In nearly 24,000 Swedish workplace drug tests, 4.6% came back positive—and cannabis was the most commonly detected substance, found in over 40% of positive results.
Employers designing drug testing policies, occupational health professionals, and anyone interested in how cannabis use intersects with workplace safety.
What the researchers found
This analysis of 23,900 workplace drug test results from Sweden provides a snapshot of substance use among employed people. The overall positive rate was 4.6%, with cannabis dominating at over 40% of all positive results.
The testing circumstances mattered. Random tests and new-employment screenings made up the majority of samples (40% and 36% respectively), but the highest positive rates came from tests done after accidents or incidents, or when there was already suspicion of drug use. The construction sector had the highest rate of positive random tests.
A key practical point the study raises: several controlled substances that trigger positive tests are also legitimately prescribed—amphetamines for ADHD, benzodiazepines for anxiety, and opiates for pain. Without medical review of positive results, employers risk penalizing workers for taking prescribed medication. The authors argue this makes medical review officer (MRO) involvement essential in any workplace testing program.
While this is Swedish data and drug testing policies vary internationally, the finding that cannabis is the most common substance detected in workplace tests is consistent with data from other countries.
Why it matters
As cannabis legalization expands globally, workplace drug testing policies are under increasing scrutiny. This data shows cannabis dominates positive workplace tests even in Sweden, where it remains illegal. For countries and states with legal cannabis, the tension between workplace safety and employee rights is even more acute—particularly since cannabis can be detected long after impairment has worn off.
The numbers in context
23,900 tests analyzed. 4.6% positive overall. Cannabis: >40% of positive results. Random testing and new employment: 76% of all samples. Construction: highest positive rate on random tests.
How the study worked
Cross-sectional analysis of 23,900 urine and oral fluid drug test results from Swedish workplaces in 2023. Tests categorized by circumstance: random (40%), new employment (36%), accident/incident, or suspicion-based. Results analyzed by substance detected and industry sector.
Who was studied
N=23,900 adults from various workplaces in Sweden
What this study cannot tell us
Swedish data may not generalize to countries with different drug policies, cannabis legality, or workplace testing cultures. No information on impairment at the time of testing. The study can't distinguish between recreational and medicinal use. Urine testing for cannabis detects metabolites from days or weeks prior, not current intoxication.
How to read the evidence
Large cross-sectional analysis of real-world workplace testing data, though limited to one country and one year.
When this study was published
Published in 2025 with 2023 testing data from Sweden.
The bigger picture
This connects to the broader question of how workplaces should respond to changing cannabis laws and norms. The fact that cannabis metabolites persist in urine for weeks means a positive test doesn't necessarily indicate current impairment—a gap that has led some employers and jurisdictions to move toward impairment-based testing rather than substance detection. The prescription medication overlap issue also highlights how workplace testing intersects with the medical cannabis landscape (see RTHC-00161 on medical marijuana policies and prescribing).
Replication
Not stated in abstract.
Funding
Not reported in abstract.
Conflicts of interest
Not reported in abstract.
Questions still open
- How would positive rates change in countries where cannabis is legal? Should workplace testing shift from detection to impairment-based approaches? What is the actual safety impact of cannabis-positive workers versus other substances?
Read the original research
Workplace Drug Testing-Prevalence of Positive Test Results, Most Common Substances, and Importance of Medical Review.
Drug testing and analysis, 17(9), 1694-1700
Drug Testing and Analysis is a peer-reviewed journal focusing on the science and technology of drug testing.
Citation
Helander, Anders; Sparring, Fredrik. (2025). Workplace Drug Testing-Prevalence of Positive Test Results, Most Common Substances, and Importance of Medical Review.. Drug testing and analysis, 17(9), 1694-1700. https://doi.org/10.1002/dta.3863
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