Features:
By Dan Vergano, USA TODAY
What's in your showerhead? Don't wanna know, do you?
Too late, you're reading this — it's disease-causing "mycobacteria" microbes stuck there in their own slime.
"Microbes are everywhere, so in fact finding
them in showers is not a surprise," says Laura Baumgartner of the
University of Colorado, Boulder, an author of the showerhead survey
study. "Finding large numbers of (disease-causing) mycobacteria was a
bit of a surprise, though."
Released Monday by the Proceedings of the National Academies of Science
journal, the study looked at 45 showerheads in nine cities, including
Denver and New York. Using standard genetic tests, the team looked for
microbes, expecting to find harmless varieties usually seen in tap
water.
They did find those, but surprisingly,
discovered about 20% of the samples contained mycobacterium, at least
100 times more than expected, according to the study. That is worrisome
because strains of the bacteria cause lung disease, and showerheads
"aerosolize" bacteria, making them easy to inhale.
Only about 1 in 4,000 people suffer from lung
diseases linked to environmental mycobacteria, says lung expert
Theodore Marras of the University of Toronto, but infections have
doubled in Ontario in the last decade, perhaps linked to more people
showering.
"Given their ubiquity in the water system, the
markedly increasing rates of infection, and the extreme difficulty in
treating them, I think that this is an important problem," he says in
an email.
"For the average person, this isn't a concern,
but people with immune (system) disease or cystic fibrosis might want
to change their showerheads every six months or so," Baumgartner says.
"The first burst of the showerhead is the most concentrated."
The study found one case where cleaning
showerheads with bleach actually lead the mycobacteria to proliferate,
suggesting they may be resistant to chlorine. "It's anecdotal, but
cleaning may paradoxically allow them to grow after other bacteria are
killed," Baumgartner says.
Microbes typically grow in "biofilms" on
surfaces, allowing them to cling to showerheads despite the onrush of
water during a shower. Biofilms grow much better on plastic, rather
than metal, showerheads.
Past studies of microbes in showerheads,
typically looking for signs of Legionnaires' disease in hospital
settings, relied on growing microbes in culture dishes, rather than
genetic markers, to identify bugs, Baumgartner says. Many microbes grow
poorly in culture, however, which is why the findings surprised the
researchers. "We need microbes to survive. Most microbes are good
ones," she adds.
To view this article online through USA Today click this link: http://www.usatoday.com/tech/science/2009-09-14-showerhead-bacteria_N.htm
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