                 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                         WASHINGTON, D.C. 20460      

                                                     	OFFICE OF CHEMICAL SAFETY
                                                      	AND POLLUTION PREVENTION
	


Date:	May 15, 2017							
					
Subject:	Rimsulfuron.  Occupational and Residential Exposure Assessment for New Use or Registration Requests for Grasses Grown for Seed and Cranberry. 

PC Code: 129009
DP Barcode:  D438172
Decision No.: 519986
Registration No.: 66222-184, 352-768
Petition No.: 6E8496
Regulatory Action: Section 3 Registration
Risk Assessment Type: Occupational Exposure Assessment
Case No.: NA
TXR No.: NA
CAS No.: 122931-48-0
MRID No.: NA
40 CFR: §180.478


From:	Laura Bacon, Biologist
	Risk Assessment Branch III (RAB3)
	Health Effects Division (7509P)

Through:	Barry O'Keefe, Biologist
	RAB3
	Health Effects Division (7509P)
	
	and

	Ume Hassan, ExpoSAC Reviewer #1
	Lata Venkateshwara, ExpoSAC Reviewer #2
	Exposure Science Advisory Committee (ExpoSAC) / HED
	
To:	Sidney Jackson, Minor Use Team
	Minor Use and Emergency Response Branch 
	Registration Division (7505P)

Introduction		

The Registration Division (RD) requested that the Health Effects Division (HED) conduct an exposure and risk assessment to evaluate the hazard and exposure data and conduct an occupational and residential exposure assessment, as needed, to estimate the risks to human health that will result from the proposed uses or registration requests for rimsulfuron on grasses grown for seed and cranberry.  

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, including Pesticide Handlers Exposure Database Version 1.1 (PHED 1.1) and the Agricultural Handler Exposure Task Force (AHETF) 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 May 4, 2017.
                               Table of Contents

1.0 Executive Summary	4
2.0 Risk Assessment Conclusions and Recommendations	5
2.1 Summary of Risk Estimates	5
2.2 Label Recommendations from Occupational Assessment	5
3.0 Hazard Characterization	6
4.0 Use Profile	7
5.0 Residential Exposure and Risk Estimates	8
6.0 Non-Occupational Spray Drift Exposure and Risk Estimates	8
7.0 Non-Occupational Bystander Post-Application Inhalation Exposure and Risk Estimates	9
8.0 Occupational Exposure and Risk Estimates	9
8.1 Occupational Handler Exposure/Risk Estimates	9
8.2 Occupational Post-Application Exposure/Risk Estimates	13
8.2.1 Occupational Post-application Inhalation Exposure/Risk Estimates	13
8.2.2 Occupational Post-application Dermal Exposure/Risk Estimates	13
Appendix A.  Summary of Occupational and Residential Non-cancer Algorithms	15

1.0 Executive Summary

Rimsulfuron is a systemic herbicide belonging to the sulfonylurea group that is used for pre- and post-emergent control of annual grasses, broadleaf weeds, and yellow nutsedge. It has been registered for use on bushberries, caneberries, grape, citrus, tree nuts, pome fruits, stone fruits, corn, chicory, and non-cropland areas (e.g., professional and college sports fields, commercial turf, golf courses, roadsides, industrial sites, utility substations and rangeland).

Proposed Uses
DuPont Crop Protection (DuPont) has submitted a petition for the active ingredient (ai), rimsulfuron, for a new use on grasses grown for seed (fescue and perennial ryegrass) and to add grasses grown for seed (Oregon and Washington only) to the DuPont(TM) Matrix(R) SG Herbicide (EPA Reg. No. 352-768) end-use product label at a single maximum application rate of 0.048 lb ai/A; and to add cranberry to the Pruvin(R) Herbicide (EPA Reg. No. 66222-184) end-use product label at a single maximum application rate of 0.031 lb ai/A. Pruvin(R) Herbicide is a dry flowable formulation and DuPont(TM) Matrix(R) SG is a water soluble granule formulation; both products contain 25% of the ai rimsulfuron. These products direct mixers, loaders, applicators and other handlers to wear a long-sleeved shirt and long pants; chemical-resistant gloves made of any waterproof material; and shoes plus socks. The restricted entry interval (REI) listed on both end-use product labels is 4 hours.

