It may sound unbelievable, but the toilet seat is more hygienic than most other surfaces in the home, including kitchen chopping boards, tap handles and sinks.

Pat Rusin and her colleagues at the University of Arizona in Tucson monitored the bacteria living in 15 Tucson homes. In the final third of the 30-week study, Rusin's team gave the homeowners household bleach and drilled them on how best to keep surfaces clean.

The team took swabs from 14 sites in kitchens and toilets, including sink surfaces, fluids wrung from dishcloths, tap handles and kitchen worktops. "What we found, and we are still theorising as to why, is that even before we introduced any disinfectant, the toilet seat was always the cleanest site," says Rusin.

The most likely explanation, she says, is that toilet seats are simply too dry to support a thriving population of bacteria, which tend to prefer damp environments.

At the start of the study, the researchers found a million times as many bacteria in the fluid wrung from dishcloths as on toilet seats. Even chopping boards hosted three times as many bacteria.

There was a dramatic improvement in kitchen hygiene when bleach was introduced, however. "We went from 100 000 bacteria per millilitre of fluid coming out of the dishcloth to just 10," says Rubin, whose team will publish its results in a future issue of the Journal of Applied Microbiology.

Rubin's advice is to clean dishcloths at least once a week. "Simply add one cup of bleach to a sinkful of water, throw in the dishcloth and let it soak for 10 minutes before letting it drain," she says. Worktops, sink surfaces, chopping boards and tap handles should be cleaned daily, and the toilet bowl three times a week.

Author: Andy Coghlan

New Scientist issue 13 June 1998, page 21

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Contact: Claire Bowles
claire.bowles@rbi.co.uk
44 171 331 2751
New Scientist
10-Jun-1998