Aquatic ecosystems: Harbingers of endocrine disruption

In the 1950s, top predator wildlife populations in aquatic systems signaled disturbances in their environment through a series of adverse health effec ts. Bioaccumulation in plant and animal tissue, with accompanying biomagnif ication in the animals that consumed these tissues, led to extremely high c oncentrations of some synthetic chemicals in top predator species in aquati c trophic systems. By the late 1960s technological improvements in analytic al chemistry allowed for associations between a suite of persistent chemica ls in the tissues of affected animals and the hearth status of wildlife pop ulations. This group of contaminants, the organochlorine chemicals, and the ir effects on wildlife provided the insight into the phenomenon called "end ocrine disruption," where certain synthetic chemicals can interfere with th e natural chemical messengers that control normal development and function. Because the effects were most often expressed in offspring that were expos ed via maternal transfer before, or soon after, birth or hatching, the dama ge in wildlife was often overlooked. Forensic field research over the past decade has revealed far wider damage than heretofore had been realized. In addition, interest in chemicals that can interfere with the endocrine syste m has expanded to include natural plant and animal compounds, nonhalogenate d compounds, and other large-volume chemicals (>4.5 x 10(6) kg/yr) that had been considered benign until only recently. Concern about the effects of c ontaminants in wildlife and their implications for human health led to the discovery that human offspring are experiencing developmental and neurologi cal damage. These effects have been associated with exposure to certain org anochlorine chemicals and their co-contaminants at, or slightly above, ambi ent concentrations in the industrialized world.