Impact of in-Sewer Degradation of Pharmaceutical and Personal Care Products (PPCPs) Population Markers on a Population Model

Abstract

A key uncertainty of wastewater-based epidemiology is the size of the population which contributed to a given wastewater sample. We previously developed and validated a Bayesian inference model to estimate population size based on 14 population markers which: (1) are easily measured and (2) have mass loads which correlate with population size. However, the potential uncertainty of the model prediction due to in-sewer degradation of these markers was not evaluated. In this study, we addressed this gap by testing their stability under sewer conditions and assessed whether degradation impacts the model estimates. Five markers, which formed the core of our model, were stable in the sewers while the others were not. Our evaluation showed that the presence of unstable population markers in the model did not decrease the precision of the population estimates providing that stable markers such as acesulfame remained in the model. However, to achieve the minimum uncertainty in population estimates, we propose that the core markers to be included in population models for other sites should meet two additional criteria: (3) negligible degradation in wastewater to ensure the stability of chemicals during collection; and (4) < 10% in-sewer degradation could occur during the mean residence time of the sewer network.

Potential impact of the sewer system on the applicability of alcohol and tobacco biomarkers in wastewater‐based epidemiology

“…This study employed laboratory‐scale reactors to simulate typical sewer conditions, which have been reported in our previous studies . Three different sewer reactors were employed, which included a rising main (RM) sewer reactor, a gravity sewer (GS) reactor, and a control (CR) sewer reactor without biofilms.…”

“…Senta et al also recognised HCot's potential as a population marker. Considering the potential degradation of Cot and HCot in the sewer system, we applied the criteria recommended by O'Brien et al to assess whether they are ‘best practice’ population markers. Cot satisfies this set of 4 criteria to be used for population estimation purpose while HCot does not meet the average 10% loss threshold.…”

“…This study employed laboratory-scale reactors to simulate typical sewer conditions, which have been reported in our previous studies. 13,17 Three different sewer reactors were employed, which included a rising main (RM) sewer reactor, a gravity sewer (GS) reactor, and a control (CR) sewer reactor without biofilms. Detailed description of the reactors can be found in Jiang et al 19 Sewer biofilms in RM and GS reactors have been cultivated for over 8 years using real wastewater before the experiments.…”

“…Biofilms are capable of transforming/degrading various chemical compounds more strongly than the suspended microbes in wastewater alone . The capacity of sewer biofilms to enhance degradation of certain chemicals including cocaine, 6‐acetylmorphine (heroin metabolite), creatinine, and paracetamol has been reported …”

“…13,14 The capacity of sewer biofilms to enhance degradation of certain chemicals including cocaine, 6-acetylmorphine (heroin metabolite), creatinine, and paracetamol has been reported. 13,14,17,18 Therefore, in this study, we aimed to investigate the stability of EtG, EtS, Cot, and HCot under different sewer conditions using laboratory-scale sewer reactors and to assess the impact of in-sewer degradation of these biomarkers to their applicability in WBE studies including for consumption estimation and population estimation purposes.…”