encounter the glug/pour method of dispens- ing from a half-gallon jug more often than not. All told, QACs are in virtually every place we inspect and are integral to the food, healthcare, and hospitality industries. Their very nature warrants increased oversight to ensure safe use and minimal impact on health and the environment. The most recent occurrence of something being amiss with a QAC disinfectant hap- pened in one of our institutions. Two ser- vice workers simultaneously reported similar rashes and presented with severe skin and hand irritation. This case was not isolated— we had seen similar cases, but this one had a commonality. We immediately went to the automatic disinfectant dispenser system at their duty station and found it was deliver- ing an extremely high concentration of QAC solution, and that personal protective equip- ment, such as gloves, was absent. While it was a simple fix and the workers were successfully treated, it demonstrated the potential harm of a dispenser malfunction and poor training. Moreover, the harm came from contact with a chemical considered safe by most standards and widely held belief. This incident, the recent increase in use, and our extensive experience with QACs got us wondering about the toxic effects of inhala- tion, dermal contact, and ingestion of these widely used products. On this last point, the U.S. Environmental Protection Agency (U.S. EPA) mandates that rinsing does not fol- low application of a sanitizer deemed safe for use on food contact surfaces (21 C.F.R. 178.1010), which includes QACs. Yes, we eat it. And as we learned in basic toxicology, the dose makes the poison. Earlier, we encountered two environmen- tal situations. The first occurred during the height of the COVID-19 pandemic, when a small conventional sewage disposal plant became biologically inoperable after overuse of a QAC detergent/disinfectant destroyed the biome. The sewage plant serves a county building complex that includes a nursing home, three correctional facilities, a train- ing and maintenance center, and several office buildings. In this case, overuse was easy to recognize, and we identified the culprit. QACs, when concentrations exceed recommended limits, leave a waxy residue on floors that accumulates along the wall– floor junction. These areas are discolored (as
Useful References
Cadnum, J.L., Kaple, C.E., Eckstein, E.C., Saade, E.A., Ray, A.J., Zabarsky, T.F., Guer- rero, B.J., Yassin, M.H., & Donskey, C.J. (2024). Dilution dysfunction: Evaluation of automated disinfectant dispenser systems in 10 hospitals demonstrates a need for improved monitoring to ensure that correct disinfectant concentrations are deliv- ered. Infection Control & Hospital Epidemiology, 45 (11), 1362–1365. https://doi. org/10.1017/ice.2024.148 Camagay, A.V., & Connolly, M.K. (2023). Quaternary ammonium compound toxicity. In StatPearls . StatPearls Publishing. Department of Toxic Substances Control Safety Consumer Products Program, & Cali- fornia Environmental Protection Agency. (2024). Background document on quaternary ammonium compounds in cleaning products and beauty, personal care, and hygiene products. https://www.dtsc.ca.gov/wp-content/uploads/sites/31/2024/11/QACs- Background-Document-Final-Accessible.pdf Hora, P.I., Pati, S.G., McNamara, P.J., & Arnold, W.A. (2020). Increased use of quaternary ammonium compounds during the SARS-CoV-2 pandemic and beyond: Consider- ation of environmental implications. Environmental Science & Technology Letters, 7 (9), 622–631. https://doi.org/10.1021/acs.estlett.0c00437 Lim, X. (2020, August 2). Do we know enough about the safety of quat disinfectants? Chemical & Engineering News . American Chemical Society. https://cen.acs.org/safe ty/consumer-safety/know-enough-safety-quat-disinfectants/98/i30 National Pesticide Information Center. (n.d.). Quaternary ammonium compounds ADBAC and DDAC fact sheet. Oregon State University and U.S. Environmental Protection Agency. https://www.npic.orst.edu/factsheets/quats.pdf Ng, M.K., Mont, M.A., & Bonutti, P.M. (2025). Clinical and environmental harms of qua- ternary ammonium disinfectants and the promise of ultraviolet-C (UV-C) alternatives: A narrative review. Cureus, 17 (5), e84022. https://doi.org/10.7759/cureus.84022 Tetro, J.A., Alderson, F.A., & Sattar, S.A. (2024). Is it time to re-evaluate exposure risks to quaternary ammonium compounds as disinfectants? Current Research in Microbial Sciences, 7 , Article 100258. https://doi.org/10.1016/j.crmicr.2024.100258
if soiled) and are sticky to the touch. The waxy buildup is difficult to remove without alcohol, a commercial stripper, or repeated use of a multipurpose cleaner. Prevention is the preferred approach. Routine monitoring is the solution. The second occurrence was similar, but it involved a small food manufacturing plant with an on-site advanced sewage treatment system. Overuse of QACs killed the waste- water treatment system biologically and was due to a vendor over-selling their product with the promise of controlling Listeria . Discharging untreated waste and biologi- cally toxic chemicals into a small creek had an immediate ecological impact far beyond the plant’s boundary. Without nature’s inter- vention, rain and low temperatures, envi- ronmental harm would have been far more extensive. A sanitary evaluation, including assessments of traffic and airflow patterns,
material movement, cleaning methodology, and training, would have prevented this occurrence and saved considerable money on cleaning and remediation. Human and environmental consequences resulting from misuse of QACs prompted us to conduct a quick online search specific to its safety. On the opening screen, we found four pertinent peer-reviewed articles and two fact sheets (see Sidebar), along with U.S. EPA information on the safe use of QACs and their listing under the Federal Insecticide, Fungicide, and Rodenticide Act. Professional Considerations and Action After reviewing readily available literature and reflecting on our own observations, the following are takeaways for further study, questions to ask, and actions to take when QACs are encountered in the field.
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November 2026 • Journal of Environmental Health
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