UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

MEMORANDUM 

DATE: June 3, 2016 

SUBJECT: Response to Comments on the Health Effects Divisions Sulfonylurea Risk Assessments 

PC Code: 085601, 108209, 118601, 118602, 

119009,119011, 122001,122009,122010,122020, 

122021, 128721,128820, 128845, 128887, 128901, 

128969, 128973, 129002, 129008, 129009, 129031, 

129091 

Decision No.: 514016 

Pet ition No.: NA 

Risk Assessment Type: Single Chemical/Aggregate 

TXR No.: NA 

MRID No.: NA 

FROM: Monique M . Perron, Sc.D., Toxicologist 

Risk Assessment Branch 1 (RAB6) 

Health Effects Division (HED; 7509P) 

DP No.: D431776 

Registration No.: NA 

Regulatory Action: Registration Review 

Case No.: NA 

CAS No.: 141776-32-1, 213464-77-8, 64902-

72-3, 122548-33-8, 290332-10-4, 104040-78-0, 

74222-97-2, 208465-21-8, 74223-64-6, 173159-

57-4, 144550-36-7, 100784-20-1, 83055-99-6, 

79227-27-3, 79277-27-3, 101200-48-0, 90982-

32-4, 82097-50-5, 86209-51-0, 126535-15-7, 

111991-09-4, 122931-48-0, 94125-34-5, 97780-

06-8 

40 CFR: NA 

THROUGH: Charles w. Smith Ill, Acting Associate Division DirectorQ ~ 

HED (7509P) ~ 

TO: Margaret Hathaway/Kevin Costello 

Risk Management and Implementation Branch II & IV 

Pesticide Re-evaluation Division (PRO; 7508P) 

Page 1 of 4 
Introduction: 

The purpose of this document is to provide the Health Effects Division's (HED) response to the public 

comments received on the individual HED sulfonylurea (SU) draft risk assessments (DRAs). These risk 

assessments are available on http://www.regulations.gov in the following dockets: 

• Bensulfuron-methyl (EPA-HQ-OPP-2011-0663) 

• Chlorimuron-ethyl (EPA-HQ-OPP-2010-04 78) 

• Chlorsulfuron (EPA-HQ-OPP-2012-0878) 

• Flazasulfuron (EPA-HQ-OPP-2011-0994) 

• Foramsulfuron (EPA-HQ-OPP-2012-0387) 

• Halosulfuron-methyl (EPA-HQ-OPP-2011-0745) 

• lmazosulfuron (EPA-HQ-OPP-2015-0625) 

• lodosulfuron-methyl-sodium (EPA-HQ-OPP-2012-0717) 

• Mesosulfuron-methyl (EPA-HQ-OPP-2012-0833) 

• Metsulfuron-methyl (EPA-HQ-OPP-2011-0375) 

• Nicosulfuron (EPA-HQ-OPP-2012-03 72) 

• Orthosulfamuron (EPA-HQ-OPP-2011-0438) 

• Primisulfuron-methyl (EPA-HQ-OPP-2011-0844) 

• Prosulfuron (EPA-HQ-OPP-2011-1010) 

• Rimsulfuron (EPA-HQ-OPP-2012-0178) 

• Sulfometuron-methyl (EPA-HQ-OPP-2012-0433) 

• Sulfosulfuron (EPA-HQ-OPP-2011-0434) 

• Thifensulfuron-methyl (EPA-HQ-OPP-2011-0171) 

• Triasulfuron (EPA-HQ-OPP-2012-0115) 

• Tribenuron-methyl (EPA-HQ-OPP-2010-0626) 

• Trifloxysulfuron-Sodium (EPA-HQ-OPP-2013-0409) 

• Triflusulfuron-methyl (EPA-HQ-OPP-2012-0605) 

HED appreciates the public's comments on the SU PRAs, has considered all of them, and has addressed 

them as appropriate below. Each of the comments identified below in this memo is individually 

addressed and is referenced by its specific comment number. 

Chlorimuron-methyl, EPA-HQ-OPP-2010-0478-0036 (R. Ambrose, DuPont Crop Protection): 

Comment Summary: During the review of this draft risk assessment, and that from September 14, 2009, 

an error was discovered in the description of effects observed in the 90-day dog study (MRID#: 132745). 

This study is utilized to set chronic dietary and short-term inhalation point-of-departures for 

chlorimuron. In summary Tables 4.3.1 entitled "Toxicological Doses and Endpoints for Chlorimuron 

ethyl for Use in Dietary and Non-Occupational Human Health Risk Assessments" and 4.3.2 entitled 

"Summary of Toxicological Doses and Endpoints for Chlorimuron ethyl for Use in Occupational Human 

Health Risk Assessments"; EPA indicates the Lowest Observed Adverse Effect Level (LOAEL) of 42.7 

mg/kg/day is based on "hematological changes", which is correct. However, it states these changes are 

"increased" hematocrit, hemoglobin and erythrocyt e counts ... Our report states that these parameters 

are actually "decreased". Decreases in these parameters are also consistent with histopathological data 

demonstrating recovery from the observed mild hemolytic anemia (hematopoiesis in various tissues and 

tendency toward increased reticulocytes, etc.). 

