Understanding Illicit Drug Use Trends During the Carnival Holiday in the Brazilian Capital Through Wastewater Analysis

Cocaine and cannabis consumption during and after the 2019 Carnival holiday were assessed using the wastewater-based epidemiology (WBE) in the capital of Brazil, Brasília. The substances 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH), cocaine (COC), benzoylecgonine (BE), and cocaethylene (COE) were monitored in composite samples (24 h) collected in the entrance of North-Wing (NW) and South-Wing (SW) wastewater treatment plants (WWTP) for 15 consecutive days, including the Carnival holiday. Aliquots (100 ml) were enriched with isotope-labeled standards, solid-phase extracted and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results reveal higher cocaine consumption during the Carnival (average of 2.8 ± 0.7 g/1000inh/day) compared to the subsequent period (average of 1.7 ± 0.3 g/1000inh/day). Cannabis (THC) use was also higher during the holiday (14 ± 5 g/1000inh/day) but differences were not significative (unpaired t-test, 95%) compared to the following days (11 ± 3 g/1000inh/day), where consumption remained relatively constant corroborating that cannabis overall consumption is less affected by occasional abuse. Regarding cocaine, an unusual low consumption was noticed in the weekend immediately after the Carnival Holiday, indicating lower demand or supply issues. Higher cocaine and cannabis use was observed throughout the entire sampling period in the area covered by NW-WWTP, probably due to the higher proportion of young people. This investigation brings the first data on cannabis use in Brazil by WBE and confirms this strategy as a well consolidate tool for estimating illicit drug use and abuse.

Introduction

Residues from licit and illicit drugs, personal care products, hormones, pathogens, and a variety of substances associated with consumer products have been investigated in environmental samples, considering their relation to lifestyle in modern societies (Pal et al., 2014). Although wastewaters are an important source of these contaminants of emerging concern to the environment, their investigation may also reveal population exposure, behavior and habits (Gracia-Lor et al., 2017; Choi et al., 2019).

Recently, wastewater-based epidemiology (WBE) emerged as a monitoring strategy to assess population exposure do SARS-CoV-2 worldwide (Ahmed et al., 2021). However, it has also been used for the past decade to estimate population exposure to pharmaceuticals, pesticides and, most notably, illicit drugs (Choi et al., 2018; Lorenzo and Picó, 2019). Illicit drug use estimates using wastewater analysis allow dynamic and rapid investigations into the temporal and geospatial evolution of consumption (Choi et al., 2018). In addition, WBE can provide important information about illicit drug use at special events, such as National holidays and popular festivals.

Several studies show an increase in the concentration of drug residues in wastewater collected during holidays, festive and sport events in different regions of the world (Sodré et al., 2017; Verovšek et al., 2020; Montgomery et al., 2021). Music event attendees, for example, may consume illicit substances more often in comparison with ordinary people of the same age group. Such festive events are therefore opportune for monitoring illicit drug use (Van Havere et al., 2011). Rushing and Burgard (2019) reported higher loads of cocaine and its major metabolite, benzoylecgonine, in wastewaters collected during the Pride festival in Washington (United States). In Queensland (Australia) Lai et al. (2013b) monitored residues of drugs and their metabolites in wastewaters and found that cannabis and cocaine use steadily increased throughout a six-day annual music festival. Mackuľak et al. (2019) showed that there was preferential use of cocaine at dance and multi-genre themed festivals, while cannabis was the drug of choice at a pop-rock festival, evidencing that the abuse of drugs is closely associated with specific musical preferences. These findings show that the illicit substance market is rapidly expanding into special music events where attendees appear to be willing to abuse drugs.

A significant increase in cocaine loads was also observed during the Independence Day in US (Foppe et al., 2018), the Easter holiday in France (Thiebault et al., 2019), the Chinese National Day (Zhang et al., 2019), and the Brazilian Carnival (da Silva et al., 2018). Lai et al., 2013a) and Huerta-Fontela et al. (2008) found that cannabis and cocaine use on Christmas and New Year’s Eve increased in urban areas of Australia and Spain, respectively. The concomitant use of cocaine and alcohol was assessed by da Silva et al. (2018) through the high content of cocaethylene in a wastewater sample collected during the 2018 Carnival Holiday in Brazil. The authors suggested that cocaine use could be even higher, as the ingestion of ethanol with cocaine leads to the excretion of cocaethylene instead of benzoylecgonine, the main metabolite used to estimate consumption.

As the previous findings assessing cocaine consumption during the Brazilian Carnival were obtained through the analysis of a single sample collected in the nation capital, Brasilia (da Silva et al., 2018), the goal of this study is to assess, for the first time, cannabis and cocaine consumption (including the analysis of cocaethylene) in wastewater samples from two treatment plants, collected throughout the entire Carnival holiday and in subsequent days, totalizing 15 consecutive days of sampling. This complementary work aims to provide a better understand on the illicit drug use trends as influenced by a major special event such as the Carnival in Brazil. To the best of our knowledge this is also the first study assessing cannabis consumption using WBE in Brazil. In addition to the data produced involving cocaine use, the results can help authorities to map hot spots of drug use and associate them with the behavior of illicit drug users during special events and regular days of the week.

Materials and Methods

Chemicals and Reagents

Cocaine (COC) and its metabolites benzoylecgonine (BE) and cocaethylene (COE) were purchased from Cerilliant (Round Rock, TX, United States) as solutions of 1 mg/ml in acetonitrile (ACN). The main metabolite of tetrahydrocannabinol, 11-Nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) was also obtained from Cerilliant as a 0.1 mg/ml methanol (MeOH) solution. Deuterated compounds were used as surrogate standards for analytical quantitation. Cocaine-D3 (COC-D3), benzoylecgonine-D3 (BE-D3), cocaethylene-D3 (COE-D3), and THC-COOH-D3 were supplied by Cerilliant. Mixed solutions were prepared with MeOH whereas working solutions were prepared before analysis by successive dilutions of the mixed solution with MeOH and stored at −20°C in the dark.

Formic acid (98%) MS-grade, hydrochloric acid (HCl, 37%) and MeOH (LC LiChrosolv grade) were purchased from Merck (Darmstadt, Germany). Ultrapure water was produced in a Milli-Q Academic system (Millipore, Bedford, MA, United States).

Characterization of the Study Area

This work was carried out in the Brazilian capital, Brasília. Along with other satellite cities and administrative regions, Brasilia is part of the Brazilian Federal District (FD), a relatively small three million inhabitants’ unit, politically equivalent to the other 26 Brazilian states. With an airplane shape, Brasília was specifically planned and build from the scratch in the 1960s to host the executive, legislative and judicial branches. The so-called Pilot Plan is organized in sectors that concentrate certain types of activities, such as banking, financial, commercial, hospital, entertainment and residential sectors. Wastewater produced in the FD is collected and treated in 15 wastewater treatment plants (WWTP), but in the present work only two, located in the south and north wings of the Pilot Plan, were selected (Figure 1). The South-Wing (SW) WWTP serves around 525,000 people residing in ten administrative regions of the FD while North-Wing (NW) WWTP covers an area with approximately 145,000 inhabitants from five administrative regions. Together, they serve the entire population of Brasília (Pilot Plan) and around 22% of the entire FD.

FIGURE 1

FIGURE 1. Map showing the location of Brasília, in the Brazilian Federal District (Brazil), and the areas served by the North-Wing and South-Wing wastewater treatment plants.

Characterization of the Carnival Holiday in Brazil

Carnival is the most popular festival holiday in Brazil. Celebrations occur between February and March and usually begin on Friday afternoon, ending on the Ash Wednesday at noon, marking the beginning of Lent, the forty-day period before Easter, according to Catholic tradition. During this period, several festive events take place throughout Brazil, from North to South. The southeast cities of Rio de Janeiro and São Paulo host the most famous carnival parades, while in the northeast cities of Salvador, Recife and Olinda, more emphasis is given to the street events. In practice, the country is virtually unified for almost a week, in day and night festivities, accompanied by lots of music, dancing and drinking throughout the holiday. In Brasília, as in the vast majority of Brazilian cities, there are daytime activities on the streets as well as night parties in sport clubs, associations and nightclubs. The Carnival holiday studied was in 2019 and started on Friday, March 1st and ended on Wednesday, March 6th, although related events may also have occurred few days before or after this period.

