UNITED ST ATES ENVIRONMENT AL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MEMORANDUM 

Date: September 16, 20 15 

OFFICE OFCHEMICAL SAFETY 

AND POLLUTION PREVENTION 

SUBJECT: Sulfosulfuron. Draft Human Health Risk Assessment in Support of Registration 

Review. 

PC Code: 08560 1 

Decision No.: 505 178 

Petition No.: Not Applicable (NA) 

Risk Assessment Type: Single Chemical Aggregate 

TXRNo.: NA 

MRID No.: NA 

DP Barcode: 427399 

Registration Nos.: 524-500, 524-525, 

524-533, 524-534. 

Regulatory Action: Registration Review 

Case No.: 724 7 

CAS No.: 141776-32-1 

40 CFR: § 180.552 

FROM: Bonnie Cropp-Kohlligian, Risk Assessor -:rs~ ~ -'t\~\~ Abdallah Khasawinah, Ph.D., Toxicologist ~ ~ 

Kelly O'Rourke, ORE Assessor ~ n . () 1 Y'...a~ 

Risk Assessment Branch (RAB) TV 

Health Effects Division (HED) (7509P) 

THROUGH: C

RAB 

harles 

IV

w. 

, HED 

Smith 

(7509P) 

m, Acting Branch Chief C ~ 

TO: Kelly Ballard and Thomas Moriarty (RM 51) 

Risk Management and Implementation Branch I 

Pesticide Re-Evaluation Division (7508P) 

Sulfosulfuron is a selective broad leaf herbicide belonging to the sulfonylurea group of 

herbicides. This document evaluates the existing uses of sulfosul furon as part of Registration 

Review and represents the draft risk assessment (ORA). The Agency is reviewing all the 

sulfonylurea herbicides jointly under Registration Review. 

Since the last human health risk assessment and scoping document, the following 

changes/updates have been incorporated for sulfosulfuron. 

1) The immunotoxicity and inhalation toxicity study requirements have been waived. 

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Sulfosulfuron (085601) Draft Human Health Risk Assessment DP#: 427399 

2) The short-term incidental oral endpoint and point of departure have been changed and are 

now based on a subchronic toxicity study rather than a chronic/carcinogenicity study 

since the subchronic study duration is considered more appropriate for assessing this 

exposure scenario. 

3) The short-term incidental oral risk assessment has been updated to incorporate new 

science policies. Consequently, the short-term aggregate risk assessment has also been 

updated. 

4) Previously identified deficiencies related to the enforcement method have been resolved. 

5) A high-end drinking water exposure value was used to assess screening-level dietary 

exposure/risk estimates and dietary assessments were conducted with an updated version 

of DEEM which uses updated food consumption data. 

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Sulfosulfuron (085601) Draft Human Health Risk Assessment DP#: 427399

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Table of Contents

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

2.0 HED Recommendations .................................................................................................... 5

2.1 Tolerance Considerations................................................................................................. 5

3.0 Introduction........................................................................................................................ 6

3.1 Chemical Identity and Physical/Chemical Characteristics............................................... 6

3.2 Pesticide Use Pattern and Anticipated Exposure Pathways............................................. 6

3.3 Consideration of Environmental Justice .......................................................................... 8

4.0 Hazard Characterization and Dose-Response Assessment............................................ 8

4.1 Summary of Toxicological Effects .................................................................................. 9

4.2 Safety Factor for Infants and Children (FQPA Safety Factor)....................................... 10

4.3 Toxicity Endpoint and Point of Departure Selections.................................................... 10

4.4 Endocrine Disruption ..................................................................................................... 11

5.0 Dietary Exposure and Risk Assessment......................................................................... 12

5.1 Water Residue Profile .................................................................................................... 12

5.2 Food Residue Profile...................................................................................................... 13

5.3 Dietary Exposure and Risk Estimates............................................................................ 13

6.0 Residential (Non-Occupational) Exposure/Risk Characterization ............................. 14

6.1 Spray Drift...................................................................................................................... 15

7.0 Aggregate Exposure/Risk Characterization.................................................................. 16

7.1 Short-term Aggregate Risk............................................................................................. 17

7.2 Chronic Aggregate Risk................................................................................................. 17

8.0 Cumulative Exposure/Risk Characterization ............................................................... 17

9.0 Occupational Exposure/Risk Characterization ............................................................ 18

10.0 Public Health and Pesticide Epidemiology Data........................................................... 18

11.0 Literature References...................................................................................................... 18

12.0 References......................................................................................................................... 19

Appendix A. Toxicology Profile and Executive Summaries................................................ 20

A.1 Toxicology Data Requirements...................................................................................... 20

A.2 Toxicity Profiles................................................................................................................. 21

Appendix B. Dietary Exposure/Risk Modeling Input and Output ..................................... 24

Appendix C. Nomenclature and Physical/Chemical Properties.......................................... 26

Appendix D. Review of Human Research ............................................................................. 27

Appendix E. Submittal of Analytical Reference Standards (860.1650).............................. 27

Appendix F. TTR Data Waiver Criteria ............................................................................... 28
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1.0 Executive Summary

Sulfosulfuron (N-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]-2-(ethylsulfonyl)imidazo

[1,2-a]pyridine-3-sulfonamide) is a selective broadleaf sulfonylurea (SU) herbicide registered for 

the control of various annual grasses and/or broadleaf weeds in wheat, pastures, rangelands and 

highly managed residential and commercial non-crop turf sites such as apartment complexes, 

athletic fields, cemeteries, golf courses, hotel properties, office complexes, parks, public turf 

areas, retail sites, school grounds, sod and turfgrass seed farms. It is also used in forestry and for 

conifer release and on a number of other non-crop use sites such as roadsides, utility rights-ofway, airports, fallow areas, ditch banks, dry ditches, dry canals, fencerows, industrial sites, 

lumberyards, manufacturing sites, petroleum tank farms, pumping installations, railroads, storage 

areas, utility substations, warehouse areas and wildlife areas. There is no explicit prohibition 

against purchase and/or use of sulfosulfuron products by homeowners. 

The most recent human health risk assessment for sulfosulfuron was completed in 2008 

(D349702). Since then, no new sulfosulfuron data have been received and the only condition of 

registration, completion of a petition method validation (PMV) of an enforcement method, has 

been satisfied (D427730). A human health scoping document was completed for sulfosulfuron

in 2011 (D385545) and immunotoxicity and subchronic inhalation toxicity studies were 

identified as data gaps. However, the subchronic inhalation toxicity study was later waived by 

HED (D394271) and the HED Hazard and Science Policy Council (HASPOC) has since 

determined that both immunotoxicity and subchronic inhalation toxicity data are not required 

(TXR 0056762, TXR 0056723 and TXR 0052986). 

The toxicology, residue chemistry and occupational/residential exposure (ORE) databases for 

sulfosulfuron are considered complete for risk assessment. HED is recommending for the 

removal of established tolerances for residues of sulfosulfuron in hog commodities (D427730) 

and the current tolerance expression for sulfosulfuron must be updated in accordance with HED 

guidance (see Section 2.1). An analytical reference standard for the ethyl sulfone chemophore 

metabolite of sulfosulfuron must be submitted to the EPA National Pesticide Standards 

Repository (see Appendix E).

No toxicity endpoints have been identified for acute dietary, dermal or inhalation routes of 

exposure. The toxicity endpoint for chronic dietary exposure continues to be based on a 

chronic/carcinogenicity study; however, the short-term incidental oral endpoint is now based on 

a subchronic toxicity study rather than a chronic/carcinogenicity study since the subchronic study 

duration is considered more appropriate for assessing this exposure scenario. Sulfosulfuron is 

not likely to be carcinogenic to humans at doses that do not cause crystals with subsequent 

calculi formation resulting in cellular damage of the urinary tract.

A screening-level chronic dietary exposure and risk assessment was conducted for sulfosulfuron

using tolerance-level residues and default processing factors for foods, 100% crop treated and a 

sulfonylurea-class-wide screening-level estimate of residues for drinking water. Chronic dietary 

risk estimates range from 3.2 to 11% of the chronic population adjusted dose (cPAD) and are not 

of concern to HED, being less than the level of concern (LOC = 100% cPAD). 
Sulfosulfuron (085601) Draft Human Health Risk Assessment DP#: 427399

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Since there is no explicit prohibition against purchase and/or use of sulfosulfuron containing 

products by homeowners, based on the use sites/patterns, potential residential exposure scenarios 

may include short-term exposures to adult handlers (mixers, loaders, applicators, etc.) and postapplication exposures to adults and children. However, no hazard via the dermal or inhalation 

route has been identified (for any duration). Only short-term incidental oral exposures (i.e., 

hand-to-mouth, object-to-mouth, and soil ingestion) from residential turf use of sulfosulfuron are 

expected for children. The short-term incidental oral exposures for children were assessed and 

resulted in margins of exposure (MOEs) of ≥740,000 and are not of concern to HED, being 

greater than the LOC (100). 

