Halosulfuron-Methyl Human Health Risk Assessment DP No. D42 I 819 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

ME MORANDUM 

DATE: June 10, 2015 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

SUBJECT: Halosulfuron-Methyl. Human Health Risk Assessment for a Proposed Use on 

Pome Fruit Crop Group I 1-1 0 and Small Fruit Vine Climbing Subgroup, Except 

Fuzzy Kiwifruit, Subgroup I 3-07F. 

PC Code: 128721 

Decision No.: 493338 

Petitio n No.: 4E8297 

DP Ba r code: 0421819 

Registration Nos.: 81880-18, 81880-2 

Regulatory Action: Section 3 Registration 

Ris k Assessment T ype: Single Chemical Aggregate Case No.: NA 

TXR No.: NA CAS No.: 100784-20-1 

MRID No.: NA 40 CFR: § 180.4 79 

FROM: 

THROUGH: 

TO: 

Kristin 

Whang 

Rur

Phang

y, MPH; 

, Senjor 

Biolo

Tox

g

ico

ist 

log

\6ist ~ t 

Risk Assessment Branch 3 

/ 

Risk 

Wi lliam 

Assessme

T. Drew, 

nt Branch 

Chemis

2 

t ~ 

Health Effects Division (7509P) 

Christine Olinger, Branch Ch p~/( '/} . . 

Risk Assessment Branch 3 ?.~ / {___:..-

Health Effects Division (7509P 

Sidney Jackson and Barbara Madden 

Minor Use & Emergency Response Branch 

Registration Division (7505P) 

The Registration Division (RD) requested the Hea lth Effects Division (HED) evaluate the 

proposed new uses of halosulfw·on-methyl requested by the Interregional Research Project 4 (IR4). Since the last risk assessment, the toxi city endpoints and points of departure (PODs) have 

been re-evaluated; therefore the residential scenarios for inclusion in the aggregate risk 

assessment have changed. The dietary exposure assessment has been updated to reflect the 

proposed new uses of halosulfuron-methyl, and the aggregate risk assessment has been updated 

to include the proposed new uses and the updated residential scenarios. 

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Halosulfuron-Methyl Human Health Risk Assessment DP No. 0421819 

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

2.0 HED Recommendations ................................................................... ... ....... ....................... 6 

2.1 Tolerance Considerations ....................................... ... .... .... ....... ............................ ....... .. 6 

2.1.1 Enforcement Analytical Method/Multiresidue Methods ........................... .... ... .... .. 6 

2.1.2 Recommended Tolerances ..................................... ........... .... ... ............................ ...... 7 

2.1.3 International Harmonization ..................... .... .... .... .... .... ... .... ... ..................... ... .... ... ... 8 

2.2 Label Recommendations ... .... .... .... .... ........................................... ....... ........................... 8 

2.2.1 Recommendations from Residue Reviews ........ .... .... ... .... .... ... .... ................. .......... ... 8 

3.0 Introduction .. .... .......... .... ........... ........ .... ......................... .... ... .... ... .... ... .................. ... .... ... ... 8 

3.1 Chemical Identity .......... .... ........ .... .... .... .... ..... .......................... ....... ... .... ... .... ................. 8 

3.2 Physical/Chemical Characteristics ...... ............................... .... ... .... ... ..................... ... .... 9 

3.3 Pesticide Use Pattern ......................................... ........... ................................ ....... ... ........ 9 

3.4 Anticipated Exposure Pathways ............. .... .... .... ............................. ....... ... .... ... .......... 10 

3.5 Consideration of Environmental Justice .............................. ....... ... .... ..................... ... 10 

4.0 Hazard Characterization and Dose-Response Assessment ... .... ........................ .... ... .... 11 

4.1 Toxicology Studies Available for Analysis ... .... ................................. ... .... ... .... ... ........ 11 

4.2 Absorption, Distribution, Metabolism and Elimination .... .... ... ... ..................... .... ... . 12 

4.2.1 Dermal absorption .. .... .... .... ............ .... .... ........ .... .... ... ......................... ........... ... ... ..... 12 

4.3 Summary of Toxicological Effects ... .... .......................................... .... ... ...................... 12 

4.4 Safety Factor for Infants and Children (FQPA Safety Factor) .. .................... .... ... .. 13 

4.4.1 Completeness of the Toxicology Database ... .... .... .... .... ... ... ......................... ... ....... .. 13 

4.4.2 Evidence of Neurotoxicity .... .... .... .... .... ..... .... .................................... .... ... ....... ... ... ... 13 

4.4.3 Evidence of Sensitivity/Susceptibility in the Developing or Young Animal.. ...... 13 

4.4.4 Residual Uncertainty in the Exposure Database ...... ................................... ....... ... 13 

4.5 Toxicity Endpoint and Point of Departure (POD) Selections ...... ....... .... ... ........... ... 14 

5.0 Dietary Exposure and Risk Assessment .................... .... ... .... ... .... ... .... ... .... ... .................. 15 

5.1 Residues of Concern Summary and Rationale ..... ... .... .... ... .... ............................... ... . 15 

5.2 Food Residue Profile .. .... .... ........ ........ ....................................... ... .... ... .... ... ........... ....... 16 

5.3 Water Residue Profile ............... ............. .... ............ .... .... ... .... ....... ................................ 16 

5.4 Dietary Risk Assessment ....... .... ......... ............ .... .... .... ....... .... ............................... ....... . 17 

5.4.1 Description of Residue Data Used in Dietary Assessment .............. ... .... ... ....... ... .. 17 

5.4.2 Percent Crop Treated Used in Dietary Assessment .......... ... .... ... ....... ... .... ... ......... 17 

5.4.3 Acute Dietary Risk Assessment ................ .... .... ........ ............................................... 17 

5.4.4 Chronic Dietary Risk Assessment.. ......................... ........... ....... .... ... .... ... ... .... ... ...... 18 

5.4.5 Cancer Dietary Risk Assessment.. ... .... .... .... .... .... .... ....... ................................... ... ... 18 

5.4.6 Summary Table ............................................................ .... ... .... ....... .... ... ... .... .... ... ...... 18 

6.0 Residential (Non-Occupational) Exposure/Risk Characterization ............................. 18 

6.1 Residential Risk Estimates for Use in Aggregate Assessment ...... .... .......... .... .......... 19 

6.2 Residential Bystander Post-application Inhalation Exposure ................................. 19 

6.3 Spray Drift ................................................................................................................ ... . 19 

7.0 Aggregate Exposure/Risk Characterization .... .... .... .... .... .... ... ....... ....... .... ... .......... ........ 20 

7.1 Acute Aggregate Risk ............ .... .... .... ......... ... ..... ........... .... .... ... .... ................................ 20 

7.2 Short-Term Aggregate Risk ...................................................................... ... .... ... ... ... .. 20 

7.3 Intermediate-Term Aggregate Risk .... ..... .... .... ............... ....... .............. ...................... 21 

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Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

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7.4 Chronic Aggregate Risk .............................................................................................. 21

7.5 Cancer Aggregate Risk ................................................................................................ 21

8.0 Cumulative Exposure/Risk Characterization ............................................................... 21

9.0 Occupational Exposure/Risk Characterization ............................................................ 22

9.1 Short-/Intermediate-Term Handler Risk................................................................... 22

9.2 Short-/Intermediate-Term Post-Application Risk .................................................... 25

9.2.1 Dermal Post-Application Risk................................................................................. 25

9.2.2 Inhalation Post-Application Risk............................................................................ 25

10.0 References......................................................................................................................... 26

Appendix A. Toxicology Profile and Executive Summaries .................................................. 27

A.1 Toxicology Data Requirements................................................................................... 27

A.2 Toxicity Profiles............................................................................................................ 28

Appendix B: Sulfonylureas: comparative physical chemical properties and percent dermal 

absorption.................................................................................................................................... 32

Appendix C. Physical/Chemical Properties............................................................................. 36

Appendix D. International Residue Limit ............................................................................... 37

Appendix E. Review of Human Research................................................................................ 38

Appendix F. TTR and DFR Waiver Summary ....................................................................... 39
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

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1.0 Executive Summary

Halosulfuron-methyl is a sulfonylurea herbicide used for the pre- and post-emergence control of 

annual broadleaf weeds and nutsedges in selected crops, as well as in residential turf grass and 

ornamentals. Halosulfuron-methyl has been proposed for use on pome fruit crop group 11-10 

and small fruit vine climbing subgroup, except fuzzy kiwifruit, subgroup 13-07F. 

Proposed Use Profile 

The proposed use sites will be added to two formulated end-use product labels (Sandea®

Herbicide, EPA Reg. No. 81880-18 and GWN-3061® Herbicide, EPA Reg. No. 81880-2). Both 

end-use products are dry flowable (DF) formulations containing 75% halosulfuron-methyl by 

weight. The proposed maximum single application rates are as follows: 2 fl oz/A (0.094 lb ai/A) 

for pome fruit crop group 11-10, and 1 fl oz/A (0.047 lb ai/A) for small fruit vine climbing 

subgroup, except fuzzy kiwifruit, subgroup 13-07F. Both products may be applied via 

groundboom, aerial, and handheld equipment; however, application with airblast and 

chemigation equipment is prohibited. Both labels list a restricted entry interval (REI) of 12 

hours and require occupational handlers to wear long sleeves, long pants, shoes, and socks. 

Exposure Profile 

Exposure to halosulfuron-methyl can occur from dietary (food and drinking water), residential, 

and occupational exposure sources. Based on all of the proposed application rates and label 

information, only short- and intermediate-term dermal and inhalation exposures are expected for 

occupational handlers and post-application workers. Based on the existing residential uses of 

halosulfuron-methyl on turf and ornamentals, only short-term dermal and inhalation exposures 

are expected for residential handlers. Short-term residential post-application exposure is 

expected for adults and children. For the proposed uses of halosulfuron-methyl, there is also 

potential for acute and chronic exposure through food and drinking water. 

