Impact of Cannabis Use on Road Traffic Collisions and Safety at Work: Systematic Review and Meta-analysis

Is cannabis a slippery slope? Associations between psychological dysfunctioning, other substance use, and impaired driving, in a sample of active cannabis users

Cannabis is a gateway drug that can lead to the engagement of other substances. Psychological dysfunctioning and dependence have been highlighted as primary components to substance misuse. The purpose of this study was to investigate what aspects of cannabis use and psychological dysfunctioning are associated with the engagement of other substances and impaired driving. Subject to screening, 200 active adult cannabis users completed an online survey. Existing data involving non-cannabis users (N = 833) were also implemented as comparative data. The comparisons suggested that cannabis users were far more likely to have used other drugs in the past 12 months, compared to non-cannabis users. Bivariate correlations and multiple regressions indicated that the degree of cannabis use and likely dependence, psycho-social motives for using cannabis, emotion dysregulation, and psychopathology were positively associated with the frequency of using and driving on other substances. Finally, an ANOVA demonstrated that outside of age, there were no apparent differences in substance use behaviours, motives for using cannabis, and psychological dysfunction, between medicinal and black-market cannabis users. These findings highlight the potential benefits of incorporating self-regulatory concepts into current road safety initiatives, which aim to reduce the interconnected issue of substance misuse and impaired driving behaviours.

Neurological Complications of Cannabinoids

Cannabinoid use, particularly for recreational purposes, is increasing exponentially across all age groups, especially in younger populations, due to its perceived low risk and legalization. While cannabinoids may be largely considered as safe, there is mounting evidence of increased risk of systemic and neurological complications through their interaction with the poorly understood endocannabinoid receptor network within the central nervous system and other organ systems. Acute cannabinoid exposure can cause neuropsychiatric symptoms in addition to altering cerebral blood flow, leading to cerebrovascular complications such as ischemic stroke, subarachnoid hemorrhage, and reversible cerebral vasoconstriction syndrome (RCVS). Chronic use, particularly among adolescents, may be associated with increased risk of long-term cognitive deficits, schizophrenia, and other neuropsychiatric effects. Synthetic cannabinoids have increased potency, with reports of causing profound neurological complications including coma, seizures, posterior reversible encephalopathy syndrome, and RCVS. Despite increasing evidence, the quality of literature describing neurologic complications with cannabinoids remains limited to case series and retrospective cohort studies, with significant confounding factors such as concomitant use of other illicit drugs, limiting interpretation. In this review, we summarize the effect of cannabinoids on the neurologic system and associated neurological complications.

Cannabidiol (CBD) Products for Pain: Ineffective, Expensive, and With Potential Harms

Cannabidiol (CBD) attracts considerable attention for promoting good health and treating various conditions, predominantly pain, often in breach of advertising rules. Examination of available CBD products in North America and Europe demonstrates that CBD content can vary from none to much more than advertised and that potentially harmful other chemicals are often included. Serious harm is associated with chemicals found in CBD products and reported in children, adults, and the elderly. A 2021 International Association for the Study of Pain task force examined the evidence for cannabinoids and pain but found no trials of CBD. Sixteen CBD randomized trials using pharmaceutical-supplied CBD or making preparations from such a source and with pain as an outcome have been published subsequently. The trials were conducted in 12 different pain states, using 3 oral, topical, and buccal/sublingual administration, with CBD doses between 6 and 1,600 mg, and durations of treatment between a single dose and 12 weeks. Fifteen of the 16 showed no benefit of CBD over placebo. Small clinical trials using verified CBD suggest the drug to be largely benign; while large-scale evidence of safety is lacking, there is growing evidence linking CBD to increased rates of serious adverse events and hepatotoxicity. In January 2023, the Food and Drug Administration (FDA) announced that a new regulatory pathway for CBD was needed. Consumers and health care providers should rely on evidence-based sources of information on CBD, not just advertisements. Current evidence is that CBD for pain is expensive, ineffective, and possibly harmful. PERSPECTIVE: There is no good reason for thinking that CBD relieves pain, but there are good reasons for doubting the contents of CBD products in terms of CBD content and purity.

