Seasonal variation and human health risk assessment of potentially toxic elements in pharmaceutical effluents around Ilorin metropolis, Nigeria

Potentially toxic elements (PTEs) are widely released into the environment as a result of increased urban and industrial development in recent years. The bulk of PTEs are cancer-causing and harm human health by producing free radicals. As a result, it is crucial to monitor, evaluate, and limit the effects of the elements on human health. In this study, levels of PTEs (As, Cr, Cd, Ni, Co, and Pb) in pharmaceutical effluents discharged along the Asa River around the Ilorin metropolis and their seasonal variations were evaluated. Water samples were collected from eight different locations over a two-season period along the river and analyzed for PTEs using atomic absorption spectrophotometry and an inductively coupled plasma optical emission spectrometer. As, Cd, Pb, Cr, Ni, and Co had mean PTE values in the effluents (both seasons) of 0.0258, 0.0233, 0.00193, 0.0176, and 0.0164 mg/L, respectively, with As and Pb surpassing the WHO standard. Maximum temperature and pH were measured for the physicochemical parameters in the wet season, whereas electrical conductivity and total dissolved solids were seen in the dry season. The average values of the metals in the human risk assessment for carcinogenicity were As > Cd > Pb > Cr > Ni > Co, with As above the recommended threshold in several locations. However, all of the metal hazard indices were