Trends in organochlorine residue concentrations and burdens in grey seals (Halichoerus grypus) from Sable Is., NS, Canada, between 1974 and 1994.

Abstract In blubber from maternal grey seals ( Halichoerus grypus ) from Sable Is., NS, ΣDDT ( p,p′ -DDE and p,p′ -DDT) concentrations declined from 12 μg/g lipid in 1974 to 0.5 μg/g in 1994. Pup blubber ΣDDT concentrations were about 60% of those of their mothers, and declined at similar rates. In maternal seals, p,p ′-DDE increased from 56% ΣDDT in 1974 to 89% in 1994. Polychlorinated biphenyl concentrations did not change between 1976 and 1988, but then declined; the relative proportion of chlorobiphenyl (CB) 101 increased, and those of CBs 170 and 187 decreased between 1985 and 1991. Concentrations of α-hexachlorocyclohexane and trans -nonachlor declined after 1988, and of oxychlordane after 1992; concentrations of hexachlorobenzene were constant between 1984 and 1994.