預(yù)防醫(yī)學(xué)課件：Introduction

1、PREVENTIVE MEDICINE Introduction( (一一). ). Health and Disease Health and Disease1. Health Health is a state of complete physical, mental and social well being and not merely the absence of disease or infirmity. World Health Organization (WHO) put forward a proposal: “Health for all by the year 2000”

2、. Medical model: biomedicalbio-psycho-social medical model 2. Disease Opposite to health, disease is in-adaptation, in-coordination of organism caused by environmental stimulation, disequilibrium of organism and internal and external environment, destruction of homeostasis and occurrence of damage i

3、n systemic, local or organic function and structure.3. Preventive medicineStudy rangeObjectBasic MedicineLaboratoryExperimental FindingsClinical MedicineHospitalIndividualPreventive MedicineCommunityPopulation1). Definition Preventive medicine studies the environmental factors and their effects on h

4、uman health, based on which man can take measurements in order to improve environmental quality, establish environmental standards, and protect human health and prevent the disease. 2). Object of study environmental factor health effect improvement of environment 3). Purpose of study: prevent the di

5、seaseprotect and promote human health4). Department of Preventive Medicine: Statistics, Health Toxicology, Health Chemistry, Health Microorganism, Epidemiology, Environmental Health, Industrial Health and Occupational Disease, Nutrition and food health and so on. ( (二二). ). Three level prevention of

6、 the Three level prevention of the diseasedisease1. Primary preventionetiological prevention Primary prevention is prevention of the disease by altering susceptibility or reducing exposure for susceptible individuals. 2. Secondary prevention-preclinical prevention Secondary prevention is the early d

7、etection, diagnosis and treatment of disease.3. Tertiary prevention-clinical prevention Tertiary prevention is the alleviation of disability resulting from disease and attempts to restore effective functioning. 補(bǔ)充：全球環(huán)境問題M溫室效應(yīng)溫室效應(yīng)M臭氧層耗竭臭氧層耗竭M(jìn)酸沉降酸沉降M環(huán)境內(nèi)分泌干擾物環(huán)境內(nèi)分泌干擾物M持久性有機(jī)污染物持久性有機(jī)污染物M生物多樣性銳減生物多樣性銳減M抗生素

8、濫用抗生素濫用M人類健康質(zhì)量下降人類健康質(zhì)量下降溫室效應(yīng)（green-house effect， global warming ）溫室氣體大量排放溫室氣體大量排放全球表面全球表面TContribution to global warming 1.Carbon dioxide 55%2.Methane 15 %3.Nitrous oxides 6%4.Chlorofluorocarbons (CFCs) 24%危害：危害：1.極地冰雪融化，海平面上升。極地冰雪融化，海平面上升。2.全球降雨模式改變。全球降雨模式改變。3.自然疫源性疾病、不明原因疾病增多自然疫源性疾病、不明原因疾病增多4.人類壽命

9、的影響人類壽命的影響酸沉降（ acid deposition；acid precipitation ）包括酸雨包括酸雨(pH300的物質(zhì)的物質(zhì) 連接角質(zhì)層：阻止水、電解質(zhì)、水溶性物質(zhì)連接角質(zhì)層：阻止水、電解質(zhì)、水溶性物質(zhì) 通過脂溶性物質(zhì)通過脂溶性物質(zhì) 基膜基膜(表皮與真皮間表皮與真皮間)：阻止少數(shù)物質(zhì)：阻止少數(shù)物質(zhì)不進(jìn)入肝臟，直接進(jìn)入大循環(huán)不進(jìn)入肝臟，直接進(jìn)入大循環(huán)影響因素影響因素脂脂/水分配系數(shù)水分配系數(shù) 易溶于脂、難溶于水、易揮發(fā)：吸收少，如苯易溶于脂、難溶于水、易揮發(fā)：吸收少，如苯 易溶于脂、水、不易揮發(fā)：吸收多，如有機(jī)磷易溶于脂、水、不易揮發(fā)：吸收多，如有機(jī)磷皮膚完整性皮膚完整性( (

