Navigating the Marijuana Use Landscape to Support Safe Workplaces 

June 4, 2025 | General

As marijuana laws continue to evolve across the U.S., employers are facing a growing challenge: how to maintain a safe, compliant, and productive workplace while navigating shifting legal expectations around cannabis use.

With more states legalizing marijuana for medicinal and recreational purposes, questions are emerging around what employers can legally require when it comes to drug testing, workplace impairment, and maintaining a drug-free environment. This post, the third in a five-part series on drug and alcohol testing and drug-free workplace policies, breaks down the current legal landscape and outlines what employers can and cannot do when it comes to managing marijuana use among employees. Be sure to read Part 1: Workplace Substance Testing – A Safety Essential and Part 2: Why Employers Test for Drugs: Managing Risk, Safety, and Workforce Readiness.)  

U.S. employers must navigate an evolving legal and social landscape when addressing the potential for impacts on workplace safety caused by employees who use marijuana before or during work. The terrain is pocked with contradictions.  

Legal Conundrums: Medical Marijuana and Cannabis 

Medicinal marijuana use is legal with a medical provider’s recommendation (not a prescription) in more than 75 percent of states. Recreational use is legal in more than 20 states and Washington, D.C. However, cannabis remains listed as a Schedule I drug with a high potential for abuse and no accepted medical use under the Controlled Substances Act, making its use in federal jurisdictions illegal.  

In 2024, the U.S. Drug Enforcement Administration initiated a review to potentially reclassify cannabis to Schedule III (substances with moderate-to-low potential for physical and psychological dependence), but that proposal is now on hold without a projected date for renewed consideration. The Americans with Disabilities Act (ADA) does not require job accommodations for medical marijuana use because it is still illegal under federal law. Meanwhile, state courts are being asked to allow employees to use marijuana to manage chronic medical conditions. 

Attorneys say federal enforcement of laws to prevent the possession, cultivation, or intrastate distribution of cannabis in states where use is legal is not rigorous. But employers working with the federal government or operating in federally regulated sectors (such as transportation, aviation, or defense) are still required to maintain zero-tolerance policies. The Department of Transportation, for instance, mandates drug testing that includes marijuana, regardless of state laws. Non-regulated employers also have the right to create and maintain drug-free workplace policies – including testing for marijuana and the medical review of certain test results – to help reduce the potential for negative impacts on performance at work, particularly in safety-sensitive environments.  

Medical Versus Recreational Marijuana Use by Employees 

When evaluating impairment and its risks, it helps to understand the difference between cannabis and marijuana. Cannabis refers to the Cannabis sativa plant. Marijuana refers to the dried, leafy, and flowering parts of the plant, particularly those containing elevated levels of tetrahydrocannabinol (THC), the psychoactive compound. THC and cannabidiol (CBD), a component used in medications, are cannabinoids. They interact with neurotransmitters in the brain that influence pain, the immune system, stress reactions, sleep quality, and other critical physical and mental health functions.  

Some cancer patients use THC to help relieve chemotherapy-induced nausea, vomiting, and to help stimulate their appetite. For recreational use, THC is primarily responsible for the “high” that users experience. Most recreational users smoke marijuana, but it’s also available in oils, edibles, tinctures, capsules, and other products. 

Cannabis is referred to as hemp when it contains less than 0.3 percent of THC content by dry weight. CBD in hemp is used medicinally to help relieve pain, reduce inflammation, and treat symptoms of anxiety without mind-altering effects. Cannabidiol is approved by the U.S. Food and Drug Administration to treat seizures in certain people, and it is being studied for use by cancer patients. It is contained in medicinal gels, gummies, oils, supplements, and extracts.  

Marijuana Impairment Assessment Precautions 

Tests are used to detect the presence of marijuana metabolites in a specimen. The role of a Medical Review Officer is important because physician review of non-negative findings can be the deciding factor in whether an employee who is using marijuana to manage symptoms of a physical or mental health condition poses a workplace safety risk. 

Cannabinoids can remain in a user’s system and may be detectable in a drug test long after the physical or cognitive effects that could temporarily impair performance subside. Consequently, some states limit an employer’s ability to take adverse employment actions based on off-duty recreational use without corresponding signs of use or impairment while on duty. 

While there are correlations between substances use and higher rates of workplace accidents, injuries, and fatalities (refer to Part 1 of this blog series for related statistics), the degree of influence marijuana use may have in such incidents requires further investigation. Scientific research on the short- and long-term effects of marijuana use on human performance is ongoing. 

