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One-Third of Employees Observed Cannabis Use at Work, Survey Finds

Cannabis is catching. Approximately 48.2 million people in the United States—or 18 percent of the U.S. population—used marijuana at least once in 2019, according to the U.S. Centers for Disease Control and Prevention. With the expansion of legalized medical or recreational marijuana in the United States, Canada, and other countries, workplaces face challenges around impairment, drug testing, and cannabis-related workplace accidents.

According to a recent survey from the National Safety Council (NSC), Understanding Cannabis in the Workplace, one-third of employees said they have observed cannabis use during work hours.

Additionally, among companies that have eliminated THC testing, more than half reported an increase in incidents or other workplace performance concerns.

Even where cannabis use is decriminalized or legalized, there are some legal exceptions for safety-sensitive jobs that could frequently face workplace accidents or dangers, according to the Society for Human Resource Management (SHRM). While this term is sometimes defined by federal or state statutes, it can also be left to the employer’s discretion.

“‘Safety sensitive’ is defined as one that if not performed in a safe manner, can cause direct or significant damage to property, and/or injury to the employee, others around him or her, the public and/or the immediate environment,” says Jenny Burke, senior director of the impairment practice at the NSC. This could include, for example, commercial motor vehicle operators.

In U.S. states that legalized recreational cannabis use early—including Colorado, Nevada, Oregon, and Washington—vehicle crashes increased as much as six percent, as reported in 2018. In addition, the National Highway Traffic Safety Administration’s preliminary estimates found that total traffic deaths increased 7 percent in 2020—with the increase being partly attributed to an increase in impaired driving.

The NSC survey found that more than half of employers identify illicit opioids, acute employee illnesses, and illicit stimulants as major concerns, but only a third of employers cited cannabis as a primary concern (around the same level as fatigue and alcohol).

In Colorado, where recreational cannabis was legalized in 2013, traffic deaths where drivers tested positive for cannabis increased 138 percent, while all Colorado traffic deaths increased 29 percent, according to a report from the Rocky Mountain High Intensity Drug Trafficking Area Investigative Support Center.

According to Ken Kolosh, statistics manager at the NSC, data is limited when it comes to measuring how cannabis-related workplace incidents compare to other impairment-related incidents because the U.S. Bureau of Labor Statistics does not collect information about the contributing causes behind incidents, such as impairment.

“Regarding impaired driving, the National Highway Traffic Safety Administration does report data regarding alcohol impairment but not drug impairment,” Kolosh says. “The latest 2019 data show 10,142 deaths (28 percent of total traffic deaths) result from crashes involving at least one alcohol-impaired driver.”

Other recent studies, including one out of Washington state, found that the percentage of drivers involved in fatal crashes with a positive THC test result increased from 8.8 percent (pre-decriminalization) to 21.4 percent in 2017. However, Kolosh cautions, testing positive for THC does not necessarily indicate impairment, especially since the effects of cannabis can vary greatly person-to-person, and THC is stored in body fat, not blood—changing how long it stays detectable in a person’s system.

The use of recreational cannabis is perceived as slightly more likely to cause impacts in the workplace, with 59 percent of employers saying impairment from recreational cannabis use would be a justifiable reason to fire an employee, and 56 percent saying it lowers the productivity of the workforce and causes workers to have more injuries.

However, employees view cannabis use differently—only one-third of employees said occasional use of cannabis is unacceptable, and the percentage decreases when focusing solely on CBD products and medicinal cannabis.

While most employers said that they believe employees would feel comfortable reporting to a manager that they were too impaired to work, less than half of employees said they would actually feel comfortable doing so. This finding plays into some of the NSC’s recommendations to employers to address cannabis risks at work:

  1. Establish a clear, fair cannabis policy that prevents impairment at work and provides employee support.
  2. Build a safety-focused, trusting culture for employees to report cannabis use at work.
  3. Advocate for increased access to employee assistance programs (EAPs) and healthcare benefits for employees with substance use disorders.
  4. Train supervisors to recognize and respond to impairment in the workplace.

“A strategy grounded in evidence-based human behavior theory is needed as a catalyst to change attitudes and beliefs, and ultimately influence widespread culture and behavior change,” Burke tells Security Management. “This is done by using proven safety countermeasures, advancing technology, and prioritizing safety.

“NSC recommends that organizations embody a psychologically safe environment,” she continues. “A team member feels psychologically safe when they share the belief that they will not be exposed to interpersonal or social threats to their self or identity, their status or standing, [and] their career or employment when engaging in learning behaviors such as asking for help, seeking feedback, admitting errors or lack of knowledge, trying something new, or voicing work-related dissenting views.”

Workplace impairment goes beyond cannabis, and training programs can alert employees and managers to the physical, cognitive, and performance-affecting signs of impairment caused by alcohol, opioids, cannabis, fatigue, mental distress, or stress. Broadening impairment awareness programs to a more holistic view can help destigmatize reporting.

Indicators of impairment can include (but are not limited to) the following, Burke says:

Physical Indicators

Cognitive Indicators

Performance Indicators

Rapid shift in physical appearance

Inappropriate verbal or emotional responses

Frequently calling off sick



Unexplained tardiness, early departures, or extended breaks

Unsteady gait or lack of coordination

Memory loss

Errors in judgment

Delayed reaction time

Inappropriate or abnormal behavior

Decreased concentration and vigilance

Odor of alcohol or drugs


Deterioration in performance or quality of work

Direct observation of substance use

Lack of concentration, confusion, or forgetfulness

Testing positive on a drug screen or impairment detection test

Lack of energy or chronic weariness


Loss of ability to do skilled tasks

Lack of consciousness




These indicators do not necessarily signify impairment, however. “Avoid jumping to conclusions about why someone is acting differently,” Burke says. “It is important for supervisors to stay connected with their employees in order to recognize when they may be acting differently.”