Pot Shots

"After years of giggling at quaintly outdated marijuana scare stories like the 1936 movie 'Reefer Madness,' " writes drug czar John P. Walters in a recent Washington Post op-ed piece, "we've become almost conditioned to think that any warnings about the true dangers of marijuana are overblown."

Walters thus concedes that people like him have been lying to the public about marijuana for at least 66 years. But finally, he seems to be saying, the government is telling the truth. Walters does not get far before he reneges on that implicit promise.

The drug czar claims "drug use among our nation's teens remains at near-record levels, with some 49 percent of high school seniors experimenting with marijuana at least once prior to graduation—and 22 percent smoking marijuana at least once a month." Actually, the latter figure refers to use in the previous month, not "at least once a month," and these numbers peaked at 60 percent and 37 percent, respectively, in 1979.

Walters says marijuana is "10 to 20 times stronger" today than it used to be. As the sociologist Lynn Zimmer and the pharmacologist John P. Morgan explain in Marijuana Myths, Marijuana Facts, claims like these are based on a spurious comparison with small samples of low-grade Mexican marijuana seized in the early '70s. These samples were not representative of the marijuana available at the time, and it appears that they decayed before they were tested. Even if average potency were somewhat higher today, that would be a health advantage, since users could smoke less to achieve the same effect.

"Each year," Walters asserts, "marijuana use is linked to tens of thousands of serious traffic accidents." Linked is a slippery word. The fact that traces of marijuana are found in a driver's blood does not mean he was under the influence at the time of the accident or that marijuana contributed to the crash. In a 1992 analysis of accidents in which the drivers were killed, the National Highway Traffic Safety Administration reported: "The THC-only drivers had a responsibility rate below that of the drug-free drivers… While the difference was not statistically significant, there was no indication that cannabis by itself was a cause of fatal crashes."

To support his contention that marijuana "is in fact addictive" (whatever that means), Walters reports that two-thirds of the "4.3 million Americans who meet the diagnostic criteria for needing drug treatment… are dependent on marijuana." Since Walters conveniently leaves out alcohol, and since marijuana is by far the most popular illegal drug, its predominance among people with drug problems is hardly surprising. A more relevant question is what percentage of marijuana users get into trouble with the drug. A 1994 study based on data from the National Comorbidity Survey estimated that 9 percent of marijuana users have ever met the American Psychiatric Association's criteria for "substance dependence." The comparable figure for alcohol was 15 percent.

Walters says claims about marijuana's medical utility are "based on pseudo-science." Apparently he has not seen the National Academy of Sciences report that discusses the evidence at length. He should check it out. It was commissioned by his predecessor.