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TABLE OF CONTENTS

 Page 

I. Preliminary Work Plan (PWP) 4

II. Fact Sheet 11

III. Summary of Data Gaps 16

________________________________________

Please Note

This Preliminary Work Plan and Fact Sheet summarize the Environmental Protection 

Agency's current position based on the following documents:

1. Registration Review: Preliminary Problem Formulation for Environmental Fate and

Ecological Risk, Endangered Species and Drinking Water Assessments for Halosulfuronmethyl, March 8, 2012.

2. Halosulfuron-methyl: Human Health Assessment Scoping Document in Support of 

Registration Review, March 6, 2012.

3. Halosulfuron-methyl: Review of Human Incidents. December 8, 2011.

4. Halosulfuron-methyl Screening Level Usage Analysis (SLUA), June 3, 2011.

5. BEAD Chemical Profile for Registration Review: Halosulfuron-methyl. October 12, 

2011.

6. Appendix A: Food/Feed & Non-Food/Non-Feed Uses Considered in Registration Review 

Work Planning, August 2, 2011.

Additional supporting documents for halosulfuron-methyl may be found in the registration 

review docket EPA-HQ-OPP-2011-0745 located on the internet at www.regulations.gov.
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I. Preliminary Work Plan – Halosulfuron-methyl

Introduction:

The Food Quality Protection Act (FQPA) of 1996 mandated a registration review program. All 

pesticides sold or distributed in the United States generally must be registered by the 

Environmental Protection Agency (EPA), based on scientific data showing that they will not 

cause unreasonable risks to human health or the environment when used as directed on product 

labeling. The registration review program is intended to make sure that, as the ability to assess 

risk evolves and as policies and practices change, all registered pesticides continue to meet the 

statutory standard of no unreasonable adverse effects to human health or the environment. 

Changes in science, public policy, and pesticide use practices will occur over time. Through the 

registration review program, the Agency periodically reevaluates pesticides to make sure that as 

change occurs, products in the marketplace can be used safely. Information on this program is 

provided at: http://www.epa.gov/oppsrrd1/registration_review/.

The Agency is implementing the registration review program pursuant to Section 3(g) of the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and will review each registered 

pesticide every 15 years to determine whether it continues to meet the FIFRA standard for 

registration. The Agency will consider benefits information and data as required by FIFRA. The 

public phase of registration review begins when the initial docket is opened for each case. The 

docket is the Agency’s opportunity to state what it knows about the pesticide and what additional 

risk analyses and data or information it believes are needed to make a registration review 

decision. After reviewing and responding to comments and data received in the docket during 

this initial comment period, the Agency will develop and commit to a final work plan and 

schedule for the registration review of halosulfuron-methyl.

Halosulfuron-methyl is a sulfonylurea herbicide that is primarily absorbed through the leaves of 

plants. Sulfonylurea herbicides disrupt the synthesis of amino acids in plants by inhibiting the 

enzyme acetolactate synthase (ALS). ALS inhibition in plants adversely affects plant growth 

and reproduction. Although the sulfonylurea herbicides all act upon the same enzyme system in 

plants, that system is not present in humans or other mammals. Halosulfuron-methyl is 

registered for use on various crops including corn, cotton, nuts, rice, sorghum, soybeans, squash, 

sugarcane, and fruiting vegetables to control broadleaf weeds and annual and perennial sedges. 

In addition to the agricultural food uses, halosulfuron-methyl is also registered for use on 

turfgrass, ornamentals, and a variety of non-crop areas including, but not limited to, airports, 

cemeteries, fallow non-crop areas, golf courses, landscaped areas, public recreation areas, 

residential and commercial lawns, sod and turf farms, sports fields, tennis courts, race tracks, 

fairgrounds, and rights-of-way. Halosulfuron-methyl was first registered in 1994; therefore, it 

was not subject to the reregistration requirements of FIFRA. In 1999, in conjunction with the 

establishment of new halosulfuron-methyl tolerances (64 FR 25439), EPA also completed the 

reassessment of the existing halosulfuron-methyl tolerances as required by FQPA.

