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

OFFICE OF PREVENTION, PESTICIDES
AND TOXIC SUBSTANCES



### MEMORANDUM

Date: 17 February 2009

SUBJECT: Imazosulfuron; Occupational and Residential Risk Assessment for Proposed Use of Imazosulfuron on Residential Turf, Or namentals and Bare Ground Non-Crop Areas.

PC Code: 118602 DP Barcode: D349707

Decision No.: 387737 Registration No.: 59639-RLL

Petition No.: NA Regulatory Action: Section 3 Assessment Type: Single Chemical/No Aggregate Case No.: NA

TXR No.: NA CAS No.: 122548-33-8

MRID No.: 47305124, 47305125 40 CFR:

FROM: Kelly O’Rourke, Biologist

Risk Assessment Branch 4 Health Effects Division (7509P)

THROUGH: Barry O’Keefe, ORE Assessment Team Leader

Risk Assessment Branch 3 Health Effects Division (7509P)

TO: Sheila Healy, Risk Assessor and Toxicologist

Risk Assessment Branch 3 Health Effects Division (7509P)

I. CONCLUSIONS

The V-10142 Herbicide label, EPA Reg. No. 59639- RLL, is not acceptable as written. In addition to agricultural sites such as sod farm s, imazosulfuron is intended for non-agricultural use sites, to which the Worker Protection Standa rd Restricted Entry In terval does not apply. Therefore, the label should be amended to c ontain language cautioning u nprotected persons to keep out of treated areas until sprays have drie d. The occupational and residential margins of exposure (MOEs) for all scenarios reach/sur pass the level of concern (LOC) of 100 and therefore, are not of concern.

Page 1 of 12

### II. ACTION REQUESTED

Provide an occupational and residential exposure and risk assessment for the proposed uses on residential turf, ornamentals and bare ground non-crop areas.

III. BACKGROUND/ EXECUTIVE SUMMARY

The registrant, Valent U.S.A. Corporation, requests the registration of the product V-10142 Herbicide (EPA Reg. No. 59639-RLL), containi ng 75% imazosulfuron, for the control of nutsedge and other weeds in turfgrass, orna mentals and bare ground non-crop areas. This memorandum assesses the occupational and resi dential exposure risks from imazosulfuron for these proposed uses. An aggregate human health risk assessment is pr esented in a separate Health Effects Division (HED) memorandum. In this memorandum, the ANSI name imazosulfuron will be used for the active ingredient (ai) evaluated in this product.

Use Profile

Imazosulfuron is a new active ingredient (ai); there ar e currently no registered uses in the U.S. It is proposed, in the herbicidal product V-10142 (EPA Reg. No. 59639-RLL, formulated as a water dispersible granule containing 75% ai), to control nutsedge and other weeds for the following use sites:

• 

### Established turf (residential, commercial, golf course, and sod farms) - proposed application rates range from 0.50 to 0.75 lb ai/A, with a second application 21 days later using ground broadcast-spraying equipment (not to be applied by air or through irrigation systems);

• 

### Around outdoor ornamentals (field grown coni fers, deciduous trees, non-bearing fruit and nut trees, and landscape plants) - proposed rates range fr om 0.50 to 1.0 lb ai/A for preemergence, and 0.50 to 0.75 lb ai/A for post-emer gence, to be applied as a directed spray (away from plant material) - the number of a pplications and retreatme nt intervals are not specified; and

• 

### Maintenance of bare ground non-crop areas - pr oposed applications rates range from 0.50 to 1.0 lb ai/A for pre-emergence, and 0.50 to 0.75 lb ai/A for post-emergence, using handgun sprayers or aerial application - the number of applications and retreatment intervals are not specified.

Hazard Profile

Short-term handler exposure is possible via the dermal and inha lation routes, and short-term postapplication exposure may occur via the dermal and oral (incidental ingestion for children in residential settings) routes ba sed on the proposed use pattern. Intermediate-term and chronic exposures are not expected for the proposed use patterns because the app lication interval is 21 days and turf transferable residue/terrestrial field dissipation data submitted by the registrant

indicate that the longest estimated half-life is 6 days.

