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Will Possible Listing of THC and Cannabis Stigmatize California’s New Cannabis Industry?

California’s cannabis industry has seen tremendous growth in the past few years, but its continued prosperity will hinge in some part on the possible listing of THC and cannabis on the Proposition 65 chemical list. Cannabis products may become subject to these regulations, and those in the cannabis industry should understand the legal and regulatory issues for compliance.

In 2009, California added “marijuana smoke” as a listed chemical known to the State to cause cancer.  The report of the Office of Environmental Health Hazard Assessment (OEHHA) determined that there is some evidence from studies in humans that marijuana smoke is linked to an increased risk of cancer. In addition, the chemical composition and toxicological profile of marijuana and tobacco smoke had many similarities, thereby purporting to provide evidence of carcinogenicity.

In the past four years, private enforcers have issued over 800 Proposition 65 notices to cannabis-related businesses for violations of the Proposition 65 warning requirement. Since the addition of marijuana smoke, cannabis products have become increasingly subject to enforcement actions. But marijuana smoke is not the listed chemical target. Other chemicals on the Proposition 65 list, such as beta-Myrcene and pesticides like carbaryl and myclobutanil found in both edible and smokable cannabis products may be the subject of future enforcement actions. In that regard, it is critical to understand that compliance with the California cannabis testing requirements does not necessarily mean compliance with Proposition 65.

Recently, OEHHA announced that is has selected cannabis, cannabis extracts, and THC for review for listing under Proposition 65 as chemicals that may cause reproductive toxicity. A determination by the Developmental and Reproductive Toxicant Identification Committee that these chemicals cause reproductive toxicity would place obligations on companies that grow, distribute and sell marijuana products to provide “clear and reasonable” warnings about exposure to these chemicals. OEHHA’s intent to review these chemicals for potential listing will be – or at least should be – met with opposition given the use of marijuana products to relieve certain health conditions.

OEHHA requested information from the public related to whether these chemicals cause reproductive harm. OEHHA is in the process of developing hazard identification materials for these chemicals. A public meeting will be held in fall of 2019, to consider listing cannabis and other related chemicals.

Grimaldi Law Offices has been advising clients for over 20 years on chemical and product law. For knowledgeable advice and in-depth analysis of your chemical regulatory compliance obligations, contact Grimaldi Law Offices at (415) 463-5186 or email us at [email protected].


Ms. Grimaldi maintains a diverse environmental law practice focusing on chemical and product regulation and litigation defense. Her practice areas include Proposition 65, California's Safer Consumer Products Regulations, California's Rigid Plastic Packaging Container Act and the federal Toxic Substances Control Act. Ms. Grimaldi graduated from the University of California Hastings College of the Law magna cum laude and holds a Bachelor of Science Degree in Bacteriology from University of California, Davis. Prior to attending law school, she worked as a research assistant in laboratories at the University of California, San Francisco Cancer Research Institute and at the University of California, San Francisco School of Medicine.