What would be a good percentage of germs for an anti-bacterial soap to kill?

anti-bacterial soap only compounds the problem by being introduced into the water stream. Our best bet is to use ordinary soap and water. I think a total kill off of germs and bacteria is part of the problem, because the bacteria that lives in our guts, and exists in the soil actually are beneficial. We are never going to achieve 100% sterility in ordinary environments, and to do so would probably eventually be a bad thing. Without exposure to some germs, viruses and bacteria, how can our immune system build the anti-bodies to fight these things?

I know that isnt a direct answer to your question, but I’d say anything under 80% would probably be enough.

Regular soap and water is much better than anti-bacterial soaps and cleaners. Studies show that kids raised with normal amounts of dirt and normal exposure to germs and with animals have many fewer allergies.

Our immune systems work better when they are exercised.

@Marina, any idea what percentage of germs are eliminated just using regular soap & water?

Well, if antibacterial soap kills 99.9% of germs and normal soap works just as well, then I assume that normal soap will rid you of 99.9% of germs, too. The main thing is to make sure the soap lathers and scrub well for a few minutes, and make sure not to re-contaminate yourself with the tap handle etc. My mom was taught when she worked in a hospital to shut off the water with her wrist or elbow to avoid this.

@evelyns_pet_zebra touched on this, but I think it bears repeating. It’s not bad to get rid of germs by washing your hands, the problem with antibacterial soap is that it gets into the environment and kills germs that can’t withstand it (leaving the ones that can, thus selecting for anti-bacteria-resistant superbugs). Normal soap doesn’t do this. Killing the germs on your hands with normal soap is fine!

Here is some data from Columbia:

“Regular household soap or cleanser does not kill germs — rather, it suspends (or lifts) them off the skin surface, allowing the microscopic critters to be rinsed down the drain.”

That, however, is effective. The Mayo Clinic says this (emphasis mine):

“Antibacterial soaps have become increasingly popular in recent years. However, these soaps are no more effective at killing germs than is regular soap. Using antibacterial soaps may lead to the development of bacteria that are resistant to the products’ antimicrobial agents — making it even harder to kill these germs in the future. In general, regular soap is fine. The combination of scrubbing your hands with soap — antibacterial or not — and rinsing them with water loosens and removes bacteria from your hands.”

Here is another problem with hand sanitizers:

“In several randomized, well-controlled, parallel, and blinded, clinical studies antiseptics (sanitizers) containing alcohol killed 99.99% of the microorganisms on human skin. The microorganisms killed included both “harmful” and “normal flora” bacteria and fungus.”

@Marina, that all sounds contradictory. Not trying to be argumentative, but it’s hard for me to hold these two sentences in the same state:

- “Regular household soap or cleanser does not kill germs — rather, it suspends (or lifts) them off the skin surface, allowing the microscopic critters to be rinsed down the drain.”

- “Antibacterial soaps… are no more effective at killing germs than is regular soap.”

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The first says regular soap doesn’t kill germs. Indeed we know this to be true because a soggy bar of soap is a veritable breeding ground for microscopic bugs.

Anti-bacterial soap has long advertised a 99.9% kill rate… an advertising practice that I doubt would be allowed were it not true to a point. Perhaps the Mayo Clinic’s study was based on how people typically use anti-bacterial soap… that is, not leaving on long enough to be fully effective.

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The first point, however, does answer my direct question of you. Namely, that soap doesn’t kill bacteria… it simply helps remove them – as well as dirt, grime, oils, etc. – so that your hands are clean.

Point is then, soap is best for getting you clean. Anti-bacterial agents serve a targeted purpose and one that long-term could prove more harmful than beneficial.

@robmandu I understand where you are coming from. I almost did not put in the Mayo Clinic quote, because I thought the use of the word “killing” was sloppy writing. (Professional editor disease). I would have said “removing” germs.

I think the key to resolving the apparent contradiction is here:

“The combination of scrubbing your hands with soap — antibacterial or not — and rinsing them with water loosens and removes bacteria from your hands.”

The site also has hand washing instructions.

Here is a some information on the 99.9 % claim, which apparently is not quite as sold as one would think:

“In a review of the research, Barbara Almanza, an associate professor at Purdue University who teaches safe sanitation practices to workers, came to an interesting conclusion. She notes that the research shows that hand sanitizers do not significantly reduce the number of bacteria on the hand and in some cases may potentially increase the amount of bacteria on the hand. So the question arises, how can the manufacturers make the 99.9 percent claim?

How can the manufacturers make the 99.9 percent claim?

The manufacturers of the products test the products on inanimate surfaces hence they are able to derive the claims of 99.9 percent of bacteria killed. If the products were fully tested on hands, there would no doubt be different results.”

Finally, I found this study with actual data, but it is self-published and there is no attribtuion:

“By Freshman bio student (Guest Post)
I recently did a study on the effectiveness of bar vs. liquid soap in my bio honors class. We made agar plates in sterilized petri dishes. We then brought in bar and liquid soap. We used 1.8 grams of liquid soap and 1.8 grams of bar soap shavings. we washed our hands in the exact same way with the liquid and bar soap. then we touched our hands to the agar and incubated the petri dishes for 48 hours at 37 degrees Celsius which is 98.6 degrees Fahrenheit. We then went back the next monday and we calculated the percentage of the germs on the plate. The liquid soap had 4% bacteria covering the petri dish the bar was 11% and the control group was 23% of the area of the agar.”

An excellent discussion. Here is a useful link on hand washing from the CDC.

I would say a good percentage of germs for a soap to kill is 0%, a good percentage for it to wash away is 100%.