UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

MEMORANDUM 

Date: September 5, 2013 

SUBJECT: Bensulfuron-methyi-Immunotoxicity Study (870.7800) and 2l/28 Day Dennal 

Toxicity Study (870.3200) Waiver Decisions 

PC Code: 128820 DP Barcode: D412016, D412018 

Decision No.: 479080, 479082 

Petition No.: NA 

Registration No.: 71085-33, 71085-34, 71085-35 

Regulatory Action: NA 

Risk Assessment Type: NA Case No.: NA 

TXR No.: 0056778 

MRIDNo.:NA 

CAS No.: 83055-99-6 

40 CFR: §180.445 

FROM: Minerva Mercado, Toxicologist --=;.-.-,.-/ 

Risk Assessment Branch 3 _:is;4;.,-"'f-£-- - - Health Effects Division (7509P) 

THROUGH: Christine Olinger, Branch Chi~f f / 

Risk Assessment Branch 3 f- ~ 

Health Effects Division (7509 

TO: Jill Bloom, Risk Manager Reviewer 

Risk Management and Implementation Branch 5 

Registration Division (7505P) 

I. CONCLUSIONS 

• 

Ver.Apr. 2010 

The Health Effects Division (HED) Hazard and Science Policy Council (HASPOC) concluded 

that the above mentioned studies are not required for bensulfuron-methyl. These decisions are 

documented in the attached memos (K. Rury 8/6/2013, TXR 0056723; K Rury 8/26/2013, TXR 

0056721). 

II. ACTION REQUESTED 

The Registration Division (RD) requested that HED review waiver requests for the 2l/28 day 

dermal toxicity and immunotoxicity studies required for registration review and advice as to 

whether the data requirement could be waived. 

Page l of 1 
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTO~, D.C. 20460 

MEMORANDUM 

Date: August 26,2013 

OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

SUBJECT: Bensulfuron-methyl: Swnmary of Ha:7m:d Wid Science Policy Council 

(HASPOC) Meeting on July 18, 2013: Recommendations on the Requirement of 

a2l/28-Day Dermal Toxicity Study. 

PC Code: 128820 

DMi!lion No.: N/A 

Pdftion No.: N/A 

RiskABB~:Ssment Type: N/A 

TXR No.: 0056721 

MRID No.: Nl A 

DP DllToode: N/ A 

Registrooon No.: Nl A 

Regulatory Action: Registration Review 3 

Case No.: 7216-1 

CAS No.: 83055-99-6 

40 CFR: §180.445 

FROM: Kristin Rury, MPH y_Q~ Executive Secretary, HA~rocU 

--!1r J(l 

Health Effects Division (7 509P) ft!)! 

Anna Lowit, Ph.D., C<rChair, HAS OC . / JTHROUGH: Jess Rowland, Co-Chair ~ 

Health Effects Division (7509P) Vl 

TO: Sheila Healy, Ph.D. 

Christine Olinger, Branch Chief 

Risk Assessment Branch III 

Health Effects Division (7509P) 

MEETING ATTENDEES: 

HASPOC Members: Aona L<>wi~ Anwar Dunbar, Elizabeth Mendez, JeffEVlllls, Jeff Dawson, 

John Kough, Jonathan Chen, Julie Van Alstine, Kristin Rury, Michael Metzger, PV Shall, Ray 

Kent 

Presenter: Sheila Healy, Nancy Tso.ur 

Page 1 of3 
Page 2 of 3

Other Attendees: Christopher Schlosser, Christina Swartz, Jaime D’Agostino, Joey Bever, 

Jonathan Leshin, Monique Perron 

I. PURPOSE OF MEETING:

In a recent Human Health Scoping Document in support of Registration Review (D389431, 

07/06/2011), Risk Assessment Branch III (RAB III) requested a 21/28-day dermal toxicity study 

to fulfill a data requirement under 40 CFR 158.500. The Sponsor, RiceCo, L.L.C., has since 

submitted a waiver request for this data requirement. The Hazard and Science Policy Council 

(HASPOC) met on July 18, 2013 to discuss the need for a repeat-dose dermal toxicity study to 

support the registered use of bensulfuron-methyl. 

