Simultaneous Determination of Pharmaceuticals in the South African Environment Followed by the Health Risk Assessment

Abstract

The present work examined the occurrence of efavirenz, ibuprofen, naproxen, sulfamethoxazole, and trimethoprim in wastewater, sewage sludge, river water, estuaries, seawater, garden soil, and vegetables. This was achieved through the application of solid-phase extraction (SPE) and ultrasound-assisted solvent extraction (UASE) for sample preparation prior to liquid chromatographic analysis. The validity of these sample preparation techniques was confirmed by computing analyte recoveries after spiking the investigated matrices with mixed standards at 5 and 15 μg/L for aqueous samples and 5 and 15 ng/g for solid samples. In all cases, all the analytes were recovered within the acceptable range of 70–120%, except for sulfamethoxazole, which was recovered at 62% in wastewater influent and 56% in sludge due to the complexity of the matrices. The relative standard deviation across all the studied matrices was below 15%, indicating the precision of the analytical method. The sensitivity of the analytical method was investigated by determining method detection limits (MDL) and method quantification limits (MQL). The MDL and MQL ranged between 0.02–6.20 ng/L and 0.07–14.2 ng/L for aqueous samples and 0.08–8.36 ng/kg and 0.20–25.32 ng/kg for solid samples, respectively. The analytical method was then applied to determine the extent of pharmaceutical pollution in the aquatic environment of the Eastern Cape province. Wastewater and sewage sludge samples were highly contaminated with the targeted pharmaceuticals, with concentrations reaching 77 μg/L and 13.35 ng/g, respectively. The studied pharmaceuticals were detected in seawater samples, with ibuprofen at the highest concentration of 90 ng/L. The detected concentrations in seawater were found to pose a negligible risk to aquatic species. The studied vegetables were also contaminated, with a high detection of trimethoprim at 1501 ng/kg in spinach. In addition to the targeted pharmaceuticals, 108 other drugs were detected in the edible parts of vegetables. However, the health risks associated with the consumption of these pharmaceuticals-contaminated vegetables were found to be negligible. The overall findings of the present study provided invaluable insights into pharmaceutical pollution across various environmental matrices. The results highlighted the critical need to improve the maintenance and efficiency of wastewater treatment plants as they are major contributors to pharmaceutical pollution. Continuous disposal of pharmaceuticals into the environment could lead to increased concentrations, deteriorating the quality of freshwater, and promoting the emergence of antimicrobial resistance.