During the H1N1 pandemic at the end of 2009, the Province of Ontario was distributing kits of supplies to healthcare professionals in the field. Many of the kits being distributed contained hand sanitizer that was, technically, expired. We received calls from doctors’ offices and medical institutions about the expired hand sanitizer asking us if it’s safe to use. As I sit here at my desk looking at a bottle of hand sanitizer that expired in April 2010, I think it’s time to share with you why hand sanitizer has an expiration date but doesn’t actually expire. It’s safe to use well past its expiration date.
One of my colleagues calls this a marketer’s dream, but there is some validity behind the use of an expiration date. I’m looking at a bottle of Purell hand santizer and the label tells me it contains 62% ethyl alcohol with the other 38% made up of water, glycerin, isopropyl myristate, propylene glycol, tocopheryl acetate, aminomethyl propanol, carbomer and fragrance. It’s really the ethyl alcohol that kills the bacteria by literally boiling them to death. Alcohol vaporizes (boils) at a much lower temperature than water, but is entirely water soluble. Therefore, the bacteria absorb the alcohol when you rub your hands with the stuff and then are literally exploded from within as the alcohol they’ve absorbed boils away. In any case, it’s the alcohol that does the trick — the rest of the ingredients are there to make the sanitizer into a gel that feels okay and smells okay to the user.
The bottles we use to package, transport, and dispense the sanitizer are not airtight. There is some leakage going on whether at the seams where the caps/pumps are screwed on, or even right through the plastic itself. Alcohol evaporates right out of the bottle over time. That is the key to the expiration date.
At some point, the sanitizer in the bottle will no longer comprise 62% or more of the contents. Enough will have evaporated to lower the content to something lower — say, 61.9%. At that point, technically speaking, the bottle has expired. The nature of the contents, particularly the active ingredient, no longer reflects what it is labelled as being. Is the sanitizer still usable? Sure. Is it still effective? You bet. But many people, even healthcare professionals, don’t know why there’s an expiration date. They just know that when they see that something’s expired, it’s time to throw it out and buy a replacement.
Bam! That’s great for business! The product is still good, but your customers and consumers are throwing it out and buying more from you! Given the fantastic margins on what is essentially a dirt-cheap product (much like soft drinks, I might add), this is a wonderful situation for the manufacturers.
But is it a total sham? Not entirely. At some point, with enough evaporation, yes the sanitizer will be ineffective. Given enough time, all of the alcohol will eventually evaporate out of the bottle. But that will take a long, long time — not the span of 3–5 years as indicated by the expiration dates. It’s true that there are guidelines recommending that everyone buy and use hand sanitizer with >60% alcohol content — and you can buy them as high as 90% alcohol — but if you know you have expired sanitizer you can just use more of it to ensure you’re using enough alcohol to do the trick.
Hand sanitizer does not expire, at least not within the timespans indicated by the expiration dates on the bottle. You can overshoot it by a few years and still have a safe, usable product. But if you’ve gone over by, say, 5 years or more… by that point your product is 10 years old and yeah, it is time to throw it out and get a new one. By that point, the sanitizer will most likely still be safe to use, but it might smell a bit funky because the fragrance has started to change — and I’m not sure how nice your bottle is going to be on the outside by then either! Your hands probably weren’t absolutely clean when you grabbed the bottle all those times over the years, right?
On a final note, alcohol evaporation isn’t just limited to hand sanitizer. It also happens with wine and liquor production. A colleague who used to work for a distillery tells me that warehouses full of whiskey aging in wood barrels are full of alcohol vapors. If you walk into the warehouse where the barrels are sitting and the whiskey is aging, make sure you keep the doors open or you will be drunk within 20 minutes from the alcohol vapors being absorbed into your bloodstream. That’s entirely off-topic, but I had to share that!
Ah! Charles posted a comment noting that there’s an additional factor that I didn’t address in the original write-up. To be more accurate, it just didn’t occur to me. It’s a matter of concentration. Below some threshold value, the alcohol in expired sanitizer will no longer be concentrated enough to kill the bacteria. It’d be like trying to kill tigers by shooting nerf balls at them. I’ll try to find out what the relevant threshold concentrations are for the key bacteria that we’re trying to kill.
New update posted! The expiration date isn’t hard-and-fast, but you do want to pay attention to it in relation to the printed alcohol concentration.