Reliability of roadside oral fluid testing devices for ∆9 -tetrahydrocannabinol (∆9 -THC) detection

Driving under the influence of cannabis (DUIC) is increasing worldwide, and cannabis is the most prevalent drug after alcohol in impaired driving cases, emphasizing the need for a reliable traffic enforcement strategy. ∆9 -tetrahydrocannabinol (THC) detection in oral fluid has great potential for identifying recent cannabis use; however, additional data are needed on the sensitivities, specificities, and efficiencies of different oral fluid devices for detecting cannabinoids at the roadside by police during routine traffic safety enforcement efforts. At the roadside, 8945 oral fluid THC screening tests were performed with four devices: AquilaScan®, Dräger DrugTest®, WipeAlyser Reader®, and Druglizer®. A total of 530 samples screened positive for THC (5.9%) and were analyzed by liquid chromatography-tandem mass spectrometry at multiple cutoff concentrations (2 ng/mL, 10 ng/mL, and manufacturers' recommended device cutoffs) to investigate device performance. Results varied substantially, with sensitivities of 0%-96.8%, specificities of 89.8%-98.5%, and efficiencies of 84.3%-97.8%. The Dräger DrugTest® outperformed the other devices with a 96.8% sensitivity, 97.1% specificity, and 97.0% efficiency at a 5-ng/mL LC-MS/MS confirmation cutoff. The WipeAlyser Reader® had good performance with a 91.4% sensitivity, 97.2% specificity, and 96.4% efficiency. AquilaScan® and Druglizer® had unacceptable performance for cannabinoid detection, highlighted by sensitivity <13%. The choice of roadside oral fluid testing device must offer good analytical performance for cannabinoids because of its high prevalence of use and impact on road safety.

Cannabinoids and synthetic cannabinoids as a cause of death: Trends and their healthcare implications

INTRODUCTION

Cannabis remains one of the most widely used illicit substances globally, with 188 million users in 2017. In the United States, nearly 50 million people are reported to have used cannabis in 2020. More research is needed because of the dramatic increase in cannabis use and the perception that its use has minimal risk.

DESIGN

The researchers used a retrospective design for this study.

METHODS

We used the Florida Department of Law Enforcement data from 2014 to 2020 for this study. We used descriptive statistics to report the characteristics of decedents whose cause of death (COD) was associated with cannabinoid (CB) and synthetic cannabinoid (SC) use. We used a general linear model with repeated measures to examine CB and SC death rate trends.

RESULTS

A total of 386 decedents' COD in Florida was associated with CB and SC use. Nearly 28% of decedents were 45-54 years, male (87.8%), and non-Hispanic whites (65.3%). One hundred percent of CB-related decedents died in urban counties. In rural counties, SC decedents accounted for 28.3% of deaths. Of decedents in rural counties, 39.9% were African American. Most decedents (with CB and SC use) died from accidents (98.7%), with 12.6% of cases involving cardiovascular-related illnesses.

CONCLUSION

CBs and SCs as a COD pose a legitimate health problem to society. More people ages 45-54 died from CBs and SCs. Drug intoxications (from CBs and SCs) and motor vehicle collisions accounted for most of the accidents reported while under the influence of CBs and SCs. While most decedents from both CBs and SCs were non-Hispanic whites, a substantial proportion of African Americans died from SCs as a COD in rural counties. It is important that the public become aware of the risks for adverse effects of CB and SC. The public needs to be aware that CB and SC use can exacerbate cardiac-related conditions.

CLINICAL RELEVANCE

This study has clinical relevance to patient safety. CB and SC use contributes to motor vehicle accidents and can cause adverse effects including death.

The impact of recreational cannabis markets on motor vehicle accident, suicide, and opioid overdose fatalities

In the U.S., an increasing number of states are legalizing regulated commercial markets for recreational cannabis, which allows private industry to produce, distribute, and sell marijuana to those 21 and older. The health impacts of these markets are not fully understood. Preliminary evidence suggests recreational markets may be associated with increased use among adults, which indicates there may be downstream health impacts on outcomes related to cannabis use. Three causes of death that are linked to cannabis use are motor vehicle accidents, suicide, and opioid overdose. Drawing on data from U.S. death certificates from 2009 to 2019, we conducted a difference-in-differences analysis to estimate the impact of recreational markets on fatalities from motor vehicle accidents, suicide, and opioid overdose in seven states: Colorado, Washington, Oregon, Alaska, Nevada, California, and Massachusetts. States with comprehensive medical cannabis programs with similar pre-trends in deaths were used as comparisons. For each outcome, a pooled estimate was generated with a meta-analysis using random effects models. The results revealed substantial increases in crash fatalities in Colorado, Oregon, Alaska, and California of 16%, 22%, 20%, and 14%, respectively. Based on estimates from all seven states, recreational markets were associated with a 10% increase in motor vehicle accident deaths, on average. This study found no evidence that recreational markets impacted suicides. Most states saw a relative reduction in opioid overdose death that ranged between 3 and 28%. On average, recreational markets were associated with an 11% reduction in opioid overdose fatalities.

