Potential Exposures Associated with Indoor Marijuana Growing Operations

Abstract

We entered a total of 30 indoor marijuana grow operations (IMGO) with law enforcement investigators in order to determine potential exposures to first responders. Samples for airborne fungal spores, volatile organic compounds, carbon dioxide, carbon monoxide, and delta-9-tetrahydrocannabinol (THC) were obtained as well as the identification of chemicals utilized in the IMGO. The chemicals utilized within the IMGOs were primarily pesticides and fertilizers with none showing high toxicity. Although several of the IMGOs had CO₂ enrichment processes involving combustion, CO levels were not elevated. THC levels were identified on surfaces within the IMGOs and on the hands of the investigators. Surface levels ranged from <0.1 μg /100 cm² to 2000 μg /100 cm² with a geometric mean of 0.37 μg /100 cm². THC levels on the hands of officers ranged from <0.10 μg /wipe to 2900 μg /wipe with a geometric mean of 15 μg /wipe. These levels were not considered to be elevated to the point of causing a toxic exposure to responders. A total of 407 fungal spore samples were taken using both slit impactor plates and 400-hole impactors. Both methods identified elevated fungal spore levels, especially during the removal of plants from some of the IMGOs. After plant removal, spore counts increased to levels above 50,000 spores/m³ with one sample over 500,000 spores/m³. In addition, we found that there was a shift in species between indoor and outdoor samples with Cladosporium sp. the predominant outdoor species and Penicillium sp. the predominant indoor species. We concluded that the potential increase in fungal spore concentrations associated with the investigation and especially removal of the marijuana plants could potentially expose responders to levels of exposure consistent with those associated with mold remediation processes and that respiratory protection is advisable.

Keywords:

• fungal spores
• tetrahydrocannabinol
• carbon monoxide
• pesticides
• microbial growth
• pesticides

ACKNOWLEDGMENTS

This project was supported by Grant No. 2010-DJ-BX-0316 awarded by the Bureau of Justice Assistance, a component of the U.S. Department of Justice's Office of Juvenile Justice and Delinquency Prevention and the Office for Victims of Crime. The points of view or opinions expressed in the document are those of the author and do not represent the official position or policies of the Department of Justice. This project was also supported by grants from the Colorado Chiefs of Police and the Association of Colorado County Sheriffs. The Colorado Drug Investigators Association and the North Metro Task Force in Denver, Colorado, were instrumental in providing IMGOs in which to conduct the sampling as well as personnel to maintain security and assistance. Commander Jerry Peters and Sergeant Jim Gerhardt of the North Metro Task Force and the City of Thornton Police Department were instrumental in coordinating the project and providing law enforcement knowledge to the project.