Date: 

Subject: 

From: 

Through: 

To: 

Introduction 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

March 27, 2014 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

Rimsulfuron: Occupational and Residential Exposure Assessment for the New 

Use on ALS-Tolerant "DuPont INZEN Z" Sorghum 

PC Code: 129009 

Decision No.: 473406 

Petiition No.: 

Risk Assessment Type: ORE 

TXRNo.:NA 

MRIDNo.:NA 

DP Barcode: 418152 

Registration No.: 352-748, 352-816 

Regulatory Action: Section 3 

Case No.: NA 

CAS No.: 122931-48-0 

40 CFR: § 180.478 

Cassi Walls, Ph.D., Senior Biologist ~ 2 W~ Risk Assessment Branch III 

Health Effects Division (7509P) 

Barry O'Keefe, Branch Senior Scientist (:5, 0 ~ ~ Risk Assessment Branch III - r 

Health Effects Division (7509P) 

Jennifer Tyler, ExpoSAC Reviewer vJ).l.t -{l;[ij;z~ _ and t l'\ 

Mon

Exposure 

ica Hawkins, 

Science 

ExpoSAC 

Advisory Comm 

Revie 

ixpoSAC) 

f~ 

I HED 

Kable Davis, RM#25 

Registration Division (7505P) 

The Registration Division (RD) requested that the Health Effects Division (HED) conduct an 

occupational and residential exposure and risk assessment for the proposed new use of 

rimsulfuron on ALS-Tolerant "DuPont INZEN Z" sorghum. 

It is HED policy to use the best available data to assess exposure. Several sources of generic 

data were used in this assessment as surrogate data in the absence of chemical-specific data, 

Page I of 19 
including Pesticide Handlers Exposure Database Version 1.1 (PHED 1.1 ); the Agricultural 

Handler Exposure Task Force (AHETF) database; and the Agricultural Reentry Task Force 

(ARTF) database. Some of these data are proprietary, and subject to the data protection 

provisions of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). 

Note: This memorandum was reviewed by the Exposure Science Advisory Committee 

(ExpoSAC) on March 20, 2014. 

Page 2 of 19 
Table of Contents 

1.0 Executive Summary ....... .... .................................................................................................. 4 

2.0 Risk Assessment Conclusions and Recommendations ........................................................ 5 

3.0 Hazard Characterization ....................................................................................................... 6 

4.0 Use Profile ........................................................................................................................... 8 

5.0 Residential Exposure and Risk Estimates ............................................................................ 9 

5.1 SprayDrift .............................. ........................... .................. ............................................. 9 

5.2 Residential Bystander Post-Application Inhalation Exposure ....................................... l 0 

6.0 Occupational Exposure and Risk Estimates ...................................................................... 10 

6.1 Occupational Handler Exposure/Risk Estimates ............................................................ 10 

6.2 Occupational Post-application Exposure/Risk Estimates .............................................. 15 

6.2.1 Occupational Post-application Inhalation Exposure/Risk Estimates ...................... 15 

6.2.2 Occupational Post-application Dermal Exposure/Risk Estimates .......................... 15 

Appendix A. Summary of Occupational and Residential Non-cancer Algorithms ..................... 18 

Page 3 of 19 
1.0 Executive Summary 

Rimsulfuron is a sulfonylurea herbicide (Group 2) that works via inhibition of acetolactate 

synthetase enzyme found in susceptible plants. It has been registered for weed control on 

bushberries, caneberries, grapes, citrus, tree nuts, pome fruits, stone fruits, corn, chicory and 

non-cropland. 

DuPont Crop Protection (DuPont) has submitted a petition to add a new use for rimsulfuron 

herbicide on "INZENTM Z", a variety of sulfonylurea tolerant sorghum, and to add the proposed 

crop to the DuPontTM Resolve® Herbicide (EPA Reg. No. 352-748) and DuPontTM Steadfast® XP 

Herbicide (EPA Reg. No. 352-816) product labels. The Resolve® Herbicide end-use product is a 

water soluble granule (WG) formulation containing 25% rimsulfuron as the active ingredient 

(ai). The Steadfast® Herbicide end-use product is a WG formulation containing 15% rimsulfuron 

and 30% nicosulfuron as the active ingredients. Nicosulfuron exposure and risk will be assessed 

in a separate document. 

Proposed Use Profile: 

DuPontTM Resolve® Herbicide and DuPontTM Steadfast® XP Herbicide end-use products are 

proposed to include a use on "IN ZENTM Z", a variety of sulfonylurea tolerant sorghum. 

Applications are made using ground and aerial equipment. The proposed postemergent 

application rates are 0.012- 0.031 lb ai/ A with a maximum seasonal rate of 0.031 lb ai/ A, a 

retreatment interval (RTI) of 7 days and, a pre-harvest interval (PHI) of 69 days. Handlers are 

required to wear the following personal protective equipment (PPE): long-sleeved shirt, long 

pants, shoes, socks, and chemical-resistant gloves. 

