Variations of polychlorinated biphenyls (PCBs) levels in the bivalve Galatea paradoxa from Ada, in Ghana, during the dry and wet seasons

Justice Wiston Amstrong Jonath

Abstract

Polychlorinated biphenyls (PCBs) are synthetic, aromatic organochlorine chemicals regulated by the Stockholm Convention on Persistent Organic Pollutants (POPs) due to their slow degradation, toxicity, lipophility and the ability to accumulate and biomagnify in food chains. Several studies have revealed a wide range of adverse health and developmental effects associated with exposure to PCB congeners. In order to investigate the magnitude and spatial distribution of PCBs in biota in Ghana, the bivalve Galatea paradoxa from Ada in Ghana was analyzed to determine their PCB congener concentration levels during the wet and dry seasons. The number of bivalves collected for both seasons was 180. PCB congeners were extracted using 1:1 acetone-hexane solvent mixture and the samples analyzed with a gas chromatogram; model CP 3800, equipped with electron capture detector (GC-ECD), using mixed PCBs standard of ICES 7 after clean-up. Quality assurance assessment was carried out to validate the efficiency and precision of extraction and analytical methods by the use of spiked samples and certified reference material, 1941b, from NIST, USA and analyzed alongside the samples. Total mean PCB congener levels detected ranged from 7.56 ± 1.08 µg/kg wet weight (for the dry season) to 8.26 ± 1.18 µg/kg wet weight (for the wet season); with a mean of 7.91 µg/kg wet weight. The levels of PCB congeners detected in Galatea paradoxa were very low and compared favorably well with those obtained in bivalves from other regions of the world. The compositions of PCB homologues detected followed the descending order: hepta (24.78%), tetra (22.62%), hexa (21.61%), tri (17.44%t) and penta (13.65%). Results of risk assessment conducted on the data showed that PCBs levels in Galatea paradoxa from Ada in Ghana were not high and fall within the recommended standards set by the World Health organization (WHO) and other regulatory authorities, hence may not pose any significant health risk to consumers.