预防医学英文版课件：Introduction

PREVENTIVEMEDICINE

DepartmentofEnvironmentalHealthSchoolofPublicHealthChinaMedicalUniversityIntroduction(一).HealthandDisease

1.Health

Healthisastateofcompletephysical,mentalandsocialwellbeingandnotmerelytheabsenceofdiseaseorinfirmity.WorldHealthOrganization(WHO)putforwardaproposal:“Healthforallbytheyear2000”.Medicalmodel:biomedical→bio-psycho-socialmedicalmodel

2.DiseaseOppositetohealth,diseaseisin-adaptation,in-coordinationoforganismcausedbyenvironmentalstimulation,disequilibriumoforganismandinternalandexternalenvironment,destructionofhomeostasisandoccurrenceofdamageinsystemic,localororganicfunctionandstructure.3.Preventivemedicine

StudyrangeObjectBasicMedicineLaboratoryExperimentalFindingsClinicalMedicineHospitalIndividualPreventiveMedicineCommunityPopulation1).Definition

Preventivemedicinestudiestheenvironmentalfactorsandtheireffectsonhumanhealth,basedonwhichmancantakemeasurementsinordertoimproveenvironmentalquality,establishenvironmentalstandards,andprotecthumanhealthandpreventthedisease.

2).Objectofstudyenvironmentalfactorhealtheffectimprovementofenvironment

3).Purposeofstudy:

preventthediseaseprotectandpromotehumanhealth4).DepartmentofPreventiveMedicine:

Statistics,HealthToxicology,HealthChemistry,HealthMicroorganism,Epidemiology,EnvironmentalHealth,IndustrialHealthandOccupationalDisease,Nutritionandfoodhealthandsoon.

(二).Threelevelpreventionofthedisease

1.Primaryprevention—etiologicalpreventionPrimarypreventionispreventionofthediseasebyalteringsusceptibilityorreducingexposureforsusceptibleindividuals.

2.Secondaryprevention----preclinicalpreventionSecondarypreventionistheearlydetection,diagnosisandtreatmentofdisease.3.Tertiaryprevention----clinicalpreventionTertiarypreventionisthealleviationofdisabilityresultingfromdiseaseandattemptstorestoreeffectivefunctioning.

补充：全球环境问题温室效应臭氧层耗竭酸沉降环境内分泌干扰物持久性有机污染物生物多样性锐减抗生素滥用人类健康质量下降温室效应（green-houseeffect，globalwarming）温室气体大量排放——全球表面T↑ContributiontoglobalwarmingCarbondioxide55%Methane15%Nitrousoxides6%Chlorofluorocarbons(CFCs)24%危害：极地冰雪融化，海平面上升。全球降雨模式改变。自然疫源性疾病、不明原因疾病增多人类寿命的影响酸沉降（aciddeposition；acidprecipitation）包括酸雨(pH<5.6)、酸雾、酸雪、酸云等。被称为“现代空中死神”。导致土壤酸化，肥力降低；腐蚀建筑物、金属、橡胶等；破坏动物生息地（急剧减少和灭绝的青蛙已达30种）；危害人类健康.臭氧层空洞（耗竭）

stratosphericozonedepletion,

ozone-layerdepletionThestratosphericozonelayershieldstheearthfromultravioletradiation.CFCs（Chloroflurocarbons–e.g.freons）arestable,driftupwardsUVradiationbreaksdownCFCsintochlorineatoms,Chlorineatomsreactwithanddestroyozone.Chlorinewillpersistover100yearsinstratosphereA1%decreaseinozonelayer

increaseUVradiationreachingearthby2%2-10%increaseincellcarcinomas

increasesinskinmelanomas氯氟烃——ClOClO+O3——Cl+O2+O2Cl+O3

——ClO+O2+O2MontrealProtocol1987:29nationsagreedtophaseoutuseofCFCsDevelopedcountriesbannedCFCsuseandproductionin1996DevelopingcountriesmaystilluseandproduceCFCsuntil2010环境内分泌干扰物

