WHO/HEP/ECH/WSH/2021.6

Nickelindrinking-water

Backgrounddocumentfordevelopmentof

WHOGuidelinesfordrinking-waterquality

ThisdocumentreplacesdocumentreferencenumberWHO/SDE/WSH/05.08/55

WHO/HEP/ECH/WSH/2021.6

?WorldHealthOrganization2021

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iii

Preface

Accesstosafedrinking-waterisessentialtohealth,abasichumanrightandacomponentofeffectivepolicyforhealthprotection.AmajorWorldHealthOrganization(WHO)functiontosupportaccesstosafedrinking-wateristheresponsibility“topropose...regulations,andtomakerecommendationswithrespecttointernationalhealthmatters...”,includingthoserelatedtothesafetyandmanagementofdrinking-water.

ThefirstWHOdocumentdealingspecificallywithpublicdrinking-waterqualitywaspublishedin1958asInternationalstandardsfordrinking-water.Itwasrevisedin1963and1971underthesametitle.In1984–1985,thefirsteditionoftheWHOGuidelinesfordrinking-waterquality(GDWQ)waspublishedinthreevolumes:Volume1,Recommendations;Volume2,Healthcriteriaandothersupportinginformation;andVolume3,Surveillanceandcontrolofcommunitysupplies.Secondeditionsofthesevolumeswerepublishedin1993,1996and1997,respectively.AddendatoVolumes1and2ofthesecondeditionwerepublishedin1998,addressingselectedchemicals.Anaddendumonmicrobiologicalaspects,reviewingselectedmicroorganisms,waspublishedin2002.ThethirdeditionoftheGDWQwaspublishedin2004,thefirstaddendumtothethirdeditionwaspublishedin2006,andthesecondaddendumtothethirdeditionwaspublishedin2008.Thefourtheditionwaspublishedin2011,andthefirstaddendumtothefourtheditionwaspublishedin2017.

TheGDWQaresubjecttoarollingrevisionprocess.Throughthisprocess,microbial,chemicalandradiologicalaspectsofdrinking-wateraresubjecttoperiodicreview,anddocumentationrelatingtoaspectsofprotectionandcontrolofdrinking-waterqualityisaccordinglypreparedandupdated.

SincethefirsteditionoftheGDWQ,WHOhaspublishedinformationonhealthcriteriaandotherinformationtosupporttheGDWQ,describingtheapproachesusedinderivingguidelinevalues,andpresentingcriticalreviewsandevaluationsoftheeffectsonhumanhealthofthesubstancesorcontaminantsofpotentialhealthconcernindrinking-water.Inthefirstandsecondeditions,theseconstitutedVolume2oftheGDWQ.Sincepublicationofthethirdedition,theycompriseaseriesoffree-standingmonographs,includingthisone.

Foreachchemicalcontaminantorsubstanceconsidered,abackgrounddocumentevaluatingtheriskstohumanhealthfromexposuretothatchemicalindrinking-waterwasprepared.Thedrafthealthcriteriadocumentwassubmittedtoanumberofscientificinstitutionsandselectedexpertsforpeerreview.Thedraftdocumentwasalsoreleasedtothepublicdomainforcomment.Commentswerecarefullyconsideredandaddressed,asappropriate,takingintoconsiderationtheprocessesoutlinedinthe

PoliciesandproceduresusedinupdatingtheWHOguidelinesfordrinking-waterquality

andtheWHO

Handbookforguidelinedevelopment

.

Thereviseddraftwassubmittedforfinalevaluationatexpertconsultations.

Duringpreparationofbackgrounddocumentsandatexpertconsultations,carefulconsiderationwasgiventoinformationavailableinpreviousriskassessmentscarriedoutbytheInternationalProgrammeonChemicalSafety,initsEnvironmentalHealthCriteriamonographsandConciseInternationalChemicalAssessmentDocuments;theInternationalAgencyforResearchonCancer;theJointFoodandAgricultureOrganizationoftheUnitedNations(FAO)/WHOMeetingonPesticideResidues;andtheJointFAO/WHOExpertCommitteeonFoodAdditives(whichevaluatescontaminantssuchaslead,cadmium,nitrateandnitrite,inadditiontofoodadditives).

