1. Analysis: results from a European multi-city study
Wastewater analysis is a rapidly developing scientific discipline with the potential for monitoring real-time data on geographical and temporal trends in illicit drug use. Originally used in the 1990s to monitor the environmental impact of liquid household waste, the method has since been used to estimate illicit drug consumption in different cities (Daughton, 2001; Zuccato et al., 2008; van Nuijs et al., 2011). It involves sampling a source of wastewater, such as a sewage influent to a wastewater treatment plant. This allows scientists to estimate the quantity of drugs consumed by a community by measuring the levels of illicit drugs and their metabolites excreted in urine (Zuccato et al., 2008).
Wastewater testing in European cities
In 2010 a Europe-wide network (Sewage analysis CORe group — Europe (SCORE)) was established with the aim of standardising the approaches used for wastewater analysis and coordinating international studies through the establishment of a common protocol of action (1). The first activity of the SCORE group was a Europe-wide investigation, performed in 2011 in 19 European cities, which allowed the first ever wastewater study of regional differences in illicit drug use in Europe (Thomas et al., 2012). That study also included the first intercalibration exercise for the evaluation of the quality of the analytical data and allowed a comprehensive characterisation of the major uncertainties of the approach (Castiglioni et al., 2014). Following the success of this initial study, comparable studies were undertaken over the following four years, covering 53 cities and 20 countries in Europe in 2016. A standard protocol and a common quality control exercise were used in all locations, which made it possible to directly compare illicit drug loads in Europe over a one-week period during six consecutive years. For the 2016 wastewater monitoring campaign, raw 24-hour composite samples were collected during a single week in March. These samples were analysed for the urinary biomarkers (i.e. measurable characteristics) of the parent drug (i.e. primary substance) for amphetamine, methamphetamine and MDMA. In addition, the samples were analysed for the main urinary metabolites (i.e. substances produced when the body breaks drugs down) of cocaine and cannabis, which are benzoylecgonine (BE) and THC-COOH (11-nor-9-carboxy-delta9-tetrahydrocannabinol).
This report is focused on illicit stimulants. No results for cannabis are reported, as the identification of THC-COOH loads in wastewater poses some sampling and analytical challenges.
Patterns of illicit drug use: geographical and temporal variation
2016 key findings
The project revealed a picture of distinct geographical and temporal patterns of drug use across European cities (see Interactive: explore the data from the study).
The BE loads observed in wastewater indicate that cocaine use is highest in western and southern European cities, in particular in cities in Belgium, Spain and the United Kingdom. Wastewater analysis indicates that cocaine use is very low to negligible in the majority of eastern European cities.
The loads of amphetamine detected in wastewater varied considerably across study locations, with the highest levels reported in cities in the north of Europe. Amphetamine was found at much lower levels in cities in the south of Europe.
In contrast, methamphetamine use, generally low and historically concentrated in the Czech Republic and Slovakia, now appears to be present also in the east of Germany and northern Europe, particularly in cities in Finland. The observed methamphetamine loads in the other locations were very low to negligible.
The highest mass loads of MDMA were found in the wastewater in cities in Belgium, the Netherlands and Norway.
Ten countries participating in the 2016 monitoring campaign included two or more study locations (Belgium, Cyprus, Germany, Spain, Finland, France, the Netherlands, Portugal, Slovakia and UK). The study highlighted differences between these cities within the same country, which may be explained in part by the different social and demographic characteristics of the cities (universities, nightlife areas and age distribution of the population). In the large majority of countries with multiple study locations, cocaine and MDMA loads were higher in large cities compared to smaller locations. No such differences could be detected for amphetamine and methamphetamine.
In addition to geographical patterns, wastewater analysis can detect fluctuations in weekly patterns of illicit drug use. More than three-quarters of cities show higher loads of BE and MDMA in wastewater during the weekend (Friday to Monday) than during weekdays. In contrast, amphetamine use was found to be distributed more evenly over the whole week.
Five-year trend data
Seventeen cities have participated in five or six of the annual wastewater monitoring campaigns since 2011, which allows for time trend analysis of drug consumption based on wastewater testing.
