Today’s Health Matters guest writer Mylan Blomquist, a senior at Barry Goldwater high school, decided to get to the bottom of how hand sanitizers work, and which ones are most effective.
As a high school student with a lot of obligations, I’m somewhat of a hand sanitizer connoisseur.
I’ve always carried a portable sized gel hand sanitizer around with me, hoping that it is effective in fending off illnesses that would force me to miss school. It seems like everyone else has one in their school bag, too, with a variety of scents and fun holders.
Recently, I received an assignment from my senior IB biology class –to design and carry out lab research on a topic of my choosing. I was about to stress over this, thinking about how hard it would be to come up with my own unique topic.
But I soon realized the answer has been hiding in all my purses, backpacks, and pockets for years!
So, I decided to do some research and test just how effective these sanitizers really are. I started by taking a look at the labels.
How sanitizers work
According to the Centers for Disease Control and Prevention, a gel hand sanitizer must contain at least 60% alcohol to be effective in killing bacteria.
Many hand sanitizers, especially those marketed for young children, contain less alcohol than this.
If a sanitizer falls short of this 60% benchmark, here’s what happens: bacteria continue to live on the surface of the hands — despite the illusion of cleanliness.
The membranes surrounding bacterial cells dissolve and break down when paired with the friction from rubbing the hands together. If there isn’t enough alcohol in the product, no damage to these cells may occur at all.
Despite this fact, consumers can find hand sanitizers with a wide range of alcohol content, from the dangerously low (50%) to as high as 75%.
This wide variety of sanitizers is what left me wondering about what specific alcohol content is really the most effective. Do those with 75% alcohol pack a bigger punch than one that just meets the 60% benchmark?
That’s what I decided to find out for my biology experiment.
I purchased five different hand sanitizing gels.
After preparing the nutrient agar petri dishes (a surface that allows bacteria to grow), I swabbed my computer keyboard for the bacteria.
Then, I placed a ½ mL droplet of hand sanitizer in the center of each swabbed petri dish. After 4 days, the diameter of bacteria-free area, or halo, surrounding each droplet of sanitizer was the same.
In fact, each day of the experiment, the halo surrounding each droplet was the same, regardless of the hand sanitizer.
This means that any hand sanitizer containing over 60% alcohol is equally effective.
For example, a sanitizer containing 62% alcohol will kill the same amount of bacteria as one containing 70%.
As long as it contains over 60% of any type of alcohol, it will be effective in killing existing bacteria and creating a temporarily inhospitable environment for new bacteria.
The brands that were used and proved effective were Purell (regular and advanced), Germ-X, and Bath and Body Works PocketBacs, demonstrating that different types of moisturizing or coloring agents do not affect how a sanitizer performs.
Hand sanitizers should be purchased based on price, scent, or any other preference instead of alcohol content, as long as consumers check the label to ensure that it is at 60% or above.
Added moisturizers or scents do not have any influence on the effectiveness of the sanitizer, considering that I used a variety of products in this experiment.
Although it may seem logical, hand sanitizers containing large amounts of alcohol are not any more effective than one containing 60%.
My study aligned with the CDC findings: be on the lookout for those sanitizers that contain less than 60%. They are simply not effective.
However, my study determined that consumers shouldn’t worry about finding sanitizers with the highest alcohol contents, as long as it is over 60%, they have the freedom to choose whichever product they prefer.
Hand sanitizers shouldn’t be considered a replacement for soap and water, especially if hands are visibly soiled. And they don’t work in the presence of fecal matter.
- Mylan Blomquist