Illicit drug consumption in school populations measured by wastewater analysis

Highlights

• Wastewater (WW) analysis provided illicit drugs (ID) consumption results in line with population survey figures.

• WW analysis suggested that students used mainly and almost exclusively cannabis.

• Consumption of cocaine and opioids by students was very limited.

• Consumption of other substances by students was negligible.

Abstract

Background

Analysis of student consumption of illicit drugs (ID) by school population surveys (SPS) provides information useful for prevention, but the results may be influenced by subjective factors. We explored wastewater (WW) analysis to improve the information.

Methods

We used WW analysis to measure ID consumption in eight secondary schools in Italy in 2010-13 (students aged 15–19). Samples were collected from the sewage pipes of the schools during lessons for one week each year. Samples were analysed by mass spectrometry to measure ID and consumption by students was compared to that of the general population.

Results

We found THCCOOH (human metabolite of THC) concentrations in 2010 indicating significant consumption of cannabis in all the schools and benzoylecgonine (human metabolite of cocaine) suggesting a limited consumption of cocaine in all but one school. Morphine was only found in traces, and amphetamine, methamphetamine, ecstasy, ketamine and mephedrone were not detectable. Repeated analysis showed cannabis stable until 2012 with increases in 2013, low cocaine and morphine levels, and none of the other ID.

Discussion

WW analysis suggested that students used amounts of cannabis comparable to the general population, with low, sporadic use of cocaine and opioids, but excluded the use of significant amounts of amphetamine, methamphetamine, ecstasy, ketamine and mephedrone. WW analysis was useful to confirm SPS figures and provides complementary findings for effective prevention strategies. This is the first time WW analysis has been used to investigate consumption of a large number of ID and new psychoactive substances (NPS) in schools.

Introduction

Monitoring consumption is useful for preventing the spread of illicit drugs (ID) in the population and is particularly important for young people. In Italy, a school population survey (SPS-DAP) on drug use started at the beginning of the 2000 s (DPA, 2014) and is being repeated yearly (DPA, 2012). It permits analysis of the school population habits regarding the consumption of legal and illegal psychoactive substances and gives essential information for planning prevention strategies and enforcement action.

However, population surveys can be influenced by subjective factors, namely, whether the respondents answer questions truthfully about the substance abused, as investigation of a sensitive and stigmatized behavior may generate inaccurate reporting (Harrison, 1997), and the bias can hamper the targeting and efficacy of preventive measures. It is still harder to study consumption of new psychoactive substances (NPS), as consumers frequently do not know which they are really taking. In this case WW analysis provides findings that could not be obtained by any other method, including population surveys. In this study, we explored the utility of wastewater (WW) analysis for complementing school population surveys, with the aim of generating detailed and reliable figures of ID use by students, useful for prevention and enforcement.

WW analysis is a recently proposed approach to population studies to measure ID consumption in communities (Zuccato et al., 2008, Zuccato et al., 2005). It is based on chemical analysis and quantification of the metabolic residues of the drugs excreted by consumers in WW with urine (urinary biomarkers) (Castiglioni et al., 2006). Its application to study ID consumption has given results that complement figures from population surveys (Banta-Green et al., 2009, Reid et al., 2012, Zuccato et al., 2016, Zuccato et al., 2011).

WW analysis has been applied to large communities, and smaller ones, like prisons (Postigo et al., 2011) or schools (Panawennage et al., 2011), have also been investigated. Here we present the findings of a systematic investigation of ID consumption by secondary school students in Italy (aged 15–19 years). To our knowledge, this is the first investigation of ID consumption in schools conducted by WW analysis. Panawennage et al. conducted a pilot study in collaboration with our group (Panawennage et al., 2011), while Burgard et al. (Burgard et al., 2013) reported results on amphetamine during an investigation on ADHD-drugs abuse in 2013. Our study has investigated ID consumption within several schools more extensively (all the common drugs and some NPS) and over a greater period of time than previous studies. The results might be useful to complement school population surveys, and to provide an integrated assessment of ID consumption by students.

We collected WW samples from sewage pipes of eight secondary schools in Italy, attended by more than 6000 students. Samples were collected daily during school time, for five or six consecutive days, and analyzed for biomarkers of consumption of cocaine, opioids (morphine/heroin), cannabis, amphetamine, methamphetamine, ecstasy, ketamine and mephedrone by the people attending the schools. Sampling was done in March 2010 and repeated in three schools in October 2011, March 2012, October 2012 and November 2013.

The study was conducted in collaboration with the National Agency for Drug Policy (Dipartimento Politiche Antidroga). Samplings were done with the informed consent of the school authorities but to avoid biases students were not aware of the study. For privacy reasons, results are reported anonymously. Only the location of the schools will be disclosed, and any other information blinded, as established by the ethical guideline recently developed for wastewater analysis studies (Prichard et al., 2014).