UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MEMORANDUM 

Date: l l-JUN-2015 

OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

SUBJECT: Sulfentrazone: Response to Comments on the Preliminary Human Health Risk 

Assessment. 

PC Code: 129081 

Decision No.: 495324 

Petition No.: NIA 

Risk Assessment Type: NIA 

TXR No.: NIA 

MRID No.: NIA 

DP Barcode: 0422814 

Registration No.: NIA 

Regulatory Action: Registration Review 

Case No.: 723 1 

CAS No.: 122836-35-5 

40 CFR: § 180.498 

FROM: Kelly 

Anwar 

M. 

Y. 

Lowe, 

Dunba

Environmen

r, Ph.D., Pha~macolog tal Scientisi. t st P':;

.-::, ~ =!!: ~ 

George F. Kramer, Ph.D., Semor Chem ~ _Jii~iiiit-§riC,.._ -------- --

Risk Assessment Branch 1 (RAB l) 

Health Effects Division (HED, 7509P) 

THROUGH: Thurston G. Morton, Acting Branch Chief 

RAB l/HED (7509P) 

TO: Christina Sche ltema, Chemical Review Manager 

Pesticide Re-Evaluation Division (PRD) (7508P) 

The Sulfentrazone Risk Assessment team has received comments on the Sulfentrazone 

Preliminary Human Health Risk Assessment (PRA; EPA Docket JD: EPA-HQ-OPP-2009-0624-

00 16) and attached is the response to comments. Comments relevant to the human health PRA 

were provided by FMC Corporation. 

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Sulfentrazone Response to Comments 0422814 

Comment #1: (Page 20, Section 4.4.4) "The residential assessment includes an FQPA SF of 

1 OX for inhalation exposures to account for the uncertainty associated with the lack of an 

appropriate inhalation toxicity study." 

FMC Comment: FMC notes that section 4.4.4 still accounts for a FQPA SF of IOX due to a lack 

of an appropriate inhalation toxicity study. A 28-day inhalation toxicity study has been 

submitted and has been determined acceptable by the Agency (MR1D 49253902). Section 4.1 of 

the sulfentrazone preliminary human health risk assessment states that the toxicological database 

for sulfentrazone is complete for risk assessment purposes and that the subchronic inhalation 

study has been submitted and reviewed by the Agency. The results have been incorporated in 

the risk assessment. In addition, Section 4.4 on page 20 "The RAB l risk assessment team 

recommends that the FQPA SF be reduced to IX for all exposure scenarios. The toxicity 

database is complete and dietary and residential exposure analyses are unlikely to underestimate 

exposure." FMC requests that this error in Section 4.4.4 be corTected from a l OX SF to a IX SF 

as supported by the study submitted and corresponding Agency review. 

EPA Response: The Agency agrees with FMC Corporation that there is an error in Section 

4.4.4, and will correct that section to reflect a 1 X SF. 

Comment #2: (Page 22, Section 4.5. l) "This inhalation study is protective for the systemic 

effects (including developmental effects seen in the oral studies) for the following reasons: 1) the 

dose spread in the inhalation study between the NOAEL and LOAEL is large (40 to 600 

mg/kg/day) .. . " 

FMC Comment: FMC notes ·that there is an error in the statement. The dose spread should be 

corrected from 40 to 600 mg/kg/day to 60 to 400 mg/kg/day. 

EPA Response: EPA confirms that the dose spread is 20, 60, and 400 mg/kg/day. 

Comment #3: (Page 28, Section 5.3) - Drinking Water Residue Profile 

FMC Comment: The use of PR1SM-GW to provide estimates for groundwater provides overly 

conservative values. PRISM-OW does not consider the best available data. Four prospective 

groundwater studies have been submitted that show significantly lower concentrations than 

esti'mated values from PR1SM-GW, even though the sites where these studies were conducted 

are within the upper most percentile of groundwater vulnerability. 

EPA Response: The Agency believes that the standard scenarios for the PRZM-GW model 

provide groundwater concentration estimates that are representative of the conditions modeled 

using the available information on the pesticide environmental fate and use patterns. Indeed, the 

6 scenarios currently used do represent evaluation of aquifers that are relatively vulnerable to 

impacts from applied pesticides. Should the Agency receive additional verifiable data regarding 

the environmental fate and transport of sulfentrazone residues that allow for refinement of mode l 

inputs it will be utilized in exposure modeling to support future risk assessments. EFED believes 

that the four PGW studies for sulfentrazone provide useful insights into sulfentrazone impacts on 

groundwater from normal use, but does not believe that it is scientifically valid to assume that 

the results of these studies directly provide upper-bound concentrations for sulfentrazone 

residues in groundwater. These studies provide a useful but small sampling of the range of 

conditions that may be associated with the application of sulfentrazone and do not directly 

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Sulfentrazone Response to Comments 0422814 

address the impacts of uses at the same site over multiple decades, which is assumed for 

screening for groundwater exposure with PRZM-GW. 

