Recently, California’s Office of Environmental Health Hazard Assessment (OEHHA) adopted safe harbor warning regulations for cannabis smoke and delta-9-tetrahydrocannabinol (delta-9-THC) under California Proposition 65.1

What is Proposition 65?

The Safe Drinking Water and Toxic Enforcement Act of 1986 (also known as Proposition 65) requires the governor of California to publish, at least annually, a list of chemicals known to the State to cause cancer or reproductive toxicity.2 Among other things, the law prohibits the knowing exposure of any individual to an amount of a listed chemical without first providing a “clear and reasonable warning” to such individual.3 The law requires these warnings to be provided for Proposition 65 exposures from consumer products, the workplace, and the environment unless “the person responsible can show that the exposure [to a listed carcinogen] poses no significant risk assuming lifetime exposure at the level in question,” or, for a listed reproductive toxin, that the substance “will have no observable effect assuming exposure at 1,000 times the level in question.”4 Other limited exemptions from the warning requirement also may apply under the law.

Safe Harbor Warning Regulations for Cannabis Smoke and Delta-9-THC

OEHHA initially added cannabis smoke and delta-9-THC to the Proposition 65 list for developmental toxicity in 2020, while cannabis smoke has been listed as a carcinogen since 2009. In late 2021, OEHHA initially proposed the safe harbor warning regulations for cannabis smoke and delta-9-THC. After two updated draft proposals, OEHHA adopted this final version.

The new regulations suggest specific safe harbor methods of transmission and warning language for retail products that can expose consumers to cannabis smoke or delta-9-THC via inhalation, ingestion, or dermal application, and for environmental exposures to cannabis smoke and delta-9-THC at businesses where smoking of cannabis or vaping or dabbing of delta-9-THC occurs.

As is the case with other safe harbor warnings set out in the regulations, the specific warning language is not mandatory. Thus, businesses may use another method or provide other language to satisfy the warning obligations under the law. However, those alternative warnings must satisfy the statutory “clear and reasonable” standard.

In OEHHA’s final statement of reasons for the regulations, the agency stated that “[t]he safe harbor warning content for these regulations identifies the chemical, route of exposure and provides specific information to consumers about the risks of using cannabis products including cancer and, while pregnant, the impact exposures can have on the unborn child.”5

The newly adopted rule took effect October 1, 2022, and includes both a one-year phase-in period and an unlimited sell-through provision for products manufactured and labeled with compliant warnings prior to October 1, 2023.

Be sure to register for Keller and Heckman’s Annual E-Vapor and Tobacco Law Symposium on February 15 – 16, 2023, in Irvine, California. Details and registration information can be found here.


1. See Cal. Code Regs. tit. 27, §§ 25607.38-25607.47 (2022).

2. See Cal. Health & Safety Code §§ 25249 et seq.

3. Cal. Health & Safety Code § 25249.6

4. Cal. Health & Safety Code § 25249.10(c).

5. See The Safe Drinking Water and Toxics Enforcement Act of 1986 Proposition 65, Final Statement of Reasons (June 2022),

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Originally published at Mondaq