This chapter reviews the health effects linked to exposure to contaminants in soil or food, other than those resulting from direct pesticide applications to crops. These include home gardening in contaminated soil, some exposures involving work with soil, and consumption of fish from contaminated waters. Although heavily exposed persons could have a high risk of disease, in general, small numbers of persons have been exposed directly or indirectly through ingestion of foods that have absorbed contaminants from soil or water, or through avocational or vocational exposures to contaminated materials. Studies of soil and food contamination usually encompass many individuals with relatively low or negligible exposure in the “exposed” group. Accordingly, low estimates of risk, as well as low attributable risks in the general population, can be discerned, although some highly exposed individuals can incur serious risks, especially when contaminated soil has been used as topsoil in building construction.
In accordance with Figure 1-1 of this report, animal studies on the consumption of contaminated fish are relevant to this discussion. Animals experimentally exposed to fish contaminated with polychlorinated biphenyl (PCB) congeners and other pollutants display a range of neurologic, immunologic, and enzymatic impairments. Hertzler (1990) reports that rats fed different concentrations of Lake Ontario salmon consistently evidence lower activity, rearing, and other behaviors, when compared to rats fed ocean salmon or rat chow. Studies of the levels of two common pesticides, Mirex and PCBs in rat brain and fish, found dose-related neurobehavioral effects. Cleland et al. (1989) similarly report that mice fed diets of Lake Ontario salmon had reduced immune function, including lowered immunoglobulin, which correlated with elevated PCB levels in the ingested salmon. An earlier study by Cleland et al. (1987) produced both hepatomegaly and suppression of important detoxifying enzymes in mice fed Lake Ontario coho salmon, compared to unexposed control mice.
Regarding environmental contamination of finfish and shellfish and other freshwater species, inadequate harvest management and control is in effect for environmental chemicals such as mercury, lead, cadmium, PCBs, dioxin, and pesticides, according to a recent report of the Institute of Medicine (1991). Regional agricultural or industrial pollution varies considerably and can be substantial in some small areas. One fifth of the fish and shellfish eaten in the United States comes from recreational or subsistence fishing, and is not sub-