Yikes. According to a study published in the current issue of Medical Hypotheses, taking showers may cause brain damage.

A couple of scientists from Wake Forest University noted that water contains trace elements of manganese. That's a metal that occurs in nature, so we're naturally exposed to it all the time; but when it enters the body in higher concentrations than normal, it can cause brain damage. The scientists hypothesized that showers would would aerosolize any manganese in the air and make it inhalable, a particularly effect way of getting the metal into your system.

So they used animal studies to calculate how much manganese a human would absorb in a 10-minute shower, multipied it by the number of people taking showers -- and average shower lengths -- and came up with some hair-raising conclusions. As Fairfax Digital reports:

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

"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. 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."

The abstract of the study is available online here.

(Thanks to Rebecca Skloot for this one!)