GLOBAL PUBLIC HEALTH THREAT FROM ARSENIC IN DRINKING WATER: CURRENT EPIDEMIOLOGICAL EVIDENCE AND FUTURE DIRECTION (Invited Presentation)

Arsenic is naturally present at high levels in the groundwater of many countries, including parts of the US, and arsenic exposure from drinking water poses the greatest threat to public health. Arsenic exposure is known to increase the risk of many diseases, including lung, bladder, laryngeal, and kidney cancers, as well as non-cancer diseases such as chronic renal failure, chronic respiratory disease, and diabetes. Many efforts have been made to reduce arsenic exposure, but with long latency patterns, increased risks continue for many years. Especially, the exposure of fetuses during pregnancy and children results in major increase in mortality in adults which continues even 40 years after high arsenic exposures have been reduced, based on data from Chile. The association of age at arsenic exposure and mortality was investigated in Antofagasta, Chile, 30–40 years after a distinct period of very high water arsenic concentrations (average 860 μg/L) (1958–1970). A remarkable relationship with age at first exposure was found for bronchiectasis, with increased risk in adults 30–40 years after exposure in utero and during early life. Increased standard mortality ratios (SMRs) for lung, bladder, and laryngeal cancer were evident for exposures starting at all ages. In a Bangladesh study, we found the children exposed to high concentrations of arsenic in drinking water in utero and early childhood (average 436 µg/L) had marked increases in chronic respiratory symptoms. In the US, public water systems are regulated with a current drinking water standard for arsenic at 10 μg/L. However, private well water is not regulated and 14% of the population people are using private wells, and there are 2 million people potentially exposed to arsenic over 10 μg/L. For example, in Texas, the southern High Plains and Gulf Coast areas have high levels of arsenic in the groundwater over the Maximum Contamination Level for drinking water, posing the high risk of health issues to 351,224 residents. However, studies have shown even low-level arsenic below the current standard level still increases the risk of diseases. An ecologic study conducted in Iowa, where exposure levels are low, but duration of exposure can be long, showed a significant dose-dependent association between low-level arsenic exposure (1.08-18.6 μg/L) and prostate cancer and suggested that 10 μg/L is not protective for human health. In conclusion, the long-term intervention strategies for the exposed and stricter regulation should be considered to protect public health.