Nitrogen, an abundant element, is present in the air we breathe and naturally dissolved in water. The safety of nitrogen in drinking water is nuanced, depending on its specific chemical form. Understanding these forms is crucial for assessing potential health implications.
Nitrogen Gas Versus Contaminants
The most common form, nitrogen gas (N2), is generally harmless when dissolved in water. This dissolved gas is inert, similar to carbon dioxide in sparkling water, and poses no health concerns. Bubbles sometimes observed in tap water are often dissolved nitrogen or oxygen, which are naturally present and do not signify contamination. The concern arises from specific nitrogen compounds that act as contaminants.
The Harmful Forms: Nitrates and Nitrites
The nitrogen compounds posing health risks are primarily nitrates (NO3-) and nitrites (NO2-). These compounds enter water sources through human activities or natural processes. Common sources include agricultural runoff from fertilizers, animal manure, and human waste from septic systems and sewage. Nitrate is often more prevalent in water but can convert to nitrite in the environment and human body. This conversion is significant because nitrites are considerably more harmful than nitrates.
Health Impacts and Vulnerable Populations
High levels of nitrates and nitrites in drinking water can lead to serious health issues, particularly for infants. The most recognized condition is methemoglobinemia, or “blue baby syndrome,” where nitrites interfere with the blood’s ability to carry oxygen. Infants under six months are especially vulnerable due to less acidic digestive systems, which allow bacteria to convert nitrates into nitrites more efficiently, and lower levels of an enzyme that reverses this process. Symptoms include shortness of breath and a bluish or brownish discoloration of the skin, lips, or fingernails.
While methemoglobinemia primarily affects infants, research links long-term adult exposure to nitrates to other health concerns, even below regulatory limits. These include possible links to certain cancers, such as colorectal cancer, and adverse reproductive outcomes like increased risk of spontaneous preterm birth and birth defects. The U.S. Environmental Protection Agency (EPA) set Maximum Contaminant Levels (MCL) for nitrate at 10 ppm (NO3-N) and nitrite at 1 ppm (NO2-N) to protect against these effects. These enforceable standards apply to public water systems.
Ensuring Your Drinking Water is Safe
Determining nitrogen compound levels in your drinking water is crucial for safety. Public water system users can find this information in annual water quality reports. Private well owners must test their water annually, especially near agricultural areas or septic systems. Nitrate and nitrite are colorless, odorless, and tasteless, making professional laboratory testing the only reliable way to detect their levels.
If nitrate or nitrite levels are high, several treatment methods can reduce them. Point-of-use systems like reverse osmosis (RO) and distillation effectively treat water for drinking and cooking. Ion exchange systems also remove nitrates. Boiling water is ineffective and actually concentrates nitrates. For infants, using an alternative, low-nitrate water source is advised if contamination is confirmed.