Are "Bar" Soaps Hygienic?
Over my soapmaking career thus far, I invariably will run into people who will say something to the effect of, "Oh, that's nice what you do....but I prefer to use liquid soap or shower gel from a dispenser, it's cleaner." By "cleaner", they are saying they believe there is less potential bacterial contamination compared to bar soap that may be touched by more than one person.
Actual studies beg to differ:
This study suggests dispenser soap is more likely to transfer bacteria:
Of course, "setting" is a large factor, and how many people have access to and are touching any given method of hand-cleaner; ...an airport bathroom, for example, compared to your own bathroom at home. Bacteria is attracted to and thrives in moisture. The surface of a soap bar is only attractive to bacteria if water remains sitting on it, which is why we promote rinsing off your sudsy bar after use, and using self-draining soap dishes where the bar can dry between uses. Whereas liquid soap is made up primarily of water. If you are concerned about who and how many individuals are routinely touching your soap, hopefully you are as methodical about disinfecting your soap dispenser and it's pump, where touch-bacteria can be constantly transferred.
Another concern of many liquid or gel soaps, is the number of synthetic chemicals used in them which are microbiome disrupters, killing off naturally-occurring microbes that are part of your skin's natural defense. These biocide chemicals (i.e. Triclosan, etc.) leave you vulnerable to opportunistic pathogens. The plastic dispensers most liquid or gel soaps come packaged in can contain BPA, also a microbiome and hormone disrupter leaching into product.
The healthy alternative is to seek products with natural antibacterial properties that do not destroy your microbiome, and are not packaged in plastic. And remember, when it comes to hand-washing, it is the actual ACT of washing that is what is most effective - the CDC recommends 20 seconds minimum of soaping-up before thoroughly rinsing.
As a handcrafted soapmaker and ecology-minded individual, I am biased, but I trust nature over chemicals. I've also lived in households my entire life where bar soap is the norm and we rarely if ever are sick.
Bacteria on hand towels study:
Bacterial studies related to handwashing:
Washing with contaminated soap bar unlikely to transfer bacteria: