Alcohol-based hand sanitizers are one of the recommended control measures to help to reduce coronavirus infection, along with social distancing and the wearing if masks. However, excessive use of a hand sanitizer can disrupt the microbiome of the skin, which could lead to some ill-health outcomes. Furthermore, not all hand sanitizers are effective against viruses. This article looks at the issues.
Not all hand sanitizers are the same
The most commonly used alcohol-based hand sanitizers are isopropyl alcohol or a form of denatured ethanol (i.e. industrial methylated spirits), normally at a 70 percent concentration, yet not all hand sanitizers are equal and some a demonstrably substandard.
To be effective, hand sanitizers need to be formed from an effective formula (which means the absence of perfumes). According to the World Health Organization, the specification for an effective hand sanitizer is:
Alcohol (ethanol) (80% volume/volume) in an aqueous solution; or isopropyl alcohol (75% v/v) in an aqueous solution;
Glycerol (1.45% v/v);
Hydrogen peroxide (0.125% v/v); and
Sterile distilled water or boiled cold water.
As well as variances with viral elimination, According to Emerging Infectious Diseases many commercially available hand sanitizers are not all that good. The report notes: “Some products marketed to the public as antimicrobial hand sanitizers are not effective in reducing bacterial counts on hands.”
Affecting the microbiome
One of the dangers with excessive use of hand sanitizers is with eliminating too many potentially beneficial bacteria, putting the microbiome out of balance. To an extent, the microbiome of the hands is in constant flux (since hands are a vector for transmitting microorganisms between people, pets, inanimate objects and our environments). However, there is also a steady-state of normal and potentially beneficial bacteria too.
It is important to use hand sanitizer where there is no alternative, however repopulating the microbiome is important to maintain proper health. This argument in made in the International Journal of Preventive Medicine (“Bacteriological Aspects of Hand Washing: A Key for Health Promotion and Infections Control “).
A secondary concern, is with the contribution to antimicrobial resistance. A sanitizer will reduce a microbial population down, but it will not completely eliminate all of the bacteria. Those surviving cells have the theoretical capability to develop resistance. While this is with resistance to the disinfectant, the changes that take place to the genome could make the organism more resistant to other chemicals, such as antimicrobials prescribed to treat different skin conditions.
Some hand sanitizers also pose a risk of toxins entering the skin, although this will depend upon the specific type of sanitizer. With this, some regularly used hand sanitizers contain so-termed dermal penetration enhancing chemicals. These additives can increase by up to 100 fold the dermal absorption of lipophilic compounds such as bisphinol A (BPA) See: “Holding Thermal Receipt Paper and Eating Food after Using Hand Sanitizer Results in High Serum Bioactive and Urine Total Levels of Bisphenol A (BPA)”, published in PLoS One.
The best approach is to try to use hot water and soap to clean hands (applying the soap lather for 20 seconds or longer – time is a very important determinant of and cleanliness) and to use hand sanitizer products more sparingly (such as when entering stores, where there is no alternative available). It also stands that soap and hot water is more effective for eliminating the SARS-CoV-2 virus, given the enveloped nature of the virus and the ability of detergent to attack the viral envelope. In addition, some hand sanitizers are relatively ineffective at inactivating viruses.
In addition to this, a study conducted back in 2009 (obviously not specific to the current coronavirus) found that typical soap, when scrubbed on properly, is just as effective at killing potentially infectious bacteria and inactivating viruses. This study appears in Clinical Infectious Diseases: “Efficacy of soap and water and alcohol-based hand-rub preparations against live H1N1 influenza virus on the hands of human volunteers.”