Toxic ingredient in disinfectants can give rise to antibiotic-resistant bacteria, birth defects and more

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Experts are raising the alarm about a certain family of chemicals that are found in several commercial cleaning products. Quaternary ammonium compounds, or quats, are charged chemicals that can kill bacteria, viruses and other microorganisms. But though they are effective disinfectants, researchers found that quats can give rise to serious health and environmental problems, including antibiotic resistance, birth defects, fertility issues and marine toxicity.

Health and environmental hazards of quats

The COVID-19 pandemic increased the demand for cleaning products such as Lysol wipes that use quats as active ingredients. The sales for Lysol wipes, for instance, jumped by nearly 50 percent in the spring of last year. Meanwhile, the annual sales of aerosol disinfectants – a large fraction of which contain quats – doubled.

“We’re in an era now where the concentration [of quats] is certainly higher than ever before,” William Arnold, an environmental engineer at the University of Minnesota, told Environmental Health News.

In a study last year, Arnold and his colleagues found that increased concentrations of quats are likely piling up in wastewater plants, which had been unable to keep up with the increase in disinfectant use. Though quats are removed during the wastewater treatment process, according to Arnold and his team, they are still found in marine environments where they can disrupt aquatic food chains.

Quats can spur antibiotic resistance

Quats can also encourage the rise of antibiotic-resistant germs. Many kinds of bacteria are getting better at recognizing quats, said Kevin Minbiole, a Villanova University chemist who studies how quats affect bacteria and viruses.

Bacteria can also develop broad resistance that blocks attacks from other kinds of antiseptics. This “cross-resistance” happens when changes microbes make to survive one threat make them suited to survive other threats too.

“Those changes make bacteria capable of surviving different compounds, different chemicals that it hasn’t seen before,” explained Beatriz Pereira, a recent graduate student in microbiology from the University of California, Davis.

In the lab, Pereira observed bacteria develop resistance to certain types of quats even when exposed to low concentrations. The microbes revamped their defenses to strengthen their outer membranes, which is a common way to develop cross-resistance.

However, it’s not yet clear whether bacteria in the wild can develop antibiotic resistance with the current levels of quat pollution. But to Pereira, those lab experiments suggest that the best way to address antibiotic resistance is to consider whether to stop the use of these toxic chemicals.

Quat exposure is bad for health

Theresa Hrubec, a biologist at the Virginia Polytechnic Institute and State University, was carrying out research on mice when she observed that her animal subjects were developing birth defects. After ruling out any experiment mistakes on her part, she surmised that the mice might have been unintentionally being dosed with quats. The facility had just started to use quats for disinfection.

Since then, Hrubec conducted a few animal studies linking quats to birth defects and decreased fertility. For those studies, she and her team fed mice a mixture of two common quat disinfectants at high doses for several weeks before assessing them for either fetal birth defects or signs of decreased fertility.

The mice exposed to quats were found to be more likely to develop neural tube defects, an early-stage birth defect. Meanwhile, the number and size of litters born declined.

Quats may also inflame the lungs. A 2010 mice study shows that inhaling high concentrations of quats can increase levels of inflammation and cell death. Hrubec and her team also performed a study on humans and found that quat levels in the blood are associated with higher inflammation levels and decreased mitochondrial function. While their results are preliminary, the study is among the first to monitor quat levels in humans.