HEALTH AND SANITATION
33
“There is a fascinating microbial world
thriving in your showerhead and you can
be exposed every time you shower.”
NTM lung infection, the symptoms of which include coughing
up blood, shortness of breath, persistent coughing, fatigue,
and fever.
“Most of the bacteria that can become aerosolised and inhaled
when the shower is in use are likely harmless. However, this is
not always the case,” said study author Dr Matthew Gebert.
“These bacteria must tolerate rapid temperature fluctuations,
long intervals of stagnation or desiccation followed by high-shear
turbulent flow events, and the low nutrient and organic carbon
concentrations typical of most drinking water.
“In many cases, showerhead-associated bacteria must also
be able to tolerate residue from the chemical disinfectants –
including chlorinated compounds – which are often added to
municipal drinking water to limit bacterial contamination,”
said Gebert.
Ironically, the researchers found that incidents of the dangerous
pathogens were higher among those communities that received
their water from municipal systems as opposed to wells,
boreholes, or other sources.
“There is a fascinating microbial world thriving in your
showerhead and you can be exposed every time you shower,”
said study leader Noah Fierer in a statement. “Most of those
microbes are harmless, but a few are not, and this kind of
research is helping us understand how our own actions – from
the kinds of water treatment systems we use to the materials
in our plumbing – can change the makeup of those
microbial communities.”
In total, Fierer, a Cooperative Institute for Research in
Environmental Sciences fellow and professor of ecology and
evolutionary biology at the University of Colorado-Boulder, and
his research team, tested 656 samples from locations across
the US and Europe and found that the regions in the US where
pathogenic mycobacteria are most prevalent in showerheads are
the same regions where NTM lung infections are most common.
The study also found that metal showerheads are more
susceptible to mycobacteria overgrowth than plastic
showerheads. Plastic leaches chemicals over time that encourage
diverse bacteria, which could prevent the mycobacteria from
taking over.
The team recommends that showerheads either be periodically
replaced, or alternatively disinfected with a bag of bleach hung
on the showerhead for a few hours. PA
July 2019 Volume 25 I Number 5