Wrong signal on marijuana

In rejecting the conclusions of a National Academy of Sciences panel that called for the decriminalization of marijuana, academy president Frank Press expressed legitimate scientific and political concerns. As noted by Mr. Press, a recent study by the academy's own Institute of Medicine concluded that ''marijuana has a broad range of psychological and biological effects, some of which, at least under certain condition, are harmful to human health.'' While the medical panel conceded that little is definitively known about the effects of the drug, that which is known ''justifies serious national concern.''

Mr. Press also properly points out that decriminalization involves a decided risk, for it would send a clear signal to young people in particular that experts believe the drug is ''safe.''

It is interesting that this latest panel report urging that penalties for personal marijuana use be repealed comes at a time when evidence suggests that use of the drug is falling off among the young. It makes little sense to end federal restrictions when doubts about the drug are growing.

Back in 1972 the Nixon administration rejected a report by a national commission on marijuana which concluded that decriminalizing the drug would not lead to expanded usage. The Reagan administration should exercise similar good judgment.