Latitudinal fractionation of polybrominated diphenyl ethers and polychlorinated biphenyls in frogs (Rana temporaria)

Abstract

The flame retardant polybrominated diphenyl ethers (PBDEs) have become ubiquitous environmental pollutants. The environmental distribution of PBDEs is much less studied than that of the polychlorinated biphenyls (PCBs). To compare the environmental fate of the PCBs with their partial substitute, the PBDEs, common frogs (Rana temporaria)were collected along a ∼1500-km-long latitudinal gradient of the Scandinavian Peninsula and their livers analyzed for PCBs and PBDEs. Mean concentrations of total PCBs and BDE47 ranged from 9200 to 92 900 and 30 to 120 ng kg-1 fresh weight, respectively, whereas BDE99 was detected in less than 50% of the frogs. PCB concentrations were higher than that of the PBDEs, and the differences decreased in the northern latitudes. Moreover, the pollutant concentrations in frog livers were negative functions of latitude. The observed scatter and regression slopes imply several influencing factors (such as habitat, exposure route, uptake, metabolism, excretion, etc.) and indicate release events instead of the grasshopper effect. Biological variables such as gender, age, body size, and lipid content did not influence pollutant concentrations in the frog livers. The total PCB and BDE47 concentrations in frogs were highly correlated. Hence, their environmental fate is analogous and our results highlight the need to examine the potential role of xenobiotics on amphibian populations.