title: Methaemoglobinaemia in areas with high nitrate concentration in drinking water.
abstract: BACKGROUND
  An epidemiological investigation was undertaken in all age groups to assess the prevalence of methaemoglobinaemia in areas with high nitrate concentration in drinking water.
  
  
  METHODS
  Five areas were selected with an average nitrate concentration (as nitrate) of 26, 45, 95, 222 and 459 mg nitrate ions/litre in drinking water. These areas were visited and the house schedule (containing name, age, sex and weight of the family members) prepared in accordance with the statistically designed protocol. In all, 178 persons, matched for age and weight, were selected and arranged in five age groups. They constituted 10% of the total population of each of these areas. A detailed history of the selected population was taken, medical examination conducted and blood samples taken to ascertain the level of methaemoglobin. The collected data were subjected to statistical analysis to ascertain a relationship between nitrate concentration and methaemoglobinaemia.
  
  
  RESULTS
  High nitrate concentrations cause severe methaemoglobinaemia (7%-27% of Hb) in all age groups, especially in the age group of less than 1 year and above 18 years. The lower levels of methaemoglobin in the age group of 1-18 years is probably due to better reserve of cytochrome b5 reductase activity and its adaptation to increasing nitrate concentration in water to compensate for methaemoglobinaemia in this age group.
  
  
  CONCLUSIONS
  We conclude that high nitrate ingestion causes methaemoglobinaemia in all age groups. Cytochrome b5 reductase activity and its adaptation with increasing water nitrate ingestion plays a role in compensating for the methaemoglobinaemia.
authors.affiliation: Satellite Hospital, Rajasthan, India.
authors.forename: S K
authors.initials: SK
authors.lastname: Gupta
authors.forename: R C
authors.initials: RC
authors.lastname: Gupta
authors.forename: A K
authors.initials: AK
authors.lastname: Seth
authors.forename: A B
authors.initials: AB
authors.lastname: Gupta
authors.forename: J K
authors.initials: JK
authors.lastname: Bassin
authors.forename: A
authors.initials: A
authors.lastname: Gupta
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003579:Cytochrome Reductases / Q000097:blood; D006801:Humans; D007194:India / Q000453:epidemiology; D007223:Infant; D007231:Infant, Newborn; D008708:Methemoglobinemia / Q000139:chemically induced* / Q000453:epidemiology / Q000503:physiopathology; D008875:Middle Aged; D009566:Nitrates / Q000506:poisoning*; D012044:Regression Analysis; D014873:Water Pollutants / Q000506:poisoning*; D014881:Water Supply
chemical_list: D009566:Nitrates; D014873:Water Pollutants; D003579:Cytochrome Reductases