NEW YORK (Reuters Life!) - Your shower may not be getting you as clean as you think with a U.S. study finding many showerheads are dirty and may be covering you in a daily dose of bacteria that could make you sick.
An analysis of 50 showerheads from nine U.S. cities found that about 30 percent harbored high levels of Mycobacterium avium -- a group of bacteria that can cause lung infections when inhaled or swallowed. Researchers from the University of Colorado at Boulder found the levels of Mycobacterium avium were 100 times higher than those found in typical household 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," said researcher Norman Pace in a statement.
Mycobacterium avium is linked to pulmonary disease, causing symptoms such as a persistent drug cough, breathlessness and fatigue, and most often infects people with compromised immune system but can occasionally infect healthy people.
Pace said research at the National Jewish Hospital in Denver found 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.
He said 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 problem with showerheads is that the insides provide a moist, warm, dark haven where bacteria can form sticky "biofilms" that allow them to gain a foothold and eventually set up residence in the device.
The researchers, however, said it was still probably safe for most people to get into the shower and recommended people with compromised immune systems due to HIV or immune-suppressing drugs, use metal showerheads and change them regularly.
"This really shouldn't concern average, healthy people. The main concern is for people who are immune-compromised," researcher Leah Feazel told Reuters Health. The findings, published in Proceedings of the National Academy of Sciences on Monday, are based on tests of about 50 showerheads taken from nine U.S. cities, including New York, Denver and Chicago.
The researchers said showerheads are not the only potential bacterial dispersants in the home, however.
Feazel said more research is needed to measure bacteria levels in household devices like humidifiers and evaporative coolers.
Reporting by Amy Norton of Reutres Health, Editing by Belinda Goldsmith