Date: 

Subj ect: 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

March 29, 2016 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

Dicamba. Occupational and Residential Exposure Assessment for a Proposed 

Use on Herbicide-Tolerant Soybean and Cotton 

PC Code: 02980 I (acid), 128931 (DGA salt), I 00094 (BAPMA salt) 

Decision No.: 4637 10 

DP Barcode: 0429870 

Registration No.: 524-582 

Regulatory Action: Section 3 

Case No.: NA 

Petition No.: NA 

Risk Assessment Type: Occupational/Residential Exposure Assessment 

TXR No.: NA CAS No.: 1918-00-9, I 04040-79-1 

MRID No.: NA .tO CFR: 180.227 

From: 

Through: 

To: 

Introduction 

,-...._, 

Alexandra Gavclek, Biologist /A, {) Ii- +6\ 

Kelly 

Risk Assessment 

M. Lowe, E

Branch 

nvironm

V 

e

N

nta

II 

l Jc en ti ......_ ,.,..... ~~ 

- 0 -

Health Effects Division (7509P) ~ ~f.J ) . I ~ Michael Metzger, Branch Chief V \\. 

Risk Assessment Branch V N II 

Health Effects Division (7509P) 

and 

Matthew Crowley /( .,, Cassi Walls WT u~ Exposure Science Advisory Committee (Ex poSAC) I HED 

Kathryn Montague 

Registration Division (7505P) 

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

occupational and residential exposure and risk assessment for the proposed new use of the 

diglycolamine (DGA) sa lt of dicamba on dicamba-tolerant cotton and soybean, as well as for the 

proposed new BAPMA salt of dicamba for use on conventional crops, inc luding dicambatolerant crops. 

Page I of 36 
lt 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 I. I (PHED 1.1 ); the Agricultural 

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

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

SOPs. 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 October 29, 2015. 

Page 2 of 36 
Page 3 of 36

Table of Contents

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

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

2.1 Data Deficiencies and Requirements ............................................................................... 6

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

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

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

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

5.2 Residential Post-application Exposure/Risk Estimates.................................................. 14

5.3 Residential Risk Estimates for Use in Aggregate Assessment ...................................... 18

6.0 Non-Occupational Spray Drift Exposure and Risk Estimates................................................ 19

7.0 Non-Occupational Bystander Post-Application Inhalation Exposure and Risk Estimates..... 21

7.1 Flux Data........................................................................................................................ 21

7.2 Volatilization Modeling and Risk Assessment .............................................................. 22

7.3 Volatilization Risk Estimates......................................................................................... 23

8.0 Occupational Exposure and Risk Estimates ........................................................................... 23

8.1 Occupational Handler Exposure/Risk Estimates................................................................ 23

8.2 Occupational Post-application Exposure/Risk Estimates .............................................. 27

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

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

Appendix A. Summary of Occupational and Residential Non-cancer Algorithms..................... 29
Page 4 of 36

1.0 Executive Summary

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

exposure and risk assessment for a proposed new use of the diglycolamine (DGA) salt of 

dicamba and the new N, N-Bis-(3-aminopropyl) methylamine (BAPMA) salt of dicamba on 

dicamba-tolerant cotton and soybean. The new dicamba BAPMA salt is also proposed for use on 

several agricultural crops in addition to dicamba-tolerant cotton and soybean. The dicamba DGA 

salt product, M1691 Herbicide, is formulated as a liquid concentrate and contains 56.8% active 

ingredient diglycolamine salt of dicamba (38.5% dicamba acid, or 4 lbs acid equivalent (ae) per 

gallon). The dicamba BAPMA salt product, Engenia® Herbicide, is formulated as a liquid 

concentrate and contains 60.8% active ingredient N,N-Bis-(3-aminopropyl)methylamine salt of 

3,6-dichloro-o-anisic acid (48.38% dicamba acid, or 5 pounds acid equivalent per gallon). The 

label for the DGA salt of dicamba states that mixers, loaders, applicators, and other handlers 

must wear required work attire and chemical-resistant gloves (except for applicators using 

groundboom equipment, pilots or flaggers). The label for the BAPMA salt of dicamba lists 

required work attire and no personal protective equipment (PPE) for all handler activities. The 

restricted entry interval (REI) on the proposed labels is 24 hours.

Occupational handler and post-application exposures are anticipated from the proposed uses of 

dicamba on cotton and soybean, as well as the proposed use of dicamba BAPMA salt on various 

agricultural crops. No residential exposures are anticipated from the proposed uses; however, 

there are existing residential turf uses of dicamba that have been reassessed here to reflect 

updates to the 2012 Residential SOPs. Non-occupational exposures from spray drift and 

bystander volatilization have also been addressed for both dicamba and the BAPMA salt. 

For both dicamba and the BAPMA salt, no dermal assessment was conducted since the dermal 

toxicology studies all had no observed adverse effect levels (NOAELs) of 1000 mg/kg/day. The 

point of departure (POD) for the inhalation route for dicamba was chosen from an inhalation 

study in rats with dicamba acid, with a NOAEL of 0.005 mg/L. The POD for the inhalation 

route for the BAPMA salt was chosen from an inhalation study with BAPMA, with a lowest 

observed adverse effect level (LOAEL) of 0.0014 mg/L. For both dicamba and BAPMA salt, a 

POD for the incidental oral route was chosen from a reproductive study in rats with dicamba 

acid, with a NOAEL of 136 mg/kg/day. 

There are no proposed residential uses at this time for either dicamba or the BAPMA salt; 

however, there are existing residential turf uses of dicamba that have been reassessed in this 

document to reflect updates to HED’s 2012 Residential Standard Operating Procedures (SOPs).

The residential handler and post-application risk estimates are not of concern for dicamba for all 

scenarios and all routes of exposure (i.e., all inhalation MOEs ≥ 30 and all incidental oral MOEs 

≥ 100). 

A quantitative assessment of exposure and risk resulting from spray drift was conducted for the 

BAPMA salt, which results in no risk estimates of concern (i.e., all MOEs ≥ 100) at the field 

edge for aerial and groundboom applications at the maximum agricultural application rate of 1 lb 

ae/A. Since the dicamba residential turf application rate is equal to or higher than the proposed 
Page 5 of 36

uses of dicamba on agricultural crops, the residential turf scenario is protective of any exposure 

via spray drift from the proposed agricultural dicamba applications.

The potential non-occupational exposure to vapor phase dicamba and BAPMA residues emitted 

from treated fields from the proposed uses has been evaluated in this assessment. Volatilization 

modeling was completed using Probabilistic Exposure and Risk model for FUMigants 

(PERFUM) as well as chemical- and formulation-specific flux data. The results indicate that 

volatilization of dicamba and BAPMA from treated crops does occur and could result in 

bystander exposure; however, results of PERFUM modeling indicate that airborne 

concentrations, even at the edge of the treated fields, are not of concern. 

There is no potential hazard via the dermal route for dicamba; therefore, only a quantitative 

inhalation exposure and risk assessment was completed for occupational handlers. The 

occupational handler inhalation risk estimates are not of concern for dicamba DGA salt (i.e., 

MOEs ≥ 30). Most occupational handler inhalation risk estimates are of concern for dicamba 

BAPMA salt (inhalation MOEs < LOC of 300) based on the label-required PPE (i.e., no 

respiratory protection). Some handler risk estimates are of concern despite assuming maximum 

respiratory protection/engineering controls. 

Since there is no potential hazard via the dermal route for dicamba, a quantitative occupational 

post-application dermal risk assessment was not completed. The REI on the proposed labels is 

based on WPS requirements (24 hours). Based on the Agency's current practices, a quantitative 

non-cancer post-application inhalation exposure assessment was not performed for dicamba 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 dicamba.

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 ORETF database; the ARTF database; and the Residential 

SOPs, 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

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

dicamba were reassessed. There were no residential risk estimates of concern for the uses of 

dicamba. 

The occupational handler inhalation risk estimates are not of concern for DGA salt of dicamba

(i.e., MOEs ≥ 30). Most occupational handler inhalation risk estimates are of concern for 

 

1

http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/occupational-pesticide-handler-exposure-data and 

http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/occupational-pesticide-post-application-exposure
Page 6 of 36

dicamba BAPMA salt (inhalation MOEs < LOC of 300) assuming the label-required PPE (i.e.,

no respiratory protection). Some occupational handler risk estimates are of concern despite 

assuming maximum respiratory protection/ engineering controls. 

