Occurrence of Emerging Contaminants and Heavy Metals in Freshwater and Wastewater Samples from Southwest States, Nigeria

Abstract

In recent decades, contaminants have been described as one of the highest causes of diseases and premature deaths globally. A new class of contaminants known as emerging pollutants has been identified as dangerous to the environment and human health. Samples were collected from Lake 264, Rivers Osun and Ureje from Osun and Ekiti States. Raw effluent, slurry sludge, treated effluent and canal water were collected from Apapa and Festac Town, Lagos State. The concentrations of iron (Fe), lead (Pb), cadmium (Cd), chromium (Cr) zinc (Zn), nickel (Ni) and manganese (Mn), bisphenol A (BPA), phthalates, dioxin, erythromycin, tramadol, paracetamol, diclofenac, diazepam and monosodium glutamate were measured in the samples. The result showed that the concentrations of Cd and Cr in all samples were below the detection limits and the Standard Organisation of Nigeria (SON) permissible limits of 0.03 and 0.05 ppm, respectively. The highest concentrations of Fe (28.33 ppm), Zn (6.50 ppm), Pb (5.00 ppm) and Mn (9.50 ppm) were detected in the slurry sludge. However, Fe (20.00 ppm), Zn (5.00 ppm) and Mn (9.00 ppm) in raw effluent were above the WHO limit of 2.00, 3.00 and 0.04 ppm. The canal water revealed the presence of paracetamol, diazepam, diclofenac, BPA and phthalate esters. In addition, BPA and phthalates were detected in Rivers Osun and Ureje, wastewater, sludge and treated effluents. Human health risk assessment results showed that the chronic daily intake (CDI) values in the slurry sludge and raw effluents were above the reference dose of the metals and found in the order Fe > Mn >Zn>Pb>Ni>Cd>Cr for the children and adult population. Hazard quotients (HQ) and hazard index (HI) values were greater than 1 and may be carcinogenic to humans. This study concludes that pollutants were present in the study location, irrespective of their proximity to industries and recommends further research on emerging contaminants, their human health risks assessment, evaluation and prevention and control of all pollutants.