Have you ever questioned the cleanliness of a bar of soap that is reused by each member in a household?
This thought has crossed my mind on numerous occasions, although I have yet to come across an individual who can comprehend and explain the reasoning behind this concept on the behalf of my understanding.
“Bacteria are everywhere on your skin, hair and eyelashes,” so we should not be surprised, by the fact, that they are also found upon the surface of the bars of soap let alone pays a contribution in its materialization. “As long as the bacteria keep their numbers small, there’s nothing wrong with them living in soap.”
Similarly, to how certain vaccinations contain the dead forms of viruses, even though soaps composition consists of live bacteria, it still cleans hands effectively. “Any cosmetic product in the U.S. in a public setting or a home setting, it’s going to have some normal bacteria that don’t cause any illness.”
“You’re only trying to reduce the number of bacteria [on your hands] to give your immune system a fighting chance.”
So knowing that no soap is free of bacteria, how does a soap-maker proceed?
“You need to make sure that microbes won’t take advantage of the situation and proliferate,” says Dave Shumaker, a microbiologist at GOJO Industries. To that end, most products have antimicrobial agents built into the recipe, even if they are not labeled as antibacterial. Soap- and shampoo-makers call these agents the soap’s preservation system. Without a preservation system, bacteria would munch on the surfactants and lipids.
Soap and shampoo companies employ someone like Shumaker to make sure that the preservation system works and that an unopened product will last three years on the shelf. To test that system, he might use bioluminescence to detect any metabolic products — signs that some sort of organism is converting nutrients into energy. Alternatively, he might dilute the sample and culture it on a Petri dish to count how many bacteria colonies form.
The FDA has set upper limits for bacteria in cosmetics and hygiene products. A product used around the eyes must contain fewer than 500 colony-forming units per milliliter, a standard measure of how many bacterial cells are living in a substance. A product for use elsewhere on the body must contain fewer than 1,000 colony-forming units per milliliter.
Another common test involves adding bacteria to products to see how the preservation system fights back. After all, there are many bacteria in a home that could contaminate a product at any time especially in the bathroom. However, as long as the antimicrobial agents are working, bacteria in the soap should not increase in number.