Polychlorinated dibenzo-p-dioxins and furans and non-ortho- and mono-ortho-chlorine substituted polychlorinated biphenyls in grey seals (Halichoerus grypus) from Sable Island, Nova Scotia, in 1995

Abstract Six mother–pup pairs of grey seals ( Halichoerus grypus ) were sampled on Sable Island, Nova Scotia (NS), in January 1995. Blubber samples from mothers and pups, and blood and milk samples from mothers were analysed for polychlorinated dibenzo- p -dioxins and furans (PCDD/Fs) and for non- ortho and mono- ortho chlorobiphenyls (NO- and MO-CBs). Total PCDD and PCDF concentrations were each below 20 pg/g lipid in blubber samples; these are among the lowest concentrations recorded in seals, and indicate little contamination by these compounds. Total NO-CB concentrations in blubber were in the low ng/g lipid range. Concentrations of MO-CB ranged from a few pg/g lipid to several hundred ng/g lipid in blubber; total NO- and MO-CB congeners measured were in the low μg/g lipid range. PCDD/Fs were detected only sporadically in blood samples but were measurable in milk samples. The transfer efficiency of CB congeners between maternal and pup blubber lipid was inversely correlated with lipid solubility (as indicated by ln K o/w ) and this selectivity of transfer appeared to occur partly at the stage of digestion of milk by the pup.