Report of Committee on Persistent Pesticides, Division of Biology and Agriculture, National Research Council to U.S. Department of Agriculture (1969) / Chapter Skim
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Pages 6-18
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From page 6... ...
- 6 for the good of mankind, it is conceivable that society may wish to put restraints on the use of certain pesticides regardless of economic considerations and crop quality. PRODUCTION AND USE OF PESTICIDES The worldwide increase in the use of persistent pesticidal chemicals is cause for concern, and, if trends continue, problems of environmental contamination by such chemicals may become more serious.
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- 7 for fungicides. These two groups do not contribute importantly to the problems commonly associated with persistent pesticides.
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- 8 Health Understanding of the toxicology of persistent pesticide residues is increasing steadily insofar as warmblooded animals are concerned. However, extrapolation of toxicological data from test animals to man remains uncertain.
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- 9 These studies were conducted to measure chronic effects, including, in most cases, effects on reproduction and carcinogenicity potentials. Studies of aldrin, dieldrin, endrin, heptachlor, heptachlor epoxide, and chlordane in animals have not shown that these chemicals produce significant toxicological effects at dosage levels under 1.0 ppm in the diet, although they produce reversible "adaptive responses" of the liver at a level of 1.0 ppm or higher.
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- 10 From this statement of the need for information about possible effects of long-term exposure, it does not necessarily follow that such exposure would be deleterious to health. The point is that definite information is lacking.
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- 11 Some pesticides, notably DDT, are so widely distributed that few, if any, food-producing areas are free of their residues. Thus, most foods contain measurable traces of such residues.
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- 12 thickness and thus to increase premature breakage of the eggs. Certain organochlorine pesticides are hazardous to many species because they are readily absorbed, are stored in body lipids, and are slowly metabolized and excreted.
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- 13 Research on natural populations is a difficult, undeveloped field that is poorly supported at the national level. Methods of field study are imprecise, yet they must be used for populations that fluctuate continually.
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- 14 reflect only a relatively small circulating store concentrated in the biota. Scattered measurements of DDT in rain and the atmosphere emphasize the need to know what is in the atmosphere.
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- 15 through enzymatic processes that may result in a complete conversion of organic chemicals to simple, well-known products. In other instances, biological degradation yields organic compounds that are normal constituents of living organisms.
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- 16 Evidence suggests that general environmental contamination by the chemicals is more likely to occur from wind and water erosion of the soil than through leaching into ground water. One means of transport is the sorption of pesticides to soil particles, especially the fine silt and organic fractions, both at the site of application and in the aquatic environment.
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- 17 Release of short-lived material is a different matter. If such a material is released and is later found to be hazardous, the store in the biosphere will be rapidly reduced once the use of the material is discontinued.
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- 18 environmental conditions. Evaluation of the overall rate of disappearance from the biosphere requires quantitative knowledge concerning (1)
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