Calcium and magnesium in drinking water and risk of death from kidney cancer.

The possible association between the risk of kidney cancer development and the levels of calcium and magnesium in drinking water from municipal supplies was investigated in a matched cancer case-control study in Taiwan. All eligible kidney cancer deaths (1778 cases) of Taiwan residents from 1999 through 2008 were compared with deaths from other causes (1778 controls), and the levels of calcium and magnesium in drinking water of these residents were determined. Data on calcium and magnesium levels in drinking water throughout Taiwan were obtained from the Taiwan Water Supply Corporation (TWSC). The control group consisted of individuals who died from other causes, and the controls were pair-matched to the cancer cases by gender, year of birth, and year of death. The adjusted odd ratios for death attributed to kidney cancer for individuals with higher calcium levels in their drinking water, as compared to the lowest tertile, were 0.89 (95% CI = 0.72-1.11) and 0.78 (95% CI = 0.62-0.98), respectively. The adjusted odd ratios were not statistically significant for the relationship between magnesium levels in drinking water and kidney cancer development. The results of the present study demonstrate that there may be a significant protective effect of calcium intake from drinking water against the risk of death due to kidney cancer.