Cannabis use as a risk factor for causing motor vehicle crashes: a prospective study

Cannabis Use As A Risk Factor

Cannabis Use As A Risk Factor



Cannabis Use As A Risk Factor, We conducted a responsibility analysis to determine whether drivers injured in motor vehicle collisions who test positive for Δ‐9‐tetrahydrocannabinol (THC) or other drugs are more likely to have contributed to the crash than those who test negative.


Prospective case–control study.


Trauma centres in British Columbia, Canada.


Injured drivers who required blood tests for clinical purposes following a motor vehicle collision.


Excess whole blood remaining after clinical use was obtained and broad‐spectrum toxicology testing performed. The analysis quantified alcohol and THC and gave semiquantitative levels of other impairing drugs and medications. Police crash reports were analysed to determine which drivers contributed to the crash (responsible) and which were ‘innocently involved’ (non‐responsible). We used unconditional logistic regression to determine the likelihood (odds ratio: OR) of crash responsibility in drivers with 0 < THC < 2 ng/ml, 2 ng/ml ≤ THC < 5 ng/ml and THC ≥ 5 ng/ml (all versus THC = 0 ng/ml). Risk estimates were adjusted for age, sex and presence of other impairing substances.


We obtained toxicology results on 3005 injured drivers and police reports on 2318. Alcohol was detected in 14.4% of drivers, THC in 8.3%, other drugs in 8.9% and sedating medications in 19.8%. There was no increased risk of crash responsibility in drivers with THC < 2 ng/ml or 2 ≤ THC < 5 ng/ml. In drivers with THC ≥ 5 ng/ml, the adjusted OR was 1.74 [95% confidence interval (CI) = 0.59–6.36; P = 0.35]. There was significantly increased risk of crash responsibility in drivers with blood alcohol concentration (BAC) ≥ 0.08% (OR = 6.00;95% CI = 3.87–9.75; P < 0.01), other recreational drugs detected (OR = 1.82;95% CI = 1.21–2.80; P < 0.01) or sedating medications detected (OR = 1.45; 95%CI = 1.11–1.91; P < 0.01).


In this sample of non‐fatally injured motor vehicle drivers in British Columbia, Canada, there was no evidence of increased crash risk in drivers with Δ‐9‐tetrahydrocannabinol < 5 ng/ml and a statistically non‐significant increased risk of crash responsibility (odds ratio = 1.74) in drivers with Δ‐9‐tetrahydrocannabinol ≥ 5 ng/ml.

Marijuana Use and Highway Safety

Marijuana Use And Highway Safety

Marijuana Use And Highway Safety

-Congressional Research Service

Marijuana Use And Highway Safety, A growing number of Americans report that they use marijuana. Most states now allow the use of marijuana for treatment of medical conditions. Ten states and the District of Columbia, representing a quarter of the U.S. population, have decriminalized the recreational use of marijuana, and other states are considering following suit.

As the opportunity for legal use of marijuana grows, there is concern about the impact of marijuana usage on highway safety. In a 2018 survey, the majority of state highway safety officers considered drugged driving an issue at least as important as driving while impaired by alcohol (which is associated with over 10,000 highway deaths each year). As of May 2019, 18 states have enacted laws declaring that a specified concentration of THC in a driver’s body constitutes evidence of impairment and is inherently illegal (referred to as per se laws), similar to the .08% blood alcohol content (BAC) standard of alcohol impairment.

Advocates of loosening restrictions on marijuana often compare marijuana usage to drinking alcohol, which may contribute to some stakeholders viewing marijuana use and driving as similar to alcohol’s impairment of driving. Research studies indicate that marijuana’s effects on drivers’ performance may vary from the effects of alcohol, in ways that challenge dealing with marijuana impairment and driving similarly to alcohol-impaired driving.

Marijuana legalization and road safety: a panel study of US States

Marijuana Legalization And Road Safety

Marijuana Legalization And Road Safety

Marijuana Legalization And Road Safety, Policymakers and the public are concerned about the road safety implications of legalizing marijuana. Despite the more than two decades of data since California became the first state to legalize marijuana for medical use, there has been surprisingly little research on this question.

This study seeks to address this gap in the literature. Specifically, this research combines twenty-three years of state traffic data with information on the contemporaneous legal status of marijuana, for both medical and recreational use, to estimate two models of road safety. First, while treating both the state and the year as fixed effects, the resulting panel regression model estimates that the legalization of medical or recreational marijuana is not a predictor of the number of fatalities per 100,000 vehicle-miles traveled.