FMC Comment: The use of the total toxic residues (TTR) approach is overly simplified and 

does not consider all available data. When possible, environmental fate profiles and data of each 

residue of concern should be treated separately to appropriately represent chemical transport. In 

this case, environmental fate data are available for the metabolite SCA, so the use of the TTR 

approach should be refined to the sum of residues approach. 

EPA Response: The Agency has concluded that parent and 3-carboxylic acid sulfentrazone are 

the residues of concern for the drinking water assessment. The TTR values provided are the sum 

of parent and 3-carboxylic acid sulfentrazone, consistent with the definition of the residues of 

concern. 

FMC Comment: FMC supports the Crop Life America position that the SCI-GROW model 

would provide an adequate representation of conservative groundwater exposure. The dietary 

risk assessment using the drinking water exposure estimates from SCI-GROW would better 

represent potential, worst-case dietary exposure. 

EPA Response: The Agency has decided to support the primary use of PRZM-G W for screening 

for groundwater exposure. PRZM-GW modeling can be refined to represent more closely actual 

use conditions and pesticide behavior by site if there are available data. If the registrant believes 

that the exposure estimates with PRZM-GW are unnecessarily conservative, then a submission 

outlining their position with specific verifiable data should be submitted, and would be reviewed 

by the Agency. 

Comment #4: (Page 31) Table 6.1.1 Residential Handler Non-cancer Exposure and Risk 

Assessments for Sulfentrazone 

FMC Comment: Table 6.1. l has inhalation LOC = 100. The discrepancy lies within Section 6.1 

on page 30 that states that inhalation exposure risk estimates for residential handlers are not of 

concern (i.e. MOEs ~ 30 for inJ1alation). FMC requests that the error in Table 6.1. I be changed 

to match Section 6.1 and Section 4.5. l to a SF of 30X to account for 3X interspecies and I OX 

intraspecies uncertainty factors. 

EPA Response: HED agrees that there is an error in Table 6. 1.1 and will correct the table to 

indicate the LOC for inhalation is 30. 

Comment #5: (Page 3 7-40) Table 9 .1. I Occupational Handler Non-cancer Exposure and Risk 

Assessments for Sulfentrazone 

FMC Comment: Table 9.1.1 has inhalation LOC = 100. The discrepancy lies within Section 9.1 

on page 36 that states that occupational handler exposure and risk estimates indicate that shortand intermediate-term dermal and inhalation MO Es are not of concern to HED (i.e. MO Es ~ I 00 

for dermal and MOEs 30 for inhalation). FMC requests that the error in Table 9.1. 1 be changed 

to match Section 9.1 and Section 4.5. l to a SF of 30X to account for 3X interspecies and 1 OX 

intraspecies uncertainty factors. 

EPA Response: HED agrees that there is an error in Table 9. I. I and will correct the table to 

indicate the LOC for inhalation is 30. 

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Su I fentrazone Response to Comments 0422814 

Comment #6: (Page 43) Table A.2. Acute Toxicity Profile - Sulfentrazone 

FMC Comment: Row 4, column 3: The correct MRID number for "Acute dennal" study is 

41911607. 

EPA Response: There are two acute dermal studies for sulfentrazone, one in mice and the other 

in rats (MRlDs 419 11 606 and 41911607, respectively). HED acknowledges that the rat study 

should also be listed on the acute toxicity profile table. 

Comment #7: (Page 44) Table A.3. Toxicity Profile - Sulfentrazone 

FMC Comment: Row 3, Column 2: The cotTect MRID number for "90-Day oral toxicity 

(mice)" study is 43004602. 

EPA Response: HED acknowledges that the correct MRlD number is 43004602. 

Comment #8: (Page 54) Table B. l. Physiochemical Properties of Technical Grade 

Sulfentrazone 

FMC Comment: FMC notes that there is an error in Table B. l, which states that UV/visible 

absorption spectrum data is not available. FMC requests that the error be corrected to include 

data from the study "UV /visible absorption spectrum data is available for sulfentrazone technical 

with the title "Sulfentrazone (TGAI and PAI): Detennination of UV /Visible Absorption and 

Molar Absorptivity" (MRlD 4852160 1) which has previously been submitted to address this data 

requirement. 

EPA Response: BED acknowledges that a study was submitted to address the UV /visible 

absorption study. The table in the PRA will be revised. 

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