Effective January 3, 2020, California's Office of Environmental Health Hazard Assessment (OEHHA) listed cannabis smoke and THC as reproductive toxins under Proposition 65 (Prop 65).

Prop 65 requires the Governor to publish a list of chemicals that are known to the State of California to cause cancer, birth defects, or other reproductive harm. It also requires businesses to warn Californians about significant amounts of listed chemicals:

(Cal. Health & Safety Code § 25249.6.)

Prop 65 warnings already appear on many cannabis-based products since cannabis smoke has been listed as a Prop 65 carcinogen since 2005. The new listing of cannabis smoke as a reproductive toxin will likely require businesses to update their warnings to cover both cancer and reproductive toxicity. Failure to do so will expose businesses to suits that challenge the adequacy of existing warnings for these products.

The new THC listing also expands the range of marijuana products that are covered by Prop 65, namely, smoke-less marijuana products such as beverages, edibles, or vape cartridges.

Under Prop 65, sellers have a one-year grace period before enforcement of the warning requirement begins. During that time, businesses can determine whether their product requires a warning to reflect the new listing. In addition, OEHHA can pursue development of "safe harbor levels" to determine the amount of exposure above which a warning is required. Absent this action by OEHHA, businesses must make a safe level determination on their own.

In this case, businesses have until January 3, 2021 to determine if warnings are required for their products. If so, they must issue an appropriate warning on a product label, website page, or shelf sign, among other options.

For more information about Prop 65, see Practice Note, California's Proposition 65: Overview. For a guide to resources on legal issues arising out of the possession, sale, cultivation, and trade of cannabis and cannabis-related products, see Practical Law's Cannabis Toolkit.