Cannabis and Work: The Need for More Research

Posted on by Jamie Osborne, MPH, CHES®, and John Howard, MD


Cannabis sativa has been used for a wide variety of industrial, medical, and non-medical uses for thousands of years, yet remains a source of controversy across the fields of medicine, law, and occupational safety1-5. Access to and consumption of cannabis have increased as a result of more favorable public attitudes and state access laws. Nearly 18 percent of full-time workers and 21 percent of part-time workers used cannabis in 20186. Lifetime, past-year, and past-month use among full-time workers all increased from 2017 to 20186. The implications and challenges of increasing cannabis consumption by workers requires urgent and critical research attention. These issues are discussed in a new commentary, Cannabis and work: Need for more research, in the American Journal of Industrial Medicine. A summary is provided below.

Uses and Health Effects

Cannabis sativa contains 120 cannabinoids, only two of which have been studied for medical use: delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD)7-9. THC produces psychoactive effects in consumers and is responsible for the “high” associated with cannabis10,11. CBD is non-intoxicating and has potential therapeutic properties, but clinical data to support its medical benefits is limited12-14. Typical cannabis products, prepared from the flowering tops of the unfertilized female plant, contain 7 to 14 percent THC7. Medical cannabis sold in dispensaries has a similar THC concentration to cannabis sold for non-medical use15.

Cannabis was widely used for a variety of medical ailments throughout the 19th and early 20th centuries, until a series of federal laws beginning in the 1930s penalized the sale and use of medicinal cannabis and ended its legitimate medical use16. However, pharmaceutical-grade cannabis products have recently been approved by the U.S. Food and Drug Administration for the treatment of childhood epilepsy syndromes, as well as nausea and vomiting associated with a variety of conditions17-20. Cannabis is also consumed for enjoyment and without medical justification, using a variety of products with varying potency levels and routes of administration. In addition to a variety of acute health effects, including dizziness, dry mouth, nausea, vomiting, drowsiness, euphoria, disorientation, confusion, loss of balance, and hallucination21, chronic use in some individuals can result in cannabis use disorder (CUD). CUD is characterized by dependence, withdrawal symptoms, failure to meet work, school, or home responsibilities, tolerance to greater amounts of cannabis, and other qualifying symptoms22-25.

Cannabis and Workplace Injury

Increasing access to and consumption of cannabis by workers have led to increased concerns about workplace safety4,26-29. Research is needed to explore the incidence of cannabis consumption by industry and occupation, as well as the relationship between cannabis consumption by workers and occupational injuries. Such research should consider temporal relationship between consumption and injury, confounding variables (e.g. gender, safety climate, training, and fatigue), and factors potentially influencing work impairment from cannabis consumption, including timing, intensity, duration, potency, and route of administration30. Cannabis industry workers face unique workplace safety and health risks, including exposures to chemical, biological, and physical hazards31. Exposures may also affect law enforcement, fire fighters, emergency medical technicians, and hazardous materials response personnel working around cannabis or responding to cannabis industry sites32-34.

Cannabis, Occupational Driving, and Job Impairment

Even though there has been considerable research about cannabis consumption, driver performance, and vehicular crashes indicating that driving under the influence of cannabis does increase the risk of traffic crashes24,26,28,35-38, further research is needed to determine the prevalence of cannabis consumption by workers who drive as part of their job. Determining driver impairment from cannabis consumption also remains a complicated but critical research need.

Since cannabis is stored in body fat and released into the bloodstream over days or weeks from the time of actual consumption, THC levels detected in a positive urine or blood drug test do not permit sound inferences about the frequency of cannabis consumption, specific time of last use, or cannabis-related impairment39-42. Impairment testing provides a promising adjunct or alternative to traditional workplace drug testing that would evaluate real-time deficits in job performance from multiple causes, such as lack of sleep, chronic medical conditions, effect from physician-prescribed medications, and self-prescribed drugs, including cannabis. Some impairment tests are modeled after traditional field sobriety tests used by law enforcement43, and newer digital tests are available as applications that resemble video games44. More intervention studies are needed to validate the effectiveness of workplace impairment testing methodologies.

Workplace Supported Recovery

Workplace programs that provide access to support, counseling, and treatment can be an important means to achieve recovery from all substance use disorders, including CUD, while maintaining employment—a key goal for workers in recovery45. The 2020 U.S. National Drug Control Strategy encourages “workplace support for current employees in treatment and recovery,” which may reduce the stigma associated with substance use disorders and lower barriers to seeking and receiving care46. Workplace Supported Recovery programs aim to prevent work-related exposures that may contribute to substance use disorders and provide access to support and treatment for workers in recovery.

Legal Landscape

In 1970, the Controlled Substances Act (CSA) consolidated all federal laws that regulated controlled substances47, making it unlawful to manufacture, distribute, dispense, or possess a controlled substance (21 U.S.C.§841(a)), including cannabis. However, shifting public attitudes have led 33 states, along with the District of Columbia, to approve access laws that make cannabis available to consumers with qualifying medical conditions48. Eleven states, and the District of Columbia, allow consumer access to cannabis for medical and non-medical use48. Additionally, many states have passed laws decriminalizing the possession and use of small amounts of cannabis and expunging or vacating criminal records for qualifying cannabis convictions49. As the debate over national legalization of cannabis continues, so does the uncertainty regarding cannabis and workplace drug testing programs, workplace substance use policies, worker’s compensation claims, and employment litigation.

Need for More Research

As the legal and cultural landscapes of cannabis access and consumption continue to evolve, implications for workplace policies, programs, and practices become more salient. Critical research attention should be focused on these implications and the challenges surrounding cannabis and work. Among these research challenges are the following:

  1. data about industries and occupations where cannabis consumption among workers is most prevalent;
  2. adverse health consequences of cannabis consumption among workers;
  3. relationship between cannabis consumption and occupational injuries;
  4. hazards to workers in the emerging cannabis industry;
  5. cannabis consumption and its effect on occupational driving;
  6. ways to assess performance deficits and impairment from cannabis consumption;
  7. workplace supported recovery programs; and
  8. ways to craft workplace policies and practices that take into consideration conflicting state and federal laws pertaining to cannabis.


How has your workplace addressed issues surrounding cannabis? Please share with us in the comment section below.


Jamie Osborne, MPH, CHES® is a Public Health Analyst with the NIOSH Office of the Director.

John Howard, MD, is the Director of the National Institute for Occupational Safety and Health (NIOSH).



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Posted on by Jamie Osborne, MPH, CHES®, and John Howard, MD

11 comments on “Cannabis and Work: The Need for More Research”

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    IMMAD-Impairment Measurement Marijuana and Driving is an objective test of retinal function to be used roadside by law enforcement. IMMAD uses a simple VR goggle and Bluetooth response button. The VR displays small striped squares of variable contrast. Driver’s having recently used marijuana cannot see many of the squares. If a driver cannot see accurately, they cannot drive safely. There are 34 states that already have laws regarding the reductions horizontal peripheral vision (which IMMAD measures) and Kentucky defines the reductions in superior vision before a driver is deemed unsafe and cannot legally drive. IMMAD measures functions that are directly related to safe driving.

    Thank you, Dr. Valenti, for providing information about the IMMAD (Impairment Measurement Marijuana Driving) test for use by law enforcement at the roadside.

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Page last reviewed: August 7, 2023
Page last updated: August 7, 2023