During the COVID-19 pandemic, disinfectants became our shield. Hand sanitizers, disinfectant wipes and antimicrobial sprays became part of daily life. They made us feel safe. Today, they are still everywhere: in homes, hospitals and public spaces.

But there’s a hidden cost. The chemicals we trust to protect us may also inadvertently help microbes evolve resistance and protect themselves against antibiotics.

Among the most common active ingredients in disinfectants are quaternary ammonium compounds (QACs). They are found not only in the wipes, sprays and liquids we use to clean surfaces at home and in hospitals, but also in everyday products like fabric softeners and personal care products.

Roughly half of the products on the U.S. Environmental Protection Agency’s (EPA) List N of disinfectants effective against SARS-CoV-2 and List Q for emerging viral pathogens contain QACs.

Due to their widespread use, QACs enter wastewater treatment plants in substantial amounts, with effluents and sewage sludge being the main pathways through which QACs are released into the environment.

Within wastewater treatment plants, more than 90 per cent of QACs are typically removed, but small amounts........

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