However, because of individual differences in infants, some may not be affected. If an infant is affected, the skin becomes blue similar to the color of the blood vessels located close to the skin. If this condition is observed, seek medical help immediately. The infant is becoming asphyxiated, because oxygen cannot be transported by the blood. Prompt medical attention normally results in quick recovery of the infant.
Adults can consume large quantities of nitrates in drinking water or food with no known ill effects.
The adult stomach, which contains strong acid, does not promote the growth of bacteria which convert nitrate to the more toxic nitrite. Infants, however, are more susceptible because their stomach juices are less acidic, and therefore conducive to the growth of nitrate-reducing bacteria. Not all infants are affected by nitrates. Boiling the water will not reduce nitrates and should not be used for preparation of infant formula or in any other way that could result in consumption by the baby. It is often difficult to pinpoint sources of nitrates because there are so many possibilities.