Daily shower may deliver face full of germs

(Ivanhoe Newswire) -- While daily bathroom showers provide invigorating relief and a good cleansing for millions of Americans, they also can deliver a face full of potentially harmful bacteria, according to a new study from the University of Colorado, Boulder.

Researchers analyzed roughly 50 showerheads from nine cities in seven states that included New York City, Chicago and Denver. They found about 30 percent of the devices harbored significant levels of Mycobacterium avium, a pathogen linked to pulmonary disease that usually infects people with compromised immune systems, but which can occasionally infect healthy people, according to CU-Boulder Distinguished Professor Norman Pace, lead study author.

It is not surprising to find pathogens in municipal waters, said Pace. But the CU-Boulder researchers found that some M. avium and related pathogens were clumped together in slimy "biofilms" that clung to the insides 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," he was quoted as saying, "that means you are probably getting a particularly high load of Mycobacterium avium, which may not be too healthy."

Research at National Jewish Hospital in Denver indicates that increases in pulmonary infections in the United States in recent decades from so-called "non-tuberculosis" mycobacteria species like M. avium may be linked to people taking more showers and fewer baths, said Pace. 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.

Symptoms of pulmonary disease caused by M. avium include tiredness, a persistent, dry cough, shortness of breath, weakness and "generally feeling bad." Immune-compromised people like pregnant women, the elderly and those who are fighting off other diseases are more prone to experience such symptoms, said Pace.

Although scientists have tried cell culturing to test for showerhead pathogens, the technique is unable to detect 99.9 percent of bacteria species present in any given environment, Pace explained. "There have been some precedents for concern regarding pathogens and showerheads," said Pace. "But until this study we did not know just how much concern."

During the early stages of the study, the CU 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," CU-Boulder researcher Leah Feazel, first author on the study, was quoted as saying. "Then we worked up the New York data and saw a lot of M. avium. It completely reinvigorated the study."

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, said Pace. Tests on the showerhead several months later showed the bleach treatment had caused a three-fold increase in M. gordonae, indicating a general resistance of mycobacteria species to chlorine.

Previous studies by Pace and his group found massive amounts of M. avium in "soap scum" commonly found on vinyl shower curtains and floating above the water surface of warm therapy pools. A 2006 therapy pool study led by Pace and CU-Boulder Professor Mark Hernandez showed high levels of M. avium in the indoor pool environment were linked to a pneumonia-like pulmonary condition in pool attendants known as "lifeguard lung," leading the CU team into the showerhead study, said Pace.

So is it dangerous to take showers? "Probably not, if your immune system is not compromised in some way," said Pace. "But it's like anything else -- there is a risk associated with it."

Pace said since 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," said Pace. "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."

SOURCE: Proceedings of the National Academy of Sciences, September 14, 2009