Researchers from Dartmouth Medical School have reported that patients with bladder cancer with high arsenic exposure had a lower survival rate than patients with bladder cancer without a high arsenic exposure. The details of this study appeared in an early online publication in the World Journal of Urology on October 16, 2009.[1]

Exposure to high levels of arsenic in drinking water can cause an increase in a variety of cancers and skin lesions. In the United States, most arsenic-contaminated drinking water sources would be classified as low level with unproven adverse health effects. The current debate in the United States concerns the cost-effectiveness of reducing low levels of exposure to arsenic in drinking water. However, it may be prudent to consider some of the known effects of arsenic exposure. Arsenic is a poison and a known carcinogen for skin cancers and bladder cancers, but the exact mechanism by which arsenic causes cancer is unknown. High levels of arsenic occur naturally in some drinking water in the United States and other countries.

Researchers in Argentina, Chile, and the United States evaluated chromosomal abnormalities in bladder cancers from patients chronically exposed to different levels of arsenic in their drinking water.[2] They found that arsenic-associated bladder cancers demonstrated more chromosomal abnormalities than bladder cancers not associated with arsenic. These researchers also suggested that arsenic-induced bladder cancers were more aggressive than other bladder cancers.

The current study examined the relationship between arsenic exposure and bladder cancer mortality in 832 patients in the U.S. Northeast. These authors evaluated arsenic exposure in drinking water and concentrations of arsenic in toenails. They observed that patients with high exposure to arsenic had a 50% reduction in survival compared with those with low arsenic exposure. This association between high arsenic exposure and survival was seen predominantly in smokers.

Comments: These data are consistent with the study from Argentina and Chile, suggesting that patients with arsenic-induced bladder cancer have a more virulent disease. The levels of arsenic in the drinking water in Chile and Argentina are much greater than those found in most studies in the United States, but the current study suggests that arsenic, at levels found in U.S. drinking water, may have adverse clinical significance.

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