10、二二) )環(huán)境污染物在體內(nèi)的分布與貯存環(huán)境污染物在體內(nèi)的分布與貯存1. 分布：分布：環(huán)境污染物通過吸收后，隨血液和淋巴液分散到環(huán)境污染物通過吸收后，隨血液和淋巴液分散到全身各組織的過程全身各組織的過程 非均勻分布非均勻分布 器官或組織血流量大，灌注速率高，如肝臟器官或組織血流量大，灌注速率高，如肝臟 化學(xué)物與器官親和力：化學(xué)物與器官親和力：90%鉛鹽沉積在骨骼鉛鹽沉積在骨骼 屏障作用屏障作用(血腦、胎盤、血眼、血睪血腦、胎盤、血眼、血睪)： 甲基汞易通過血腦和胎盤屏障甲基汞易通過血腦和胎盤屏障2. 2. 貯存貯存(storage)(storage)靶器官：多數(shù)情況下污染物貯存的部位就是毒物直接

11、作用靶器官：多數(shù)情況下污染物貯存的部位就是毒物直接作用部位，稱為靶部位（靶組織或靶器官）部位，稱為靶部位（靶組織或靶器官）貯存庫：化學(xué)物含量高，但不顯示明顯毒作用的部位貯存庫：化學(xué)物含量高，但不顯示明顯毒作用的部位 血漿蛋白血漿蛋白( (白蛋白為主白蛋白為主) )是暫時貯存庫是暫時貯存庫 肝、腎、脂肪組織是多數(shù)污染物的貯存庫肝、腎、脂肪組織是多數(shù)污染物的貯存庫 硫蛋白硫蛋白( (metallothioneinmetallothionein) )蓄積蓄積 物質(zhì)蓄積：物質(zhì)蓄積：進(jìn)入機(jī)體的污染物或其代謝產(chǎn)物，不能完全進(jìn)入機(jī)體的污染物或其代謝產(chǎn)物，不能完全排出而逐漸蓄積于體內(nèi)排出而逐漸蓄積于體內(nèi) 功能

12、蓄積：功能蓄積：毒物進(jìn)入體內(nèi)后，用現(xiàn)代檢測技術(shù)不能發(fā)現(xiàn)毒物進(jìn)入體內(nèi)后，用現(xiàn)代檢測技術(shù)不能發(fā)現(xiàn)其在體內(nèi)有明顯貯留，但由該物質(zhì)引起的功能改變卻逐漸其在體內(nèi)有明顯貯留，但由該物質(zhì)引起的功能改變卻逐漸累積，導(dǎo)致機(jī)體對該毒物的反應(yīng)性增強(qiáng)累積，導(dǎo)致機(jī)體對該毒物的反應(yīng)性增強(qiáng)( (三三) )環(huán)境污染物在體內(nèi)的轉(zhuǎn)化環(huán)境污染物在體內(nèi)的轉(zhuǎn)化生物轉(zhuǎn)化：生物轉(zhuǎn)化：進(jìn)入機(jī)體的環(huán)境化學(xué)物，在體進(jìn)入機(jī)體的環(huán)境化學(xué)物，在體液或組織內(nèi)參與機(jī)體固有的復(fù)雜生化過程，液或組織內(nèi)參與機(jī)體固有的復(fù)雜生化過程，使其本身的化學(xué)結(jié)構(gòu)發(fā)生一系列變化。使其本身的化學(xué)結(jié)構(gòu)發(fā)生一系列變化。污染物污染物 第一階段反應(yīng)第一階段反應(yīng)( (降解反應(yīng)降解反應(yīng)):

13、 ): 氧化、還原、水解氧化、還原、水解第二階段反應(yīng)第二階段反應(yīng)(II(II相反應(yīng)相反應(yīng)) )：結(jié)合反應(yīng)：結(jié)合反應(yīng)生物解毒作用生物解毒作用 (detoxication)經(jīng)過體內(nèi)的轉(zhuǎn)化，環(huán)境污染物毒性降低，如大多數(shù)毒物。經(jīng)過體內(nèi)的轉(zhuǎn)化，環(huán)境污染物毒性降低，如大多數(shù)毒物。生物活化作用生物活化作用 (bioactivation)經(jīng)過生物轉(zhuǎn)化，經(jīng)過生物轉(zhuǎn)化，環(huán)境污染物環(huán)境污染物毒物增加，毒物增加， 如對硫磷，樂果；如對硫磷，樂果；苯并苯并(a)(a)芘、芳香胺芘、芳香胺( (四四) )環(huán)境污染物的排泄環(huán)境污染物的排泄1.1.經(jīng)腎隨尿排出：主要途徑經(jīng)腎隨尿排出：主要途徑污染物或其代謝物污染物或其代謝物腎

