The COVID-19 pandemic has called for the increased use of disinfectants worldwide in public facilities, transportation, hospitals, nursing homes, wastewater treatment facilities, and even common households to mitigate virus burden. Active ingredients in common disinfectants recommended for use against COVID-19 viruses include chemicals such as quaternary ammonium compounds (QACs), hydrogen peroxide, bleach (sodium hypochlorite), and alcohols. These disinfecting chemicals differ in their structures, properties, modes of action, environmental behaviors, and effects on human health upon exposure. Humans can be exposed to disinfecting chemicals mainly through dermal absorption, inhalation, and ingestion. The total exposure and relative contribution of each exposure route vary considerably among the disinfectants. QACs have been linked to occupational illnesses such as asthma and an increased risk of chronic obstructive pulmonary disease (COPD), whereas excess use of bleach, hydrogen peroxide, or alcohol-based disinfectants can cause respiratory damage and has been linked to an increased risk of developing and controlling asthma. Recent studies showed that the presence of QACs in human blood has been associated with changes in health biomarkers such as an increase in inflammatory cytokines, decreased mitochondrial function, and disruption of cholesterol homeostasis in a dose-dependent manner. Therefore, repeated human exposure to disinfectants during the pandemic has raised questions on exposure-related long-term health risks and occupational safety. Furthermore, in lieu of a lack of adequate knowledge and public awareness, these chemicals have been frequently used on porous surfaces, including fabrics/textiles and consumer plastics and even for disinfecting cloth facemasks, on which disinfectant chemical residues may persist for longer duration, causing potential degradation of plastic materials, releasing additives, and shedding microplastics. In addition, the increased use of these disinfectant chemicals and the subsequent discharge into wastewater may cause adverse impacts on aquatic ecosystems, accumulation on vegetables, and contamination of the food chain via wastewater irrigation and sludge application. This article provides a well-rounded understanding of the most common disinfectants and reviews modes of action of those disinfectants, their interactions with aquatic and terrestrial environments, the exposure to humans, and potential impacts to human health and safety.

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