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Marijuana Legalization Not Linked To Increased Traffic Deaths, Study Finds



Legalizing marijuana for medical or recreational purposes isn’t associated with an uptick in traffic fatalities, according to a new study released this month.

Kansas State University graduate student Andrew Young looked at data on average traffic fatalities over 23 years and used two models to assess the impact of cannabis reform on road safety.

“[L]egalizing marijuana is not found to be a statistically significant predictor of fatality rates,” he concluded. “This finding means that the legalization of marijuana for both medical and recreational purposes is not associated with either a reduction or increase in fatalities per 100,000 vehicle miles travelled.”

After conducting a regression analysis that turned up no evidence that state legalization efforts result in an increase or decrease in traffic fatalities, Young used a difference-in-difference model to compare the traffic fatality rates in legal cannabis states and control states. The more tailored analysis covered an eight-year timeline, starting five years before the state in question legalized marijuana.

No concrete trends emerged from that analysis.

In Arizona, where medical cannabis is legal, average traffic fatalities mirrored those of Wyoming and South Dakota, where marijuana is prohibited.


Via Kansas State University.

The fatal car accident rate was considerably higher in Colorado compared to Georgia and Iowa in 2001, but that trend started happening prior to medical cannabis legalization and also leveled out by 2003.


Via Kansas State University.

Traffic fatalities dropped in Washington D.C. following the City Council’s 2010 approval of medical cannabis, and were lower than in Utah or Virginia, which prohibit marijuana.


Via Kansas State University.

“The results of the analysis suggest that there is no statistically [significant] relationship between marijuana legalization and fatal crashes,” Young wrote. “These findings suggest that concerns of policy makers and the public that legalizing marijuana will worsen road safety are not entirely founded.”

“According to the difference-in-differences model, the recent upward trend of traffic fatality rates nationwide is not a result of medical marijuana legalization. In fact, the legalization of marijuana is not found to be a predictor of traffic fatalities,” he wrote.

The main limitation of the study, which has not been published in a peer-reviewed journal, concerns states where cannabis has been legalized for adult use. The small sample size, at least compared to medical marijuana states, means the analysis might not have been able to “fully estimate the impact of recreational cannabis on traffic safety.”

That said, the findings reflect those of several past studies that have also failed to identify a statistically significant relationship between legalization and road safety.

Another recent study also debunked the myth that traffic accidents spike on the cannabis holiday 4/20.


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Concerns about higher rates of impaired driving on the unofficial marijuana holiday 4/20 seem to be overblown, according to a new study accepted for publication in the journal Injury Prevention.

Some prior research has indicated that traffic fatalities spike on April 20—by as much as 12 percent—but the data supporting that claim has been limited in scope, the authors of the new paper said. So instead of singularly focusing on arbitrarily chosen control days one week before and after the daylong cannabis celebration for comparison, this latest study broadens the data pool.

Researchers at McGill University conducted three separate analyses. One compared traffic fatalities on 4/20 to control days one week before and after the holiday—the same data set used in prior research on the subject. Another considered both the one-week-apart control days as well as control days two weeks before and after the holiday. The last compared 4/20 traffic fatalities to the all the rest of the days in the year.

Then they took it another step, conducting the same analysis on five other major holidays.

“We found little evidence that the number of drivers involved in fatal traffic crashes are elevated on April 20 relative to any control period,” the researchers said. “This is not because daily crash rates are too noisy to detect any signal. On the contrary, we find important, systematic, and meaningful variation in the daily number of drivers involved in fatal traffic crashes across the period from 1975 to 2016.”

Traffic fatalities did seem to increase somewhat on 4/20 when looking at data from 1992 to 2016 and only comparing it to one-week control days, but “the magnitude of the estimate is consistent with the bulk of daily variations for many other days.”


Via Injury Prevention.

There were significantly more traffic crash fatalities on the 4th of July and the days before Labor Day and Thanksgiving. Interestingly, the analysis also showed that “systematically fewer drivers” were involved in fatal traffic accidents on Christmas and New Year’s Day.


Via Injury Prevention.

Over the years, the number of traffic fatalities on April 20 has remained relatively constant, which runs counter to expectations because if “recent celebrations of 4/20 were generating excess fatal crashes, we would expect to see a greater excess in recent years,” the researchers wrote.

“We conclude that there is limited evidence of any population-wide effects of the annual cannabis holiday on fatal traffic crashes.”

“The policy landscape for addressing marijuana-impaired driving is rapidly changing, and efforts to combat drugged driving are likely to require new initiatives,” they continued. “Given the considerable resources already devoted to heightened enforcement campaigns to reduce the impact of impaired driving, there does not seem to be sufficient evidence for including 4/20 among ‘risky’ days.”

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12 minutes ago, greensprout said:

the findings reflect those of several past studies that have also failed to identify a statistically significant relationship between legalization and road safety.


Found three examples of cannabis consumption directly impacting on driver safety in the first thing I clicked on..


Several reviews of driving and simulator studies have concluded that marijuana use by drivers is likely to result in decreased speed and fewer attempts to overtake, as well as increased “following distance”.


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I used to drive like an arsehole....

I had a girlfriend back in the '80's, she was only a five footer (I'm a six footer), a proper biker, she had a Bonneville I think, but she would NEVER take a pillion, not even me, and I was a bloody good pillion, she just never did, simple as that....

But in my car, she would complain about my driving style, I was always up the arse of the car in front, so often braking/accelerating and complaining about other bloody drivers for whatever reasn.... moron stuff.


Now..., the drive back from Manni Juana in Manchester over the moors to my home in north Notts, brilliant, happy to take my time... but more importantly, for decades now, I have never driven like an arsehole on someones bumper, I am more than happy to leave a large gap between me and the vehicle in front, and am well aware of the occaisional idiot in a hurry behind me, and happily give them the first safe opportunity to pass me with a flick of my left indicator... I want them off my arse, let them pass. :smokin:

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il admit that when it comes to motorcycles I drive like an absolute tit, cant help myself, ive got the cheek to do shoulder checks toppin 130+

 I always seemed to drive better when lightly stoned, seemed zoned in more or is it that I just think that ?love the challengeof hitting apexes and braking distances etc.

sold my bike because I just couldny help myself, sooner or later I would have killed some innocent party so super bikes are a no no

although I might settle for a big Harley or some british iron.


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4 minutes ago, The Budmeister said:

although I might settle for a big Harley or some british iron.

Biking no longer easy for me... but the thought of just cruising at 30/40 over the Saddleworth moors on a Bonny or a Commando.... bliss :) 


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