Showering may be bad for your health, say US scientists, who have shown that dirty shower heads can deliver a face full of harmful bacteria.
Tests revealed nearly a third of devices harbour significant levels of a bug that causes lung disease. Levels of Mycobacterium avium were 100 times higher than those found in typical household water supplies. M. avium forms a biofilm that clings to the inside of the shower head, reports the National Academy of Science.
In the Proceedings journal , the study authors say their findings might explain why there have been more cases of these lung infections in recent years, linked with people tending to take more showers and fewer baths. Water spurting from shower heads can distribute bacteria-filled droplets that suspend themselves in the air and can easily be inhaled into the deepest parts of the lungs, say the scientists from the University of Colorado at Boulder.
[...] While it is rarely a problem for most healthy people, those with weakened immune systems, like the elderly, pregnant women or those who are fighting off other diseases, can be susceptible to infection. They may develop lung infection with M. avium and experience symptoms including tiredness, a persistent, dry cough, shortness of breath and weakness, and generally feel unwell.
[...] Since plastic shower heads appear to “load up” with more bacteria-rich biofilms, metal shower heads may be a good alternative. Showers have also been identified as a route for spreading other infectious diseases, including a type of pneumonia called Legionnaires’ disease and chest infections with a bacterium called Pseudomonas aeruginosa.
Hot tubs and spa pools carry a similar infection risk, according to the Health Protection Agency.
 Feazela, L.M. …[et al.] (2009). Opportunistic pathogens enriched in showerhead biofilms. PNAS. Published online before print 14 Sep 2009, doi:10.1073/pnas.0908446106
Source: BBC, 14 Sep 2009