Nahas, a Columbia University pharmacologist, believes that marijuana is a dangerous drug. He notes that it accumulates in the body, deposited in fatty tissues like brain, liver, kidney, and sex organs. Thus even a mild user carries traces of the drug at all times. Nahas' and other studies suggest that the active ingredient (THC) and other metabolites diminish the normal rate of cell division and produce more chromosomally damaged cells. Lymphocyte (white cell) counts are lower in users than in non-users (although there is no evidence that the former are more infection-prone). Studies of male users have also shown diminished sperm counts and even total impotence. In this semi-autobiographical account Nahas is on the defensive, but also counterattacking the social scientists who want to legalize the drug and claim it is less harmful than alcohol or tobacco. He also provides an interesting history of marijuana in both the less intoxicating fibrous forms that grow wild in North America and the powerful varieties found in India or North Africa. Nahas' strong feelings stem in part from a childhood in Egypt where the use of hashish (a more potent form) was condemned among the educated and affluent; it was considered a tragic habit associated with misery and poverty. Certainly much more research is needed to disclose the short- and long-term psychological and physiological effects of the drug. In the meantime Nahas agrees that strongly punitive laws against users are unfair but feels that any attempt to legalize drug use would be disastrous.