When you step into the shower, you may think that all you’re spraying yourself with is water. But in fact, you may also be getting showered with disease-causing bacteria, according to a University of Colorado study released Monday.


CU researchers analyzed 50 shower heads from homes, apartments and public places in Denver and eight other cities and found that about three in 10 of them contained significant levels of Mycobacterium avium, bacteria linked to pulmonary disease.

The disease caused by the bacteria most often infects people with compromised immune systems, but can also at times infect healthy people, according to CU-Boulder professor Norman Pace, the study’s lead author.

The study appears in Monday’s edition of the Proceedings of the National Academy of Sciences. Co-authors include University of Colorado at Boulder researchers Leah Feazel, Laura Baumgartner, Kristen Peterson and Daniel Frank and University of Colorado Denver pediatrics professor Kirk Harris.

The study was supported by the Alfred P. Sloan Foundation.

The bacteria were found in “biofilms” clinging to the interior of shower heads 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,” Pace said in a statement released by CU-Boulder.

He said research at Denver’s National Jewish Hospital in Denver indicates that increases in pulmonary infections in the United States in recent decades from M. avium and similar species may be linked to people taking more showers and fewer baths.

Symptoms of pulmonary disease caused by M. avium can include fatigue, a persistent, dry cough, shortness of breath, weakness and “generally feeling bad,” Pace said.

Pace said people taking showers are “probably not” at risk of getting sick unless their immune system is compromised. He added that plastic shower heads seem to “load up” with more bacteria-rich biofilms, so metal shower heads may be “a good alternative.”

Via Denver Business Journal