Anti-odour clothing may not be living up to its promise, and it could all be a matter of how the product was tested, scientists say.
In two separate experiments, researchers found that some antimicrobial textiles were far more effective at performing their advertised tasks in the lab than in testing on humans.
In one experiment, the fabrics were designed to help lower the risk of infection; in the second, the fabric was treated with a silver compound, which can be marketed preventing odour in clothing.
"We aren't necessarily seeing the same results in the lab about antimicrobial activity translating into antimicrobial activity when we're wearing them next to our bodies in real life," Rachel McQueen, Human Ecology researcher at the University of Alberta said.
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The first experiment analysed the effectiveness of three different textiles coated in antimicrobials triclosan, a zinc pyrithione derivative and a silver chloride-titanium dioxide compound.
After putting the fabric on people's arms under plastic film for 24 hours, the silver-chloride titanium dioxide compound hardly eliminated any bacteria.
Overall, the researchers found the in vivo tested on humans results were not comparable with in vitro - tested in the lab results in how they prevented microorganisms from surviving in the textile.
The second test had similar results, and tested whether polyester textiles treated with bioactive concentrations of an antimicrobial silver chloride compound reduced armpit odour and bacterial populations.
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Although lab testing showed antimicrobial activity, the treated fabrics did not lower odour or bacterial intensity in in-vivo testing.
McQueen said that anything from sweat to the proteins in the human body can disrupt the antimicrobial properties of a fabric.
"In reality, when it goes to the point that it gets put on a textile... it may not have the same level of effectiveness as the ones they studied," she said.
McQueen said these findings highlight the importance of in vivo testing, which is less common than in vitro testing, in textile product development.
But, because the textiles appear to be effective at reducing bacteria in the lab, she said they may be advertised as being anti-odourous, although they may not necessarily be so when actually worn.
The research was published in the International Journal of Clothing Science and Technology.