Organochlorine contaminants in freshwater mussels; occurrence,bioaccumulation pattern,spatio-temporal distribution and human health risk assessment from the tributaries of River Ravi,Pakistan

The present study was conducted to investigate the bioavailable levels and human health risk of organochlorine contaminants (OCs), particularly organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in freshwater mussels from northern three tributaries of River Ravi, Pakistan that provides the pioneer data for the occurrence of POPs in the freshwater mussels from Pakistan. The Σ₂₃OCPs and Σ₃₅PCBs concentrations in mussels were ranged from 189.66–2049.40 ng/g and 25.81 to 135.38 ng/g, respectively. The comparison of current bioavailable levels of OCs with maximum residual limits (MRLs) established by Food and Agricultural Organization and European Union revealed that Σendosulfan (100%), ΣDDTs (93%), HCB (87%), β-HCH (77%), endrin (77%), γ-HCH (70%), heptachlor (67%), aldrin (67%), dielrin (67%), Chlordane (70%), α-HCH (40%), and WHO-TEQ (2005) values for PCB-126, PCB-169 and Σ₈DL-PCBs were exceeding the permissible limits. The human health risk assessment revealed the occurrence of substantial lifetime carcinogenic risk for OCPs and PCBs at both 50th and 95th percentile concentrations in freshwater mussels from the tributaries of River Ravi. Therefore, the freshwater mussels are recommended to be used in environmental toxicological studies to assess the bioavailable levels of pollution in hostile environment.