Cannabis Rolling Papers Found to Contain Heavy Metals and Pesticides above California Regulatory Levels

Posted on Behalf of  Dami Adebambo

In states that have legalized cannabis, batch laboratory testing is required at various stages of production prior to sale to protect consumer health and safety (NCIA Policy Council 2018). While the regulatory limits set for these tests vary between states, they primarily screen for potency, residual pesticides, heavy metals, and microbial contamination (NCIA Policy Council 2018). Furthermore, some states, such as California (CA), require cannabis products entering the market to be tested for regulated contaminants “in their final form” (NCIA Policy Council 2018, California AB-1470 Cannabis testing 2020). In September, 2020, a Santa Cruz, CA based laboratory (SC labs Inc.) that performs regulatory compliance testing was alerted to pesticide contamina­tion in pre-roll products submitted for compliance testing by an unnamed client (SC Labs Analysis Report 2020). Batches of cannabis flower used to produce these pre-roll products had previously passed testing, with none of the 21 regulated (BCC, 2017)*pesticide residues detected. When prepared as a pre-rolled product, however, chlorpyrifos was unexpectedly detected (SC Labs Analysis Report 2020). Suspecting that this contamination might have resulted from the rolling papers used, SC Labs collected and tested 118 different rolling paper brands, blunt wraps, and hemp cones sourced from local smoke shops and online retailers in July, 2020 (SC Labs Analysis Report 2020). Overall, 11% (13 of the 118 samples) contained pesticides or heavy metals over the action limits established by the CA Bureau of Cannabis Control (SC Labs Analysis Report 2020). Of the 101 samples tested for heavy metal contamination, 90% had at least one heavy metal (arsenic, cadmium, lead, or mercury) present, with lead most frequently detected (SC Labs Analysis Report 2020). Furthermore, 8% of the papers contained levels of heavy metals (arsenic and lead) that would have failed state-testing standards (rolling papers alone are not required to undergo state cannabis compliance testing) (SC Labs Analysis Report 2020).

Sources of Rolling Paper Contamination

Plant fibers, such as wood pulp, flax, hemp, and rice straw, and natural plant extracts such as cellulose are the most common materials used to make rolling papers (The Rolling Paper Company 2020). SC Labs reported that, according to the labels on the rolling papers tested, “The products were made from either rice paper, hemp, or cellulose … [although] many of the products were not labeled with the source fiber used” (SC Labs Analysis Report 2020). These materials have a high capacity for accumulating heavy metals and pesticides in their tissues, and, as such, detectable levels of these contaminants have been found in many natural fiber-based materials (SC Labs Analysis Report 2020, Dryburgh LM et al., 2018, Husain et al., 2019).

Health Effects

Arsenic, cadmium, lead, and mercury are systemic toxicants associated with numerous health effects at certain levels (Tchounwouet al., 2012). According to the SC Lab report, two clear cellulose papers contained 55.1 and 60.3 μg lead/g respectively, far above the CA action limit of 0.5 μg/g for lead in cannabis products (BCC, 2017). In addition, one flavored hemp wrap and two flavored cigar cones had arsenic levels of 3.2, 1.6 and 5.4 μg/g, respectively (SC Labs Analysis Report 2020). Similar to lead, these arsenic levels are higher than the action limit set by CA of 0.2 μg/g for inhalable cannabis goods (BCC, 2017). None of the tested rolling papers or cones contained mercury levels above the action limit, while one product contained 0.56 µg/g cadmium, slightly above its action limit of 0.5 µg/g (SC Labs Analysis Report 2020, BCC, 2017). Although conservative health risk estimates were utilized in setting these limits (BCC, 2017, FDA 2020), using contaminated rolling papers consistently and at high-volume could potentially result in exposure levels of concern, and subsequent health effects. Hence, to accurately characterize the type and likelihood of these health risks, a comprehensive human health risk assessment utilizing the four steps of hazard identification, dose-response assessment, exposure assessment, and risk characterization should be performed. The goal of the risk assessment would be to ultimately identify and characterize associated health risks for all types of cannabis rolling paper consumers and usage levels.

Cardno ChemRisk Capabilities                                                             

Cardno ChemRisk scientists have extensive experience characterizing potential exposures and health risks posed by various chemicals (e.g., metals and pesticides) in consumer products, including vaping devices that deliver inhalable aerosols, as well as foods and personal care products, using state-of-the-art risk assessment methods. As part of the cannabis initiative, our team offers a multidisciplinary approach to resolving health and safety issues related to cannabis and cannabis-derived products. For more information on Cardno ChemRisk’s capabilities, please contact Elise de Gandiaga or Heidi O’Neill.