Toxicity/Hazard Characterization 

With repeated dosing, the available data did not demonstrate a consistent target organ or tissue in 

any of the test animals; however, reduced body weights were seen in rats and dogs. Although 

there is qualitative susceptibility seen in the prenatal developmental toxicity study in rats and in 

rabbits, concern is low because a clear No Observed Adverse Effect Level (NOAEL) for these 

effects was established in each of the studies. Halosulfuron-methyl did not produce any effects 

on reproductive parameters in the two-generation reproduction study in rats. No neurotoxic 

effects were observed in the acute or subchronic neurotoxicity studies up to 2000 mg/kg or 760 

mg/kg/day, respectively. An endpoint attributable to a single dose appropriate for the general US 

population was not found in the halosulfuron-methyl toxicity database; however, an endpoint 

attributable to a single dose that is appropriate for dietary risk assessment for females 13-14 

years old was selected. The subchronic dermal study in rats has been reevaluated; no adverse 

effects were seen at doses up to the limit dose (1000 mg/kg/day) and no dermal hazard was 

identified throughout the halosulfuron-methyl toxicity database; therefore, a dermal point of 

departure (POD) was not selected. The incidental oral, and acute (females 13-49 years old only) 

and chronic dietary points of departure (PODs) remain unchanged since the previous risk 

assessment. The acute dietary (females 13-49) POD is based on increased number of resorptions 

(total and per dam) and increased post-implantation loss seen in the rabbit developmental 
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

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toxicity study at the Lowest Observed Adverse Effect Level (LOAEL) of 150 mg/kg/day. The 

short-term incidental oral and inhalation POD is based on decreased food consumption and food 

efficiency (maternal toxicity) seen in the rabbit developmental toxicity study at the LOAEL of 

150 mg/kg/day (NOAEL = 50 mg/kg/day). The chronic dietary POD is based on decreased body 

weight in females seen in the chronic dog toxicity study at the LOAEL of 40 mg/kg/day 

(NOAEL = 10 mg/kg/day). The Food Quality Protection Act (FQPA) Safety Factor (SF) has 

been reduced to 1X for all exposure durations and routes. Halosulfuron-methyl is classified as 

“not likely to be carcinogenic to humans” and has low acute toxicity (Toxicity Category III-IV) 

via the oral, dermal, and inhalation routes of exposure. It is not a dermal sensitizer. 

Dietary Exposure (Food and Drinking Water) and Risk Estimates 

Unrefined acute (females 13-49 years old) and chronic dietary exposure assessments were 

conducted for the currently registered and proposed new uses of halosulfuron-methyl. There 

were no appropriate toxicological effects attributable to a single exposure (dose) for the general 

population or any other population subgroups except females 13-49 years old; therefore, a 

dietary exposure assessment was not conducted for these population subgroups. The acute 

(females 13-49 years old) and chronic dietary assessments included tolerance-level residues for 

all commodities and assumed 100% crop treated (CT) for all crops. For both the acute and 

chronic assessments, the modeled surface water estimated drinking water concentration (EDWC) 

from the currently registered rice application scenario was the highest EDWC for all 

proposed/registered crops and was incorporated directly into the dietary assessments. 

The results of the acute dietary analysis for food and drinking water indicate that acute dietary 

exposure and risk estimates do not exceed the Agency’s level of concern (LOC = < 100% of the 

acute population adjust dose (aPAD)) for females 13-49 years old. The unrefined acute dietary 

exposure estimate at the 95th percentile is <1% of the aPAD.

The unrefined chronic dietary (food and drinking water) exposure to halosulfuron-methyl is 

below the LOC (<100% of the chronic population adjusted dose (cPAD)) for the general U.S. 

population and all population subgroups. The chronic dietary exposure and risk estimates are 

2.1% of the cPAD for the general U.S. population and 5.7% of the cPAD for children 1-2 years 

old, the most highly exposed population subgroup.

Aggregate Exposure and Risk Estimates 

There is potential short-term exposure to halosulfuron-methyl via dietary (which is considered 

background exposure) and residential (which is considered primary) exposure pathways for 

adults and children. The most conservative scenario was chosen for each population (e.g., 

mixing/loading/applying (M/L/A) via handheld equipment to turf for adults and hand-to mouth 

exposure to treated turf for children 1 to < 2 years old). For adults and children 1 to < 2 years 

old, the short-term aggregate risk estimates are not of concern; the margins of exposure (MOEs) 

are 25,000 and 1,800, respectively. 

Occupational Exposure and Risk Estimates 

There are no occupational handler risk estimates of concern for the proposed uses of 

halosulfuron-methyl at baseline (without personal protective equipment; PPE). The LOC for 

occupational handler risk from inhalation exposures is a MOE < 100. For the proposed uses of 
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

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halosulfuron-methyl, the short-term occupational handler inhalation MOEs ranged from 14,000 

to 50,000,000 and the intermediate-term occupational handler inhalation MOEs ranged from 

2,700 to 9,900,000 at baseline PPE (no respirator). 

Because no dermal hazard was identified, dermal occupational handler and post-application 

assessments were not required. 

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

inhalation exposure assessment was not performed for halosulfuron-methyl at this time. If new 

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

occupational post-application inhalation exposure assessment for halosulfuron-methyl.

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, which include Pesticide 

Handlers Exposure Database Version 1.1 (PHED 1.1); the Agricultural Handler Exposure Task 

Force (AHETF) database; the Residential Standard Operating Procedures (SOPs; Lawns & Turf), 

and other registrant-submitted exposure monitoring studies (MRID 44339801), are (1) subject to 

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

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

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

use, can be found at the Agency website1. 

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://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf).

2.0 HED Recommendations

HED has examined the hazard and exposure databases for halosulfuron-methyl. Pending 

submission of revised Sections B and F (to correct the commodity definition for subgroup 13-

07F) and submission of analytical reference standards, there are no issues that would preclude

the establishment of the recommended tolerances. The recommended tolerances are listed in 

Table 2.2.2, below, the need for analytical reference standards is mentioned in Section 2.1.1, and 

the tolerance recommendations are listed in Section 2.1.2. 

2.1 Tolerance Considerations

2.1.1 Enforcement Analytical Method/Multiresidue Methods

 

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

http://www.epa.gov/pesticides/science/post-app-exposure-data.html
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

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Adequate analytical methods utilizing gas chromatography (GC) thermionic-specific detection 

(TSD, nitrogen specific) are available for the enforcement of tolerances for residues of 

halosulfuron-methyl in plants (Method RES-109-97-4), and a GC/ECD for residues of 

halosulfuron-methyl and its 3-CSA metabolites in livestock commodities (Method RES-046-93). 

The plant method determines halosulfuron-methyl as its rearrangement ester (RRE), and the 

livestock method converts residues of halosulfuron-methyl and metabolites containing the 3-

CSA moiety to 3-CSA for determination. For confirmation, the RRE can be determined by 

GC/MS with monitoring at m/z 327. BEAD/ACB conducted successful petition method 

validations (PMVs) for both methods (G.J. Herndon; D250584; 10/28/1998). 

The analytical reference standards for parent halosulfuron-methyl (having expired on 24 October 

2013) and metabolite 3-CSA (having expired on 17 February 2006) are currently unavailable in 

EPA’s National Pesticide Standards Repository (NPSR). RD should notify the registrant 

regarding this lack of reference standards, and direct the registrant to provide new reference 

standards, or updated certificates of analysis (COAs), as soon as possible.

Data concerning the recovery of halosulfuron-methyl and 3-CSA using the Food and Drug 

Administration (FDA) multiresidue method protocols (PAM Volume I) were previously reviewed 

by HED. Halosulfuron-methyl and 3-CSA were not adequately recovered by any of these 

procedures. The data were forwarded to FDA for evaluation, and updating of PAM Volume I. 

2.1.2 Recommended Tolerances

The Organisation for Economic Co-operation and Development (OECD) tolerance calculation 

procedure was not used for the submitted pear and grape field trial results. The tolerances were 

set at the limit of quantification (LOQ) because all of the residue values obtained were nondetectable (< limit of detection; LOD). 

The submitted pear and grape field trial data are adequate, and support the establishment of 

permanent tolerances in pome fruit group 11-10 and small vine climbing fruit except fuzzy 

kiwifruit subgroup 13-07F at 0.05 ppm. 

Upon establishment of the recommended tolerance in pome fruit group 11-10, the existing 

tolerance in apple should be removed (40 CFR §180.479[a][2]). 

The proposed use on small vine climbing fruit except fuzzy kiwifruit subgroup 13-07F is for 

regional registration, east of the Rocky Mountains only (40 CFR §180.479[c]). 

The incorrect entry, succulent shelled pea and bean subgroup 6, should be removed from 40 CFR 

§180.479[a][2]. The correct entry, succulent shelled pea and bean subgroup 6B, is listed 

immediately beneath the incorrect entry.

TABLE 2.1.2 Tolerance Summary for Halosulfuron-methyl (40 CFR §180.479). 

Proposed or Existing*

Commodity

Proposed or Existing*

Tolerance (ppm)

Recommended 

Tolerance (ppm)

Correct Commodity Definition; 

Comments

40 CFR §180.479(a)(2)
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

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TABLE 2.1.2 Tolerance Summary for Halosulfuron-methyl (40 CFR §180.479). 

Proposed or Existing*

Commodity

Proposed or Existing*

Tolerance (ppm)

Recommended 

Tolerance (ppm)

Correct Commodity Definition; 

Comments

Fruit, pome, group 11-10 0.05 0.05

Based on data supporting the existing 

tolerance in apple, and field trial data 

on pear submitted by IR-4.

Apple* 0.05* Remove Covered by the tolerance to be 

established in pome fruit group 11-10.

40 CFR §180.479(c)

Small fruit vine climbing 

subgroup, except fuzzy

kiwifruit, subgroup l 3-07F

0.05 0.05

Fruit, small, vine climbing, except 

fuzzy kiwifruit, subgroup 13-07F. 

Based on field trial data on grape (the 

representative commodity for the 

subgroup) submitted by IR-4.

* A tolerance is currently established at the listed level in the corresponding commodity. 

The currently established tolerance expressions for halosulfuron-methyl are adequate, and 

include both coverage and compliance statements for enforcement purposes. 

2.1.3 International Harmonization

Codex has not established maximum residue levels (MRLs) for halosulfuron-methyl in either 

group 11-10 or subgroup 13-07F. Canada’s PMRA has an existing MRL in apple at 0.05 mg/kg, 

which is harmonized with the existing tolerance. There are no Canadian MRLs on crop 

subgroup 13-07F or any other members of the pome fruit group 11-10.

2.2 Label Recommendations

2.2.1 Recommendations from Residue Reviews

The labels should stipulate that the minimum PHI is 14 days for group 11-10 and subgroup 13-

07F, as stated in Section B of the petition volume, and as reflected in the pear and grape field 

trial studies. The labels should stipulate that the minimum RTI for pome fruit is 45 days, as 

stated in Section B of the petition volume. 

3.0 Introduction

Halosulfuron-methyl is a selective herbicide belonging to the sulfonylurea group of herbicides, 

which inhibits the action of acetolactate synthase (ALS), a specific plant enzyme not found in 

mammals. Halosulfuron-methyl is used for the pre- and post-emergence control of annual 

broadleaf weeds and nutsedges on various agricultural crops, as well as in residential turf grass 

and ornamentals. Halosulfuron-methyl has been proposed for use on pome fruit group 11-10 and 

small vine climbing fruit except fuzzy kiwifruit subgroup 13-07F by IR-4. 

