For most people, consuming small amounts of nitrate is not harmful. Nitrate can cause health problems for infants, especially those six months of age and younger. Nitrate interferes with their blood’s ability to transport oxygen. This causes an oxygen deficiency, which results in a dangerous condition called methemoglobinemia, or “blue baby syndrome.” The most common symptom of nitrate poisoning is bluish skin coloring, especially around the eyes and mouth. Infants six months of age and younger and pregnant and nursing women should avoid consumption of water high in nitrate. Cattle, horses, sheep, and baby pigs, are also susceptible to nitrate poisoning.