Occurrence profiling, risk assessment, and correlations of antimicrobials in surface water and groundwater systems in Southwest Nigeria

The presence of antimicrobials in water has grown into a major global health concern. This study thus focused on the presence, ecological implications, and potential health risks associated with nine antimicrobials: five antibiotics (ampicillin, chloramphenicol, ciprofloxacin, metronidazole, and tetracycline) and four parabens (methylparaben, ethylparaben, propylparaben, and butylparaben) in surface water and groundwater samples collected from three Southwestern States in Nigeria (Osun, Oyo, and Lagos States). These antimicrobials were widely detected across the three States with ciprofloxacin being the most dominant having maximum average concentrations of 189 mu g L-1 and 319 mu g L-1 in surface water and groundwater respectively. The range of average concentrations of antibiotics in surface water are 47.3-235 mu g L-1 (Osun), 27.9-166 mu g L-1 (Oyo) and 52.1-159 mu g L-1 (Lagos). For groundwater, it is 35.3-180 mu g L-1 (Osun), 26.5-181 mu g L-1 (Oyo) and 32.3-319 mu g L-1 (Lagos). The average concentrations of all parabens were 32.4-153 mu g L-1, 53.4-80.1 mu g L-1, and 83.2-132 mu g L-1 for surface water and 46.7-55.7 mu g L-1, 53-117 mu g L-1, and 62.4-118 mu g L-1 for groundwater in Osun, Oyo, and Lagos States respectively. Methylparaben was most frequently detected paraben with average concentrations of 153 mu g L-1 and 117 mu g L-1 in surface water and groundwater respectively. The measured environmental concentrations of these antimicrobials pose a significant ecological risk while those of ciprofloxacin and ampicillin pose a high health risk to all population groups studied. The average concentrations of antibiotics investigated in this study exceeded their threshold values for Predicted No-Effect Concentrations (PNEC) associated with resistance selection, except for tetracycline. In this study, nine PPCPs were widely detected in surface and groundwater. Ciprofloxacin and methylparaben were the most dominant antibiotic and paraben compounds, respectively, with ciprofloxacin posing a high health risk to all population groups.