Second, due to limitations in the regression model, a difference-in-difference analysis was conducted over the same period and found no relationship between legalization of medical marijuana and the number of fatalities per 100,000 vehicle-miles traveled. These findings suggest that concerns of policy makers and the public that legalizing marijuana will worsen road safety are not ungrounded at this time. According to the models, the recent upward trend of traffic fatality rates nationwide is not a result of medical marijuana legalization. In fact, the legalization of marijuana is not found to be a predictor of traffic fatalities.

The Annual Cannabis Holiday and Fatal Traffic Crashes

Cannabis Holiday And Fatal Crashes

Cannabis Holiday And Fatal Crashes



Cannabis Holiday And Fatal Crashes, Cannabis use has been linked to impaired driving and fatal accidents. Prior evidence suggests the potential for population-wide effects of the annual cannabis celebration on April 20th (“4/20”), but evidence to date is limited.


We used data from the Fatal Analysis Reporting System for the years 1975-2016 to estimate the impact of “4/20” on drivers involved in fatal traffic crashes occurring between 1620h and 2359h in the United States. We compared the effects of 4/20 to those for other major holidays, and evaluated whether the impact of “4/20” had changed in recent years.


Results: Between 1992-2016 “4/20” was associated with an increase in the number of drivers involved in fatal crashes (Incidence rate ratio [IRR]: 1.12, 95% CI 0.97 to 1.28) relative to control days one week before and after, but not when compared with control days one and two weeks before and after (IRR 1.05, 95% CI 0.92 to 1.28) or all days of the year (IRR 0.98, 95% CI 0.88 to 1.10). Across all years we found little evidence to distinguish excess drivers involved in fatal crashes on 4/20 from routine daily variations.


There is little evidence to suggest population-wide effects of the annual cannabis holiday on the number of drivers involved in fatal traffic crashes.

Crash Fatality Rates After Recreational Marijuana Legalization in Washington and Colorado

Fatality Rates After Legalization

Fatality Rates After Legalization



 To evaluate motor vehicle crash fatality rates in the first 2 states with recreational marijuana legalization and compare them with motor vehicle crash fatality rates in similar states without recreational marijuana legalization.


 We used the US Fatality Analysis Reporting System to determine the annual numbers of motor vehicle crash fatalities between 2009 and 2015 in Washington, Colorado, and 8 control states. We compared year-over-year changes in motor vehicle crash fatality rates (per billion vehicle miles traveled) before and after recreational marijuana legalization with a difference-in-differences approach that controlled for underlying time trends and state-specific population, economic, and traffic characteristics.


 Pre–recreational marijuana legalization annual changes in motor vehicle crash fatality rates for Washington and Colorado were similar to those for the control states. Post–recreational marijuana legalization changes in motor vehicle crash fatality rates for Washington and Colorado also did not significantly differ from those for the control states (adjusted difference-in-differences coefficient = +0.2 fatalities/billion vehicle miles traveled; 95% confidence interval = −0.4, +0.9).


 Three years after recreational marijuana legalization, changes in motor vehicle crash fatality rates for Washington and Colorado were not statistically different from those in similar states without recreational marijuana legalization. Future studies over a longer time remain warranted.

Alcohol-Related Car Crashes Declined In Idaho After Washington Legalized Marijuana Next Door

Crashes Declined After Legalized Marijuana

Crashes Declined After Legalized Marijuana

Crashes Declined After Legalized Marijuana.

Are alcohol and marijuana substitutes? For years, there has been extensive academic debate in the literature of medicine, public policy, and economics on the relationship between the two substances. The recent legalization of marijuana by several states provides new opportunities to study the relationship between marijuana and alcohol and the public health effects of legalization in neighboring states. This research examines the effects of Washington’s legalization of marijuana on alcohol consumption in neighboring Idaho.

Legalization in Washington spurred interest in marijuana dispensaries in Idaho

Using data from Google searches, Dr. Hansen identifies a significant increase in the number of web searches for dispensaries by individuals in Idaho after the legalization. This demonstrates an increased interest in marijuana products in Washington’s neighboring state.

Legalization in Washington reduced alcohol-related car crashes in Idaho

Using data on vehicle miles traveled and car crashes in Idaho, Dr. Hansen finds that the number of crashes involving alcohol decreased by 18 percent after the legalization of marijuana in Washington. This finding fades out for Idaho counties as the distance from Washington increases and provides evidence of consumers substituting marijuana for alcohol.

For Idaho counties that directly border Washington, the legalization of marijuana reduced car crashes involving alcohol by 21%.

For Idaho counties one hour away from Washington, the legalization of marijuana reduced car crashes involving alcohol by 18%.

For Idaho counties three hours away from Washington, the legalization of marijuana reduced car crashes involving alcohol by 10%.