environmentalendocrinedisruptors定义（USEPA）：能干扰机体天然激素合成、分泌、转运、结合或清除的各种外源性物质。来源：自然界（如某些植物激素）人工合成（环境污染的主要来源）名称衍变环境雌激素（Environmentalestrogens,EEs）外源性雌激素（Xenoestrogens,XEs）内分泌干扰物（Endocrinedisruptingchemicals，EDCs）内分泌活性化合物（Endocrineactivecompounds,EACs)环境内分泌干扰物（Environmentalendocrinedisruptors,EEDs）机制：模拟(mimicking)。在结构及性质上均类似天然激素；拮抗(antagonizing)。结构上类似但性质上不同，从而作为竞争者，阻滞或拮抗天然激素与受体的结合；改变（altering）激素的代谢。影响体内激素的合成、储存、释放、转运、清除等多个过程；弱化（modifying）受体水平。如调低受体数量，或降低受体与正常激素结合的敏感度等。危害及后果：人类及动物生殖能力下降：精子平均数从1940年1.13亿/ml下降到1990年的0.66亿/ml，不育症患者越来越多。生殖系统肿瘤发病率增加：乳腺癌、前列腺癌等儿童性发育异常.美国USEPA公布的第一批环境内分泌干扰物质（67种（类））Dioxinsandfurans二恶英及其多氯代苯并呋喃类（1）高温焚烧含氯有机物后形成；（2）农药中的杂质或副产品；（3）纸浆的氯化漂白过程中形成 Polychlorinatedbiphenyl(PCBs)多氯联苯热媒、无碳复写纸、电容器变压器绝缘Polybromobiphenyl(PPB)多溴联苯防火材料Hexachlorobenzene(HCB)六氯苯杀菌剂Pentachlorophenol(PCP)五氯苯酚杀菌消毒剂、除草剂、防腐剂2,4,5-Trichlorophenoxyaceticacid2,4,5-三氯苯氧基乙酸（2,4,5-滴）除草剂 2,4-Dichlorophenoxyaceticacid2,4-二氯苯氧基乙酸（2,4-滴）除草剂Amitrole杀草强除草剂、树脂硬化剂Atrazine莠去净除草剂 Alachlor草不氯除草剂Simazine(CAT) 西玛津除草剂HexachlorocyclohenaneEthylParathion六氯环己烷乙基对硫磷杀虫剂Carbaryl 西维因杀虫剂Chlordane 氯丹杀虫剂Oxychlordane氧化氯丹 氯丹的代谢中间产物Trans-Nonachlor 反式-九氯 杀虫剂1,2-dibromo-3-chloropropane1,2-二溴-3-氯丙烷杀虫剂DDT滴滴涕杀虫剂DDEandDDD滴滴伊和滴滴滴 杀虫剂（DDT的代谢中间产物）Kelthane(Dicofol) 三氯杀螨醇 杀虫剂 Aldrin 艾氏剂 杀虫剂 Endrin 异狄氏剂 杀虫剂 Dieldrin 狄氏剂 杀虫剂 Endosulfan(Benzoepin) 硫丹 杀虫剂 Heptachlor 七氯 杀虫剂 Heptachlorepoxide 环氧七氯 七氯的代谢中间产Malathion 马拉硫磷 杀虫剂 Methomyl 灭索威 杀虫剂 Methoxychlor 甲氧滴滴涕 杀虫剂 Mirex 灭蚁灵 杀虫剂持久性有机污染物

(PersistentOrganicPollutants，POPs)定义：符合以下四个特性的环境污染物环境持久性（长期残留）；生物蓄积性（可在食物链中蓄积并放大）；半挥发性（能够在大气环境中长距离迁移），高毒性（在环境浓度下就有毒性）的天然或人工合成的有机污染物。符合上述定义的POPs物质有数千种之多。斯德哥尔摩国际公约提出首批控制12种：艾氏剂、狄氏剂、异狄氏剂、DDT、氯丹、六氯苯、灭蚁灵、毒杀芬、七氯、多氯联苯(PCBs)、二恶英和苯并呋喃(PCDD／Fs)。生物多样性（biodiversity）锐减生物多样性包括三个层次生态系统多样性：如“地球之肺”热带雨林，“地球之肾”天然湿地等。物种多样性：地球上每天有100种生物绝种。种内基因多样性：不同的人种、鸟种、微生物种类等多样性锐减主要为人类活动所致无限制采伐、掠夺性开采、过度捕捞狩猎、严重污染对人类前途构成致命威胁（生态平衡失调）犹如缺了零件的飞机。抗生素滥用（antibioticabuse）1928年弗莱明发明青霉素，1940年用于临床，使人类平均寿命从40岁提高到了65岁。目前许多毁灭性新旧传染疾病正在逐渐出现。如目前全球已有17亿人感染了结核杆菌，约有2000万结核病病人，每年死亡300万人。在抗生素投入使用至今的60年间，很多细菌就对抗生素产生了严重的耐药，有的甚至产生了多重耐药。20世纪50年代在欧美首先发生了耐甲氧西林金黄色葡萄球菌的感染，很快席卷全球，有5000万人被感染,50多万人死亡。细菌产生耐药性的速度远远快于人类新药开发的速度，如不遏止，人类将进入“后抗生素时代”，也即回到抗生素发现之前的人们面对细菌性感染束手无策的黑暗时代。

