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Workplace Policies on Medical Marijuana: Some Guidance on the Complex, Chameleon-like Legal and Medical Issues Involved

May 28, 2015 (11 min read)

Karen C. Yotis, Esq., a Feature Resident Columnist for the LexisNexis Workers’ Compensation eNewsletter, provides insights into workplace issues and the nuts and bolts of the workers’ comp world.

How risky would it be if your mailroom employees used medical marijuana at work? Would your creative writers or graphic designers be a danger to themselves or others if they got stoned before or after working hours for medical reasons? How about someone in your IT department? A cafeteria worker? A CEO? Are there any situations where workers could use medical marijuana with reasonable safety? In an attempt to help employers navigate the complex and chameleon-like legal and medical issues surrounding medical marijuana in the workplace, a new study examines the known and potential health effects of medical marijuana, dose and concentration of tetrahydrocannabinol (THC), psychometer effects, and pharmacokinetics, and concludes with seven recommendations for employers and occupational physicians when dealing with medical marijuana in the workplace. (See Goldsmith, R.S., et al., “Medical Marijuana in the Workplace: Challenges and Management Options for Occupational Physicians”, Journal of Occupational and Environmental Medicine, Vol. 57, No. 5 (May 2015)).

Sharing his expertise on this article is Mark Pew, Senior Vice President at PRIUM and nationally recognized thought leader on the topic of marijuana in the workplace. Fresh from the conference circuit, Pew spoke last week about medical marijuana at the Self-Insurance Institute of America Workers’ Compensation Executive Forum. Pew’s comments are interspersed throughout the study authors’ observations and recommendations below.

State Laws on Medicinal Use of Cannabis

In spite of federal laws that still prohibit possession and use of marijuana, four states (AK, CO, OR, WA) and the District of Columbia have legalized marijuana, 23 states allow medicinal use of marijuana and 14 additional states have limited-access approval. Up-to-date information about the marijuana laws in effect throughout the nation is available on the National Conference of State Legislatures website. The study authors note a wide range of medical uses for marijuana—30 in all. For example, the majority of states permit medical marijuana for cancer, HIV-AIDS, epilepsy, glaucoma, cachexia or wasting syndrome, severe nausea, severe or chronic pain, and severe muscle spasms, as well as other medical conditions that are approved by a state agency.

Potency Levels of Cannabis

Most of the marijuana cultivated in the U.S. is Cannabis sativa, which has over 400 different chemical compounds that include over 60 cannabinoids. As explained by the study authors, cannabinoids “modulate neurotransmission through receptors in the brain (CB1)…THC, which is active at CB1 receptors, is primarily responsible for the plant’s psychoactivity.” For the past 20 or so years, marijuana growers have cultivated more potent strains with higher levels of THC. In the U.S., the THC level has increased from 4% in 1983 to 9.6% in 2007. However, studies have shown that lower levels of THC have therapeutic value, such as for chronic pain, without the psychoactive effect.

Pew supplemented these figures with some additional research, noting that “today’s marijuana can be up to 30% THC, for orally ingested edibles the THC concentration can be up to 70% and THC levels can be as high as 90% in ‘dabs’ (the marijuana equivalent of crack cocaine).” Adding a real-world, practical element to the study authors’ scientific research, Pew also stated:

“With capitalism at work in states where recreational use is legal, there is a competition in the marketplace for the biggest buzz that occurs the quickest and lasts the longest. That ‘product development’ obviously has a ripple effect for both recreational and medicinal users, and will likely continue as manufacturers and dispensaries try to distinguish themselves.”

Cannabinoid Pharmacokinetics

In the U.S., cannabis is usually inhaled or taken orally. With inhaled smoke or vaporized THC, the psychotropic effects start within a few seconds or minutes, peak at 15 to 30 minutes, and then taper off within 2 to 3 hours.

With respect to ingestion of oral preparations of cannabis, the peak level of THC is lower and longer-delayed because it is absorbed in the gastrointestinal tract. Psychotropic effects start after 30 to 90 minutes, peak at 2 to 3 hours, and remain apparent for 4 to 12 hours. However, the study authors point out that when it comes to consumption of THC, there are considerable variations in peak concentrations and rates of absorption due to factors unique to each individual as well as the dose involved and the type of oral preparation ingested (e.g., ice cream, brownie, oil concentrate). This presents serious challenges for occupational physicians in determining impairment variables.

Transdermal application of cannabinoids has become an attractive alternative for those individuals who cannot inhale or ingest medical marijuana. When cannabis is applied through skin patches, the THC concentrations occur within 1.4 hours and maintained for at least 48 hours.

Shedding light on a decidedly darker side of the debate surrounding marijuana edibles, Pew added:

“Based on my research, edibles are dangerous. Given the higher level of potency and the possibility of overdosing (by eating more ‘portions’), it is actually the most dangerous form of delivery. There are at least four people in Colorado that have died by having psychotic events that caused them to commit suicide from the effects of overdosing. The trend in jurisdictions to outlaw smoking (good) and focus on vaping and edibles can be a mistake, even if portions and labeling are tightly regulated.”

Impairment of Judgment and Psychomotor Skills

The study authors cite numerous studies that have correlated the effect of marijuana use in the workplace with higher incidences of industrial accidents, injuries, and absenteeism due to impairment of judgment and psychomotor skills. The lingering effects of the drug can last from hours to weeks. Even after 28 days of abstinence, there are still decrements in neurocognitive performance associated with individuals with very heavy use of the drug. The study authors note that more studies are needed to address non-acute manifestations of marijuana use.

The “unknowns” surrounding the science of marijuana use underscores Pew’s opinion that the validation of impairment needs to go beyond urine and blood tests alone. And although he noted that “formal cognition tests are available in addition to roadside-type tests like saying ABC’s, bloodshot eyes and walking a straight line,” Pew was careful to point out that “the presence of marijuana is not sufficient to prove (or even speculate) upon impairment and must be corroborated with motor and cognitive skills testing.”

The study authors point out that most of the studies conducted to date focused on individuals who were using a lower potency TCH strain, whereas today higher potency strains are being used by individuals. One can assume that the higher potency strains will have “proportionally greater and more prolonged psychomotor effects.”

The study authors warn that products being marketed as “non-sedating” and “non-impairing” and therefore safe for the workplace are unproven. So far scientific research has been limited to rats with no human trials. It remains to be seen if selective inhibition of CB1 receptors can be achieved to “improve the safety profile of cannabinoids.”

Should the development of psychoactive tolerance to cannabis be a factor in determining the safety of marijuana use? The study authors note studies that show psychoactive tolerance among chronic marijuana users and “minimal effects on complex cognitive task performance in experienced users.”

Pew addressed this conundrum when he suggested that:

“When ‘medical’ marijuana is used in the workplace by a registered user, they should have a baseline test done to use as a source of comparison for future testing. This is probably an overlooked procedure in existing workplace policies.”

Pew construed the study authors’ suggestion that employers establish an agreement with users similar to an opioid use agreement as a best practice, as well as treating marijuana similarly when it comes to any change in rationale, dosing or delivery method.

7 Guidelines to Help Employers With Managing Marijuana in the Workplace

The study authors make the following recommendations:

Outright Prohibitions and State Law

While supporting a total ban on marijuana use as a reasonable and responsible option that aligns with current federal laws, the study authors recommend a careful review of state laws, particularly antidiscrimination laws as they may apply to an employee’s use of marijuana while away from work, and with respect to employee discipline that stems from drug testing.

Continuing Policy Review

The study authors recommend that companies conduct a regular review of any relevant policies in light of the rapidly changing legislation and jurisprudence and evolving knowledge on marijuana’s risks and benefits.

Safety Sensitive Positions

The study authors underscore the importance of maintaining zero tolerance of medical marijuana use by employees in any safety sensitive positions that are subject to federal or state safety standards or federally imposed drug testing requirements.

