Reduced arsenic exposure improves health outcomes

In populations exposed to contaminated drinking water, reduced arsenic exposure appears to lower mortality from chronic diseases, including cancer and cardiovascular disease (CVD), as shown in a study conducted in Bangladesh.

The study included 10,977 adults (mean age 37 years, 57 percent female) with levels of well-water arsenic ranging from <1 to 864 µg/L (mean, 102 µg/L), which exceeded the Bangladesh standard of 50 µg/L. Urinary arsenic levels were measured up to five times per participant from 2000 to 2018.

A mitigation program was concurrently implemented, leading to a substantial reduction in arsenic exposure for some but not all participants. The mean urinary arsenic levels decreased from 283 to 132 µg/g creatinine between 2000 and 2018. Over a mean follow-up of 19.5 years, 1,401 deaths from chronic diseases occurred, including 256 from cancer and 730 from CVD.

Each interquartile range decrease in urinary arsenic (197 µg/g creatinine) correlated with 22-percent lower chronic disease mortality (adjusted hazard ratio [aHR], 0.78, 95 percent confidence interval [CI], 0.75–0.82), 20-percent lower cancer mortality (aHR, 0.80, 95 percent CI, 0.73–0.87), and 23-percent lower CVD mortality (aHR, 0.77, 95 percent CI, 0.73–0.81).

In time-varying Cox and restricted cubic spline analyses, larger reductions in arsenic exposure led to further reductions in mortality, while increases contributed to higher risk.

When compared with participants who had consistently high urinary arsenic levels (above the median of 199 µg/g creatinine), those whose levels declined below the median had a lower risk of mortality from chronic diseases (aHR, 0.46, 95 percent CI, 0.39–0.53), including cancer (aHR, 0.51, 95 percent CI, 0.35–0.73) and CVD (aHR, 0.43, 95 percent  CI, 0.34-0.53). This risk reduction was similar to that observed for those whose urinary arsenic levels stayed consistently below the median (aHR, 0.43-0.49).