Sampling and Sample Preparation

Raw sewage influents from the two WWTPs were collected daily, over two consecutive weeks, from March 1st to 15th 2019, with the exception of the 08/03 sample which was not collected at SW-WWTP due to logistical issues. This period corresponded to the Carnival holiday and the following days. On each day, 24-h flow proportional composite samples were obtained from each WWTP using refrigerated automatic wastewater samplers (AS950 AWRS, Hach, Loveland, CO, United States). Sampling began 12 midnight (12.00 a.m.) and ended at the same hour on the next day. During this period, aliquots were kept in the dark at 4°C. The composite samples were then taken to the laboratory in amber glass bottles every day at 7:00 a.m. and analyzed on the same day.

Sample preparation was carried out according to the protocol proposed by Causanilles et al. (2017a). Briefly, 100-ml wastewater aliquots were pH-adjusted (7.0), enriched with 4 ng/ml of the surrogate deuterated standards, passed through 1.2 μm GF/C glass microfiber filters (Whatman, Maidstone, United Kingdom) followed by 0.45 µm cellulose acetate membranes (Whatman, Maidstone, United Kingdom). Then, they were transferred to individual syringe tubes connected in line to disposable cartridges for solid-phase extraction (SPE) containing 500 mg of a polystyrene divinylbenzene sorbent with both hydrophilic and lipophilic groups (HLB Oasis, Waters, Milford, CT, United States). The sorbent was conditioned with 10 ml of MeOH and 10 ml of pH 7.0 ultrapure water and samples percolate cartridges at a flow rate of 3 ml/min in order to provide adequate contact between analytes and the solid phase. Cartridges were then centrifuged at 4,000 rpm for 8 min to eliminate residual water and stored at –20°C until the elution step (Senta et al., 2014; Causanilles et al., 2017a). Immediately before analysis, the analytes were eluted from the cartridges with 10 ml of MeOH and recovered into previously cleaned glass tubes. The eluates were individually evaporated under vacuum in a Syncore Analyst system (Buchi, Flawil, Switzerland) in order to obtain a volume of approximately 0.2 ml and the extract was diluted to a final volume of 1.0 ml using a 0.1% (v/v) formic acid solution prepared in ultrapure water. Before injections, extracts were filtered through a 0.22 µm PVDF syringe membranes (Merck Millipore, Billerica, MA, United States) in order to avoid residual solids.

Quantification of the Target Analytes

Extracts were analyzed by liquid chromatograph (1200 Series, Agilent, Santa Clara, CA, United States) coupled to triple-quadrupole (QqQ) mass spectrometer (QTRAP 3200, Sciex, Toronto, Canada) with electrospray ionization (ESI) interface operating at 550°C and 5500 V, using nitrogen as curtain gas at 10 psi and as auxiliary and nebulizing gas at 40 and 45 psi, respectively.

Separation was performed at 30°C using a Kinetex C18 column (2.1 mm × 50 mm, particle size of 1.3 μm, Phenomenex, Torrance, CA, United States) with gradient elution (0.2 ml min⁻¹) using water and ACN as mobile phases containing 0.1% (v/v) of formic acid, used to improve ionisation and the intensity of analytical signals. The gradient was achieved by maintaining a relative ACN concentration of 20% for 1 min, followed by the increase to 95% in 5 min, and held constant for 4 min. After readjusting to the initial conditions, the system was re-equilibrated for 5 min. The injection volume was 10 μL.

Mass spectrometric analyses were carried out using the multiple reaction monitoring (MRM) mode in order to identify and quantify the target analytes by measuring the fragmentation products of the protonated molecular ions [M + H]⁺ for all analytes. Each analyte was monitored using the two most abundant precursor → product ion transitions. Instrumental parameters, such as declustering potential (DP), entrance potential (EP), collision cell entrance potential (CEP), collision energy (CE) and collision cell exit potential (CXP) were optimized for each analyte as shown in Table 1.

TABLE 1

TABLE 1. Mass spectrometer parameters used during the analysis, chromatographic retention times and limits of detection and quantification of the target analytes.

All analytes were quantified by internal standard calibration using 8-points analytical curves (1.0–350 μg/L for the cocainics and 5.0–350 μg/L for THC-COOH) prepared in tap water in a matrix-matched approach. Curves (R² > 0.995) were previously tested for the homogeneity of variances by the Cochran test. Limits of quantification of the method (LOQ) were expressed by the lower standard concentration of the analytical curves divided by the pre-concentration factor of 100 times. Limits of detection (LOD) were calculated using LOQ divided by the factor of 3.3. Recoveries from a wastewater spiked solution (500 ng/L) ranged from 77% (THC-COOH) to 102% (BE) (RSD < 9.9%). The software Analyst was used to instrument control and data acquirement, whilst data treatment was performed using the SignalFinder1 algorithm in the Multiquant platform, both integrated to the Analyst software.

Illicit Drug Use Estimates

Cocaine and cannabis consumption estimates ($C$), in mg/1000inh/day, were calculated according to Eq. 1, where $c$, in mg/L, is the concentration of the biomarker (BE for cocaine and THC-COOH for cannabis estimates), $Q_v$ is the volumetric flow of the influent wastewater (L/day), $f$ is a correction factor associated to the excretion of the biomarker in relation to the drug consumed and $hab$ is the number of inhabitants served by the WWTP.

$C=\frac{c\times Q_v\times f}{inhab}(1)$

For cocaine use estimates, a $f$ value of 4.19 has been used in Brazil (da Silva et al., 2018; Sodré et al., 2018), reflecting a weighted urine excretion factor of 25% of BE as influenced by pharmacokinetics studies (Castiglioni et al., 2013) as well as by the average route of administration of cocaine in Brazil with a prevalence of intranasal (cocaine hydrochloride) adult users (70%) in comparison with crack (free-base) users (30%) (Laranjeira et al., 2014). For cannabis (THC), an average excretion of 0.5% of THC-COOH in urine is considered when cannabis is administered via the pulmonary route. Therefore, considering a THC/THC-COOH molar ratio of 0.91, the $f$ value is 182 (Gracia-Lor et al., 2016).

For all intents and purposes, in this work, estimated cannabis consumption refers to THC, the main active ingredient in any of the very broad families of cannabis products available (marijuana, hashish, extracts, amid others).

In addition to the carnival period, two other periods were analyzed in the present work. Wastewater samples from Monday to Thursday were considered weekdays, while those from Friday to Sunday were considered weekends. As sampling starts at midnight, user contribution during Friday night social activities can be computed. This approach has been used elsewhere (Celma et al., 2019; Bijlsma et al., 2021; Kuloglu Genc et al., 2021), probably because users may abuse alcohol and other drugs during promotions such as “happy hours,” which usually take place on Thursday, Friday and Saturday nights. In addition, Dázio et al. (2016) investigate the use of alcohol and controlled drugs among male university students in Brazil and show that preferred days to use controlled substances are Fridays and Saturdays.

Results and Discussion

Concentration of the Target Analytes in Wastewater

Table 2 shows the concentration of cocaine, benzoylecgonine, cocaethylene and carboxi-THC obtained during 15 consecutive days in wastewater samples collected in the North-Wing and South-Wing WWTP.

TABLE 2

TABLE 2. Daily concentrations, in ng/L, of the investigated substances in the wastewater samples and average volumetric flow at the sampling points during the sampling period.

The concentrations of cocaine and benzoylecgonine were similar to those found in previous studies carried out in both WWTPs (Maldaner et al., 2012; Sodré et al., 2017, 2018; da Silva et al., 2018). However, concentrations of cocaethylene in this work, ranging from 3 to 53 ng/L, were lower than those observed by da Silva et al. (2018) for samples collected at the same sampling points in a regular week of 2017 (19–188 ng/L). Regarding THC-COOH, data shown in Table 2 are the first obtained in wastewater samples from the study region and, to the best of our knowledge, from the entire Brazilian territory. Figure 2 portrays the concentrations ratios of the target analytes.

FIGURE 2

FIGURE 2. Concentration ratios of the investigated substances. Data from the North-Wing WWTP in red and from the South-Wing WWTP in blue. For COE/BE ratios, COE concentrations between LOD and LOQ were represented by LOQ/2. Values below LOD were not included.

