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Big changes are coming to the Colorado cannabis industry. On October 7, 2020, Colorado’s Marijuana Enforcement Division (CMED) added a new rule to the state’s list of cannabis regulations which will require heavy metal emissions testing for all marijuana concentrates placed into vaporizer delivery devices (Statement of Adoption; CCR 212-3). Effective January 1, 2022, “each harvest batch and production batch of regulated marijuana concentrate in a vaporized delivery device must be tested for metals contamination via emissions testing” by an accredited laboratory in the state of Colorado (CCR 212-3). All products that require testing for metals contamination include regulated marijuana flower and trim; water-based, food-based, heat/pressure-based, and solvent-based medical and retail marijuana concentrates; regulated marijuana products; pressurized metered-dose inhalers; vaporizing delivery devices; audited products; and industrial hemp products (CCR 212-3). The metals contamination testing must include but is not limited to, testing for the “presence and amounts” of arsenic, cadmium, lead, and mercury (CCR 212-3). The acceptable limits of metals in these products are dependent upon product type and the route of exposure (e.g., inhalation, dermal, oral, and rectal/vaginal administration), and range between <0.1 and <0.5 ppm for inhalable products, <1 and <10 ppm for topical and/or transdermal products, and <0.5 and <1.5 ppm for oral and rectal/vaginal products (CCR 212-3).  

Although emissions testing is a new requirement within the Colorado cannabis industry, this type of testing is not uncommon for aerosolizing devices, especially in the electronic nicotine delivery systems (ENDS) industry. Since 2016, when the U.S. Food and Drug Administration (FDA) received authority to regulate vaping devices or ENDS as a tobacco product, guidance documents published by the agency have included recommendations for aerosol testing to characterize harmful and potentially harmful constituents (HPHCs), which include several heavy metals, in ENDS products. Understanding potential exposures from harmful constituents like heavy metals ultimately provides policymakers with the necessary information to evaluate these products (vaporized cannabis products) from a public health perspective.

Where Do Heavy Metals in Cannabis Come From?

Contamination of heavy metals in cannabis can occur during the growth cycle, processing, or post-processing of cannabis plants and cannabis products (Analytical Cannabis 2019). During the cultivation and the production process, there are various sources that contain heavy metals and can thereby contaminate the crop, including soil, water, fertilizers, nutrients, and pesticides (Analytical Cannabis 2019; Analytical Cannabis 2020). Cannabis plants have been shown to be efficient in the uptake of heavy metals from soil (Zerihun et al. 2015). While contamination of heavy metals in soil is a growing concern, hemp is suitable for phytoremediation of contaminated soil as it is capable of removing significant quantities of contaminants that are generally stored in its roots (Florida Hemp Coalition). Furthermore, other sources that can contribute to heavy metal contamination include machinery or equipment used in the production process as well as equipment used to package and deliver cannabis products, such as inhalers, vaporizers, transdermal patches, bottles, and containers (Analytical Cannabis 2019; Analytical Cannabis 2020).

Why is This Important?

Exposure to heavy metals has been associated with several adverse health outcomes. Some heavy metals have the ability to bioaccumulate and disrupt and alter functions of vital organs and glands in the human body, including the brain, kidney, liver, and blood (Engwa et al. 2019; Jaishankar et al. 2014). Several heavy metals are also known to lead to carcinogenic and reproductive adverse effects (Badr and El-Habit 2018; Engwa et al. 2019). The FDA currently regulates heavy metal elemental impurities in drug products as they “pose toxicological risks to patients without providing any therapeutic benefit” (FDA 2018). However, when evaluating the safety of consumer products, like vaporizing cannabis products, the dose of heavy metals will ultimately dictate whether the use of those products will lead to any critical health effects. The action limits set by Colorado for heavy metals in inhalable marijuana products are based on the United States Pharmacopeia (USP) <232> Elemental impurities – Limits for pharmaceutical products, substances, and excipients. Although acceptable limits within USP <232>, specifically for Class 1 impurities (heavy metals), are based on safety or toxicity data for each metal, these limits are set to control levels in drug products since elemental impurities do not provide any therapeutic benefit to patients. Nevertheless, action limits based on health effects, such as the ones provided by the state of Colorado for inhalable marijuana products, are considered appropriate comparisons when evaluating the absolute risk associated with consumer products.

How Cardno ChemRisk Can Help

Cardno ChemRisk scientists have extensive experience in assisting the e-cigarette or ENDS industry with designing and conducting aerosol characterization studies as part of FDA regulatory compliance, as well as performing human health and environmental risk assessments on a wide range of metals, as well as other HPHCs. For more information on Cardno ChemRisk’s capabilities, please contact Elise de Gandiaga or Heidi O’Neill.