Quaternary ammonium compounds of emerging concern: Classification, occurrence, fate, toxicity and antimicrobial resistance

Abstract

Amplified hygiene and precautionary measures are of utmost importance to control the spread of COVID-19 and future infection; however, these changes in practice are projected to trigger a rise in the purchase, utilisation and hence, discharge of many disinfectants into the environment. While alcohol-based, hydrogen peroxide-based, and chlorine-based compounds have been used widely, quaternary ammonium compounds (QACs) based disinfectants are of significant concern due to their overuse during this pandemic. This review presents the classification of disinfectants and their mechanism of action, focusing on QACs. Most importantly, the occurrence, fate, toxicity and antimicrobial resistance due to QACs are covered in this paper. Here we collated evidence from multiple studies and found rising trends of concern, including an increase in the mass load of QACs at a wastewater treatment plant (WWTP) by 331% compared to before the COVID-19 pandemic, as well as an increases in the concentration of 62% in residential dust, resulting in high concentrations of QACs in human blood and breast milk and suggesting that these could be potential sources of persistent QACs in infants. In addition to increased toxicity to human and aquatic life, increased use of QACs and accelerated use of antibiotics and antimicrobials during the COVID-19 pandemic could multiply the threat to antimicrobial resistance.

Keywords: Antimicrobial resistance; Disinfectants; Quaternary ammonium compounds; Sediment; Toxicity.

Graphical abstract

Fig. 1

Variation in the concentrations of QACs during and before the COVID19 pandemic (Reproduced with permission [Zheng et al., 2020]).

Fig. 2

Network analysis of literature on QACs based on SCOPUS database.

Fig. 3

General structure of (a) QACs and (b) BACs, DDACs and ATMACs (Zheng et al., 2022).

Fig. 4

Mode of action of QACs on the SARS-CoV-2 envelope.

Fig. 5

Concentration of QACs in different types of wastewater and sludge samples across different countries. 1 (Pati and Arnold, 2020), 2 (Ferrer and Furlong, 2001), 3 (Zhu et al., 2018), 4 (Ruan et al., 2014), 5 (Li et al., 2014), 6 (Ding and Liao, 2001), 7 (Alexandre et al., 2016), 8 (Merino et al., 2003), 9 (Gerike et al., 1994), 10 (Sütterlin, 2008), 11 (Radke et al., 1999), 12 (Clara et al., 2007), 13 (Fernández et al., 1996). (CPC: Cetylpyridinium chloride; BZT: Benzethonium chloride).