MEMORANDUM 

PC Code: 050410 

DP Barcode: 417634 

SUBJECT: Fluensulfone: Refined Drinking Water Exposure Assessment for Proposed New 

Registration for Uses on Cucurbits and Fruiting Vegetables Based on Ground 

Water Sources 2J 

James Lin, Environmental Engineer __ Environmental Risk Branch II 

FROM: 

Ecological Fate and Effects Division (7507P) 

!/) j-Jo-llf THROUGH: Greg Orrick, Environmental Scientist -

Brian Anderson, Branch Chief , 'c: jlt/YLEnvironmental Risk Branch II · 

Fate and Effects Division (7507P) 

TO: Michael Doherty, Risk Assessor 

Christina Swartz, Branch Chief 

Risk Assessment Branch II 

Health Effects Division (7509P) 

Jennifer Gaines, Wildlife Biologist John Hebert, Team"Leader, PM Team 7 

Insecticide-Rodenticide Branch 

Registration Division (7505P) 

This memo provides refined estimated drinking water concentrations (EDWC) in ground water 

from the use offluensulfone in support of the Health Effects Division's (HED) human health risk 

assessment (Table 1). In the current and previous drinking water memos (050410_ 411774_ 

DWA_08-01-2013), a total toxic residues (TTR) modeling approach was used, based on the 

recommendation by ROCKS (The Residues of Concern Knowledge base Subcommittee of HED). 

The previous exposure estimates reflected the Total Residues of Concern (TRC), which are a 

summation of the parent compound and two transformation products: methyl sulfone (MS) and 

deschloro-fluensulfone. Since deschloro-fluensulfone was not formed in the submitted aerobic 

soil metabolism study (MRID 48574823), for ground water systems, the EDWC will be the sum 

of parent fluensulfone and methyl sulfone (MS) only. The refined screening approach will be 

running the model PRZM-GW separately one for the parent fluensulfone alone and the other for 

methyl sulfone. The resulting EDWC is the sum of the two modeling runs. Table 1 provides the 

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Cucurbits and 

Ground water (Tier I: PRZM-GW) fruiting vegetables 77.6 52.5 

(4 Kg a.i./Ha/year) 

PRZM-GW modeling of Parent Fluensulfone Alone 

PRZM-GW model inputs for fluensulfone alone are listed in Tables 2. The outputs are 

presented in Table 3. 

T a e bl 2PRZM -GWI npu tP arame t ers or Fl uensu one AI one 

Input Parameter Value Justification Source 

Application Rate 4 Kg a.i./Ha Maximum use pattern Current label 

Applications per Year 1; every year Maximum use pattern Current label 

Assume 3 weeks after emergency 

Application date See note below date to mimic the requirement of PRZM-GW the minimum 7 days before scenanos 

transplanting 

Hydrolysis Half-life 0 Stable pH 4, 7 and 9 MRID 48574718 

Aerobic Soil Metabolism 90th percentile confidence bound on 

Half-life 17.08 days the mean of six half-lives: 8.05, MRID 48574823 9.12, 9.53, 11.9, 15.0, and 25.4 

Organic Carbon Partition 192 Llkgoc Mean value of 154, 157, 172, 203, MRID 48574833 Coefficient (K0 c) and 275 

Note: Emergency dates: DMV -10/04 (day/month), FLC- 01/01, FLP -15/02, 

GAP- 01105, NCC- 15/05, WIC- 01/05 

Application dates: DMV- 01/05, FLC- 22/01, FLP- 09/03, GAP- 22/05, 

NCC- 05/06, WIC- 22/05 

T a e bl 3 . PRZM -GWO utput or Fl uensu U one AI one 

Modeled Max. Daily Cone. Mean Breakthrough Post-breakthrough 

Scenario (f.lg/L) Time (yrs) Mean (f.lg/L) 

DMV corn 4.93 33.2 3.3 

FL citrus 21 48.8 17.2 

FL potato 0.0252 8.7 0.0065 

GA peanut 1.49 10.4 1.08 

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PRZM-GW model inputs for methyl sulfone alone are listed in Tables 4. The outputs are 

presented in Table 5. 

T a e bl 4 . PRZM -GWI npu tP arame t ers or e tyJ u one one AI 

Input Parameter Value Justification Source 

Application Rate* 0.298 Kg Maximum use pattern Current label a.i./Ha 

Applications per Year 1; every year Maximum use pattern Current label 

Application date See Table 2 

Hydrolysis Half-life 0 Assumed stable Assumption in the absence of data 

Aerobic Soil Metabolism 90th percentile confidence bound on 

Half-life 45.3 days the mean of three half-lives (34.2, MRID 48574829 41.3, and 44 days) 

Represents the mean adsorption 

Organic Carbon Partition 27.2 Koc of methyl sulfone based on MRID 48574834 

Coefficient (Koc) five values (14.3, 17.5, 26.3, 27.5 

and 50.5) 

*0.298 = 4.0 * 7.45% (max detectiOn of methyl sulfone m the aerobic soil metabolism study) expressed as 

fluensulfone equivalent. 

Table 5. PRZM-GW Output for Methyl Sulfone Alone (express as Fluensul fone Eq.) 

Modeled Max. Daily Cone. Mean Breakthrough Post-breakthrough 

Scenario (JLgiL) Time (yrs) Mean (JLg/L) 

DMVcorn 42.2 1.21 26.6 

FL citrus 41.4 1.26 28 

FL potato 13 2.24 6.72 

GA peanut 13.3 3.93 10.1 

NC cotton 19.3 3.49 12.7 

WI corn 59.3 3.58 39.5 

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Modeled Max. Daily Cone. Post-breakthrough 

Scenario (Jlg/L) Mean (Jlg/L) 

DMVcom 47.13 29.9 

FL citrus 62.4 45.2 

FL potato 13.03 6.73 

GA peanut 14.79 11.19 

NC cotton 20.94 13.59 

WI com 77.6 52.5 

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