Nitrates in Well Water and Infant Feeding
by Anne Eglash MD, IBCLC, FABM
There is an uncommon condition called methemoglobinemia, AKA Blue Baby Syndrome, that can occur in young infants when exposed to variety of substances, mainly nitrates. This condition occasionally develops in older children and adults, but the vast majority of cases involve infants under 2 months of age because of immature metabolic activity in their red cells that carry oxygen.
Nitrates are the main cause of methemoglobinemia in young infants. Nitrates occur in the soil from bacteria, but also from car exhaust, fertilizer, manure, and other sources. The nitrates end up in wells and ground water. The US Safe Drinking Water Act mandates that all public water supplies test water for nitrates, so water from cities and other municipalities have low nitrate levels. The greatest source of nitrates in water is from private wells that are not tested regularly.
In young infants, symptoms of methemoglobinemia may include poor feeding, low tone, and delay of developmental milestones. The infant may appear bluish in areas of thin skin such as lips, earlobes and nailbeds. However, the authors of this week’s article state that the bluish signs of methemoglobinemia may not be obvious, and some infants may just be fussy and lethargic.
Despite the fact that the % of nitrates in US soil has been increasing due to artificial fertilizers, reports of methemoglobinemia are uncommon. The author theorizes that we are seeing much less infant methemoglobinemia in the USA because of high breastfeeding rates in the first few months of life, in addition to improved codes on well construction.
Nitrate levels in breastmilk are very low, much lower than the mother’s serum level. There has never been a reported case of a breastfed infant with methemoglobinemia.
Vegetables can be high in nitrates, including leafy greens, carrots and celery. Peeling and steaming/boiling vegetables decreases the nitrate content. The Center for Disease Control states that children at highest risk for methemoglobinemia are those under 6 months who ingest formula prepared with water high in nitrates. They also recommend that families eat fewer foods that are high in nitrates or nitrites, but don’t specifically advise avoiding feeding certain vegetables to infants and young children.
- Local anesthetics used for procedures such as circumcision can cause methemoglobinemia.
- The oral anesthetic benzocaine used over-the-counter for teething, sore throats, and canker sores can cause methemoglobinemia.
- Most cases of infant methemoglobinemia are due to underlying metabolic disorders that decrease their tolerance to small amounts of nitrates in water.
- It is considered normal for individuals to have approximately 1.5% methemoglobin in their blood.
- Soy infant formulas have higher nitrate levels than non-soy formulas.
- Well water should be tested for nitrates once a year.
- Boiling well water will destroy the nitrates.
- Washing and peeling vegetables will decrease nitrates.
See the Answer
Methemoglobin is formed when the iron center in hemoglobin is oxidized from ferrous iron to ferric iron. The functional consequence of this change is that hemoglobin is transformed to methemoglobin and cannot oxygenate tissues adequately, causing hypoxia and cyanosis. Infants have unique physiology that increases their risk of developing methemoglobinemia. Infants drink more water per body weight compared to children and adults, have lower NADH cyb5r reductase activity that converts methemoglobin to hemoglobin, and have a higher percentage of fetal hemoglobin, which is easier to convert to methemoglobin. A well-studied exposure to a chemical that can cause methemoglobinemia in infants is nitrate in well water. For the first part specifically about methemoglobin in infants, articles that were recent (2015-now) were given preference over articles that were older. Search terms included: methemoglobin, methemoglobinemia, infant, acquired, congenital, and methylene blue. For the latter half of the paper on nitrate and methemoglobinemia, preference was given to articles that described regionally important cases. In addition, search terms were: Minnesota, methemoglobinemia, nitrate, well water, drinking water, and infant. Acquired methemoglobinemia is rare, yet can still be seen in medical settings, and when an infant is exposed to nitrate in well water above 10 mg/L. To prevent exposure, parents should have their water tested for nitrate before the baby comes home. Physicians should make it practice to ask what the source of drinking water is for newly pregnant women and urge them to test for nitrate and bacteria if using a well. Using bottled water to make formula is also an option, but the best option is still breastfeeding.
Benzocaine and lidocaine can cause methemoglobinemia. Benzocaine can still be found in some over-the-counter products for both infants and adults. Lidocaine is used for medical procedures such as circumcisions.
Most cases of infant methemoglobinemia occur in infants under 2 months of age who consume formula prepared with water high in nitrates.
Boiling well water will kill bacteria but will not remove nitrates.
I wrote about this topic today because we might see a rise in formula use among newborns during the COVID-19 pandemic. Families may have less contact with breastfeeding supporters such as family members, WIC, lactation consultants, mother-infant support groups, etc. We need to remind families to have their private wells tested annually, especially if using well water for preparing infant formula. Given the financial crisis and social distancing, families may be more tempted to use their well water than to purchase bottled water for formula preparation.
In addition, I have heard from families in my practice that they are planting victory gardens not only to save money, but because they have time to garden during the safe-at-home orders. Families may ask if their infants can have fresh veggies from the garden. The answer is yes. Peeling and washing veggies, as well as steaming, will reduce the nitrate and nitrite content of the produce.