The values for COC/BE ratios in Figure 2, ranging between 0.27 and 0.71 (average 0.43 ± 0.09), are in agreement with previous studies (da Silva et al., 2018; Sodré et al., 2018) and indicate the predominance of human consumption to explain the origin of cocaine in the samples. Higher ratios were observed for samples collected during the weekdays in both investigated WWTP.

Although van Nuijs et al. (2009) have suggested a cut-off value of 0.75 to indicate sources unrelated to cocaine consumption, such as transport and handling in streets or clandestine facilities, the proportions of parental cocaine and its metabolites in excreted urine may vary significantly depending on the time of use, route of administration and co-consumption with other substances (Shimomura et al., 2019; Isenschmid, 2020). Moreover, transformations may also occur in sewage or samples if proper preservation routines are not implemented during analysis (McCall et al., 2016).

In-sewage transformations of cocaine, benzoylecgonine and cocaethylene were previously estimated considering ambient conditions of the Brasilia wastewaters (pH 7.5 and temperature of 23°C) during 24 h (da Silva et al., 2018). Considering the results, where a relative decrease of 14.6% for cocaine and an increase of 9.0% for benzoylecgonine was observed, the COC/BE ratios should become smaller and smaller over time. Therefore, monitoring COC/BE rations should still be promising to investigate sources unrelated to illicit drug use. One can consider that high COC/BE ratios could be potentially useful to indicate the disposal of non-consumed drugs into sewer systems. However, conclusions about the origin of the drug using diagnostic ratios must be made with care, even if they are promising to support decision-making related to public safety in countries such as Brazil, which borders the three largest cocaine producers—Colombia, Peru, and Bolivia—and is a major transit point for cocaine smuggling to Europe through Central and West Africa (Miraglia, 2015). Nonetheless, COC/BE ratios between 0.76 and 25.83 were reported in samples collected in Bursa—Turkey indicating that not all cocaine loads were from human consumption (Kuloglu Genc et al., 2021). According to the authors, cocaine was widely seized in Europe during 2017, leading to a new smuggling route from Turkey to Europe.

It is important to point out that low rates of metabolic conversion of cocaine to benzoylecgonine could also be a consequence of the concurrent use of cocaine with other substances such as ethanol and clinical drugs (Shimomura et al., 2019; Abbott et al., 2020). The combination of cocaine and ethanol, in addition to forming cocaethylene, dramatically alter the molar ratios of cocaine metabolites. Harris et al. (2003) found that ethanol ingestion before cocaine administration decreased urinary benzoylecgonine levels by 48% and increased urinary cocaethylene and ecgonine ethyl ester levels. In this case, COC/BE ratios may become higher due to the use of cocaine concomitantly with alcohol, with the consequent formation of cocaethylene. It is interesting to note that, in fact, the highest COC/BE ratios observed on weekdays (Figure 2) are followed by high COE/BE ratios (cocaethylene/benzoylecgonine), notably for samples collected at the North-Wing WWTP.

In the present work, the COE/BE ratios were strangely higher during the ordinary weekdays, while high values are normally expected during the weekends and at the Carnival, as shown earlier (da Silva et al., 2018). In view of the low cocaethylene values determined in the samples, the COE/BE ratios were also below those reported in other studies, where values ranged between 0.025 and 0.055 (Cami et al., 1998; Harris et al., 2003). On the 2018 Carnival holiday, for example, da Silva et al. (2018) reported values around 0.07 for samples collected in Brasília, while in the present work, COE/BE ratios ranged between 0.002 and 0.034.

Concomitant use of alcohol and cocaine is quite common at festive events and during regular weekends (Van Havere et al., 2011). This is a potentially harmful combination, since cocaethylene is an active substance, with a stimulant action similar to that of cocaine, while benzoylecgonine is a non-active metabolite (Shimomura et al., 2019). Cocaethylene excretion is less than 1%, with higher values directly associated with the proportion of alcohol and cocaine ingested (Harris et al., 2003; Herbst et al., 2011; Occupati et al., 2017). With this information, it is theoretically possible to assess whether there was significant co-consumption of cocaine with alcoholic beverages by estimating COE/BE ratios. Rodríguez-Álvarez et al. (2015) compiled pharmacological data concerning the administration of both substances and suggest a cut-off value of 0.039. None of the COE/BE ratios obtained in the present work was higher than the reference value.

Ratios between the metabolites used to estimate cannabis and cocaine use, THC-COOH and benzoylecgonine, respectively, are also shown in Figure 2. Higher THC-COOH/BE values were constantly observed for samples collected in the North-Wing WWTP, independently of the sampling period. Although such diagnostic ratio is not commonly used in the literature, it may be useful to compare the prevalence of cannabis consumption between different regions under investigation.

Illicit Drug Use Estimates During the Sampling Period

In Figure 3, illicit drug use estimates, in mg/1000inh/day, are shown for the investigated regions during the 2019 Carnival holiday and the subsequent days.

FIGURE 3

FIGURE 3. Cocaine and cannabis (THC) per capita consumption estimated in the regions covered by North-Wing (NW, in red) and South-Wing (SW, in blue) WWTPs. The gray area represents the Carnival period and dates in bold represent the days of the weekend.

Cocaine use during the Carnival holyday was higher than in the subsequent period, a result in agreement with previous findings (da Silva et al., 2018). Considering both investigated regions, an average cocaine consumption of 2754 ± 686 mg/1000inh/day (mean ± confidence interval, 95%) was noticed during the Carnival holyday period (from the 1st to the 6th of March), whereas for the subsequent period, from the 7th to the 15th of March, a consumption of 1739 ± 327 mg/1000inh/day, significantly lower (unpaired sample t-test, t = 3.05 > t_P=0.05 = 2.05), was observed. Higher cocaine consumption was observed in the region covered by the North-Wing WWTP compared to the region served by the South-Wing WWTP, with the exception of three isolated days. This result is consistent with findings from the last 10 years that have always shown higher cocaine use in the northern region of Brasília (Maldaner et al., 2012; Sodré et al., 2017, 2018; da Silva et al., 2018; González-Mariño et al., 2019).

During the Carnival period, it is possible to notice a gradual decrease in cocaine consumption in the last days of the holiday (except for 03/05), as well as shortly after, between the 6th and 12th of March. This behavior is intriguing, as it indicates a relatively lower cocaine use on the weekend following the Carnival period, although several studies have shown that there is a higher use of cocaine, as well as other stimulant drugs, on weekends compared to weekdays. Therefore, three hypotheses may be raised to understand this behavior. The first considers that the high use of cocaine during the carnival holiday, almost 60% higher than the subsequent period, results in an immediate reduction in drug use on the following weekend, as if users were facing a kind of hangover from cocaine. Actually, this behavior is typical of binge users, i.e., episodic users who consume repeated doses of cocaine followed by a period of abstinence (Vosburg et al., 2010).

The second hypothesis is based on the fact that cocaine is a drug whose intense use is more often related to recreational and social activities (Zuccato et al., 2008; Tscharke et al., 2016; Verovšek et al., 2020). Thus, the cocaine hangover may have been motivated both by excessive use during Carnival and by the relative low frequency of parties and recreational activities on the weekend immediately after the festivities. Finally, the third hypothesis considers a possible decrease in the supply or a reduction of purity of cocaine on the streets, precisely because of the excessive demand during the Carnival. In this case, the low consumption on the weekend after holiday may be related to the dynamics of drug trafficking, affected by the high demand during the festivities. Although there is a lack of elements to support any of the hypothesis, future work can be carried out in coordination with the activities of the National Secretariat for Drug Policies (SENAD), one of the funders of wastewater-based epidemiology studies in Brazil.

In Figure 3, it is also possible to observe that cocaine consumption in both investigated areas rose sharply from March 13th, suggesting that drug use increases in the next weekend as expected.

Regarding cannabis, the first notable aspect in Figure 3 is the higher consumption in the region served by the North-Wing WWTP compared to the southern region of Brasília. Considering that drug use is more frequent among adolescents, young adults and adults (UNODC, 2021), the difference in the consumption profile in the investigated regions may be associated to the relative higher proportion of young people in administrative regions served by North-Wing WWTP (CODEPLAN, 2016). Also, the northern part of the Brasília Pilot Plan is characterized by a high number of colleges and universities, including main campus of the University of Brasília. Higher THC-COOH concentrations were also reported by Mackuľak et al. (2014) in areas with increased concentration of young people and artists in the Slovak Republic.

