[Contamination of drinking water by nitrates: analysis of health risks].

Nitrate ground water contamination is a relatively frequent problem due to the massive use of fertilizers in agriculture. The health effects of contamination are due to the transformation of nitrates into nitrites in the G.I. tract and possibly the transformation of nitrites into nitrosamines in the stomach. The risk of methemoglobinemia in infants is due to nitrites contained in the water used to reconstitute milk for feeding. There are possible but unproven risks associated with the formation of nitrosamines, i.e. teratogenous and cancer risks. Drinking water standards are only based on the risk of methemoglobinemia, but given the present state of knowledge they appear to be safer in relation to the other potential risks. In the face of the increase in nitrates in ground water and the partially known risks, it appears necessary to try and prevent this type of contamination and inform the persons at risk, such as pregnant women and young mothers. It would also be useful to promote research on the effects of nitrates and nitrites on humans.