With the covid pandemic, handwashing was strongly encouraged (and still is). Gels and soaps have been made available. Furthermore, consumers are encouraged to use solid or bulk products. Does this increase the risk of contamination? Answer in The Conversation.
The recent Covid pandemic has turned our daily lives upside down and changed our hygiene rituals… by imposing the wearing of a mask, as well as putting hand cleaning back in the spotlight. Thus, communications from Public Health France have been reminding us again for three years of the importance of washing your hands regularly and carefully to limit the risk of infection.
Soaps and hydroalcoholic gels have at the same time reinvested in public reception areas. Legions of hands have thus taken turns at the collective distributors placed at the entrances to the stores and other solid soaps in the sanitary facilities.
At the same time, awareness of the environmental impact encourages consumers to favor solid hygiene products or products sold in bulk in order to limit packaging, particularly plastic.
Faced with these new practices, are there new risks of microbiological contamination? To what extent can hygiene products made available in a public place be infected and harm health?
Understanding these risks and their challenges involves going back over the properties and composition of hygiene products, recalling the regulations as well as the potential sources of contamination.
A bit of history: since when do we recommend washing our hands?
It was in 1847 that the doctor Ignace Philippe Semmelweis (1818-1865) demonstrated the usefulness of washing hands with soap in preventing cases of puerperal fever.
In 1961, the United States Public Health Service issued a recommendation directing healthcare personnel to wash their hands with soap and water for 1 to 2 minutes before and after contact with patients, in order to reduce spread of pathogenic microorganisms.
This is how the use of soap has spread under the influence of hand-borne epidemics such as influenza, gastroenteritis, food and community poisoning (TIAC) and more recently Covid-19. Hand hygiene considerably limits the circulation of infectious agents, consequently reducing the consumption of antibiotics – and the probability of seeing resistance appear, the management and treatment of which are difficult and costly. Despite this, this use is still too limited.
Solid, liquid, foaming: the main types of soaps
Hygiene product anchored in daily, private and medical practices, soap or rather “soaps” are now available in different forms, solid, liquid and even in the form of foam, depending on the manufacturing process and composition.
A soap is obtained by chemical reaction of saponification between a basic compound and fatty substances, oils or fats. It is the nature of the basic compound that defines the texture of the soap: solid with soda, liquid with potash.
- A solid soap is obtained by reaction of saponification of oil (olive, palm, coconut…) and soda, cold or hot. Anhydrous, its pH is basic, between 8 and 10.
- A liquid soap contains compounds obtained by saponification reaction of oil and potassium hydroxide diluted in water. Made up of a large amount of water, its pH is neutral to basic, between 7 and 9.
- A foaming gel is obtained by a conventional process of mixing different ingredients: water, synthetic or natural surfactants with cleansing and foaming properties, gelling agents and preservatives. Its pH is neutral, between 6 and 7.
Soap has constantly changed status, considered either as a cosmetic product, or as a hygiene product, an excipient or even an active substance – insofar as it could be used in preparations intended to treat scabies, burns or in purges.
Considered since the XIXe century as a medicine, it was the law of 1975 then directive 76/768 EEC (4) which reclassified soap as a cosmetic product, effectively prohibiting claims of therapeutic actions. Thus, the soap perfumes, cleans and protects the skin, helps to limit body odors but it does not heal.
Alongside consumer soaps, antiseptic soaps are medical devices. They combine a detergent and an antiseptic, which gives them cleansing and anti-microbial properties. Regulations require them to meet specific requirements in terms of bactericidal, fungicidal and virucidal efficacy, effectively excluding the risk of contamination.
Finally, the hydroalcoholic gels and solutions are biocides. Consisting mainly of distilled water and alcohol (65 to 75%), they are excellent disinfectants intended to eliminate microbes from healthy skin, with a very broad spectrum of action against microorganisms, excluding poses the risk of contamination.
Can you be contaminated by soap?
A soap’s likelihood of contamination is intrinsically linked to its composition, which determines its pH and free water content. Most pathogenic bacteria grow at a pH close to neutrality (pH~ 7) with a tolerance between 6 and 9. Conversely, an environment whose pH is very acidic or very basic slows their growth.
