MPH

thesisThe objective of this research was to test the hypothesis that there is a positive association between the use of asbestos-cement piping for drinking water supplies and the incidence of gastrointestinal and kidney cancer. Fourteen Utah communities were identified that use predominately asbestos-cement piping in the drinking water supplies for twenty years or more. These were compared with 27 Utah communities that had never use asbestos-cement piping. Using cancer incidence data from the Utah Cancer Registry, cancer incidence was tabulated for 11 cancer sites for the years 1967 to 1976. These sites included the stomach, small intestine, colon, rectum, peritoneum, gall bladder, pancreas, kidney, leukemia, lymphoma and melanoma (the later three being control sites). Observed and expected ratios were calculated from incidence data and probability values were generated using the Mantel-Haenszel Chi Square Statistical Procedure. Observed cancer incidence of several cancer sites in study communities were substantially increased over expected values. These included cancer of the kidney in males (31 cases observed, 16 expected) with and SIR of 192 (P = 0.0085). Cancer of the kidney in both sexes combined (42 observed, 25 expected) with an SIR of 163 (P=0.0188); leukemia in both sexes combined (83 observed, 58 expected) with an SIR of 163 (P=0.0136). Cancer of the gall bladder in females also showed an increased observed incidence in study communities (13 cases observed, 6 cases expected). The SIR in this instance was 215 with the P-value close to being statistically significant (P=0.0532). Also, 22 cases of gall bladder cancer were observed for both sexes combined with 13 cases were expected (SIE=142, P=0.0556). The results of this study are inconclusive, especially in light of nonsignificant results in cancer of the cancers of the stomach, small intestine, rectum and peritoneum, and expected value in cancer of the colon and the positive association in leukemia (a site not implicated with asbestos-exposure). The small population studied and relatively low number of cancer cases could account for the significant levels noted in the various sites. Several biases in the study were also noted, including the inability to control for emigration-immigration patter, the unknown quantity of asbestos-cement piping in the exposed communities, the unknown amount of fibers actually in the drinking water and the inability to control for such variables as occupation, diet and smoking habits