Most everyone is exposed to small amounts of manganese, a naturally occurring substance in our air, soil, water and food, daily. If kept in check, the body is able to control manganese levels by expelling extra amounts, but if the intake becomes too great, it can become overwhelming and cause a variety of health problems, including permanent nervous system damage.
What makes manganese so dangerous is that the current safety levels may not be adequate, so people may be taking in dangerous levels of this compound that almost no one is aware of.
Nearly 9 Million Americans Exposed to Dangerous Manganese Levels
According to a study by John Spangler, M.D., an associate professor of family medicine, and other researchers from Wake Forest University School of Medicine, "Nearly 9 million people in the United States are exposed to manganese levels that our study shows may cause toxic effects."
Exposure can occur via many routes, drinking water, foods, manganese-containing pesticides, air, and more, but the researchers found that the most concerning source may come from something most of us do daily: shower.
The study found that after showering 10 minutes a day for 10 years in manganese-contaminated water:
Children would be exposed to doses of manganese three times higher than doses that resulted in manganese deposits in the brains of rats.
Adults would be exposed to doses 50 percent higher than the rats.
Damage may Occur at Levels Considered Safe by the EPA
Perhaps most concerning is that permanent damage to the nervous system may occur after exposure to manganese levels that the Environmental Protection Agency (EPA) has noted as safe.
According to the EPA, 0.5 milligrams/liter is the upper limit of manganese in water supplies, based on odor and taste of the water. However, the amount of manganese accumulated by breathing in shower vapors has not been considered, and even at 0.5 milligrams/liter researchers say manganese could cause brain injury.
"Inhaling manganese, rather than eating or drinking it, is far more efficient at delivering manganese to the brain," Spangler said. "The nerve cells involved in smell are a direct pathway for toxins to enter the brain. Once inside these small nerves, manganese can travel throughout the brain."
Health Risks of Manganese
High levels of manganese are toxic to the nervous system and can cause:
According to Spangler, the elderly, pregnant women, children and people with liver disease are particularly susceptible to manganese toxicity, and may develop problems even at low doses in water supplies.
"If our results are confirmed, they could have profound implications for the nation and the world," Spangler said.
Major Sources of Manganese
People who work in, or live near, a factory that produces manganese metal are likely exposed to high levels of manganese dust in the air. Likewise, those living near a coal- or oil-burning factory are also exposed to high levels, as manganese is released into the air when fossil fuels are burned.
Manganese is also added to some gasoline, which could pose a threat to those living in urban areas, working in garages or spending a lot of time in bus stops.
Further, "The manganese, as it settles from car exhaust onto streets and highways, may enter the water supply, increasing manganese levels in the water we drink and bathe in," said Spangler.
Other potentially risky sources include:
Soy infant formula: Soybean plants may take in manganese from the soil and concentrate it. Soy formula may have 200 times the manganese level found in breast milk, which can lead to brain damage in infants and behavioral changes in adolescents, according to Dr. Francis Crinella, clinical professor of pediatrics at UC-Irvine, and Trinh Tran, a graduate researcher at the UC-Davis Department of Animal Studies.
Wells and private water supplies (may contain higher levels than public water supplies).
Reducing Your Risk of Manganese Toxicity
Manganese is a necessary nutrient that should be included in your diet. Limiting foods that contain manganese is therefore not a good idea, as toxicity from manganese in foods has not been documented. Rich food sources of manganese include whole grains, nuts, leafy vegetables and tea.
If you are concerned of your exposure to manganese via water supplies or air, however, it would be prudent to take precautions, including: