Background & Aims: Arsenic in drinking water is associated with hepatomegaly and death from liver cancer. However, confounding factors related to liver diseases have not been carefully studied. We examined associations between exposure of arsenic in drinking water and risk of hepatitis and cirrhosis, and the interaction with chronic viral hepatitis, in people living in the Lanyang Basin of northeastern Taiwan, where well water has an arsenic content that ranges from undetectable to 3590 μg/L. Methods: We tested blood samples from 4387 people who lived in arseniasis-endemic areas in northeastern Taiwan from 1991 through 1994 for hepatitis B virus DNA, hepatitis B surface antigen (HBsAg), and antibodies against hepatitis C virus (anti-HCV). We measured arsenic concentrations in well water and collected information on residents' histories of major chronic diseases. Reports of chronic hepatitis or cirrhosis were ascertained using the Taiwan National Health Insurance database. Reports of liver cancer were ascertained using the Taiwan National Cancer Registry. Results: Prevalence odds ratios in the overall study population for chronic hepatitis or cirrhosis for well water arsenic concentrations of ≤10 μg/L were 1.00 (reference), 0.93 for 10.1-49.9 μg/L (95% confidence interval [CI], 0.57-1.52), 1.24 for 50.0-99.9 μg/L (95% CI, 0.68-2.23), 0.98 for 100.0-299.9 (95% CI, 0.52-1.85), and 1.86 for ≥300.0 μg/L (95% CI, 1.08-3.20). Increasing levels of arsenic in drinking water were associated with increasing prevalence of chronic hepatitis or cirrhosis in residents who were seronegative for HBsAg and seronegative for anti-HCV, but not for seropositive for either HBsAg or anti-HCV. In individuals who were seropositive for HBsAg or anti-HCV, we observed an inverse association between hepatitis or cirrhosis and consumption of water with levels of arsenic ≥100.0 μg/L. Among participants who were seropositive for HBsAg or anti-HCV, consumption of water with levels of arsenic ≥100.0 μg/L was associated with a reduced risk of liver cancer (multivariate-adjusted hazard ratio, 0.29; 95% CI, 0.09-0.95; . P < .05). A higher proportion of individuals exposed to cumulative arsenic level >14,000 μg/L ×year were carriers of inactive hepatitis B virus (DNA <10,000 copies/mL) and were positive for HBsAg (60%) than individuals exposed to water below this arsenic level (35%). Conclusions: Concentrations of arsenic concentration in drinking water ≥300.0 μg/L significantly increase risk of hepatitis or cirrhosis in people without chronic viral hepatitis. However, in people with chronic viral hepatitis, levels of arsenic ≥100.0 μg/L in drinking water significantly reduce the risk of chronic hepatitis or cirrhosis.
- Environmental Factors
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