Short-term aggregate exposure for sulfosulfuron resulting from short-term incidental oral 

exposure (from residential turf) and dietary exposure (food and water) is expected for children. 

The short-term aggregate exposure for children from incidental oral and dietary exposures was 

assessed and resulted in a MOE of 6,300 and is not of concern to HED, being greater than the 

LOC (100). Chronic aggregate exposure for sulfosulfuron resulting from dietary exposure (food 

and water) is discussed above.

Occupational handlers/workers may be exposed to sulfosulfuron during mixing, loading, and/or 

applying the herbicide as well as during post-application activities. However, no hazard via the 

dermal or inhalation route has been identified (for any exposure duration); hence, a quantitative

occupational risk assessment was not conducted. Labels require personal protective equipment 

(PPE) consisting of baseline attire only (i.e., long-sleeved shirt, long pants, and shoes plus socks)

and a restricted entry interval (REI) of 12 hours which are considered adequately protective. 

2.0 HED Recommendations

2.1 Tolerance Considerations

The existing tolerances (40 CFR §180.552) are supported by the available residue chemistry 

data. There are no established Codex Canadian or Mexican maximum residue limits (MRLs) for 

residues of sulfosulfuron with the exception of a Canadian MRL in/on wheat grain which is 

harmonized with the U.S. tolerance in/on wheat grain (0.02 ppm) with regards to both definition 

and limits. 

The current tolerance expression for sulfosulfuron should be revised, in accordance with the 

HED Interim Guidance on Tolerance Expressions (S. Knizner, 5/27/2009), to the following:

Tolerances are established for residues of sulfosulfuron (N-[[(4,6-dimethoxy-2-

pyrimidinyl)amino]carbonyl]-2-(ethylsulfonyl)imidazo[1,2-a]pyridine-3-sulfonamide), 

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 those sulfosulfuron residues convertible to 2-(ethylsulfonyl)-imidazo[1,2-a]pyridine, 

expressed as the stoichiometric equivalent of sulfosulfuron.

Tolerances for residues of sulfosulfuron in livestock commodities were re-evaluated (D427730) 

and it was determined that there is no reasonable expectation of finite residues of concern in 
Sulfosulfuron (085601) Draft Human Health Risk Assessment DP#: 427399

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swine (i.e., Category 3 of 40 CFR 180.6(a)). Therefore, HED is recommending for the removal 

of established tolerances for residues of sulfosulfuron in fat (0.005 ppm), meat (0.005 ppm) and 

meat byproducts (0.05 ppm) of hog. This recommendation is also a consequence of the reevaluation of the enforcement methods (D427730) and the finding that the limits of quantitation 

for these methods is 0.01 ppm. 

3.0 Introduction

3.1 Chemical Identity and Physical/Chemical Characteristics

Sulfosulfuron (N-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]-2-(ethylsulfonyl)imidazo

[1,2-a]pyridine-3-sulfonamide) is a selective broadleaf herbicide belong to the sulfonylurea class 

of chemicals. The chemical properties of sulfosulfuron do not suggest that there are any 

particular exposure issues that warrant special consideration. The compound has multiple 

dissociation constants, making its water solubility dependent on pH, with lower solubility under 

more acidic conditions. The potential for sulfosulfuron to partition into fatty matrices is also pH 

dependent; however, based on the octanol/water partitioning coefficients, such partitioning is 

unlikely to occur. Sulfosulfuron has a relatively low vapor pressure, indicating that inhalation of 

vapors is unlikely to be a significant source of exposure under ambient conditions. The structure 

and physical/chemical properties of sulfosulfuron are provided in Appendix C.

3.2 Pesticide Use Pattern and Anticipated Exposure Pathways

Sulfosulfuron exhibits systemic post-emergence herbicidal activity on a broad spectrum of 

annual and perennial sedges, grasses, and broadleaf weeds, but does not injure many warmseason and some cool-season grasses. Sulfonylurea herbicides disrupt amino acid biosynthesis 

in susceptible plants by binding to the acetolactate synthase (ALS) enzyme. 

Sulfosulfuron is currently registered to Monsanto Company as a selective pre- and post-emergent 

herbicide for the control of various annual grasses and/or broadleaf weeds in wheat, pastures, 

rangelands and highly managed residential and commercial turf non-crop sites such as apartment 

complexes, athletic fields, cemeteries, golf courses, hotel properties, office complexes, parks, 

public turf areas, retail sites, school grounds, sod and turfgrass seed farms. It is also used in 

forestry and for conifer release and on a number of other non-crop sites such as roadsides, utility 

rights-of-way, airports, fallow areas, ditch banks, dry ditches, dry canals, fencerows, industrial 

sites, lumberyards, manufacturing sites, petroleum tank farms, pumping installations, railroads, 

storage areas, utility substations, warehouse areas and wildlife areas. Sulfosulfuron formulations 

include water dispersible granule (WDG; 3 end-use products) and suspension concentrate (SC; 1 

end-use product). Applications are made by ground or aerial equipment. 

There is no explicit prohibition against purchase and/or use of sulfosulfuron products by 

homeowners; hence, potential residential exposure scenarios may occur. Also, sulfosulfuron 

may be applied by professional commercial operators to lawn areas (such as apartment 

complexes, parks, schools, recreational areas and public areas) where residents may be expected 

to come into contact with sulfosulfuron residues.
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Individuals may be exposed to sulfosulfuron via their diet (food and water) and there is the 

potential for exposure in residential settings, including short-term exposures to adult handlers 

(mixers, loaders, applicators, etc.) and post-application exposures to adults and children. 

Occupational handlers/workers may be exposed (dermal and inhalation) to sulfosulfuron during 

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

Based on the use pattern, the duration of exposure for occupational handlers is expected to be 

short-term and intermediate-term but not long-term. The personal protective equipment (PPE) 

requirement on the labels consists of baseline attire only (i.e., long-sleeved shirt, long pants and 

shoes plus socks). The restricted entry interval (REI) on all labels is 12 hours. 

Table 3.2. Summary of Directions for Registered Use of Sulfosulfuron.

Applic. Type, and 

Equipment

Formulation

[EPA Reg No.]1

Max. Applic. 

Rate

(lb ai/A/applic.)

Max. No.

Applic. 

per 

Season

Max. Yearly

Applic. Rate 

(lb ai/A)

PHI

(days)

Use Directions and Limitations

Grass – Pastures and Rangeland

Broadcast;

Ground or Aerial

75% WDG

[524-500]

0.09 2 0.125 0 forage

14 hay

For use on well-established 

pastures. Applications may be 

made from early spring through 

the fall; follow-up applications 

may be made after suitable 

regrowth of weeds but no 

sooner than 30 days after initial 

application. Addition of a 

nonionic surfactant (NIS) at

0.25% by volume is required. 

Wheat

Broadcast;

Ground or Aerial

75% WDG

[524-500]

0.03 1 0.03 0 forage

30 hay

55 straw

55 grain

Applied either pre- or postemergence on winter wheat; 

apply only post-emergence for 

spring wheat.

75% WDG

[524-525]

Ornamentals

(i.e., for use on woody ornamentals, perennial groundcovers and ornamental grasses growing in landscaped areas or field production nurseries)

Broadcast;

Ground or Aerial

75% WDG

[524-534]

0.09 2 0.125 N/A

Residential/Commercial Turf

(i.e., for use on highly managed turf, sod farms and native grass sites such as apartment complexes, athletic fields, cemeteries, golf courses, hotel 

properties, office complexes, parks, public turf areas, retail sites, school grounds, sod and turfgrass seed farms)

Broadcast;

Ground or Aerial

75% WDG

[524-534]

0.09 2 0.125 N/A Do not apply directly to or 

within 4 feet of golf course 

putting greens.

24.1% SC

[524-533]

Use limited to golf courses 

(excluding greens) and sod 

farms. Do not apply to golf 

course greens or within 4 feet of 

these sites.