人类健康及生活质量下降亚健康状态者增加严重危害健康的慢性疾病糖尿病、高血压、心脑血管疾病等发病率增加、高发年龄提前癌症发病率上升、高发年龄提前不育症患者增加新型、不明原因传染病增多：SARS、禽流感等耐药性疾病增多心理疾患增多、自杀率增加青少年发育、行为问题及犯罪率增加更年期提前……EnvironmentFactorsandDisease

Chapter1:MankindandEnvironment

Section1.HumanEnvironment1.Definitionofenvironment

(1)Environment

Theimplicationofenvironmentisthewholethingsofoutsideworldthatismainlycomposedofhumanbeingsociety.Itincludesnaturalenvironmentandsocialenvironment.①NaturalenvironmentNaturalenvironmentreferstototalthingsofmaterialsandenergyformednaturally,whichdirectlyorindirectlyaffectslivingandproductionofhumanbeingsurroundingthespaceofthecrowd.环境自然环境社会环境（大气圈、岩石圈、水圈、生物圈）原生环境primaryenvironment次生环境secondaryenvironmentprimaryenvironment原生环境：天然形成的,未受或少受人为因素影响的环境有利健康因素不利健康因素促进健康地方病“正常”空气,水,土壤,阳光,微小气候,风光secondaryenvironment次生环境：人类活动下形成的环境，环境污染是主要问题

破坏生态平衡:次生环境质量恶化

保持生态平衡:次生环境优于原生环境促进健康引起疾病②SocialenvironmentalSocialenvironmentreferstotheartificialenvironmentcreatedbysociallaborconsciouslyforalongtimeonthebasisofnaturalenvironment.(2).LivingenvironmentLivingenvironmentreferstoavarietyofnaturalandartificialconditions,whichcloselyapproachandrelatetosociallifeofmankind.(3).Ecologicalenvironment

Ecologicalenvironmentreferstogeneralizednaturalenvironment,whichisapartalittlefarfromthesociallifeofmankindandiscomposedofavarietyoftypesandlevelsofecologicalsystem.2.EnvironmentalFactors(1)BiologicalfactorPathogenicmicroorganism

微生物寄生虫支原体原虫环境中能引起传染病和寄生虫病的生物病原因子

(2)ChemicalfactorDuetoartificialornaturalreasonchemicalcompositioninair,water,soilandfoodmayvarygreatly.ForexamplelargeamountoffuelisburnedwhichdischargeSO2intotheair.

人为原因(环境污染)自然原因:洪水、地震、风景、火山爆发燃料燃烧工业废水污染或灌溉农田

(汞;镉;砷)空气

水

土壤

食物化学组成变化(3)

Physicalfactor

Physicfactorrefertoairtemperature,humidity,aircurrent,radiationandairpressure,whichareknownasclimaticconditions.Radioactivesubstance,highfrequencyelectromagneticfield,microwave,laser,noiseandvibrationmayalsocontaminateourenvironmentcausehazardtohumanbeing.

气象因素(微小气候)放射元素——电离辐射

生活、生产环境

阳光电磁辐射

人为原因自然原因：异常气象

物理因素变化(4)Social-psychologicalfactorInhabitinsocialcommunity,economicstatus,politicalstatus,educationalandculturallevel,livingstandard,medicalservice,behaviorandhabitetcarealsohavetheirinfluenceonhumanbeing.Studytheeffectofthesefactorareanewfieldofpreventivemedicine.3.Ecosystemandecologicalequilibrium(1).BiosphereAlllivingthingsinhabitontheearthsurface.Thesurfacelayeroftheearthinthepresenceoflivingthingsiscalledbiosphere.Itrangesfrom12kmdepthoftheearthcrustorocean,toapproximately15kmthicknessofairlayer.Thereareair,sunlight,water,soil,rockinthebiosphere,whichprovidethenecessitiesfororganisms.Biosphereisthecombinationoforganismsandtheirenvironment.

