The embodiment of wastewater data for the estimation of illicit drug consumption in Spain

Data obtained from wastewater analysis can provide rapid and complementary insights in illicit drug consumption at community level. Within Europe, Spain is an important country of transit of both cocaine and cannabis. The quantity of seized drugs and prevalence of their use rank Spain at the top of Europe. Hence, the implementation of a wastewater monitoring program at national level would help to get better understanding of spatial differences and trends in use of illicit drugs. In this study, a national wastewater campaign was performed for the first time to get more insight on the consumption of illicit drugs within Spain. The 13 Spanish cities monitored cover approximately 6 million inhabitants (12.8% of the Spanish population). Untreated wastewater samples were analyzed for urinary biomarkers of amphetamine, methamphetamine, MDMA, cocaine, and cannabis. In addition, weekend samples were monitored for 17 new psychoactive substances. Cannabis and cocaine are the most consumed drugs in Spain, but geographical variations showed, for instance, comparatively higher levels of methamphetamine in Barcelona and amphetamine in Bilbao, with about 1-fold higher consumption of these two substances in such metropolitan areas. For amphetamine, an enantiomeric profiling was performed in order to assure the results were due to consumption and not to illegal dumping of production residues. Furthermore, different correction factors for the excretion of cannabis were used to compare consumption estimations. All wastewater results were compared with previously reported data, national seizure data and general population survey data, were a reasonable agreement was found. Daily and yearly drug consumption were extrapolated to the entire Spanish population with due precautions because of the uncertainty associated. These data was further used to estimate the retail drug market, where for instance cocaine illicit consumption alone was calculated to contribute to 0.2–0.5% of the Spanish gross domestic product (ca. 3000–6000 million Euro/year).This study was supported by MINECO/AEI projects (CTM2016-81935-REDT, CTM2017-84763-C3-2-R, CTM2017-84763-C3-1-R, CTM2017-84763-C3-3-R, RTI2018-097158-B-C31 and CTM2017-90890-REDT), MICINN project (CEX2018-000794-S), Galician Council of Culture, Education and Universities (ED481D-2017/003, ED431C-2017/36 and ED481A-2020/258), cofounded by FEDER/ERDF. The UJI and CIDE (CSIC-UV-GV) authors acknowledge the financial support of Generalitat Valenciana (Excellence Research Group, Prometeo 2019/040 and Prometeo 2018/150, respectively). IDAEA-CSIC authors acknowledge the financial support of Generalitat de Catalunya (Exp. Num. SA-2018-780 and Consolidated Research Group 2017 SGR 01404) and the Spanish Ministry of Science and Innovation (Project CEX2018-000794-S). Alberto Celma acknowledges the Spanish Ministry of Economy and Competitiveness for his predoctoral Grant (BES-2016-076914). Elena Pitarch acknowledge the financial support of University Jaume I of Castellón, Spain (project UJI-B2018-55). Andreu Rico is supported by a postdoctoral grant provided by the Spanish Ministry of Science, Innovation and University (IJCI–2017–33465).Peer reviewe