Driving under the influence of drugs: Correlation between blood psychoactive drug concentrations and cognitive impairment. A narrative review taking into account forensic issues

Driving under the influence of alcohol has been shown to increase the risk of involvement in road traffic collisions (RTCs) however, less is known about the effects of illicit drugs, and a clear correlation between drug concentrations and RTC risk is still debated. The goal of this narrative review is to assess the current literature regarding the most detected psychoactive drugs in RTC (ethanol, amphetamines, cannabis, opioids and cocaine), in relation to driving performance. Evidence on impaired driving due to psychoactive substances, forensic issues relating to the assessment of the impact of drugs, blood cut-off values proposed to date as well as scientific basis for proposed legislative limits are discussed. At present there is no unequivocal evidence demonstrating a clear dose/concentration dependent impairment in many substances. Per se and zero tolerance approaches seem to have negative effect on drugged driving fatalities. However, the weight of these approaches needs further investigation.

Cannabis and driving ability

The aim of this review is to discuss recent evidence on cannabis and driving ability. In particular, the review examines experimental research on the acute effects of tetrahydrocannabinol (THC) on driving-related neurobehavioral skills and driving performance based on simulator and road course studies. The evidence indicates that certain driving abilities are significantly, albeit modestly, impaired in individuals experiencing the acute effects of THC. Treatment effects are moderated by dose, delivery method, recency of use, and tolerance development, with inconclusive evidence concerning the moderating influence of cannabidiol. Emerging research priorities include linking neurobehavioral deficits to specific decrements in driving performance, estimating the real-world implications of experimental impaired driving research, understanding how tolerance differentially affects driving impairment across subgroups, and developing more evidence on cannabidiol's potential role in mitigating THC-induced impairment.

Road traffic injuries and substance use among emergency department patients in the Dominican Republic and Peru

Objective.

To report demographic and substance use characteristics and risk of road traffic injury (RTI) from alcohol use, cannabis use, and combined use in a sample of emergency department patients from two countries in Latin America and the Caribbean.

Methods.

A cross-sectional study in which patients 18 years and older admitted within six hours of suffering an RTI to one emergency department in Santa Domingo, Dominican Republic (n = 501) and in Lima, Peru (n = 431) were interviewed. Case-crossover analysis, based on self-reported use prior to the RTI, was used to analyze risk from alcohol, cannabis, and co-use.

Results.

Overall, 15.3% reported alcohol use prior to the event and 2.5% cannabis use. Drivers using alcohol only were over twice as likely to have an RTI (OR = 2.46, p < 0.001), and nearly eight times more likely if using both alcohol and cannabis (OR = 6.89, p < 0.01), but risk was not elevated for cannabis alone. Significant differences were not found for passengers or pedestrians.

Conclusions.

Risk of RTI for drivers in these two samples is significantly elevated from alcohol use, and more so for co-use with cannabis. Differences between the two countries underscore the need for similar data from the region to determine risk of RTI from substance use, including risk for passengers and pedestrians. Data suggest that alcohol contributes significantly to the burden of RTI, which calls for more stringent enforcement of alcohol control policy related to drink driving in the region.

Random drug and alcohol testing for preventing injury in workers

BACKGROUND

Drug- and alcohol-related impairment in the workplace has been linked to an increased risk of injury for workers. Randomly testing populations of workers for these substances has become a practice in many jurisdictions, with the intention of reducing the risk of workplace incidents and accidents. Despite the proliferation of random drug and alcohol testing (RDAT), there is currently a lack of consensus about whether it is effective at preventing workplace injury, or improving other non-injury accident outcomes in the work place.

OBJECTIVES

To assess the effectiveness of workplace RDAT to prevent injuries and improve non-injury accident outcomes (unplanned events that result in damage or loss of property) in workers compared with no workplace RDAT.

SEARCH METHODS

We conducted a systematic literature search to identify eligible published and unpublished studies. The date of the last search was 1 November 2020. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, two other databases, Google Scholar, and three trials registers. We also screened the reference lists of relevant publications known to us.

