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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF CHEMICAL SAFETY AND

 POLLUTION PREVENTION

MEMORANDUM

DATE: March 19, 2011

SUBJECT: FLAZASULFURON: Occupational and Residential Exposure/Risk Assessment

for Use on Citrus, Grapes, Sugarcane, Christmas Trees, and Industrial Vegetation 

Management

PC Code: 119011 DP Barcode: D378633

Decision Number: 425253 Registration Number: 71512-RI

Petition Number: 9F7666 Regulatory Action: NA

Risk Assessment Type: NA Case Number: NA

TXR Number: NA CAS Number: 104040-78-0

MRID Numbers: NA 40CFR: NA

FROM: Cassi L. Walls, Ph.D., Senior Biologist

Risk Assessment Branch III

Health Effects Division (7509P)

THROUGH: Barry O’Keefe, ORE Team Leader

Risk Assessment Branch III

Health Effects Division (7509P)

TO: Cassi L. Walls, Ph.D., Risk Assessor

Risk Assessment Branch 3

Health Effects Division (7509P)

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

occupational exposure and risk assessment for proposed first food uses of flazasulfuron in/on

citrus, grapes, sugarcane and proposed uses on Christmas trees and industrial vegetation 

management areas.
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1.0 Executive Summary

Flazasulfuron is a herbicide for control of certain broadleaf weeds and grasses which acts by 

inhibiting the acetolactate synthase (ALS) biochemical process. It is currently registered for use 

on golf courses, sod farms, athletic fields, and commercial lawns. A Section 3 registration is 

being requested by ISK Biosciences Corporation for the proposed first new food uses of 

flazasulfuron in/on citrus, grapes and sugarcane. Additionally, flazasulfuron is also being 

proposed for use on Christmas trees and industrial vegetation management in nonagricultural 

areas. ISK has submitted an application to register these uses on the proposed label ISK 

Flazasulfuron Herbicide (EPA Reg. No. 71512-), which is a water dispersible granule

formulation containing a 25.0% active ingredient.

Proposed Use Profile:

ISK Flazasulfuron Herbicide is proposed for use on citrus, grapes, sugarcane, Christmas trees, 

and nonagricultural vegetation management areas. Soil directed spray application for citrus and 

grapes are proposed at rates of 0.033 – 0.045 lb ai/A/application with a maximum seasonal rate 

of 0.15 lb ai/A. Preharvest intervals (PHIs) are proposed at 1 day for citrus and 75 days for 

grapes. Over-the-top applications for sugarcane are proposed at rates of 0.014 – 0.023 lb 

ai/A/application with a retreatment interval (RTI) of 14 days. Post-directed applications for 

sugarcane are proposed at rates of 0.014 – 0.045 lb ai/A/application with a maximum seasonal 

rate of 0.15 lb ai/A. The proposed PHI for sugarcane is 180 days. Over-the-top and soil directed 

spray applications are proposed for Christmas trees at rates of 0.033 – 0.045 lb ai/A/application. 

Over-the-top applications must be made prior to spring bud break or when conifers are 

sufficiently hardened off. Application rates for vegetation management in nonagricultural areas 

are proposed at 0.047 lb ai/A/application with an RTI of 4 to 6 weeks. These applications many 

not be made near residential properties or near sensitive desired plants.

It should be noted that RTIs are currently not provided specifically for citrus, grapes, or 

Christmas trees while maximum seasonal rates are not provided for Christmas trees or 

nonagricultural areas. HED recommends that these use directions be included on the proposed 

label. 

Hazard Concerns: 

Short- and intermediate-term inhalation risks are based on systemic effects observed at the LOAEL of 

10 mg/kg/day (NOAEL of 2 mg/kg/day) from a 90-day oral toxicity study in dogs. No short- or 

intermediate-term dermal hazard was identified. Since the inhalation endpoint is not based on 

developmental effects, the average body weight of an adult (70 kilograms) was used in the exposure 

assessments. The cancer classification is “not likely to be carcinogenic to humans.” 

FQPA: The adequacy of the flazasulfuron toxicity database is considered complete. The 

flazasulfuron risk assessment team evaluated the quality of the toxicity and exposure data and, 

based on these data, recommended that the FQPA Safety Factor be reduced to 1X.