Dermal endpoints were not selected for imazo sulfuron because no systemic toxicity was observed at the limit dose in the dermal study; there was no significant evidence of increased

Page 2 of 12

### sensitivity or susceptibility; and dermal absorption is expected to be minimal. The short-term inhalation and incidental oral endpoints were selected from a two-generation reproduction study and a co-critical 90-day oral toxi city study in rats. Toxicity by the inhalation route is assumed to be equivalent to oral toxicity, and expos ures compared to the parental NOAEL of 235 mg/kg/day. The endpoint includes mortality, c linical signs, and decreased body weights, body weight gain, and food consumption at the L OAEL of 892 mg/kg/day. The level of concern (LOC) is a margin of exposure (MOE) less than 100 [10X for interspecies extrapolation and 10X for intraspecies variation]. Imazosulfuron is cl assified as “Not likely to be Carcinogenic to Humans” based on the absence of significant tumor increases in tw o adequate rodent carcinogenicity studies.

Occupational Exposure / Risk

No chemical-specific handler exposure data were submitted in support of this registration. It is the policy of the HED to use data from the Pesticide Handlers Exposure Database (PHED) Version 1.1 as presented in PHED Surrogate Expos ure Guide (8/98) to a ssess handler exposures for regulatory actions when chemical-specific mo nitoring data are not av ailable (HED Science Advisory Council for Exposure Standard Operati ng Procedure (SOP) #7, dated 1/28/99). The handgun sprayer exposure data used in this asse ssment are from proprietary data (MRID # 44972201) submitted by the Outdoor Resident ial Exposure Task Force (ORETF).

The results of the handler occupational exposure and risk assessment indicate that risks are not

of concern with baseline cl othing. The inhalation MOEs range from 61,000 to 2,300,000; and therefore, are not of concern

.

Per the Worker Protection Standard (WPS), the minimum level of PPE for handlers is based on the acute toxicity of the end-us e product. The Registration Divi sion is responsible for ensuring that PPE listed on the product label is in compliance with WPS.

Occupational postapplication dermal exposure is possible following treatment of turf and ornamentals with imazosulfuron. The registrant submitted chemical-specific turf transferrable residue (TTR) studies (MRIDs: 47305124 and 47305125) for use in assessing postapplication exposure. However, because a dermal endpoint was not identified for this exposure potential, and inhalation exposure is expected to be negligible for reentry activities, a posta pplication risk

assessment was not conducted . The imazosulfuron technical material has been classified in Toxicity Category III for acute dermal and Toxi city Category IV for primary eye irritation and primary skin irritation. Per the Worker Protec tion Standard (WPS), a 12-hr restricted entry interval (REI) is required for chemicals classified under Toxici ty Category III or IV. The proposed label indicates a 12-hour REI, which comp lies with the WPS. This product is intended for use on sod farms, which are within the scope of the WPS. In addition, imazosulfuron is intended for non-agricultural use sites to which the WPS does not apply. The label should be amended to contain language cautioning unprot ected persons to keep out of treated areas until sprays have dried

.

Page 3 of 12

### Residential Exposure/Risk

Imazosulfuron is proposed for use on residential turf and recreational sites such as golf courses. The proposed label (V-10142) does not prohibit application by home -owners; therefore, shortterm non-occupational handler exposure was ev aluated. HED’s Draft Standard Operating Procedures (SOPs) for Residential Exposure Assessments, and Recommended Revisions (HED Policy Number 11, revised 22 Feb 2001), were used as the basis for all residential handler exposure calculations. Data from the Outdoor Residential Exposure Task Force (ORETF) (MRID # 44972201) were used in this assessment in place of PHED data for the garden hose-end sprayer scenario, which provided more c onfidence in the exposure estimate. The MOEs for residential handlers are well above the LOC of 100, and are not of concern

.

Residential postapplication exposur e via the inhalation route is e xpected to be negligible, and while dermal exposure is likely for adults and childr en entering treated lawns, there is a lack of observable dermal toxicity, as discussed prev iously. Toddlers may experience exposure via incidental non-dietary inges tion (i.e., hand-to-mouth, object- to-mouth (turfgrass), and soil ingestion) during postapplication activities on treated turf. Th e postapplication risk assessment is based on generic assumptions as specified by the Recommended Revisions to the Residential SOPs and recommended approaches by HED’s Science Advisory Council for Exposure (ExpoSAC).