3.1 Chemical Identity

The chemical structure and nomenclature of halosulfuron-methyl are listed in Table 3.1. 
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TABLE 3.1 Test Compound Nomenclature. 

Chemical structure

Common name halosulfuron-methyl

Company experimental names MON 12000, NC-319

Molecular formula C13H15ClN6O7S

Molecular weight 434.8 amu

IUPAC name methyl 3-chloro-5-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)-1-

methylpyrazole-4-carboxylate

CAS name methyl 3-chloro-5-[[[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]amino]

sulfonyl]-1-methyl-1H-pyrazole-4-carboxylate

CAS registry number 100784-20-1

End-use products (EPs) 75% DF formulation (Sandea Herbicide; EPA Registration #81880-18) and 75% 

DF formulation (GWN-3061 Herbicide; EPA Registration #81880-2). 

Chemical structure of

3-chlorosulfonamide acid 

(3-CSA)

3-chloro-1-methyl-5-sulfamoyl-1H-pyrazole-4-carboxylic acid

3.2 Physical/Chemical Characteristics

Halosulfuron-methyl is a solid under ambient conditions and has a low volatility. The compound 

has a relatively low solubility in organic solvents. It is slightly soluble in water, and this 

solubility increases with increasing pH. Its octanol/water partition coefficient suggests that 

accumulation of halosulfuron-methyl in fatty tissues is unlikely. The physical/chemical 

properties of halosulfuron-methyl are listed in Appendix C. 

3.3 Pesticide Use Pattern

A summary of the proposed uses of halosulfuron-methyl is provided in Table 3.3.

N

N

CH3

Cl

N

N N

H

N

H

O

S

O

O

O

CH3

O

CH3

O

O

CH3

N

N

CH3

Cl

NH2

S

O

O

OH

O
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Table 3.3. Summary of Directions for Use of Halosulfuron-Methyl.

Applic. 

Timing, Type, 

and Equip.

Formulation 

[EPA Reg. 

No.]

Max. 

Applic. 

Rate (lb 

ai/A)

Max. No. 

Applic. per 

Season

Max. 

Seasonal 

Applic. 

Rate (lb 

ai/A)

RTI

(days)

Use Directions and 

Limitations

Pome Fruit Group 11-10

Groundboom1, 

Aerial, 

Handheld

Dry Flowable 

[81880-18 

and 81880-2]

0.094 2

2 0.094 “Later in 

Season”3

May be re-treated once 

later in the season. Do not 

apply to nursery stock. 

Pre-emergence and postemergence applications. 

For best results, apply to 

bare ground. 

Small Fruit Vine Climbing Subgroup, Except Fuzzy Kiwifruit, Subgroup 13-07F

Groundboom1, 

Aerial, 

Handheld

Dry Flowable 

[81880-18 

and 81880-2]

0.047 2 0.094 45

Pre- and post-emergence

directed application. 

Contact with grape vines 

should be avoided. Use of 

a shieldboom is 

recommended. Do not 

contact crop foliage. Do 

not apply to nursery stock. 

1. Not to include chemigation or airblast applications.

2. May apply 2 applications, but not at the maximum single application rate. 

3. See Section 2.0 for recommended label language (RTI - 45 days). 

3.4 Anticipated Exposure Pathways

Humans may be exposed to halosulfuron-methyl in food and drinking water since halosulfuronmethyl may be applied directly to growing crops and application may result in halosulfuronmethyl reaching surface and ground sources of drinking water. In residential settings, residential 

handlers may be exposed while handling halosulfuron-methyl, and adults and children may be 

exposed when contacting turf treated with halosulfuron-methyl. In an occupational setting, 

applicators may be exposed while handling the pesticide prior to application as well as during 

application. There is also a potential for post-application exposure for workers re-entering 

treated fields. 

Dietary and aggregate risk assessments have been completed for the existing uses of 

halosulfuron-methyl. This risk assessment considers all of the aforementioned exposure 

pathways based on the proposed new uses of halosulfuron-methyl, but also considers existing 

uses of halosulfuron-methyl, particularly in the dietary and residential exposure assessments. 

3.5 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://www.epa.gov/environmentaljustice/resources/policy/exec_order_12898.pdf). As a part of 

every pesticide risk assessment, OPP considers a large variety of consumer subgroups according 
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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 National Health and Nutrition Examination Survey, 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. Spray drift can also potentially result in post-application 

exposure and it is also being considered whenever appropriate. Further considerations are also 

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

specialized software and models that consider exposure to other types of possible bystander

exposures and farm workers as well as lifestyle and traditional dietary patterns among specific 

subgroups.

4.0 Hazard Characterization and Dose-Response Assessment

Halosulfuron-methyl is a member of the sulfonylurea class of herbicides. It inhibits acetolactate 

synthase (ALS), an enzyme found in plants and micro-organisms that catalyzes the first step in 

the synthesis of the branched-chain amino acids such as valine, leucine, and isoleucine. ALS is 

also found in mammals, but its function and mode of action are unknown.

4.1 Toxicology Studies Available for Analysis

The halosulfuron-methyl toxicity database is considered adequate for risk assessment; all of the 

required toxicity studies are available to support the proposed uses (Appendix A). At this time 

the requirement for subchronic inhalation toxicity and the immunotoxicity studies are waived (D. 

Smegal, TXR 0054045, 02/22/2012; & K. Rury, TXR 0056723, 08/06/2013). The available 

studies include: 

 a 28-day and a 90-day oral toxicity in rats,

 90-day oral toxicity in dogs,

 21-day dermal toxicity in rats,

 1-year oral toxicity in dogs,

 combined/carcinogenicity in rats,

 carcinogenicity study in mice,

 carcinogenicity study in mice,

 developmental toxicity studies in rats and rabbits,

 2-generation reproduction in rats,

 acute and subchronic neurotoxicity studies,

 metabolism studies, and

 a battery of genotoxicity studies.
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4.2 Absorption, Distribution, Metabolism and Elimination

With oral administration, halosulfuron-methyl was absorbed rapidly but not completely from the 

gastrointestinal tract. In the rat metabolism study, the absorbed halosulfuron-methyl was 

eliminated in the urine and feces within 72 hours, and approximately 90% of the administered

dose was eliminated within 48 hours. Negligible levels of radioactivity were found in most 

tissues with the exception of the blood, in which measurable levels were detected at 7 days post 

dosing (earliest reported examination time). Desmethyl NC-319 and the 5-hydroxy derivatives 

were found in urine and feces, respectively; and these two derivatives were considered to be 

major metabolites. The absorption, elimination, and metabolism showed no sex dependence. 

4.2.1 Dermal absorption

A dermal penetration study is not available for halosulfuron-methyl. However, in-vivo dermal 

absorption data indicate that many sulfonylureas have relatively low dermal absorption values 

(ranging from 1- 4.7% for concentrate and 1.7-21% for dilute formulations in rats). Based on the 

physical chemical properties and structural analysis, dermal absorption for halosulfuron-methyl 

is expected to be within the range of dermal absorption values shown in Appendix B (1-21% invivo dermal absorption in rats). The expected low dermal absorption for halosulfuron-methyl 

was also supported by the results of a 21-day dermal toxicity study, where no toxicity was 

observed up to the limit dose (1000 mg/kg/day).

4.3 Summary of Toxicological Effects

With repeated dosing, the available data did not demonstrate a target organ or tissue in any of the 

test animals. Reduction in body weight was seen in the 90-day and 1-year oral toxicity studies in 

dogs. Reduced body weights were also seen in rat studies at higher dose levels than those seen 

in dogs. An effect on the hematological parameters was detected in the dog studies, but the 

magnitude of changes was slight and the effect was considered to be marginal. Thus, the slight 

hematological changes were not considered to be adverse.

In the prenatal developmental toxicity study in rats, increases in resorptions, soft tissue (dilation 

of the lateral ventricles) and skeletal variations, and decreases in body weights were seen in the 

fetuses compared to clinical signs and decreases in body weights and food consumption in the 

maternal animals at a similar dose level. In the rabbit developmental toxicity study, increases in 

resorptions and post-implantation losses and decreases in mean litter size were observed in the 

presence of decreases in body weight and food consumption in maternal animals. The fetal 

effects seen in developmental toxicity studies in rats and rabbits represented a qualitative 

increase in susceptibility. However, a clear NOAEL for these effects was established in both rat 

and rabbit developmental toxicity studies. No quantitative susceptibility was found in studies 

following pre-and/or post-natal exposures. Halosulfuron-methyl did not produce any effects on 

reproductive parameters in the two-generation reproduction study in rats. No neurotoxic effects 

were observed in the acute or subchronic neurotoxicity studies up to 2000 mg/kg or 760 

mg/kg/day, respectively. In addition, no adverse effect was found in a 21-day dermal toxicity 

study at doses up to the limit dose (1000 mg/kg/day). 
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Halosulfuron-methyl is negative for mutagenicity in a battery of genotoxicity studies. It is 

classified as “not likely to be carcinogenic to humans” based on lack of evidence for 

carcinogenicity in mice and rats following long-term dietary administration. 

Halosulfuron-methyl has low acute toxicity (Toxicity Category III-IV) by oral, dermal, and 

inhalation routes of exposure. It is not a dermal sensitizer, but it produced transient eye irritation 

which was cleared within 24 hours. 

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

The FQPA safety factor has been reduced to 1x for the reasons detailed below (Sections 4.4.1 -

4.4.4). 

4.4.1 Completeness of the Toxicology Database

The toxicology database for halosulfuron-methyl is complete with the requirements for 

inhalation and immunotoxicity studies being waived at this time. Consequently, HED believes 

the existing data are sufficient for toxicity endpoint selection for exposure/risk assessment 

scenarios and for evaluation of the requirements under the FQPA.

4.4.2 Evidence of Neurotoxicity

There was no neurotoxicity found in the halosulfuron-methyl toxicity database. No adverse 

neurobehavioral signs were observed at doses approaching the limit dose in any of the 

subchronic or chronic studies in rats or mice. No neurotoxic effects were observed in acute or

subchronic neurotoxicity studies in which animals were dosed at systemically toxic dose levels.

A developmental neurotoxicity study is not required.

4.4.3 Evidence of Sensitivity/Susceptibility in the Developing or Young Animal

There was no quantitative evidence of increased susceptibility following pre- and/or post-natal 

exposure. However, the qualitative susceptibility observed in the developmental toxicity studies 

in rats and rabbits was of low concern because (1) in both studies, there were clear NOAELs/ 

LOAELs for developmental and maternal toxicities; (2) the developmental effects were seen in 

the presence of maternal toxicity; and (3) the effects were only seen at the high dose levels. In 

rats, the developmental effects were seen at a dose (750 mg/kg/day) which was approaching the 

limit-dose (1000 mg/kg/day). Furthermore, the PODs for risk assessment are protective of the 

effects which occur at high doses. 

