Asbestos and Drinking Water in Canada

Critical review of epidemiologic studies related to ingested asbestos.

“…Tables 1 and 2 show for gastrointestinal and nongastrointestinal cancer sites, respectively, a summary of results from the 13 studies. As shown here, one or more previous studies have found for males or females some association between asbestos in water supplies and cancer mortality (or incidence) for neoplasms of the esophagus (1,8,9), stomach (1,2,(6)(7)(8)(9), small intestine (13), colon a(Male, female) = association with ingested asbestos: + positive, 0 none, -negative, ns = not studied.…”

“…ns (+ 0) ns (+ -) a(Male, female) = association with ingested asbestos: + positive, 0 none, -negative, ns = not studied. (2,9,11,12), rectum (1), gallbladder (8,11), pancreas (1)(2)(3)5,6,8,9), peritoneum (8,9), bronchus, trachea, or lungs (1,(6)(7)(8), pleura (8,9), prostate (9,13), kidneys (8,11), brain or central nervous system (13), thyroid (13), and leukemia or aleukemia (11,13). The large variability in findings evident among the studies is matched by a considerable descrepancy in results for males and females within the 13 studies.…”

“…Occupation was a particularly important confounding variable in the studies conducted in Quebec (6,7), the Bay Area (8-10), and Connecticut (4,5), since a substantial number of males are employed in the various asbestos-related industries within these areas. The confounding effects of occupation are particularly evident in the two Quebec studies (6,7), where positive associations for lung and stomach cancer were consistently confined to males.…”

“…In 1982, the U.S. Environmental Protection Agency commissioned a critical review of the major epidemiologic studies that were germane to the question of possible adverse health effects caused by ingested asbestos. Thirteen published and unpublished studies conducted in five areas of the United States and Canada were included in the review (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). This paper presents the major findings and salient points of the more detailed review found elsewhere (14).…”

“…The two Connecticut studies of Harrington et al in 1978 (4) and Meigs et al in 1980 (5) were prompted by the possibility of studying reliable cancer incidence data over a 35year period through the Connecticut Tumor Registry and linking these data with information collected on asbestos-cement pipe studies done by the U.S. EPA. In Canada, the mortality studies of Wigle in 1977 (6) and Tbft et al in 1981 (7) were induced by the extent of the asbestos mining done in Quebec and by environmental surveys that revealed high concentrations of asbestos fibers in the drinking water supplies of certain cities. The San Francisco Bay Area cancer incidence studies of Kanarek et al in 1980 (8), Conforti et al in 1981 (9), and Tarter in 1981 (10) were motivated by the fact that several drinking water supplies come from aquifers or are stored in reservoirs that are exposed to serpentine, the parent rock form of chrysotile asbestos.…”