Residential short-term postapplication MOEs were estimated for “Day 0” exposure (i.e., the day of application). The combined short-term MOE for children is 17 ,000 . This MOE is greater than the LOC of 100 on the day of application, and therefore, is not of concern

.

Note: This risk assessment relies in part on da ta from studies in which adult human subjects were intentionally exposed to a pesticide or othe r chemical. These studies (listed below) have been determined to require a re view of their ethical conduct, and have received that review.

• 

### The PHED Task Force, 1995. The Pesticide Handlers Exposure Database, Version 1.1. Task Force members Health Canada, U.S. Environmental Protection Agency, and the National Agricultural Chemicals A ssociation, released February, 1995.

• 

### Klonne, D. (1999) Integrated Report for Evaluation of Potential Exposures to

Homeowners and Professional Lawn Care Operators Mixing, Loading, and Applying Granular and Liquid Pesticides to Residential Lawns: Lab Project Number: OMA005: OMA001: OMA002. Unpublished study prep ared by Riceerca, Inc., and Morse Laboratories. 2213 p. (MRID 44972201).

Page 4 of 12

### IV. RESULTS/DISCUSSION

1.0 Hazard Profile

Table 1 presents a summary of the applicable endpoints selected for imazosulfuron by the RAB3 risk assessment team and confirmed by HED’ s Science Advisory Council for Toxicity. A summary of the acute toxicity categories for th e technical material are included in Table 2.

Table 1. Summary of Toxicological Dose and Endpoints for Imazosulfuron

Exposure/

Scenario Point of Departure Uncertainty/FQPA Safety Factors RfD, PAD,

LOC for Risk

Assessment Study and Toxicological Effects

Incidental Oral

Short-

/IntermediateTerm (1-30 days) NOAEL= 235 mg/kg/day (MRID 47305232) UF A = 10x

UF H = 10x Residential

LOC for MOE

= 100 Reproduction, 2 generation (rat; MRID 47305304) and 90-day oral toxicity (rat; 47305232). LOAEL = 892 mg/kg/day based on mortality, clinical signs, decreased body weights, body weight gains and food consumption in parents (MRID 47305304). LOAEL = 956 mg/kg/day based on decreased body weight gains and food efficiency (MRID 47305232).

Dermal Short-/

Intermediate-Term (1-30 days) No systemic toxicity occu rred at the limit dose and the primary toxic effects of c oncern (liver, eye) were adequately assessed in a 21-day dermal toxicity study (MRID 47305236). It is concluded that this compound is not absorbed or is poorly absorb ed through the skin and, therefore, a quantitative

risk assessment for this route and duration is not necessary.

Inhalation Short-

/IntermediateTerm (1-30 days) NOAEL= 235 mg/kg/day (MRID 47305232)

(100% absorption) UF A = 10x

UF H = 10x Residential

LOC for MOE

= 100 Reproduction, 2 generation (rat; MRID 47305304) and 90-day oral toxicity (rat; 47305232). LOAEL = 892 mg/kg/day based on mortality, clinical signs, decreased body weights, body weight gains and food consumption in parents (MRID 47305304). LOAEL = 956 mg/kg/day based on decreased body weight gains and food efficiency (MRID 47305232).

Cancer (oral, dermal, inhalation) Classification: “Not likely to be Carcinogenic to Humans” based on the absence of significant tumor increases in two adequate rodent carcinogenicity studies (MRID 47305307, mouse; 47305306, rat).
Point of Departure (POD) = A data point or an estimated poin t that is derived from observed dose-response data and used to mark the beginning of extrapolation to determine risk associated with lower en vironmentally relevant human exposures. NOAEL = no observed adverse effect level. LOAEL = lowest observed adverse effect level. UF = uncertainty factor. UF A = extrapolation from animal to human (interspecies). UF H = potential variation in sensitivity among members of the human population (intrasp ecies). FQPA SF = FQPA Safety Factor. LOC = level of concern. MOE = margin of exposure.



