1 OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

October 20 , 2015

PC Code: 050410

MEMORANDUM DP Barcode: 4 2 8910

SUBJECT: Fluensulfone: Drinking Water Exposure Assessment for Proposed New U ses on

Tuberous and Corm Subgroup 1C , Brassica (Crop Group 5A and 5B), Leafy Vegetables (Crop Group 4), Root Vegetables (Crop Group 1B), Strawberry including low growing berry subgroup (Crop Group 13

- 0 7G), and Tobacco

FROM: J a m es Lin, Environmental Engineer

Environmental Risk Branch II Ecological Fate and Effects Division (7507P)

THROUGH: Ronald Parker

, Senior Environmental Engineer

Brian Anderson, Branch Chief

Environmental Risk Branch II Ecolog ical Fate and Effects Division (7507P)

TO: Michael Doherty, Risk Assessor

Christina Swartz, Branch Chief

Risk Assessment Branch II Health Effects Division (7509P)

AWillis Ertman

, Risk Manager Reviewer

Barbara Madden

, Risk Manager

Insecticide

- Rodenticide Branch Registration Division (7505P)

1. EXECUTIVE SUMMARY

This assessment provides estimated drinking water concentrations (EDWC) from the use of the above subject crop group uses in support of the Health Effects Division’s (HED) human health

risk assessment. As depicted below in Table 1

, the surface water sources for cranberry uses provide the higher values th a n the groundwater sources. Therefore, the EDWCs of 187.84 μg/L,

and 64 .99 μg/L should be used for acute and chronic drinking water exposure, respectively.2

Table 1.1. Maximum Screening Drinking Water Exposure Estimates for Proposed

Fluensulfone Uses. A

Source (Tier: Model) Use (Maximum Rate) Peak Exposure (μg/L) Annual Mean

Exposure (μg/L)

Surface water (Tier I: Cranberry model ) Cranberries (3.5 lb a.i./A) 187.84 64.99

Groundwater (Tier I: PRZM

- GW ) Cucurbits and Fruiting Vegetables. (3.57 lb a.i./A) 77.5 52.5

A Maximum values in bold.

2. USE CHARACTERIZATION

Two labels are proposed for the new uses and they are summarized below:

MCW

- 2 15G (alternate band name Nimitz® 1.5G Nematicides) is a granule formulation containing 15% of fluensulfone active ingredient by weight

. The label use is for nematode

control in roo t crop potato (vegetable, tuberous and corm subgroup 1C). Specifically the use restrictions including:

 Do not apply more than one application per crop. Do not exceed 24 pounds of product

per acre (3.6 lb ai/ac) per year (365 days).

 Do not allow livestock animals (cattle, sheep or horses etc.) to forage or graze on treated areas within 6 months following application.

Fluensulfone 480EC (alternate brand name: NIMITZTM) is an emulsifiable concentrate formulation containing 4 pounds active ingredient (ai) per gallon. The proposed new label uses including:

(1) Brassica (cole) leafy vegetables

– broccoli, cabbage, cauliflower and other brassicas including: broccoli, Chinese (gai lon); broccoli raab (rapini); brussels sprouts; cabbage, Chinese (bok choy); cabbage, C hinese (napa); cabbage, Chinese mustard(gai choy); cavalo broccolo; collards; kale; kohlrabi; mizuna; mustard greens; mustard spinach; rape

greens ; (2) Leafy vegetables

– celery, lettuce (head and leaf) spinach and other leafy vegetables including: amaranth ( Chinese spinach); arugula (roquette); cardoon; celery, Chinese; celtuce; chervil; chrysanthemum, edible

- leaved; chrysanthemum, garland; corn salad; cress, garden; cress, upland; dandelion; dock (sorrel); endive (escarole); fennel, Florence; orach; parsley; purslane, garden; purslane, winter; radicchio (red chicory); rhubarb; spinach, New Zealand; spinach, vine; Swiss chard ; (3) Strawberry and low growing berry

- including: bearberry; bilberry; blueberry, lowbush; cloudberry; cranberry; lingonberry; muntries; p artridgeberry; strawberry; cultivar, varieties, and/or hybrids of these; and (4) Tobacco.

Specifically the use restrictions includ e :3

 Do not make applications when soil temperature is below 55 o F. Root knot nematodes

are not active below 55 o F and will not a bsorb Fluensulfone 480 EC

.

 Do not apply more than one application per crop and no more than 112 fl. oz. of product per acre (3.5 lb ai/ac) per year (365 days)

.

3. PREVIOUS DRINKING WATER ASSESSMENTS

The most recent drinking water assessment for turf uses (DP 424167) has indicated that the drinking water assessment should be based on the uses f or cucurbits and fruiting vegetables uses from groundwater sources (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 for groundwater include parent fluensulfone and the degradate methyl sulfone

.