14、小球腎小球被動過濾被動過濾腎小管腎小管解離解離. .水溶性水溶性未解離未解離. .脂溶性脂溶性被動被動擴(kuò)散擴(kuò)散尿尿重吸收入血重吸收入血不易排除不易排除2.2.經(jīng)肝、膽通過腸道隨糞便排出經(jīng)肝、膽通過腸道隨糞便排出肝臟生物轉(zhuǎn)化肝臟生物轉(zhuǎn)化代謝物代謝物肝細(xì)胞肝細(xì)胞膽膽 汁汁腸腸 道道隨糞排出隨糞排出腸肝循環(huán)腸肝循環(huán)3.經(jīng)呼吸道排出經(jīng)呼吸道排出氣態(tài)或揮發(fā)性物質(zhì)氣態(tài)或揮發(fā)性物質(zhì)(CO、SO2、HS、C4H6)可經(jīng)肺呼出可經(jīng)肺呼出以下因素可加速排出以下因素可加速排出血中溶解度低血中溶解度低肺泡分壓?。阂浦量諝庑迈r環(huán)境肺泡分壓?。阂浦量諝庑迈r環(huán)境肺通氣量大肺通氣量大4.4.其他排除途徑其他排除途徑毛發(fā)、唾液

15、、乳汁、月經(jīng)毛發(fā)、唾液、乳汁、月經(jīng)生物監(jiān)測指標(biāo)生物監(jiān)測指標(biāo)( (生物標(biāo)記物生物標(biāo)記物) )： 血液、尿液、呼出氣、毛發(fā)及脂肪組織等生物樣品血液、尿液、呼出氣、毛發(fā)及脂肪組織等生物樣品中某些化學(xué)物或其代謝產(chǎn)物的含量，可作為評價體內(nèi)該化中某些化學(xué)物或其代謝產(chǎn)物的含量，可作為評價體內(nèi)該化學(xué)物量的生物檢測指標(biāo)，即生物標(biāo)記物學(xué)物量的生物檢測指標(biāo)，即生物標(biāo)記物5. Public nuisance It refers to harmful situation, which polluted and destroyed environment, endangered the public health, sa

16、fety, and life as well as common or private property.6. Public nuisance event It refers to the incident that resulted in obviously increase of disease and death in a short period of the time by severe environmental pollution.In the history, the public nuisance experienced three periods: the emerging

17、 period of public nuisance (The end of 19 century to the beginning of 20 century) the developing period of public nuisance (Twenties to forties of 20 century) the overflowing period of public nuisance (Fifties to Seventies of 20 century)7. Public nuisance disease The patients were located in some re

18、gion where severe environment pollution had happened in some period of the time. This kind of the disease was called the public nuisance disease.8. Toxicity index of environmental pollutants1). Toxicity One could define a poison as any agent capable of producing a deleterious response in a biologica

19、l system, seriously injuring function or producing death. This is not, however, a useful working definition for the very simple reason that virtually every known chemical has the potential to produce injury or death if it is present in a sufficient amount. Paracelsus (1493-1541), phrased this well w

20、hen he noted “What is there that is not poison? All things are poison and nothing is without poison. Solely the does determines that a thing is not a poison”. Toxicity is a measure to the degree to which something is toxic or poisonous.2). Lethal dose (1). Absolute lethal dose (LD100) Absolute letha

21、l dose is the lowest dose or concentration of a chemical that can be expected to cause death in all of the animals tested. (2). Median lethal dose (LD50) Median lethal dose is the statistically derived single dose of a substance that can be expected to cause death in 50 percent of the animals tested

22、. The LD50 value is the standard for comparison of acute toxicity between toxicants and between species. Determination of the median lethal dose is usually the first experiment performed with a new chemical.(3). Minimal lethal dose (MLD/LD01) Minimal lethal dose is the lowest dose of a chemical that

23、 had ever been observed to result in death.(4). Maximal tolerance dose (MTD/LD0) Maximal tolerance dose is the highest dose of a chemical that can not cause death in the animals tested.3). Maximal no-effect dose (ED0) Maximal no-effect dose is highest dose of a chemical that can not produce any adve