### Page 5 of 12

### Table 2. Acute Toxicity of Imazosulfuron Technical

Guideline

No. Study Type MRID# Results Toxicity Category

870.1100 Acute Oral- Rats 47305221 LD 50 >5000 mg/kg IV

870.1200 Acute Dermal- Rat 47305227 LD 50 >2000 mg/kg III

870.1300 Acute Inhalation- Rat 47305228 LC 50 >2.12 mg/L IV

870.2400 Acute Eye Irritation- Rabbit 47305229 Non-irritating IV

870.2500 Primary Dermal Irritation- Rabbit 47305230 Non-irritating IV

870.2600 Dermal Sensitization- Guinea pig 47305231 Negative N/A



### 2.0 Use Profile

Imazosulfuron is a new active ingredie nt; there are currently no register ed uses in the U.S. It is proposed, in the herbicidal product V-10142 (EPA Reg. No. 59639- RLL) for the control of nutsedge and other weeds in turfgrass, orna mentals and bare ground non-crop areas. The use profile proposed for this S ection 3 registration request is summarized in Table 3.

Table 3. Summary of Use Pa ttern/Formulation Information

Formulation Type Application

Method Use Site Application

Rate (lb ai/A) Application

Interval Preharvest

Interval

Groundboom, Low-pressure

Handheld Equipment 1 Established

Turf (residential, commercial, golf course, and sod farms) 0.50 – 0.75 21 days 2

Groundboom, Low-pressure

Handheld Equipment Around Outdoor Ornamentals (field grown conifers, deciduous trees , non-bearing fruit and nut trees, and landscape plants) V-10142

Herbicide

(water dispersible

granule)

75% ai

Aerial or

Handheld Equipment Bare Ground Non-Crop 0.50 – 1.0(preemergence)

0.50 – 0.75(postemergence) Not Specified 2 N/A

1 For turf, aerial applications are prohibited, and product is not to be applied through any type of irrigation system.

2 A second application is permitted for turf, however, the number of applications and retreatment intervals are not

specified for the ornamental and bare ground non-crop use sites.



### Page 6 of 12

### 3.0 Occupational Exposure

3.1 Handler Exposure and Risk

There is a potential for exposure to imazosu lfuron during mixing, loading, and application activities. No chemical-specific handler exposure data were submitted in support of this registration. It is the policy of the HED to use data from the Pesticide Handlers Exposure Database (PHED) Version 1.1 as presented in PHED Surrogate E xposure Guide (8/98) to assess handler exposures for regulatory actions when chemical-specific monitoring data are not available (HED Science Advisory Council for E xposure Standard Operating Procedure #7, dated 1/28/99). There are no PHED unit exposure data for mixing/loading/appl ying water dispersible granules [also called dry flowable] with a low pressure handwand. The scenario evaluated for this equipment type using the li quid formulation is considered to be an adequate surrogate for estimating exposure from the water dispersible gr anule formulation. The handler exposure data for the turf handgun sprayer scenario are from the Outdoor Residential Exposure Task Force (ORETF) (MRID # 44972201), rather than from PH ED. The ORETF data were designed to replace the present PHED data with higher-conf idence, higher quality data that contain more replicates than the PHED data for those scenarios.

Short-term occupational handler exposure is poss ible via the dermal and inhalation routes based on the proposed use pattern. Dermal endpoints we re not selected for imazosulfuron because no systemic toxicity was observed at the limit dose in the dermal study; there was no significant evidence of increased sensitivity or susceptibility; and dermal absorption is expected to be minimal. A short-term inhalation endpoint wa s selected from a two- generation reproduction study and a co-critical 90-day oral toxicity study in rats. Toxi city by the inhalation route is assumed to be equivalent to oral toxicity, a nd inhalation exposures compared to the NOAEL of 235 mg/kg/day. The endpoint includes mortality , clinical signs, and decreased body weights, body weight gain, and food consumption at the LOAEL of 892 mg/kg/day. The LOC is an

MOE less than 100. Imazosulfuron is classified as “Not likely to be Carcinogenic to Humans” based on the absence of significant tumor increa ses in two adequate rodent carcinogenicity

studies.

The results of the handler occupa tional exposure and risk assessment indicate that risks are not of concern with baseline clothing (i.e., no respirator). Occupati onal handlers’ inhalation MOEs range from 61,000 to 2,300,000, and are not of con cern. Exposure assumptions and MOEs for occupational handlers are su mmarized in Table 4.