Hazard Concerns: 

The adequacy of the rimsulfuron toxicity database is considered complete. Short- and intermediateterm dermal and inhalation risks are based on systemic effects observed at the lowest observed adverse 

effect level (LOAEL) of 125 mg/kg/day and a no observed adverse effect level (NOAEL) of6.25 

mg/kg/day) from a 90-day oral toxicity study in dogs. The HASPOC has determined that the 

requirement for a subchronic inhalation toxicity study and dermal study (TRX 0050008) has been 

waived. Since no inhalation absorption data are available, toxicity by the inhalation route is 

considered to be equivalent to the estimated toxicity by the oral route of exposure. Since no dermal 

absorption data are available, a dermal absorption factor of 1 00% was used for the exposure 

assessment. Since the dermal and inhalation endpoint is not based on developmental effects, the 

average body weight of an adult (80 kilograms) was used in the exposure assessments. The cancer 

classification is "not likely to be carcinogenic to humans." 

The rimsulfuron risk assessment team evaluated the quality of the toxicity and exposure data 

and, based on these data, recommended that the Food Quality Protection Act (FQP A) Safety 

Factor be reduced to 1 X. The level of concern (LOC) for occupational dermal and inhalation 

risk assessments is a margin of exposure (MOE) of 100. 

Page 4 of 19 
Occupational Exposure: 

Occupational Handler Exposures: 

Occupational short- and intermediate- term dermal and inhalation exposures are expected from 

rimsulfuron handler activities associated with the proposed sorghum use. Since the dermal and 

inhalation endpoints are based on the same study, the exposures were combined. A MOE greater 

than 1 00 for the dermal, inhalation, and combined routes is deemed adequate to protect 

occupational rimsulfuron handlers. All handler scenarios resulted in MOEs greater than the LOC 

(i.e., MOEs 2:: 1 00) for dermal, inhalation, and combined exposures and, therefore are not of 

concern. 

Occupational Post-application Exposures: 

Occupational short - and intermediate-term dermal exposures are expected from rimsulfuron 

post-application activities associated with the proposed sorghum use. All post-application 

scenarios resulted in MOEs greater than the level of concern (LOC = MOEs 2:: 1 00) for dermal 

exposures and, therefore are not of concern. 

Based on the Agency's current practices, a quantitative non-cancer occupational post-application 

inhalation exposure assessment was not performed for rimsulfuron at this time. If new policies 

or procedures are put into place, the Agency may revisit the need for a quantitative occupational 

post-application inhalation exposure assessment for rimsulfuron. 

Restricted Entry Interval (REI): The proposed 4-hour REI which appears on the proposed 

supplemental label is consistent with 4-hour REI on the master label, and is adequate to protect 

for worker exposure. 

Human Studies Review 

This risk assessment relies in part on data from studies in which adult human subjects were 

intentionally exposed to a pesticide or other chemical. These data, which include studies from 

PHED 1.1, AHETF, and the ARTF database are ( 1) subject to ethics review pursuant to 40 CFR 

26, (2) have received that review, and (3) are compliant with applicable ethics requirements. For 

certain studies, the ethics review may have included review by the Human Studies Review 

Board. Descriptions of data sources, as well as guidance on their use, can be found at the 

Agency website 1

• 

2.0 Risk Assessment Conclusions and Recommendations 

There are no occupational risk estimates of concern associated with the proposed new sorghum 

use of rimsulfuron. All of the dermal, inhalation, and combined handler and post-application 

MOEs based on the labeled PPE are greater than the LOC of 100 based on the proposed labeled 

PPE. 

1 http://www.epa.gov/pesticides/science/hand ler-exposure-data.htm I and 

http://www. epa. gov /pesticides/science/post -app-ex posure-data.htm I 

Page 5 of 19 
Residue Data Requirements 

Dislodgeable Foliar Residue (DFR): In accordance with the updated Part 158 data requirements 

(2007), one or more DFR studies are required when a pesticide has residential or occupational 

uses that could result in post-application dermal exposure. As part of the recent revision to the 

Health Effects Division's 2012 Standard Operating Procedures for Residential Pesticide 

Exposure Assessment, HED analyzed a number of DFR studies and selected a new default value 

for the fraction of the application rate available to be dislodged after a foliar application (FAR). 

This default value is 25% and is based on an analysis of 19 DFR studies where the FAR value 

ranged from 2% to 89%. This value is recommended for use in both residential and occupational 

post-application assessments. Of the analyzed DFR studies, the maximum FAR value seen was 

89% or 3.6 times higher than the default residue transfer value. Therefore, the HED has decided 

that a calculated MOE of approximately 4 times higher than the level of concern (e.g., an MOE> 

400 if the LOC = 1 00) using the default dislodged residue values would provide an adequate 

margin of safety for any potentially higher residues seen in a chemical-specific DFR study 

(Guidance for Requiring/ Waiving TurfTransferrable Residue (I'TR) and Dislodgeable Foliar 

Residue (DFR) Studies. 6/7/2012, Exposure Science Advisory Council). A DFR study is not 

required for rimsulfuron at this time since the dermal MOE is greater than 4 times the LOC 

based on default values for the fraction of application rate available for transfer after a foliar 

application. 

