# Alcohol-based handwash. Where does the dirt go? **URL:** \ **Category:** Factual Questions\ **Created:** [September 21, 2009, 8:47pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991 "2009-09-21T20:47:47Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\ **Post date:** [September 21, 2009, 8:47pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/1 "2009-09-21T20:47:47Z")
I could easily goggle this (And I will if I get no replies), but I think it’s a perfect GQ question. When you wash your hands with alcohol-based ‘dry’\* hand wash, where does the dirt go? [sub]\*Dry as in - does not require water like traditional soap or hand wash[/sub] ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [September 21, 2009, 8:57pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/2 "2009-09-21T20:57:38Z")
I’d venture that the dirt goes nowhere, but the germs are killed. ---
**Author:** ![EmAnJ](https://avatars.discourse-cdn.com/v4/letter/e/d2c977/32.png) [@EmAnJ](https://boards.straightdope.com/u/EmAnJ)\ **Post date:** [September 21, 2009, 8:58pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/3 "2009-09-21T20:58:36Z")
Yeah, your hands are still dirty, they’re just disinfected. PS: Do NOT use hand sanitizer while camping and then try to put contacts in. It doens’t work that way. ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [September 21, 2009, 8:59pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/4 "2009-09-21T20:59:51Z")
> [@Lobsang](#): > > I could easily goggle this (And I will if I get no replies), but I think it’s a perfect GQ question. > > When you wash your hands with alcohol-based ‘dry’\* hand wash, where does the dirt go? > > [sub]\*Dry as in - does not require water like traditional soap or hand wash[/sub] It doesn’t. What you are thinking of as “dirt” is simply skin oils which the alcohol breaks down. If you really have real “dirt” (ie soil) on your hands you need wipes or water to remove it. ---
**Author:** ![Lobsang](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobsang/32/4067_2.png) [@Lobsang](https://boards.straightdope.com/u/Lobsang)\ **Post date:** [September 21, 2009, 9:08pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/5 "2009-09-21T21:08:22Z")
Ok, where does the broken-down oil go? Evaporate? Or does it stay there (albeit not oily) like the dirt? ---
**Author:** ![Superhal](https://avatars.discourse-cdn.com/v4/letter/s/b4bc9f/32.png) [@Superhal](https://boards.straightdope.com/u/Superhal)\ **Post date:** [September 21, 2009, 9:10pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/6 "2009-09-21T21:10:21Z")
Sanitizers and cleaners are different. A sanitizer usually uses the idea of dehydration to kill germs. So, the germs are still there, but dead. Cleaners, like soap, use the idea of lathering to clean. By making bubbles, dirt is lifted from the surface, and then rinsed off. ---
**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\ **Post date:** [September 21, 2009, 9:18pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/7 "2009-09-21T21:18:20Z")
> [@EmAnJ](#): > > PS: Do NOT use hand sanitizer while camping and then try to put contacts in. It doens’t work that way. …ouch :eek: FWIW, contact solution works great whether to soak, rub, clean hands with or use as a giant eyedrop solution. Really! ---
**Author:** ![janeslogin](https://avatars.discourse-cdn.com/v4/letter/j/df788c/32.png) [@janeslogin](https://boards.straightdope.com/u/janeslogin)\ **Post date:** [September 21, 2009, 10:25pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/8 "2009-09-21T22:25:56Z")
I don’t know what they are teaching now but in 1960 or so in ‘Advanced Medical Microbiology’ we were taught that it took 10-15 minutes for alcohol to kill significant numbers of “germs”; that alcohol was used to reduce surface tension, not to kill. ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [September 21, 2009, 10:32pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/9 "2009-09-21T22:32:53Z")
I work in a hospital. Computers, not medical. Your hands are supposed to be clean when you use the sanitiser. You wash them in water and soap as per normal, rinse with water, dry with a towel, then use the alcohol sanitiser for a final disinfection. The alcohol also displaces any remaining water. All computer equipment has to be sanitised too. ---
**Author:** ![legalsnugs](https://avatars.discourse-cdn.com/v4/letter/l/45deac/32.png) [@legalsnugs](https://boards.straightdope.com/u/legalsnugs)\ **Post date:** [September 22, 2009, 10:28am UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/10 "2009-09-22T10:28:44Z")
I used some hand sanitizer the other day after handling a ferret, to kill any germs and to get rid of the smell. I can only assume the germs were killed because the smell remained. Yick. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [September 22, 2009, 10:59am UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/11 "2009-09-22T10:59:17Z")
