With a breathalyzer, it’s pretty easy to measure how much alcohol a person has consumed in a day. This is not the case with marijuana.
According to a new op-ed, it’s incredibly tricky to determine how much weed a person has consumed at any given time. It can be equally complex to figure out at what point a stoner has consumed so much that he’s impaired to drive.
With Canada legalizing weed and the United States looking like it’s going to follow suit, activists are increasingly calling for the introduction of roadside tests that would be similar to those of alcohol Breathalyzers in order to measure if someone is too impaired to drive. They are also calling on authorities to set up a legal marijuana limit, similar to that of alcohol.
However, according to a paper that was recently published in the journal called Trends in Molecular Medicine, this is not easy as one might think as the level of tetrahydrocannabinol (THC), the active compound in cannabis, doesn’t line up to show how impaired a person is. Marilyn Huestis, University of Maryland’s adjunct professor of epidemiology and public health, says that marijuana affects people in different ways. “One nanogram per millilitre of cannabis can impair some people, while others will not experience or have much impairment after taking 5 ng/ml,” said Huestis, one of the toxicologists who co-authored the paper.
The paper recommends that researchers need to develop a better understanding of the effects of THC and more than 500 other compounds found in the cannabis plant. For instance, there’s a need for researchers to check how long the human body takes to break down cannabinoids or to remove them from the blood system.
The researchers also wrote that there’s a need to study all the compounds and check how people’s behaviour changes as the compounds move through their system. Huestis told Live Science that cannabinoids are an important area of study as most researchers need to know the health conditions that these compounds can help to treat. As more countries and states legalize marijuana, most people are now faced with the choice about whether or not to use cannabis. However, says Huestis, they must understand the pros and cons of the drug.
Recent research reveals some surprising findings, indicating that THC indeed seems to linger for long in the blood systems of heavy cannabis consumers. Huestis says that THC can stay for up to 30 days in the blood system of a person even after they stop consuming the drug. She added that THC is stored together with body fats from where it’s released over time.
Surprisingly, THC remains so active that even when it’s finally released, its effects can still be felt. “Earlier all toxicologists thought that THC was flushed out of the blood system within 6-8 hours,” states Huestis. Technically, marijuana is different from alcohol: While alcohol dissolves in water and is easily flushed out, THC is usually stored in the body’s fat cells. With no easy way of flushing out THC from the cells, no THC test can clearly determine when a person has consumed weed. It could be that he or she did it a few hours ago — or two weeks ago.
Roadside challenge
That said, the best way to measure impaired driving caused by weed consumption is to use a two-step method.
First, the driver’s behaviour when driving should be documented and compared to their normal behaviour in order to check if their driving is impaired by weed. The second step is to conduct a blood or saliva test to determine some level of cannabis in their bloodstream. In this case, the exact amount of weed in the system is not an important factor.
Huestis says that the public should realize that weed leads to impaired driving. The drug is known to affect two regions of the human brain; cerebellum and basal ganglia. These regions’ job is to plan and control muscle movements needed to control a car when a person is driving. She says that when one is driving, one of the rules is to stay in one lane. “Cannabis encourages the driver to weave into lanes,” she says.
Cannabis also affects the brain’s executive function. Simply put, this is how the brain gathers information from senses, filtering what’s important and comparing that to memories and making a decision on how to act. Huestis says that when driving, so many unexpected things can happen and the brain needs some time to react, plan and execute an action that could potentially prevent a problem. Unfortunately, marijuana interferes with this process.
According to recent research, there’s no way of setting a legal limit on blood levels as far as marijuana is concerned. Huestis says she used to believe that toxicologists could come up with a limit, but after working with chronic frequent users, she realized that there’s no limit that distinguishes impairment.