WEBVTT - How Dirty Is Soap?

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<v Speaker 1>Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,

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<v Speaker 1>it's Christian Seger. It's good hygiene to wash your hands

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<v Speaker 1>after using the restroom and after touching kind of gross stuff,

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<v Speaker 1>you know, like raw meat, snakes, cat litter, cats, biomedical waste,

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<v Speaker 1>and any number of shared surfaces from door knobs to countertops.

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<v Speaker 1>But what about soap? Bars of soap are also shared surfaces.

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<v Speaker 1>So how dirty is soap? Soap is absolutely seething with bacteria,

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<v Speaker 1>But you know, so is your face, and so so

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<v Speaker 1>is my face and everything we come into contact with

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<v Speaker 1>all day, every day. Really, organism for organism, microbes outnumber

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<v Speaker 1>humans on the planet at least a hundred and thirty

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<v Speaker 1>one quintillion to one. Sell for sell, The microbes in

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<v Speaker 1>and on our bodies outnumber us ten to one, and

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<v Speaker 1>human hands can have up to one hundred thousand micro

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<v Speaker 1>organisms per square centimeter of skin. Most of them are

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<v Speaker 1>harmless or you know, even helpful, but yeah, there's a

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<v Speaker 1>lot of them, and some of them get transferred to

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<v Speaker 1>your soap. One study from reported that of the bar

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<v Speaker 1>soaps they tested, two tocent cultured positive for micro organisms.

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<v Speaker 1>The antibacterial soap they tested actually had a bit more

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<v Speaker 1>microbial activity than regular soap. The soaps in question were

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<v Speaker 1>in use by the staff of clinics and laboratories over

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<v Speaker 1>the course of seven days, and samples were taken on

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<v Speaker 1>five of those days. But the interesting and comforting part

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<v Speaker 1>of their results is that the microbes didn't build over

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<v Speaker 1>the course of that week. Organisms would appear and disappear

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<v Speaker 1>with each sample taken, indicating one of two things. Either

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<v Speaker 1>the soaps were somehow self sterilizing, possibly due to preservatives

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<v Speaker 1>they can tane that are you know, not delicious or

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<v Speaker 1>downright dastardly to microbes, or the little buggers were being

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<v Speaker 1>mechanically removed during the process of washing, meaning that as

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<v Speaker 1>you wash your hands, you're also washing your soap. These

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<v Speaker 1>results back up a couple of other studies about microbes

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<v Speaker 1>and hand washing, one from ninety and one from The

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<v Speaker 1>former study had subjects come into their lab, douse a

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<v Speaker 1>hand in a vat of bacteria, and then wash with

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<v Speaker 1>a bar of soap. The soap was tested for the bacteria,

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<v Speaker 1>then given to another subject to assess the transfer of

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<v Speaker 1>the bacteria. The latter study carefully doused bars of soap

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<v Speaker 1>with ecle i and had subjects come in and first

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<v Speaker 1>sterilized their hands, then wash them with this gross soap.

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<v Speaker 1>The researchers then tested both the hands and the soap

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<v Speaker 1>for microbes. Both of these studies found that although bacteria

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<v Speaker 1>remained on the soaps, none transferred to the participants hands.

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<v Speaker 1>Now here's the thing to note. These studies were done

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<v Speaker 1>by employees of Procter and Gamble and Dial Corporation, respectively,

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<v Speaker 1>and the first study I mentioned that one from that

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<v Speaker 1>was completed with a grant from Minnatonka Incorporated, which was

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<v Speaker 1>the original maker of soft soap. That doesn't necessarily mean

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<v Speaker 1>their science was bad, though experts say there's no evidence

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<v Speaker 1>to contradict their results. So bar soap is not underty,

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<v Speaker 1>but it's still safe to use and way better than

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<v Speaker 1>not washing. So here's a few pro tips. Be sure

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<v Speaker 1>to dry your hands thoroughly after washing. Don't wash more

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<v Speaker 1>often than necessary. That can lead to parched skin, which

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<v Speaker 1>can crack, which can let in microbes. You otherwise would

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<v Speaker 1>have been able to just wash off. And make sure

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<v Speaker 1>you store bar soap in a dish that lets it

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<v Speaker 1>drain and dry out between uses. That'll cut down on

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<v Speaker 1>any potential bacterial growth. Check out the brainstuff channel on YouTube,

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<v Speaker 1>and for more on this and thousands of other topics,

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<v Speaker 1>visit how stuff Works dot com.