PCBs and organochlorine pesticides concentration levels in liver and fat tissues of diurnal (falconiformes) and nocturnal (strigiformes) birds of prey from Greece

Since the organochlorine contaminants (OCs) are persistent in the environment, contamination by the toxic chemicals has been consequently found in air, water, fish, marine mammals and human even after the ban or restriction of their use. However, information on OCs residues present in avian wildlife inhabiting Greece is lacking. This study was initiated in order to gain first information about the levels of organochlorines in Greek predatory birds. Birds of prey are intensively used in biomonitoring studies due to their position at the top of the food chain and the spatial integration of contaminant levels of their extended home ranges. In the time period of 1 year, during 2003, 16 bird of prey species (6 and 10 species from stigiformes and falconiformes families respectively) were collected with the collaboration of Hellenic Wildlife Hospital (Aigina Island, Greece). Liver and subcutaneous fat tissue samples were analyzed for seven target PCB congeners (Nos 28, 52, 101, 118, 138, 153 and 180) and for nineteen organochlorine pesticides such as DDT and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs) and cyclodienes (Cycls). The analytical method was based on Soxhlet extraction, sulfuric acid and alumina column clean-up followed by gas chromatography coupled to electron capture and MS detection. This is the first report of PCBs in Greece birds of prey tissues to be presented. Geometric mean concentrations of total PCBs ranged from 24.96 to 1254.40 ng/g ww for falconiformes and from 33.6 to 204.1 ng/g for strigiformes. From the organochlorine insecticides p,p'-DDE was found in higher levels (geometric mean concentrations up to 5.74 mu g/g for strigiformes and 17.35 mu g/g for talconiformes). The concentrations are similar to those reported for birds in other European and Mediterranean countries. The congeners generally present in the highest concentrations were 118, 138, 153 and 180. Residues of any contaminant measured in a bird will vary according to many factors, including feeding habits, metabolic capabilities and the nutritional state of the bird. The liver PCBs reported in this study are below the concentrations currently believed to exert ecotoxicological effects. On the contrary, in some cases p,p'-DDE concentrations are higher than the reported effect values for birds of the same order. The results from such monitoring studies are useful for conservation actions of birds of wildlife.