Researchers in London estimate that if everyone routinely washed their hands, one million deaths per year could be prevented.1 Washing hands is clearly one of the best preventative measures to help avoid sickness and maintain health.
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Researchers in London estimate that if everyone routinely washed their hands, one million deaths per year could be prevented.1 Washing hands is clearly one of the best preventative measures to help avoid sickness and maintain health.
Featured: Hand Hygiene and Disease Prevention, Part I
Over the past year and a half, hand-washing has become increasingly necessary due to the COVID-19 pandemic. In addition, Salmonella, E. coli O157 and norovirus are common germs found in human and animal waste, and people can easily come into contact with these germs when using the toilet, changing a diaper and/or handling raw meats. Without hand-washing after handling these materials, germs can easily spread from human to human just by a contaminated doorknob, putting others at risk of becoming ill.2
Furthermore, according to the World Health Organization, as is well-known, hand hygiene is of the utmost importance to keep patients safe, especially in medical and health care environments.3 As a result, however, many nurses and doctors have found the skin on their hands becoming increasingly irritated due to frequent hand-washing—as have consumers overall, in light of new hyper-hygienic practices.
Washing hands multiple times a day can result in dry and cracked skin, and this outermost layer acts as a defense against the external environment and helps to maintain the moisture in the skin. Surfactants in hand cleansers, while helping to remove unwanted dirt and germs, can also, through the same mechanism, break down the outer skin barrier. This, in turn, can cause dryness, redness, itching and skin sensitivity.4 It is often recommended that consumers apply cream after washing hands, but optimizing a formulation that does not dry out the skin even after multiple hand-washing cycles would more be ideal.
Anionic surfactants are commonly found in hand cleaners as they are one of the most effective ingredients to help remove dirt and germs from the skin. Due to their effectiveness, however, as noted, they also can solubilize the lipid membrane of skin and damage stratum corneum proteins.5 By combining anionics with other surfactants, such as nonionics and amphoterics, efficient cleansing can be achieved while reducing these unwanted effects.
Surfactant Overview
Surface-active agents (surfactants) are the primary ingredient in hand cleansers. Surfactants often have both polar and non-polar parts, where the hydrophilic region may carry a charge.
This dual nature surfactants possess allows them to act as a solvent and to create micelles through surface tension activity. This trait allows a variety of characteristics and properties to emerge based on different types of surfactants.
There are four major types: anionic, cationic, amphoteric and nonionic. This piece will focus on anionics, nonionics and amphoterics, as cationic surfactants are not compatible with anionics and are not commonly found in hand cleansers.
Anionic Surfactants
Anionic surfactants contain a negatively charged hydrophilic group. Common ions found on the hydrophilic head include carboxylate, sulfate or sulfonate. This type of surfactant is great for cleansing and foaming action. Common ones found in skin care include alkyl sulfates and alkyl ethoxylated sulfates.
Related: Helping Hands: Building Soothing, Protecting, Repair and Care Products
As previously mentioned, anionic surfactants can be a bit irritating. Sulfonic acid, phosphate esters, glutamates, isethionates and taurates are slightly milder than sulfates, which are great additions to sulfates or as replacements to help reduce skin sensitivity.
Anionic surfactants generally should not be used alone—they should be used alongside amphoteric and/or nonionic surfactants to help optimize skin tolerance, foam quality and product viscosity.6
Amphoteric Surfactants
One unique surfactant molecule that theoretically contains both negative and positive charges is characterized as zwitterionic, or more commonly termed amphoteric.
Amphoteric surfactants are wonderful to boost foam, improve conditioning and reduce irritation. Amphoteric surfactants are pH sensitive. This means at low pH, they will exhibit similar conditioning properties to those found in cationic surfactants. At a high pH, they will impart characteristics similar to anionic surfactants.
This type of surfactant is great to use alongside anionic surfactants to optimize cleaning action, foaming and skin tolerance. Some examples of amphoteric surfactants include propionates, betaines and amphoacetates.6
Nonionic Surfactants
Nonionic surfactants carry no charge but obtain water solubility from polar groups such as hydroxyls and polyoxyethylene. These surfactants are a great option to help reduce skin sensitivity because they act as emulsifiers, conditioners and solubilizing agents. Since there is no charge on this type of surfactant, they are generally compatible with all other types of surfactants and are minimally affected by pH.
Some of the fatty alcohols in this category can assist in reducing irritation and imparting moisture onto the skin. Examples of nonionic surfactants include: ethoxylated fatty alcohols, alkyl polyglycosides, glyceryl esters, PEG-esters, sorbitan esters, polysorbates and fatty alcohols. Nonionic surfactants will also contribute pleasing aesthetics to the formulation.
Conclusion
Frequent hand-washing has been proven to help reduce the spread of germs and bacteria. However, this repeated practice can have adverse effects on the skin, such as redness and dryness.
As previously stated, hand-washing is extremely important but maintaining skin health is just as vital. Through the use of surfactants, products can help remove dirt, germs and bacteria while not stripping the skin. This is achieved by optimizing anionic, amphoteric and nonionic surfactant ratios to ensure the skin is effectively cleaned in a non-stripping manner.
Beyond surfactant ratio optimization, the inclusion of other ingredients such as glycerin and propanediol can help to further assist with barrier protection.
Previously: Formulating on Trend: Combining Humectants and Retinol
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