II. SUMMARY OF USE PROFILE & PREVIOUS RISK ASSESSMENT: 

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

pyrimidinyl)amino]carbonyl]amino]sulfonyl]methyl]benzoate]) is a systemic sulfonylurea 

herbicide used in pre-and post-emergence control of broadleaf weeds and sedges in rice. The 

most recent risk assessment for bensulfuron-methyl was conducted in 1997 to set tolerances on 

crayfish, rice grain, and rice straw. All registered formulations of bensulfuron methyl (dry 

flowable, granular, and emulsifiable concentrate) may be applied via ground or aerial equipment 

at a single maximum application rate of 0.064 lb ai/acre. There is potential for short- and 

intermediate-term occupational exposure to bensulfuron-methyl during handling (mixing, 

loading, applying) of formulations with ground and aerial equipment. There are no uses of 

bensulfuron-methyl that would result in residential (non-occupational) exposure. 

In the most recent risk assessment (D238880, 11/20/1997), a point of departure (POD) was not 

selected for dermal exposure scenarios; an appropriate endpoint was not identified and the 

dermal toxicity study requirement was waived based on the results of an acute dermal study 

(LD50 > 2000 mg/kg). A POD of 19.9 mg/kg/day was used for chronic dietary exposure and is 

based on liver toxicity and discoloration/ inflammation of oral mucosa observed in the chronic 

dog study at a LOAEL of 222.6 mg/kg/day. There is no concern for increased quantitative or 

qualitative susceptibility of the young following in utero (rats and rabbits) and pre-and post-natal 

exposure (rats) to bensulfuron-methyl. Additionally, there is no evidence of neurotoxicity. The 

Food Quality Protection Act (FQPA) safety factor has been reduced to 1X. The Level of 

Concern is 100. Bensulfuron-methyl is classified as not likely to be a human carcinogen. 

III. STUDY WAIVER REQUEST

a. Subchronic Dermal Study 

With respect to considering whether a subchronic dermal toxicity study with bensulfuron-methyl 

is required, the HASPOC used a WOE approach. This WOE approach considered: 

1. Use Pattern & Exposure Scenarios: Any application scenario that leads to dermal 

exposure needs to be considered in the WOE analysis for a dermal toxicology study waiver 

request. There is potential occupational exposure from mixing/loading/applying 
Page 3 of 3

bensulfuron-methyl during ground and aerial applications. Exposure is expected to be both 

short-and intermediate-term. 

2. Margins of Exposure: For the purpose of the HASPOC WOE evaluation, a screening level 

dermal exposure analysis was performed using the chronic no observed adverse effect level 

(NOAEL) of 19.9 mg/kg/day and assuming 100% dermal absorption. Estimated dermal 

MOEs ranged from 93 to 26,000. If 75% dermal absorption is assumed, MOEs range from 

120 – 34,000. The lowest MOEs represent mixing and loading for aerial application to highacreage crops. These MOE estimates are considered conservative based on the dermal 

absorption factor assumptions; and could be refined with additional information on the 

dermal absorption of sulfonylureas as a class. For example many of the sulfonylureas are 

ionized at physiological pH and dermal uptake of charged compounds is typically poor. 

With a pKa of 5.2 (D238880, 11/20/1997), bensulfuron methyl is one of those that will be 

ionized at pH 7. Dermal absorption is expected to be below 100%. 

3. Toxicological Considerations: The primary target organ of bensulfuron methyl toxicity is 

the liver. Effects in the mouse included enlarged livers, nodules and masses in the liver, and 

increased liver weight accompanied by liver enzyme perturbations and histological lesions at 

the highest dose tested (HDT ~ 450 mg/kg/day). Similar hepatotoxicity, as well as irritation 

of oral mucosa, was also observed in the chronic dog study at a lowest observed adverse 

effect level (LOAEL)/highest dose tested (HDT) of 222.6 mg/kg/day. Adaptive, but not 

adverse changes in liver histopathology were observed in the chronic rat study at 305 

mg/kg/day (HDT). Shorter-term subchronic mouse and dog studies may provide candidate 

endpoints for dermal assessment at the time of Registration Review. Similar to chronic 

studies, liver effects were seen in the subchronic toxicity studies in the mouse and dog at 

similar dose levels with NOAELs of 132 and 32 mg/kg/day, respectively. The acute dermal 

toxicity indicates that the LD50 for bensulfuron-methyl is >2000 mg/kg. There is no dermal 

penetration study on bensulfuron-methyl. .

