Wastewater surveillance for 168 pharmaceuticals and metabolites in a WWTP: Occurrence, temporal variations and feasibility of metabolic biomarkers for intake estimation

Abstract

Wastewater-based epidemiology (WBE) is amply used for mining information about public health such as the estimation of consumption/intake of certain substances. Yet, proper biomarker selection is critical to obtain reliable data. This study measured a broad range of pharmaceuticals and metabolites in a wastewater treatment plant in Beijing, China, and evaluated their suitability as consumption estimation biomarkers. Wastewater sampling was conducted during a normal week and two holiday weeks to assess the impact of the holiday on population normalized daily mass loads (PNDLs). One hundred and forty-nine out of 168 pharmaceuticals were detected, with 94 analytes being quantified in all sampling events. Moreover, digestive drug cimetidine (<MDL∼672 ng L − 1) and anabolic steroid trenbolone (<MDL∼53 ng L − 1) were only detected during holiday weeks. PNDLs of some substances showed disparities between weekdays and weekends during the normal week. This study proposed a framework to diagnose whether a parent compound or its metabolite is suitable for intake/prevalence rate estimation. Our results support that not all the metabolites can be employed as biomarkers for back-calculation when the in-sewer stability of these compounds is unclear, such as metoprolol acid and O-desmethyl venlafaxine. Public healthcare data for drug utilization were applied to validate the prevalence of average substance use in this study. As a popular anti-epileptic ranging from hundreds to thousands of ng L − 1 in this study, the parent compound levetiracetam is more appropriate to be used in WBE under our framework, referring to public healthcare data. This WBE study illustrates the changes in pharmaceutical use and population lifestyle that stem from holidays and commutes. In addition, it can provide data support for the selection of more suitable biomarkers in WBE studies.