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OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

February 19, 2015

PC Code: 050410

MEMORANDUM DP Barcode: 424167

SUBJECT: Fluensulfone: Drinking Water Exposure Assessment for Proposed New Uses on 

Turfgrass

FROM: James Lin, Environmental Engineer

Environmental Risk Branch II

Ecological Fate and Effects Division (7507P)

THROUGH: Greg Orrick, Environmental Scientist

Brian Anderson, Branch Chief 

Environmental Risk Branch II

Ecological Fate and Effects Division (7507P)

TO: Michael Doherty, Risk Assessor

Christina Swartz, Branch Chief

Risk Assessment Branch II

Health Effects Division (7509P)

Reuben Baris, Risk Manager Reviewer

Mark Suarez, Team Leader, PM Team 7

Insecticide-Rodenticide Branch

Registration Division (7505P)

1. EXECUTIVE SUMMARY

This assessment provides estimated drinking water concentrations (EDWC) from the use of 

fluensulfone on turf in support of the Health Effects Division’s (HED) human health risk 

assessment. As discussed below, the EDWCs based on turf uses are less than those of the 

previous assessment that was based on cucurbits and fruiting vegetables. Therefore, the EDWCs 

of 77.7 μg/L, and 52.5 μg/L should be used for acute and chronic drinking water exposure,

respectively.

2. USE CHARACTERIZATION

Quali-Pro® Nimitz® 1.5G Nematicide is a granule formulation containing 1.5% of fluensulfone 

active ingredient by weight. The label specifies that applications should be uniformly

broadcasted over turfgrass area suspected to have nematodes or with a history of nematodes. 
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The use rate range is 60 – 120 pounds product per acre with a maximum seasonal amount of 240 

pounds product per year. Depending on nematode populations and damage, applications can be 

made monthly, bi-monthly or sequentially. It is recommended to irrigate following application 

with an adequate amount of water (generally 0.5 inches). The proposed label specifies three 

application scenarios:

 

(1) 60 lb/acre (0.9 lb ai/ac) can be applied at 1 month intervals for 4 consecutive months;

(2) 80 lb/acre (1.2 lb ai/ac) can be applied at 1 month interval for 3 consecutive months; and 

(3) 120 lb/ac (1.8 lb ai/ac) can be made in spring or early summer with a second application 

at the same rate 2-6 months following the initial broadcast.

3. PREVIOUS DRINKING WATER ASSESSMENTS

Two drinking water assessments have been generated for cucurbits and fruiting vegetables uses 

(DP 411774 and DP 417634). The assessments present maximum EDWCs from ground water 

sources (based on PRZM-GW) of 77.7 μg/L, and 52.5 μg/L, for acute and chronic exposure, 

respectively. The residues of concern include parent fluensulfone and the degradate methyl 

sulfone. 

4. DRINKING WATER ASSESSMENT FOR TURF USES

The detailed fate characterizations including product chemistry, transport, mobility, degradation, 

field studies, environmental degradates, and selections of residues of concern have been 

presented in the previous drinking water assessments. Only modeling input information and 

output results are presented in this assessment.

PRZM-GW modeling of Parent Fluensulfone Alone

PRZM-GW (version 1.07) model inputs for fluensulfone alone are listed in Table 2. The outputs 

are presented in Table 3. Three use pattern schemes are represented.
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Table 2. PRZM-GW Input Parameters for Fluensulfone Alone. 

Input Parameter Value Justification Source

Applications per 

Year @ Application 

Rate

[1] 4 @ 1.008 kg/ha

[2] 3 @ 1,344 kg/ha

[3] 2 @ 2.106 kg/ha

Values follow label directions Proposed Label

Application Dates

and Intervals

Assuming 1st

application at Spring 

(March 15), followed 

by monthly interval, 

except for the third 

scheme with only two 

applications, the 

interval is 6 months

Values are within the application 

windows, following label 

directions

Proposed Label

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

Aerobic Soil 

Metabolism

Half-life

17.08 days

90th percentile confidence bound 

on the mean of six half-lives: 

8.05, 9.12, 9.53, 11.9, 15.0, and 

25.4 

MRID 48574823 

Organic Carbon 

Partition Coefficient 

(KOC)

192 L/kgOC

Mean value of 154, 157, 172, 203, 

and 275 MRID 48574833

Table 3. PRZM-GW Output for Fluensulfone Alone

Modeled 

Scenario Max. Daily Conc. (μg/L)

Mean 

Breakthrough 

Time (yrs)

Post-breakthrough Mean 

(μg/L)