IV. HASPOC CONCLUSIONS: 

The HASPOC concludes, based on a WOE approach, that a subchronic dermal toxicity 

study is not required for bensulfuron-methyl at this time. This approach considered all of the 

available hazard and exposure information, particularly that: (1) the low acute dermal toxicity 

(LD50 is > 2000mg/kg; Toxicity Category III) and 2) The use of an oral POD based on the most 

sensitive endpoint (liver toxicity) observed in the most sensitive species (dog) after long-term 

exposure (1-year) with a high dermal absorption (75-100%) results in acceptable MOEs (>120) 

with 75% dermal absorption, or MOEs that are close to the level of concern (MOE=93) with 

100% dermal absorption. A longer term study is used to assess short and intermediate term 

exposure scenarios with high dermal absorption. Therefore, there is high confidence that the 

Agency is not underestimating risks in the absence of this study.
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

:.:Q:.~~ ~\ WASHINGTON, D.C. 20460 

~ \:"·() ll ~~~ .•. ay ' ... f/ '<.:::.~ .::::.: ~>~ OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

MEMORANDUM 

August 6, 20 13 

SUBJECT: Sulfonylureas: Summary of Hazard and Science Policy Council (HAS PO C) 

Meeting on July 18, 2013: Recommendations on Data Requirement for 

Immunotoxicity Studies for Sulfonylurea Pesticides. 

PC Codes: See below DP Barcode: D412018 and D412408 

Decision No.: N/A Registration No.: N/A 

Petition No.: N/A Regulatory Action: N/A 

Risk Assessment Type: N/ A Case No.: N/ A 

TXR No.: 0056723 CAS No.: See below 

MRID No.: N/A 40 CFR: N/A 

FROM: Kristin Rury, MPH \"._(J--..-

Executive Secretary, HASioW 

Health Effects Division (7509P) 

THROUGH: Jess Rowl~nd, Co-Chair r ~) / 

Anna Low1t, Ph.D., Co-Chatr ~ / / j ~ 

HASPOC vt[.) D / 

Health Effects Division (7509P) · 

TO: Jaime D'Agostino, Toxicologist 

Risk Assessment Branch II 

Health Effects Division (7509P) 

MEETING ATTENDEES 

HASPOC Members: Anna Lowit, Anwar Dunbar, Elizabeth Mendez, Jeff Evans, Jeff Dawson, 

John Kough, Jonathan Chen, Julie Van Alstine, Kristin Rury, Michael Metzger, PV Shah, Ray 

Kent 

Presenter: Jaime D' Agostino 

Other Attendees: Abdallah Khasawinah, Christina Swartz Christopher Schlosser, Joey Bever, 

Monique Perron, Zaida Figueroa 

Page 1 of 10 
Page 2 of 10

1. PURPOSE OF MEETING

In accordance with the revised 2007 40 CFR Part 158 Toxicology Data Requirements, an 

immunotoxicity study is required for food and non-food use pesticides. HED has received 

immunotoxicity waiver requests from the registrants of bensulfuron methyl, orthosulfamuron and 

sulfosulfuron, however the HED Hazard and Science Policy Council (HASPOC) has decided to 

evaluate the sulfonylurea (SU) pesticides as a class due to their structural and toxicological 

similarities. The HASPOC met on July 18, 2013 to determine the need for the immunotoxicity 

study (870.7800) for the following sulfonylurea (SU) pesticides. 