Page 2 of 4 
EPA Response: The endpoint for the 90 day dog study will be revised in any future chlorimuron-methyl 

risk assessments to state that hematocrit, hemoglobin and erythrocytes were decreased at the mid and 

high dose in the study. 

Chlorsulfuron, EPA-HQ-OPP-2012-0878-0035 (E. Bockrath, DuPont Crop Protection) 

Comment Summary: DuPont requests that EPA refer to its DER of MRID 41983101 and a recent 

supplemental rabbit study in MRID 48735102. DuPont is requesting that EPA update the review of this 

study. 

EPA Response: HED thanks DuPont for the comment. The review for this study and any potential 

impacts on endpoints for chlorsulfuron will be updated in any future chlorsulfuron risk assessments. 

Foramsulfuron, EPA-HQ-OPP-2012-0387-0026 (T. Moore, Bayer CropScience): 

Comment Summary: Foramsulfuron is currently only registered for use in ground application in turf 

grass and vegetative management (non-crop). The use patterns for foramsulfuron in corn are no longer 

registered. Bayer voluntarily canceled Option® Corn Herbicide (Reg. No. 264-685). This information was 

released via the Agency in a public notice on June 16th, 2015 in the notice of receipt 80 FR 34408. 

EPA Response: Any future risk assessments for foramsulfuron will specify that corn is no longer a 

registered use. 

Primisulfuron-methyl, EPA-HQ-OPP-2011-0844-0029 (S. Pvles, Syngenta Crop Protection, LLC}: 

Comment Summary: Guideline study numbers 870.11 and 870.12 are included in the acute toxicity table 

(Table B.2.1) twice, it is not clear why these endpoints are repeated (the MRID numbers are the same 

for both acute oral, and both acute dermal studies listed). Please clarify the duplication. 

EPA Response: HED acknowledges the duplication error in the table. Since the revision does not impact 

the risk calculations or conclusions, no revision was undertaken at this time. However, HED will remove 

the duplicated lines for any future risk assessments for primisulfuron-methyl. 

Nicosulfuron, EPA-HQ-OPP-2012-0372-0051 (R. Ashley, DuPont Crop Protection) 

Comment Summary: DuPont noted that in the HED RA, it states that the coarse screen water number 

was used for nicosulfuron. However, in the "Drinking Water Exposure Assessment for the 22 SUs", 

nicosulfuron is listed as one of the 8 compounds for which refined screen data was generated. 

EPA Response: HED thanks DuPont for the comment . Given the risk picture for nicosulfuron there was 

no need to utilize the refined drinking water number in the nicosulfuron dietary assessment. 

Tribenuron-methyl, EPA-HQ-OPP-2010-0626-0037 (R. Ambrose, DuPont Crop Protection): 

Comment Summary: The point of departure for the acute dietary assessment is correctly identified as 

300 mg/kg/day, which is the No Observed Adverse Effect Level (NOAH) from the acute neurotoxicity 

study (MRID# 48732501, DuPont Study Report Number: DuPont-31859 Revision 1). The lowest 

Page 3 of 4 
Observed Adverse Effect level (lOAEL) of 1000 gm/kg/day is correctly identified based on the body 

weight and body weight gain reductions observed. However, the transient effects on motor activity and 

rearing are considered to be secondary to these effects on body weight and are NOT considered to be a 

specific neurotoxic effect as characterized in the health assessments. Therefore we would suggest an 

amendment of the basis for the Point of Departure (POD) which excludes neurotoxicity as an end point; 

since there is no indication that tribenuron methyl has the potential to cause a specific neurotoxic 

effect. 

EPA Response: The endpoint for the acute neurotoxicity study will be updated in any future tribenuronmethyl risk assessments to clarify that the clinical signs observed are attributed to the systemic effects 

seen in the study. 

Triflusulfuron-methyl, EPA-HQ-OPP-2012-0605-0027 (8. Bieber, DuPont Crop Protection): 

Comment Summary: On Page 28 of 32, Table E.2 Physicochemical Properties of the report for 

triflusulfuron methyl, the unit of solvent solubility should be mg/ml or g/L. 

EPA Response: HED thanks DuPont for the comment. HED will correct the unit of solvent solubility to 

reflect g/L in any future triflusulfuron-methyl risk assessments. 

Page 4 of 4