Forestry and Conifer Release

Broadcast;

Ground or Aerial

75% WDG

[524-500]

0.06-0.09 2 0.125 N/A
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Table 3.2. Summary of Directions for Registered Use of Sulfosulfuron.

Applic. Type, and 

Equipment

Formulation

[EPA Reg No.]1

Max. Applic. 

Rate

(lb ai/A/applic.)

Max. No.

Applic. 

per 

Season

Max. Yearly

Applic. Rate 

(lb ai/A)

PHI

(days)

Use Directions and Limitations

Noncrop Areas

(i.e., roadsides, utility rights-of-way, airports, fallow areas, ditch banks, dry ditches, dry canals, fencerows, industrial sites, lumberyards, manufacturing 

sites, petroleum tank farms, pumping installations, railroads, storage areas, utility substations, warehouse areas, wildlife areas)

Broadcast;

Ground or Aerial

75% WDG

[524-500]

0.09 2 0.125 N/A Do not apply on or around 

athletic fields, commercial turf 

sites, golf courses, residential 

turf sites or sod and turfgrass 

seed farms. 

1 There are four currently registered end-use products containing sulfosulfuron as the active ingredient: (1) EPA 

Registration No. 524-500; Maverick Herbicide; 75% Water (EPA Acceptance Date 9/22/2010; (2) EPA Registration 

No. 524-533; MON 44940 SC Herbicide (EPA Acceptance Date 2/27/2002); (3) EPA Registration No. 524-525; 

Maverick C/A Herbicide (EPA Acceptance Date 8/2/2001); and (4) EPA Registration No. 524-534; MON 44951 

Herbicide (EPA Acceptance Date 12/4/2006) and Supplemental (EPA Acceptance Date 1//25/2010).

3.3 Consideration of Environmental Justice

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

human health risk assessment, in accordance with U.S. Executive Order 12898, "Federal Actions 

to Address Environmental Justice in Minority Populations and Low-Income Populations," 

(http://epa.gov/compliance/ej/resources/policy/exec_order_12898.pdf). 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 U.S. Department of 

Agriculture’s (USDA’s) National Health and Nutrition Examination Survey/What We Eat in 

America, (NHANES/WWEIA), 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 and Dose-Response Assessment

The toxicology database for sulfosulfuron is complete and adequate for risk assessment. 

Immunotoxicity and inhalation studies are part of the current 40 CFR Part 158 Toxicology Data 

Requirements. However, the HASPOC determined that these studies are not required at this time 

for sulfosulfuron (TXR 0056762, TXR 0056723 and TXR 0052986). The TOXLINE (National 

Library of Medicine) database literature search did not identify any new toxicological 

information not already considered. No new toxicity and/or metabolism data have been received 
Sulfosulfuron (085601) Draft Human Health Risk Assessment DP#: 427399

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since the most recent human health risk assessment for sulfosulfuron was completed in 2008 

(D349702). The endpoints selected for the previous risk assessment remain the same except for 

the short-term incidental oral endpoint that is now based on a subchronic toxicity study rather 

than a chronic/carcinogenicity study since the subchronic study duration is considered more 

appropriate for assessing this exposure scenario. For a summary of the acute, subchronic and 

chronic toxicity profile, see Appendix A.

4.1 Summary of Toxicological Effects

Sulfosulfuron has low acute oral, dermal, and inhalation toxicity (Acute Toxicity Category IV

for oral, dermal and inhalation). It is nonirritating to skin and slightly irritating to eyes (Category 

III). It is not a skin sensitizer. The subchronic toxicity studies in rats, mice, and dogs 

demonstrate that the primary effects of sulfosulfuron were observed at high doses, and included 

urinary crystals, bladder stones and associated pathology of the urinary bladder, kidney and 

ureter.

In the chronic rat and mouse toxicity studies, urinary crystals, bladder stones and associated 

pathology of the urinary bladder, kidney and ureter were also observed at high doses. In the rat, 

single incidences of rarely observed urinary bladder transitional cell papilloma and carcinoma 

were reported in 2 different females at 5,000 ppm (314.1 mg/kg/day) and in the mouse there was 

an increased incidence of benign mesenchymal bladder tumors in the male and a single renal 

adenoma in both high dose males and females.

In accordance with the Agency's Proposed Guidelines for Carcinogenic Risk Assessment (10-

APR-1996), the CARC classified sulfosulfuron as “not likely to be carcinogenic to humans” at 

doses that do not cause crystals with subsequent calculi formation resulting in cellular damage of 

the urinary tract. The current endpoint selected for chronic RfD is based on the NOAEL of 500 

ppm (24.4 mg/kg/day) from the carcinogenicity study in rats and is considered protective of 

cancer and noncancer effects.

The results of the 2-generation reproduction and developmental toxicity studies indicate that 

sulfosulfuron is not a developmental or reproductive toxicant. The acute and subchronic 

neurotoxicity studies show that sulfosulfuron is not neurotoxic.

The mutagenic test battery demonstrated that sulfosulfuron is not mutagenic at non-cytotoxic 

concentrations. An in vitro Chinese hamster lung point mutation assay was positive, only under 

conditions of non-activation and at levels that caused precipitation.

The toxicity of sulfosulfuron appears to be dependent on saturation in the urine, followed by 

precipitation and formation of urinary crystals and bladder stones. The metabolism study in the 

rat shows that sulfosulfuron is excreted largely un-metabolized (80%-90% of administered dose). 

Excretion at a low dose (10 mg/kg) occurs primarily in the urine (77%-87% of dose); whereas, at 

a high dose (1,000 mg/kg), a large percentage of the administered dose is excreted in the feces 

(55%-63%). Sulfosulfuron is rapidly excreted and is not retained in tissues to any significant 

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

The toxicity database of sulfosulfuron is complete and adequate to assess the qualitative or 

quantitative susceptibility in the young. There is no evidence of increased qualitative or 

quantitative susceptibility in the young, there is no evidence of neurotoxicity with sulfosulfuron,

and exposure estimates are unlikely to underestimate risk; therefore, the FQPA Safety Factor is 

reduced to 1X. 

4.3 Toxicity Endpoint and Point of Departure Selections

There have been no changes to the prior dose-response assessment and cancer classification

except for the short-term incidental oral endpoint. In the previous risk assessment (D349702), the 

endpoint of toxicity for assessing this exposure scenario was based on the rat 

chronic/carcinogenicity study with a NOAEL of 24 mg/kg/day. The current assessment is based 

on a NOAEL of 100 mg/kg/day from a subchronic dog toxicity study where the study duration is 

more appropriate for assessing this exposure scenario.

Table 4.3. Sulfosulfuron Summary of Toxicological Doses and Endpoints for Use in Dietary and 

Occupational Human Health Risk Assessments.

Exposure Scenario Point of 

Departure

Uncertainty/

FQPA SFs

Population 

Adjusted Dose 

for Risk 

Assessment

Study and Toxicological Effects

Acute Dietary 

(General 

Population 

including Infants 

and Children)

A single dose effect relevant to the general US population including infants and children 

was not identified in the toxicity studies conducted with sulfosulfuron [including 

developmental toxicity studies in the rat and the rabbit (at up to 1,000 mg/kg/day) and an 

acute neurotoxicity study in the rat (at up to 2,000 mg/kg)]. 

Acute dietary 

(Females 13-49 

years of age)

No appropriate endpoint was identified including developmental toxicity studies in rats and 

rabbits.

Chronic Dietary 

(All Populations)

NOAEL = 24 

mg/kg/day

UFA = 10x

UFH =10x

FQPA SF= 1x

RfD= 0.24 

mg/kg/day

cPAD = 0.24 

mg/kg/day

Chronic toxicity/carcinogenicity -

rat; MRID 44295759 

LOAEL = 244.2 mg/kg/day based 

on urinary tract pathology, 

abnormal crystals and urinary 

calculi (both sexes); mineralization 

in heart, lung, pancreas, and skeletal 

muscles (male).

Short-term 

Incidental Oral

NOAEL = 100

mg/kg/day

UFA = 10x

UFH =10x

FQPA SF= 1x

LOC for MOE 

= 100

Subchronic oral toxicity study-dog, 

MRID 44295751 

LOAEL = 300 mg/kg/day based on 

lesions in the urinary bladder in 

females occurring subsequent to 

urinary formation/urolithiasis and 

on abnormal urinary crystals in 

males and females.

