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

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

PC Code: 005210 DP Barcode: 398590 May 8, 2012 MEMORANDUM

SUBJECT: Estimated Drinking Water Concentrations of Su lfoxaflor from Use in

Cotton (FIFRA Section 18 Emergency Use in Cotton) for the Use in Human Health Risk Assessment.

TO: Debra Rate , Risk Manager Reviewer

,

Marcel Howard

, Risk Manager, Room 09, RIMUERB
, Registration Division (7505 P )

AND Chris tina Swartz

, Branch Chief, RAB 2

Health Effects Division (7509 P )

FROM: Mohammed A. Ruhman , Ph.D ., Agronomist.

Environmental Risk Branch V

, Environmental Fate and Effects Division (7507 P )

THRU: Mah T. Shamim, Ph.D., Chief

Environmental Risk Branch V

, Environmental Fate and Effects Division (7507 P )


### I. Summary

This memo presents the Estimated Drinking Water Concentrations (EDW Cs) for the total toxic residue resulting from the expected rapid degradation of parent sulfoxaflor (t1⁄2= <1 day) to the toxic

re sidues of concern for drinking water . These residues (hereinafter referred to as TTR) : parent, main degradate X117194

- 74 (hereinafter referred to as X

- 474 ) and degradate of the latter X115195

- 40 degradate (hereinafter referred to as X

- 540 ) for use in an FQ PA human health risk assessment for section 18 use on cotton

.

Sulfoxaflor is characterized by its non

- persistence in soil and low affinity to soil/sediment particles

. The chemical is not expected to partition in significant amount into the air from water in wet and dry soil s

. The degradation profile for sulfoxaflor show very limited a biotic degradation occurring in2

laboratory aqueous systems affected or not affected by sunlight. In the soil system

, parent transforms biologically into a major persistent and highly mobile degradate X

- 474 that may degrade, in some soils to two degradates, namely: X

- 5 40 and X

- 4 7 4 . The latter two degradates can be considered as highly persistent. T he Residues of Concern Knowledgebase Subcommittee ( ROCK S ) decided that the residue s of concern for drinking water are parent , X

- 474 and X

- 5 40 ( DP Barcode D398294 , dated April 6, 2012)

. Source of surface water contamination include drift for parent and run

- off for X

- 474 and X

- 5 40 following the rapid degradation of parent in the soil

. The parent reaching surface water, by drift, is expected to degrade rather slowly to X

- 4 74

. In contrast, the source of ground water contamination is expected to be leaching of the highly mobile parent ( only if rain and irrigation follows application) and its highly mobile degradation products X

- 474 and X

- 540

.

The screening level EDWCs

, from surface water sources

, were calculated using Tier II PRZM (Pesticide Root Zone Model) and EXAMS (Exposure Analysis Modeling System). Tier I SCI

- GROW ( S creening C oncentrat ion in Gro und W ater) model was used for calculating the EDWCs from ground water sources. The estimates for both TTS and individual constituents of the TTS are presented in Table 1 for surface water ( acute “peak” and non

- cancer/cancer chronic values ) and f or groundwater ( acute an d chronic values )

. Modeling included all available cotton scenarios using the maximum application rate , maximum number of applications ( two applications) and the minimu m application interval of 5 day s. Results in Table 1 are for t he highest modeled concentrations.

Table 1 Estimated drinking water concentrations (EDWCs in ppb ) for sulfoxaflor parent , X

- 474

, X

- 540 individually and the TTR from surface and ground waters

Scenario Residue (

s ) of Concern Acute Peak 1 Non

- cancer/Chronic 2 Cancer/chronic 3

Surface Water

TX cotton Parent 2.76 zero zero

X

- 474 zero 0.761 0.417

X

- 540 zero 0.104 0.057 Total (TTR) 2.76 0.865 0.474
Ground Water

Not Applicable Parent zero

X

- 474 39.7 X

- 540 5.4 Total (TTR) 45.1

1 Peak value; 2 Annua l mean values; 3 Overall annual mean values.

Based on the results above, the surface water acute 1

- in

- 10 years peak EDWC is 2.7 6 ppb for the TTR while the surface water non - cancer/chronic 1

- in

- 10 years annual mean EDWC is 0.86 5 ppb for TTR and the 1

- 10

- y ears overall mean cancer/chronic is 0.47 4 ppb for TTR . Concentrations for individual chemicals are included in Table 1 , above.3

For ground water acute/chronic, EDWCs is 45.1 ppb for TTR

. Concentrations for individual chemicals are included in Table 1 , abo ve.