A relatively stable picture of cocaine use can be observed over five years. The general patterns detected were similar in the six consecutive monitoring campaigns, with the highest and lowest BE loads found in the same cities and regions. Most cities show either a decreasing or a stable trend between 2011 and 2015, but there are signs that this pattern may have changed with 22 out of 33 cities that have data for 2015 and 2016 reporting an increase. In a few cases, including London and Zagreb, a longer-term increase in BE loads found in wastewater over the 2011–16 period has been notified.
Over the six years of monitoring the highest MDMA loads were consistently found in the wastewater of cities in Belgium and the Netherlands. Looking at longer term trends, in most cities with at least five data points wastewater MDMA loads were higher in 2016 than in 2011, with sharp increases observed in some cities, including Antwerp and Oslo.
Overall, the data related to amphetamine and methamphetamine from the six monitoring campaigns showed no major changes in the general patterns of use observed.
Comparison with findings from other monitoring tools
Because different types of information are provided by wastewater analysis (collective consumption of substances within a community) and by established monitoring tools, such as population surveys (prevalence in the last month or year), a direct comparison of the data is difficult. However, the patterns and trends being detected by wastewater analysis are largely, but not completely, in line with the analyses coming from other monitoring tools.
For example, both seizure and wastewater data present a picture of a geographically divergent stimulant market in Europe, where cocaine is more prevalent in the south and west, while amphetamines are more common in central and northern countries (EMCDDA, 2017). While the general pattern detected in wastewater is in line with established monitoring tools, there are some exceptions: the amphetamine loads in wastewater in Paris have been below the level of quantification over the consecutive annual monitoring campaigns, contrary to indications from other monitoring tools.
Data from established indicators show that methamphetamine use has historically been restricted to the Czech Republic, and more recently also Slovakia, although recent years have seen increased use in other countries (EMCDDA, 2016a). These findings have been confirmed by recent wastewater-based epidemiology, with the highest methamphetamine loads found in Czech, Slovak, German and Finnish cities.
Established indicators show that, until recently, MDMA prevalence was declining in many countries from peak levels in the early to mid 2000s. Data from wastewater and from established indicators show that this appears to be changing, with the large majority of cities reporting higher wastewater MDMA loads in 2016 than in 2011.
Similarly, studies based on self-reported drug use and those using wastewater data both point towards the same weekly variations in use, with stimulants such as amphetamine and cocaine being primarily used at weekend music events and in celebratory contexts (Tossmann et al., 2001).
A limited but steadily increasing number of studies have been published comparing drug use estimates obtained through wastewater analysis and estimates provided by epidemiological surveys (EMCDDA, 2016b; van Wel et al., 2015). While in 2012 only one reported study tried to evaluate sewage analysis alongside traditional epidemiological techniques (Reid et al., 2012), this number has now increased to around 20 published research articles that are focused on comparing information provided by wastewater analysis and information provided by other indicators.
A first study, performed in Oslo, Norway, and published in 2012, compared the results from three different datasets (a general population survey, a roadside survey and wastewater analysis) (Reid et al., 2012).
Other, more recent studies compare and correlate wastewater-based consumption estimates of illicit drugs with other data sources, including self-reported data (Been et al., 2015; Castiglioni et al., 2016; van Wel et al., 2016a), consumption offences (Been et al., 2016a), illicit drug seizures (Baz-Lomba et al., 2016; Kankaanpää et al., 2014, 2016), syringe distribution estimates (Been et al., 2015) toxicological data (Kankaanpää et al., 2014, 2016) and the number of drug users in treatment (Krizman et al., 2016).
The majority of comparative studies have been carried out within Europe, including in Belgium (van Wel et al., 2016a), Croatia (Krizman et al., 2016), Germany (Been et al., 2016a), Finland (Kankaanpää et al., 2014, 2016), Italy (Castiglioni et al., 2016), Switzerland (Been et al., 2015; Been et al., 2016b) and across European countries (Baz-Lomba et al., 2016). Outside Europe, in recent years studies have been published comparing wastewater-based estimates with other data sources in China (Du et al., 2015) and Australia (Tscharke et al., 2015).
These examples confirm the promising future of wastewater-based epidemiology as a complementary approach to obtain a more accurate and balanced picture of substance use within different communities. Wastewater analysis can predict results from population surveys and can be used as a ‘first alert’ tool in the identification of new trends in drug consumption.
