Organochlorine contaminants in narwhal (Monodon monoceros) from the Canadian Arctic

Abstract

Organochlorine pesticides (DDT, chlordane, polychlorinated camphenes (PCCs), dieldrin, hexachloroheclohexanes (ΣHCH), mirex), polychlorinated biphenyl congeners (PCBs) and chlorobenzenes (ΣCBz) were determined in blubber and liver of narwhal (Monodon monoceros) collected during 1982-1983 from Pond Inlet on northern Baffin Island in the Canadian Arctic. PCCs were the predominate organochlorines in narwhal blubber, ranging in concentration from 2990 to 13 200 ng g-1 (wet wt) in males and from 1910 to 8390 ng g-1 in females. PCCs consisted of two major components, an octachlorobornane and a nonachlorobornane with gas chromatographic retention times of 1·05 and 1·22, relative to 4,4′-DDE. ΣPCB concentrations in blubber ranged from 2250 to 7290 ng g-1 in males and from 894 to 5710 ng g-1 in females. Seven PCB congeners (tetra-, penta- and hexachlorobiphenyls) accounted for 45% of total PCB (ΣPCB) in narwhal blubber. Narwhal had 1·4- to 8·6-fold higher ratios of tetra- and pentachlorobiphenyls to PCB-153 (2,2′,4,4′,5,5′-hexachlorobiphenyl), lower 4,4′-DDE/ΣDDT ratios and lower proportions of trans-nonachlor to total chlordane components than reported for odontocetes living in more contaminated environments. Mean ΣPCB concentrations in narwhal were 6- to 15-fold lower than in dolphins from the Canadian east coast and belugas from the St Lawrence River estuary, respectively, while PCC levels were from 4- to about 2-fold lower, and ΣHCH, dieldrin and ΣCBz differed by <2-fold. The pattern of organochlorines in narwhal tissues suggests they are exposed to proportionally more volatile compounds, and may have less capacity to metabolize some of these compounds, relative to odontocetes living nearer sources of these contaminants. © 1992.