Arsenic has been well documented as the major risk factor for development of blackfoot disease (BFD), a unique
peripheral vascular disease that was once endemic to the southwestern coast of Taiwan, where residents imbibed artesian well water containing high concentrations of
arsenic for more than 50yr. Long-term
arsenic exposure has also been reported to be associated with increased incidence of
liver cancer in a dose-responsive manner. A tap-water supply system was implemented in the early 1960s in the BFD endemic areas. Artesian well water was no longer used for drinking and cooking after the mid-1970s. The objective of this study was to examine whether
liver cancer mortality rates were altered after the consumption of high-
arsenic artesian well water ceased and, if so, when the reduction occurred. Standardized mortality ratios (SMRs) for
liver cancer were calculated for the BFD endemic area for the years 1971-2000. Cumulative-sum techniques were used to detect the occurrence of changes in the SMRs. The study results show that mortality from
liver cancer in females declined starting 9yr after the cessation of consumption of high-
arsenic artesian well water. However, data show fluctuations in male
liver cancer mortality rates. Based on the reversibility criterion, the association between
arsenic exposure and
liver cancer mortality is likely to be causal for females but not in males.