Occupational Exposure:
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Occupational short-term (1 - 30 days) and intermediate-term (1 - 6 months) dermal and

inhalation exposures are expected from flazasulfuron handler activities associated with both the 

proposed agricultural and Christmas tree uses. HED used data from the Pesticide Handlers 

Exposure Database (PHED) Version 1.1 as presented in the PHED Surrogate Exposure Guide 

(8/98) to assess handler exposures (HED Science Advisory Council for Exposure (ExpoSAC) 

Standard Operating Procedure (SOP) No. 7, dated 01/28/1999). Since no hazard was identified 

for the dermal route of exposure, dermal risks were not assessed. A Margin of Exposure (MOE) 

greater than 100 for the inhalation route is deemed adequate to protect occupational flazasulfuron 

handlers. All handler scenarios resulted in MOEs greater than the level of concern (LOC) (i.e., 

MOEs ≥ 100) for inhalation exposures and, therefore are not of concern. 

Agricultural Handlers:

Occupational short- and intermediate-term dermal exposures are expected from post-application 

activities. However, since no hazard was identified for the dermal route of exposure, dermal 

risks were not assessed

Agricultural Post-application:

Restricted Entry Interval: The ISK Flazasulfuron Herbicide label proposes a 4-hour reduced 

reentry interval (REI). In accordance with criteria for reduced REI candidates, an active 

ingredient cannot elicit reproductive, developmental, neurotoxic or carcinogenic effects. 

Flazasulfuron elicits developmental effects, and therefore cannot be a candidate for a reduced 

REI. Per the Worker Protection Standard (WPS), chemicals classified as Toxicity Categories III 

and IV require a 12-hr restricted entry interval (REI). HED recommends that RD ensure that the 

REI on the label be corrected to 12 hours.

Review of Human Research:

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 studies, which comprise of the 

Pesticide Handlers Exposure Database (PHED), have been determined to require a review of 

their ethical conduct and have received that review.

Residential Exposure:

This document only presents the assessment of the proposed new agricultural uses of 

flazasulfuron. No residential uses are being requested at this time; therefore, a residential risk 

assessment has not been conducted.

2.0 Hazard Characterization

2.1 Hazard Profile

The hazard profile for flazasulfuron has not changed since the previous risk assessment was 

written in November of 2005. For complete details on the hazard profile refer to “Flazasulfuron: 

Human Health Risk Assessment for the Proposed Uses on Golf Courses, Sod Farms, 
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Professionally Managed Athletic Fields (College and Professional), and Commercial Lawns. ”

(D303573, Gerome Burke, 11/16/2005). The acute toxicity findings for technical flazasulfuron

are presented in Table 1.

 

Table 1. Acute Toxicity Profile – Flazasulfuron, TGAI

Guideline 

No. Study Type MRID(s) Results Toxicity Category

870.1100 Acute oral – rat 46220908 LD50 > 5000 mg/kg 

(male and females)

IV

870.1200 Acute dermal- rat 46220909 LD50 > 2000 mg/kg 

(male and females)

III

870.1300 Acute inhalation – rat 46220910 LC50 > 5 mg/L 

(male and females)

IV

870.2400 Acute eye irritation –rabbit

46220911 Minimal 

conjunctivitis 

through 48 hours. 

Free by 72 hours.

III

870.2500 Acute dermal irritation – rabbit

46220912 No erythema, 

edema, or dermal 

effects observed at 

application site.

IV

870.2600 Skin sensitization – guinea pig 46220913 Not a sensitizer -

No short- or intermediate-term dermal hazard was identified, since dermal or systemic toxicity was not 

seen in a subchronic dermal study in rabbits at dose levels up to the limit dose. Short- and 

intermediate-term inhalation risks are based on liver toxicity (increase in deposition of brown 

pigments, glutamic pyruvic transaminase, creatine phosphokinase, inflammatory cell infiltration, 

microgranulomas) observed at the LOAEL of 10 mg/kg/day (NOAEL of 2 mg/kg/day) from a 90-day 

oral toxicity study in dogs. An inhalation absorption value of 100% was assumed, since the endpoint 

is based on an oral study. The average body weight of an adult (70 kilograms) was used in the 

assessment, since the effects are not a developmental study. 

HED’s LOC for the MOE is defined by the uncertainty factors that are applied to the assessment. 

