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This month’s discussion of disinfectants concludes with how disinfectants are different from sterilants.
Both products kill germs and are for use on inanimate (not living) surfaces; however, the major difference between a disinfectant and a sterilant is that sterilants destroy bacterial spores as well as active, growing colonies.
Bacterial spores are very durable life forms, so it takes strong chemical action and extended contact time to destroy them. Typical sterilant actives include chemicals such a peracetic acid, ethylene oxide (a gaseous material) and glutaraldehyde.
Making the right choice
You might ask yourself: If sterilants are so much more effective than disinfectants, why not use them in place of disinfectants?
The main reason is that sterilants have higher toxicity and are typically used in controlled conditions, such as in a medical environment.
For example, a device that penetrates the skin must be 100 percent free of microbial contamination. You don't want any bacterial spores getting into the bloodstream during an injection, because the body provides the perfect environment for bacteria to flourish: Warmth and moisture.
This is why most medical devices, such as scalpels, needles and sutures, must be sterilized prior to use. In contrast, normal environmental cleaning does not require complete elimination of bacterial spores.
Know your facts
Sometimes the term “sterilizing” is used interchangeably with “sanitizing” or “disinfecting.” You might hear someone claim that they are “sterilizing” a carpet or wall.
While you can do this in theory, it just doesn't happen in practice except in specialized industrial applications. And as you might expect, sterilants require government registration.
Dwell on it
Dwell time is one of the most important yet most misunderstood references found on all disinfectant labels. A dwell time is the number of minutes that an applied product must be in contact with the surface and remain wet in order to ensure compliance. On many product labels, dwell time is indicated with phrases like “must remain wet for” or “contact time.”
Most labels call for a 10 minute contact time; for a cleaner, that may seem like a long time. However, in disaster restoration applications, a 10 minute dwell time is not unreasonable and in most cases, the area being treated will easily remain wet for the required period.
Ten minutes is a standard “rule of thumb” for dwell time. Disinfectant products that indicate dwell times of less than 10 minutes are able to do so because the manufacturer have conducted additional testing to show efficacy with shorter dwell times.
Typically, however, these tests are specific to a certain organism. This feature is handy if you know that only that organism is on the surface, but if you are not sure (and you usually aren’t), use the standard dwell time of 10 minutes.
This concludes our two-part series on disinfectants. The proper selection, handling and use of disinfecting agents to controlling microbial activity — and the odors, health hazards and secondary damages they can cause — is critical to successful restoration and cleaning.
Mike Kerner has been senior scientist with Legend Brands since 2009. He has 30 years of experience related to cleaning and restoration chemistry. Kerner provides technical support for chemical products in the various Legend Brands divisions including Dri-Eaz, ProRestore and Sapphire Scientific. He recently started providing technical support for Chemspec, a Legend Brands partner company.