Enantiomeric ratios of α-hexachlorocyclohexane in blubber of small cetaceans

The enantiomeric ratio of α-hexachlorocyclohexane (α-HCH) in blubber of 10 species of adult male small cetaceans has been determined by means of capillary gas chromatography using β-cyclodextrin as a chiral stationary phase. The enantiomeric ratio of (+)-α-HCH/(−)-α-HCH ranged from 1.6 to 2.8, showing diverse values. Moreover, even in the same species, the ratios varied between animals collected from different localities. Dallʹs porpoise (Phocoenoides dalli) collected from the Bering Sea had enantiomeric ratios of 2.0–2.1 and others, from the North Pacific and Japan Sea, exhibited ratios ranging from 1.6–1.9. The ratios of β-HCH concentration to total HCH concentration (β-HCH/∑HCH) was linearly related to the enantiomeric ratios of α-HCH (r = −0.46, p < 0.005). This may indicate that the metabolic capacity to degrade HCH isomers among cetaceans can be evaluated in terms of degradation of the (+)-α-HCH enantiomer. Present enantiomeric ratios were compared with earlier observations on various environmental samples and unbalanced degradation of (+)- and (−)-α-HCH enantiomers was suggested in small cetaceans.