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SCHOOL OF PUBLIC HEALTH DEPARTMENT OF EPIDEMIOLOCY
March 11, 1981
The Editor American Journal of Epidemiology 550 N. Broadway, Suite 201 Baltimore, Maryland 21205
RECtiv*.^
. MAR 1 3 1981
YMO/J.im.
109 OBSERVATORY STREET ANN ARBOR, MICHIGAN <8109
1 should like to draw your readers attention to a serious flaw in the paper by Kanarek and his colleagues (1), which invalidates their conclusion that there may be a causal connection between asbestos fibers in drinking water and cancer. In reaching this conclusion, they apparently ignored the well known association between cancer and population density. Review of Kanarek's doctoral thesis (though not of the paper in the Am. J. Epid.), shows that high fiber concentrations were concentrated in two main areas: San Francisco County (or City) and San Mateo County. The highest concentra tions were in San Mateo County. If digestive tract cancer death rates in San Francisco are compared with'the State of California, it is apparent that the rates are, as expected, higher in San Francisco (Table 1). This cannot, however, be attributed to the asbestos fibers in the drinking water. If New' York City is compared with New York State, similar differences are observed. Unlike San Francisco, New York City does not have high fiber counts in the drinking water (2). It is clear that the fiber/cancer association is con founded by the density of population factor. The importance of population density in assessing the relationship between asbestos fibers in drinking water and cancer has been well shown by Meigs and his colleagues (3, 4).
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REFERENCES
'I. Kanarek MS, Conforti PM, Jackson LA, et al. Asbestos in drinking water and cancer incidence in the San Francisco Bay area. Am J Epidemiol 1980;112:54-72.
2. United States Environmental Protection Agency. Millette OR, Clark PJ, Pansing MF. Exposure to asbestos from drinking water in the United States. EPA 7979;600/l-79-028.
3. Harrington JM, Craun GF, Meigs 0W, et al. An investigation of the use of asbestos cement pipe for public water supply and the incidence of gastrointestinal cancer in Connecticut, 1935-1973. Am 0 Epi.demiol 1978; 107:96-103.
4. Meigs JW, Walter SD, Heston OF, et al. Asbestos cement pipe and cancer in Connecticut, 1955-1974. 0 Env Hlth 1980;42:187-191.
5. Severson RK. A study of the effects of asbestos in drinking water on cancer incidence in the Puget Sound Region, thesis for M.S. degree. Biomathematics Group, University of Washington, Seattle, Washington, 1979.
Ian T. T. Higgins The University of Michigan School of Public Health Department of Epidemiology Ann Arbor, Michigan
CAP CO JEN 0010290
Comparison o f Age A djusted Rates f o r W hite Men and Women 1950 to 1969 fo r Various D igestive T ract Cancers in
San Francisco County (= C ity ) and New York C ity W ith the States o f C a lifo rn ia and New York and the U nited S tates
;on TJ, McKay FW. U.S. Cancer M o r ta lity by County: 1950-1969.
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