Nitrate in Drinking Water
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How can nitrate get into my well water?
Nitrate is a
chemical found in most fertilizers, manure and liquid waste discharged
from septic tanks. Natural bacteria in soil can convert nitrogen into
nitrate. Rain or irrigation water can carry nitrate down through the
soil into groundwater. Your drinking water may contain nitrate if your
well draws from this groundwater.
How does nitrate affect health?
Nitrate is an acute
contaminant, which means a single exposure can affect a person's health.
It reduces the ability of red blood cells to carry oxygen. In most
adults and children these red blood cells rapidly return to normal.
However, in infants it can take much longer for the blood cells to
return to normal. Infants who drink water with high levels of nitrate
(or eat foods made with nitrate-contaminated water) may develop a
serious health condition due to the lack of oxygen. This condition is
called methemoglobinemia or "blue baby syndrome." Some scientists think
diarrhea can make this problem even worse.
Low
levels of nitrate in water will not have a long-lasting effect
on your baby. If your baby does not have any of the symptoms of
"blue baby syndrome," you do not need to have a doctor test for
methemoglobinemia.
How is nitrate in drinking water regulated?
Washington's drinking
water quality standard for nitrate is 10 milligrams per liter, or 10
parts per million (ppm). State law requires public water systems
to sample for many contaminants, including nitrate, on a regular basis.
Public water systems with nitrate levels over 10 ppm must notify the
people who receive water from them.
Signs of "blue baby syndrome"
An infant with
moderate to serious "blue baby syndrome" may have a brownish-blue skin
tone due to lack of oxygen. This condition may be hard to detect
in infants with dark skin.
An infant
with mild to moderate "blue baby syndrome" may have symptoms
similar to a cold or other infection (fussy, tired, diarrhea or
vomiting). 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.
What to do about "blue baby syndrome"
If your baby has a
brownish-blue skin tone, take him/her to a hospital immediately. A
medication called "methylene blue" will quickly return the baby's blood
to normal.
Preventing "blue baby syndrome"
The best way to
prevent “blue baby syndrome” is to avoid giving your baby water that may
be contaminated with nitrate and foods that are high in nitrate. Infants less than 1-year-old should not be given drinking water with
nitrate levels more than 10 ppm. High-nitrate vegetables such as beets,
broccoli, carrots, cauliflower, green beans, spinach and turnips should
not be offered until after six months of age.
Nitrate levels in
well water can vary throughout the year. If you have a private well and
the nitrate level is above five mg/L,or if you haven't tested your well,
you may want to use bottled water for your baby's foods and drinks.
Although boiling water kills bacteria, it will not remove chemicals such
as nitrate. In fact, boiling may actually increase the nitrate level.
Will breast-feeding give my infant "blue baby
syndrome"?
Low levels of nitrate
have been found in breast milk, but the levels are not high enough to
cause "blue baby syndrome."
Can nitrate affect adults?
Although red blood
cells in older children and adults quickly return to normal, some health
conditions make people susceptible to health problems from nitrate. They
include:
Some studies have
found an increased risk of spontaneous abortion or certain birth defects
if the mother drank water high in nitrate. Women who are pregnant
or are trying to become pregnant should not consume water with more than
10 mg/L of nitrate.
How can I tell if my well water has nitrate?
Shallow wells, poorly
sealed or constructed wells, and wells that draw from shallow aquifers
are at greatest risk of nitrate contamination. Manure and
septic-tank waste may also contain disease-causing bacteria and viruses.
If you own
a private well and are unsure about your water quality, you
should test for coliform bacteria and nitrate. Your county
health department can tell you where you can get your water
tested and may have specific recommendations for testing. Many
certified labs in Washington charge $20 to $40 per test. If your
nitrate test results are over 8 mg/L, we recommend annual
testing. If results are less than 8 mg/L, we recommend you test
every three years. (Also see Important information for private
wellowners, DOH Pub. #331-349).
Where can I get more information?
If you get your water
from a public water system, call your water utility or the Washington
State Department of Health Office of Drinking Water at 1-800-521-0323 or
visit our Drinking Water
homepage. If
you have a private well, call your local health department.
For a list of certified labs, visit the
Washington State Department of Ecology Web Site. Under
"Location," select your state, city and county. Scroll down and
click on "Show results." Click on the name of a lab to see the
tests it performs. Call the lab to make sure it is accredited
for drinking water analysis of nitrate.
February 2007
DOH PUB. #331-214 (Revised)
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