Antibacterial soaps containing the chemical triclosan are no better at removing bacteria from your hands than conventional soaps, a new study has concluded. This raises questions about the necessity of using the chemical, which has been labeled as potentially dangerous, in antibacterial soaps.
The antibacterial soap market is big business, worth an impressive $1 billion (£647 million) annually in the United States alone. Yet the most widely used antiseptic agent in these soaps, triclosan, has been linked to antibiotic resistance, allergies, and interference with the hormone system in mammals. Worryingly, one study even found potential carcinogenic, or cancer-causing, risk. These potentially harmful effects have even prompted the U.S. Food and Drug Administration to look into its safety, and possibly restrict its use.
The study, published in the Journal of Antimicrobial Chemotherapy, looked at its effect on 20 dangerous bacterial strains, including Escherichia coli, Listeria monocytogenes, and Salmonella enteritidis. They placed them in Petri dishes with either the antibacterial or normal soap and heated them to 22 degrees Celsius (72 degrees Fahrenheit) or 40 degrees Celsius (104 degrees Fahrenheit), simulating exposure to warm or hot water, for 20 seconds.
In addition to this experiment, they then went on to test the antibacterial soap in real life so to speak, rather than in the lab. Volunteers had their hands coated with the bacteria Serratia marcescens (a species often found in bathrooms), and were then asked to wash their hands for 30 seconds, again using either conventional or antibacterial soap containing 0.3% triclosan, the maximum allowed in products sold in the E.U., Canada, Australia, China and Japan.
After failing to find a difference in bactericidal effect between the soaps, the researchers looked to see just how long it would take for triclosan to kill bacteria. Using the same concentration as before, they found that it was only effective if the microorganisms were allowed to soak in it for over nine hours.
The researchers suggest that people buying antibacterial soaps should be made aware that they might not be as effective as claimed during normal hand-washing conditions. “It should be banned to exaggerate the effectiveness of… products which can confuse consumers,” said Min Suk Rhee, who coauthored the study.