Bensulfuron-Methyl Human Health Risk Assessment 0429515 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MEMORANDUM 

DA TE: November 30, 20 l 5 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

SUBJECT: Bensulfuron-Methyl. Human Health Risk Assessment for Registration Review. 

PC Code: 128820 

Decision No.: 509906 

Petition No.: NA 

DP Barcodc: 0429515 

Registration Nos.: 70506-147, 148; 71085-9,16,23 

Regulatory Action: Registration Review 

Risk Assessment Type: Single Chemical/Aggrega1e 

TXR No.: NA 

Case No.: 7216-1 

CAS No.: 83055-99-6 

MRID No.: NA 

FROM: 

THROUGH: 

TO: 

Myron S. Ottley, Senior Bio 

Kristin Rury, Biologist ¥-

Don Wilbur. Senior Chemist 

Risk Assessment Branch 3 

Health Effects Division (7509P) 

40 CFR: § 180.445 

C

Risk 

hristine 

Assess

Olinger. 

ment Branch 

Chief 

3 

~~ · 

Health Effects Division (75 --

Moana Appleyard, Risk Manager Reviewer 

Risk Management and Implementation Branch V (RM53) 

Pesticide Re-Registration Division (7508P) 

Bensulfuron-methyl is a systemic herbicide belonging to the pyrimidinylsulfonylurea group of 

herbicides. It inhibits the action of the plant enzyme acetolactate synthase (ALS)/acetohydroxy 

acid synthase (AHAS). This document evaluates the existing uses of bensulfuron-methyl as part 

of Registration Review and represents the draft risk assessment (ORA). The Agency is 

reviewing all the sulfonylurea herbicides jointly under Registration Review. 

Page 1 of31 
Bensulfuron-Methyl Human Health Risk Assessment 04295 15 

Table of Contents 

1.0 Executive Summary ........................................................................................................... 3 

2.0 HED Recommendations .................................................................................................... 3 

2.1 Tolerance Considerations .............................................................................................. 3 

2.2 Data Deficiencies ............................................................................................................ 3 

2.3 Label Recommendations ......................................................................... 4 

3.0 Introduction .................................................................................................................... 4 

3.1 Use Profile & Anticipated Exposure Pathways ........................................................... 4 

3.2 Consideration of Environmental Justice ...................................................................... 4 

4.0 Hazard Characterization .................................................................................................. 5 

5.0 Residue Chemistry ............................................................................................................. 9 

6.0 Dietary Risk Assessment ................................................................................................. 10 

6.1 Water Residue Profile .................................................................................................. 10 

6.2 Dietary (Food + Water) Exposure Assessment .......................................................... 11 

7.0 Residentia l (Non-Occupational) Exposure/Risk Characterization ............................. 12 

7.1 Spray Drift .................................................................................................................... 12 

7.2 Residential Bystander Post-Application Inhalation Exposure ................................ 14 

8.0 Aggregate Exposure/Risk Characteriza tion .................................................................. 15 

9.0 Cumulative Exposure/Risk Characterization ............................................................... 15 

10.0 Occupational Exposure/Risk Characterization ............................................................ 15 

11.0 Public Health and Pesticide Epidemiology Data ........................................................... 19 

12.0 References ......................................................................................................................... 20 

Appendix A: Toxicity Profile of Bensulfuron-Methyl.. ........................................................... 21 

Appendix B: Dietary Exposure/Risk Modeling Input and Output ..................................... 25 

Appendix C: Revie\v of Human Research ............................................................................... 26 

Appendix D: Occupational Non-cancer Handler Exposure Estimates and Algorithms ... 27 

Appendix E. Nomenclature and Physical/Chemical Properties ............................................. 29 

Appendix F. International Harmonization .............................................................................. 30 

Appendix G. DFR Data Waiver Rationale .............................................................................. 31 

Page 2 of31 
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 3 of 31

1.0 Executive Summary

Bensulfuron-methyl, [methyl 2-[[[[[(4,6-dimethoxy-2-

pyrimidinyl)amino]carbonyl]amino]sulfonyl]methyl]benzoate], is a systemic herbicide belonging 

to the pyrimidinylsulfonylurea class of chemicals. It is currently registered for use on rice. The 

registrant of bensulfuron-methyl end-use products is E.I. duPont de Nemours and Company. 

Since the last risk assessment (W. Wassell, D238880, 11/20/1997) and scoping document (N. 

Tsaur, D389431, 07/06/2011), toxicity data requirements for all toxicity studies have been met or 

waived, and the bensulfuron-methyl hazard profile has been updated accordingly. The residue 

profile no longer includes rice, straw because it is no longer an animal feed item or a regulated 

commodity. Dietary exposure to bensulfuron-methyl has been reevaluated in order to 

incorporate updated consumption data and drinking water modeling estimates. Non-dietary 

exposure has also been reevaluated to incorporate changes to occupational exposure assessment 

methodologies (unit exposures) and to incorporate a spray drift assessment. There are no risk

estimates of concern for the existing uses of bensulfuron-methyl.

2.0 HED Recommendations

2.1 Tolerance Considerations

The existing tolerances for bensulfuron-methyl are listed in 40 CFR §180.445 and are supported 

by the available residue chemistry data: Crayfish at 0.05 parts per million (ppm); and rice, grain 

at 0.02 ppm. However, HED recommends that the tolerance on rice, straw be revoked since it is 

no longer an animal feed item or a regulated commodity. The residue of concern for tolerance 

enforcement is bensulfuron-methyl only. There are no Maximum Residue Limits (MRLs) or 

tolerances for bensulfuron-methyl in Canada or in the Codex system. Please refer to Appendix F 

for a listing of all tolerances. 

HED recommends for modification of the tolerance expression for bensulfuron-methyl according 

to the new compliance/measurement policy (Interim Guidance on Tolerance Expressions, Steve 

Knizner, May 27, 2009) as follows:

Tolerances are established for residues of bensulfuron-methyl, including its metabolites 

and degradates, in or on the commodities in the table below. Compliance with the 

tolerance levels specified below is to be determined by measuring only bensulfuronmethyl [methyl 2-[[[[[(4,6-dimethoxy-2-

pyrimidinyl)amino]carbonyl]amino]sulfonyl]methyl]benzoate].

2.2 Data Deficiencies 

None
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 4 of 31

2.3 Label Recommendations

EPA Reg. No. 70506-149 should list required personal protective equipment (PPE) based on the 

acute toxicity of the end-use product per 40 CFR 170.240. EPA Reg. No. 70506-149 should also 

list a restricted entry interval (REI) based on the acute toxicity of the active ingredient per 40 

CFR 156.208. 

3.0 Introduction 

3.1 Use Profile & Anticipated Exposure Pathways 

Bensulfuron-methyl is formulated as dry flowable (DF), granular, and liquid formulations. 

Currently registered labels include one technical/manufacturing use product label, and five end 

use product labels. The only registered use of bensulfuron-methyl is on rice. In general, 

bensulfuron-methyl may be applied once or twice per year or growing season. Bensulfuronmethyl may be applied using groundboom and aerial application equipment; application via 

chemigation is prohibited on the registered labels. Most of the registered bensulfuron-methyl

labels require occupational handlers to wear long-sleeved shirts, long pants, shoes, socks, and 

chemical resistant gloves. Bensulfuron-methyl labels that are co-formulations with propanil 

require the addition of chemical resistant footwear, chemical resistant aprons, chemical resistant 

eyewear, and chemical resistant headgear when handling. Most of the REIs are 24 hours on the 

registered labels; however EPA Reg. No. 70506-149 does not list required PPE or an REI. 

