What are Nitrate and Nitrite?
Nitrate and Nitrite are naturally occurring inorganic ion compounds. Ammonia is released when organic materials, such as animal wastes, decompose in soil. This ammonia oxidizes to form nitrate and nitrite. Both nitrate and nitrite can be found in groundwater and soil, but nitrate is more common.
What Happens to Nitrate and Nitrite in the Environment?
Nitrate and Nitrite are ionic compounds that naturally occur as part of the earth's nitrogen cycle. Typically, nitrate and nitrite are found in highly water-soluble forms and are connected to other ions such as potassium or sodium. When combined with oxygen, nitrite forms nitrate. Plants use nitrate as an essential nutrient which is why they are often used in inorganic plant fertilizers.
Where are Nitrate and Nitrite Found and how are They Used?
Nitrate and Nitrite occur naturally in soil and water at levels that do not cause health problems. Nitrate is also found naturally in vegetables, fruits, dairy, meat, and other foods. When excess nitrate is introduced into the environment by humans, however, the groundwater and drinking water can get contaminated with high levels of the chemical. The overuse of chemical fertilizers containing nitrogen compounds, improper disposal of animal wastes on animal feedlots, pesticide runoff from farms, and septic systems and sewage treatment facilities are all sources of nitrate contamination.
How Might I Be Exposed to Nitrate and Nitrite?
Humans are primarily exposed to nitrate and nitrite through consuming food or water that contains nitrate and nitrite. You may be exposed to unnaturally high levels of nitrate and nitrite through ingestion of water from a contaminated private well or an improperly managed public drinking water system. Humans might also be exposed by inhaling nitrate or nitrite in fertilizer dust or dermally, through their skin, if the fertilizer dust dissolves in sweat on the skin. Certain foods, especially cured meats, are also high in nitrates.
How can Nitrate and Nitrite Ingestion Affect My Health?
Nitrates can turn the body's hemoglobin, the chemical in the blood responsible for transporting oxygen, into methemoglobin. Increased methemoglobin reduces the ability of the blood to transport oxygen to cells that need it. This oxygen starvation is the cause of methemoglobinemia ("blue baby syndrome" in infants). In mild cases, the reduced oxygen can cause lips to have a bluish tint in the lips, ears, and nose. In severe cases, it can lead to respiratory problems and even death.
Infants are especially at risk for methemoglobinemia because there is an increased conversion of nitrate to nitrite due to the low hydrogen potential in infant stomachs. Pregnant women are also more at risk as their methemoglobin levels are naturally higher during pregnancy, which means they cannot tolerate as much additional exposure to nitrate and nitrite. Children and adults who consumed food or water with high levels of nitrite have experienced the following health problems:
In addition, the International Agency for Research on Cancer (IARC), a division of the World Health Organization (WHO), has concluded that under certain conditions, nitrate and nitrite are probably carcinogenic to humans. Scientific studies have linked nitrate and nitrite with the following cancers:
How can I Reduce My Family's Risk of Exposure to Nitrate and Nitrite?
If you consume water from a private well, have the well tested regularly for nitrates. You can also protect your water supply from nitrate contamination by reducing fertilizer and manure use and by properly maintaining your septic system and tanks. Although federal and state regulations require testing of public water systems for nitrates, if you suspect high levels of nitrates in your water, contact your local department of public health.
Are There Medical Tests to Determine if I Have Been Overexposed to Nitrate and Nitrite?
Yes, there are methods to detect nitrate and nitrite in blood and urine. However, these methods are not always available at a doctor's office. Routine blood tests can also detect methemoglobinemia but the tests cannot determine whether the condition was caused by nitrate or nitrite.
What Should I do if I'm Concerned My Family's Health may Be Affected?
If your baby is presenting with a brownish-blue skin tone or a bluish color to the lips, tongue, gums, nail beds, or nose, seek immediate medical attention as this condition could lead to a coma or even death. For other concerns see your family doctor and let them know you suspect you have ingested a high level of nitrate or nitrite.
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