Antibiotic, Heavy Metal, and Biocide Concentrations in a Wastewater Treatment Plant and Its Receiving Water Body Exceed PNEC Limits: Potential for Antimicrobial Resistance Selective Pressure

• Published in: Antibiotics (Basel) Vol. 12; no. 7; p. 1166
• Main Authors: Chukwu, Kelechi B, Abafe, Ovokeroye A, Amoako, Daniel G, Essack, Sabiha Y, Abia, Akebe L K
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.07.2023; MDPI
• Subjects: antibiotic residues; Antibiotics; Antimicrobial agents; Antimicrobial resistance; Aquaculture; Benzalkonium chloride; Biocides; Downstream; Drug resistance; Drug resistance in microorganisms; Effluents; Environmental protection; environmental stressors; Heavy metals; High performance liquid chromatography; Liquid chromatography; Mass spectrometry; Mass spectroscopy; Metal concentrations; Neodymium; Penicillin; Pollutants; Publishing industry; Purification; Receiving waters; Sediments; selective pressure; Sewage; Sulfamethoxazole; Surface water; Tetracycline; Tetracyclines; Upstream; Wastewater discharges; Wastewater treatment; Wastewater treatment plants; Water analysis; Water bodies; Water sampling; Water treatment; Water treatment plants; South Africa; Netherlands; United States; Massachusetts; Africa; antibiotic residues; selective pressure; environmental stressors; antimicrobial resistance; aquatic environment; heavy metals; PNEC; biocides
• ISSN: 2079-6382; 2079-6382
• DOI: 10.3390/antibiotics12071166

Although the rise in antimicrobial resistance has been attributed mainly to the extensive and indiscriminate use of antimicrobials such as antibiotics and biocides in humans, animals and on plants, studies investigating the impact of this use on water environments in Africa are minimal. This study quantified selected antibiotics, heavy metals, and biocides in an urban wastewater treatment plant (WWTP) and its receiving water body in Kwazulu-Natal, South Africa, in the context of the predicted no-effect concentrations (PNEC) for the selection of antimicrobial resistance (AMR). Water samples were collected from the WWTP effluent discharge point and upstream and downstream from this point. Heavy metals were identified and quantified using the United States Environmental Protection Agency (US EPA) method 200.7. Biocides and antibiotic residues were determined using validated ultra-high-performance liquid chromatography with tandem mass spectrometry-based methods. The overall highest mean antibiotic, metal and biocide concentrations were observed for sulfamethoxazole (286.180 µg/L), neodymium (Nd; 27.734 mg/L), and benzalkonium chloride (BAC 12) (7.805 µg/L), respectively. In decreasing order per sampling site, the pollutant concentrations were effluent > downstream > upstream. This implies that the WWTP significantly contributed to the observed pollution in the receiving water. Furthermore, most of the pollutants measured recorded values exceeding the recommended predicted no-effect concentration (PNEC) values, suggesting that the microbes in such water environments were at risk of developing resistance due to the selection pressure exerted by these antimicrobials. Further studies are required to establish such a relationship.