Pew cut to the heart of the issue with respect to safety sensitive positions when he noted:

“The safety sensitive positions, whether mandated by federal guidelines or common sense, are obvious. But if an accountant is cognitively impaired and they’re responsible for tracking revenue and expenses and filing U.S. taxes and paying contractors, is that a good combination?”

Impairment Evidence

If a worker is suspected of being impaired (by marijuana or another substance), the study authors recommend that the employer immediately remove that worker from the premises. While acknowledging the generally accepted whole blood THC level of 5 ng/mL, the study authors warn against using THC levels alone or in place of neurocognitive testing to establish impairment. Evidence of impairment coupled with a blood THC level that exceeds the generally accepted legal limit could establish evidence of THC-induced impairment. The study authors recommend a full medical evaluation—including mental health testing—for clinically impaired workers who fail to test positive for THC.

Accepted Medical Use

For employers that decide to accept their employees’ use of medical marijuana, the study authors recommend:

> Including an occupational physician with impairment training and legal counsel on all discussions about the company’s policy or an individual’s marijuana use

> Instituting clear guidelines on medical marijuana use in specific situations and applying those guidelines consistently, and requiring employees seeking approval for use to submit written permission from their doctor that includes the legal validation, medical basis, schedule of use, methods of administration, accommodations or restrictions, and expected length of use

> Requiring employees who are certified to use marijuana to report any changes in the marijuana product they use, the amount of marijuana they are prescribed, how often they use it, their schedule of use, and how they ingest the drug.

> Requiring all workers who use medical marijuana to undergo neurocognitive testing that assesses residual impairment (with respect to work-related risk) and establishes a baseline function before the employee is allowed to use marijuana, as well as retesting whenever an employee reports any of changes recommended above.

> Having the occupational physician-reviewer and legal counsel compare the requesting worker’s medical condition with the state’s approved list, work with site managers to assess risk of residual impairment, deny accommodation if a worker, coworker or public safety is at risk, and consider if necessary workplace safety concerns vis-à-vis the underlying medical reason for which a worker is using marijuana.

> Not allowing marijuana while an employee is at work (or on the way to or from a job site) unless the employer is certain that the using worker, coworkers, or the public are not at risk from any neurocognitive and judgment impairment associated with that worker’s marijuana use.

> Remembering that marijuana use before or after working hours does not guarantee that an employee using marijuana outside of a shift is safe, especially in view of evidence that “complex human performance” may be impaired more than 24 hours after THC an employee inhales THC.

Continuing Research

The study authors support continuing research on marijuana use, particularly with respect to its pharmacodynamics, pharmacokinetics and occupational risks.

Reminding us about the political and economic ramifications underpinning the ongoing debate about medical marijuana, Pew revealed:

“I’ve heard that up to 90% of the current studies were initiated to validate the risks associated with marijuana use, not the benefits. Part of that has to do with its illegality at the federal level (thereby reducing financial incentives for expensive and time-consuming studies), part of it has to do with the stigma associated with marijuana use and part of it has to do with opponents trying to battle the obvious momentum towards legalization.”

Continuing Education

The study authors emphasize how important it is for occupational physicians to remain up-to-date on developments in marijuana research and treatment, especially in view of the rapid changes that are taking place in the legal and scientific milieu.


In view of the thousands of anecdotal accounts about the medical benefits of marijuana, and in view of the apparent increase in marijuana research, Pew comes down on the side of using extreme care and caution both in the workplace and beyond. Leaving us with some poignant thoughts to reflect upon, Pew laid it on the line when he opined:

“I believe that marijuana can be useful for some medical conditions. Like with any other treatment, I believe the basis of ongoing use should be judged by clinical outcomes—i.e., the patient is better with the treatment than without and the benefits outweigh the risks. I also believe more studies that clinically and scientifically prove benefits are needed. However, I also believe that the American Society of Addiction Medicine (ASAM) is correct in stating, ‘[F]or every disease and disorder for which marijuana has been recommended, there is a better, FDA-approved medication.’”

Put that in your pipe and smoke it.

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