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September 15, 2009 5:00 AM PDT

Showers may be far dirtier than we think

by Elizabeth Armstrong Moore
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As if we didn't already have enough germs and toxins to deal with in our home environments (the lead in our paint; flame retardants in our furniture; indoor air quality and even the resulting air purifiers; to name a few), we now get to fret over another perpetrator: the showerhead.

Researchers at the University of Colorado at Boulder have just published a study in the Proceedings of the National Academy of Sciences finding that about 30 percent of the showerheads in nine cities (including New York, Chicago, and Denver) carry "significant" levels of Mycobacterium avium, a pathogen that is linked to pulmonary disease.

Biofilms clinging to the insides of showerheads can harbor up to 100 times the levels of pathogens found in background municipal water, according to a new University of Colorado study.

(Credit: Glenn Asakawa, University of Colorado)

Moreover, the M. avium pathogen was often clumped together with other pathogens in a slimy biofilm that clings to the insides of showerheads at more than 100 times the levels found in municipal water.

"If you are getting a face full of water when you first turn your shower on, that means you are probably getting a particularly high load of Mycobacterium avium, which may not be too healthy," says lead author Norman Pace, a distinguished professor in the Molecular, Cellular and Developmental Biology department who won the nation's highest award in microbiology in 2001, as well as a MacArthur Foundation "genius grant" for his work.

In addition, research at Denver's National Jewish Hospital suggests that the increase in pulmonary infections in the U.S. in recent decades may be the result of people taking more showers and fewer baths, Pace says. Even those who are careful never to swallow the water spurting from showerheads can inhale the pathogens, which are distributed from water droplets into the air.

Cigarette smoke is the most common cause of pulmonary disease, according to the National Heart, Lung, and Blood Institute, but general air quality also plays a role. Some 7.6 million U.S. adults were diagnosed with chronic bronchitis (a type of pulmonary disease) in 2007, according to the Centers for Disease Control and Prevention.

Symptoms of pulmonary disease that has been caused by M. avium can include weakness, shortness of breath, and a persistent, dry cough; obviously the immune-compromised, such as pregnant women and the elderly, are more prone to experience such symptoms, says Pace.

Previous studies by Pace and his colleagues have found massive enrichments of M. avium in the soap scum commonly found in places such as the surface of vinyl shower curtains. In 2006, Pace and colleague Mark Hernandez found that high levels of M. Avium in indoor pool environments led to pneumonia-like pulmonary conditions in workers known as "lifeguard lung."

Pace says that people with strong immune systems are probably in very little danger of being compromised, but he suggests that there is a higher risk associated with plastic showerheads than metal ones. And if all that isn't enough to swallow, water monitoring in the U.S., according to Pace, is "frankly archaic."

Elizabeth Armstrong Moore is a freelance journalist based in Portland, Ore. She has contributed to Wired magazine, The Christian Science Monitor, and public radio. Her semi-obscure hobbies include unicycling, slacklining, hula-hooping, scuba diving, billiards, Sudoku, Magic the Gathering, and classical piano. She is a member of the CNET Blog Network and is not an employee of CNET.
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by pjhenry1216 September 15, 2009 5:32 AM PDT
Is there any recommended best practices? Clean the showerhead more often or even before every shower? Let the shower run for a few minutes before getting in? Anything?
Reply to this comment
by Super2online September 15, 2009 5:48 AM PDT
I kept waiting for the information you seek to reveal itself as well. What good is an article like this if they can't tell you what to do to limit your exposure?
by Charleston Charge September 15, 2009 7:35 AM PDT
I think it's obvious - we should all just quit showering.
by rdupuy11 September 15, 2009 10:08 AM PDT
I always let the shower warm up before getting in, so no problems there, but my favorite shower gel is called " Oil of Mycobacterium avium" Should I be worried?
by rayzoredge September 15, 2009 5:47 AM PDT
Don't shower. You might die of pulmonary disease.

But don't take baths either. It's not green.

Air bathing in the nude. Could be good, could be bad... depending on how hot your neighbors are. =)
Reply to this comment
by Seaspray0 September 15, 2009 8:07 AM PDT
Just you wait. The surgeon general will tell us that air bathing is bad for our health because of all the smog in the air.
by rayzoredge September 15, 2009 5:51 AM PDT
Also, I don't know of anyone who gets in the shower before turning the water on.

Common sense says to warm up the water before you go in. That'll help you in this situation plus keep you from getting hit with a blast of cold water. Common sense also says to clean the showerhead once in a while...
Reply to this comment
by ballssalty September 15, 2009 6:15 AM PDT
Cleaning the shower head does nothing. The pathogen is inside the shower head. Unless you open it up there is nothing you can do. But don't let the sensationalist headline make you fret. It was found at significant levels in only 30% of shower heads in 9 cities. That means that no significant levels were in 70% of shower heads. Also they say plastic is more conducive. So those with metal shower heads (the majority I believe) should be completely fine.
by MaggieRed September 15, 2009 6:59 AM PDT
I agree, most people turn on the shower let it get to the temp you want then get in the shower.

If you want to clean the head, unscrew it and first run CLR or similar to clean out the scale, then flush/soak with bleach. Not much survives bleach.

Use Speakman models with the flow restriction removed. They are metal.
by ikramerica--2008 September 15, 2009 11:00 AM PDT
Sadly, most showerheads are not plastic, even if they have a metal enclosure.

As for not being able to clean a showerhead? Seriously? Soak it in a water+bleach solution, fully submerged. It's not rocket science...
by inachu1 September 15, 2009 5:55 AM PDT
They already said to limi the expore change your showerhead to a metal one.
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by lori_vowels September 15, 2009 6:27 AM PDT
I always let the shower run a couple of minutes before getting in.
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by nicmart September 15, 2009 6:40 AM PDT
We use a plastic snake shower head, which is probably even worse. Time to switch to a conventional metal head.
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by JLBer September 15, 2009 7:44 AM PDT
People need to look up some of George Carlin's routines about the paranoia of germs in this country. At what point do we just throw our hands up and yell, "Oh, to hell with our immune system! We don't need it as long as we have studies to tell us how to live completely sterile lives!"
Reply to this comment
by Remo_Williams September 15, 2009 7:58 AM PDT
@MaggieRed: actually, bleach is not the best biocide for cleaning water systems. Hydrogen peroxide and vinegar do a much better job at it, especially against biofilms. The acidity is the key. Moreover, if you really want to kill everything, acidify your bleach.

--#
Reply to this comment
by eswinson September 15, 2009 9:40 AM PDT
Don't put acid in bleach unless you want to create hypochlorous acid. Which is pretty deadly when inhaled.
by steven_nixa September 15, 2009 8:02 AM PDT
10 comments on this topic, 9 of them are ready to either stop showering or attempting to transform they way you do shower. Wounder how many will be seeking help in the ER, or better yet...seeking a Lawyer.
Reply to this comment
by libertyforall1776 September 15, 2009 10:01 AM PDT
Interesting. This article forgets to mention the high levels of chlorine in municipal water supplies and the benefit of a shower-head chlorine filter to reduce the inhalation of chlorine chemicals.
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by Brent212 September 15, 2009 1:21 PM PDT
Wouldn't the tap in your sink, or dispensor in your refridgerator be just as dirty as your showerhead? And people drink from those.
Reply to this comment
by setjeff15081947 September 15, 2009 6:02 PM PDT
Okay ... Everyone climb into their beds; cover themselves from head to foot; lock all the doors and windows; turn out all the lights; and don't ever move again until they cart your decaying corpse away.
There, you didn't catch anything. Whoops! You're dead!
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