The cannabis market is set to reach $50bn by 2026, and, within the past year, there is an estimated 55 million users. Currently, 15 states have made medicinal cannabis legal, but little attention has been paid to its implications in chemical exposure and consumer safety.
As cannabis is still listed as an illegal substance at the federal level, efforts of several federal agencies in assessing and mitigating the public health risk of cannabis contamination is limited.
Cannabis is neither federally regulated as an agricultural, food, nor pharmaceutical commodity, so the USDA does not monitor its growth and FDA does not consider it a drug, meaning it is difficult for cannabis consumers to know what they are putting into their bodies.
Contaminated cannabis
A new study urges that state and federal regulators need to take a closer look at the health and safety risks of the growing medicinal and recreational cannabis market after finding that, as of May 2022, 36 states and the District of Columbia listed a total of 679 cannabis contaminants listed as regulated in medical or recreational cannabis.
Most of these 551contaminants were pesticides – which included 174 insecticide, 160 herbicide and 123 fungicides subcategories, followed by 74 solvents, 21 microbes, 12 inorganic compounds, five mycotoxins and 16 classified as “other.”
Read more: Avoiding heavy metal contamination in cannabis crops
Lead author Max Leung, an Arizona State University assistant professor in the School of Mathematical and Natural Sciences, commented: “Cannabis regulation is unlike any agricultural commodities, food, or drugs in the US. Currently, there are no national-level guidelines based on conventional risk assessment methodologies or knowledge of patients’ susceptibility in medical use of cannabis.
“Therefore, our research team conducted the first comprehensive study to examine three main concerns: 1) the current landscape of state-level contaminant regulations, 2) identifying cannabis contaminants of concern in samples, and 3) explore any patient populations who may be susceptible to contaminants.
“There is surprisingly limited information on the contaminant level of cannabis products sold in this country. Without any federal guidelines, it’s been left entirely up to the states to craft a patchwork of cannabis regulations and policy.
“Individual legalised states and DC set their own rules with huge discrepancies.
“What was interesting is that many pesticides in this document were highly unlikely to be utilised in cannabis cultivation and processing.”
These pesticides included chlorpropham, a plant hormone that prevents potatoes from sprouting, oxytetracycline, an antibiotic, and norflurazon, an aquatic herbicide for Hydrilla control.
Leung added: “What was also alarming to us is that the US EPA tolerance document and individual jurisdictions also listed a total of 42 legacy pesticides that were no longer registered for any agricultural use in the US, such as dichlorodiphenyltrichloroethane (DDT), chlordane, lindane and parathion.”
The study found that different state jurisdictions showed significant variations in regulated contaminants and action levels ranging up to four orders of magnitude.
Testing record data of cannabis flower and extract samples produced in California were also mined, the largest state cannabis market in the US, a sample which represented about 6 per cent of California’s legal production in 2020 to 2021.
“As mandated by California’s Medicinal and Adult-Use Cannabis Regulation and Safety Act, all cannabis and cannabis products in the legal market of California are required to be tested for 68 pesticides, four inorganics, 20 solvents, six microbes, and five mycotoxins,” said Leung.
“The cannabis manufacturers must submit their products – including cannabis flowers and cannabis products such as edibles, concentrates, and other consumables – to a state-licensed cannabis testing laboratory. All products must be certified for compliance testing before they can be sold legally.
“The products that failed the state’s regulatory levels in the compliance testing are subject to recalls.”
The research showed that insecticides and fungicides were the most prevalent categories of detected contaminants, with boscalid and chlorpyrifos being the most common. The contaminant concentrations fell below the regulatory action levels in many legalised jurisdictions, indicating a higher risk of contaminant exposure.
Medical cannabis
Medical cannabis use reports released by state-level public health agencies from 2016 to 2021 were also reviewed.
Leung said: “Cannabis and cannabis products are often marketed as alternative options to standard medical treatments. As such, medical cannabis can potentially expose susceptible patients to harmful contaminants.
“Immunocompromised patients with cancer and HIV, women of reproductive age, and patients with seizures and epilepsy are among those who are more susceptible to the health hazards of pesticide and microbial contaminants that may be found in cannabis.”
The majority of patients were prescribed medical cannabis for use in alleviating pain (799,808 patients), followed by post-traumatic stress disorder (164,383 patients), spasticity associated with multiple sclerosis or spinal cord injury (78,145 patients), cancer (44,318 patients), and epilepsy (21,195 patients).
“Our findings have two important public health implications.
“First, the scattershot approach of regulations at the state level can confuse cannabis manufacturers and discourage compliance while subjecting cannabis users to a higher level of contaminant exposure in some jurisdictions.
“Second, given the current status of cannabis contaminant regulation in the US, it is unclear whether the health benefit of cannabis usage outweighs the health risk of exposure to cannabis-borne contaminants.”
To help better inform the public and policymakers, Leung recommends further investigations to examine the safety considerations in susceptible patient populations across all medical conditions.
Leung said: “The progression and prognosis of many qualifying conditions may be worsened by exposure to detected contaminants in cannabis. This study demonstrates an urgent need for a unified regulatory approach to mitigate the public health risk of cannabis contamination at a national level.”
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