Solid, basic soaps therefore present a low risk of contamination. They cannot host microorganisms either in their mass or on the surface, so much so that current legislation via the ISO 29621 standard has established that the addition of preservatives was not necessary. Thus, there is no risk in using a solid soap that would drag on a sink or washbasin under conventional conditions of use.
The free water content (AW= activity of water), likely to be used by the enzymes of microbial metabolism, also has an impact on microbial proliferation. The higher the AW of a product, the more it will be conducive to the development of microorganisms. Neutral pH, with a high AW, foaming gels and liquid soaps are at risk of contamination, and that is why industrial manufacturers add preservatives to them. Their effectiveness is assessed using a normative standard test (challenge test, ISO 11930 standard), in order to guarantee that microbial growth is limited under normal conditions of storage and use during the life of the product.
Whatever the form of the soap, their industrial manufacture requires compliance with good manufacturing practices (GMP), which include microbiological controls and tests when necessary to assess the preservatives. Thus, there is no risk in using industrial soaps.
What about bulk liquid soap sales? A real challenge for the points of sale which ensure the packaging and must guarantee compliance with the regulations! They too must apply good manufacturing practices (GMP), have Product Information Files (PIF), notify the products and put their name on the labels.
Since the AGEC law on the fight against waste and the circular economy, professionals are required to accept containers from consumers as long as they are not dirty or unsuitable. The Consumer Code, article L.120-1, authorizes the bulk sale of everyday consumer products, except in exceptional cases justified by public health reasons. Article L.120-2 provides for in-store displays to inform consumers of the rules for cleaning and the suitability of reusable containers.
So much for the theory, which implies managers aware of the legislation, and special attention from the health authorities.
Very rare cases of contamination with soap
However, rare contaminations may occur. They have their origin at the industrial level, in connection with malfunctions in the production, packaging and storage processes which favor the development of strains of bacteria resistant in basic medium such as Cellulosimicrobium, Dietzia, Arthrobacter And Micrococci (whose virulent potential is little studied). The installation of air purification and water filtration equipment can bring a real benefit in eliminating this risk.
A few rare cases have been documented. Contaminations of Nesterenkonia lacusekhoensis (Micrococcus) were, for example, observed in 2016 in Canada on Castile soaps, following a change in smell. These aerobic bacteria live in extreme environments at temperatures above 30°C, alkaline hypersaline soils and waters, desert soils. Although they are not very pathogenic, the soaps were withdrawn from the market at the request of the Canadian government.
Castile soaps are specific because they are made using the cold saponification technique, which is slow and less polluting compared to the hot saponification used for Marseille and Aleppo soaps. This has made it a medium of choice for N. lacusekhoensis. However, at present, no study demonstrates the influence of the cold or hot saponification technique on the level of risk of contamination.
Other cases of contamination have been observed in dispensers of liquid soaps and foaming gels in the collective space (restaurants or public toilets). Here, it is the dispenser reloading step that is critical, insofar as it promotes pollution by faecal bacteria, some of which, such as Escherichia coli, may be responsible for gastroenteritis. To avoid this phenomenon, the health authorities recommend the cleaning and disinfection of dispensers before reloading.
In summary: the risk is very low
In summary, contamination of all these hand hygiene products is very rare, as are the risks of transmitting infectious diseases through them.
Soaps have a cleansing role and remove all organic matter on the surface of the skin, including microorganisms. Their role is therefore very different from that of hydroalcoholic products, which do not wash but disinfect (when the skin is free of dirt).
Soap remains the simplest and most effective way to prevent the spread of infections… To be used in moderation all the same, because excessive washing weakens the cutaneous microbiota and the hydrolipidic film of the skin, which will have more difficulty in fight against microbial invasions.
Selcan Tokgoz, Head of Galenic Research and Ecodesign, School of Industrial Biology (EBI) ; Delphine Hermouet, Industrial and Institutional Relations Manager, Head of the Research Committee, School of Industrial Biology (EBI) and Houda Morakchi-Goudjil, Teacher-Researcher in Biology, School of Industrial Biology (EBI)
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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