Exposure Profile
For this action, occupational exposures to rimsulfuron are expected for short- and intermediate-term durations from handling and post-application activities. Potential routes of exposure include both dermal and inhalation. 

Hazard Characterization
The adequacy of the rimsulfuron toxicity database is considered complete. Short- and intermediate-term inhalation risks are based on systemic effects observed from a 90-day oral toxicity study in dogs. A dermal endpoint was not selected for risk assessment because rimsulfuron is not expected to be toxic through the dermal route. No quantitative or qualitative evidence of increased susceptibility was identified following pre- and/or postnatal exposures of rimsulfuron in rats or rabbits. There is no genotoxicity, neurotoxicity, or immunotoxicity concerns observed in the available toxicity studies. The data requirements for a dermal toxicity study and a subchronic inhalation toxicity study have been waived (J. Van Alstine, TXR 0050008, 4/26/2012; K. Rury, TXR 0056438, 9/17/2012). Rimsulfuron is "not likely to be carcinogenic to humans." The level of concern (LOC) for all routes and durations of exposure for occupational exposure and risk assessment is a margin of exposure (MOE) of 100.

Residential Handler and Post-Application Exposure and Risk Estimates 
Rimsulfuron is registered for use on non-residential athletic fields and other non-residential non-cropland areas. While there is the potential for post-application exposures to rimsulfuron (e.g., treated turf on golf courses), the dermal route of exposure has not been assessed because there is no adverse systemic hazard resulting from dermal exposures to rimsulfuron. Therefore, a residential exposure assessment has not been conducted. 


Occupational Handler Exposure and Risk Estimates
There are no occupational risk estimates of concern associated with the proposed uses of rimsulfuron. The dermal route of exposure has not been assessed because there is no adverse systemic hazard resulting from dermal exposures to rimsulfuron.  The occupational handler inhalation risk estimates quantified in this assessment resulted in MOEs between 990 to 1,800,000, and are not of concern (LOC = 100). Because the short- and intermediate-term inhalation points of departure (PODs) are the same, short-term occupational exposure risk estimates are protective of the intermediate-term duration of exposure. 

Occupational Post-Application Exposure and Risk Estimates
The dermal route of exposure has not been assessed because there is no adverse systemic hazard resulting from dermal exposures to rimsulfuron. 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.

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 PHED 1.1 and the AHETF 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.  

2.0 Risk Assessment Conclusions and Recommendations

2.1 Summary of Risk Estimates

There are no occupational risk estimates of concern associated with the proposed new uses of rimsulfuron. The occupational inhalation risk estimates quantified in this assessment resulted in MOEs between 990 to 1,800,000, and are not of concern (LOC = 100). Because the short- and intermediate-term inhalation PODs are the same, short-term occupational exposure risk estimates are protective of intermediate-term exposure risk estimates. 

Although occupational dermal exposure is expected following treatment of agricultural crops, dermal hazard was not identified for rimsulfuron. Therefore, quantitative dermal risk assessments for occupational handlers or post-application workers were not conducted for the proposed use of rimsulfuron.  

2.2 Label Recommendations from Occupational Assessment 

Matrix(R) SG Herbicide (EPA Reg. No. 352-768) proposes a single maximum application rate of 0.048 lb ai/A. However, the calculated maximum application rate is 0.047 lb ai/A based upon information stated on the label. This discrepancy should be clarified on the label. 

3.0 Hazard Characterization

Acute Toxicity
Technical rimsulfuron has low acute 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 of Rimsulfuron
                                 Guideline No.
                                  Study Type
                                    Results
                               Toxicity Category
870.1100
Acute oral  -  rat
LD50 = > 5000 mg/kg
                                      IV
870.1200
Acute dermal  -  rat
LD50 = > 2000 mg/kg
                                      IV
870.1300
Acute inhalation  -  rat
LC50 = > 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 
                                      --

Toxicological PODs Used for Risk Assessment
The endpoints and PODs remain unchanged since the last completed risk assessment for rimsulfuron (M. Mercado-Feliciano, D425703, 09/14/2015). It should be noted that studies used for endpoint selection have conservative No Observed Adverse Effect Level/Lowest Observed Adverse Effect Level (NOAEL/LOAEL) values that have not been updated to reflect current standards for evaluating toxicity studies. Updates would result in higher NOAEL/LOAEL values and, given the current risk picture, updates would not impact the overall findings of the risk assessment.