For the procedure used to estimate of the expected concentrations for the various constituents of the TTR, please refer to: EDWCs for the Constituents of the total toxic residue of sulfoxaflor

. The above stated values repres ent upper

- bound estimates o f total concentrations that might be found in surface water and ground water due to the use of sulfoxaflor as an insecticide in cotton

. If more information or refinement is need ed , please call Mohammed A. Ruhman at (703) 605

- 0644.4

EDWCs for the Constitue nts of the total toxic residue (TTR) of sulfoxaflor Degradation profiles for sulfoxaflor in soil and aquatic systems are expected to be the major governing factors in determining the constituents of the TTR that are expected to reach surface and ground wa ters

. Figure s 1 and 2 are conceptual diagram s showing these governing factors along with reasonable estimates of the species present ( Figure 1 for ground water and Figure 2 for surface water) . The conceptual diagrams are based on the degradation profiles o f parent and degradate X

4 74 /X

- 540 and on the assumption that the following statement is added to the label: “do not apply this product if rain or irrigation is expected within 2

- 3 days” . The latter statement is expected to limit the possibility of parent leaching to ground water and/or transported to surface water by run

- off

.

Ground water conceptual diagram Figure 1 shows the conceptual diagram for ground water.

Figure 1 Conceptual diagram for distribution of expected stressor constituents in ground w ater

Application of Sulfoxaflor Parent

Plant Foliage : Parent (major)

Soil S ystem: Parent (major)

Wash

- off Drift

Rapid Aerobic Soil Degradation

Parent (minor) X

- 474 (major)

X

- 540 (minor) X

- 474 (major) Very Slow Aerobic Soil Degradation Parent (major) Direct Application

None *

None *

Run

- off

X

- 474 (major) + X

- 540 (minor) Leaching Leaching

Ground Water N one*= none is expected to be transported Resulting from suggested l abel restriction Leaching
Run

- off

Run

- off Expected soil concentration following very slow degradation in the soil system Surface Water (Refer to Figure 2, below)5

As shown in Figure 1

, the exposure value for the TTR

, of 45.1 ppb , for ground water may be considered from the X

- 474 degradate and its degradation product X

- 540 . This is b ecause the possibility of parent leaching to ground water is expected to be eliminated due to suggested label restriction which increases the residence time for parent to degrade completely befo re it has the opportunity leach to ground water. Based on the maximum observed 12% formation of X

- 540 (from X

- 474 ) in the soil system , the exposure acute/chronic value of 45.1 ppb may be divided to 39.7 ppb from X

- 474 and 5.4 ppb from X

- 540 . It is noted however, that these values are conservative due to the following reasons:

(1) The amount of X

- 474 that is available for leaching is expected to be lowered as a result of its expected movement into the plant ( X

- 474 is systemic); (2) The amount of X

- 540 that is available for leaching is expected to be lowered as it depends in the amount/soil resident time of its parent X

- 474

. X

- 474 is expected to be leached and transported into the plant causing reduction in the amount/soil residue time available for it to degrade into X

- 540 ; noting that transformation of X

- 474 into X

- 540 is expected to occur only in the soil system before it reaches ground water ( X

- 474 is hydrolytically stable). (3) Observed leachate concentrations for chemicals similar to the total toxic residues of sulfoxaflor (long half

- lives and very low K oc values ) in prospe ctive ground water studies were observed to be much lower than values predicted by SCIGROW when rates are standardized to the maximum rate used for sulfoxaflor. This indicates that SCIGRO predicted EDWCs for this chemical might have been overestimated

.6

S urface water conceptual diagram Figure 2 shows the conceptual diagram for ground water.

