Determination and Risk Associated with Phthalic Esters Distribution from the Ekpan River, Effurun, Delta State, Nigeria

Abstract

Phthalates are additives or plasticizers added to make plastics soft. However, they could leach into the environment and cause harm to human health when contacted. Sites along the Ekpan river have been used for open dumping of refuse. The river also serves as a point source for the disposal of effluents from the Warri Refinery and Petrochemical Company Limited (WRPC). Hence, the need for a preliminary study of phthalates across the river system. Surface water samples were collected from six points along the Ekpan river. Phthalates were extracted using USEPA standard method 3535 and EPA method 8061. Gas Chromatography-Mass Spectrometer (GC-MS) was used for the analysis of six PAEs including di-n-butyl phthalate (DnBP or DPX), butyl benzyl phthalate (BBP), di(2-Ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (D-n-OP)), Dimethyl phthalate (DMP), and Diethyl phthalate (DEP) in the river system. Analysis of phthalates in the Ekpan river system showed that DEP across the Effurun river system ranged from 4.22 – 13.81 μg/L, DPX; 3.03 – 11.5 μg/L, BBP; 0.11–1.39 μg/L, DEHP; 0.12 – 3.33 μg/L. D-n-OP and DMP were below the limit of detection of the analytical instrument used (0.1 μg/L). The distribution of PAEs along the network of the river revealed that the sampling sites in the urban region were more contaminated with PAEs due to urbanization and an increase in population across the river network. Human health risk assessment revealed that the hazard quotient (HQ) for DEP, DPX, DEHP, and D-i-NP were below 1, indicating an acceptable risk of PAEs via ingestion or bathing of the river water. In addition, the Hazard Index (HI) via ingestion and bathing of the river water was less than 1 indicating acceptable risks. According to this study, these PAEs congeners are safe for toddlers, adolescents, and adults to eat and bathe in tap water. Even DEHP, the only PAEs congener designated as a carcinogenic agent by WHO, was shown to have a tolerable cancer risk. These findings indicate that there is no harm to children, adolescents, and adults from DEHP in the river water studied.