The wastewater-based epidemiology (WBE) approach has made it possible to analyse trends in drug use in Valencia over a decade; detect the appearance of new substances of abuse and identify changes in consumption patterns related to vacation periods or festive events.
For the work, the Food and Environmental Safety Research Group of the University of Valencia (SAMA-UV) , at CIDE, analysed the wastewater from three treatment plants in the city of Valencia and managed to detect a total of 16 psychoactive substances. -legal or illegal-, eight of which received continuous monitoring through chromatographic and mass spectrometry studies.
The results, recently published in the journal Water Research, show that cannabis, tobacco and cocaine were the most consumed drugs, with an average of 9.9 g/day for cannabis per 1,000 inhabitants, 1.7 g/day for day for cocaine and 1.5 g/day for nicotine ( see original data in article ). The study also shows an upward trend in the consumption of the three substances as of 2018. Opiates such as codeine (0.5 g/day), hallucinogens such as bufotenine (0.2 g/day), or stimulants such as ecstasy (MDMA 42 mg/day), amphetamines (36 mg/day), and methamphetamines (20 mg/day) stand out next. And, finally, heroin, ketamine or methadone, among others, proved to be the least used drugs in Valencia during the study period. Samples for analysis were obtained both in the form of pure substances and their metabolites.
"These data are similar to those found in other Spanish cities and are in accordance with the estimates made for the EU by the European Centre for Monitoring Drugs and Drug Addiction", says engineer Julián Campo, first author of this article. and researcher of the SAMA Group at CIDE. The 2021 European Report on Drugs identified cocaine as the second most widespread and seized stimulant in Europe, and the 2021 Report of the Spanish Observatory on Drugs and Addictions (OEDA), confirmed that cocaine is one of the drugs with the highest prevalence of consumption in the Spanish population between 15 and 64 year-olds and in the period 2019-2020, after alcohol and tobacco.
The results of the SAMA-UV group show that, in addition to cocaine, cannabis is among the most frequently detected illicit drugs in wastewater samples. These data agree with different studies carried out for similar periods in 26 EU countries.
Other data provided by the work are the increase in cocaine use in the city of Valencia and its surrounding municipalities throughout the decade, coinciding with the general trend observed throughout Europe; stabilised use of methamphetamine, decreased for amphetamine and increased for ecstasy. During weekends and local holidays, mainly Las Fallas, a higher frequency of consumption of psychotropic substances was observed compared to weekdays.
"Similar results have been recorded in different festivals, events or holiday periods in different cities around the world, which confirms the recreational use of some of these substances", says Yolanda Picó, professor of Nutrition and Bromatology at the University of Valencia and responsible for the SAMA-UV group.
The results of this work highlight the relevance of wastewater analysis as an excellent complement to classic epidemiological indicators - prevalence data, seizure statistics, etc. - when it comes to compose an objective, fast, cheap and anonymous overview of patterns of drug use in a specific location, as is the case of the city of Valencia", concludes Julián Campo.