Furtherup-to-dateinformationontheGDWQandtheprocessoftheirdevelopmentisavailableontheWHOwebsiteandinthecurrenteditionoftheGDWQ.

iv

Acknowledgements

Thebackgrounddocumentonnickelindrinking-waterforthedevelopmentoftheWHO

Guidelinesfor

drinking-waterquality

(GDWQ)waspreparedbyDrAkihikoHiroseoftheNationalInstituteofHealthSciencesofJapan,underthecoordinationofWHOasdescribedfurtherbelow.ThesupportofDrMikaTakahashi,formerlyoftheNationalInstituteofHealthSciencesofJapan,inthepreparationofthisdocumentisalsogratefullyacknowledged.

Theworkofthefollowingexpertswascrucialinthedevelopmentofthisdocumentandothersinthesecondaddendumtothefourthedition:

DrMAsami,NationalInstituteofPublicHealth,Japan

DrRJBevan,independentconsultant,UnitedKingdom

MrRCarrier,HealthCanada,Canada

DrJCotruvo,JosephCotruvo&AssociatesandNSFInternationalWHOCollaboratingCentre,UnitedStatesofAmerica

DrDCunliffe,SouthAustralianDepartmentofHealth,Australia

DrAEckhardt,Umweltbundesamt(FederalEnvironmentAgency),Germany

ProfessorJKFawell,CranfieldUniversity,UnitedKingdom

DrAHirose,NationalInstituteofHealthSciencesofJapan

DrAHumpage,UniversityofAdelaide(formerlySouthAustralianWaterCorporation),AustraliaDrPMarsden,DrinkingWaterInspectorate,UnitedKingdom

ProfessorYMatsui,HokkaidoUniversity,Japan

DrEOhanian,EnvironmentalProtectionAgency,UnitedStatesofAmerica

ProfessorCNOng,NationalUniversityofSingapore,Singapore

DrJStrong,formerlyEnvironmentalProtectionAgency,UnitedStatesofAmericaDrETestai,NationalInstituteofHealth,Italy

ThedrafttextwasdiscussedattheexpertconsultationsforthesecondaddendumtothefourtheditionoftheGDWQ,heldon28–30March2017,13–14July2018and2March2021.Thefinalversionofthedocumenttakesintoconsiderationcommentsfrombothpeerreviewersandthepublic,includingVBhat,formerlyNSFInternational,UnitedStatesofAmerica;JDonohue,UnitedStatesEnvironmentalProtectionAgency;BLampe,NSFInternational,UnitedStatesofAmerica;FLemieux,HealthCanada;MTempleton,ImperialCollegeLondon,UnitedKingdom;MZemlyanova,FederalScientificCenterforMedicalandPreventiveHealthRiskManagementTechnologies,Russia;andKZiegler-Skylakakis,TechnicalUniversityofMunich,Germany.

ThecoordinatorwasMsJDeFrance,WHO.StrategicdirectionwasprovidedbyMrBGordon,WHO.DrEPetersen,formerlyofWHO,andDrPVerger,WHO,providedliaisonswiththeJointFAO/WHOExpertCommitteeonFoodAdditivesandtheJointFAO/WHOMeetingonPesticideResidues.DrRBrownandMsCVickers,WHO,providedliaisonswiththeInternationalProgrammeonChemicalSafety.DrMPerezcontributedonbehalfoftheWHORadiationProgramme.DrAndinaFaragher,Biotext,Australia,wasresponsibleforthescientificeditingofthedocument.

ManyindividualsfromvariouscountriescontributedtothedevelopmentoftheGDWQ.Theeffortsofallwhocontributedtothepreparationofthisdocumentaregreatlyappreciated.

v

BMD

BMDL10

BMDU10

bw

CI

CONTAMPanelEFSA

FAO

GDWQ

GV

LOAEL

MOE

NiCl2

NiO

NiS

Ni3S2

NiSO4

NiSO4·6H2O

NOAEL

OR

SCD

USA

WHO

Acronymsandabbreviations

benchmarkdose

95%lowerconfidencelimitonthebenchmarkdosefora10%response95%upperconfidencelimitonthebenchmarkdosefora10%responsebodyweight

confidenceinterval

PanelonContaminantsintheFoodChain(EuropeanFoodSafetyAuthority)EuropeanFoodSafetyAuthority

