hazardous-waste studies are smaller scale comparisons of adjacent counties or Zip Codes. Although such indicators are relatively crude and insensitive, they have been used to compare mortality data in populations close to or more distant from point sources of emissions, such as smelters that emit arsenic. In one study in Sweden, Pershagen (1985) found significant small-scale regional differences in lung cancer rates that could be attributable to such air emissions, and Lloyd et al. (1984) suggest that changes in sex ratio of births might also be found in a similar polluted environment. In general, area studies of health patterns linked to hazardous-waste sites have been too small to permit significant mortality comparisons. Moreover, exposures in such studies certainly involve multiple routes and can induce multiple adverse effects.

At least one cross-sectional ecological study (Lave and Seskin, 1977) found associations between long-term airborne exposures to sulfate pollution and age-, race-, and sex-adjusted mortality rates in urban areas of the U.S. These studies were criticized because of their highly ecological nature and poor control for other factors that could explain geographic variations in mortality rates. Subsequent studies (Lipfert, 1980; Chappie and Lave, 1982) obtained better data on other relevant risk factors, such as smoking and industrial employment. A more recent study by Griffith et al. (1989) reports an association between the presence of hazardous-waste sites in counties in the U.S. and excess cancer mortality. No effort was made to control for cigarette sales by county, employment in high-risk industries, or presence of industrial facilities that might emit carcinogens. Without these controls, such studies may be of limited value.

Vinyl chloride (VC) is a substance found at many hazardous-waste sites (see Appendix 3-A of this volume). In the 1970s, several epidemiologic investigations indicated that occupational exposure to VC was associated with an increased risk of angiosarcoma of the liver as well as cancer of other sites (Infante, 1981). In addition, epidemiologic study and case reports associated angiosarcoma of the liver with community exposure to VC. Brady et al. (1977) reported the results of a New York State case control study of 26 confirmed cases of angiosarcoma of the liver. Controls were comprised of individuals who had an internal malignant tumor other than primary liver cancer; they were matched with cases on the basis of age at diagnosis, race, sex, place of residence and vital status. Of 10 women with angiosarcoma of the liver, five lived within one mile of VC polymerization or fabrication plants (1 case lived within 1700 feet for 62 years; 4 cases lived from 500 to 4500 feet for 8 to 27 years), whereas none of their matched controls lived as close. According to the au-



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