Abstract

Levels of organochlorine compounds (PCDD, PCDF, PCB and organochlorine pesticides) were determined in cetaceans collected from the west coast of North America between 1986 and 1989. The samples included gray whale (Eschrichtius robustus), killer whale (Orcinus orca), false killer whale (Pseudorca crassidens), Risso’s dolphin (Grampus griseus) and Dall’s porpoise (Phocoenoides dalli) collected in British Columbia, and harbour porpoises (Phocoena phocoena) collected in British Columbia and central California. TCDD and TCDF levels ranged from 1 to 8 ng kg−1 and 2.0 to 109 ng kg−1, respectively. The highest levels of PCDDs were found in the harbour porpoises; the levels of 1,2,3,6,7,8-HxCDD in the samples from Victoria, Campbell River and Qualicum River were 128, 128 and 62 ng kg−1, respectively. Five other 2,3,7,8-substituted dioxins and dibenzofurans were detected in the cetaceans at levels ranging from 1 to 10 ng kg−1. In addition to the 2,3,7,8-substituted congeners, several non 2,3,7,8-substituted congeners were detected. The patterns of the PCDDs and PCDFs in the British Columbia porpoises were consistent with implication of chlorophenols as the source of the PCDDs and PCDFs, which were either present in wood chips used in bleached kraft paper mills, or came from direct contamination by chlorophenols. No PCDDs or PCDFs were detected in the California samples. One false killer whale sample had exceptionally high levels of DDT compounds (1700 mg kg−1 DDE, 120 mg kg−1 DDT and 40 mg kg−1 o,p′-DDT) and Toxaphene (89 mg kg−1). PCB levels in the cetaceans were highest in the false and killer whales (22 to 46 mg kg−1 GM), and lowest in the Risso’s dolphin (1.7 mg kg−1). Levels of DDE in the British Columbia harbour porpoises were 6.0 mg kg−1, and probably reflect the accumulation of global background levels of DDE.