Pubdate: Fri, 25 Feb 2000 Date: 02/25/2000 Source: Washington Post (DC) Author: Christopher A. Joseph Note: Title supplied by Newshawk Fern Shen [Metro, Feb. 22] did a fair job of citing the Institute of Medicine (IOM) report on marijuana, but she erred in allowing Maryland Del. Thomas E. Dewberry to use the alleged "gateway effect" as reason to oppose its use. The IOM report stated that there is no gateway. If there were, then alcohol and tobacco would be the true gateways, as most who use marijuana, cocaine or heroin had taken those drugs first. CHRISTOPHER A. JOSEPH, Parma, Ohio