By Karen Danko, Cole-Parmer, US with Patricia Atkins, R&D Applications & Products Chemist, SPEX CertiPrep Ltd. and Mark Brandon, Product Manager, Cole-Parmer Lab Essentials
Many factors play a role in the effectiveness of hand sanitizer
We’ve seen the news repeatedly covering COVID-19 patients saying they’ve done all the right safety measures to protect themselves from the coronavirus, but they still contracted it. We will never know what they did or didn’t do, but based on scientific evidence, we can question whether they were using a hand sanitizer appropriately and with effective ingredients such as with alcohols at levels strong enough to kill the coronavirus.
Just because you rub your hands with hand sanitizer doesn’t mean you are eliminating all the germs on your hands. Though the Centers for Disease Control and Prevention (CDC) recommends hand washing over hand sanitizer as the most effective way to wash away germs, hand sanitizer is recommended for when we are on-the-go and do not have soap and water readily available. Remember the last time you used hand sanitizer? Did you feel safe after slathering your hands? Did you know exactly what was in that bottle? It’s a practice that can give you a false sense of security. Many factors play into effective use of hand sanitizer including how much you squirt into your hands, how long you rub your hands, the ingredients in the hand sanitizer, and the types of alcohols and percentages in the hand sanitizer.
There is a science behind making reliable hand sanitizers and percentages of ingredients matter. Basically, alcohol hand sanitizers can contain a formulation of the following: water; isopropanol (IPA), ethanol (EtOH), or both to kill germs; glycerin to smooth and soften the skin; and hydrogen peroxide to prevent bacterial or mold growth in the bottle and possibly some fragrance. The alcohols disrupt the proteins and lipids in bacteria and viruses to kill the germs, but it is the concentration of these chemicals that makes them effective.
Ethanol is the same type of alcohol found in alcoholic beverages. It is made from a fermentation process converting carbohydrates and sugars to EtOH; which is a more expensive process than to make some other types of alcohol. Ethanol is more efficient at breaking down viruses and bacteria than IPA and therefore can be effective at concentrations over 60% while you need over 70% IPA for the same efficacy.
What you don’t want to see is methanol (MeOH). Methanol is ”wood” alcohol and is a cheap by-product of many manufacturing processes. In the past, it was used to counterfeit or adulterate alcoholic beverages causing blindness and death. It is dangerous and if large quantities are absorbed through skin could cause injury. It’s up to the manufacturers’ discretion as to what ingredients they use in their hand sanitizer formulation but, methanol is banned from hand sanitizers in most countries.
According to the Centers for Disease Control and Prevention (CDC,) many studies have found that sanitizers with an alcohol concentration between 60 to 95% are more effective at killing germs than those with a lower alcohol concentration or non-alcohol-based hand sanitizers. Hand sanitizers without 60 to 95% alcohol may not work equally well for many types of germs, and merely reduce the growth of germs rather than kill them outright.
In the July 2020 issue of Forbes magazine, an article, How Much Alcohol Do You Really Need in Hand Sanitizer states, “…at concentration of 60%, ethanol might work against germs generally, but not coronaviruses specifically. Studies showed that 80% is effective against enveloped viruses within 30 seconds, which means that at lower concentrations (such as 43%) it will take longer — maybe a minute, by which time the alcohol might have evaporated from the skin before it could have the desired effect. People tend to squirt a few drops of sanitizer into the palm of one hand then rub their hands together for a few seconds, and 60% ethanol wouldn’t be effective enough over that time scale.”
Read the label
Before you purchase hand sanitizer, it’s critical to read the label because not all hand sanitizers are the same. Not all are manufactured with the same ingredients. This is proven from the hand sanitizer recall list on the US Food and Drug Administration’s (FDA) Hand Sanitizer Do-Not-Use List of ineffective and harmful hand sanitizers, some that contain methanol, and this list continues to grow. Many of these hand sanitizers are inexpensive and off brands. It’s not always safe to look for the lowest priced product, especially when purchasing chemicals you rub on your skin. Choose a reliable brand.
Example of a hand sanitizer label
Use hand sanitizer correctly
Once you have read the label and checked your ingredients then you must apply the sanitizer correctly. Sanitizer products do not instantly kill viruses and bacteria. The product must be in contact with the virus for up to one minute to destroy the particles. Liquid hand sanitizers are slightly more efficient at spreading over the skin surface skin, and over the surface area of the (germ) particles, and can kill the virus in about 30 seconds. Gel-type sanitizers spread slightly more slowly and take more rubbing to spread over all the skin area and kill the virus.
The correct application procedure is to liberally apply the sanitizer to your hands in all areas front and back, rub well for up for several seconds, and then allow to air dry for up to 30 seconds before touching any part of your face or body. Gel-type sanitizers need a bit more rubbing and time to be effective.
When to use soap and water vs. hand sanitizer
Protect yourself against COVID-19 and other viruses and bacteria. Always keep your hands clean. If you can’t use soap and water, use reliable hand sanitizer. When purchasing hand sanitizer, be sure to read the label and look for hand sanitizer per WHO formulations and to CDC recommendations that have alcohol percentages above 60%. Remember that the cheapest or off brands aren’t always the best choice and that there is a list of recalled hand sanitizers. Also, think about bringing your own hand sanitizer with you if you are going to be in a community area such as the grocery store. Most have hand sanitizer stations, but you don’t know what is in that formulation, how your skin will react to it, or how effective it will be. Better safe than sorry.
Feature image credit: Kelly Sikkema, Unsplash