What Does The “Kills 99.9% Germs” Label Mean? Why And How Do Companies Get Products Tested?

Eliminating 99.9 or 99.99 percent germs is a label we have all come across. Hand sanitizer, paints, soap solution, toilet cleaner, bleach. But what does it really mean? The logical response to looking at labels with 99.99% and 99% effectiveness is to assume the former is better than the latter.

However, individual substances, surfaces, and fluids differ across various metrics. They may also have distinct efficacy claims, contrasting active ingredients, and dilution ratios.

Microbe Investigations Switzerland (MIS) has worked on thousands of different products for customers across the globe and can help you test your product to support your claims.  

So, what does the 99.9% mean?

99.9 and 99.99 percent is a precise number, but not quite in the way one typically thinks. Let’s break it down, shall we?

When a marketing claim of “kills 99.99 percent of germs” is used, it designates the specific bacteria or pathogen it has been tested against. This implies that the efficacy is being measured against a particular pathogen “A”. However, this does not mean the same disinfectant will demonstrate the same efficacy against another pathogen “B”.

Scientifically, the potency of a disinfectant is measured by the “microbicidal effect”. This is also known as “log reduction” or log kill. 

By extrapolating, we can figure out that with each subsequent log kill the number of organisms left is reduced by 10-fold, that is, by one decimal point.

Now, let us get microscopic. When the microbes being counted are microscopic, the implications of 0.1% are significant. This means the differences between 99%, 99.9%, 99.99%, 99.999%, and so on are considerable. 

Also Read: Antimicrobial vs Antibacterial: What is the Difference?

Why do hand sanitizers only kill 99.99?

The use of the phrase “kills 99.9 or 99.99 percent of germs” is a common marketing claim used by hand sanitizer/ disinfectant manufacturers to emphasize the effectiveness of their products. Such claims indicate that hand sanitizer demonstrates a high level of efficacy against a wide range of microorganisms, but also acknowledges that there may be a minimal chance of some germs surviving or being resistant to the hand sanitizer.

Achieving a 100% kill rate  is challenging  due to the complexities of real-world environments. Additionally, the effectiveness of a product is also influenced by other factors such as product concentration and contact time adjustments by end users.

The label claims like “kills 99.99% germs” made by hand sanitizer manufacturers are typically based on general guidance on the product’s intended use and effectiveness. These claims often encourage users to follow the instructions for use and maintain realistic expectations about the product’s capabilities.

Why are products tested?

Validation of the products distributed for commercial and personal use is essential. This validation helps in creating a trail of documented evidence of the capabilities of the product ranging from consistently eliminating or inactivating known or possible pathogens from inanimate objects.

Further, disinfectants used in infirmaries, manufacturing industries, and laboratories must be tested regularly to confirm their strength and effectiveness.

Additionally, international regulations stipulate that disinfectants must list the microorganisms against which a product has been tested for and found to be effective on their label, the correct dilution, and the directions for use. 

The protocols followed, testing to be done vary based on national regulations and compliance procedures. 

Efficacy testing standards

Based on a product’s classification and assertions, the following tests are mandated for testing efficacy:

• Germ kill efficacy test
• Hand rub and hand wash studies
• Minimum Inhibitory Concentration (MIC)
• Virucidal activity against the standard list of human viruses including Betacoronavirus models

Also Read: Evaluating the Efficacy of Chemical Disinfectant with EN 14476

Microbe Investigations

At Microbe Investigations [MIS], we simplify the quantification of the antimicrobial activity of your products. Our testing laboratory has ISO certified antimicrobial tests that are regularly updated with the emergence of new technologies like ISO 18184, EN 1276, EN 14476, ISO 20743, ISO 21702, ISO 22196, etc.

Companies looking to register specific products ranging from paints to disinfectants to hard surfaces must offer detailed chemical characterization, safety, and efficacy data to regulatory bodies. 

At MIS, we work to test various products ranging from plastics, disinfectants, fabrics, etc to determine the efficacy under the environmental conditions they will be used. We validate the efficacy and ensure the microbial test requirements are reproducible, of the highest quality, and affordable.

You can connect with us for queries.