Halogenated hydrocarbons: past, present and near-future problems.

The fear that the wholesale entry of biocides into the environment would endanger the integrity of ecosystems was voiced in the 1940s by a small group of scientists. Subsequently, the population declines of seabirds and marine mammals, coupled with laboratory experiments showing negative impacts upon organisms through exposure to various pesticides, led many sovereign nations to ban or strongly regulate the use of such chemicals, as well as the industrially used polychlorinated biphenyls. Subsequently, and up to the present, the major concern has been with increasing usages of these materials in the tropics and Southern Hemisphere, the so-called "continental tilt". An International Mussel Watch Program has been proposed to assess potential damages to the ecosystems in these areas from increased pesticide usages. Near-future problems include identification of peaks of gas chromatograms that may represent anthropogenic toxins in the environment; the antagonistic or synergistic effects of already identified toxins; and the impacts of agricultural biocides upon mariculture.