Introductory Remarks

Abstract

For many years following the introduction of the major classes of organic pesticides in the 1940s and early 1950s, what was known about the environmental behavior of these chemicals was largely gained in retrospect from empirical observations made after years of use. The dissipation rates of chemicals from treated areas, their movement in ecosystems and food chains, and the global circulation of the more persistent chemicals became known by painstaking analyses of samples from the environments of interest. This was difficult and expensive work, and it was often only after years of accumulated measurements that even crude generalizations could be reached regarding movement, persistence, and fate. The retrospective approach also left an unacceptable margin for error, and indeed some regrettable errors occurred in the introduction, use, and overuse of certain chemicals.