Individuals may be exposed to bensulfuron-methyl via their diet (food and drinking water) and 

agricultural workers may be exposed (dermally and via inhalation) to bensulfuron-methyl during 

mixing, loading, and/or applying the herbicide as well as during post-application activities. 

There are no registered uses for bensulfuron-methyl that will result in direct non-dietary (i.e., 

residential) exposures. However, there is the potential for indirect exposure (incidental oral and 

dermal) to bensulfuron-methyl related to spray drift. Exposure to bensulfuron-methyl is 

expected to be short- and intermediate-term for occupational handlers and post-application 

workers. Exposure to bensulfuron-methyl via non-occupational spray drift is expected to be 

short-term only.

Table 3.1. Summary of Directions for Use of Bensulfuron.

Applic. Timing, 

Type, and Equip. Formulation Max. Single Applic. Rate (lb ai/A)

Max. No. Applic. 

per Season

Max. Seasonal 

Applic. Rate (lb ai/A)

Rice

Groundboom, Aerial1

DF 0.063 One at max single 

application rate 0.063

Liquid 0.047 Two 0.062

Granular 0.064 One 0.064

1. Chemigation is not permitted on the registered labels.

3.2 Consideration of Environmental Justice

Potential areas of environmental justice concerns, to the extent possible, were considered in the 

preliminary human health risk assessment for bensulfuron-methyl, in accordance with U.S. 
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 5 of 31

Executive Order 12898, "Federal Actions to Address Environmental Justice in Minority 

Populations and Low-Income Populations"1. As a part of every pesticide risk assessment, OPP 

considers a large variety of consumer subgroups according to well-established procedures. In 

line with OPP policy, HED estimates risks to population subgroups from pesticide exposures that 

are based on patterns of that subgroup’s food and water consumption, and activities in and 

around the home that involve pesticide use in a residential setting. Extensive data on food 

consumption patterns are compiled by the USDA under the National Health and Nutrition

Examination Surveys/What We Eat in America (NHANES/WWEIA) and are used in pesticide 

risk assessments for all registered food uses of a pesticide. These data are analyzed and 

categorized by subgroups based on age and ethnic group. Additionally, OPP is able to assess 

dietary exposure to smaller, specialized subgroups and exposure assessments are performed 

when conditions or circumstances warrant. Whenever appropriate, non-dietary exposures based 

on home use of pesticide products and associated risks for adult applicators and for toddlers, 

youths, and adults entering or playing on treated areas post-application are evaluated. Further 

considerations are currently in development as OPP has committed resources and expertise to the 

development of specialized software and models that consider exposure to bystanders and farm 

workers as well as lifestyle and traditional dietary patterns among specific subgroups. 

4.0 Hazard Characterization

The toxicology database for bensulfuron-methyl is considered complete and adequate for risk 

assessment. Although guideline subchronic dermal, subchronic inhalation, subchronic 

neurotoxicity, immunotoxicity and oncogenicity (rat) studies are not available for bensulfuronmethyl as required in accordance with the current 40 CFR Part 158 Toxicology Data 

Requirements, the Hazard and Science Policy Council (HASPOC) determined that these studies 

are not required at this time for bensulfuron-methyl2. The last risk assessment was conducted in 

1997 (D238880, W. Wassell, 11/20/1997). Since that risk assessment, an acceptable acute 

neurotoxicity (ACN) study has been submitted and reviewed. For a summary of the acute, 

subchronic and chronic toxicity profiles, see Appendix A.

4.1 Summary of Toxicological Effects

The primary target organ of bensulfuron-methyl toxicity is the liver. Effects in the mouse 

included enlarged livers, nodules and masses in the liver, and increased liver weight

accompanied by liver elevated liver enzymes (alkaline phosphatase (AP), alanine transaminase 

(ALT) and aspartate aminotransferase (AST)) and histological lesions at the highest dose tested 

(455 mg/kg/day). Similar hepatotoxicity, as well as irritation of oral mucosa, were observed in 

the chronic dog study at 237 mg/kg/day and above. Adaptive, non-adverse changes in liver 

histology were observed in the chronic rat study at 305/405

mg/kg/day (M/F). Similar to chronic studies, liver effects were seen in the 90-day subchronic 

toxicity studies in the mouse and dog at comparable dose levels. Submitted reproductive and 

 

1 http://www.epa.gov/compliance/resources/policies/ej/exec_order_12898.pdf

2 TXR 0057190, R. Beaver, 08/27/2015 (subchronic neurotoxicity, oncogenicity--rat)

 TXR 0052986, E. Craig, 05/07/2015 (subchronic inhalation)

 TXR 0056721, K. Rury, 08/26/2013 (subchronic dermal)

 TXR 0056723, K. Rury, 8/6/2013 (immunotoxicity)
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 6 of 31

developmental toxicity studies indicated that bensulfuron-methyl induces developmental effects 

(skeletal variations and reduced ossification in rats, abortions in rabbits) only at levels above the 

limit dose, and has no adverse effects on reproductive function. Bensulfuron-methyl did not 

produce evidence of neurotoxicity in any of the studies in the database, including the acute and 

subchronic neurotoxicity studies. Bensulfuron-methyl is not mutagenic in bacteria or cultured 

mammalian cells. Bensulfuron-methyl is classified as "not likely to be carcinogenic to humans" 

based on no evidence of increased tumor incidence in rats or mice.

Bensulfuron-methyl has low acute toxicity. It is classified as toxicity category IV for oral and 

inhalation exposures and toxicity category III for dermal exposure. Bensulfuron-methyl is

classified as toxicity category IV for primary eye and skin irritation and is not a dermal

sensitizer.

4.2 Safety Factor for Infants and Children (FQPA Safety Factor)

The 10-fold FQPA Safety Factor is reduced to 1X. The toxicity database of bensulfuron-methyl 

is considered complete and adequate to assess the qualitative or quantitative susceptibility in the 

young, and exposure estimates are unlikely to underestimate risk. There is no evidence of 

increased susceptibility in the pre-natal developmental studies in rabbits and in rats of 

reproduction study. There was an increase in susceptibility seen in the rat fetuses consisting of

skeletal variations and reduced ossification at the dose where maternal toxicity was absent. 

However, these effects occurred only above the limit dose (1320 mg/kg/day), and there was a 

clear No Observed Adverse Effect Level (NOAEL) for these effects. In addition, this NOAEL 

was substantially greater the POD used for risk assessment. Therefore, there is low concern for 

this finding. There is no concern for neurotoxicity based on the absence of neurotoxicity in the 

neurotoxicity battery and other studies in the toxicity database.

4.3 Toxicity Endpoint and Point of Departure Selections

The last dose-response assessment has been modified to include incident oral, dermal and 

inhalation endpoints and points of departure (PODs), due to updated exposure scenarios. It is 

recognized that the studies in the bensulfuron-methyl database, including those used for endpoint 

selection, have not been updated to reflect current data evaluation policy and may be considered 

conservative. The currently selected PODs are protective of the effects observed in the 

bensulfuron-methyl database and any updates would not impact the overall findings of the risk 

assessment given the current risk picture for bensulfuron-methyl. 
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 7 of 31

Table 4.3. Bensulfuron-methyl Summary of Toxicological Doses and Endpoints for Use in 

Dietary, Non-Occupational, and Occupational Human Health Risk Assessments.

Exposure 

Scenario

Point of 

Departure

Uncertainty

Factors

RfD/

Level of 

Concern

Study & Toxicological Effects

Acute Dietary 

(general 

population 

including infants 

and children)

No toxicological effects attributable to a single dose were identified in any of the studies.