Apparently, cannabis consumption in Figure 3 was higher during the Carnival holiday compared to the subsequent period. A deeper look at the data reveals an average consumption of 14,342 ± 5232 mg/1000inh/day (mean ± confidence interval, 95%) during the Carnival period (from the 1st to the 6th of March), while for the subsequent period, from the 7th to the 15th of March, a consumption of 11,471 ± 2679 mg/1000inh/day was noticed. Although a higher cannabis consumption is observed for the Carnival period, a statistical comparison (unpaired sample t-test, t = 1.11 < t_P=0.05 = 2.05), revealed that there is no significant difference between the tested data. Therefore, there are indications to believe in a higher consumption of cannabis during the Carnival holiday, but the results presented here are not conclusive.

Our results concerning cannabis use during a major summer event are in agreement with other reports in the literature. Nefau et al. (2013) observed a lack of weekend effect on cannabis use in French cities, suggesting that cannabis is not a typical festive drug such as cocaine or MDMA. Mackuľak et al. (2014) investigated drug use at two important Slovak music events and could not confirm the increase in the number of cannabis users during these summer festivals. No observable effect on illicit drug use was also reported by Devault et al. (2020) during the World Music Day in Bordeaux, a French festival with massive public participation in the streets. Foppe et al. (2018) verified that THC use in a community of Western Kentucky (US) was not influenced by special events, such as the Independence Day and the first week of semester, compared to a regular week. However, in another community, THC consumption was 78% higher during the Independence Day festivities (3rd, 4th, and 5th of July) compared to a typical week. Mackuľak et al. (2019) analyzed wastewater samples during seven music festivals in the Czech and Slovak Republics evidencing that cocaine and methamphetamine loads increased during rock and dance music festival, whereas cannabis was consumed independently on the music genre preferences. Bijlsma et al. (2020) investigated illicit drug use at six music festivals across Europe and observed higher THC-COOH loads (approximately 10 times) during a pop/rock festival in Portugal compared to a regular period. The authors also observed higher levels of traditional illicit drugs in the investigated samples (wastewater and pooled urine) compared to new psychoactive drugs (NPS). All mentioned events, including the Brazilian carnival, are notably popular among young people, and could explain the increase in THC consumption, as youth tends to underestimate cannabis dangers (UNODC, 2021).

After the Carnival holiday, cannabis consumption remained relatively constant throughout the week, a behavior that is well documented in the literature (Lai et al., 2011; Tscharke et al., 2016; Zuccato et al., 2016). Therefore, it is possible to infer that in Brasília/Brazil, differently from cocaine, cannabis is not a drug of occasional abuse, exhibiting a usage profile similar to that of tobacco, for example.

Figure 4 shows the average illicit drug use considering different periods, i.e., the Carnival holiday (March 1st to 6th), weekends (Fridays, Saturdays and Sundays between March 7th and 15th), and weekdays (remaining days from March 7th to 15th). As previously reported, cocaine consumption is directly related to social and special events. Thus, higher values are observed for the Carnival holiday, followed by weekends, and weekdays, as expected, in both regions studied. Even though a period of decrease in consumption was observed immediately after Carnival, the compilation of data from the entire sampling period was still able to show a slightly higher consumption during weekends compared to weekdays.

FIGURE 4

FIGURE 4. Cocaine and cannabis (THC) consumption in the regions covered by North-Wing (NW) and South-Wing (SW) WWTPs in different periods during March 1st to 15th, 2019.

Estimates of cocaine consumption corroborate the high exposure of the Brazilian population to this illicit drug. The estimated average consumption in the regions served by the North-Wing and South-Wing WWTPs after Carnival, 2149 ± 479 and 1279 ± 453 mg/1000inh/day, respectively, are similar to estimations produced in Reus and Castellón—Spain (2.8 and 1.1 g/1000inh/day, respectively) (Bijlsma et al., 2021), Medellín—Colombia (3022 mg/1000inh/day) (Bijlsma et al., 2016), Reykjavik—Iceland (2660 mg/1000inh/day) (Löve et al., 2022), Fort de France—Martinique (2420 mg/1000inh/day) (Devault et al., 2014), El Roble—Costa Rica (2390 mg/1000inh/day) (Causanilles et al., 2017b), and higher than values reported in New South Wales, Victoria, and Queensland—Australia (893, 719, and 640 mg/1000inh/day) (Wilkins et al., 2018), San Luis Río Colorado—Mexico (370 mg/1000inh/day) (Cruz-Cruz et al., 2021), Athens—Greece (213 mg/1000inh/day) (Gatidou et al., 2016), Istanbul—Turkey (201 mg/1000inh/day) (Asicioglu et al., 2021), Kotka—Finland (54 mg/1000inh/day) (Kankaanpää et al., 2016), and Diyarbakır—Turkey (47 mg/1000inh/day) (Daglioglu et al., 2021).

Figure 4 shows slightly differences between cannabis use in the three studied periods, especially in the area covered by the South-Wing WWTP, where the average consumption was 7 ± 2 g/1000inh/day. In the region served by the North-Wing WWTP, average uses of 21 ± 5 and 16 ± 2 g/1000inh/day were calculated for the Carnival holiday and for the subsequent period, respectively. Unlike cocaine, cannabis use in Brasilia was lower than that reported in several other regions, such as Western Kentucky—US (62 and 81 g/1000inh/day in two communities) (Foppe et al., 2018), Fort de France—Martinique (38 g/1000inh/day) (Devault et al., 2014), Barcelona—Spain (38 g/1000inh/day aging 15–64) (Mastroianni et al., 2017).

Due to the low excretion of the metabolite used in the back-calculation for cannabis, consumption data are often reported in terms of THC-COOH loads. Therefore, in the present work, average THC-COOH loads for the regions served by South-Wing and North-Wing WWTPs were 38 ± 11 and 99 ± 24 mg/1000inh/day, respectively. Comparing with other regions, THC-COOH loads were lower than in Amsterdam—Netherlands (192 mg/1000inh/day), Paris—France (124 mg/1000inh/day) (Thomas et al., 2012), Innsbruck—Austria (109 mg/1000inh/day) (Reinstadler et al., 2021), and more similar to Bogota—Colombia (33 mg/1000inh/day), Medellin—Colombia (47 mg/1000inh/day) (Bijlsma et al., 2016), and Petržalka—Slovakia (35 mg/1000inh/day) (Mackuľak et al., 2014).

According to the most recent National Survey on Drug Use by the Brazilian Population, (FIOCRUZ, 2017), prevalence of cocaine and cannabis consumption was 3.1 and 7.7% respectively. These data corroborate the higher relative incidence of the per capita consumption of cannabis and confirm that WBE is a consolidated strategy for estimating drug use and abuse, producing responses in agreement with those obtained by other strategies.

One should also bear in mind that WBE data usually provides results for a drug consumed as a 100% purity product and do not consider the real composition of the drug purchased on the streets and actually consumed by the user. From a law enforcement perspective, it is mandatory to have up-to-date information on the actual composition of drugs to convert WBE estimates into information that helps investigators assess how much of each drug has been consumed and trafficked. This issue has been raised in previous works, notably for cocaine (Maldaner et al., 2012; Ort et al., 2014; Sodré et al., 2018). However, there is still no consensus in the WBE literature regarding the terms and units used to express the estimation of drug consumption, especially cannabis.

Uncertainties and Limitations

As with other estimates, data collected using WBE are accompanied by uncertainties and limitations. They can be related to the different steps of the analytical sequence as well as to the parameters used in the back-calculation. Sampling uncertainties have been minimized with composite samples obtained by automated refrigerated samplers programmed to collect flow or time-proportional aliquots during 24 h.

