Arsenic exposure deaths high decades later

SANTIAGO, Chile, June 14 (UPI) -- Death rates from lung and bladder cancer remain high decades after residents in northern Chile were exposed to high levels of arsenic in drinking water.

That the mortality risks remain elevated long after exposure to high levels of arsenic ended indicates a clear pattern of latency in health effects that had not been known before, according to the study published in the Journal of the National Cancer Institute.

Principal investigator Allan Smith, of the University of California at Berkeley's School of Public Health, and lead author Guillermo Marshall, of Pontificia University Catolica in Chile, found that until 1958, when government officials sought out additional sources of water, a northern province in Chile got its water from arsenic-contaminated rivers originating in the Andes mountains that contained 90 micrograms per liter of inorganic arsenic.

Unfortunately, the supplemental water provided by the government came from the Toconce and Holajar rivers, which between 1958 and 1970 averaged 870 micrograms per liter of inorganic arsenic, nearly 90 times higher than today's World Health Organization standard.

Between 1992 and 1994, more than 20 years after the arsenic levels began dropping, combined lung and bladder cancer death rates were 153 per 100,000 men and 50 per 100,000 women in the region -- 2.5 to nearly three times higher than their counterparts in another part of Chile, the study found.