Background and aims
Wastewater‐based epidemiology is an additional indicator of drug use that is gaining reliability to complement the current established panel of indicators. The aims of this study were to: (i) assess spatial and temporal trends of population‐normalized mass loads of benzoylecgonine, amphetamine, methamphetamine and 3,4‐methylenedioxymethamphetamine (MDMA) in raw wastewater over 7 years (2011–17); (ii) address overall drug use by estimating the average number of combined doses consumed per day in each city; and (iii) compare these with existing prevalence and seizure data.
Design
Analysis of daily raw wastewater composite samples collected over 1 week per year from 2011 to 2017.
Setting and Participants
Catchment areas of 143 wastewater treatment plants in 120 cities in 37 countries.
Measurements
Parent substances (amphetamine, methamphetamine and MDMA) and the metabolites of cocaine (benzoylecgonine) and of Δ9‐tetrahydrocannabinol (11‐nor‐9‐carboxy‐Δ9‐tetrahydrocannabinol) were measured in wastewater using liquid chromatography–tandem mass spectrometry. Daily mass loads (mg/day) were normalized to catchment population (mg/1000 people/day) and converted to the number of combined doses consumed per day. Spatial differences were assessed world‐wide, and temporal trends were discerned at European level by comparing 2011–13 drug loads versus 2014–17 loads.
Findings
Benzoylecgonine was the stimulant metabolite detected at higher loads in southern and western Europe, and amphetamine, MDMA and methamphetamine in East and North–Central Europe. In other continents, methamphetamine showed the highest levels in the United States and Australia and benzoylecgonine in South America. During the reporting period, benzoylecgonine loads increased in general across Europe, amphetamine and methamphetamine levels fluctuated and MDMA underwent an intermittent upsurge.
Conclusions
The analysis of wastewater to quantify drug loads provides near real‐time drug use estimates that globally correspond to prevalence and seizure data.
A simple vortex-assisted liquid-liquid microextraction protocol followed by GC-MS is proposed for the determination of 12 organophosphate pesticides residues in environmental water samples and wines. The sample pretreatment employs the usage of low-density organic solvent. The parameters affecting the extraction efficiency (type and volume of organic extraction solvent, sample pH, ionic strength, extraction time, and centrifugation speed) were carefully examined. A mild emulsification process was involved by the addition of 40 μL toluene into 10 mL sample followed by sequential vortex-based agitation and manual shaking for 3 min. Following the extraction, the pesticide-rich organic solvent was recovered by centrifugation at 4000 rpm for 5 min. A fraction of the floated toluene was then collected and analyzed by GC-MS in SIM mode. Under the optimized conditions, the enrichment factor ranged between 65 and 389. Satisfactory linearity was observed for all pesticides tested with correlation coefficients higher than 0.9945 while the LODs were in the range of 2-11 ng L(-1) . The main advantages of the proposed method are the simplicity of operation, rapidity, low cost, and high sensitivity.
Laboratory studies were conducted to determine the effect of pH and redox conditions, as well as the effect of Fe, Mn, Ca, Al, and organic matter, on the release of ortho-phosphates in lake sediments taken from Lakes Koronia and Volvi (Northern Greece). Results were evaluated in combination with experiments to determine P fractionation in the sediment. The study revealed the major effect of redox potential and pH on the release of P from lake sediments. Both lakes showed increased release rates under reductive conditions and high pH values. The fractionation experiments revealed increased mobility of the reductive P fraction as well as of the NaOH-P fraction, indicating participation of both fractions in the overall release of sediment-bound P, depending on the prevailing environmental conditions. The results were assessed in combination with the release patterns of Fe, Mn, Ca, Al, and organic matter, enabling the identification of more specific processes of P release for each lake. The basic release patterns included the redox induced reductive dissolution of P-bearing metal oxides and the competitive exchange of phosphate anions with OH- at high pH values. The formation of an oxidized surface microlayer under oxic conditions acted as a protective film, preventing further P release from the sediments of Lake Volvi, while sediments from Lake Koronia exhibited a continuous and increased tendency to release P under various physicochemical conditions, acting as a constant source of internal P loading.
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