Vaping cannabis can impair driving, study shows

Daily News Article   —   Posted on December 3, 2020

(by Brian P. Dunleavy, UPI) — Drivers who vape THC or a combination of THC and CBD show signs of “modest” impairment up to four hours later, a study published Tuesday by JAMA found. (JAMA is the Journal of the American Medical Association.)

The impairment from vaping compounds containing the main ingredients of marijuana (THC and CBD) is equivalent to that seen in drivers with blood alcohol concentrations of 0.05%, or roughly half the legal limit for driving under the influence in most states, the researchers said.

Compounds containing higher amounts of tetrahydrocannabinol, or THC, “are typically used for intoxication,” while those with cannabidiol, or CBD, which are not intoxicating, are prescribed for the treatment of epilepsy, anxiety, psychosis and neurological disorders, they said.

While researchers in the new study had participants vape cannabis oil, previous studies have linked any marijuana consumption — smoking flower, vaping or using edibles, among other methods — to a higher risk for car accidents.

“[Our] study shows that cannabis-induced driving impairment varies with cannabis strains,” study co-author Dr. Johannes Ramaekers told UPI.

“The implication for the general public is that the cannabis-induced driving impairment should be acknowledged as a public health risk, while taking into account that impairment may differ between cannabis strains and depends on time after use,” said Ramaekers, professor of psychopharmacology and behavioral toxicology at Maastricht University in the Netherlands.

…The sale of CBD-based products is legal in all 50 states, though some states require a doctor’s prescription, according to…ProCon .org.

Meanwhile, 33 states have legalized “medical marijuana”…and 15 states, as well as Washington, D.C., allow the drug to be used for both medical and recreational purposes, the site says.

Although some studies have linked CBD use with increased accident risk while driving, its effect on driving performance remains unclear, Ramaekers and his colleagues said.  …..

Published at UPI .com. Reprinted here for educational purposes only. May not be reproduced on other websites without permission from United Press International.


From the UPI article above:

For this study, 22 adults completed eight, 60-mile on-road driving tests 40 minutes and four hours after cannabis consumption.

Some participants used vaping devices containing either 13.75 mg each of THC and CBD, 13.75 mg of THC alone or 13.75 of CBD alone, while others were given a placebo containing neither of the ingredients, the researchers said.

These amounts are roughly equivalent to the levels found in one-third of a marijuana cigarette or "joint," according to industry publication High Times.

Participants' driving was evaluated based on standard deviation of lateral position -- a standard measure of "lane weaving" -- the researchers said.

At 40 to 100 minutes following consumption, standard deviation of lateral position was 7.2 inches with CBD-dominant cannabis, 8.1 inches with THC-dominant cannabis, 8.3 inches with THC/CBD-equivalent cannabis and 7.2 inches with a placebo, the data showed.

At four to five hours following consumption, standard deviation of lateral position was 7.5 inches with CBD-dominant cannabis, 7.8 inches with THC-dominant cannabis, 8.1 inches with THC/CBD-equivalent cannabis and 7.6 inches with placebo cannabis.

In general, impairment following cannabis use "was modest in magnitude" and similar to that seen in drivers with a 0.05% blood alcohol content, they said.

Still, even with this "modest" impairment, "driving after consumption of THC dominant cannabis is not safe [and] CBD-induced driving impairment might occur at high doses," Ramaekers said.

From Cannabis and Impaired Driving - by Thomas B. Cole, MD, MPH; Richard Saitz, MD, MPH (Dec. 1, 2020)

  • Impaired driving is a major cause of preventable death worldwide.
  • Alcohol-impaired driving accounted for a mean of 19% (range, 3%-34%) of the motor vehicle crash deaths in 20 countries in 20161; in 2018, 29% of the 36 560 crash deaths in the US were attributed to impaired driving.
  • By comparison, driving under the influence of cannabis was estimated to account for 8700 road traffic deaths worldwide in 2013.
  • Alcohol and cannabis are often consumed together, and their combined use is associated with greater crash risk than the use of either substance alone.
  • Notably, cannabinoids are the most commonly detected other drugs (besides alcohol) in fatally injured drivers (up to 15% in urban areas), and the prevalence is increasing.