Anticipated Risk Assessment and Data Needs:

The Agency anticipates requiring data to conduct a comprehensive ecological risk assessment, 

including an endangered species risk assessment, for all uses of halosulfuron-methyl. The 

Agency also anticipates requiring additional data to conduct human exposure risk assessments. 

Below is a summary of the issues relevant to the registration review of halosulfuron-methyl.
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Ecological Risk:

• The most recent ecological risk assessment for halosulfuron-methyl was completed in 

May 2010 for the registration of halosulfuron-methyl-containing pesticides on dried 

shelled peas and beans (except soybeans), succulent shelled peas and beans, apples, 

rhubarb, bushberry, fruiting vegetables, and tuberous and corm vegetables. 

• The Agency has not conducted a risk assessment that supports a complete endangered 

species determination for halosulfuron-methyl. The ecological risk assessment planned 

during registration review will allow the Agency to determine whether halosulfuronmethyl’s use has “no effect” or “may affect” federally listed threatened or endangered 

species (listed species) or their designated critical habitats. When an assessment 

concludes that a pesticide’s use “may affect” a listed species or its designated critical 

habitat, the Agency will consult with the U.S. Fish and Wildlife Service and/or National 

Marine Fisheries Service (the Services), as appropriate.

• The Agency anticipates requiring the following data for halosulfuron-methyl in order to 

conduct a complete ecological risk assessment, including an endangered species 

assessment:

• GDLN 835.4100 – Aerobic Soil Metabolism (two additional soils)

• GDLN 835.4300 – Aerobic Aquatic Metabolism (submitted study in review)

• GDLN 835.6100 (7) – Terrestrial Field Dissipation1

• GDLN 835.6200 – Aquatic Field Dissipation (including Environmental 

Chemistry Methods and Independent Laboratory Validation for Water) 2

• GDLN 850.1010 –Acute Toxicity Freshwater Invertebrates (TEP)

• GDLN 850.1075 – Acute Freshwater Fish Toxicity (TEP)

• NON-GDLN – Special Study for Non-Target Plant Reproductive Toxicity

• NON-GDLN – Enhanced Aerobic Soil Metabolism Study

• NON-GDLN – Enhanced Hydrolysis Study

• The Agency anticipates requiring an enhanced aerobic soil metabolism study during 

registration review. Limited studies on halosulfuron-methyl decline in at least 10 soils 

are expected to be needed because of discrepancies between available field and 

laboratory study results regarding halosulfuron-methyl persistence. Halosulfuron-methyl 

appears to be significantly more persistent than expected at some field sites based on the 

results of currently available aerobic soil metabolism studies. Once these studies are 

conducted in at least 10 soils, the Agency anticipates requiring registrants to conduct full 

aerobic soil metabolism studies (i.e., with characterization of the formation and decline of 

major degradates) on the two soils where halosulfuron-methyl is most persistent.

 1 See footnote 7 of 40 CFR 158.1300. EPA anticipates requiring only the environmental chemistry analytical 

method and independent laboratory validation portions of GDLN 835.6100 – Terrestrial Field Dissipation. 2 The Agency has classified a previously-submitted study (MRID 44437304) as supplemental, as it incompletely 

addressed the fate of halosulfuron-methyl in flooded environments. Acceptance of this study is made conditional 

upon acceptance of a submitted aerobic aquatic metabolism study (GDLN 835.4300), which is currently in review. 

In addition, environmental chemistry methods and independent laboratory validation are still required for water 

under GDLN 835.6200 per footnote 7 of 40 CFR 158.1300.
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• The Agency anticipates requiring an enhanced hydrolysis study for halosulfuron-methyl 

during registration review due to the variability in the hydrolysis rate of halosulfuronmethyl with changes in pH and temperature. Suggested parameters are expected to 

include: testing at pHs of 5, 7, and 9 and at temperatures of 10, 15, 20, and 25 C for 60 

days; testing at pHs of 4, 6, and 8 at 15 C; and analysis for halosulfuron-methyl and 

potential major hydrolysis products.

