Suspect Screening of Wastewaters to Trace Anti-Covid-19 Drugs: Potential Adverse Effects on Aquatic Environment

The impact of the novel COVID-19 disease led to managing the sanitary emergency with new strategies, protocols and therapies. In the absence of specific treatments, a series of drugs were attempted, in particular during the first phase of the pandemic, with therapeutical protocols being continuously revised as new scientific evidence emerged. The management of this critical situation may also have led to indirect adverse effects on the environment, such as the release of a large amount of pharmaceuticals from WWTPs, leading to new risks for the aquatic environment, especially when drugs never used so widely until then, were administered massively. In this study, a suspect screening approach, performed on LC-HRMS instrument, was used to survey the presence of pharmaceuticals used for COVID-19 treatment in three WWTPs of Lombardy region, where the first European cluster of SARS-CoV-2 cases was detected. Out of the 63 suspect compounds (including some metabolites and transformation products), 6 compounds were fully confirmed and, together with other target analytes, were quantified. The monitoring campaign was surveyed in detail in one WWTP from April to December 2020 and the temporal trends of the quantified compounds were correlated with the trends of COVID-19 cases and deaths. The average emission loads of the three sewage plants were compared, evidencing that the WWTP that receives the discharges from the hospital that admitted COVID-19 patients had a different emission pattern, with higher loads of hydroxychloroquine, azithromycin and ciprofloxacin. From the survey of the receiving water bodies, eight compounds were found to be of high ecological concern including three antibiotics; for two of these (ciprofloxacin and azithromycin) a risk for Antibiotic Resistance occurrence was also assessed, underlying that for the risk assessment is important to consider all the biotic components of the aquatic ecosystem.