HealthDay reporter
THURSDAY, Jan. 13, 2022 (HealthDay News) – Here’s more evidence that marijuana can make driving more dangerous: Because pots are legalized in more countries and states, more people are intoxicated by drugs and crashed , researchers report.
THC, the active ingredient in cannabis, has been found in twice as many injured Canadian drivers since 2018, when cannabis was first legalized. The same effect is observed in the United States, said lead researcher Dr. Jeffrey Brubacher, an associate professor in the Department of Emergency Medicine at the University of British Columbia in Vancouver.
A prominent American addiction expert agreed.
“This is an emerging and extremely important area of research,” said Dr. Nora Volkov, director of the US National Institute on Drug Abuse. “One recent study found increased levels of motor vehicle accidents in the six months following the medical cannabis permit in Canada, and another study found a relatively increased risk of fatal motor vehicle collisions by 15% and a relative increase in related deaths. of 16% in US jurisdictions where cannabis is legal, “she said.
As more and more countries seek to legalize marijuana, it is crucial to understand the impact of legalization on addiction and a number of other health outcomes, including driving accidents, in order to identify legalization strategies while minimizing the potential damage, “Volkov added. .
Brubacher said how much sweat is consumed before getting behind the wheel also matters.
“The increasing number of drivers using cannabis, especially drivers with high THC levels (5 nanograms / mL or more), is worrying,” he said. “But we can’t conclude that all these clashes were caused by cannabis.”
Previous studies have found no evidence that low THC levels (less than 5 ng / mL) are associated with an increased risk of causing a crash, Brubacher said.
“However, acute cannabis use causes cognitive deficits and psychomotor impairment, and there is evidence that drivers with THC levels of 5 ng / mL or more are at higher risk of accidents,” he said.
Delayed reaction time
These deficits lead to slow response times, lack of concentration and overflow, Brubacher said.
“We know that the risk of an accident is higher for drunk drivers than for drivers who use cannabis,” he said. “Some previous researchers have suggested that legalizing cannabis could improve road safety if drivers use cannabis instead of alcohol. Unfortunately, we found no evidence of a reduction in the percentage of injured drivers who tested positive for alcohol.”
Volkov noted that the effects of marijuana on the ability to drive are significant.
“Numerous studies have shown that marijuana significantly impairs many of the skills needed for safe driving, including judgment, motor coordination and response time. “Laboratory studies have also found a direct link between blood THC levels and difficulty driving,” she said.
“However, this study must be interpreted with caution, as it can be extremely difficult to establish a causal link for a car accident. This is because – unlike alcohol – there is no roadside test to measure drug levels in the body, “Volkov explained. “This means that the tests used to detect THC levels in drivers are often conducted hours after the accident. In addition, marijuana can be found in body fluids for days or weeks after the last use, and drivers often combine it with alcohol, making it difficult to identify. how important a role cannabis itself has played in a disaster. “
For the study, Brubacher and colleagues analyzed THC levels in blood samples from more than 4,300 injured drivers who were treated at trauma centers in British Columbia between 2013 and 2020.
Before the vessel was legalized, about 4% of drivers had blood levels of THC above the Canadian legal driving limit of 2 ng / mL. That percentage rose to nearly 9 percent 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 is observed in drivers over 50 years. No significant changes were observed in drivers who tested positive for alcohol, alone or in combination with THC, the researchers said.
Delayed driving is recommended
The percentage of those who drive both drunk and in an extreme state is about 2% before legalization and 3% after, the study authors found.
Blood THC levels usually peak at about 100 ng / mL within 15 minutes of smoking. Levels then fall rapidly, to less than 2 ng / mL within four hours of smoking. After ingesting edible THC, levels drop to an equally low concentration after eight hours, Brubacher said.
Based on these data, he advises people not to drive four hours after smoking a potty and eight hours after swallowing. Brubacher also warned that the combination of alcohol and a pot can be especially deadly behind the wheel.
“Although these figures are alarming and I think there is some cause for concern, it is not the sky to fall,” he said. “This is not as serious a problem as it would be if we saw a doubling of the number of drivers who use alcohol, because the risk is lower with THC than with alcohol.”
The same increase in marijuana use while driving has been observed in the United States in states where it is legalized.
According to Paul Armentano, deputy director of NORML, a group advocating for marijuana law reform in the United States, “Similar data on increased prevalence have been reported in some U.S. states, such as Washington, without a statistically significant increase in deaths in the United States.” traffic “
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 cannabis consumption on driving efficiency, and we believe that such campaigns should be an integral part of any law to legalize adult use,” said Armentano. “We also have a long history of calls for law enforcement to be provided with additional and more accurate tools and methods for identifying and discouraging DUIs. [driving under the influence] behavior of cannabis. “
The report was published on January 13 New England Medical Journal.
More information
Contact the U.S. National Institute on Drug Abuse for more information on marijuana and driving.
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 Medical Journal, January 13, 2022