“Neither blood nor oral fluid THC, CBD, or metabolites was significantly correlated with any measure of driving [performance],” investigators concluded.
Topic: Driving
“There are no empirically supported thresholds for blood or oral fluids that reliably indicate cannabis impairment,” investigators concluded.
“These results add to a growing body of evidence that per se THC blood statutes lack scientific credibility as prima facie evidence of impairment.”
Despite subjects’ lack of psychomotor impairment, researchers acknowledged that some participants tested positive for THC at levels classifying them as “under the influence” in several states.
“The introduction of recreational cannabis dispensaries did not lead to a significant rise in motor vehicle accident rates statewide or at the local level near cannabis dispensaries,” investigators concluded.
Consistent with prior studies, patients drove at slower speeds and increased the distance between their vehicle and the vehicles in front of them following THC dosing.
“These statistics suggest that although more drivers test positive for THC, alcohol remains the greater threat to road safety,” the study’s authors concluded.
The study did not identify any “statistically significant impacts of legalization” on car accident fatality rates, insurance claim frequency, or average costs per insurance claim.