What’s in Your Gummy? State Cannabis Contaminant Rules Vary Widely

Abstract

With every passing year, more U.S. states move to fully legalize cannabis, or at least permit its medical use. The federal government, by contrast, continues to view cannabis as an illegal drug. Absent federal oversight, states have enacted a patchwork of policies governing product testing, quality, and safety—roles usually fulfilled by the U.S. Environmental Protection Agency, the Food and Drug Administration, and the Department of Agriculture. The resulting lack of rigorous, universal standards for regulating common cannabis contaminants has significant implications for public health, write the authors of a new study in Environmental Health Perspectives.¹

People who use cannabis medically may be particularly vulnerable to harm from exposure to contaminants, notes senior author Maxwell Leung, an assistant professor of pharmacology and toxicology at Arizona State University. Various compounds in the plant are used to treat or alleviate symptoms of a variety of health conditions, including seizures, epilepsy, and Parkinson’s and Alzheimer’s diseases. Cannabis can also help reduce side effects of common therapies for AIDS and cancer.² The global market for medical cannabis is currently worth approximately USD $\$10\text{\hspace{0.17em}billion}$ and is expected to grow rapidly in the coming years.^3,4

Contaminants in cannabis and its products—including foods such as gummies and cookies, plus tinctures, topicals, and concentrates—are regulated by the states that permit some or all uses. The result is a patchwork of different testing rules, methods, and action levels. Image: © Shelby/stock.adobe.com.

During cultivation and subsequent processing, cannabis flower (the part of the plant commonly used for smoking) and cannabis-derived goods (such as concentrates, extracts, and edibles) can be contaminated with potentially harmful substances. Pesticides applied directly to plants or dispersed from nearby fields may exhibit neurotoxicity, as can metals absorbed into plant tissues from soils and fertilizers.^5–8 Bacterial and fungal pathogens that can grow on flowers before and after harvest may pose a risk of serious infection to immunocompromised users.⁹ Residues of solvents used to concentrate or extract desired compounds may have other ill effects.¹⁰

In the new study, researchers from Arizona State University and two California-based cannabis testing labs reviewed the disparate rules regulating cannabis contamination across the jurisdictions—36 states and the District of Columbia—that permitted recreational or medical use as of May 2022 (legislative changes are ongoing¹¹). They tracked which substances were screened for and how much of each substance was allowed. The authors found particularly large discrepancies in the regulation of pesticides. For example, although 27 jurisdictions tested for the fungicide myclobutanil, just two tested for the insecticide ethion, even though both may be harmful to human health.^12,13 Four jurisdictions regulated more than 400 different pesticides on cannabis; most of the rest regulated fewer than 100.

Next, the authors compared test results for nearly 10,000 cannabis samples previously analyzed by CannaSafe—a state-licensed testing laboratory in California—against the jurisdictions’ range of “action levels” (pass/fail limits) to further assess regulatory variation. Myclobutanil was detected in 16 samples at concentrations ranging from 0.1 to 41.2 ppm. In the 27 jurisdictions that regulated the chemical, action levels varied from 0 to 1.0 ppm, so regulatory responses to detection of these fungicide residues also would be expected to vary widely.

In addition, the authors used jurisdictional licensing data to characterize populations who use medical cannabis. By far the most commonly cited reason for use was chronic pain (nearly 800,000 reported users), followed by posttraumatic stress disorder ($\text{approximately\hspace{0.17em}}\mathrm{164,000}$ users). Spasticity, cancer, seizures, irritable bowel syndrome, and dozens more reasons also were reported.

“This study demonstrates an urgent need for a unified regulatory approach to mitigate the public health risk of cannabis contamination at a national level…. In our opinion, this guideline should be based on human health risk assessment methodologies consistent with other agricultural and food commodities,” the authors concluded.¹ They also recommended a more stringent approach to regulating medical cannabis.

Chris Hudalla, founder and chief scientific officer ProVerde Laboratories, a cannabis testing company with facilities in Maine and Massachusetts, notes that though these issues are widely acknowledged in the rapidly expanding legal cannabis industry, they may well persist for some time. “Short of federal legalization of [cannabis], there does not appear to be any chance of harmonizing safety standards,” he says. “Even with federal legalization, this harmonization would most likely take years to develop, oftentimes requiring studies to assess the hazards associated with individual contaminants.”

Although the new study succeeds in highlighting the huge disparities in cannabis quality and consumer safety across the United States, he adds, its discussion of common, potentially dangerous microbial contaminants would benefit from an analysis of additional test results from labs outside California, where different microbes are prevalent and other testing methodologies employed.

Sang Hyuck-Park, a senior scientist at the Colorado State University Pueblo’s Institute of Cannabis Research, agrees that the industry should move toward adopting a single set of regulatory guidelines for contaminants. Such guidelines should dictate not only safety standards but also testing protocols, he says, because the latter area is similarly rife with inconsistencies, both between and within individual states. “There are so many different lab protocols, and results are not consistent,” he says.

In a more effective, federally managed system, he says, contamination above set levels could trigger an inspection or audit to ensure that producers are following Current Good Manufacturing Practice regulations as defined by the U.S. Food and Drug Administration.¹⁴ This would simultaneously protect consumer safety and reduce the likelihood of future failures.

“Short-term, [transitioning to a federally managed system] would be very impactful for manufacturers who are not ready for it,” Hyuck-Park says. “But long-term, this is what we need for public health.”

Biography

Nate Seltenrich covers science and the environment from the San Francisco Bay Area. His work on subjects including energy, ecology, and environmental health has appeared in a wide variety of regional, national, and international publications.