Dermal

(Any time period)

This risk assessment is not required. No dermal or systemic toxicity was seen following 

repeated dermal application at the limit dose in a 21-day dermal toxicity study in rats. 
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Table 4.3. Sulfosulfuron Summary of Toxicological Doses and Endpoints for Use in Dietary and 

Occupational Human Health Risk Assessments.

Exposure Scenario Point of 

Departure

Uncertainty/

FQPA SFs

Population 

Adjusted Dose 

for Risk 

Assessment

Study and Toxicological Effects

Inhalation 

(Any time period)

Based on the low acute inhalation toxicity (Category IV), and the low application rates for 

the proposed use patterns ranging from 25 - 101 g ai/hectare (10-41 g ai/acre), there is 

negligible concern for potential inhalation exposure and risk. Therefore, a separate 

inhalation risk assessment is not required. A subchronic inhalation study has been waived 

by HASPOC (TXR 0052986)

Cancer Not likely to be carcinogenic to humans at doses that do not cause crystals with 

subsequent calculi formation resulting in cellular damage of the urinary tract. The current 

endpoint selected for chronic RfD based on the NOAEL of 500 ppm (24.4 mg/kg/day) 

from the carcinogenicity study in rats is considered protective of cancer and non-cancer 

effects.

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

and used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant 

human exposures. NOAEL = no observed adverse effect level. LOAEL = lowest observed adverse effect level. 

UF = uncertainty factor. UFA = extrapolation from animal to human (interspecies). UFH = potential variation in 

sensitivity among members of the human population (intraspecies). FQPA SF = FQPA Safety Factor. PAD = 

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

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 sulfosulfuron, 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), 

sulfosulfuron 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 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 
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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, 20131and 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 

website2.

5.0 Dietary Exposure and Risk Assessment 

5.1 Water Residue Profile

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

Pesticide Root Zone Model for GroundWater (PRZM-GW; v.1.07) for use in the sulfonylurea 

(SU) dietary risk assessments. Rather than produce chemical-specific estimated drinking water 

concentrations (EDWCs) following the usual assessment procedures, EFED provided coarsescreen estimates that should exceed upper-bound, chemical-specific 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 the highest persistence to any 

route of degradation over time. The resulting coarse-screen EDWCs from PRZM-GW were used 

as conservative estimates of exposure and are summarized in Table 5.1. (D427429). 

The chronic dietary assessment for sulfosulfuron used the post-breakthrough mean EDWC value 

of 492 μg/L (0.492 ppm). 

Table 5.1. PRZM-GW Coarse-Screen EDWCs for Sulfonylureas1.

Modeled Scenario Kd or KOC2

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

FL citrus

Kd 7 429 3.2 351

KOC 7 467 2.3 349

 

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

chemicals.

2 http://www.epa.gov/endo/
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Table 5.1. PRZM-GW Coarse-Screen EDWCs for Sulfonylureas1.

Modeled Scenario Kd or KOC2

Initial Application 

Dates (days postemergence)

Max. Daily Conc. 

(μg/L)

Mean 

Breakthrough 

Time (yrs)

Postbreakthrough 

Mean (μg/L)

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 Maximum values are bolded.

2 Kd = soil-water partition coefficient. Koc = organic carbon-water partition coefficient.

5.2 Food Residue Profile

Sulfosulfuron is registered for use on wheat and a tolerance has been established for residues 

in/on wheat grain at 0.02 ppm. Sulfosulfuron tolerances have also been established for residues 

in ruminant tissue ranging from 0.005-0.3 ppm and in milk at 0.02 ppm. In conducting this 

assessment, HED has assumed tolerance-level residues, DEEM default processing factors, and 

100 percent crop treated.

5.3 Dietary Exposure and Risk Estimates

Exposure and risk estimates were obtained from the Dietary Exposure Evaluation Model using 

the Food Commodity Intake Database (DEEM-FCID; version 3.18). The model uses food 

consumption data from the 2003-2008 NHANES/WWEIA 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 sulfosulfuron, the chronic dietary risk estimates (Table 5.3) range from 3.2 to 11% 

of the cPAD and are below HED’s level of concern (LOC = 100% cPAD). Because of the very 

conservative assumptions used in the analysis (tolerance level residues, 100 % crop treated, 

DEEM default processing factors, upper-bound modeled drinking water estimates), actual 

exposure and risk are expected to be much lower than those shown in Table 5.3. The listings of 

inputs and outputs to the assessment are included in Appendix B. HED did not conduct an acute 

dietary exposure/risk assessment due to the lack of an endpoint appropriate for acute dietary 

assessment. Based on the cancer classification, a cancer dietary risk assessment is not required. 
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Table 5.3. Summary of dietary exposure and risk estimates for sulfosulfuron.

Acute Estimates Chronic Estimates

Population Group

Exposure,

mg/kg bw

Risk,

% aPAD

Exposure,

mg/kg bw/day

Risk,

% cPAD

Total US Population Not Applicable 0.010480 4.4

All Infants (< 1 year old) 0.026819 11

Children 1-2 years old 0.015834 6.6

Children 3-5 years old 0.013104 5.5

Children 6-12 years old 0.009366 3.9

Youth 13-19 years old 0.007671 3.2

Adults 20-49 years old 0.010387 4.3

Adults 50-99 years old 0.010260 4.3

Female 13-49 years old 0.010351 4.3

6.0 Residential (Non-Occupational) Exposure/Risk Characterization

Sulfosulfuron is registered for weed control in landscaped areas including highly managed 

residential and commercial non-crop turf sites such as apartment complexes, athletic fields, golf 

courses, hotel properties, parks, public turf areas, school grounds, sod and turfgrass seed farms. 

Previous risk assessments did not identify a residential turf scenario; however, it is evaluated in 

this assessment as a screening measure. Although the registered products are intended for 

professional and commercial applicators, they are not labeled as restricted-use products; hence,

homeowners may purchase and use these products on residential lawns, resulting in the potential 

for residential handler exposure. However, a quantitative handler exposure assessment is not 

applicable due to the absence of toxicity endpoints and associated PODs for residential dermal 

and inhalation routes of exposure. 

Post-application exposures are also expected for adults and children following use of 

sulfosulfuron on residential sites. These exposures include dermal exposures for adults and 

children, and incidental oral (i.e., hand-to-mouth, object-to-mouth, and soil ingestion) exposure 

for children. Because there is no hazard associated with dermal exposure, only incidental oral 

exposure has been evaluated for children. A series of assumptions and exposure factors served 

as the basis for completing the residential post-application risk assessment. Each assumption, 

factor and algorithm used to estimate residential post-application exposure and dose is detailed in 

the 2012 Residential SOPs3. Table 6.0 presents the risk estimates for hand-to-mouth, objects-tomouth, and soil ingestion; all of which yield MOEs greater than the LOC of 100, and therefore 

are not of concern. There are no post-application risks of concern associated with residential 

uses of sulfosulfuron.

 

3 Available: http://www.epa.gov/pesticides/science/residential-exposure-sop.html
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Table 6.0. Residential Post-application Non-cancer Exposure and Risk Estimates for Sulfosulfuron.

Lifestage

Post-application 

Exposure Scenario Application 

Rate1

Dose 

(mg/kg/day)2 MOEs3

Use Site Route of Exposure

Child Turf

Incidental oral

Hand to mouth

0.09 lb ai/A

0.00014 740,000

Incidental oral

Object to mouth 0.0000083 12,000,000

Incidental oral

Soil ingestion 0.0000030 33,000,000

1 Based on registered label (EPA Reg. No. 524-534).

2 Dose (mg/kg/day) equations:

Hand-to-Mouth Dose = hand residue loading (0.000015 mg/cm2) × fraction of hand mouthed (0.127) × surface area of 1 hand

(150 cm2) × exposure time (1.5 hrs/day) × # of replenishment intervals/hr (4 int/hr) × (1-((1-saliva extraction factor 

(0.5))^(Number of hand-to-mouth events per hour (13.9 events/hr) ÷ # of replenishment intervals/hr)) ÷ body weight (11 kg).

Object-to-Mouth Dose = object residue loading (0.002 μg/cm2) × unit conversion factor (0.001 mg/μg) × object surface area 

mouthed / event (10 cm2/event) × exposure time (1.5 hrs/day) × # replenishment intervals/hr (4 int/hr) × (1-((1- saliva 

extraction factor (0.50))^(# Object-to-Mouth Events/hr (8.8 events/hr) ÷ # replenishment intervals/hr)) ÷ body weight (11 kg).

