Traffic crash injuries soar in areas where cannabis is legalised, new research has shown.
An investigation by the Insurance Institute for Highway Safety (IIHS) in Virginia, US, found a 5.8 per cent rise in crashes that caused injury, and a 4.1 per cent increase in fatal crash rates, in five states which allow recreational marijuana.
Colorado had the biggest jump in injury-inducing crashes, with a 17.8 per cent increase, while California had the smallest, with a rise of 5.7 per cent.
The researchers found no increase in a comparison group of states which did not legalise the drug.
There were also increases in fatal road traffic accidents in Colorado and Oregon, although other states, such as Nevada and Washington, saw falls, which researchers believe may be to do with the change in behaviour of intoxicated drivers.
Researchers said that drivers under the influence of marijuana often slow down and maintain a larger distance between themselves and other vehicles. While this can lead to the avoidance of fatal accidents, impaired drivers still cause dangerous smashes.
“The legalisation of marijuana doesn’t come without cost,” said lead researcher Dr Charles Farmer, of the IIHS.
“Users who previously avoided driving high may feel that it’s okay after legalisation.”
New laws to punish drivers high on cannabis
“First, [we need to] convince everyone that driving under the influence of marijuana is not okay. Then, enact laws and sanctions penalising those who ignore the message.”
For the new study, researchers collected data on traffic crashes and traffic volume for 2009 to 2019 from 11 states and from the Federal Highway Administration.
They compared Colorado, Washington, Oregon, California and Nevada which had legalised recreational marijuana during the study period, and compared them to Arizona, Idaho, Montana, New Mexico, Utah and Wyoming where the drug is still banned.
