UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D .C. 20460

OF FICE OF P

REVENTION, PES TIC IDES AND
TOX IC SUBST ANCES

MEMORAND UM

DATE: 5/8 /2009

SUBJECT: Sulfometuron Methyl: Response to Public Comments for "Phase 3 Amendment of Sulfometuron Methyl: HED Chapter of the Registration Eligibility Decision (RED)"

PC Code: 12200 I

MRJD No.: NA Petition No .: NA
Assessment Type: NA
TXRNo.: NA DP Barcode: 0346177 Registration No.: NA Regulatory Action: Response to Comments Reregistration Case No.: NA
CAS No.: 74222 -97-2

FROM :

THROUGH:

TO : Wade Britton

, MPH

, Risk Assessor
Risk Assessment Branch V Health Effects Division (7509P)

Jack Arthur, Branch Chief

# ~. Risk Assessment Branch V
Health Effects Division (7509 )

R ussell W asem , Chemical Re view Manage r Reregistration Branch 1 Special Review & Reregistration Division (7508P)

The Health Effects Division's (HED) Risk Assessment Branch V has addressed public

comments on the human health risk assessment for sulfometuron me thyl RED dated August II

, 2008. HED defers to the Environmental Fate and Effects Division ( EFED) on issues identified in the public comments that effect the human health assessment, but pertain to how E FED calculated concentrations ofsulfometuron methyl's degradates.

HED received public comments from the following groups: DuPont Crop Protection (the technical registrant), American Forest Management

, lnc., Roseburg Resources Company (Mark Wall and Tim Truax), and an anonymous commenter

.

Page I of5Comment from DuPont Crop Protection:

Docket ID Number EPA-HQ-OPP- 2008-0129-0117, submitted January 9, 2009.

DuPont proposes the Agency consider surrogate data to inform sulfometuron methyl dermal penetration. Due to the absence of a dermal penetration study the Agency exposure estimates are driven by a default 100% dermal absorption factor. DuPont’s review of in vitro and in vivo dermal pene tration values for othe r DuPont sulfonylureas (i.e., bensulfuron methyl, nicosulfuron, trib enuron methyl, rimsulfuron, thifensulfuron methyl and triflusulfuron methyl) ranged from 0.01 to 17.7%. Based on this review, DuPont proposed that a penetration value of 10.0% can be conservatively used for the assessment of operator exposure.

HED Response:

HED reviewed the data on the sulfonylur ea chemicals provided in Table 1 of the DuPont’s submission. However, no actual data with sulfometuron methyl were provided and HED considers it speculative at this time to use data from these other sulfonylureas as surrogate data to establish a dermal abso rption factor. Therefor e, in the absence of actual data with sulfometuron methyl, HED uses the more conservative default estimate of 100% dermal absorption.

All but one occupational exposur e scenario result in MOEs which are not of concern to the Agency (at some level of personal prot ection) using the default estimate for dermal absorption. A combined MOE = 90 result s for mixing/loading water dispersable granulars (WDGs) for aerial app lication to forestry and non-cr op areas. This scenario is of concern to the Agency; however, this co ncern was described as reduced based upon conservative inputs (i.e., 100 % dermal abso rption) in the risk estimates.

Comments from Roseburg Resources Comp any (Mark Wall and Tim Truax) and American Forest Management, Inc.:

Roseburg Resources Company (Mark Wall) , Docket ID Number EPA-HQ-OPP-2008- 0129-0022, submitted December 31, 2008.

American Forest Management, Inc., Docket ID Number EPA-HQ-OPP-2008-0129-42

Roseburg Resources Company (Tim Truax) , Docket ID Number EPA-HQ-OPP-2008- 0129-0131, submitted January 9, 2009.

The following comments and resulting response ha ve been collated due to their similarity of topic (i.e., the changes for personal protective equipment (PPE) required due to the sulfometuron methyl RED).

Page 2 of 5Mark Wall and Tim Truax of Roseburg Re sources Company both commented that the proposed PPE rule changes are unnecessary gi ven the “practically non-toxic” status of sulfometuron methyl to humans, but are none theless not a burden and acceptable as presented.

American Forest Management, Inc. comment ed that the changes to the proposed PPE shown on page 32 appear to be somewhat excessive considering sulfometuron has toxicological ratings listed either as a categ ory III or IV rating. The requirement for chemical resistant gloves while mixing the concentrated product could be argued, but these should not be required for loading or applying a dilu ted mix with a low pressure hand wand.