Soil Ingestion = soil residue (0.67 μg/g) × ingestion rate (50 mg/day) × conversion factor (0.000001 g/μg) ÷ body weight (11 

kg).

TTR for solid application rate of 0.09 lb ai/A x 0.2% x (1-10%)0 x conversion factor (ug/lb) x conversion factor (acre/cm2)= 

0.002 μg/cm2.

3 Incidental Oral MOE = Oral NOAEL (100 mg/kg/day) ÷ Incidental oral Dose (mg/kg/day). Note: LOC is 100.

In conjunction with the 2007 Part 158 Data Requirements, HED typically requires submission of 

a turf transferable residue (TTR) study in order to determine exposure and risk associated with 

children playing on treated turf. Since the estimated residential turf post-application exposure 

for residential turf using default TTR values for sulfosulfuron is minimal in comparison to the 

level of concern (i.e., the calculated MOE is greater than 10 times higher than the level of 

concern, lowest MOE = 740,000 compared to the LOC of 100); EPA is waiving the 40CFR TTR 

data requirement. HED has reasonable certainty that no harm will result from this exposure 

since there is no toxicity associated with the dermal route of exposure to sulfosulfuron, and 

incidental oral risk estimates are minimal. In this instance, it is unlikely that chemical-specific 

TTR data would be needed to further refine exposure assessments or would add appreciably to 

our general understanding of the availability of turf transferable pesticide residues (see Appendix 

F for further details).

6.1 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 coupled with methods 

employed for residential risk assessments for turf products.
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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.4 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. 

EPA Reg. No. 524-534 is an existing label for use on turf, thus it was evaluated to determine 

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

that would be associated with spray drift. If the maximum application rate on crops, adjusted by 

the amount of drift expected, is less than or equal to existing turf application rates, the existing 

turf assessment is considered protective of spray drift exposure. For sulfosulfuron, the registered 

residential uses on turf result in estimated exposure levels that are greater than the potential 

exposure from spray drift; therefore, no new residential assessment needs to be completed. The 

currently registered maximum single application rate of sulfosulfuron for all registered crops is 

0.09 lb ai/A. The highest degree of spray drift noted for any application method immediately 

adjacent to a treated field (Tier 1 output from the aerial 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 sulfosulfuron is not required because the maximum application rate to a 

crop/target site (i.e., 0.09 lb ai/A) multiplied by the adjustment factor for drift of 0.26 equals 

0.023 lb ai/A, which is less than the maximum direct spray residential turf application rate of 

0.09 lb ai/A for any sulfosulfuron product.

7.0 Aggregate Exposure/Risk Characterization

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

chemical residues, including all anticipated dietary exposures and all other exposures for which 

there is reliable information. Toxicity endpoints for risk assessment through exposure via acute 

and cancer dietary were not identified; therefore, quantitative aggregate risk assessments for 

these scenarios were not required. Additionally, no hazard via the dermal or inhalation route was

identified (for any duration). Chronic dietary exposure (food and water) is expected for the U.S. 

population and all population subgroups and short-term aggregate exposure is expected for 

children resulting from short-term incidental oral exposure (from residential turf) and dietary 

exposure (food and water). Intermediate- and chronic-term aggregate exposure is not expected 

for children resulting from incidental oral exposure based on the use pattern (30-day application 

interval).

 

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

on all labels, precludes direct exposure pathways.
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7.1 Short-term Aggregate Risk

Due to the potential for post-application exposure from lawn uses of sulfosulfuron, short-term 

aggregate risks were assessed. The short-term aggregate risk takes into account the exposure 

from potential residential sources in addition to average dietary residues from food and drinking 

water. The short-term aggregate risk assessment was performed for children only, since nondietary incidental oral exposure is not expected for other population subgroups (youth, adults). 

As can be seen in Table 7.1 below, short-term aggregate risk for children results in a MOE of 

6,300 and is, therefore, not of concern to HED, being greater than the LOC (100).

Table 7.1. Short-Term Aggregate Risk Calculations. 

Population

Oral Exposure for Children Only

NOAEL

(mg/kg/day) LOC1

Max 

Allowable

Exposure2

(mg/kg/day)

Average

Food & 

Water

Exposure

(mg/kg/day)

Residential 

Exposure3

(mg/kg/day)

Aggregate MOE

(food and

residential)4

Children, 1-2 

years old 100 100 1.0 0.015834 0.00014 6300

1

 The LOC is 100, based on the standard 10X inter-species and 10X intra-species UFs totaling 100. 

2 Maximum Allowable Exposure (mg/kg/day) = NOAEL/LOC.

3 Residential Exposure = [Oral Exposure]. Taken from the 2004 HED risk assessment ((DP# D304483, M. ClockRust, et al., 10/07/2004), Table 5, oral exposure.

4 Aggregate MOE = [NOAEL/(Avg. Food & Water Exposure + Residential Exposure)].

7.2 Chronic Aggregate Risk

The chronic aggregate risk assessment considered exposure from food and water (chronic 

residential exposure is not anticipated); therefore, the screening-level chronic dietary exposure 

and risk analysis presented in Section 5.3 represents chronic aggregate risk for sulfosulfuron. As 

can be seen in Table 5.3, the DEEM-FCID chronic exposure estimates were below the LOC 

(100% cPAD) for all populations subgroups, and not of concern to HED.

8.0 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 
Sulfosulfuron (085601) Draft Human Health Risk Assessment DP#: 427399

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groups (CMGs)5and conducting cumulative risk assessments (CRA)6. The Agency has utilized 

this framework to evaluate the SUs of which sulfosulfuron is a member (D428798). 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.

The Agency is required to consider the cumulative risks of chemicals sharing a common 

mechanism of toxicity. The Agency has not determined that sulfosulfuron shares a common 

mechanism of toxicity with other chemical substances; therefore, a cumulative risk assessment to 

support Registration Review is not required.

9.0 Occupational Exposure/Risk Characterization

Use of sulfosulfuron for weed control in agricultural, residential, commercial/industrial, and 

public areas will result in occupational handler and post-application exposures. However, there 

are no occupational handler or post-application risks of concern associated with agricultural and 

non-agricultural uses of sulfosulfuron based on the low toxicity. The label-specified PPE (i.e., 

long-sleeved shirt, long pants and shoes with socks) is expected to provide adequate protection 

for handlers. Post-application exposures also are not of concern; workers may re-enter treated 

areas after the Restricted Entry Interval (REI) of 12 hours based on the acute toxicity of 

sulfosulfuron. 

10.0 Public Health and Pesticide Epidemiology Data

An updated HED incident report was conducted in 2011 (D387221). Based on the low 

frequency and severity of incident cases, there does not appear to be a concern at this time that 

would warrant further investigation. The Agency will continue to monitor the incident 

information.

11.0 Literature References

A literature search was conducted for sulfosulfuron. The TOXLINE (National Library of 

Medicine) database search did not identify any new toxicological information not already 

considered.

 

5 Guidance For Identifying Pesticide Chemicals and Other Substances that have a Common Mechanism of Toxicity

(USEPA, 1999)

6 Guidance on Cumulative Risk Assessment of Pesticide Chemicals That Have a Common Mechanism of Toxicity

(USEPA, 2002)
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12.0 References

Author Barcode/

TXR#

Date Title

Craig, E. TXR 

0052986

5/7/2015 Sulfonylurea Pesticides: Summary of Hazard.and Science 

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

Recommendations on Data Requirement for Subchronic 

Inhalation Studies.

Cropp-Kohlligian, B. D427730 9/16/2015 Sulfosulfuron. Re-evaluation of Enforcement Methods 

and Livestock Tolerances.

D’Agostino, J. D428798 9/9/2015 Sulfonylureas: Screening Analysis of Toxicological 

Profiles to Consider Whether a Candidate Common 

Mechanism Group Can Be Established.

Daiss, B. D385545 6/7/2011 Sulfosulfuron: Human Health Risk Scoping Document in 

Support of Registration Review. 

Daiss, B. D394271 10/18/2011 Sulfosulfuron: Response to Comments on the Human 

Health Risk Scoping Document in Support of Registration 

Review.

Khasawinah, A. TXR 

0056762

8/16/13 Sulfosulfuron: Response to GDCI-085601-1061 regarding 

Immunotoxicity study waiver request

Knizner, S. None 5/27/2009 HED Interim Guidance on Tolerance Expressions

Levy, S., et al. D349702 2/28/2008 AMENDMENT TO: Sulfosulfuron. PP#6F7031. Human 

Health Risk Assessment for Proposed Uses of the 

Herbicide Sulfosulfuron on Grass Forage, Fodder and Hay 

(Crop Group 17), Forestry Conifer Release and Non-crop 

Areas. DP#: 327363.