FoodandAgricultureOrganizationoftheUnitedNations

Guidelinesfordrinking-waterquality

guidelinevalue

lowest-observed-adverse-effectlevel

marginofexposure

nickelchloride

nickeloxide

nickelsulfide

nickelsubsulfide

nickelsulfate

nickelsulfatehexahydrate

no-observed-adverse-effectlevel

oddsratio

systemiccontactdermatitis

UnitedStatesofAmerica

WorldHealthOrganization

vi

Contents

Executivesummary 1

1Generaldescription 2

1.1Identity 2

1.2Physicochemicalproperties 2

1.3Organolepticproperties 2

1.4Majorusesandsources 2

2Environmentallevelsandhumanexposure 3

2.1Water 3

2.2Food 5

2.3Air 7

2.4Bioaccumulation 7

2.5Biomonitoringstudies 8

2.6Estimatedtotalexposureandrelativecontributionofdrinking-water 8

3Toxicokineticsandmetabolisminanimalsandhumans 9

3.1Absorption 9

3.2Distribution 10

3.3Metabolism 10

3.4Elimination 10

4Effectsonhumans 10

4.1Acuteeffects 10

4.2Reproductiveanddevelopmentaleffects 11

4.3Immunologicaleffects 13

4.4Genotoxicityandcarcinogenicity 15

5Effectsonexperimentalanimalsandinvitrosystems 16

5.1Acuteexposure 16

5.2Short-termexposure 16

5.3Long-termexposure 16

vii

5.3.1Systemiceffects 16

5.3.2Neurologicaleffects 17

5.3.3Reproductiveanddevelopmentaleffects 17

5.3.4Genotoxicityandcarcinogenicity 19

5.4Modeofaction 20

5.5Othereffects 21

6Overalldatabaseandqualityofevidence 22

6.1Summaryofhealtheffects 22

6.2Qualityofevidence 22

7Practicalaspects 23

7.1Analyticalmethodsandachievability 23

7.2Sourcecontrol 23

7.3Treatmentmethodsandperformance 23

8Conclusion 23

8.1Derivationoftheguidelinevalue 23

8.2Considerationsinapplyingtheguidelinevalue 25

References 26

Nickelindrinking-water

1

Executivesummary

Nickelisanaturallyoccurringelement.Foodisthemainsourceofnickelexposureinnonsmokerswhoarenotexposedinoccupationalsettings.However,drinking-watermaybecomeasignificantsourcewhennickelleachesfrommetalalloysthatareincontactwiththewater.Elevatednickelindrinking-watercanalsoresultfromheavypollutionormobilizationfromnaturaldepositsinrocksandsoilstogroundwater.Toxicitydataforwater-solublenickelsaltsarethemostrelevanttoassessingpotentialhealthrisksfromnickelexposurethroughdrinking-water.

Humanoralexposuretonickelisprimarilyassociatedwithgastrointestinalandneurologicalsymptomsafteracuteexposure.Exposurethroughskinorbyinhalationmayleadtonickelsensitization.Oralexposuretonickelisnotknowntoleadtosensitization.However,individualssensitizedtonickelthroughskincontactandwhohaveallergiccontactdermatitismaydevelopeczematousflare-upreactionsintheskin(systemiccontactdermatitis–SCD)fromasingleoralexposuretonickelsalts.

Ahealth-basedvalueof80μg/Lfornickelwasderivedforchronicoralexposurebasedonreproductiveanddevelopmentaltoxicityinrats.Theseeffectswereidentifiedasbeingthemostsensitivehuman-relevanteffectsidentifiedfromtheanimaldata,andsomecorrespondingtoxicologicaleffectsweresuggestedinrecenthumanstudies.

Fortheacuteexposureassessment,themarginofexposure(MOE)valuesderivedfromthelowest-observed-adverse-effectlevel(0.3mg/day)associatedwithSCDandtheupper-boundacutedietaryexposure(high-nickel-contentfood)rangedfrom0.3to2.3acrossdietarysurveys,andraiseahealthconcernfornickel-sensitizedindividuals.However,acuteconsumptionofwatercontainingnickelatthechronichealth-basedvalueof80μg/LwouldresultinanMOEofapproximately16.Further,consideringthatSCDelicitationwasassociatedwithabolusexposure,incontrasttotheintermittentnatureofdrinking-waterexposure,thechronichealth-basedvalueof80μg/LisdeterminedtobeadequatelyprotectiveofSCDthatmayresultfromacuteexposure.

