Over the past few years, hand-washing has become increasingly necessary due to the COVID-19 pandemic. In addition, salmonella and norovirus are commonly found in human and animal feces that people are easily exposed to when using the toilet, changing diapers, and tackling raw meat. Without washing your hands after handling these materials, germs can easily be spread from person to person through contaminated doorknobs, putting others at risk of getting sick.
Additionally, according to the World Health Organization, hand hygiene is known to be critical to ensuring patient safety, especially in medical and healthcare settings. However, as a result, many nurses and doctors are finding that their hands are becoming sensitive due to frequent hand-washing.
Washing your hands many times a day can make your hands dry and crack, and this outermost layer acts as a barrier against the external environment and helps retain moisture in the skin. While the surfactant in hand sanitizers helps remove dirt and bacteria, they can also break through the skin’s outer barrier through the same mechanism. This, in turn, can lead to dryness, redness, itching, and skin sensitivity. People are generally advised to apply cream after washing their hands, but optimizing a formula that won’t dry out the skin even after multiple hand-washing cycles would be ideal.
Surfactants are commonly found in hand sanitizers because they are one of the most effective ingredients in helping to remove dirt and bacteria from the skin. However, due to their effectiveness, as mentioned above, they can also dissolve the skin’s lipid membrane and disrupt stratum corneum proteins. By combining anionic surfactants with other surfactants such as nonionic and amphoteric surfactants, efficient cleaning can be achieved while reducing these undesirable effects.
Surfactant Overview
Surfactant is the main ingredient in hand sanitizer. Surfactants typically have a polar part and a non-polar part, where the hydrophilic region may be charged.
This dual nature of surfactants allows them to act as solvents and create micelles through surface tension activity. This property allows for the emergence of various properties based on different types of surfactants.
There are four main types: anionic, cationic, amphoteric, and nonionic. This article will focus on anionic, nonionic, and amphoteric surfactants because cationic surfactants are incompatible with anionic surfactants and are not commonly found in hand sanitizers.
Anionic Surfactant
Anionic surfactants contain negatively charged hydrophilic groups. Common ions found on the hydrophilic head include carboxylate, sulfate, or sulfonate. This type of surfactant is great for cleaning and lathering. Common ones found in skin care include alkyl sulfates and alkyl ethoxylated sulfates, such as SLS SLES.
As mentioned before, anionic surfactants can be a bit harsh. Sulfonic acids, phosphates, glutamates, isethionates, and laurates are slightly milder than sulfates and are great supplements to sulfates or alternatives to help reduce skin sensitivity.
Anionic surfactants generally should not be used alone – they should be used with amphoteric and/or nonionic surfactants to help optimize skin tolerance, lather quality and product viscosity.
Amphoteric Surfactants
A unique type of surfactant molecule that theoretically contains both negative and positive charges is characterized as a zwitterion, or more commonly known as amphoteric.
Amphoteric surfactants are great for increasing lather, improving conditioning and reducing irritation. Amphoteric surfactants are pH-sensitive. This means that at low pH they will exhibit similar conditioning properties to cationic surfactant. At high pH, they will impart properties similar to anionic surfactant.
This type of surfactant is ideal for use with anionic surfactant to optimize cleansing action, lathering and skin tolerance. Some examples of amphoteric surfactants include propionate, betaine, and amphoteric acetate.
Nonionic Surfactant
Nonionic surfactants are uncharged but gain their water solubility from polar groups such as hydroxyl groups and polyoxyethylene. These surfactants are excellent choices for helping reduce skin sensitivity because they act as emulsifiers, conditioners, and solubilizers. Because these surfactants are uncharged, they are generally compatible with all other surfactant types and are minimally affected by pH.
Some fatty alcohols in this category can help reduce irritation and provide moisture to the skin. Examples of nonionic surfactants include ethoxylated fatty alcohols, alkyl polyglycolide, glycerides, PEG-esters, sorbitan esters, polysorbates and fatty alcohols. Nonionic surfactants will also bring a pleasing aesthetic to the formulation.
Conclusion
Regular hand washing has been proven to help reduce the spread of bacteria and viruses. However, this repetitive action can have adverse effects on the skin, such as redness and dryness.
As mentioned before, washing your hands is extremely important, but keeping your skin healthy is equally important. By using surfactants, products can help remove dirt, viruses, and bacteria without stripping the skin. This is achieved by optimizing the ratio of anionic, amphoteric and nonionic surfactants to ensure effective skin cleansing in a non-stripping manner.
In addition to surfactant ratio optimization, the inclusion of other ingredients such as glycerin and propylene glycol can help further assist with barrier protection.
