They are also exposed to dust containing excessive amounts of lead. Other sources of exposure to lead include old food cans, industrial waste emissions, and the clothes of industrial workers. See lead in food. Nitrites and nitrates , used as fertilizers and occuring primarily from crop runoff, are the most pervasive contaminants found in drinking water. Coupled with the large amounts of fluid ingested by infants is the fact that nitrates are converted to nitrites in the infant's immature digestive system.
Nitrites can bind to hemoglobin in the blood, effectively blocking the binding sites for oxygen.
The term 'Blue Baby Syndrome' comes from the resulting blue color of the skin under oxygen deprived conditions. Other clinical signs are shortness of breath, increased sensitivity to illness, heart attacks, and possibly death by asphyxiation. Public drinking water supplies are monitored for nitrates and nitrites, and advisories are sent out if concentrations rise above set standards. Private water supplies are not monitored regularly by local agencies, and it may be advisable to use bottled drinking water for infants, especially in agricultural areas. See Nitrites and Nitrates in drinking water.