Uranium Gastrointestinal Absorption in Humans: A Chronic Exposure Study

To estimate gastrointestinal(GI) absorption(f1) of uranium in humans where exposure is through chronic ingestion, a study was conducted of a rural community in Canada where the residents relied on drilled private wells that delivered water with uranium levels ranging from 2 to 780 μg/L. A comparison was made with an urban centre whose drinking water was supplied by a municipal system and had a uranium content of <1 μg/L. Fifty subjects participated in the study. To estimate daily intake from both water and food as accurately as possible, the duplicate diet approach was used where individuals collected and set aside a duplicate amount of beverage and food that they had ingested over a three-day period. Total intakes from water and through food varied from 0.03 to 570 ug/day. The f1 values obtained ranged from 0.001 to 0.06, with a mean of 0.012 and a median of 0.009. Variation of f1 values correlated poorly with gender, years of residence and age at the time of study. Contrary to expectations, the values were found to be in reasonable agreement with values obtained in previous human studies whether the pattern of exposure was acute or chronic.