3.0 Hazard Characterization 

For the proposed new use, the toxicological database for rimsulfuron is sufficient for risk 

assessment purposes. All the requirements of the new Part 15 8 guidelines have now been 

submitted or waived. The recently submitted immunotoxicity, acute neurotoxicity and 

subchronic neurotoxicity studied are currently under review. HASPOC waived the subchronic 

inhalation study. 

Acute Toxicity 

Technical rimsulfuron has low toxicity (Toxicity Category IV) via oral, dermal and inhalation 

route of exposures. It is a moderate eye irritant (Toxicity Category III) and is not a skin 

sensitizer (Table 3.1). 

Table 3.1 Acute Toxicity Profile ofRimsulfuron 

Guideline No. Study Type Results Toxicity Category 

870.1100 Acute oral - rat LDso = > 5000 mg/kg IV 

870.1200 Acute dermal - rat LDso = > 2000 mg/kg IV 

870.1300 Acute inhalation - rat LCso = > 5.4 mg/L IV 

870.2400 Acute eye irritation Moderate eye irritant III 

870.2500 Acute dermal irritation Not an irritant IV 

870.2600 Skin sensitization Not a sensitizer --

Page 6 of 19 
Toxicological PODs Used for Risk Assessment 

The toxicity database indicates that target organs for rimsulfuron are the liver and kidney in the 

rat and dog, along with the testis and blood in the mouse and dog. In the mouse, the stomach 

was also a target organ. Adverse changes in body weight and food consumption were observed 

in rats, mice and dogs. 

Effects seen in the subchronic and/or chronic toxicity studies in one or more species included 

decreased body weight and body weight gain, increased relative and/or absolute liver and kidney 

weights, diuresis (increased urine volume), decreased liver enzymes and bilirubin and increased 

serum cholesterol, fatty change, hepatocellular hypertrophy, increased red blood cell (RBC), 

hemoglobin and platelet concentration, increased incidences of dilation and cysts in the glandular 

stomach, degeneration of the testicular artery and tunica albuginea, increased incidence of 

seminiferous tubule degeneration and increased numbers of spermatid giant cells present in 

epididymides in males. 

Rimsulfuron is not mutagenic and has been classified as "Not Likely to be Carcinogenic to 

Humans," based on the lack of evidence for carcinogenicity in studies conducted in rats and 

mice. 

In the developmental toxicity study in rats, no developmental toxicity was seen at the highest 

dose tested. In the developmental toxicity study in rabbits, and in the two generation study in 

rats, developmental/offspring toxicity was seen in the presence of maternal/systemic toxicity of 

comparable severity, and at similar dose levels. Consequently, there is no quantitative or 

qualitative evidence of increased susceptibility following pre- and/or postnatal exposures, and 

there are no concerns or residual uncertainties. There was no evidence of neurotoxicity or 

immunotoxicity in the recently submitted studies which have undergone preliminary evaluation 

and are currently under detailed review. Therefore, HED has concluded that the FQPA Safety 

Factor should be reduced to 1 X. The LOC for occupational dermal and inhalation risk 

assessments is an MOE of 100. 

The endpoint for dermal and inhalation risk assessments for occupational workers was chosen 

from the 90-day oral study in the dog, and was based on kidney effects. 

A summary of the toxicological endpoints and doses used in the non-occupational and 

occupational risk assessment for rimsulfuron is provided in Table 3.2. 

Table 3.2. Toxicolo!!ical Doses and Endpoints Used in Occupa tional Risk Assessment of Rimsulfuron. 

Exposure/ Point of Uncertainty LOC for Risk Study and Toxicological 

Scenario Departure Factors Assessment Effects 

Dermal NOAEL=6.25 UFA= lOx Occupational 90 Day Toxicity-Dog Short- (1-30 Days) mg/kg!day UFH = lOx LOC for MOE LOAEL= 125 mg!kg!day, based on 

and Intermed iate- DAF= 100% = 100 kidney effects including increased Tenn (I- 6 urinary volume, increased kidney Months) weights, and decreased osmolality. 

Page 7 of 19 
Table 3.2. Toxicolouical Doses and Endpoints Used in Occupationa l Risk Assessment of Rimsulfuron. 

Exposure/ Point of Uncertainty LOC fo r Risk Study and Toxicological 

Scenario Depa rture Factors Assessment Effects 

Inhalation NOAEL= 6.25 UFA= I Occupational 

Short- (1 -30 Days) mg/kg/day UFH"" lOx LOC for MOE 

and Intermediate- = 100 

Term(I-6 

Months) 

Cancer (oral, Rimsulfuron is classified as "not likely to be carcinogenic to humans" due to the absence of 

dermal, inhalation) tumors in rat a!ld mouse carcinogenicity studies. 

OAF = dermal absorption factor, LOAEL = lowest observed adverse effect level, LOC = level of concern, MOE = 

margin of exposure, NOAEL = no observed adverse effect level, UF A= uncertainty factor for extrapolation from 

animal to human (interspecies) and UFH = uncertainty factor for potential variation in sensitivity among members of 

the human population (intraspecies). 

