Arsenic in drinking water may cause cancer decades after exposure

Oct. 24 (UPI) -- A new study reveals that inorganic arsenic, found naturally occurring in drinking water in some countries, can cause cancer decades after initial exposure ends.

Inorganic arsenic is naturally occurring at high levels in groundwater in many countries across the globe and can cause several types of cancer, including skin, kidney, lung and bladder cancer, among other diseases.

A recent study found the U.S. government's tighter limits on arsenic in drinking water since 2006 have resulted in a 17 percent decrease in the levels of arsenic found in individuals, according to public water systems with an estimated 200 fewer cases of lung and bladder cancer the following year.

In the study, published today in the Journal of the National Cancer Institute, researchers found that arsenic in drinking water has one of the longest dormancy periods of any carcinogen, possibly up to 40 years after exposure ended.

Researchers studied the affects of arsenic contamination in a water source in Antofagasta, Chile. The town experienced a sudden dramatic increase of arsenic in its drinking water in 1958. This increase was followed in 1970 by a dramatic reduction in exposure when an arsenic removal plant was installed.

By analyzing medical records and data from residents who lived in Antofagasta during that time period, researchers found that lung, bladder and kidney cancer mortality rates began to increase roughly 10 years after the spike in arsenic exposure occurred.

This increase in cancer mortality rates did not peak until nearly 20 years after exposure reduction started. Cancer mortality rates for lung, bladder and kidney cancers remained high for 40 years after the high arsenic exposure was halted.

Researchers believe these findings mean the incidence of arsenic-related diseases will remain high for years to come.