BLADDER-CANCER AND DRINKING-WATER - A POPULATION-BASED CASE-CONTROL STUDY IN WASHINGTON COUNTY, MARYLAND (UNITED-STATES)

A population-based case-control study was conducted in Washington Coun ty Maryland (United States) to explore the association between inciden t bladder cancer and exposure to drinking water from chlorinated surfa ce sources. Cancer cases were White residents, enumerated in a 1975 co unty census and reported to the Washington County Cancer Registry (n = 294) between 1975 and 1992. White controls, frequency matched by age (+/-5 years) and gender, were selected randomly from the census (n = 2 ,326). Households receiving municipal water, which generally derived f rom chlorinated surface waters, were treated as having 'high exposure' and all others, as 'low exposure.' Duration of exposure to type of dr inking water was based on length of residence in the census household prior to 1975. Odds ratios (OR) were calculated using logistic regress ion methods, adjusting for age, gender, tobacco use, and urbanicity. B ladder cancer risk was associated weakly in the general population wit h duration of exposure to municipal water The association was limited to those who had smoked cigarettes. In ever-smokers compared with neve r-smokers with low exposure, the adjusted ORs for bladder cancer risk with increasing exposure were 1.3, 1.4, 1.4, 1.7, 2.2, 2.8, respective ly, for 0, 1-10, 11-20, 21-30, 31-40, > 40 years' exposure duration. T he ORs in smokers were not diminished after adjusting for smoking hist ory and intensity.