4.4.4 Residual Uncertainty in the Exposure Database

There are no residual uncertainties in the exposure database. Since the dietary and non-dietary 

exposure estimates were based on several conservative assumptions, HED does not believe that 

the exposure estimates are underestimated. The dietary assessments conducted with the Dietary 

Exposure Evaluation Model software with the Food Commodity Intake Database (DEEM-FCID)

were conservative and utilized tolerance-level residues for all crops, default processing factors 
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for all commodities, and assumed that 100% of the proposed and registered crops were treated 

with halosulfuron-methyl. The dietary exposure analyses also assumed that all drinking water 

will contain halosulfuron-methyl at the highest EDWC levels modeled by the Environmental 

Fate and Effects Division (EFED) for ground water or surface water. Therefore, the dietary

analysis does not underestimate risk from exposure to halosulfuron-methyl. Similarly, HED 

does not believe that the occupational and residential exposures are underestimated because they 

are also based on conservative assumptions, including maximum application rates, baseline PPE, 

and standard values for unit exposures and acreage treated/amount handled.

4.5 Toxicity Endpoint and Point of Departure (POD) Selections

There is one change to the prior toxicity endpoint and point of departure selections for 

halosulfuron-methyl (Hazard Identification and Assessment Review Committee (HIARC) report, 

08/23/2002; Attachment B). The rationales for endpoint selection as presented in the 2002 

HIARC report on halosulfuron-methyl are considered applicable for the current consideration 

with the exception of the dermal toxicity endpoint. The previous toxicity endpoint for dermal 

exposure assessments was based on the results of a 21-day dermal toxicity study, where the no 

observed effect level (NOEL) and lowest observed effect level (LOEL) were established at 100 

and 1000 mg/kg/day, respectively. The LOEL was based on “total body weight gains in males”. 

However, following a reevaluation of this study according to the current evaluation standard, 

there was only 4% reduction in absolute body weight in the affected 1000 mg/kg/day males. 

This reduction was not considered to be adverse and no other adverse effect was reported in this 

study. No LOAEL could be established, and the NOAEL was 1000 mg/kg/day. Based on this 

re-evaluation, halosulfuron-methyl did not cause adverse effects at the limit dose (1000 

mg/kg/day), and no toxicity endpoint could be established for dermal exposure scenario. In 

addition, no quantitative susceptibility was found in studies following pre-and/or post-natal 

exposures. Hence, no dermal exposure assessment was necessary. 

For the general population acute dietary toxicity endpoint, the available data did not demonstrate 

an adverse effect attributable to a single dose. Although the acute neurotoxicity study 

summarized in Appendix A showed a death occurred in this study, the death was not considered 

to be treatment related and occurred at 2000 mg/kg/day (limit dose for acute neurotoxicity study) 

where no compound related effect was found. Hence, this study was not used for selecting a 

POD for risk assessment.

The PODs and toxicity endpoints selected for various exposure scenarios applicable to this risk 

assessment are summarized in Table 4.5.1. 
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Table 4.5.1 Summary of Toxicological Doses and Endpoints for Halosulfuron-methyl for Use in Dietary, 

Occupational and Non-Occupational Human Health Risk Assessments

Exposure/

Scenario

Point of 

Departure

Uncertainty/

FQPA Safety 

Factors

RfD, PAD, 

LOC for Risk 

Assessment

Study and Toxicological Effects

Acute Dietary

(Females 13-

49 years of 

age)

NOAEL= 

50 

mg/kg/day

UFA= 10x

UFH= 10x

FQPA SF= 

1x

Acute RfD = 0.5 

mg/kg/day

aPAD =0.5 

mg/kg/day

Developmental Toxicity – Rabbit

LOAEL = 150 mg/kg/day based on 

increased number of resorptions (total and 

per dam and increased post-implantation 

loss (developmental toxicity).

Acute Dietary 

(General 

Population)

No adverse effect attributable to a single dose was identified; therefore, no dose/endpoint was 

selected for this exposure scenario.

Chronic 

Dietary (All 

Populations)

NOAEL= 

10 

mg/kg/day

UFA= 10x

UFH= 10x

FQPA SF= 

1x 

Chronic RfD = 

0.1

mg/kg/day

cPAD = 0.1 

mg/kg/day

Chronic Toxicity – Dog

LOAEL = 40 mg/kg/day based on decreased 

body weight in females.

Incidental 

Oral ShortTerm (1-30 

days)

NOAEL= 

50 

mg/kg/day

UFA= 10x

UFH= 10x

FQPA SF= 

1x 

Residential LOC 

for MOE = 100

Developmental Toxicity - Rabbit

LOAEL = 150 mg/kg/day based on 

decreased food consumption and food 

efficiency (maternal toxicity). 

Dermal ShortTerm (1-30 

days) 

IntermediateTerm (1-6 

months)+

A 21-day dermal toxicity tested up to the limit dose (1000 mg/kg/day) demonstrated no adverse 

effects. No dermal toxicity endpoint could be established. 

Inhalation 

Short- Term 

(1-30 days)

NOAEL = 

50 

mg/kg/day

UFA= 10x

UFH= 10x

FQPA SF= 

1x 

Residential and 

Occupational 

LOC for MOE = 

100

Developmental Toxicity - Rabbit

LOAEL = 150 mg/kg/day based on

decreased food consumption and food 

efficiency (maternal toxicity).

Cancer (oral, 

dermal, 

inhalation)

Classification: "not likely to be carcinogenic to humans" by the oral route, based on no evidence 

of carcinogenicity from studies in rats and mice.

Toxicity via the inhalation route is presumed to be equivalent to oral toxicity. 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 (intra-species). FQPA SF = FQPA 

Safety Factor. PAD = population adjusted dose (a = acute, c = chronic). RfD = reference dose. MOE = margin of exposure. 

LOC = level of concern. N/A = not applicable

5.0 Dietary Exposure and Risk Assessment 

5.1 Residues of Concern Summary and Rationale

HED has concluded that the residue of concern for tolerance enforcement and risk assessment in 

target plants and rotational plants is halosulfuron-methyl (G. J. Herndon, No DP #, 09/16/1993 

and 05/21/1996). 

HED previously concluded that the residue of concern in ruminants is halosulfuron-methyl.

However, because the approved enforcement method for livestock commodities quantifies the 

parent compound and metabolites containing the 3-CSA moiety by converting residues to 3-
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CSA, tolerances for residues of parent and its metabolites in livestock commodities are 

determined as 3-CSA, expressed in halosulfuron-methyl equivalents. 

The residue of concern in drinking water is halosulfuron-methyl. 

Table 5.1. Summary of Halosulfuron-methyl Metabolites and Degradates to be included in the Risk 

Assessment and Tolerance Expression. 

Matrix Residues Included in Risk 

Assessment

Residues Included in 

Tolerance Expression

Plants Primary Crop Halosulfuron-methyl Halosulfuron-methyl

Rotational Crop Halosulfuron-methyl Halosulfuron-methyl

Livestock Ruminant Halosulfuron-methyl* Halosulfuron-methyl, 3-CSA

Poultry Halosulfuron-methyl* Halosulfuron-methyl, 3-CSA

Drinking Water Halosulfuron-methyl Not Applicable

*Residues are determined as 3-CSA, and expressed in halosulfuron-methyl equivalents.

5.2 Food Residue Profile

The data submitted in support of the requested uses (PP#4E8297), along with previously 

reviewed data, are adequate for risk and tolerance assessment. Maximum residues of 

halosulfuron-methyl are expected to occur at very low levels (<0.05 ppm, the LOQ) from the 

new uses on group 11-10 and subgroup 13-07F proposed in the current petition. The established 

livestock tolerances are adequate to cover the proposed and registered uses.

Halosulfuron-methyl residues generally tend to decline or remain stable with increasing PHI, and 

do not increase to any significant degree. Following foliar applications, halosulfuron-methyl is 

present primarily as surface residues; translocation does not appear to be extensive. In general, 

halosulfuron-methyl residues do not tend to concentrate in processed fractions, other than via 

dehydration or from surface residues. 

Residues of halosulfuron-methyl are not expected to accumulate above the LOQ in rotational 

crops. HED previously concluded that rotational crop tolerances and restrictions are not required 

for halosulfuron-methyl. 

No significant livestock feedstuffs are associated with the proposed new uses on group 11-10 and 

subgroup 13-07F. Feed items associated with the existing use on apple were addressed 

previously, in conjunction with registration of the use on that commodity. 

5.3 Water Residue Profile

Tier I surface and ground water EDWCs were evaluated for the proposed new uses of 

halosulfuron-methyl and to incorporate updated models employed by EFED, including the

Pesticide Root Zone Model - Ground Water (PRZM-GW) (M. Barrett, D421820, 04/15/2015). 

However, the highest EDWCs continue to be from the existing use on rice. The Tier I EDWCs 

for halosulfuron-methyl are based on a maximum annual application rate of 0.125 lb ai/A for 

rice. The two screening models, the Food Quality Protection Act (FQPA) Index Resevoir 

Screening Tool (FIRST) and Screening Concentrations in Ground Water (SCI-GROW), were 
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used for estimating EDWCs of halosulfuron-methyl. Estimates for halosulfuron-methyl in 

surface water based on the FIRST model for rice are 59.2 ppb for both acute and chronic 

concentrations. 

Table 5.3 summarizes the results. 

Table 5.3. Summary of Estimated Surface Water and Groundwater Concentrations for 

Halosulfuron-methyl.

Duration Surface Water Conc., ppb a Groundwater Conc., 

ppb b

Acute 59.2 0.065

Chronic (non-cancer) 59.2 0.065

a From the FIRST model. 

b From the SCI-GROW model.

The drinking water models and their descriptions are available at the EPA internet site: 

http://www.epa.gov/oppefed1/models/water/. 

5.4 Dietary Risk Assessment

Acute and chronic aggregate dietary (food and drinking water) exposure and risk assessments 

were conducted using the DEEM-FCID Version 3.16. This software uses 2003-2008 food 

consumption data from the U.S. Department of Agriculture’s (USDA’s) National Health and 

Nutrition Examination Survey, What We Eat in America (NHANES/WWEIA). 

5.4.1 Description of Residue Data Used in Dietary Assessment

The acute and chronic assessments are unrefined assessments using proposed and established 

tolerance-level residues and 100% CT for all commodities. Additionally, DEEM default 

processing factors were assumed except for where tolerances were established for processed 

commodities or when processing studies showed no concentration. Based on processing studies, 

the default processing factors were reduced to 1 for tomato paste, tomato puree, potato flour, and 

potato granules/flakes. 