• Please refer to Registration Review: Preliminary Problem Formulation for 

Environmental Fate and Ecological Risk, Endangered Species and Drinking Water 

Assessments for Halosulfuron-methyl, March 8, 2012, located in the docket, for a detailed 

discussion of these anticipated risk assessment and data needs.

Human Health Risk:

• The most recent human health risk assessment, including a drinking water assessment, for 

halosulfuron-methyl was completed in April 2010 for the registration of use on dried 

shelled peas and beans (except soybeans), succulent shelled peas and beans, apples, 

rhubarb, bushberry, fruiting vegetables, and tuberous and corm vegetables.

 

• The Agency anticipates requiring the following data for halosulfuron-methyl in order to 

conduct a complete human health risk assessment:

• GDLN 860.1650 – Submittal of Analytical Reference Standards

• GDLN 870.7800 – Immunotoxicity

• The current uncertainty factor for halosulfuron-methyl is 100X (1X FQPA safety factor, 

10X for inter-species variation, 10X for intra-species variation). However, the 

uncertainty/safety factors will be re-evaluated for halosulfuron-methyl after the additional 

toxicology study that is expected to be required is submitted and reviewed.

• The Agency does not anticipate conducting updated dietary, residential, aggregate, or 

occupational risk assessments during registration review. The Agency plans to rely on 

the most recent comprehensive human health assessment in making its registration 

review decision, as there were no risks of concern at that time and changes in Agency 

models and policies that have occurred since that assessment are not expected to alter risk 

conclusions. If the results of the additional toxicity study that is expected to be required 

changes assessment endpoints or uncertainly/safety factors, the Agency will reconsider 

the need for updated risk assessments. 

• The Agency anticipates updating the current halosulfuron-methyl tolerance expression in 

40 CFR §180.479 to be consistent with the Chemical Abstracts Service (CAS) 

nomenclature or the International Union of Pure and Applied Chemistry (IUPAC) 

nomenclature. 

• For more information please refer to Halosulfuron-methyl. Human Health Assessment 

Scoping Document in Support of Registration Review, March 6, 2012, located in the 

docket.
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Endocrine Disruptor Screening Program

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

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

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

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

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

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

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

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

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

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

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

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

Screening Program (EDSP). 

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

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

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 

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

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

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

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

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

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

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

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

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between 

October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 

chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. Halosulfuronmethyl is not among the group of 58 pesticide active ingredients on the initial list to be screened 

under the EDSP. Accordingly, as part of registration review, EPA will issue future EDSP 

orders/data call-ins, requiring the submission of EDSP screening assays for halosulfuron-methyl. 

For further information on the status of the EDSP, the policies and procedures, the list of 67 

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

website: http://www.epa.gov/endo/.
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Timeline:

EPA has created the following estimated timeline for the completion of the halosulfuron-methyl

registration review.

Registration Review for Halosulfuron-methyl – Projected Registration Review Timeline

Activities Estimated Date

Opening the Docket

Open Docket and Public Comment Period 2012 – March

Close Public Comment 2012 – May

Case Development

Final Work Plan 2012 – August

Issue DCI 2013 – April – June

Data Submission 2017 – April – June

Open Public Comment Period for Draft Risk Assessments 2018 – Oct. – Dec.

Close Public Comment Period 2019 – Jan. – March

Registration Review Decision

Open Public Comment Period for Proposed Registration Review 

Decision 

2019 – April – June

Close Public Comment Period 2019 – July – Sept.

Registration Review Decision and Begin Post-Decision Follow-up 2020

Total (years) 8

Guidance for Commenters:

The public is invited to comment on EPA’s preliminary work plan and rationale. The Agency 

will carefully consider all comments as well as any additional information or data provided in a 

timely manner prior to issuing a Final Work Plan for halosulfuron-methyl.

