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BEST OF 2009: Are you sick and clean?

U. COLORADO (US)—Millions of Americans are getting a dousing of pathogenic bacteria along with their daily showers, a new study finds. Researchers have discovered that water spurting from showerheads can distribute pathogen-filled droplets that suspend themselves in the air and can easily be inhaled into the deepest parts of the lungs.

The findings by a team from the University of Colorado at Boulder indicates that increases in pulmonary infections in the United States in recent decades from so-called “non-tuberculosis” mycobacteria species like Mycobacterium avium may be linked to people taking more showers and fewer baths, says the study’s lead author Norman Pace.

For the study, researchers used high-tech instruments and lab methods to analyze roughly 50 showerheads from nine cities in seven states that included New York City, Chicago, Denver, Tennessee, and North Dakota. They concluded about 30 percent of the devices harbored significant levels of M. avium, a pathogen linked to pulmonary disease.

It’s not surprising to find pathogens in municipal waters, Pace says, but some M. avium and related pathogens were found clumped together in slimy “biofilms” that clung to the inside of showerheads at more than 100 times the “background” levels of 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,” he explains.

Symptoms of pulmonary disease caused by M. avium can include tiredness, a persistent, dry cough, shortness of breath, weakness, and “generally feeling bad,” says Pace, a professor in the molecular, cellular, and developmental biology department. Immune-compromised people like pregnant women, the elderly and those who are fighting off other diseases are more prone to experience such symptoms.

“There have been some precedents for concern regarding pathogens and showerheads,” says Pace. “But until this study we did not know just how much concern.”

During the early stages of the study, the team tested showerheads from smaller towns and cities, many of which were using well water rather than municipal water.

“We were starting to conclude that pathogen levels we detected in the showerheads were pretty boring,” says first author Leah Feazel. “Then we worked up the New York data and saw a lot of M. avium. It completely reinvigorated the study.”

In addition to the showerhead swabbing technique, Feazel took several individual showerheads, broke them into tiny pieces, coated them with gold, used a fluorescent dye to stain the surfaces and used a scanning electron microscope to look at the surfaces in detail. “Once we started analyzing the big metropolitan data, it suddenly became a huge story to us,” she says.

In Denver, one showerhead in the study with high loads of the pathogen Mycobacterium gordonae was cleaned with a bleach solution in an attempt to eradicate it, says Pace. Tests on the showerhead several months later showed the bleach treatment ironically caused a three-fold increase in M. gordonae, indicating a general resistance of mycobacteria species to chlorine.

Pace says a 2006 therapy pool study in which high levels of M. avium in indoor pool environments was linked to a pneumonia-like pulmonary condition known as “lifeguard lung” led to the current study.

So is it dangerous to take showers? “Probably not, if your immune system is not compromised in some way,” says Pace. “But it’s like anything else—there is a risk associated with it.”

Because plastic showerheads appear to “load up” with more pathogen-enriched biofilms, metal showerheads may be a good alternative.

“There are lessons to be learned here in terms of how we handle and monitor water,” Pace concludes. “Water monitoring in this country is frankly archaic. The tools now exist to monitor it far more accurately and far less expensively that what is routinely being done today.”

The study appeared in the Sept. 14 online edition of the Proceedings of the National Academy of Sciences and was supported by the Alfred P. Sloan Foundation.

University of Colorado at Boulder news: www.colorado.edu/news

chat11 Comments

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11 Comments

  1. Doug Alder

    “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,

    So does that mean it’s safer if you turn the shower on and let it run for a minute or so before getting in?

  2. jon

    If not bleach, what can I spray on my showerhead? Is it safe to remove the showerhead for cleaning?

  3. Dave

    I read about this in an article on WebMD last week.
    http://www.webmd.com/lung/copd/news/20090914/bacteria-may-lurk-on-your-showerhead

    “So does that mean it’s safer if you turn the shower on and let it run for a minute or so before getting in?”

    That seems to be the advice from both authors Norman Pace and Laura K. Baumgartner.

    “”Run your shower for a minute or so before you get in, otherwise you’ll get a face full of bacteria.””
    from:
    http://www.newscientist.com/article/dn17786-shower-heads-make-a-perfect-home-for-bugs.html

    and

    “For most people, though, the simplest thing is not to stand in front the spray at the start, said Baumgartner.
    The first full blast in the face probably means you’re getting showered with a high load of M. avium, she said. “But most people don’t do that anyway because that first blast is cold.”
    from:
    http://seattletimes.nwsource.com/html/health/2009866955_shower15.html

    “If not bleach, what can I spray on my showerhead? Is it safe to remove the showerhead for cleaning?”

    To, again, quote Pace: “”Cleaning the showerhead is a reasonable thing to do.””
    from the WebMD article.

    Many I’ve seen/used can be taken apart and cleaned. I’ve normally used a mild ammonia solution in the past, rinsing well afterward.

  4. Brian

    This is great progress in a problem well stated, but it of course does an awful job of explaining how to reduce M. avium or the effect of it other than abandoning shower heads. Chlorine was the only attempt to rid of it? This may explain the fear mongering here: “supported by the Alfred P. Sloan Foundation.” We’ll wait for the next product roll-out!

  5. Peter

    This observation is completely meaningless. Everyone turns on the shower and let it run until the water temperature gets adjusted, ample time to clean the shower head. Also, even in the unlikely case of getting bacteria on the head, in the process of showering (soap and rinse) they would get washed away.

  6. Ryan

    To Peter’s comments
    This is not meaningless. Not everyone lets the shower run to adjust the temperature before getting in. I run the bath water to the right temperature and then pull the shower, thus resulting in the initial burst to my body.
    The process of showering would was away the bacteria, but the concerns mentioned in the article are regarding inhalation.

  7. Tektrix

    Would be good to know if M. avium and M. gordonae (and other similar pathogens) are eradicated or diminished by anti-microbial metals such as copper and silver. Many bathroom fixtures are made of brass (which contains copper), so perhaps some shower heads naturally reduce the populations of these microbes.

  8. Brian

    On second thought, that is too being too critical of a foundation that does fund some great studies with no apparent motive. Thanks for the release about this!

  9. Josh

    “Everyone turns on the shower and let it run until the water temperature gets adjusted, ample time to clean the shower head. ”

    That may be, and disputed by Ryan above, but the article states that the pathogens become airborne after the initial gush of water. Unless you have a super fan above your shower/bath sucking up all the air, you are still breathing it in.

    I wonder if cleaning with CLR or LimeAway, adds a coating to prevent, or at least delay, the growth of bacteria.

  10. jon

    Peter, the danger here is not getting the bacteria on your skin, the danger is inhaling the bacteria via breathing in tiny water droplets produced by the showerhead.

  11. russ

    One should consider whether the level of supposed bacterial/microbe intake is any different than that one is exposed to when walking around the home, workplace, or neighborhood park…

    Too many studies purport to reveal things about a specific problem that in reality are not all that different than the rest of the environment.

    The human body ingests bacteria all the time, through the skin and through our lungs. If one follows Mom’s advice of “everything in moderation”, eats a healthy diet, and exercises, the body will manage itself most of the time.

    Maintaining a reasonably clean living environment is part of “everything in moderation”.

    Pay attention to the causes of accidents and deaths in the newspaper. A large percentage of things happen when someone has gone to excess.

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