Figure 2 Conceptual diagram for distribution of expected stressor constituents in surface water

A s shown in Figure 2

, expected constituents of sulfoxaflor TTR in surface water , at the acute and chronic levels, are govern by the drift contribution and the degradation profile for parent and X

- 474 in aquatic systems in addition to run

- off contribution of X

- 474 and X

- 540 transported from the soil system

. D rifted parent sulfoxaflor will be the major species at the short

- term and as run

- off reaches aquatic system ( X

- 474 loading) the major species at the medium

- term is expected to be parent + X

474 . At the l

ong - term parent degrades further to X

- 474 (X

- 474 loading) and with run

- off ( X

- 474 + X

540 loading), the species present are expected to be: X

- 474 (major) + X

- 540 (minor) ; at this time frame parent is expected to be long gone due to degradation

.

In order t o determine the contribution of drift to surface water EDWCs, the chosen scenario was modeled with and without drift. Table 2 contains a summary of the results. App lication of Sulfoxaflor Parent

Drift

Parent (Minor)

X

- 540 (minor) X

- 474 (major) Aquatic Systems : Parent (major)

Slow Aerobic/Anaerobic Aquatic Degradation Direct Application

Un

- degraded Parent (Major)

X

- 474 (From parent degradation) + From Run

- off) (Major) None *

X

- 540 (minor) Run

- off

Ground Water (refe r to Figure 1 above) Run

- off

Run

- off Expected soil concentration following: Fast

degradation of parent and slow degradation of X

- 474 in the soil system Plant Foliage : Parent (major)

Soil System: Parent (major)

Surface Water

None*= none is expected to be transported Resulting from suggested l abel restriction Wash

- off7

Table 2 Estimated drinking water concentrations (EDWCs in ppb) for sulfoxaflor from surface wa ters

Scenario Exposure Source Acute Peak 1 Non

- cancer/Chronic 2 Cancer/chronic 3

TX cotton (Aerial) Run

- off 2. 524 (91.5 %) 0.776 (90%) 0.386 (81%)
Drift 0.234 (8 .5 %) 0.089 (10%) 0.088 (19%)
Total 2.758 (100%) 0.865 (100%) 0.474 (100%)

1 Peak value; 2 Annual mean values; 3 Overall annual mean values.

Results of this modeling exercise suggest that only 8 .5 % of the modeled acute exposure value of 2.7 58 ppb may be considered as acute exposure. This value is equal to 0.234 ppb (2.76 x 0.085= 0.234) fr om parent alone as it is the only species reaching surface waters from drift just after application

. Giving EFED suggested label restriction, 2 to 3 day of parent presence in the soil system will cause it to degrade to X

- 474 before it is transported to su rface waters by run

- off. The n on

cancer/Chronic and Cancer/chronic values of 0.865 and 0.474 are expected to be from (X

- 474 + X

540 ) and concentration may be divided between the two degradates based on the maximum observed 12% formation of X

- 540 (from X

- 4 74 ) in the soil system (the source of exposure

, X

- 540 was not observed in laboratory aquatic studies ). This gives n on

- cancer/Chronic and Cancer/chronic values of 0.761 1 and 0.417 2 ppb from X

- 4 74 and 0.104 3 and 0.057 4 ppb from X

- 5 40 . This is based on the fa ct that the only source of X

- 5 40 is run

- off following its formation in the aerobic soil system and that the maximum X

- 5 40 formed from X

- 474 in the soil was observed to be 12%. Parent is not expected to be present at this time frame.

II. Background

Missis sippi Department of Agriculture and Commerce have submitted a request for the emergency use of Transform TM WG insecticide (50% a.i of sulfoxaflor) to control the tarnished plant bug, Lygus lineolaris on Cotton.

Sulfoxaflor (XDE

- 208; C yanamide, N

- [methyl oxido[1

- [6

- (trifluoromethyl)

- 3

- pyridinyl]ethyl]

- lambda 4

- sulf

anylidene] ; CAS No. 946578

- 00

- 3 , PC code 005210) consists of two diastereomers in a ratio of approximately 50:50. Currently, the chemical is being considered for a new chemical registration for m any proposed uses including some grains, most vegetables, canola (rapeseed), citrus, cotton, low growing berries, ornamentals, turf, most fruit and tree nuts, root and tuber vegetables, soybean, succulent/edible and dry beans.

