Research/studies Drugs Workplace exposures Respiratory conditions Worker Health and Wellness

Respiratory hazards in the cannabis industry: Researchers say ag standards may apply

Photo: FatCamera/iStockphoto

Berkeley, CA — Cannabis industry workers may be at increased risk of respiratory problems as a result of on-the-job exposure to various hazards, results of a recent study led by a University of Washington professor indicate.

Researchers studied workers at two legal cannabis growing facilities in Washington state. One was a 30,000-square-foot operation that used traditional growing methods and employed 45 workers – 31 of whom participated in the study. At the other location, a 20,000-square-foot facility that used all organic growing methods, 11 out of 20 workers took part.

As many as 7 out of 10 workers at the larger facility exhibited abnormal lung function based on spirometry tests, while half of the participants in the same facility experienced cannabis allergic sensitization along with borderline or high levels of exhaled nitrous oxide, which causes airway inflammation.

Ten workers at each facility who said they experienced respiratory symptoms were tested for exposures. At the larger facility, work areas were tested on eight different days. At the smaller facility, work areas were tested once.

The highest particle mass concentrations (60 micrograms per cubic meter) were measured in the trim task area, where the product is trimmed and prepared for sale. In contrast, the lowest concentrations were in the grow task area and an office area used as reference. Measurements in both areas were near 27 micrograms per cubic meter.

In 2017, the Washington State Department of Labor & Industries issued a hazard alert titled “Marijuana and Work-Related Asthma,” citing a connection between risk for work-related breathing problems and plant dust inhalation.

Christopher Simpson, a professor of exposure science at the UW School of Public Health, Environmental and Occupational Health Sciences, presented the study’s findings as the featured speaker on a March 10 webinar, hosted by the Center for Occupational and Environmental Health at the University of California, Berkeley. Simpson said lessons learned from other industries can be helpful for cannabis employers and workers.


“While some of the exposures may be unique to cannabis workers, many of these hazards are likely to be similar to those faced by other agriculture or horticultural workers,” he said. “Thus, we can apply much of what we’ve learned from those related industries in order to protect cannabis workers.”

Simpson and his research team concluded that cannabis facilities should adopt the American Conference of Governmental Industrial Hygienists’ Threshold Limit Value for cotton dust as an interim measure, in lieu of cannabis-specific measures. In addition, he encouraged employers to consider implementing exposure controls for tasks that generate high levels of dust, such as in the pre-roll task area, where crushed cannabis flower is packed into rolled joints and can create exposures.

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