Accumulation profile and seasonal variations of polychlorinated biphenyls (PCBs) in bivalves Crassostrea tulipa (oysters) and Anadara senilis (mussels) at three different aquatic habitats in two seasons in Ghana

Abstract

Research has shown that some polychlorinated biphenyl congeners degrade slowly in the environment and build up in the food chain, causing a wide range of possible adverse effects to humans. In order to ascertain the nature of the situation in Ghana, polychlorinated biphenyls congener residues in Crassostrea tulipa (oysters) and Anadara senilis (mussels) at Narkwa, Ada and Anyanui in the coastal region of Ghana were determined. At Narkwa, both bivalves’ species were collected; at Ada only Anadara senilis were collected while at Anyanui, only Crassotrea tulipa were collected. The number of each bivalve species collected from each site was 80 (n=80), making up a total of 320 for the dry and the wet seasons. The PCBs were extracted with (1:1) hexane-acetone mixture and analyzed with a gas chromatogram equipped with 65Ni electron capture detector, model CP 3800 using the mixed PCBs standard of the ICES 7. Total PCBs in the bivalves ranged from 5.55 to 6.37μg/kg wet weight in mussels and 2.95–11.41μg/kg wet weight in oysters, respectively. The composition of the PCB homologues in the bivalves was dominated by tri-, hepta- and hexa-PCBs in descending order. Risk assessments conducted on the samples indicated that edible bivalves from Narkwa, Ada and Anyanui in Ghana might pose some health risk to the consumers.