Study: ‘THC Does Not Increase Risk Of Traffic Accidents’

Lawmakers worldwide debate the legalization of cannabis. As some may fear it will inevitably lead to a rise in cannabis-related traffic accidents. Though researchers recently concluded that THC from cannabis may not increase the risk of traffic accidents.

Cannabis In Traffic

Lawmakers worldwide debate the consequences legalization of cannabis may have. And where some think about the positive effects legal weed can have on the economy and well-being of the public – others focus on the possible negative effects. One of the most popular arguments against cannabis legalization is the consequences it might have on traffic-safety.

Because the belief is that THC, the main active component in cannabis, could increase the risk of traffic accidents. Though recent research from the University of British Columbia indicates otherwise.


In efforts to figure out how THC affects the risk on traffic accidents, researchers analyzed police reports from thousands of accidents. All of which occurred between 2010 and 2016 in British Columbia. In each case, drivers gave blood samples. Showing if and how much THC, Alcohol and ‘other impairing drugs and medications’ were consumed.

data analysis computer
Researchers analyzed data from traffic accidents between 2010 and 2016, to show the effects of THC on the risk on traffic accidents.

Finally, they compared these concentrations to the police reports in order to determine who was responsible for each crash. And subsequently, to determine who was ‘innocently involved’ or not responsible at all. But despite of the hypothesis that THC would increase the risk of traffic accidents, researchers concluded otherwise.

In their report, researchers say they ‘found no increase in crash risk, after adjustment for age, sex and use of other impairing substances, in drivers with THC levels less than 5 nanograms. For drivers with THC greater than 5ng, there may be an increased risk of crash responsibility. But this result is statistically non-significant and requires further study.’


In comparison to cannabis users, the study reports that drivers intoxicated by alcohol and other drugs had a much higher probability of causing traffic accidents. In other words: ‘the risk increases for drivers who use alcohol, sedating medications or recreational drugs other than cannabis.’

However, the study also reports that drivers with both THC and alcohol in their system, are more likely to cause an accident compared to alcohol alone. In conclusion, ‘our findings suggest that the impact of cannabis on road safety is relatively small at the present time.’

happy man in car
Conslusion: THC does not increase the risk of traffic accidents – unless it’s mixed with alcohol.

These results are similar to an earlier study published in the Frontiers of Pharmacology; concluding there is no link between cannabis-intoxicated driving and traffic accidents. Another study, comparing the number of traffic deaths in legal states with those in non-legal states, also found no association between legal weed and increased fatalities.

Don’t push your luck though! It is still illegal to smoke and drive.