Suspect Screening of Pharmaceuticals and Their Transformation Products (TPs) in Wastewater during COVID-19 Infection Peak: Identification of New TPs and Elevated Risks

Pharmaceuticals and their transformation products (TPs)
in wastewater
are emerging contaminants that pose risks to ecosystems and human
health. Here, a typical period marked by the easing of the “zero-COVID”
policy in December 2022, resulting in unprecedented infections in
China, was chosen to illustrate the environmental impact of pharmaceutical
usage during the COVID-19 pandemic. A suspect screening workflow was
developed to identify pharmaceuticals and transformation products
(TPs) in wastewater influent and effluent from a wastewater treatment
plant (WWTP) during the peak and postpeak periods of COVID-19, integrating
medication recommendations and TPs’ prediction. A total of
114 pharmaceuticals and TPs were identified (13 TPs were detected
for the first time in WWTP) by using liquid chromatography coupled
with high-resolution mass spectrometry (LC-HRMS). Wastewater-based
epidemiology analysis showed that the most predominant pharmaceuticals
were nonsteroidal anti-inflammatory drugs. Interestingly, the consumption
of propafenone increased after the infection peak, possibly linked
to long COVID-19 symptoms. Risks were further evaluated based on concentration,
detection frequency, and PMT (persistence, mobility, and toxicity)
properties, revealing that TPs of aminopyrine, acetaminophen, etc.
showed even greater ToxPi scores than their parent compounds. This
study highlights the elevated risks posed by pharmaceutical discharge
during epidemics and the necessity for TPs’ monitoring.