Fit for Duty and How Cannabis Legalization and the Opioid Epidemic Impact Workplace Safety

Recreational Legalization of Cannabis

For most individuals working in Occupational Health and Safety, October 17, 2018 will not be easy to forget. However, the truth is, substance use in the workplace is not new.  Prior to cannabis legalization, individuals did use cannabis in a recreational fashion before and at work. The Canadian Cannabis Survey, both 2017 and 2018, surveyed Canadians prior to legalization and both surveys confirmed use of non-medical cannabis before or at work by Canadians.

In 2018, eight percent of cannabis users advised they used cannabis before or at work weekly or more often (recreationally and not including medical use of cannabis), a similar rate found in the 2017 survey. The National Cannabis Survey 2019 found that 13% of cannabis users disclosed using cannabis before or at work, with the number jumping to 27% when the same question was asked of daily or almost daily users of cannabis. The question is: will the use of cannabis at work become more prevalent as Canadians start to accept cannabis as a legal recreational substance? This is difficult to answer at this time. However, since recreational cannabis legalization, there are some concerning trends that point in this direction. DriverCheck Inc., a third-party administrator for alcohol and drug testing in safety sensitive workplaces, has seen an increase in positive workplace drug tests due to THC, the psychoactive component of cannabis that is responsible for the euphoric effects of cannabis. In oral fluid drug testing, which detects very recent use of cannabis, there has been an increase of 106.5% of THC positivity rates.

Additionally, we continue to see a rise in individuals authorized to use cannabis for medical purposes across Canada with the most recent Government statistics showing that 363,917 Canadians have an authorization for cannabis for medical purposes (as of June 2019). Although this does not specifically speak to use in the workplace, employers continue to struggle with increasing number of employees advising of medical authorizations in safety sensitive workplaces.

With respect to cannabis use and safety sensitive workplaces, there is the great debate over the length of time cannabis may deem an individual unfit for duty. There is sufficient and significant data to support prolonged impairment from cannabis. Cannabis is a complicated substance and impairment is vastly different from that of the other legal recreational substance -- alcohol.   

The National Academies of Sciences, Engineering and Medicine’s literature review “The Health Effects of Cannabis and Cannabinoids” (2017),  reports that there is a statistical association between cannabis use and impairment in the cognitive domains of learning, memory and attention after acute consumption of cannabis.

The differences in the ability to predict impairment with cannabis is due to many factors, some of which are listed below:

• Multiple active components of the cannabis plant (cannabinoids, terpenes, flavanoids), acting on an individual’s endocannabinoid system (which may vary from person to person);

• Varying strengths of THC (with potencies that will exceed 90% with legalization of concentrates);

• Different routes of administration resulting in various lengths of time of intoxication (acute impairment);

• Differing impairments seen with regular users of cannabis and those with less frequent cannabis use;

•  Impairment which can be prolonged due to the accumulation of delta-9-THC in the fat cells (including the brain);

•  Personal genetics/make-up of the endocannabinoid system differs between individuals;

•  Acute, residual and long-term impairment is seen with cannabis use.

Schreiner and Dunn (2012) conducted two large meta-analyses to resolve the inconsistencies in the literature regarding the long-term impact of cannabis. One analysis looked at whether effects of cannabis last longer than 25 days, whereas the larger of the two meta-analyses attempted to determine whether residual effects are present. They concluded, through an analysis of 33 studies, that there was indeed a significant decreased global neurocognitive performance effect as well as impacts on eight of the ten cognitive domains assessed. These effects were not seen to last when looking at studies that tested at least 25 days of abstinence. In other words, there does not appear to be long-term permanent cognitive effects in chronic, heavy users of cannabis.

Residual impairment from cannabis is a concern in safety-sensitive workplaces and for those individuals performing any safety-sensitive duties. The length of time of residual impairment, the extent of impairment, as well as the severity of the impact on functioning differ between individuals (Norris, Szkudlarek, Pereira, Rushlow, and Laviolette, 2019). Residual impairment is unpredictable and non-linear, differentiating cannabis from alcohol. This is part of the reason that, despite the legalization of recreational cannabis, there continues to be a concern about the use of cannabis for those individuals working in safety-sensitive workplaces.