Absorption 

Since no dermal absorption data are available, a dermal absorption factor of 100% was used for 

the exposure assessment. Since no inhalation absorption data are available, toxicity by the 

inhalation route is considered to be equivalent to the estimated toxicity by the oral route of 

exposure. 

Body Weight 

The standard body weight for the general population (80 kg) was used for all exposure scenarios 

covered in this risk assessment since the endpoints selected were not developmental and/or fetal 

effects. 

4.0 Use Profile 

The proposed use pattern for rimsulfuron on sorghum is summarized in Table 4.1. 

Table 4.1. Summary of Directions for Use of Rimsulfuron. 

Formulatio Max. 

Applic. T iming, Applic. Max. No. RTP Seasonal n PHI Use Directions and Rate Applic. Applic. and Equipment (EPA Reg. Jb ai/A per Season (days) Rate (days) Limitations 

No.) lb ai/A 

Sulfonyl-Tolerant Varieties of Sorghum "INZENTM Z" 

Page 8 of 19 
Table 4.1. Summary of Directions for Use of Rimsulfuron. 

Formulatio 

Applic. T iming, n 

and Equipment [EPA Reg. 

No.) 

Postemergence, 4 -

20 inches tall (Y3 Steadfast® - V7 stage); XP 

15%SG Aerial, Broadcast, [352-8 16] foliar; Ground 

equipment only. 

Postemergence, 4 -

20 inches tall (V3 

- Y7 stage); Resolve® 

25%SG 

Aerial, Broadcast, [352-748] 

foliar; Ground 

equipment only. 

1 Rl ' I = Retreatment mterval 1 PHI = Preharvest interval. 

Applic. Max. No. 

Rate Applic. 

lb ai/A per Season 

0.012 

(1.25 oz/A) 

to 2 

0.016 

(1.67 oz/A) 

0.016 

( 1.0 oz/A) 

to 2 

0.031 

(2.0 oz/A) 

Max. 

RTJ 1 Seasonal PHI Use Directions and Applic. (days) Rate (days) Limitations 

lb ai/A 

Do not apply through any 

0.0 16 irrigation system. Aerial 

7 (1 .67 oz/A) 69 application is not permitted 

in New York State or 

California. 

Do not apply through any 

0.03 1 irrigation system. Aerial 

7 (2.0 oz/A) 69 application is not permitted 

in New York State or 

California. 

The proposed use pattern for Steadfast® XP Herbicide on sulfonyl-tolerant sorghum is to apply at 

a maximum rate of 1.67 ozl A/season (0.0 16 lb ai/ A/season) to provide selective postemergence 

grass and broadleaf weed control. The annual rate may be applied in two sequential treatments; 

with a minimum of 7 days between applications. A preharvest interval (PHI) of 69 days has 

been proposed for sorghum grain and stover. 

The proposed use pattern for Resolve® Herbicide on sulfonyl-tolerant sorghum is to apply at a 

maximum rate of2.0 ozJA/season (0.031 lb ai/A/season) to provide selective postemergence 

grass and broadleaf weed control. The annual rate may be applied in two sequential treatments; 

with a minimum of 7 days between applications. A PHI of 69 days has been proposed for 

sorghum grain and stover. 

Personal Protective Equipment (PPE): The PPE for Steadfast®XP and Resolve® Herbicides is 

long-sleeved shirt, and long pants, shoes plus socks, and chemical resistant gloves. 

5.0 Residential Exposure and Risk Estimates 

There are no existing or proposed uses for rimsulfuron in residential settings, and therefore a 

residential exposure assessment was not conducted. 

5.1 Spray Drift 

Spray drift is always a potential source of exposure to residents nearby to spraying operations. 

This is particularly the case with aerial application, but, to a lesser extent, could also be a 

potential source of exposure from the ground application method employed for rimsulfuron. The 

Agency has been working with the Spray Drift Task Force, EPA Regional Offices and State 

Lead Agencies for pesticide regulation and other parties to develop the best spray drift 

Page 9 of 19 
management practices (see the Agency's Spray Drift website for more information2• The 

Agency has completed its evaluation of the new database submitted by the Spray Drift Task 

Force, a membership of U.S. pesticide registrants, and is developing a policy on how to 

appropriately apply the data and the AgDRIFT computer model to its risk assessments for 

pesticides applied by air, orchard airblast and ground hydraulic methods. After the policy is in 

place, the Agency may impose further refinements in spray drift management practices to reduce 

otT-target drift with specific products with significant risk estimates associated with drift. 

Although a quantitative residential post-application inhalation exposure assessment was not 

performed as a result of pesticide drift from neighboring treated agricultural fields, an inhalation 

exposure assessment was performed for flaggers. This exposure scenario is representative of a 

worse case inhalation (drift) exposure and may be considered protective of most outdoor 

agricultural and commercial post-application inhalation exposure scenarios. 