For Idaho counties six hours away from Washington, the legalization of marijuana was not associated with a reduction in car crashes involving alcohol.

Dr. Hansen’s research suggests that marijuana and alcohol are substitutes. As marijuana becomes easier for consumers to access, individuals, drink less, as seen in fewer alcohol-related car crashes in Idaho. Policymakers should consider that there are trade-offs involved in setting drug and alcohol policies that influence public safety and the prevalence of dangerous driving.

Group wants Camas voters to reverse city’s ban on cannabis retail shops

Camas Washougal Post Article

Camas Washougal Post Article

Camas-Washougal Post Record Article, February 27th, 2020

Political action committee, launched by New Vansterdam owners, hopes to get issue on November ballot.

Camas Washougal Post Article

When the issue of legalizing cannabis came before Washington voters in 2012, nearly half of Camas voters — 47 percent overall and more than 50 percent in the city’s Ward 1 — supported decriminalizing the drug. But when the issue of opening the one cannabis retail shop allowed in Camas under the state ordinance came before city council members in 2015, the council voted 5-2 to ban marijuana shops within city limits. Now, the owners of a popular Vancouver cannabis shop hope to reverse that decision.

Rachel and James Bean own the New Vansterdam cannabis retail shop located off Mill Plain Boulevard and hold the the lone cannabis retailer license available in Camas. Although the Beans would love to see Camas officials lift the 2015 retailer ban, they are prepared to take the issue to the city’s voters through a local ballot measure process.

“We would hope this could be resolved with the city council. I believe it would just take a little more education and more discussion,” said Rachel Bean. “But we will be moving forward with the (voter) initiative either way.”

Bean and her physician husband have formed the Camas for Cannabis Access political action committee (PAC) to gather the 2,377 Camas voter signatures needed to place the issue on the November general election ballot.

“We’ve been kind of sitting back a little, waiting and trying to work with the city council,” Bean said. “We have three other stores (in Vancouver, Tacoma and Wenatchee), so we were pretty busy and (the Camas license) wasn’t a high priority for us. But this year, with the big election, it seemed like the year to jump on this.”

Terah Pitchford is leading the Camas for Cannabis Access outreach efforts.

A Camas native who now lives in Vancouver, Pitchford became involved in cannabis-legalization activism in 2008, after surviving a violent home invasion linked to the illicit marijuana trade. Home invaders mistook the home Pitchford, then a 19-year-old Clark College student, shared with roommates as being the site of an illegal stash of marijuana.

“Masked gang members held me hostage,” Pitchford said of the incident that led her into cannabis activism. “Afterward, I started thinking about the reasons why cannabis was illegal and about the people involved in violent crimes connected to the illicit cannabis market.”

Pitchford participated in early efforts to legalize cannabis in Washington state, and said she has seen a shift in people’s perception of marijuana since Washington voters approved Initiative 502, a measure that decriminalized recreational marijuana, in November 2012.

“People have been able to see what it looks like to go into a cannabis store, to see that these shops are a functional part of the community,” Pitchford said. “There is less stigma.”

Rachel Bean agreed.

“People have become much more open to the idea of retail cannabis,” she said. “I think things have changed drastically since 2012, when legalization was passed, and even more since stores started opening in 2014.”

Bean said people’s attitudes toward cannabis also is shifting as health providers start to understand the medicinal benefits of the herb, and as more research is conducted on cannabis’ ability to help with pain management, cancer treatments and opioid addiction.

“Time and time again, I see people coming into the shop for the first time, including a lot of the elderly population, and they’re looking to try new things to help whatever ailment they might have. They have doctors telling them to try these new things,” Bean said. “(Cannabis) has become less taboo and more of an actual medicine that is helping people.”

Pitchford said the Camas for Cannabis Access PAC is training workers to collect signatures and help educate Camas voters about the legal cannabis industry and the benefits of having a cannabis retail shop within the city limits.

“This is really about access,” Pitchford said. “We know the support exists in Camas.”

Armed with statistics and research showing that legalizing marijuana has helped reduce marijuana use among teens, led to a reduction in violent crimes, provided living-wage jobs — New Vansterdam, Bean said, pays more than a living wage and provides a full range of benefits to its 20 employees — and helped bring millions of dollars in tax revenue to cities and counties that allow cannabis retailers, the Camas for Cannabis Access PAC is gearing up to attend local events and collect signatures to get the issue onto the November ballot.

“We want to be very respectful and help educate people,” Pitchford said. “A lot of the (signature collectors) have worked in the industry and are knowledgeable about cannabis and cannabis retail, so they will be able to answer questions people might have.”

The Beans, who live in Vancouver, said they hope Camas voters and officials will see them for who they are — professionals who run successful cannabis businesses in other Washington cities.

