重金属

HEAVY METALS 重金属 朱雪梅 2012.5.16 HEAVY METALS The term heavy metal refers to any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations. Properties y are natural components of the Earth's crust y they cannot be degraded or destroyed y to a small extent they enter our bodies via food, drinking water and air y as trace elements, some heavy metals (e.g. copper, selenium, zinc) are essential to maintain the metabolism of the human body y however, at higher concentrations they can lead to poisoning y heavy metal poisoning could result, for instance, from drinking-water contamination (e.g. lead pipes), high ambient air concentrations near emission sources, or intake via the food chain Heavy Metals y Cadmium and mercury are released as a by- product of mining and smelting Æ primary long-range transport is through the atmosphere y Metal levels are highest in people who eat large amounts of organ meat Poisoning mechanism y Reaction with protein y Reaction with nucleic acid y Reaction with amino acid，vitamin, hormone, fatty acid, sugar……. Losing their bioactivity enhancing their bioactivity 近年，根据泰国、澳大利亚、新西兰和丹麦等国家的科研人员对一些鲨鱼鱼翅进行详细调查分析，发现鱼 翅中含有大量的汞，食用后危害相当严重。尤其是孕妇，若摄入过多，不仅可导致流产、死胎，会影响幸存胎 儿大脑和神经细胞的生长，使他们患上“先天性水俣病”?穴此病因多发于日本水俣湾而得名?。轻者患儿的注 意力、记忆力、语言能力和脑的其他功能发育迟延；重则可导致幼儿发育不良、智力低下、畸形，甚至脑瘫痪 死亡。科学家还提醒，即使母亲摄入的汞不多，胎儿的发育也可能发生迟延。即便非妊娠期的育龄妇女，摄入 多量的甲基汞也不利优生，严重的可导致不育。 水俣病事件 y 发生时间：1953年——1956年 发生地点：日本熊本县水俣市 y 从l932年开始，日本氮肥公司在氮肥生产中使用含汞催化剂；1949年后，这个公司开始生 产氯乙烯(C2H3C])； 1956年产量超过6000吨。与此同时，工厂把没有经过任何处理的废 水排放到水俣湾中。 1956年，水俣湾附近发现了一种奇怪的病。这种病症最初出现在猫身上，病猫步态 不稳，抽搐，甚至跳海“自杀”，因此被称为“猫舞蹈症”。但是不久之后，当地发现了有 人患有这些病症。患者轻者口齿不清、步履蹒跚、面部痴呆、手足麻痹、知觉出现障碍、 手足变形，重者神经失常，直至死亡。由此，恐慌随即蔓延开来，然而，当地居民的这一 噩梦其实才刚刚开始,先后有2265人被确诊患有水俣病。 后来的研究表明，日本氮肥公司排放的废水中含有大量的汞，当汞离子在水中被鱼虾 摄入体内后转化成甲基汞(CH3Hg) ¬----一种主要侵犯神经系统的有毒物质。水俣湾里 的鱼虾因为工业废水被污染，而这些被污染的鱼虾又被动物和人类食用。甲基汞进入人体 后，会导致神经衰弱综合征，精神障碍、昏迷、瘫痪、震颤等，并可导致发生肾脏损害， 重者可致急性肾功能衰竭，此外还可以致心脏、肝脏损害。据统计，有数十万人食用了水 俣湾中被甲基汞污染的鱼虾。 Mercury – Hg(汞) Mercury is the only common metal which is liquid at ordinary temperatures. It rarely occurs free in nature and is found mainly in cinnabar ore (HgS) in Spain and Italy. It alloys easily with many metals, such as gold, silver, and tin - these alloys are called amalgams. Its ease in amalgamating with gold is used in the recovery of gold from its ores. Health effects of mercury y Disruption of the nervous system y Damage to brain functions y DNA damage and chromosomal damage y Allergic reactions, resulting in skin rashes, tiredness and headaches y Negative reproductive effects, such as sperm damage, birth defects and miscarriages Air pollution y Fossil fuel combustion y Mining y Smelting y Solid waste combustion Water pollution y the application of agricultural fertilizers and industrial wastewater disposal Environmental effects of mercury y Acidic surface waters can contain significant amounts of mercury y When the pH values are between five and seven, the mercury concentrations in the water will increase due to mobilisation of mercury in the ground y Once mercury has reached surface waters or soils microorganisms can convert it to methyl mercury, a substance that can be absorbed quickly by most organisms and is known to cause nerve damage y Fish are organisms that absorb great amounts of methyl mercury from surface waters every day (mercury can accumulate in fish and in the food chains) Maximum level of Hg in some food GB2762(mg/kg Hg) y 粮食（成品粮）：0.02 y 豆类、薯类、果蔬：0.01 y 肉、蛋：0.05 y 鱼（不包括食肉鱼）和其它水产品：0.5（甲基汞） y 食肉鱼（鲨鱼、金枪鱼）：1.0 痛痛病事件 y 1955～1972年发生在日本富山县神通川流域。