5.4.2 Percent Crop Treated Used in Dietary Assessment

The acute and chronic dietary exposure assessments assumed that 100% of the proposed and 

registered crops were treated with halosulfuron-methyl (100% CT).

5.4.3 Acute Dietary Risk Assessment

There was no indication of an adverse effect attributable to a single dose for the general U.S. 

population. However, an aRfD was established for females 13-49 years old, and an acute dietary 

exposure assessment was only conducted for that population subgroup. The unrefined acute 

dietary exposure estimate at the 95th percentile is <1% of the aPAD for females 13-49 years old.
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5.4.4 Chronic Dietary Risk Assessment

The unrefined chronic dietary (food and drinking water) exposure to halosulfuron-methyl is 

below HED’s level of concern (<100% of the cPAD) for the general U.S. population and all 

population subgroups. The chronic dietary exposure estimates are 2.1% of the cPAD for the 

general U.S. population and 5.7% of the cPAD for children 1-2 years old, the most highly 

exposed population subgroup.

5.4.5 Cancer Dietary Risk Assessment

Halosulfuron-methyl is classified as “not likely to be carcinogenic to humans”; therefore a 

cancer dietary exposure assessment was not conducted. 

5.4.6 Summary Table

Table 5.4.6. Summary of Dietary (Food and Drinking Water) Exposure and Risk for 

Halosulfuron-Methyl.

Population Subgroup

Acute Dietary

(95th Percentile) Chronic Dietary

Dietary 

Exposure 

(mg/kg/day)

% aPAD*

Dietary 

Exposure

(mg/kg/day)

% cPAD*

General U.S. Population

N/A N/A

0.002091 2.1

All Infants (<1 year old) 0.004987 5.0

Children 1-2 years old* 0.005740 5.7

Children 3-5 years old 0.004025 4.0

Children 6-12 years old 0.002488 2.5

Youth 13-19 years old 0.001597 1.6

Adults 20-49 years old 0.001817 1.8

Adults 50-99 years old 0.001767 1.8

Females 13-49 years old 0.004139 <1 0.001812 1.8

*The subpopulation(s) with the highest risk estimates. The highest risk estimate is bolded. 

6.0 Residential (Non-Occupational) Exposure/Risk Characterization

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

uses that have been reassessed to reflect the removal of the dermal POD for halosulfuron-methyl; 

therefore, the residential scenarios for aggregate risk assessment have changed. 

Since the estimated children’s post-application incidental oral exposure from halosulfuronmethyl applications to residential turf using default TTR values for halosulfuron-methyl is 

minimal in comparison to the level of concern (i.e., the calculated MOE is greater than 10 times 

higher than the level of concern, MOE = 24,000 compared to the LOC of 100), EPA is waiving 

the 40 CFR TTR data requirement. In this instance, it is unlikely that chemical-specific TTR 
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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 more details. 

6.1 Residential Risk Estimates for Use in Aggregate Assessment

Table 6.1 reflects the residential risk estimates that are recommended for use in the aggregate 

assessment for halosulfuron-methyl.

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

inhalation exposure from mixing/loading/applying halosulfuron-methyl via backpack 

sprayer or manually pressurized handwand to turf.

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

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

turf.

Table 6.1. Recommendations for the Residential Exposures for the Halosulfuron-Methyl Aggregate Assessment.

Lifestage Exposure Scenario

Dose (mg/kg/day)1 MOE2

Inhalation Oral Inhalation Oral

Adults

M/L/A via Backpack Sprayer or 

Manually-Pressurized Handwand 

to Turf

0.000215 N/A 230,000 N/A

Children

(1 to <2 years 

old)

Hand-to-Mouth Exposure to 

Treated Turf N/A 0.00207 N/A 24,000

1 Dose = the highest dose for each applicable lifestage of all residential scenarios assessed. 

2 MOE = margin of exposure. These MOEs are associated with the highest residential doses. 

6.2 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 

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

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

inhalation toxicological studies) or further analysis is required for halosulfuron-methyl.

In addition to this screen, the Agency has developed a preliminary bystander volatilization 

inhalation exposure assessment for halosulfuron-methyl utilizing the currently available 

inhalation toxicity and air monitoring data. 

6.3 Spray Drift

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

particularly the case with aerial application, but, to a lesser extent, spray drift can also be a 
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potential source of exposure from the ground application methods (e.g., groundboom and 

airblast) employed for halosulfuron-methyl. The agency has been working with the Spray Drift 

Task Force (a task force composed of various registrants which was developed as a result of a 

Data Call-In issued by EPA), EPA Regional Offices and State Lead Agencies for pesticide 

regulation and other parties to develop the best spray drift management practices (see the 

agency’s Spray Drift website for more information). 2 The Agency has also developed a policy 

on how to appropriately consider spray drift as a potential source of exposure in risk assessments 

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

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

considered concurrently. The approach is outlined in the revised (2012) Standard Operating 

Procedures For Residential Risk Assessment (SOPs) - Residential Exposure Assessment 

Standard Operating Procedures Addenda 1: Consideration of Spray Drift. This document

outlines the quantification of indirect non-occupational exposure to drift. 

7.0 Aggregate Exposure/Risk Characterization

HED must consider and aggregate (add) pesticide exposures and risks from three major sources: 

food, drinking water, and residential exposures. In an aggregate assessment, exposures from 

relevant sources are added together and compared to quantitative estimates of hazard (e.g. a 

NOAEL or PAD), or the risks themselves can be aggregated. When aggregating exposures and 

risks from various sources, HED considers both the route and duration of exposure. For 

halosulfuron-methyl, potential exposures from food, drinking water and residential scenarios 

were aggregated. 

This assessment has utilized the Residential SOPs implemented in January of 2012 and the 

updated PODs for halosulfuron-methyl (i.e., the dermal POD was removed since the previous 

assessment). HED confirms that there are no risk estimates of concern resulting from the 

proposed or existing uses of halosulfuron-methyl.

7.1 Acute Aggregate Risk

The aggregate acute risk estimates include exposure to residues of halosulfuron-methyl in food 

and water, and do not include dermal, inhalation, or incidental oral exposure. There were no 

appropriate toxicological effects attributable to a single exposure (dose) for the general 

population or any other population subgroups except females 13-49 years old; therefore, an 

aggregate exposure assessment was not conducted for these population subgroups. The acute 

risk estimate for the females 13-49 years old, resulting from aggregate exposure to halosulfuronmethyl in food and drinking water, is below the Agency’s LOC and is <1% of the aPAD. There 

was no indication of an adverse effect attributable to a single dose for the general U.S. 

population. 

7.2 Short-Term Aggregate Risk

 

2 Available: http://www.epa.gov/opp00001/factsheets/spraydrift.htm 
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There is potential short-term exposure to halosulfuron-methyl via dietary (which is considered 

background exposure) and residential (which is considered primary) exposure pathways. The 

most conservative scenario was chosen for each population (e.g., hand-to mouth exposure to 

treated turf for children 1 to < 2 years old and M/L/A via handheld equipment to turf for adults). 

For adults and children 1 to < 2 years old, the short-term aggregate risk estimates are not of 

concern; the MOEs are 22,000 and 1,800, respectively. For a description of the residential 

exposure scenarios considered in the aggregate risk assessment, see K. Rury, D425728, 

05/25/2015 and N. Tsaur, D396460, 06/12/2012. 

Table 7.2 Short-Term Aggregate Risk Calculations.

Population

Short- or Intermediate-Term Scenario

NOAEL 

mg/kg/day LOC1

Average 

Food and 

Water 

Exposure 

mg/kg/day

Residential 

Exposure 

mg/kg/day2

Total 

Exposure 

mg/kg/day3

Aggregate MOE 

(food, water, 

and residential)4

Adults

5

50 100

0.001817 0.000215 0.002032 25,000

Children 1 to < 

2 years old 0.00574 0.00207 0.02854 1,800

1 LOC = 100, 10X UFA, 10X UFH, FQPA SF = 1X. 

2 Residential Exposure Scenarios = Table 6.1.

3 Total Exposure = Avg Food & Water Exposure + Residential Exposure)

4 Aggregate MOE = Incidental Oral NOAEL 50 mg/kg/day ÷ Total Exposure)

5 Adult subpopulation selected from the dietary exposure assessment is Adults 20-49 from the chronic dietary exposure 

assessment, which is the most protective adult subpopulation. 

7.3 Intermediate-Term Aggregate Risk

Intermediate-term residential exposure is not expected for halosulfuron-methyl due to the 

intermittent application by homeowners. Therefore, the intermediate-term aggregate risk would 

be equivalent to the chronic dietary exposure estimate. 

7.4 Chronic Aggregate Risk

Chronic exposure is not expected for the adult residential (dermal and inhalation) exposure 

pathway. Therefore, the chronic aggregate risk would be equivalent to the chronic dietary 

exposure estimate. Refer to Section 5.4.4 for the chronic dietary (food and drinking water) 

exposure assessment. 

7.5 Cancer Aggregate Risk

Halosulfuron-methyl is considered “not likely to be carcinogenic to humans;” therefore, an 

aggregate cancer risk assessment has not been conducted. 

8.0 Cumulative Exposure/Risk Characterization

Unlike other pesticides for which EPA has followed a cumulative risk approach based on a 

common mechanism of toxicity, EPA has not made a common mechanism of toxicity finding as 
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to halosulfuron-methyl and any other substances and halosulfuron-methyl does not appear to 

produce a toxic metabolite produced by other substances. For the purposes of this tolerance 

action, therefore, EPA has not assumed that halosulfuron-methyl has a common mechanism of 

toxicity with other substances. For information regarding EPA’s efforts to determine which 

chemicals have a common mechanism of toxicity and to evaluate the cumulative effects of such 

chemicals, see the policy statements released by EPA’s Office of Pesticide Programs concerning 

common mechanism determinations and procedures for cumulating effects from substances 

found to have a common mechanism on EPA’s website at 

http://www.epa.gov/pesticides/cumulative/.

9.0 Occupational Exposure/Risk Characterization

This document presents an assessment of the proposed uses of halosulfuron-methyl on pome 

fruit crop group 11-10 and small fruit vine climbing subgroup, except fuzzy kiwifruit, subgroup 

13-07F. Based on application rate and label information, only short- and intermediate-term 

exposure is expected for occupational handlers and post-application workers. Chronic exposure 

is not expected for the proposed use pattern. 

