environment and health（2hours）.ppt

<p>单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,环境与健康,武汉大学公共卫生学院,School of Public Health,Wuhan University,谭晓东,Xiaodong Tan,Introduction of Environmental Health,大气层的结构：对流层,平流层,电离层,生态系统,食物链,水体富营养化,Review of some conceptions,:,Main environmental challenges,Greenhouse effect and global warm,Ozone depletion,acidification,smog formation,human health,ecosystem health,Contributions of Different Gases to Global Warming,Trends in U.S.GHG Emissions,19901998,GHG:Green House gases;MMTCE:Million metric tons carbon equivalent,Carbon Emissions by Region 1997,(6175 Million Metric Tons Carbon),Main environmental challenges,Greenhouse effect and global warm,Ozone depletion,acidification,smog formation,human health,ecosystem health,空气中有一种叫“臭氧”的气体。臭氧分子包括,3,个氧原子。这种有毒的气体在大气中非常稀薄。,90,以上的臭氧存在于大气层的上部，或平流层，离地面有,10到50,公里。电视台每日公布的空气质量中，有一项就是臭氧。地面上的臭氧来源于汽车尾气和其他污染源。笼罩地球的臭氧层像是一层保护屏，完全挡住了太阳射来的致命的,UVC,和,UVB,射线，而放过对生物无害的紫外线,UVA。,亿万万年以来，正是这道天然屏障使得地球上万物繁衍生息，人类也得以自由自在地传宗接代。,臭氧层是地球最好的保护伞，它吸收了来自太阳的大部分紫外线。然而近二十年的科学研究和大气观测发现：每年春季南极大气中的臭氧层一直在变薄，事实上在极地大气中存在一个臭氧“洞”,这种臭氧损耗现象是一种反常现象，这是否表明这一紫外线吸收层正处于全球性灾难呢？通过不断的科学研究，人们发现人类社会活动释放的物质严重的破坏了臭氧层，当然这种现象还受到这一地区独特的气象状态（极涡、寒冷的平流层温度、极地平流层云）的影响。,本世纪,20,年代，人们使用的制冷机和空调机经常发生事故。那是由于里面的制冷剂主要是氨、二硫化碳和乙烯这些有毒、易燃的东西。能不能找到无毒、不燃、安全的制冷剂？化学家千方百计，终于找到了氟，并在,1931,年开始了含氟制冷剂的商业化生产。很快，这种安全的制冷剂又被应用到发泡剂和气雾剂中。从女人喜欢的发胶，衣物干洗、首饰和精密电子产品使用的清洗剂、空调、冰箱的制冷剂，火灾时的灭火剂，到在全世界疯狂增加的汽车上,人类尽情享受新技术带来的恩惠，却没有想到，所有这些东西中的氟里昂和哈龙，会长期存留在大气层中，积聚成一种无形的灾难，变成侵犯地球生物保护屏障,臭氧层的罪魁。,1970,年的一天，保罗,格森教授发现肥料和超音速飞机释放的氮氧化物可能对臭氧层造成破坏。他的研究提醒人类开始关注头顶上那根本看不着的臭氧层的变化。,4,年后，罗兰德和简,莫里纳教授也证实了氟里昂在大气中分裂并释放出破坏臭氧层的氯原子，灭火剂中的哈龙也在破坏臭氧层。这,3,位科学家因发现了危及人类生存的重大问题，而获得,1995,年的诺贝尔化学奖,。,Ozone Layer Depletion,臭氧层耗损引起全球关注,自80,年代以来，臭氧层破坏越来越严重，南极上空臭氧洞的面积在过去,20,年中增长了,10,倍，,1998,年臭氧洞面积达到历史最大值，并超过北美洲的面积。,臭氧的形成和破坏机理,臭氧层破坏机理得到验证,臭氧层耗损导致,UVB,辐射增加,根据,1998,年,UNEP,评估报告，,由于臭氧层耗损，不同地区,UVB,的变化如下：,北半球中纬度地区冬,/,春季增加了,7%,；,北半球中纬度地区夏,/,秋季增加了,4%,；,南半球中纬度地区全年平均增加了,6%,；,南极地区春季增加了,130%,；,北极地区春季增加了,22%,。,UVB,辐射增加的影响,导致皮肤癌和白内障，削弱免疫功能；,影响陆生生态和水生生态系统，导致粮食减产，破坏海洋食物链,；,加速材料老化,。,中国已经成为最大的,ODS,生产国和消费国,发达国家于,1995,年和,1996,年先后淘汰了,CFCs,和哈龙的生产和消费。,1996,年以来，中国,ODS,年生产和消费跃居世界第一位。,1999年,ODS,生产和消费量各约,7,万吨。,1995年南极春季臭氧洞变化,Main environmental challenges,Greenhouse effect and global warm,Ozone depletion,acidification,smog formation,human health,ecosystem health,什么是酸雨,?,简单地说，酸雨就是酸性的雨。什么是酸,?,纯水是中性的，没有味道；柠檬水，橙汁有酸味，醋的酸味较大，它们都是弱酸；小苏打水有略涩的碱性，而苛性钠水就涩涩的，碱味较大，它们是碱。科学家发现酸味大小与水溶液中氢离子浓度有关；而碱味与水溶液中羟基离子浓度有关；然后建立了一个指标：氢离子浓度对数的负值,叫,pH,值。于是，纯水的,pH,值为,7,；酸性越大，,pH,值越低；碱性越大,pH,值越高。未被污染的雨雪是中性的，,pH,值近于,7,；当它为大气中二氧化碳饱和时，略呈酸性，,pH,值为,5.65,。被大气中存在的酸性气体污染,pH,值小于,5.65,的雨叫酸雨；,pH,值小于,5.65,的雪叫酸雪；在高空或高山,(,如峨眉山,),上弥漫的雾,pH,值小于,5.65,时叫酸雾。,我国酸雨监测网,酸雨控制区,目前,我国年均降水,pH,值低于,5.60,的地区已达全国面积,40%,左右。酸雨是区域问题；大部份地区的酸雨仅仅是少部分城市排放的酸性物质经大气长程传送形成的,只要消灭了少数城市的污染源,大面积酸雨现象自然会消失。所以,酸雨控制区应不同于酸雨地区,要比酸雨地区小得多。当降水,pH,值低于,4.60时,将会对森林,农作物和材料产生损害,西方发达国家多将降水,pH,值低于,4.60,作为受控对象的标准。而降水,pH,值低于,4.60,的地区要比降水,pH,值低于,5.60,的地区小得多。除了这一标准而外,还要考虑生态系统对酸雨的承受能力问题。不同地区的土壤和植被等生态系统对硫沉降的承受能力不同,硫沉降负荷反映了该承受能力之大小,当实际硫沉降超过硫沉降负荷的区域就应予以控制。此外,酸雨控制区应包括酸雨污染最严重地区及其周边二氧化硫排放最大区域。,依此标准,我国酸雨控制地区的面积约为,80,万平方公里,占国土面积,8.40%,。它主要包括上海市,重庆市和浙江,安徽,福建,江西,湖北,湖南,广东,广西,四川,贵州,云南等省的部分城市地区。,何谓我国二氧化硫控制区,?,南方的酸雨还和北方二氧化硫的大量排放有关,仅控制酸雨地区的酸性物质排放而忽略北方二氧化硫的排放,还是不能有效地控制酸雨。二氧化硫年平均浓度的二级标准是,0.06,毫克,/,立方米,在此浓度之下,人群在环境中长期暴露将不受危害；二氧化硫日平均浓度三级标准是,0.25,毫克,/,立方米,在此浓度之下,人群在环境中短期暴露不受急性建康损害。