COVID disinfectants may contain harmful chemicals, researchers say

Nov 01, 2023

The World Health Organization (WHO) recently declared that COVID-19 is no longer a global public health emergency, but the virus will continue to circulate and retain its pandemic status — though the risk of death and severe illness has significantly declined.

Before we understood how COVID-19 spread, keeping surfaces clean seemed to be a safe bet for lowering transmission rates. While this is a good practice, COVID-19 is primarily spread through airborne particles.

A new review investigates the safety of some compounds commonly found in surface cleaning products, the use of which use rose sharply during the early days of the COVID-19 pandemic.

These disinfectants include cleaning sprays and antibacterial wipes used in the home, in schools, and in healthcare settings.

The review shows quaternary ammonium compounds (QACs) in disinfectant products have been associated with health issues, and that their overuse likely contributes to the growing problem of antibacterial resistance.

Further, disinfectants containing QACs are no more effective at killing SARS-CoV-2 than soap and water.

The study is published in the peer-reviewed Environmental Science & Technology journal.

QACs are popular with manufacturers in part because they are non-corrosive on surfaces.

QACs include compounds such as benzalkonium chloride, dimethyl benzyl ammonium chloride, and benzethonium chloride. They are found in many surface-cleaning products, according to the study.

Previously, animal studies have suggested that QACs may disrupt the immune system, and can cause male and female infertility in offspring. But the compounds had not yet been tested extensively on humans.

Study co-author Dr. Erica Marie Hartmann, PhD, associate professor of civil and environmental engineering at Northwestern University, told Medical News Today that there is existing evidence that QACs are irritants that are harmful to the skin and lungs.

"Chemicals get put into use much, much faster than we can test them and study their impacts," Dr. Hartmann said.

Dr. Hartmann noted that earlier antimicrobial agents such as triclosan fell out of common use in the United States when they were banned from handwashing products in 2016.

QACs were exempt from that ban due to a lack of safety health research at the time.

Their use in cleaning products has "skyrocketed," Dr. Hartmann said, adding that she expects that as exposure to QACs increases, researchers will start to see more evidence of their unwanted effects.

"The acute toxicity [threshold] is high, meaning it takes a large amount to see toxic effects right away. This gives the impression that QACs are safe," study co-author Terry Hrubec, PhD, professor of anatomical sciences at The Edward Via College of Osteopathic Medicine in Blacksburg, VA, explained to MNT.

"The problem comes with the day-in and day-out exposure over time, which studies are now showing is unsafe," Dr. Hrubec added.

Soap or detergent and water are more than sufficient for killing SARS-CoV-2 on surfaces, Dr. Hartmann said.

"It's not a very hardy organism, so a regular detergent is fine for cleaning purposes," said Dr. Hartmann.

Vaccination is the most effective way to avoid severe illness or death from COVID-19. While the pandemic is no longer a global health emergency, immunocompromised people may continue to protect themselves by wearing a mask and receiving regular booster shoots.

Still, handwashing and general sanitizing with alcohol-based products are still valuable for protection from SARS-CoV-2 and other viruses.

Experts contributing to a recent New York Times article on the overuse of disinfectants shared that they rarely, if ever, use disinfectants in their homes. They also revealed a preference for homemade cleaners, including water-based mixtures with small amounts of dish soap and added baking soda for especially dirty areas.

The review raises another concern regarding the role of these chemicals in antimicrobial resistance.

"Every time we use an antimicrobial, we provide an opportunity for microbes to adapt and become more resistant," Dr. Hartmann explained.

She noted that a pathogen may become more resistant to the antimicrobial in the cleaning product and also to antibiotic drugs.

"Bacteria that become resistant to antibiotics are one of the biggest emergencies in medicine today," Dr. Hrubec added. "It would knock medical treatments back 100 years if we lose the ability to use antibiotics."

According to the WHO, antibiotic resistance is reaching dangerously high levels all over the world.

The WHO notes that serious infectious diseases such as pneumonia, tuberculosis, blood poisoning, gonorrhea, and various food-borne diseases are becoming ever more difficult, or even impossible, to treat.

In addition to the cost to human health, antibiotic resistance is also making treatment more expensive. As common antibiotics fail, more expensive drugs are required, potentially putting treatment out of reach for more people.

Surgeries and treatments including organ transplants, cesarean sections, and chemotherapy also become more dangerous as antibiotic resistance spreads.

Dr. Hartmann noted that the medical field has "recognized this risk and responded with antimicrobial stewardship."

"This is a really good first step in thinking about how we use antimicrobials. We need to apply that thinking, using antimicrobials only when necessary, to other fields like cleaning products."

– Erica Marie Hartmann, Ph.D., study co-author