Epidemiologic approaches to persons with exposures to waste chemicals.

Evaluation of disease in populations exposed to hazardous waste dumps requires: documentation of the chemicals in a dump; assessment of the materials released from the dump into environmental media; tracing of the probable routes of human exposure (groundwater, air, direct contact, or occupational); development, when possible, of individual exposure estimates and/or direct biological assessment of absorption; precise definition of the subpopulations at highest risk of exposure; and the employment of specific and sensitive health outcome indicators. Demonstration of dose-response relationships between chemical exposure and disease provides the most compelling evidence for a chemical etiology of illness in exposed populations. Interpretation of apparently negative data must be cautious, given the small size of most high-risk populations and the usual brevity of exposures.