24、rse effect such as mortality, clinical signs of toxicity, or pathologic lesions that would be predicted to shorten the animals natural life span.4). Minimal effect dose (MEL/ED01) Minimal effect dose is the dose below which no response occurs. It evokes a stated all-or-none response. We can also cal

25、l it “threshold dose” For the inter-individual variability in response and qualitative changes in response pattern with dose make it difficult to establish a true ED0/ED01 for any chemical. So in the toxic experiment we use no-observed adverse effect level (NOAEL)/lowest observed adverse effect leve

26、l (LOAEL) instead.二二. Health effect of environmental . Health effect of environmental pollutionpollution（一）（一）The effect of environmental pollution on health influence of population1. Dose - effect relationship and dose - response relationship Dose - effect relationship Dose effect relationship is t

27、he relation-ship of different dose and effects in differ-ent intensity, ranging from undetectable, pre-clinical to clinical or even to death. As we know, the effect of any chemicals or physical agent is dose-related. The curve of dose effect relation generally appears as S type for toxic agent or a

28、straight line for carcinogens. For essential trace element the situation is more complicated. At very low dose physiological requirement can not be satisfied with, disease may occur, at high dose level, intoxication appears. Only at proper dose people can keep healthy. For example, insufficient of f

29、luorine, dental caries occurs; however, excessive amount of fluorine may cause fluorosis. Dose - response relationship It is the relation between different dosage and incidence of damage, intoxication, or other clinical symptom.2. Population health effect spectrum and high-risk groupThe health spect

30、rum usually is expressed by a figure 1-1. It looks like a pyramid. The top of pyramid express the strongest effect, but the rate is lowest, the bottom expresses the slightest effect (pre-clinical phase), people there are the majority.In the polluted area the concentration of toxic agent at different

31、 site are different, persons exposed to different level of the agent, on the other hand the sensitivity of individuals are also different, consequently the response among individuals are various. Scientist vividly describes the health effect spectrum as an iceberg floating on the ocean. From remote

32、only the top of iceberg can be seen but the major part are under the ocean, if this part is to be neglected and take no measure of prevention, the ship of human health will inevitably run on iceberg.（二）（二）Characteristics of health Characteristics of health effects of environmental pollutantseffects

33、of environmental pollutants1) Extensive influence to population2) Long-term effect of low dose action3) Complexity of multiple factors4) Multiple types of action( (三三). ). Health hazard of Health hazard of environmental pollutionenvironmental pollution1. Specific injury (1). Acute effect Acute intox

34、ication may occur after single or short period exposure to high dose of environmental pollutant. In this case generally appear as disaster, such as London smog, or Los Angeles episode, the later is consequence of photochemical smog. (2). Chronic effect Chronic intoxication: Chronic intoxication is m

35、ore common, such as Minamata disease and Iti-iti disease, due to methyl Hg or Cd intoxication.(3). Remote effects . Carcinogenesis The mechanism of carcinogenesis is not perfectly identified. It is known that mutation of oncogen or tumor suppressor gene may initiate carcinogenesis. Oncogen and tumor

36、 suppressor genes are the genes that regulate reproduction of DNA. The activation of the oncogen or inactivation of the tumor suppressor gene through mutation would cause excessive duplication of DNA. The uncontrolled growth of cell would result in the formation of tumor. Carcinogens are classified

37、as physical factor, such as radioactive substance, UVR, chemical factor, such as benzo (a) pyrene, -naphylamine, arsenic, aflatoxin-B, asbestos and biological factor such as nasolaryngeal cancer, which can be induced by virus. 化學(xué)致癌物的分類按對人的危險性分按對人的危險性分按活化的需要分按活化的需要分按是否具有誘變性分按是否具有誘變性分按化學(xué)結(jié)構(gòu)分按化學(xué)結(jié)構(gòu)分根據(jù)致癌物