Inthecurrentassessment,theexistingguidelinevalue(GV)of70μg/Lisretained,asthedifferencebetweenthehealth-basedvalueof80μg/LandtheexistingGVof70μg/LisnotconsideredsignificantenoughtowarrantaminimalrelaxingoftheGV.Furthermore,theexistingGVisstillconsideredtobeadequatelyprotectiveofhumanhealth,andisfurthersupportedbyavailablesourcecontrolmeasures,currenttreatmenttechnologies,andmeasurabilitybyanalyticalmethods.Asthemajorsourceofnickelindrinking-waterisleachingfromstainlesssteeldevicesormaterialsusedinwatersupplysystemsornickel-orchromium-platedtapsusedinplumbing,flushingthetapbeforedrinking,particularlyafterperiodsofstagnation,isrecommendedfornickel-sensitivepeople.Themostimportantmeansofcontrolisbyproductspecificationsdeliveredthroughanappropriatecertificationschemeformaterialsincontactwithdrinking-water.

Nickelindrinking-water

2

1Generaldescription

1.1Identity

Nickelisanaturallyoccurring,lustrouswhite,hard,ferromagneticmetalthatisubiquitousintheenvironment.Itoccursnaturallyinfiveisotopicforms:58(67.8%),60(26.2%),61(1.2%),62(3.7%)and64(1.2%).

1.2Physicochemicalproperties

SomephysicochemicalpropertiesofnickelareshowninTable1.

Table1.Physicochemicalpropertiesofnickel

Property

Value

Boilingpoint

2837°C

Meltingpoint

1555°C

Density

8.90g/cm3at25°C

Nickelusuallyhastwovalenceelectrons,butoxidationstatesof+1,+3or+4mayalsoexist.Metallicnickelisnotaffectedbywater,butisslowlyattackedbydilutehydrochloricorsulfuricacidandisreadilyattackedbynitricacid.Fusedalkalihydroxidesdonotattacknickel.Severalnickelsalts,includingtheacetate,chloride,nitrateandsulfatesalts,aresolubleinwater.Carbonatesandhydroxidesofnickelarefarlesssoluble,andsulfides,disulfides,subsulfidesandoxidesarepracticallyinsolubleinwater.Alloysofnickelcontainingmorethan13%chromiumarelargelyprotectedfromcorrosioninmanymediabythepresenceofasurfacefilmconsistingmainlyofchromiumoxide(Morgan&Flint,1989;Haudrechyetal.,1994).

Nickeloxide(NiO)hastwoforms:ablackcrystallineform(Antonsen,1981)withanickelcontentof76–77%,andamorestable,greenformwithanickelcontentof78.5%.Nickelammoniumsulfate(Ni(NH4)2(SO4)2),nickelchloride(NiCl2)andnickelnitrate(Ni(NO3)2)usuallyexistashexahydrates,whereasnickelacetate,nickelcyanideandnickelsulfamateareintheformoftetrahydrates(ATSDR,2005).

1.3Organolepticproperties

Nickelanditscompoundshavenocharacteristicodourortaste.Tasteorodourthresholdsfornickelcompoundsinwaterwerenotidentified(ATSDR,2005).

1.4Majorusesandsources

Nickelisusedmainlyintheproductionofstainlesssteels,nonferrousalloysandsuperalloys.Otherusesofnickelandnickelsaltsareinelectroplating,ascatalysts,innickel–cadmiumbatteries,incoins,inweldingproducts,andincertainpigmentsandelectronicproducts(IARC,1990).Itisestimatedthat8%ofnickelisusedforhouseholdappliances(IPCS,1991).Nickelisalsoincorporatedinsomefoodsupplements,whichcancontainseveralmicrogramsofnickelpertablet(EU,2008).

Nickelentersambientwatersprimarilyasnickel-containingparticulatemattercarriedbyrainwater,andthroughthedegradationordissolutionofnickel-containingrocksandsoils(IPCS,1991).Themainanthropogenicsourcesofnickelinwaterareprimarilynickel

Nickelindrinking-water

3

production,metallurgicalprocesses,combustionandincinerationoffossilfuels,chemicalandcatalystproduction,anddischargesofindustrialandmunicipalwastes(EFSA,2015).Theprimarysourceofnickelindrinking-waterisleachingfrommetalsthatareincontactwithdrinking-water,suchasinpipesandfittings.