HED recognizes that it is feasible for the same individual to mix/load and apply formulations with the groundboom sprayer; however, appropriat e data are not available in PHED for which unit exposure values for these combined activit ies can be derived. HED does not recommend simply adding the unit exposure values for each job function because any extrapolation error (i.e., exposure from the amount of ai handled in th e study to that of a real -life application) would be magnified, leading to greater uncertainty. For information and characterization purposes, even with the over-estimation uncertainty, the MOEs for these combined activities would be above the LOC of 100 (i.e., 180,000 and 270,000 for turf and ornamentals, respectively). The

minimum level of PPE for handlers is based on acute toxicity for the end-use products. The Registration Division (RD) is responsible for ensuring that PPE listed on the label is in compliance with the Worker Protection Standard (WPS).

Page 7 of 12Table 4. Summary of MOEs for Occupational Handlers of Imazosulfuron

Exposure Scenario (Scenario #) Inhalation

Unit Exposure (mg/lb ai) 1 Use Site Application

Rate (lb ai/A) 2 Area

Treated (A/day) 3 Inhalation

Dose (mg/kg/day) 4 ShortTerm

MOE 5

Mixer/Loader

(1) Mixing/Loading Dry Flowables for Aerial application Bare ground Non-Crop 1.0 350 0.0039 61,000

Turf 0.75 80 0.00066 360,000 (2) Mixing/Loading Dry Flowables for Groundboom application 0.00077

Ornamentals 1.0 40 0.00044 530,000

Applicator

(3) Applying Sprays with Sprays with Fixed-wing Aircraft 0.000068 Bare ground Non-Crop 1.0 350 0.00034 690,000

Turf 0.75 80 0.00063 370,000 (4) Applying Sprays with Open Cab

Groundboom 0.00074

Ornamentals 1.0 40 0.00042 560,000

Mixer/Loader/Applicator

Turf 0.75 5 0.00010 2,300,000 (5) Mixing/Loading Dry Flowables and Applying with Handgun Sprayer 0.0019 Ornamentals & Non-Crop 1.0 5 0.00014 1,700,000

(6) Mixing/Loading Liquid and Applying

with Low-Pressure Handwand 0.03 Turf 0.025 (lb ai/gal) 40 (gal/day) 0.00043 550,000

Flagger

(7) Flagging to Support Aerial Applications 0.00035 Bare ground Non-Crop 1.0 350 0.0018 130,000

1 Inhalation unit exposure values represent no respirator. Values are reported in the PHED Surrogate Exposure Guide dated August 1998, except for the handgun value which was obtained from ORETF.

2 Application rates are based on maximum values presen ted in proposed label: V-10142 (EPA Reg. No. 59639-RLL).

3 Daily area treated is based on the area or gallons that can be reasonably applied in a single day for each exposure scenario ba sed on the application method and formul ation/packaging type. (standard EPA/OPP/HED values).

4 Daily Dose (mg/kg/day) = (Inhalation unit expos ure * Application rate * Area treated) / 70 kg

5 MOE = NOAEL / Daily Dose; where the short-term NOAEL is 235 mg/kg/day. The LOC is 100.



### 3.2 Occupational Postapplication Exposure and Risk

This registration action for imazosulfuron involves applications to residential and commercial turfgrass, golf courses, sod farms, and orname ntals. Therefore, there is a potential for postapplication exposure to maintenance worker s and sod harvesters. However, because no appropriate dermal endpoints we re identified for this exposur e potential, and postapplication inhalation exposure is expected to be negligible, an occupationa l postapplication risk assessment was not conducted. Non-occupationa l postapplication risk in reside ntial settings is covered in

Section 4.2

Page 8 of 12

### 4.0 Non-Occupational/Residential Exposure

V-10142 herbicide is proposed for application to re sidential turfgrass and r ecreational sites. It may be applied to turf at rate s ranging from 0.50 to 0.75 lb ai/A , for two applications at an interval of 21 days. The labels do not prohibit homeowners from using th ese products; therefore, residential handlers may receive short-term de rmal and inhalation exposure to imazosulfuron when mixing, loading and applying the formula tion. Residential postapplication exposure via the inhalation route is expected to be negligible; however, dermal exposure is likely for adults and children entering treated lawns. Toddlers ma y also experience exposur e via incidental nondietary ingestion (i.e., hand-to -mouth, object-to-mouth (turfgrass) , and soil ingestion) during postapplication activities on treated turf.

