Pharmaceuticals in drinking water in suburban communities in Chengdu, China: potential risks on the human health

Water supplies have come under serious environmental stress in suburban communities in China due to developmental activities. A comprehensive study was carried out to investigate the occurrence of pharmaceutical compounds in county-level drinking water sources within Chengdu City. The solid-phase extraction combined with ultra-high performance liquid chromatography/tandem mass spectrometry was employed to analyze the residues of pharmaceuticals in the water sources for water supply in Chengdu. An internal standard calibration method was used to minimize the matrix effects. The results indicated that all 30 targeted pharmaceuticals were detected. Results showed that the total concentrations of pharmaceuticals at different points ranged from 16.56 to 257.5 ng/L. Ofloxacin, sulfamethoxazole, and lincomycin had relatively high detection rates with average concentrations of 15.28 ng/L, 8.92 ng/L, and 7.08 ng/L, respectively. Source analysis showed that domestic sewage, aquaculture wastewater, and medical wastewater were the main sources of the pharmaceuticals. Furthermore, concentrations were higher in summer than in spring and winter. Drinking water treatment plants (DWTPs) exhibit suboptimal removal performance of pharmaceuticals. In some waterworks, the pharmaceutical residues detected in the finished water are higher than those in the source water. The removal efficiency of trimethoprim and lincomycin was found to be relatively good. The risk quotient method was used to evaluate the health risk and ecological risk of pharmaceutical. Health risk assessments show that pharmaceuticals posed no threat to human health through the drinking water route, and even the OFL with the highest risk quotient is much less than 0.01. Ecological risk assessment showed that ofloxacin posed a medium-high risk to sensitive algae species. Sulfamethoxazole also posed a medium risk to algae in some water sources but no risk to fish. This work provided a scientific basis for pollution risk management and control of pharmaceuticals in the drinking water sources of Chengdu.