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Nitrate

What is it and where is it found?

Nitrate, a naturally occurring compound of nitrogen and oxygen atoms, is found nearly everywhere in the environment. Artificially made nitrate is often added to fertilizers because it improves plant growth. Nitrate is also found in animal manure and septic systems.  Nitrate dissolves easily in water and can be washed into groundwater, rivers and streams by irrigation or rainfall, potentially contaminating water supplies and contributing to toxic algae blooms.

How do people come into contact with it?

Everyone ingests some nitrate from their diet. Certain vegetables have naturally high levels of nitrate, but any worrisome health effects are offset by the vitamins the vegetables contain. Another dietary source of nitrate is sodium nitrate, which is used to preserve cured meats like bacon, ham and various lunchmeats. Cured meats should be a limited part of the diet. People can also be exposed to nitrate by drinking water that is contaminated by runoff from areas where fertilizers or manure were applied or from leaking sewer or septic systems.

 Private wells are especially vulnerable to nitrate contamination because they are often located in rural areas where fertilizers are heavily used, or they may be located close to septic systems. Contaminated well water may also indicate improper well construction, maintenance or location.

What are the health concerns?

High levels of nitrate can seriously interfere with the blood’s ability to carry oxygen to vital tissues in the body. People who drink nitrate-contaminated water may develop a condition called methemoglobinemia. Symptoms of methemoglobinemia can range from a bluish tinge to the skin, rapid pulse and weakness to convulsions, coma, or in very extreme cases, death.

Methemoglobinemia is sometimes referred to as "blue baby syndrome” due to cases of children less than one year old developing the condition after drinking nitrate-contaminated water or drinking formula that has been mixed with such water.  Pregnant or nursing women should be informed that if they drink nitrate-contaminated water, they may pass high levels of nitrates on to their infants.

Seniors with pre-existing health conditions and those taking certain medications also may be at risk for developing methemoglobinemia. Other potential health effects suggested to be associated with long term exposure to nitrate-contaminated water include bladder, stomach and ovarian cancers, recurring acute respiratory infections, diabetes and hormonal and nervous system disorders in children.

What can I do to protect myself, my family, or my employees?

If you get your water from a domestic well, test for nitrate on a yearly basis. A list of accredited Oregon laboratories can be found here.  Nitrate levels should be less than 10 parts per million (ppm).

Certain filtration systems can remove nitrate from water. Ion exchange, distillation and reverse osmosis are three types typically used. However, these systems require careful and ongoing maintenance to work properly. When choosing a filtration system, look for the National Sanitation Foundation (NSF) certification.

Heating or boiling contaminated water will not remove nitrate, and may actually concentrate nitrate levels.

If you get your water from a private well, test for nitrate on a yearly basis in the spring. Testing more than once a year may be warranted if:  

  • An infant is in the home;
  • Someone is nursing or pregnant;
  • Neighboring wells are contaminated;
  • There are changes in the taste or odor of the well water;
  • The well was recently repaired or replaced.

What's being done to protect public health?

The U.S. Environmental Protection Agency (EPA) has set a maximum contaminant level (MCL) for drinking water. All public water systems must have nitrate levels below 10 parts per million (PPM). 

Oregon law requires that owners of residential properties with domestic wells have their water tested for nitrates, bacteria and arsenic prior to selling the property.  This information is collected by the Oregon Health Authority Drinking Water Program for analysis and outreach.

Where can I get more information?

Oregon Department of Environmental Quality, Nitrate in Drinking Water 

Oregon Health Authority, Drinking Water Program, Health Effects of Nitrate Oregon State University’s Well Water Program

The Agency for Toxic Substances and Disease Registry (ATSDR)  Nitrate factsheet