Quaternary ammonium compounds: From cleaners to environmental contaminants?

Quaternary ammonium compounds (QACs) are ubiquitous in everyday products and have been widely used for several decades due to their surfactant-like behavior and antimicrobial properties. They play essential roles in healthcare, consumer products, food and beverage processing, textiles, leather industries, and agriculture. The increased use of QAC-containing sanitizers and disinfectants during and after the COVID-19 pandemic has intensified concerns about their environmental occurrence and persistence. QACs have been frequently detected in diverse environmental matrices, including wastewater, surface water, soil, sediments, ambient air, and even human body, raising questions about their long-term impact on ecosystems and human health. Exposure to QACs has been linked to several ecological and human health impacts, underscoring the need for a deeper understanding of their risks. Given these concerns, this chapter provides a comprehensive review of QACs, examining their chemical structures and properties, pathways of environmental release, occurrence, and fate and transport in various ecosystems. It further explores their potential ecological and human health risks. Additionally, the chapter discusses effective mitigation and remediation strategies, such as advanced wastewater treatment technologies, the development of biodegradable alternatives, regulatory policies, and sustainable practices to minimize their environmental burden and safeguard public health.