DDT and other organochlorines have very very low toxicity to humans and to most organisms, but they persist in the environment, so their toxic effects accumulate. In general there is an inverse relationship between short-term toxicity and environmental persistence, since the more effective a chemical entity is in killing insects, the more rapidly it may be degraded without loss of efficacy. The overlap with agricultural uses is also important. Many of the pesticides in use today for public health vector control were developed originally for agricultural purposes. The benefit to public health from inheriting these compounds comes at a price, however.
Agricultural uses are in much larger amounts than public health counterparts.
There have been many changes in the legislative and policy arena with respect to pesticides. In the early 1990s there were numerous publicly funded studies of the impact on human health and the environment from exposures to low levels of insecticides. The purpose of the act is to require that the EPA estimate and control the cumulative, aggregate exposure of children to insecticides from multiple sources and routes of exposure. Because many of the insecticides used on food crops are also used in public health vector control, however, there is concern that these uses will be affected by restrictions imposed in the FQPA context. This is a worthy goal and the United States position is supportive, as soon as effective, cost-effective and environmentally sound alternatives can be identified.