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Trong phần 2, sự chú ý được tập trung vào các chất gây ô nhiễm cụ thể. Tính chất hóa học và sinh hóa của họ đã được liên quan đến ảnh hưởng ecotoxicological của họ. Đôi khi, với sự trợ giúp của những xét nghiệm biomarker, hiệu ứng của họ khi các cá nhân liên quan đến ảnh hưởng hậu quả ở mức độ dân số và ở trên. Các xét nghiệm biomarker cung cấp bằng chứng cần thiết, ảnh hưởng xấu đến quần thể, cộng đồng và hệ sinh thái đã được gây ra bởi mức độ môi. | CHAPTER 14 Dealing with complexity the toxicity of mixtures 14.1 Introduction In Part 2 attention was focused on particular pollutants. Their chemical and biochemical properties were related to their ecotoxicological effects. Sometimes with the aid of biomarker assays their effects upon individuals were related to consequent effects at the level of population and above. The biomarker assays provided the essential evidence that adverse effects on populations communities and ecosystems were being caused by environmental levels of particular chemicals. The examples given included population declines in raptors due to eggshell thinning caused by p-p -DDE and the decline or extinction of dog whelk populations due to imposex caused by TBTs. These were relatively straightforward situations in which most of the adverse change was attributable to a single chemical. In environmental studies however one is usually dealing with mixtures of pollutants and adverse effects may be due to combinations of chemicals. There are many cases where adverse effects at the level of population or above have been shown to correlate with levels of either individual pollutants or combinations of pollutants e.g. the studies on pollution by polychlorinated aromatic compounds in the Great Lakes Chapters 5 7 . The problem is establishing where pollutant levels 2001 C. H. Walker 234 Further issues and future prospects are causally related to adverse effects. Many factors other than the pollutants actually determined by chemical analysis may cause populations to decline including shortage of food habitat change disease and climatic change and other pollutants that have not been analysed Such factors may very well correlate with the measured pollutant levels especially where comparison is simply being made between the populations in one or two polluted areas and the population in a clean area. In badly polluted areas there may be elevated levels of other pollutants in addition to those determined by .
