Disinfectant-induced hormesis: An unknown environmental threat of the application of disinfectants to prevent SARS-CoV-2 infection during the COVID-19 pandemic?

Abstract

Massive additional quantities of disinfectants have been applied during the COVID-19 pandemic as infection preventive and control measures. While the application of disinfectants plays a key role in preventing the spread of SARS-CoV-2 infection, the effects of disinfectants applied during the ongoing pandemic on non-target organisms remain unknown. Here we collated evidence from multiple studies showing that chemicals used for major disinfectant products can induce hormesis in various organisms, such as plants, animal cells, and microorganisms, when applied singly or in mixtures, suggesting potential ecological risks at sub-threshold doses that are normally considered safe. Among other effects, sub-threshold doses of disinfectant chemicals can enhance the proliferation and pathogenicity of pathogenic microbes, enhancing the development and spread of drug resistance. We opine that hormesis should be considered when evaluating the effects and risks of such disinfectants, especially since the linear-no-threshold (LNT) and threshold dose-response models cannot identify or predict their effects.

Keywords: Coronavirus; Disinfectants application; Dose-response relationship; Environmental pollution; Hormesis; Pandemic.

Graphical abstract

Fig. 1

A: A schematic representation of hormetic dose-response relationship. Similar hormetic-like responses were found in various organisms exposed to different types of disinfectant-containing chemicals. B: An example of hormetic dose-response relationship. Cell viability assay was evaluated with the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium reduction assay in a mouse embryonic fibroblast cell line. The figure has been created based on data reported by Kar et al. (2021), and asterisk above a mean indicates significant difference from the control based on the original authors' statistical analyses. The ethanol concentrations were transformed for presentation purposes. The original concentrations were 0, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 5, and 10 v/v % for 48 h. Data were extracted from the relevant figure of the published article using Adobe Photoshop CS4 Extended v.11 (Adobe Systems Incorporated, CA, USA).