Elsevier

Science of The Total Environment

Volume 432, 15 August 2012, Pages 432-439
Science of The Total Environment

Comparing illicit drug use in 19 European cities through sewage analysis

https://doi.org/10.1016/j.scitotenv.2012.06.069Get rights and content

Abstract

The analysis of sewage for urinary biomarkers of illicit drugs is a promising and complementary approach for estimating the use of these substances in the general population. For the first time, this approach was simultaneously applied in 19 European cities, making it possible to directly compare illicit drug loads in Europe over a 1-week period. An inter-laboratory comparison study was performed to evaluate the analytical performance of the participating laboratories. Raw 24-hour composite sewage samples were collected from 19 European cities during a single week in March 2011 and analyzed for the urinary biomarkers of cocaine, amphetamine, ecstasy, methamphetamine and cannabis using in-house optimized and validated analytical methods. The load of each substance used in each city was back-calculated from the measured concentrations. The data show distinct temporal and spatial patterns in drug use across Europe. Cocaine use was higher in Western and Central Europe and lower in Northern and Eastern Europe. The extrapolated total daily use of cocaine in Europe during the study period was equivalent to 356 kg/day. High per capita ecstasy loads were observed in Dutch cities, as well as in Antwerp and London. In general, cocaine and ecstasy loads were significantly elevated during the weekend compared to weekdays. Per-capita loads of methamphetamine were highest in Helsinki and Turku, Oslo and Budweis, while the per capita loads of cannabis were similar throughout Europe. This study shows that a standardized analysis for illicit drug urinary biomarkers in sewage can be applied to estimate and compare the use of these substances at local and international scales. This approach has the potential to deliver important information on drug markets (supply indicator).

Highlights

► First Europe-wide study of illicit drug use through sewage biomarker analysis. ► First application of a harmonized protocol to report and evaluate sampling, analysis and data handling. ► First inter-laboratory comparison of the analysis of illicit drugs. ► Comparable illicit drug use data for 19 European cities. ► Extrapolated total daily use of cocaine in Europe during the study period was equivalent to 356 kg/day.

Introduction

Illicit drug use and trafficking are international issues that have negative impacts across the social and economic spectrum, from the public health of individuals to the large-scale stability of national borders. Statistics show that around a third of European citizens have tried an illicit drug, while overdose claims the life of at least one citizen every hour (European Monitoring Centre for Drugs and Drug Addiction, 2010a). Ever-changing patterns in illicit drug production, demand and supply necessitate a program of frequent monitoring. Independent, objective and timely information on the type, scale and demographics of illicit drug use is essential in order to fully understand drug use and develop better methods and actions to respond to them. The European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) is responsible for collating such information in Europe and providing these data to policy makers so that they can design management strategies and appropriate laws. This information is also vital for measuring the success of existing management strategies and laws in view of a dynamic drug culture and emerging trends.

Illicit drug use is a socially stigmatized and often hidden activity, so traditional survey methods such as general population surveys and interviews can be inaccurate and prone to conjecture. The possibility of adding a new technique that overcomes these challenges to the existing repertoire of research methods is therefore an exciting prospect (European Monitoring Centre for Drugs and Drug Addiction, 2008). On average between 80 and 90% of the population is connected to the sewer network with much lower rates (40–65%) connected to primary sewage treatment in Eastern Europe. Sampling sewage at the inlet of a sewage treatment plant (STP) can therefore provide a diluted and pooled community urine sample that can deliver objective near real-time estimates of the total quantities of illicit drugs being used by the connected population (Zuccato et al., 2008, van Nuijs et al., 2011a, Daughton, 2011) (Fig. S1). The quantitative analysis of sewage for the estimation of illicit drug use is complementary to existing epidemiologically based approaches and can provide additional, evidence-based information. The potential of this approach to provide information regarding drug use at local level has previously been shown by Zuccato et al. (2008) where reproducible and characteristic profiles of illicit drug use were obtained in three cities, quickly revealing any short-time changes. Subsequently this approach has been used to estimate local (i.e. city or small town) and national use (van Nuijs et al., 2011b), monitor use trends with time (short-term and long-term; Harman et al., 2011), identify changing trends and new habits (Reid et al., 2011a, Castiglioni et al., 2011a) and identify the use of new substances (Zuccato et al., 2008, van Nuijs et al., 2011a, Daughton, 2011). The conceptual advantages of estimating illicit drug use based on sewage analysis are that it provides an aggregated estimate of all the people contributing to the sewage in a catchment over the sampling period, is non-intrusive and ethical approval from individuals is of no concern, it is objective and does not have the problems of surveys that may suffer from a limited number of subjects and self-reporting bias, and the results can be obtained almost in real-time, which means within days or weeks compared to surveys that may take years before publication.