横贯日本中部的富山平原有一条清水河叫神通川 ，两岸人民世世代代喝这条河的水长大，并用这条河的水灌溉两岸肥沃的土地，使这一带成为日 本主要的粮食产地。后来三井金属矿业公司在这条河的上游设立了神冈矿业所，建成炼锌工厂， 把大量污水排入神通川。 1952年，这条河里的鱼大量死亡，两岸稻田大面积死秧减产。1955年以后，在河流两岸的群 马县等地出现一种怪病，患者一开始是腰、手、脚等各关节疼痛，延续几年之后，身体各部位神 经痛和全身骨痛，不能行动，最后骨骼软化萎缩，自然骨折，直到在衰弱疼痛中死去。有的人因 无法忍受痛苦而自杀。由于病人经常“哎唷——哎唷”地呼叫呻吟，日本人便称此病症为“哎唷— —哎唷病”，即“痛痛病”。 痛病患者在1960年以前就开始出现，但直到1961年才有人查明，此病与三井金属矿业公司神 冈炼锌厂的废水有关。该公司把炼锌过程中未经处理净化的含镉废水长年累月地排放到神通川中 ，而当地居民长期饮用受镉污染的河水并食用此水灌溉的含镉稻米，致使镉在体内蓄积而造成肾 损害，进而导致骨软化症。 后来，日本痛痛病患区已远远超过神通川，而扩大到黑川、铅川、二迫川等7条河的流域。截 至1968年，共确诊患者258例，其中死亡128例。 镉污染事件 y 我国发生的事件 y 1、中国广州中山大学生物科技学院联同香港浸会大学生物系 在2006年3至4月期间，抽查化验中港两地市面出售的杨桃，51%镉 含量属严重超标； y 2、2005年12月15日广东省环保部门检测发现，从孟洲坝电站 断面到高桥断面全部超过标准，高桥断面镉超标近10倍，也引发了 对于企业污水排放治理力度的讨论。 y 3、2009年8月3日下午4时，湖南省环保厅在浏阳市镇头镇向 当地村民代表正式公布了长沙湘和化工厂镉污染事件环境调查监测 结论。结论显示，此次镉污染事件，主要是由于长沙湘和化工厂废 渣、废水、粉尘、地表径流、原料产品运输与堆存，以及部分村民 使用废旧包装材料和压滤布等造成； y 4、2012年1月15日起，广西龙江河宜州拉浪段发现重金属镉超 标。截至1月21日18时，污染事件已造成大约28.1万尾鱼死亡，宜 州市怀远镇附近群众生活用水直接受到影响。 Cadmium – Cd（镉） y Human uptake of cadmium takes place mainly through food y Foodstuffs that are rich in cadmium can greatly increase the cadmium concentration in human bodies (liver, mushrooms, shellfish, mussels, cocoa powder and dried seaweed) HEALTH EFFECTS y Diarrhoea, stomach pains and severe vomiting y Bone fracture y Reproductive failure and possibly even infertility y Damage to the central nervous system y Damage to the immune system y Psychological disorders y Possibly DNA damage or cancer development Environmental effects of cadmium y Cadmium can be transported over great distances when it is absorbed by sludge y This cadmium-rich sludge can pollute surface waters as well as soils y Cadmium strongly adsorbs to organic matter in soils y When cadmium is present in soils it can be extremely dangerous, as the uptake through food will increase y Soils that are acidified enhance the cadmium uptake by plants y This is a potential danger to the animals that are dependent upon the plants for survival – Cadmium can accumulate in their bodies, especially when they eat multiple plants y Cows may have large amounts of cadmium in their kidneys due to this Maximum level of Cd in some food GB2762(mg/kg Cd) y 面粉、杂粮：0.1 y 大米大豆：0.2 y 水果、花生：0.05 y 肉、鱼：0.1 y 蛋：0.05 y 根茎蔬菜：0.1 y 叶菜、芹菜、食用菌：0.2 Environmental effects of cadmium y In aquatic ecosystems cadmium can bioaccumulate in mussels, oysters, shrimps, lobsters and fish y The susceptibility to cadmium can vary greatly between aquatic organisms y Salt-water organisms are known to be more resistant to cadmium poisoning than freshwater organisms 近日有媒体爆出，珍珠奶茶里的“珍珠”普遍含有明胶成分。年轻人爱喝的珍 珠奶茶里，含不含皮革明胶等违规成分？ Chromium – Cr（铬） y Chromium(III) is an essential nutrient for humans and shortages may cause heart disease, disruptions of metabolisms and diabetes y But the uptake of too much chromium(III) can cause health effects as well, for instance skin rashes y Chromium(VI) is mainly toxic to organisms - it can alter genetic materials and cause cancer Chromium - Cr Chromium(VI) is a danger to human health, mainly for people who work in the steel and textile industry People who smoke tobacco also have a higher chance of exposure to chromium Hexavalent Chromium – Chromium (VI) is a species of chromium that is forbidden to use in electrical & electronic industry by RoHS Directive. HEALTH EFFECTS y When it is a compound in leather products, it can cause allergic reactions, such as skin rash y After breathing it in, chromium(VI) can cause nose irritations and nosebleeds y Upset stomachs and ulcers y Respiratory problems y Weakened immune system y Kidney and liver damage y Alteration of genetic material y Lung cancer y Death Environmental effects of chromium y Most of the chromium in air will eventually settle and end up in waters or soils y Chromium in soils strongly attaches to soil particles and as a result it will not move towards groundwater y In water chromium will absorb on sediment and become immobile y Only a small part of the chromium that ends up in water will eventually dissolve Maximum level of Cr in some food GB2762(mg/kg Cr) y 粮食、豆类、肉、蛋：1.0 y 薯类、果蔬：0.5 y 鱼贝类：2.0 铅污染 Lead – Pb（铅） y Foods such as fruit, vegetables, meats, grains, seafood, soft drinks and wine may contain significant amounts of lead y Cigarette smoke also contains small amounts of lead Lead – Pb y Generally，the average daily intake of lead is 60ug y The average absorption by digestive tract is 8% y The absorption by respiratory tract is 29% y Most of absorbed lead is eliminate by kidney Lead source y Industrial contamination y vehicle exhaust y The food container and package y Inadequate food additives y natural Health effects of lead y Disruption of the biosynthesis of haemoglobin and anemia y A rise in blood pressure y Kidney damage y Miscarriages y Disruption of nervous systems y Brain damage y Declined fertility of men through sperm damage y Diminished learning abilities of children y Behavioural disruptions of children, such as aggression, impulsive behaviour and hyperactivity Health effects of lead y Lead can enter a foetus through the placenta of the mother y Because of this it can cause serious damage to the nervous system and the brains of unborn children That is why women in pregnancy can not work with lead. Effects of lead Lead accumulates in the bodies of water organisms and soil organisms Health effects on shellfish can take place even when only very small concentrations of lead are present Body functions of phytoplankton can be disturbed when lead interferes. Phytoplankton is an important source of oxygen production in seas and many larger sea-animals eat it That is why we now begin to wonder whether lead pollution can influence global balances Maximum level of Pb in some food GB2762(mg/kg Pb) y 谷类、豆类、薯类：0.2 y 水果、蔬菜（球茎、叶菜、食用菌除外）：0.1 y 肉、蛋：0.2 y 茶叶：5 y 鲜乳：0.05 y 婴儿配方奶风：0.02 HEAVY METALS HEAVY METALS Properties Heavy Metals Poisoning mechanism 幻灯片编号 6 水俣病事件 Mercury – Hg(汞) Health effects of mercury Air pollution Water pollution Environmental effects of mercury 幻灯片编号 13 Maximum level of Hg in some food 痛痛病事件 镉污染事件 Cadmium – Cd（镉） HEALTH EFFECTS Environmental effects of cadmium 幻灯片编号 20 Environmental effects of cadmium 幻灯片编号 22 Chromium – Cr （铬） Chromium - Cr HEALTH EFFECTS Environmental effects of chromium Maximum level of Cr in some food 铅污染 Lead – Pb （铅） Lead – Pb Lead source Health effects of lead Health effects of lead Effects of lead 幻灯片编号 35