Adding an essential oil to WHO Handrub Formulation

Question

I'm not a chemist, so I prefer to ask this question to some people, who definitely have knowledge in that area.

WHO Handrub Formulation is available here. Ingridients: Ethanol 96%, Hydrogen peroxide 3%, Glycerol 98%, Sterile distilled or boiled cold water.

I would like to use it to produce 4l of handrub (I have 92% alcohol, and I re-calculated needed amounts). Can I also add some essential oil to the formula? Only few drops or more ~10 ml?

For example:

• Orange, ingridients: citrus aurantium dulcis peel oil expressed, linalool, citral
• Spruce, ingridients: limonane, linalool, geraniol. INCI: oleum picea excelsa
• Pine, ingridients/INCI: oleum phus silvestris
• Lavender, ingridients/INCI: lavandula angustifolia oil, linalool, limonene

I just want to make sure that the final substance wouldn't be irritating to the hands nor cause any allergies etc. I also found this paper, where they added Piper nigrum Essential Oils to the formula.

Thank you for suggestions.

Answer 1

The WHO formulae are tested formulations against micro-organisms. You don't mention whether you have hydrogen peroxide but that is added to kill microbial spores that have contaminated your anti-septic solutions.

The issue then is whether adding something else improves or reduces the efficacy of the formulation. Although some essential oils have been shown in studies to have anti-viral properties I was not able to find any study of these against the SARS-CoV-2 virus which I presume is the reason you are making this up.

The SARS-CoV-2 virus is also encapsulated with a lipid layer or fatty layer, and we have no information on whether essential oils can help protect the virus or disrupt it.

Therefore, it is advised that in this time where we lack the data we should not alter the WHO formulation.

There is a lot more reading on this topic here