生物圈：生物生存的地球表层。范围：12km深地壳、海洋及15km以内的地表大气层(2).EcosystemEcosystemiscomposedoflivingthingsandtheirenvironment,air,water,andsoil.Livingthingsarecloselylinkedtotheirexternalenvironment.

Structureofecosystem:producer,consumer,decomposerandnon-livingthingsenvironment.

Functionofecosystem:energyflowthroughecosystem,materialcyclesinecosystemandinformationtransferinecosystem.

(3).EcologicalequilibriumThroughenergyandnourishmentcirculation,ecosystemkeepsitsbalance.Itiscalledecologicalequilibrium,inwhicheachlinkkeepsstableinqualityandinquantities,andadaptstoeachother.

(4).EcologicaldisturbanceDuetoman-madecausessometimeenvironmentfactormaychangegreatly,causedisruptionofecologicalequilibrium.Forexamplepesticidewhichisnotintrinsiccomingintoenvironment,killinsects,reducethenumberofbirds,owingtodiminishpollination,plantbloom,blossomandbearnofruit,residuepesticidecomeintoanimalandhumantissueposepotentialhazardtohumanbeing.Section2.Therelationshipof

environmentandhealth1.Theunityofhumanandenvironment2.Theadaptabilityofhumantoenvironment3.Theinteractionofhumanandenvironment1.Theunityofhumanandenvironment

Aswementionedearlier,livingthingsarecloselyrelatedtoitsexternalenvironment.Throughtakingfood,waterfromenvironmenthumanobtainsenergyandthematerialtobuiltitsbodytissue.Accordingtoanalysiselementarycontentofhumanbodyandrockofearthcrust,theelementalabundancearequitesimilarbetweenhumananditsenvironment.Thoseelementswhicharerichinexternalenvironment,arefoundplentyinhumanbody,onthecontraryitisalsotrue,rareelementarescarceinhumanbody.Theabovefactindicatesthecloserelationbetweenhumananditsenvironment.人体血液中和地壳中元素含量的相关性2.Theadaptabilityofhumantoenvironment

3.TheinteractionofhumanandenvironmentSection3Environmentalpollution

andHealtheffects

一.Outlineofenvironmentalpollution

1.Definitionofenvironmentalpollution:Owingtomen-madeornaturalcause,thealterationinenvironmentalconstituentandcondition,resultsindisturbanceanddisruptionofecologicalequilibriumandnormalenvironmentforhumanlivingandproducing,leadsdirect,indirectorpotentialdamagetohumanhealthisdefinedasenvironmentalpollution.

2.Typesofenvironmentalpollution①.ChemicalcontaminationPoisonousgas:SO2,NO2,Cl2,COHeavymetal:Hg,Cd,Pb,Cr,NiOrganiccompounds:organophosphoruspesticide,organochlorinepesticidehigh-molecularcompounds②.Physicalcontaminationnoise,microwaveradiationandradioactivesubstancescontamination③.BiologicalcontaminationPathogenicmicroorganismParasiticovum

3.SourceofenvironmentalpollutionItmaybeclassifiedasproductive,domesticandmiscellaneous.Sourceofenvironmentalpollutionisasfollows.(1).ProductivepollutionWastegas,wastewater,wasteresidue(threewaste)fromindustrialprocess,withoutpropertreatmentpourintoexternalenvironmentmaycausecontaminationofair,water,soilandfood.(2).Domesticsourcepollution(3).MiscellaneoussourceApartfromproductiveanddomesticsourcethereareothersourcesuchastransportation:train,ship,airplane,automobile.TheyburncoalorgasolineandemitSO2,hydrocarbonandincompletecombustionproduct.Soilwithoutcoveredwithlawnortree,soilparticlesmaybeblownintotheair.Insomedistrict,soilparticleaccountfor50%ofairdust.