环境空气中二氧化硫的主要危害是引起人体呼吸系统疾病,导致死亡率增加。二氧化硫污染主要来自燃煤,集中在城市,应以城市,特别是大城市为控制单元。目前,全国有,62.3%,的城市二氧化硫年均浓度超过国家二级标准,达不到保护居民和生态环境不受危害的基本要求；而日均浓度超过国家三级标准,达不到保护居民和生态环境不受急性危害的最低要求。依此标准,我国二氧化硫污染控制区面积为,29,万平方公里,占国土面积,3%,。主要包括北京市，天津市及河北，山西，内蒙，辽宁，吉林,江苏,河南,陕西,甘肃,宁夏,新疆等省的部分城市。实施双控区政策几年来,情况有了一定改进。,1999,年底,列入双控区的,175,个城市中已,有98,座城市实现了二氧化硫浓度达标,在未来十年内,情况会有明显改变。,2006年4月17日，,降下的沙土据说超过了30万吨，,京城人均摊上20公斤。,这些沙子，从内蒙古中西部远道而来，经河北北部入京，,横扫我国10个省、区、市，两亿人的生活受到影响。,Smog in Washington,DC,Main environmental challenges,Greenhouse effect and global warm,Ozone depletion,acidification,smog formation,human health,ecosystem health,Pollution and health,Environmental pollution,Public nuisance,Public nuisance diseases,pollutants,Industrial pollution,Municipal Solid Waste,Transport pollution,EPA：Pollution,Pollution is an undesirable change in the physical,chemical,or biological characteristics of the air,land,or water that will be harmful to human life or that of other species,the environment,or cultural assets;or that will result in the deterioration of raw materials resources.,Industrial Waste,Industrial waste is process waste associated with manufacturing.,This waste usually is not classified as either municipal waste or hazardous waste by federal or state laws.,Regulatory programs for managing industrial waste vary widely among state,tribal,and some local governments.,Each year,industrial facilities generate and manage 7.6 billion tons of,nonhazardous,industrial waste in land application units.,Municipal Solid Waste,EPA definition,includes wastes such as durable goods,nondurable goods,containers and packaging,food scraps,and miscellaneous inorganic wastes from residential,commercial,institutional,and industrial sources.,Examples of waste from these categories include appliances,automobile tires,newspapers,clothing,boxes,disposable tableware,office and classroom paper,wood pallets,and cafeteria wastes.,Transport is a Major Source of Air Pollution,Six Principal Air Pollutants Tracked Nationally by EPA,Nitrogen Dioxide(NO,2,),Ozone(O,3,)-formed by volatile organic compounds(VOCs)and nitrogen oxides(NO,x,),Sulfur Dioxide(SO,2,),Particulate Matter(PM)-formed by SO,2,NO,x,ammonia,VOCs,and direct particle emissions,Carbon Monoxide(CO),Lead(Pb),Principles of Toxicology:The Study of Poisons,Elizabeth Casarez,Department of,Pharmacology and Toxicology,University of Arizona,The study of the,adverse effects,of a,toxicant,on,living organisms,Adverse effects,any change from an organisms normal state,dependent upon the concentration of active compound at the target site for a sufficient time.,Toxicant(Poison),any agent capable of producing a deleterious response in a biological system,Living organism,a sac of water with target sites,storage depots and enzymes,What is a Poison?,All substances are poisons;,there is none that is not a poison.,The right,dose,differentiates a poison and a remedy.,Paracelsus(1493-1541),Dose,The amount of chemical entering the body,This is usually given as,mg of chemical/kg of body weight=,mg/kg,The dose is dependent upon,The environmental concentration,The properties of the toxicant,The frequency of exposure,The length of exposure,The exposure pathway,What is a Response?,The degree and spectra of responses depend upon the dose and the organism-describe exposure