Oo, K. D387221 3/1/2011 Sulfosulfuron: Review of Human Incidents.

Orrick, G. D427429 8/12/2015 Drinking Water Exposure Assessment for the Registration 

Review of 22 Sulfonylurea Herbicides.

Rury, K. TXR 

0056723

8/6/13 Sulfonylureas: Summary of Hazard and Science Policy 

Council (HASPOC) Meeting on July 18,2013: 

Recommendations on Data Requirement for

Immunotoxicity Studies for Sulfonylurea Pesticides.
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Appendix A. Toxicology Profile and Executive Summaries

A.1 Toxicology Data Requirements

The toxicology requirements (40 CFR 158.340) for the sulfosulfuron food use are shown below. Use of the new 

guideline numbers does not imply that the new (1998) guideline protocols were used.

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 (non-rodent)

870.3200 21-Day Dermal

870.3250 90-Day Dermal

870.3465 90-Day Inhalation

yes

yes

yes

no

CR

yes

yes

yes

-

waived1

870.3700a Developmental Toxicity (rodent)

870.3700b Developmental Toxicity (non-rodent)

870.3800 Reproduction

yes

yes

yes

yes

yes

yes

870.4100a Chronic Toxicity (rodent)

870.4100b Chronic Toxicity (non-rodent)

870.4200a Oncogenicity (rat)

870.4200b Oncogenicity (mouse)

870.4300 Chronic/Oncogenicity

yes

yes

-

yes

yes

yes

yes

-

yes

yes

870.5100 Mutagenicity-Gene Mutation - bacterial

870.5300 Mutagenicity-Gene Mutation - mammalian

870.5xxx Mutagenicity-Structural Chromosomal Aberrations

870.5xxx Mutagenicity—Other Genotoxic Effects

yes

yes

yes

yes

yes

yes

yes

yes

870.6100a Acute Delayed Neurotox. (hen)

870.6100b 90-Day Neurotoxicity (hen)

870.6200a Acute Neurotox. Screening Battery (rat)

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

870.6300 Develop. Neuro

no

no

yes

no

no

-

-

yes

yes

-

870.7485 General Metabolism

870.7600 Dermal Penetration

870.7800 Immunotoxicity

yes

no

yes

yes

-

waived2

Special Studies for Ocular Effects

Acute Oral (rat)

Subchronic Oral (rat)

Six-month Oral (dog)

no

no

no

-

-

-

1 The requirement for this study has been waived (TXR 0052986) 

2 The requirement for this study has been waived (TXR 0056723 and TXR 0056762)
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A.2 Toxicity Profiles

Table A.2.1. Acute Toxicity Profile – Sulfosulfuron.

Guideline 

No. Study Type MRID(s) Results Toxicity Category

870.1100 Acute oral rat 44295737 (1993) LD50 >5,000 mg/kg IV

870.1200 Acute dermal rat 44295739 (1993) LD50 >5,000 mg/kg III

870.1300 Acute inhalation rat 44295745 (1994) No mortality at 3.0 mg/L IV

870.2400 Acute eye irritation rabbit 44295741 (1993) Moderately irritating III

870.2500 Acute dermal irritation rabbit 44295743 (1993) Not an irritant IV

870.2600 Skin sensitization guinea pig 44295747 (1993) Not a sensitizer N/A

Table A.2.2. Subchronic, Chronic and Other Toxicity Profile – Sulfosulfuron.

Guideline 

No. 

Study Type MRID No. (year)/ 

Classification /Doses

Results

870.3100 90-Day oral 

toxicity rat (with 

1-generation 

reproduction 

range-finding 

study)

44295750 (1995)

Acceptable/guideline

0, 20, 200, 2000, 6000 or 

20000 ppm

M: 0, 1.2, 12.1, 123.2, 

370.3 or 1277.5 mg/kg/d

F: 0, 1.5, 14.6, 144.3, 

447.5 or 1489.1 mg/kg/d

NOAEL = 370.3 mg/kg/day

LOAEL = 1277.5 mg/kg/day based on 

decreased body weight/weight gain in males, 

possible decreased weight gain in pregnant 

females during gestation days 14-21, and 

possible renal lesions related to formation of 

calculi.

870.3150 90-Day oral 

toxicity dog

44295751 (1996)

Acceptable/guideline

0, 30, 100, 300 or 1000 

mg/kg/d

NOAEL = 100 mg/kg/day

LOAEL = 300 mg/kg/day based on lesions in 

the urinary bladder in females occurring 

subsequent to urinary formation/urolithiasis and 

on abnormal urinary crystals in males and 

females.

870.3200 21/28-Day 

dermal toxicity 

rat

44295752 (1994)

Acceptable/guideline

0, 100, 300 or 1000 

mg/kg/d; 5d/wk for 4 wks

NOAEL > 1000 mg/kg/day

LOAEL was not determined.

870.3700a Prenatal 

developmental in 

rat

44295756 (1997)

Acceptable/guideline

0, 100, 300 or 1000 

mg/kg/d; days 6-15.

Maternal NOAEL > 1000 mg/kg/day

LOAEL was not determined.

Developmental NOAEL > 1000 mg/kg/day

LOAEL was not determined.

870.3700b Prenatal 

developmental in 

rabbit

44295757 (1994)

Acceptable/guideline

0, 50, 250 or 1000 

mg/kg/d; days 7-19.

Maternal NOAEL > 1000 mg/kg/day

LOAEL was not determined.

Developmental NOAEL > 1000 mg/kg/day

LOAEL was not determined.

870.3800 Reproduction 

and fertility 

effects

rat

44295758 (1996)

Acceptable/guideline

0, 50, 500, 5000 or 20,000 

ppm

M (P): 0, 31.6, 312.1 and 

1318.2 mg/kg/d

F (P): 0, 3.6, 36.2, 363.2 

or 1454.1 mg/kg/d

M (F1a): 0, 3.1, 31.1, 

315.8 and 1378.8 mg/kg/d

F (F1a): 0, 3.7, 37.7, 

377.8 and 1598.o mg/kg/d

Parental/Systemic NOAEL = 312.8 

mg/kg/day

LOAEL = 1312.8 mg/kg/day based on 

decreased parental body weight gain during 

premating, gestation and lactation.

Reproductive NOAEL ≥1312.8 mg/kg/day

LOAEL ≥1312.8 mg/kg/day

Offspring NOAEL = 312.1 mg/kg/day

LOAEL = 1312.8 mg/kg/day based on 

decreased body weight gain in post-weaning 

adolescent rats.
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Table A.2.2. Subchronic, Chronic and Other Toxicity Profile – Sulfosulfuron.

Guideline 

No. 

Study Type MRID No. (year)/ 

Classification /Doses

Results

870.4100b Chronic toxicity 

dog

44295754 (1997)

Acceptable/guideline

0, 5, 20, 100 or 500 

mg/kg/d

NOAEL = 100 mg/kg/day

LOAEL = 500 mg/kg/day based on the 

presence of abnormal urinary crystals and 

bladder pathology secondary to formation of 

urinary tract calculi in males.

870.4200 Carcinogenicity

rat

44295759 (1997)

Acceptable/guideline

0, 50, 500, 5000 or 20000 

ppm 

M: 0, 2.4, 24.4, 244.2 or 

1178.3 mg/kg/d (20000 

ppm male group 

terminated at day 259 due 

to excessive mortality)

F: 0, 3.1, 30.4, 314.1 or 

1296.5 mg/kg/d

NOAEL = 24.4 mg/kg/day

LOAEL = 244.2 mg/kg/day based on increased 

incidence of urinary tract gross/microscopic 

lesions, mineralization in several tissues 

(males), abnormal urine crystals and possible 

albumin (males, termination).

At the high dose, urinary bladder 

transitional cell carcinoma and papilloma 

were observed in females (1/50 each vs. 

0/controls) and were considered treatmentrelated.

870.4300 Carcinogenicity

mouse

44295755 (1997)

Acceptable/guideline

0, 30, 700, 3000 or 7000 

ppm

M: 0, 4.0, 93.4, 393.6 or 

943.5 mg/kg/d

F: 0, 6.5, 153.0, 634.9 or 

1388.2 mg/kg/d

NOAEL (M) = 93.4 mg/kg/day

LOAEL (M) = 393.6 mg/kg/day based on 

gross and microscopic effects related to urinary 

calculus formation in the urinary bladder of 

males. 

