Drugs of abuse in wastewater and suspended particulate matter — Further developments in sewage epidemiology

This manuscript reports, for the first time, a monitoring study analysing wastewater and associated suspended particulate matter (SPM) to determine the concentration of drugs of abuse and metabolites in wastewater influent. The monitoring of SPM is crucial for target analytes because, depending on their physico-chemical properties, they may partition to particulates; thus, analysis of wastewater only will result in under-reporting of the concentration of target analytes in the sample. A daily one week monitoring study was carried out at a WWTP serving one of the largest cities in the Czech Republic; representing the first comprehensive application of the sewage epidemiology approach in the Czech Republic. In total, 60 analytes were targeted in the monitoring programme including stimulants, opioid and morphine derivatives, benzodiazepines, antidepressants, dissociative anaesthetics, drug precursors and their metabolites. Analysis of SPM determined that significant proportions of some compounds were present on the solids. For example, 21.0–49.8% of the total concentration of EDDP (2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine) in the sample was determined on SPM and 11.2–19.6% of methadone. The highest proportion on SPM was determined for fluoxetine in the range 68.1–79.6%, norfluoxetine 46.6–61.9% and amitriptyline 21.8–51.2%. In contrast, some compounds presented very little partitioning to SPM. Less than 5% was determined partitioned to SPM over the week period for analytes including cocaine, benzoylecgonine, cocaethylene, amphetamine, methamphetamine, MDMA (3,4-methylenedioxymethamphetamine), codeine, dihydrocodeine, tramadol, nortramadol, oxazepam and ephedrine. Determined concentrations in wastewater influent were subsequently utilised in the sewage epidemiology approach to estimate drug consumption, in the community from which the wastewater was derived. This back-calculation was updated for the first time to include the concentration of analytes present on SPM. The consumption of methamphetamine and MDMA was determined to be especially high in the studied community in relation to other European countries, while cocaine and methadone consumption was relatively low. This manuscript shows that in order to apply the sewage epidemiology approach, SPM analysis is required for some compounds; whereas for others the partitioning is small and one may regard this as negligible.