Health
Cannabis edibles cause driving impairment below standard legal THC limits, study finds
A clinical trial reveals that edible cannabis can significantly degrade driving performance despite leaving blood THC levels under common roadside testing thresholds.
The short version
- A study published in JAMA Network Open found that 10 mg and 20 mg doses of THC edibles impaired simulator driving performance at two and five hours post-consumption.
- Despite observable impairment in reaction times and lane control, average blood THC concentrations stayed below the common legal limit of 5 nanograms per milliliter.
- Researchers and experts note that because oral cannabis is metabolized differently than inhaled marijuana, standard roadside blood tests may fail to detect impaired drivers.
- The findings present a challenge for policymakers and law enforcement developing objective roadside sobriety standards.
Key facts
- Researchers at the Centre for Addiction and Mental Health in Toronto conducted a trial with 40 healthy adult volunteers who regularly consume cannabis, testing them on driving simulators after taking gummies with 0, 2, 10, or 20 mg of THC.[Fox News]
- Participants taking 10 mg and 20 mg doses exhibited increased lane variability, slower reaction times, and less consistent speed control at two and five hours post-consumption.[Fox News]
- Peak blood THC levels averaged 1.6 ng/mL for the 10 mg dose and 3.4 ng/mL for the 20 mg dose, remaining beneath the common 5 ng/mL legal cutoff.[Fox News]
- In a prior study by the same research group, smoked cannabis produced comparable driving impairment but resulted in an average peak blood THC concentration of 30.3 ng/mL.[Fox News]
What remains uncertain
- The trial was conducted solely on virtual simulators with regular cannabis users, leaving real-world road performance and effects on occasional users unverified.[Fox News]