废水

生产性污染

废气

工业性“三废”

废渣

污水

生活性污染

粪尿

生活性“三废”

垃圾其它污染：噪声等环境内分泌干扰物（EEDs）持久性有机污染物（POPs）

(一)生产性污染（Productivepollutant）

1.能源大规模使用；

2.资源大规模的开发；

3.新物质的大规模合成：现有960万种新的化学物质，人工合成200万种，增加1000种/

年。三大合成（塑料、纤维、橡胶）。特点：有组织排放、量大、毒性强、易治理工厂大量废气的排放工厂废水未经处理大量排放排污口长江水污染资源大规模的开发(二)生活性污染（Domesticpollutant）污水：医院污水、生活污水垃圾：成分复杂，含致突变致癌物粪尿：主要是生物性污染

煤烟：产生大量有害气体和灰尘。1999年九届人大11

次会议提案：在大城市禁止烧煤。特点：片污染、无组织排放、难治理生活性三废随意乱倒的生活垃圾堆积如山(三)其他污染（Otherpollutant

）交通污染噪声污染光污染放射性污染农药化肥交通性污染4.Spreadandtransportationofchemicalpollutantintheenvironment(1).Migrationofchemicalpollutants①Bio-concentration

Inbiosphere,thetransferofenvironmentalpollutantismorecomplex,onenteringlivingthings,somepollutantsmaycombinetightlywithprotein,andsulfhydrylgroupsthenexcrete,oreliminateless.Asaresulttheygraduallyaccumulateandconcentrateinbodytissue.Thephenomenonthattheconcentrationofpollutantinbiologicalbodysurpassestheconcentrationinenvironmentiscalledbio-concentration.Theratioofchemicalconcentrationinbiologicalsubstanceversustheconcentrationinenvironmentcalledcoefficientofbio-concentration.②Bio-magnificationApartfromaccumulationinonebiologicalspecies,theprocessmayfurtheramplifythroughfoodchainandeventuallyreachessuchahighlevelastocauseintoxicationinhigheranimalsandthisprocessiscalledbio-magnification.环境污染物发生生物放大的条件:①环境化学物质易为各种生物体吸收②进入生物体的环境化学物质较难分解和排泄③污染物在生物体内富集和逐渐积累时，尚不会对该生物造成致命性的损害④在生物放大过程中是通过食物链进行Fortunatelyfoodchainaccumulationisnotnecessaryprocessformostpollutant.Onthecontrary,throughspreadandtransportationgenerallytheconcentrationsofthepollutantgraduallydeclineordisappearaswellasdetoxify.Thecommonorganicsuchashydrocarbonproteinsthroughbiochemicaloxidationmicroorganismsplayamajorrule,decomposetonitrite,carbonate,sulfate.Thesearestablesimpleinorganic,whichnolongerputrid,andsafe.(2)TransformationofchemicalpollutantsItsphysic-chemicalpropertyandenvironmentalconditiondeterminethebehaviorofpollutantafterdischargingintotheenvironment.Ininorganicsphere,usuallythroughdilution,dissolutionandsedimentationtheconcentrationofpollutantgraduallydeclined.Apartfromthephysicalprocess,oxidation,reduction,hydrationalsooccurs,throughwhichpollutantsdegradedecomposethendetoxify.Duringdegradationmicroorganismsplayamajorrule.

①PrimarypollutantThechemicalpollutants,whichcomefrompollutionsourcedirectlyanddon’tchangetheirphysic-chemicalpropertiesinenvironment,arecalledprimarypollutants.②SecondarypollutantThenewcompounds,whichareformedfromoriginalpollutantsafterdischargefrompollutionsourcebyphysical,chemicalorbiologicalreaction,arecalledsecondarypollutant.

(3)Environmentalself-purificationTheprocessofself-purification(biodegradation)includesasfollows.PhysicalactionChemicalactionBiologicalaction自净方式

物理净化：稀释、混合、扩散、沉降、挥发、逸散、凝聚化学净化：氧化、还原、水解及中和、光解生物净化：吸收、分解或降解、转化、氧化、拮抗等影响因素环境物理条件(温度、流量、流速、风速)污染物的物理特性(比重、形态、粒度)影响因素环境化学条件(pH值、化学组分、氧化还原电势)污染物的化学性质环境污染物的吸收、分布与排泄(一)环境污染物的吸收

