Arsenic Exposure may Increase Mortality from Tuberculosis
Allan H. Smith, M.D., Ph.D.
University of California Berkeley
NIEHS Grants P42ES004705 and R01ES010033
According to scientists supported by NIEHS and the Superfund Research Program, increased mortality from pulmonary tuberculosis could be yet another serious outcome from exposure to arsenic in drinking water. These findings are from an ongoing study in Chile and if verified, they will have important public health implications, since some of the largest arsenic-exposed populations are in developing countries with widespread tuberculosis.
Tuberculosis is a major public health problem worldwide causing over 2 million deaths in the last year alone and 9 million new infections. There is more tuberculosis today than at any other time in history. Increased susceptibility to tuberculosis has been identified with a variety of other diseases and exposures. Likewise, arsenic in drinking water is a serious public health problem affecting many countries, with millions of people throughout the world exposed. Marked increases in mortality from many different causes have been established resulting from prolonged consumption of arsenic-contaminated water.
The research team has been conducting research on arsenic exposure in Chile for some time. Their findings present the first evidence relating arsenic exposure to tuberculosis. They compared mortality rate ratios with time patterns of arsenic exposure, which increased abruptly in 1958 in a specific region in Chile and then started declining in 1971. Tuberculosis mortality rate ratios in men started increasing in 1968, 10 years after high arsenic exposure commenced. The peak male 5-year mortality rate ratio occurred during 1982-1986. The findings are biologically plausible in view of evidence that arsenic is an immunosuppressant and also a cause of chronic lung disease.
The research team concludes that if arsenic in water increases mortality from tuberculosis, then particular attention will be needed to ensure that patients with tuberculosis are not drinking arsenic-contaminated water. Confirmatory evidence is needed from other arsenic-exposed populations.
Citation: Smith AH, Marshall G, Yuan Y, Liaw J, Ferreccio C, Steinmaus C. Evidence from Chile that arsenic in drinking water may increase mortality from pulmonary tuberculosis. Am J Epidemiol. 2011 Feb 15;173(4):414-20.
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