Smelly discovery challenges effectiveness of antimicrobial textiles

University of Alberta textiles scientist Rachel McQueen has found that anti-odor clothing may not be living up to its promise. Credit: University of Alberta

Anti-odour clothing may not be living up to its promise, and an ALES researcher is saying it could all be a matter of how the product was tested.

In two separate experiments, Human Ecology researcher Rachel McQueen and her team 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," she said.

The first experiment analyzed 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, they 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. 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.

So, for now, McQueen suggests thinking twice before trusting textile's advertised claims.

"It's just a real spectrum to how effective they may truly be. So I'd probably say, from a consumer's point of view, if you're actually buying something that says it's antimicrobial, it may not be," she said. "I think that's important to consider in relation to a lot of claims made about textiles, that is, to be skeptical about the claims marketers make."

McQueen's research was recently published in the International Journal of Clothing Science and Technology.

Source: University of Alberta

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Sampling rivers for genes rather than organisms

Conventional methods used to inventory macroinvertebrates are extremely time-consuming. Credit: Image courtesy of EAWAG: Swiss Federal Institute of Aquatic Science and Technology

Effective environmental management depends on a detailed knowledge of the distribution of species. But taxonomists are in short supply, and some species can be difficult to identify, even for experts. Eawag, in collaboration with Canton Zurich, is now pursuing a new approach for species identification, requiring no more than samples of DNA shed into the environment.

If amphipods are detected in a river, are they a threatened species, or organisms indicating good water quality? Or perhaps the first arrivals of an invasive species? Conservation and environmental management call for a detailed knowledge of species. But experts capable of identifying species under the microscope on the basis of morphological characteristics are increasingly rare. Alternative methods for water monitoring would therefore be welcome. Biologists at Eawag are now pursuing a new approach for the detection of species, involving the use of environmental DNA (eDNA). Because organisms continuously release genetic material into the environment in the form of faeces, hair or skin cells, water samples collected from a river or lake contain innumerable fragments of DNA. As long as the relevant genetic code is known, these DNA segments can be assigned to particular species, using the latest molecular biological techniques and global databases.

Cantonal authorities interested
In cooperation with the Canton Zurich Office of Waste, Water, Energy and Air (AWEL), the researchers investigated whether this method is suitable for the detection of macroinvertebrates: organisms such as mayflies, amphipods, mussels or snails are important bioindicators, used in the assessment of water quality and ecotoxicity. Water samples were collected from 14 lake and river habitats in Canton Zurich for eDNA analysis, and macroinvertebrate species collected by kicknet sampling were also determined in the conventional manner.

While the two methods did not always deliver the same results, five of the six target species were reliably detected by both methods. Especially for organisms occurring in small populations, the eDNA method appears to be more sensitive. With this approach, the rare mayfly Baetis buceratus was additionally detected at two sites where no Baetis specimens where found by kicknet sampling. According to project leader Florian Altermatt, the new method may also be suitable for the detection of invasive species at an early stage of colonization. In the US and France, it is already being tested for invasive carp species.

Long-term goal: routine monitoring of biodiversity
The eDNA method offers additional advantages. As eDNA is ubiquitous in freshwater throughout the year, the findings reflect the situation of an entire catchment, and surveillance is less time-critical. By contrast, kicknet sampling merely provides a snapshot, and for many species it can only be carried out at certain stages of the life cycle and certain times of the year. For eDNA analysis, organisms do not have to be removed from a river or lake and -- in principle -- hundreds of species can be detected at the same time. This means that continuous monitoring of freshwater biodiversity could one day become possible, just as chemical parameters are routinely monitored today.

This, however, is still a long way off: apart from the need for further refinements, the method is still costly and time-consuming. The cantons currently lack the necessary infrastructure and expertise. But Altermatt believes it will not take too long for technical standards to be established, permitting efficient operation: "eDNA analysis will then cost a few hundred Swiss francs and will be cheaper than conventional surveys." However, the new method will not wholly replace the conventional approach. Altermatt argues that the benefits of both approaches should be exploited. In addition, taxonomists will remain indispensable for validation and calibration of the new procedures.

Source:  EAWAG: Swiss Federal Institute of Aquatic Science and Technology

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