Cancer risks from arsenic in drinking water.

Area of Science:

• Environmental Health
• Toxicology
• Cancer Research

Background:

• Arsenic exposure from water and medicines is a known cause of skin cancer.
• Evidence suggests arsenic also contributes to liver, lung, kidney, and bladder cancers.
• Population cancer risks from U.S. water arsenic may be comparable to environmental tobacco smoke and indoor radon.

Purpose of the Study:

• To assess the population cancer risks associated with arsenic in U.S. water supplies.
• To establish dose-response relationships between arsenic concentration and cancer risk.

Main Methods:

• Utilized large population studies from Taiwan with high well water arsenic levels (170-800 µg/L).
• Extrapolated findings to estimate cancer risks at current U.S. Environmental Protection Agency (EPA) standards and average U.S. exposure levels.

Main Results:

• At the EPA standard of 50 µg/L, lifetime cancer risk (liver, lung, kidney, bladder) from drinking 1 L/day could be 13 per 1000 persons.
• Over 350,000 people in the U.S. may receive water with >50 µg/L arsenic; >2.5 million may receive water with >25 µg/L.
• Estimated average U.S. lifetime cancer risk is approximately 1 per 1000 persons.

Conclusions:

• Arsenic in drinking water poses significant cancer risks beyond skin cancer.
• Current U.S. water arsenic levels may present substantial public health risks.
• Measures to reduce arsenic levels in water supplies warrant consideration pending further research.