Antimicrobial coatings might make you feel safe but they probably don’t do anything
As offices begin to reopen in the U.S.—even as the number of new COVID-19 infections continues to grow in some areas—many companies are hawking antimicrobial building products that purport to help stop the spread of the virus, from antimicrobial door handles to countertops, light switches, and paint with antimicrobial coatings. The problem: There’s no evidence that these products actually help, and a chance that they may worsen health.
“The reality is, it’s not helping the situation,” says Max Richter, senior associate and co-director of the Materials Performance Lab at the global architecture and design firm Perkins and Will. After a slew of requests from clients about antimicrobial additives, the firm joined with the nonprofit Healthy Building Network to issue a warning about the products. The statement reiterated what the organizations found in a 2017 investigation: the products haven’t been proven to help, and may not be safe.
Many different antimicrobials are used in building products to kill viruses or bacteria, from triclosan and formadehyde to less pronounceable chemicals like methylchloroisothiazolinone or oxybisphenooxyarsine. But no studies have shown that the products are effective. A CDC review for hospitals in 2003 found that “no evidence is available to suggest that use of [products impregnated with antimicrobial additives] will make consumers and patients healthier or prevent disease. No data support the use of these items as part of a sound infection-control strategy.” In 2016, the FDA looked at antimicrobial additives in hand soap and came to a similar conclusion.
While it’s true that antimicrobials do kill germs, it doesn’t happen effectively when they’re coated on something like a countertop. “When you try to apply them to material, you don’t have the dosage level that’s needed to deal with a lot of the viruses or pathogens that you’re trying to get rid of with the antimicrobial,” Richter says. Worse, someone with an antimicrobial product may be less likely to clean it, thinking that it’s capable of disinfecting itself.
Even when a material does reduce the viral load on a surface, that doesn’t necessarily translate into fewer infections. Coronavirus studies have found that SARS-CoV-2 doesn’t survive as long on copper as some other materials, for example. But past studies into copper surfaces have found that while they shrink the number of microbes, there isn’t any strong evidence that shows that results in a reduced rate of infection.
At the same time, antimicrobial coatings could have the unintended effect of creating superbugs. “If the bugs are exposed to antimicrobials that don’t kill all of them off, the next generation of those organisms may develop resistance to antimicrobial treatments,” Richter says. Some people may also have allergic reactions to the additives. Additionally, the products can leach out of materials during use, potentially harming the environment. If something like nano-sized silver—considered toxic to humans and aquatic ecosystems—flows down a drain into a water treatment plant, that’s a problem.
While epidemiologists still don’t fully understand how the novel coronavirus spreads, the evidence so far seems to suggest that it’s more likely to spread through person-to-person contact than through contaminated surfaces. For surface spread to happen, there would have to be a large amount of virus on a surface, it would have to survive, and after someone touched the surface, the virus would have to surface on their hand until they touch their eyes or mouth. There’s a simple and proven way to avoid this—anyone touching something in public spaces now should be frequently washing their hands. Frequent cleaning of surfaces makes sense. But buying new door handles doesn’t.
“We always refer to the Centers for Disease Control or the World Health Organization and all of their guidance on infection control in healthcare settings,” Richter says. “It’s all about source control, hand washing, and then cleaning and disinfecting.”