What contaminants in water are known to cause methemoglobinemia?

Methemoglobinemia is a condition where the ability of hemoglobin to carry oxygen in the blood is impaired, leading to a decrease in the oxygen delivery to tissues. One of the main causes of methemoglobinemia is exposure to contaminants that can oxidize hemoglobin to methemoglobin. Nitrates and chloramines are well-documented as contaminants that can lead to this condition.

Nitrates, which are commonly found in fertilizers and can leach into drinking water supplies, can be converted to nitrites in the body. Nitrites have a high affinity for hemoglobin, converting it to methemoglobin, thereby reducing the oxygen-carrying capacity of the blood. This is particularly critical in infants, as their digestive systems can convert nitrates to nitrites more readily, making them more susceptible to methemoglobinemia.

Chloramines, which are formed when chlorine used for disinfection reacts with ammonia, can also contribute to methemoglobinemia through a similar oxidative process on hemoglobin. During the disinfection process, chloramines can enter the water supply, and their presence can cause methemoglobinemia by oxidizing hemoglobin to its methemoglobin form.

In summary, nitrates and chloramines both pose