Limitations of this method
Wastewater analysis offers an interesting complementary data source for monitoring the quantities of illicit drugs used at the population level, but it cannot provide information on prevalence and frequency of use, main classes of users and purity of the drugs. Additional challenges arise from uncertainties associated with the behaviour of the selected biomarkers in the sewer, different back-calculation methods and different approaches to estimate the size of the population being tested (Castiglioni et al., 2013, 2016; Lai et al., 2014; EMCDDA, 2016b). The caveats in selecting the analytical targets for heroin, for example, make monitoring this drug in wastewater more complicated compared to other substances (Been et al., 2015). Also, the purity of street products fluctuates unpredictably over time and in different locations. Furthermore, translating the total consumed amounts into the corresponding number of average doses is complicated, as drugs can be taken by different routes and in amounts that vary widely, and purity levels fluctuate (Zuccato et al., 2008).
The necessary sampling intervals for wastewater samples to reduce random biases and produce reliable annual consumption estimates is an issue that will be further explored in the 2017 SCORE annual monitoring campaign (http://score-cost.eu/monitoring2017/).
New developments and the future
Wastewater-based epidemiology has established itself as an important tool for monitoring illicit drug use and future directions for wastewater research have been explored (EMCDDA, 2016b).
First, wastewater analysis has been proposed as a tool to address some of the challenges related to the dynamic new psychoactive substances (NPS) market. This includes the large number of individual NPS, the relatively low prevalence of use and the fact that many of the users are actually unaware of exactly which substances they are using. A new technique has been established to identify NPS that involves the collection and analysis of pooled urine from stand-alone portable urinals from nightclubs, city centres and music festivals, thereby providing timely data on exactly which NPS are currently in use at a particular location (Archer et al., 2013a, 2013b, 2015; Reid et al., 2014; Kinyua, et al., 2016).
Second, in addition to estimating illicit drug use, wastewater-based epidemiology has been successfully applied in recent years to providing detailed information on the use and misuse of alcohol (Boogaerts et al., 2016; Rodríguez-Álvarez et al., 2015), tobacco (Senta et al., 2015; van Wel et al., 2016b) and medicines in a specific population (Been et al., 2015; Salvatore et al., 2016; Baz-Lomba, 2016). Furthermore, wastewater analysis can potentially provide information on health and illness indicators within a community (Yang et al., 2015; Kasprzyk-Hordern et al., 2014).
Third, the potential for wastewater-based epidemiology to be used as an outcome measurement tool, in particular in the evaluation of the effectiveness of interventions that target drug supply (e.g. law enforcement) or drug demand (e.g. public health campaigns) has not yet been fully explored. Close collaboration between the different stakeholders involved, including epidemiologists, wastewater experts and legal authorities, is highly recommended in order to start examining these potential wastewater-based epidemiology applications (EMCDDA, 2016b).
Fourth, by back-calculating the daily sewer loads of target residues, wastewater analysis can provide total consumption estimates, and specific efforts are now being directed towards finding the best procedures for estimating annual averages. In 2016 the EMCDDA presented for the first time illicit drug retail market size estimates in terms of quantity and value for the main substances used (EMCDDA and Europol, 2016c). It is envisaged that findings from wastewater analysis can help to further develop work in this area.
Finally, new methods such as enantiomeric profiling have been developed to determine if mass loads of drugs in wastewater originated from consumption or from the disposal of unused drugs or production waste. It is now important to assess the possible utility of wastewater analysis to report on drug supply dynamics, including synthetic drug production.
Wastewater analysis has demonstrated its potential as a useful complement to established monitoring tools in the drugs area. It has some clear advantages over other approaches as it is not subject to response and non-response bias and can better identify the true spectrum of drugs being consumed, as users are often unaware of the actual mix of substances they take. This tool also has the potential to provide timely information in short timeframes on geographical and temporal trends. In order to check the quality and accuracy of data, further comparisons between wastewater analysis and data obtained through other indicators are needed.
As a method, wastewater analysis has moved from being an experimental technique to being a new method in the epidemiological toolkit. Its rapid ability to detect new trends can help target public health programmes and policy initiatives at specific groups of people and the different drugs they are using.
(1) The protocol can be found on the EMCDDA website: www.emcdda.europa.eu/wastewater-analysis
- Archer, J. R. H., Dargan, P. I., Hudson, S. and Wood, D. M. (2013a), ‘Analysis of anonymous pooled urinals in central London confirms the significant use of novel psychoactive substances’, QJM,106(2), pp. 147–152.
