What are nitrates and nitrites?
Nitrate and nitrite are two nitrogen compounds needed by plants and animals to live and grow. They occur naturally in soil, water, and air and are also made in the body.
In agriculture, nitrate is used as fertilizer for crops and lawns. Nitrate and nitrite are also used as food preservatives.
How can I be exposed to nitrates and nitrites?
Nitrate and nitrite dissolve easily in water and will move quickly through soil into surface water and groundwater.
People can be exposed to nitrates and nitrites by drinking contaminated water. Nitrates and nitrites can enter drinking water from fertilizers, septic tanks, and decaying natural material such as livestock manure and decaying plants.
Nitrate and nitrite are also found in vegetables (especially celery, lettuce, and spinach), fruits, cured meats, fish, dairy products, beers, and cereals.
How can nitrates and nitrites affect my health?
Most people are not exposed to levels of nitrates and nitrites that would cause health effects.
Nitrates are not normally dangerous to health unless they are converted to nitrites, which can happen inside the body. Infants are more prone to the effects of nitrate exposure due to this change from nitrate to nitrite in the body - especially if an infant is fed formula prepared with drinking water that has high levels of nitrates and/or nitrites. This can interfere with the oxygen-carrying capacity of the child's blood and cause a health condition called methemoglobinemia. This condition can worsen rapidly over a period of days with symptoms including shortness of breath and blueness of the skin.
There is limited evidence that long-term exposure to nitrate and nitrite can cause some cancers. Because the data are inconclusive, health standards focus on protecting infants.
What is the drinking water standard for nitrates and nitrites?
The U.S. Environmental Protection Agency (EPA) and Massachusetts Maximum Contaminant Levels are 10 milligrams per liter (mg/L) for total nitrate and nitrite (and 10 mg/L for nitrate and 1 mg/L for nitrite for transient non-community systems).
In Massachusetts, local Boards of Health and Health Departments have the authority to regulate private wells and may establish criteria for their location, construction, water quality, and quantity. Additional information for residents who use private wells is available from MassDEP.
What are the testing requirements for nitrates and nitrites?
All public water systems are required to test for nitrate and nitrite at each entry point to the distribution system (after water is treated and before it enters the pipes that bring water to customers). Surface water systems are required to test quarterly (every three months) and groundwater systems are required to test for nitrate and nitrite every year. The Massachusetts Department of Environmental Protection (MassDEP) reviews the testing plan for each public water system and adjusts it according to past sample results and other considerations.