In the continuing debate over the effects of pot, the heads appeared last week to have gained a slight edge over the straights. Issuing a summary of current scientific knowledge about marijuana, the National Institute of Mental Health asserted that for most people the drug "does not seem harmful." But the institute cautioned that information about marijuanaespecially about its long-term effectsis still fragmentary and that final judgments await more research.
Meanwhile, NIMH reported some interim findings:
> There is no evidence that marijuana affects unborn children.
> Use of the drug is sometimes associated with...