4. DRINKING WATER ASSESSMENT

4.1 From Groundwater Sources Based on MCW

- 2 15G L abel

According to the label, the maximum application rate is 3.6 lb ai/ac and only allowed for one application per year. 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 A lone

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.

Table 2

. PRZM

- GW Input Parameters for Fluensulfone Alone

. Input Parameter Value Justification Source

One a pplication per

y ear @ maximum

a pplication r ate 4.032 kg ai /ha

(3.6 lb ai/ac) Values follow label directions Proposed Label

Application Date Application can be

made at planting or

pre

- planting two weeks before emergence

date: 03/27 (DMV); 12/18 (FLC); 02/01 (FLP0; 04/17 (GAP); 05/01 (NCC); 04/17

(WIC) Proposed Label

Hydrolysis Half

- life 0 Stable at pH 4, 7 and 9 MRID 4 8574718

Aerobic Soil

Metabolism

Half

- life 17.08 days 90 th percentile confidence bound

on the mean of six half

- lives: 8.05, 9.12, 9.53, 11.9, 15.0, and

25.4 MRID 485748234

Input Parameter Value Justification Source

Organic Carbon

Partition Coefficient (K OC ) 192 L/kg OC Mean value of 154, 157, 172, 203,

and 275 MRID 4 8574833

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 3.97 9.14 3.19

FL citrus 13.4 7.25 10.3

FL potato 0.0162 13.03 0.0063

GA peanut 0.578 12.04 0.45

NC cotton 0.536 10.22 0.302

WI corn 18.2 13.54 15.4

A Maximum values are in bold.

PRZM

- GW modeling of Degradate Methyl S ulfone 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

One a pplication per

y ear @ maximum

a pplication r ate 0.3004 kg ai/ha

(0.2682 lb ai/ac) Values follow label directions Proposed Label

Application Date Application can be

made at planting or

pre

- planting Assuming the application dates as the modeling for the parent Proposed Label

Hydrolysis Half

- life 0 Assumed stable Absence of data

Aerobic Soil

Metabolism

Half

- life 45.3 days 90 th percentile confidence bound

on the mean of three half

- lives: 34.2, 41.3, and 44 days MRID 48574829

Organic Carbon

Partition Coefficient (K OC ) 27.2 L/kg OC Mean value of 14.3, 17.5, 26.3, 27.5, and 50.5 MRID 4 8574834

Corrected for max imum detection value (7.45%) of methyl sulfone in the aerobic soil metabolism study

, as fluensulfone equivalent

.5

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 27.2 3.82 22.7

FL citrus 32.4 2.71 24.1

FL potato 9.9 3.11 5.46

GA peanut 8.43 4.56 6.8

NC cotton 12.9 6.04 9.5

WI corn 40.5 7.49 33.9

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 31.17 25.89

FL citrus 45.80 34.40

FL potato 9.92 5.47

GA peanut 9.01 7.25

NC cotton 13.44 9.80

WI corn 58.70 49.30

A Maximum values are in bold.

The combined EDWCs of 58.7 μg/L and 49.3 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. Therefore, for groundwater sources, the EDWCs of 77.7 μg/L, and 52.5 μg/L should be used for acute and chronic drinking water exposure, respectively.

4.2 From Surface Water Sources Based on Fluensulfone 480EC L abel

Among the proposed new uses including: brassica (Crop Group 5A and 5B), leafy vegetables (Crop Group 4), root vegetables (Crop Grou p 1B), strawberry including low growing berry subgroup (Crop Group 13

- 07G), and tobacco. The maximum application rate is 3.5 lb ai/ac and only allowed for one application per year. Based on the past experience, among all these proposed used, the cranberr y use may have produce the highest EDWC, due to the typical flooding practice for harvest. To assess this use, the provisional cranberry model is used.6 Provisional Cranberry Model

The Provisional Cranberry Model is a provisional refinement to the Tier I Rice Model (v1.0, May 8, 2007) . Refinements include the addition of sim ple degradation processes in dry and flooded conditions and a water depth of twelve inches, rather than the water depth of four inches

used in the rice model. These modification s al low estimation of screening

- level peak and annual

mean EDWC s of fluensulfone residues of concern that may occur in untreated surface water used as drinking wate r following use on cranberries

.

