tailieunhanh - ECOTOXICOLOGY: A Comprehensive Treatment - Chapter 9

Khi toxicologists thêm tiền tố sinh thái đến lĩnh vực của chất độc, do đó các từ đã trở thành sinh thái chất độc, họ vẫn tiếp tục chủ yếu để thực hiện các phép đo cùng một họ thực hiện trước khi đổi tên. (Cairns 1992) Tử vong có thể do tiếp xúc cấp tính hoặc mãn tính chất độc có trong nhiều nguồn khác nhau. Sự khác biệt giữa thời gian tiếp xúc cấp tính và mãn tính, được thông qua từ chất độc của con người, dựa nhiều vào chủ nghĩa thực dụng như độc tố âm thanh | 9 Lethal Effects OVERVIEW When toxicologists added the prefix eco to the field of toxicology so that the word became ecotoxicology they continued primarily to make the same measurements they made before the name changed. Cairns 1992 Death can result from acute or chronic exposures to toxicants contained in many diverse sources. The distinction between acute and chronic exposure duration adopted from human toxicology is based as much on pragmatism as sound toxicology. A lethal exposure is customarily categorized as acute if it is a relatively brief and intense one to a poison. Standard durations are espoused for conducting acute lethality tests. For example Sprague 1969 argued for 96 h after observing that For 211 of 375 toxicity tests reviewed acute lethal action apparently ceased with 4 days although this tabulation may have been biased . This kind of correlative analysis and the convenience of fitting a test within the workweek motivated the initial codification of a 96-h test. It is important to note that Sprague stated in his 1969 monograph that his intentions were to describe profitable bioassay methods about which there was ample room for healthy disagreement. Along the vein of healthy disagreement one could conclude from these same data that a 96-h duration was insufficient for characterizing acute lethality in more than 4 out of 10 tests Figure . Further Sprague notes that the tests considered in making his recommendation included many static tests1 in which toxicant concentrations probably decreased substantially during the exposures and that those results from continuous flow tests that had much less chance of substantial toxicant concentration decrease during the tests generally indicated a longer duration was needed than did the static tests. Given the urgency in the 1960s for standard tools for dealing with pervasive pollution the assumption that mortality by 96 h accurately reflected that occurring during any acute exposure duration is an .