The incidence of benign mesenchymal 

tumors of the urinary bladder was increased 

in males in the high dose (5/60) compared to 

controls (0/60).

Gene 

Mutation

870.5100

Salmonella 

typhimurium; E. 

coli)/ mammalian 

activation gene 

mutation assay

44295760 (1995)

Acceptable/guideline

312, 624, 1250, 2500 or 

5000 μg/mL

Negative for inducing reverse gene mutations 

with Salmonella typhimurium strains TA1535, 

TA1537, TA98, TA 100 or TA1O2 exposed in 

either the presence or absence of mammalian 

metabolic activation at doses up to 5,000 

μg/plate. Cytotoxicity observed at ≥ 1,500 

μg/plate.

Cytogenetics 

870.5300

In Vitro

mammalian cells 

in culture gene 

mutation assay in 

Chinese hamster 

ovary cells

44295761 (1996)

Acceptable/guideline

624-5000 μg/mL

Negative for inducing forward gene mutations 

at the HGPRT locus in Chinese hamster ovary 

(CHO) cells exposed in either the presence or 

absence of S9 activation up to 5,000 μg/mL. 

Doses caused cytotoxicity at 5,000 μg/mL in 

the absence of S9 but not in the presence of S9; 

however, MON 37500 was insoluble at or 

above 2,500 μg/mL.

Other Effects 

870.5375 

In vitro

mammalian 

chromosome 

aberration

44280201 (1996)

Acceptable/guideline

1000, 1250, 2000, 2500, 

3000 or 5000 μg/mL

Positive under non-activated conditions; 

however, precipitation occurred

Negative under activated conditions.

Other Effects 

870.5375 

In vitro

mammalian 

chromosome 

aberration

44295762 (1996)

Acceptable/guideline

100, 250, 500, 750 or 

1000 μg/mL

Negative for inducing structural chromosome 

damage in Cultured Human Lymphocytes 

exposed at levels up to 1,000 μg/mL in either 

the presence or absence of S9 and harvested 

either at 18 or 42 hrs post-treatment. 

Cytotoxicity (decreased mitotic indices) were 

observed at 1,000 μg/mL with and without S9. 

MON 37500 was precipitated at 1,000 μg/mL.
Sulfosulfuron (085601) Draft Human Health Risk Assessment DP#: 427399

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Table A.2.2. Subchronic, Chronic and Other Toxicity Profile – Sulfosulfuron.

Guideline 

No. 

Study Type MRID No. (year)/ 

Classification /Doses

Results

Other Effects 

870.5395 

In vitro

mammalian 

micronucleus 

assay

44295763, 4429564 

(1995)

Acceptable/guideline

0, 1250, 2500 or 5000 

mg/mL

Negative for inducing micronuclei in 

polychromatic erythrocytes from male or 

female CD-1 mice at dose levels up to 5,000 

mg/kg. Although no indication of cytotoxicity 

was observed, a pharmacokinetic study 

demonstrated that MON 37500 reached the 

bone marrow in male CD-1 mice at 2 and 8 hrs 

following an oral gavage dose of 2.000 mg/kg.

870.6200a Acute 

neurotoxicity 

screening battery

44295749 (1997)

Acceptable/guideline

0, 125, 500 or 2000 

mg/kg/d

NOAEL > 2000 mg/kg/day

LOAEL > 2000 mg/kg/day.

870.6200b Subchronic 

neurotoxicity 

screening battery

44295753 (1997)

Acceptable/guideline

0, 200, 2000 or 20000 

ppm

M: 0, 12, 122 or 1211 

mg/kg/d

F: 0, 14, 141 or 1467 

mg/kg/d

NOAEL = 1211 mg/kg/day

LOAEL > 1211 mg/kg/day.

870.7485 Metabolism and 

pharmacokinetics

rat

44295765 (1996)

Acceptable/guideline

Single oral dose of 10 or 

1000 mg/kg

Repeated oral dose of 10 

mg/kg (14 doses, followed 

by 1 unlabeled dose)

Single iv dose of 10 

mg/kg

90% of radioactivity excreted over 72 hrs. 

Between 77-87% excreted in the urine, 5-13% 

in the feces at low dose. At high dose, 55-63% 

excreted in the feces and 32-33% excreted in 

the urine. Biliary excretion accounted for 5-9% 

of an iv dose. Urinary excretion followed a 

biexponential pattern with half-life of 2.2-5.8 

hrs initial phase and 21.4-56.7 hrs terminal 

phase. Minimal radioactivity was retained in 

the tissues (>0.07%). Expiration of 14CO2 was 

insignificant. Parent was excreted mostly 

unchanged. Metabolism occurred via ring 

hydroxylation or demethylation. Major 

metabolites were desmethyl MON 37500 

(3.5%), 5-hydroxy MON 37500 (1.9%), and 

sulfonamide (2.9%). Other minor metabolites 

were also present.
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Appendix B. Dietary Exposure/Risk Modeling Input and Output

Filename: Sulfosulfuron\085601\Chronic.R08

Chemical: Sulfosulfuron

RfD(Chronic): .24 mg/kg bw/day NOEL(Chronic): 0 mg/kg bw/day

RfD(Acute): 0 mg/kg bw/day NOEL(Acute): 0 mg/kg bw/day

Date created/last modified: 02-05-2015/13:58:05 Program ver. 3.16, 03-08-d

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

 EPA Crop Def Res Adj.Factors Comment

 Code Grp Commodity Name (ppm) #1 #2 

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

1500381000 15 Triticale, flour 0.020000 1.000 1.000 

1500381001 15 Triticale, flour-babyfood 0.020000 1.000 1.000 

1500401000 15 Wheat, grain 0.020000 1.000 1.000 

1500401001 15 Wheat, grain-babyfood 0.020000 1.000 1.000 

1500402000 15 Wheat, flour 0.020000 1.000 1.000 

1500402001 15 Wheat, flour-babyfood 0.020000 1.000 1.000 

1500403000 15 Wheat, germ 0.020000 1.000 1.000 

1500404000 15 Wheat, bran 0.020000 1.000 1.000 

3100044000 31 Beef, meat 0.010000 1.000 1.000 

3100044001 31 Beef, meat-babyfood 0.010000 1.000 1.000 

3100045000 31 Beef, meat, dried 0.010000 1.920 1.000 

3100046000 31 Beef, meat byproducts 0.300000 1.000 1.000 

3100046001 31 Beef, meat byproducts-babyfood 0.300000 1.000 1.000 

3100047000 31 Beef, fat 0.020000 1.000 1.000 

3100047001 31 Beef, fat-babyfood 0.020000 1.000 1.000 

3100048000 31 Beef, kidney 0.300000 1.000 1.000 

3100049000 31 Beef, liver 0.300000 1.000 1.000 

3100049001 31 Beef, liver-babyfood 0.300000 1.000 1.000 

3200169000 32 Goat, meat 0.010000 1.000 1.000 

3200170000 32 Goat, meat byproducts 0.300000 1.000 1.000 

3200171000 32 Goat, fat 0.020000 1.000 1.000 

3200172000 32 Goat, kidney 0.300000 1.000 1.000 

3200173000 32 Goat, liver 0.300000 1.000 1.000 

3300189000 33 Horse, meat 0.010000 1.000 1.000 

3400290000 34 Pork, meat 0.005000 1.000 1.000 

3400290001 34 Pork, meat-babyfood 0.005000 1.000 1.000 

3400291000 34 Pork, skin 0.005000 1.000 1.000 

3400292000 34 Pork, meat byproducts 0.050000 1.000 1.000 

3400292001 34 Pork, meat byproducts-babyfood 0.050000 1.000 1.000 

3400293000 34 Pork, fat 0.005000 1.000 1.000 

3400293001 34 Pork, fat-babyfood 0.005000 1.000 1.000 

3400294000 34 Pork, kidney 0.050000 1.000 1.000 

3400295000 34 Pork, liver 0.050000 1.000 1.000 

3500339000 35 Sheep, meat 0.010000 1.000 1.000 

3500339001 35 Sheep, meat-babyfood 0.010000 1.000 1.000 

3500340000 35 Sheep, meat byproducts 0.300000 1.000 1.000 

3500341000 35 Sheep, fat 0.020000 1.000 1.000 

3500341001 35 Sheep, fat-babyfood 0.020000 1.000 1.000 

3500342000 35 Sheep, kidney 0.300000 1.000 1.000 

3500343000 35 Sheep, liver 0.300000 1.000 1.000 

3600222000 36 Milk, fat 0.020000 1.000 1.000 

3600222001 36 Milk, fat-baby food/infant formu 0.020000 1.000 1.000 

3600223000 36 Milk, nonfat solids 0.020000 1.000 1.000 

3600223001 36 Milk, nonfat solids-baby food/in 0.020000 1.000 1.000 

3600224000 36 Milk, water 0.020000 1.000 1.000 

3600224001 36 Milk, water-babyfood/infant form 0.020000 1.000 1.000 

3600225001 36 Milk, sugar (lactose)-baby food/ 0.020000 1.000 1.000 

3800221000 38 Meat, game 0.010000 1.000 1.000 

3900312000 39 Rabbit, meat 0.010000 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 
Sulfosulfuron (085601) Draft Human Health Risk Assessment DP#: 427399