DMV corn

[1] 2.96

9.14

2.41

[2] 3.66 2.87

[3] 10.9 7.42

FL citrus

[1] 15.5

7.25

13.2

[2] 15.5 13.6

[3] 11.1 9.73

FL potato

[1] 0.0019

13.03

0.000892

[2] 0.00244 0.00108

[3] 0.00491 0.00219

GA peanut

[1] 1.08

12.04

0.86

[2] 1.17 0.806

[3] 2.2 1.71

NC cotton

[1] 0.679

10.22

0.479

[2] 0.568 0.445
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Modeled 

Scenario Max. Daily Conc. (μg/L)

Mean 

Breakthrough 

Time (yrs)

Post-breakthrough Mean 

(μg/L)

[3] 3.83 2.61

WI corn

[1] 20.5

13.54

16.4

[2] 19.8 16.6

[3] 20.3 16.4

A Maximum values are in bold.

PRZM-GW modeling of Degradate Methyl Sulfone Alone

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

presented in Table 5.

Table 4. PRZM-GW Input Parameters for Methyl Sulfone Alone. 

Input Parameter Value Justification Source

Applications per 

Year @ Application 

Rate

[1] 4 @0.0751 kg/ha

[2] 3 @ 0.1001 kg/ha

[3] 2 @ 0.1502 kg/ha

Values follow label directions Proposed Label

Application Dates

and Intervals

Assuming 1st

application at Spring 

(March 15), followed 

by monthly interval, 

except for the third 

scheme with only two 

applications, the 

interval is 6 months

Values are within the application 

windows, following label 

directions

Proposed Label

Hydrolysis Half-life 0 Assumed stable Absence of data

Aerobic Soil 

Metabolism

Half-life

45.3 days

90th percentile confidence bound 

on the mean of three half-lives: 

34.2, 41.3, and 44 days

MRID 48574829 

Organic Carbon 

Partition Coefficient 

(KOC)

27.2 L/kgOC

Mean value of 14.3, 17.5, 26.3, 

27.5, and 50.5 MRID 48574834

Corrected for maximum detection value (7.45%) of methyl sulfone in the aerobic soil metabolism study, as 

fluensulfone equivalent.

Table 5. PRZM-GW Output for Methyl Sulfone Alone

Modeled 

Scenario Max. Daily Conc. (μg/L)

Mean 

Breakthrough 

Time (yrs)

Post-breakthrough Mean 

(μg/L)

DMV corn [1] 22 3.82 18.2
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Modeled 

Scenario Max. Daily Conc. (μg/L)

Mean 

Breakthrough 

Time (yrs)

Post-breakthrough Mean 

(μg/L)

[2] 24.2 20.7

[3] 30.1 26.2

FL citrus

[1] 33.5

2.71

26.3

[2] 33.9 26.5

[3] 29.4 23.3

FL potato

[1] 6

3.11

3.35

[2] 6.73 3.53

[3] 5.85 4.22

GA peanut

[1] 9.37

4.56

7.96

[2] 9.61 7.57

[3] 9.69 8.38

NC cotton

[1] 13.6

6.04

10.3

[2] 12.4 9.83

[3] 19.9 17.8

WI corn

[1] 41.4

7.49

34.8

[2] 41.2 34.6

[3] 39.2 33.8

A Maximum values are in bold.

Combining Results of Parent Fluensulfone and Degradate Methyl Sulfone

The resulting EDWCs of fluensulfone and methyl sulfone combined are derived by adding the 

contents of Table 3 and Table 5. Table 6 shows the final water values based on ground water 

sources.

Table 6. Final Results of EDWC 

Modeled 

Scenario

Max. Daily Conc. 

(μg/L)

Post-breakthrough 

Mean (μg/L)

DMV corn

[1] 24.96 20.61

[2] 27.86 23.57

[3] 41 33.62

FL citrus

[1] 49 39.5

[2] 49.4 40.1

[3] 40.5 33.03

FL potato

[1] 6.00 3.35

[2] 6.73 3.53

[3] 5.85 4.22

GA peanut

[1] 10.45 8.82

[2] 10.78 8.38

[3] 11.89 10.09
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Modeled 

Scenario

Max. Daily Conc. 

(μg/L)

Post-breakthrough 

Mean (μg/L)

NC cotton

[1] 14.28 10.78

[2] 12.97 10.28

[3] 23.73 20.41

WI corn

[1] 61.9 51.2

[2] 61 51.2

[3] 59.5 50.2

A Maximum values are in bold.

The combined EDWCs of 61.9 μg/L and 51.2 μg/L, respectively for acute and chronic concerns 

are less than the values provided by the previous drinking water assessment for cucurbits and 

fruiting vegetables.