Since the advent of the coronavirus, hand sanitiser has become a staple in our daily routine.
When the supermarket’s shelves quickly became depleted of this all-important new essential, people started making their own sanitiser. Along with it, came no shortage of misinformation and unproven ingredients that claim to prevent COVID-19 – from colloidal silver, Vitamin C to Aloe Vera and Red light therapy.
But here at the naked chemist, we can’t stress enough that the type of sanitiser you use, is essential because just like any science, there is an art to how an effective, well-thought-out sanitiser is put together – the formulations behind pharmaceutical products are created by qualified chemists and need to be treated with respect.
Confused? No problem we’ve got you covered – read on to find out how you can recognise a medical-grade hand sanitiser in a hugely unregulated market, so you can become your own label detective and avoid the pitfalls and those snake oils salesman.
How do our hands spread viruses?
Viruses are believed to be mostly spread via respiratory droplets — the little secretions we generate when we sneeze or cough. Small, virus-laden droplets land on the people or surfaces around them. Once the virus is on your hands, you touch your face, and the virus takes hold in your respiratory tract, via your mouth, nose, or eyes. Such is the case with the novel coronavirus, SARS-CoV-2.
What makes a sanitising product ‘sanitising’? And when is it hospital grade?
The alcohol in the formulas makes them sanitising; essentially, this means it removes dirt and micro-organisms, but a few spores may remain. For this reason, you often see claims like “kills 99.9% germs” on the packaging. Sterilisation kills all micro-organisms. These formulas are referred to as “sanitising” because they are effective on 99.9% of micro-organisms when formulated correctly.
The World Health Organisation recommendations suggest that for a formula to be effective, it must contain a combination of alcohol, glycerine, hydrogen peroxide, and sterile distilled water at set percentages:
Alcohol: Concentrations with 60-95% alcohol are most effective – specifically ethanol, isopropanol (isopropyl alcohol), n-propanol, or a combination of two of these ingredients. The coronavirus has a structure that alcohol can attack. A formula with this ratio of ingredients is proven to be effective against many types of bacteria and viruses, including HIV, influenza, and severe acute respiratory syndrome – the likes of which we see with CoVid-19. This particular virus is an enveloped RNA virus. A certain percentage of alcohol can denature and coagulate proteins, dissolving the fat membranes; very similar to the soap action against coronavirus. It is worth noting that higher concentrations of alcohol are less effective. Why? Because proteins aren’t denatured as easily without water. Water also helps slow the alcohol’s evaporation, which will happen very quickly with 100% alcohol, which means alcohol will have more time to work its magic on your skin.
Polymers: Our skin contains lipids, which are important to maintain the skin protection against germs and foreign substances. Repeated use of ingredients such as alcohol can dry out the barrier function, leading to irritation and sensitivity. When the barrier is impaired, it can allow microbes to penetrate much more easily. Polymers help get around this problem by increasing the thickness of the formula. Still, it can also improve contact time for the hand sanitiser by laying down microfilm over the skin, thus increasing contact time. Polymers also keep the skin hydrated by reducing transepidermal water loss (TEWL).
Glycerine: The presence of humectants such as glycerine is also important; these will keep the skin emollient and prevent skin from damage caused by alcohol. Don’t be surprised to see a solubiliser in your formula; ingredients like humectants and fragrances require a solubiliser, so they don’t separate over time.
Hydrogen Peroxide: The WHO also recommends adding hydrogen peroxide at 0.125 per cent in hand sanitisers, which helps to serve as an additional disinfectant. This is because hydrogen peroxide can produce free radicals that attack the fat membranes of various viruses.
What shouldn’t be in my hand sanitiser?
Many people who are formulating their own sanitiser, don’t actually realize that the inclusion of certain ingredients in their hand sanitiser might just be doing more harm than good:
- Aloe Vera can add a microbial burden, thus having a negative effect on the gel.
- Xanthan gum or other natural thickeners such as Guar gum are used, but natural agents don’t pass the rigours of testing as the synthetic polymers do.
- Preservative – when using 60% or more ethanol or isopropyl alcohol, they are ‘self-preserving’ and don’t require a preservative, as microorganisms can’t grow in these formulae.
- Quaternary Ammonium Compounds such as alkyl dimethyl ammonium chloride or benzalkonium chloride have emerged as an alternative alcohol-free hand sanitiser. However, a recent study in Germany has found that it’s not effective against the coronavirus.
- Methylated Spirits or Denatured Ethanol contains chemicals not meant for topical application and not suitable for these formulas. Only un-denatured alcohol should be used.
- Colloidal Silver is occasionally used in formulas at low concentrations because of its antibacterial and antiviral activities. Owing to a relatively smaller size of silver nanoparticles compared to SARS-CoV-2 or Covid-19, it has shown to be effective against several types of viruses including HIV, hepatitis B virus, herpes simplex virus, and influenza virus. However, at present, there is no clear evidence of its effectiveness against coronaviruses.
- Sodium Hypochlorite or Sodium Salt of Hypochlorous Acid is commonly found in household bleach which is also a useful disinfectant. Some schools of thought that say they may be effective against the virus. This is a potentially dangerous chemical, and no research has linked it to be effective against the virus.
- Citrus-based essential oils such as lemon, bergamot, grapefruit, bitter orange, or grapefruit contain a phototoxic agent that can cause eczema and other skin conditions on the skin. Citrus-based essential oils can also leave permanent stains on your skin when the formula is exposed to the sun. As discussed above, under the WHO recommendation, your product does not require additional essential oils when you use alcohol, so ensure your formula is formulated without them.
Hand Sanitisers are a lot more complex than most consumers realise. There’s a reason alcohol hand sanitiser products are regulated as drugs – formulations are more complex than you’d think and it’s super important to make sure it will actually work.
Let’s take a look at a hand sanitiser formulation: When using alcohol on a scale, it’s crucially important that the formulator is aware of the difference between weight and volume, especially if the solution’s concentration is used is labelled in volume. Alcohol is often sold by volume rather than weight. The specific gravity of ethanol, for instance, at 20° Celsius is 0.789. Essentially, what this means is that if you bought 70% v/v(un-denatured 100% ethanol) and used it to make a homemade hand sanitiser using a scale, that bottle of ethanol you are adding to the formula actually contains 55.23% w/w ethanol, not 70% w/w as you may think. Confusing, right?
Yes, there are rules. You also have to take into consideration the stability of the product, which has to satisfy the FDA’s monograph on hand sanitiser:
- microbial testing against a range of organisms
- concentration testing on the type of actives used in the formula
- human Repeat Insult Patch Test (HRIPT). This helps to verify that the formula won’t irritate, especially when repeatedly applied to human subjects over time
The take-home? Before you consider making or purchasing a DIY hand sanitiser, we recommend becoming your own label detective and using one from a reputable company, to be fully protected.