The toxicity database for rimsulfuron indicates that target organs are the liver and kidney in the rat and dog, along with the testes 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. No quantitative or qualitative evidence of increased susceptibility was identified following pre- and/or postnatal exposures of rimsulfuron in rats or rabbits. There was no evidence of neurotoxicity or immunotoxicity in the database. The data requirements for a dermal toxicity study and a subchronic inhalation toxicity study have been waived (J. Van Alstine, TXR 0050008, 4/26/2012; K. Rury, TXR 0056438, 9/17/2012). 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.

The endpoint for inhalation risk assessments for occupational workers was chosen from the 90-day oral study in the dog, and was based on kidney effects. A dermal endpoint was not selected for risk assessment because: (1) rimsulfuron has low acute dermal toxicity; (2) there is no qualitative or quantitative offspring susceptibility in the toxicity database, (3) most sulfonylureas for which guideline dermal studies were submitted to the Agency showed no effects through the dermal route up to the limit dose; and (4) dermal absorption is generally low (DAF < 20%) for sulfonylureas. 
For all routes and durations for the occupational exposure and risk assessment, the resulting LOC is an MOE of 100. Table 3.2 provides a detailed summary of the toxicity endpoints and PODs selected for the occupational exposure risk assessment for rimsulfuron.


Table 3.2.  Summary of Toxicity Endpoints and Points of Departure for Rimsulfuron for Use in Occupational Risk Assessment.
                                   Exposure
                                   Scenario
                              Point of Departure
                                 Uncertainty/
                              FQPA Safety Factors
                RfD, PAD, Level of Concern for Risk Assessment
                        Study and Toxicological Effects
Inhalation Exposure: Short- and Intermediate-Term
NOAEL= 6.25 mg/kg /day
Inhalation toxicity assumed to be equivalent to oral toxicity.
UFA = 10X
UFH = 10X
Occupational LOC for MOE = 100
90-day toxicity study  -  Dog
LOAEL = 125 mg/kg/day based on increased urinary volume, kidney weights, and decreased osmolality.
Dermal Exposure: Short- and Intermediate-Term
A dermal endpoint was not selected because rimsulfuron is not expected to be toxic through the dermal route.
Cancer (oral, dermal, inhalation)
Not a carcinogen based on the lack of evidence of carcinogenicity in rats and mice.
UF = uncertainty factor, FQPA SF = FQPA safety factor, NOAEL = no observed adverse effect level, LOAEL = lowest observed adverse effect level, MOE = margin of exposure, LOC = level of concern.  

Absorption
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 

Rimsulfuron is proposed for the pre- and post-emergent control of certain grasses and broadleaves/sedges for cranberry. Rimsulfuron is proposed to control seedling annual bluegrass, annual and perennial ryegrass, volunteer wheat and roughstock bluegrass in grasses grown for seed (fescue and ryegrass) in the states of Oregon and Washington, only. Table 4.1 provides a summary of the proposed use directions.

Table 4.1.  Summary of Directions for Use of Rimsulfuron.
                       Applic. Timing, Type, and  Equip.
                    Trade Name; Formulation [EPA Reg. No.]
                                 Max. Single 
Application Rate 
                          Max. No. Applic. per Season
                           Max. Annual Applic. Rate 
                                  PHI (days)
                        Use Directions and Limitations
                                 Cranberry[2]
                Pre- or post-emergence broadcast or chemigation
                            Pruvin(R); dry flowable
                                   (25% ai)
                                  [66222-184]
                       2.0 oz product/A (0.031 lb ai/A)
                                       2
                  4.0 oz product/A/year (0.063 lb ai/A/year)
                                      60
21-day retreatment interval (RTI); A spray adjuvant must be added with each application. For chemigation, do not apply by flood or drip irrigation. Do not apply in a spray solution with a pH below 4 or above 8. Do not apply by air.
                Grasses grown for seed (Fescue and Ryegrass)[3]
                       Pre-emergence ground broadcast[1]
                   Matrix(R); water soluble granule (25% ai)
                                   [352-768]
                       3.0 oz product/A (0.048 lb ai/A)
                                       1
                     3.0 oz product/A/year (0.048 lb ai/A)
                                      NA
For use in Oregon and Washington only. Recommended for use in conjunction with carbon planted Perennial Ryegrass and Tall Fescue grown for seed. Do not apply through any type of irrigation system.
1 Because aerial applications were not prohibited on the supplemental label for EPA Reg. No. 352-768, that use pattern was also assessed for grass grown for seed.
[2] Cranberry = field crop, typical
3 Grasses grown for seed (fescue and ryegrass) = field crop, high-acreage