Sulfoxaflor is a sap

- fe eding insecticide (i.e. systemic) and is from a new class of insecticides, the sulfoxamines. Sulfoxamines act through a unique interaction with the nicotinic acetycholine receptor in insects. Relative to neonicotinoids, sulfoxaflor is a highly efficacious agonist of the

1 Value derived as follows: o.865 ppb x 88%= 0.761 ppb
2 Value derived as follows: 0.474 ppb x 88%= 0.417 ppb
3 Value derived as follows: 0.865 ppb

– 0.761= 0.104 ppb
4 Value derived as follows: 0.474 ppb

– 0.417= 0.057 ppb8

nicotinic receptor with low binding affinity for the imidacloprid binding site. The structural novelty of sulfoxaflor makes it stable in the presence of monooxygenase enzymes that degrade neonicotinoids and cause virtually all known cases of neonicotinoid resistance in the field.

As per the submittal, sulfoxaflor is to be applied by a ground or aerial sprays. The submittals stated the following: Cotton crop is to be treated with a maximum of two applications at a maximum single rate of 0.08 6 lb a.i/A with a minimum of 5

- day intervals and a maximum seasonal rate of 0.172 lb a.i/A; Cotton acreage to be treated is 300,000 acres ; and The maximum seasonal usage will be 1 03,125 lbs of product or 51,562.5 lbs of active ingredient

.



### II I . Environme ntal fate of Sulfoxaflor

Sulfoxaflor is soluble in water (570 ppm @ pH 7 ) . If moisture is available, the chemical is expected to be completely soluble and available for leaching given the fact that expected concentrations , from single application, is much below 570 ppm on the top 6” of the soil (expected concentrations is 0.04 ppm assuming the total single application of 0.086 lb a.i/A reaches and mixed in the top 6” of the soil). The chemical is not expected to partition in significant amount into the air from water and wet and dry soil (Vapor pressure= 1.88 x 10 - 6 torr and calculated Henry’s Law constant= 4.2 x 10 - 11 atm m3 mol - 1 @25 o C). The chemical structure s and name s of diastereomeric pairs are presented in Figure 3

. Figure 3 Sulfoxaflor chemical st ructure and relevant data9

Degradation Profile for Sulfoxaflor parent Based on abiotic laboratory studies, sulfoxaflor is stable to photolysis on soil and to hydrolysis in acidic, neutral and alkaline systems (MRIDs: 478320

- 21 and 478321

- 49, respectivel y) . Aqueous photolysis is expected to be slow and may not be considered an important transformation route in the natural environment (t1⁄2 >1,000 days in de

- ionized water and 637 days in natural water ; MRIDs: 478322

- 83/84 , respectively ). In the aerobic soil system, sulfoxaflor degrades rather quickly to its major degradate X

- 474 (90 th percentile t1⁄2= 0.4 days, n=8 and a range of <0.1 to 0.6 days). In eight US and EU soils, sulfoxaflor reached non detection within one day in one soil, 3

- 4 days in five soils, an d 7

- 14 days in two soils (MRIDs 478655

- 78 & 478320

- 13)

. Other residues, forming as a result of aerobic soil biotransformation, includes limited amounts of two transformation products ( Maximums 9

- 12%) of degradates X

- 11579

- 57 and X

- 540

. Anaerobic soil data suggest that anaerobic conditions produces the main degradate X

- 4 74 and with very limited amount of CO 2 from much slower rate of transformation than aerobic conditions (MRIDs 478322

- 79 & 478320

- 13). In contrast to the rapid degradation of sulfoxaflor in ae robic soil systems, the chemical degrades rather slowly to X

- 474 in both aerobic and anaerobic aquatic conditions (MRIDs 478320

- 14 & 473723

- 11 with 90 th percentile t1⁄2= 141 days, n=2 & 672 days, n=2, and a range of 37 to 88days & 103 to 382 days, respective ly). Based on laboratory studies, Figure 4 summarize s expected degradation pathway in important compartments of the natural

env ironment for parent sulfoxaflor and degradates.10

Figure 4 Expected environmental degradation pathways and transformation profile s for Sulfoxaflor

* Half

- lives were >1,000 days in US soils with no degradates observed. In contrast, half

- lives ranged from 85

- 381 days in EU soils producing degradate X

- 5 40 & X115794

- 57. Separate aerobic soil experiments sh owed that both of these degradates are persistent (90 th percentile half

- lives were 526 days (range 96 to 670 days) for X115794

- 57 and 2,808 days (range 71 to 3,630 days) for X

- 5 40

In the field, sulfoxaflor dissipated rapidly, mainly by degradation, in t he top 6” of the soil into its main degradate X

- 4 74 (observed half

- lives: in bare

- plots= 0.3 to 2 .0 days in CA, FL, ND, ON and 8.1 days in TX; in cropped plots, half

- lives ranged from 0.1 to 1.9 days). Generally, field data for sulfoxaflor transformation agrees with that predicted from laboratory data.

