State Regulators Face Challenges in Keeping Harmful Substances Out of Legal Marijuana

State regulators around the country are facing challenges in keeping harmful substances such as pesticides, molds and heavy metals out of the supply of legal marijuana, NPR reports.

Among states that have legalized marijuana, there are differences in how they regulate it. A study conducted in 2022 found there were more than 600 contaminants that were regulated across some 30 states that had legalized marijuana at that time, according to researcher Maxwell Leung of Arizona State University. “But interestingly, in each jurisdiction there’s only anywhere between 60 to 120 contaminants that are regulated,” he said. So while one state may stop selling marijuana because of a particular pesticide, another state may not even be looking for that contaminant.

Because marijuana is still illegal under federal law, even properly regulated products cannot be shipped legally between states. This means there is a large opening for underground producers and distributors, who often grow and process marijuana in unsanitary conditions with banned pesticides and unhealthy working conditions.

Experts tell NPR that legal marijuana is still probably more likely to be free of many contaminants such as mold and pesticides because states are testing them and pulling unsafe products off the shelves.