conditions with description of dose,Change from normal state,could be on the molecular,cellular,organ,or organism level-the symptoms,Local vs.Systemic,Reversible vs.Irreversible,Immediate vs.Delayed,Graded vs.,Quantal,degrees of the same damage vs.all or none,Dose-Response Relationship:,As the dose of a toxicant increases,so does the response.,2,3,4,0,1,DOSE,RESPONSE,0-1 NOAEL,2-3 Linear Range,4 Maximum Response,DOSE DETERMINES THE BIOLOGICAL RESPONSE,LD,50,Quantal,responses can be treated as gradient when data from a population is used.,The cumulative proportion of the population responding to a certain dose is plotted per dose-10-30 fold variation w/in a population,If Mortality is the response,the dose that is lethal to 50%of the population LD,50,can be generated from the curve,Different toxicants can be compared-lowest dose is most potent,LD,50,Comparison,Exposure:Pathways,Routes and Sites of Exposure,Ingestion(Gastrointestinal Tract),Inhalation(Lungs),Dermal/Topical(Skin),Injection,intravenous,intramuscular,intraperitoneal,Typical Effectiveness of Route of Exposure,iv inhale,ip,im,ingest topical,Exposure:Duration,Acute,3morepeated doses,Over time,the amount of chemical in the body can build up,it can redistribute,or it can overwhelm repair and removal mechanisms,ADME:Absorption,Distribution,Metabolism,and Excretion,Once a living organism has been exposed to a toxicant,the compound must get into the body and to its target site in an active form in order to cause an adverse effect.,The body has defenses:,Membrane barriers,passive and facilitated diffusion,active transport,Biotransformation enzymes,antioxidants,Elimination mechanisms,Absorption:,ability of a chemical to enter the blood(blood is in equilibrium with tissues),Inhalation-,readily absorb gases into the blood stream via the alveoli.(Large alveolar surface,high blood flow,and proximity of blood to alveolar air),Ingestion-,absorption through GI tract stomach(acids),small intestine(long contact time,large surface area-,villi,;bases and transporters for others),1st Pass Effect (liver can modify),Dermal-,absorption through epidermis(stratum,corneum,),then dermis;site and condition of skin,Distribution:,the process in which a chemical agent,translocates,throughout the body,Blood carries the agent to and from its site of action,storage depots,organs of transformation,and organs of elimination,Rate of distribution(rapid)dependent upon,blood flow,characteristics of toxicant(affinity for the tissue,and the partition coefficient),Distribution may change over time,Distribution:Storage and Binding,Storage in Adipose tissue-Very,lipophylic,compounds(DDT)will store in fat.Rapid mobilization of the fat(starvation)can rapidly increase blood concentration,Storage in Bone-Chemicals analogous to Calcium-Fluoride,Lead,Strontium,Binding to Plasma proteins-can displace endogenous compounds.Only free is available for adverse effects or excretion,Target Organs:,adverse effect is dependent upon the concentration of active compound at the,target site,for enough time,Not all organs are affected equally,greater susceptibility of the target organ,higher concentration of active compound,Liver-,high blood flow,oxidative reactions,Kidney-,high blood flow,concentrates chemicals,Lung-,high blood flow,site of