overview of nitrate in drinking water and its health effect with emphasis on its carcinogenic risk in human

during the past two centuries, production and consumption of nitrate, especially in agricultural field, have been increased considerably. currently many countries in the world including iran encounter to a high nitrate level in drinking water. the main reason is the seepage of agricultural runoff and municipal and industrial wastewater to water resources, particularly groundwater. from the old days, it has been demonstrated that high nitrate levels in drinking water can cause methemoglobinema in infants, and even standard limits for the nitrate level in water is established on the basis of infant preservation from this disease. however, the important issue that has been a controversial subject between researchers for decades is carcinigenity potential of nitrate in drinking water that many studies have related high prevalence of variety of cancers such as stomach, thyroid and bladder to high nitrate levels in drinking water. nevertheless, some researches didn’t confirm this hypothesis. in this study the findings of the related researches on the subject “cancer risk related to nitrate in water” is reviewed. also some other issues related to nitrate including dietary nitrate, nitrate metabolism in human body, other significance adverse effects of nitrate like methemoglobinemia and its reproductive and developmental effects are reviewed. finally, general procedure to nitrate control in drinking water is discussed.