No quantitative post-application dermal assessment was conducted since a dermal hazard was 

not identified; therefore, the REI on the proposed label is based on the minimum Worker 

Protection Standard (WPS) requirements (24 hours). 

2.1 Data Deficiencies and Requirements

None.

3.0 Hazard Characterization

Acute Toxicity

A summary of the acute toxicity data is included in Table 3.0.1. Dicamba is Acute Toxicity 

Category III or IV via the oral, inhalation or dermal routes of exposure. Dicamba is an eye and 

skin irritant (Toxicity Category II), however, it is not a skin sensitizer.

Table 3.0.1 Acute Toxicity of Dicamba

Guideline 

No. Study Type MRID NO. Results Toxicity Category

870.1100

870.1200

870.1300

870.2400

870.2500

870.2600

Acute Oral

Acute Dermal

Acute Inhalation

Primary Eye Irritation

Primary Skin Irritation

Dermal sensitization

00078444

00241584

00263861

00241584

00237955

00263861

LD50 = 2740 mg/kg

LD50 > 2000 mg/kg

LC50 = >5.3 mg/L

Irritant

Irritant

Non sensitizer

III

III

IV

II

II

N/A

Toxicological PODs Used for Risk Assessment

The toxicological endpoints used to complete residential and occupational exposure assessments 

are summarized in Table 3.0.2 (Dicamba DGA salt) and 3.0.3 (Dicamba BAPMA salt). HED 

recommends that the 10X FQPA Safety Factor (for the protection of infants and children) be 

reduced to 1X for all scenarios, except for the inhalation scenario for dicamba BAPMA salt

which will have a 10X UFL retained for lack of a NOAEL in the inhalation study. 
Page 7 of 36

Table 3.0.2 Toxicological Doses and Endpoints for Dicamba DGA Salt/ Dicamba Acid for use in Human 

Health Risk Assessments

Exposure

Scenario Point of Departure

FQPA SF and Level of 

Concern for Risk 

Assessment

Study and Toxicological Effects

Acute Dietary (Used 

for Granule Ingestion 

Assessment)

(General population 

including infants and 

children

NOAEL = 29 

mg/kg/day

Acute RfD = 0.29 

mg/kg/day

UFA =10x

UFH =10x

FQPA SF = 1X

aPAD = 0.29 mg/kg/day

Dicamba BAPMA 

Rat Developmental Study

Maternal

NOAEL is 29 mg/kg/day in dams 

(20 as Acid form)

LOAEL is 86 mg/kg/day in dams, based 

on ataxia, unsteady gait and convulsions 

(60 as Acid Form)

Developmental

NOAEL > 288 mg/kg/day

(200 as acid equivalent)

Short- (1 - 30 Days) 

and Intermediate- (1-6 

months) Term 

Incidental Oral

Offspring NOAEL= 

136 mg/kg/day

UFA =10x

UFH =10x

FQPA SF = 1X

LOC for MOE = 100

Reproductive study in rats with 

Dicamba Acid.

Offspring LOAEL=450 mg/kg/day based 

on decreased pup weights.

No dermal assessment for dicamba acid since the dermal toxicology studies for dicamba acid, IPA and DGA salts all 

had NOAELs of 1000 mg/kg/day

Short-, Intermediateand Long-Term 

Inhalation

NOAEL=0.005/0.005 

mg/L (M/F)

Residential Handler

HED=0.084 

mg/kg/day

HEC=0.00295 mg/L

Residential Bystander

HEC=0.00053 mg/L

Occupational Handler 

HED=0.21 mg/kg/day

HEC=0.00221 mg/L

UFA =3x

UFH =10x

FQPA SF = 1X

LOC for MOE = 30

Inhalation study in rats with Dicamba 

Acid. 

NOAEL=0.005/0.005 mg/L (M/F)

LOAEL=0.050/0.050 mg/L (M/F), based 

on

minimal multifocal bronchiole-alveolar 

hyperplasia in males; multiple 

microscopic findings in the lung and 

associated lymph nodes in females

Cancer 

(Oral, dermal, 

inhalation)

Dicamba is classified as “not likely to be carcinogenic to humans”.

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. N/A = not applicable.
Page 8 of 36

Table 3.0.3 Toxicological Doses and Endpoints for Dicamba BAPMA Salt for use in Human Health Risk 

Assessments

Exposure

Scenario Point of Departure

FQPA SF and Level of 

Concern for Risk 

Assessment

Study and Toxicological Effects

Short- (1 - 30 Days) 

and Intermediate- (1-6 

months) Term 

Incidental Oral

NOAEL= 136 mg/kg/day

UFA =10x

UFH =10x

FQPA SF = 1X

LOC for MOE = 100

Reproductive study in rats with 

Dicamba Acid.

Offspring LOAEL=450 mg/kg/day 

based on decreased pup weights.

No dermal assessment for the dicamba BAPMA salt since the dermal toxicology studies for dicamba acid, IPA and 

DGA salts all had NOAELs of 1000 mg/kg/day. The dicamba anion component is ~80% of the dicamba BAPMA salt 

weight, so the BAPMA composition is unlikely to significantly influence a dermal study toxicity if this study was 

performed. The acute dermal toxicity for the BAPMA salt was category IV.

Short-, Intermediateand Long-Term 

Inhalation

LOAEL = 0.0014 mg/L

Occupational Handler 

HED=0.020 mg/kg/day

HEC=0.0002 mg/L

Residential Bystander

HEC=0.00005 mg/L

UFA =3x

UFH =10x

UFL = 10X

FQPA SF = 1X

LOC for MOE = 300

Dicamba BAPMA 

Rat Inhalation Study

NOAEL=NA

LOAEL=0.0014 mg/L (LDT), based 

on ulcers in epithelial tissues of the 

larynx and single/multi-focal 

hyperplasia in the larynx

Cancer 

(Oral, dermal, 

inhalation)

Dicamba is classified as “not likely to be carcinogenic to humans”.

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). UFL = use of a LOAEL to extrapolate a NOAEL. FQPA SF = FQPA Safety Factor. PAD = 

population adjusted dose (a = acute, c = chronic). RfD = reference dose. MOE = margin of exposure. LOC = level of concern. 

N/A = not applicable.

Body Weight

Since the inhalation PODs are not based on developmental and/or fetal effects, the body weight 

appropriate for inhalation assessments for adults is 80 kg. The body weight for children 1 to <2 

years old is 11 kg.

4.0 Use Profile 

A summary of use directions for the proposed uses of the DGA salt of dicamba are listed in 

Table 4.1 below. M1691 Herbicide contains 56.8% Dicamba DGA salt (38.5% dicamba, or 4 lb 

ae/gal). The REI on the proposed label is 24 hours and the PPE requirements are that all mixers, 

loaders, applicators and other handlers must wear long-sleeved shirt and long pants, chemicalresistant gloves, and shoes plus socks (no respiratory protection).
Page 9 of 36

Table 4.1. Summary of Directions for New Use of Dicamba DGA salt (EPA Reg. No. 524-582).

Applic. Timing, Type, 

and Equip. Formulation Applic. Rate (lb ae/A)

Max. 

Seasonal 

Applic. Rate 

(lb ae/A)

Use Directions and Limitations

Roundup Ready® 2 Xtend Soybean

Pre-plant, At-planting, 

pre-emergence 

applications

Ground Equipment Only

(Aerial Application 

Prohibited)

M1691 

Herbicide

56.8% 

Dicamba 

DGA salt

(38.5% 

dicamba, 4 lb 

ae/gal)

1 1

The maximum combined quantity of this 

product that may be applied for all pre-plant, 

at-planting, and pre-emergence applications is 

1 lb ae/acre per season

The maximum application rate for a single, 

pre-plant, at-planting or pre-emergence 

application must not exceed 1 lb ae/acre

Post-emergence (incrop) applications 

(emergence to R1 stage 

soybean)

Ground equipment only

(Aerial Application 

Prohibited)

0.5 1

Total of all in-crop applications from 

emergence to beginning bloom (R1) stage 

soybean is 1 lb ae/acre

The maximum rate for any single, in-crop 

application must not exceed 0.5 lb ae/acre

Other restrictions:

Do not apply this product to Roundup Ready® 2 Xtend Soybean using aerial spray equipment

Combined total per year for all applications maximum application rate is 2 lb ae/acre

MON 88701 Cotton

Pre-plant, At-planting, 

pre-emergence 

applications

Ground equipment Only

M1691 

Herbicide

56.8% 

Dicamba 

DGA salt

(38.5% 

dicamba, 4 lb 

ae/gal)

