Impacts of High Nitrate Levels
What are the impacts of high nitrate levels?
Although nitrate is necessary, high concentrations can be harmful to the health of the environment, as well as the economy.
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Human Health Health impacts to humans and animal life occur from drinking water, and/or eating foods high in nitrate such as vegetables and meat. In humans, pregnant women are advised to avoid high nitrate water because of research showing possible connections to birth defects and miscarriages. Also, babies under 6 months, may get a disease commonly called, Blue Baby Syndrome, or medically called Methemoglobinemia. Babies have low intestinal acidity (or a higher intestinal pH), which allows a bacteria to convert nitrate to nitrite. Nitrite is absorbed and combines with hemoglobin to form methemoglobin, which depletes the blood of oxygen. Early human symptoms include a bluish tint to fingers, lips, and other extremities. Other symptoms include headache, dizziness, lethargy, syncope, dyspnea, coma, arrhythmias, shock, and convulsions. Even with treatment brain damage or death can occur.
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| According to Kross, infants are more susceptible to nitrate toxicity for three reasons: |
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| According to a National Academy of Science study, the incidents of
Blue Baby Syndrome usually occur when nitrate-nitrogen concentrations exceed
11 ppm and when coliform bacteria contamination is also present in the
water.65
The article, Blue
Babies and Nitrate-Contaminated Well Water, investigates two
cases of babies diagnosed with Blue Baby Syndrome. 56
. (abstract
only). (Reproduced with permission from Environmental
Health Perspectives.)
However, other scientists believe the following human illness may possibly be linked to high nitrate levels: Non-Hodgkin's Lymphoma, bladder cancer, cancer in the digestive tract, diabetes, and some birth defects and miscarriages. A few recent studies have linked high nitrate to bladder cancer, especially in women. |
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| Animal Health
Ruminant livestock with multiple stomachs like cows and sheep tend to experience a similar illness to Blue Baby. Nitrate is converted to nitrite in the rumen or first stomach of livestock, which depletes the blood of oxygen. "If too much hemoglobin changes to methemoglobin, the animal will begin to show signs of a lack of oxygen: low tolerance to exercise, lack of coordination, labored breathing, blue coloring of mucous membranes, rapid heartbeat, abdominal pain and vomiting, blood discolored chocolate-brown, and abortions" 58. Thus far, no symptom or chemical diagnosis specifically points to nitrate poisoning. 58 |
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Aquatic Health
Links have also been made between high nitrate and toxicity in fish eggs, amphibian eggs, and tadpoles. Fertilizers often increase the amount of nitrate and phosphate in surface water and groundwater resulting in accelerated algae and weed growth. When the algae and weeds decay, the decomposers remove oxygen from the water, which can kill fish and other aquatic life. This process is known as eutrophication.
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Economic Health
Additionally, the economy can be negatively impacted as demonstrated by the following examples.
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The DNR website has more information on impacts of nitrate in drinking water.
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