Nitrate in drinking water may increase risk of colorectal cancer shows a new study based on a PhD study in The dNmark alliance. Individual nitrate exposure was calculated for 2.7 million adults based on drinking water quality analyses at public waterworks and private wells between 1978 and 2011. For the main analyses, 1.7 million individuals with highest exposure assessment quality were included. Persons exposed to the highest level of drinking water nitrate had an Hazard ratio of 1.16 (95% CI: 1.08-1.25) for colorectal cancer compared with persons exposed to the lowest level. We found statistically significant increased risks at drinking water levels above 3.87 mg/L, well below the current drinking water standard of 50 mg/L. Our results add to the existing evidence suggesting increased CRC risk at drinking water nitrate concentrations below the current drinking water standard. A discussion on the adequacy of the drinking water standard in regards to chronic effects is warranted.

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