Ingested inorganic arsenic, cigarettes smoking and risk of urinary cancer in Taiwan

Our previous studies using data from either southwestern or northeastern arseniasis endemic areas from Taiwan consistently demonstrated an increased risk of urinary cancer, especially urothelial carcinoma, in a dose-response fashion. We conducted analyses to elucidate whether these is an interaction between cigarette smoking and long term arsenic exposure using the information from residents in arseniasis endemic area in northeastern Taiwan. With an average of 12 years follow-up, there were 45 incident urinary cancer cases. The interaction term between arsenic concentration and cigarette smoking status was significant for urinary cancer (p = 0.0222), but not for urothelial carcinoma (p = 0.1085). When combining arsenic concentration and pack-years of cigarettes smoking, the highest relative risk were those who were exposed to $100 μg/L of arsenic and smoked <25 pack-years of cigarettes (RR = 10.72, 95% CI, 1.75-65.5). For residents exposed to the same level of arsenic and were heavier smokers, the relative risk was 9.53 (95% CI, 1.28-54.2). Similar trends were found when restricted to urothelial carcinoma, with all risk estimates even higher.