tailieunhanh - Mercury Hazards to Living Organisms - Chapter 4

Độc tính của thủy ngân đã được công nhận từ thời cổ đại (Hook và Hewitt, 1986). Không có kim loại khác cho thấy sự đa dạng của các hiệu ứng gây ra bởi các hình thức khác nhau sinh hóa hơn so với thủy ngân (Goyer, 1986). Toxicologically, có ba hình thức thủy ngân: (1) nguyên tố thủy ngân, (2) các hợp chất thủy ngân vô cơ, và (3) organomercurials (Goyer, 1986). Trong số các hình thức khác nhau của thủy ngân và các hợp chất của nó, nguyên tố thủy ngân ở dạng hơi, thủy ngân thủy ngân,. | Chapter 4 Mercury Poisoning and Treatment The toxicity of mercury has been recognized since antiquity Hook and Hewitt 1986 . No other metal demonstrates the diversity of effects caused by different biochemical forms than does mercury Goyer 1986 . Toxicologically there are three forms of mercury 1 elemental mercury 2 inorganic mercury compounds and 3 organomercurials Goyer 1986 . Among the various forms of mercury and its compounds elemental mercury in the form of vapor mercuric mercury and methylmercury have the greatest toxicological potential Satoh 1995 . Metallic or elemental mercury volatilizes to mercury vapor at ambient air temperatures and most human exposure is by inhalation. Mercury vapor is lipid soluble readily diffuses across the alveolar membranes and concentrates in erythrocytes and the central nervous system. Inorganic mercury salts can be divalent mercuric or monovalent mercurous . Gastrointestinal GI absorption of inorganic salts of mercury from food is less than in mice and about in a study of human volunteers however methylmercury absorption in the GI tract is to . Methylmercury when compared to inorganic mercury compounds is about 5 times more soluble in erythrocytes than in plasma and about 250 times more abundant in hair than in blood Goyer 1986 . POISONING The primary mode of action of both inorganic and organic mercury compounds is associated with interference of membrane permeability and enzyme reactions through binding of mercuric ion to sulfhydryl groups although organomercurials can penetrate membranes more readily Norton 1986 . Early accounts of acute and chronic mercury poisoning and their treatment follow Anon. 1948 however it is cautioned that treatment should be under the guidance of a physician. Elemental Mercury Metallic or elemental mercury volatilizes to mercury vapor at ambient air temperatures and most human exposure is by way of inhalation Goyer 1986 . The saturated vapor pressure at C is .