WASHINGTON - In what may be the scariest shower news since Alfred
Hitchcock's Psycho, a study says showerheads can harbor tiny bacteria that come
spraying into your face when you wash.
People with normal immune systems have little to fear, but these
microbes could be a concern for folks with cystic fibrosis or AIDS, people who
are undergoing cancer treatment or those who have had a recent organ
transplant.
Researchers at the University of Colorado tested 45 showers in
five states as part of a larger study of the microbiology of air and water in
homes, schools and public buildings. They report their shower findings in
Tuesday's edition of Proceedings of the National Academy of Sciences.
In general, is it dangerous to take showers? "Probably not,
if your immune system is not compromised in some way," lead author Norman
R. Pace says. "But it's like anything else - there is a risk associated
with it."
The researchers offer suggestions for the wary, such as getting
allmetal showerheads, which microbes have a harder time clinging to. Still,
showerheads are full of nooks and crannies, making them hard to clean, the
researchers note, and the microbes come back even after treatment with bleach.
People who have filtered showerheads could replace the filter
weekly, added co-author Laura K. Baumgartner. And, she said, baths don't splash
microbes into the air as much as showers, which blast them into easily inhaled
aerosol form. It doesn't seem as frightening as the famous murder-in-the-shower
scene in Hitchcock's classic 1960 movie. But it's something to be reckoned with
all the same.
The bugs in question are Mycobacterium avium, which have been
linked to lung disease in some people.
Indeed, studies by the National Jewish Hospital in Denver suggest
increases in pulmonary infections in the United States in recent decades from
species like M. avium may be linked to people taking more showers and fewer
baths, according to Pace.
Symptoms of infection can include tiredness, a persistent, dry
cough, shortness of breath, weakness and "generally feeling bad," he
said.
Showerheads were sampled at houses, apartment buildings and public
places in New York, Illinois, Colorado, Tennessee and North Dakota.
The researchers sampled water flowing from the showerheads, then
removed them, swabbed the interiors of the devices and separately sampled water
flowing from the pipes without the showerheads.
By studying the DNA of the samples they were able to determine
which bacteria were present.
They found that the bacteria tended to build up in the showerhead,
where they were much more common than in the incoming feed water.
Most of the water samples came from municipal water systems in
cities such as New York and Denver, but the team also looked at showerheads in
four rural homes supplied by private wells. No M. avium were found in those
showerheads, though some other bacteria were.
In previous work, the same research team has found M. avium in
soap scum on vinyl shower curtains and above the water surface of warm therapy
pools.
Virginia Tech microbiologist Joseph O. Falkinham welcomed the
findings, saying M. avium can be a danger because in a shower "the
organism is aerosolized where you can inhale it."
In addition to people with weakened immune systems, Falkinham also
cited studies showing increased M. avium infections in slender, elderly people
who have a single gene for cystic fibrosis, but not the disease itself.
Two copies of the gene are needed to get cystic fibrosis, but
having just one copy may result in increased vulnerability to M. avium
infection as people age, said Falkinham, who was not part of Pace's research
team. AP
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