The U.S. Environmental Protection Agency has set a maximum contaminant level for nitrates at 10 parts per million. High levels of nitrates can cause health problems, including methemoglobinemia, commonly known as “blue baby syndrome.”
In blue baby syndrome, nitrates are reduced to nitrites by bacteria in an infant’s stomach. When the nitrites enter the bloodstream, they interfere with the blood’s ability to carry oxygen to body tissues. This can be an acute condition in which the baby’s health deteriorates rapidly in a span of a few days. It can cause shortness of breath, increased susceptibility to illness, heart attacks, and even death by asphyxiation.
Older children and adults are able to withstand higher levels of nitrates than babies because of stronger stomach acids that kill the bacteria. However, there have been reports that nitrates could potentially be linked to gastrointestinal cancer. The EPA also says that long-term exposure to water over the maximum contaminant level can cause diuresis (excessive discharge of urine), increased starchy deposits, and hemorrhaging of the spleen.
The presence of significant levels of nitrite and nitrate may indicate additional groundwater contamination conditions, which should be investigated and addressed. Some nitrate-reducing bacteria are known to form heavy growths on well screens and equipment. Excessive nitrate in groundwater feeding ponds and streams contributes to algal growth and oxygen depletion, affecting aquatic life.