Can a soap be dirty? In a sense that there are still some bacteria living on it.
In: Chemistry
Not eli5, since I don’t know how to really get it to that level. There are only a couple ways to mostly clean something. One is in an autoclave, which uses pressure and steam mostly to kill almost everything (only a few types of spores survive and it’s exceedingly rare). Bleach and alcohol also work, but those require certain concentrations and/or time frames to really work. Basically, soap isn’t all that good, since it usually only breaks up water surface tension so that the water gets “wetter” and can reach more places. The act of scrubbing your hands together does most of the work.
Now your skin is mostly bacteria. So when you’re using soap (especially bar soap), a lot of that bacteria – both from your skin and the bacteria on your skin from the environment – are pulled off, which is the point. That bacteria can live in the soap for quite some time, feeding on both other bacteria or other things that come out of the air. When things get too rough, they can enter a hibernation-like state or form spores to wait until conditions are better.
Anti-microbial soaps do more than break surface tension of water and have extra things to actively kill bacteria. They work far better, but remember, your skin is mostly bacteria so it’s hard on your skin. There’s a reason why nurses hands look they’re 90 years old. But even then, you can culture bacteria straight from the bottle. Not a lot, but with how fast bacteria grow, it’s enough.
One of my favorite statistics is this: You know the bleach wipes that kill 99.9% of bacteria? What’s 0.01% of 100 trillion? Everything, and I mean everything, is covered in bacteria. NASA missions to Mars that can’t risk contaminating Mars with bacteria from Earth don’t even get close – they just assume that when they land somewhere, you won’t be able to look for life after a certain point because the risk of contamination is high. The second you pull things out of the autoclave, they have bacteria from the air land on them. There’s bacteria that can survive space, that can survive underwater vents with temperatures and pressures that make pressure cookers look comfortable, and that can survive on any place we’ve ever found on this planet.
Yes it can be. Bacteria love to grow in damp, dark, warm places such as underneath a bar of soap in the bathroom. It’s also worth noting that every person in your household should be using their own bar of soap due to the risk of transferring bacterial between members. I’ve had patients who gave their SO a staph infection from sharing soap. Also had one that kept getting recurrent bacterial infection in his face because of bar soap. Using liquid body wash is much more hygienic. If you must use bar soap, put it in a place where both sides can dry. If you use a body scrub/loofah make sure those dry thoroughly as well.
Soap is an EXCELLENT source of food for bacteria, especially when coupled with water. As others have said, it’s the surfactant properties of soap that clean you, it is in no way antibacterial. You should see some of the stuff that grows from cultures of soap that isn’t made in a super sanitary way.
Source: I work for a large soap manufacturer.
Yes, it is advised that immunocompromised individuals should avoid bar soap and cloth hand towels and instead should use liquid soap and paper towels
Latest Answers