Guidance on California Proposition 65 and Cannabis Products

Guidance on California Proposition 65 and Cannabis Products

Revised April 2020

Published: Wednesday, April 15, 2020

This document was revised in April 2020 to address:

  • The addition of tetrahydrocannabinol (THC) and cannabis (marijuana) smoke to the list of Prop 65 chemicals as reproductive toxins on on January 3, 2020
  • Marketers have until January 3, 2021 (one year grace period) to provide warnings for their products if required
  • Marijuana smoke was already on the Prop 65 list as a carcinogen, and is now also listed as a reproductive toxin
  • A safe harbor has not been determined for THC, so any detectable amount of THC in a cannabis product may require a warning to be provided
  • These new listings do not specify routes of exposure, so warnings may be needed for products taken orally, applied topically, or inhaled


Consumer goods sold in the State of California are, with certain exceptions, subject to that State’s Proposition 65, the Safe Drinking Water and Toxic Enforcement Act of 1986. The regulations that have been implemented in the years since the Proposition was passed require that warnings be provided for products sold in the State of California if the products contain chemicals listed by the State as carcinogens or reproductive toxicants. Failure to provide such warnings can result in action by the California Attorney General, District or City Attorneys, or by “any person in the public interest.”

Proposition 65 requires persons doing business to provide “clear and reasonable” warnings prior to exposing individuals to chemicals known to the State to cause cancer and/or reproductive toxicity. The State is required to publish a list of the chemicals it considers to cause cancer and/or reproductive toxicity.

Of particular interest to the cannabis industry is marijuana smoke, which was added to the Proposition 65 list in June 2009 as a chemical known to the State of California to cause cancer. The Hazard Identification Document that outlines the basis for the classification of marijuana smoke as a carcinogen can be reviewed on the website of the California Office of Environmental Health Hazard Assessment (OEHHA). In January 2020, cannabis (marijuana) smoke and Δ9-tetrahydrocannabinol (Δ9 THC) were both added to the Proposition 65 list as chemicals known to cause reproductive toxicity. The scientific basis for these classifications is also available from OEHHA.

In addition to marijuana smoke and Δ9 THC, other chemicals on the Proposition 65 list that may be used in the cultivation and processing of cannabis, such as the pesticides myclobutanil and carbaryl, must be considered when cannabis businesses are determining compliance to this regulation.

This guidance document was prepared with a narrow focus; it is concerned only with the regulatory and liability implications for cannabis businesses or other entities in the State of California regarding exposure to marijuana smoke, Δ9 THC, and other chemicals listed under Proposition 65. This document does not address the implications of Proposition 65 for hemp products. It is not intended to address any other elements of Proposition 65 except as necessary for the present purpose, nor does it serve as a substitute for this law, its implementing regulations, or legal counsel.

AHPA has also produced the document Guidance on California Proposition 65 and Herbal Products, which addresses the impact of this regulation to the broader herbal products industry and may also be of interest to the hemp industry. Another AHPA document, Guidance on California Proposition 65 and Hemp Products, addresses the specific impact of this law on the cannabis (non-hemp) products industry. AHPA produces periodic webinars on Proposition 65 to keep members of the regulated industry up to date on the latest developments from OEHHA regarding lead and other Proposition 65 listed chemicals. For more information, visit AHPA's Prop 65 webpage.


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