A small study, to be sure, but encouraging for those who can't get access to hot water (or just don't want to wait for it to heat up).
http://www.bbc.com/news/health-40118539
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When we let politics trump science, people are needlessly put in harm's way. http://arstechnica.com/science/2017/01/self-censoring-fears...
Cool, not cold, water actually less drying on the skin.
ReplyDeleteOr for those that want to save energy...
ReplyDeleteBoiling hot water would kill more microbes, but also cook your hands.
ReplyDeleteI've argued this for years. Heat does reduce water's surface tension a bit, but that's all, and soap does that just fine on its own. It's the soap that kills germs. Water, hot or not, only feeds 'em.
ReplyDeleteIt's the friction that removes the germs, the water washes them away. Soap reduces the surface tension. It "makes water, wetter".
ReplyDeleteWhen you wash your hands for the duration of the "Happy Birthday" song, warm water makes it comfortable so you don't quit early.
What a rather artificial and misleading study. Warm water is necessary if there are greases which are not easily "dissolved" by whatever soap you use, but which would be by using warmer water (which will help melt the greases, or at least accelerate it to the point where it's likely to happen during the time the average person spends actually doing the washing).
ReplyDeleteGreg A. Woods Detergents may contain degreasers. Not all soaps do.
ReplyDeletequora.com - Does soap kill bacteria or just clean off bacteria and viruses? How does the hand washing process really work?
ReplyDeleteSakari Maaranen Not all soaps are equal.
ReplyDeleteEven using a good (i.e. harsh) degreasing dish-washing detergent on one's hands when they're coated with fats or grease, requires either enough time and friction to naturally increase the surface temperature of one's hands to the melting point of the grease and fat (something directly opposed by the friction-reducing affect of the detergent and the grease or fat itself), or else requires warm water. This is very easily shown by experiment in any kitchen. :-)
ReplyDeleteI have, by experiment, shown that it is possible to clean greasy fat-covered hands with sufficient quantities of detergent and water and time, but the waste of all is enormous. A small amount of warm water will save great amounts of time, detergent, and water.
Even when it's just already liquid oil, the affect of warmth increases the chemical reaction speed of the degreasers and still saves time and effort and water.
One learns these facts when one's sink is a great distance from one's water heater and the intervening pipe is in a rather cool space. :-)
Some make you wish you was dirty. Linda Tewes
ReplyDeletecdc.gov - Hand Hygiene in Healthcare Settings | Hand Hygiene | CDC
ReplyDeleteThere are of course industrial degreasers available which will clean even mineral-based greases and dirt from one's hands with cold water, and which are water soluble, and some aren't even all that harsh on one's skin (in the old days on the farm, when oil was cheap, we just used gasoline, but that stuff is really harsh on one's skin -- and the fumes aren't that great to breath either, nor are they safe near anything hot), but I've never seen them in very many home kitchens (unless the home owner is a mechanic or farmer), nor in any commercial kitchen.
ReplyDeleteSakari Maaranen Some make you want to shower all over again because you don't feel quite clean when you're done.
ReplyDeleteChadwick Jones I was taught that we could use a combination of hand sanitizer and soap+water. But every third hand washing event must be soap and water. 2 sanitizer::1 soap and water.
ReplyDeleteThe stuff I used to use, in my bicycle home mechanic days :-) , left an odd smell on my hands, but it was the quickest and most effective way of completely cleaning my hands (just too expensive to use for every hand cleaning). I keep it in the bathroom off the kitchen, which is closer to the hot water heater, by coincidence.
ReplyDeleteHa! to my wife right now.
ReplyDeletehttps://lh3.googleusercontent.com/CuhiFCFWnQsZybLe1cmMA3BgaUk_HMsGb9k05uhqDy016nQdTgjTn48QNEvZfHht1OgUQ-o-C0FiNjLQQJs97Vod9hH_kb4qNE6u=s0
Especially important to use soap and water when dealing with C.Diff patients. Alcohol-based sanitizers simply don't work for certain infection control situations.
ReplyDeleteLisa Chabot lava? That's what I remember my dad using.
ReplyDeleteChadwick Jones Absolutely.
ReplyDeleteI have always used cool water for standard hand washing. Even at the hottest temperature my hands could stand, the difference in survivability for bacteria is so miniscule it won't be worth the effort.
ReplyDeleteFor the degreasing aspect, that is outside the realm of this study. The question here is all about microbial vitality, not the removal of all foreign material.
Brad the issue with grease or fat is that it can contain, or cover, harmful microbes.
ReplyDeleteHowever after washing all it takes is a wee bit of mechanical action (a tiny abrasion) to disturb that grease coating and release the microbes again.
Which is why I said the study is artificial and misleading especially for kitchens and food preparation where greases and fats are a common contaminant.
Common sense should be enough to dictate when warm water is helpful or necessary, but common sense was one thing this study had none of.
Linda Tewes "Mary had a little lamb" also works. However, singing either song out loud whilst washing could cause other issues not discussed here.
ReplyDeleteDegreasers generally seem to work better for me with warm or hot water, and my skin feels less greasy or soapy afterward. Other than that though, any liquid temperature seems to work fine for dirt.
ReplyDeleteQwerty Uiop Unless you're among people who understand what you're doing.
ReplyDeleteLinda Tewes No, not Lava. Pumice is fine if you want to remove skin, but it won't necessarily get stuff embedded into the cracks or around fingernails.
ReplyDeleteThe stuff I mean comes in a tub and usually has a name like "Mechanics Friend".
Oh gosh, what a question ! Obviously cold water is as efficient. Actually, hot/warm water offers a nice place for bacteria to develop ( except if you boil your water before washing, which might be unpleasant for the hands )
ReplyDeleteGreg A. Woods The fat/grease issue is still outside the purview of this study. The microbe content of fats and greases will not be affected by the water temperature. The only significant way of removing those microbes is to remove the grease, which yes that will be aided by using hot water. But that isn't the root question of the study though. The root question is "Does hot water kill more microbes than cold water?". Even though hot water may get microbe filled grease off your hands better, it still doesn't do any more to kill those microbes.
ReplyDeleteOf course it's outside the purview of the study. Self-defined constraints on studies often make them stupid and irrelevant.
ReplyDeleteWhat a terrible article. The hands were coated in "bugs"? Really? I assume they mean a solution containing bacteria. And how the heck do you measure soap usage in millimeters? I assume the article meant ml (milli_liters_).
ReplyDeleteIf it got this wrong, what else did it misinterpret from the study?