Nitrogen compounds in drinking water

Nitrates

 * Standard 50 mg/l;
 * an increased concentration of nitrates in drinking water is dangerous for infants → occurrence of methemoglobinemia.

Methemoglobinemia [ edit | edit source
Nitrates are reduced by bacteria in the GIT to nitrites → absorbed into the blood → change hemoglobin (Fe 2+ ) to methemoglobin (Fe 3+ ), which tightly binds oxygen → tissue hypoxia.

Clinical picture of methemoglobinemia
In the first stage, the lips and skin turn blue. The condition progresses to shortness of breath, hypoxia damages internal organs, and if this condition persists for a long time, death may occur.

Pathophysiology of methemoglobinemia

 * Infants (up to the third month) do not have a sufficiently mature methemoglobin reductase system;
 * at the same time, they still partially have fetal hemoglobin, which is more prone to the oxidation of Fe 2+ to Fe 3+.

Nitrites

 * Standard 0.1–0.5 mg/l;
 * presence in water indicates pollution;
 * the nitrate/nitrite ratio is important.

Nitrites and health
In the body, nitrites turn into some carcinogenic nitrosamines, which can cause stomach or bladder cancer. The protective factor is vitamin C, which serves as an antioxidant.