Trade Irritants:

Through the registration review process, the Agency intends to solicit information on trade

irritants and, to the extent feasible, take steps toward facilitating irritant resolution. Growers and 

other stakeholders are asked to comment on any trade irritant issues resulting from lack of MRLs 

or disparities between U.S. tolerances and MRLs in key export markets, providing as much 

specificity as possible regarding the nature of the concern.

Water Quality:

Halosulfuron-methyl is not identified as a cause of impairment for any water bodies listed as 

impaired under section 303(d) of the Clean Water Act3. In addition, no Total Maximum Daily 

Loads (TMDL) have been developed for halosulfuron-methyl4

. More information on impaired 

water bodies and TMDLs can be found at the Agency’s website5

 3

. The Agency invites submission 

of water quality data for this pesticide. To the extent possible, data should conform to the quality 

standards in Appendix A of the OPP Standard Operating Procedure: Inclusion of Impaired 

Water Body and Other Water Quality Data in OPP’s Registration Review Risk Assessment and 

http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885

4 http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant_group_name=PESTICIDES 5 http://www.epa.gov/owow/tmdl/
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Management Process6

 

in order to ensure they can be used quantitatively or qualitatively in 

pesticide risk assessments.

Environmental Justice:

EPA seeks to achieve environmental justice, the fair treatment and meaningful involvement of all 

people, regardless of race, color, national origin, or income, in the development, implementation, 

and enforcement of environmental laws, regulations, and policies. To help address potential 

environmental justice issues, the Agency seeks information on any groups or segments of the 

population who, as a result of their location, cultural practices, or other factors, may have 

atypical, unusually high exposure to halosulfuron-methyl, compared to the general population.

Please comment if you are aware of any sub-populations that may have atypical, unusually high 

exposure compared to the general population.

Additional Information:

Stakeholders are also specifically asked to provide information and data that will assist the 

Agency in refining its risk assessments, including any species-specific ecological effects 

determinations. The Agency is interested in receiving the following information:

1. confirmation on the following label information

a. sites of application

b. formulations

c. application methods and equipment

d. maximum application rates in units related to mass per unit area of treatment 

zone

e. frequency of application, application intervals and maximum number of 

applications per season

f. geographic limitations on use

2. use or potential use distribution (e.g., acreage and geographical distribution of 

relevant crops)

3. use history

4. median and 90th

5. application timing (date of first application and application intervals) by crop –

national, state and county

percentile reported use rates (lbs. a.i./acre) from usage data –

national, state, and county

6. sub-county crop location data

7. directly acquired county-level usage data (not derived from state level data)

a. maximum reported use rate (lbs. a.i./acre) from usage data – county

b. percent crop treated – county

c. median and 90th

d. total pounds per year – county

percentile number of applications – county

e. the year the pesticide was last used in the county/sub-county area

f. the years in which the pesticide was applied in the county/sub-county area

8. typical interval (days)

9. state or local use restrictions

10. ecological incidents (non-target plant damage and avian, fish, reptilian, amphibian 

and mammalian mortalities) not already reported to the Agency

11. monitoring data

 6 http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm
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12. data regarding the use of halosulfuron-methyl on airports, outdoor non-agricultural 

areas, fallow non-crop areas, farm storage areas, tank farms, 

industrial/commercial/recreational areas, race tracks, fencerows, rights-of-way, 

roadsides, schools, and tennis courts. 

Next Steps:

After the 60-day comment period closes, the Agency will review and respond to any comments 

received in a timely manner, and expects to issue a Final Work Plan for halosulfuron-methyl.
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II. FACT SHEET

Background Information:

• Halosulfuron-methyl registration review case number: 7233

• Halosulfuron-methyl PC code: 128721.

• The first halosulfuron-methyl-containing pesticide was registered in the U.S. in 1994;

therefore, it was not subject to the reregistration process under FIFRA.

• Existing halosulfuron-methyl tolerances were reassessed in 1999 in conjunction with the 

establishment of new halosulfuron-methyl tolerances (64 FR 25439).

