We often discuss hypochlorous acid in terms of its efficacy against sodium hypochlorite (bleach). But how does hypochlorous stack up against another one of the most popular forms of disinfection--alcohol?

Alcohol is a widely-used sanitizer, mainly due to its availability and low cost. There are two main types of alcohol sanitizers--isopropyl and ethyl. Ethyl alcohol is the same form of alcohol you'd find in a pint of beer. It's created by the fermentation of sugars and is a combination of carbon, hydrogen, and oxygen. Isopropyl alcohol contains two more hydrogen molecules and one more carbon molecule than ethyl alcohol does, and is more commonly used for sanitation purposes. While both forms of alcohol can cause alcohol poisoning if ingested, isopropyl alcohol is twice as potent as ethyl alcohol and can cause alcohol poisoning very quickly if ingested.

As far as disinfecting power is concerned, ethyl alcohol is more effective against a wider range of pathogens, including smaller non-enveloped viruses, which are the hardest to kill. Ethyl alcohol can inactivate adenovirus, rotavirus, and rhinovirus, while isopropyl cannot. Hypochlorous acid, on the other hand, is effective against both enveloped and small non-enveloped viruses.

Alcohol is also not sporicidal, while hypochlorous acid is. The efficacy of alcohol is highly dependent on the physical properties of the pathogen. Isopropyl alcohol is lipophilic, which means it's most effective against pathogens that are surrounded by a protective layer of lipids (fats). Additionally, alcohol is highly susceptible to evaporation, and thus is most effective when combined with water between concentrations of 60-90%. Alcohol is extremely flammable and can cause damage to materials such as plastic and fabric over extended use.

So why choose hypochlorous acid? Hypochlorous is more effective against a wider range of pathogens, less sensitive, does not need to be diluted, is completely non-toxic, more stable, and poses no health or environmental risks.

It is the superior option on all counts, but especially in the healthcare setting, where alcohol-based sanitizers are commonly used. Sanitizing tools with alcohol is a difficult process, as it involves completely submerging the tools in large quantities of alcohol to prevent rapid evaporation of the sanitizer and achieve the necessary contact times. Because it is less effective against certain key pathogens that need to be controlled, alcohol generally needs to be used in combination with other disinfectants. This adds unnecessary complication to the cleaning process (and the budget).

Compare this to hypochlorous, which can be manufactured on-site with simple ingredients, remains stable for 4 to 8 weeks, is effective as a broad spectrum disinfectant, and doesn't come with any health or safety concerns. When generated on site, hypochlorous is extremely cost effective and poses none of the risks associated with supply chain shortages. We think the choice is pretty clear!

Photo by engin akyurt on Unsplash

References:

Sandle, T. (2017) Risk of microbial spores to cleanrooms: Part 2: Selection of sporicidal disinfectants, Clean Air and Containment Review, Issue 29, pp14-16