HED applies a 10X factor to account for interspecies extrapolation and a 10X factor to account for 

intraspecies sensitivity. Therefore, the total uncertainty factor that has been applied to the non-cancer 

risk assessment is 100 for occupational exposure. Occupational risks resulting in MOEs greater than 

or equal to 100 do not exceed HED’s LOC.

There was no evidence of carcinogenicity to humans based on lack of carcinogenic effects in the rat 

and mouse carcinogenicity studies and lack of a mutagenicity concern. Quantification of cancer risk is 

therefore not required. The cancer classification is “not likely to be carcinogenic to humans.”
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FQPA: The adequacy of the flazasulfuron toxicity database is considered complete. The 

flazasulfuorn risk assessment team evaluated the quality of the toxicity and exposure data and, 

based on these data, recommended that the FQPA Safety Factor be reduced to 1X.

Applicable toxicological doses and endpoints for use in this occupational risk assessment are 

presented in Table 2.

Table 2. Summary of Toxicological Doses and Endpoints for Flazasulfuron for Use in Occupational Human 

Health Risk Assessments

Exposure/

Scenario

Point of 

Departure

Uncertainty/

FQPA Safety 

Factors

Level of 

Concern for 

Risk 

Assessment

Study and Toxicological Effects

Dermal 

Short-Term

(1 - 30 days)

IntermediateTerm

(1-6 months)

NOAEL = 

N/A

(dermal 

absorption 

rate = 45%)

UFA = N/A

UFH = N/A

Residential:

LOC for MOE = 

N/A

21-day Dermal study

NOAEL > 1000 mg/kg/day.

This risk assessment is not required

Inhalation 

Short-Term

(1 - 30 days)

and

IntermediateTerm

(1 - 6 

months)

NOAEL = 2 

mg/kg/day

(inhalation 

absorption 

rate = 100%)

UFA = 10x

UFH = 10x

Occupational:

LOC for MOE = 

100

90-Day oral toxicity in (dog)

LOAEL = 10 mg/kg/day based on changes in 

liver (increase in: deposition of brown pigments, 

glutamic pyruvic transaminase, creatine 

phosphokinase, inflammatory cell infiltration, 

microgranulomas).

Cancer (oral, 

dermal, 

inhalation)

Classification: No evidence of carcinogenicity to humans based on lack of carcinogenic effects in the 

rat and mouse carcinogenicity studies and lack of a mutagenicity concern

Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and 

used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human 

exposures. NOAEL = no observed adverse effect level. LOAEL = lowest observed adverse effect level. UF = 

uncertainty factor. UFA = extrapolation from animal to human (interspecies). UFH = potential variation in 

sensitivity among members of the human population (intraspecies). MOE = margin of exposure. LOC = level of 

concern.

3.0 Summary of Proposed Uses

Flazasulfuron is a sulfonylurea herbicide for control of certain broad-leaf weeds and grasses, and 

acts by inhibiting the acetolactate synthase (ALS) biochemical process. A summary of the 

proposed new flazasulfuron uses is presented in Table 3 below.
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Table 3. Use Profile for Proposed New Flazasulfuron Uses

Use Site

Max. Rate 

for Single

Appl.

Max. 

Rate 

per 

Season

Retreatment 

Interval and 

Maximum 

No. of 

Applications

PHI Application Method and 

Instructions

ISK Flazasulfuron Herbicide [EPA Reg. No71512-RI]

Citrus 0.045 lb 

ai/acre

0.15 lb 

ai/acre

Not reported1

Not reported 1 day

Pre-emergence and Postemergence

Apply only as a directed 

spray to the soil beneath 

the trees using ground 

spray equipment

Use a non-ionic surfactant 

at 0.25% v/v for postemergence applications.

Grapes 0.045 lb 

ai/acre

0.15 lb 

ai/acre

Not reported1

Not reported

75 days

Pre-emergence and Postemergence

Apply only as a directed 

spray to the soil beneath 

the vines using ground 

spray equipment

Use a non-ionic surfactant 

at 0.25% v/v for postemergence applications.

Sugarcane

Over-theTop or 

Postdirected:

0.023 lb 

ai/acre

0.15 lb 

ai/acre

14 days

Not reported

180 days

Apply prior to spiking or 

on ratoon up to 24 inches 

tall at a 0.014 lb ai/A rate.