9.1 Short-/Intermediate-Term Handler Risk

There are no occupational handler risk estimates of concern for the proposed uses of 

halosulfuron-methyl at baseline (no personal protective equipment; PPE). The LOC for 

occupational handler risk is a margin of exposure (MOE) < 100. At baseline PPE (no respirator), 

the short-term occupational handler MOEs ranged from 14,000 to 50,000,000 and the 

intermediate-term occupational handler MOEs ranged from 2,700 to 9,900,000 for the proposed 

uses of halosulfuron-methyl. See Tables 9.1.1 and 9.1.2 for details. 
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1 Based on the “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table”; Level of mitigation: Baseline or Eng. Controls (enclosed cockpits for aerial applications).

2 Based on registered or proposed labels (Reg. Nos. 81880-18 and 81880-2).

3 Exposure Science Advisory Council Policy #9.1.

4 Inhalation Dose = Inhalation Unit Exposure (μg/lb ai) × Conversion Factor (0.001 mg/μg) × Application Rate (lb ai/acre or gal) × Area Treated or Amount Handled Daily (A or gal/day) ÷ BW (80 

kg).

5 Inhalation MOE = Inhalation NOAEL (50 mg/kg/day) ÷ Inhalation Dose (mg/kg/day).

Table 9.1.1. Occupational Handler Short-Term Exposure and Risk Estimates for Halosulfuron-Methyl.

Exposure Scenario Crop or Target LOC

Inhalation Unit 

Exposure (μg/lb ai)1 Maximum

Application Rate2

Area Treated or 

Amount Handled 

Daily3

Inhalation

Baseline Dose 

(mg/kg/day)4 MOE5

Mixer/Loader

Mixing/Loading for Aerial 

Application

Pome Fruit

100

8.96

0.094 lb ai/A

350 acres

0.00369 14,000

Small Fruit Vine 

Climbing 0.047 lb ai/A 0.00184 27,000

Mixing/Loading for 

Groundboom Application

Pome Fruit

8.96

0.094 lb ai/A

40 acres

0.000421 120,000

Small Fruit Vine 

Climbing 0.047 lb ai/A 0.00021 240,000

Applicator

Applying Sprays via Aerial 

Equipment

Pome Fruit

100

0.0049

(engineering control -

enclosed cockpit)

0.094 lb ai/A

350 acres

0.00000201 25,000,000

Small Fruit Vine 

Climbing 0.047 lb ai/A 0.00000101 50,000,000

Applying Sprays via 

Groundboom Equipment

Pome Fruit

0.34

0.094 lb ai/A

40 acres

0.0000160 3,100,000

Small Fruit Vine 

Climbing 0.047 lb ai/A 0.00000799 6,300,000

Flagger

Flagging for Aerial Applications

Pome Fruit

100 0.35

0.094 lb ai/A

350 acres

0.000144 350,000

Small Fruit Vine 

Climbing 0.047 lb ai/A 0.0000720 690,000

Mixer/Loader/Applicator

Mixing/Loading/Applying via 

Backpack Sprayer (Soil 

Directed)

Pome Fruit

100

2.58

0.0063 lb ai/gal

40 gallons

0.00000806 6,200,000

Small Fruit Vine 

Climbing 0.0031 lb ai/gal 0.00000040 13,000,000

Mixing/Loading/Applying via 

Mechanically Pressurized 

Handgun (Soil Directed)

Pome Fruit

3.9

0.0063 lb ai/gal

1000 gallons

0.000305 160,000

Small Fruit Vine 

Climbing 0.0031 lb ai/gal 0.000151 330,000
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

Page 24 of 40

1 Based on the “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table”; Level of mitigation: Baseline or Eng. Controls (enclosed cockpits for aerial applications).

2 Based on registered or proposed labels (Reg. Nos. 81880-18 and 81880-2).

3 Exposure Science Advisory Council Policy #9.1.

4 Inhalation Dose = Inhalation Unit Exposure (μg/lb ai) × Conversion Factor (0.001 mg/μg) × Application Rate (lb ai/acre or gal) × Area Treated or Amount Handled Daily (A or gal/day) ÷ BW (80 

kg).

5 Inhalation MOE = Inhalation NOAEL (10 mg/kg/day) ÷ Inhalation Dose (mg/kg/day).

Table 9.1.2. Occupational Handler Intermediate-Term Exposure and Risk Estimates for Halosulfuron-Methyl.

Exposure Scenario Crop or Target Level of 

Concern

Inhalation Unit 

Exposure (μg/lb ai)1 Maximum

Application Rate2

Area Treated or 

Amount Handled 

Daily3

Inhalation

Baseline Dose (mg/kg/day)4 MOE5

Mixer/Loader

Mixing/Loading for Aerial 

Application

Pome Fruit

100

8.96

0.094 lb ai/A

350 acres

0.00369 2,700

Small Fruit Vine 

Climbing 0.047 lb ai/A 0.00184 5,400

Mixing/Loading for 

Groundboom Application

Pome Fruit

8.96

0.094 lb ai/A

40 acres

0.000421 24,000

Small Fruit Vine 

Climbing 0.047 lb ai/A 0.00021 48,000

Applicator

Applying Sprays via Aerial 

Equipment

Pome Fruit

100

0.0049

(engineering control 

- enclosed cockpit)

0.094 lb ai/A

350 acres

0.00000201 5,000,000

Small Fruit Vine 

Climbing 0.047 lb ai/A 0.00000101 9,900,000

Applying Sprays via 

Groundboom Equipment

Pome Fruit

0.34

0.094 lb ai/A

40 acres

0.0000160 630,000

Small Fruit Vine 

Climbing 0.047 lb ai/A 0.00000799 1,300,000

Flagger

Flagging for Aerial Applications

Pome Fruit

100 0.35

0.094 lb ai/A

350 acres

0.000144 69,000

Small Fruit Vine 

Climbing 0.047 lb ai/A 0.0000720 140,000

Mixer/Loader/Applicator

Mixing/Loading/Applying via 

Backpack Sprayer (Soil 

Directed)

Pome Fruit

100

2.58

0.0063 lb ai/gal

40 gallons

0.00000806 1,200,000

Small Fruit Vine 

Climbing 0.0031 lb ai/gal 0.00000040 2,500,000

Mixing/Loading/Applying via 

Mechanically Pressurized 

Handgun (Soil Directed)

Pome Fruit

3.9

0.0063 lb ai/gal

1000 gallons

0.000305 33,000

Small Fruit Vine 

Climbing 0.0031 lb ai/gal 0.000151 66,000
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

Page 25 of 40

9.2 Short-/Intermediate-Term Post-Application Risk

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.

9.2.1 Dermal Post-Application Risk

There is no hazard identified for halosulfuron-methyl via the dermal route of exposure; therefore, 

an occupational dermal post-application assessment and a dislodgeable foliar residue (DFR)

study are not required at this time (see Appendix F). 

Restricted Entry Interval

Since short- and intermediate-term post-application risk estimates are not of concern on day 0 for 

all post-application activities, the REI specified on the proposed label is based on the acute 

toxicity of halosulfuron-methyl. Halosulfuron-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. 

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

irritation and primary skin irritation are assigned a 12-hour REI. Therefore, the 40 CFR 156 

subpart K Worker Protection Statement interim REI of 12 hours is adequate to protect 

agricultural workers from post-application exposures to halosulfuron-methyl. 

9.2.2 Inhalation Post-Application Risk

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 halosulfuron-methyl.

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 
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

Page 26 of 40

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.

10.0 References

M. Barrett; 04/15/2015; D421820. Halosulfuron-methyl Drinking Water Assessment for 

Additional Food/Feed Uses on Pome Fruits Group 11-10 and Climbing Vines Subgroup 13-07F. 

S. Healy; 03/25/2013; D404095. Halosulfuron-Methyl: Human Health Risk Assessment for 

Proposed New Uses on Artichoke and Caneberry (Crop subgroup 13-07A).

K. Rury; 08/06/2013; TXR0056723. Sulfonylureas: Summary of Hazard and Science Policy 

Council (HASPOC) Meeting on July 18, 2013: Recommendations on Data Requirement for 

Immunotoxicity Studies for Sulfonylurea Pesticides.

K. Rury; 05/25/2015; D425728. Halosulfuron-Methyl. Occupational and Residential Exposure 

Assessment for a Proposed Use on Pome Fruit Crop Group 11-10 and Small Fruit Vine Climbing 

Subgroup, Except Fuzzy Kiwifruit, Subgroup 13-07F. 

K. Rury; 05/25/2015; D426724. Halosulfuron-Methyl. Acute and Chronic Aggregate Dietary 

(Food and Drinking Water) Exposure and Risk Assessments for the Section 3 Registration 

Action on Pome Fruit Group 11-10 and Fruit, Small Vine Climbing Subgroup 13-07F. 

D. Smegal; 02/22/2012; TXR0054045. Halosulfuron-methyl: Summary of Hazard and Science 

Policy Council (HASPOC) Meeting of February 9, 2012: Recommendations on waiver requests 

for 28-day inhalation study.

N. Tsaur; 06/12/2013; D396460. Halosulfuron-Methyl. Occupational Exposure Assessment for 

Proposed New Uses on Proso Millet and Crop Group 17 (Grass, Forage, Fodder, and Hay) with 

An Updated Residential Exposure Assessment of All Existing Residential Uses.

W. Drew; 05/XX/2015; D426614. Petition to Establish Permanent Tolerances, and Associated 

Section 3 Registration, for Residues Resulting from Use of the Herbicide on Pome Fruit Group 

11-10 and Small Vine Climbing Fruit Except Fuzzy Kiwifruit Subgroup 13-07F (Regional 

Registration). Summary of Analytical Chemistry and Residue Data.
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

Page 27 of 40

Appendix A. Toxicology Profile and Executive Summaries

A.1 Toxicology Data Requirements

The requirements (40 CFR 158.500) for food use for halosulfuron-methyl are in Table 1. Use of the new guideline 

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

Study

Technical

Required Satisfied

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

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

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

870.2400 Acute Eye Irritation.......................................................

870.2500 Acute Dermal Irritation .................................................

870.2600 Skin Sensitization..........................................................

yes

yes

yes

yes

yes

yes

Yes

yes

yes

yes

yes

yes

870.3100 90-Day Oral Toxicity in Rodents..................................

870.3150 90-Day Oral Toxicity in Nonrodents.............................

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

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

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

yes

yes

yes

no

CR

Yes

yes

yes

no

waiveda

870.3700a Prenatal Developmental Toxicity (rodent) ....................

870.3700b Prenatal Developmental Toxicity (nonrodent) ..............

