99.99% of germs, what am I missing?

I just washed my hands with one of those hand sanitizer, water free, anti-bacterial gels. On the bottle (and I have noticed it on others), it states that it kills 99.99% of germs. So, what does this leave? What germs are still lurking on my hands? What is the other 1/100th of a percent?

My guess: statistics.

Nothing in biology is ever 100%. There will always be a few stragglers. There’s nothing special about them. Yes, if we’re talking anitbiotics, the survivors will be more likely to be resistant to the drug, but even if we’re just talking plain old soap, some will squeak through.

What do you mean by that?

Same question.

Pretty much what Smeghead said. Some always make it through, purely by chance. They can’t say “Kills 100% of germs!” if it doesn’t kill all of them, all the time.

For 1 thing I wonder if it kills 99.99% in vitro (lab) or in vivo (IRL), there’s nothing unusual about significant differences between the 2. Next you have to ask about surface germs, that is, the stuff you’ve just picked up, and colonized germs that developed have enlightened civilizations; don’t think for a minute that you hands are sterile after you use that stuff. Oh, and as always never underestimate the marketing depts spin. Still, we use the stuff in our hosp all the time so I guess there’s some good research behind it.

Yes, if it says “Kills 100% of the germs,” then the company has a very difficult row to hoe.

Kills 100% under what conditions? What is the dosage of the product? What is the temp of the water? How long are they required to scrub? What is the germ infestation of their skin to start with? And what kind of germs were these–easy to kill ones or hard to kill ones? …and so on.

I’d imagine it’d be a nightmare. Far safer to say that there is a possibility that a few germs just might live on no matter what.

Are there any studies or statistics stating what germs are not killed? When I started this thread, I knew that nobody could make a claim to kill all germs. However, are there any major germs that are not killed?

Also, are there any studies showing how good these hand sanitizers really are? Am I better off using regular soap and rinsing it off?

I don’t think the 99.99% means any specific TYPES of germs aren’t killed, only that due to chance, some random germs might not be. Could be one type today and one type tomorrow. I’d guess that most common germs found on people’s hands are covered.

The germs that aren’t killed are probably just .01% of the population of the germs that live on your hands normally.

For instance, like Staphylococcus epidermis:

Maybe you’ve got a million of these bugs living on your hands and after using hand sanitizer you’ll have 100 of the little buggers left over living. Of course you don’t really necessarily even want to kill the bacteria that normally is living on your hands, you want to kill cold viruses, colliform bacteria, and the like. Does it wipe out a proportion of those that will make you sick less often?

Are they effective?

Well, it depends on the context. Do you get sick a lot?

Certainly they seem to be worthwhile in hospitals and other care facilities, reducing serious infections like UTI’s and even surgical site infections by about a third in this study:

Also, for people with multiple kids in the family, the use of hand sanitizers seems to lessen the risk of getting colds slightly and have a significant impact on gastrointestinal illnesses:

But if you live by yourself and without kids and you never or rarely get sick, it won’t have a big effect. If you have a workplace or social scene where you’re exposed to a lot of colds or other illnesses, then they are probably very worthwhile.

The format of the number comes from the traditional method of determing the number of bacteria in a sample: Serial Dilution and Plate Counts.

Sorry, here’s a review article that looks at 6 experimental studies, all of which came down strongly in favor of the use of alcohol hand sanitizers.

Is it better than washing your hands? Well, the reporting for this type of study is poor, so if it came down to a difference of washing your hands 12 times a day versus hand sanitizing and washing 12 times a day, then I don’t know that anyone can tell you which method would be better.

However, in real life my guess would be that the handwashers might wash 8 times a day while the washer/sanitizers might wash 6 times a day and sanitize 15 times a day, which might make them less likely to communicate diseases not because hand sanitizing is more effective than soap and water per se, but just because it’s fast and easier to use.

Also, I don’t have a cite handy, but an article in the NY Times last month made the following points:

  1. A lot of “citizen” (non health professional) users of hand sanitizer didn’t use enough for it to be effective. They would put on a dab, rub it around, and it would quickly dry. For hand sanitizer to be effective you need to use about 3-4 ml at least (which is a lot to most people) and your hands need to stay wet for at least 30 seconds to a minute with the stuff

  2. If your hands aren’t just contaminated but actually soiled (grease, fecal mater, whatever) soap and water is the definite winner because it will actually pick that stuff off while sanitizer will just kill the germs in the outer layer of the stuff

  3. A lot of hand sanitizers sold to the public are less than 60% alcohol. To be effective, it has to be at least 60% ethanol. Purel is, a lot of the “scented” ones aren’t. Look at the bottle.

Damnit, here’s the review article.

Why in the world am I incapable of putting everything I have to say in one post?

I swear to god, I’m not trying to pad my post-count!

Great information everybody. What I got from all of this is that the hand sanitizers are good to use, especially when combined with regular hand washing. What started all of this is the fact that my wife works with children, who are always sick. So she uses it nonstop, but I just washed my hands. I am in sales and am constantly shaking hands, etc. My wife made me bring it to work. So here I was staring at it, wondering if it was really worth the extra 30 seconds every hour to use it.

I guess so!