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Fatal car crashes rise on 4/20, but we can’t say why

Fatal car crashes rise on 4/20, but we can’t say why


We need better tests for marijuana intoxication

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cannabis (wikimedia)

The risk for deadly car crashes is higher on 4/20 — the unofficial holiday for cannabis culture, new research says. While the study can’t directly tie the crashes to pot use, the findings add to a growing body of research that suggests stoned driving can be dangerous.

Legal cannabis sales reportedly spike on April 20th, when people celebrate by getting blazed. When researchers compared the number of deadly car crashes on April 20th to crashes on other days in April, they found a 12 percent increased risk for fatal car accidents. The findings, reported today in the journal JAMA Internal Medicine, don’t necessarily mean that pot caused the crashes — because there’s no good test for cannabis intoxication. But they do mean that we need more research and public education about the risks of getting behind the wheel while stoned.

During holidays when people drink a lot, like July 4th, there are more deadly car accidents. So researchers at the University of British Columbia and the University of Toronto wanted to find out whether a holiday celebrating cannabis also saw a similar increase in fatal crashes. Several studies report that cannabis can slow reactions and blunt coordination, especially when combined with alcohol — which can make driving more dangerous.

The research team collected statistics about deadly car crashes in the US over 25 years starting in 1992, a year after a flier published in High Times made 4/20, the “High Holiday,” popular. Since ideally festivities start around 4:20PM, the research team compared crashes between 4:20 PM and midnight on April 20th to that same window of time on regular days in April. They found that there were an average of 7.1 crashes per hour on 4/20, compared to 6.4 crashes per hour on a more typical April day. Overall, that accounted for a 12 percent increased risk of a fatal car crash on 4/20.

The study has a few limitations. For example, most of the drivers weren’t actually tested for drug use — probably because there isn’t a reliable test for marijuana intoxication. Cannabis can stay in the body for days to weeks after last using it, which means blood tests aren’t a good way to measure acute intoxication. And breathalyzers haven’t made it from lab to roadside yet, although there’s promising early research that measures THC (pot’s main psychoactive ingredient) in breath. It’s also possible that there were simply more people on the road, driving longer distances.

So there’s still a lot more we need to learn. Today’s findings are a start — but without a better way to test for marijuana intoxication, we won’t be able to know which crashes can be directly linked to pot, and which can’t. That information is critical to passing more informed laws about stoned driving. And as recreational marijuana becomes legal in more and more states, clear, evidence-based policies will be key to keeping people safe on the road.