It's warm and damp and dark -- the perfect place for bacteria to nestle and stay for a while.
It turns out that that's just what they do -- in your showerhead.
What's more, says a new study, the mucky film of microorganisms lining the inside of your showerhead often harbors bacteria that can cause lung disease, including a cough, fever, fatigue and weight loss.
These mycobacteria -- close relatives of the bacterium that causes tuberculosis -- can be more than 100 times more prevalent in showerheads than in the water in the pipes just upstream, according to the research, published in Proceedings of the National Academy of Sciences.
Infections with such non-tuberculosis mycobacteria have risen in recent years, up six fold since 1997, according to another study. The bacteria don't threaten healthy people, but those with cystic fibrosis, AIDS, recent organ transplants or other immune-compromising conditions are at risk of an infection.
"There's been a growing voice in the medical field hypothesizing that showering has caused some of this increase," said the study's lead author, Leah Feazel of the University of Colorado, Boulder. "One hundred years ago, people bathed, they didn't shower."