In vivo and in vitro studies of the cytogenetic effects of Cannabis sativa in rats and men.

The cytogenetic effects of Cannabis sativa were studied in (a) embryonic rat fibroblasts and rat and human leucocytes exposed to 40–200 μg/ml of cannabis resin in vitro for 6–72 h, (b) embryonic rat cells and leucocytes from pregnant rats exposed to a teratogenic dosage of cannabis resin in vivo, and (c) leucocyte cultures from male Jamaican chronic cannabis smokers. The in vitro experiments showed depression of mitotic rate with increasing doses of cannabis resin. In both in vitro and in vivo studies the experimental groups showed no increase in the percentage of numerical or structural chromosome aberrations. It appears that the reported teratogenic effects of cannabis are not due to chromosome damage though they may be due to mitotic inhibition.