Use a non-ionic surfactant 

at 0.25% v/v.

Allow a 12 month interval 

between the last 

application and the 

planting of the rotational 

crop.

Postdirected:

0.045 lb 

ai/acre

0.15 lb 

ai/acre

14 days

Not reported

180 days

Apply to sugarcane that is 

18 inches tall up through 

layby. Applications 

should minimize contact 

with the whorl of the 

sugarcane.

Use a non-ionic surfactant 

at 0.25% v/v.

Allow a 12 month interval 

between the last 

application and the 

planting of the rotational 

crop.
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Table 3. Use Profile for Proposed New Flazasulfuron Uses

Use Site

Max. Rate 

for Single

Appl.

Max. 

Rate 

per 

Season

Retreatment 

Interval and 

Maximum 

No. of 

Applications

PHI Application Method and 

Instructions

Christmas trees 0.045 lb 

ai/acre

Not 

reported

Not reported1

Not reported

NA

Pre-emergence and Postemergence 

Do not apply to conifer 

seedbeds. Do not apply to 

trees within 1 year of 

seeding. May be applied 

over-the-top to conifers 

prior to spring bud break 

or when conifers are 

sufficiently hardend off. 

Directed sprays must be 

made to conifers that have 

new growth or are not 

sufficiently hardened off. 

Directed sprays are 

preferred and 

recommended to reduce 

phytotoxicity potential

Use a non-ionic surfactant 

at 0.25% v/v.

Uncultivated 

nonagricultural areas 

(airports, ditch banks, 

dry canals, highway, 

railroad and utility 

rights-of-ways,

industrial sites, 

storage areas, and 

warehouse areas)

0.047 lb 

ai/acre

Not 

reported

4 to 6 weeks

Not reported

NA

Post-emergence 

Do not use near 

residential properties.

Use a non-ionic surfactant 

at 0.25% v/v.

1 A retreatment interval specifically for citrus and grapes was not provided. A generic retreatment interval was provided.

General application information on the label states that pre-emergence and post-emergence 

applications should be made in 15 to 50 gallons of water per acre. For directed post-emergence 

sprays, a spray volume of 20 gallons or more per acre is recommended. Applications should be 

made using conventional low pressure ground spray equipment. Applications cannot be made 

aerially or through any irrigation system. The general label application restrictions also state that 

repeat applications may be made at 2 to 6 weeks after application. However, the label also states 

that split applications should be made at 4 to 6 weeks after the first application, and that 

sequential applications are made on a longer term interval such as spring followed by a fall 

application. 

4.0 Occupational Exposure and Risk

4.1 Handler Exposure and Risk

Chemical-specific exposure data were not submitted to support the proposed flazasulfuron uses. 

When chemical-specific monitoring data are not available, it is the policy of HED to use data 
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from PHED Version 1.1 as presented in the PHED Surrogate Exposure Guide (8/98)1 to assess 

handler exposures for regulatory actions. Additionally, typical HED standard values were used 

for the amount treated per day (ExpoSAC Policy # 9, 7/5/00). 

Based upon the proposed flazasulfuron use patterns, HED assessed risks to occupational 

pesticide handlers in the following scenarios:

• mixing/loading dry flowable powder to support groundboom applications,

• mixing/loading dry flowable powder to support groundboom applications,

• applying sprays with groundboom equipment,

• applying sprays with right-of-way sprayer equipment,

• mixing/loading/applying sprays with backpack sprayers, and

• wettable powder mixing/loading/applying with low pressure handwand.

Equations and Calculations:

Daily Exposure: Daily handler exposures are estimated for each applicable handler task with the 

application rate, the amount of acres treated in a day, and the applicable unit exposure using the 

following equation:

Daily Exposure (mg ai/day) = UE (μg/lb ai) or (mg/lb ai) x AR (lbs ai/A) x AT (A/day) x CF (as needed) (mg/1,000 μg)

Where: 

Daily Exposure = Amount (mg ai/day) deposited on the surface of the skin that is available for dermal

absorption or amount inhaled that is available for inhalation absorption,

UE = Unit exposure value (μg /lb ai) or (mg/lb ai) 

AR = Application rate (lb ai/A) or (lb ai/gal) based on maximum labeled rate

AT = Area treated (A/day) or Amount handled (gal/day) 

Daily Dose: Daily dose (inhalation or dermal) is calculated by normalizing the daily dermal or 

inhalation exposure value by body weight and accounting for dermal and inhalation absorption. 

