Studies on the distribution of beta- and gamma-isomers of hexachlorocyclohexane in rat tissues.

A study of the comparative distribution pattern of beta- and gamma-isomers of hexachlorocyclohexane (HCH) in albino rat tissues as a function of duration of treatment at two dose levels revealed different accumulation patterns for the two isomers in tissues. In general, the accumulation pattern was found to be in the order: fat greater than kidney greater than lungs greater than liver greater than muscle greater than heart greater than spleen greater than brain greater than blood for beta-HCH and fat greater than brain greater than kidney greater than muscle greater than lungs greater than heart greater than spleen greater than liver greater than blood for gamma-HCH. The tissue accumulation of beta-isomer was always greater than that of gamma-isomer in any tissue except in brain. Brain beta-HCH residue levels were relatively lower than in many other tissues except blood, whereas brain gamma-HCH concentration was only next to fat. A higher dose or a longer period of treatment generally produced a more marked elevation of tissue residue levels in beta-HCH fed rats, but not in gamma-HCH treated animals.