The approach has been applied in Australia, Europe, and North America yielding promising results (van Nuijs et al., 2011a, van Nuijs et al., 2011b, Daughton, 2011, Reid et al., 2011a, Castiglioni et al., 2011a, Irvine et al., 2011). However, coordinated international studies have yet to be performed, and the direct comparison of these data is not trivial. Challenges arise from uncertainties associated with the sampling of sewage, behavior of the selected biomarkers in the sewer, reliability of inter-laboratory analytical measurements, different back-calculation methods, and different approaches to estimate the size of the population being tested.

The objective of the present study was for the first time to apply sewage analysis simultaneously in 19 European cities over a single week, following a harmonized protocol to report and evaluate sampling, analysis and data handling. In this way, it was possible to compare patterns of illicit drug use across Europe in a sound and reliable way. Sewage samples were analyzed for biomarkers of cocaine (COC), amphetamine (AMP), methamphetamine (METH), ecstasy (as 3,4-methylenedioxymethamphetamine, MDMA), and cannabis (CAN). To evaluate the analytical performance of each participating laboratory, an inter-laboratory comparison exercise was performed. The resulting estimates of illicit drug use were then further compared with official national statistics as compiled and reported by the EMCDDA (European Monitoring Centre for Drugs and Drug Addiction, 2010a).

The approach applied on a Europe-wide scale can reveal if trends of drug consumption can be promptly monitored at an international scale, using a tool which is complementary to more focused survey methods, and which has the potential to become an additional source of real-time epidemiological information.

Section snippets

Sewer system characterization (questionnaire)

To assess the potential of sewage drug testing under normal operating conditions, we purposely relied on existing sampling procedures at the individual STPs. It is worth noting that the catchments and sewer systems cannot be controlled by the investigators and that both sewage flows and biomarker concentrations vary during a day; not only at the time-scales of hours but also minutes (Ort et al., 2010a). This has been neglected in most previous studies and relevant information, to evaluate the

System characterization and sampling

The questionnaire had a very good response and all but one of the operators were very cooperative. The results show that 10 of 20 STPs sample volume proportionally with average sampling intervals of around 15 min, which resulted in generally acceptable uncertainties with only two potentially critical sites. Similarly, flow data quality also seems satisfactory since 10 of the 20 STPs reported that they calibrate their flow meters in periods of between 1 month and 6 years. Systematic flow

System characterization and sampling

Our results show that a thorough analysis of sewage systems, which requires close collaboration with local STP operators, and sampling design are necessary to obtain good, reliable data. The results of this study revealed only a few cases where the level of confidence associated with the STPs' own sampling equipment and protocol was unacceptable. This supports the recent findings of Mathieu et al. (2011) who suggest that the STPs' own sampling equipment is usually suitable for this type of

Conclusions

For the first time sewage analysis using a uniform protocol has been simultaneously applied in 19 European cities to estimate and compare the use of illicit drugs across Europe. The quantitative, non-intrusive, objective and rapid analysis of the illicit drug use of 15 million individuals was determined over a 1-week period, providing the most current data on illicit drug use in Europe with the results generally being in good agreement with officially reported prevalence data. In addition the

Acknowledgments

The following scientists contributed to the study: Marijan Ahel, Asmail Asgadaouan, Damià Barceló, David R Baker, Leon Barron, Jean-Daniel Berset, Cristina Blasco, Jenny-Maria Brozinski, Ganna Fedorova, Jerker Fick, Iria González-Mariño, Leif Kronberg, Katherine Langford, Ana Masia, Nicola Mastroianni, Thomas Nefau, Brett Paul, Isaac Rodríguez, Andreas Scheidegger, Ivan Senta, Mauro Tettamanti, Mats Tysklind and Ettore Zuccato. We thank Paul Griffith, Jane Mounteney and Ana Gallegos from EMCDDA

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