How do hand sanitizers work? How to choose the best hand sanitizer?

Personal hygiene has become very important in our lives due to COVID-19 pandemic. One of the most important parts of having personal hygiene is to have clean hands. Clean hands are of utmost importance for the fight against COVID-19. You may not have time or it may not be the right place to wash your hands with soap and water, hand sanitizer is here for your rescue! You may be at your home or in the office, or at the marketplace, there’s always a chance of contracting these pathogens. What’s better than carrying your weapon aka HAND SANITIZER to eliminate these pathogens.

In this war against the COVID-19 pandemic where N95/KN95 protective face masks and PPE kits are playing the role of shields, our beloved hand sanitizers are enacting the role of a weapon. There isn’t a speck of doubt about the fact that this little bottle of sanitizer has clinically tested and proved itself as an effective measure in eliminating the novel coronavirus (SARS-CoV-2).

CDC has recommended washing hands with soap and water because it removes and reduces all the types of pathogens and chemicals on hands. But when you cannot employ soap and water, using a hand sanitizer with at least 60% alcohol (for alcohol-based sanitizers) eliminates most of the pathogens.

How to Choose the ‘Right’ Hand Sanitizer?

According to the WHO and CDC, hand sanitizers provide the best, convenient, and most effective way to clean your hands if you cannot wash your hands with soap and water. According to FDA, a product can be sold as a hand sanitizer if and only if it contains ethyl alcohol (ethanol), isopropyl alcohol (isopropanol or 2-propanol), or benzalkonium chloride as the active ingredient.

No hand sanitizer should be used if it contains an active ingredient other than the three mentioned ones. Any active ingredient other than the three mentioned above are either not effective or can be harmful to human beings. According to the FDA, they recommend not to use hand sanitizers that contain methyl alcohol (wood alcohol or methanol) or propyl alcohol (1-propanol) as it can be harmful and toxic to human skin. These two chemicals are lethal and cause alcohol poisoning if ingested.

 

 

Types of Hand Sanitizers :

Hand sanitizers can be categorized into two types, based on alcohol :

I) Alcohol-based :

This type of hand sanitizer is most commonly used and the active ingredient is alcohol. Alcohols are organic compounds primarily comprising three elements namely, Carbon, Oxygen, and Hydrogen with a functional group of -OH. The alcohol-based active ingredients are ethanol and isopropyl alcohol.

Ethanol is present in most alcoholic drinks. It is most widely used as the active ingredient in hand sanitizers followed by isopropyl alcohol. Both these alcohols are highly soluble in water with low boiling points and high volatility.

The effectiveness of alcohol-based hand sanitizers increases with the concentration of alcohol. According to studies, an alcohol concentration of 30% has pathogen-killing/denaturing ability, and this ability increases with alcohol concentration.

Hand sanitizers work well when the concentration exceeds 60%, and the effectiveness increases rapidly as the concentration increases until it reaches 95% concentration. Thus, the alcohol percentage becomes a deciding factor in choosing the right type of alcohol-based hand sanitizer.

100% of alcohol is not a good hand sanitizer and doesn’t eliminate the pathogens. According to the CDC, the best effectiveness of alcohol-based sanitizers is the range of 60-90% concentration. The other component present in water is necessary to denature the protein structures and increase the effectiveness of the hand sanitizers. It improves effectiveness by allowing longer contact time. Moreover, water also aids in the storage of hand sanitizers by preventing alcohol from evaporation.

 

II) Alcohol-Free :

The most widely used alcohol-free active ingredient is Benzalkonium chloride. This chemical compound is used as the active ingredient, at a concentration of 0.13% and can be just as effective as alcohol-based hand sanitizers. Benzalkonium chloride has proved that it can be better than alcohol-based hand sanitizers in eliminating a few pathogens.

Benzalkonium chloride if inhaled, ingested, or comes in contact at higher concentrations can result in respiratory problems, allergy reactions, nausea, itching, rashes, etc. Hence, due to the risks involved and very little knowledge of their working, alcohol-free sanitizers are seldom used.

