Opinion

One ex-pothead does not evidence for marijuana's dangers make

No, marijuana users don't cause a ton of traffic accidents or have lower IQs because of the drug

Susan Shapiro's anecdotal experience with cannabis — describing her past use as "an extreme addiction" — is anomalous. Most people who experiment with pot do not become dependent upon it. In truth, most users who try marijuana voluntarily cease their use as they grow older, enter the workplace or start a family.

That is because pot lacks the dependence liability associated with many other substances. According to the National Academy of Sciences Institute of Medicine, cannabis' risk of causing dependence is far lower than that of alcohol, opiates or tobacco. At worst, cannabis' potential dependence liability is on par with anxiolytics such as Valium or Xanax. Indeed, a minority of pot users experience difficulty kicking the habit, but that doesn't mean that we as a society should continue enforcing the failed policy of cannabis criminalization.

Many of Shapiro's claims regarding pot's risk potential are unsupported by the scientific literature. For instance, she expresses concerns that some cannabis products possess greater THC content today than in the past while ignoring the reality that most consumers regulate their intake accordingly. (When consuming more potent pot, most consumers typically ingest lesser quantities.) Further, THC itself is a comparatively nontoxic substance, having been approved as a medicine by the Food and Drug Administration in 1986 and descheduled by the U.S. Drug Enforcement Administration in 1999 (to a Class 3 drug from a Class 2) because of its stellar safety record. 

The author further asserts that cannabis "contributes" to 12% of traffic fatalities in the United States. But the purported source of this claim alleges nothing of the sort. In fact, the study in question solely assessed the prevalence of cannabis or its inert metabolites in injured drivers. (These metabolites, the authors state, may linger in the blood for up to a week following ingestion and should not be presumed to be a measurement of drug impairment.) The study's authors make no claims in regard to whether these drivers were under the influence of pot or whether their driving behavior was responsible for an accident. 

Further, studies evaluating whether marijuana-positive drivers are more likely to be culpable in traffic accidents find that the plant typically plays little role in auto fatalities. According to a 2012 review paper of 66 studies assessing drug-positive drivers and crash risk, marijuana-positive drivers possessed an odds-adjusted risk of traffic injury of 1.10 and an odds-adjusted risk of fatal accident of 1.26. This risk level was among the lowest of any drugs assessed by the study's author and it was comparable to the odds ratio associated with penicillin (1.12), antihistamines (1.12) and antidepressants (1.35). By contrast, a 2013 study published in the journal Injury Prevention reported that drivers with a blood alcohol content of 0.01% were "46% more likely to be officially blamed for a crash than are the sober drivers they collide with."

Shapiro also repeats the specious claim that cannabis use lowers intelligence quotient. But a review of a highly publicized 2012 study purporting to link adolescent pot use to lower IQ later in life determined that once economic variables were factored into the assessment, cannabis' actual effect was likely to be "zero." The findings of a previous longitudinal study from Canada that tracked the IQs of a group of marijuana users and non-users from birth similarly concluded, "Marijuana does not have a long-term negative impact on global intelligence."

This is not to allege that cannabis is harmless or that Shapiro is alone in her pot-centric struggles. But public policy should not be governed exclusively by trying to prevent the potential worst-case scenario. Further, if we are truly concerned with pot's potential societal impact and in particular its impact on the lives of adolescents, then the obvious public policy response is to regulate the substance in a manner that better restricts children's access and provides them with evidence-based information in regard to its potential risks. (Allegations such as Shapiro's sensationalist claim that "marijuana essentially fries your brain" don't cut it.)

This is the policy that we as a society have employed for alcohol and tobacco, two substances that possess known risks far greater than those posed by cannabis. And it has been successful. Adolescent alcohol and tobacco use now stand at historic lows. It's high time we as a society employ a similarly principled policy for cannabis.

Paul Armentano is the deputy director of the National Organization for the Reform of Marijuana Laws and coauthor of the book "Marijuana Is Safer: So Why Are We Driving People to Drink?" He is also a senior policy advisor for Freedom Leaf Inc. He lives in Vallejo.

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