Chemical PC Code CAS Number 

Bensulfuron-methyl 128820 83055-99-6 

Chlorsulfuron 118601 64902-72-3 

Ethametsulfuron 129091 97780-06-8 

Flazasulfuron 119011 104040-78-0 

Foramsulfuron 122020 173159-57-4 

Halosulfuron-methyl 128721 135397-30-7 

Mesosulfuron-methyl 122009 400852-66-6 

Metsulfuron-methyl 122010 868680-84-6 

Orthosulfamuron 108209 213464-77-8 

Primisulfuron-methyl 128973 113036-87-6 

Prosulfuron 129031 94125-34-5 

Sulfometuron-methyl 122001 74222-97-2 

Sulfosulfuron 085601 141776-32-1 

Triasulfuron 128969 82097-50-5 

Triflusulfuron-methyl 129002 126535-15-7 

II. SUMMARY OF USE PROFILE, EXPOSURE AND HAZARD CONSIDERATIONS 

a. Use Profile:

The use profile for the SU pesticides is presented in Appendix 1. 

b. Toxicity Profile: 

The SUs have low toxicity following acute exposure via oral, inhalation, and dermal routes of 

exposure (Toxicity Category III-IV). Except for ethametsulfuron (Toxicity Category II) and 

metsulfuron methyl (Toxicity Category I), there is no evidence of eye irritation. Except for 

tribenuron-methyl, the SUs are not dermal sensitizers. 

As a class, SU pesticides tend to target the liver or only cause general signs of toxicity, such as 

decreased body weight and body weight gains. Other organs where toxicity was observed 

sporadically in the databases of individual SUs include the kidney, hematopoietic system, 

thyroid, bladder, testes, thymus, and spleen. Of the SUs that did cause toxicity in organs related 

to the immune system (hematopoietic system, thymus, and spleen), an immunotoxicity study was 

conducted (iodosulfuron, rimsulfuron, trifloxysulfuron and chlorimuron ethyl) or the toxic 

effects were observed in the presence of toxicity to organs that were not related to the immune 
Page 3 of 10

system (primisulfuron and prosulfuron), such as the liver; with the exception of sulfometuron 

methyl, where the most sensitive toxic effect was hemolytic anemia. For the SUs where dermal 

studies were performed, toxicity was generally not seen following dermal exposure except 

following dermal exposure to triasulfuron, halosulfuron methyl, metsulfuron methyl, and 

tribenuron methyl. Developmental toxicity was observed for the majority of the SUs; however, 

qualitative or quantitative susceptibility was not commonly observed. When there was 

susceptibility in offspring, it was of low concern because there were clearly established no 

observed adverse effect levels (NOAELs) and the endpoints chosen for risk assessment were 

protective of the developmental effects. Effects on reproduction were rare but were observed for 

some SUs (flazasulfuron, primisulfuron, prosulfuron, triasulfuron, and tribenuron methyl). SUs 

did not show consistent evidence of neurotoxicity, except prosulfuron. None of the SUs were 

considered mutagenic and the majority of the SUs are classified as “not likely to be 

carcinogenic” or displayed no evidence of carcinogenicity. Triflusulfuron and tribenruon methyl 

were classified as possible human carcinogens, while orthosulfamuron was classified as having 

suggestive evidence of carcinogenicity. 

c. Indicators for Potential Immunotoxicity

Parameter Findings 

Hematology Indicators 

(WBC changes) 

Decreased white blood cells in dogs (halosulfuron methyl), mice (nicosulfuron), and 

rats (prosulfuron). 

Clinical Chemistry Indicators 

(A/G Ratio) Decreased A/G ratio in dogs (prosulfuron). 

Organ Weight Indicators 

(Spleen, Thymus) None. 

Histopathology Indicators 

(Spleen, Thymus, 

 Lymph nodes) 

Histological changes in bone marrow in dogs (orthosulfamuron). 

Toxicity Profile 

(Target Organs) None. 

The overall weight of evidence (WOE) suggests that these chemicals do not target the immune 

system. There were some effects on hematology, clinical chemistry, and histopathological 

alterations in immune-related tissues; but these effects generally were observed in the presence 

of toxicity in other organs and were not considered major effects. Furthermore, the majority of 

SUs did not show any evidence of immunotoxicity. 

d. Evidence for Immunotoxicity from SAR Chemicals – Retrospective Analysis. 

