Drinking water arsenic in northern chile: high cancer risks 40 years after exposure cessation.

Background: Millions of people worldwide are exposed to arsenic-contaminated water. In the largest city in northern Chile (Antofagasta), more than 250,000 people were exposed to high arsenic drinking water concentrations from 1958 until 1970 when a water treatment plant was installed. Because of its unique geology, limited water sources, and good historical records, lifetime exposure and long-term latency patterns can be assessed in this area with better accuracy than in other arsenic-exposed areas worldwide.