A nuanced picture of illicit drug use in 17 Italian cities through functional principal component analysis of temporal wastewater data
Wastewater-based epidemiology is a novel approach in drug use epidemiology, which may provide more objective estimates of illicit drug use in a community. Functional data analysis (FDA) is a statistical framework specifically developed for analysing curves. We applied FDA to study weekly temporal patterns in wastewater curves for six different drugs in Italy.
Wastewater samples were collected over seven consecutive days in November 2013, from the inlet of 17 wastewater treatment plants in 17 Italian cities. The weekly temporal features of the drug loads throughout the week were extracted using functional principal component analysis (FPCA), obtaining functional principal component (FPC) curves and corresponding FPC score variables. The FPC score variables were used as outcome variables in linear regression analyses.
The most important weekly features of the drug loads were captured by the first three FPCs. The first FPC represented the general level of drug in the wastewater, while the second and third FPCs represented the discrepancy between the weekend peak and midweek level, and the weekend peak timing respectively. Cannabis was the predominant drug in the Italian wastewater, while ecstasy (MDMA) was the drug with the highest discrepancy between the weekend peak and midweek level. The Italian cities showed different patterns of drug use depending on several characteristics of the cities.
FPCA extracted detailed features of the weekly temporal patterns of the use of drugs derived from the wastewater analysis. This may help in understanding and monitoring the profile of drug use in a specific community.
KeywordsWastewater-based epidemiology Illicit drugs Functional principal component analysis Pattern of drug use
We gratefully acknowledge the European Union and the Norwegian Centre for Addiction Research (SERAF) for the financial support. We would also like to thank all colleagues from the SEWPROF team and SCORE group (www.score-cost.eu).
All authors have contributed to this scientific work and have approved the final version of the manuscript. EZ and SC have provided the wastewater data and revised the paper. SS, KFF, JR and JGB designed the study, the data analysis and revised the paper. SS analysed the data and drafted the manuscript.
Data sharing statement
The data used in this study are freely available: http://www.politicheantidroga.gov.it/attivita/pubblicazioni/relazioni-al-parlamento.aspx
Compliance with ethical standards
The study is funded by the EU-International Training Network SEWPROF (Marie Curie-FP7-PEOPLE Grant #317205) and the Norwegian Centre for Addiction Research (SERAF). The analytical campaign in Italy (“Aqua Drugs” Project) was supported by Dipartimento Politiche Antidroga (Presidenza del Consiglio dei Ministri, Rome, Italy).
The authors declare that they have no competing interests.
- Banta-Green CJ, Field JA, Chiaia AC, Sudakin DL, Power L, de Montigny L (2009) The spatial epidemiology of cocaine, methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA) use: a demonstration using a population measure of community drug load derived from municipal wastewater. Addiction 104:1874–1880. doi: 10.1111/j.1360-0443.2009.02678.x CrossRefPubMedPubMedCentralGoogle Scholar
- Burnham KP, Anderson DR (2002) Model selection and multimodel inference: a practical information-theoretic approach. Springer, Berlin HeidelbergGoogle Scholar
- Castiglioni S, Borsotti A, Senta I, Zuccato E (2015) Wastewater analysis to monitor spatial and temporal patterns of use of two synthetic recreational drugs, ketamine and mephedrone, in Italy. Environ Sci TechnolGoogle Scholar
- Dipartimento Politiche Antidroga PdCdM, Rome, Italy (2013) Relazione Annuale al Parlamento sull'uso di sostanze stupefacenti e sulle tossicodipendenze in ItaliaGoogle Scholar
- EMCDDA (2009) The state of the drug problem in the European Union and NorwayGoogle Scholar
- EMCDDA (2010) The state of the drugs problem in EuropeGoogle Scholar
- EMCDDA (2013) European drug report: trends and developmentsGoogle Scholar
- Froslie KF, Roislien J, Qvigstad E, Godang K, Bollerslev J, Voldner N, Henriksen T, Veierod MB (2013) Shape information from glucose curves: functional data analysis compared with traditional summary measures. BMC Med Res Methodol 13:6. doi: 10.1186/1471-2288-13-6 CrossRefPubMedPubMedCentralGoogle Scholar
- Ort C, van Nuijs AL, Berset JD, Bijlsma L, Castiglioni S, Covaci A, de Voogt P, Emke E, Fatta-Kassinos D, Griffiths P, Hernandez F, Gonzalez-Marino I, Grabic R, Kasprzyk-Hordern B, Mastroianni N, Meierjohann A, Nefau T, Ostman M, Pico Y, Racamonde I, Reid M, Slobodnik J, Terzic S, Thomaidis N, Thomas KV (2014) Spatial differences and temporal changes in illicit drug use in Europe quantified by wastewater analysis. Addiction. doi: 10.1111/add.12570 PubMedCentralGoogle Scholar
- Percival DB, Walden AT (2006) Wavelet methods for time series analysis, vol 4. Cambridge University Press, CambridgeGoogle Scholar
- Ramsay JOSB (2005) Functional data analysis, 2nd edn. Springer, Berlin HeidelbergGoogle Scholar
- Team RC (2015) R: a language and environment for statistical computing, vol 3.2.1. R Foundation for Statistical Computing, ViennaGoogle Scholar
- Thomas KV, Bijlsma L, Castiglioni S, Covaci A, Emke E, Grabic R, Hernandez F, Karolak S, Kasprzyk-Hordern B, Lindberg RH, de Alda M L, Meierjohann A, Ort C, Pico Y, Quintana JB, Reid M, Rieckermann J, Terzic S, van Nuijs AL, de Voogt P (2012) Comparing illicit drug use in 19 European cities through sewage analysis. Sci Total Environ 432:432–439. doi: 10.1016/j.scitotenv.2012.06.069 CrossRefPubMedGoogle Scholar
- van Nuijs AL, Castiglioni S, Tarcomnicu I, Postigo C, de Alda M L, Neels H, Zuccato E, Barcelo D, Covaci A (2011a) Illicit drug consumption estimations derived from wastewater analysis: a critical review. Sci Total Environ 409:3564–3577. doi: 10.1016/j.scitotenv.2010.05.030 CrossRefPubMedGoogle Scholar
- Vidakovic B (2009) Statistical modeling by wavelets vol 503. John Wiley & SonsGoogle Scholar
- Winje BA, Roislien J, Saastad E, Eide J, Riley CF, Stray-Pedersen B, Froen JF (2013) Wavelet principal component analysis of fetal movement counting data preceding hospital examinations due to decreased fetal movement: a prospective cohort study. BMC Pregnancy Childbirth 13:172. doi: 10.1186/1471-2393-13-172 CrossRefPubMedPubMedCentralGoogle Scholar
- Zuccato E, Castiglioni S (2012) Consumi di sostanze stupefacenti nelle città europee. Ricerca E Pratica 3:252–260Google Scholar