Acceptable guideline immunotoxicity studies have been submitted for seven SU pesticide 

chemicals. No immunotoxicity was seen following exposure to six of the seven chemicals. For 

one chemical (imazosulfuron), evidence of immunosuppression (i.e., lower anti-SRBC IgM 

concentration) was seen only at the highest dose tested (710 mg/kg/day) and in the presence of 

systemic toxicity. The NOAEL for immunotoxicity was 222 mg/kg/day and the lowest observed 

adverse effect level (LOAEL) was 710 mg/kg/day. Systemic toxicity, manifested as decreases in 
Page 4 of 10

body weight/body weight gain, and food consumption were seen at 710 mg/kg/day (LOAEL); 

the NOAEL was 222 mg/kg/day. 

For imazosulfuron, there was no impact of the immunotoxicity study to the points of departure 

(PODs) for risk assessment. The chronic reference dose (cRfD) is based on a POD of 75 

mg/kg/day which is approximately 3-fold lower than the NOAEL for immunotoxicity, and the 

POD used for assessing risks for short and intermediate-term incidental oral exposure 

(235mg/kg/day) is numerically equivalent to the immunotoxicity NOAEL (222 mg/kg/day). 

 

Chlorimuron ethyl 

MRID No. 48691101 

Immunotoxicity NOAEL 184 mg/kg/day (HDT) 

Immunotoxicity LOAEL Not Established 

Basis for LOAEL None 

Systemic toxicity NOAEL 184 mg/kg/day 

Systemic Toxicity LOAEL Not Established 

Basis for the LOAEL None 

Imazosulfuron 

MRID No. 48691004 

Immunotoxicity NOAEL 222 mg/kg/day (HDT) 

Immunotoxicity LOAEL 710 

Basis for LOAEL Decrease in anti-SRBC IgM 

Systemic toxicity NOAEL 222 mg/kg/day 

Systemic Toxicity LOAEL 710 mg/kg/day 

Basis for the LOAEL Decreases in body weight/body weight gain, and 

food consumption 

Iodosulfuron methyl-sodium 

MRID No. 48592801 

Immunotoxicity NOAEL 242 mg/kg/day (HDT) 

Immunotoxicity LOAEL Not Established 

Basis for LOAEL None 

Systemic toxicity NOAEL 73 mg/kg/day 

Systemic Toxicity LOAEL 242 mg/kg/day 

Basis for the LOAEL Decreases in body weight gain, and food 

consumption 

Rimsulfuron 

MRID No 48710305 

Immunotoxicity NOAEL 1006 mg/kg/day (HDT) 

Immunotoxicity LOAEL Not Established 

Basis for LOAEL None 

Systemic toxicity NOAEL 1006 mg/kg/day 

Systemic Toxicity LOAEL Not Established 

Basis for the LOAEL None 
Page 5 of 10

Thifensulfuron-methyl 

MRID No. 48686101 

Immunotoxicity NOAEL 529 mg/kg/day (HDT) 

Immunotoxicity LOAEL Not Established 

Basis for LOAEL None 

Systemic toxicity NOAEL 529 mg/kg/day 

Systemic Toxicity LOAEL Not Established 

Basis for the LOAEL None 

Tribenuron-methyl 

MRID No. 48641101 

Immunotoxicity NOAEL 44 mg/kg/day (HDT) 

Immunotoxicity LOAEL Not Established 

Basis for LOAEL None 

Systemic toxicity NOAEL 23 mg/kg/day 

Systemic Toxicity LOAEL 44 mg/kg/day 

Basis for the LOAEL Decreases in body weight/body weight gain, and 

food consumption 

Trifloxysulfuron sodium 

MRID No. 48857701 

Immunotoxicity NOAEL 1066.6 mg/kg/day (HDT) 

Immunotoxicity LOAEL Not Established 

Basis for LOAEL None 

Systemic toxicity NOAEL 1066.6 mg/kg/day 

Systemic Toxicity LOAEL Not Established 

Basis for the LOAEL None 

III. STUDY WAIVER REQUESTS 

A waiver is recommended for an immunotoxicity study for the SU pesticides based on the 

following considerations: 

 There was minimal evidence of immunotoxicity in the available data bases for any of the 

SU pesticides. 

