"If our results are confirmed, they could have profound implications for the nation and the world,” said John Spangler, M.D., an associate professor of family medicine from Wake Forest University School of Medicine. "Nearly nine million people in the United States are exposed to manganese levels that our study shows may cause toxic effects.”
The study is the first to show the potential for permanent brain damage from breathing vaporised manganese during a shower. It was conducted by reviewing the medical literature and calculating, based on animal studies, the amount of manganese people would absorb by showering ten minutes a day.
At higher levels, manganese is toxic to the central nervous system and can cause learning and coordination disabilities, behavioural changes and a condition that is similar to Parkinson's disease. Children, pregnant women, the elderly, and patients with liver disease are at highest risk from manganese toxicity. Some of these groups have developed manganese poisoning even at fairly low doses in their water supplies, Spangler said.
The Environmental Protection Agency (EPA) has set 0.5 milligrams/liter as the upper limit of manganese advisable in water supplies. In their analysis, Spangler and Elsner found that concentrations well below 0.5 milligrams might lead to brain injury.
"Inhaling manganese, rather than eating or drinking it, is far more efficient at delivering manganese to the brain,” said Spangler. "The nerve cells involved in smell are a direct pathway for toxins to enter the brain.”
Elsner and Spangler extrapolated data from rodents to estimate human exposure to manganese during showering. They found that after ten years of showering 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 rodents.
MEDICA.de; Source: Wake Forest University Baptist Medical Center