New Cannabis Laws: Impact in the Workplace 

October 2019 brings about new laws that will no doubt challenge workplaces: the legalization of edibles and concentrates. Although edibles and concentrates fall under the cannabis umbrella, they will not be legal for recreational sale until October 2019, with no availability to purchase until December 2019 at the earliest. Orally ingested cannabis “edibles” bring about a vastly different concern due to the slow onset of action and the prolonged impairing effects that occur. Given it takes 30 minutes to two hours to feel the effects of an orally ingested cannabis treat, many new and even some seasoned users of cannabis over-consume while waiting for the effects to take place. The impairment from edible cannabis is different and it is important to note the differences in pharmacokinetics and pharmacodynamics. With orally ingested cannabis there is first-pass effect, with the ingested delta-9-tetrahydrocannabinol (delta-9-THC) being metabolized to 11-hydroxy-tetrahydrocannabinol (11-OH-THC). This particular active metabolite is a much more potent cannabinoid with more profound psychoactive and euphoric effects and is thought to be the main reason why those who over-consume edible cannabis experience adverse effects (panic, paranoia and a more significant impairment) (Vandrey, Hermann, Mitchell, Bigelow, Flegel, LoDico and Cone, 2017).  The differences between the rise of the active components and metabolites of delta-9-THC when cannabis is ingested and smoked are illustrated below:

The impairment seen with orally ingested cannabis (“edibles”) is slower, more unpredictable and results in prolonged acute impairment that has been shown to last far longer than the acute intoxication associated with smoked cannabis (Vandrey et al., 2017).  The differences between edible cannabis and smoked cannabis requires more employee education. With the upcoming changes to the law, now is the time to ramp up employee education ensuring that all individuals are aware of the what “fit for duty” means.

 The complexity of cannabis, the increasing strength of THC products, the different impairments seen with differing routes of administration, and unpredictable and prolonged impairment are some of the reasons why some employers have instituted either a zero-tolerance policy or a 28-day cannabis ban. Although the Occupational and Environmental Medical Association of Canada (OEMAC) has recommended 24 hours between cannabis use and safety sensitive work, some industries have taken the stand that this is not long enough. The requirement and desire to maintain a safe workplace is the reason why it is of the utmost importance to educate the employees about cannabis and the risks of use for those performing safety sensitive duties or in safety sensitive workplaces.  

The Canadian Opioid Epidemic

The legalization of recreational cannabis and changes to the law for edibles and concentrates have overshadowed the much more problematic opioid epidemic that continues to rise across Canada.

Despite increased resources and commitments to strengthen the Health Care services available for individuals suffering from opioid use disorder, the opioid crisis continues to devastate families and communities across the continent. 2018 saw a record high number of opioid related deaths across Canada, with the numbers exceeding 4,400 (Government of Canada Statistics, 2019). One Canadian dies every two hours due to opioids. The pervasiveness of this crisis is highlighted by the fact that opioid-related deaths are increasing in all age groups, both sexes, and all income brackets with over 73% of accidental overdoses due to fentanyl (Ibid). 

This epidemic does impact the workplace with individuals using opioids requiring daily use in order to function. The exceedingly high prevalence of opioid prescriptions in Canada is also cause for concern in the workplace. Although there was a decrease in prescribing of opioids from 2016 to 2017, 21.3 million prescriptions for opioids were dispensed in 2017. Most concerning however is the fact that 57% of all opioid prescriptions were for the top four strongest narcotics including fentanyl, hydromorphone, morphine and oxycodone (Canadian Institute for Health Information, 2018).

Opioids, whether prescribed or used recreationally, result in impairment in the workplace. The specific impairments vary across the different opioids. In general, the acute use of opioids results in somnolence, issues with attention, concentration, and memory as well as psychomotor dysfunction. Although some of these initial symptoms resolve with repeated doses, chronic use of opioids lead to cognitive effects and impairment in 20-62% of daily users of opioids.  For example: impairment in executive functions, attention, memory, and sleep disturbances (Dhingra, Ahmed, Shin, Scharaga, and Magun, 2015).

