Nitrate levels in drinking water and their impact on the risk of developing gynecological diseases and adverse pregnancy outcomes

Nitrate is a nitrogen oxoanion formed by loss of a proton from nitric acid. It is an important source of nitrogen which is essential for protein formation. Regular levels of nitrate in the environment do not exceed 2-5 mg/L. Fertilizers, herbicides and pesticides increase, however, the amount of nitrate in drinking water. In 2011 the World Health Organization (WHO) has issued a revised document on nitrate and nitrite levels in drinking water to help establish a common guideline that will help countries. To date, the majority of guidelines on drinking water quality that is directly related to nitrate levels are based in its toxic effect in infants and neonates (primarily the occurrence of methemoglobinemia) and suggest as an arbitrary cut-off the existence of less than 10 mg/L as a measure of safety. Exposure to nitrate levels has been linked to adverse neurodevelopmental effects, fetal malformations and several forms of cancer. However, the associations remain scarce in several fields as the majority of available data is retrieved from articles that investigate the impact of nitrosatable drugs, rather than environmental exposure. In Greece, seven vulnerable regions have been recently identified, following the country`s referral to the Court of Justice by Commission. The aim of the present article is to summarize current evidence and provide recommendations for clinical practice and future research in the field.