Abstract
This study evaluated the environmental and public health implications of pharmaceutical wastewater discharged in Kano, Kaduna, Sokoto, and Maiduguri, Northern Nigeria. Physicochemical parameters, pharmaceutical residues, heavy metals, bacteriological quality, antibiotic resistance, and human health risk indices were investigated in wastewater collected from hospitals, pharmaceutical premises, and receiving drainage channels. Wastewater quality was generally poor in all the studied cities. Electrical conductivity ranged from 1186 ± 36 to 1502 ± 55 µS/cm, while biochemical oxygen demand and chemical oxygen demand reached 70.1 ± 4.5 mg/L and 151.4 ± 8.1 mg/L, respectively, particularly in Maiduguri. Dissolved oxygen remained below the recommended threshold in all locations. Pharmaceutical residues, including paracetamol, diclofenac, ibuprofen, ciprofloxacin, sulfamethoxazole, estradiol, and ethinylestradiol, were detected at concentrations exceeding guideline values. Estradiol and ethinylestradiol exceeded acceptable limits by more than 14–36 times, indicating substantial endocrine-disrupting potential. Heavy metals such as lead, cadmium, chromium, nickel, and mercury also exceeded permissible limits, with the highest concentrations recorded in Maiduguri and Kano. Total coliforms ranged from 2.7 × 10⁵ to 4.2 × 10⁵ CFU/mL, while multidrug-resistant bacteria accounted for 51.4–66.8% of the isolates. Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae were the dominant bacterial species. The combined hazard index ranged from 2.78 to 4.39, indicating significant non-carcinogenic health risks, while carcinogenic risk values for lead and cadmium exceeded acceptable limits. Strong positive correlations were observed between ciprofloxacin and multidrug-resistant bacteria, as well as between heavy metals and the overall hazard index. The study concludes that pharmaceutical wastewater discharge in Northern Nigeria contributes significantly to environmental contamination, antimicrobial resistance, and public health risk, emphasising the need for improved wastewater treatment and stricter regulation of pharmaceutical waste disposal.