1 1

The maximum rate for all pre-plant, atplanting, and pre-emergence applications is 1 

lb ae/acre per season

The maximum application rate for a single, 

pre-plant, at-planting, or pre-emergence 

application must not exceed 1 lb ae/acre

Post-emergence (incrop) (emergence to 7 

days pre-harvest)

Ground equipment Only

0.5 2

Total of all in-crop applications application 

rate is 2 lb ae/acre

The maximum rate for any single, in-crop 

application must not exceed 0.5 lb ae/acre

Allow at least 7 days between applications

A pre-harvest application of this product may 

be made up to 7 days before harvest

Other restrictions:

Do not apply this product to MON 88701 Cotton using aerial spray equipment

Combined total per year for all applications maximum application rate is 2 lb ae/acre

A summary of use directions for the proposed new product, Engenia® Herbicide, are listed in 

Table 4.2 below. Engenia ® Herbicide contains 60.8% Dicamba BAPMA salt (48.38% dicamba, 

or 5 lb ae/gal). The REI on the proposed label is 24 hours and the label requirements are that all 

mixers, loaders, applicators and other handlers must wear long-sleeved shirt and long pants, 

shoes plus socks. 
Page 10 of 36

Table 4.2. Summary of Directions for New Use of Dicamba BAPMA salt.

Applic. Timing, or 

Type Formulation Applic. Rate (lb ae/A)

Max. 

Seasonal 

Applic. Rate 

(lb ae/A)

Use Directions and Limitations

Asparagus

Post-emergence 

After cutting but 24 

hrs before next 

cutting

Engenia® 

Herbicide

0.5 0.5

Do not apply more than 0.5 lb ae/A per year in 

asparagus

Do not harvest for 24 hours after treatment

Broadcast or spot 

burndown 

treatment, Between 

Crop Application

1 2

Burndown treatment during the fallow period 

following crop harvest and before the 

following crop is planted

Conservation Reserve Program (CRP)

Preplant, 

Post-emergence 

Engenia® 

Herbicide 1 2

Preplant or postemergence

Postemergence application may be made after 

seedling grasses exceed the 3-leaf stage

Do not apply more than 1 lb ae/A per 

application

Do not apply more than 2 lb ae/A per season

Corn

Preplant/ 

Preemergence/ 

Postemergence 

Engenia® 

Herbicide 0.5 1.5

Do not apply more than 0.5 lb ae/A in a single 

application

Do not apply more than 1.5 lb ae/A per 

cropping season

Cotton (non-tolerant)

Preplant, Broadcast Engenia® 

Herbicide 0.25 2

Do not apply more than 0.25 lb ae/A per year 

(single growing season)

Do not apply more than 2 lb ae/A for the 

combination of treatments if applying a spring 

preplant treatment following application of a 

fall preplant (postharvest) treatment

Cotton (tolerant)

Preplant/ 

Preemergent

Engenia® 

Herbicide

1 1

Do not apply more than 1 lb ae/A in a single 

application before crop emergence

Do not apply more than 0.5 lb ae/A in a single 

postemergence application

Do not apply more than a cumulative total of 2 

lb ae/A postemergence over the top

Do not apply more than 2 lb ae/A per year 

(single growing season)

Aerial application is not allowed for preplant, 

preemergence, or postemergence use in 

dicamba-tolerant cotton or soybean

Postemergent 0.5 2

Grass Grown for Seed
Page 11 of 36

Table 4.2. Summary of Directions for New Use of Dicamba BAPMA salt.

Applic. Timing, or 

Type Formulation Applic. Rate (lb ae/A)

Max. 

Seasonal 

Applic. Rate 

(lb ae/A)

Use Directions and Limitations

Seedling grasses/ 

Well-established 

grasses

Engenia® 

Herbicide 1 2

Do not apply more than 1 lb ae/A per 

application or a cumulative total of 2 lb ae/A 

per season

Pasture, Hay, Rangeland, and Farmstead (noncropland) 

Pasture, hay, 

rangeland, 

farmstead, 

noncropland, cutsurface treatment, 

spot treatment

Engenia® 

Herbicide - 1

Do not apply more than 1 lb ae/A during a 

growing season

Do not apply more than 0.5 lb ae/A during a 

growing season on small grain grown for 

pasture and newly seeded areas

Proso Millet 

Broadcast or spot 

treatment when 

proso millet is in 

the 2 to 5 leaf stage

Engenia® 

Herbicide 0.125 0.125

Do not apply more than 0.125 lb ae/A per 

season

For use only within Colorado, Nebraska, 

North Dakota, South Dakota, and Wyoming

Small Grain

Early season

Engenia® 

Herbicide

0.125 0.125: oats 

and triticale

0.375: barley

0.5: wheat

Maximum use rate per application: 0.125 lb 

ae/A for oats and triticale and 0.25 for barley 

and wheat

Do not apply postharvest to oats or triticale 

Fall seeded wheat 0.25

Preharvest 0.25

Sorghum 

Preplant

Engenia® 

Herbicide

0.25

0.5

A preplant application up to 0.25 lb ae/A may 

be applied at least 14 days before planting 

Up to 0.25 lb ae/A may be applied after 

sorghum is in the spike stage but before 

sorghum is 15 inches tall

Up to 0.25 lb ae/A may be applied after 

sorghum has reached the soft-dough stage

May be applied in split applications; preplant 

followed by postemergence or Preharvest, or 

postemergence following by Preharvest. Do 

not apply more than 0.25 lb ae/A per 

application or a maximum cumulative total of 

0.5 lb ae/A per year

Postemergence 0.25

Preharvest 0.25

Soybean (non-tolerant)

Preplant

Engenia® 

Herbicide

0.5

2

Do not apply more than 0.5 lb ae/A in a spring 

application before planting

Do not apply more than 2 lb ae/A per year 

(single growing season)

Preharvest 1

Dicamba-tolerant Soybean

Preplant/ 

Preemergent 

Engenia® 

Herbicide

1 1 Do not apply more than 1 lb ae/A in a single 

application before crop emergence

Do not apply more than 0.5 lb ae/A in a single 

postemergence application

Postemergent –

Prior to first bloom 

growth stage

0.5 1
Page 12 of 36

Table 4.2. Summary of Directions for New Use of Dicamba BAPMA salt.

Applic. Timing, or 

Type Formulation Applic. Rate (lb ae/A)

Max. 

Seasonal 

Applic. Rate 

(lb ae/A)

Use Directions and Limitations

Do not apply more than a cumulative total of 1 

lb ae/A postemergence over the top

Do not apply more than 2 lb ae/A per year

(single growing season)

Aerial application is not allowed for preplant, 

preemergence, or postemergence use in 

dicamba-tolerant cotton or soybean

Sugarcane 

Prior to close-in 

stage of sugarcane

Engenia® 

Herbicide 1 2

Do not apply more than 1 lb ae/A in a single 

application

Do not apply more than a cumulative total of 2 

lb ae/A per growing season

Farmstead Turf (Noncropland) and Sod Farms

Farmstead turf 

(noncropland) and 

sod farms

Engenia® 

Herbicide 0.5 1

Do not apply more than 1 lb ae/A per growing 

season

Do not use on residential sites

5.0 Residential Exposure and Risk Estimates

There are no proposed residential uses at this time for either the dicamba acid or the dicamba 

BAPMA salt; however, there are existing residential uses of dicamba that have been reassessed 

in this document to reflect updates to HED’s 2012 Residential SOPs2along with policy changes 

for body weight assumptions. The revision of residential exposures will impact the human 

health aggregate risk assessment for dicamba. The proposed new BAPMA salt of dicamba does 

not impact the residential assessment as there are no proposed uses of dicamba BAPMA that 

would result in residential exposure; therefore, only the registered uses of dicamba have been 

reassessed in this document. 

Registered uses of dicamba include solid products and liquid products in concentrates, granules

or ready-to-use sprays for use as spot and broadcast treatments on turf.

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.

 

2 Available: http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/standard-operating-procedures-residentialpesticide
Page 13 of 36

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

following lawn/turf application scenarios: 

 Mix/Load/Apply Liquids with Hand-held Equipment

 Apply Ready-To-Use Sprays with Hand-held Equipment

 Load/Apply Granules with Hand-held Equipment

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 maximum application rate for residential products on turf is 1 lb ae/acre.

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 SOPs3.

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. 

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.