SELECTION CRITERIA

Study designs that were eligible for inclusion in our review included randomised controlled trials (RCTs), cluster-randomised trials (CRTs), interrupted time-series (ITS) studies, and controlled before-after (CBA) studies. Studies needed to evaluate the effectiveness of RDAT in preventing workplace injury or improving other non-injury workplace outcomes. We also considered unpublished data from clinical trial registries. We included employees working in all safety-sensitive occupations, except for commercial drivers, who are the subject of another Cochrane Review.

DATA COLLECTION AND ANALYSIS

Independently, two review authors used a data collection form to extract relevant characteristics from the included study. They then analysed a line graph included in the study of the prevalence rate of alcohol violations per year. Independently, the review authors completed a GRADE assessment, as a means of rating the quality of the evidence.

MAIN RESULTS

Although our searching originally identified 4198 unique hits, only one study was eligible for inclusion in this review. This was an ITS study that measured the effect of random alcohol testing (RAT) on the test positivity rate of employees of major airlines in the USA from 1995 to 2002. The study included data from 511,745 random alcohol tests, and reported no information about testing for other substances. The rate of positive results was the only outcome of interest reported by the study. The average rate of positive results found by RAT increased from 0.07% to 0.11% when the minimum percentage of workers who underwent RAT annually was reduced from 25% to 10%. Our analyses found this change to be a statistically significant increase (estimated change in level, where the level reflects the average percentage points of positive tests = 0.040, 95% confidence interval 0.005 to 0.075; P = 0.031). Our GRADE assessment, for the observed effect of lower minimum testing percentages associating with a higher rate of positive test results, found the quality of the evidence to be 'very low' across the five GRADE domains. The one included study did not address the following outcomes of interest: fatal injuries; non-fatal injuries; non-injury accidents; absenteeism; and adverse effects associated with RDAT.

AUTHORS' CONCLUSIONS

In the aviation industry in the USA, the only setting for which the eligible study reported data, there was a statistically significant increase in the rate of positive RAT results following a reduction in the percentage of workers tested, which we deem to be clinically relevant. This result suggests an inverse relationship between the proportion of positive test results and the rate of testing, which is consistent with a deterrent effect for testing. No data were reported on adverse effects related to RDAT. We could not draw definitive conclusions regarding the effectiveness of RDAT for employees in safety-sensitive occupations (not including commercial driving), or with safety-sensitive job functions. We identified only one eligible study that reflected one industry in one country, was of non-randomised design, and tested only for alcohol, not for drugs or other substances. Our GRADE assessment resulted in a 'very low' rating for the quality of the evidence on the only outcome reported. The paucity of eligible research was a major limitation in our review, and additional studies evaluating the effect of RDAT on safety outcomes are needed.

Rates, characteristics and manner of cannabis-related deaths in Australia 2000-2018

BACKGROUND

The most commonly used illicit substance worldwide is cannabis. To date, no national level study of cannabis-related death has been undertaken in Australia. The current study aimed to investigate the rates, characteristics and manner of cannabis-related deaths recorded in Australia (2000-2018).

METHODS

A retrospective case review of medicolegal files was undertaken through the National Coronial Information System (NCIS) (1/07/2000-31/12/2018).

RESULTS

A total of 559 cases were identified, with a mean age of 35.8 years, 81.2% were male. The crude mortality rate per 100,000 people ranged between 0.10 (CI = 0.06-0.15) and 0.23 (CI = 0.17-0.30). The manner of deaths were: accidental injury (29.9%), suicide (25.0%), polysubstance toxicity (17.0%), natural disease (16.1 %), natural disease and drug effect/toxicity (7.9%), assault (3.0%) and unascertained (1.1%). No deaths were solely due to cannabis toxicity. Men were over-represented in this group and were three times as likely to die of accidental injury than women who died from cannabis-related deaths. Motor vehicle accidents were the leading cause of accidental injury. Cardiovascular (14.3%) and respiratory conditions (9.7%) were the most common disease types recorded in cause of death. The median Δ-9-tetrahydrocannabinol blood concentration was 0.008 mg/L (range 0.0005-19.00 mg/L). Other drugs were cited in the cause of death alongside cannabis (81.4%), the most common being alcohol (47.2%).

CONCLUSIONS

Low all-cause crude mortality rates remained relatively stable over the study period. No deaths were due to direct cannabis toxicity, but death due to accidental injury was prominent.