Chronic Dietary NOAEL = 19.9 

mg/kg/day

UFA = 10X

UFH = 10X

FQPA SF = 1X

Chronic RfD = 

0.2 mg/kg/day

cPAD = 0.2 

mg/kg/day

Chronic toxicity study in dogs

(MRID 40889319)

LOAEL = 222.6 mg/kg/day based on 

discoloration and inflammation of oral 

mucosa; increased liver weight in the 

presence of increased AP and ALT, 

and microscopic lesions (inflammation 

of the gums).

Incidental Oral

Short- and 

Intermediate 

Term

NOAEL = 36.3 

mg/kg/day

UFA = 10X

UFH = 10X

FQPA SF = 1X

LOC for MOE 

= 100

90-Day toxicity study in dogs

(MRID 00147397)

LOAEL = 340 mg/kg/day based on 

moderately elevated alkaline 

phosphatase and SGPT (ALT);

decreased weights for heart and 

ovary/fallopian tube; liver enlargement 

and discoloration with bile stasis and 

centrilobular hepatocyte swelling; gall 

bladder calculus; and vacuolation of 

the seminiferous tubules.

Dermal

Short- and 

Intermediate 

Term

NOAEL

b =

36.3 mg/kg/day

UFA = 10X

UFH = 10X

FQPA SF = 1X

LOC for MOE 

= 100

90-Day toxicity study in dogs

(MRID 00147397)

LOAEL = 340 mg/kg/day based on 

moderately elevated alkaline 

phosphatase and SGPT (ALT);

decreased weights for heart and 

ovary/fallopian tube; liver enlargement 

and discoloration with bile stasis and 

centrilobular hepatocyte swelling; gall 

bladder calculus; and vacuolation of 

the seminiferous tubules.
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 8 of 31

Table 4.3. Bensulfuron-methyl Summary of Toxicological Doses and Endpoints for Use in 

Dietary, Non-Occupational, and Occupational Human Health Risk Assessments.

Exposure 

Scenario

Point of 

Departure

Uncertainty

Factors

RfD/

Level of 

Concern

Study & Toxicological Effects

Inhalation

Short- and 

Intermediate 

Term

NOAELc =

36.3 mg/kg/day

UFA = 10X

UFH = 10X

FQPA SF = 1X

LOC for MOE 

= 100

90-Day toxicity study in dogs

(MRID 00147397)

LOAEL = 340 mg/kg/day based on 

moderately elevated alkaline 

phosphatase and SGPT (ALT);

decreased weights for heart and 

ovary/fallopian tube; liver enlargement 

and discoloration with bile stasis and 

centrilobular hepatocyte swelling; gall 

bladder calculus; and vacuolation of 

the seminiferous tubules.

Cancer Classification: Not likely to be carcinogenic to humans based on no evidence of increased 

tumor incidence in rats or mice under the experimental conditions tested.

a Endpoint Selection Table derived from D238880 (W. Wassell, 11/20/1997) and updated with endpoints and 

points of departure for incidental oral exposures.

b

In the absence of dermal absorption data, the dermal absorption factor (DAF) is assumed to be 100%

c Toxicity via the oral and inhalation routes are assumed to be equivalent in terms of nature and severity.

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). RfD = reference dose. MOE = margin of 

exposure. LOC = level of concern; FQPA = Food Quality Protection Act. 

4.4 Endocrine Disruption

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of its most recent registration decision for bensulfuron-methyl, EPA 

reviewed these data and selected the most sensitive endpoints for relevant risk assessment 

scenarios from the existing hazard database. However, as required by FFDCA section 408(p),

bensulfuron-methyl is subject to the endocrine screening part of the Endocrine Disruptor 

Screening Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 9 of 31

may designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine-related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. Under FFDCA 

section 408(p), the Agency must screen all pesticide chemicals. Between October 2009 and 

February 2010, EPA issued test orders/data call-ins for the first group of 67 chemicals, which 

contains 58 pesticide active ingredients and 9 inert ingredients. A second list of chemicals 

identified for EDSP screening was published on June 14, 20133and includes some pesticides 

scheduled for Registration Review and chemicals found in water. Neither of these lists should be 

construed as a list of known or likely endocrine disruptors.

For further information on the status of the EDSP, the policies and procedures, the lists of 

chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our 

website.4

5.0 Residue Chemistry

The only registered use for bensulfuron-methyl is in/on rice (grain and straw). Related with that 

use, there is a tolerance set for residues of bensulfuron-methyl in/on crayfish (cultured in rice 

paddies).

The nature of the residue of bensulfuron-methyl in plants and ruminants has been adequately 

delineated based on metabolism studies conducted in rice and lactating goats, and the results of 

the metabolism study in lactating goats can be translated to crayfish. The metabolic pathways in 

plants and ruminants were found to be similar. The nature of the residue in poultry has not been 

adequately defined; however, HED has previously concluded that based on the livestock 

metabolism data (ruminants and poultry) and the absence of detectable residues in rice grain, the 

use on rice can be classified as 40 CFR 180.6 (a)(3), no reasonable expectation of finite residues 

in livestock commodities. HED has determined that the residue of concern (ROC) for tolerance 

enforcement and risk assessment is the parent compound (bensulfuron-methyl) for both plants 

and livestock commodities.

The residue chemistry database is adequate to support current Registration Review data 

requirements. Adequate field trial and processing studies are available to support the registered 

use on rice. The magnitude of the residue and processing studies are supported by adequate 

storage stability data for bensulfuron-methyl. Adequate methods are available for enforcement 

of the currently established tolerances. Adequate confined rotational crop data are available to 

support minimum plant-back intervals of 120 days.

 

3 See http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list of 

chemicals.

4 http://www.epa.gov/endo/
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 10 of 31

Adequate high performance liquid chromatography methods are available for tolerance 

enforcement: Method DuPont-AMR 2866-93 for rice and its processed commodities, and 

Method DuPont AMR 2981-94 for crayfish. The methods have been adequately validated for 

the determination of residues of bensulfuron-methyl in rice and crayfish. Multi-residue methods 

testing data were previously submitted for bensulfuron-methyl, which indicated that the methods 

are not applicable for bensulfuron-methyl determination. 

An analytical reference standard for bensulfuron-methyl with an expiration date of 10/26/2016 is 

available at EPA’s National Pesticide Standards Repository (e-mail dated 10/26/2015 from 

Gregory Verdin, Analytical Chemistry Branch/Biological and Economic Analysis Division). 

The structure and the physical/chemical properties are summarized in Appendix E. 

6.0 Dietary Risk Assessment

An updated dietary exposure assessment has been completed for bensulfuron-methyl to 

incorporate updated food consumption data and drinking water modeling estimates. The use 

pattern, PODs, and residue inputs to the dietary assessment have not changed since the previous 

assessment. 

6.1 Water Residue Profile 

Screening ground water-sourced drinking water exposure estimates were generated with the 

Pesticide Root Zone Model for Ground Water (PRZM-GW; v.1.07) for use in the SU dietary risk 

assessments. Rather than produce chemical-specific estimated drinking water concentrations 

(EDWCs) following the usual assessment procedures, the Environmental Fate and Effects 

Division (EFED) provided coarse-screen estimates that should exceed upper-bound chemicalspecific EDWCs for any SU. This was achieved by using model inputs that represent the use 

pattern of highest exposure from any SU, the highest soil mobility of any SU residue of concern, 

and persistence to any route of degradation over time. The resulting highest coarse-screen 

EDWCs from PRZM-GW can be used as conservative estimates of exposure and are 

summarized in Table 6.1 (G. Orrick, D427429, 08/12/2015). 

