Frequently Asked Questions
Nitrates in Public Drinking Water
What are nitrates?
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Nitrate (NO3) is a naturally occurring chemical made of nitrogen and
oxygen.
Much of the nitrate in our environment comes from decomposition
of plants and animal wastes.
People also add nitrate to the environment in the form of fertilizers,
sewage, manure, and some industrial wastes.
Nitrate is commonly used as a preservative and for color
enhancement of processed meats.
Nitrate dissolves easily in water. Major sources of nitrate in drinking
water include fertilizers, sewage and animal manure.
How much nitrate is allowed in drinking water?
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The EPA established a maximum contaminant level for nitrate in public drinking water systems of
10 milligrams per liter.
This level of nitrate can be present in drinking water without a high risk of causing health
problems. This level is considered to be protective of the most sensitive population, infants less
than 6 months of age.
Who is at risk for negative health impacts from nitrates?
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Infants less than 6 months old
Women trying to get pregnant, pregnant and/or nursing
Other sensitive individuals (detailed below)
Infants
What is blue baby syndrome?
Infants younger than 6 months of age are most at risk from high nitrates by ingesting water containing
nitrates or formula diluted with nitrate contaminated water. If an infant drinks water or formula made
with water that is high in nitrate, a condition called blue baby syndrome (or methemoglobinemia) can
develop. Bacteria present in an infant's stomach can convert nitrate to nitrite (NO2), a chemical that can
interfere with the ability of the infant's blood to carry oxygen. As the condition worsens, the baby's skin
turns a bluish color, particularly around the eyes and mouth. If prompt medical attention is not received,
death can result. Infants with illnesses that cause vomiting and diarrhea are at highest risk for blue baby
syndrome.
What should I do if I have a baby less than six months old?
Do NOT allow your baby to drink tap water or use tap water to prepare juice, formula or other food.
Bottled water should be used for infants until you receive notice that nitrate levels in your drinking
water have been reduced to below 10 milligrams per liter.
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Frequently Asked Questions
Nitrates in Public Drinking Water
Why are young infants more susceptible to nitrates?
As an infant ages, its stomach acidity increases, reducing the
numbers of nitrite producing bacteria. After six months, the
conversion of nitrate to nitrite in the stomach no longer
occurs. Most adults can consume large amounts of nitrate with
no ill effects. In fact, the average adult in the United States
consumes about 20-25 milligrams of nitrate every day in food,
largely from vegetables.
What are the symptoms of blue baby syndrome?
An infant with moderate to serious" blue baby syndrome" may
have a brownish- blue color due to the lack of oxygen. This condition may be hard to detect in infants
with dark skin. In mild to moderate cases, babies may have the same symptoms as when they have a
cold or another infection. They may act fussy, tired, have diarrhea, or vomit. In severe cases, the child
may gasp for air. While there is a simple blood test to see if an infant has "blue baby syndrome," doctors
may not think to do this test for babies with mild to moderate symptoms. Many other common illnesses
cause the same symptoms. If your baby has a brownish- blue color, bring your baby to a hospital
immediately. There is a medication methylene blue) that will quickly make your baby's blood go back to
normal. The body always has some methemoglobin due to normal biologic processes. Low levels of
methemoglobin do not require treatment but the child should not be given nitrate contaminated water.
Women
Pregnant women are more sensitive to the effects of nitrate in drinking water during the later stages of
pregnancy (30 weeks). Some studies have shown that consuming water with high levels of nitrates may
increase the risk of pregnancy complications such as anemia, threatened abortion/premature labor, or
preeclampsia (a late pregnancy condition that requires medical treatment). Other studies have shown a
possible link between higher levels of nitrate in drinking water and spontaneous miscarriages and
certain birth defects.
Fetuses and infants are more susceptible to nitrate induced methemoglobinemia because their oxygen
carrying molecule, hemoglobin, is not mature. Pregnant and breastfeeding mothers should avoid nitrate
contaminated water until the level is below 10 ppm. This level has been shown to be safe in all people,
including pregnant women and infants.
Others in the General Population Who May Have Concern
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Patients with oxygen transport or delivery conditions like anemia, cardiovascular diseases, lung
disease, sepsis, etc.
People taking certain antibiotic medications
People taking the following medications: anesthetic teething gels, phenazopyridine (Pyridium),
dapsone, isosorbide dinitrate (Isordil, Dilatrate-SR, BiDil), isosorbide mononitrate (Imdur, Ismo,
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Frequently Asked Questions
Nitrates in Public Drinking Water
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Monoket), nitroglycerin (Nitrolingual, NitroMist, Nitrostat), or topical anesthetics such as
lidocaine (Lidoderm patch, AnaMantle HC, LidaMantle HC, Synera) or tetracaine.
People with enzyme deficiency (Glucose 6 Phosphate Dehydrogenase and RBC methemoglobin
reductase and other genetic factors)
Recreational drug users (volatile nitrite inhalers, cocaine, cocaine adulterated with phenacetin
and local anesthetics like benzocaine)
People with rare conditions, which are generally passed on through generations, who have
higher than normal levels of methemoglobin in their blood
What should I do if I am pregnant, breastfeeding, or part of the population
that is sensitive to nitrates in drinking water?
If you are concerned about your health for any reason, you can use bottled water or other water low in
nitrates to drink and prepare your meals. Consult your physician or the Poison Control Center (1-800222-1222) for additional information specific to your condition.
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Substitute bottled water for tap water for drinking and cooking until the nitrate advisory is lifted
Boiling tap water will not get rid of the nitrate; it only concentrates it
It is safe to bathe or shower in tap water with elevated nitrate levels
Avoid exposure to water, soil or food contaminated with high levels of nitrates
Are there long-term health problems from high levels of nitrate in drinking
water?
Exposure to high nitrate levels for short periods of time is unlikely to result in long-term health
problems. However, little is known about the long-term effects of drinking water with elevated nitrate
levels. There is not sufficient scientific evidence to strongly link long-term health effects with elevated
nitrate levels in drinking water. Also, there is not sufficient evidence of cancer in humans from nitrate in
food and drinking water.
What about bathing and showering?
Nitrate does not easily enter the body through the skin.
Bathing, swimming and showering with water that has levels
of nitrate over10 milligrams per liter is safe as long as you
avoid swallowing the water. Supervise small children when
they are bathing and brushing teeth to ensure they do not
swallow the water.
What about washing dishes, utensils and
food preparation areas?
Only a very small amount of water clings to smooth surfaces,
like dishes. Water having more than 10 ppm of nitrate may
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Frequently Asked Questions
Nitrates in Public Drinking Water
be safely used to wash and sanitize dishes, tables and eating utensils.
What about general cleaning and laundry?
Very little water remains on washed surfaces and in laundered fabrics. Because these articles are not
placed in the mouth, water having more than 10 ppm of nitrate may be safely used for general cleaning
and washing of clothing, bedding and linens.
What type of water treatment system do I need in my home to reduce the
nitrate levels?
Generally available water filters like Brita or PUR do not remove nitrates from drinking water.
Learn more about nitrates in drinking water
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For information on drinking water and maximum contaminant levels:
http://www.epa.gov/safewater/contaminants/index.html
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For information on the health effects of nitrates:
http://www.epa.gov/teach/chem_summ/Nitrates_summary.pdf
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