肺泡总表观面积大，壁薄，毛细血管丰富：吸收迅速不经肝，直接进入大循环肺泡/血液浓度(分压)差大，吸收快血/气分配系数大，易吸收入血颗粒大小、分散度、溶解度活动强度、肺通气量环境气象因素1.呼吸道：气体、蒸气、气溶胶特点影响因素2.消化道吸收：水与食物中的有害物质消化道吸收：水与食物中的有害物质特点主要经小肠吸收绒毛增加吸收面积600倍扩散方式为主，也可经载体可在肠肝循环过程中反复被吸收影响因素pH值胃肠道内容物多少、排空时间、蠕动状况3.皮肤吸收：水溶性同时具脂溶性环境毒物特点主要经表皮，少量经毛囊、汗腺、皮脂腺透过三层屏障

——表皮角质层：阻止分子量>300的物质

——连接角质层：阻止水、电解质、水溶性物质通过脂溶性物质

——基膜(表皮与真皮间)：阻止少数物质不进入肝脏，直接进入大循环影响因素脂/水分配系数易溶于脂、难溶于水、易挥发：吸收少，如苯易溶于脂、水、不易挥发：吸收多，如有机磷皮肤完整性(二)环境污染物在体内的分布与贮存

1.分布：环境污染物通过吸收后，随血液和淋巴液分散到全身各组织的过程非均匀分布器官或组织血流量大，灌注速率高，如肝脏化学物与器官亲和力：90%铅盐沉积在骨骼屏障作用(血脑、胎盘、血眼、血睾)：甲基汞易通过血脑和胎盘屏障2.贮存(storage)靶器官：多数情况下污染物贮存的部位就是毒物直接作用部位，称为靶部位（靶组织或靶器官）贮存库：化学物含量高，但不显示明显毒作用的部位

—血浆蛋白(白蛋白为主)是暂时贮存库

—肝、肾、脂肪组织是多数污染物的贮存库硫蛋白(metallothionein)蓄积

物质蓄积：进入机体的污染物或其代谢产物，不能完全排出而逐渐蓄积于体内

功能蓄积：毒物进入体内后，用现代检测技术不能发现其在体内有明显贮留，但由该物质引起的功能改变却逐渐累积，导致机体对该毒物的反应性增强(三)环境污染物在体内的转化

生物转化：进入机体的环境化学物，在体液或组织内参与机体固有的复杂生化过程，使其本身的化学结构发生一系列变化。污染物第一阶段反应(降解反应):氧化、还原、水解第二阶段反应(II相反应)：结合反应生物解毒作用(detoxication)经过体内的转化，环境污染物毒性降低，如大多数毒物。生物活化作用(bioactivation)经过生物转化，环境污染物毒物增加，如对硫磷，乐果；苯并(a)芘、芳香胺(四)环境污染物的排泄1.经肾随尿排出：主要途径污染物或其代谢物肾小球被动过滤肾小管解离.水溶性未解离.脂溶性被动扩散尿重吸收入血不易排除2.经肝、胆通过肠道随粪便排出肝脏生物转化代谢物肝细胞胆汁肠道随粪排出肠肝循环3.经呼吸道排出

气态或挥发性物质(CO、SO2、HS、C4H6)可经肺呼出以下因素可加速排出——血中溶解度低——肺泡分压小：移至空气新鲜环境——肺通气量大4.其他排除途径

毛发、唾液、乳汁、月经生物监测指标(生物标记物)：血液、尿液、呼出气、毛发及脂肪组织等生物样品中某些化学物或其代谢产物的含量，可作为评价体内该化学物量的生物检测指标，即生物标记物5.Publicnuisance

Itreferstoharmfulsituation,whichpollutedanddestroyedenvironment,endangeredthepublichealth,safety,andlifeaswellascommonorprivateproperty.6.Publicnuisanceevent

Itreferstotheincidentthatresultedinobviouslyincreaseofdiseaseanddeathinashortperiodofthetimebysevereenvironmentalpollution.Inthehistory,thepublicnuisanceexperiencedthreeperiods:

①theemergingperiodofpublicnuisance(Theendof19centurytothebeginningof20century)②thedevelopingperiodofpublicnuisance(Twentiestofortiesof20century)③theoverflowingperiodofpublicnuisance(FiftiestoSeventiesof20century)7.Publicnuisancedisease

Thepatientswerelocatedinsomeregionwheresevereenvironmentpollutionhadhappenedinsomeperiodofthetime.Thiskindofthediseasewascalledthepublicnuisancedisease.8.Toxicityindexofenvironmentalpollutants1).ToxicityOnecoulddefineapoisonasanyagentcapableofproducingadeleteriousresponseinabiologicalsystem,seriouslyinjuringfunctionorproducingdeath.Thisisnot,however,ausefulworkingdefinitionfortheverysimplereasonthatvirtuallyeveryknownchemicalhasthepotentialtoproduceinjuryordeathifitispresentinasufficientamount.