5.0 Residential Exposure and Risk Estimates

Residential exposures are not anticipated from the proposed uses of rimsulfuron. Rimsulfuron is registered for use on non-residential athletic fields and other non-residential non-cropland areas. While there is the potential for post-application exposures to rimsulfuron (e.g., treated turf on golf courses), the dermal route of exposure has not been assessed because there is no adverse systemic hazard resulting from dermal exposures to rimsulfuron. Therefore, a residential exposure assessment has not been conducted. 

6.0 Non-Occupational Spray Drift Exposure and Risk Estimates
      
Spray drift is a potential source of exposure to those nearby pesticide applications. This is particularly the case with aerial application, but, to a lesser extent, spray drift can also be a potential source of exposure from the ground application methods (e.g., groundboom and airblast) employed for rimsulfuron. The Agency has been working with the Spray Drift Task Force (a task force composed of various registrants which was developed as a result of a Data Call-In issued by EPA), EPA Regional Offices and State Lead Agencies for pesticide regulation and other parties to develop the best spray drift management practices (see the agency's Spray Drift website for more information).  The Agency has also developed a policy on how to appropriately consider spray drift as a potential source of exposure in risk assessments for pesticides. 

Rimsulfuron is registered on multiple agricultural use sites, as well as on non-agricultural use sites that could result in spray drift. The potential for spray drift was previously quantitatively evaluated for rimsulfuron during the Registration Review process; incidental oral risk estimates from drift onto residential areas were evaluated for rimsulfuron using the maximum registered application rate of 0.063 lb ai/A on non-crop use sites (i.e., airports, highway, railroad, and utility rights of way; sewage disposal areas, uncultivated agricultural areas; non-crop producing areas). Children's (1 to <2 year old) incidental oral risk estimates from indirect exposure to rimsulfuron related to spray drift resulted in no risks of concern at field edge; the resulting MOEs were 25,000 to 35,000 (MOEs > 100). Dermal risk estimates were not calculated because there was no dermal hazard identified in the rimsulfuron database. This current action is not expected to result in increased spray drift potential exposures. Further information may be found in the draft risk assessment for Registration Review of rimsulfuron (M. Mercado-Feliciano, D425703, 09/14/2015).   

7.0 Non-Occupational Bystander Post-Application Inhalation Exposure and Risk Estimates

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, 2010 (http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2009-0687-0037). The Agency has evaluated the SAP report and has developed a Volatilization Screening Tool and a subsequent Volatilization Screening Analysis (http://www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2014-0219).  
During Registration Review, the agency will utilize this analysis to determine if data (i.e., flux studies, route-specific inhalation toxicological studies) or further analysis is required for rimsulfuron.

8.0 Occupational Exposure and Risk Estimates

8.1 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. The quantitative exposure/risk assessment developed for occupational handlers is based on the methods of application and includes aerial, chemigation, groundboom, and handheld equipment. Refer to Table 8.1.1. for a detailed list of each occupational exposure scenario.

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 proposed application rate information is provided in Table 4.1.

Unit Exposures:  It is the policy of HED 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, the AHETF database, the Outdoor Residential Exposure Task Force (ORETF) database, or other registrant-submitted occupational exposure studies.  Some of these data are proprietary (e.g., AHETF data), and subject to the data protection provisions of FIFRA.  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 Table", 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 website. 

Area Treated or Amount Handled:  The daily areas treated or amounts handled were defined for each handler scenario (in appropriate units) by determining the amount that can be reasonably treated by an individual in a single day. When possible, the assumptions for daily areas treated or amounts handled are taken from the HED's ExpoSAC Policy 9.1: "Standard Values for Daily Acres Treated in Agriculture". The values used for area treated may be found in Table 8.1.1.