 The liver, not the immune system, is generally the target organ for this chemical class, 

and hepatotoxicity or body weight changes are the primary toxicological endpoints of 

concern. 

 PODs based on the most sensitive endpoints obtained via the appropriate routes of 

exposure in the most sensitive species are currently used for dietary and non-dietary risk 

assessments for most SUs. 

 There was no evidence of immunotoxicity with six other structurally-related sulfonylurea 

herbicides, namely chlorimuron ethyl, iodosulfuron, rimsulfuron, thifensulfuron methyl, 

tribenuron methyl, and trifloxysulfuron sodium. While imazosulfuron did exhibit 
Page 6 of 10

immunotoxicity, it was observed in the presence of systemic toxicity and at a relatively 

high dose. 

All these factors indicate that an immunotoxicity study would most likely not result in an adverse 

effect that could be used as an endpoint for SU risk assessment. 

IV. HASPOC CONCLUSIONS 

The HASPOC, based on a weight of evidence approach, concludes that immunotoxicity studies 

are not required as this time for bensulfuron-methyl, chlorsulfuron, ethametsulfuron, 

flazasulfuron, foramsulfuron, halosulfuron-methyl, mesosulfuron-methyl, metsulfuron-methyl, 

orthosulfamuron, primisulfuron-methyl, prosulfuron, sulfometuron-methyl, sulfosulfuron, 

triasulfuron, and triflusulfuron-methyl. 
Page 7 of 10

Appendix 1: Use Profiles of Sulfonylurea Pesticides 

1. Bensulfuron methyl (128820): Currently registered for use on agricultural rice 

production (grain and straw) to control broadleaf weeds and sedges. Due to common 

crayfish aquaculture in flooded rice paddies, a tolerance for crayfish was established 

concomitant with the tolerance establishment for rice grain and rice straw. All registered 

formulations of bensulfuron methyl (dry flowable, granular, and emulsifiable 

concentrate) may be applied to rice via ground or aerial equipment. 

2. Chlorimuron ethyl (128901): Currently registered for use on soybeans, field corn, 

peanuts, low growing berries (subgroup 13-07H, except strawberry) and non-crop areas 

such as fence rows and roadsides. Soybean is the predominant agricultural usage. 

Chlorimuron ethyl may be applied to soybeans at pre-plant, pre-emergence, postemergence, as a band treatment, broadcast, ground spray, low volume spray, or soil 

incorporation treatment. The use on corn is pre-plant, pre-and post emergence, applied as 

a band treatment, broadcast, and burndown treatment. Chlorimuron ethyl may also be 

applied to non-crop land as a broadcast treatment. 

3. Chlorsulfuron (118601): Currently registered for use on barley, oats, wheat, fallow 

fields, and ornamental turf to control grasses and broadleaf weeds. Based on the current 

use profile, exposures can be expected to occur via the dietary (food and drinking water), 

occupational (handler and post-application), and residential (handler and postapplication) routes for chlorsulfuron. 

4. Ethametsulfuron (129091): Currently registered for a single, early postemergence 

application on canola, crambe, and rapeseed. These uses involve a broadcast foliar spray 

using ground equipment. The only relevant route of exposure is dietary, based on import 

tolerances. International registrations are limited to canola, rapeseed, crambe, mustard 

seed, and sunflower seeds. 

5. Flazasulfuron (119011): Currently registered for use on non-residential turf such as golf 

courses, sod farms, professionally managed athletic fields, commercial lawns, Christmas 

trees, and industrial vegetation management areas. Additionally, it is registered for 

agricultural use on citrus, grapes, and sugarcane. Flazasulfuron is a sulfonylurea 

herbicide used to control certain broad-leaf weeds and grasses. Although the dietary 

exposure from treated agricultural commodities is not affected by the proposed turf grass 

use, flazasulfuron may reach surface and/or groundwater and affect the drinking water 

component of the dietary exposure. Residential short-term (1 - 30 days) dermal and 

inhalation exposures are expected from flazasulfuron handler activities associated with 

the proposed residential spot treatment use. 

