HYGIENE These were all tested following the ASTM
E1052 protocol, the standard practice to assess the activity of microbicides against viruses in suspension, to measure their efficacy in every product at typical consumer dilutions, duration of contact and other parameters. The results showed >99.9% reduction of the input value load within 20 seconds of contacts for the soap bars and liquid handwashes and within ten seconds for the hand sanitisers. Meanwhile, the virus was spreading and mutating into new variants. This raised questions about the efficacy of vaccines, since they mainly targeted the spike protein which was now mutating. Fortunately, the ingredients in personal care formulations remained effective against the variants, as they have three different broad-spectrum and mainly physical-chemical modes of action: viral protein denaturation, viral genome denaturation and bilayer disruption. However, Mukherjee said, there was still
a lot of scepticism about the performance of vaccines against the evolving strains, so many people were equally sceptical about whether soaps and sanitisers would still work. Therefore, Unilever decided to carry out the same tests again against the two variants then of most concern, the Beta and Delta variants. These again showed a >99.9% reduction in viral load across the portfolio (Figure 1). Unilever is also a major producer of oral
care products and the oral cavity is another major entry and exit point for the virus through salivary aerosols. Multiple research papers have suggested that reducing the viral load in the oral cavity can also reduce the speed of virus transmission, even though it has not formed any part of the official advice about prevention. “On the basis of the overwhelming
evidence, produced by a well-established laboratories and academics, what we proposed is that mouthwashes are capable of providing an initial layer to cut down on the
17
Figure 1: Effectiveness of Unilever products against SARS-CoV2
transmission, if and only if we can prove that ingredients in the mouthwash are capable of acting against the COVID virus,” Mukherjee said. Of course, no single layer of protection is perfect but this could add an extra one, like masks, social distancing, cleaning and disinfection. One common ingredient in mouthwashes
is the quaternary ammonium compound cetylpyridinium chloride (CPC). Previously published research has proven it to be able to destabilise viruses causing influenza and
herpes-1 and -2. Could it also destabilise SARS-CoV2 in the presence of saliva? Together with Dr Grant Hughes’ team at
the Liverpool School of Tropical Medicine, Unilever tested two proprietary mouthwash formulations containing 0.7% CPC and another with chlorhexidine against the original and later strains of the virus in the presence of saliva over a 30-second contact time. The CPC-containing formulation deactivated the tested variants below the limit of detection, whereas the chlorhexidine-containing one achieved only 1-log reduction.
150 * 100 * * 50 * * *
More than cleansing? Some believe that hand sanitisers should be able to do more than just clean. Marie Lodén, CEO of Eviderm Institute and associate professor in experimental dermatology at Uppsala University in Sweden, asked if alcohol-based hand products could be formulated in a way to deliver hydration as well as hygiene. Hitherto, they have been known to cause dryness, potentially leading to irritation and skin conditions like hand eczema. They can also change the function of the skin barrier and the biochemistry of the skin. “When you have a weak barrier function,
0 Membrane 10% urea 5% urea glycerin 20%
Lipid-rich cream
mineral oil Figure 2: Sensitivity to SLS in healthy skin treated with various creams
www.personalcaremagazine.com 40%
40% veg oil
it is easy to understand that it becomes even weaker due to the entrance of irritating substances,” Lodén noted. These include increased susceptibility to irritants and allergens and increased trans-epidermal water loss (TEWL) in those who already have sensitive skin and thus a higher vulnerability to eczema and other conditions. As has been shown by studies, soap is actually more damaging to the hands than
March 2022 PERSONAL CARE
Irritation TEWL % of control
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