As cannabis use rises across the United States, consumers are being urged to consider where their products come from. While scientific studies indicate that marijuana is less harmful than alcohol, experts warn that safety hinges on sourcing. With federal prohibition leaving regulation to individual states, the disparity in oversight has created risks for consumers and challenges for legitimate businesses.
"We're talking about a market that lacks transparency and accountability," said Paul Armentano, deputy director of the National Organization for the Reform of Marijuana Laws (NORML). "Whether I was getting cannabis, alcohol, or my broccoli from an entirely unregulated market, I'd be concerned about any number of issues."
Maxwell Leung, an assistant professor at Arizona State University, is part of a group of researchers who studied state-level contaminant regulations and compiled complete list of regulated contaminants, namely, pesticides, inorganics, solvents, microbe, and mycotoxins.
In total, 36 states and the District of Columbia listed 679 cannabis contaminants. "But in each jurisdiction there are only between 60 to 120 contaminants that are regulated," Leung said.
The reseachers data mined compliance records for 5,654 cured flower and 3,760 extract samples — roughly 6% of California’s legal cannabis production in 2020–2021. The failure rate of the samples was 2.3% for flowers and 9.2% for extracts. The most commonly detected contaminants were insecticides like chlorpyrifos and fungicides like boscalid.
The black market further compounds the risk. A recent NPR investigation found that illegal cannabis production often involves unsafe conditions, unregulated pesticides, and misleading potency labels.
Large industrialized Cannabis farms also contribute to heightened risk by flooding the market with cheaper products grown in contaminated soil exposed to pesticide and fungicide drift.
For consumers, purchasing from a trusted dispensary is one way to mitigate risk. Mary Aiger, owner of Sol de Mendocino, emphasizes the importance of knowing your suppliers. "One of the things we do at our shop is we try to very carefully vet which producers and suppliers we use so we have an assurance we are providing clean, quality products to our customers," she said. "Consumers need to demand that regulators do a better job ensuring the safety and purity of products in the market."
In addition to dubious black market suppliers and industrialized farms, the evolving cannabis industry has introduced increasingly complex products. Pre-rolled joints now often contain additional cannabis derivatives, such as THC distillate or diamonds, which can amplify potency.
"What was once a simple process of buying bud and rolling it into a joint has turned into a much more manufactured and enhanced product," Aiger noted. "The basic rule is , know your farmer, know your source. That's true whether you're consuming, produce, food, wine, or cannabis."