- Archer, J. R. H., Hudson, S., Wood, D. M. and Dragan, P. I. (2013b), ‘Analysis of urine from pooled urinals: a novel method for the detection of novel psychoactive substances’, Current Drug Abuse Reviews, online publication, 5 December.
- Archer, J. R. H., Hudson, S., Jackson, O. (2015), ‘Analysis of anonymized pooled urine in nine UK cities: variation in classical recreational drug, novel psychoactive substance and anabolic steroid use’, QJM, 108 (12), pp. 929–933.
- Baz-Lomba, J. A., Salvatore, S., Gracia-Lor, E., et al. (2016), ‘Comparison of pharmaceutical, illicit drug, alcohol, nicotine and caffeine levels in wastewater with sale, seizure and consumption data for 8 European cities’, BMC Public Health, 16, 1, 1035.
- Been, F., Benaglia, L., Lucia, S., et al. (2015), ‘Data triangulation in the context of opioids monitoring via wastewater analyses’, Drug and Alcohol Dependence, 151, pp. 203–210.
- Been, F., Bijlsma, L., Benaglia, L., et al. (2016a), ‘Assessing geographical differences in illicit drug consumption: A comparison of results from epidemiological and wastewater data in Germany and Switzerland’, Drug and Alcohol Dependence 161, pp. 189–199.
- Been, F., Schneider, C., Zobel, F., Delémont, O., Esseiva, P. (2016b), ‘Integrating environmental and self-report data to refine cannabis prevalence estimates in a major urban area of Switzerland’, International Journal of Drug Policy, 36, pp. 33–40.
- Boogaerts, T., Covaci, A., Kinyua, J., et al. (2016), ‘Spatial and temporal trends in alcohol consumption in Belgian cities: A wastewater-based approach’, Drug and Alcohol Dependence 160, pp. 170–176.
- Bramness, J.G., Reid M.J., Solvik, K.F. and Vindenes, V. (2014), ‘Recent trends in the availability and use of amphetamine and methamphetamine in Norway’, Forensic Science International, 246, pp. 92–97.
- Castiglioni, S., Thomas, K. V., Kasprzyk-Hordern, B., Vandam, L. and Griffiths, P. (2013a), ‘Testing wastewater to detect illicit drugs: state of the art, potential and research needs’, Science of the Total Environment, online publication, 25 October.
- Castiglioni, S., Bijlsma, L., Covaci A., et al. (2013b), ‘Evaluation of uncertainties associated with the determination of community drug use through the measurement of sewage drug biomarkers’, Environmental Science and Technology, 47(3), pp. 1452–1460.
- Daughton, C.G. (2001), ‘Emerging pollutants, and communicating the science of environmental chemistry and mass spectrometry: pharmaceuticals in the environment’, American Society for Mass Spectrometry, 12, pp. 1067–1076.
- Du, P. (2015), ‘Methamphetamine and ketamine use in major Chinese cities, a nationwide reconnaissance through sewage-based epidemiology’, Water Research, Volume 84, pp. 76–84.EMCDDA (2016a), European drug report: Trends and developments, Publications Office of the European Union, Luxembourg.
- EMCDDA (2016a), European Drug Report: Trends and Developments, Publications Office of the European Union, Luxembourg.
- EMCDDA (2016b), Assessing illicit drugs in wastewater: Advances in wastewater-based drug epidemiology, Publications Office of the European Union, Luxembourg.
- EMCDDA and Europol (2016c), EU Drug Markets Report, EMCDDA–Europol.
- EMCDDA (2017), European Drug Report: Trends and Developments, Publications Office of the European Union, Luxembourg.
- Kankaanpää, A., Ariniemi K., Heinonen M., et al. (2014), ‘Use of illicit stimulant drugs in Finland: A wastewater study in ten major cities’, Science of the Total Environment, 487, pp. 696–702.
- Kankaanpää, A., Ariniemi, K., Heinonen, M., Kuoppasalmi, K., Gunnar T. (2016), ‘Current trends in Finnish drug abuse: Wastewater based epidemiology combined with other national indicators’, Science of the Total Environment, 568, pp. 864–874.
