Illicit drug consumption estimated using wastewater analysis and compared by settlement size in New Zealand.
Estimation of consumption of illicit drugs by wastewater-based epidemiology provides estimates of community drug-use patterns. This study describes monitoring data of three illicit drugs in New Zealand using wastewater-based epidemiology. Wastewater samples were collected at monthly intervals for larger (population 50,000) cities or in smaller towns where more data was required by authorities. In other smaller towns, samples were collected every 2 months. Samples were extracted and analysed for parent compounds and metabolites of methamphetamine, MDMA, cocaine, heroin and fentanyl consumption using solid-phase extraction followed by liquid chromatography coupled with tandem-mass spectrometry (LC-MSMS) detection. Back calculations were performed to estimate the consumption of each drug in each catchment area. Methamphetamine was the drug measured with the highest estimated mean consumption rates (724 mg1000 people per day) in New Zealand. North Island small urban settlements had the highest estimated mean methamphetamine consumption rates (1259 mg1000 peopleday). Cocaine had the lowest estimated consumption rates (9.4 mg1000 peopleday). The highest estimated mean cocaine consumption rate was in North Island major urban settlements (24.4 mg1000 peopleday). Major urban settlements had the highest estimated mean MDMA (420 mg1000 peopleday) and cocaine consumption rates (18.8 mg1000 peopleday). South Island medium urban settlements had unexpectedly high estimated mean consumption rates of MDMA (533 mg1000 peopleday) and cocaine (17.0 mg1000 peopleday). The higher-than-expected estimated cocaine consumption was from one medium urban settlement that is also a popular tourist destination in the South Island. Heroin biomarkers were not detected at any locations, and fentanyl was detected around or below the limit of reporting. This research provides information for appropriate responses for improved social and health investment to support social services associated with illicit drug consumption.