FUNDAMENTAL AND APPLIED TOXICOLOGY 21, 500-507 ( 1 993) Residual Myelotoxicity of Lindane in Mice

used insecticide, may be found at low concentrations in the hu-man diet. Male B6C3F, mice given lindane daily at doses of 20 and 40 mg/kg body wt by gavage in corn oil for 3 days had suppressed bone marrow cellularity, erythrocyte precursors, granulocyte-macrophage progenitor cells (CFU-GM), and re-sidual progenitor cell damage, which could be demonstrated by two whole-body irradiations (WBI) at 200 rads. Lindane expo-sure for 10 consecutive days at doses of 0, 10, or 20 mg/kg did not cause clinical abnormality or changes in body weights, but there were dose-dependent decreases in marrow cellularity, in more pluripotent stem cells and in committed CFU-GMs, which returned to control values by 4 weeks. These mice were then subjected to two 100-rad exposures of WBI at 4 and 9 weeks following cessation of lindane treatment. This level of irradiation caused only a transient drop in number of marro