Clinical and Environmental Harms of Quaternary Ammonium Disinfectants and the Promise of Ultraviolet-C (UV-C)...

Quaternary ammonium compounds (QACs) are widely used disinfectants whose application expanded dramatically during the COVID-19 pandemic, raising concerns about long-term safety and environmental impact. This narrative review begins by outlining the chemical structure, mechanisms of action, and widespread use of QACs across healthcare, consumer, and industrial settings. We examine toxicologic findings from in vitro and animal studies, highlighting mitochondrial dysfunction, oxidative stress, and reproductive toxicity at low-dose exposures. Clinical and public health data are reviewed, linking QAC exposure to respiratory symptoms, dermatitis, and potential reproductive risks among healthcare workers and other vulnerable populations. Environmental harms are also discussed, including QAC persistence in soil and water, ecotoxicity in aquatic species, and potential for bioaccumulation. We then explore ultraviolet-C (UV-C) disinfection as a non-chemical alternative, demonstrating comparable antimicrobial efficacy without the toxicological or ecological drawbacks of QACs. Despite the growing use of QACs, few studies have comprehensively reviewed their adverse effects or evaluated UV-C as a viable substitute. This narrative review fills a critical gap by synthesizing current evidence across disciplines and highlighting the need for safer disinfection practices. We advocate for the broader adoption of UV-C technologies to reduce chemical exposure, protect public health, and promote environmental sustainability.