• There are currently 25 FIFRA Section 3 registrations for halosulfuron-methyl.

• Technical registrants for halosulfuron-methyl include: Aceto Agricultural Chemicals 

Corp. and Canyon Group, LLC.

• Tolerances for residues of halosulfuron-methyl in/on raw agricultural commodities exist 

under 40 CFR §180.479.

• Pesticide Re-evaluation Division (PRD) Chemical Review Manager (CRM): Kaitlin 

Keller, keller.kaitlin@epa.gov 

• Registration Division (RD) Product Manager (PM): Kable Bo Davis, 

davis.kable@epa.gov

Use & Usage Information: For additional details, please refer to Appendix A: Food/Feed & 

Non-Food/Non-Feed Uses Considered in Registration Review Work Planning, August 2, 2011;

Halosulfuron-methyl Screening Level Usage Analysis (SLUA), June 3, 2011; and BEAD 

Chemical Profile for Registration Review: Halosulfuron-methyl (PC Code:128887 October 12, 

2011).

• Halosulfuron-methyl is registered for use on various crops including corn, cotton, nuts, 

rice, sorghum, soybeans, squash, sugarcane, and fruiting vegetables to control broadleaf 

weeds and annual and perennial sedges. In addition to the agricultural food uses, 

halosulfuron-methyl is also registered for use on turfgrass, ornamentals, and a variety of 

non-crop areas including, but not limited to, airports, cemeteries, fallow non-crop areas, 

golf courses, landscaped areas, public recreation areas, residential and commercial lawns, 

sod and turf farms, sports fields, tennis courts, race tracks, fairgrounds, and rights-ofway. 

• According to the most recent usage data, approximately 30,000 pounds of halosulfuronmethyl active ingredient (a.i.) are applied per year to approximately one million acres for 

agricultural purposes. Rice, corn, sugarcane, and green beans account for the highest 

agricultural usage (in pounds) of halosulfuron-methyl. On average, the states with the 

most agricultural usage in terms of pounds a.i. applied are Arkansas, Louisiana, Texas, 

Florida, and Wisconsin. The majority of non-agricultural usage is on turfgrass at golf 

courses, turf farms, and lawns. Approximately 1,000 pounds a.i. is used on golf courses 

and 1,000 pounds a.i. is used on turf farms annually. Additionally, lawn care operators 

use approximately 500 pounds a.i. per year. 

• Halosulfuron-methyl is formulated as water dispersible granules and emulsifiable, 

flowable, and soluble concentrates. End-use product concentrations range from 0.32 –

75.0 percent a.i.
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• Application methods include aircraft, ground, soil in-furrow, soil surface, and spot

treatments as well as backpack, handheld, band, and hooded sprayers. 

Recent Actions:

• During the development of the Preliminary Work Plan for halosulfuron-methyl, the 

Agency identified an erroneous single application rate of 0.47 lb a.i lb/ acre for field corn 

on EPA Reg. No. 81880-20. After contacting the registrant about this label error, the 

registrant requested voluntary cancellation of EPA Reg. No 81880-20 on February 28, 

2012. The Agency will process this cancellation request by publishing a notice in the 

Federal Register and taking the other steps required by FIFRA Section 6(f) relating to 

voluntary cancellations.

• On December 8, 2011, tolerances were proposed for halosulfuron-methyl and its 

metabolites and degradates in or on millet, proso, forage; millet, proso, hay; millet, proso, 

grain; millet, proso, straw; grass forage, fodder, and hay, crop group 17, forage; and grass 

forage, fodder, and hay, crop group 17, hay (76 FR 76674). The Agency is currently 

conducting dietary and occupational risk assessments in 2012 to support the proposed 

uses of halosulfuron-methyl on millet and grass forage, fodder, and hay.

