Nov. 19, 2004 -- Candles containing certain essential oils can do more than set a mood and smell pretty. They can also kill bacteria, according to a new British study.
The finding shows a new way to destroy bacteria, such as Escherichia coli (E. coli) and Staphylococcus aureus (staph) on surfaces, say researchers Lindsey Gaunt, PhD, and Sabrina Higgins of England's University of Southampton.
Gaunt and Higgins worked on the project with John Hughes, a professor at the university's Bioelectrostatics Research Centre. They presented their study in Tokyo at the sixth joint symposium of the International Electrostatics Society of Japan and the Electrostatics Society of America.
The scientists made their own essential oil candles and tested them against the two common bacteria.
Staph and E. coli can both spread easily and cause skin infection and food poisoning respectively. There are hundreds of strains of E. coli, most of which live harmlessly in the digestive tracts of humans and animals; however, some strains produce a powerful toxin.
The scientists used essential oils of orange, palmarosa, may chang, thyme, and an element of tea tree oil called beta-pinene.
They burned each candle for one, three, or five hours in an airtight chamber containing E. coli and staph bacteria.
For comparison, the researchers also tested plain wax candles without essential oils and evaporated essential oils in water on a hot plate.
The candles containing beta-pinene and may chang did the best job of killing the bacteria. Both were almost 100% effective, virtually wiping out the bacteria.
The staph bacteria were killed within an hour, but it took five hours for the beta-pinene candle to destroy the E. coli bacteria.
The other essential oils had varying effects.
For instance, orange oil worked better against E. coli, while palmarosa was more effective against staph. That's probably due to the different chemical composition of the oils, say the researchers.
In contrast, the plain wax candle had no effect on bacteria, and vapor created by the essential oil also had little to no impact on the bacteria.
The candle flame and essential oil components appear to work together for a sterilizing effect, say the researchers.