Combining Exposures/Risk Estimates:

There is no potential hazard via the dermal route for dicamba. Only inhalation risk estimates 

were quantitatively assessed. 

Summary of Residential Handler Non-Cancer Exposure and Risk Estimates

The residential handler risk estimates are not of concern for dicamba (Inhalation MOEs > LOC 

of 30) for all scenarios.

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

Exposure Scenario Level of 

Concern

Inhalation Unit 

Exposure (mg/lb 

ai)

Maximum 

Application 

Rate1

Area Treated or 

Amount Handled 

Daily2

Inhalation

Dose 

(mg/kg/day)5 MOE6

Mixer/Loader/Applicator

Lawns/Turf, Liquid, Hose-end Sprayer

30

0.022

1 lb ae/acre 0.5 acres 0.00014 510

Lawns/Turf, Liquid, Sprinkler Can 0.000023 lb 

ae/ft2 1000 ft2 0.0000063 11,000

Lawns/Turf, Liquid, Manuallypressurized handwand 0.018

0.05 lb ae/gallon 5 gallons

0.000056 1,200

Lawns/Turf, Liquid, Backpack 0.14 0.00044 160

 

3 Available: http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/standard-operating-procedures-residentialpesticide
Page 14 of 36

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

Exposure Scenario Level of 

Concern

Inhalation Unit 

Exposure (mg/lb 

ai)

Maximum 

Application 

Rate1

Area Treated or 

Amount Handled 

Daily2

Inhalation

Dose 

(mg/kg/day)5 MOE6

Lawns/Turf, RTU, Hose-end Sprayer 0.034 1 lb ae/acre 0.5 acres 0.00021 330

Lawns/Turf, Granule, Push-type rotary 

spreader 0.0026 1 lb ae/acre 0.5 acres 0.000016 4,300

Lawns/Turf, Granule, Belly grinder 0.039

0.000023 lb 

ae/ft2

1200 ft2 0.000013 5,200

Lawns/Turf, Granule, Spoon 0.087

100 ft2

0.0000025 28,000

Lawns/Turf, Granule, Cup/Shaker Can 0.013 0.00000037 190,000

Lawns/Turf, Granule, Hand Dispersal 0.38 0.000011 6,400

Liquid = Liquid concentrate; RTU = Ready-to-use

1 Based on registered uses. Application rate is 1 lb ae/acre. 1 lb ae per acre with an assumed minimum of 20 gallons used per 

acre = 0.05 lb ae/gal; 1 lb ae/acre * 1 acre/43560 ft2 = 0.0000344 lb ae/ft2

2 Based on HED’s 2012 Residential SOPs (http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/standardoperating-procedures-residential-pesticide).

5 Inhalation Dose = Inhalation Unit Exposure (mg/lb ai) × Application Rate (lb ai/area or volume) × Area Treated or Amount 

Handled (area/day or volume/day) ÷ Body Weight (80 kg).

6 Inhalation MOE = Inhalation NOAEL (0.084 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 dicamba. The quantitative exposure/risk 

assessment for residential post-application exposures is based on the following scenarios: 

 Children (1 to < 2 years old) incidental oral exposure to treated turf.

 Children (1 to < 2 years old) episodic granular ingestion exposure.

Assessment of post-application exposure to liquid formulations is protective of exposure to solid 

formulations, except for the episodic granular ingestion scenario which was quantitatively 

assessed.

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

Appendix in the 2012 Residential SOPs4. These lifestages are not the only lifestages that could 

be potentially exposed for these post-application scenarios; however, the assessment of these 

lifestages is health protective for the exposures and risk estimates for any other potentially 

exposed lifestages.

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 

SOPs and can be found in Appendix A. In addition to the standard assumptions, chemicalspecific turf transferable residue data (TTR) are available for dicamba and have been used in risk 

assessment. These data are summarized briefly below. 

 

4 Available: : http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/standard-operating-procedures-residentialpesticide
Page 15 of 36

Turf Transferable Residue Data

There are chemical-specific turf transferable residue (TTR) data available for dicamba; these 

data are described below.

MRID 44655702 (Reviewed in Memo, A. Lamay, D410014, 14-MAR-2013): This study 

measured the transferable turf residue (TTR) of 2,4-D 2-EHE, 2,4-D, MCPA 2-EHE, 

MCPA, 2,4-DP 2-EHE, 2,4-DP, MCPP, and dicamba from turf treated with emulsifiable 

concentrate/liquid formulations. The trial was conducted at one location (Franklin County, 

North Carolina), consisting of 10 established turf plots, including one control plot (TRT1) 

and one plot for each of the test substances (TRT2 – TRT9). Samples were collected 

from treated plots using the modified California Roller technique at the following time 

points: before the application; at 3 and 8-12 hrs after the application; and then at 1, 2, 3, 

4, 5, 6, 7, 10, and 14 days after the application. This study was reviewed by HED and 

found to be acceptable for risk assessment purposes. A summary of the dicamba residue 

data and the regression analysis is presented below in Table 5.2.1. The predicted day 0 

residue from the regression analysis is 0.055 μg/cm2; this residue is equivalent to 0.275 

μg/cm2 when adjusted from the study rate of 0.2 lb ae/acre for the maximum application 

rate of 1 lb ae/acre.

Table 5.2.1. Dicamba Summary of TTR Data and Regression Analysis (MRID 

44655702)

Statistic TRT9 – Dicamba

Application Rate (lb ae/A) 0.2

Peak TTR (μg/cm2) 0.051

Time Interval Of Peak TTR 8-12 hr after application

Measured Average Day 0 Residue (μg/cm2) 0.018

Predicted Day 0 Residue (μg/cm2) 0.055

Slope -2.28

Half-life (days) 0.31

R

2 0.884

MRID 45033101 (Reviewed in Memo, A. Lamay, D410012, 14-MAR-2013): This study 

was designed to determine the TTR of 2,4-D, MCPA, MCPP, dicamba, and 2,4-DP from

turf treated with liquid formulations. Trials were conducted at two locations in the 

United States (Tulare County, California and Dane County, Wisconsin), with each site 

consisting of five established turf plots, including one control plot (TRT1) and one 

treated plot for each of the test substances (TRT2 – TRT5). Transferable residues were 

collected from the treated plots using the modified California Roller technique at the 

following time points: before the application; at 1, 4, 8, and 12 hrs after the application;

and then at 1, 2, 3, 4, and 7 days after the application. A regression analysis was not 

performed due to the nature of the dissipation pattern. Lower residues occurred at the 

Wisconsin site likely due to rainfall during sampling; no rain occurred at the California 

site. Data at 12 hr after application at the California test site was taken out of the analysis 

as there was dew at this time point.
Page 16 of 36

Table 5.2.2. Dicamba Summary of TTR Data and Regression Analysis (MRID 

45033101)

Statistic TRT4 – California TRT4 – Wisconsin

Application Rate (lb ae/A) 0.21 0.21

Peak TTR (μg/cm2) *

0.1595

Not including 12 hr 

time point: 0.022

0.0258

Time Interval Of Peak TTR *

12hr after application

Not including 12hr 

time point: 1 hr after 

application

8hr after application

*Peak determined without the residue value at 12 hr after application at the California site as there was dew at this 

time point.

MRID 44655703 (Reviewed in Memo, A. Lamay, D410013, 14-MAR-2013): This study 

was designed to determine the TTR of 2,4-D, MCPP, and dicamba from turf treated with 

a suspension concentrate/liquid (SC/L) formulation at one location (Franklin County, 

NC) when applied using various spray volumes. The treated plots were treated with EH1358 mixed to achieve a target spray volume of 2, 5, and 20 gallons per acre (GPA) for 

treatments 2,3 and 4 respectively. Transferable residues were collected using the 

modified California Roller technique before and after application and up to 14 days 

following application. This study was reviewed by HED and found to be acceptable for 

risk assessment purposes. A summary of the dicamba residue data and the regressions 

analysis is presented below in Table 5.2.3. The predicted day 0 residues from the 

regression analyses are 0.036 μg/cm2, 0.041 μg/cm2, and 0.032 μg/cm2for treatments 2, 3 

and 4, respectively; these residues are equivalent to 0.16 μg/cm2, 0.18 μg/cm2, and 0.14 

μg/cm2for treatments 2, 3, and 4, respectively when adjusted from the study rate of 0.22 

lb ae/acre for the maximum application rate of 1 lb ae/acre.

