be bad for your health, say US scientists, who have shown that dirty shower
heads can deliver a face full of harmful bacteria.
nearly a third of devices harbour significant levels of a bug that causes lung
Mycobacterium avium were 100 times higher than those found in typical household
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.
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.
researcher Professor Norman Pace, said: “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
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.
develop lung infection with M. avium and experience symptoms including
tiredness, a persistent, dry cough, shortness of breath and weakness, and
generally feel unwell.
researchers swabbed and tested 50 shower heads from nine cities in seven different
states in the US, including New York City and Denver,
they found 30 per cent of the devices posed a potential risk.
shower heads appear to “load up” with more bacteria-rich biofilms,
metal shower heads may be a good alternative, said Professor Pace.
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
spokesperson said: “This is an interesting paper which provides further
information about the occurrence of opportunist organisms – germs which do not
usually cause infections in humans – in the environment.
bacteria, which belong to the same family as TB, can be found in the environment
and occasionally in water supplies but rarely cause disease in healthy people.
work will need to look at whether finding these organisms is associated with
any increased risk of infection.”