6. Foramsulfuron (122020): Currently registered for post-emergence use on field corn, 

sweet corn, popcorn, and also for use on golf course turf, sports fields, commercial lawns, 

cemeteries, parks, campsites, recreational areas, home lawns, roadsides, school grounds, 

and sod farms to control cool season grasses from tolerant grasses and broadleaf weeds. 

Foramsulfuron is labeled for ground and aerial application; it is not labeled for 
Page 8 of 10

application via chemigation systems. Based on the existing use patterns, dietary exposure 

through food and water is possible following application to growing crops. In addition, 

dermal and inhalation exposures are possible for both residential and occupational 

handlers. Post-application exposure is possible for those who re-enter treated areas, 

including incidental oral (hand-to-mouth) and dermal post-application exposures for 

toddlers playing on treated turf.

7. Halosulfuron Methyl (128721): Currently registered for used as a pre- and postemergent control of annual broadleaf weeds and nutsedges in several agricultural crops as 

well as residential turf grass and ornamentals. 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 property, roadsides, 

school grounds, sod or turf seed farms, sports fields, residential and commercial 

landscaped areas with established woody ornamentals, fairgrounds, race tracks, tennis 

courts, campgrounds, and rights-of-way. Halosulfuron-methyl is formulated as a water 

dispersible granule (WG) and applied as postemergence broadcast foliar sprays using 

ground or aerial equipment. Application through any type of irrigation system is 

prohibited. 

8. Imazosulfuron (118602): Currently registered for use on tomatoes, peppers and rice in 

conjunction with turf grass (residential, commercial, golf courses and sod farms), 

ornamentals (field-grown conifers, deciduous trees, non-bearing fruit and nut trees and 

landscape plants) bare-ground non-crop areas. Soil-directed ground application is to be 

used for all tomatoes, peppers, and rice; aerial application is permitted for rice only. 

Foliar application may be allowed for tomato and rice. Applications to turf and 

ornamentals are made with ground equipment; applications to bare ground non-crop areas 

can be made with ground or aerial equipment. Potential exposure routes from the 

proposed non-crop, turf and ornamental uses are limited to drinking water and 

occupational and residential pathways. 

9. Iodosulfuron Methyl (122021): Currently registered for foliar application to wheat, 

triticale, field corn, and turf (commercial/industrial, sod farms, ornamental, golf course, 

recreational, residential) and for preplant burndown application for cereal grains, 

soybean, and cotton. All applications of this product are to be performed by professional 

(commercial) applicators only. HED assumes that the product is not available for direct 

residential use and HED did not conduct a residential handler assessment. Occupational 

handlers may experience short-/intermediate-term exposure to iodosulfuron-methylsodium while mixing/loading and applying sprays. 

10. Mesosulfuron Methyl (122009): Currently registered uses are wheat and triticale. 

Mesosulfuron-methyl is not intended for use in public or residential settings. Therefore, 

residential exposure is not expected. There is a potential for occupational exposure to 

mesosulfuron-methyl during mixing, loading, application, and post-application activities. 
Page 9 of 10

11. Metsulfuron Methyl (122010): Metsulfuron-methyl is a herbicide used to control a 

variety of annual grasses and broadleaf weeds. Metsulfuron-methyl is registered for use 

on a number of food and feed crops, on conifers and hardwoods, on industrial sites, and 

on turf. Based on the current use profile, exposures can be expected to occur via the 

dietary (food and drinking water), residential (handler and post-application), and 

occupational (handler and post-application) routes for metsulfuron-methyl. 

12. Nicosulfuron (129008): Currently registered for use on field corn, sweet corn, popcorn, 

and grasses (Bermuda grass, grass forage and grass hay). Nicosulfuron is also registered 

for use on sorghum plants in seed propagation fields.  There are no residential uses of 

nicosulfuron.  

13. Orthosulfamuron (108209): Currently registered for the control of annual and perennial 

broadleaf weeds, sedges, and barnyard grass. There are no registered residential uses for 

orthosulfamuron or uses that might result in residential exposure. 

14. Primisulfuron Methyl (128973): Currently registered to control annual and perennial 

grass and broadleaf weeds. Based on the proposed use patterns, short-term dermal and 

inhalation exposures are expected. Intermediate-term dermal and inhalation exposures 

are possible for commercial or contract applicators. No residential handler or postapplication exposure risk has been calculated. 

