waste incinerators, similar patterns of exposure may also have occurred. ATSDR issued a health advisory for the Caldwell incinerator, located in Lenore, North Carolina, based on a health assessment that found significant elevations of blood lead both in workers at the small incinerator and in residents of the community (ATSDR, 1990). In addition, more than half of the 80 workers had advanced neuropathies. Although this advisory has not been published in the literature that this report generally reviews, we cite it here as an illustration of the fact that such community effects have been documented. Soil lead levels in these circumstances can be an important reservoir for continuous re-exposure of the population.
Under many circumstances, the route of exposure is unclear. This applies to potential chemical exposures from many toxic-waste sites. One example is a study of residents near a landfill site in Hamilton Ontario, used from the early 1950s until 1980 for disposal of solid and liquid industrial wastes (Hertzman et al., 1987). The study of residents was preceded by a study of workers to help focus on relevant symptomatology. Both groups exhibited mood, narcotic, skin, and respiratory disorders. Although perception of exposure could explain the results of the study, it was the authors' conclusion that the adverse effects seen were more likely than not the result of chemical exposure.
Where residents near hazardous-waste sites have engaged in home gardening, residues in their foods need to be carefully evaluated. In order to evaluate these residues, background levels need to be determined. The Food and Drug Administration (FDA) Market Basket Survey consists of four samples of grocery products purchased annually in each of four regions of the U.S., and prepared for eating. In the Total Diet Study, 234 different food items are collected and analyzed four times each year in three cities in each of four regions. Analyses are conducted on chemical residues in this market basket, in some cases evaluating contaminants in samples as small as three raisins, and extrapolated to the general food supply. Comparisons are made between the residues measured and the Acceptable Daily Intakes (ADI) established for individual contaminants. The ADI is established by panels of scientific experts at the FDA and other international organizations and are estimated to be the daily amount of a chemical that can be safely