Enantiomeric ratios of α-hexachlorocyclohexane in blubber of small cetaceans

Abstract

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. Dall's 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.