Errors in chemical analysis are partially addressed through the use of deuterated internal standards as surrogate. During sampling, transport, storage and sample preparation, the stability of biomarkers is a matter of concern and has been addressed elsewhere (da Silva et al., 2018; Sodré et al., 2018). Briefly, benzoylecgonine is considered a relatively stable biomarker, while concentrations of cocaine, cocaethylene and carboxi-THC may decrease over time, specially at ambient temperatures (van Nuijs et al., 2012; Bisceglia and Lippa, 2014; Devault et al., 2017). Other uncertainties include assessing the wastewater volumetric flow and population variations related to the regions covered by the ETEs, especially during the carnival period. In the literature, strategies to addresses these uncertainties include using a high-frequency flow-proportional sampling strategy coupled to conscious calibration of flowmeter sensors (Lai et al., 2011; Subedi, 2019) and the monitoring of (bio)markers associated with the population such as caffeine, nicotine, ammonia and BOD, as well as the use of mobile phone networks and population censuses (Lai et al., 2011, 2015; Been et al., 2014; Senta et al., 2015; Rico et al., 2017; Thomas et al., 2017; Tscharke et al., 2019).

Despite the uncertainties, WBE is a well-established and widely used strategy to complement estimates produced by classical methods, which are also surrounded by uncertainties. It is worth mentioning that the WBE provides anonymous and objective answers, not only about drug consumption, but also about the spatiotemporal exposure of communities to different chemical and biological hazardous substances, and with relatively low costs, considering the size of the investigated population.

Conclusion

The findings obtained confirm that the use of drugs is directly related to social and special events since the consumption of cocaine and cannabis increased during the Carnival holyday. Due to the difference in the young population served by the WWTPs, was noted higher consumption of cannabis and cocaine in the administrative region of North-Wing. While for cannabis the consumption showed relatively constant throughout the post Carnival days, cocaine had its consumption profile significatively decreased after Carnival, indicating its recreational use, usually on weekends or in social events. This work shows that WBE is a consolidated strategy to estimate illicit drug use, producing near real-time information and allowing dynamic investigations concerning the temporal evolution of consumption.

Data Availability Statement

The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding authors.

Author Contributions

FS was responsible for writing the original manuscript, data curation, conceptualization, project management and student supervision; DF was in charge of visualizing, producing and processing the data and writing the first original draft; DA was responsible for writing, reviewing and editing the original manuscript; and AM was in charge of data curation, project management, student supervision and reviewing the original manuscript.

Funding

This work was supported by the Federal District Research Foundation (FAPDF) under Grant 19300000121/2019-13; the Brazilian National Council for Scientific and Technological Development (CNPq) under Grant 429858/2018-3; the National Institute of Advanced Analytical Science and Technology (INCTAA) under Grant 465768/2014-8, and the Ministry of Justice and Public Security under Grant TED/UnB/SENAD 04/2020.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s Note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Acknowledgments

The authors acknowledge the Environmental Sanitation Company of the Federal District (CAESB) and its employees, especially Ana Maria do Carmo Mota, for their support in obtaining the samples.

References

Abbott, K. L., Flannery, P. C., Gill, K. S., Boothe, D. M., Dhanasekaran, M., Mani, S., et al. (2020). Adverse Pharmacokinetic Interactions between Illicit Substances and Clinical Drugs. Drug Metab. Rev. 52, 44–65. doi:10.1080/03602532.2019.1697283

PubMed Abstract | CrossRef Full Text | Google Scholar

Ahmed, W., Tscharke, B., Bertsch, P. M., Bibby, K., Bivins, A., Choi, P., et al. (2021). SARS-CoV-2 RNA Monitoring in Wastewater as a Potential Early Warning System for COVID-19 Transmission in the Community: A Temporal Case Study. Sci. Total Environ. 761, 144216. doi:10.1016/j.scitotenv.2020.144216

PubMed Abstract | CrossRef Full Text | Google Scholar

Asicioglu, F., Kuloglu Genc, M., Tekin Bulbul, T., Yayla, M., Simsek, S., Adioren, C., et al. (2021). Investigation of Temporal Illicit Drugs, Alcohol and Tobacco Trends in Istanbul City: Wastewater Analysis of 14 Treatment Plants. Water Res. 190, 116729. doi:10.1016/j.watres.2020.116729

PubMed Abstract | CrossRef Full Text | Google Scholar

Been, F., Rossi, L., Ort, C., Rudaz, S., Delémont, O., Esseiva, P., et al. (2014). Population Normalization with Ammonium in Wastewater-Based Epidemiology: Application to Illicit Drug Monitoring. Environ. Sci. Technol. 48, 8162–8169. doi:10.1021/es5008388

PubMed Abstract | CrossRef Full Text | Google Scholar

Bijlsma, L., Botero-Coy, A. M., Rincón, R. J., Peñuela, G. A., and Hernández, F. (2016). Estimation of Illicit Drug Use in the Main Cities of Colombia by Means of Urban Wastewater Analysis. Sci. Total Environ. 565, 984–993. doi:10.1016/j.scitotenv.2016.05.078

PubMed Abstract | CrossRef Full Text | Google Scholar

Bijlsma, L., Celma, A., Castiglioni, S., Salgueiro-González, N., Bou-Iserte, L., Baz-Lomba, J. A., et al. (2020). Monitoring Psychoactive Substance Use at Six European Festivals through Wastewater and Pooled Urine Analysis. Sci. Total Environ. 725, 138376. doi:10.1016/j.scitotenv.2020.138376

PubMed Abstract | CrossRef Full Text | Google Scholar

Bijlsma, L., Picó, Y., Andreu, V., Celma, A., Estévez-Danta, A., González-Mariño, I., et al. (2021). The Embodiment of Wastewater Data for the Estimation of Illicit Drug Consumption in Spain. Sci. Total Environ. 772, 144794. doi:10.1016/j.scitotenv.2020.144794

PubMed Abstract | CrossRef Full Text | Google Scholar

Bisceglia, K. J., and Lippa, K. A. (2014). Stability of Cocaine and its Metabolites in Municipal Wastewater - the Case for Using Metabolite Consolidation to Monitor Cocaine Utilization. Environ. Sci. Pollut. Res. 21, 4453–4460. doi:10.1007/s11356-013-2403-5

CrossRef Full Text | Google Scholar

Cami, J., Farré, M., González, M. L., Segura, J., and de la Torre, R. (1998). “Cocaine Metabolism in Humans after Use of Alcohol Clinical and Research Implications,” in Recent Developments in Alcoholism: The Consequences of Alcoholism Medical Neuropsychiatric Economic Cross-Cultural (Boston, MA: Springer US), 437–455. doi:10.1007/0-306-47148-5_22

CrossRef Full Text | Google Scholar

Castiglioni, S., Bijlsma, L., Covaci, A., Emke, E., Hernández, F., Reid, M., et al. (2013). Evaluation of Uncertainties Associated with the Determination of Community Drug Use through the Measurement of Sewage Drug Biomarkers. Environ. Sci. Technol. 47, 1452–1460. doi:10.1021/es302722f

PubMed Abstract | CrossRef Full Text | Google Scholar

Causanilles, A., Baz-Lomba, J. A., Burgard, D. A., Emke, E., González-Mariño, I., Krizman-Matasic, I., et al. (2017a). Improving Wastewater-Based Epidemiology to Estimate Cannabis Use: Focus on the Initial Aspects of the Analytical Procedure. Anal. Chim. Acta 988, 27–33. doi:10.1016/j.aca.2017.08.011

PubMed Abstract | CrossRef Full Text | Google Scholar

Causanilles, A., Ruepert, C., Ibáñez, M., Emke, E., Hernández, F., and de Voogt, P. (2017b). Occurrence and Fate of Illicit Drugs and Pharmaceuticals in Wastewater from Two Wastewater Treatment Plants in Costa Rica. Sci. Total Environ. 599-600, 98–107. doi:10.1016/j.scitotenv.2017.04.202

CrossRef Full Text | Google Scholar

Celma, A., Sancho, J. V., Salgueiro-González, N., Castiglioni, S., Zuccato, E., Hernández, F., et al. (2019). Simultaneous Determination of New Psychoactive Substances and Illicit Drugs in Sewage: Potential of Micro-liquid Chromatography Tandem Mass Spectrometry in Wastewater-Based Epidemiology. J. Chromatogr. A 1602, 300–309. doi:10.1016/j.chroma.2019.05.051

PubMed Abstract | CrossRef Full Text | Google Scholar

Choi, P. M., Tscharke, B. J., Donner, E., O'Brien, J. W., Grant, S. C., Kaserzon, S. L., et al. (2018). Wastewater-based Epidemiology Biomarkers: Past, Present and Future. TrAC Trends Anal. Chem. 105, 453–469. doi:10.1016/j.trac.2018.06.004

CrossRef Full Text | Google Scholar

Choi, P. M., Tscharke, B., Samanipour, S., Hall, W. D., Gartner, C. E., Mueller, J. F., et al. (2019). Social, Demographic, and Economic Correlates of Food and Chemical Consumption Measured by Wastewater-Based Epidemiology. Proc. Natl. Acad. Sci. U.S.A. 116, 21864–21873. doi:10.1073/pnas.1910242116

PubMed Abstract | CrossRef Full Text | Google Scholar

CODEPLAN (2016). The Youth Profile of the Federal District. An Analysis of Data from the 2015/2016 District Household Sample Survey [In Portuguese]. Brasília. Available at: https://www.codeplan.df.gov.br/wp-content/uploads/2018/02/O-Perfil-da-Juventude-do-Distrito-Federal-Uma-análise-dos-dados-da-PDAD-2015-2016.pdf.

