Recent research shows that residues of licit and illicit drugs often occur in surface waters, while their presence in groundwaters is less studied. The behavioural and biological effects of licit and illicit drugs on humans are well known, however, their impact on non-target aquatic organisms remains to be examined. In this work, residues of licit (nicotine), illicit (cocaine, THC – tetrahydrocannabinol, amphetamine, and MDMA – 3,4-methylenedioxymethamphetamine) drugs and medications of abuse (morphine and methadone) were determined in samples of Slovene surface waters and groundwaters. Their potential influence on green algae was studied in silico using ECOSAR software and in vivo using an algal growth inhibition test. Drug residues were extracted using solid-phase extraction followed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Concentrations of drug residues measured in surface waters were compared to predicted effect concentrations obtained by ECOSAR. The algal growth inhibition test was performed by adding green algae (Chlamydomonas reinhardtii) and drug residues (individually or in a mixture) to a standard medium (tris acetate phosphate, TAP) at 1 mg/L. Flow cytometry was then used to measure cell density every 24 h over 72 h or 240 h intervals. After extracting the samples using supported-liquid extraction or liquid-liquid extraction, LC-MS/MS was used to determine the concentration of analytes in the TAP medium.
The results revealed the presence of the studied analytes in surface water samples in the ng/L concentration range, except for amphetamine and THC-COOH which were below the detection limit. In groundwater samples, only nicotine and cocaine residues were determined (ng/L range), with cocaine detected in five samples below the limit of quantification. In both surface water and groundwater, measured concentrations were lower than the effect concentrations predicted by ECOSAR (mg/L range). However, calculated risk quotients indicated that nicotine, EDDP (2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine) and MDMA could pose acute or even chronic risks to aquatic organisms at detected environmental concentrations in surface waters. Although the concentrations of analytes in the TAP medium in the algal growth inhibition test were high (1 mg/L) and, in some cases (morphine, EDDP and THC-COOH), comparable with ECOSAR predicted effect concentrations, none of the tested compounds showed an effect on the growth of green algae. However, we should not disregard the fact that in the environment, compounds can interact with other (toxic) compounds and cause an impact on aquatic organisms due to synergistic, antagonistic or additive effects.
|