Paracelsus(1493-1541),phrasedthiswellwhenhenoted“Whatistherethatisnotpoison?Allthingsarepoisonandnothingiswithoutpoison.Solelythedoesdeterminesthatathingisnotapoison”.Toxicityisameasuretothedegreetowhichsomethingistoxicorpoisonous.2).Lethaldose

(1).Absolutelethaldose(LD100)Absolutelethaldoseisthelowestdoseorconcentrationofachemicalthatcanbeexpectedtocausedeathinalloftheanimalstested.(2).Medianlethaldose(LD50)Medianlethaldoseisthestatisticallyderivedsingledoseofasubstancethatcanbeexpectedtocausedeathin50percentoftheanimalstested.TheLD50valueisthestandardforcomparisonofacutetoxicitybetweentoxicantsandbetweenspecies.Determinationofthemedianlethaldoseisusuallythefirstexperimentperformedwithanewchemical.(3).Minimallethaldose(MLD/LD01)Minimallethaldoseisthelowestdoseofachemicalthathadeverbeenobservedtoresultindeath.(4).Maximaltolerancedose(MTD/LD0)Maximaltolerancedoseisthehighestdoseofachemicalthatcannotcausedeathintheanimalstested.3).Maximalno-effectdose(ED0)

Maximalno-effectdoseishighestdoseofachemicalthatcannotproduceanyadverseeffectsuchasmortality,clinicalsignsoftoxicity,orpathologiclesionsthatwouldbepredictedtoshortentheanimals’naturallifespan.4).Minimaleffectdose(MEL/ED01)

Minimaleffectdoseisthedosebelowwhichnoresponseoccurs.Itevokesastatedall-or-noneresponse.Wecanalsocallit“thresholddose”Fortheinter-individualvariabilityinresponseandqualitativechangesinresponsepatternwithdosemakeitdifficulttoestablishatrueED0/ED01foranychemical.Sointhetoxicexperimentweuseno-observedadverseeffectlevel(NOAEL)/lowestobservedadverseeffectlevel(LOAEL)instead.二.Healtheffectofenvironmentalpollution

（一）Theeffectofenvironmentalpollutiononhealthinfluenceofpopulation1.Dose-effectrelationshipanddose-responserelationship①Dose-effectrelationship

Doseeffectrelationshipistherelation-shipofdifferentdoseandeffectsindiffer-entintensity,rangingfromundetectable,pre-clinicaltoclinicaloreventodeath.Asweknow,theeffectofanychemicalsorphysicalagentisdose-related.

ThecurveofdoseeffectrelationgenerallyappearsasStypefortoxicagentorastraightlineforcarcinogens.Foressentialtraceelementthesituationismorecomplicated.Atverylowdosephysiologicalrequirementcannotbesatisfiedwith,diseasemayoccur,athighdoselevel,intoxicationappears.Onlyatproperdosepeoplecankeephealthy.Forexample,insufficientoffluorine,dentalcariesoccurs;however,excessiveamountoffluorinemaycausefluorosis.②Dose-responserelationshipItistherelationbetweendifferentdosageandincidenceofdamage,intoxication,orotherclinicalsymptom.2.Populationhealtheffectspectrumandhigh-riskgroupThehealthspectrumusuallyisexpressedbyafigure1-1.Itlookslikeapyramid.Thetopofpyramidexpressthestrongesteffect,buttherateislowest,thebottomexpressestheslightesteffect(pre-clinicalphase),peopletherearethemajority.Inthepollutedareatheconcentrationoftoxicagentatdifferentsitearedifferent,personsexposedtodifferentleveloftheagent,ontheotherhandthesensitivityofindividualsarealsodifferent,consequentlytheresponseamongindividualsarevarious.Scientistvividlydescribesthehealtheffectspectrumasanicebergfloatingontheocean.Fromremoteonlythetopoficebergcanbeseenbutthemajorpartareundertheocean,ifthispartistobeneglectedandtakenomeasureofprevention,theshipofhumanhealthwillinevitablyrunoniceberg.（二）Characteristicsofhealtheffectsofenvironmentalpollutants

1)Extensiveinfluencetopopulation2)Long-termeffectoflowdoseaction3)Complexityofmultiplefactors4)Multipletypesofaction(三).Healthhazardofenvironmentalpollution

1.Specificinjury(1).AcuteeffectAcuteintoxicationmayoccuraftersingleorshortperiodexposuretohighdoseofenvironmentalpollutant.Inthiscasegenerallyappearasdisaster,suchasLondonsmog,orLosAngelesepisode,thelaterisconsequenceofphotochemicalsmog.

