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How Soap Works: The Science Behind Handwashing

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Re: How Soap Works: The Science Behind Handwashing

#81

Post by dist-epoch »

downWidOutaFite wrote: post #34
Kranar wrote: post #14

Earlier quoted context omitted.

I mean yes, technically soap will destroy viruses that are already in your body absolutely. It will also destroy many other cells and proteins in your body as well since soap is an indiscriminate killer. The end result is that both viruses and normal tissue will end up dying which will damage you or possibly kill you.

This doesn't sound right. Soap is considered nontoxic. We all ingest soap residue from dishes and other hygiene and I've never heard anyone concerned about it.

It's all about the concentration. Our gastro-intestinal tract is coated in mucus which will prevent small quantities of soap from actually touching the cells.

And I think it will be neutralized by the acids inside the stomach.

Re: How Soap Works: The Science Behind Handwashing

#82

Post by GeekyBear »

teach wrote: post #70
elhudy wrote: post #62

I was always under the impression that the purpose of soap isn’t to kill bacteria/viruses as the article implies, but to wash those thing off of your hands. Was my impression wrong?

I'm not an expert on this either, but I think it's true that IN GENERAL a lot of the value in soap is just "debulking". It does do that very well. But in the specific case of COVID-19 soap happens to also destroy the virus particles and that turns out to be pretty valuable too. :)

It's also important to know the current scientific consensus on how Covid spreads.

We now know that people who are infected with Covid emit viral particles into the air while breathing normally. Those viral particles can float in the air for hours and the people who inhale them become infected.

> The most common way COVID-19 is transmitted from one person to another is through tiny airborne particles of the virus hanging in indoor air for minutes or hours after an infected person has been there.

https://www.whitehouse.gov/ostp/news-updates/2022/03/23/lets...

Previously we thought the only transmission route was that infected people who sneeze or cough spray large droplets that fall out of the air quickly, and the people who touch surfaces contaminated by those droplets and later touch a mucous membrane become infected.

So Covid has fully airborne transmission like the measles, not a droplet based spread like the flu. Hand washing is an effective mitigation for a virus with a droplet based spread, but not a virus with an airborne spread.

The Whitehouse post linked above discusses the sorts of mitigations that can be effective against an airborne virus.

Re: How Soap Works: The Science Behind Handwashing

#83

Post by bch »

nextos wrote: post #45
downWidOutaFite wrote: post #34

Earlier quoted context omitted.

This doesn't sound right. Soap is considered nontoxic. We all ingest soap residue from dishes and other hygiene and I've never heard anyone concerned about it.

Actually residue from fancy dish soaps is known to be a gut irritant, see https://www.sciencedirect.com/science/article/pii/S009167492... For this reason, I stick to either first-generation soap (made by saponification) or simple surfactants. In general, as a precautionary principle, it is always good to stick to simple products that have been around for a long time.

Lead and asbestos beg to differ. I mean, your admonition works when it works, but…

Re: How Soap Works: The Science Behind Handwashing

#84

Post by edbaskerville »

teach wrote: post #70
elhudy wrote: post #62

I was always under the impression that the purpose of soap isn’t to kill bacteria/viruses as the article implies, but to wash those thing off of your hands. Was my impression wrong?

I'm not an expert on this either, but I think it's true that IN GENERAL a lot of the value in soap is just "debulking". It does do that very well. But in the specific case of COVID-19 soap happens to also destroy the virus particles and that turns out to be pretty valuable too. :)

Non-expert, but soap disables not just COVID-19 but also most other viruses and bacteria.

Also, water alone does a lot to wash them away. Found this study of no-washing vs. water-washing vs. soap+water-washing with a quick search:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3037063/

No washing: 44% of hands intentionally touching doorknobs and railings had bacteria

Water alone: 23%

Water + soap: 8%

(edit: line breaks)

Re: How Soap Works: The Science Behind Handwashing

#86

Post by senderista »

jyoung789 wrote: post #8
ProjectArcturis wrote: post #4

I understand soap molecules having polar and nonpolar ends, so that it can help nonpolar things dissolve in water. What I've never understood is, why doesn't soap clean off pine sap?

I don’t have a real answer for you but I will say that olive oil works well for this. I worked on a Christmas tree lot through my winters as an undergrad and olive oil always worked well. Of course then you need soap and water to remove the olive oil.

Also works for jackfruit residue.

Re: How Soap Works: The Science Behind Handwashing

#87

Post by ska »

TeMPOraL wrote: post #78
ska wrote: post #53

Earlier quoted context omitted.

IIRC This is why "goo gone" product is really good with many adhesives.

Does it have a generic name for non-American audience?

I don't know if it does. It's the original from here: https://googone.com/original

I imagine there are variations in other places, I think it's mostly concentated citrus oils from oranges.

Re: How Soap Works: The Science Behind Handwashing

#88

Post by agumonkey »

elhudy wrote: post #62

I was always under the impression that the purpose of soap isn’t to kill bacteria/viruses as the article implies, but to wash those thing off of your hands. Was my impression wrong?

A bit of both ? it messes with lipids, either your own lipid layer on the skin where dirt/microbes will lie, or actual cell membranes (also lipids).

Covid news claimed loud that soap will disrupt virus membranes, killing it.

Re: How Soap Works: The Science Behind Handwashing

#89

Post by acyou »

More generally, I'm a huge proponent for washing and drying hands after coming home, after using the bathroom and before eating, in order to disrupt a wide variety of infectious diseases. In particular, I consider the fecal-oral route for a wide variety of nasty parasitic diseases. This has had and continues to have major public health benefits.

There are some other considerations. Water temperature, water hardness, soap composition, handwashing technique.

Re: How Soap Works: The Science Behind Handwashing

#90

Post by gosub100 »

jawns wrote: post #10

This is probably the stupidest question many of you will encounter today, but: If soap has an extraordinary ability to destroy viruses on our skin ... can eating soap give us some of those benefits for viruses that are already in our bodies? I'm not seriously envisioning chowing down on bar soap or using liquid hand soap as a salad dressing. But are there ways to use the _properties_ of soap that make it good for kil…

I did a cursory skim and didn't see any mention of the gut biome. I'm not a medical person but my guess would be ingesting soap would harm the good bacteria.

I asked a similar question to a doctor about inhaling alcohol vapor, if that would kill bronchitis or pneumonia (obviously the answer is NO). I can't remember the specific response, but it's unfortunate because if biology were as simple as computer science: pneumonia/bronchitis is an infection, alcohol kills bugs, ergo breath alcohol vapor to stop infection. I also asked in good faith why an I.V. solution of alcohol wouldn't help with sepsis, and I'm pretty sure the answer is that it _would_ treat sepsis but the concentration would have to be so high that you'd have no liver in the end :(

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