Background: Nitrate is known to be a precursor in the endogenous formation of N-nitroso compounds which are thought to be associated with the development of brain tumours.
Methods: We conducted a population-based case-control study on the aetiology of primary brain tumours in adults in which the nitrate concentration in drinking water was investigated as a quantitative variable. For this purpose, an additional drinking water survey was performed.
Results: Analysis of 173 incident cases and 418 controls did not show any relationship between exposure to nitrate in drinking water and risk of developing primary brain tumours. We found mean nitrate concentrations of 15.98 mg/l (SD 15.61) in the drinking water history of the cases and of 16.16 mg/l (SD 15.72) for controls. In addition, we compared the quantitative history of nitrate contamination of the study participants to a semi-quantitative assessment by a stick method. Although we found good agreement between these methods we would recommend the use of detailed water surveys for retrospective studies on contaminants in drinking water.
Conclusion: The results suggest the absence of an association between nitrate levels in drinking water and the risk of brain tumours. However in order to draw definite conclusions quantitative prospective studies are needed.