According to the CDC, alcohol-free hand sanitizers may not kill as many pathogens when compared to alcohol-based ones. They usually reduce the growth of pathogens rather than killing/denaturing them.

How to use Hand Sanitizer?

This video by Babylon Health clearly explains how you should apply Hand Sanitizer.

 

 

How do Alcohol-based Hand Sanitizers WORK?

According to studies, it has been proven that alcohol-based sanitizers eliminate a variety of pathogens which include bacteria and viruses.

Every hand sanitizer whether it be alcohol-based or alcohol-free protects our hands by killing/denaturing the pathogens. Alcohols kill/denature the pathogens primarily in three ways :

1) Breaking apart protein structures,

2) Splitting cells into some pieces,

3) Destroying or Disturbing cell metabolism.

In general, for the elimination of viruses, sanitizers work by destroying or disturbing the virus's outer coat while for bacteria they work by destroying or disturbing its cell membrane.

Advantages of Alcohol-based Hand Sanitizers :

1) Pathogens cannot develop resistance to alcohol. Thus, the effectiveness of alcohol remains undisturbed.

2) According to studies, Ethanol-based hand sanitizers (60-90%) are better than regular handwash (soap and water) for eliminating three pathogenic bacteria namely, Escherichia coli, Serratia marcescens, and Staphylococcus saprophyticus.

3) They don’t damage or hurt human skin cells.

4) Ethanol-based hand sanitizers have a pleasant smell. (It has nothing to do with pathogen-killing/denaturing ability).

 

Why Hand Sanitizers are not better than Handwash?

1) Hand sanitizers don’t eliminate harmful chemicals which may include fertilizers, pesticides, and heavy metals.

2) Hand sanitizer cannot be used when hands are soiled or dirty or greasy.

3) Handwash (soap and water) is better than hand sanitizers in eliminating certain pathogens like Cryptosporidium, norovirus, and Clostridium difficile. This is either because these viruses (like Norovirus) lack an outer coat or the spore-forming bacteria (like Clostridium difficile) cannot be penetrated and are not very susceptible to hand sanitizers.

 

 

Key Points to NOTE :

1) Incorrect choice and usage of hand sanitizer can hamper the effectiveness of hand sanitizer.

2) Common mistakes are using low volume/concentration of the sanitizers or wiping off sanitizer before it has dried.

3) Hand sanitizers don’t expire. Instead, the concentration of alcohol decreases with time (due to evaporation), and thus effectiveness decreases. Though, there will be an expiry date mentioned on hand sanitizers. This is regulated by the FDA.

4) Alcohol evaporates quickly due to its low boiling point and high volatility. It evaporates when the bottle is opened and closed. Thus, if you store the bottle (closed) and preferably at room temperature, hand sanitizers last long.

5) Though alcohol-based hand sanitizers don’t have any toxic or harmful effect on human skin, their repeated use can cause dryness.

6) Don't wipe your hands after applying alcohol-based hand sanitizer before the alcohol dries up.

7) Alcohol-based sanitizers are inflammable. They should be stored safely and if used then the user shouldn’t come in contact or nearby of any spark or flame.

8) Children under the age of six should use hand sanitizer under adult supervision.

9) Alcohol-based hand sanitizers if ingested by mistake; medical help should be contacted immediately.

10) While selecting amongst alcohol-based sanitizers the following points should be noted :

Ethanol is more effective, less toxic, and has a pleasant smell. Isopropyl alcohol has a pungent odor and is a man-made chemical. Both these alcohols have different grades which influence their effectiveness.

11) Some hand sanitizers have additives such as aloe, glycerine and vitamin E. These additives positively influence stability and reduce the drying effect.

Conclusion :

Different types of sanitizers are available in the market but you have to choose the right one which is FDA approved and has optimum alcohol concentration. Always go for the sanitizer which has a tried and tested formulation and that is safe for the skin.

At Trueppeusa, our hand sanitizer is FDA approved and has a 70% alcohol concentration. It is highly effective against pathogens and primarily against the novel coronavirus.