環境與職業汞暴露之健康效應：系統性回顧

Health Effects of Environmental and Occupational Mercury Exposure: Systemic Review

王建楠(Jian-Nan Wang) ； 李璧伊(Pi-I Li)

《中華職業醫學雜誌》 23卷3期 (2016/07) Pp. 171-179

摘要

汞(mercury)是一種銀白色重金屬，在室溫下呈液態狀，也因此俗稱為水銀，在高溫下易成蒸汽，經由呼吸系統進入人體。汞之高蒸汽壓力特性，導致持續釋放至空氣中，可說是職業暴露與環境污染之主要貢獻因子。汞主要是從硫化汞化合物(HgS)中萃煉取得，釋放至大氣中的汞主要來自天然資源(如火山)或工業排放，造成全球性汞之分佈。日常雨水可補獲氧化汞(oxidized mercury)及將元素汞還原至水體中(如湖泊、河流、海灣、海洋等)，當海洋生物攝取到汞及生物甲基化(biomethylated)化，透過食物鏈(food chain)，會蓄積在動物及人類體內。蒸汽汞最後亦可能進入土攘中，造成種植農作物之污染。早期汞被用於黃金開採，自礦石(ore)中萃取金或形成汞合金(amalgam)。在汞合金燃燒之場所，附近空氣中汞蒸汽之濃度，幾乎總是超過世界衛生組織(WHO)所訂之暴露標準上限1.0 ug/m3 。過去農業曾用烷基汞化物( 如甲基汞、乙基汞等) 作為穀物之薰蒸劑(fumigants)，導致人類嚴重汞中毒事件。元素汞在目前工業上使用非常廣泛，如控制儀、燈管、整流器(rectifiers)、溫度計、氣壓計、血壓計、電池及電氣設備等，汞亦常用於電鍍業(plating)、首飾業(jewelry)、皮革鞣製業(tanning)或動物標本製作(taxidermy)。人類因暴露汞而引發中毒(intoxication)，依接觸來源可分為三大類即元素汞(elementalmercury)、無機汞(inorganic mercury)、有機汞(organic mercury)，可能是急性大量暴露或慢性長期暴露。一般急性中毒常見於吸入大量汞蒸汽，引發咳嗽、胸悶、呼吸困難、腹痛、噁心、嘔吐、頭痛、金屬味等臨床症狀，嚴重時可導致肺水腫、呼吸衰竭，甚至死亡。汞一旦進入血液中，迅速被氧化成二價汞，沉積在腎臟。汞本身脂溶性高，可通過腦血管屏障(brain blood barrier,BBB)，氧化成二價汞而蓄積在中樞神經系統，引發手顫抖、步態不穩、感覺異常等症狀。長期無機汞(即汞與非碳之化合物)中毒可能引發腸胃道、腎功能及神經系統方面問題，如腸胃不適、金屬味、口腔灼熱感、牙齒鬆脫、蛋白尿、腎衰竭、手顫抖、步態不穩、感覺異常、視野縮小、焦躁不安、注意力無法集中、瞻妄等症狀。有機汞(汞與碳結合之化合物)中毒，來源絕大多數是使用汞之工業廢料所產生，排放至水域中，經食物鏈之生物蓄積放大效應，最後被人類服食，最著名的即發生於日本的水俁病(Minamatadisease)，工廠排放汞至海灣，導致附近居民嚴重甲基汞中毒。

關鍵字

汞 ； 無機汞 ； 有機汞 ； 中樞神經系統 ； 腸胃系統 ； 腎毒性

並列摘要

Mercury is a kind of silver-white heavy metal, it is a liquid at room temperature, hence also called watery silver. At high temperature, mercury can easily evaporize, via respiratory tract into the body. Due to high vapor pressure character of mercury, it may continuously release to the air, a major contributing factor to environmental and occupational pollution. Mercury mainly comes from extractions of mercury sulfide, mercury releasing into the atmosphere might originate from natural sources(such as volcanoes) or industrial emmisions, and finally globally distributed. Daily rains can capture oxidized mercury and element mercury, reduced to water field(suche as lakes, rivers, bays, and oceans).When ocean organisms take in mercury and biomethylated, via the food-chain process, it might accumulate in animals and human body. As for mercury vapor, it finally dropped into the soil, resulted in agricultural contamination. Elementary mercury is used in control instruments, tubes, rectifiers, thermometes, barometers, batteries, and electrical devices. Mercury is also used in plating, jewelry, tanning, and taxidermy. Historical use of alkyl mercury compounds as grain fumigants caused serious human poisoning. Mercury dental amalgams remain an important source of low-level exposure, along with vaccines containing preservative thiomersal. Human poisoning due to mercury exposure, it may be classified into three kinds according to contact sources, namely elementary mercury, inorganic mercury, and organic mercury, it might be acute high concentrations inhalation or chronic low-level exposure. Elemental mercury is efficiently absorbed after the inhalation but not in- gestion. Inhalation of high concentrations of mercury vapor causes cough, dyspnea, chest discomfort, nausea, vomiting, abdominal pain, etc., severe cases might develop pulmonary edema, respiratory failure, even death. Inorganic compounds are distribut- ed into many tissues, primarily the brain and kidney, they bind to sulfhydryl groups and may interfere with numerous cellular enzymes. Chronic exposure to inorganic mercury primarily affects the nervous system, such as resting fine tremor, head tremor,s keletal ataxia, coarse jerking movement, hallucination, dementia, etc.

並列關鍵字

mercury ； organic mercury ； inorganic mercury ； central nervous system ； gastrointestinalsystem ； renal toxicity