As discussed previously, dermal endpoints we re not selected for imazosulfuron because no systemic toxicity was observed at the limit dose in the dermal study. Short-term inhalation and incidental oral exposure was assessed using the same NOAEL (235 mg/kg/da y) that was selected for occupational inhalation exposure. Toxicity by the inhalation route is assumed to be equivalent to oral t oxicity. The LOC is an MOE less than 100.

4.1 Residential Handler Exposure and Risk

HED’s Draft Standard Operating Procedures (SOPs) for Residen tial Exposure Assessments, and Recommended Revisions (HED Policy Number 11, revised 22 Feb 2001), were used as the basis for the residential handler exposure calculations. Data from the Out door Residential Exposure Task Force (ORETF) (MRID # 44972201) were used in this assessment in place of PHED data for the garden hose-end sprayer scenario, which provided more confidence in the exposure estimate. As shown in Table 5, the inhalation MO Es for residential handlers are well above the LOC of 100, and are not of concern.

Table 5. Handler Exposure and Risk Es timates for Residential Lawn Applicators

Handler Scenario Application

Rate 1

(lb ai/A) Area

Treated 2
(acres/day) Inhalation

Unit Exposure 3
(mg/lb ai) Daily Dose 4
(mg/kg/day) Short-Term

MOE 5

(1) Mix/load and spot application of liquid formulation (low-pressure hand sprayer) 0.75 0.023 (1,000 ft 2 ) 0.030 0.0000074 32,000,000

(2) Mix/load and broadcast application of liquid formulation (garden hose-end sprayer) 0.75 0.50 0.017 0.000091 2,600,000

1 Application rate is based on maximum values found in proposed label: V-10142 (EPA Reg. No. 59639-RLL).

2 Area treated is based on the area that can be reasonably treated in a single day based on the a pplication method (standard EPA/OPP/HED values).

3 Inhalation unit exposure values represent no respirator. Value for low-pressure handwand is reported in the PHED Surrogate Exposure Guide dated August 1998, and that for hos e-end sprayer was obtained from the ORETF data.

4 Daily Dose (mg/kg/day) = (Uni t Exposure * Application rate * Area treated) / 70 kg.

5 Short-Term MOE = NOAEL (235 mg/kg/day) / Daily Dose. The LOC is 100.



### Page 9 of 12

### Page 10 of 12 4.2 Residential Postapplic ation Exposure and Risk

Turf transferrable residue (TTR) studies were submitted by the registrant (MRIDs: 47305124 and 47305125) for use in assessing postapp lication activities. The data from these studies were not used because TTR studies are only relevant fo r dermal exposure. The incidental ingestion assessment was conducted with standard assumptions for the initial fracti on of residue available as well as other factors as specified by the R ecommended Revisions to th e Residential SOPs and recommended approaches by HED’s Science Ad visory Council for Exposure (ExpoSAC).

The exposure and risk estimates for the residentia l exposure scenarios are assessed for the day of application (day “0") because it is assumed th at toddlers could contact the lawn immediately after application. The equations used for the exposure calculations and the results are presented in Tables 6 through 8.

The exposure estimates are based on some uppe r-percentile (i.e., maximum application rate,

initial amount of transf errable residue and durati on of exposure) and some central tendency (i.e., surface area and body weight) assumptions and are c onsidered to be representative of high-end exposures. The uncertainties associated with this assessment stem from the use of an assumed amount of pesticide available from turf, and assu mptions regarding transfer of chemical residues and hand-to mouth activity. The estimated expos ures are believed to be reasonable high-end estimates based on observations from chemical-sp ecific field studies and professional judgment.

The short-term MOEs for each scenario are greate r than the LOC of 100, and are not of concern. The total short-term MOE resulting from conservatively combining MOEs for children (shown in Table 9) is 17,000, which is also a bove the LOC of 100, and not of concern.

4.3 Off Target Non-Occupational Exposure

Spray drift is always a potential source of expos ure to residents nearby to spraying operations. This is particularly the case with aerial appl ication, but, to a lesser ex tent, could also be a potential source of exposure from the ground application method employed for imazosulfuron. The Agency has been working with the Spray Dr ift Task Force, EPA Regional Offices and State Lead Agencies for pesticide regulation and ot her parties to develop the best spray drift management practices. The Agency is now re quiring interim mitigation measures for aerial applications that must be placed on product la bels/labeling. The Agency has completed its evaluation of the new data base submitted by the Spray Drift Task Force, a membership of U.S. pesticide registrants, and is de veloping a policy on how to appr opriately 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 and risks associated with aerial as well as other application types where appropriate. Note that imazosulfuron is directly applied to residential tu rf and does not result in exposures of concern. It is unlikely that spray drift would result in a hi gher potential for risk of expos ure than the scenarios already