HED Response:

The Agency completes occupational handler assessments by using different levels of personal protection, or a tiered approach. The lowest tier is repres ented by the baseline scenario (long-sleeved shirt, long pants and no gloves or re spiratory protection), followed by increasing levels of personal protection represented by personal protective equipment (PPE) (e.g., gloves, extra clothi ng and respirators) and engine ering controls (e.g., closed cabs and closed loading systems). This approa ch is always used by the Agency in order to be able to define label language using a risk-based approach and not based on generic requirements for label language. The minimal le vel of adequate protection for a chemical is generally considered by the Agency to be the most practical option for risk reduction.

20 occupational exposure scenarios were iden tified based on the types of equipment and techniques that can potentially be used to make sulfometuron methyl applications. Of the 20 exposure scenarios assessed, 2 (mixing/lo ading aerial equipment with WDGs and mixing/loading/applying liquid with low pressure handwand) resulted in a risk of concern at baseline level and, therefore, required an increase (or tier ed) level of personal protection to equal or exceed the Ag ency’s level of concern (LOC).

The exposure data, toxicological endpoints, and other factors which were used to estimate occupational exposure/risk represent the best sources of data available to the Agency. Maximum application rates were derived dire ctly from sulfometuron methyl labels. Exposure factors (e.g., body weight, amount treat ed per day, protection factors, etc.) are all standard values that have been used by the Agency for several years and are derived from peer reviewed sources whenever possible. The unit exposure values (UEs) used are the best available estimates of exposure.

The toxicological database fo r sulfometuron methyl was cons idered sufficient to provide information to conduct a screening level assessment for the occupational exposure scenarios identified

. The acute toxicity profile (i.e., 6-pack) was not used to for the purposes of risk assessment and/or ORE mitigat ion, rather dermal and inhalation toxicity endpoints were used to quantify risk were selected from a chronic dog feeding study. Therefore, the required increase in personal protection (chemical resistant gloves) was based upon the endpoints selected from the chr onic study, not the acute toxicity profile of

Page 3 of 5sulfometuron methyl. A dermal absorption factor of 100% was assumed since no data were provided. A full description of the algorithms and inputs used by the Agency to assess occupational handler exposure is described in the document, “Sulfometuron Methyl: Occupational and Residential Exposur e Assessment for the Reregistration Eligibility Decision (Non-Food) ” (W. Britton, D345025, 12/20/2007).

Comment from Anonymous:

Docket ID Number EPA-HQ-OPP-2008- 0129-0038, no submission date provided, received January 6, 2009.

An anonymous commenter stated that the Agency’s statements regarding personal protective equipment have no merit. The fo rmulation of an extruded pellet or a dry flowable formulation. Chemical resistant gloves are most importa nt with liquid or emulsifiable concentrate formulations. Th e proposed label change s are regarding liquid formulation. I feel the product label alre ady meets the safety and personal protective equipment.

HED Response:

The Agency uses a concept known as unit expos ure (UE) as the basis for the scenarios used to assess occupational worker exposures to pesticides. UEs numerically represent the exposures one would receive related to mixing/loading or an application. The Agency has developed a series of UEs that are unique for each scenario typically considered in our assessments (i.e., there ar e different unit exposures for different types of application equipment, job functions, and levels of protection). The UE concept has been established in scientif ic literature and also thr ough various exposure monitoring guidelines published by the Agency and inte rnational organizations such as Health Canada and OECD (Organization for Ec onomic Cooperation and Development).

The unit exposure values used to assess occ upational exposure for varying scenarios of sulfometuron methyl use were based on surr ogate exposure data from Pesticide Handlers Exposure Database (PHED) Version 1.1. PHED was developed by the Agency to provide the best available information on occupa tional handler exposures. It is a software system consisting of two parts – a database of measured exposure values for workers involved in the handling of pes ticides under actual field conditions and a set of computer algorithms used to subset and statistically summarize the selected data. Mixer/loader sulfometuron methyl exposure s cenarios were estimated using PHED data specific to dry flowable (DF) products since this formulati on is most similar to WDGs; however, all other tasks (i.e., applicators, flaggers, and mixer/loader/applicators) were assessed with PHED data specific to liquid products since the WDGs are mixed into and applied as a liquid.

Using the UE values from PHED specific to dry flowable formulati ons and incorporating the tiered approach for estimating exposure a nd risk described in the previous response, the Agency determined that double layer (i.e ., coveralls over a singl e layer of clothing)

Page 4 of 5and chemical resistant gloves are required for mixing/loading for aerial equipment with WDGs (e.g., an MOE = 64 without gloves and anMOE = 90 results with the addition of gloves). Employing the same method of ri sk quantification/es timation, the Agency determined that single layer of clothing and gloves are required for mixing/loading/applying liquids wi th a low pressure handwand.

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