In a 2024 study published in the JAMA Health Forum, researchers found that the legalization of recreational marijuana was associated with a 13 percent increase in workplace injuries per 100 full-time workers aged 24 to 34 years old. Paradoxically, researchers said the findings may be “directionally ambiguous” and noted that:  

“Recreational marijuana laws may be associated with greater workplace injuries if increased marijuana use diminishes workers’ cognitive functioning or acts as a gateway to harder drugs, or they may be associated with fewer injuries if marijuana treats pain that contributes to workplace accidents or induces substitution away from alcohol or opioids.”  

Signs and Symptoms of Marijuana Impairment 

Drug-free workplace policies often require front-line supervisors to be trained to recognize signs and symptoms of potential drug or alcohol use by an employee. For marijuana users, these may include: 

  • Dizziness or disorientation
  • Mood fluctuations 
  • Forgetfulness 
  • Poor concentration 
  • Sleepiness 
  • Altered sense perceptions 
  • Lack of coordination 
  • Nausea 

Less apparent symptoms may include dry mouth, rapid heart rate, and increased appetite.  

Long-term physical and mental health effects are associated with the toxins, irritants, and carcinogens that are contained in some cannabis products.  

According to the National Institute on Drug Abuse (NIDA), chronic, heavy, or daily use of cannabis products with THC can lead to the development of cannabis (substance) use disorder. An estimated 20 to 30 percent of people who use cannabis have the disorder, which is characterized by clinically significant impairment or distress. In addition, NIDA reports that habitual inhalation of marijuana smoke may harm lung tissue, cause respiratory distress, or increase cancer risk. Marijuana use is also linked to problems with learning and retention, processing speed, perceptual motor function, and language.  

Social Considerations of Employee Marijuana Use 

Statistics and survey results suggest a mixed bag of attitudes toward marijuana use, which appear to be influenced by the nation’s gradual shift toward legalization. Here are some related findings: 

  • The National Center for Drug Abuse Statistics reports that about 17 percent of American adults use marijuana, and about half of the U.S. population has tried it at some point in their lives.  
  • YouGov, an international research data and technology group, found in a 2024 survey that three in five American adults – including those in the workforce – believe marijuana is less harmful to health than drinking alcohol or smoking cigarettes, and that it is not a gateway to the use of addictive substances such as opioids. Among 24 percent Americans who said they had used marijuana in the past year, 35 percent used it daily. 
  • A 2024 Pew Research survey found that 57 percent of Americans favor legalization of both medical and recreational marijuana, 32 percent support medical use only, and 11 percent are opposed to any legal use. 
  • In a Gallup Consumption Habits poll, 42 percent of respondents said marijuana use has positive effects on society and consumers; 50 percent said it has negative effects. 

Testing Methods for Marijuana (THC) 

The testing method used to detect the presence of marijuana (THC) in an employee’s system depends on the circumstances (e.g., pre-employment, random, post-accident), applicable workplace policies and regulations, and how recently it was used. Behavior-based assessments and observations of employee performance are being used in combination with testing or as an alternative to it in some cases. 

Testing methods include: 

  1. Urine: Specimens are collected to detect THC metabolites, not active THC that could cause current impairment. Urine testing is common and includes both lab-based and point-of- collection test results. Marijuana detection windows can vary from three to five days for occasional users to 30 or more days for heavy/chronic users.  
  2. Oral fluid (saliva): A mouth swab is used to collect saliva. The test detects active THC, typically immediately after use and for up to 24 to 72 hours. After collection, the swab is placed in a solution and is analyzed on-site or sent to a laboratory for testing.  
  3. Hair: Hair samples are sent to a lab to detect THC metabolites. The detection window spans up to 90 days, excluding the seven days before testing. Hair testing provides a long window of detection for repetitive use, and unlike urine, samples are difficult to adulterate. 
  4. Blood: A blood sample is tested to detect active THC within 12 to 14 hours of use and metabolites within 48 or more hours in heavy users. It is typically used after an accident and for law enforcement investigations.  
  5. Sweat patch: A patch is worn on the skin for seven to 14 days, then tested for excreted THC metabolites. Patches are sometimes used to monitor people in rehabilitation facilities or who are on probation; they are not commonly used for workplace testing. 
  6. Breath: This method uses a device (similar to an alcohol “breathalyzer”) to detect molecules in the breath that indicate recent consumption. The technology is new and not fully developed for the marketplace. Unlike alcohol, THC has low concentrations in breath that may not be detectable after a brief time, and a baseline cutoff measure for impairment has not been legally established. 

Reach Out to WorkCare 

U.S. employers are caught in a balancing act when assessing the potential impacts of marijuana use. They must weigh the importance of compliance with existing laws, workforce health, and public safety – especially in high-risk environments – and employees’ right to privacy and legal use away from their workplace. WorkCare’s subject matter experts can provide guidance on cost-effective ways to reduce exposure risk and manage employee use of marijuana for medicinal or recreational purposes. Reach out to our team to develop a plan that works for your workforce and your business. 

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