Table 5.2.3. Dicamba Summary of TTR Data and Regression Analysis (MRID 

44655703)

Statistic TRT2 – 2 GPA TRT3- 5 GPA TRT4- 20 GPA

Application Rate (lb ae/A) 0.222 0.222 0.218

Peak TTR (μg/cm2) 0.036 0.036 0.028

Time Interval Of Peak TTR 1DAT 0DAT 8-12hr after 

application

Measured Average Day 0 

Residue (μg/cm2)

0.027 0.036 0.020

Predicted Day 0 Residue

(μg/cm2)

0.036 0.041 0.032

Slope -1.81 -2.15 -2.09

Half-life (days) 0.38 0.32 0.33

R

2 0.623 0.935 0.943

MRID 44959001: This study measured dicamba TTR after a soluble concentrate 

formulation in water was applied to turf at a single application rate of 1 lb ae/acre at three 

test sites in Florida, California, and Pennsylvania. Transferable residues were collected 

using the modified California Roller technique at each location immediately before and 

after each application; 4 hours, 8 hours, 24 hours, 36 hours, 48 hours, 60 hours after 

application as well as 3, 5, and 7 days after treatment (DAT). This study was reviewed 
Page 17 of 36

by HED and found to be acceptable for risk assessment purposes. A summary of the 

dicamba residue data and the regression analysis is presented below in Table 5.2.4. 

Treatment 2 results from the Pennsylvania site were not included in this summary as the 

plot was irrigated and the linear regression of the data had an R-squared value of 

0.00594, and thus could not be used to calculate a half-life. The predicted day 0 residues 

from the regression analyses are 0.13 μg/cm2, 0.15 μg/cm2, and 0.13 μg/cm2for the 

Florida, California, and Pennsylvania locations, respectively.

Table 5.2.4. Dicamba Summary of TTR Data and Regression Analysis (MRID 

44959001)

Statistic Florida – No 

Irrigation

California- No 

Irrigation

Pennsylvania 

TRT1 – No 

Irrigation

Application Rate (lb ae/A) 1 1 1

Peak TTR (μg/cm2) 0.29 0.135 0.13

Time Interval Of Peak TTR 8 hr after 

treatment 0DAT 4 hr after treatment

Predicted Day 0 Residue

(μg/cm2)

0.126 0.15 0.128

Slope -1.6 -0.62 -0.46

Half-life (days) 0.43 1.1 1.5

R

2 0.58 0.95 0.93

Conclusion

The highest adjusted predicted day 0 residue for dicamba was from MRID 44655702. 

The predicted day 0 residue from the regression analysis is 0.055 μg/cm2; this residue is 

equivalent to 0.275 μg/cm2 when adjusted for the maximum application rate of 1 lb 

ae/acre. However, MRID 44959001 was conducted at the maximum application rate

being assessed, with predicted residues of approximately 0.15 μg/cm2consistently 

measured in three different site locations; therefore, HED has determined it is 

scientifically valid to use the results from this study for risk assessment purposes. 

Episodic Granular Ingestion Assumptions: It should be noted that the standard assumption for 

granule ingestion rate per day for dicamba has been adjusted from the recommended 2012 

Residential SOP value due to product-specific information available. The default ingestion rate 

for dry pesticide formulations (e.g., pellets and granules) is 0.3 gram/day for children 1 < 2 years 

old in the 2012 Residential SOPs. It is assumed that if 150 pounds of product were to be applied 

to a 1⁄2 acre lawn, the amount of product per square foot would be approximately 3 g/ft2and a 

child would consume one-tenth of the product available in a square foot. The maximum 

application rate for dicamba on lawns is 1 lb ae/acre, and the maximum percent of active 

ingredient in dry formulation is 1%, therefore, the maximum amount of product to treat an acre is 

100 pounds; or a maximum of 50 pounds of product to treat a half-acre. Therefore, the point 

estimate for granular ingestion rate has been reduced by a third to 0.1 grams/day (see Appendix 

A). 

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 SOPs.
Page 18 of 36

Combining Exposure and Risk Estimates

There is no potential hazard via the dermal route for dicamba. Only incidental oral risk estimates 

were quantitatively assessed. The incidental oral scenarios (i.e., hand-to-mouth and object-tomouth) should be considered inter-related and it is likely that they occur interspersed amongst 

each other across time. The granular ingestion scenario is not combined as this exposure would

not occur as a result of routine behavior and is considered an episodic event related to poisoning. 

Therefore, no post-application exposure scenarios were combined for children 1 < 2 years old. 

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

The residential post-application risk estimates are not of concern for dicamba. MOEs are greater 

than the level of concern of 100 for incidental oral scenarios and episodic ingestion. All 

scenarios are short-term exposures, except episodic granular ingestion which is an acute 

scenario. Incidental soil ingestion scenario is short-term exposure only as the soil half-life for 

dicamba is 18 days (EFED memo, I. Maher, D378447, 11/22/10).

Table 5.2.1. Residential Post-application Non-cancer Exposure and Risk Estimates for Dicamba.

Lifestage

Post-application Exposure Scenario Application 

Rate1

TTR 

(ug/cm2)

2

Dose 

(mg/kg/day)

MOE

(LOC = 100)3 Use Site Route of Exposure

1 to < 2 

years old

Turf - liquid

Hand-to-Mouth

1 lb ae/acre 0.15

0.02055 6,600

Object-to-Mouth 0.00062 220,000

Soil Ingestion 0.000034 4,000,000

Turf- Granular Episodic Granular Ingestion 1% ai 0.27 320A

1 Based on registered uses (reference: 2005 RED).

2 TTR based on MRID 44959001.

3 MOE = Incidental oral POD (136 mg/kg/day) ÷ Dose (mg/kg/day) for hand-to-mouth, object-to-mouth, and soil ingestion scenarios. 

LOC = 100. 

A Ingestion of granules is considered episodic in nature; MOE was calculated using the acute dietary POD (29 mg/kg/day) and 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 dicamba. Inhalation exposures are not included in the aggregate assessment since 

effects from the inhalation route are not systemic/cannot be aggregated. Post-application episodic 

granular ingestion following applications to lawns and turf are not included in the aggregate 

assessment as this exposure would not occur as a result of routine behavior and is considered an 

episodic event related to poisoning. There is no recommended residential exposure for use in the 

adult aggregate assessment since there is no hazard via the dermal route of exposure and 

inhalation exposures are not included, as described above. Therefore, the only residential 

exposures recommended for the dicamba aggregate assessment are the following:

 The recommended residential exposure for use in the children (1 to <2 years old) 

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

scenario (i.e., post-application exposure to treated turf).
Page 19 of 36

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

Lifestage Exposure 

Scenario

Dose (mg/kg/day)1 MOE2

Dermal Inhalation Oral Total Dermal Inhalation Oral Total

Child

Hand-toMouth 

Postapplication 

Exposure –

Treated 

Turf

N/A N/A 0.02055 0.02055 N/A N/A 6,600 6,600

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

(where applicable).

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

Oral MOE), where applicable.

6.0 Non-Occupational Spray Drift Exposure and Risk Estimates

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 indirect 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 is based 

on a premise of compliant applications which, by definition, should not result in direct exposures 

to individuals because of existing label language and other regulatory requirements intended to 

prevent them.5 Direct exposures would include inhalation of the spray plume or being sprayed 

directly. Rather, the exposures addressed here are thought to occur indirectly through contact 

with impacted areas, such as residential lawns, when compliant applications are conducted. 

Given this premise, 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 indirect 

exposure are the focus of this analysis analogous to how exposures to turf products are 

considered in risk assessment. 

Dicamba: Several dicamba products have existing labels for use on turf, thus it was considered 

whether the risk assessment for that use may be considered protective of any type of exposure 

that would be associated with spray drift. It should be noted that the registered residential uses 

on turf result in exposure greater than potential exposure from spray drift; therefore, no new 

residential assessment needs to be completed. 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 proposed maximum single 

application rate of dicamba is 1 lb ae/A. The highest degree of spray drift noted for any 

application method immediately adjacent to a treated field (Tier 1 output from the aerial 

 

5 This approach is consistent with the requirements of the EPA’s Worker Protection Standard which, 

when included on all labels, precludes direct exposure pathways.
Page 20 of 36

application using fine to medium spray quality) results in a deposition fraction of 0.26 of the 

application rate. A quantitative spray drift assessment for dicamba is not required because the 

maximum application rate to 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 ae/A6for any

dicamba products. The turf post-application MOEs have been previously assessed and are based 

on the revised SOPs for Residential Exposure Assessment (i.e., see above in Section 6.2).

