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更新时间:2022-11-16 01:04:22 阅读：评论：0

新标准初中英语下载-合比定理

2022年11月16日发(作者：高丽参怎么吃)

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DefiningBiomarkers

Biomarkersaremeasurablesubstancesorcharacteristicsinthehumanbodythat

canbeudtomonitortheprenceofachemicalinthebody,biologicalrespons,

ofbiomarkerswillhelpuvaluatepotential

exposurestopesticidesaswellaspredicteffectsthatmayresult,allowingusto

kersare

commonlygroupedintobiomarkersofexposure,effect,b

pagedescribesthegroupsofbiomarkersandprovidexamples.

Onthispage:

BiomarkersofExposure

BiomarkersofExposureCategories

BiomarkersofEffect

BiomarkersofEffectCategories

BiomarkersofSusceptibility

BiomarkersofExposure

Biomarkersofexposureareudtoassstheamountofachemicalthatisprent

emicalscanbemeasuredinurine,blood,saliva,and,if

theyarefatsoluble,inbodyfatandbreastmilk(e.g.,DDT).Biomarkersofexposure

provideinformationon

chemicalexposuresinindividuals,

changesinlevelsovertime,and

variabilityamongdifferentpopulations.

Theymayalsoprovideinformationontherelativeimportanceofdifferentexposure

portanttonotethatthemeasurementofa

chemicalinsomeone’sbodydoesnotbyitlfmeanthatchemicalhascaud

adverhealtheffects.

Additionally,thereareanumberofusrelatedtotheinterpretationofbiomarkers

mple,themeasurementof3-phenoxybenziocacid(3-PBA)in

urineisconsideredanon-specificbiomarkerofexposurebecau3-PBAisa

ore,additional

informationisneededtoresolvewhichpyrethroidwastheparentchemical.

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BiomarkersofExposureCategories

Chemical–Themostspecificexposurebiomarkerisdirectmeasurementof

lly,measurementofthe

chemicalismadeinanaccessiblebiologicalmatrix(e.g.,blood,urine).

Whilesomepesticidescanbedirectlymeasuredinthebody,itisgenerally

morecommontomeasuremetabolitesofpesticides.

Metabolite–Manychemicalsarerapidlymetabolizedordifficulttomeasure.

Inthecas,amorestablebreakdownproduct(metabolite)ofthe

metabolitemayderivefromanumberofdifferentchemicals(asinthe

3-PBAexampleabove),additionalinformationisneededtoresolveto

whichchemicalthepersonwaxpod.

Endogenoussurrogate–Insomecas,achemicalorclassofchemicals

mayresultinanendogenousrespon(responwithinthebody)thatis

esofthatrespon

canbeudasasurrogateinlieuofdirectmeasurementofthechemicalor

metaboliteconcentrationwhensufficientadditionalinformationisavailable.

Sincetherearemanyfactorsthatcaninfluenceendogenousrespons,

thistypeofexposurebiomarkerisaccompaniedbymanyuncertaintiesthat

shouldbeidentifiedanddiscusd.

SeeexamplesinTable1

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BiomarkersofEffect

Biomarkersofeffectareindicatorsofachangeinbiologicfunctioninrespontoa

,theymoredirectlyrelatetoinsightintothepotentialfor

adverhealtheffectscomparedwithbiomarkersofexposure.

Oneexampleofabiomarkerofeffectisbloodcholinestera,whichcanbecome

depresdfollowingexposuretoorganophosphateandN-methylcarbamate

ingcholinesteralevelscanbeaufultoolformonitoring

agriculturalworkersandidentifyingworkersthatmaypotentiallybeoverexpodto

pesticides.

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BiomarkersofEffectCategories

Bioindicator–Anidealbiomarkerofeffecthasanexplicitlyknown

cas,

thisisachievedbyasufficientunderstandingoftheadveroutcome

pathwayormodeofactionofthechemical,andthecausalorcorrelative

relationshipofbiologicaleventsbetweenthemarkerandtheadver

outcome.

Bioindicatorsprovideahighdegreeofconfidenceinpredictingthe

potentialforadvereffectsinanindividualorpopulationbadonmarker

rstandingoftheadveroutcomepathwayalsosupports

developmentofavarietyofbioindicatorsfordifferentkeyeventsor

outcomesofinterest(e.g.,markersforprecursoreventsleadingtoa

clinicallydetectableadveroutcometosupportearlydetectionand

prevention).

Whencellularormolecularinitiatingeventscanbeidentifiedascritical

stepsinanadveroutcomepathway,bioindicatorscanbedevelopedin

conjunctionwithhighthroughputscreeningassaystoprovidearapidand

efficientmeansforearlydetectionofadveroutcomesintarget

earchersareactivelydevelopingthisclassof

biomarkersofeffectsinsupportofToxicityTestinginthe21stCentury.

Undeterminedconquence–Thissubgroupofbiomarkersprovides

morelimitedanduncertainindicationofthepotentialforadvereffects,

becautheeventsordeterministiclinkagesinanadveroutcome

plewouldbemarkersofoxidative

stresswhereelevationshavebeenassociatedwithavarietyofadver

outcomes,ole

ofoxidativestressindifferentdiaprocess(andadveroutcome

pathways)becomesmoreclearlydefined,therewillbeincreasingcertainty

intheuofoxidativestressbiomarkerstopredictthepotentialfor

organism/ile,thebiomarkerscanbe

udinconjunctionwithotherbiomarkersinthisorothersubgroupsto

improvethespecificityandnsitivityoftheoveralltofmarkersfor

developmentofanadveroutcome.

Exogenoussurrogate–Somechemicalshavewellknownadvereffects,

whichareaccompaniedbyothereffectsthatcanbeudassurrogate

nexampleis

paranitrophenol,ementin

humansofparanitrophenolintheurinehasbeenudasanexogenous

surrogatebiomarkerofexposuretomethylparathion,andasanindicator

ofthepotentialfortoxicityduetomethylparathion-induced

acetylcholinesterainhibition.

Exogenoussurrogatebiomarkersaresuboptimalaffectsmarkers

becautheydonotdirectlycapturethecontributionofadditionalfactors

(intrinsicandextrinsic)thatmayinfluencetheincidenceorverityofan

helimitations,uofexogenoussurrogatesas

biomarkersismostlylimitedtomeasurementofthoeffectsthatare

predominantlyduetothechemicalofinterest(i.e.,toreducethenumber

ofpotentiallyconfoundingeffects,andtodecreauncertaintyassociated

withthemeasuredsurrogatebiomarker).

SeeexamplesinTable2

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BiomarkersofSusceptibility

Biomarkersofsusceptibilityarefactorsthatmaymakecertainindividualsmore

kersofsusceptibilityinclude:

geneticfactorsthatmayinfluencehowthebodyinteractswithachemical

otherbiologicalfactorsrelatedtonutritionalstatus,healthstatus,lifestyle,

andlifestagethatmayaffectanindividual’ssusceptibilitytochemical

exposure.

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Table1:ExamplesofBiomarkersofExposure

fromDifferentCategories

Exposure

Biomarker