Prevalence and risk assessment of antibiotics in riverine estuarine waters of Larut and Sangga Besar River, Perak

Antibiotics released into the environment through anthropogenic activities exert selective pressure, driving bacteria towards increasing antimicrobial resistance. The prevalence of antibiotics and the ecological risks posed in the riverine estuarine of Larut River and Sangga Besar River, which included wastewater effluents from hospital, zoo, and poultry slaughterhouse sources were investigated. Solid phase extraction (SPE) followed by high-performance liquid chromatography tandem mass chromatography (HPLC-MS/MS) were used to extract and quantify the antibiotic residues from 22 antibiotics belonging to six major antibiotic classes (sulfonamide, macrolide, fluoroquinolone, phenicol, trimethoprim, and tetracycline). Sixteen antibiotic residues were detected with concentrations ranging from limit of detection (LOD) to 1 262.3 ng/L. Fluoroquinolones and macrolides were the most frequently detected compounds. Erythromycin, clarithromycin, and ofloxacin detected in hospital and zoo effluents posed a high risk to algae while tetracycline had low to medium ecological risks toward all the relevant organisms from aquatic environments (algae, invertebrate Daphnia magna, and fish).

Automated summary

Antibiotics released into the environment through human activities were found in Larut River and Sangga Besar River, posing potential risks to the riverine estuarine ecosystem. Fluoroquinolones and macrolides were the most frequently detected antibiotic residues, with some posing high risks to algae.