BAPMA salt: In order to evaluate the drift potential and associated risks for the BAPMA salt, an 

approach based on drift modeling coupled with techniques used to evaluate residential uses of 

pesticides was utilized. Essentially, a residential turf assessment based on exposure to deposited 

residues has been completed to address drift from the agricultural applications of the BAPMA 

salt. In the spray drift scenario, the deposited residue value was determined based on the amount 

of spray drift that may occur at varying distances from the edge of the treated field using the 

AgDrift (v2.1.1) model and the Residential Exposure Assessment Standard Operating 

Procedures Addenda 1: Consideration of Spray Drift Policy. Once the deposited residue values 

were determined, the remainder of the spray drift assessment was based on the algorithms and 

input values specified in the recently revised (2012) Standard Operating Procedures For 

Residential Risk Assessment (SOPs). 

A screening approach was developed based on the use of the AgDrift model in situations where 

specific label guidance that defines application parameters is not available.7 AgDrift is 

appropriate for use only when applications are made by aircraft, airblast orchard sprayers, and 

groundboom sprayers. When AgDrift was developed, a series of screening values (i.e., the Tier 

1 option) were incorporated into the model and represent each equipment type and use under 

varied conditions. The screening options specifically recommended in this methodology were 

selected because they are plausible and represent a reasonable upper bound level of drift for 

common application methods in agriculture. These screening options are consistent with how 

spray drift is considered in a number of ecological risk assessments and in the process used to 

develop drinking water concentrations used for risk assessment. In all cases, each scenario is to 

be evaluated unless it is not plausible based on the anticipated use pattern (e.g., herbicides are 

not typically applied to tree canopies) or specific label prohibitions (e.g., aerial applications are 

not allowed). 

The spray drift risk estimates are based on an estimated deposited residue concentration as a 

result of the screening level agricultural application scenarios. BAPMA salt is proposed for used 

on numerous agricultural crops and can be applied via aerial and groundboom equipment. The 

recommended drift scenario screening level options are listed below: 

 Groundboom applications are based on the AgDrift option for high boom height and 

using very fine to fine spray type using the 90th percentile results. 

 Aerial applications are based on the use of AgDrift Tier 1 aerial option for a fine to 

medium spray type and a series of other parameters which will be described in more 

detail below (e.g., wind vector assumed to be 10 mph in a downwind direction for entire 

application/drift event).

 

6 1 lb ae/A x 0.26 ≤ 1 lb ae/A

7http://www.agdrift.com/ 
Page 21 of 36

Only incidental oral risk estimates were estimated since there is not dermal hazard for the 

BAPMA salt. The total applicable LOC is 100 so MOEs < 100 would be of concern. Children’s 

(1<2 year old) incidental oral risk estimates from indirect exposure to dicamba BAPMA salt 

related to spray drift result in no risk estimates of concern at the field edge for groundboom and 

aerial applications (i.e., all MOEs ≥ 35,000).

Table 6.0.1. Non-occupational Risk Estimates Resulting from Spray Drift for BAPMA Salt.

Crop/Rate Group Spray Type/ Nozzle 

Configuration 

Application 

Rate (lb ai/A)

Estimated TTRt

(ug/cm2)

a

HtM MOE at 

Field Edge

Aerial Fine to Medium

1 0.11115

 35,000 

Groundboom High Boom Very fine to Fine 48,000 

a. TTR = Application Rate × F × (1-D)t × 4.54E8 μg/lb × 2.47E-8 acre/cm2.

7.0 Non-Occupational Bystander Post-Application Inhalation Exposure and Risk Estimates

The potential exposure to bystanders from vapor phase dicamba and BAPMA salt residues 

emitted from treated fields has been evaluated for the proposed uses of dicamba on dicambatolerant corn and soybean, and for the proposed uses of BAPMA on various agricultural crops. 

Bystander exposure to dicamba and BAPMA emitted from treated fields depends on two main 

factors: 1) the rate at which these chemicals come off a treated field (described as the offgassing, emission or flux), and 2) how those vapors are dispersed in the air over and around the 

treated field. Volatilization can occur during the application process or thereafter. It can result 

from aerosols evaporating during application, while deposited sprays are still drying (e.g., 

possibly via co-distillation), or after as dried deposited residues volatilize. 

This assessment employs approaches EPA has used previously to assess inhalation exposures to 

fumigant pesticides8and is also consistent with the recommendations of the December 2009 

Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP)9 meeting 

on the scientific issues associated with field volatilization of conversional (semi-volatile) 

pesticides.

7.1 Flux Data 

A submitted flux study10 was reviewed by the Environmental Fate and Effects Division (EFED), 

which estimated the flux of dicamba vapors after spray application of the DGA salt formulation. 

The dicamba DGA salt formulation was used alone without any tank adjuvants, and the test 

 

8 U.S. EPA 2004d. FIFRA Science Advisory Panel Meeting Minutes - Fumigant Bystander Exposure Model Review: 

Probabilistic Exposure and Risk Model for Fumigants (PERFUM) Using Iodomethane as a Case Study. Available at 

http://www.epa.gov/scipoly/sap/meetings/2004/august1/august2425minutes.pdf

9 U.S. EPA 2009. FIFRA Science Advisory Panel Meeting Minutes - Scientific Issues Associated with Field Volatilization of 

Conventional Pesticides. Available at http://www.epa.gov/scipoly/sap/meetings/2009/december/120309meetingminutes.pdf

10 Memo, D411382, W. Eckel. MRID 49022501. Sall, E.; Smith, H.; Findley, D.; et al. (2013) Measurement of the Volatile Flux 

of Dicamba under Field Conditions using the Theoretical Profile Shape Method. Project Number: RPN/2012/0662, 

MSL0024798. Unpublished study prepared by Monsanto Company. 52p.
Page 22 of 36

surface was zoysiagrass. The trial was performed in August 2012 near Columbia, IL, and 

experienced minimum and maximum temperatures of 21.1oC and 26.2oC, respectively. 

A circle in the zoysiagrass with a diameter of 40 m (~131 ft) was sprayed with a tank mix of 32 

oz/A (1.0 lb a.e./A) Clarity® (EPA Reg. # 7969-137). Herbicide treatments were applied using a 

nitrogen pressurized backpack sprayer calibrated to deliver 10 gallons per acre (GPA) at 50 PSI 

using TeeJet® TTI 110015 spray tips. Application of the test substance was made approximately 

perpendicular to the prevailing wind direction. In the test plot, three air samplers and an 

anemometer were placed in the treatment area after post-application drift was allowed to settle 

(typically 2-5 minutes). Data were collected for 0-6 hours after application. 

The field test method employed was the Theoretical Profile Shape (TPS) method which calls for 

circular spray plots of a certain diameter, with air sampling and wind velocity measurements 

acquired at the center of the circle at a certain, single height determined by the circle size and the 

surface roughness. A short description of the TPS method and calculations is provided in an 

Appendix of the study report. 

The estimated 6 hr average flux from the Clarity® application on zoysiagrass was 0.4 (+/- 0.1) 

ng/m2/sec, representing 0.008% of the application rate. Quantitative analysis using the estimated 

flux rate derived from this study is described below.

While the flux data are specific to the DGA salt of dicamba, it is considered protective for the 

BAPMA salt form of dicamba as well. BAPMA is considered less volatile than the DGA salt 

and, therefore, would be expected to result in lower air concentrations as a result of flux from a 

treated field. Based on modeling data using EPISuite and information provided in a BASF 

patent11, the volatility of the BAPMA salt is lower than that of the DGA salt. EPISuite estimated 

the vapor pressure of the DGA salt as 1.48E-11 mmHg at 25oC, and for BAPMA as 1.10E-21 

mmHg at 25oC. The BASF patent provides a relative ranking of the volatility of the various 

forms of dicamba (compared to the acid at 100%), with the BAPMA salt being 0.5% of the 

volatility of the dicamba acid and the DGA salt being 5.4% of the dicamba acid. Therefore, 

HED believes that the volatilization assessment conducted using the flux data for the DGA salt is 

protective of the BAPMA salt. 

7.2 Volatilization Modeling and Risk Assessment

Exposure modeling for a single day was completed using Probabilistic Exposure and Risk model 

for FUMigants (PERFUM). There are a variety of factors that potentially affect the emission 

rates of dicamba and subsequent offsite transport including: field condition (bare soil, growing or 

mature crop canopy), field parameters (soil type, moisture, etc.), formulation type, 

meteorological conditions, and application scenario (rate, method). The flux estimate from the 

study (0.0004 ug/m2/s), a single 40A field, and the Bradenton, FL meteorological data were used 

with PERFUM to estimate risk based on the dicamba field volatility study summarized in 

Section 7.1. 

