Analysis of elemental impurities in cannabis following vaporization

The use of vaporizers to inhale cannabis is a technique that has risen in popularity among the American public. There is a general perception that vaporizers are “safer” when compared to more traditional cannabis smoking via combustion (i.e., cigarettes). The inherent use of heated air in vaporizers might reduce the respiratory toxicants or protein toxins by heating cannabis to a temperature where active compounds form in vapor phase. Yet this temperature is below the point of combustion where smoke and associated toxicants are produced. The elemental impurities are a general concern in all botanical products including cannabis and cannabis-derived products (CCDPs). This study aimed to investigate the potential transfer of those metallic elements from cannabis material to cannabis vapor through the vaporization process. A Volcano Digit Vaporizer (Storz & Bickel) was used as the heating device to perform the vaporization. Three cannabis plant materials were evaluated with varying contents of cannabinoids, including a cannabis placebo (<0.01 % Tetrahydrocannabinol (THC), Cannabidiol (CBD) & Cannabinol (CBN)), cannabis with low potency (2.0 % THC/ 0.02 % CBD/ 0.47 % CBN) and high potency (6.7 % THC/ non detectable CBD/ 0.49 % CBN). Baseline elemental impurity levels were evaluated for all cannabis plant materials. Four different types of heat treatment, namely no heat, 30 seconds (s), and 70 s heat treatment, and finally 70 s heat treatment with air flow, were developed for the three cannabis materials and the experimental samples after vaporization were analyzed by an inductively coupled plasma-mass spectrometry (ICP-MS) system. The results showed that sixteen elemental impurities were detected, and all have similar concentration, between 10 ng/g and 8 × 10⁶ ng/g, in the three types of cannabis materials, where Mg was measured with the highest content. Within the four heating treatments evaluated no significant changes of these metallic elements (elemental impurities) were found when compared to the plant materials. This preliminary experimental study evaluated a single vaporizer and three cannabis plant materials suggesting a transfer of metallic elements from cannabis material to cannabis vapor may not occur during the vaporization process under these study conditions.