We have hand sanitiser dispensers by the lifts in our office, as part of a company-wide kneejerk reaction to swine flu. It says on the label “Ensure hands are clean and dry before use”. ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [September 22, 2009, 12:37pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/12 "2009-09-22T12:37:54Z")
I just did a test of one of those sanitizers as part of health day. First I used the sanitizer as instructed. Then I rubbed some liquid on my hands that showed bacteria when exposed to ultraviolet. I put my hands under the ultraviolet and they were covered with germs. Conclusion: alcohol sanitizers are worthless. Also, the test only showed bacteria. It did not show viruses. Therefore we have no way of knowing if it killed any viruses at all. So does it protect against flu viruses or not? ---
**Author:** ![Sigene](https://avatars.discourse-cdn.com/v4/letter/s/df788c/32.png) [@Sigene](https://boards.straightdope.com/u/Sigene)\ **Post date:** [September 22, 2009, 12:52pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/13 "2009-09-22T12:52:54Z")
> [@RealityChuck](#): > > I just did a test of one of those sanitizers as part of health day. First I used the sanitizer as instructed. Then I rubbed some liquid on my hands that showed bacteria when exposed to ultraviolet. I put my hands under the ultraviolet and they were covered with germs. > > Conclusion: alcohol sanitizers are worthless. I’m not so sure your UV test is appropriate to show bacteria are alive or not. Can you trust your test to be accurate, and that it isn’t the thing that is “worthless.” ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [September 22, 2009, 1:36pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/14 "2009-09-22T13:36:51Z")
[Here’s an article about the CDC guidelines.](http://www.infectioncontroltoday.com/articles/400/400_2c1feat6.html) Yup. Start with clean (no visible dirt) hands and wash with soap and water if your hands get any visible dirt or debris on them along the way. In between patients however an alcohol hand rub works as well - or better - at killing germs than hand washes - and is more likely to actually be used with the needed obsessive regularity by healthcare workers - than traditional handwashing is. (Yes that UV test will show up dead germs.) It kills bugs well and does not remove dirt or oils, as already pointed out. Me (a pediatrician), I wash at the start of the day, and if handle a poopy diaper, but in between I hand sanitize upon entry in the room (before touching the keyboard), and immediately before (hands now off that microscopically disgustingly filthy keyboard) and after each patient contact, and then again as I leave the room after having typed some more. It is unlikely that I’d wash effectively that often. ---
**Author:** ![Hampshire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hampshire/32/4887_2.png) [@Hampshire](https://boards.straightdope.com/u/Hampshire)\ **Post date:** [September 22, 2009, 1:42pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/15 "2009-09-22T13:42:11Z")
> [@RealityChuck](#): > > I just did a test of one of those sanitizers as part of health day. First I used the sanitizer as instructed. Then I rubbed some liquid on my hands that showed bacteria when exposed to ultraviolet. I put my hands under the ultraviolet and they were covered with germs. > > Conclusion: alcohol sanitizers are worthless. I’ve seen a lot of local news running small side stories on this lately investigating the effectiveness of hand sanitizers. They came to the same conclusion, they are pretty worthless. Especially when compared to good ol’ soap rinsed clean with water. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [September 22, 2009, 2:59pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/16 "2009-09-22T14:59:26Z")
I for one just love when the local news expose is so much more expert than oh say the actual scientific expert bodies. It must be noted that not all alcohol based hand sanitizers are created equal. To be effective the alcohol concentration should be between 60 to 95% ethanol or isopropanol; some over the counter products are only 40%. And oh for kicks, [a real study.](http://www.ncbi.nlm.nih.gov/pubmed/15489352?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DiscoveryPanel.Pubmed_Discovery_RA&linkpos=5&log$=relatedreviews&logdbfrom=pubmed) > [@](#): > > The best antimicrobial efficacy can be achieved with ethanol (60 to 85%), isopropanol (60 to 80%), and n-propanol (60 to 80%). … Plain soap and water has the lowest efficacy of all. … So much for local news running small side stories. Hand cleansing methods are like which car seat you buckle your kid into - the first most effective choice is the one you actually use every time. ---
