Drinking water may contain arsenic resulting from natural deposits in the earth or resulting from agricultural or industrial contamination. Exposure to high levels of arsenic in drinking water has been linked to bladder cancer. In addition, bladder cancer patients who have been exposed to arsenic may experience more aggressive cancer.
In order to determine the long-term effects of exposure to arsenic in drinking water on bladder cancer, researchers evaluated a region in northern Chile where 400,000 people were exposed to extremely high levels of arsenic in their drinking water between 1955 and 1989, at which time arsenic levels were controlled. The researchers determined arsenic levels as well as hospitalizations and deaths related to bladder cancer in this region and compared them to the rest of Chile for the last 60 years.
Despite control of arsenic levels in the drinking water in 1989, there has been a trend toward an increase in the death rate due to bladder cancer for the last 20 years for the arsenic-exposed population compared with the rest of the country. In addition, the researchers reported that arsenic-exposed bladder cancer patients died at a younger age compared with bladder cancer patients in Chile who were not exposed to arsenic.
The researchers concluded that “exposure to arsenic is related to high mortality rates and a significant need for bladder cancer health care even twenty years after controlling arsenic levels in drinking water.” Education initiatives to inform individuals who have been exposed to high levels of arsenic in their drinking water are important, even years after the toxin has been controlled.
 Lopez JF, Fernández M, Westendarp M, Vivaldi B, and Coz LF. Long-term impact of arsenic in drinking water on bladder cancer mortality and health care twenty years after end of exposure. Presented at the 105th Annual Scientific Meeting of the American Urological Association (AUA), San Francisco, CA, May 29-June 3, 2010. Abstract 120.