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Trong chương trước đã có nhiều ví dụ về hóa chất môi trường, cả hai tự nhiên và nhân tạo, có tác dụng có hại trên hệ thống thần kinh của động vật. Nhiều hợp chất độc hại cả động vật có xương sống và động vật không xương sống. Điều thú vị là, năm nhóm lớn thuốc trừ sâu, thuốc trừ sâu organochlorine (thuốc uống ngừa thai), thuốc trừ sâu organophosphorous (OPS), thuốc trừ sâu carbamate, pyrethroids, và neonicotinoids, tất cả nợ côn trùng độc tính của họ phần lớn hoặc toàn bộ hành động của họ trên các. | 16 Neurotoxicity and Behavioral Effects of Environmental Chemicals 16.1 INTRODUCTION In the previous chapters there have been many examples of environmental chemicals both natural and human-made that have harmful effects on the nervous system of animals. Many of these compounds are toxic both to vertebrates and invertebrates. Interestingly five major groups of insecticides organochlorine insecticides OCs organophosphorous insecticides OPs carbamate insecticides pyrethroids and neo-nicotinoids all owe their insecticidal toxicity largely or entirely to their action on sites in the nervous system. A few of these compounds have also been used to control vertebrate pests e.g. the cyclodiene endrin has been used for vole control and the OP insecticides fenthion and parathion for controlling birds . Separate chapters have been devoted to the OCs Chapter 5 OPs and carbamates Chapter 10 and the pyrethroids Chapter 12 . Other human-made pollutants also have harmful effects on the nervous system of animals although they are not used with the intention of doing so. Examples include the organomercury fungicides and tetraethyl lead which has been used as an antiknock in petrol both in Chapter 8 . It would appear therefore that the nervous system represents an Achilles heel within both vertebrates and invertebrates when it comes to the toxic action of chemicals. When pesticide manufacturers have screened for insecticidal activity across a wide diversity of organic chemicals many of the substances that have proved successful in subsequent commercial development have been neurotoxic. This line of argument can be extended to natural toxins as well Chapter 1 . Thus many plant toxins such as the pyrethrins physostigmine strychnine veratridine aconitine etc. all act upon the nervous system. As discussed earlier the presence of such compounds in plants is taken as evidence for a coevolutionary arms race between higher plants and the animals that graze upon them. The production of these