• A final rule for halosulfuron-methyl was issued on August 4, 2010 (75 FR 46847), which 

established tolerances for residues of halosulfuron-methyl, including its metabolites and 

degradates, in or on apple; bushberry, subgroup 13-07B; okra; pea and bean, succulent 

shelled, subgroup 6B; rhubarb; vegetable, tuberous and corm, subgroup 1C; and removed

an existing tolerance for residues for halosulfuron-methyl and its metabolites and 

degradates in or on bean, snap, succulent as it was superseded by the new tolerance on 

pea and bean, succulent shelled, subgroup 6B. 

Ecological Risk Assessment Status:

The following are key findings of the most recent ecological risk assessments for halosulfuronmethyl. Please refer to Registration Review – Preliminary Problem Formulation for the 

Environmental Fate, Ecological Risk, and Endangered Species and Drinking Water Assessments 

for Halosulfuron-methyl, March 8, 2012, located in the docket, for a detailed discussion of the 

ecological risk assessments.

• The most recent ecological risk assessment for halosulfuron-methyl was completed in 

May 2010 in support of the registration for use on dried shelled peas and beans (except 

soybeans), succulent shelled peas and beans, apples, rhubarb, bushberry, fruiting 

vegetables, and tuberous and corm vegetables. 

• The Agency concluded that acute and chronic risk estimates for birds, mammals, 

freshwater fish, aquatic invertebrates, and estuarine/marine invertebrates did not exceed 

the Agency’s Level of Concern (LOC) for ecological effects. 

• In the 2010 ecological risk assessment, the Agency concluded that the LOCs were 

exceeded for aquatic and terrestrial plants (listed species and non-listed species) from 

both the aerial and ground application of halosulfuron-methyl.
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Human Health Risk Assessment Status:

The following are key findings of the most recent human health risk assessments for 

halosulfuron-methyl. Please refer to Halosulfuron-methyl: Human Health Assessment Scoping 

Document in Support of Registration Review, March 6, 2012 located in the docket, for a detailed 

discussion of the human health risk assessment.

The most recent human health risk assessment for halosulfuron-methyl was completed in April 

2010 in support of the registration for use on dried shelled peas and beans (except soybeans), 

succulent shelled peas and beans, apples, rhubarb, bushberry, fruiting vegetables, and tuberous 

and corm vegetables.

Hazard Characterization:

• The herbicidal activity of halosulfuron-methyl, as with all sulfonylureas, is due to the 

inhibition of acetolactate synthase (ALS), an enzyme found only in plants and bacteria. 

This enzyme is part of the biosynthesis pathway leading to the formation of branched 

chain amino acids (e.g., isoleucine, leucine, and valine), which are required for growth. 

Animals lack ALS and this biosynthetic pathway, contributing to the relatively low 

toxicity of sulfonylurea herbicides in animals.

• Halosulfuron-methyl has low acute toxicity via the oral, inhalation, and dermal routes of 

exposure. It is not a dermal or eye irritant or skin sensitizer. 

• The Agency reduced the 10x FQPA Safety Factor to 1x in its most recent risk 

assessment. Although the data indicated an increase in qualitative susceptibility in 

fetuses following prenatal exposure in rats and rabbits, the developmental effects were 

seen in the presence of maternal effects and clear No Observed Adverse Effect Levels 

(NOAELs) and Lowest Observed Adverse Effect Levels (LOAELs) were established for 

both maternal and developmental effects. In addition, the developmental effects in rats 

were seen at doses approaching the limit dose (1000 mg/kg). The Agency concluded that 

the degree of concern was low and there was no residual uncertainty in either the rat or 

rabbit developmental toxicity study. In addition to a lack of residual concerns for 

susceptibility, there was no evidence of neurotoxicity, and exposures were not considered 

to be underestimated.

• Halosulfuron-methyl has been classified as “not likely to be carcinogenic to humans” 

because carcinogenicity studies in rats and mice showed no increase in the incidence of 

treatment-related tumors. The results of acute and subchronic neurotoxicity studies show 

no neurotoxic effects. Genotoxicity studies did not demonstrate any evidence of 

mutagenic potential for halosulfuron-methyl.

