Drinking-water nitrate, methemoglobinemia, and global burden of disease: a discussion.
On behalf of the World Health Organization (WHO), I have undertaken a series of literature-based investigations examining the global burden of disease related to a number of environmental risk factors associated with drinking water. In this article I outline the investigation of drinking-water nitrate concentration and methemoglobinemia. The exposure assessment was based on levels of nitrate in drinking water greater than the WHO guideline value of 50 mg/L. No exposure-response relationship, however, could be identified that related drinking-water nitrate level to methemoglobinemia. Indeed, although it has previously been accepted that consumption of drinking water high in nitrates causes methemoglobinemia in infants, it appears now that nitrate may be one of a number of co-factors that play a sometimes complex role in causing the disease. I conclude that, given the apparently low incidence of possible water-related methemoglobinemia, the complex nature of the role of nitrates, and that of individual behavior, it is currently inappropriate to attempt to link illness rates with drinking-water nitrate levels.
Centre for Research into Environment and Health, 5 Quakers Coppice, Crewe Gates Farm, Crewe, Cheshire CW1 6FA, United Kingdom. Lorna@creh.demon.co.uk
Lorna
L
Fewtrell
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D017281:Cost of Illness; D004781:Environmental Exposure; D005260:Female; D014943:Global Health; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008708:Methemoglobinemia / Q000209:etiology*; D008875:Middle Aged; D009566:Nitrates / Q000506:poisoning*; D012307:Risk Factors; D014874:Water Pollutants, Chemical / Q000506:poisoning*; D014881:Water Supply
D009566:Nitrates; D014874:Water Pollutants, Chemical