**Author:** ![Fantome](https://avatars.discourse-cdn.com/v4/letter/f/e9c0ed/32.png) [@Fantome](https://boards.straightdope.com/u/Fantome)\ **Post date:** [September 22, 2009, 3:43pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/17 "2009-09-22T15:43:37Z")
> [@Superhal](#): > > Cleaners, like soap, use the idea of lathering to clean. By making bubbles, dirt is lifted from the surface, and then rinsed off. Bubbles don’t lift dirt from the surface and a lather isn’t necessay. As **Cheesesteak** said in [this](http://boards.straightdope.com/sdmb/showthread.php?t=354622) thread, “For handwashing, suds are more than just pretty bubbles, they are indicators of how much active detergent is available to clean with, and help define where it has been applied and rinsed from.” [How does Soap Work?](http://www.edinformatics.com/interactive_molecules/soap.htm) > [@](#): > > Nearly all compounds fall into one of two categories: hydrophilic (‘water-loving’) and hydrophobic (‘water-hating’). Water and anything that will mix with water are hydrophilic. Oil and anything that will mix with oil are hydrophobic. When water and oil are mixed they separate. Hydrophilic and hydrophobic compounds just don’t mix. > > The cleansing action of soap is determined by its polar and non-polar structures in conjunction with an application of solubility principles. The long hydrocarbon chain is non-polar and hydrophobic (repelled by water). The “salt” end of the soap molecule is ionic and hydrophilic (water soluble). > > When grease or oil (non-polar hydrocarbons) are mixed with a soap- water solution, the soap molecules work as a bridge between polar water molecules and non-polar oil molecules. Since soap molecules have both properties of non-polar and polar molecules the soap can act as an emulsifier. An emulsifier is capable of dispersing one liquid into another immiscible liquid. This means that while oil (which attracts dirt) doesn’t naturally mix with water, soap can suspend oil/dirt in such a way that it can be removed. The soap will form micelles (see below) and trap the fats within the micelle. Since the micelle is soluble in water, it can easily be washed away. > > When you mix soap into the water the soap molecules arrange themselves into tiny clusters (called ‘micelles’). The water-loving (hydrophilic) part of the soap molecules points outwards, forming the outer surface of the micelle. The oil-loving (hydrophobic) parts group together on the inside, where they don’t come into contact with the water at all. Micelles can trap fats in the center. ---
**Author:** ![Waenara](https://avatars.discourse-cdn.com/v4/letter/w/50afbb/32.png) [@Waenara](https://boards.straightdope.com/u/Waenara)\ **Post date:** [September 23, 2009, 6:50am UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/18 "2009-09-23T06:50:58Z")
I’m a nursing student, and we’ve been taught to use both handwashing (properly - hot water, soap, scrub thoroughly for 20-30 seconds, turn off taps using a paper towel) and hand sanitizer. Hand sanitizer is okay to use if your hands are not visibly soiled or dirty (then you use soap and water) - this is because sanitizer kills the germs but does not remove dirt. Also, we’ve been told that once we’ve used the hand sanitizer up to ten times we should then use soap and water to get rid of accumulated grime before using sanitizer again. When seeing a patient, we wash our hands on entering the room and when leaving. Often handwashing is required more often than that. For example, when entering a room where a patient is under isolation precautions (e.g. they have MRSA): wash hands, put on gown, put on mask, put on gloves, treat patient, remove gloves, wash hands, remove gown, wash hands, remove mask, wash hands. If you had to properly wash your hands with soap and water each time, you’d spend half your day at the sink and your hands would suffer (they get dry and chapped as it is). Instead, in that situation I’d likely use hand sanitizer at each step, except the final handwash would be with soap and water. ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [September 23, 2009, 5:07pm UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/19 "2009-09-23T17:07:10Z")
Have you had problems with alcoholics trying to steal the sanitisers? We have. ---
**Author:** ![user\_hostile](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/user_hostile/32/474_2.png) [@user\_hostile](https://boards.straightdope.com/u/user_hostile)\ **Post date:** [September 25, 2009, 1:40am UTC](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991/20 "2009-09-25T01:40:16Z")
Hmm… can one get drunk off of hand sanitizer? [Next page](https://boards.straightdope.com/t/alcohol-based-handwash-where-does-the-dirt-go/510991.md?page=2)