Background
In referring to chemical hygiene products which we have all come to appreciate and rely on with the advent of the COVID-19 pandemic, the words sanitizer and disinfectant are often used interchangeably. Many of us only recently started checking chemical hygiene product labels for the first time in a long time just to verify the presence of a claim against SARS-CoV-2, the virus that causes COVID-19. In doing this, the words sanitizer and disinfectant always feature but many don't know the difference. If this is you, do not beat yourself up. You are not alone! I first read a chemical hygiene product label in 2018 during my Ph.D. research.
Sanitizer or Disinfectant?
In the viewpoint of the US Environmental Protection Agency (EPA), sanitizers and disinfectants are utterly different. They are so different that the EPA has different performance and registration standards for them. For example, a product will only be registered as a nonfood contact surface sanitizer if it reduced at least 99.9% of bacteria within a 5 min contact time. However, for an antimicrobial product to qualify as a nonfood contact surface disinfectant, it must irreversibly inactivate or destroy at least 99.999% of bacteria on a surface. Notice that for a disinfectant, there are many more nines. This makes a huge difference. A smart reader like yourself is thinking these differences only represent increments of 0.9, 0.09 and 0.009. So what's the big deal? In the world of microbiology and antimicrobial product efficacy, each nine in the percent reduction shaves one zero off the total number of bacteria on a contaminated surface. Assuming there are 10,000,000 bacteria cells on a surface, a 99.9% reduction will leave 10,000 cells on the surface while a 99.999% reduction leaves 100 cells on the surface. Also, notice that sanitizers reduce, whereas disinfectants irreversibly inactivate or destroy microorganisms. The difference is indeed in the details. The EPA selected their words carefully in their definition outlined in 40 CFR 158.2203. Why are we talking about nonfood contact surfaces? Foodborne pathogens can be transferred from nonfood contact surfaces to food contact surfaces and foods; causing foodborne illnesses.
On food contact surfaces, a sanitizer should reduce at least 99.999% of microorganisms within 30 seconds while a disinfectant should destroy 99.9999% of bacteria on hard non-porous inanimate surfaces within 10 min. Again, notice the difference in the number of 9s between sanitizers and disinfectants approved for use on food contact surfaces. Unlike disinfectants, sanitizers do not inactivate fungi and viruses.
The Label is the Law
Sanitizers and disinfectants are designed to help reduce food safety risks if used appropriately. By appropriately, I mean as directed by the product label; which simply described, is the law. Baseline information on the appropriate use of sanitizers and disinfectants usually includes the requirement to clean surfaces before sanitization or disinfection, dilutions allowed and their applications and contact times. Cleaning is the first step; it should always precede the sanitization or disinfection of surfaces except where all-in-one products such as cleaner sanitizer or cleaner disinfectants are being used. A rinse step is often required for food contact surfaces following the cleaning step, with the exception of when a cleaner sanitizer is being used. For the sanitation of food contact surfaces in the US, the EPA mandates that no rinse occurs after sanitizer application. However, for disinfectants used on food contact surfaces, rinsing is usually encouraged after the contact time has elapsed; this is often a requirement in the EU. This is the case because disinfectants generally have higher percentages of active ingredients than sanitizers and may leave residues on the surface. If not appropriately rinsed, these residues could present a food safety risk.
Conclusion
When antimicrobial products are used incorrectly, foodborne pathogens are not reduced or destroyed. As I join the US Centers for Disease Control and Prevention to promote food safety education throughout September 2021, I hope you remember that the best sanitizer or disinfectant used inappropriately will inevitably fail to reduce food safety risk. For more on this topic, I strongly recommend reading a recent publication by Fraser et al., 2021.
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