UNITEDSTATESENVIRONMENTALPROTECTIONAGENCYWASHINGTON.D.C.20460January30,2014MEMORANDUMOFFICEOFCHEMICALSAFETYANDPOLLUTIONPREVENTIONPCCode:050410DPBarcode:417634SUBJECT:Fluensulfone:RefinedDrinkingWaterExposureAssessmentforProposedNewRegistrationforUsesonCucurbitsandFruitingVegetablesBasedonGroundWaterSources2JJamesLin,EnvironmentalEngineer__EnvironmentalRiskBranchIIFROM:EcologicalFateandEffectsDivision(7507P)!/)j-Jo-llfTHROUGH:GregOrrick,EnvironmentalScientist-BrianAnderson,BranchChief,'c:jlt/YLEnvironmentalRiskBranchII·FateandEffectsDivision(7507P)TO:MichaelDoherty,RiskAssessorChristinaSwartz,BranchChiefRiskAssessmentBranchIIHealthEffectsDivision(7509P)JenniferGaines,WildlifeBiologistJohnHebert,Team"Leader,PMTeam7Insecticide-RodenticideBranchRegistrationDivision(7505P)Thismemoprovidesrefinedestimateddrinkingwaterconcentrations(EDWC)ingroundwaterfromtheuseoffluensulfoneinsupportoftheHealthEffectsDivision's(HED)humanhealthriskassessment(Table1).Inthecurrentandpreviousdrinkingwatermemos(050410_411774_DWA_08-01-2013),atotaltoxicresidues(TTR)modelingapproachwasused,basedontherecommendationbyROCKS(TheResiduesofConcernKnowledgebaseSubcommitteeofHED).ThepreviousexposureestimatesreflectedtheTotalResiduesofConcern(TRC),whichareasummationoftheparentcompoundandtwotransformationproducts:methylsulfone(MS)anddeschloro-fluensulfone.Sincedeschloro-fluensulfonewasnotformedinthesubmittedaerobicsoilmetabolismstudy(MRID48574823),forgroundwatersystems,theEDWCwillbethesumofparentfluensulfoneandmethylsulfone(MS)only.TherefinedscreeningapproachwillberunningthemodelPRZM-GWseparatelyonefortheparentfluensulfonealoneandtheotherformethylsulfone.TheresultingEDWCisthesumofthetwo modelingruns.Table1providesthe1resultingacuteandchronicEDWCs(77.6and52.5J..lg/L,respectively)thatare87%lessthanthevaluesinthepreviousdrinkingwaterassessment.Table1.FluensulfoneEDWCsinGroundWaterforUseinDietaryRiskAssessmentBasedonthUPttf Cb'tVtbld F't'Vtbleseaernoucur1e2eaesane2eaes.Source(Tier:Model)Use(maximumAcuteEDWCChronicrate)(Jlg/L)EDWC(Jlg/L)CucurbitsandGroundwater(TierI:PRZM-GW)fruitingvegetables77.652.5(4Kga.i./Ha/year)PRZM-GWmodelingofParentFluensulfoneAlonePRZM-GWmodelinputsforfluensulfonealonearelistedinTables2.TheoutputsarepresentedinTable3.Tbl2PRZMGWIa e-nputPtFlarameersorAIuensuoneoneInputParameterValueJustificationSourceApplicationRate4Kga.i./HaMaximumusepatternCurrentlabelApplicationsperYear1;everyyearMaximumusepatternCurrentlabelAssume3weeksafteremergencyApplicationdateSeenotebelowdatetomimictherequirementofPRZM-GWtheminimum7daysbeforescenanostransplantingHydrolysisHalf-life0StablepH4,7and9MRID48574718AerobicSoilMetabolism90thpercentileconfidenceboundonHalf-life17.08daysthemeanofsixhalf-lives:8.05,MRID485748239.12,9.53,11.9,15.0,and25.4OrganicCarbonPartition192LlkgocMeanvalueof154, 157, 172,203,MRID48574833Coefficient(K0c)and275Note:Emergencydates:DMV-10/04(day/month),FLC-01/01,FLP-15/02,GAP-01105,NCC-15/05,WIC-01/05Applicationdates:DMV-01/05,FLC-22/01,FLP-09/03,GAP-22/05,NCC-05/06,WIC-22/05Tbl3PRZMGWOFlUAIa e.-utputoruensuoneoneModeledMax.DailyCone.MeanBreakthroughPost-breakthroughScenario(f.lg/L)Time(yrs)Mean(f.lg/L)DMVcorn4.9333.23.3FLcitrus2148.817.2FLpotato0.02528.70.0065GApeanut1.4910.41.082ModeledMax.DailyCone.MeanBreakthroughPost-breakthroughScenario(JLg/L)Time(yrs)Mean(JLg/L)NCcotton1.6414.50.887WIcorn18.310.813PRZM-GWModelingofDegradateMethylSulfoneAlonePRZM-GWmodelinputsformethylsulfonealonearelistedinTables4.TheoutputsarepresentedinTable5.Tbl4PRZMGWItPtAIa e.-npuarameersoretyJuone oneInputParameterValueJustificationSourceApplicationRate*0.298KgMaximumusepatternCurrentlabela.i./HaApplicationsperYear1;everyyearMaximumusepatternCurrentlabelApplicationdateSeeTable2HydrolysisHalf-life0AssumedstableAssumptionintheabsenceofdataAerobicSoilMetabolism90thpercentileconfidenceboundonHalf-life45.3daysthemeanofthreehalf-lives(34.2,MRID4857482941.3,and44days)RepresentsthemeanadsorptionOrganicCarbonPartition27.2KocofmethylsulfonebasedonMRID48574834Coefficient(Koc)fivevalues(14.3,17.5,26.3,27.5and50.5)*0.298=4.0*7.45%(maxdetectiOnofmethylsulfonemtheaerobicsoilmetabolismstudy)expressedasfluensulfoneequivalent.Table5.PRZM-GWOutputforMethylSulfoneAlone(expressasFluensulfoneEq.)ModeledMax.DailyCone.MeanBreakthroughPost-breakthroughScenario(JLgiL)Time(yrs)Mean(JLg/L)DMVcorn42.21.2126.6FLcitrus41.41.2628FLpotato132.246.72GApeanut13.33.9310.1NCcotton19.33.4912.7WIcorn59.33.5839.53CombiningResultsofParentFluensulfonePlusDegradateMethylSulfoneTheresultingconcentrationsoffluensulfoneandmethylsulfonecombinedarederivedbyaddingthecontentsofTable3andTable5.Table6showsthefinalresultsforestimateddrinkingwaterconcentrationsbasedongroundwatersources.Table6.CombinedResultsforFluensulfonePlusesMethylSulfoneinFluensulfoneEq.ModeledMax.DailyCone.Post-breakthroughScenario(Jlg/L)Mean(Jlg/L)DMVcom47.1329.9FLcitrus62.445.2FLpotato13.036.73GApeanut14.7911.19NCcotton20.9413.59WIcom77.652.54