5.2 Residential Bystander Post-Application Inhalation Exposure 

Based on the Agency's current practices, a quantitative post-application inhalation exposure 

assessment was not performed for rimsulfuron at this time primarily because of the low acute 

inhalation toxicity (Toxicity Category IV), low vapor pressure (1.13x 1 o-8 mm Hg at 25 °C), and 

the low proposed use rate (0.031 lb ai/ A). However, volatilization of pesticides may be a source 

of post-application inhalation exposure to individuals nearby pesticide applications. The Agency 

sought expert advice and input on issues related to volatilization of pesticides from its Federal 

Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP) in December 2009, 

and received the SAP's final report on March 2, 20103. The Agency is in the process of 

evaluating the SAP report and may, as appropriate, develop policies and procedures to identify 

the need for and, subsequently, the way to incorporate post-application inhalation exposure into 

the Agency's risk assessments. If new policies or procedures are developed, the Agency may 

revisit the need for a quantitative post-application inhalation exposure assessment for 

rimsulfuron. 

6.0 Occupational Exposure and Risk Estimates 

6.1 Occupational Handler Exposure/Risk Estimates 

HED uses the term handlers to describe those individuals who are involved in the pesticide 

application process. HED believes that there are distinct job functions or tasks related to 

applications and exposures can vary depending on the specifics of each task. Job requirements 

(amount of chemical used in each application), the kinds of equipment used, the target being 

treated, and the level of protection used by a handler can cause exposure levels to differ in a 

manner specific to each application event. 

Based on the anticipated use patterns and current labeling, types of equipment and techniques 

that can potentially be used, occupational handler exposure is expected from the proposed uses. 

2 Available: hlil~t:£. ~\v epu~lli)Y op pOOOO I !lactsheets!spralf.drill.bJ!!.l 3 Available: http://www.epa.gov/scipoly/SAP/meetings/2009/ 120 I 09meeting.html 

Page 10 of 19 
The quantitative exposure/risk assessment developed for occupational handlers is based on the 

following scenarios: 

• Mixer/Loader of SG formulation for ground boom application to sorghum, 

• Mixer/Loader of SG formulation for aerial application to sorghum, 

• Applicator of liquid formulation for groundboom application to sorghum, 

• Applicator of liquid formulation for aerial application to sorghum, and 

• Flagging to support aerial spray applications. 

Occupational Handler Exposure Data and Assumptions 

A series of assumptions and exposure factors served as the basis for completing the occupational 

handler risk assessments. Each assumption and factor is detailed below on an individual basis. 

Application Rate: 

The maximum single application rate listed on the Resolve® SG Herbicide [EPA Reg. No. 352-

748] label is 0.031 lb ai/A, and is considered protective of the proposed application rates listed 

on the Steadfast®XP 15% SG [352-816] label. 

Unit Exposures: 

It is the policy ofHED to use the best available data to assess handler exposure. Sources of 

generic handler data, used as surrogate data in the absence of chemical-specific data, include 

PHED 1.1 and the AHETF database. Some of these data are proprietary (e.g., AHETF data), and 

subject to the data protection provisions ofFIFRA. The standard values recommended for use in 

predicting handler exposure that are used in this assessment, known as "unit exposures", are 

outlined in the "Occupational Pesticide Handler Unit Exposure Surrogate Reference Table4", 

which, along with additional information on HED policy on use of surrogate data, including 

descriptions of the various sources, can be found at the Agency website5

. 

Area Treated or Amount Handled: 

The area treated or amount handled is based on guidance in HED ExpoSAC Policy 9.1. Refer to 

Table 6.1.1 for these assumptions for each scenario. 

Exposure Duration: 

HED classifies exposures from 1 to 30 days as short-term and exposures 30 days to six months 

as intermediate-term. Exposure duration is determined by many things, including the exposed 

population, the use site, the pest pressure triggering the use of the pesticide, and the cultural 

practices surrounding that use site. For most agricultural uses, it is reasonable to believe that 

occupational handlers will not apply the same chemical every day for more than a one-month 

time frame; however, there may be a large agribusiness and/or commercial applicators who may 

apply a product over a period of weeks (e.g., completing multiple applications for multiple 

clients within a region). 

4 Available: http://www.epa.gov/oppOOOO I /science/handler-exposure-table.pdf 

5 A vai !able: http://www .epa. gov/pesticides/science/ hand ler-exposure-data.html 

Page II of 19 
According to the proposed label, one application on sorghum is allowed per year at the 

maximum rate of0.031 lb ai/A, resulting in short-term handler exposures. Two sequential 

applications may be made at a maximum seasonal rate of 0.031 lb ai/ A/growing season. HED 

typically assumes commercial applicators use rimsulfuron for longer durations (> 1 month). 

Since the short- and intermediate-term PODs are the same and therefore, only a short-term 

handler exposure was estimated which is considered protective of intermediate-term exposures. 

Long-term exposures are not expected; therefore, a long-term assessment was not conducted. 

Mitigation/Personal Protective Equipment: 

Estimates of dermal and inhalation exposure were calculated for various levels of PPE. Results 

are presented for labeled PPE which includes "baseline'' plus gloves, defined as a single layer of 

clothing consisting of a long sleeved shirt, long pants, shoes plus socks, and no respirator. The 

rimsulfuron product labels direct mixers, loaders, applicators and other handlers to wear longsleeved shirt, long pants, shoes, socks, and chemical- resistant gloves. 