“I’d like people to know that we are a part of the community and that we respect the people and businesses around us,” Rachel Bean said. “We don’t want people to be concerned about who is holding this license.”

Already, the Beans have made a concession that they didn’t have to make — agreeing to not site the cannabis store in historic, downtown Camas if voters approve the initiative or if city council members decide to overturn their 2015 cannabis retail ban.

“That wasn’t something we had to do, but we had heard from council members that (not having a cannabis retailer) in the historic district was important to their constituents, so that was something we were more than happy to respect,” Rachel Bean said.

Pitchford said she hopes to get more information out to the Camas community about cannabis that will help dispel some of the fears and myths surrounding the drug. For instance, she said, although many people have said they worry that having a legal cannabis shop in Camas will lead to greater marijuana usage by children, the facts show otherwise.

“I’m the mother of two young children, so I understand why they would be concerned,” Pitchford said. “But when you look at the studies, including the Healthy Youth Survey that is done in Clark County, there is a decrease (in marijuana use among teens and children) and that is a direct result of legalizing cannabis. They just can’t get it anymore. The shops are very strict about that. Some of them even have scanners to make sure the IDs (for those over the age of 21) are real.”

During the 2015 hearing that led to the city’s ban on cannabis retailers, only two Camas officials — current Councilwoman Melissa Smith and former Camas Mayor Shannon Turk — voted against the ban.

“It will be a novelty at first for some, but as more people are aware of it I think it will de-stigmatize it,” Smith said in 2015, adding that she had researched cannabis several years prior, after receiving a doctor’s prescription for marijuana to treat pain.

Other council members who still serve as elected officials, including Councilman Don Chaney, spoke in favor of the ban in 2015.

“It’s not about the use or possession of marijuana, at least as far as I’m concerned,” Chaney said in 2015. “And it’s not about the personal qualities or business opportunities of the proponents. That’s not an issue here for me. The issue is, what’s it going to do to our community, and how does the fact that we do or do not (allow retail marijuana businesses) reflect the culture of our community?”

Washougal city officials also have banned cannabis retail operations, and both Camas and Washougal have bans in place on the growing and processing of retail marijuana within city limits. To learn more about the Camas for Cannabis Access group and its efforts, visit and listen to XRAY FM’s interview with Rachel Bean and Pitchford. The group plans to launch a website soon and will have social media sites up and running within the next few weeks.

Original Source of the Camas Washougal Post Article

Support for marijuana legalization is at an all-time high in a new poll

Marijuana legalization Support Soars

Marijuana legalization Support Soars

Marijuana legalization Support Soars, Two-thirds of Americans support marijuana legalization, according to two recent polls.

The overwhelming majority of Americans support marijuana legalization, according to two recent surveys from major polling organizations.

The newest poll, from the Pew Research Center, found that 67 percent of Americans now back marijuana legalization, up from 62 percent in 2018. Opposition to legalization also dropped to 32 percent, down from 34 percent last year.

A Pew chart showing support and opposition for marijuana legalization over the years.

Pew also asked respondents about what kind of legalization they back. About 59 percent said they want medical and recreational legalization, while 32 percent said they only want medical legalization. Only 8 percent said neither.

Pew found that even a majority — 55 percent — of Republicans support legalizing pot. About 78 percent of Democrats do as well.

At the same time, another recent poll by Gallup found 66 percent of Americans support marijuana legalization, the same as Gallup found last year. Gallup also found that a majority of both Republicans and Democrats support legalization.

A Gallup chart showing support for marijuana legalization over the years.

Marijuana legalization has had some big victories in the past few years. The first two states — Colorado and Washington — legalized in 2012. In the seven years since, nine more states and Washington, DC, have legalized, with Illinois’ legislature most recently becoming the first legislature to legalize commercial sales of marijuana for recreational uses.

Meanwhile, Democratic presidential candidates have increasingly thrown their support behind legalization. With the exception of Joe Biden, the higher-polling Democrats back it.

Supporters of legalization argue that it eliminates the harms of marijuana prohibition: the hundreds of thousands of arrests around the US, the racial disparities behind those arrests, and the billions of dollars that flow from the black market for illicit marijuana to drug cartels that then use the money for violent operations around the world. All of this, legalization advocates say, will outweigh any of the potential downsides — such as increased cannabis use — that might come with legalization.

Opponents, however, claim that legalization will enable a huge marijuana industry that will market the drug irresponsibly. They point to America’s experiences with the alcohol and tobacco industries in particular, which have built their financial empires in large part on some of the heaviest consumers of their products. This could result in more people using pot, even if it leads to negative health consequences.