Google Scholar

Cruz-Cruz, C., Yargeau, V., Vidaña-Perez, D., Schilmann, A., Pineda, M. A., Lobato, M., et al. (2021). Opioids, Stimulants, and Depressant Drugs in Fifteen Mexican Cities: A Wastewater-Based Epidemiological Study. Int. J. Drug Policy 88, 103027. doi:10.1016/j.drugpo.2020.103027

PubMed Abstract | CrossRef Full Text | Google Scholar

da Silva, K. M., Quintana, J. B., González-Mariño, I., Rodil, R., Gallassi, A. D., Arantes, L. C., et al. (2018). Assessing Cocaine Use Patterns in the Brazilian Capital by Wastewater-Based Epidemiology. Int. J. Environ. Anal. Chem. 98, 1370–1387. doi:10.1080/03067319.2018.1554743

CrossRef Full Text | Google Scholar

Daglioglu, N., Guzel, E. Y., Atasoy, A., and Gören, İ. E. (2021). Comparison of Community Illicit Drug Use in 11 Cities of Turkey through Wastewater-Based Epidemiology. Environ. Sci. Pollut. Res. 28, 15076–15089. doi:10.1007/s11356-020-11404-9

CrossRef Full Text | Google Scholar

Damien, D. A., Thomas, N., Hélène, P., Sara, K., and Yves, L. (2014). First evaluation of illicit and licit drug consumption based on wastewater analysis in Fort de France urban area (Martinique, Caribbean), a transit area for drug smuggling. Sci. Total Environ. 490, 970–978. doi:10.1016/j.scitotenv.2014.05.090

PubMed Abstract | CrossRef Full Text | Google Scholar

Dázio, E. M. R., Zago, M. M. F., and Fava, S. M. C. L. (2016). Use of Alcohol and Other Drugs Among Male University Students and its Meanings. Rev. Esc. Enferm. Usp. 50, 785–791. doi:10.1590/S0080-623420160000600011

PubMed Abstract | CrossRef Full Text | Google Scholar

Devault, D. A., Lévi, Y., and Karolak, S. (2017). Applying Sewage Epidemiology Approach to Estimate Illicit Drug Consumption in a Tropical Context: Bias Related to Sewage Temperature and pH. Sci. Total Environ. 584-585 (585), 252–258. doi:10.1016/j.scitotenv.2017.01.114

PubMed Abstract | CrossRef Full Text | Google Scholar

Devault, D. A., Peyré, A., Jaupitre, O., Daveluy, A., and Karolak, S. (2020). The Effect of the Music Day Event on Community Drug Use. Forensic Sci. Int. 309, 110226. doi:10.1016/j.forsciint.2020.110226

PubMed Abstract | CrossRef Full Text | Google Scholar

FIOCRUZ (2017). in 3rd National Survey on Drug Use by the Brazilian Population. Editors F. I. P. M. Bastos, M. T. L. de Vasconcellos, R. B. De Boni, N. B. Dos Reis, and C. F. de S. C (Rio de Janeiro, Brazil. Available at: https://www.arca.fiocruz.br/handle/icict/34614).

Google Scholar

Foppe, K. S., Hammond-Weinberger, D. R., and Subedi, B. (2018). Estimation of the Consumption of Illicit Drugs during Special Events in Two Communities in Western Kentucky, USA Using Sewage Epidemiology. Sci. Total Environ. 633, 249–256. doi:10.1016/j.scitotenv.2018.03.175

PubMed Abstract | CrossRef Full Text | Google Scholar

Gatidou, G., Kinyua, J., van Nuijs, A. L. N., Gracia-Lor, E., Castiglioni, S., Covaci, A., et al. (2016). Drugs of Abuse and Alcohol Consumption Among Different Groups of Population on the Greek Island of Lesvos through Sewage-Based Epidemiology. Sci. Total Environ. 563-564, 633–640. doi:10.1016/j.scitotenv.2016.04.130

PubMed Abstract | CrossRef Full Text | Google Scholar

González‐Mariño, I., Estévez‐Danta, A., Rodil, R., Da Silva, K. M., Sodré, F. F., Cela, R., et al. (2019). Profiling Cocaine Residues and Pyrolytic Products in Wastewater by Mixed‐mode Liquid Chromatography-Tandem Mass Spectrometry. Drug Test. Anal. 11, 1018–1027. doi:10.1002/dta.2590

PubMed Abstract | CrossRef Full Text | Google Scholar

Gracia-Lor, E., Castiglioni, S., Bade, R., Been, F., Castrignanò, E., Covaci, A., et al. (2017). Measuring Biomarkers in Wastewater as a New Source of Epidemiological Information: Current State and Future Perspectives. Environ. Int. 99, 131–150. doi:10.1016/j.envint.2016.12.016

PubMed Abstract | CrossRef Full Text | Google Scholar

Gracia-Lor, E., Zuccato, E., and Castiglioni, S. (2016). Refining Correction Factors for Back-Calculation of Illicit Drug Use. Sci. Total Environ. 573, 1648–1659. doi:10.1016/j.scitotenv.2016.09.179

PubMed Abstract | CrossRef Full Text | Google Scholar

Harris, D. S., Everhart, E. T., Mendelson, J., and Jones, R. T. (2003). The Pharmacology of Cocaethylene in Humans Following Cocaine and Ethanol Administration. Drug Alcohol Dependence 72, 169–182. doi:10.1016/S0376-8716(03)00200-X

PubMed Abstract | CrossRef Full Text | Google Scholar

Herbst, E. D., Harris, D. S., Everhart, E. T., Mendelson, J., Jacob, P., and Jones, R. T. (2011). Cocaethylene Formation Following Ethanol and Cocaine Administration by Different Routes. Exp. Clin. Psychopharmacol. 19, 95–104. doi:10.1037/a0022950

PubMed Abstract | CrossRef Full Text | Google Scholar

Herbst, E. D., Harris, D. S., Everhart, E. T., Mendelson, J., Jacob, P., and Jones, R. T. (2017). Cocaethylene Formation Following Ethanol and Cocaine Administration by Different Routes. Exp. Clin. Psychopharmacol. 19, 95–104. doi:10.1037/a0022950

CrossRef Full Text | Google Scholar

Huerta-Fontela, M., Galceran, M. T., and Ventura, F. (2008). Stimulatory Drugs of Abuse in Surface Waters and Their Removal in a Conventional Drinking Water Treatment Plant. Environ. Sci. Technol. 42, 6809–6816. doi:10.1021/es800768h

PubMed Abstract | CrossRef Full Text | Google Scholar

Isenschmid, D. S. (2020). “Cocaine,” in Principles of Forensic Toxicology. Editors B. S. Levine, and S. Kerrigan (Cham: Springer Nature Switzerland AG), 371–387. doi:10.1007/978-3-030-42917-1_23

CrossRef Full Text | Google Scholar

Kankaanpää, A., Ariniemi, K., Heinonen, M., Kuoppasalmi, K., and Gunnar, T. (2016). Current Trends in Finnish Drug Abuse: Wastewater Based Epidemiology Combined with Other National Indicators. Sci. Total Environ. 568, 864–874. doi:10.1016/j.scitotenv.2016.06.060

