gaps; studies that combine data from multiple sites; long-term surveillance of populations that have been permanently relocated because of exposure to hazardous-waste releases in their original communities; state-based surveillance, usually conducted as ecologic studies that link existing data bases such as birth weight, birth defects, and cancer incidence to geographic distributions of environmental contamination; surveillance of workers employed in the cleanup of hazardous waste; and development of a public health reporting and surveillance system for hazardous-waste material emergencies (ATSDR, 1990b).
ATSDR also is investigating the use of “sentinel health events” as additional indicators of environmental contamination. The concept was first developed for public health surveillance of morbidity and mortality that results from preventable causes, such as deaths from infectious diseases that are preventable by immunization or chronic obstructive pulmonary disease that results from cigarette smoking (Rutstein et al., 1983). Such indicators are most useful when they identify causes of morbidity and mortality that are uniquely or predominantly associated with specific and preventable exposures. For example, mesothelioma is almost exclusively associated with exposure to asbestos fibers, and hepatic angiosarcoma is predominantly associated with exposure to vinyl chloride.
Environmental sentinel health events are designed to serve as warning signals of particular environmental exposures, using existing data systems such as vital records, hospital discharge data, and tumor registries. Some illnesses, such as methemoglobinemia that results from excessive amounts of nitrate in water, indicate hazardous environmental exposure even when they occur as single cases. Other diseases indicate potential environmental exposures when they occur at elevated rates among larger populations, such as bladder cancer among nonsmokers or chronic respiratory disease among children. The further development and application of this approach to environmental surveillance holds particular promise for the epidemiologic investigation of populations exposed to hazardous wastes.
Although ATSDR is vigorously pursuing the development of an intramural research program in environmental epidemiology and has extended this to include a number of states through cooperative agreements, in FY90 ATSDR's total budget for programs that assess hazardous-waste sites was $15.8 million (J. Andrews, ATSDR, personal communication, 1990). The National Institute of Environmental Health Sciences (NIEHS), a sister agency within the U.S. Public Health Service, also receives Superfund monies to support a basic research program in ecology, engineering, and hydrogeology integrated with bio-