UW study finds applying UV light to common disinfectants makes them safer to use

KITCHENER -- A new study from the University of Waterloo has found that over 400 common disinfectants currently in use could be made safer and more effective if ultraviolet light is applied.

In a news release sent out Monday, researchers note that Benzalkonium chloride (BAK) is the most common ingredient used in most disinfectants.

They say the chemical can protect against a wide range of viruses and bacteria, including COVID-19, and is most often found in disinfectants used in hospitals, households and food processing plants.

Researchers say that while BAK is necessary for a disinfectant’s efficacy, the toxicity of the chemical means it can’t be used in high concentrations and can be harmful to people and the environment.

They say the chemical can cause irritation on human skin and eyes, as well as prove to be harmful to the environment; especially fish, aquatic invertebrates and birds.

“With concerns about the spread of COVID-19, people are utilizing products with BAK as an active ingredient more than ever,” said Waterloo alumnus and lead author Dr. Manlong Xu, who is currently a clinical research fellow in the University of Alberta’s Department of Ophthalmology and Visual Science. “For many industries, there is the demand to improve the efficacy of standard disinfection procedures, while also keeping in mind any potential negative impact on the environment.”

However, researchers discovered that the chemical’s toxicity could be completely neutralized using ultraviolet light.

“Our results show that a disinfecting procedure using BAK followed by UVC radiation can minimize the harmful effect of BAK residues on humans and the environment,” said Dr. David McCanna of Waterloo’s Department of Optometry & Vision Science in a news release. “Such a procedure also has a great potential to maximize the disinfection efficacy by utilizing two different antimicrobial mechanisms.”

McCanna noted that their findings are especially significant during the pandemic, and provide another method to make hospitals, food, homes and the environment safer.