The photolytic behavior of COVID-19 antivirals ribavirin in natural waters and the increased environmental risk

Increasing drug residues in aquatic environments have been caused by the abuse of antivirals since the global spread of the COVID-19 epidemic, whereas research on the photolytic mechanism, pathways and toxicity of these drugs is limited. The concentration of COVID-19 antivirals ribavirin in rivers has been reported to increase after the epidemic. Its photolytic behavior and environmental risk in actual waters such as wastewater treatment plant (WWTP) effluent, river water and lake water were first investigated in this study. Direct photolysis of ribavirin in these media was limited, but indirect photolysis was promoted in WWTP effluent and lake water by dissolved organic matter and NO3- . Identification of photolytic intermediates suggested that ribavirin was photolyzed mainly via C-N bond cleavage, splitting of the furan ring and oxidation of the hydroxyl group. Notably, the acute toxicity was increased after ribavirin photolysis owing to the higher toxicity of most of the products. Additionally, the overall toxicity was greater when ARB photolysis in WWTP effluent and lake water. These findings emphasize the necessity to concern about the toxicity of ribavirin transformation in natural waters, as well as to limit its usage and discharge.

Automated summary

The abuse of antivirals during the global spread of COVID-19 has led to an increase in drug residues in aquatic environments. However, research on the photolytic mechanism, pathways, and toxicity of these drugs is limited. This study investigated the photolytic behavior and environmental risk of the COVID-19 antiviral ribavirin in wastewater treatment plant effluent, river water, and lake water. The results showed that ribavirin underwent indirect photolysis in these media, mainly through C-N bond cleavage, furan ring splitting, and hydroxyl group oxidation. The photolysis of ribavirin resulted in increased acute toxicity, highlighting the need to consider the toxicity of ribavirin transformation in natural waters and to restrict its usage and discharge.