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Drivers With Common THC Limit Are Not More Likely To Cause Accidents, Study Finds

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To deter impaired driving in areas where marijuana use is legal, several jurisdictions have set per se limits ranging from 2 to 5 nanograms of THC per milliliter in motorists’ blood. New research, however, finds no evidence that drivers whose blood samples tested in that range are more likely to cause a traffic accident.

The study, published last month in the journal Addiction by a team of Canadian researchers, supports a key message relayed in a recent U.S. Congressional Research Service report on marijuana’s impact on driving: That is, experts aren’t convinced yet that cannabis use is associated with a higher risk of crashes.

“In this multi-site observational study of non-fatally injured drivers,” the study’s authors write, “we found no increase in crash risk, after adjustment for age, sex, and use of other impairing substances, in drivers with THC<5ng/mL.”

There may be an increased risk of crash responsibility for drivers with greater than that amount, the paper concluded, but it was “statistically non-significant and further study is required.”

“[T]here was no evidence of increased crash risk in drivers with THC<5ng/mL and a statistically non‐significant increased risk of crash responsibility in drivers with THC≄5ng/mL.”

While the authors acknowledge a number of other studies that have linked marijuana consumption with increased road safety risks, they also argue that those analyses have “significant limitations,” including the ways those experiments were conducted.

For the new study, researchers utilized a responsibility analysis design, which they said helped them avoid bias. The blood they analyzed for THC and other impairing substances, for example, came from excess samples gathered by treating physicians at hospitals following drivers’ accidents. To determine whether or not a driver was responsible for a crash, they looked at police reports and scored them using a computerized algorithm.

The authors sampled car crash patients from seven British Columbia trauma centers from January 2010 to July 2016 and ultimately tested the blood of 2,318 drivers who had police reports associated with their car accidents.

According to their results, 886 drivers were found to have at least one substance in their blood sample that may have impacted their ability to drive safely. “Alcohol was detected in 334 drivers (14.4%), THC in 192 (8.3%), other recreational drugs in 207 (8.9%), and sedating medications in 460 (19.8%),” the study states. “Polysubstance use was common and many drivers (11.4%) tested positive for more than one impairing substance.” Overall, more than half of drivers (1,178) were deemed responsible for the crash.

Among those drivers whose blood samples included THC—less than 2 ng/mL and up to 5 ng/mL—the study’s authors found there were “non-statistically significant increases in unadjusted risk of responsibility.”

“Our findings, of a low prevalence of drivers with THC>5 ng/mL, combined with a modest and statistically nonsignificant risk of crash responsibility, suggest that the impact of cannabis on road safety is relatively small at present time,” they write.

When the authors modeled THC as a continuous variable—meaning, the possible factors impacting their analysis were infinite— they found “there was a statistically significant but small increase in unadjusted risk for each 1ng/mL increase in THC. However, after adjustment for other predictors, there was no statistically significant association between THC level and risk of responsibility.”

There was, however, “significantly increased risk in drivers who had used alcohol, sedating medications, or recreational drugs other than cannabis.” As a result, “the road safety risk associated with alcohol or with other impairing substances is higher than for cannabis.”

But, as the authors point out, it’s possible crash risk may increase following legalization: As more people gain access to marijuana, it’s likely more people will drive after using the substance, including “occasional users with less tolerance to the impairing effects of cannabis.” In particular, they note, the risks for traffic accidents may be higher for younger drivers or inexperienced cannabis consumers.

They also caution that their findings don’t “necessarily apply to fatal crashes where the association with cannabis may be stronger.” Past research, however, has found that marijuana legalization is not associated with an increase in traffic fatalities.

Study co-author Dr. Jeff Brubacher, an associate professor of emergency medicine at the University of British Columbia, said in an interview released prior to the completion of the new research that marijuana consumption does impact a person’s ability to drive. And he strongly cautioned against getting behind the wheel after using any form of cannabis.

“Marijuana affects motor ability—reaction times are slower so people can’t respond quickly enough to a dangerous situation,” Brubacher said. “Drivers who have used cannabis may have trouble staying in their lane and tend to weave. The ability to maintain a consistent speed is also impaired and they tend to slow down and speed up erratically. Marijuana also makes for a more easily distracted driver.”

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Kimberly Lawson is a former altweekly newspaper editor turned freelance writer based in Georgia. Her writing has been featured in the New York Times, O magazine, Broadly, Rewire.News, The Week and more.

Science & Health

Federal Data Shows Youth Marijuana Use Isn’t Increasing Under Legalization

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Despite prohibitionists’ often-expressed fears that legalization would lead more young people to use marijuana, new federal data released on Tuesday shows no such trend.

Reports of past-month cannabis use among those 12-17 remained stable from 2017 to 2018—and they’re significantly lower than in the years prior to when the first states began legalizing for adult use.

That’s according to the 2018 National Survey on Drug Use and Health (NSDUH), an annual report produced by the Substance Abuse and Mental Health Services Administration (SAMHSA).

