Soap kills Coronavirus, but what if your Body Wash has no soap in it?
March 16, 2020 3:34 PM Subscribe
There's a science behind how soap kills Coronavirus when you wash your hands. But products like Nivea Sensitive Body Wash and Aveeno Skin Relief Body Wash note they have no soap in them. So is it time to use something else? Or am I misunderstanding terms or chemicals and these types of products will work as well to kill Coronavirus?
Best answer: Look at the ingredient lists for those products, and you will see “Sodium Laureth Sulfate.” It is a detergent. Detergents break apart lipids/fats just like soaps do, and remove viruses just like soaps do. Most of what we colloquially call “soap” is really detergent — and this is true for recommendations to wash hands with “soap and water.” Most liquid hand “soaps” effective for handwashing are really hand detergents.
The manufacturers of those products are playing with technicalities when they say “contains no soap”. In the most technical sense, “soap” has to be made using a natural fat, vs. “detergent” which can be entirely a human-made chemical. Using this technical definition, bar soap is “soap” because it contains ingredients like “sodium tallowate” and “sodium palm kernelate” (made from tallow and palm kernel oil) , but Dawn dish detergent does not contain “soap.” Yet Dawn is very good at breaking up lipids.
Rule of thumb: Soap usually leaves a scum or film, but detergents rinse clean.
posted by snowmentality at 3:52 PM on March 16, 2020 [22 favorites]
The manufacturers of those products are playing with technicalities when they say “contains no soap”. In the most technical sense, “soap” has to be made using a natural fat, vs. “detergent” which can be entirely a human-made chemical. Using this technical definition, bar soap is “soap” because it contains ingredients like “sodium tallowate” and “sodium palm kernelate” (made from tallow and palm kernel oil) , but Dawn dish detergent does not contain “soap.” Yet Dawn is very good at breaking up lipids.
Rule of thumb: Soap usually leaves a scum or film, but detergents rinse clean.
posted by snowmentality at 3:52 PM on March 16, 2020 [22 favorites]
Bar soap is soap, liquid is usually detergent. as far as I can find out, the difference between liquid hand soap and body wash is just labeling; I use them interchangeably.
posted by theora55 at 4:30 PM on March 16, 2020
posted by theora55 at 4:30 PM on March 16, 2020
BTW, soap doesn't kill bacteria or virus, it loosens them and rinses them away.
For what it's worth, soap totally kills bacteria and viruses (or, if you insist that viruses aren't alive, it kills bacteria and breaks viruses up, rendering them inactive). Soap molecules work their way into the lipid membranes that encapsulate many viruses, pops them open, and then surrounds the resulting bits--I suppose this could be described as "loosening and washing away" in the same way soap loosens and washes away grease on a pan, but it isn't like you wind up with soapy runoff full of still-active, still-infectious virus particles and bacteria after washing your hands (what a nightmare that would be!). Post-soap viruses are very much kaput.
There's a good in-depth description here.
posted by pullayup at 5:24 PM on March 16, 2020 [17 favorites]
For what it's worth, soap totally kills bacteria and viruses (or, if you insist that viruses aren't alive, it kills bacteria and breaks viruses up, rendering them inactive). Soap molecules work their way into the lipid membranes that encapsulate many viruses, pops them open, and then surrounds the resulting bits--I suppose this could be described as "loosening and washing away" in the same way soap loosens and washes away grease on a pan, but it isn't like you wind up with soapy runoff full of still-active, still-infectious virus particles and bacteria after washing your hands (what a nightmare that would be!). Post-soap viruses are very much kaput.
There's a good in-depth description here.
posted by pullayup at 5:24 PM on March 16, 2020 [17 favorites]
Can I tag onto this? Why are people encouraging disinfectants with X percent alcohol then? Wouldn't any soap suffice for washing down the countertops?
posted by slidell at 5:39 PM on March 16, 2020
posted by slidell at 5:39 PM on March 16, 2020
slidell, are you talking about the requirement that hand sanitizers (not disinfectants for countertops) must contain 60% alcohol? That’s because they need to kill viruses and bacteria without soap or detergent.
Are you talking about surface disinfectants? The CDC explains the difference between cleaning and disinfecting. Cleaning removes germs; disinfecting kills whatever is left. Surfaces should be cleaned using soap or detergent before using disinfectant.
posted by snowmentality at 5:55 PM on March 16, 2020 [3 favorites]
Are you talking about surface disinfectants? The CDC explains the difference between cleaning and disinfecting. Cleaning removes germs; disinfecting kills whatever is left. Surfaces should be cleaned using soap or detergent before using disinfectant.
posted by snowmentality at 5:55 PM on March 16, 2020 [3 favorites]
Fda’s FAQ on soap
You might also check out ‘Is It a Cosmetic, a Drug, or Both? (Or Is It Soap?)’ link at the bottom of the page.
Not sure these pages directly answer your question but they give some background maybe on the labeling distinctions. And how ‘soap’ or not leads to some regulatory differences...
posted by Tandem Affinity at 7:00 PM on March 16, 2020
You might also check out ‘Is It a Cosmetic, a Drug, or Both? (Or Is It Soap?)’ link at the bottom of the page.
Not sure these pages directly answer your question but they give some background maybe on the labeling distinctions. And how ‘soap’ or not leads to some regulatory differences...
posted by Tandem Affinity at 7:00 PM on March 16, 2020
Disinfectants with 60% alcohol kill germs dead, but soap works as well.. with water. Without water, soap is not going to get the job done. So, the decision to use soap or sanitizer comes down to whether clean, preferably warm water is available, and of course what, besides Coronavirus, is on your hands (i.e. dirt, urine splatter, teriyaki sauce, dog funk, etc. -- hopefully not all in one sitting)
I gather that alcohol also needs some amount of water to do the job right-- not that 99% alcohol doesn't kill germs, but there's an optimal ratio of alcohol to water, which I gather is in the neighborhood of 70:30 Alcohol:Water. I am not a chemist or microbiologist.
posted by Sunburnt at 7:20 PM on March 16, 2020 [1 favorite]
I gather that alcohol also needs some amount of water to do the job right-- not that 99% alcohol doesn't kill germs, but there's an optimal ratio of alcohol to water, which I gather is in the neighborhood of 70:30 Alcohol:Water. I am not a chemist or microbiologist.
posted by Sunburnt at 7:20 PM on March 16, 2020 [1 favorite]
Do we include soap-free products that do not contain SLS? I assume that this is a mild surfacant in soaps for the eczema prone.
posted by jadepearl at 7:29 PM on March 16, 2020
posted by jadepearl at 7:29 PM on March 16, 2020
This thread is closed to new comments.
Source: chemical engineer husband
posted by crunchy potato at 3:47 PM on March 16, 2020 [27 favorites]