Average Daily Dose (mg/kg/day) = 

Body Weight (kg)

Daily Exposure (mg ai/day) x Absorption Factor (%)

Where:

Average Daily Dose = Absorbed dose received from exposure to a pesticide in a given 

scenario (mg pesticide active ingredient/kg body weight/day),

Daily Exposure = Amount (mg ai/day) deposited on the surface of the skin that is 

available for dermal absorption or amount inhaled that is available for 

inhalation absorption,

Absorption Factor = A measure of the amount of chemical that crosses a biological 

boundary such as the skin or lungs, and

Body Weight = Body weight determined to represent the population of interest in a risk

assessment.

 

1 HED Science Advisory Council for Exposure [ExpoSAC] Policy .007, “Use of Values from PHED Surrogate 

Table and Chemical-Specific Data” HED, OPP, 1/28/99
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Margin of Exposure (MOE): The daily dermal dose and daily inhalation dose received by 

occupational handlers are compared to the appropriate point of departure (i.e., NOAEL) to assess 

the risk to occupational handlers for each exposure route. All MOE values are calculated 

separately for dermal and inhalation exposure levels using the following equation:

MOE = 

 Average Daily Dose (mg/kg/day)

NOAEL (mg/kg/day)

Where:

MOE = Margin of exposure value used by HED to represent risk or how close a 

chemical exposure is to being a concern (unitless),

ADD = Average daily dose is the absorbed dose received from exposure to pesticide (mg/kg/day)

NOAEL = No Observable Adverse Effect Level (mg/kg/day)

HED’s LOC for the MOE is defined by the uncertainty factors that are applied to the assessment. 

HED applies a 10X factor to account for interspecies extrapolation and a 10X factor to account 

for intraspecies sensitivity. Therefore, the total uncertainty factor that has been applied to the 

non-cancer risk assessment is 100 for occupational exposure. Occupational risks resulting in

MOEs greater than or equal to 100 do not exceed HED’s LOC.

Short- and intermediate-term risk estimates for occupational handlers are included in Table 4. 

All handler scenarios resulted in MOEs greater than the LOC (MOEs ≥ 100), and therefore are 

not of concern. 

Table 4. Summary Of Short- and Intermediate-Term Occupational Handler Exposures And Risks

Exposure 

Scenario

Crop 

Grouping

Application 

Ratea

(lb ai/A)

Area 

Treated 

Dailyb 

(A/day)

Baseline 

Inhalationc

Unit Exposure 

(μg/lb ai)

Baseline 

Inhalation Dose 

(mg/kg/day)

Baseline 

Inhalation 

ST MOEd

(LOC ≥ 100)

Baseline 

Inhalation 

IT MOEe

(LOC ≥ 100)

Mixer/Loader

Mixing/Loading 

Dry Flowable

for 

Groundboom 

Applications

Citrus

0.045 80 0.77 0.000040 2,200,000 51,000

Grapes

Sugarcane

Christmas 

Trees

Non-crop 0.047 80 0.77 0.000041 2,100,000 48,000

Mixing/Loading 

Dry Flowable

for Right-ofWay

Applications

Non-crop 0.047 40 0.77 0.000021 4,200,000 97,000

Applicator

Applying 

Sprays via 

Groundboom 

Equipment 

(open cab)

Citrus

Grapes

Sugarcane

Christmas 

Trees

0.045 80 0.74 0.000038 2,300,000 53,000

Non-crop 0.047 80 0.74 0.000040 2,200,000 50,000

Applying 

Sprays via 

Right-of-Way

Non-crop

0.0024

(lb ai/gal)

1000

(gal/day) 3.9 0.00013 670,000 15,000
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Table 4. Summary Of Short- and Intermediate-Term Occupational Handler Exposures And Risks

Exposure 

Scenario

Crop 

Grouping

Application 

Ratea

(lb ai/A)

Area 

Treated 

Dailyb 

(A/day)

Baseline 

Inhalationc

Unit Exposure 

(μg/lb ai)

