From the standpoint of workplace safety, marijuana is different from legal intoxicants such as alcohol or prescription narcotics – partly because of the unpredictability of impairment. Robert Goldsmith, an occupational health professional in the pharmaceutical industry and co-author of “Medical Marijuana in the Workplace,” a 2015 article published in the Journal of Occupational and Environmental Medicine, noted that the degree and duration of marijuana impairment is highly individual, based on a number of factors, including:
Route of administration (smoking, consuming edibles, vaping or applying a skin patch)
History of use (first time vs. habitual use)
Concurrent medication use
Some of these factors apply in the cases of other substances as well, but marijuana dosage is uniquely variable. “It’s very difficult to standardize a medical marijuana dose, especially if the marijuana is smoked,” Goldsmith said. “There are inhalation factors – how deeply the marijuana is inhaled, how long it’s held. Is one puff equivalent to another puff?”
Further complicating dose predictability is the variation in potency of different marijuana strains, which have been bred for higher levels of tetrahydrocannabinol (or THC, the primary psychoactive component of marijuana). “Marijuana can be up to 30 times stronger than it was 20 years ago, and one cultivator versus another could be hugely different in the strength of the marijuana,” said Christine Clearwater, president of the consulting firm Drug-Free Solutions Group LLC. “The reason is, there are no set controls or standards. It’s like the Wild West right now.”
Contrast this with the standardization of commercial alcohol products or prescription drugs. “Alcoholic drinks are premeasured for sale, so each ounce contains a pre-approved, designated amount of alcohol,” Clearwater said. “That means one bottle of a particular brand of whiskey is the same as the next.”
Similarly, Food and Drug Administration-approved prescription drugs are subject to rigorous testing and strict manufacturing practices, she added, “so you have well-defined, measurable ingredients that are consistent unit to unit.”
FDA recently approved a drug with the active ingredient cannabidiol (CBD), which is derived from marijuana but lacks its psychoactive properties. However, because this medication has been approved only for rare forms of epilepsy, employers are unlikely to come across it in the workplace.
Additionally, although other marijuana-derived products purport to be non-impairing, Goldsmith views these claims as theoretical, at best. “Without federal regulation, it’s difficult to be confident that products that claim to be entirely CBD-containing or non-impairing are in fact not impairing,” he said.
Accommodation means documentation
For employers who tolerate medical use of the drug, experts recommend requiring workers to provide documentation supporting their use of marijuana, similar to how they would report a potentially impairing prescription medication.
However, because of the variability of dosing and other factors, “the assessment of impairment and the oversight required for the safe use of medical marijuana exceeds that for other potentially psychoactive drugs,” Goldsmith cautioned. “It’s critical that the health and safety group establish guidelines for the assessment of neurocognitive function among employees who have been permitted to use medical marijuana.”
In “Medical Marijuana in the Workplace,” Goldsmith and his colleagues recommend that employers require baseline neurocognitive testing, as well as the following documentation from the authorizing medical provider (plus prompt updates and re-evaluation whenever there’s a change):
The diagnosis or condition
The medical rationale for treatment with marijuana
The dosage, frequency, timing of use and route of administration
How long the drug is expected to be used
Any recommended work restrictions or accommodations
Communication is crucial
The changing legal landscape regarding marijuana can be just as confusing for workers as it is for employers. If managers and workers don’t know what their company’s policy is, they’ll operate on assumptions.
“A policy is just a policy,” Clearwater said. “It’s a piece of paper. You breathe life into it by training managers and educating employees.”
Clemens recommends advising workers of company drug policies frequently, especially when changing laws raise the likelihood of confusion.
“When recreational marijuana was legalized in Alaska, we required each employee to sign a new drug test policy form that clearly stated the company’s position,” he said.
Communicating a tough stance toward marijuana doesn’t mean employers can’t show compassion for employees who are struggling with substance abuse.
“I think any safety professional would agree that any use of drugs or alcohol that would lead to impairment in the workplace is completely at odds with a culture of safety and cannot be tolerated,” said Brian Hendrix, a partner in Husch Blackwell’s Energy and Natural Resources Group. “But I will say that a lot of our clients – large and small – don’t take a one-strike approach to drug and alcohol use. If you do self-report or test positive in certain situations, and agree to go through a rehabilitation program and then submit to post-program testing, you can be returned to work – even for positions that are safety-sensitive.”
OSHA’s new post-incident rule: What it doesn’t mean
In 2016, OSHA issued its Improve Tracking of Workplace Injuries and Illnesses final rule, which – among other provisions – prohibits post-incident testing “if an injury or illness is very unlikely to have been caused by employee drug use, or if the method of drug testing does not identify impairment but only use at some time in the recent past.”
“The new policy does not apply to random drug testing,” said Brian Hendrix, an employment law partner with the Energy and Natural Resources Group of Husch Blackwell, a law firm with offices in 18 U.S. cities. “But OSHA will consider across-the-board post-accident or post-incident testing to be potentially retaliatory and a violation of the new recordkeeping rule, the theory being that if the employer doesn’t have a reasonable suspicion that drugs or alcohol could have played a role in an incident, it will depress or otherwise discourage the reporting of injuries and illnesses in the workplace.”
Of course, this rule is problematic given the difficulty of determining marijuana impairment with existing tests (see The problem of impairment, previous page). It also presents the challenge of defining and documenting exactly what makes an injury or illness potentially drug related.
Hendrix provided the example of a bee sting (unlikely to be drug related) versus a forklift incident (conceivably drug related). “You don’t need any objective evidence that drugs did in fact play a role, and you don’t have to investigate the accident prior to sending the employee for drug or alcohol testing,” Hendrix said. “However, you should document why the type of accident that is being reported could reasonably have some relationship to drug or alcohol use.”