38、對人類和動物的致癌作用分類根據(jù)致癌物對人類和動物的致癌作用分類 國際癌癥研究機(jī)構(gòu)國際癌癥研究機(jī)構(gòu)（IARC2002年）年）根據(jù)證據(jù)的強(qiáng)度將根據(jù)證據(jù)的強(qiáng)度將化學(xué)物質(zhì)分為四組化學(xué)物質(zhì)分為四組（878種）種）：1類類：確證的人類致癌物，是指在流行病學(xué)及動物致癌試驗均有充分：確證的人類致癌物，是指在流行病學(xué)及動物致癌試驗均有充分證據(jù)的致癌物有證據(jù)的致癌物有87種。種。2類類：對人很可能或可能致癌物，分為組：對人很可能或可能致癌物，分為組2A和組和組2B兩組。兩組。2A類類：對人類很可能致癌，指有充分動物試驗結(jié)果證明，但對人：對人類很可能致癌，指有充分動物試驗結(jié)果證明，但對人類證據(jù)有限，有類證據(jù)有限，有

39、63種。種。2B類類：對人類可能致癌，指對人類致癌性證據(jù)有限，對動物致癌：對人類可能致癌，指對人類致癌性證據(jù)有限，對動物致癌性證據(jù)并不充分，有性證據(jù)并不充分，有243種。種。3類類：現(xiàn)有的證據(jù)不能對人類致癌性進(jìn)行分類，即動物試驗及流行?。含F(xiàn)有的證據(jù)不能對人類致癌性進(jìn)行分類，即動物試驗及流行病學(xué)調(diào)查有一定結(jié)果，但均未能確證其有致癌性的物質(zhì)，有學(xué)調(diào)查有一定結(jié)果，但均未能確證其有致癌性的物質(zhì)，有493種。種。4類類：對人類可能是非致癌物，即按目前的試驗結(jié)果，未見有致癌性：對人類可能是非致癌物，即按目前的試驗結(jié)果，未見有致癌性的物質(zhì)的物質(zhì) ，有，有1種。種。按活化的需要分類按活化的需要分類直接致癌物（

40、直接致癌物（direct carcinogens)各種烷化劑，大多為親電子反應(yīng)各種烷化劑，大多為親電子反應(yīng)物物間接致癌物（間接致癌物（indirect carcinogens)多環(huán)芳烴、芳香胺類化合物多環(huán)芳烴、芳香胺類化合物按是否具有誘變性分類按是否具有誘變性分類誘變性致癌物誘變性致癌物遺傳毒性致癌物遺傳毒性致癌物(genotoxic carcinogen)。非誘變性致癌物非誘變性致癌物非遺傳毒性致癌物非遺傳毒性致癌物(nogenotoxic crcinogen)，或稱，或稱DNA活活性外或基因外致癌物（性外或基因外致癌物（epigenetic carcinogen)。. Mutagenesi

41、s Mutagenesis generally is the appearance of evolution, results in the adaptation of changing environment but mutation induced by environmental pollutant is harmful to human health. Mutation of bodily cell will result in carcinogenesis, and mutation in reproductive cell will result in teratogenesis.

42、 Mutation is closely related to carcinogenesis, most mutagens are also carcinogens. . Teratogenesis Some agent through maternal placenta during pregnancy may disturb the development of embryo and cause sterility, abortion, stillborn and malformation. The delayed development of wit is called teratoge

43、n. This effect is not hereditary, such as thalidomide, urticaria virus. Some mutagen induced mutation of reproductive cell results in malformation, which is heritable. 5.生育毒性和發(fā)育毒性生育毒性和發(fā)育毒性 反應(yīng)停事件反應(yīng)停事件(4). Effect on immune functionSensitization: Some environmental pollutant act as allergen, is able to

44、 cause allergic disease such as pollen cause hay fever. Immunosuppression: Some environmental pollutant can cause immune suppression, disturb one or a few steps of immune process such as alkylating agent, anti- metabolic drug, ionization, UVR, some pesticide.2. Non-specific injury Apart from specifi

45、c effect, environmental pollutant may cause non-specific injury, such as increase prevalence of common diseases, frequently occurring diseases, respiratory infection, common cold and raise blood pressure. The mechanism of this is not fully identified. （四）（四）The disease caused by The disease caused b

46、y environmental pollutionenvironmental pollution1. Public nuisance disease2. Occupational disease3. Food poisoning公害病的特征公害病的特征 它是人為活動造成的嚴(yán)重環(huán)境污染所引起它是人為活動造成的嚴(yán)重環(huán)境污染所引起 引起公害病的環(huán)境污染多數(shù)是連續(xù)性的環(huán)境污染引起公害病的環(huán)境污染多數(shù)是連續(xù)性的環(huán)境污染 有一定病人數(shù)，病人往往分布在一定區(qū)域范圍內(nèi)公害病的病因是共同有一定病人數(shù)，病人往往分布在一定區(qū)域范圍內(nèi)公害病的病因是共同的；引起公害病的環(huán)境污染因素有時是復(fù)雜的，可能是單一污染物，的；引

