THURSDAY, January 13, 2022 (HealthDay News) – Here’s more evidence that marijuana can make driving more dangerous: As weed is legalized in more countries and states, more and more people are driving under the influence of drugs and colliding, researchers report.
THC, the active ingredient in cannabis, has been detected in twice as many injured Canadian drivers since 2018. cannabis was first legalized. The same effect is seen in the United States, said lead researcher Dr. Jeffrey Brubacher, an associate professor in the emergency department at British Columbia University in Vancouver.
A prominent American addiction expert agreed.
“This is a new and extremely important area of research,” Dr. Nora Volkow, director of the U.S. National Institute on Drug Abuse, said in a statement. “One recent study showed an increased rate of motor vehicle crashes in the six months following medical cannabis approval in Canada, and another study found a relative increased risk of fatal motor vehicle crashes of 15% and a relative increase in related deaths of 16% in U.S. jurisdictions where cannabis is legal, “she said.
“As more and more states seek to legalize marijuana, it is crucial to understand the impact of legalization on addiction and a range of other health outcomes, including driving accidents, to determine strategies to implement legalization while minimizing potential harm,” Volkow added.
Brubacher said how many pots were drunk before he got behind the wheel is also important.
“Increased number of drivers who use cannabis, especially drivers with high THC levels (5 nanograms / mL or more) are worrying, “he said.” But we can’t conclude that all these collisions were caused by cannabis. “
Previous research has found no evidence that low THC levels (less than 5 ng / mL) are associated with an increased risk of collisions, Brubacher said.
“However, acute cannabis use causes cognitive deficits and psychomotor impairments, and there is evidence that drivers with a THC level of 5 ng / mL or more are at greater risk of collision,” he said.
Slow reaction time
These shortcomings lead to slow reaction times, lack of concentration and weaving along the way, Brubacher said.
“We know that the risk of a collision is higher in drunk drivers than in drivers who use cannabis,” he said. “Some previous researchers have suggested that legalizing cannabis can improve road safety if drivers use cannabis instead alcohol. Unfortunately, we found no evidence of a reduction in the percentage of injured drivers who tested positive alcohol. “
Volkow noted that the effects of marijuana on driving ability are significant.
“Numerous studies have shown that marijuana significantly impairs many of the skills needed for safe driving, including judgment, motor coordination and reaction time. Laboratory studies have also found a direct link between blood THC levels and reduced driving ability,” she said. .
“However, this research must be interpreted with caution, as it can be extremely difficult to determine the causality of any car accident. This is because – unlike alcohol – there is no road test to measure drug levels in the body,” Volkow explained. “This means that tests used to detect THC levels in drivers are often conducted hours after a collision. Furthermore, marijuana can be detected in body fluids days or weeks after the last use, and drivers often combine it with alcohol, making it difficult to discover how significant a role cannabis itself could have played in an accident. “
For the study, Brubacher and colleagues analyzed THC levels in blood samples from more than 4,300 injured drivers treated at British Columbia Trauma Centers between 2013 and 2020.
Before the pot was legalized, about 4% of drivers had blood THC levels above the Canadian legal driving limit of 2 ng / mL. That percentage rose to almost 9% after legalization, the researchers found.
The share of drivers with higher THC concentrations also increased, from 1% before legalization to 4% after.
The largest increase was recorded among drivers over the age of 50. No significant changes were observed in drivers who were positive for alcohol, either alone or in combination with THC, the researchers noted.
Delayed driving is advised
Percentage of those driving both drunk and was high at about 2% before legalization and 3% after, the study authors found.
Blood THC levels usually reach a maximum of about 100 ng / mL within 15 minutes of smoking weed. Levels then drop rapidly, to less than 2 ng / mL within four hours of smoking. After taking edible THC, levels drop to a similarly low concentration after eight hours, Brubacher said.
Based on this information, he advises people not to drive four hours after smoking weed and eight hours after drinking it. Brubacher also warned that the combination of alcohol and weed can be especially deadly behind the wheel.
“Although these figures are worrying, and I think there is reason for concern, the sky is not falling,” he said. “It’s not as serious a problem as it would be if we saw a doubling of the number of drivers who consumed alcohol, because the risk is lower with THC than with alcohol.”
The same increase in marijuana use while driving was recorded in the United States in the states where it is legalized.
According to Paul Armentan, deputy director of NORML, a group advocating for marijuana law reform in the United States, “Similar data on increasing prevalence have also been reported in some U.S. states, such as Washington, with no statistically significant increase in traffic deaths. “
Although testing for THC can be difficult, Armentano warned that people should not drive while feeling “bloated”.
“NORML has a long history of calling for targeted public education campaigns on the impact of acute cannabis consumption on driving performance, and we believe such campaigns should be an integral part of any adult legalization law,” Armentano said. “We also have a long history of calling for additional and more accurate law enforcement tools and methods to identify and discourage DUI [driving under the influence] cannabis behavior. “
The report was published Jan. 13 in New England Journal of Medicine.
For more information on marijuana and driving, go to the U.S. National Institute on Drug Abuse.
SOURCES: Jeffrey Brubacher, MD, Associate Professor, Department of Emergency Medicine, University of British Columbia, Vancouver, Canada; Paul Armentano, Deputy Director, NORML, Washington, DC; New England Journal of Medicine, January 13, 2022