The Tier I Rice Model relies on an equilibrium partitioning con cept to provide conservative estimates of EDWCs resulting from application of pesticides to rice paddies. When a pesticide is applied to a rice paddy, the model assumes that it will instantaneously partition between a water phase and a sediment phase. Th e model does not account for pesticide degradation, mass transfer between the aqueous phase and the sediment, volatilization, dilution, or other dissipation processes. The Tier I Rice Model was calibrated to generate estimates that are consistent with or conservative for dissolved concentrations measured within rice paddies and in discharged paddy

water. The model was not evaluated or calibrated for concentrations measured in sediment and does not account for residues bound to suspended sediment. Guidanc e for using the Tier I Rice Model may be found on the U.S. Environmental Protection Agency (EPA) Wat er Models web

page (USEPA, 2011 a ).

The Provisional Cranberry Model is based on the same assumptions as the Tier I Rice Model,

with the addition of degradation processes in dry and flood conditions and a water depth of twelve inches in the flooded cranberry bog. Degradation of fluensulfone residues of concern is assumed to occur predominantly via aerobic microbial metabolism, whether on dry cranberry bog soil or in bog flood water.

The cranberry bog water depth of twelve inches is a maximum depth recommended by the Cape Cod Cranberry Growers Association (2001). Previous assessments of mesotrione uses that employed the Provisional Cranberry Model ass umed a water depth of eighteen inches (DP

barcode 339984 , USEPA, 2004; DP barcode 325840, USEPA, 2006a), which is within the range of water depths traditionally used. However, modern water conservation pressures are causing cranberry growers to reduce the flood depth to fewer inches above the vertical cranberry branches, which grow up to eight inches high (Cape Cod Cranberry Growers Association, 2001; The Cranberry Institute, 2008). Therefore, a twelve

- inch deep flood is a reasonable refinement

to model a ssumptions.

The proposed use of fluensulfone on cranberries at the maximum application rate of 3.5 lbs a.i./A and only one application allowed per year.

Cranberry bogs are not typically flooded until the night before harvesting. For application of fluensulfone, it is assumed the maximum application rate of 3.5 lb ai/ac was aged on dry soil with the Provisional Cranberry Model for 60 days. The resulting residues (in lbs a.i./A) were

then input into the flooded component of the mod el to estimate exposure in bog tailwater following harvest. Peak and annual mean EDWCs were calculated twenty

- one days after flooding to account for three weeks of holding perio d

.7

The residues of concern from the surface water sources include fluensulf one, methyl sulfone and

deschloro

- fluensulfone , the last one is only detected in the aquatic system, therefore is different from the groundwater sources. The modeling inputs are estimated using available chemical properties and environmental fate data. T able 7 lists the environmental fate parameters for the

total residues of concern ( TRC ) of fluensulfone that a re relevant for exposure modeling. These parameters reflect regression of the total residues at each interval of the biodegradation studies.

For the soil metabolism studies (MRID 48574823, 48574824) the TRC biodegradation half

- lives

were based on the sum of parent fluensulfone and methyl sulfone; whereas for the aquatic metabolism studies (MRID 48574839, 48574840), the TRC biodegradation half

- lives were based

on the sum of parent fluensulfone, methyl sulfone and deschloro

- fluensulfone . B ecause PCA (percent crop area factor) values were not available for non

- agricultural uses, they were not used for exposure estimates in this assessment.

Table 7

. Provisional Cranberry Model Input P arameters for Fluensulfone , Deschloro

Fluensulfone Plus Methyl Sulfone

. Input Parameter Value Comments Source

Application Rate (lbs a.i./A) 3.5 Maximum proposed single application

rate. Proposed label

Applications per Year 1 Maximum proposed number of applications per year at the maximum proposed single application rate. Proposed label

Organic Carbon Partition Coefficient (K OC ) (L/kg OC ) 47.08 Represents the mean K OC of methyl sulfone based on five values (31.3, 37.4, 52.2, 55.4, and 59.1) MRID 48574833

Aerobic Soil Metabolism

Half

- life (days) 24.01 Represents the upper 90% confidence

bound on the mean of five half

- lives (6.73, 8.68, 12.8, 20.2, and 39 days) for fluensulfone + methyl sulfone 48574823

Aerobic aquatic metabolism

half

- life (days) 93.45 Represents the upper 90% confidence

bound on the mean of two half

- lives (85.7

and 89.5 ) 48574839

The results of provisional cranberry model are presented in Figure 1

. The peak EDWC is 187.84 μg/L, and the annual mean EDWC is 64.99 μg/L.

Figure 1

. EDWC for Cranberry Uses

0 100 200

0 100 200 300 400 Aqueous Concentration
(μg/L)

Days After Application 

## Cranberry Bog EDWCs vs Time, After a 21

- d Holding

Period8

4.3 Drinking Water Exposure Conclusions

The EDWCs from the surface water sources for cranberry uses are higher than that from the groundwater s ources, therefore, the final EDWC should be used are 187.84 μg/L and 64.99 μg/L, respectively for the peak value and the annual mean value.