Apparently cellphones are not the only thing that cause car accidents.

A new study published in the British Medical Journal found a positive correlation between smoking marijuana and vehicle accident risks.

The study looked at reports from 49,411 car accident victims and evaluated which drivers either had traces of marijuana in their blood streams, or reported smoking marijuana up to three hours before driving. Those who had used the drug before driving were found to have twice the risk of being involved in a car accident, compared to non-users.

Researchers told CBC that more research is needed to truly determine how much marijuana affects driving ability, but confirm that there is a strong correlation shown in the data. They said smoking marijuana likely has less of an influence on driving danger than drinking alcohol, but that more tests are required.

Currently, it is tough to test for marijuana use in drivers because of difficulties in measuring the amount of key chemicals, including tetrahyrocannabinol (THC) in the bloodstream. One professor told CBC that there aren’t enough law enforcement efforts to deter people from driving after using marijuana.

via CBC News courtesy of Automobile Magazine Staff