foliar pesticide 

residues for DMTA-P. 

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

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

workers can be found in Appendix A.

Occupational Post-application Non-Cancer Dermal Risk Estimates

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

Crop/Site Activities Transfer Coefficient 

(cm2/hr) DFR1 Dermal Dose (mg/kg/day)2

MOE3

LOC=100

Short- and Intermediate-term

Cotton Subgroup 20C

Scouting 210

2.8

0.059 5,100

Weeding, Hand 70 0.020 15,000

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

2 Daily Dermal Dose = [DFR (μg/cm2) × Transfer Coefficient × 0.001 mg/μg × 8 hrs/day × dermal absorption (%)]  BW (kg).

3 MOE = POD (mg/kg/day) / Daily Dermal Dose. Daily Dermal Dose = [DFR/TTR (μg/cm2) × TC × 0.001 mg/μg × 8 hrs/day × dermal 

absorption factor (%)]  BW (kg).
Page 23 of 36

Restricted Entry Interval

The REI specified on the proposed label is based on the acute toxicity of dimethenamid-P. 

Dimethenamid-P is classified as Toxicity Category III via the dermal route, Toxicity Category III 

for eye irritation potential and Toxicity Category IV for skin irritation potential. It is a mild skin 

sensitizer. Short- and intermediate-term post-application risk estimates were not a concern on 

day 0 (12 hours following application) for all post-application activities. Under 40 CFR 156.208 

(c) (2) (iii), ai’s classified as Acute III or IV for acute dermal, eye irritation and primary skin 

irritation are assigned a 12-hour REI. Therefore, the [156 subpart K] Worker Protection 

Statement interim REI of 12 hours is adequate to protect agricultural workers from postapplication exposures to DMTA-P. 

 
Page 24 of 36

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

Residential Handler Exposure Calculations

Turf, Gardens and Trees, 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).

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).

Residential Post-application

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.

E = TTRt * CF1 * TC * ET
Page 25 of 36

where:

E = exposure (mg/day);

TTRt = turf transferable residue on day t (μg/cm2) (Chemical-specific data, 0.352 for liquids, 

0.0009 for solids);

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

TC = transfer coefficient (cm2/hr); and

ET = exposure time (hr/day).

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) 1.5 lb ai/A

F

Fraction of AR as TTR 

following application (if 

chemical-specific data is 

unavailable)

L/WP/WDG 0.01

Granules 0.002

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))]
Page 26 of 36

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).

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
Page 27 of 36

Table A-2: Turf (Physical Activities) – Inputs for Residential Post-application Hand-to-Mouth 

Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

AR Application rate

(mass active ingredient per unit area) 1.5 lb ai/A

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);

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).
Page 28 of 36

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 Object-to-Mouth 

Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

AR Application rate (to turf)

(mass active ingredient per unit area) 1.5 lb ai/A

FO Fraction of AR as OR following application 1 0.01

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:

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);
Page 29 of 36

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

BW = body weight (kg).

Table A-3: 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) 1.5 lb ai/A

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

Post-application Episodic Granular Ingestion Exposure Algorithm– Physical Activities on Turf

Exposure from incidental ingestion of pesticide pellets or granules is calculated as follows:

 E = GIgR* FD * CF1

where:

E = exposure (mg/day);

GIgR = ingestion rate of dry pesticide formulation (g/day);

FD = fraction of ai in dry formulation (unitless); and

CF1 = weight unit conversion factor (1,000 mg/g).

Dose, normalized to body weight, are calculated as:

BW

E

D 

where:

D = dose (mg/kg-day);
Page 30 of 36

E = exposure (mg/day); and

BW = body weight (kg).

Table A-4: Turf (Physical Activities) – Inputs for Residential Post-application Episodic Granular 

Ingestion Exposure 

Algorithm 

Notation

Exposure Factor 

(units) Point Estimate(s)

FD Fraction of active ingredient in dry formulation 0.8%

AR Application rate (lbs/A or lbs/1,000 ft2) 1.5 lb ai/A

GIgR Granule ingestion rate per day

(g/day) 1 0.3

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

1 See discussion below on how this value may be adjusted if product specific information is available.

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) (Chemical-specific data, 0.352 for liquids, 

0.0009 for solids);

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

TC = transfer coefficient (cm2/hr); and

ET = exposure time (hr/day).

