Clarkson T W
Department of Environmental Medicine, University of Rochester School of Medicine, New York 14642, USA.
Crit Rev Clin Lab Sci. 1997;34(4):369-403. doi: 10.3109/10408369708998098.
The major physical forms of mercury to which humans are exposed are mercury vapor, Hg0, and methylmercury compounds, Ch3HgX. Mercury vapor emitted from both natural and anthropogenic sources is globally distributed in the atmosphere. It is returned as a water-soluble form in precipitation and finds its way into bodies of fresh and ocean water. Land run-off also accounts for further input into lakes and oceans. Inorganic mercury, present in water sediments, is subject to bacterial conversion to methylmercury compounds that are bioaccumulated in the aquatic food chain to reach the highest concentration in predatory fish. Human exposure to mercury vapor is from dental amalgam and industries using mercury. Methylmercury compounds are found exclusively in seafood and freshwater fish. The health effects of mercury vapor have been known since ancient times. Severe exposure results in a triad of symptoms, erethism, tremor, and gingivitis. Today, we are concerned with more subtle effects such as preclinical changes in kidney function and behavioral and cognitive changes associated with effects on the central nervous system. Methylmercury is a neurological poison affecting primarily brain tissue. In adults, brain damage is focal affecting the function of such areas as the cerebellum (ataxia) and the visual cortex (constricted visual fields). Methylmercury also at high doses can cause severe damage to the developing brain. Today the chief concern is with the more subtle effects arising from prenatal exposure such as delayed development and cognitive changes in children.
人类接触到的汞的主要物理形态是汞蒸气（Hg0）和甲基汞化合物（Ch3HgX）。来自自然和人为来源的汞蒸气在全球大气中分布。它以水溶性形式随降水返回，并进入淡水和海洋水体。陆地径流也会进一步将汞输入湖泊和海洋。存在于水沉积物中的无机汞会被细菌转化为甲基汞化合物，这些化合物在水生食物链中生物累积，在掠食性鱼类中达到最高浓度。人类接触汞蒸气来自牙科汞合金和使用汞的行业。甲基汞化合物仅存在于海鲜和淡水鱼中。汞蒸气对健康的影响自古以来就为人所知。严重接触会导致一组症状，即易兴奋症、震颤和牙龈炎。如今，我们关注的是更细微的影响，如肾功能的临床前变化以及与中枢神经系统影响相关的行为和认知变化。甲基汞是一种神经毒素，主要影响脑组织。在成年人中，脑损伤是局部性的，影响小脑（共济失调）和视觉皮层（视野缩小）等区域的功能。高剂量的甲基汞也会对发育中的大脑造成严重损害。如今，主要关注的是产前接触所产生的更细微的影响，如儿童发育迟缓及认知变化。