Nickelisusedprincipallyinitsmetallicform,combinedwithothermetalsandnon-metalsasalloys.Nickelalloysarecharacterizedbytheirhardness,strength,andresistancetocorrosionandheat.

2Environmentallevelsandhumanexposure

Environmentalexposuretonickelofanthropogenicoriginoccurslocallyfrom,amongothersources,emissionsofmetalmining,smeltingandrefiningoperations;industrialactivities(e.g.nickelplating,alloymanufacturing);landdisposalofsludges,solidsandslags;anddisposalofeffluents(IPCS,1991).Ingeneral,nickelisfoundintheenvironmentinawidevarietyofchemicalforms,andconcentrationsarehighlyvariable,reflectingtheinfluenceofnickelemissionsfromdifferenttypesofsources(EFSA,2015).

2.1Water

Nickeloccurspredominantlyastheionnickelhexahydrate(Ni(H2O)62+)innaturalwatersatpH5–9(IPCS,1991).Complexeswithligands,suchashydroxide(OH?),sulfate(SO42?),bicarbonate(HCO3?),chloride(Cl?)andammonia(NH3),areformedtoaminordegreeinthispHrange.Nickelthathasleachedfromnickel-orchromium-platedfittingsisexpectedtobeinasimilarform.

Nickelconcentrationsingroundwaterdependonthesoiluse,pHanddepthofsampling.TheaverageconcentrationingroundwaterintheNetherlandsrangesfrom7.9μg/L(urbanareas)to16.6μg/L(ruralareas).Acidrainincreasesthemobilityofnickelinthesoilandthusmightincreasenickelconcentrationsingroundwater(IPCS,1991).IngroundwaterwithapHbelow6.2,nickelconcentrationsupto980μg/Lhavebeenmeasured(RIVM,1994).Concentrationsofnickelinpristinesurfacewatersmaybesolowastobenearthelimitsofdetectionofcurrentanalyticalmethods(ATSDR,2005).

Nickelconcentrationsintapwatercanbeinfluencedbytheoriginofthewater(surfacewater,groundwater,geologicallayer),itssubsequenttreatmentprocess,pipingandtapmaterial,andstagnationtime.Someevidencesuggeststhatcorrosionofstainlesssteelpipesindomesticwaterdistributionsystemscontributesnickeltowaterdrawnfromtaps,especiallyduringthefirstdraw(DeBrouwereetal.,2012).

InCanada,surveysofdrinking-watersuppliesconductedbetween1985and1988innorthernAlbertaandtheAtlanticprovincesfoundthatmeannickelconcentrationswere2.1–2.3μg/L(HealthCanada,1994).Meanconcentrationswere0.2–7.2μg/Linasurveyof96plantsacrossOntario,withtheexceptionofthoseinSudbury(HealthCanada,1994).IntheSudburyarea,drinking-watersampledbetween1972and1992hadmarkedlyhighermeanconcentrationsof26–300μg/L.Themediannickelconcentrationsinbothtreatedanddistributedprovincialdrinking-watermeasuredinanextensivenationalsurveyofmanyCanadianmunicipalitieswere≤0.6–1.3μg/Lfortreatedwaterand1.8μg/Lfordistributedwater;themaximumvaluewas72.4μg/L(ATSDR,2005).NickellevelsintapwaterfromBritishColumbia,PrinceEdwardIsland,theYukonandtheNorthwestTerritorieswerebelowthedetectionlimit.