Occupational Handler Exposure and Risk Estimate Equations 

The algorithms used to estimate exposure and dose for occupational handlers can be found in 

Appendix A. 

Combining Exposures/Risk Estimates: 

Dermal and inhalation risk estimates were combined in this assessment, since the toxicological 

effects for these exposure routes were similar. Dermal and inhalation risk estimates were 

combined using the following formula: 

Total MOE ; Point of Departure (mg!kglday) 7 Combined dermal+ inhalation dose (mglkg/day) 

Summary of Occupational Handler Non-Cancer Exposure and Risk Estimates 

All of the MOEs for the occupational handler's dermal, inhalation, and combined exposures are greater 

than 100 at labeled PPE and therefore are not of concern. Table 6.1.1 summarizes the rimsulfuron 

occupational handler exposures and risks. 

The Agency matches quantitative occupational exposure assessment with appropriate 

characterization of exposure potential. While HED presents quantitative risk estimates for human 

flaggers where appropriate, agricultural aviation has changed dramatically over the past two 

decades. According the 2012 National Agricultural Aviation Association (NAAA) survey of 

their membership, the use of GPS for swath guidance in agricultural aviation has grown steadily 

from the mid 1990's. Over the same time period, the use of human flaggers for aerial pesticide 

applications has decreased steadily from 15 % in the late 1990's to only 1% in the most recent 

(20 12) NAAA survey. The Agency will continue to monitor all available information sources to 

best assess and characterize the exposure potential for human flaggers in agricultural aerial 

applications. 

HED has no data to assess exposures to pilots using open cockpits. The only data available is for 

exposure to pilots in enclosed cockpits. Therefore, risks to pilots are assessed using the 

engineering control (enclosed cockpits) and baseline attire (long-sleeve shirt, long pants, shoes, 

and socks); per the Agency's Worker Protection Standard stipulations for engineering controls, 

Page 12 of 19 
pilots are not required to wear protective gloves for the duration of the application. With this 

level of protection, there are no risk estimates of concern for applicators. 

Page 13 of 19 
Table 6.1.1. STand lT Occupational Handler Exposure and Risk Estimates for Rimsulfuron 

Dermal Unit Inhalation Unit 

Exposure Exposure Maximum Area Dermal Inhalation 

Exposure Scenario Crop (Jlg/lb ai)1 (Jlg/lb ai)1 Application 

Rate2 

Baseline 

Basel (lb ai/A) ine+ Gloves (no respirator) 

Aerial (SG form.) Sorghum 51.6 8.96 

Groundboom (SG form.) 51.6 8.96 

Aerial (liquid form.) Sorghum 2.08 0.0049 

Groundboom (liquid form.) 16.1 0.34 

Flagger Sorghum 12.0 0.35 

Based on the "Occupational Pesticide Handler Unit Exposure Surrogate Reference Table 

Based on registered or proposed label (Reg. No. 352-748) 

3 Exposure Science Advisory Council Policy #9.1. 

Mixer/Loader 

0.031 

O.D31 

Applicator 

0.031 

O.D3 1 

Flagger 

0.03 1 

Treated 

Dailr 

(A/day) Dose MOE5 Dose 

(mglkglday)4 (mglkglday)6 

1200 0.024 260 0.0042 

200 0.0040 1,600 0.00070 

1200 0.00094 6,700 0.0000022 

200 0.0013 5,000 0.000027 

350 0.0016 3,800 0.000048 

4 Dermal Dose = Dermal Unit Exposure (f.lg/lb ai) x Conversion Factor (0.001 mg/)Jg) x Application Rate (lb ai/acre) x Area Treated (Nday) x DAF {100%) + BW (80kg). 

5 Dem1al MOE = Dermal NOAEL (6.25 mg!kg/day) + Dermal Dose (mg/kg/day). 

6 Inhala tion Dose = Inhalation Unit Exposure (j.tg/lb ai) x Conversion Factor (0.001 mg/~tg) x Application Rate (lb ai/acre) x Area Treated (Nday) + BW (80kg). 

7 Inhalation MOE = Inhalation NOAEL (6.25 mg!kg!day) +Inhalation Dose (mg/kg!day). 

8 Total MOE= NOAEL (mg/kg/day) + Dermal Dose + Inhalation Dose. 

Page 14 of 19 

MOE7 

1,500 

9,000 

2,800,000 

240,000 

130,000 

• 

Total i 

! 

MOE8 

220 j 

1,400 

6,700 

1,000 

3,800 
6.2 Occupational Post-application Exposure/Risk Estimates 

HED uses the term post-application to describe exposures that occur when individuals are 

present in an environment that has been previously treated with a pesticide (also referred to as reentry exposure). Such exposures may occur when workers enter previously treated areas to 

perform job functions, including activities related to crop production, such as scouting for pests 

or harvesting. Post-application exposure levels vary over time and depend on such things as the 

type of activity, the nature of the crop or target that was treated, the type of pesticide application, 

and the chemical's degradation properties. In addition, the timing of pesticide applications, 

relative to harvest activities, can greatly reduce the potential for post-application exposure. 