PubMed Abstract | CrossRef Full Text | Google Scholar

Kuloglu Genc, M., Mercan, S., Yayla, M., Tekin Bulbul, T., Adioren, C., Simsek, S. Z., et al. (2021). Monitoring Geographical Differences in Illicit Drugs, Alcohol, and Tobacco Consumption via Wastewater-Based Epidemiology: Six Major Cities in Turkey. Sci. Total Environ. 797, 149156. doi:10.1016/j.scitotenv.2021.149156

PubMed Abstract | CrossRef Full Text | Google Scholar

Lai, F. Y., Anuj, S., Bruno, R., Carter, S., Gartner, C., Hall, W., et al. (2015). Systematic and Day-To-Day Effects of Chemical-Derived Population Estimates on Wastewater-Based Drug Epidemiology. Environ. Sci. Technol. 49, 999–1008. doi:10.1021/es503474d

PubMed Abstract | CrossRef Full Text | Google Scholar

Lai, F. Y., Bruno, R., Hall, W., Gartner, C., Ort, C., Kirkbride, P., et al. (2013a). Profiles of Illicit Drug Use during Annual Key Holiday and Control Periods in Australia: Wastewater Analysis in an Urban, a Semi-rural and a Vacation Area. Addiction 108, 556–565. doi:10.1111/add.12006

PubMed Abstract | CrossRef Full Text | Google Scholar

Lai, F. Y., Ort, C., Gartner, C., Carter, S., Prichard, J., Kirkbride, P., et al. (2011). Refining the Estimation of Illicit Drug Consumptions from Wastewater Analysis: Co-analysis of Prescription Pharmaceuticals and Uncertainty Assessment. Water Res. 45, 4437–4448. doi:10.1016/j.watres.2011.05.042

PubMed Abstract | CrossRef Full Text | Google Scholar

Lai, F. Y., Thai, P. K., O'Brien, J., Gartner, C., Bruno, R., Kele, B., et al. (2013b). Using Quantitative Wastewater Analysis to Measure Daily Usage of Conventional and Emerging Illicit Drugs at an Annual Music Festival. Drug Alcohol Rev. 32, 594–602. doi:10.1111/dar.12061

CrossRef Full Text | Google Scholar

Laranjeira, R., Madruga, C. S., Pinsky, I., Caetano, R., and Mitsuhiro, S. S. (2014). Segundo Levantamento Nacional de Álcool e Drogas (LENAD) - 2012. São Paulo: Inst. Nac. Ciência e Tecnol. para Políticas Públicas Álcool e Outras Drog, 85. Available at: https://inpad.org.br/wp-content/uploads/2014/03/Lenad-II-Relatório.pdf.

Google Scholar

Lorenzo, M., and Picó, Y. (2019). Wastewater-based Epidemiology: Current Status and Future Prospects. Curr. Opin. Environ. Sci. Health 9, 77–84. doi:10.1016/j.coesh.2019.05.007

CrossRef Full Text | Google Scholar

Löve, A. S. C., Ásgrímsson, V., and Ólafsdóttir, K. (2022). Illicit Drug Use in Reykjavik by Wastewater-Based Epidemiology. Sci. Total Environ. 803, 149795. doi:10.1016/j.scitotenv.2021.149795

PubMed Abstract | CrossRef Full Text | Google Scholar

Mackuľak, T., Brandeburová, P., Grenčíková, A., Bodík, I., Staňová, A. V., Golovko, O., et al. (2019). Music Festivals and Drugs: Wastewater Analysis. Sci. Total Environ. 659, 326–334. doi:10.1016/j.scitotenv.2018.12.275

PubMed Abstract | CrossRef Full Text | Google Scholar

Mackuľak, T., Škubák, J., Grabic, R., Ryba, J., Birošová, L., Fedorova, G., et al. (2014). National Study of Illicit Drug Use in Slovakia Based on Wastewater Analysis. Sci. Total Environ. 494-495, 158–165. doi:10.1016/j.scitotenv.2014.06.089

PubMed Abstract | CrossRef Full Text | Google Scholar

Maldaner, A. O., Schmidt, L. L., Locatelli, M. A. F., Jardim, W. F., Sodré, F. F., Almeida, F. V., et al. (2012). Estimating Cocaine Consumption in the Brazilian Federal District (FD) by Sewage Analysis. J. Braz. Chem. Soc. 23, 861–867. doi:10.1590/S0103-50532012000500011

CrossRef Full Text | Google Scholar

Mastroianni, N., López-García, E., Postigo, C., Barceló, D., and López de Alda, M. (2017). Five-year Monitoring of 19 Illicit and Legal Substances of Abuse at the Inlet of a Wastewater Treatment Plant in Barcelona (NE Spain) and Estimation of Drug Consumption Patterns and Trends. Sci. Total Environ. 609, 916–926. doi:10.1016/j.scitotenv.2017.07.126

PubMed Abstract | CrossRef Full Text | Google Scholar

McCall, A.-K., Bade, R., Kinyua, J., Lai, F. Y., Thai, P. K., Covaci, A., et al. (2016). Critical Review on the Stability of Illicit Drugs in Sewers and Wastewater Samples. Water Res. 88, 933–947. doi:10.1016/j.watres.2015.10.040

PubMed Abstract | CrossRef Full Text | Google Scholar

Miraglia, P. (2015). “Drugs and Drug Trafficking in Brazil: Trends and Policies,” in Improving Global Drug Policy: Comparative Perspectives and UNGASS 2016. Editors V. Felbab-Brown,, and H. Trinkunas (Washington: Brookings, 16. Available at: https://www.brookings.edu/wp-content/uploads/2016/07/miraglia-brazil-final.pdf.

Google Scholar

Montgomery, A. B., O'Rourke, C. E., and Subedi, B. (2021). Basketball and Drugs: Wastewater-Based Epidemiological Estimation of Discharged Drugs during Basketball Games in Kentucky. Sci. Total Environ. 752, 141712. doi:10.1016/j.scitotenv.2020.141712

PubMed Abstract | CrossRef Full Text | Google Scholar

Nefau, T., Karolak, S., Castillo, L., Boireau, V., and Levi, Y. (2013). Presence of Illicit Drugs and Metabolites in Influents and Effluents of 25 Sewage Water Treatment Plants and Map of Drug Consumption in France. Sci. Total Environ. 461-462, 712–722. doi:10.1016/j.scitotenv.2013.05.038

PubMed Abstract | CrossRef Full Text | Google Scholar

Ort, C., Nuijs, A. L. N., Berset, J. D., Bijlsma, L., Castiglioni, S., Covaci, A., et al. (2014). Spatial Differences and Temporal Changes in Illicit Drug Use in E Urope Quantified by Wastewater Analysis. Addiction 109, 1338–1352. doi:10.1111/add.12570

PubMed Abstract | CrossRef Full Text | Google Scholar

Pal, A., He, Y., Jekel, M., Reinhard, M., and Gin, K. Y.-H. (2014). Emerging Contaminants of Public Health Significance as Water Quality Indicator Compounds in the Urban Water Cycle. Environ. Int. 71, 46–62. doi:10.1016/j.envint.2014.05.025

PubMed Abstract | CrossRef Full Text | Google Scholar

Reinstadler, V., Ausweger, V., Grabher, A.-L., Kreidl, M., Huber, S., Grander, J., et al. (2021). Monitoring Drug Consumption in Innsbruck during Coronavirus Disease 2019 (COVID-19) Lockdown by Wastewater Analysis. Sci. Total Environ. 757, 144006. doi:10.1016/j.scitotenv.2020.144006

PubMed Abstract | CrossRef Full Text | Google Scholar

Rico, M., Andrés-Costa, M. J., and Picó, Y. (2017). Estimating Population Size in Wastewater-Based Epidemiology. Valencia Metropolitan Area as a Case Study. J. Hazard. Mater. 323, 156–165. doi:10.1016/j.jhazmat.2016.05.079

PubMed Abstract | CrossRef Full Text | Google Scholar

Rodríguez-Álvarez, T., Racamonde, I., González-Mariño, I., Borsotti, A., Rodil, R., Rodríguez, I., et al. (2015). Alcohol and Cocaine Co-consumption in Two European Cities Assessed by Wastewater Analysis. Sci. Total Environ. 536, 91–98. doi:10.1016/j.scitotenv.2015.07.016

