Monitoring illicit stimulant drug use in Cyprus during the COVID-19 lockdown by UPLC-MS/MS

The occurrence and spread of the novel corona virus SARS-CoV-2 at the end of 2019, has led WHO to announce the outbreak of a pandemic. Restriction measures were taken from authorities globally, in order to impede its spread. In Cyprus, a strict lockdown period was implemented on the 24th March of 2020 and lasted until the end of April, with many restrictions still remaining. During the COVID-19 crisis, Wastewater Based Epidemiology (WBE) or otherwise environmental surveillance, has been proven to be a useful tool, enabling the investigation of various aspects of the pandemic. This work focuses on the impact of the lockdown restrictions implemented in Cyprus on the consumption of illicit, stimulant drugs, employing the WBE approach. Influent wastewater samples collected during the lockdown period were analysed to estimate amphetamine, methamphetamine, MDMA and cocaine consumption during this period. A similar sampling campaign was conducted one year earlier, during April of 2019, and the results were compared. The first campaign was conducted between 3-9 of April 2019 and the second, between 21-27 of April 2020, during the strict lockdown period. Daily composite 24-hour samples of influent wastewater were collected from two WWTPs of the country, LIM and AGN, serving one big city and a touristic area, respectively. All samples were spiked with a mixture of internal standards. After solid phase extraction, the samples were analysed for amphetamine, methamphetamine, MDMA and benzoylecgonine, using an ACQUITY TQD UPLC-MS/MS system (Waters Corp, USA), with a triple quadrupole mass spectrometer operating in positive ionization mode. The analysis and method validation procedures were based on the European Network of SCORE (Sewage analysis CORe group Europe), SCORE-Protocol of Action for the analysis of illicit drugs. For amphetamine, methamphetamine and MDMA, the concentrations of the parent compounds were used for the determination of the consumption of each drug. For cocaine, its main metabolite’s concetration, benzoylecgonine, was used. Back-calculations, requiring the polulation served from a specific WWTP, influent daily flows and a correction factor, CF, that accounts for excretion rates and the molar mass ratio of the parent/metabolite, were applied to convert the concentrations of each drug in the influent samples to consumption of the drug, in mg/day/1000 inhabitants. The CF values, adopted from the most recent literature, were 2.77, 2.44, 4.4 and 3.59 for amphetamine, methamphetamine, MDMA and cocaine, respectively. The analysis showed that amphetamine use was not affected from the imposed lockdown at both areas studied. At the LIM site, the average consumption of this drug during the 2019 campaign was 13.4 mg/day/1000 inhabitants, while during the lockdown sampling, the corresponding value was 9.5 mg/day/1000 inhabitants. The amphetamine consumption estimated at the AGN site was slightly lower than that at the LIM site, during both campaigns. Average methamphetamine consumption was found to decrease significantly at the LIM site during the lockdown, dropping from 136.5 during 2019, to 35.2 mg/day/1000 inhabitants during the lockdown. At the AGN site no significant change was observed, where the mean consumption during 2019 and lockdown were 51.0 and 46.0 mg/day/1000 inhabitants, respectively. The lockdown led to a remarkable decrease of the MDMA consumption at both sites: At the LIM site, where the average MDMA consumption was 60.1 mg/day/1000 inhabitants during the 2019 campaign, was found to be 5 times lower. The initial MDMA mean consumption of 17.3 mg/day/1000 inhabitants at the AGN site dropped below the method’s LOQ. The lockdown strongly impacted the use of cocaine, as well. At the LIM site, where the consumption during 2019 was 977.9 mg/day/1000 inhabitants, a more than 6 times decrease was observed. Similarly, at the AGN site, a significant decrease, from 433.0 to 118.0 mg/day/1000 inhabitants was observed.