6.2.1 Occupational Post-application Inhalation Exposure/Risk Estimates 

Based on the Agency's current practices, a quantitative post-application inhalation exposure 

assessment was not performed for rimsulfuron at this time primarily because of the low acute 

inhalation toxicity (Toxicity Category IV), low vapor pressure (1.13xl0-8 mm Hg at 25 °C), and 

the low proposed use rate (0.031 lb ai/ A). However, there are multiple potential sources of postapplication inhalation exposure to individuals performing post-application activities in 

previously treated fields. These potential sources include volatilization of pesticides and 

resuspension of dusts and/or particulates that contain pesticides. The Agency sought expert 

advice and input on issues related to volatilization of pesticides from its Federal Insecticide, 

Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP) in December 2009, and 

received the SAP's final report on March 2, 20106. The Agency is in the process of evaluating 

the SAP report as well as available post-application inhalation exposure data generated by the 

ARTF and may, as appropriate, develop policies and procedures, to identify the need for and, 

subsequently, the way to incorporate occupational post-application inhalation exposure into the 

Agency's risk assessments. If new policies or procedures are put into place, the Agency may 

revisit the need for a quantitative occupational post-application inhalation exposure assessment 

for rimsulfuron. 

Although a quantitative occupational post-application inhalation exposure assessment was not 

performed, an inhalation exposure assessment was performed for occupational/commercial 

handlers. Handler exposure resulting from application of pesticides outdoors is likely to result in 

higher exposure than post-application exposure. Therefore, it is expected that these handler 

inhalation exposure estimates would be protective of most occupational post-application 

inhalation exposure scenarios. 

6.2.2 Occupational Post-application Dermal Exposure/Risk Estimates 

Occupational Post-application Dermal Exposure Data and Assumptions 

A series of assumptions and exposure factors served as the basis for completing the occupational 

post-application risk assessments. Each assumption and factor is detailed below on an individual 

basis. 

6 Available: http://www .epa.gov/scipoly/SAP/meetings/2009/ 120 I 09meeting.htm I 

Page 15 of 19 
Exposure Duration: 

HED classifies exposures from 1 to 30 days as short-term and exposures 30 days to six months 

as intermediate-term. For rimsulfuron, based on the proposed sorghum use, short- and 

intermediate-exposures are expected. 

Transfer Coefficients: 

It is the policy of HED to use the best available data to assess post-application exposure. 

Sources of generic post-application data, used as surrogate data in the absence of chemicalspecific data, are derived from ARTF exposure monitoring studies, and, as proprietary data, are 

subject to the data protection provisions of FIFRA. The standard values recommended for use in 

predicting post-application exposure that are used in this assessment, known as "transfer 

coefficients", are presented in the ExpoSAC Policy 37

" which, along with additional information 

about the ARTF data, can be found at the Agency website8• 

Table 6.2.2.1. Anticipated Post-Application Activities and Dermal Transfer Coefficients. 

Policy Crop Crop Foliage Transfer 

Proposed Crops Group Coefficients Activities 

Category Height Density (cm2/hr) 

High Full 210 Scouting Field I row Low Full Sorghum, grain crop, tall High Full 

Low Full 70 Hand weeding 

Application Rate: 

The maximum single application rate listed on the Resolve® SG Herbicide [EPA Reg. No. 352-

748] label is 0.031 lb ai/A, and is considered protective ofthe proposed application rates listed 

on the Steadfast®XP 15% SG [352-816] label. 

Exposure Time: 

The average occupational workday is assumed to be 8 hours. 

Dislodgeable Foliar Residues: 

Chemical-specific dislodgeable foliar residue data have not been submitted for rimsulfuron. 

Therefore, this assessment uses HED's default assumption that 25% of the application is 

available for transfer on day 0 following the application and the residues dissipate at a rate of 

10% each following day. 

Occupational Post-application Dermal Exposure and Risk Estimate Equations 

The algorithms used to estimate non-cancer exposure and dose for occupational post-application 

workers can be found in Appendix A. 

7 Available: http://www.epa.gov/pesticides/science/exposac policy3.pdf 8 Available: http://www.epa.gov/pesticides/science/post-app-exposure-data.html 

Page 16 of 19 
Occupational Post-application Dermal Risk Estimates 

The dermal MOEs for each activity scenario using default assumptions are above the LOC of 

100 on Day 0 and therefore, are not of concern (Table 6.2.2.2). Furthermore, a DFR study is not 

required for rimsulfuron at this time since the dermal MOE is greater than 4 times the LOC 

based on default values for the fraction of application rate available for transfer after a foliar 

application. This decision of not requesting a DFR study may need to be reconsidered if there is 

a change in use patterns for rimsulfuron. 

Table 6.2.2.2. Occupational Post-application Non-Cancer Exposure and Risk Estimates for Rimsulfuron. 