Dietary:

• Acute and chronic dietary (food and water) risk assessments were conducted for the 

general U.S. population and various population subgroups, with the major emphasis 

placed on the exposure estimates for infants and children. For all supported registered 

commodities, acute and chronic dietary exposure to halosulfuron-methyl did not exceed 

the Agency’s LOC for the general population and vulnerable population subgroups. 
14

Residential:

• In the 2010 risk assessment, short- and intermediate-term dermal and inhalation 

residential handler risk estimates for all residential handler exposure scenarios were 

below the Agency’s target LOC. Based on the use pattern of halosulfuron-methyl, longterm residential exposures were not expected and, therefore, not assessed. 

• For residential post-application exposure scenarios, all risk estimates were below the 

Agency’s LOC. Post-application exposure risk estimates from lawn treatment were 

assessed for adults’ and children’s post-application dermal exposure, children’s incidental 

ingestion of pesticide residues on lawns from hand-to-mouth exposure, children’s objectto-mouth transfer from mouthing of pesticide-treated turfgrass, and children’s incidental 

ingestion of soil from pesticide-treated residential areas.

Aggregate:

• Acute, short-, and intermediate-term aggregate risk assessments were conducted as part 

of the 2010 human health risk assessment. A cancer aggregate risk assessment was not 

performed because halosulfuron-methyl has not been shown to be carcinogenic. All 

aggregate risk estimates were below the Agency’s LOC.

Occupational:

• Short- and intermediate-term occupational handler scenarios resulted in exposures below 

the Agency’s LOC with the use of baseline clothing (i.e., long-sleeved shirt, pants, socks, 

and shoes). Post-application scenarios also resulted in dermal exposure below the 

Agency’s LOC at a restricted-entry interval of 12 hours. 

• Based on Agency standards and policies at the time of the assessment, a quantitative 

post-application inhalation exposure assessment was not performed for halosulfuronmethyl.

 

Human Studies:

• Past halosulfuron-methyl risk assessments rely in part on data from studies in which adult

human subjects were intentionally exposed to a pesticide to determine their dermal and

inhalation exposure. Many such studies, involving exposure to many different pesticides,

comprise generic pesticide exposure databases such as the Pesticide Handlers Exposure

Database (PHED) and the Agricultural Reentry Task Force (ARTF) Database. EPA has

reviewed all the studies supporting these multi-pesticide generic exposure databases, and

has found no clear and convincing evidence that the conduct of any of them was either

fundamentally unethical or significantly deficient relative to the ethical standards

prevailing at the time the research was conducted. All applicable requirements of EPA’s 

Rule for the Protection of Human Subjects of Research (40 CPR Part 26) have been 

satisfied, and there is no regulatory barrier to continued reliance on these studies.
15

Cumulative:

• The Agency has not determined whether halosulfuron-methyl shares a common 

mechanism of toxicity with other chemical substances. If, in the future, the Agency 

determines that new information on halosulfuron-methyl is available that could 

potentially impact a cumulative risk assessment, the Agency will revisit the need for one. 

Incidents:

• The Office of Pesticide Programs (OPP) Incident Data System (IDS) was consulted for 

reports of halosulfuron-methyl incidents. From 2006 to November 2, 2011, fourteen

cases were reported for halosulfuron-methyl. Because the cases fall within the categories 

reported as minor, unknown, or no effects, there is no unique report that provides details 

about the incidents, and single chemical incidents are not distinguished from multiple 

chemical incidents. Based on the low severity of incident cases that occurred, there does 

not appear to be a concern at this time that would warrant further investigation.

• A preliminary review was made on September 6, 2011 of the Ecological Incident 

Information System (EIIS), which is maintained by OPP, and the Avian Monitoring 

Information System (AIMS), which is maintained by the American Bird Conservancy. 

No incidents involving halosulfuron-methyl were found in EIIS or the AIMS database. 