 

11 Low volatile amine salts of anionic pesticides. USPTO Application: #20150210723. 

http://images3.freshpatents.com/pdf/US20150210723A1.pdf 
Page 23 of 36

The short-term residential inhalation endpoints for dicamba and BAPMA were used in the 

volatilization assessment (dicamba acid: 530 ug/m3and LOC of 30; BAPMA salt: 50 ug/m3; 

LOC = 300). This is considered a conservative assumption to compare the day 1 volatilization 

exposure to a short-term HEC. Furthermore, a 6-hour exposure averaging period was used in the 

model; it is a conservative assumption to compare the 6 hour average exposure from the model to 

the HEC calculated for 24 hours of exposure especially since the 6 hour exposure period used as 

the basis for the comparison represents the peak emissions period after application.

All of the files associated with the use of PERFUM in this assessment can be provided upon 

request. These files could be used to examine the detailed input and output files for each 

permutation of the model completed for this analysis. 

7.3 Volatilization Risk Estimates

The field volatility study suggests that volatilization of dicamba and BAPMA from treated crops 

does occur and could result in bystander exposure. Results of PERFUM modeling, however,

indicate that airborne concentrations, even at the edge of the treated fields, are not of concern. 

The maximum proposed application rate of 1 lb a.e./A was assessed. There were no whole field 

and maximum field buffers estimated using PERFUM (i.e., risks were acceptable at all 

percentiles of exposure at the edge of a treated field). 

8.0 Occupational Exposure and Risk Estimates

8.1 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 for the dicamba 

DGA salt uses is based on the following scenarios: 

 Mixing/loading liquid in support of groundboom application to high-acreage crops

(cotton and soybean)

 Applying spray by groundboom equipment to high acreage crops (cotton and soybean)

The quantitative exposure/risk assessment developed for occupational handlers for the dicamba 

BAPMA salt uses is based on the following scenarios: 

 Mixing/loading liquid in support of aerial application to sod, typical field crops 

(asparagus), and high-acreage crops (corn, soybean, cotton, sugarcane)
Page 24 of 36

 Mixing/loading liquid in support of groundboom application to sod, typical field crops 

(asparagus), and high-acreage crops (corn, soybean, cotton, sugarcane)

 Applying spray by aerial equipment to sod, typical field crops, and high-acreage crops

 Applying spray by groundboom equipment to sod, typical field crops, and high-acreage 

crops

 Flagging in support of aerial application to sod, typical field crops, and high-acreage 

crops

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 maximum single application rate for tolerant soybean and cotton is 1 lb ae/acre. See Table 

4.1 for a summary of use directions.

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

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

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

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

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

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

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

Exposure Surrogate Reference Table12”, 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 website13. 

Area Treated or Amount Handled: 

Based on ExpoSAC Policy 9.1:

 The area treated for groundboom application to sod and typical field crops is 80 acres per 

day and to high acreage crops is 200 acres per day.

 The area treated for aerial application to sod and typical field crops is 350 acres per day 

and to high acreage crops is 1200 acres per day.

 

Exposure Duration: 

HED classifies exposures from 1 to 30 days as short-term and exposures 30 days to six months 

as intermediate-term. Exposure duration is determined by many things, including the exposed 

population, the use site, the pest pressure triggering the use of the pesticide, and the cultural 

practices surrounding that use site. For most agricultural uses, it is reasonable to believe that 

occupational handlers will not apply the same chemical every day for more than a one-month 

time frame; however, there may be a large agribusiness and/or commercial applicators who may 

apply a product over a period of weeks (e.g., completing multiple applications for multiple 

clients within a region). 

 

12 Available: http://www2.epa.gov/sites/production/files/2015-09/documents/handler-exposure-table-2015.pdf

13 Available: http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/occupational-pesticide-handler-exposure-data
Page 25 of 36

For dicamba, based on the proposed use, short- and intermediate-term exposures are expected as 

the product can have multiple applications to the crop throughout the season and applicators may 

apply the product to multiple farms throughout the growing season. 

Mitigation/Personal Protective Equipment: Estimates of inhalation exposure were calculated for 

various levels of personal protective equipment (PPE) or engineering controls. Results are 

presented for “baseline,” defined as no respirator, as well as with various levels of respiratory 

protection. The dicamba product labels currently do not require respiratory protection.

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:

There is no potential hazard via the dermal route for dicamba. Only inhalation risk estimates 

were quantitatively assessed. 

Summary of Occupational Handler Non-Cancer Exposure and Risk Estimates

DGA salt of dicamba: The occupational handler risk estimates are not of concern for dicamba 

acid (inhalation MOEs > LOC of 30) for all scenarios with label required PPE (i.e., no 

respiratory protection). See Table 8.1.1 below.

Table 8.1.1. Occupational Handler Non-Cancer Exposure and Risk Estimates for Dicamba acid (DGA salt). 

Exposure Scenario Crop or Target

Inhalation Unit Exposure 

(μg/lb ai)1 Maximum 

Application 

Rate2

Area 

Treated or 

Amount 

Handled 

Daily3

Inhalation

(LOC = 30)

Baseline Mitigation Level

(No Respiratory Protection 

Unless Otherwise Specified)

Dose 

(mg/kg/day)4 MOE5

Mixer/Loader

Mixing/Loading Liquid in Support 

of Groundboom Application High Acreage Crops 0.219 1 lb ae/acre 200 acres 0.000548 380

Applicator

Applying Spray by Groundboom 

Application High Acreage Crops 0.34 1 lb ae/acre 200 acres 0.00085 250

1 Based on the “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table” (September 2015).

2 Based on proposed label (Reg. No. 524-582).

3 Exposure Science Advisory Council Policy #9.1.

4 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).

5 Inhalation MOE = Inhalation POD (0.21 mg/kg/day) ÷ Inhalation Dose (mg/kg/day).

BAPMA salt of dicamba: Most occupational handler risk estimates are of concern for dicamba 

BAPMA salt (inhalation MOEs < LOC of 300) based on label-required PPE (i.e., no respiratory 

protection). See Table 8.1.2 for a summary of handler risk estimates below. A summary of 

handler risk estimates with additional inhalation PPE/ engineering controls to mitigate risks is 

provided in Table 8.1.3; some handler risk estimates are still of concern with the maximum PPE/ 
Page 26 of 36

engineering controls. Note that HED has no data to assess exposures to pilots using open 

cockpits. The only data available is for exposure to pilots in enclosed cockpits (i.e., engineering 

controls). Therefore, in both tables, aerial applicator risk estimates are shown representing the 

use of engineering controls.

 

Table 8.1.2. Occupational Handler Non-Cancer Exposure and Risk Estimates for Dicamba BAPMA (Label Required PPE = No 

Respirator). 

Exposure Scenario Crop or Target

Inhalation Unit Exposure 

(μg/lb ai)1

Maximum 

Application 

Rate2

Area Treated 

or Amount 

Handled 

Daily3

Inhalation

Baseline Mitigation Level 

(No Respiratory Protection 

Unless Otherwise 

Specified)

Dose 

(mg/kg/day)4

MOE

(LOC = 300)5

Mixer/Loader

Mixing/Loading Liquid in 

Support of Aerial 

Application

Sod

0.219

0.5 lb ae/A 350 acres 0.000479 42

Typical Field Crops

1 lb ae/A

350 acres 0.000959 21

High Acreage Field 

Crops 1200 acres 0.00329 6.1

Mixing/Loading Liquid in 

Support of Ground boom 

Application

Sod 0.5 lb ae/A 80 acres 0.00011 180

Typical Field Crops

1 lb ae/A

80 acres 0.000219 91

High Acreage Crops 200 acres 0.000548 36

Applicator

Applying Spray via Aerial 

Application

Sod

Engineering Control: 

0.0049

0.5 lb ae/A 350 acres 0.0000107 1,900

Typical Field Crops

1 lb ae/A

350 acres 0.0000215 930

High Acreage Field 

Crops 1200 acres 0.0000735 270

Applying Spray by Ground 

boom Application

Sod

0.34

0.5 lb ae/A 80 acres 0.00017 120

Typical Field Crops

1 lb ae/A

80 acres 0.00034 59

High Acreage Crops 200 acres 0.00085 24

Flagger

Flagging in support of 

Aerial Application

Sod

0.35

0.5 lb ae/A

350 acres

0.000766 26

Typical Field Crops

1 lb ae/A

0.00154 13

High Acreage Field 

Crops 0.00154 13

1 Based on the “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table” (March 2016).

2 Based on proposed label (7969-GUL).

3 Exposure Science Advisory Council Policy #9.1.

4 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).