PubMed Abstract | CrossRef Full Text | Google Scholar

Rushing, R., and Burgard, D. A. (2019). “Utilizing Wastewater-Based Epidemiology to Determine Temporal Trends in Illicit Stimulant Use in Seattle, Washington,”. Wastewater-Based Epidemiology: Estimation Of Community Consumption Of Drugs And Diets ACS Symposium Series. Editors B. Subedi, D. A. Burgard, and B. G. Loganathan (Washington: American Chemical Society), 155–166. doi:10.1021/bk-2019-1319.ch008

CrossRef Full Text | Google Scholar

Senta, I., Gracia-Lor, E., Borsotti, A., Zuccato, E., and Castiglioni, S. (2015). Wastewater Analysis to Monitor Use of Caffeine and Nicotine and Evaluation of Their Metabolites as Biomarkers for Population Size Assessment. Water Res. 74, 23–33. doi:10.1016/j.watres.2015.02.002

PubMed Abstract | CrossRef Full Text | Google Scholar

Senta, I., Krizman, I., Ahel, M., and Terzic, S. (2014). Assessment of Stability of Drug Biomarkers in Municipal Wastewater as a Factor Influencing the Estimation of Drug Consumption Using Sewage Epidemiology. Sci. Total Environ. 487, 659–665. doi:10.1016/j.scitotenv.2013.12.054

PubMed Abstract | CrossRef Full Text | Google Scholar

Shimomura, E. T., Jackson, G. F., and Paul, B. D. (2019). “Cocaine, Crack Cocaine, and Ethanol,” in Critical Issues in Alcohol and Drugs of Abuse Testing. Editor A. Dasgupta (Cambridge: Academic Press), 215–224. doi:10.1016/B978-0-12-815607-0.00017-4

CrossRef Full Text | Google Scholar

Sodré, F., Feitosa, R., Jardim, W., and Maldaner, A. (2018). Wastewater-based Epidemiology of Cocaine in the Brazilian Federal District: Spatial Distribution, Weekly Variation and Sample Preservation Strategies. J. Braz. Chem. Soc. 29, 2287–2298. doi:10.21577/0103-5053.20180105

CrossRef Full Text | Google Scholar

Sodré, F., Souza, G., Feitosa, R., Pereira, C., and Maldaner, A. (2017). Illicit Drugs, Metabolites and Adulterants in Wastewater: Monitoring Community Drug Abuse in the Brazilian Federal District during the 2014 Soccer World Cup. J. Braz. Chem. Soc. 28, 2146–2154. doi:10.21577/0103-5053.20170063

CrossRef Full Text | Google Scholar

Subedi, B. (2019). “Uncertainties Associated with Wastewater-Based Epidemiology for the Estimation of Community Consumption of Drugs,”. Wastewater-Based Epidemiology: Estimation Of Community Consumption Of Drugs And Diets ACS Symposium Series. Editors B. Subedi, D. A. Burgard, and B. G. Loganathan (Washington: American Chemical Society), 79–98. doi:10.1021/bk-2019-1319.ch004

CrossRef Full Text | Google Scholar

Thiebault, T., Fougère, L., Destandau, E., Réty, M., and Jacob, J. (2019). Impact of Meteorological and Social Events on Human-Excreted Contaminant Loads in Raw Wastewater: From Daily to Weekly Dynamics. Chemosphere 230, 107–116. doi:10.1016/j.chemosphere.2019.04.221

PubMed Abstract | CrossRef Full Text | Google Scholar

Thomas, K. V., Amador, A., Baz-Lomba, J. A., and Reid, M. (2017). Use of Mobile Device Data to Better Estimate Dynamic Population Size for Wastewater-Based Epidemiology. Environ. Sci. Technol. 51, 11363–11370. doi:10.1021/acs.est.7b02538

PubMed Abstract | CrossRef Full Text | Google Scholar

Thomas, K. V., Bijlsma, L., Castiglioni, S., Covaci, A., Emke, E., Grabic, R., et al. (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

PubMed Abstract | CrossRef Full Text | Google Scholar

Tscharke, B. J., Chen, C., Gerber, J. P., and White, J. M. (2016). Temporal Trends in Drug Use in Adelaide, South Australia by Wastewater Analysis. Sci. Total Environ. 565, 384–391. doi:10.1016/j.scitotenv.2016.04.183

PubMed Abstract | CrossRef Full Text | Google Scholar

Tscharke, B. J., O’Brien, J. W., Ort, C., Grant, S., Gerber, C., Bade, R., et al. (2019). Harnessing the Power of the Census: Characterizing Wastewater Treatment Plant Catchment Populations for Wastewater-Based Epidemiology. Environ. Sci. Technol. 53, 10303–10311. doi:10.1021/acs.est.9b03447

PubMed Abstract | CrossRef Full Text | Google Scholar

UNODC (2021). World Drug Report. Global Overview: Drug Demand, Drug Supply. Vienna: United Nations Office on Drugs and Crime. Available at: http://www.unodc.org/unodc/en/data-and-analysis/wdr2021.html.

Google Scholar

Van Havere, T., Vanderplasschen, W., Lammertyn, J., Broekaert, E., and Bellis, M. (2011). Drug Use and Nightlife: More Than Just Dance Music. Subst. Abuse Treat. Prev. Policy 6, 18. doi:10.1186/1747-597X-6-18

PubMed Abstract | CrossRef Full Text | Google Scholar

van Nuijs, A. L. N., Abdellati, K., Bervoets, L., Blust, R., Jorens, P. G., Neels, H., et al. (2012). The Stability of Illicit Drugs and Metabolites in Wastewater, an Important Issue for Sewage Epidemiology? J. Hazard. Mater. 239-240, 19–23. doi:10.1016/j.jhazmat.2012.04.030

PubMed Abstract | CrossRef Full Text | Google Scholar

van Nuijs, A. L. N., Pecceu, B., Theunis, L., Dubois, N., Charlier, C., Jorens, P. G., et al. (2009). Can Cocaine Use Be Evaluated through Analysis of Wastewater? A Nation-wide Approach Conducted in Belgium. Addiction 104, 734–741. doi:10.1111/j.1360-0443.2009.02523.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Verovšek, T., Krizman-Matasic, I., Heath, D., and Heath, E. (2020). Site- and Event-specific Wastewater-Based Epidemiology: Current Status and Future Perspectives. Trends Environ. Anal. Chem. 28, e00105. doi:10.1016/j.teac.2020.e00105

CrossRef Full Text | Google Scholar

Vosburg, S. K., Haney, M., Rubin, E., and Foltin, R. W. (2010). Using a Novel Alternative to Drug Choice in a Human Laboratory Model of a Cocaine Binge: A Game of Chance. Drug Alcohol Dependence 110, 144–150. doi:10.1016/j.drugalcdep.2010.02.015

PubMed Abstract | CrossRef Full Text | Google Scholar

Wilkins, C., Lai, F. Y., O'Brien, J., Thai, P., and Mueller, J. F. (2018). Comparing Methamphetamine, MDMA, Cocaine, Codeine and Methadone Use between the Auckland Region and Four Australian States Using Wastewater-Based Epidemiology (WBE). N. Z. Med. J. 131, 12–20.

Google Scholar

Zhang, X., Huang, R., Li, P., Ren, Y., Gao, J., Mueller, J. F., et al. (2019). Temporal Profile of Illicit Drug Consumption in Guangzhou, China Monitored by Wastewater-Based Epidemiology. Environ. Sci. Pollut. Res. 26, 23593–23602. doi:10.1007/s11356-019-05575-3

CrossRef Full Text | Google Scholar

Zuccato, E., Castiglioni, S., Senta, I., Borsotti, A., Genetti, B., Andreotti, A., et al. (2016). Population Surveys Compared with Wastewater Analysis for Monitoring Illicit Drug Consumption in Italy in 2010-2014. Drug Alcohol Dependence 161, 178–188. doi:10.1016/j.drugalcdep.2016.02.003

PubMed Abstract | CrossRef Full Text | Google Scholar

Zuccato, E., Chiabrando, C., Castiglioni, S., Bagnati, R., and Fanelli, R. (2008). Estimating Community Drug Abuse by Wastewater Analysis. Environ. Health Perspect. 116, 1027–1032. doi:10.1289/ehp.11022

PubMed Abstract | CrossRef Full Text | Google Scholar