Metabolic fate of cis- and trans-chlordane in mice

A single dose of a cis-chlordane and trans-chlordane mixture (1:1) was orally administered to mice (total dose: 40 mg/kg), and the metabolic fate of the two congeners administered and their major metabolite, oxychlordane, in various tissues, was studied from day 1 after dosing to week 52. Cis-chlordane and trans-chlordane showed the highest concentrations on day 1 after dosing, and disappeared on day 14 except in the liver. The half life in the tissues was approximately one day for both congeners. On the other hand, oxychlordane was observed in various tissues from day 1 after dosing, reaching the maximum concentration on day 1 or 2 showing considerably higher concentrations than those of the congeners. The rate of decrease of oxychlordane in the tissues was extremely slow compared to the congeners. It was found that oxychlordane remained in the tissues even in week 52 (year 1) after dosing. The regression curve for the tissue oxychlordane concentration was diphasic after or at around week 8 after dosing; the half life was approximately 20 days in the first phase and was prolonged to over 100 days in the second phase. These results suggest that the cis-chlordane and trans-chlordane taken into the human body via foods disappear rapidly from the tissues but that oxychlordane, their metabolite, remains in the body over a prolonged period of time.