5 Inhalation MOE = Inhalation POD (0.02 mg/kg/day) ÷ Inhalation Dose (mg/kg/day).
Page 27 of 36

Table 8.1.3. Occupational Handler Non-Cancer Exposure and Risk Estimates for Dicamba BAPMA (with additional respiratory 

protection).

Exposure Scenario Crop or Target

Inhalation Unit 

Exposure (μg/lb ai)1 Maximum 

Application 

Rate2

Area 

Treated or 

Amount 

Handled 

Daily3

Inhalation MOE

(LOC = 300)4

Mitigation Level PF5 PF10 Eng. Control

Mixer/Loader

Mixing/Loading Liquid in 

Support of Aerial 

Application

Sod

PF5: 0.0438

PF10: 0.0219

EC: 0.083

0.5 lb ae/A 350 acres 210 420 110

Typical Field Crops

1 lb ai/A

350 acres 100 210 55

High Acreage Field Crops 1200 acres 30 61 16

Mixing/Loading Liquid in 

Support of Ground boom 

Application

Sod 0.5 lb ae/A 80 acres 910 1.800 480

Typical Field Crops

1 lb ae/A

80 acres 460 910 240

High Acreage Crops 200 acres 180 360 96

Applicator

Applying Spray via Aerial 

Application

Sod

EC: 0.0049

0.5 lb ae/A 350 acres NA NA 1,900

Typical Field Crops

1 lb ae/A

350 acres NA NA 930

High Acreage Field Crops 1200 acres NA NA 270

Applying Spray by 

Ground boom Application

Sod PF5: 0.068

PF10: 0.034

EC: 0.043

0.5 lb ae/A 80 acres 590 1,200 930

Typical Field Crops

1 lb ae/A

80 acres 290 590 470

High Acreage Crops 200 acres 120 240 190

Flagger

Flagging in support of 

Aerial Application

Sod

PF5: 0.07

PF10: 0.035

0.5 lb ae/A

350 acres

130 260 NA

Typical Field Crops

1 lb ae/A

65 130 NA

High Acreage Field Crops 65 130 NA

1 Based on the “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table” (March 2016)

2 Based on proposed label (7969-GUL).

3 Exposure Science Advisory Council Policy #9.1.

4 Inhalation MOE = Inhalation POD (0.02 mg/kg/day) ÷ Inhalation Dose (mg/kg/day).

8.2 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.

8.2.1 Occupational Post-application Inhalation Exposure/Risk Estimates

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

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

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

pesticides. 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 
Page 28 of 36

(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 dicamba.

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.

8.2.2 Occupational Post-application Dermal Exposure/Risk Estimates

Occupational Post-application Dermal Exposure

There is no potential hazard via the dermal route for dicamba; therefore, a quantitative 

occupational post-application dermal risk assessment was not completed.

Restricted Entry Interval

The REI specified on the proposed label is based on the acute toxicity of dicamba. Dicamba is 

classified as Toxicity Category III via the dermal route, Toxicity Category II for skin irritation 

potential, and Toxicity Category II for eye irritation. It is not a skin sensitizer. As there is no 

hazard via the dermal route of exposure, there are no post-application risks of concern on day 0 

(12 hours following application). Under 40 CFR 156.208 (c) (2) (iii), ai’s classified as Acute II

for acute dermal, eye irritation or primary skin irritation 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 dicamba. 
Page 29 of 36

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

Residential Non-cancer Handler Algorithms

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).

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 Non-cancer Post-application Algorithms

Post-application Dermal Exposure Algorithm – Physical Activities on Turf

Exposure resulting from contacting previously treated turf while performing physical activities is 

calculated as shown below. Residential post-application exposure assessment must include 

calculation of exposure on the day of application. Therefore, though an assessment can present 

exposures for any day “t” following the application, it must include “day 0” exposure.

E = TTRt * CF1 * TC * ET

where:

E = exposure (mg/day);

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

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

TC = transfer coefficient (cm2/hr); and
Page 30 of 36

ET = exposure time (hr/day).

If chemical-specific TTR data are available, then surface residues from the day of application 

should be used (assume that individuals could be exposed to residues immediately after 

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

formula:

TTRt= AR * F * (1-FD)t * CF2 * CF3

where:

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

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

F = fraction of ai as transferable residue following application (unitless);

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

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

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

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

Dermal absorbed doses are calculated as:

BW

E AF D*



where:

D = dose (mg/kg-day);

E = exposure (mg/day);

AF = absorption factor (dermal); and

BW = body weight (kg).

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

to calculate HTM exposure)

Algorithm Notation Exposure Factor

(units) Point Estimate(s)

AR Application rate

(mass active ingredient per unit area) 1 lb ae/acre

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
Page 31 of 36

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

to calculate HTM exposure)

Algorithm Notation Exposure Factor

(units) Point Estimate(s)

ET Exposure Time

(hours per day)

Adults 1.5

Children 1 < 2 years old 1.5

BW Body Weight

(kg)

Adults 80

Children 1 < 2 years old 11

L/WP/WDG = Liquids/Wettable Powders/Water-dispersible Granules

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

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

the SHEDS-Multimedia model):

E = [HR * (FM * SAH) * (ET * N_Replen) * (1- (1- SE)

(Freq_HtM/N-Replen))]

where:

E = exposure (mg/day);

HR = hand residue loading (mg/cm2);

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

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

ET = exposure time (hr/day);

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

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

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

and

SA * 2

Fai *DE

HR

H

hands



where:

HR = hand residue loading (mg/cm2);

Faihands = fraction ai on hands compared to total surface residue from dermal transfer coefficient 

study (unitless);

DE = dermal exposure (mg); and

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

Dose, normalized to body weight, is calculated as:

BW

E

D 

where:

D = dose (mg/kg-day);
Page 32 of 36

E = exposure (mg/day); and

BW = body weight (kg).

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

Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

Faihands

Fraction of ai on hands 

from dermal transfer 

coefficient study

(unitless)

Liquid formulations 0.06

Granular formulations 0.027

DE Dermal exposure (mg) Calculated

SAH

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

2 years old 150

AR Application rate

(mass active ingredient per unit area) 1 lb ae/acre

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
Page 33 of 36

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-3: Turf (Physical Activities) – Inputs for Residential Post-application Object-to-Mouth 

Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

AR Application rate (to turf)

(mass active ingredient per unit area) 1 lb ae/acre

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);
Page 34 of 36

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

BW = body weight (kg).

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

Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

AR Application rate

(mass active ingredient per unit area) 1 lb ae/acre

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:
Page 35 of 36

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);

E = exposure (mg/day); and

BW = body weight (kg).

Table A-5: 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 1%

AR Application rate (lbs/A or lbs/1,000 ft2) 1 lb ae/acre

GIgR Granule ingestion rate per day

(g/day) 1 0.1*

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.

Post-application granular pesticide exposure following applications to lawns and turf would not 

occur as a result of routine behavior and is considered an episodic event related to poisoning.

*The default ingestion rate for dry pesticide formulations (e.g., pellets and granules) is 0.3 

gram/day for children 1 < 2 years old. It is assumed that if 150 pounds of product were to be 

applied to a 1⁄2 acre lawn, the amount of product per square foot would be approximately 3 g/ft2

and a child would consume one-tenth of the product available in a square foot. According to the 

2012 Residential SOP, if product-specific information is available, the granular ingestion rate 

may be adjusted to reflect the amount of product applied on a per area basis if it is less or more 

than 150 pounds to a 1⁄2 acre lawn. For instance, if 50 pounds of product is meant to treat a 1⁄2 

acre lawn, then the ingestion rate should be reduced by a third to 0.1 grams/day. As the 

maximum application rate for dicamba on lawns is 1 lb ae/acre, and the maximum percent of 

active ingredient in dry formulation is 1%, the maximum amount of product to treat an acre is 

100 pounds; or a maximum of 50 pounds of product to treat a half-acre. Therefore, the point 

estimate for granular ingestion rate (GIgR) has been reduced by a third to 0.1 grams/day.

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
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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 

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).