15. Prosulfuron (129031): Currently is registered for use on field corn (grown for grain, 

silage, or seed), popcorn, grain sorghum (milo), wheat, barley, rye oats, triticale, proso 

millet, and following small grain harvest. Based on the current use profile, exposures can 

be expected to occur via the dietary (food and drinking water) and occupational (handler 

and post-application) routes for prosulfuron. 

16. Rimsulfuron (129009): Currently registered for use on non-residential turf such as golf 

courses, sod farms athletic fields, industrial and commercial lawns and similar 

nonresidential areas. Additionally, it is registered on agricultural food crops including 

bushberries, caneberries, soybeans, potatoes, field corn, tomatoes, grapes, various tree 

fruits, and tree nuts. There is currently a pending use on chicory. There are no proposed 

residential uses for rimsulfuron. 

17. Sulfometuron methyl (122001): Currently registered for commercial pre- and postemergent applications to manage annual and perennial broadleaf weeds and grasses in 

non-agricultural sites (i.e., forestry, rights of way, non-crop industrial sites, and 

unimproved turf). It is a non-food/non-feed use chemical with no current usage which 

could lead to exposures from consuming raw agricultural commodities (RACs) and/or 

processed foods. All sulfometuron methyl containing products are formulated as a water 

dispersible granule (WDG). Applications of sulfometuron methyl can be made aerially 

using fixed wing airplane and helicopter, and by ground using groundboom, rights-ofway, and hand-held equipment. Sulfometuron methyl can also be used to impregnate or 

coat dry bulk fertilizer for application to forested areas. Sulfometuron methyl containing 
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products are not labeled for use by professionals in the residential marketplace (i.e., 

indoor or outdoor residential use sites). 

18. Sulfosulfuron (085601): Currently registered as a selective pre- and post-emergent 

sulfonylurea herbicide for the control of various annual grasses and broadleaf weeds in 

winter and spring wheat, non-food crops and a variety of other non-crop sites including 

ornamentals, roadsides, airports, lumber yards, recreational areas, parks, golf courses, 

residential areas (lawns), industrial rights of way, etc. 

19. Thifensulfuron Methyl (128845): Currently registered for use on cereal grains (barley, 

field corn, oats, rice, sorghum, wheat, and triticale), oilseed crops (canola, rape, and flax), 

soybeans, sugar beets and cotton. In addition to these crop uses, it is also registered for 

use on agricultural fallow, idle, and conservation reserve land. It is registered for use as 

preplant or preemergence applications for the selective control of broadleaf weeds, and it 

is applied using common agricultural equipment (i.e., aerial, ground, chemigation). 

There are no registered residential uses for thifensulfuron methyl. 

20. Triasulfuron (128969): Currently registered for pre-emergence control of broadleaf and 

grassy weeds in wheat and post-emergence in wheat, barley, pastures, and rangeland. 

There are no residential uses for triasulfuron. Occupational exposure occurs through 

simultaneous dermal and inhalation exposure. 

21. Tribenuron Methyl (128887): Currently registered for use on cereal grains (barley, 

field corn, oats, rice, sorghum, and wheat), oilseed crops (canola, flax, and sunflower), 

soybeans, and cotton. There is also a tolerance with regional registration for grass forage, 

fodder, and hay (except Bermuda grass forage and hay). It is applied using common 

agricultural equipment (i.e., aerial, ground, chemigation). There are no registered 

residential uses for tribenuron methyl. 

22. Trifloxysulfuron Sodium (119009): Currently registered for used for use on numerous 

agricultural food/feed crops, including almonds, citrus, cotton (picker variety only), 

sugarcane and tomatoes. Non-agricultural uses include sports fields and residential turf 

grass.

23. Triflusulfuron Methyl (129002): Currently registered for use on sugar beets, garden 

beets, and chicory using broadcast (ground- or aerial-based) or band application methods 

at seasonal rates. There are no current or pending residential uses associated with 

triflusulfuron; therefore, a residential exposure assessment was not performed or 

required.