title: Critical review on the stability of illicit drugs in sewers and wastewater samples.
abstract: Wastewater-based epidemiology (WBE) applies advanced analytical methods to quantify drug residues in wastewater with the aim to estimate illicit drug use at the population level. Transformation processes during transport in sewers (chemical and biological reactors) and storage of wastewater samples before analysis are expected to change concentrations of different drugs to varying degrees. Ignoring transformation for drugs with low to medium stability will lead to an unknown degree of systematic under- or overestimation of drug use, which should be avoided. This review aims to summarize the current knowledge related to the stability of commonly investigated drugs and, furthermore, suggest a more effective approach to future experiments. From over 100 WBE studies, around 50 mentioned the importance of stability and 24 included tests in wastewater. Most focused on in-sample stability (i.e., sample preparation, preservation and storage) and some extrapolated to in-sewer stability (i.e., during transport in real sewers). While consistent results were reported for rather stable compounds (e.g., MDMA and methamphetamine), a varying range of stability under different or similar conditions was observed for other compounds (e.g., cocaine, amphetamine and morphine). Wastewater composition can vary considerably over time, and different conditions prevail in different sewer systems. In summary, this indicates that more systematic studies are needed to: i) cover the range of possible conditions in sewers and ii) compare results more objectively. To facilitate the latter, we propose a set of parameters that should be reported for in-sewer stability experiments. Finally, a best practice of sample collection, preservation, and preparation before analysis is suggested in order to minimize transformation during these steps.
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH 8600 Dübendorf, Switzerland.
authors.forename: Ann-Kathrin
authors.initials: AK
authors.lastname: McCall
authors.affiliation: Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat, E-12071 Castellón, Spain.
authors.forename: Richard
authors.initials: R
authors.lastname: Bade
authors.affiliation: Toxicological Centre, Department of Pharmaceutical Sciences, University of Antwerp (UA), Universiteitsplein 1, 2610 Antwerp, Belgium.
authors.forename: Juliet
authors.initials: J
authors.lastname: Kinyua
authors.affiliation: The University of Queensland, The National Research Centre for Environmental Toxicology (Entox), 39 Kessels Rd., Coopers Plains, Brisbane, QLD 4108, Australia.
authors.forename: Foon Yin
authors.initials: FY
authors.lastname: Lai
authors.affiliation: The University of Queensland, The National Research Centre for Environmental Toxicology (Entox), 39 Kessels Rd., Coopers Plains, Brisbane, QLD 4108, Australia; Queensland University of Technology, International Laboratory for Air Quality & Health, 2 George Street, Brisbane, QLD 4001, Australia.
authors.forename: Phong K
authors.initials: PK
authors.lastname: Thai
authors.affiliation: Toxicological Centre, Department of Pharmaceutical Sciences, University of Antwerp (UA), Universiteitsplein 1, 2610 Antwerp, Belgium.
authors.forename: Adrian
authors.initials: A
authors.lastname: Covaci
authors.affiliation: Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat, E-12071 Castellón, Spain.
authors.forename: Lubertus
authors.initials: L
authors.lastname: Bijlsma
authors.affiliation: Toxicological Centre, Department of Pharmaceutical Sciences, University of Antwerp (UA), Universiteitsplein 1, 2610 Antwerp, Belgium.
authors.forename: Alexander L N
authors.initials: ALN
authors.lastname: van Nuijs
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH 8600 Dübendorf, Switzerland. Electronic address: Christoph.Ort@eawag.ch.
authors.forename: Christoph
authors.initials: C
authors.lastname: Ort
mesh_terms: D004784:Environmental Monitoring / Q000379:methods*; D013287:Illicit Drugs / Q000032:analysis*; D012722:Sewage / Q000032:analysis*; D062065:Wastewater / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D013287:Illicit Drugs; D012722:Sewage; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Biodegradation; Psychoactive substances; Sample preservation; Sewage epidemiology; Transformation