47、起公害病的環(huán)境污染因素有時是復(fù)雜的，可能是單一污染物，也可能是多種污染物聯(lián)合作用；可能是一次污染物，也可能是二次污也可能是多種污染物聯(lián)合作用；可能是一次污染物，也可能是二次污染物染物 污染源數(shù)量及其排放污染物性質(zhì)、濃度與人群損害程度呈一定相關(guān)性污染源數(shù)量及其排放污染物性質(zhì)、濃度與人群損害程度呈一定相關(guān)性 病區(qū)人群不分年齡、性別均可發(fā)病病區(qū)人群不分年齡、性別均可發(fā)病 公害病可能流行時間長，還可能累及胎兒，危害后代；也可以是急性公害病可能流行時間長，還可能累及胎兒，危害后代；也可以是急性中毒性疾病中毒性疾病 患同一公害病的個體其癥狀與體征相似患同一公害病的個體其癥狀與體征相似 有些公害病的發(fā)病機(jī)制

48、尚不清楚，缺乏有效的治療方法有些公害病的發(fā)病機(jī)制尚不清楚，缺乏有效的治療方法 歷史上的幾次重大公害事件歷史上的幾次重大公害事件 名名 稱稱原原 因因后后 果果年年 代代倫敦?zé)熿F事件倫敦?zé)熿F事件盆地，逆溫層形成。自盆地，逆溫層形成。自18731873年以來，共發(fā)生七次，主要是采年以來，共發(fā)生七次，主要是采暖煤煙粉塵與濃霧結(jié)合，二氧化硫污染也較嚴(yán)重，煙塵達(dá)暖煤煙粉塵與濃霧結(jié)合，二氧化硫污染也較嚴(yán)重，煙塵達(dá)4.5mg/m4.5mg/m3 3，SOSO2 2達(dá)達(dá)3.8mg/m3.8mg/m3 3。僅僅19521952年年1212月的煙霧事件，比同期多死亡月的煙霧事件，比同期多死亡48074807人。人

49、。最近四次發(fā)生在最近四次發(fā)生在19541954、19561956、19571957、19621962年年比利時馬斯河谷煙比利時馬斯河谷煙霧事件霧事件狹窄盆地，逆溫層形成，含硫礦冶煉廠、煉鋼、煉鋅、煉焦狹窄盆地，逆溫層形成，含硫礦冶煉廠、煉鋼、煉鋅、煉焦、發(fā)電等排放二氧化硫等有害氣體，、發(fā)電等排放二氧化硫等有害氣體，SOSO2 2達(dá)達(dá)25 mg/m25 mg/m3 3100mg/m100mg/m3 3。數(shù)千人出現(xiàn)上呼吸道炎癥的癥狀與體征數(shù)千人出現(xiàn)上呼吸道炎癥的癥狀與體征,1,1周內(nèi)周內(nèi)6060多人死亡多人死亡19301930年年洛杉磯光化學(xué)煙霧洛杉磯光化學(xué)煙霧事件事件三面環(huán)山，一年中有三面環(huán)山，

50、一年中有100100天出現(xiàn)逆溫，大量汽車（天出現(xiàn)逆溫，大量汽車（250250萬輛）萬輛）排放出的廢氣，在日光紫外線作用下形成大量以排放出的廢氣，在日光紫外線作用下形成大量以O(shè) O3 3為主的光為主的光化學(xué)煙霧?；瘜W(xué)煙霧。造成數(shù)千人出現(xiàn)紅眼病及上呼吸道炎癥等造成數(shù)千人出現(xiàn)紅眼病及上呼吸道炎癥等，6565歲以上的老人死亡歲以上的老人死亡400400人。人。19431943、19551955年年 痛痛病事件痛痛病事件日本富山縣神通川流域，因上游鋅冶煉廠排出的含鎘廢水污日本富山縣神通川流域，因上游鋅冶煉廠排出的含鎘廢水污染了河水，居民用河水灌田，使稻米含鎘量增高。染了河水，居民用河水灌田，使稻米含鎘量