Tolerances and International Harmonization: 

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

and degradates, under 40 CFR §180.479(a)(2). Compliance with tolerances levels is 

determined by measuring halosulfuron-methyl, methyl 5-[(4,6-dimethoxy-2-

pyrimidinyl)amino]carbonylaminosulfonyl]-3-chloro-1-methyl-1H-pyrazole-4-

carboxylate

• The Agency anticipates updating the current halosulfuron-methyl tolerance expression in 

40 CFR §180.479 to be consistent with the Chemical Abstracts Service (CAS) 

nomenclature (methyl 3-chloro-5-[[[[(4,6-dimethoxy-2-

pyrimidinyl)amino]carbonyl]amino]sulfonyl]-1-methyl-1H-pyrazole-4-carboxylate) or 

the International Union of Pure and Applied Chemistry (IUPAC) nomenclature (methyl 

3-chloro-5-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)-1-methylpyrazole-4-

carboxylate).

Data Call-In Status

• No data call-ins have been issued for halosulfuron-methyl.

Labels:

• Halosulfuron-methyl Section 3 product labels can be obtained from the Pesticide Product 

Label System (PPLS) website: http://oaspub.epa.gov/pestlabl/ppls.hom
16

III. Summary of Anticipated Data Requirements – Halosulfuron-methyl

1. The table below summarizes all anticipated data needs for halosulfuron-methyl in Section 

I, of this document (Preliminary Work Plan), the Registration Review: Preliminary 

Problem Formulation for the Environmental Fate and Ecological Risk, Endangered 

Species and Drinking Water Assessments for Halosulfuron-methyl, March 8, 2012,

and the Halosulfuron-methyl: Human Health Assessment Scoping Document in Support 

of Registration Review, March 6, 2012.

Guideline 

Number Anticipated Data Requirement Test 

Material

Study 

Duration

835.4100 Aerobic Soil Metabolism (two soils) TGAI 24

835.4300 Aerobic Aquatic Metabolism TGAI 24

835.6100 Terrestrial Field Dissipation1 TGAI 12

835.6200 Aquatic Field Dissipation2 TEP 24

850.1010 Acute Toxicity Freshwater Invertebrates TEP 24

850.1075 Acute Freshwater Fish Toxicity TEP 12

860.1650 Submittal of Analytical Reference Standards3

PAI;

residue of 

concern

24

870.7800 Immunotoxicity TGAI 12

NONGDLN Enhanced Aerobic Soil Metabolism Study4 TGAI 48

NONGDLN Enhanced Hydrolysis Study5 TGAI 12

NONGDLNSpecial Study for Non-Target Plant Reproductive 

Toxicity4 TEP 24

 1 See footnote 7 of 40 CFR 158.1300. EPA anticipates requiring only the environmental chemistry analytical method and 

independent laboratory validation portions of GDLN 835.6100 – Terrestrial Field Dissipation. 2 That Agency has classified a previously-submitted study (MRID 44437304) as supplemental, as it incompletely addressed the 

fate of halosulfuron-methyl in flooded environments. Acceptance of this study is made conditional upon acceptance of a 

submitted aerobic aquatic metabolism study (GDLN 835.4300), which is currently in review. In addition, environmental 

chemistry methods and independent laboratory validation are still required for water under GDLN 835.6200 per footnote 7 of 40

CFR 158.1300. 3 Analytical reference standards are available for halosulfuron-methyl and the 3-CSA (3-chlorosulfonamide acid) metabolite but 

not for the rearrangement ester (RRE) of halosulfuron-methyl. An analytical reference standard for the RRE of halosulfuronmethyl is expected to be required to be submitted to the EPA National Pesticide Standards Repository. 4 The anticipated DCI will require a protocol be submitted within 90 days of receipt of the DCI for review and approval by the 

Agency prior to initiation of this study.

5 The anticipated DCI will require the protocol for GDLN 835.2120 – hydrolysis be followed. Suggested parameters include 

testing at pHs of 5, 7, and 9 and at temperatures of 10, 15, 20, and 25 C for 60 days (and additionally pH 4, 6, and 8 at 15 C), and 

analysis for halosulfuron-methyl and potential major hydrolysis products.