870.3800 Reproduction and Fertility Effects ................................

yes 

yes 

yes

Yes

yes

yes

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

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

870.4300 Combined Chronic Toxicity/Carcinogenicity ...............

no

yes

yes

Yes

yes

yes

870.5100 Mutagenicity—Bacterial Reverse Mutation Test ..........

870.5300 Mutagenicity—Mammalian Cell Gene Mutation Test..

870.5375 Mutagenicity—Structural Chromosomal Aberrations...

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

yes

yes

yes

yes

Yes

yes

yes

yes

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

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

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

yes

yes

no

Yes

yes

-

870.7485 Metabolism and Pharmacokinetics................................

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

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

yes

no

yes

Yes

-

waivedb

 

a

: TXR 0054045; 02/22/2012. 

b

: TXR 0056723; 08/06/2013.
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

Page 28 of 40

A.2 Toxicity Profiles

Table 1. Acute Toxicity of Halosulfuron-Methyl Technical.

OPPTS 

No.

Study Type MRID Results Toxicity 

Category

870.1100 Acute Oral- Rats 42139413 LD50: Males = 10,435 mg/kg

 Females = 7758 mg/kg

 Combined = 8866 mg/kg

IV

870.1200 Acute Dermal- Rats 42139415 LD50 >2000 mg/kg (limit test) III

870.1300 Acute Inhalation- Rats 42139417 LC50 >6 mg/L IV

870.2400 Primary Eye IrritationRabbits42139419 Mild transient (<24 hr) irritation 

involving the conjunctiva and iris.

IV

870.2500 Primary Skin 

Irritation- Rabbits

42139421 Non-irritant IV

870.2600 Dermal SensitizationGuinea pigs42139423 Not a skin sensitizer (maximization test) N/A

Table 2. Toxicity Profile of Halosulfuron-Methyl Technical.

Guideline 

No.

Study Type MRID No. 

(Date)/Classification/ Doses

Results

870.3100 

(82-1)

Subchronic oral 

toxicity study in 

rats 

43616301 (1995)/ 

Acceptable/Guideline

Doses: 0, 100, 1000, 10000, or 

20000 ppm (diet) (M/F: 

6.7/7.6, 66.5/75.8, 682.8/772.8, 

1400/1578 mg/kg/day)

NOAEL = M > 1400, F = 75.8 mg/kg/day

LOAEL = M not determined, F = 772.8 mg/kg/day 

based on decreased body weight gains.

870.3100 

(82-1)

Subchronic oral 

toxicity study in 

rats (28 day rangefinder)

42171501 (1988)/ 

Acceptable/Nonguideline 

Doses: 0, 100, 400, 1600, or 

6400 ppm (diet)

(M/F: 7.4/8.9, 28.8/37.3, 

116/147, 497/640 mg/kg/day)

NOAEL = M = 116, F =147 mg/kg/day

LOAEL = M = 497, F = 640 mg/kg/day based on

decreased organ weights and changes in clinical 

chemistry parameters.

870.3150 

(82-1)

Subchronic oral 

toxicity study in 

nonrodents - dogs 

42171502 (1991)/ 

Acceptable/Guideline

Doses: 0, 2.5, 10, 40, and 160 

mg/kg/day (capsule) 

NOAEL = 10 mg/kg/day

LOAEL = 40 mg/kg/day based on ↓bwt, cholesterol, 

& albumin levels. The decrease was particularly 

marked at the next higher dose level, 160 

mg/kg/day.

870.3200 

(82-2)

21-day dermal 

toxicity in rats

42661417 (1990)/ 

Acceptable/Guideline

Doses: 0, 10, 100, or 1000 

mg/kg/day

No adverse effects was seen at the highest dose level.

NOAEL = 1000 mg/kg/day (Highest dose tested)

(limit dose)

870.3465 

(82-4)

90-day inhalation 

study in rats

The requirement of this study was waived (TXR 0054045; 02/22/12)

870.4100 

(83-1b) 

42396211 (1991)/ 

Acceptable/Guideline

NOAEL = 10 mg/kg/day
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

Page 29 of 40

Table 2. Toxicity Profile of Halosulfuron-Methyl Technical.

Guideline 

No.

Study Type MRID No. 

(Date)/Classification/ Doses

Results

Chronic oral 

toxicity study in 

dogs (1-year)

Doses: 0, 0.25, 1.0, 10.0, or 40 

mg/kg/day (capsule).

LOAEL = 40 mg/kg/day based on ↓bwt (9-13%); 

↓RBC, hematocrit, & hemoglobin; ↓ cholesterol

870.4300 

(83-5)

Combined 

Chronic/ 

Carcinogenicity in 

rats

42661418 (1992)/ 

Acceptable/Guideline

Doses: 0, 10, 100, 1000, or 

2500, 5000 (males only) ppm 

(diet)

(M/F: 0.44/0.56, 4.4/5.6, 

43.8/56.3, 108.3/138.6, 225.6 

(M) mg/kg/day)

NOAEL = M=108.3, F=56.3 mg/kg/day

LOAEL = M=225.6, F=138.6 mg/kg/day based on 

marginal decrease in body weight gain in both males 

and females.

No evidence of carcinogenicity.

870.4200 

(83-2) 

Carcinogenicity 

study in mice 

42661419 (1992)/ 

Acceptable/Guideline

Doses: 0, 30, 300, 3000, or 

7000 ppm (diet)

(M/F: 4.0/5.2, 41.1/51.0, 

410.0/509.1, or 971.9/1214.6 

mg/kg/day)

NOAEL = M=410.0, F > 1214.6 mg/kg/day

LOAEL = M=971.9, F>1214.6 mg/kg/day based on 

necropsy findings (increase incidence of 

microconcretion/mineralization in the testis and 

epididymis). 

No evidence of carcinogenicity.

870.3700 

(83-3) 

Developmental 

toxicity in rats

42139425 (1990)/ 

Acceptable/Guideline

Doses: 0, 75, 250, or 750 

mg/kg/day (gavage)

Maternal NOAEL = 250 mg/kg/day.

Maternal LOAEL = 750 mg/kg/day, based on increased 

incidence of clinical observations, reduced food 

consumption and food efficiency.

Developmental NOAEL = 250 mg/kg/day. 

Developmental LOAEL = 750 mg/kg/day, based on 

decreased mean fetal body weight and mean litter size, 

increased fetal and litter incidences of soft tissue and 

skeletal variations.

870.3700 

(83-3b)

Developmental 

toxicity study in 

rabbits

42139426 (1990)/ 

Acceptable/Guideline

Doses: 0, 15, 50, or 150 

mg/kg/day (gavage)

Maternal NOAEL = 50 mg/kg/day

Maternal LOAEL = 150 mg/kg/day based on reduced 

body weight gain, food consumption and food 

efficiency.

Developmental NOAEL = 50 mg/kg/day

Developmental LOAEL = 150 mg/kg/day based on 

group decreased mean litter size, increased number of 

resorptions and resorptions per dam, and increased 

postimplantation loss.

870.3700 

(83-3b)

Developmental 

toxicity study in 

rabbits

43621901 (1995) 3-

chlorosulfonamide acid

Metabolite/

Acceptable/Guideline

Doses: 0, 30, 300, or 1000 

mg/kg/day 

Maternal Toxicity NOAEL => 1000 mg/kg/day

Maternal Toxicity LOAEL > 1000 mg/kg/day

Developmental Toxicity NOAEL => 1000 mg/kg/day

Developmental Toxicity LOAEL > 1000 mg/kg/day

870.3800 

(83-4)

Two-Generation 

reproduction study 

in rats

42139427 (1991)/ 

Acceptable/Guideline

Doses: 0, 100, 800, or 3600 

ppm (diet)

( F0 Males: 6.3, 50.4, and 223.2 

mg/kg/day; F0 Females: 7.4, 

58.7, and 261.4 mg/kg/day)

Parental/Systemic NOAEL = M=50.5, F=58.7 

mg/kg/day 

Parental/Systemic LOAEL = M=223.2, F=261.4 

mg/kg/day based on decreased body weights and 

reduced food consumption during the premating period 

in both sexes.

Offspring NOAEL = 51/59 mg/kg/day
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

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Table 2. Toxicity Profile of Halosulfuron-Methyl Technical.

Guideline 

No.

Study Type MRID No. 

(Date)/Classification/ Doses

Results

Offspring LOAEL = 223.2/261.4 mg/kg/day based on 

decreased body weight in the F1 pups and marginal 

decreased body weight in F2 pups.

Reproductive NOAEL > = 223.2/261.4 mg/kg/day.

870.6200a 

(82-7)

Acute 

neurotoxicity in 

rats.

45754701 (1994) and 

46199501 (1989)[positive 

control study]/ 

Acceptable/Guideline

Doses: 0, 200, 600, or 2000 

mg/kg (limit dose)

NOAEL = 600 mg/kg. 

LOAEL = 2000 mg/kg (limit dose) based on mortality 

in males. 

870.6200b 

(82-7)

Subchronic 

neurotoxicity 

study in rats.

45754702 (1992)/ 

Acceptable/Guideline

Doses: M: 0, 100, 1000, or 

10,000 ppm; F: 0, 100, 1000, 

or 4000 ppm (diet) (M/F: 0/0, 

6.3/8.1, 62.8/82.6, or 

706.0/315.9 mg/kg/day)

NOAEL = M = F = 1000 ppm (M/F: 62.8/82.6 

mg/kg/day). 

LOAEL = M = 10,000 ppm; F =4000 ppm (M: 706.0 

mg/kg/day) in males based on decreased body weight 

and body weight gain and (F: 315.9 mg/kg/day) in 

females based on decreased body weight gain. 

870.7485

(83-6)

Metabolism 42139433 (1990)/ 

Acceptable/Guideline

5 or 250 mg/kg single dose or 

5 mg/kg/day repeated doses

Absorption was rapid, incomplete and similar in both 

sexes. Elimination was mostly by urine and feces 

within 72 hours, appearing to be independent of dose 

and sex. Desmethyl NC-319 and the 5-hydroxy 

derivative were the major urinary and fecal metabolites.

870.7800(

83-6)

Immunotoxicity This requirement of this study was waived (TX: 0056723; 08/06/2013)

870.5100 

(84-2 a) 

Mutagenic - Ames

Salmonella

typhimurium and 

E. Coli.

42139428 (1991)/ Acceptable 

(+/-S9) 5 strains S. typh. 

Conc.: 1 - 10000 μg/plate; E. 

Coli WpuvrA Conc.: 333 -

10000 μg/plate

Negative. Concentrations => 5000 microgm/plate found 

to be insoluble and/or cytotoxic.

870.5100 

(84-2 a) 

Mutagenic - Gene 

Mutation

43616302 (1995)/ Acceptable 

(+/-S9) 5 strains S. typh. 

