[Reading Science] Shared Soap, Is There No Bacteria?

Is solid soap in public places used by many people safe?
Photo by YouTube screenshot

[Asia Economy Reporter Kim Jong-hwa] With the spread of the novel coronavirus infection (COVID-19), handwashing has become extremely important. Health authorities emphasize that you should lather soap and wash your hands under running water for about 30 seconds.

However, the solid soap provided in most offices, government buildings, and public restrooms is used by multiple people. Although some places use liquid soap, most use solid soap due to cost and hygiene concerns. The problem is that this solid soap often does not appear very clean or hygienic.

It can be especially unpleasant when you try to use it right after someone else. Sometimes foam is left on it or fingerprints remain, making it hard to want to touch. Since many people need to wash their hands frequently, is this soap really okay? Could it be teeming with bacteria after passing through many hands?

Soap ingredients consist of fatty acids and alkalis. This helps remove oils on the hands effectively. The reason oil does not wash off easily with water is because it is 'hydrophobic.' Hydrophobic means it does not easily bond with water molecules, the opposite of hydrophilic.

When washing hands, rubbing them together generates frictional heat, which helps remove bacteria and foreign substances. The reason health authorities emphasize rubbing hands together during handwashing is for this reason. It’s not enough to just apply soap to your hands; you need to rub to create frictional heat.

You may understand how to use soap, but still wonder what happens to bacteria on the soap itself? To conclude, there are almost no bacteria on the soap, but there are many bacteria on the soap dish.

Soap has a high pH value, meaning it is alkaline, creating an environment where bacteria find it difficult to survive. In other words, the high alkalinity prevents bacteria from lingering. While many bacteria may be found on the soap dish and in the foam, bacteria in the foam on your hands are washed away quickly, so there is no problem.

These days, many people use hanging soap without a soap dish.
[Photo by YouTube screen capture]

However, according to research, contaminated soap can harbor many bacteria. Old, cracked soap may also have dirt embedded in it. Such soap is likely to be a breeding ground for bacteria. This is one reason why many people now use hanging soap without a soap dish.

Using liquid soap, which is not exposed to the outside, is also a good option, but liquid soap has a higher pH than solid soap. This means it is more alkaline and can irritate the skin. Although liquid soap produces much more foam, if the foam is not properly rinsed off and remains on the skin, it can cause irritation.

Also, even if others have used solid soap after an infected person, the alkali in the soap foam kills viruses during the rinsing process, so there is no risk of infection. The emphasis on washing for 20 to 30 seconds is related to this. Given the current situation, do not hesitate to use plenty of water and wash your hands a little longer than usual.