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Which smells worse...
cotton or synthetic?
The Science of Stinky Shirts
Everyone knows not to leave gym clothes in a bag or locker too long - do this and you'll risk clothes so stinky you'd rather just throw them out than waste time washing away the stench.
However, you may have noticed that some clothes stink less than others, such as clothing made from cotton. On the other hand, synthetic materials like polyester tend to harbor odors, even after repeated washing. So what makes the difference?
Researchers at Ghent University in Belgium set out to determine both the cause of malodor and why it persists on synthetic fibers more than cotton.
In a study published in
Applied and Environmental Microbiology
in August, twenty-six subjects wearing natural
or synthetic fibers participated in an hour-long spin class, after which they deposited their workout gear in plastic bags and stored them in the dark-conditions analogous to tossing the workout clothes in a gym locker. Twenty-eight hours later, the shirts were sniffed by a trained team of odor connoisseurs and rated for their stench.
It turns out, synthetic shirts stank more than shirts made of natural fibers. On a scale from -4 (very unpleasant) to +4 (very pleasant), the cotton shirts achieved a score of -0.61±1.08 while the polyester shirts achieved a score of -2.04±0.90 - that's a serious (and significant) difference in stink.
To find out what was causing the increased smell on synthetic shirts, scientists swabbed the armpit regions of subjects and found abundant populations of
Micrococcus
spp. Interestingly, these organisms are not found in abundance on armpit skin, but conditions on synthetic shirts appear to promote their growth.
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Micrococcus luteus
colonies on a blood agar plate.
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So what causes the smelly odors that stick to these synthetic fibers?
Human axillary cells secrete non-volatile
,long-chain fatty acids that have no natural odor. However, the Micrococci found more abundantly in the looser, more airy weave of synthetic fibers than in the tighter weave of cotton are capable of breaking down these molecules into shorter, more volatile compounds that make us wrinkle our noses.
To explore this idea further, the team took a few pungent species of bacteria and tried growing them in Petri dishes coated with seven different fabrics: polyester, acryl, nylon, fleece, viscose, cotton, and wool.
The results were mixed. Cotton grew very few smelly germs, akin to earlier findings, while the microbes continued to swarm over polyester.
These findings may help clothing manufacturers produce clothing that is both breathable and cool, but limits microbial growth by strategically placing different weaves of fibers in different areas of the garment.
by Raquel Kahler
Reference
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