Hexachlorocyclohexanes (HCH) in ringed seal (Phoca hispida) from Ulukhaktok (Holman), NT: Trends from 1978 to 2006

Trends in α-, β-, and γ-hexachlorocyclohexane (HCH) concentrations were examined in blubber lipid of ringed seals (Phoca hispida) from Ulukhaktok (Holman), NT (Canada) sampled at intervals between 1978 and 2006. α-HCH usually represented approximately 90% of the total HCH isomers. α-HCH and γ-HCH concentrations showed no change over the sampling interval, but β-HCH concentrations increased significantly, about 8–10-fold in females and 4–5-fold in males. Residue concentrations showed no dependence on age. Concentrations (all data as ng/g lipid, GM (range)) of α-HCH were significantly higher (P < 0.001 by t-test) in males (217 (93.9–517), n = 37) than those in females (138 (40.9–402), n = 38). β-HCH concentrations did not differ between the sexes. Concentrations of γ-HCH were significantly higher (P < 0.05) in males (6.74 (0–46.7)) than in females (4.35 (0–19.0)). Although global emissions of both α-HCH and β-HCH have declined since the early 1980's, the “signal” of HCH emission changes has not yet resulted in a “response” in ringed seal residue concentrations. In the light of our current understanding of the dynamics of HCH in the Arctic, we conclude that any such response may not be detected by retrospective analyses of the sort describe here at least for another decade or so, because of the longevity of the seals.