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Tại sao là một độc tố độc hại? Theophrastus Bombastus von Hohenheim, được biết đến trong lịch sử như Paracelsus, người được sinh ra trong ngôi làng của Thụy Sĩ Einsiedeln năm 1493 và qua đời năm 1541, dạy chúng ta rằng mức độ nghiêm trọng của chất độc liên quan đến liều dùng (xem Strathern, 2000). Trích dẫn của ông: "Tất cả các chất đều là thuốc độc, có là không có gì mà không phải là một chất độc. Liều dùng phải phân biệt một chất độc từ một phương thuốc "được tìm thấy trong chương đầu tiên của. | chapter two Why is a toxicant poisonous Theophrastus Bombastus von Hohenheim better known in history as Paracelsus who was born in the Swiss village of Einsiedeln in 1493 and died in 1541 taught us that the severity of a poison was related to the dose see Strathern 2000 . His citation All substances are poisons there is none which is not a poison. The right dose differentiates a poison from a remedy is found in the first chapter of almost all textbooks of toxicology or pharmacology. However the molecular theory was formulated more than 300 years later and the law of mass action not until after the middle of the 19th century. Real rational toxicology and pharmacology are dependent on these laws and hence could not develop properly before they were known. Paracelsus idea that all substances are poisons is of course correct even water air and sugar are poisons in sufficient amounts but by looking at the chemical structures of typical poisons and trying to sort out the reactions they tend to be involved in we can roughly put them into seven categories. By using the molecular theory the law of mass action and our knowledge of the nature of the chemical processes in organisms we can condense biochemical toxicology to three sentences and about seven types of reactions 1. Toxic molecules react with biomolecules according to the common laws of chemistry and physics so that normal processes are disturbed. 2. The symptoms increase in severity with increasing concentration of the toxicant at the site of reaction. 3. This concentration increases with increasing dose. 2.1 Seven routes to death The chemist may prefer to classify toxicants according to their chemical structure the doctor according to the organ they harm the environmentalist according to their stability in the environment and so forth. The biochemist may use a different classification and we will approach the toxicology of pesticides from the biochemist s perspective. Because of point 1 above and because the cells