Opioids have been consistently associated with increased risk of motor vehicle accidents with some epidemiological studies stating a risk greater than 800% (Gomes, Redelmeier, Juurlink, Dhalla, Camacho, Mamdani, 2013) leading to the American College of Occupational and Environmental Medicine (ACOEM) recommendation that “acute or chronic opioid use is not recommended for patients who perform safety-sensitive jobs.”  (Hegmann, Weiss, Bowden, Branco, DuBrueler, Els et al, 2014).

 Unfortunately, with the opioids being used in Canada, there is a high risk of morbidity and mortality with overdoses occurring across the country at record levels. Ensuring that there are personnel at work who can respond in case of an emergency is ideal but not always possible. Naloxone is an opioid antagonist and administration of this can reverse a fatal overdose from opioids. Naloxone kits are widely available, easy to use, and can save a life. Workplaces should be equipped with these kits.  It is no different than ensuring there is access to other emergency kits in the workplace (e.g. defibrillators, etc.).

There are many causes of impairment in the workplace. The media attention of the legalization of recreational cannabis and the ongoing opioid epidemic have resulted in improved employer engagement of the reality of workplace impairment. The importance of “fit for duty” cannot be stressed enough. We must consider all causes of impairment equally with open minds and knowledge of what Canadian employees are using recreationally, as well as being prescribed or authorized.

Dr. Melissa Snider-Adler, M.D., C.C.F.P.(AM), M.R.O. (AAMRO), D.A.B.A.M., is the Chief Medical Review Officer at DriverCheck Inc. and is a board certified Addiction[FM1]  Medicine Physician.

Email:  melissasa@drivercheck.ca 

References

Dhingra, L., Ahmed, E., Shin, J., Scharaga, E., Magun, M. (2015) Cognitive effects and sedation, Pain Medicine, Volume 16, Issue suppl_1, October 2015, Pages S37-S43, https://doi.org/10.1111/pme.12912

Gomes, T., Redelmeier, D.A., Juurlink, D.N., Dhalla, I.A., Camacho, X., Mamdani, M.M. (2013). Opioid dose and risk of road trauma in Canada: a population-based study. JAMA Intern Med. 2013;173:196–201.

Government of Canada. Overview of national data on opioid- related harms and deaths 2018. Available at: https://www. canada.ca/en/health-canada/services/substance-use/problematic- prescription-drug-use/opioids/data-surveillance-research/ harms-deaths.html (accessed September 2019).

Hegmann, K.T., Weiss, M.S., Bowden, K., Branco, F., DuBrueler, K., Els, C., et al. (2014) ACOEM practice guidelines: opioids and safety-sensitive work. Journal of Occupational and Environmental Medicine 2014;56(7):e46–53. DOI:10.1097/JOM.0000000000000237

Norris, C., Szkudlarek, H., Pereira, B., Rushlow, W., Laviolette, S. (2019). The bivalent rewarding and aversive properties of δ9- tetrahydrocannabinol are mediated through dissociable opioid receptor substrates and neuronal modulation mechanisms in distinct striatal sub-regions. Scientific Reports, Volume 9, Article number: 9760

Schreiner, A.M., & Dunn, M.E. (2012). Residual effects of cannabis use on neurocognitive performance after prolonged abstinence: A meta-analysis. Experimental and Clinical Psychopharmacology, 20(5), 420-429.

http://dx.doi.org/10.1037/a0029117

 Vandrey, R., Herrmann, E.S., Mitchell, J.M., Bigelow, G.E., Flegel,R., LoDico, C., & Cone, E. J. (2017). Pharmacokinetic profile of oral cannabis in humans: blood and oral fluid disposition and relation to pharmacodynamic outcomes. Journal of analytical toxicology, 41(2), 83–99. doi:10.1093/jat/bkx012