The chronic dietary assessments for bensulfuron-methyl used the post-breakthrough time (i.e., 

the time it takes the compound to reach the ground water after application) mean value of 492 

μg/L (0.492 ppm). 

Table 6.1. PRZM-GW Coarse-Screen EDWCs for Sulfonylureas1.

Modeled Scenario Kd or KOC

Initial Application 

Dates (days postemergence)

Max. Daily Conc. 

(μg/L)

Mean 

Breakthrough 

Time (yrs)

Postbreakthrough

Mean (μg/L)

WI corn

Kd 7 449 11.5 415

KOC 7 504 6.9 425

DMV corn

Kd 7 489 5.3 369

KOC 7 560 3.3 378
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 11 of 31

Table 6.1. PRZM-GW Coarse-Screen EDWCs for Sulfonylureas1.

Modeled Scenario Kd or KOC

Initial Application 

Dates (days postemergence)

Max. Daily Conc. 

(μg/L)

Mean 

Breakthrough 

Time (yrs)

Postbreakthrough

Mean (μg/L)

FL citrus

Kd 7 429 3.2 351

KOC 7 467 2.3 349

FL potato

Kd 7 375 2.6 272

KOC 7 407 2.2 275

GA peanut

Kd 7 197 5.2 156

KOC 7 206 3.9 158

NC cotton

Kd 7 640 8.7 492

Kd 37 641 8.7 491

Kd 67 637 8.7 490

KOC 7 742 5.7 484

KOC 37 751 5.7 483

KOC 67 744 5.7 482

1 The maximum value is bolded and was used in the chronic dietary assessment.

6.2 Dietary (Food + Water) Exposure Assessment 

HED has conducted a screening-level chronic dietary risk assessment for bensulfuron-methyl

using tolerance-level residues in foods and a sulfonylurea-class-wide screening-level estimate of 

residues in drinking water (G. Orrick, D427429, 08/12/2015). Exposure and risk estimates were 

obtained from the Dietary Exposure Evaluation Model using the Food Commodity Intake 

Database (DEEM-FCID; version 3.16). The model uses food consumption data from the 2003-

2008 NHANES/WWEIA (National Health and Nutrition Examination Survey, What We Eat in 

America) database, coupled with recipe files and residues in foods, to derive estimates of dietary 

exposure and risk. Generally, HED is concerned when dietary exposure estimates exceed 100% 

of the population adjusted dose (PAD). In the case of bensulfuron-methyl, the dietary risk 

estimates (Table 6.2) range from 3.8 to 13.3% of the cPAD and are below HED’s level of 

concern. Because of the very conservative assumptions used in the analysis (tolerance level 

residues, 100% crop treated, and upper-bound modeled drinking water estimates), actual 

exposure and risk are expected to be much lower than those shown in Table 6.2. The listing of 

inputs to the assessment is included in Appendix B. HED did not conduct an acute dietary 

exposure/risk assessment because an acute dietary POD was not selected for bensulfuron-methyl. 

Bensulfuron-methyl is considered “not likely to be carcinogenic to humans”; therefore a cancer 

dietary risk assessment was also not conducted. 

Table 6.2. Summary of dietary exposure and risk estimates for Bensulfuron-methyl.

Population Group

Chronic Estimates

Exposure, mg/kg bw/day Risk, % cPAD

Total US Population 0.010309 5.2

All Infants (< 1 year old) 0.026584 13.3

Children 1-2 years old 0.014875 7.4

Children 3-5 years old 0.012532 6.3
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 12 of 31

Table 6.2. Summary of dietary exposure and risk estimates for Bensulfuron-methyl.

Population Group

Chronic Estimates

Exposure, mg/kg bw/day Risk, % cPAD

Children 6-12 years old 0.009037 4.5

Youth 13-19 years old 0.007517 3.8

Adults 20-49 years old 0.010287 5.1

Adults 50-99 years old 0.010166 5.1

Female 13-49 years old 0.010247 5.1

7.0 Residential (Non-Occupational) Exposure/Risk Characterization

There are no registered residential uses or occupational uses resulting in residential exposure to 

bensulfuron-methyl. Therefore, a quantitative residential exposure assessment was not 

performed. 

7.1 Spray Drift 

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

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

surfaces where contact with residues can eventually lead to 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 onto 50 feet wide lawns 

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, which is analogous to how exposures to turf products are 

considered in risk assessment. 

In order to evaluate the drift potential and associated risks, 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 bensulfuron. 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 

 

5 This approach is consistent with the requirements of the EPA’s Worker Protection Standard.
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 13 of 31

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.6,7 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). Section 7.1.1 provides the screening level drift related risk estimates. 

In many cases, risks are of concern when the screening level estimates for spray drift are used as 

the basis for the analysis. In order to account for this issue and to provide additional risk 

management options additional spray drift deposition fractions were also considered. These drift 

estimates represent plausible options for pesticide labels.

7.1.1 Combined Risk Estimates From Lawn Deposition Adjacent to Applications

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

result of the screening-level agricultural application scenarios. Bensulfuron-methyl is used only 

on rice and can be applied via aerial and ground equipment. The recommended drift scenario 

screening level options are listed below: 

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

very fine to fine spray type, and use 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).8

Dermal and incidental oral risk estimates were combined for children 1 to <2 years old because 

the toxicity endpoint for each route of exposure was the same for both exposure routes. The 

 

6http://www.agdrift.com/ 

7 Note that for many cases the scenarios outlined in the screening approach represent actual use practice so risk assessors should 

be aware and characterize these appropriately.

8 AgDrift allows for consideration of even finer spray patterns characterized as very fine to fine. However, this 

spray pattern was not selected as the common screening basis since it is used less commonly for most agriculture. If 

assessors identify this use pattern it should be used as the screening criteria and deposition values associated with it 

are provided in Table 1 below. Justification for including this spray quality should be included in any assessment 

based on specific label directions for its use.
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 14 of 31

applicable Levels of Concern (LOC) for each exposure route is 100; therefore MOEs < 100 are 

of concern. None of the adult or children (1 to <2 years old) risk estimates from indirect 

exposure to bensulfuron-related spray drift result in risks of concern at field edge. 

Table 7.1.1. Adult Dermal Risk Estimates (MOEs) Related to Spray Drift Exposure to Bensulfuron-methyl

from the Registered Agricultural Uses. 

Application 

Type

Spray Type/Nozzle 

Configuration

Appl. Rate 

(lb ai/A)

TTR 

(μg/cm2)

1 At Edge (LOC = 100)

Rice1

Aerial Fine to Medium

0.063 0.0070

6,000

Groundboom High Boom Very fine 

to Fine 8,200

1 HED’s default assumption that 10% 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.

Table 7.1.2. Combined Dermal and Incidental Oral (Hand to Mouth) Exposure for Children 1 < 2 Years 

Old Risk Estimates (MOEs) Related to Spray Drift Exposure to Bensulfuron-methyl from the Registered 

Agricultural Uses.