“The percentage of adolescents in 2018 who used marijuana in the past year was lower than the percentages in 2002 to 2004 and in 2009 to 2013, but it was similar to the percentages in 2005 to 2008 and in 2014 to 2017,” SAMHSA said.

Via SAMHSA.

Recent studies that have used NSDUH data and other sources also demonstrate that youth marijuana use is not increasing post-legalization. In fact, research published in JAMA Pediatrics in July found that states with recreational cannabis experience a decline in underage marijuana use, with the study authors stating that regulated markets appear to deter illicit use.

Indeed, on a national scale, the percentage of adolescents who reported using marijuana began declining at a greater rate in the years after states started implementing legal cannabis systems. In 2018, 12.5 percent of those 12-17 said they used cannabis in the last month, compared to 13.5 percent in 2012, according to the NSDUH results.

Colorado and Washington State became the first U.S. states to vote to legalize marijuana for recreational use in late 2012, with legal sales commencing in 2014.

Between 2002 and 2018, the highest rate of adolescent marijuana use took place in 2002, when 15.8 percent reported past-month consumption.

“The survey results suggest that marijuana use among youth has remained stable and low in recent years, even as more states legalize medical and adult use,” Sheila Vakharia, PhD, deputy director of the Drug Policy Alliance’s Department of Research and Academic Engagement, told Marijuana Moment. “Rather than encouraging increased use, it is possible that legalization has limited access and deterred youth use. We find that these results strengthen the case for legalization in the interest of public health and protecting our nation’s young people.”

What’s more, the report found that cases of cannabis use disorder declined again for the 12-17 group in 2018, marking the seventh year in a row that fewer young people seem to be misusing the substance.

Via SAMHSA.

Interestingly, these trends are developing even as people’s perceptions of the risks of casual marijuana consumption are dropping. That seems to contradict an argument from reform opponents who claimed that legalizing cannabis would normalize it in such a way that underage individuals would feel more emboldened to experiment with marijuana.

Via SAMHSA.

Overall, marijuana consumption increased across age groups by about one percentage point over the past year, the survey found, with the bulk of that rise being attributable to those over 26. Past-month cannabis use for that demographic increased from 12.2 percent in 2017 to 13.3 percent in 2018.

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This story was updated to include comment from the Drug Policy Alliance.

Photo courtesy of Philip Steffan.

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Federal Health Agency Releases List Of Marijuana Research Priorities

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In one of the latest signs that the federal government is recognizing the reality of the marijuana legalization movement’s continued success, a top health agency released an extensive list of cannabis-related research objectives it hopes to fund.

The notice, published on Wednesday, notes the rapid evolution of marijuana policies in the U.S. and globally, which is “far outpacing the knowledge needed to determine and minimize the public health impacts of these changes.”

“A growing number of states have loosened restrictions on cannabis, including those on sales and use, by passing medical marijuana laws or by making cannabis legal for adult recreational use, and in some cases, states have done both,” the National Institute on Drug Abuse (NIDA) wrote.

It also referenced a 2018 report from a cannabis policy working group that was tasked with identifying “cannabis policy research areas with the greatest urgency and potential for impact.”

Evidently, there are quite a few areas that fit that description, as NIDA listed 13 research objectives of “programmatic interest.” And while the agency has previously called for studies into several areas that are featured on the notice, there are others that signal NIDA is evolving in its understanding of research needs as more states opt to legalize.

For example, NIDA is not simply focusing on providing grants to explore the health risks of cannabis use, it’s also interested in learning about “reasons for initiation and continued use of marijuana for therapeutic purposes” as well as investigating “how cannabis industry practices, including research on marketing, taxes, and prices, impact use and health outcomes.”

The agency also wants to fund studies that look at the differences in legal marijuana regulatory schemes in various jurisdictions to “understand which combinations or components minimize harm to public health.”

Other research goals NIDA described include exploring the impact of cannabis use during pregnancy and developing roadside testing instruments to identify THC impaired drivers as well as standards to measure marijuana dosing.

Here’s the full list of research objectives: 

—Develop standards for measuring cannabis (including hemp and hemp product) dose, intoxication, and impairment.

—Enhance existing epidemiology research to study trends for cannabis use and CUD; including new products, patterns of use, and reasons for use in different populations.

—Characterize the composition/potency of cannabis, methods of administration, cannabis extracts/concentrates, and cannabis of varying constituents (e.g. cannabinoid or terpene content), as well as how those factors impact physical and mental health.

—Determine the physical and mental health antecedents of use, as well as outcomes of use.

—Explore the impact of polysubstance use on health outcomes, including interactions (substitution/complementation) with alcohol, tobacco, and prescription and nonprescription opioids.

—Examine reasons for initiation and continued use of marijuana for therapeutic purposes.

—Investigate the effects of different patterns of cannabis use on brain development, educational attainment, and transition to work and adult roles.

—Identify the effects of maternal cannabis consumption during pregnancy and breastfeeding.

—Develop effective roadside tests for cannabis impairment that can be practically deployed by law enforcement.