Nickelindrinking-water

4

PotabletapwaterintheUSAgenerallycontainsnickelatconcentrationsof0.55–25μg/L(ATSDR,2005;OEHHA,2012).InaSeattle(Washington)study,meanandmaximumnickellevelsinstandingwaterwere7.0μg/Land43μg/L,respectively,comparedwith2.0μg/Land28μg/Linrunningwater(ATSDR,2005).NickelconcentrationsintapwatermeasuredintheUnitedStatesTotalDietStudy1991–1999rangedfrom0to25μg/L,withameanvalueof2μg/L.Analysisofdataobtainedduring1995–1997fromtheNationalHumanExposureAssessmentStudyyieldedmedianconcentrationsofnickelintapwater(usedasdrinking-water)of4.3μg/L(90thpercentile10.6μg/L)intheArizonastudy,and4.0μg/L(90thpercentile11μg/L)intheUnitedStatesEnvironmentalProtectionAgencyRegion5(Illinois,Indiana,Michigan,Minnesota,OhioandWisconsin)study.AccordingtomonitoringdatacollectedbytheCaliforniaDepartmentofHealthServicesbetween1984and1997,thehighest,averageandmedianconcentrationsofnickelinwaterwere540μg/L,26μg/Land17.9μg/L,respectively.

InAustralia,nickelconcentrationsindrinking-wateraretypically<10μg/L.InSampleton,Australia,themeannickelconcentrationindrinking-watersampledbetweenJanuary2002andDecember2005was30μg/L(range<10–220μg/L);theconcentrationsintermittentlyexceededtheAustraliandrinkingwaterguidelinesvaluefornickelof20μg/L(Alam,Corbett&Ptolemy,2008).

InEurope,drinking-watergenerallycontainsnickelatconcentrations<10μg/L(IPCS,1991;ANSES,2005;Cempel&Nikel,2006;WHO,2007;Bertoldietal.,2011;DeBrouwereetal.,2012).Concentrationsupto13μg/Lhavebeenreported(IARC,1990;WHO,2000).In2020,theEuropeanFoodSafetyAuthority(EFSA)evaluatedtheresultsofseveralEuropeansurveysofnickelindrinking-water,whichcollectivelyincluded17831quantifiedsamplesthatwereanalysedbetween2009and2018,withthemajorityofthesamplescollectedbetween2009and2011.Approximately73%ofthesampleswerecollectedinGermany,andapproximately19%werecollectedfromCyprusandSlovakia,withtheremainingsamplescollectedelsewhereinEurope.Theresultsforeachsamplewerereportedaslowerandupperbounds.Meanlowerandupperboundsforallsampleswere2and3μg/L,respectively,and95thpercentilelowerandupperboundswere7μg/Lforbothparameters.IntheUnitedKingdom,medianconcentrationsofnickelindrinking-waterwerereportedforEngland/Wales,NorthernIrelandandScotlandat1.36,1.14and0.3μg/L,respectively(COT,2018).The97.5thpercentileconcentrationsofnickelindrinking-waterinthesethreeregionswere4.63,4.47and1.95μg/L,respectively.Nickellevels<1μg/LhavebeenreportedfromDenmarkandFinland(Punsaretal.,1975;Gammelgaard&Andersen,1985).AveragedissolvednickelconcentrationsinsurfacewaterintheriversRhineandMeusewere<7μg/L(RIWA,1994).

Increasednickelconcentrationsingroundwaterandmunicipaltapwater(100–2500μg/L)werereportedinpollutedareasandareaswherenaturalnickelwasmobilized(McNeely,Nechay&Sunderman,1972).Aftersmelteremissionsdecreasedintheearlytomid-1970s,nickelconcentrationsinpotablewaterofSudburysubstantiallydecreasedbytheearly1980s(Hopfer,Fay&Sunderman,1989).Waterleftstandingovernightinplumbingfittingsplatedwithchromiumonabaseofnickelcontainedanickelconcentrationupto490μg/L,butlowvalueswereobtainedafterflushing;therewasconsiderablevariationatdifferenttimesandfromtaptotap(Andersenetal.,1983).

CertainstainlesssteelwellmaterialswereidentifiedasthesourceofincreasednickelconcentrationsingroundwaterwellsinArizona,USA.Meannickellevelswere8–395μg/L;insomecases,nickellevelswereintherange1–5mg/L(Oakley&Korte,1996).

Nickelindrinking-water

5

Leachingofnickelfromnewstainlesssteelpipeworkintodrinking-waterdiminishedafterafewweeks.Chromiumwasrarelyfoundinthewater,indicatingthattheleakageofnickelwasattributabletopassiveleachingofnickelionsfromthesurfaceofthepipes,ratherthanacorrosiveprocess(Schwenk,1992).Concentrationsofnickelleachingfromnewstainlessstee