Endocrine-Modulating Substances in the Environment: The Wildlife Connection

Abstract

Historical observations, first publicized in Rachel Carson's Silent Spring, demonstrated biological effects of persistent, bioaccumulative pollutants on wildlife. These effects included disruption of reproduction and, in some situations, responses mediated through the endocrine system. The substances that caused these effects were mainly highly chlorinated halocarbon compounds, such as DDT (and metabolites), other organochlorine pesticides, polychlori-nated biphenyls, poly chlorinated dibenzo-p-dioxins, and poly chlorinated dibenzofurans. In contrast, responses of fish to industrial discharges and pulp mill effluents have implicated more water-soluble compounds. Characterizations of wildlife exposures require consideration of temporal and spatial factors that they exacerbate or ameliorate responses. Likewise, effects of endocrine-modulating substances m ay appear at subsequent stages of development, not at the time of exposure. Consistent with the declines in environmental concentrations of persistent, bioaccumulative substances, populations of several wild bird species, including bald eagles, cormorants, herring gulls, and Caspian terns, have increased, recovering from declines noted in previously polluted areas during the 1960s and 1970s.