Role of Polychlorinated Biphenyls (PCBs) and Polycyclic Aromatic Hydrocarbons (PAHs) on Survival of Free Ranging Birds: A Review

Abstract

The PCB contaminant levels reported in tissues individuals are not likely to have an impact on the demographic performance of the birds as a whole. However, the residues may reach levels causing decreased reproduction or survival in some years, particularly when combined with other non-anthropogenic stressors such as food scarcity. In addition, the birds normally would have more exposure to the contaminants due to their position in the food chain. Incidentally, none of the study reports revealed the free PCB and PAH congeners. Although a few experimental studies have shown the effects of PAHs in bird behavior, field assessments are invariably confounded by ecological differences between contaminated and uncontaminated sites. Presence of PCB and PAH residues in birds shows the continuous presence of these contaminants through industrial and other petrochemical operations. Studies have indicated widespread occurrence of PAHs in abiotic and biotic components. However, studies on the impact of PAHs on birds are scarce. In international context, information on the ill effects of physical deposition of oil on sea birds is available, but accumulation of PAHs in internal organs and the impact on birds is very limited. Hence, it may be recommended to study on assessing the PCBs and PAHs concentration among various species of birds and document the variation in residue concentration among tissues, years and between sexes and create baseline information of these contaminants on birds. This study recommends a continuous monitoring program on PAHs and PCBs and their metabolites in various species of birds.