Crop/Site Activities Transfer Coefficient DFR1 Dermal Dose MOE3 

(cm2/hr) (mg/kg/day)2 

Short- and Intermediate- term 

Sorghum Scouting 210 0.0869 0.0018 3,400 

Hand Weeding 70 0.0869 0.00061 10,000 

I DFR = Application Rate x F x (I·D)' x 4.54E8 j.tg/lb x 2.47E·8 acre/e ; where F = 0.25 and D = 0.10 per day 

2 Daily Dermal Dose= (DFR (j.tg/cm2

) x Transfer Coefticient x 0.001 mg/j.tg )< Slus/day x dermal absorption (100%)) + BW (80kg). 

3 MOE= POD (6.5 mg!kg/day) I Daily Dermal Dose. 

Restricted Entry Interval 

The currently registered product label lists a REI of 4 hours. PR Notice 95-03 on the Reduced 

REI policy (3-May-1995) does not list rimsulfuron as an active ingredient approved for a 4-hour 

REI. However, PR 95-03 allows a 4-hour REI provided that end-use products meet the 

following reduced risk criteria: 

(1) The active ingredient is in Toxicity Category III or IV based upon data for acute dermal 

toxicity, acute inhalation toxicity, primary skin irritation, and primary eye irritation. 

(2) The active ingredient is not a dermal sensitizer. 

(3) The active ingredient is not a cholinesterase inhibitor. 

( 4) The active ingredient is not associated with known reproductive, developmental, 

carcinogenic, or neurotoxic effects. 

(5) EPA does not possess incident information that is "definitely" or "probably" related to 

the post-application exposures to the active ingredient. 

The label REI is typically based on the acute toxicity of technical chemical. Under the WPS, 

active ingredients classified as Toxicity Category IV for Acute Dermal and Primary Skin 

Irritation are assigned a 4-hour REI; therefore, the 4-hour REI on the proposed label is 

acceptable and considered appropriate to protect agricultural workers from post-application 

exposures to rimsul furon. 

Page 17 of 19 
Appendix A. Summary of Occupational and Residential Non·cancer Algorithms 

Occupational Handler Algorithms 

Potential daily exposures for occupational handlers are calculated using the following formulas: 

where: 

E 

UE 

AR 

A 

= 

= 

= 

E=UE * AR *A* 0.001 mg/ug 

exposure (mg ai/day), 

unit exposure (!lg ai/lb ai), 

maximum application rate according to proposed label (lb ai A or lb ailgal), and 

area treated or amount handled (e.g., A/day, gal/day). 

The daily doses are calculated using the following formula: 

where: 

ADD = 

E = 

AF 

BW = 

ADD= 

E*AF 

BW 

average daily dose absorbed in a given scenario (mg ai/kg/day), 

exposure (mg ai/day), 

absorption factor (dermal and/or inhalation), and 

body weight (kg). 

Margin of Exposure: Non-cancer risk estimates for each application handler scenario are 

calculated using a Margin of Exposure (MOE), which is a ratio of the toxicological endpoint to 

the daily dose of concern. The daily dermal and inhalation dose received by occupational 

handlers are compared to the appropriate POD (i.e., NOAEL) to assess the risk to occupational 

handlers for each exposure route. All MOE values are calculated using the following formula: 

where: 

MOE = 

POD 

ADD = 

POD 

A10E= ADD 

margin of exposure: value used by HED to represent risk estimates (unitless), 

point of departure (mglkg/day), and 

average daily dose absorbed in a given scenario (mg ailkg/day). 

Occupational Post-application Algorithms 

Potential daily exposures for occupational post-application workers are calculated using the 

following formulas: 

DFR,=AR * F*(l-D/*(4.54£8~!) *(2.47E-8 c~ ) 

Page 18 of 19 
where: 

DFRt 

AR 

F 

D 

t 

where: 

E 

TC 

DFRt 

ET 

= 

= 

= 

= 

= 

= 

dislodgeable foliage residue on day "t" (~-tg/cm ), 

application rate (lb ai/acre), 

fraction of ai retained on foliage or 25% (unitless), 

fraction of residue that dissipates daily or 10% (unitless), and 

number of days after application day (days). 

E=TC * DFR 1 * ET * 0.001 mg 

ug 

exposure (mg ai/day), 

transfer coefficient (cm2

/hr), 

dislodgeable foliar residue on day "t" (!lg/cm2), and 

exposure time (hours/day). 

The daily doses are calculated using the following formula: 

where: 

ADD = 

E 

AF = 

BW = 

ADD= 

E*AF 

BW 

average daily dose absorbed in a given scenario (mg ai/kg/day), 

exposure (mg ai/day), 

absorption factor (dermal and/or inhalation), and 

body weight (kg). 

Margin of Exposure: Non-cancer risk estimates for each scenario are calculated using a Margin 

of Exposure (MOE), which is a ratio of the toxicological endpoint to the daily dose of concern. 

The daily dermal dose received by occupational post-application workers is compared to the 

appropriate POD (i.e., NOAEL) to assess the risk to occupational post-application workers. All 

MOE values are calculated using the following formula: 

where: 

MOE = 

POD 

ADD = 

POD 

MOE= ADD 

margin of exposure: value used by HED to represent risk estimates (unitless), 

point of departure (mg/kg/day), and 

average daily dose absorbed in a given scenario (mg ai/kg/day). 

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