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US EPA Ver. 3.16, 03-08-d

DEEM-FCID Chronic analysis for SULFOSULFURON NHANES 2003-2008 2-day

Residue file name: Sulfosulfuron\085601\Chronic.R08

 Adjustment factor #2 used.

Analysis Date 04-13-2015/14:10:52 Residue file dated: 04-13-2015/13:21:15

Reference dose (RfD, Chronic) = .24 mg/kg bw/day

===============================================================================

 Total exposure by population subgroup

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

 Total Exposure

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

 Population mg/kg Percent of 

 Subgroup body wt/day Rfd 

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

Total US Population 0.010480 4.4%

Hispanic 0.010052 4.2%

Non-Hisp-White 0.010772 4.5%

Non-Hisp-Black 0.008649 3.6%

Non-Hisp-Other 0.012056 5.0%

Nursing Infants 0.009405 3.9%

Non-Nursing Infants 0.034596 14.4%

Female 13+ PREG 0.009841 4.1%

Children 1-6 0.013898 5.8%

Children 7-12 0.008901 3.7%

Male 13-19 0.007261 3.0%

Female 13-19/NP 0.008074 3.4%

Male 20+ 0.009707 4.0%

Female 20+/NP 0.010919 4.5%

Seniors 55+ 0.010061 4.2%

All Infants 0.026819 11.2%

Female 13-50 0.010362 4.3%

Children 1-2 0.015834 6.6%

Children 3-5 0.013104 5.5%

Children 6-12 0.009366 3.9%

Youth 13-19 0.007671 3.2%

Adults 20-49 0.010387 4.3%

Adults 50-99 0.010260 4.3%

Female 13-49 0.010351 4.3%

-------------------------------------------------------------------------------
Sulfosulfuron (085601) Draft Human Health Risk Assessment DP#: 427399

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Appendix C. Nomenclature and Physical/Chemical Properties

Table C.1. Sulfosulfuron Nomenclature

Chemical structure

Common name Sulfosulfuron

Company experimental name MON 37500; TKM-19

IUPAC name 1-(4,6-dimethoxypyrimidin-2-yl)-3-(2-ethylsulfonylimidazo[1,2-a]pyridin-3-

ylsulfonyl)urea

CAS name N-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]-2-(ethylsulfonyl)imidazo[1,2-

a]pyridine-3-sulfonamide

CAS registry number 141776-32-1

Chemical structure of ethyl 

sulfone chemophore

2-(ethylsulfonyl)-imidazo [1,2-a]pyridine

Table C.2. Physicochemical Properties of Sulfosulfuron.

Parameter Value Reference

Melting range 180.9-184.1oC MRID 44295704; Memo, S. 

Chun, 28-SEP-1998; DP#: 

237683

pH 4.76

Density 1.55 g/mL at 20oC

Water solubility ppm at 20oC 

pH 5 17.60 ± 2.71 

pH 7 1626.8 ± 39.8

pH 9 482.44 ± 8.35

Solvent solubility ppm at 20oC

Heptane <1 

Xylene 160

Methanol 330

Ethyl acetate 1010

Dichloroethane 4350

Vapor pressure 2.29 x 10-10 mm Hg at 20oC

6.61 x 10-10 mm Hg at 25oC

Dissociation constant, pKa pKa = 3.51 at 20oC

Octanol/water partition coefficient, 

Log (KOW)

pH 5: KOW = 6.38; pKOW = 0.81

pH 7: KOW = 0.14; pKOW = -1.01

pH 9: KOW = 0.036; pKOW = -1.37

UV/visible absorption spectrum UVMAX = 208 nm

ε = 187,150 L/mol cm

(pH >10.0, 1.06% by weight in water, 

26oC)

N

N SO2C2H5

N

N

OCH3

N OCH3

H

N

H

O

SO2

N

N SO2C2H5

H
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Appendix D. 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://www.epa.gov/pesticides/science/handler-exposure-data.html and 

http://www.epa.gov/pesticides/science/post-app-exposure-data.html.

Appendix E. Submittal of Analytical Reference Standards (860.1650)

An analytical reference standard for sulfosulfuron is currently available in EPA’s National 

Pesticide Standards Repository (NPSR) and has an expiration date of 4/30/2016; however, an 

analytical reference standard for the ethyl sulfone chemophore metabolite is not currently 

available (email communication between T. Cole and B. Cropp-Kohlligian, 5/8/2015) and must 

be submitted. The registrant is required to maintain reasonable amounts of the reference 

standards for sulfosulfuron and its ethyl sulfone chemophore metabolite in the NPSR as long as 

tolerances remain published in 40 CFR §180.552. When necessary, new reference standards, or 

updated certificates of analysis (COAs), should be sent to the Analytical Chemistry Branch 

(ACB), which is located at Fort Meade, MD. It should be sent to the attention of either Theresa 

Cole or Thuy Nguyen at the address listed below, along with a letter of transmittal. Please note 

that the full 9-digit ZIP Code is required, or the mail will be returned to the registrant.

 USEPA

 National Pesticide Standards Repository

 Analytical Chemistry Branch/BEAD/OPP

 701 Mapes Road

 Fort George G. Meade, MD 20755-5350

The letter of transmittal should include the assay of the standard, name of the analytical method 

used, a statement of principal impurities, purification procedures employed, storage 

requirements, and special precautions for safe handling. Replacement of standards, or updated 

COAs, may be required periodically if supplies are exhausted, if the standards expire, or if 

decomposition occurs during storage. Material Safety Data Sheets (MSDSs) must accompany all 

analytical standards as specified by the Occupational Safety and Health Administration (OSHA) 

in 29CFR §1910.1200.
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Appendix F. TTR Data Waiver Criteria

Turf Transferrable Residue (TTR): In accordance with 40CFR158, TTR data are required for all 

occupational (e.g., sod farms, golf courses, parks, and recreational areas) or residential turf uses 

that could result in post-application exposure to turf. In the absence of chemical-specific TTR

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

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

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

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

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

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

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

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

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

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

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

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

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

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

EPA is using the default value of 0.2% for the granular product. Although there may be a small 

degree of uncertainty in the use of the default TTR value for sulfosulfuron (i.e., there is a small 

chance that the FAR value may exceed the applicable default value), it is likely that the healthprotective aspects of EPA’s residential post-application turf assessment methodology will more 

than compensate for this potential uncertainty (i.e., the methodology is likely to overestimate 

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

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

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

assessed exposure duration (i.e., EPA assumes that no dissipation or degradation occurs, it 

doesn’t rain, the grass is not mowed, etc); individuals perform the same post-application 

activities performed in the turf transfer coefficient study day after day (e.g., tumbling, playing on 

turf with toys, etc.); and individuals engage in these post-application activities for a high-end 

amount of time every day that is represented by data reflecting time children spend outdoors and 

not specifically engaged in activities on turf, when in actuality children do not spend all of their 

outdoor time on turf and high-end levels of activity will not occur every day. 

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

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

exposure is not being underestimated.

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

TTR values for sulfosulfuron is minimal in comparison to the level of concern (i.e., the 

calculated lowest MOE is greater than 10 times higher than the level of concern, MOE = 740,000

compared to the LOC of 100); EPA is waiving the 40CFR TTR data requirement. In this 

instance, it is unlikely that chemical-specific TTR data would be needed to further refine 

exposure assessments or would add appreciably to our general understanding of the availability 

of turf transferable pesticide residues.