Application 

Type

Spray Type/Nozzle 

Configuration

Appl. Rate 

(lb ai/A)

TTR 

(μg/cm2)

1 At Edge (LOC = 100)

Rice

Aerial Fine to Medium

0.063 0.0070

3,000

Groundboom High Boom Very fine 

to Fine 4,100

1 HED’s default assumption that 10% 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.

7.2 Residential Bystander Post-Application Inhalation Exposure

Volatilization of pesticides may be a source of post-application inhalation exposure to 

individuals nearby pesticide applications. The agency sought expert advice and input on issues 

related to volatilization of pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act 

Scientific Advisory Panel (SAP) in December 2009, and received the SAP’s final report on 

March 2, 2010 (http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The 

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

subsequent Volatilization Screening Analysis.9 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 bensulfuron-methyl.

 

9 Available at: http://www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2014-0219.
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 15 of 31

8.0 Aggregate Exposure/Risk Characterization

The Food Quality Protection Act of 1996 directs EPA to assess aggregate exposure to pesticide 

chemical residues. Exposures to be aggregated include anticipated dietary, residential handler, 

and residential post-application exposures. Since there are no residential uses for bensulfuronmethyl that would result in contributions to the aggregate assessment, short- and intermediateterm aggregate risk assessments are not required. Aggregate exposure and risk estimates are 

equivalent to the dietary exposure and risk estimates discussed in Section 6 of this document, and 

are not of concern. 

9.0 Cumulative Exposure/Risk Characterization

In 2015, EPA’s Office of Pesticide Programs released a guidance document entitled, Pesticide 

Cumulative Risk Assessment: Framework for Screening Analysis 

[http://www.epa.gov/oppfead1/cb/csb_page/updates/2015/framework-for-screeninganalysis.html]. This document provides guidance on how to screen groups of pesticides for 

cumulative evaluation using a two-step approach beginning with the evaluation of available 

toxicological information and if necessary, followed by a risk-based screening approach. This 

framework supplements the existing guidance documents for establishing common mechanism 

groups (CMGs)[1] and conducting cumulative risk assessments (CRA)[2]. The Agency has 

utilized this framework to evaluate the SUs of which bensulfuron-methyl is a member (J. 

D’Agostino, D428798, 09/09/15). Although the SUs share some chemical and toxicological 

characteristics, the toxicological database does not support a testable hypothesis for a common 

mechanism of action. No further mechanistic data are required and no further cumulative 

evaluation is necessary.

10.0 Occupational Exposure/Risk Characterization

There is potential occupational dermal and inhalation exposure from the registered uses of 

bensulfuron-methyl. The quantitative exposure/risk assessment developed for occupational 

handlers is based on the scenarios listed in Appendix D. 

Occupational Handler Exposure, Assumptions and Risk Estimate Equations

Application Rate: The maximum single application rates are listed in Table 3.1. Refer to section 

3.0 for a complete use pattern description.

Body Weight & Absorption Factor: The standard body weight (80 kg) was used in this risk 

assessment since the endpoints selected were not developmental and/or based on fetal effects. 

Since no inhalation or dermal absorption data are available, toxicity by the dermal and inhalation 

routes is considered to be equivalent to the estimated toxicity by the oral route of exposure.

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, 

 

[1] Guidance For Identifying Pesticide Chemicals and Other Substances that have a Common Mechanism of Toxicity (USEPA, 

1999)

[2] Guidance on Cumulative Risk Assessment of Pesticide Chemicals That Have a Common Mechanism of Toxicity (USEPA, 

2002)
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 16 of 31

include PHED (Pesticide Handlers Exposure Database) 1.1, and the AHETF (Agricultural 

Handler Exposure Task Force) database. 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 Table10.” 

HED policy on use of surrogate data, including descriptions of the various sources, can be found 

at the Agency website11. 

Area Treated: The area treated inputs were based on the Science Advisory Council for Exposure 

Policy 9.1: Standard Values for Daily Acres Treated in Agriculture (listed in Appendix D).

Risk Estimate Equations: The algorithms used to estimate non-cancer exposure and dose for 

occupational handlers can be found in Appendix D.

Combining Exposures/Risk Estimates: Dermal and inhalation risk estimates were combined in 

this assessment, since the toxicological effects for these exposure routes were similar. Dermal 

and inhalation risk estimates were combined using the following formula:

Total MOE = Point of Departure (mg/kg/day) ÷ Combined Dermal + Inhalation dose 

(mg/kg/day)

Summary of Occupational Handler Non-Cancer Exposure and Risk Estimate

All occupational handler scenarios for the registered uses resulted in MOEs greater than 100 at 

baseline level of risk mitigation (i.e., baseline attire with no gloves or respirator) or engineering 

control for aerial applications (i.e., enclosed cockpits).

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-1990s. 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, 

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.

 

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

11 Available: http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/occupational-pesticide-handlerexposure-data
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 17 of 31

Occupational Post-Application Exposure

Occupational Inhalation Post-Application Exposure

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.

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

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

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

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

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

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

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

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

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

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

required for bensulfuron.

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

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

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

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

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

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

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

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

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

inhalation exposure scenarios.

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.

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 
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 18 of 31

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

known as “transfer coefficients”, are presented in the ExpoSAC Policy 312” which, along with 

additional information about the ARTF data, can be found at the Agency website13. Table 10.1

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

coefficients for the proposed crops/use sites.

Application Rate: The maximum single application rates are listed in Table 3.1. Refer to section 

3.0 for a complete use pattern description.

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 bensulfuron-methyl. 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.

Occupational Post-application Non-Cancer Dermal Exposure and Risk Estimates

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

workers can be found in the footnotes of Table 10.1. The highest registered application rate of 

the products registered on rice was used as a conservative estimate of exposure (0.064 lb ai/A). 

The occupational post-application MOE for scouting following bensulfuron-methyl exposure is 

1,800 on day 0, and are not of concern. Hand weeding was not assessed for the registered uses 

of bensulfuron-methyl because it is a herbicide registered to kill broadleaf weeds; therefore, it is 

unlikely that someone would be entering treated fields to weed by hand following bensulfuronmethyl application. 

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

bensulfuron-methyl 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 = 1,800 compared to the LOC of 

100); EPA is waiving the 40 CFR 158 DFR data requirement. In this instance, it is unlikely that 

chemical-specific 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 bensulfuron. 

Table 10.1. Occupational Post-application Non-Cancer Exposure and Risk Estimates for Bensulfuronmethyl.

Crop/Site Activities Transfer Coefficient 

(cm2/hr) DFR/TTR1 Dermal Dose(mg/kg/day)2 MOE3

Short- and Intermediate-Term

Rice Scouting 1100 0.18 0.020 1,800

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. 

2 Daily Dermal Dose = [DFR (μg/cm2) × Transfer Coefficient × 0.001 mg/μg × 8 hrs/day × dermal absorption (100%)]  BW (80 kg).

3 MOE = POD (36.3 mg/kg/day) / Daily Dermal Dose (mg/kg/day). 

 

12 Available: http://www2.epa.gov/sites/production/files/2015-08/documents/exposac-policy-3-march2013.pdf

13 Available: http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/occupational-pesticide-postapplication-exposure
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 19 of 31

Restricted Entry Interval

Bensulfuron-methyl is classified as Toxicity Category III via the dermal route and Toxicity 

Category IV for skin irritation potential. It is not a 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), active ingredients 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 post-application exposures to bensulfuron. 

However, the labels list an REI of 24 hours, which is considered protective of post-application 

exposure. 

11.0 Public Health and Pesticide Epidemiology Data

The OPP Incident Data System (IDS), the Centers for Disease Control and Prevention/National 

Institute for Occupational Safety and Health (CDC/NIOSH) and Sentinel Event Notification 

System for Occupational Risk-Pesticides (SENSOR) databases were consulted for pesticide 

incident data on the active ingredient bensulfuron-methyl in 2013 and no incidents of concern 

were identified (S. Recore, D390061, 05/31/2011); therefore additional analysis is not required. 