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). Based on the proposed uses, short- and intermediate-term exposures to rimsulfuron are expected. The proposed use directions for the DuPont(TM) Matrix(R) SG Herbicide end-use product allow one application to grass grown for seed per year. The proposed use directions for the Pruvin(R) Herbicide Dry Flowable end-use product specifies up to two applications on cranberry with a 21-day retreatment interval. Therefore, long-term exposures are not expected.
  
Mitigation/Personal Protective Equipment:  Inhalation exposure estimates were calculated for various levels of exposure. Results are presented for "baseline," defined as a single layer of clothing consisting of a long sleeved shirt, long pants, shoes plus socks, no protective gloves, and no respirator. The rimsulfuron end-use products associated with this assessment direct mixers, loaders, applicators and other handlers to wear long-sleeved shirt and long pants; chemical-resistant gloves made of any waterproof material; and shoes plus socks. 

Occupational Handler Non-Cancer Exposure and Risk Estimate Equations
The algorithms used to estimate non-cancer exposure and dose for occupational handlers can be found in Appendix A.

Summary of Occupational Handler Non-Cancer Exposure and Risk Estimates
The results of the occupational handler exposure and risk assessment resulting from the proposed use of rimsulfuron are presented in Table 8.1.1. and indicate that short-term inhalation risks do not exceed HED's LOC (i.e. an MOE < 100 for short- and intermediate-term exposures) with baseline attire without PPE (i.e., no respirator). The inhalation MOEs ranged between 990 and 1,800,000; and therefore are not of concern. Because the short- and intermediate-term inhalation PODs are the same for occupational exposures, the assessment is protective of both short- and intermediate-term exposures. 

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, 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.

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 (2012) 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.





Table 8.1.1.  Occupational Handler Non-Cancer Exposure and Risk Estimates for Rimsulfuron.
                               Exposure Scenario
                               Crop or Target[1]
                               Level of Concern
                    Inhalation Unit Exposure (μg/lb ai)[2]
                                    Maximum
                              Application Rate[3]
                    Area Treated or Amount Handled Daily[4]
                                  Inhalation
                                       
                                       
                                       
                                       
                                       
                                       
                              Dose (mg/kg/day)[5]
                                    MOE[6]
                                 Mixer/Loader
                             Chemigation Broadcast
                              Field crop, typical
                                      100
                                     8.96
                                 0.031 lb ai/A
                                     350 A
                                    0.00123
                                     5,100
                             Groundboom Broadcast
                              Field crop, typical
                                       
                                       
                                 0.031 lb ai/A
                                     80 A
                                    0.00028
                                    22,000
                                       
                           Field crop, high-acreage
                                       
                                       
                                 0.047 lb ai/A
                                     200 A
                                    0.00105
                                     6,000
                               Aerial Broadcast
                           Field crop, high-acreage
                                       
                                       
                                 0.047 lb ai/A
                                    1,200 A
                                    0.0063
                                      990
                                  Applicator
                             Groundboom Broadcast
                              Field crop, typical
                                      100
                                     0.34
                                 0.031 lb ai/A
                                     80 A
                                   0.0000106
                                    590,000

                           Field crop, high-acreage
                                       
                                       
                                 0.047 lb ai/A
                                     200 A
                                   0.0000399
                                    160,000
                               Aerial Broadcast
                           Field crop, high-acreage
                                       
                                    0.0049
                                 0.047 lb ai/A
                                    1,200 A
                                  0.00000345
                                   1,800,000
                                    Flagger
                               Aerial Broadcast
                           Field crop, high-acreage
                                      100
                                     0.35
                                 0.047 lb ai/A
                                     350 A
                                   0.0000718
                                    87,000
                            Mixer/Loader/Applicator
Mechanically-pressurized Handgun Broadcast (foliar) or Drench/Soil/Ground-directed
                              Field crop, typical
                                      100
                                     8.68
                               0.0031 lb ai/gal
                                   1,000 gal
                                   0.000339
                                    18,000
 Field crop, typical = cranberry; Field crop, high acreage = grass grown for seed. 
2	Based on the "Occupational Pesticide Handler Unit Exposure Surrogate Reference Table" (https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/occupational-pesticide-handler-exposure-data); Level of mitigation: Baseline (single layer clothing, no respirator) for all scenarios except for aerial broadcast applicators, for which only closed cockpit data are available = Engineering Controls.
3	Typical crop proposed new use for EPA Reg. No. 66222-184; high-acreage crop proposed new use for EPA Reg. No. 352-768.
4	Exposure Science Advisory Council Policy #9.1. Area treated in acres except for the Mixer/Loader/Applicator scenario, for which the amount treated/handled is in gallons.
5	Inhalation Dose = Inhalation Unit Exposure (μg/lb ai) x Conversion Factor (0.001 mg/μg) x Application Rate (lb ai/acre or gal) x Area Treated or Amount Handled Daily (A or gal/day) / BW (80 kg). 
6	Inhalation MOE = Inhalation NOAEL (mg/kg/day) / Inhalation Dose (mg/kg/day). ST/IT Inhalation NOAEL = 6.25 mg/kg/day. Level of concern = 100.

