Antibacterial soaps show no health benefits over
plain soaps and, in fact, may render some common antibiotics
less effective, says a University of Michigan public health
In the first known comprehensive analysis of whether antibacterial
soaps work better than plain soaps, Allison Aiello of the U-M
School of Public Health and her team found that washing hands
with an antibacterial soap was no more effective in preventing
infectious illness than plain soap. Moreover, antibacterial soaps
at formulations sold to the public do not remove any more bacteria
from the hands during washing than plain soaps.
Because of the way the main active ingredient---triclosan---in
many antibacterial soaps reacts in the cells, it may cause some
bacteria to become resistant to commonly used drugs such as
amoxicillin, the researchers say. These changes have not been
detected at the population level, but e-coli bacteria bugs adapted
in lab experiments showed resistance when exposed to as much
as 0.1 percent wt/vol triclosan soap.
"What we are saying is that these e-coli could survive
in the concentrations that we use in our (consumer formulated)
antibacterial soaps," Aiello said. "What it means
for consumers is that we need to be aware of what's in the products.
The soaps containing triclosan used in the community setting
are no more effective than plain soap at preventing infectious
illness symptoms, as well as reducing bacteria on the hands."
The study, "Consumer Antibacterial Soaps: Effective or
Just Risky"" appears in the August edition of Clinical
Infectious Diseases. The team looked at 27 studies conducted
between 1980 and 2006, and found that soaps containing triclosan
within the range of concentrations commonly used in the community
setting (0.1 to 0.45 percent wt/vol) were no more effective
than plain soaps. Triclosan is used in higher concentrations
in hospitals and other clinical settings, and may be more effective
at reducing illness and bacteria.
Triclosan works by targeting a biochemical pathway in the bacteria
that allows the bacteria to keep its cell wall intact. Because
of the way triclosan kills the bacteria, mutations can happen
at the targeted site. Aiello says a mutation could mean that
the triclosan can no longer get to the target site to kill the
bacteria because the bacteria and the pathway have changed form.
The analysis concludes that government regulators should evaluate
antibacterial product claims and advertising, and further studies
are encouraged. The FDA does not formally regulate the levels
of triclosan used in consumer products.
Other antiseptic products on the market contain different active
ingredients, such as the alcohol in hand sanitizers or the bleach
in some antibacterial household cleaners. Aiello's team did
not study those products and those ingredients are not at issue.