In November 2016, California voted in favor of Proposition 64, which legalized recreational cannabis for those above the age of 21. The legislation passed with 57 percent in favor, but the impact of cannabis use on those with brains yet to fully develop – and the associated risks it may pose on the roadways – should remain valid concerns for all of us.
The fight for legalization and the focus on the positive medicinal aspects of cannabis use obscured, in some ways, the issue of impairment. That doesn’t mean that it went away.
A 2013 study showed 34 percent of teenagers believe it is safe to use cannabis and drive.
In fact, over the last decade, awareness has increased around risks such as cannabis-induced psychosis (CIP), a substance-induced disorder recognized by the American Psychiatric Association that strikes at greater rate among people in late adolescence. Indeed, some studies suggest that cannabis can create subtle lasting neurobiological changes and accelerate mental illness, which often goes undiagnosed prior to age 25.
More concerning is the too-common misperception that cannabis does not cause impairment, and that it is safe to drive after using. One 2013 study showed that 34 percent of American teenagers hold this belief.
Obviously, not everyone will be impaired by a single puff or even a single joint, just as a single sip of alcohol or single drink won’t necessarily impair a driver. Cannabis impairment depends heavily upon dose amount, tolerance, and THC levels (the primary psycho-active ingredient).
But over the years, THC levels in cannabis have increased significantly. In the 1970s, the average joint contained less than 1 percent THC; today it is 15 percent. Colorado’s average recreational retail level is around 18 percent. Cannabis concentrates are even more concerning, ranging between 50-80 percent THC. Concentrates are