11229CFRCh.XVII(7–1–10Edition)§1926.64studiesshouldbeobtainedinallindividualswithelevatedZPPlevelstobecertainthatanassociatedelevatedbloodleadlevelhasnotbeenmissedduetotransientfluctua-tionsinbloodleads.ZPPhasacharacteristicfluorescencespec-trumwithapeakat594nmwhichisdetect-ablewithahematofluorimeter.Thehematofluorimeterisaccurateandportableandcanprovideon-site,instantaneousre-sultsforworkerswhocanbefrequentlytest-edviaafingerprick.However,carefulattentionmustbegiventocalibrationandqualitycontrolproce-dures.Limiteddataonbloodlead-ZPPcor-relationsandtheZPPlevelswhichareasso-ciatedwiththeadversehealtheffectsdis-cussedinSection2arethemajorlimitationsofthetest.AlsoitisdifficulttocorrelateZPPlevelswithenvironmentalexposureandthereissomevariationofresponsewithageandsex.Nevertheless,theZPPpromisestobeanimportantdiagnostictestfortheearlydetectionofleadtoxicityanditsvaluewillincreaseasmoredataiscollectedregardingitsrelationshiptoothermanifestationsofleadpoisoning.Levelsofdelta-aminolevulinicacid(ALA)intheurinearealsousedasameasureofleadexposure.IncreasingconcentrationsofALAarebelievedtoresultfromtheinhibi-tionoftheenzymedelta-aminolevulinicaciddehydrase(ALA-D).Althoughthetestisrel-ativelyeasytoperform,inexpensive,andrapid,thedisadvantagesincludevariabilityinresults,thenecessitytocollectacom-plete24hoururinesamplewhichhasaspe-cificgravitygreaterthan1.010,andalsothefactthatALAdecomposesinthepresenceoflight.Thepatternofporphyrinexcretionintheurinecanalsobehelpfulinidentifyingleadintoxication.Withleadpoisoning,theurineconcentrationsofcoproporphyrinsIandII,porphobilinogenanduroporphyrinIrise.Themostimportantincrease,however,isthatofcoproporphyrinIII;levelsmayexceed5,000μg/lintheurineinleadpoisonedindividuals,butitscorrelationwithbloodleadlevelsandZPParenotasgoodasthoseofALA.In-creasesinurinaryporphyrinsarenotdiag-nosticofleadtoxicityandmaybeseeninporphyria,someliverdiseases,andinpa-tientswithhighreticulocytecounts.Summary.TheOccupationalSafetyandHealthAdministration’sinterimstandardforinorganicleadintheconstructionindus-tryplacessignificantemphasisonthemed-icalsurveillanceofallworkersexposedtolevelsofinorganicleadabove30μg/m3TWA.Thephysicianhasafundamentalroleinthissurveillanceprogram,andintheoperationofthemedicalremovalprotectionprogram.Evenwithadequateworkereducationontheadversehealtheffectsofleadandappro-priatetraininginworkpractices,personalhygieneandothercontrolmeasures,thephysicianhasaprimaryresponsibilityforevaluatingpotentialleadtoxicityintheworker.Itisonlythroughacarefulandde-tailedmedicalandworkhistory,acompletephysicalexaminationandappropriatelab-oratorytestingthatanaccurateassessmentcanbemade.Manyoftheadversehealthef-fectsofleadtoxicityareeitherirreversibleoronlypartiallyreversibleandthereforeearlydetectionofdiseaseisveryimportant.Thisdocumentoutlinesthemedicalmoni-toringprogramasdefinedbytheoccupa-tionalsafetyandhealthstandardforinor-ganiclead.Itreviewstheadversehealthef-fectsofleadpoisoninganddescribestheim-portantelementsofthehistoryandphysicalexaminationsastheyrelatetotheseadverseeffects.Finally,theappropriatelaboratorytestingforevaluatingleadexposureandtox-icityispresented.Itishopedthatthisreviewanddiscussionwillgivethephysicianabetterunder-standingoftheOSHAstandardwiththeulti-mategoalofprotectingthehealthandwell-beingoftheworkerexposedtoleadunderhisorhercare.[...
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