Poster: Long-term mortality patterns in a residential cohort exposed to inorganic selenium in drinking water
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- Published on Thursday, 01 September 2016 12:10
Introduction
To date, limited epidemiologic evidence exists about the health effects of selenium exposure in drinking water. We investigated the relation between selenium levels in water and mortality in a setting constituting a natural experiment in an Italian municipality.
Methods
From 1974 to 1985, 2,065 residents consumed drinking water with selenium levels close to the European standard of 10 μg/l standard, in its the inorganic hexavalent form (selenate). Follow-up was conducted for the years 1986-2012, with the remaining 100,000 municipal residents, with comparable sociodemographic characteristics, as the comparison group.
Results
Overall mortality from all causes, cardiovascular disease and cancer showed little evidence of differences. However, we observed excess rate ratios for some site-specific cancers such as neoplasms of buccal cavity and pharynx, urinary organs, lymphohematopoietic tissue, melanoma, and two neurodegenerative diseases, Parkinson's disease and amyotrophic lateral sclerosis. Excess mortality in the exposed cohort for specific outcomes was concentrated in the period 1986-1997, and waned starting 10 years after the high exposure ended. We found lower mortality from breast cancer in females during the first period. When we extended the analysis also to residents who had been consuming the high-selenium drinking water for a shorter period, the increased mortality rate ratios were less pronounced.
Conclusions
Overall, the mortality patterns related to long-term exposure to inorganic hexavalent selenium through drinking water were unfavorable, consistent with adverse effects on risk of some site-specific cancers and neurodegenerative disease, thus suggesting the need to reassess current drinking water selenium standard.