Sulfoxaflor Degradation Products

As shown in Figure 4 , above, only one major and two minor degradates are expected to be important in the natural environment; X

- 4 74 (major degradate) and X

- 5 40 and X115794

- 57 (minor degradates). The minor photolysis degradate X117210

- 61 is expected to form only in shallow clear surface waters at low concentrations. Additionally, the degradate X

- 117189

- 22 is expected to be of minor importance as it is expected to form by aq ueous photolysis from the highly persistent degradate X

- 4 74

. Rapid Bio

- degradation (90 th percentile t1⁄2= 0.4 days) (Aerobic Soil System)

Slow Aqueous Photolysis ( t 1/2 = 261 days) Very Slow Aqueous Photolysis (Practically Stable) Sulfoxaflor Parent

X117210

- 61

X117189

- 22 X

- 4 74

X115794

- 57 X

- 5 40 Very Slow Biodegrada tion * (90 th percentile t1⁄2= 825 days) (Aerobic Soil System)11

Data suggest that the major transformation product X

- 4 74 is persistent to highly persistent in the soil system (t1⁄2 range from 85

- 381 days in tested EU soils and is >1,000 days in tested US soil s ). Relative persistence was also observed for the minor degradates X

- 5 40 and X115794

- 57 in the same aerobic soil systems. In separate aerobic soil metabolism studies on these two degradates (as a test substance) , calculated half

- lives ranged from 71 to > 1 ,000 days for X

- 5 40 and from 96 to 670 days for X115794

- 57.

Mobility for Sulfoxaflor parent and Degradates

Laboratory mobility data suggest that sulfoxaflor and all degradates is of similar high mobility. Adsorption coefficients (K oc’ s) were determined f or many soils with varied characteristics in pH, organic matter and texture. Determined K oc ranged from 7 to 68 mL g - 1 for parent, 7 to 74 mL g - 1 for X

- 474 , 1

- 25 mL g - 1 for X

- 5 40 and 2

- 44 mL g - 1 for X115794

- 57. In the soil system, parent is not expected to be persistent but is expected to be highly mobile. Parent low persistence reduces the likelihood for leaching into ground water in spite of its high mobility ; unless leaching occurs within few days of application . In contrast, the relative high persistenc e for sulfoxaflor degradates

, ( X

- 474 degradate and its degradate X

- 540 )
, coupled by expected high mobility suggests high possibility for these degradates to contaminate ground water in most soils.



### I V . Estimating Drinking Water Exposure from Surface Water Sources

Sulfoxaflor is a new insecticide and no surface water monitoring data is available. For this reason, the Agency based this report on simulated screening values using Tier II PRZM/EXAMS. The screening assessment for sulfoxaflor was completed usin g Tier II PRZM/EXAMS program for drinking water. The following steps were taken to perform a model run for section 18 use pattern on cotton :
(1) Determination of Application Parameters

Currently suggested label, for section 18 on cotton, includes a maxi mum single application rate of 0.086 lb a.i/A (0.0964 kg a.i/ha), a maximum of 2 applications and a minimum of 5

- day interval. The maximum seasonal label rate is 0.172 lb a.i/A (0.193 kg a.i/ha).

(2) Determination of Stressor

The Residues of Concern Know ledgebase Subcommittee (ROCKS) decided that the residues of concern fo r drinking water are parent , X

- 4 74 and X

- 5 40 . I n an agricultural setting, sulfoxaflor is expected to be applied into variable density foliage of growing crops ; depending on application
t iming. Upon application, only limited quantities of the pesticide is expected to be carried away by drift (to adjacent terrestrial and aquatic systems) with the important part being deposited into target plants and later affected by wash

- off into the soil for the part that did not enter the plant tissues (parent is systemic)

.12

Sulfoxaflor deposited on the plant foliage is affected by its systemic nature. Plant residue data indicate that it enters the plant and is incorporated into the plant foliage with o nly limited degradation. The same data also suggest that the degradate X

