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Debunking hysterical coverage of marijuana is just too easy. For example, this front-page piece from USA Today was headlined “Caution: Marijuana May Not Be Lesser Evil.”

But it didn’t provide any evidence to support that claim. The story noted that the controversy over whether marijuana is a “gateway” to other drug use is still raging. But it failed to mention that the Institute of Medicine – charged with settling scientific controversies by Congress – had this to say about marijuana as a gateway in 1999:

“In the sense that marijuana use typically precedes rather than follows initiation of other illicit drug use, it is indeed a ‘gateway’ drug. But because underage smoking and alcohol use typically precede marijuana use, marijuana is not the most common, and is rarely the first, ‘gateway’ to illicit drug use. There is no conclusive evidence that the drug effects of marijuana are causally linked to the subsequent abuse of other illicit drugs.”

Since then, several studies (not cited by USA Today) have further supported its conclusions, and no new human data disputes them. In other words, most drug users don’t start with marijuana, most marijuana users don’t become addicted to marijuana and most do not try other drugs, let alone become addicted to them.

In Holland, where marijuana is quasi-legal in an attempt to separate the markets for it and other illicit drugs, the percent of marijuana users who ever try cocaine is 22%; in the U.S., it is 33%; if a “gateway” exists, it is most likely related to the fact that drug dealers often sell more than one product and American drug education explicitly rejects the idea of teaching students that marijuana is less harmful.  But this refutation of the gateway idea also went unreported.

And this wasn’t the only misleading aspect of the story. The paper cited a rat study by Yasmin Hurd, professor of psychiatry, pharmacology and biological chemistry at the Mount Sinai School of Medicine in New York which found that giving marijuana makes rats more sensitive to heroin addiction.

But USA Today didn’t note that the rats weren’t more likely to try heroin (which would be a gateway effect) but were more likely to use higher doses if they were exposed to it. Nor did it note that, unlike humans, most rats find marijuana stressful and have to be forced to take it ,and that stress has long been linked with greater risk of addiction. (The rats were given intraperitoneal injections, not a common route for teen drug use.) 

The article made much of the notion that early exposure to drugs is more likely to produce addiction, but failed to highlight that the people who try drugs earliest in life are very different from those who tend to try them later.

The early experimenters are far more likely to have been abused, to come from chaotic homes, to have addicted parents and to have undergone other stressful experiences; in other words, they use drugs early because they are troubled, they aren’t simply troubled because they used drugs early.

In fact, one of the stories the article used to illustrate the dangers of marijuana was of a teen whose mother kicked drugs while his father was in jail on possession charges – an example of a child with a stressful life and a strong genetic history of addiction, not one of marijuana producing a downward spiral.

USA Today also claimed that “studies have shown that when regular pot smokers quit, they do experience withdrawal symptoms, a characteristic used to predict addictiveness.” In fact, withdrawal symptoms do not predict the addictive nature of substances: some medications used to treat high blood pressure can produce a fatal withdrawal reaction, but unlike truly addictive drugs, they do not produce craving. Conversely, cocaine produces few physical withdrawal symptoms compared to heroin, but few would argue that it’s not addictive.

While marijuana can produce craving in some people, despite being the most commonly used illicit drug in the U.S, it is not a substance many people seek help kicking. There were only 284,000 treatment admissions for marijuana problems in 2003, even though the drug was used by 15 million people in the past month that year, and roughly half of adults have tried it. There are higher rates of marijuana treatment for teens; but teens are more likely to be coerced into treatment whether they need it or not.

And heroin – though only about 1% of the population has tried it – accounted for virtually the same number of treatment admissions. The majority of treatment episodes are related to alcohol: 41%.

So, where’s the evidence that marijuana is more harmful than other substances? And, why didn’t the story mention the recent research failing to link marijuana to lung cancer, once the best argument against heavy use of the drug?

The piece did include information on a study that linked the heaviest marijuana use to cognitive impairment, correctly noting that the link may not be causal and could be related to the fact that people who were initially less verbally intelligent may be more likely to smoke marijuana or that heavy marijuana use may have caused them to drop out of school and therefore they may have had less chance to learn. It didn’t note, however, that even a single marijuana-smoking incident can cause expulsion under some school zero tolerance policies; thus the connection could have to do with policies towards marijuana as much as it does with drugs.

Nor did the article include information on whether comparable levels of alcohol use or other drug use produce greater damage, which would have allowed readers to judge the relative risks for themselves.  In fact, heavy alcohol use can indisputably cause gross brain damage, while the data on marijuana and cognitive impairment is far less clear. 

People know that marijuana is simply less risky than other illicit drugs and alcohol: if the mainstream media wants credibility, it should stop pretending otherwise.