assessed.Page 11 of 12Table 6. Postapplication Oral Hand-to-Mouth Exposure and Risk for Children from Treated LawnsApplicationRate(lb ai/A)Postapplicationday (t)Fraction of aiTransferrablefrom theFoliageTurfTransferrableResidue1(μg/cm2)HandSurfaceArea(cm2/event)SalivaExtractionFactorFrequency(events/ hr)BodyWeight(kg)Daily Dose2(mg/kg/day)Short-termOralMOE30.7500.050.422050%20150.01121,0001Turf Transferrable ResiduePostapplication day(μg/cm2)= Application rate (lb ai/A) x Fraction of ai Transferrable from the Foliage x (1- Fraction of Residue ThatDissipates Daily, 0.1)Postapplication dayx 4.54E+8 μg/lb x 2.47E-8 A/cm22Daily Dose = (Turf Transferrable Residue (μg/cm2) x Hand Surface Area (cm2/event) x Saliva Extraction factor x Frequency (events/hr) x 0.001 mg/ μg xExposure time (2 hrs/day)] / [Body Weight (kg)]3Oral MOE = Oral NOAEL/Daily Dose; where Short-term NOAEL = 235 mg/kg/day.Table 7. Postapplication Oral Object-to-Mouth (Turfgrass) Exposure and Risk for Children from Treated LawnsApplication Rate(lb ai/A)Postapplication day(t)Fraction of aiTransferrablefrom the FoliageGrass/ObjectResidue1(μg/cm2)Ingestion Rate(cm2/day)BodyWeight(kg)Daily Dose2(mg/kg/day)Short-termOralMOE30.7500.21.725150.002884,0001Grass/Object residuePostapplication day(μg/cm2) = Application rate (lb ai/A) x Fraction of ai Transferrable from the Foliage x (1- Fraction of Residue That DissipatesDaily)Postapplication dayx 4.54E+8 μg/lb x 2.47E-8 A/cm22Daily Dose = [Grass reside (μg/cm2) x Ingestion rate (cm2/day) x 0.001 mg/μg] / [Body Weight (kg)]]3Oral MOE = Oral NOAEL / Daily Dose; where Short-term NOAEL= 235 mg/kg/day.Table 8. Postapplication Incidental Soil IngestionExposure and Risk for Children from Treated LawnsApplication Rate(lb ai/A)Fraction of aiRetained in theSoilSoilResidue1(μg/g)Ingestion Rate(mg/day)BodyWeight(kg)Daily Dose2(mg/kg/day)Short-termOralMOE30.7515.6100150.0000386,300,0001Soil residuePostapplication day zero(μg/cm2) = Application rate (lb ai/A) x Fraction of ai Retained on the Soil x (4.54E+8 μg/lb x 2.47E-8 A/cm2x 0.67 cm3/g soil2Daily Dose = [Soil reside (μg/g) x Ingestion rate (mg/day) x 0.000001 g/μg] / [Body Weight (kg)]]3Oral MOE = Oral NOAEL/Daily Dose; where Short-term NOAEL = 235 mg/kg/day.

### Table 9. Children’s Aggregate Exposure and Risk Estimates from Residential Lawn s

Children’s Scenarios TTR/GR/SR 0 (ug/cm 2 or g) 1 PDR 0-norm (mg/kg/day) 2 Short-Term

MOE 3 Total

Short-Term

MOE 4

(1) Hand-to-Mouth 0.42 0.011 21,000

(2) Mouthing Grass 1.7 0.0028 84,000

(3) Soil Ingestion 5.6 0.000038 6,300,000 17,000

1 TTR=turf transferable residue on day “0"; GR=grass residue on day “0"; SR 0 =soil residue on day “0".

2 PDR 0norm =potential dose rate on day “0”.

3 MOE = NOAEL/PDR; where Short-term NOAEL = 235 mg/kg/day.

4 Total MOE = 1/ [(1/MOE Hand-to-Mouth ) + (1/MOE Grass ) + (1/MOE Soil )]



### Page 12 of 12