Organochlorine pesticides and polybrominated diphenyl ethers in sediments around oil production facilities in the Escravos River basin, Nigeria: Implications for ecological and human health risk

Abstract

Organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) are halogenated organic compounds of special interest because of their persistent, pervasive and exceptionally toxic nature. Sediments collected in the vicinity of petroleum production facilities in the Escravos River basin (ERB) of Nigeria were analyzed for 20 OCPs and 39 PBDEs by gas chromatography–mass spectrometry (GC–MS). The OCP concentrations in the ERB sediments varied from 0.69 to 10.7 ng g⁻¹ (mean = 5.65 ng g⁻¹), while those of the Σ39 PBDEs ranged between 0.19 and 435 ng g⁻¹ (mean = 39.1 ng g⁻¹). The OCP class profiles in the sediments followed the order: Drins > Chls > DDTs > Endos > HCHs, while those of the PBDEs were in the order: tetra- > penta- > hexa- > tri- > hepta- > di- > mono- > deca-BDE. The ecological risk assessment suggests rare adverse effects for OCPs in the ERB sediments and potential adverse effects for penta-BDEs in the sediments. The results from the carcinogenic risk assessment suggest that human exposure to OCPs in the majority of the sites can be of moderate carcinogenic risk, while there is no risk for exposure to PBDEs in the sediments. The source analyses reflect the prominence of historically used sources over recent inputs for OCPs, while those of PBDEs reflect products of debromination of higher BDEs and the use of penta-BDEs rather than the deca-PBE mixture in the region.