Enantiomeric ratios of alpha-hexachlorocyclohexane in blubber of small cetaceans

The enantiomeric ratio of alpha-hexachlorocyclohexane (alpha-HCH) in blubber of 10 species of adult male small cetaceans has been determined by means of capillary gas chromatography using beta-cyclodextrin as a chiral stationary phase. The enantiomeric ratio of (+)-alpha-HCH/(-)-alpha-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 beta-HCH concentration to total HCH concentration (beta-HCH/Sigma HCH) was linearly related to the enantiomeric ratios of alpha-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 (+)-alpha-HCH enantiomer. Present enantiomeric ratios were compared with earlier observations on various environmental samples and unbalanced degradation of (+)- and(-)-alpha-HCH enantiomers was suggested in small cetaceans.