Further review of certain persistent organochlorine pesticides used in Great Britain.
- Great Britain. Advisory Committee on Pesticides and Other Toxic Chemicals
- Date:
- 1969
Licence: Public Domain Mark
Credit: Further review of certain persistent organochlorine pesticides used in Great Britain. Source: Wellcome Collection.
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![widespread. This chemical probably remains biologically active in the soil longer than any of the other organochlorine insecticides in common use. TDE is used much less than DDT and most TDE found in the soil probably arises from the degradation of DDT. Like DDT, it is relatively persistent in the soil. 93. Following our 1964 Review, during which we considered the direct application of aldrin and dieldrin to soil, the quantities of these chemicals used on the soil in Great Britain have undergone substantial reductions. There are very few data on the levels of camphechlor, chlordane, endrin, endosulfan, and heptachlor, in soils in Great Britain. They are not at present much used and in any case, with perhaps the exception of chlordane and heptachlor, they are much less persistent than aldrin/dieldrin and DDT/DDE. 94. Examination of freshwater fish and their avian predators in Great Britain has shown water to be a route of distribution of persistent pesticides. Residues _ of DDT in the natural waters in Great Britain that have been examined, including those in heavily treated areas, are generally well below the threshold concen- trations that would threaten survival or produce adverse effects on fish. The relatively high concentrations of dieldrin in some sewage effluents containing industrial waste might be an important element in their toxicity to fish and other aquatic organisms. Residues of organochlorine pesticides may also enter water mainly from careless disposal of containers and by direct deposition during crop spraying, and also by erosion or carriage by wind of treated soil from fields. Much of the DDT entering water in these ways is taken up by living organisms and metabolised. The processes in the ecosystem are not well understood, although it is clear that the net uptake of residues differs between species and that biodegradation occurs in both bacteria and fish. 95. Residues of organochlorine pesticides in marine organisms have been studied both to detect pesticides in the marine environment and to assess any changes in their levels. The uniformity of residues in eggs of sea birds make them particularly suitable for the latter purpose. Residues of organochlorine pesticides have been found in most of the specimens of marine organisms which have been analysed but the limited data on invertebrates and fish from British waters show that DDT and dieldrin residues are relatively low (mostly below 0-1 p.p.m.) [Appendix V (ii)]. More extensive data on the eggs of seabirds collected from colonies on the east and west coasts of Great Britain show higher levels of these chemicals (dieldrin: mostly within the range 0-1-3-0; DDE: mostly within the range 0-1-6-0 p.p.m.) [Appendix V (iti a)]. There is no evidence, however, to suggest that organochlorine compounds have had deleterious effects on British seabirds. Some animals that are important in marine food chains (e.g. the common brown shrimp) are known to be particularly sensitive to these substances but there is insufficient evidence to state whether organochlorine pesticides have affected marine invertebrates and fish. Nevertheless, the levels of insecticides in marine life in coastal waters are causing some concern. Limited studies in Britain suggest that pesticides mainly reach the sea by rivers. 96. Any environmental change which is widespread may affect man directly through his supplies of water, agricultural and other biological products, and indirectly through his opportunities for recreation and appreciation of nature. We have much evidence that DDT/TDE, aldrin/dieldrin, and to a lesser extent v5](https://iiif.wellcomecollection.org/image/b32173076_0027.jp2/full/800%2C/0/default.jpg)