Bensulfuron-methyl is also not included in the Agricultural Health Study (AHS), and therefore 

this study does not provide any additional information on bensulfuron-methyl. The Agency will 

continue to monitor the incident information and if a concern is triggered, additional analysis 

will be included in the risk assessment.
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 20 of 31

12.0 References

Author Barcode or 

TXR

Date Title

William 

Wassell

D238880 11/20/1997 PP#4F4367 & 5F4490. Human Health Risk Assessment 

for Bensulfuron-methyl in/on Crayfish and Rice Straw. 

Nancy Tsaur D389431 07/06/2011 Bensulfuron-Methyl. Human Health Scoping Document 

in Support of Registration Review.

Shanna 

Recore

D390061 05/31/2011 (to be completed)

Greg Orrick D427429 07/06/2011 Drinking Water Exposure Assessment for the Registration 

Review of 22 Sulfonylurea Herbicides

Jaime 

D’Agostino

D428798 09/09/2015 Sulfonylureas: Screening Analysis of Toxicological 

Profiles to Consider Whether a Candidate Common 

Mechanism Group Can Be Established.

Kristin Rury TXR

0056721

08/26/2013 Bensulfuron-methyl: Recommendations on the 

Requirement of a 21/28-Day Dermal Toxicity Study. 

Evisabel Craig TXR 0052986 05/07/2015 Sulfonylurea Pesticides: Summary of Hazard and Science 

Policy Council (HASPOC) Meeting on April 2, 2015: 

Recommendations on Data Requirement for Subchronic 

Inhalation Studies

Kristin Rury TXR 0056723 08/06/2013 Sulfonylureas: Summary of Hazard and Science Policy 

Council (HASPOC) Meeting on Juely 18, 2013: 

Recommendations on Data Requirement for 

Immunotoxicity Studies

Ronnie 

Beaver

TXR 0057190 08/27/2015 Bensulfuron-methyl: Recommendations on the 

Requirement of a Subchronic Neurotoxicity Study and a 

Two-year carcinogenicity Rat Study.
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 21 of 31

Appendix A: Toxicity Data Requirements and Profile of Bensulfuron-Methyl 

Table A.1. Bensulfuron-methyl Data Requirements

Test Technical

Required Satisfied

870.1100 Acute Oral Toxicity ......................................................

870.1200 Acute Dermal Toxicity .................................................

870.1300 Acute Inhalation Toxicity .............................................

870.2400 Primary Eye Irritation ...................................................

870.2500 Primary Dermal Irritation .............................................

870.2600 Dermal Sensitization.....................................................

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

870.3100 Oral Subchronic (rodent)..............................................

870.3150 Oral Subchronic (nonrodent) ........................................

870.3200 21/28-Day Dermal ........................................................

870.3250 90-Day Dermal .............................................................

870.3465 90-Day Inhalation .........................................................

yes

yes

no1

no

no1

yes

yes

--

--

--

870.3700 Developmental Toxicity (rodent)..................................

870.3700 Developmental Toxicity (nonrodent)............................

870.3800 Reproduction ................................................................

yes

yes

yes

yes

yes

yes

870.4100a Chronic Toxicity (rodent).............................................

870.4100b Chronic Toxicity (nonrodent).......................................

870.4200a Carcinogenicity (rat).....................................................

870.4200b Carcinogenicity (mouse)...............................................

870.4300 Chronic Toxicity/Carcinogenicity (rodent)...................

yes

yes

no1

yes

yes

yes2

yes

--

yes

yes

870.5100 Mutagenicity—Gene Mutation - bacterial....................

870.5300 Mutagenicity—Gene Mutation - mammalian...............

870.5375 Mutagenicity—Structural Chromosomal Aberrations..

870.5385 Mutagenicity—Structural Chromosomal Aberrations..

870.5395 Mutagenicity—Other Genotoxic Effects......................

870.5550 Mutagenicity—Other Genotoxic Effects......................

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

870.6100 Acute Delayed Neurotox. (hen)....................................

870.6100 90-Day Neurotoxicity (hen)..........................................

870.6200a Acute Neurotox. Screening Battery (rat) ......................

870.6200b 90-Day Neurotoxicity Screening Battery (rat)..............

870.6300 Developmental Neurotoxicity.......................................

no

no

yes

no1

no

--

--

yes

--

--

870.7485 General Metabolism .....................................................

870.7600 Dermal Penetration .......................................................

870.7800 Immunotoxicity ............................................................

yes

no

no1

yes

--

--

1 HASPOC concluded the subchronic dermal, subchronic inhalation, subchronic neurotoxicity, immunotoxicity and 

rat oncogenicity studies are not required at this time (references in Section 4.0, Footnote #1).

2 The combined chronic/carcinogenicity study fulfills this requirement. 
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 22 of 31

Table A.2.1. Acute Toxicity Profile of Bensulfuron-methyl Technical

Guideline 

Number Study Type MRID Results Toxicity Category

870.1100 Acute oral - Rats 00148295 LD50 > 5000 mg/kg IV

870.1200 Acute dermal - Rabbits 40089312 LD50 > 2000 mg/kg III

870.1300 Acute inhalation - Rats 40089313

40311905 LC50 > 5 mg/L IV

870.2400 Primary eye irritation - Rabbits 00147385 Slight corneal cloudiness 

(reversible) IV

870.2500 Primary skin irritation - Rabbits 073650 No dermal irritation IV

870.2600 Dermal sensitization - Guinea pigs 4217630 Not a dermal sensitizer ---

Table A.2.2. Repeated Dose Toxicity Profile of Bensulfuron-methyl Technical

Guideline 

Number Study Type MRID (year)Dose Levels, Classification Results

870.3100

90-day oral 

toxicity

Rat

00148301

0, 100, 1500, 7500 ppm.

0, 6.3, 93, 474 mg/kg/day males, 

0, 7.5, 111, 567 mg/kg/day females

Acceptable/guideline

NOAEL = 93 / 111 mg/kg/day M/F

LOAEL = 474 / 567 mg/kg/day M/F based 

on mildly elevated cholesterol values (M), 

mildly elevated kidney weights (M) and 

heart weights (F), and slight paleness of the 

hepatocellular cytoplasm (M)

870.3100

90-day oral 

toxicity

Mouse

00147395

0, 300, 1000, 3000, or 10,000 ppm

0, 38.7, 132, 387, 1320 mg/kg/day 

males

0, 40.7, 133, 407, 1320 mg/kg/day 

females

Acceptable Guideline

NOAEL = 132 / 133 mg/kg/day M/F

LOAEL = 387 and 407 mg/kg/day M/F 

based on deposition in the cortico-medullary 

junction of the adrenals in females, and an 

increase in liver size due to swelling of 

centrilobular hepatocytes.

870.3150

90-day oral 

toxicity

Dog

00147397

0, 100, 1000, or 10,000 ppm

0, 3.2, 32.1, 340 mg/kg/day males

0, 3.6, 32.1, 360 mg/kg/day females

Acceptable Guideline

NOAEL = 32.1 / 36.3 mg/kg/day M/F

LOAEL = 340 and 360 mg/kg/day M/F 

based on moderately elevated alkaline 

phosphatase and SGPT (ALT) levels in the 

high-dose at the 1-, 2-, and 3-month 

sampling intervals, indicating hepatic 

damage, organ weight changes including 

elevated weights for liver and testes, and 

decreased weights for heart, and 

ovary/fallopian tube, liver enlargement and 

discoloration with bile stasis and 

centrilobular hepatocyte swelling, gall 

bladder calculus, and vacuolation of the 

seminiferous tubules

870.3200 21-day dermal 

toxicity

A dermal toxicity study was not submitted. The requirement for this study has been 

waived (TXR0056721, K. Rury, 08/26/2013).

