The occurrence and ecological risk associated with nine pharmaceuticals; Ciprofloxacin, Metronidazole, Amoxycillin, Trimethoprim, Tetracycline, Sulfamethoxazole, Ibuprofen, Diclofenac and Paracetamol were investigated in water and sediments of Usuma Dam, Abuja, Nigeria. The samples were extracted with solid phase extraction and analysed with high performance liquid chromatography coupled with UV/VIS detector (HPLC-UV/VIS). Metronidazole with a concentration range of 191.11-572.73 ng/L and Trimethoprim with a concentration range of 0.27-0.42 µg/g d.w. were the predominant antibiotics in the water and sediments respectively. Ibuprofen was the only analgesics detected in the samples. The ecological risk assessed with the worst observed data for each pharmaceutical in the samples showed that Amoxycillin and Ibuprofen pose a high toxic risk to aquatic life in the dam while Trimethoprim and Ciprofloxacin could result in medium ecological risk. The results of this study draw attention to the occurrence and ecological risks of pharmaceuticals to aquatic life.

Usuma Dam is the major source of potable water in the Federal Capital Territory, Abuja, Nigeria. The physicochemical properties of water and sediment of the dam was assessed in this study to determine its quality. Electrical conductivity, pH, nitrate, phosphate, total dissolved solids, total suspended solids, turbidity, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, chloride, total hardness, phosphate, nitrate and sulfate were determined in the water samples. Total organic matter, total organic carbon and particle size were among the parameters analyzed in sediments. The parameters were within recommended limits except for biochemical oxygen demand and chemical oxygen demand which were more than the recommended limit of 10 mg/L and 30 mg/L respectively. The total organic matter and the total organic carbon in the sediment samples were between 1.56±0.27 – 2.85±0.20 % and 0.13±0.03 – 0.96±0.03 % respectively. The particle size was in the following order: sand > silt > clay. The results of this study confirmed the presence of high organic and inorganic matter in the dam from non-point pollution sources occasioned by storm water from poorly planned settlements around the dam and runoffs from agricultural practices.