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 1.5 lb ai/A
Page 31 of 36

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

mass active ingredient per unit area

FAR

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 5,500

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

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) (Chemical-specific data, 0.352 for liquids, 

0.0009 for solids);

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

TC = transfer coefficient (cm2/hr); and

ET = exposure time (hr/day).

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

BW

E AF D*


Page 32 of 36

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)

1.5 lb ai/A

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

Gardens and Trees

Post-application Dermal Exposure Algorithm

Exposure resulting from contacting previously treated gardens and trees while performing 

physical activities is calculated as shown below. Residential post-application exposure 

assessment must include calculation of exposure on the day of application. Therefore, though an 

assessment can present exposures for any day “t” following the application, it must include “day 

0” exposure.

E = DFRt * CF1 * TC * ET

where:

E = exposure (mg/day);

DFRt = dislodgeable foliar residue on day "t" (μg/cm2);

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

TC = transfer coefficient (cm2/hr); and
Page 33 of 36

ET = exposure time (hrs/day).

In the absence of chemical-specific data, DFRt can be calculated as follows:

DFRt = AR * FAR * (1-FD)

t

* CF2 * CF3

where:

DFRt = dislodgeable foliar residue on day "t" (μg/cm2);

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

FAR = fraction of ai as dislodgeable residue following application (unitless);

FD = fraction of residue that dissipates daily (unitless);

t = post-application day on which exposure is being assessed;

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

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

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

BW

E AF D*



where:

D = dose (mg/kg-day);

E = exposure (mg/day);

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

BW = body weight (kg).

Table A-7: Gardens, Trees, and “Pick-your-own” Farms –Inputs for Residential Post-application 

Dermal Exposure 

Algorithm 

Notation

Exposure Factor

(units)

Point Estimate(s)

AR Application rate

(mass ai per unit area) 1.5 lb ai/A

FAR

DFR following application, if chemical-specific is unavailable

(fraction) 0.25

FD

Daily residue dissipation, if chemical-specific is unavailable

(fraction) 0.10

TC

Transfer 

Coefficient

(cm2/hr)

Gardensa Adults 8400

Children 6 < 11 years old 4600

Trees, Retail 

Plants (if 

applicable)a

Adults 1700

Children 6 < 11 years old 930

Indoor Plants Adults 220

Children 6 < 11 years old 120

ET

Exposure 

Time

(hours per 

day)

Home activitiesb

Gardens

Adults 2.2

Children 6 < 11 years 

old 1.1

Trees, Retail 

Plants (if 

applicable)

Adults 1.0

Children 6 < 11 years 

old 0.50
Page 34 of 36

Table A-7: Gardens, Trees, and “Pick-your-own” Farms –Inputs for Residential Post-application 

Dermal Exposure 

Algorithm 

Notation

Exposure Factor

(units)

Point Estimate(s)

Indoor Plants

Adults 1.0

Children 6 < 11 years 

old 0.50

“Pick-your-own” 

Farms (if 

applicable)

Adults 5.0

Children 6 < 11 years old 1.9

BW Body weight

(kg)

Adults 80

Children 6 < 11 years old 32

a Transfer coefficient point estimates from a composite distribution assuming equal proportion of time spent 

conducting various activities. See “Transfer Coefficient” section below. Children 6 < 11 years old TC derived 

using surface area adjustment (see Section 2.3).

b Activity time point estimates from a composite distribution assuming equal proportion of each respective 

activity. Time for children 6 < 11 years old derived using hrs/day ratio adjustment. See “Exposure Time” 

section below and Section Error! Reference source not found. of Appendix D,

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 (dermal and/or inhalation), and

BW = body weight (kg).

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

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

the daily dose of concern. The daily dermal and inhalation dose received by occupational 
Page 35 of 36

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).

Occupational Non-cancer Post-application Algorithms

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

following formulas:

DFRt=AR * F* (1-D)t* (4.54E8

ug

lb) * (2.47E-8

A

cm2

)

where:

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

AR = application rate (lb ai/acre),

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

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

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

E=TC * DFR t* ET * 0.001

mg

ug

where:

E = exposure (mg ai/day),

TC = transfer coefficient (cm2/hr),

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

ET = exposure time (hours/day).

The daily doses are calculated using the following formula:

ADD= 

E * AF

BW

where:
Page 36 of 36

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

E = exposure (mg ai/day),

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

BW = body weight (kg).

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

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

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

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

MOE values are calculated using the following formula:

MOE= 

POD

ADD

where:

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

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

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