870.3465

90-day 

inhalation 

toxicity

An inhalation toxicity study was not submitted. The requirement for this study has 

been waived. (TXR 0052986, E. Craig, 05/07/2015).
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 23 of 31

Table A.2.2. Repeated Dose Toxicity Profile of Bensulfuron-methyl Technical

Guideline 

Number Study Type MRID (year)Dose Levels, Classification Results

870.3700

Prenatal 

developmental 

toxicity 

Rat

40089318 and 40311902

0, 50, 500 or 2000 mg/kg/day

Acceptable/Guideline

Maternal

NOAEL = 1320 mg/kg/day

LOAEL > 1320 mg/kg/day, not established

Developmental

NOAEL = 500 mg/kg/day

LOAEL = 1320 mg/kg/day based on 

statistically significant increases in skeletal 

variations that included extra ribs, reduced 

ossification of the sternebrae, and reduced 

ossification of the hyoid bones

870.3700

Prenatal 

developmental 

toxicity

Rabbit

40113801 and 40311906

0, 30, 300 or 1500 mg/kg/day

Acceptable/Guideline

Maternal

NOAEL = 300 mg/kg/day

LOAEL = 1500 mg/kg/day based on 

increased incidence of deaths, complete 

resorptions, abortions, stained tail and red 

discharge, and reduced food consumption

Developmental

NOAEL = 300 mg/kg/day

LOAEL = 1500 mg/kg/day based on 

increased resorptions and abortions

870.3800

Multi-generation 

reproduction 

study

Rat

40089316

0, 50, 750, 7500 ppm

0, 2, 30, 309 mg/kg/day males 

0, 2.7, 40, 405 mg/kg/day females

Acceptable/Guideline

Parental

NOAEL = 309/405 mg/kg/day

LOAEL > 309/405 mg/kg/day

Reproductive

NOAEL = 309/405 mg/kg/day

LOAEL > 309/405 mg/kg/day

Offspring

NOAEL = 309/405 mg/kg/day

LOAEL > 309/405 mg/kg/day

870.4100 Chronic Toxicity 

Dog

40089319

0, 50, 750 or 7500 ppm

0, 1.4, 21.4 or 237.3 mg/kg/day males

0, 1.4, 19.9, or 222.6 mg/kg/day females

Acceptable/Guideline

NOAEL = 21.4 / 19.9 mg/kg/day M/F

LOAEL = 237.3 / 222.6 mg/kg/day M/F 

based on discoloration and inflammation of 

oral mucosa; increased liver weight in the 

presence of increased AP and ALT and 

microscopic lesions.

870.4200 Carcinogenicity 

Mouse

40089317

0, 10, 150, 2500, 5000 ppm

0, 0.870, 13.35, 226, 455 mg/kg/day 

Males

0, 0.928, 13.63, 227, 460 mg/kg/day

Females

Acceptable/Guideline

NOAEL = 226 / 227 mg/kg/day M/F

LOAEL = 455 / 460 mg/kg/day M/F based 

on elevated alkaline phosphatase, ALT, 

AST, and total cholesterol, increased liver 

weights, centrilobular hepatocyte swelling 

(M) and focal hepatocellular necrosis and 

increased brown pigment deposition of 

stellate cells (F).

There was no dose-related effect on 

benign or malignant tumor formation. 
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 24 of 31

Table A.2.2. Repeated Dose Toxicity Profile of Bensulfuron-methyl Technical

Guideline 

Number Study Type MRID (year)Dose Levels, Classification Results

870.4300

Combined 

Chronic/ 

Oncogenicity 

Rat

40089316

0, 50, 750, or 7500 ppm.

0, 2.0, 30, 309 mg/kg/day males

0, 2.7, 40, 405 mg/kg/day females.

Acceptable/Guideline (chronic toxicity)

Acceptable/non-Guideline 

(carcinogenicity) because an MTD was 

not achieved. However, based on the 

weight of evidence, a new study is not 

required (TXR0057190, R. Beaver, 

08/27/2015)

NOAEL = 309 / 405 mg/kg/day M/F

LOAEL > 309 / 405 mg/kg/day M/F

Not established

There was no dose-related effect on 

benign or malignant tumor formation. 

870.6200a

Acute 

Neurotoxicity 

Rat

49623601 (2015)

0, 2000 mg/kg

Acceptable/Guideline

NOAEL = 2000 mg/kg

LOAEL > 2000 mg/kg, not established 

870.6200b

Subchronic 

Neurotoxicity 

Rat

49623602 (2015)

0, 7500, 10000, 12500, 15000ppm

0, 632, 858, 1061, 1281 mg/kg/day 

males

0, 704, 934, 1260, 1376 mg/kg/day 

females

Acceptable/non-Guideline

(study conducted for 28 days in 5 

animals/sex/dose, guidelines call for 90 

days in 10 animals/sex/dose.)

NOAEL = 1281 / 1376 mg/kg/day M/F

LOAEL > 1281 / 1376 mg/kg/day M/F, not 

established.

Waiver request granted for the requirement 

for a guideline study (TXR 0057190, R. 

Beaver, 08/27/2015)

870.7485

Metabolism and 

Pharmacokinetics

Rat

00147394

Acceptable/Guideline

Absorption of radiolabelled test article from 

the gut was nearly total. The major 

elimination routes were the urine (low-dose), 

and the feces (high-dose). No measurable 

quantities of test article or metabolites were 

found in respired air. Minute quantities of 

radioactivity (<2.1% were distributed to the 

body tissues. Approximately half of the 

doses were eliminated within 24 hours (lowdose), or 48 hours (high-dose), and nearly 

99% was eliminated within 96 hours. The 

parent compound and 6 metabolites were 

found in feces, and 8 metabolites were found 

in urine. 

870.7800 Immunotoxicity The requirement for this study has been waived (TXR 0056723, K. Rury, 8/6/2013).
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 25 of 31

Appendix B: Dietary Exposure/Risk Modeling Input

US EPA Ver. 3.16, 03-08-d

DEEM-FCID Chronic analysis for BENSULFURON

Residue file: C:\Users\dwilbur\Documents\DEEM Files\Bensulfuron\bensulfuron_chronic.r08

 Adjust. #2 NOT used

Analysis Date 10-26-2015 Residue file dated: 10-26-2015/12:21:07

Reference dose (RfD) = 0.2 mg/kg bw/day

Comment:SU - 0.492ppm EDWC - rice and crayfish only

----------------------------------------------------------------------------------

Food Crop Residue Adj.Factors

EPA Code Grp Food Name (ppm) #1 #2 

---------- ---- ------------------------------- ---------- ------ ------

8000161000 80 Fish-shellfish, crustacean 0.050000 1.000 1.000 

1500323000 15 Rice, white 0.020000 1.000 1.000 

1500323001 15 Rice, white-babyfood 0.020000 1.000 1.000 

1500324000 15 Rice, brown 0.020000 1.000 1.000 

1500324001 15 Rice, brown-babyfood 0.020000 1.000 1.000 

1500325000 15 Rice, flour 0.020000 1.000 1.000 

1500325001 15 Rice, flour-babyfood 0.020000 1.000 1.000 

1500326000 15 Rice, bran 0.020000 1.000 1.000 

1500326001 15 Rice, bran-babyfood 0.020000 1.000 1.000 

8601000000 86A Water, direct, all sources 0.492000 1.000 1.000 

8602000000 86B Water, indirect, all sources 0.492000 1.000 1.000 
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 26 of 31

Appendix C: Review of Human Research

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 are subject to ethics review 

pursuant to 40 CFR 26, have received that review, and are compliant with applicable ethics 

requirements. For certain studies that 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: 

http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/occupational-pesticidehandler-exposure-data and http://www2.epa.gov/pesticide-science-and-assessing-pesticiderisks/occupational-pesticide-post-application-exposure.
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 27 of 31

Appendix D: Occupational Non-cancer Handler Exposure Estimates and Algorithms.

