04/07/2025
A decade ago, in 2015, a study by the US National Highway Traffic Safety Administration examined the crash risk associated with alcohol and drug use by drivers. The study used a case-controlled methodology.
Alcohol Findings
The study found that alcohol use by drivers was clearly associated with elevated risk of crash involvement:
• Drivers who had been drinking at the .08 breath alcohol concentration (BrAC) had about 4 times the risk of
crashing as sober drivers. NB: .08 BrAC and blood alcohol concentration [BAC] are the per se legal limit in
every US State.
• Drivers with alcohol levels at .15 BrAC had 12 times the risk.
Drug Findings
Drivers participating in the study were tested for a large number of potentially impairing drugs using both oral fluid (saliva) and blood samples. THC was the only single category for which study findings reached statistical significance. Drivers testing positive for THC were over-represented in the crash-involved (case) population. However, when demographic factors (age and gender) and alcohol use were controlled, the study did not find an increase in population-based crash risk associated with THC use.
The study was conducted in Virginia Beach, Virginia, over a 20-month period ending in 2012. More than 3,000 crash involved drivers were included as case subjects. Two control subjects were selected for each case subject by random selection from traffic at the same location, day of week, time of day and direction of traffic as the crash-involved case subjects. This careful matching of cases and controls was critical for the validity of the findings. About 66% of the case subjects were involved in property-damage-only crashes and 33% were involved in injury crashes. Less than 1% of case subjects were involved in fatal crashes. The study could not control for factors that could affect impairment by THC such as the amount ingested, the potency ingested, prior experience with THC and individual differences in response to THC.
In February, 2024, at the Centre for Mental Health and Brain Sciences, Swinburne University of Technology, Victoria, Australia, a semi-naturalistic, open-label study examining the effect of prescribed medical cannabis use on simulated driving performance was undertaken.
Driving performance outcomes including standard deviation of lateral position (SDLP), the standard deviation of speed (SDS), mean speed and steering variability were evaluated using the Forum8 driving simulator at baseline (pre-dosing), 2.5 h and 5 -h (post-dosing). Perceived driving effort (PDE) was self-reported after each drive. This semi-naturalistic study suggests that the consumption of medical cannabis containing THC (1.13-39.18 mg/dose) has a negligible impact on driving performance when used as prescribed.
Data was published in the Journal of Safety Research in December 2024 which evidenced that Australian patients who consume botanical cannabis over extended periods do not exhibit significant changes in their simulated driving performance.
“After vaporising one dose of their prescribed cannabis flower, participants exhibited no significant changes in performance on any of the video-based tasks (hazard perception skill, gap acceptance, following distance or speed) compared to baseline”, investigators reported. The study’s authors concluded, “The findings … suggest that a dose of vaporised cannabis (consumed in accordance with prescription) may not affect hazard perception ability or driving-related risk-taking behaviour among medicinal cannabis patients”.
So a decade ago it was shown THC (in particular) had no effect on crash-risk and the same can be said of more recent studies, with each and every one of them reiterating the fact that there is NO elevated risk, nor even any rate of impairment for a majority of cannabis users, medicinally prescribed using their medicine as per prescription or responsible adult-use (self-titrating and not driving if feeling in any way impaired [even though cannabis has been shown to be a mood altering substance, NOT an impairing one]).
So why are we still discriminating against those who choose an ancient, herbal medicine (used safely for thousands of years) which has been proven not to be a major causation factor in motor vehicle crashes? It is a simple question that has not been answered but the effects (or lack of them as the case may be) of THC on driving have been known for over a decade, quite conclusively.
We need the charade that THC is causative in motor vehicle crashes to cover law enforcement discriminating against a minority of mostly ill citizens to end. It is not only impinging on their civil rights but their human rights as well. That is not giving them a fair go, Albo and co.
https://hempedification.wordpress.com/2025/06/29/no-major-crash-risk-associated-with-thc/?utm_source=HEMP+Headlines&utm_campaign=1227beceba-EMAIL_CAMPAIGN_2025_662_03_07_25&utm_medium=email&utm_term=0_-67d9ec7ee8-577478486&mc_cid=1227beceba&mc_eid=56138d083d
Drug and Alcohol Crash Risk Study with A semi-naturalistic open-label study examining the effect of prescribed medical cannabis use on simulated driving performance
👇
https://pubmed.ncbi.nlm.nih.gov/38332655/
This semi-naturalistic study suggests that the consumption of medical cannabis containing THC (1.13-39.18 mg/dose) has a negligible impact on driving performance when used as prescribed.
