Dr. John Spangler of Wake Forest University School of Medicine says breathing in small amounts of manganese dissolved in the water may harm the nervous system - even at levels normally considered safe.
Spangler says although manganese levels in public water supplies are monitored, government regulators have not considered the long-term effects of inhaling vaporized manganese while showering.
He says, "Nearly 9-million people in the United States are exposed to manganese levels that our study shows may cause toxic effects. Inhaling manganese, rather than eating or drinking it, is far more efficient at delivering manganese to the brain."