(2).ChroniceffectChronicintoxication:Chronicintoxicationismorecommon,suchasMinamatadiseaseandIti-itidisease,duetomethylHgorCdintoxication.(3).Remoteeffects

①.CarcinogenesisThemechanismofcarcinogenesisisnotperfectlyidentified.Itisknownthatmutationofoncogenortumorsuppressorgenemayinitiatecarcinogenesis.OncogenandtumorsuppressorgenesarethegenesthatregulatereproductionofDNA.TheactivationoftheoncogenorinactivationofthetumorsuppressorgenethroughmutationwouldcauseexcessiveduplicationofDNA.Theuncontrolledgrowthofcellwouldresultintheformationoftumor.Carcinogensareclassifiedasphysicalfactor,suchasradioactivesubstance,UVR,chemicalfactor,suchasbenzo(a)pyrene,

-naphylamine,arsenic,aflatoxin-B,asbestosandbiologicalfactorsuchasnasolaryngealcancer,whichcanbeinducedbyvirus.

化学致癌物的分类

按对人的危险性分 按活化的需要分按是否具有诱变性分按化学结构分根据致癌物对人类和动物的致癌作用分类国际癌症研究机构（IARC2002年）根据证据的强度将化学物质分为四组（878种）：1类：确证的人类致癌物，是指在流行病学及动物致癌试验均有充分证据的致癌物有87种。2类：对人很可能或可能致癌物，分为组2A和组2B两组。2A类：对人类很可能致癌，指有充分动物试验结果证明，但对人类证据有限，有63种。2B类：对人类可能致癌，指对人类致癌性证据有限，对动物致癌性证据并不充分，有243种。3类：现有的证据不能对人类致癌性进行分类，即动物试验及流行病学调查有一定结果，但均未能确证其有致癌性的物质，有493种。4类：对人类可能是非致癌物，即按目前的试验结果，未见有致癌性的物质，有1种。按活化的需要分类直接致癌物（directcarcinogens)各种烷化剂，大多为亲电子反应物间接致癌物（indirectcarcinogens)多环芳烃、芳香胺类化合物按是否具有诱变性分类诱变性致癌物——遗传毒性致癌物(genotoxiccarcinogen)。非诱变性致癌物——非遗传毒性致癌物(nogenotoxiccrcinogen)，或称DNA活性外或基因外致癌物（epigeneticcarcinogen)。②.MutagenesisMutagenesisgenerallyistheappearanceofevolution,resultsintheadaptationofchangingenvironmentbutmutationinducedbyenvironmentalpollutantisharmfultohumanhealth.Mutationofbodilycellwillresultincarcinogenesis,andmutationinreproductivecellwillresultinteratogenesis.Mutationiscloselyrelatedtocarcinogenesis,mostmutagensarealsocarcinogens.

③.

TeratogenesisSomeagentthroughmaternalplacentaduringpregnancymaydisturbthedevelopmentofembryoandcausesterility,abortion,stillbornandmalformation.Thedelayeddevelopmentofwitiscalledteratogen.Thiseffectisnothereditary,suchasthalidomide,urticariavirus.Somemutageninducedmutationofreproductivecellresultsinmalformation,whichisheritable.5.生育毒性和发育毒性

反应停事件(4).

Effectonimmunefunction①Sensitization:Someenvironmentalpollutantactasallergen,isabletocauseallergicdiseasesuchaspollencausehayfever.②Immunosuppression:Someenvironmentalpollutantcancauseimmunesuppression,disturboneorafewstepsofimmuneprocesssuchasalkylatingagent,anti-metabolicdrug,ionization,UVR,somepesticide.2.Non-specificinjuryApartfromspecificeffect,environmentalpollutantmaycausenon-specificinjury,suchasincreaseprevalenceofcommondiseases,frequentlyoccurringdiseases,respiratoryinfection,commoncoldandraisebloodpressure.Themechanismofthisisnotf