(The following is a guest post by trusted friend of ChopSaver and Certified Formulating Chemist Tammy Lisi. This is her response to the growing trend of do-it-yourself hand sanitizers. Some of this is technical in nature, but to sum up, it is not a good idea, in her opinion.)
Hand Sanitizer and the chemist… I’m tired and obviously those in back aren’t getting it.
This chemist is annoyed and perplexed at the crazy homemade hand sanitizer formulations circulating the globe like a dangerous wildfire. I have been in the business of new product development for over 20 years, and one thing I wish is that people would stop circulating or sending me DIY hand sanitizer formulations to “check over.” Not one of them has passed my basic standard of requirement.
Here are some basics required to make an effective sanitizer:
1) Improved contact time for alcohol to work and ideal concentration for mitigation.
a. Alcohol requires contact time, depending on the microbe, minimum required contact time of 1 minute may need to be achieved. We know that even simple microbes require time to get the alcohol inside to denature (break up) the protein within, studies show, 20 seconds when blended with other known antimicrobial agents like Benzalkonium Chloride (notice I did not say tea tree essential oil).
b. Ethyl Alcohol is generally preferred and 60-90% is generally considered safe and effective (notice, I did not say 100%). When you start to get over 95% alcohol content, studies show that microbes can limit the ability of the alcohol to denature the protein within. I really don’t care why, I’m a chemist and that is biology.
2) Do not burden the sanitizer with ingredients that add a burden.
a. Ingredients like Aloe and homemade plant extracts add a microbial burden. If you have amazing proof it doesn’t, forward it to me.
b. Finished products like Aloe Gel that are not properly handled potentially add a microbial burden.
3) Do not make unsubstantiated claims
a. Statements that have not be substantiated with testing such as “kill COVID 19” need to be tested.
b. Hand Sanitizer in the US is a drug and requires a Drug Facts Box. These products need to be tested for identity and content.
4) Don’t burn the babies. This is the number one rule of formulations, and I am dead serious about this. Do not, I repeat do not burn the babies. Do not, nope not ever, make anything that may burn someone’s baby. Just don’t ever do it.
a. Essential oils in uncontrolled percentage risk harmful skin interactions
b. Essential oils in combination with materials that they do not readily mix with such as alcohol and water create a non-homogeneous solution that can again cause harmful skin interactions.
c. Repeated use of ingredients like alcohol dry out the skins’ acid barrier which in turn causes irritation that can actually increase the risk of microbial fiesta (this is my favorite description of infection).
So how does a REAL chemist formulate hand sanitizer?
We use polymers to help increase contact time and help reduce trans epidermal water loss (TEWL). These polymers are largely synthetic (carbomers, vinyl acrylates, etc.). But you are wanting them to be sustainably sourced natural agents? Sorry, they aren’t. We have tried Guar and Xanthan but they just don’t go pass the rigors of testing like the synthetic polymers do.
I’ve read some DIY blogs saying these polymers are emulsifiers – no they are not. They are rheology modifiers. They have these amazing traits that thicken and create what we call rheology. Yes, they make things thicker but its more complicated than that.
In addition to thickening, some of them can lay down a microfilm and improve contact time of the disinfectant used as well as reduce the subjects TEWL.
In order for these polymers to work, first we hydrate them and then neutralize them. Most people don’t have the materials at home to mix a polymer for extended periods of time and then use a pH meter to optimize the effect. Yes, there are some rapid polymers (I personally like one by 3V Sigma called Rapid EZ), but most DIYer’s don’t have access to these.
In addition to the polymer, sometimes we add a humectant to help draw moisture to the skin or a pleasant fragrance (which we add a solubilizer, so it doesn’t separate over time).
Before this magic is released for sale, we run a bunch of testing.
1) Stability to satisfy the FDA’s monograph on hand sanitizer (yes there are rules).
2) Microbial testing and challenge testing against a selection of organisms.
3) Identity and concentration testing on the actives used.
4) Human Repeat Insult Patch Test HRIPT. Verifying that their products do not cause irritation when repeatedly applied to human subjects over time.
Next time you see one of those DIY formulations recommending vodka and aloe with some essential oils, think for a minute.
1) Do you really think you are at a minimum of 60% alcohol content when you complete making the formulation?
2) Are you using someone else’s aloe gel that you know nothing about the microbial activity or preservative efficacy on?
3) Are you confident that the essential oils you drop in won’t cause an unintended skin reaction?
4) Do you have a solubilizer to keep this whole thing together?
5) And finally, are you willing to keep this concoction wet on your hands for a minute while it works?
Last thing, I know someone out there is just itching to ask, “But don’t essential oils have antimicrobial properties?” I have never found essential oils diluted properly to be skin safe or improved a preservative efficacy test. Just like I have never found that adding some red raspberry seed oil to a properly formulated sunscreen added any SPF factor via real testing.
Can you believe we follow up these claims with REAL testing? We don’t just look at something and say, “It looks great!” We generally shy away from confrontation of the EWG, fearmongering, and DIY crowd because it’s not worth our breath to try to change anyone’s mind.
Enjoy your life and let the chemists formulate your products to the best of the science they understand intimately.
FYI: The FDA has come out with emergency guidance. They are apparently as annoyed as I am. Please note the rules and who it applies to. (It is meant for pharmacists only.)