Estimation of illicit drugs consumption by wastewater analysis in Paris area (France)

Abstract

Illicit drugs consumption is actually an important public health concern that needs to be well defined to be managed. A new method, expressed as sewage epidemiology has been proposed by Daughton and developed by Zuccato. This method involves estimating the consumption from the measurement of drug residues in sewage. Several studies have been carried out, leading to an assessment of drugs consumption in some European countries. This work, carried out in Paris area (France) brings new data to this assessment and allows a comparison of cocaine and MDMA consumptions with European estimations.

Four wastewater treatment plants (WWTPs) have been retained for the study, taking into account biological treatment, volume capacity, geographic location and social environment. Cocaine and its major metabolite benzoylecgonine (BZE), amphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and buprenorphine were measured in raw water and WWTP effluent using HPLC–MS/MS after SPE extraction. Amphetamine was rarely detected. Cocaine and BZE were quantified at levels from 5 to 282 ng L⁻¹ and 15 to 849 ng L⁻¹, respectively. MDMA and buprenorphine concentrations remained under 20 ng L⁻¹. Cocaine consumption was estimated from cocaine or BZE concentrations measured in raw water and the results showed significant difference in drug taking during week or weekend. The estimated doses observed in this study are lower than those reported for others countries, especially Spain and Italy. MDMA consumption was estimated at lower levels than cocaine.

Introduction

Illicit drug consumption and abuse is a great social and health problem that meets with the difficulty of realistic consumption estimations. Indeed, statistics deduced from data obtained from medical centres, police statistics or health and social organizations prove that consumption is increasing. According to the last European Monitoring Centre for Drugs and Drug Addiction annual report [1], respectively 22.5 and 4 millions people in Europe have consumed cannabis or cocaine during the last year. In France, the percentage of 15–34 years old people consuming cocaine increased from 0.5% in 2000 to 1.2% in 2005.

As with pharmaceuticals, illicit drugs and their metabolites are eliminated through urban wastewaters and have been recognized as emerging environmental contaminants. Several studies have been carried out to evaluate illicit drugs concentrations in sewage waters at the entry of wastewater treatment plants (WWTPs): cocaine levels varied from several hundreds ng L⁻¹ in Italy [2], in Belgium [3], [4] or in Spain [5] to some μg L⁻¹ in Catalonia in Spain [5], [6]. For example, Huerta-Fontela et al. [6] found a median level for cocaine of 0.2 μg L⁻¹ in 42 WWTPs influents with a wide range between 0.004 and 4.7 μg L⁻¹ (Table 1). For the same samples, BZE concentrations varied from 0.009 to 7.5 μg L⁻¹ and amphetamine concentrations between 3 and 688 ng L⁻¹. In comparison, Kasprzyk-Hordern et al. [7] analysed raw water of two WWTPs in South Wales and found mean levels of amphetamine (1196 and 4310 ng L⁻¹), higher than those of cocaine (207 and 521 ng L⁻¹) and benzoylecgonine (1082 and 992 ng L⁻¹). However, Castiglioni et al. [2] found low levels of amphetamine in influents of a WWTP located in Milano but they did not detect it in influents of a WWTP located in Lugano (Switzerland).

Drugs residual concentrations are detected in WWTPs effluents leading to contamination of surface waters: Zuccato et al. [8] reported mean cocaine levels from 0.5 to 44 ng L⁻¹ in Italian rivers, and BZE levels 3–5 times higher.

Moreover, it has been shown that these levels followed consumption variations during weekends or special events such as music festivals [9]. An increase of consumption is observed for cocaine, ecstasy and amphetamine on Saturday/Sunday [6], [8]. However, Mari et al. [10] observed variations along a year without clear tendency of consumption period.

In a context of public health, it appears essential to improve the assessment of consumption, i.e. to identify the geographic areas and the periods most favorable to drug consumption or abuse. Indeed, illicit drug consumption is supposed to be related to professional or social conditions. More, the quantities consumed can be improved during some festive events. Thus, it should be useful to define more closely the relation between drug consumption and social conditions. This is especially important for social organizations that work in the risk prevention in particular to prevent the transmission of AIDS or hepatitis C. The French government helps associations which manage and maintain street automatic dispensers of sterile syringes kit in aid of the drug-addicts and these associations need better consumption indicators to improve the dispenser deployment inside the city.

An innovative method has been described by Daughton [11] and developed by Zuccato et al. [12], [13] to estimate drug consumption from wastewater measurements. Indeed, the quantity of drug consumed can be deduced from the drug or metabolite(s) flows measured in raw WWTP influent weighted from pharmacokinetic data, i.e. percentage of drug eliminated in the parent form or percentage of a specific metabolite in the metabolic pathways. This new estimation tool from sample collection to back-calculation has been adopted by the EMCDDA [14] as a realistic method and studies have been done in Belgium [4], Italy [10] and United-Kingdom [7].

The aim of this work was to assess, for the first time in France, the consumption in the city of Paris and greater suburban area, of four illicit drugs: cocaine, amphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and buprenorphine. Buprenorphine is used under medical control for the treatment of opioid dependence. However, this compound is also used in an illicit manner and this is the reason why we choose to add it to the list of studied illicit drugs. In our knowledge, buprenorphine has never been included in published studies on illicit drugs in wastewater. Different WWTPs were selected according to the characteristics of treatment technologies, the volume capacity and the social and economic environment of the connected area.