Conc.: 50 - 5000 μg/plate

Negative. Conducted with 3-chlorosulfonamide acid-the 

principal soil metabolite of halosulfuron-methyl.

870.5300 

(84-2)

Mutagenic - Gene 

Mutation -

Hamster (Chinese)

43616303 (1995) - Metabolite/

Acceptable 

(+/-S9) Conc.: 350-3100 

μg/mL

Negative. Conducted with 3-chlorosulfonamide acid-the 

principal soil metabolite of halosulfuron-methyl.

870.5300 

(84-2)

Mutagenic -

(HGPRT) -

Hamster 

(Chinese).

42139431 (1991) - Metabolite/

Unacceptable 

Conc.: 100-1000 μg/mL

Conclusions indefinite due to partly to relatively high 

negative and low positive control values, solubility 

problems with test article.

870.5300 

(84-2)

Mutagenic -

(HGPRT) -

Hamster 

(Chinese).

42661420 (1993)/ Acceptable 

(+/-S9) Conc.: 50-900 μg/mL 

Negative. Did not induce forward mutations at the 

HGPRT locus in Chinese Hamster ovary cells. 

Concentrations above 700 ug/mL were insoluble.

870.5375 

(84-2)

Mutagenic - In 

vitro Clastogenic -

Hamster (Chinese)

42139429 (1989)/ Acceptable 

(+/-S9) Conc.: 449-1810 

μg//mL

Negative. No chromosomal aberrations.
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

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Table 2. Toxicity Profile of Halosulfuron-Methyl Technical.

Guideline 

No.

Study Type MRID No. 

(Date)/Classification/ Doses

Results

870.5395 

(84-2)

Mutagenic -

Micronucleus 

Assay - Mouse 

(CD-1)

43616304 (1995) -

Metabolite/Acceptable

Doses: 1250, 2500 or 5000 

mg/kg

Negative. Conducted with 3-chlorosulfonamide acidthe principal soil metabolite of halosulfuron-methyl. No 

overt toxicity for the treated animals or cytotoxicity for 

the target organ (bone marrow cells) was observed.

870.5395 

(84-2)

Mutagenic -

Micronucleus 

Assay - Mouse

42139430 (1989)/ Acceptable 

Doses: 500, 1667 0r 5000 

mg/kg.

Negative. Did not induce significant elevations in the 

frequencies of micronucleated polychromatic 

erythrocytes.

870.5500 

(84-2)

Mutagenic -

Unscheduled DNA 

synthesis - Rat

42139432 (1990)/ Acceptable

(+/-S9) Conc.: 25-1000 μg/mL

Negative. Fail to induce unscheduled DNA synthesis in 

primary rat hepatocytes. 
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

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Appendix B: Sulfonylureas: comparative physical chemical properties and percent dermal absorption 

(Data excerpted from a DuPont submission, MRID 48904001)

# NAME

CAS 

NUMBER

MOLECULA

R WEIGHT

LOG

Kow

(PH 7)

PKA

% DERMAL 

ABSORPTION

STUDY

DESIGN

REFERENCEI COMMENTS

CONCENTRATE DILUTE

1

Bensulfuronmethyl 83055-99-6 410.4 0.79 5.2 4.7 1.7 In vivo, rat DuPont HLR 120-90

2 Foramsulfuron

173159-57-

4

452.5 -0.78 4.6 - <2 In vivo,

rat

European Commission 

Foramsulfuron, 

SANCOI10324/2002 final,

29 November 2002

3 Mesosulfuron 400852-66-6 503.6 -0.48 4.35 9 14 In vitro

European Commission; 

Mesosulfuron, 

SANC0/10298/2003-final, 

23 June 2003

4a Nicosulfuron 111991-09-

04 410.4 -1.74 4.3 0.021 1.05

In vitro,

Human

skin

DuPont-21540

4b Nicosulfuron " " " " 0.23 0.41

In

vitro, 

Huma

n skin

DuPont-25519
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

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# NAME

CAS 

NUMBER

MOLECULA

R WEIGHT

LOG

Kow

(PH 7)

PKA

% DERMAL 

ABSORPTION

STUDY

DESIGN

REFERENCEI COMMENTS

CONCENTRATE DILUTE

5 Oxasulfuron 144651-06-

9

406.4 -0.81 5.1 1 1

In vitro

Rat &

Human

skin; In

vivo

Rat

European Commission; 

Oxasulfuron,

SANC0/4323/2002- final, 26

November 2002

6

Primisulfuron 

methyl 86209-51-0 468.3

1.15

(pH 

5.0)

3.47 - 21 In vivo,

rat

Pest Management Regulatory

Agency (PMRA); Proposed Reg 

Decision Document: 

PRDD2001-

02; Primisulfuron Methyl,

March

29, 2001; includes skin

residues

7a Rimsulfuron 122931-48-

0

431.4 -1.46 4 0.24 3.21

In vitro,

Human

skin

DuPont-24335

7b Rimsulfuron " " " " 0.4 1.63

In vitro,

Human

skin

DuPont-25519
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

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# NAME

CAS 

NUMBER

MOLECULA

R WEIGHT

LOG

Kow

(PH 7)

PKA

% DERMAL 

ABSORPTION

STUDY

DESIGN

REFERENCEI COMMENTS

CONCENTRATE DILUTE

7c Rimsulfuron " " " " 0.18 2.45

In vitro,

Human

skin

Dupont-24600

8a Thifensulfuron 

methyl

79277-27-

3

387.4 -1.66 4 0.19 2.29

In vitro,

Human

skin

DuPont-24600

8b Thifensulfuron 

methyl " " " " 0.15 2.51

In vitro,

Human

skin

DuPont-29190

9 Triasulfuron

82097-50-

5

401.8 -0.59 4.

64 - 1

No

details

provided

European Commission;

Triasulfuron, SANC0/7589NI/97-

final, 30 November 2000

10 Tribenuron 

methyl

101200-

48-00

395.4 0.78 4.

7

3.1 17.7

In vivo,

rat;

10-hour 

data

DuPont report AMR-1096-

88;

includes skin residues
Halosulfuron-Methyl Human Health Risk Assessment DP No. D421819

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# NAME

CAS 

NUMBER

MOLECULA

R WEIGHT

LOG

Kow

(PH 7)

PKA

% DERMAL 

ABSORPTION

STUDY

DESIGN

REFERENCEI COMMENTS

CONCENTRATE DILUTE

11a

Triflusulfuron 

methyl

126535-

15-7

492.4 0.96 4.

4

0.01 10.5

In vitro,

Human

skin

DuPont-12132

11b

Triflusulfuron 

methyl " " " " - 3.24

In vitro,

Human

skin

DuPont-20077

12 Tritosulfuron

142469-

14-5

445.3 0.62 4.

69 1 2

In vitro

Rat &

Human

skin; In

vivo Rat

European Commission;

Tritosulfuron, SANC0/1256/08-

rev.1, 4 March 2008

Halosulfuronmethyl 100784-20-1 0.0186 3.

5

Test substances include undiluted formulation or concentrate and diluted concentrate.
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Appendix C. Physical/Chemical Properties

TABLE C.1. Physicochemical Properties of Halosulfuron-methyl. 

Parameter Value Reference

Melting point/range 175.5-177.2oC MRID #42139403 

(D173627; G.J. Herndon; 

30 July 1992)

pH 4.11 at 25oC (1% w/v slurry)

Density 1.618 g/mL at 25oC

Water solubility at 20oC pH 5 0.015 g/L

pH 7 1.65 g/L

pH 9 7.47 g/L

Solvent solubility at 20oC methanol 1.616 g/L

n-hexane 0.01278 g/L

Vapor pressure <1 x 10-7 mm Hg at 25oC

Dissociation constant, Ka 3.61 x 10-4at 22.4oC

Octanol/water partition coefficient, 

Log(KOW) at 23oC

1.67 at pH 5

-0.0186 at pH 7

-0.542 at pH 9

UV/visible absorption spectrum Not available.
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Appendix D. International Residue Limit

Halosulfuron-methyl (PC Code 128721)

Summary of US and International Tolerances and Maximum Residue Limits

Residue Definition:

US Canada Mexico1 Codex

40 CFR §180.479

(a)General. (2) Halosulfuron-methyl 

(methyl 5-[(4,6-dimethoxy-2-

pyrimidiny)amino]

carbonylaminosulfonyl]-3-chloro-1-

methyl-1H-pyrazole-4-carboxylate)

Methyl 3-chloro-5-[[[[(4,6-

dimethoxy-2-

pyrimidinyl)amino]carbonyl]

amino]sulfonyl]-1-methyl1H-pyrazole-4-carboxylate

None

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

US Canada Mexico1 Codex

Fruit, pome, group 11-10 0.05 0.05 apples

Small vine climbing fruit, 

except fuzzy kiwifruit, 

subgroup 13-07F

0.05

Completed: M. Negussie; 04/10/2015

1

Includes only commodities of interest for this action. Tolerance values should be the HED recommendations and 

not those proposed by the applicant.

2 Mexico adopts US tolerances and/or Codex MRLs for its export purposes.
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Appendix E. 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, which include Pesticide 

Handlers Exposure Database Version 1.1 (PHED 1.1); the Agricultural Handler Exposure Task 

Force (AHETF) database; the Residential SOPs (Lawns & Turf), and other registrant-submitted 

exposure monitoring studies (MRID 44339801), are (1) subject to ethics review pursuant to 40 

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

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

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

found at the Agency website3. 

 

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

http://www.epa.gov/pesticides/science/post-app-exposure-data.html
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Appendix F. TTR and DFR Waiver Summary 

Turf Transferable Residue (TTR): In accordance with 40 CFR158, 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 halosulfuronmethyl, EPA would use the default value of 1%. Although there may be a small degree of

uncertainty in the use of the default TTR value for halosulfuron-methyl (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 would

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 postapplication activities performed in the turf transfer coefficient study day after day (e.g., 

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

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

children spend outdoors and not specifically engaged in activities on turf, when in actuality 

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

occur every day.

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

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

exposure is not being underestimated. 

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

halosulfuron-methyl is minimal in comparison to the level of concern (i.e., the calculated MOE 

is greater than 10 times higher than the level of concern, MOE = 24,000 compared to the LOC of 

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

chemical-specific TTR data would be needed to further refine exposure assessments or would 
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add appreciably to our general understanding of the availability of turf transferable pesticide 

residues.

Dislodgeable Foliar Residue (DFR): In accordance with 40 CFR158, 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 halosulfuron-methyl, EPA would use the default value of 25%. Although there may be a 

small degree of uncertainty in the use of the default DFR value for halosulfuron-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 would 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. 

There is no hazard identified for halosulfuron-methyl via the dermal route of exposure; therefore, 

a DFR study is not required at this time.