Table D.1. Occupational Handler Short- and Intermediate-Term Non-Cancer Exposure and Risk Estimates for Bensulfuron-methyl on Rice. 

Exposure Scenario LOC

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 Total 

MOE8

Baseline Baseline Dose 

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

Mixer/Loader

Mixing/Loading Dry Flowables for Aerial 

Application

100

227 8.96 0.063 lb ai/A

1200 acres 0.215 170 0.00846 4,300 160

Mixing/Loading Dry Flowables for 

Groundboom Application 200 acres 0.0358 1,000 0.00141 26,000 960

Mixing/Loading Granulars for Aerial 

Application

8.4 1.7 0.064 lb ai/A

1200 acres 0.00806 4,500 0.00164 22,000 3,700

Mixing/Loading Granulars for Tractor-Drawn 

Spreader Application 200 acres 0.00135 27,000 0.000273 130,000 22,000

Mixing/Loading Liquids for Aerial 

Application

220 0.219 0.063 lb ai/A

1200 acres 0.208 170 0.000208 170,000 170

Mixing/Loading Liquids for Groundboom 

Application 200 acres 0.0346 1,000 0.0000345 1,100,000 1,000

Applicator

Applying Sprays via Aerial Equipment

100

5 0.068

0.063 lb ai/A

1200 acres 0.00473 7,700 0.0000643 560,000 7,600

Applying Sprays via Groundboom Equipment 48.6 0.34 200 acres 0.0124 2,900 0.0000535 680,000 2,900

Applying Granulars via Aerial Equipment 1.7 1.3

0.064 lb ai/A

1200 acres 0.00164 22,000 0.00125 29,000 13,000

Applying Granulars via Groundboom 

Equipment 9.9 1.2 200 acres 0.00159 23,000 0.000193 190,000 21,000

Flagger

Flagging for Aerial Application - Liquids 100 11 0.35 0.063 lb ai/A 350 acres 0.00304 12,000 0.0000965 380,000 12,000
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 28 of 31

Table D.1. Occupational Handler Short- and Intermediate-Term Non-Cancer Exposure and Risk Estimates for Bensulfuron-methyl on Rice. 

Exposure Scenario LOC

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 Total 

MOE8

Baseline Baseline Dose 

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

Flagging for Aerial Application - Granulars 2.75 0.15 0.064 lb ai/A 0.00077 47,000 0.000042 860,000 45,000

1 Based on the “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table” (02/01/2015); Level of mitigation: Baseline. Note that aerial applicators are assessed as enclosed cockpit 

and baseline represents engineering controls. 

2 Based on registered Bensulfuron-methyl labels.

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 (100%) ÷ BW 

(80 kg).

5 Dermal MOE = Dermal NOAEL (36.3 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 (80 kg).

7 Inhalation MOE = Inhalation NOAEL (36.3 mg/kg/day) ÷ Inhalation Dose (mg/kg/day).

8 Total MOE = NOAEL (mg/kg/day) ÷ Dermal Dose + Inhalation Dose.
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 29 of 31

Appendix E. Nomenclature and Physical/Chemical Properties

Chemical Identity Table

Table E.1. Chemical Identity of Bensulfuron-methyl

Common Name bensulfuron-methyl

Company Experimental Name DPX-F5384

PC Code 128820

IUPAC Name of Acid a α-[(4,6-dimethoxypyrimidin-2-ylcarbamoyl)sulfamoyl]-o-toluic acid

CAS Name of Acid a 2-[[[[[(4,6-dimethoxy-2-

pyrimidinyl)amino]carbonyl]amino]sulfonyl]methyl]benzoic acid

CAS No. 83055-99-6

Registration Review Case No. 7216-1

Chemical Class` Sulfonylurea

End-Use Products Londax® Herbicide, DF, 60% w/w (EPA Reg. No. 70506-147)

Londax® Herbicide, G, 0.32% w/w (EPA Reg. No. 70506-149)

Duet® DF, 80% propanil and 0.62% bensulfuron-methyl w/w (EPA Reg. No. 

71085-16)

Duet® 60 DF, 60.0% propanil and 0.46% bensulfuron-methyl w/w (EPA Reg. 

No. 71085-23)

Duet® Herbicide, EC, 41.2% propanil and 0.32% bensulfuron-methyl (0.031 

lb/lb formulated product) (EPA Reg. No. 71085-9)

Chemical Structure

a Bensulfuron-methyl is the methyl ester of the acid.

Table E.2. Physicochemical Properties of Technical Grade Bensulfuron-methyl

Parameter Value Reference

Melting point/range (C) 181 40089309

Boiling point (C) Decomposes on melting 40089309

pH 6.4 to 6.9 (slurry in water) 40089309

Density 1.41 g/cc 40089309

Water solubility (25C) 0.0029 mg/ml at pH 4.8

0.012 mg/ml at pH 5.8

0.120 mg/ml at pH 6.9

40089309

Solvent solubility (g/l at 20C) hexane 0.00031

ethyl acetate 1.66

methylene chloride 11.72

xylene 0.28

acetonitrile 5.38

methanol 0.99

acetone 1.38

40089309

Vapor pressure at 25C 2.1 X 10-4 mm Hg 40089309

Dissociation constant (pKa) 5.2 40089309

Octanol/Water Partition Coefficient (Kow) 282 at pH 1.5

4.1 at pH 7.0

40089309

UV/visible absorption spectrum (λmax, nm) Not available -
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 30 of 31

Appendix F. International Harmonization

Bensulfuron-methyl (128820; 10/26/15)

Table F.1. Summary of US and International Tolerances and Maximum Residue Limits 

Residue Definition:

US Canada Mexico1 Codex

40 CFR §180.445(a): Tolerances are established for 

residues of the herbicide bensulfuron-methyl (methyl2[[[[[(4,6-dimethoxy-pyrimidin-2-yl) amino] carbonyl] 

amino] sulfonyl] methyl] benzoate)

None None

Commodity1 Tolerance (ppm) /Maximum Residue Limit (mg/kg)

US Canada Mexico1 Codex

Crayfish 0.05

Rice, grain 0.02

Rice, straw 0.3

Completed by: D. Wilbur; 10/26/2015

1 Mexico adopts US tolerances and/or Codex MRLs for its export purposes.
Bensulfuron-Methyl Human Health Risk Assessment D429515

Page 31 of 31

Appendix G. DFR Data Waiver Rationale

Dislodgeable Foliar Residue (DFR): In accordance with 40 CFR 158, 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 

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 bensulfuron-methyl, 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 bensulfuron-methyl (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 post-application 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 

bensulfuron-methyl 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 = 1,800 compared to the LOC of 

100); EPA is waiving the 40CFR DFR data requirement. In this instance, it is unlikely that 

chemical-specific 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 bensulfuron-methyl.