8.2 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 re-entry 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.

8.2.1 Occupational Post-application Inhalation Exposure/Risk Estimates

There are multiple potential sources of post-application 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, 2010 (http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2009-0687-0037 ). The Agency has evaluated the SAP report and has developed a Volatilization Screening Tool and a subsequent Volatilization Screening Analysis (https://www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2014-0219 ). During Registration Review, the agency will utilize this analysis to determine if data (i.e., flux studies, route-specific inhalation toxicological studies) or further analysis is required for rimsulfuron.

In addition, the Agency is continuing to evaluate the available post-application inhalation exposure data generated by the Agricultural Reentry Task Force. Given these two efforts, the Agency will continue to identify the need for and, subsequently, the way to incorporate occupational post-application inhalation exposure into the agency's risk assessments.

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, which are not of concern, would be protective of most occupational post-application inhalation exposure scenarios.

8.2.2 Occupational Post-application Dermal Exposure/Risk Estimates

Occupational post-application dermal exposures are expected following the use of rimsulfuron on cranberry and grasses grown for seed. However, an occupational post-application dermal exposure and risk assessment was not conducted because an adverse systemic dermal hazard was not identified for rimsulfuron. 

Restricted Entry Interval
The DuPont(TM) Matrix(R) SG Herbicide and Pruvin(R) Herbicide Dry Flowable end-use products list a REI of 4 hours. Based on the acute toxicity categories and post-application assessment for rimsulfuron, the Worker Protection Standard (WPS) Interim REI is 12-hours. REIs may be further reduced if certain criteria are met in accordance with the Pesticide Registration (PR) Notice 95-3 [Reduction of WPS Interim REIs for Certain Low Risk Pesticides]. In PR Notice 95-3, there are a set of criteria listed for the active ingredient that must be met for chemicals to be eligible for a reduced REI. Upon review of the criteria for the active ingredient only, it appears that rimsulfuron is consistent with the criteria in PRN 95-3 that allow for a 4-hour REI. 
HED notes that, if in the future, incident information is received by the Agency relating to the active ingredient and/or the end-use product, the eligibility for the 4-hr REI may need to be reevaluated. HED also notes that the PR Notice includes similar criteria for the end-use product. These criteria have not been evaluated by HED. Based solely on the active ingredient criteria, HED would recommend for the continued reduction of the REI for rimsulfuron. Further information about the criteria underlying the 4-hour REI determination for rimsulfuron is available in the Registration Review human health risk assessment (M. Mercado-Feliciano, D425703, 09/14/2015).


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

Occupational Non-cancer Handler Algorithms

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

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

where:

E	=	exposure  (mg ai/day),
UE	=	unit exposure (ug ai/lb ai),
AR	=	maximum application rate according to proposed label (lb ai A or lb ai/gal), and
A	=	area treated or amount handled (e.g., A/day, gal/day).
 
The daily doses are calculated using the following formula:

ADD=  E * AFBW


where:

ADD	= 	average daily dose absorbed in a given scenario (mg ai/kg/day),
E	=	exposure  (mg ai/day),
AF	=	absorption factor (inhalation), and
BW 	= 	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 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:


MOE= PODADD


where:

MOE	=	margin of exposure: value used by HED to represent risk estimates (unitless),
POD	=	point of departure (mg/kg/day), and
ADD	=	average daily dose absorbed in a given scenario (mg ai/kg/day).


