Seasonal Occurrences and Risk Assessment of Phthalate Esters in Sediment, Water and Biota of Two Sub-Saharan Rivers

The global environmental occurrence of phthalates is inevitable due to their substantial annual production and consumption rate of approximately 5 million tonnes. This study aimed to evaluate the seasonal occurrence of selected phthalate esters congeners in sediment, water, and biota in two freshwater bodies (River Owena and River Ogbese) in Nigeria, and to calculate their ecological risks they pose to aquatic organisms. Dibutyl-phthalate (DBP), di-2-ethylhexyl phthalate (DEHP), and dimethyl-phthalate had an all-year presence in various environmental matrices. DBP was the most prevalent phthalate congener in all environmental matrices with a considerable potential to bioaccumulate in fish tissues. The estimated risk quotient calculated revealed that DBP and DEHP showed a high risk to algae, invertebrates, and fish populations in both freshwater bodies. It is recommended that more comprehensive monitoring campaigns in freshwater bodies be implemented, especially in areas with high anthropogenic activities, to prevent deterioration of aquatic life.