Q: Could you write something about nitrates in drinking water? What does it do to the body and is it safe to drink the water? How does it affect animals and people? Our count was 107 milligrams per litre. Using reverse osmosis it rose to 148 mg per litre. At the moment it contains 91 mg per litre.
A: A nitrate is an inorganic compound, mostly soluble in
water, that has the chemical symbol NO3. Nitrites with the symbol NO2 can be formed from nitrates by a chemical process known as reduction. Nitrates do not normally cause health problem in adults unless they are turned into nitrites.
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Nitrates in drinking water are considered safe at levels of 10 mg per litre or less. Most city drinking water easily conforms to that standard, but with private rural wells such as yours, it may be a different story.
Sources of nitrogen and nitrates may include runoff or seepage from fertilized agricultural land, municipal and industrial waste water, refuse dumps, animal feedlots, septic tanks and private sewage disposal systems, urban drainage and decaying plant debris. Geologic formations and direction of ground water flow also may influence nitrate concentration.
Nitrates are also found in higher concentrations in food. Vegetables such as carrots, beets and spinach contain nitrates.
Sodium nitrite is added to processed meats such as hot dogs, bacon and ham, and accounts for 60 to 90 percent of all nitrites consumed. Grain, fruits and dairy products are more or less nitrate and nitrite free.
Nitrates pose more of a health risk to young babies. This is because there is less stomach acid in infants, which leads to a higher population of nitrogen-reducing bacteria in their digestive systems. In babies younger than six months who are exposed to high levels of nitrates, nitrite in the blood combines with hemoglobin to form methemoglobin, which reduces the capability of the blood to carry oxygen to all parts of the body. This results in a blue colour to the baby’s skin, so they are known as “blue babies.” The illness can be treated, but medical attention must be prompt or the child could become starved of oxygen and die.
It is interesting that your reverse osmosis system increased the level of nitrates. I am not sure of the technical details, but I know boiling the water also increases the concentration by the process of evaporation.
Nitrates and nitrites are soluble in water so they cannot be filtered out. The only solution would be for you to use bottled water for drinking or cooking, or bring in water from a nearby city. Another alternative would be to continue to drink the water but eliminate other food sources of nitrites from your diet, and make sure no young babies drink it. Do not mix it with infant formula or juice.
For information on testing water for bacteria and nitrates, contact the nearest public health department. The service is mostly free unless you want the water to be tested for other chemicals. You will need to run the cold water tap for about five minutes before filling the bottle, and make sure that any faucet screens or filters are removed first because these can become contaminated with bacteria and skew the results.
Clare Rowson is a retired medical doctor with a practice near Belleville, Ont. Her columns are intended for general information only. Individuals are encouraged to also seek the advice of their own doctor regarding medical questions and treatments.