- Kasprzyk-Hordern, B., Bijlsma, L., Castiglioni, S., et al. (2014), ‘Wastewater-based epidemiology for public health monitoring’, Water and Sewerage Journal, 4, pp. 25-26.
- Kinyua, J., Negreira, N., Miserez, B., et al. (2016), ‘Qualitative screening of new psychoactive substances in pooled urine samples from Belgium and United Kingdom’, Science of the Total Environment, 573, pp. 1527–1535.
- Krizman, I., Senta, I., Ahel, M., Terzic, S. (2016), ‘Wastewater-based assessment of regional and temporal consumption patterns of illicit drugs and therapeutic opioids in Croatia’, Science of the Total Environment, 566-567, pp .454–462.
- Lai, F. Y., Anuj, S., Bruno, R., et al. (2014), ‘Systematic and day-to-day effects of chemical-derived population estimates on wastewater-based drug epidemiology’, Environmental Science and Technology 49, pp. 999–1008.
- Reid, M. J., Langford, K. H., Grung, M., et al. (2012), ‘Estimation of cocaine consumption in the community: a critical comparison of the results from three complimentary techniques’, BMJ Open, 2(6).
- Reid, M. J., Baz-Lomba, J. A., Ryu, Y. and Thomas, K. V. (2014), ‘Using biomarkers in wastewater to monitor community drug use: a conceptual approach for dealing with new psychoactive substances’, Science of the Total Environment, in press.
- Rodríguez-Álvarez, T., Racamonde, I., González-Mariño, I., et al. (2015), ‘Alcohol and cocaine co-consumption in two European cities assessed by wastewater analysis’, Science of the Total Environment 536, pp. 91–98.
- Senta, I., Gracia-Lor, M., Borsotti, A., et al. (2015), ‘Wastewater analysis to monitor use of caffeine and nicotine and evaluation of their metabolites as biomarkers for population size assessment’, Water Research 74, pp. 23–33.
- Thomas, K. V., Bijlsma, L., Castiglioni, S., et al. (2012), ‘Comparing illicit drugs use in 19 European cities through sewage analysis’, Science of the Total Environment, 432, pp. 432–439.
- Tossmann, P., Boldt, S. and Tensil, M-D. (2001), ‘The use of drugs within the techno party scene in European metropolitan cities’, European Addiction Research, 7(1), pp. 2–23.
- Tscharke, B. J., Chen, C., Gerber, J. P., White, J. M. (2015), Trends in stimulant use in Australia: A comparison of wastewater analysis and population surveys’, Science of the Total Environment, 536, pp. 331–337.
- Van Nuijs, A., Mougel, J.-F., Tarcomnicu, I., et al. (2011), ‘Sewage epidemiology: a real-time approach to estimate the consumption of illicit drugs in Brussels, Belgium’, Environment International, 27, pp. 612–621.
- van Wel, J., Kinyua, J., van Nuijs, A., van Hal, G., Covaci, A. (2015), ‘Methodological considerations for combining wastewater-based epidemiology with survey research’, Archives of Public Health, 73, Suppl. 1, p. 29.
- van Wel, J, H. P., Kinyua, J., van Nuis, A. L. N., et al. (2016a), ‘A comparison between wastewater-based drug data and an illicit drug use survey in a selected community’, International Journal of Drug Policy, 34, pp. 20–26.
- van Wel, J. H. P., Gracia-Lor, E., van Nuijs, A. L. N., et al. (2016b), ‘Investigation of agreement between wastewater-based epidemiology and survey data on alcohol and nicotine use in a community’, Drug and Alcohol Dependence 162, pp. 170–175.
- Yang, Z., Anglès d’Auriac, M., Goggins, S., et al. (2015) ‘A novel DNA biosensor using a ferrocenyl intercalator applied to the potential detection of human population biomarkers in wastewater’, Environmental Science and Technology 49(9), pp. 5609–5617.
- Zuccato, E., Castiglioni, S., Senta, I., Borsotti, A., et al. (2016), ‘Population surveys compared with wastewater analysis for monitoring illicit drug consumption in Italy in 2010–2014’, Drug and Alcohol Dependence 161, pp. 178–188.
- Zuccato, E., Chiabrando, C., Castiglioni, S., Bagnati, R. and Fanelli, R. (2008), ‘Estimating community drug abuse by wastewater analysis’, Environmental Health Perspectives, 116(8), pp. 1027–1032.