—Determine the prevalence of cannabis-involved vehicular crashes and other types of injury or property damage.

—Investigate how cannabis industry practices, including research on marketing, taxes, and prices, impact use and health outcomes (e.g. how different price points impact consumption patterns across different levels of use).

—Determine the impact of federal, state, and local marijuana policies and their implementation on use and health outcomes.

—Explore the heterogeneity of regulatory schemes (e.g. models for retail distribution of cannabis) to understand which combinations or components minimize harm to public health.

A number of federal health agencies have issued several notices for marijuana-related research opportunities in recent months. One that received particular attention came from NIDA in May, when it said applications were open for what is essentially a professional research-grade marijuana joint roller and analyst position.

While NIDA said that research isn’t keeping up with the rapid reform movement, its director also acknowledged in April that the federal drug scheduling system—which regards cannabis as a tightly restricted Schedule I drug—has inhibited such research by making it difficult for scientists to access marijuana.

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Photo by Aphiwat chuangchoem.

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Science & Health

Study Reviews How Marijuana Compounds Inhibit Tumor Growth And Kill Cancer Cells

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A recent scientific review concludes that marijuana’s legal status should be revisited given existing research that shows cannabis’s components can inhibit tumor growth and help with cancer management.

Researchers at Amity University in India detailed the scientific literature surrounding the effects of cannabinoids on different cancer types and also looked at marijuana’s anti-nausea, appetite stimulation and pain relieving qualities.

Besides treating symptoms of chemotherapy side effects, cannabis also shows potential in slowing the growth of cancer cells and even kill cancer cells in certain cases, the researchers wrote.

“THC and CBD exhibit effective analgesic, anxiolytic, and appetite-stimulating effect on patients suffering from cancer.”

But that’s not all. “Apart from exerting palliative effects, THC also shows promising role in the treatment of cancer growth, neurodegenerative diseases (multiple sclerosis and Alzheimer’s disease), and alcohol addiction and hence should be exploited for potential benefits,” an abstract of the study, published in the Journal of Cancer Research and Therapeutics, states.

The majority of the studies that were reviewed were based on in vitro experiments, meaning they did not involve human subjects but rather isolated cancer cells from humans, while some of the research used mice.

Cannabinoids appear to “exert potent [anti-growth] activity and activate various apoptotic mechanisms eventually leading to cell death” of cancer cells associated with glioma, an aggressive form of brain cancer.

At least once clinical trial showed that patients with recurrent glioblastoma multiforme who were treated with a “proprietary combination of THC and CBD” in addition to a traditional pharmaceutical had a higher one-year survival rate (83 percent) compared to a placebo group (53 percent).

Another study found blood cancer cells that were treated with two synthetic endocannabinoids activated receptors that “mediated apoptosis,” or the death of the cells.

In certain cell lines of prostate cancer, similar findings were observed. There was “[s]ignificant cell growth inhibition followed by apoptosis” in one particular cancer cell type in a “study which was designed to evaluate the in vitro effects of endocannabinioids such as 2-arachidonoyl glycerol, anadamine, and its synthetic analog methazolamide.”

Less research has been conducted on the effects of cannabis on lung, breast, oral and liver cancers, but the study authors documented instances where mice with certain lung cancer types treated with THC experienced a “notable reduction of the subcutaneous tumor growth and lung metastasis” of those cells, “prompting its significance as a novel therapeutic molecule in lung cancer treatment.”

But while THC is a common study focus, other cannabinoids show particular potential in treating different cancer types, they found. For example, a synthetic CBD compound (940-CBD) was the most effective “in terms of antiproliferative effects and invasiveness” of a particular breast cancer cell line.

When treated with THC, an oral cancer cell line that’s “highly resistant to anticancer drugs,” showed increased “cellular respiration inhibition,” whereas another conventional treatment option “showed no such effect.”

While researchers have investigated a wide range of cancer treatments, “the utilization of THC and their derivatives is still unexplored pharmacologically owing to their ‘habit-forming’ nature,” the researchers concluded. “Specific targeting of cannabinoid receptors can be used to manage severe side effects during chemotherapy, palliative care and overall cancer management.”

“Furthermore, research evidences on cannabinoids have suggested tumor inhibiting and suppressing properties which warrant reconsidering legality of the substance,” they said. “Studies on [cannabinoid] receptors, in case of cancers, have demonstrated the psychoactive constituents of cannabinoids to be potent against tumor growth.”

Because the activation of CB1 and CBD2 cannabinoid receptors “tends to limit human cancer cell growth,” there may be a “role of the endocannabinoid system as a novel target for treatment of cancers” and “[f]urther explorations are required to exploit cannabinoids for an effective cancer management.”

The findings reflect another recent study that also explored the therapeutic potential of cannabis extracts in the treatment of different cancers. Like this new review, it demonstrated that while variation in cannabinoids that are used to treat distinct cancer cell lines is an important consideration, the growing data on marijuana’s ability to inhibit cell growth and kill cancer cells indicates that it should be a major area of research going forward.

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