- 4 74 is also systemic and enters the plant from the soil (following rapid parent degradation). Parent entering the plant through foliage and X

- 4 74 entering the plant from soil may be a source of exposure depending on the agricultural practices for plant residues. This exposure pathway is not considered here because it is difficult to assess as it is highly dependent on the type of plant and density of the foliage (application timing and plant type). In contrast, sulfoxaflor reaching the soil system from foliage wash

- off will be subjected to rapid degradation to X

- 4 74 (main soil degradate) which degrades, in some soils, very slowly producing relatively low concentrations of X

- 540 and X115 794

- 57. Parent may be transported by run

- off and/or leached to groundwater only if heavy rain follows application to soils vulnerable to erosion and/or leaching. In contrast, persistent and highly mobile X

- 4 74 is expected to be highly affected by run

- off a nd leaching causing surface and groundwater contamination. Another source of surface /ground water contamination , by degradate X

- 4 74 and to less extent parent, is plant residue left after the crop is harvested ; this exposure is not considered here

.

Sulfox aflor carried away by drift to adjacent terrestrial systems will be subjected to the processes described above. However, sulfoxaflor reaching aquatic systems is expected to persist longer than that reaching the soil. This is due to the fact that sulfoxaflo r shows relative stability to biodegradation in aquatic systems and it is stable to hydrolysis and aqueous photolysis is not a major route of degradation ( especially in most aquatic system which is not clear and shallow )

.
(1) Scenarios and Input Parameters U sed in modeling

Three standard scenarios were used for modeling to represent the major cotton areas of the United States. The scenarios are NC cotton, TX cotton and MS cotton. Other input parameters used in modeling are included in Table 3 . The parameters , including half

- lives, were re

- calculated for the stressor, the total toxic residue from radioactivity data . The method for calculating some of the input parameters and the basis for choosing the others are also included in Table 3 . All runs were based on two application at a single rate of 0.0964 kg a.i/ha. The first application was chosen to be early July for one set of modeling runs and August, 7 for a second set of modeling runs.13

Table 3 Summary of PRZM/EXAMS input parameters for modeling Sulfoxaflor TTR

Input Parameter (Unit) Value Reference (MRID No ) and Notes

Molecular Weight g/mole 277.27 Product chemistry Henry’s constant (atm

- m 3 mol - 1 @ 20 o C) 1.2 x 10 - 11 Calculated

Solubility in Water(mg/L) 570 Product chemistry Photolysis in Water (t1⁄2 in days @ pH 7) Stable Because the only photolysis degradate is included (MRID 478322

- 83)

Aerobic Soil Metabolism (90 th % t1⁄2 in days) 2,332 Range for US soils= 1,386 to 2,310 compared to 136 to 578 in EU soils (MRIDs 478655

- 78 and 478320

- 13) Hydrolysis ( 90 th % t1⁄2 in days) Stable All degradates are stable (MRID 478321

- 49) Aerobic Aquatic Metabolism (Whole system t1⁄2 in days) 1,761 (MRID 478320

- 14) Range from 2 89 to 1,733 , the low half

- life is associated with 1.7% CO 2 Anaerobic Aquatic Metabolism (Whole s ystem t1⁄2 in days) 655 (MRID 478322

- 77) Range from 131 to 495, the low half

- life is associated with high Un

- extractable residue (25%)

K fo c (Average in L Kg - 1 ) 30 (MRID 478320

- 14) Use K f

oc for the dominant Degradate

- 74 Noting that K foc for parent= 35 L kg

- 1 and for

X115195

- 40= 14 L kg

- 1 Chemical Application Method (CAM) 2

Parameter Guidance 5 Application Efficiency 95% for aerial 99% for ground

Spray Drift Fraction Aerial (0.16) Ground: Airblast (0.063)

and others (0.064)

Table 4 contains only the re sults obtained f or the scenario with the highest EDWCs 6 resulting from aerial and ground application on cotton.