exposure,Neurons-,oxygen dependent,irreversible damage,Myocardium-,oxygen dependent,Bone marrow,intestinal mucosa-,rapid divide,Target Sites:Mechanisms of Action,Adverse effects can occur at the level of the molecule,cell,organ,or organism,Molecularly,chemical can interact with,Proteins Lipids DNA,Cellularly,chemical can,interfere with receptor-,ligand,binding,interfere with membrane function,interfere with cellular energy production,bind to,biomolecules,perturb homeostasis(Ca),Excretion:,Toxicants are eliminated from the body by several routes,Urinary excretion,water soluble products are filtered out of the blood by the kidney and excreted into the urine,Exhalation,Volatile compounds are exhaled by breathing,Biliary,Excretion via Fecal Excretion,Compounds can be extracted by the liver and excreted into the bile.The bile drains into the small intestine and is eliminated in the feces.,Milk Sweat Saliva,Metabolism:,adverse effect depends on the concentration of,active compound,at the target site over time,The process by which the administered chemical(parent compounds)are modified by the organism by enzymatic reactions.,1,o,objective-make chemical agents more water soluble and easier to excrete,decrease lipid solubility -decrease amount at target,increase ionization -increase excretion rate-decrease toxicity,Bioactivation,-,Biotransformation can result in the formation of reactive metabolites,Biotransformation(Metabolism),Can drastically effect the rate of clearance of compounds,Can occur at any point during the compounds journey from absorption to excretion,Biotransformation,Key organs in biotransformation,LIVER(high),Lung,Kidney,Intestine(medium),Others(low),Biotransformation Pathways,Phase I-make the toxicant more water soluble,Phase II-Links with a soluble endogenous agent(conjugation),Individual Susceptibility-,there can be 10-30 fold difference in response to a toxicant in a population,Genetics-,species,strain variation,interindividual,variations(yet still can extrapolate between mammals-similar biological mechanisms),Gender,(gasoline,nephrotox,in male mice only),Age-young(old too),underdeveloped excretory mechanisms,underdeveloped biotransformation enzymes,underdeveloped blood-brain barrier,Individual Susceptibility,Age-old,changes in excretion and metabolism rates,body fat,Nutritional status,Health conditions,Previous or Concurrent Exposures,additive-antagonistic,synergistic,Other concepts,Lethal dose,Threshold dose,MEL minimal effect level,Maximal no effect dose,Toxic effect zone,Acute toxic zone,Z,ac,=LD,50,/Lim,ac,Chronic toxic zone,Z,ch,=,Lim,ac,/,Lim,ch,Lim,ch,Lim,ac,LD,50,LD,100,Health effect spectrum,Interaction between environment and health,Environmental pollution,Pathological effects:,acute and chronic poisoning,carcinogenesis,Teratogenesis,Mutagenesis,spontaneous mutation,induced mutation,Combination effects,Pollution Control,Industrial pollution by the laws,Transportation pollution by the laws,Health education for all citizens,生活垃圾分类：,Germany 3,bottles,papers and cans,examples:,France:divided by 2 bottle and papers,Germany 3,bottles,papers and cans,Holland 4,bottles papers cans,plastics,Switzerland 5,bottle,papers,cans,plastics,foams,摄于2000年台北市,当前的问题:环卫工人统一转运(不分回收还是非回收).消费者不懂标记,海南市,3R:reduce,reuse,recycle,3R:reduce,reuse,recycle,</p>