4.6 Postscript to Section 4
This section has considered a small number of chemical pollutants of water and has examined what is known about their harmful effects on animals, humans and the environment. You should be aware of a number of important general points that arise from what you have read. First, there is an enormous variety of chemical pollutants; you have read about only a few. Secondly, the evidence that chemical pollutants are potentially harmful is often more convincing from studies of animals than it is from studies of human health. Thirdly, you have read mostly about amphibians; much is known about the harmful effects of chemical pollutants on other animals, but they have been the focus here because of their role as ‘canaries’, possibly providing early warning of environmental problems. Finally, while much is known about the harmful effects of chemical pollutants on wildlife and people, this body of knowledge pales into insignificance in comparison with what is not known.