Brynne Silvey

Project title: Characterization of occupational exposure to airborne contaminants in an indoor cannabis production facility

Degree: MS (Thesis) | Program: Occupational Hygiene (OH) | Project type: Thesis/Dissertation
Completed in: 2019 | Faculty advisor: Christopher D. Simpson


Background: While the cultivation and the use of cannabis continues to be illegal at the federal level in the United States, states and districts that have made medicinal and recreational use legal have seen dramatic increases in the number of workers being employed by cannabis-related companies. Little effort has been made to characterize and identify occupational hazards that workers may be facing in this industry, specifically airborne contaminants that may affect the human respiratory system. The purpose of this study was to quantify occupational exposures to Particulate Matter (PM) and Volatile Organic Compounds (VOCs) in various task zones (trim, pre-roll, grow and office) of an indoor cannabis facility in Washington State. Methods: Full-shift (8-hour) area measurements of PM and VOCs were collected in each task zone over a 2-month study period at a single facility in Seattle. Measurement devices were placed near the employee's work area in order to attempt to estimate the exposure to the contaminants. The Dylos DC1100 Pro real-time optical particle counter with 4 size bins was used to measure particle number concentration (PNC), particle mass concentration (PMC) and cumulative size distribution of the particles in each task zone (n=8 per task). To quantify the VOC total terpene mass concentrations, a pump and sorbent tube set up was used in the trim (n=7), pre-roll (n=7), grow (n=8) and office (n=7) task areas. Sorbent tube samples were then analyzed for total terpene mass using GC/MS. Finally, correlations between PMC and total terpene mass concentrations were assessed. Results: The mean PMCs were greater in task zones that required the employees to manipulate the cannabis plants and materials. The (PMC) for the trim task was 59 g/m3, pre-roll task was 50 g/m3, grow task was 43 g/m3 and for the referent office area was 19 g/m3. When comparing each task zone PMC to the office referent PMC, the trim task and the pre-roll task were significantly higher than the referent group, (p-values both <0.001). Results for the terpene samples indicated that the mean terpene mass concentration for the trim task was 34 mg/m3, pre-roll task was 11 mg/m3, grow task was 16 mg/m3 and for the office referent space was 1.5 mg/m3. When comparing each task zone total terpene mass concentration to the office space, only the trim task area was significantly different from the referent office space (p-value = 0.002). Correlations between PMC and total terpene mass concentrations for each task zone were weak based on spearman rank correlation tests. Conclusions: Area concentrations of both PM and VOCs were greatest among the trim task area, followed by the pre-roll task and the grow task areas. This data can help inform the employer of the task zones where exposure to respiratory hazards are the highest, and where it may be beneficial to deploy control measures to reduce exposure. Results from the area measurements of PM and VOCs suggest that further research on employee personal exposure to similar airborne contaminants is needed to expand the knowledge base of exposures in this unique industry.