51、增高。痛痛病患者數(shù)百人，死亡痛痛病患者數(shù)百人，死亡3434人，人，100100多人出多人出現(xiàn)可疑癥狀?，F(xiàn)可疑癥狀。1955195519721972年年水俁病事件水俁病事件日本熊本縣水俁鎮(zhèn)上游，氮肥公司生產(chǎn)醋酸乙烯、氯乙烯，日本熊本縣水俁鎮(zhèn)上游，氮肥公司生產(chǎn)醋酸乙烯、氯乙烯，工廠排放含汞廢水，汞經(jīng)生物轉(zhuǎn)化形成甲基汞，居民長期食工廠排放含汞廢水，汞經(jīng)生物轉(zhuǎn)化形成甲基汞，居民長期食用含甲基汞量很高的魚、蝦、貝而中毒。用含甲基汞量很高的魚、蝦、貝而中毒。5050年來先后有年來先后有22652265人被確診人被確診( (其中其中15731573人因人因病死亡病死亡) )，另外有，另外有115401154

52、0人獲賠償人獲賠償19531953年以來年以來米糠油事件米糠油事件日本九州愛知縣，某一食用油廠在煉油時被多氯聯(lián)苯污染了日本九州愛知縣，某一食用油廠在煉油時被多氯聯(lián)苯污染了食用油。食用油。1 1萬多人中毒，萬多人中毒，1616人死亡人死亡19681968年年四日市哮喘病四日市哮喘病日本四日市、大阪市石油化工企業(yè)排放廢氣污染大氣，居民日本四日市、大阪市石油化工企業(yè)排放廢氣污染大氣，居民長期吸入含長期吸入含二氧化硫、硫酸、鉛等污染物的混合氣體二氧化硫、硫酸、鉛等污染物的混合氣體。四日市哮喘病患者四日市哮喘病患者500500多，實際患者超過多，實際患者超過20002000人。截至人。截至1972197

53、2年，日本國四日市哮喘年，日本國四日市哮喘總數(shù)達(dá)總數(shù)達(dá)63766376人人19551955年以來年以來博帕爾異氰酸甲酯博帕爾異氰酸甲酯事件事件印度博帕爾市農(nóng)藥廠貯氣罐泄漏異氰酸甲酯污染廠周圍居民印度博帕爾市農(nóng)藥廠貯氣罐泄漏異氰酸甲酯污染廠周圍居民區(qū)區(qū)中毒中毒1515萬多人，死亡萬多人，死亡25002500人，人，5 5萬多人雙目萬多人雙目失明失明19841984年年切爾貝利核電站事切爾貝利核電站事件件前蘇聯(lián)切爾貝利核電站事故造成廠周圍被放射性物質(zhì)污染前蘇聯(lián)切爾貝利核電站事故造成廠周圍被放射性物質(zhì)污染共造成共造成3030人死亡。污染區(qū)人群人死亡。污染區(qū)人群1010年追蹤，年追蹤，兒童甲狀腺癌發(fā)病

54、率增加兒童甲狀腺癌發(fā)病率增加19861986年年三三. . Factors influencing the health Factors influencing the health effect of pollutants on human bodyeffect of pollutants on human bodyThe toxicity of environmental pollutant and its health effect are determined by series of condition. On one hand it depends on physical, che

55、mical properties of the agent, dosage, length of exposure. On the other hand it is related to the sensitivity of the individuals, which is related to age, sex, health status and genetic property. 1). Physic-chemical properties of pollutants2). Dose or intensity Dose denotes the amount of chemical in

56、vade human body. Intensity denotes the strength of a physical factor, such as air temperature, or UVR.3). Length of exposure At a certain dose level, the length of exposure is an important factor of toxicity. Many toxic substances possess chronic effect, only after certain length of exposure, it acc

57、umulate and reach certain level of body burden, damage may occur. Body burden is determined by daily intake, biological half life of the agent (a constant denote the time needed for decline the body burden by half) and length of exposure. Daily intake is calculated by daily intake of food multiplica

58、tion of concentration of the agent in food, or daily inhaled air multiply concentration of the agent in the air.（四）（四）Combined action of environmen-tal factors Environmental factors usually not present alone, dust, toxic gas, vapor usually present simultaneously in the air, and toxic agent through air tract, digestive tract, even penetrate from skin, invade human