Incidence of transitional cell carcinoma and arsenic in drinking water: A follow-up study of 8,102 residents in an arseniasis-endemic area in northeastern Taiwan

A significant association between ingested arsenic and bladder cancer has b een reported in an arseniasis-endemic area in southwestern Taiwan, where ma ny households share only a few wells in their villages. In another arsenias is-endemic area in northeastern Taiwan, each household has its own well for obtaining drinking water. In 1991-1994, the authors examined risk of trans itional cell carcinoma (TCC) in relation to ingested arsenic in a cohort of 8,102 residents in northeastern Taiwan. Estimation of each study subject's individual exposure to inorganic arsenic was based on the arsenic concentr ation in his or her own well water, which was determined by hydride generat ion combined with atomic absorption spectrometry Information on duration of consumption of the well water was obtained through standardized questionna ire interviews. The occurrence of urinary tract cancers was ascertained by follow-up interview and by data linkage with community hospital records, th e national death certification profile, and the cancer registry profile. Co x proportional hazards regression analysis was used to estimate multivariat e-adjusted relative risks and 95% confidence intervals. There was a signifi cantly increased incidence of urinary cancers for the study cohort compared with the general population in Taiwan (standardized incidence ratio = 2.05 ; 95% confidence interval (CI): 1.22, 3.24). A significant dose-response re lation between risk of cancers of the urinary organs. especially TCC, and i ndices of arsenic exposure was observed after adjustment for age, sex, and cigarette smoking. The multivariate-adjusted relative risks of developing T CC were 1.9, 8.2, and 15.3 for arsenic concentrations of 10.1-50.0, 50.1-10 0, and >100 mug/liter, respectively, compared with the referent level of le ss than or equal to 10.0 mug/liter.