Persistent organochlorines in beluga whales (Delphinapterus leucas) from the St Lawrence River estuary .1. Concentrations and patterns of specific PCBs, chlorinated pesticides and polychlorinated dibenzo-p-dioxins and dibenzofurans

Blubber samples from beluga whales (Delphinapterus leucas) in the St Lawrence River estuary were analysed for PCB congeners (ortho- and non-ortho-substituted) and other persistent organochlorines as well as chlorinated dibenzo-dioxins/furans (PCDD/Fs). Major individual components (mean concentrations > 1 mu g g(-1)) were 4,4'-DDE, -DDD and -DDT, T12 (a toxaphene-related compound), trans-nonachlor, oxychlordane, mirex, HCB, tris(p-chlorophenyl) methane and dieldrin. Concentrations of Sigma PCBs (8.3-412 mu g g(-1)), Sigma DDT (3.36-389 mu g g(-1)) and mirex (0.18-6.8 mu g g(-1)) were particularly elevated relative to other odontocetes in Canadian waters. Sigma DDT, PCBs (as Aroclor), mirex and T12 concentrations were positively correlated with age of adult females (>10 years) but only weakly, or not significantly, correlated with age ofadult males. PCDD/Fs were present at low ng kg(-1) levels and consisted mainly of penta- and hexachlorofurans, and hepta- and octachlorodioxin. CB126 (3,3',4,4',5-PCB) was the most prominent non-ortho-substituted PCB congener in beluga blubber. Total TCDD toxic equivalents averaged 330 ng kg(-1) in females and 1400 ng kg(-1) in males and were dominated, CB126, and the mono-ortho-substituted congeners CB105 and CB118. Biomagnification factors (BMFs) for mirex and Sigma PCB from fish to beluga ranged from 11 to 16, and were similar to BMFs in Arctic animals, indicating that elevated levels in St Lawrence animals are a consequence of relatively, high levels of recalcitrant organochlorines in prey of the beluga in the St Lawrence river system. Copyright (C) 1996 Elsevier Science Ltd