Baseline 

Inhalation Dose 

(mg/kg/day)

Baseline 

Inhalation 

ST MOEd

(LOC ≥ 100)

Baseline 

Inhalation 

IT MOEe

(LOC ≥ 100)

Equipment 

Mixer/Loader/Applicator

Backpack

Christmas 

Trees 0.0023 40 30 0.000039 2,300,000 52,000

Non-crop 0.0024 40 30 0.000040 2,200,000 50,000

(lb ai/gal) (gal/day)

Low Pressure 

Handwand

Christmas 

Trees 0.0023 40 1100 0.0014 62,000 1,400

Non-crop

0.0024 40 1100 0.0015 59,000 1,400

(lb ai/gal) (gal/day)

a Application rates are the maximum application rates determined from proposed labels for flazasulfuron.

b Amount handled per day values are HED estimates of acres treated per day based on Exposure SAC SOP #9 “Standard 

Values for Daily Acres Treated in Agriculture,”

c Baseline Inhalation: no respirator.

d Inhalation ST MOE = ST NOAEL (87.5 mg/kg/day) / inhalation daily dose (mg/kg/day), where inhalation dose = daily 

unit exposure (μg/lb ai) x application rate (lb ai/A) x area treated (A/day) x 100% inhalation absorption / body weight 

(70 kg adult). LOC = 100

e Inhalation ST MOE = STNOAEL (2 mg/kg/day) / inhalation daily dose (mg/kg/day), where inhalation dose = daily unit 

exposure (μg/lb ai) x application rate (lb ai/A) x area treated (A/day) x 100% inhalation absorption / body weight (70 

kg adult). LOC = 100

4.2 Occupational Post-application Exposure and Risk

There is a possibility for agricultural workers to have post-application dermal exposure to 

flazasulfuron following its proposed new uses. However, a dermal hazard was not identified;

therefore, post-application dermal exposures were not assessed. 

Occupational Post-application Inhalation

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

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

inhalation toxicity (Toxicity Category IV) and low vapor pressure (< 1 x 10 -7 torr). However, 

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.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The Agency is in the 

process of evaluating the SAP report as well as available post-application inhalation exposure 

data generated by the Agricultural Reentry Task Force 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 
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procedures are put into place, the Agency may revisit the need for a quantitative occupational 

post-application inhalation exposure assessment for flazasulfuron.

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

performed, an inhalation exposure assessment was performed for occupational 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.

Restricted Entry Interval: The ISK Flazasulfuron Herbicide label proposes a 4-hour reduced 

reentry interval (REI). In accordance with criteria for reduced REI candidates, an active 

ingredient cannot elicit reproductive, developmental, neurotoxic or carcinogenic effects. 

Flazasulfuron elicits developmental effects, and therefore cannot be a candidate for a reduced 

REI. Per the Worker Protection Standard (WPS), chemicals classified as Toxicity Categories III 

and IV require a 12-hr restricted entry interval (REI). HED recommends that RD ensure that the 

REI on the label be corrected to 12 hours.

5.0 Residential Exposure and Risk

5.1 Residential Handler and Post-application Exposures and Risks

This document only presents the assessment of the proposed new agricultural uses of 

flazasulfuron. No residential uses are being requested at this time; therefore, a residential risk 

assessment was not necessary to conduct. 

Flazasulfuron is currently registered for use on golf courses and other non-residential turf areas 

such as industrial parks, tank farms, sod farms, seed farms, professionally managed sports fields, 

and commercial lawns. Post-application short-term dermal exposures are expected to occur for 

recreational golfers or players of various sports who use a golf course or athletic field after 

flazasulfuron has been applied. However, since a dermal hazard was not identified, dermal 

exposures and risk were not assessed. 

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

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

inhalation toxicity (Toxicity Category IV) and low vapor pressure (< 1 x 10 -7 torr). 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, 2010 (http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). 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 postapplication 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 flazasulfuron.
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5.2 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 flazasulfuron. 

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 

management practices (see the Agency’s Spray Drift website for more information at 

http://www.epa.gov/opp00001/factsheets/spraydrift.htm). On a chemical by chemical basis, the 

Agency is now requiring interim mitigation measures for aerial applications that must be placed 

on product labels/labeling. 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 off-target drift with specific products with significant risks 

associated with drift.