Drugs of abuse distribuiton in Turia River based on geographic information and ecotoxicological assessment

Abstract

The aim of this study establishes the influence and the effects of the human pressure in a typical Mediterranean River Basin to determine accurately the point sources of contamination through an environmental forensics methodology. A total of 42 drugs of abuse and metabolites were analysed in surface water samples collected from 22 sampling sites in 2012 and 31 in 2013 distributed along the river. Analysis of the target illicit drugs was performed using solid phase extraction and liquid chromatography coupled mass spectrometry (SPE-LC-MS/MS). To determine spatial incidence of drugs of abuse, analytical results of target compounds were georeferenced and integrated into a geographical information systems (GIS). Ecotoxicological risk of drugs of abuse detected in the Turia River was evaluated by calculating risk quotient (RQ). In 2012, 3,4-methylenedioxymethamphetamine (MDMA) and 4-methoxyphencyclidine (4-MeO-PCP) were detected in one sampling point at a concentration of 22.8 and 37.6 ng/L, respectively. In 2013, 4-MeO-PCP was detected in a different sampling point of 2012 at a concentration of 7.55 ng/L and ecgonine methyl ester (ECME) was detected at a concentration of 15.03 ng/L. Bufotenine (BUF), methadone (MET) and p-methoxyamphetamine (PMA) were found out in 3 or 4 sampling points at concentrations < 70 ng/L in 2012. Ephedrine (EPH) and codeine (COD) were detected in 3 sampling points at average concentrations of 11.6 ng/L for EPH and 91.3 ng/L for COD in 2013. The compound detected more frequently along the river was benzoylecgonine (BECG), a cocaine metabolite, with an average concentration of 25.4 (2.91–76.8) ng/L in 2012. In 2013, MDMA was detected in 5 sampling points (mean of 4.67 ng/L, ranged from 2.34 to 7.21 ng/L) and BECG and MET were detected in a total of 8 and 7 sampling points, respectively, each one at a mean concentration of 14.02 (1.83–12.7) ng/L for BECG and 11.4 (2.29–40.1) ng/L for MET. GIS provided the spatial incidence of drugs of abuse along the Turia River Basin. The occurrence of these drugs is higher near of the cities with highest population densities according to the descriptive model of territorial presence. Compounds used as drugs of abuse and prescribed as pharmaceuticals (MET, COD and EPH) were mostly detected in Valencia city and its metropolitan area where most hospitals are located. Although risk assessment showed low ecotoxicological hazard, further studies are also needed in order to assess long term toxicity.