10:06pm UK, Sunday July 03, 2005

Taking regular showers could pose a health risk and even result in permanent brain damage, it has been claimed.

Scientists believe that breathing in small amounts of manganese dissolved in the water may harm the nervous system.

180 gen shower woman

The damage may occur even at levels of the naturally occurring metal normally considered safe, say the US researchers.

Although manganese levels in public water supplies are monitored, regulators have not considered the long-term effects of inhaling vaporised manganese while showering, they claim.

Dr John Spangler, from Wake Forest University School of Medicine in Winston-Salem, New Carolina, who led the study, said: "If our results are confirmed, they could have profound implications for the nation and the world.

"Nearly nine 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."

Dr Spangler's team calculated from animal studies the amount of manganese people would absorb by showering for 10 minutes a day.

After 10 years of showering in manganese-contaminated water, children would be exposed to levels of the metal three times higher than the doses needed to leave deposits in rats' brains, the researchers found.

Adults with a longer history of showering could be exposed to doses 50% higher.