5 Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides. URL http://www.epa.gov/oppefed1/models/water/in put_parameter_guidance.htm

6 Highest EDWCs were chosen from Twelve model simulations ( Three scenarios “ NC cotton, TX cotton and MS cotton ” x Two application dates x Two application methods ; 3 x 2 x 2= 12 )14

Table 4 The highest e stimated drinking water concentrations (EDWCs) for sulfoxaflor residue in surface water

Scenario Application Type Acut e Peak 1 Non

- cancer/Chronic 2 Cancer/chronic 3 Surface Water

TX cotton Air 2.76 0.865 0.474

1 Peak value; 2 Annual mean values; 3 Overall annual mean values.



### IV. Estimating Drinking Water Exposure from Ground Water Sources

Sulfoxaflor is a new insect icide and no ground water monitoring data is available. For this reason, the Agency used Tier I SCI

- GROW model, a high exposure tier one model, for arriving at the Estimated Drinking Water Concentration s (EDWC s ) for this chemical in ground water sources. Table 5 summarizes the inputs and Table 6 contains a summary of the output.

Table 5 Summary of SCI

- GROW input parameters for fluopyram

Parameter Value* Reference (MRID Number)

Application Rate (lb a.i./acre) Number of Applications/Year 0.08 6 x 2 Refer to (1), above” Determination of Application Parameters”
Aerobic Soil Metabolism t1⁄2 (days) 987 Median of 8 values (MRID s 478655

- 78 & 478320

- 13

Koc ( L Kg - 1 ) 23 Median of 17 values (MRID 478320

- 18 ) ** * As per Guidance for Selecting Input Param eters in Modeling the Environmental Fate and Transport of Pesticides. Referenced above ** Median value for the dominant chemical in the residue of concern; that is X

- 4 74 , noting that the median value for parent is slightly higher (31 L Kg - 1 ) and for X

- 5 40 is much lower (13 L Kg - 1 ).

Table 6 Summary of output from SCI

- GROW for fluopyram

Parameter Modeled Value (ppb) Reference

EDWC (2 applications) 45.1 Output form model run & Corrected output form model run15



## References

Section 18 Application

- Sulfox aflor, Mississippi Cotton , Submitted by the Missis sippi Department of Agriculture and Commerce, P.O Box 5207, Mississippi State, MS 39762 ; February 2, 2012

MRID 47832149 Laughlin, L. A., 2009, Hydrolysis of XDE

- 208 at pH 5, 7, and 9 , Dow AgroSciences LLC . Report Number: 0 70102, Report Date: 3

- Mar

- 2009; 38 pages.

MRID 47832283 M. Ma, 2010, Aqueous Photolysis of XDE

- 208 and X11719474 in pH 7 Buffer Under Xenon Light, Dow AgroSciences LLC. Report Number: 090073, Report Date: 6

- May

- 2010; 86 pages.

MRID 478 32284 R. N, Yoder, 2010, Natural Water Photolysis of XDE

- 208 and the X11719474 Metabolite under Xenon Light, Dow AgroSciences LLC. Report Number: 090088, Report Date: 1

- Apr

- 2010 ; 69
pages

.

MRID 47832014 Laughlin, L. A., Adelfinskaya, Y., Balcer, J. L., 201 0, Aerobic Transformation of XDE

- 208 in Two European Aquatic Sediment Systems , Dow AgroSciences LLC. Report Number: 080138, Report Date: 18

- Mar

- 2010. 97 pages.

MRID 47832277 R. N. Yoder, A. G. Stephon., 2010, Anaerobic Aquatic Degradation of XDE

- 208 in Tw o US Sediment and Pond Water Systems , Dow AgroSciences LLC. Report Number: 070105, R eport Date: 8

- Jun

- 2010. 83 pages.

MRID 47832018 R. N. Yoder., D. Liu, 2010, Adsorption/Desorption of XDE

- 208 and Adsorption of Three XDE

208 Soil Metabolites, Dow AgroScie nces LLC. Report Number: 080161, Report Date: 4

- Jan

2010. 153 pages.

MRID 47865578 D. Liu, R. N. Yoder, Y. A. Adelfinskaya, 2010, Aerobic Degradation of XDE

- 208 in Four US Soils, Dow AgroSciences LLC. Report Number: 080130, Report Date: 11

- Jun

- 2010. 107 pages.

MRID 47832013 R. N. Yoder, A. G. Stephon, J. L. Balcer, 2009. Aerobic and Anaerobic Degradation of XDE

- 208 in Four European Soils, Dow AgroSciences LLC. Report Number: 080129, Report Date: 8

- Sep

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