title: Reexamining the risks of drinking-water nitrates on public health.
abstract: BACKGROUND
  Nitrates in drinking water are generally considered the sole source of nitrite poisoning with methemoglobinemia in infantile methomoglobinemia (IM). However, IM, which occurs during the first 4 months of life, is actually a constellation of cyanosis and hypoxia associated with methemoglobinemia that can result from several other causes.
  
  
  METHODS
  This review reexamines the role of nitrate levels in drinking water as a cause of IM and identifies other sources of nitrates that can affect public health and cause chronic diseases.
  
  
  RESULTS
  Causes of IM include nitrites in foods, environmental chemical exposures, commonly prescribed pharmaceuticals, and the endogenous generation of oxides of nitrogen. Infants with congenital enzyme deficiencies in glucose-6-phosphate dehydrogenase and methemoglobin reductase are at greater risk of nitrite-induced methemoglobinemia from nitrates in water and food and from exposures to hemoglobin oxidizers.
  
  
  CONCLUSIONS
  Early epidemiological studies demonstrated significant associations between high groundwater nitrate levels and elevated methemoglobin levels in infants fed drinking water-diluted formulas. However, more recent epidemiological investigations suggest other sources of nitrogenous substance exposures in infants, including protein-based formulas and foods and the production of nitrate precursors (nitric acid) by bacterial action in the infant gut in response to inflammation and infection.
authors.affiliation: Louisiana State University School of Medicine, New Orleans, LA.
authors.forename: Alyce M
authors.initials: AM
authors.lastname: Richard
authors.affiliation: School of Public Health, Louisiana State University Health Sciences Center, New Orleans, LA ; Department of Anesthesiology, Louisiana State University Health Sciences Center, New Orleans, LA.
authors.forename: James H
authors.initials: JH
authors.lastname: Diaz
authors.affiliation: Department of Anesthesiology, Louisiana State University Health Sciences Center, New Orleans, LA ; Department of Pharmacology, Louisiana State University Health Sciences Center, New Orleans, LA.
authors.forename: Alan David
authors.initials: AD
authors.lastname: Kaye
keywords: Congenital methemoglobinemia; drinking water; glucose-6-phosphate dehydrogenase deficiency; nitrates; nitrites