Coronavirus: low-cost and low environmental impact disinfectant for virus control
We often see on our screens, the massive disinfection carried out by several governments to eradicate the COVID-19 from the streets and public transport. Even children now know that the virus survives for several hours on metal or plastic surfaces, even without a host. There are those who say that disinfection is not necessary, those who say that it is impossible without it, those who point the finger at their environmental damage. In fact, as experts frequently advise, the most important thing is to wash your hands often and well, because they are the major vehicles for transporting the virus from the external environment to the internal environment.
I can explain how the normal soap can destroy such a dangerous virus: coronaviruses are classified as enveloped viruses, and the lipid layers that make up this envelope are extremely sensitive to heat and detergents. That’s why, even though it is of no scientific value, I would like you to know that I do not use any disinfectant; I am often at home and when I come back from shopping or sunbathing I just wash my hands with soap and water (I do not take public transport and so on). But I am aware that we are all different individuals and some of us unfortunately have pathologies that may require special attention.
So in certain cases, disinfecting our homes, our purchases, the packages we receive, our clothes, but also our shoes (we always take off our shoes before entering the house) can be a good rule, especially for those with weak immune systems.
Which products should I use as a disinfectant for virus control?
When experts have to advise which products to use, they mention the names of the brands, because these have already been tested, verified and certified, and in compliance with the law they are able to perform their task of reducing the microbiological charge, formed by bacteria, fungi and viruses on surfaces. But that does not mean, that only these brands work for disinfection from viruses or from microorganisms in general.
So here are 3 alternatives that are certainly already present in your homes, they do not cost much and are just as effective for the purpose:
1) Hydrogen peroxide, i.e. oxygen water.
It is the first on the list not because it is more efficient than the others, but it is much more environmental friendly and costs very little.
Oxygen water is normally sold at a concentration of 3%, so it must be diluted to 0.5% to obtain an adequate disinfectant effect on surfaces: to dilute it, 1 unit of product (100 ml) must be mixed with 4 units of water (400 ml). It has a contact time of 1 minute, which can be very practical in many cases (1). In a scientific article states that the hydrogen peroxide is a valid solution for the deactivation of viruses such as rhinoviruses, influenza A and B, adenoviruses 3 and 6, and coronaviruses 229E; the article also specifies that influenza viruses and coronaviruses are the most sensitive to this solution(2).
2) Rubbing alcohol.
It comes second because it is efficient, has an average cost and a relatively low environmental impact.
The main focus should be on its concentration. The CDC (Centers for Disease Control and Prevention) experts recommend using only those with a concentration above 70%. Alcohol that you can buy has a concentration of over 90% (on this concentration it is highly volatile); to lower this value to valid levels required for disinfection, simply mix 2 glasses of alcohol (400 ml) with ½ glass of water (100 ml). You should let it react to inactivate the viruses before being removed, the required contact time takes just 30 seconds to get the desired effect. But you should also know that prolonged and repeated use of alcohol as a disinfectant can also cause discoloration, swelling, hardening and cracking of rubber and certain plastics (3).
3) Chlorine compounds i. e. bleach.
It is very efficient disinfectant for virus control and it costs very little but is in third place because it damages highly the environment: during its production, and after usage during its disposing. My advice is that if you do not seriously risk infection, do not opt for this product. It is also highly irritant for the respiratory track.
After diluting (1:50), you can use it successfully. The dilution should be done with one part of disinfectant and 49 parts of water, i.e. 10 ml of bleach diluted with 490 ml of water in a 1 liter container (4) (for sanitation, dilute 1 glass of bleach with 3 glasses of water, and wait for 2 minutes). But simply applying, is not enough to disinfect the surface to be treated, you must respect the contact time, so wait for 10 minutes before removing it. Of course do not mix bleach with ammonia or other chemicals and mix bleach with cold water: as hot water decomposes the active ingredient of bleach and renders it ineffective (5).
The solutions thus created, should be used within 24 hours at the latest, so as not to lose their disinfecting power.
Certainly these products cannot be used on the skin repeatedly because of their corrosive character, in particular bleach wouldn’t be a good option also for elevated contact time.
The formula for homemade hand/skin disinfectant
If you are one of those who have not been lucky enough to grab a specific product, let’s listen to the WHO’s advice and prepare it at home.
For 1 liter of product (on the WHO website the quantities are given for 10 and 100 liters, the reduction is done by me):
– 833 ml of ethyl alcohol (ethanol) at 96%.
– 42 (41.7) ml of 3% Oxygen water (hydrogen peroxide)
– 15 (14.5) ml of 98% glycerin (glycerol)
The remaining part to reach 1000 ml (or 110 ml) must be completed with distilled water… Did you forget to buy it? Don’t panic! Boil water and then let it cool to room temperature, it will work the same.
Mix the ingredients well in a stainless steel container (in other words in a steel pot for example) and keep the disinfectant in one or more glass or plastic bottles that have an appropriate closure, otherwise you would compromise the validity of the final product. If you are not sure about the hygiene of the bottles, leave them in quarantine with the disinfectant you have just prepared for 72 hours: this will also eliminate any spores.
That said, although it is certainly not necessary, I prefer to make it clear to you that other types of home-made disinfectants such as vinegar, bicarbonate of soda, common alcohol such as vodka or whiskey, essential oils of tea tree, or oregano or thyme, or aloe vera, etc., are not valid solutions as a disinfectant for viruses and they are not valid for the deactivation of Sars-CoV-2, although eco-friendly.
(1) Omidbakhsh N, Sattar SA. Broad-spectrum microbicidal activity, toxicologic assessment, and materials compatibility of a new generation of accelerated hydrogen peroxide-based environmental surface disinfectant. Am. J. Infect. Control 2006;34:251-7.
(2) Vopr Virusol. 1977 Nov-Dec;(6):731-3. [Virus inactivation by hydrogen peroxide]. [Article in Russian] Mentel’ R, Shirrmakher R, Kevich A, Dreĭzin RS, Shmidt I.
(3) Infection Prevention and Control of Epidemic- and Pandemic-Prone Acute Respiratory Infections in Health Care. Geneva: World Health Organization; 2014. Annex G, Use of disinfectants: alcohol and bleach. Available from: https://www.ncbi.nlm.nih.gov/books/NBK214356/
(4) Matteo Guidotti e il suo team dell’Istituto di scienze e tecnologie chimiche “Giulio Natta” (Scitec) del Cnr di Milano
(5) Centre for Health Protection, Department of Health, Hong Kong Special Administrative Region Last updated in December 2018