Comparative study on the distribution of alpha- and gamma-hexachlorocyclohexane in the rat with particular reference to the problem of isomerization.

Blood levels and tissue distributions of alpha-, beta-, gamma- and delta-hexachlorocyclohexane (HCH) were studied following oral administration of alpha-HCH and gamma-HCH to rats. Following administration of alpha-HCH, there was no evidence of beta-HCH, gamma-HCH or delta-HCH, nor could transformation into alpha-HCH, beta-HCH or delta-HCH be detected after exposure to gamma-HCH. After eight weeks of administration, tissue retention of alpha-HCH was 10-20 times greater than that of gamma-HCH. gamma-HCH was eliminated to a much greater extent than alpha-HCH from the tissues, and in particular from fatty tissue. alpha-HCH accumulated in fat and brain, while gamma-HCH showed very low affinity for lipid.