Giới thiệu về Kiểm tra Độc tính Độc tính là tài sản hoặc tài sản của một vật liệu tạo ra một tác dụng có hại khi một hệ thống sinh học. Độc tố là nguyên liệu sản xuất này có hiệu lực sinh học. Phần lớn các hóa chất được thảo luận trong văn bản này có nguồn gốc con người tạo ra hoặc do con người gây ra. Điều này không phải là để phủ nhận rằng các tài liệu cực kỳ độc hại được tạo ra bởi hệ thống sinh học, nọc độc, nội độc tố botulinum, và. | CHAPTER 3 An Introduction to Toxicity Testing Toxicity is the property or properties of a material that produces a harmful effect upon a biological system. A toxicant is the material that produces this biological effect. The majority of the chemicals discussed in this text are of man-made or anthropogenic origin. This is not to deny that extremely toxic materials are produced by biological systems venom botulinum endotoxin and some of the fungal aflatoxins are extremely potent materials. However compounds that are derived from natural sources are produced in low amounts. Anthropogenically derived compounds can be produced in the millions of pounds per year. Materials introduced into the environment come from two basic types of sources. Point discharges are derived from such sources as sewage discharges waste streams from industrial sources hazardous waste disposal sites and accidental spills. Point discharges are generally easy to characterize as to the types of materials released rates of release and total amounts. In contrast nonpoint discharges are those materials released from agricultural run-offs contaminated soils and aquatic sediments atmospheric deposition and urban run-off from such sources as parking lots and residential areas. Nonpoint discharges are much more difficult to characterize. In most situations discharges from nonpoint sources are complex mixtures amounts of toxicants are difficult to characterize and rates and the timing of discharges are as difficult to predict as the rain. One of the most difficult aspects of nonpoint discharges is that the components can vary in their toxicological characteristics. Many classes of compounds can exhibit environmental toxicity. One of the most commonly discussed and researched are the pesticides. Pesticide can refer to any compound that exhibits toxicity to an undesirable organism. Since the biochemistry and physiology of all organisms are linked by the stochastic processes of evolution a compound toxic to
