Chlorinated organic contaminants in blubber biopsies from northwestern Atlantic balaenopterid whales summering in the Gulf of St Lawrence

Concentrations and patterns of chlorinated biphenyls (CBs) and other persistent organochlorine compounds (OCs) were determined from small blubber biopsy samples collected from northwestern Atlantic minke (Balaenoptera acurostrata), fin (Balaenoptera physalus), blue (Balaenoptera musculus), and humpback (Megaptera novaeangliae) whales summering in the Gulf of St. Lawrence, Québec. Concentrations of ∑PCB (sum of 19 congeners) in biopsy samples ranged from 0.2–10 μg g−1 lipid, and congeners 52, 101, 118, 153, 138 and 180 accounted for 79% of ∑PCB. Mean concentration of the sum of non-ortho CB congeners in selected biopsy samples was 2 ng g−1 lipid, and relative concentrations of these analytes were: 77 > 126 > 81 > 169. Concentrations of ∑DDT ranged from 0.6–13 μg g−1 lipid, and the average proportion of DDE to ∑DDT was 72%. All other organochlorine analytes were present at concentrations below 2 μg g−1 lipid. On average, cis-nonachlor, trans-nonachlor and oxychlordane accounted for 27, 26 and 23%, respectively, of the chlordane-related analytes, and α-hexachlorocyclohexane (HCH) comprised 67% of ∑HCH. Concentrations of ∑DDT were significantly lower and mirex concentrations were significantly higher in minke whales than in the other balaenopterid species. Concentrations of all other analytes were similar in the four whale species. Ratios of proportions of oxychlordane to trans-nonachlor were highest in fin whales. Blue whales had the lowest proportions of α-HCH but the highest proportions of DDT. Interspecies differences in the concentrations and patterns of certain CB congeners and OC compounds may reflect differences in diet or in metabolic capabilities. Males usually had higher mean concentrations of CBs and OCs than females, but these differences were significant only for εDDT, dieldrin, εCH and HCB. Higher proportions of lower chlorinated CB congeners were found in calves compared to adult females, indicating selective reproductive transfer.