Renal effects of uranium in drinking water.

Abstract

Animal studies and small studies in humans have shown that uranium is nephrotoxic. However, more information about its renal effects in humans following chronic exposure through drinking water is required. We measured uranium concentrations in drinking water and urine in 325 persons who had used drilled wells for drinking water. We measured urine and serum concentrations of calcium, phosphate, glucose, albumin, creatinine, and beta-2-microglobulin to evaluate possible renal effects. The median uranium concentration in drinking water was 28 microg/L (interquartile range 6-135, max. 1,920 microg/L) and in urine 13 ng/mmol creatinine (2-75), resulting in the median daily uranium intake of 39 microg (7-224). Uranium concentration in urine was statistically significantly associated with increased fractional excretion of calcium and phosphate. Increase of uranium in urine by 1 microg/mmol creatinine increased fractional excretion of calcium by 1.5% [95% confidence interval (CI), 0.6-2.3], phosphate by 13% (1.4-25), and glucose excretion by 0.7 micromol/min (-0.4-1.8). Uranium concentrations in drinking water and daily intake of uranium were statistically significantly associated with calcium fractional excretion, but not with phosphate or glucose excretion. Uranium exposure was not associated with creatinine clearance or urinary albumin, which reflect glomerular function. In conclusion, uranium exposure is weakly associated with altered proximal tubulus function without a clear threshold, which suggests that even low uranium concentrations in drinking water can cause nephrotoxic effects. Despite chronic intake of water with high uranium concentration, we observed no effect on glomerular function. The clinical and public health relevance of the findings are not easily established, but our results suggest that the safe concentration of uranium in drinking water may be within the range of the proposed guideline values of 2-30 microg/L.

Geochemical evolution of uraniferous soda lakes in Eastern Mongolia

“…Uranium is toxic to the kidneys and can lead to an increased risk in cancer (Kurttio et al 2002). The EPA has determined the maximum contaminant level (MCL) for U at 0.12 µmol L -1 in drinking water (EPA 2003).…”

Potential Health Risks from Uranium in Home Well Water: An Investigation by the Apsaalooke (Crow) Tribal Research Group

“…Uranium exposure has been found to be positively associated with cytotoxicity biomarkers: increases in urinary albumin [8], glucose and calcium [2], β2-microglobulin and alkaline phosphatase [6]. Absorbed uranium not excreted via urine, accumulates primarily in the skeleton and kidney [4,43]. Exposure can increase cancer risk and lead to liver damage [44].…”

“…Uranium contamination of groundwater is being increasingly recognized as a health threat to rural residents relying on home wells for their drinking water, not only in communities with a legacy of mining [1], but also where naturally occurring uranium is the source of contamination [2][3][4][5]. However, most of the key studies of health effects from drinking uranium contaminated water have been conducted in other countries [4,[6][7][8].…”

“…However, most of the key studies of health effects from drinking uranium contaminated water have been conducted in other countries [4,[6][7][8]. In the United States, naturally occurring elevated uranium in groundwater has been identified as a widespread issue in Western states, as well as in scattered locations in Eastern states [2,9].…”

Biological monitoring of uranium exposure in south central Virginia

“…Uranium is a pervasive element in the Earth's crust and under the appropriate conditions can become soluble and contaminate a region's groundwater (Kurttio et al, 2002;Al-Jundi et al, 2004). When ingested at high levels over extended periods of time, uranium can cause functional and histological damage to the proximal tubule of the kidneys (CDC, 2001(CDC, -2002.…”