Health Effects of Nitrate in Drinking Water
Sarah Yang, Ph.D. Groundwater Toxicologist February 26, 2020 High levels of nitrate can affect everyone’s health.
2 Nitrate is one of the most common contaminants in Wisconsin's groundwater.
3 Our major source of nitrate depends on age. 4 When we eat or drink nitrate, it goes through our body to our small intestine.
5 Most nitrate is absorbed in our blood.
6 While most nitrate in our blood leaves our body when we urinate, about 25% goes into our saliva.
7 Intestines Blood
Stomach
In saliva, most nitrate goes back through the intestines, but some is turned into nitrite and moves to the stomach. 8 In the stomach, nitrite can move into the blood or be turned into other substances.
Blood Beneficial substances Harmful substances
9 Nitrite in the blood can affect the body’s ability to transport oxygen. Nitrite
Fe2+ Fe3+ Hemoglobin Methemoglobin
10 1 Normal High levels of 3 Skin discoloration methemoglobin 10 Weakness, excess heart rate 20 Headache, dizziness, fatigue, can cause nausea health problems. 70 Death (very rare) % methemoglobin in the blood 11 Adapted from Shihana, F. et al (2010) High levels of nitrate can cause blue baby syndrome (methemoglobenemia) in infants.
12 Infants are at a greater risk for blue baby syndrome because of their size and how their bodies work.
13 The drinking water standard for nitrate is 10 mg/L.
14 Level of nitrate-nitrogen in formula (mg/L) ≤ 10 00
11–20 5
21–50 36
51–100 81
> 100 92 Cases of blue baby syndrome 15 The United States uses a different measure of nitrate than other countries.
Nitrate-Nitrogen Nitrate United States 10 mg/L 45 mg/L Europe 11 mg/L 50 mg/L
16 High levels of nitrate can also affect women who are or may become pregnant. 17 High levels of nitrate in drinking water may increase the incidence of neural tube defects.
18 Neural tube defects can occur in the first 3 weeks of pregnancy.
19 High levels of nitrate in drinking water can cause long-term health effects in everyone.20 Recent studies among people have evaluated the health effects of high nitrate in drinking water. Strongest Evidence
Thyroid disease Colon cancer 21 High levels of nitrate may affect the thyroid by blocking iodine uptake.
Iodine (from diet) T3
Nitrate (hormone)
Hypothyroidism
Thyroid T4
(hormone) 22 Nitrite can form N-nitroso compounds in the stomach – some of which have been shown to cause cancer in research animals.
Harmful substances (N-nitroso compounds)
2 3 Take action to protect yourself and your family
24 Test your well for nitrate at least once a year.
25 When nitrate levels are high: Do not give water to babies less than 6 months old or used to make infant formula.
Women who are or may become pregnant should immediately stop using the water for drinking and preparing foods that use a lot of water. 26 Everyone should avoid long-term use of the water for drinking and preparing foods that use a lot of water.
27 Thanks!
Sarah Yang, Ph.D. Groundwater Toxicologist Bureau of Environmental and Occupational Health Division of Public Health Wisconsin Department of Health Services
[email protected] 608-266-9337
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