THC and California Proposition 65: What’s in Store for CBD Product Labeling?

December 10, 2019

On Dec. 11, 2019, the Developmental and Reproductive Toxicant Identification Committee of the California Office of Environmental Health Hazard Assessment will meet to discuss whether delta-9-tetrahydrocannabinol (THC) should be considered a development and reproductive toxicant that may cause teratogenicity or birth defects.

If affirmed, THC will be added to the published list of more than 900 chemicals under the California Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition 65) that are known to cause cancer, birth defects and other reproductive harms. A company doing business in California with products that contain THC would then be required to warn consumers, with a clear and reasonable statement, that exposure to THC is known to the state of California to cause birth defects or other reproductive harm.

What Is California Proposition 65?

Proposition 65 is a California regulation designed to reduce or eliminate exposure to substances known to cause cancer and birth defects by requiring notice of the same to the consumer. Under Proposition 65, consumer products that contain such substances must include a “clear and reasonable” warning of the risks and hazard prior to being sold or marketed to California consumers. The warnings can be a simple and direct statement, such as “this product contains a chemical known to the state of California to cause cancer, birth defects and other reproductive harm.”

Although Proposition 65 currently contains more than 900 chemicals on the published list, approximately 300 of them have safe-harbor-level status. If a product contains a chemical exempted by a safe-harbor level, then the product must include a warning only if the chemical in the product exceeds the safe-harbor level. A safe harbor is a determination that exposure to the chemical on the Proposition 65 list is not a risk if its presence in the product is at or below the threshold amount.

Proposition 65 warnings can have significant effects on the marketplace, including scaring off consumers and increasing liability for the manufacturers, producers, packagers, importers, suppliers or distributors of a product. Importantly, Proposition 65 contains a private right of action under which consumers can bring a cause of action against companies that violate Proposition 65, which gives the consumer the opportunity to collect damages for any such violations.

How Does This Apply to CBD?

The Developmental and Reproductive Toxicant Identification Committee (DARTIC) Dec. 11 meeting on THC could affect products marketed as possessing THC, such as cannabidiol (CBD) products. In the meeting, California Office of Environmental Health Hazard Assessment (OEHHA) will present on the risks and science being considered in the decision-making process and will solicit comments from the public. While the state of California has not provided any science that suggests a strong link with CBD causing cancer, CBD continues to be subject to scrutiny under Proposition 65 because of its potential to cause reproductive harm as evidenced through various scientific studies. The evidence DARTIC published on the issue specifically references human and animal peer-reviewed studies linking potential birth defects to CBD. See “Evidence on the Developmental Toxicity of Cannabis (Marijuana) Smoke and Δ9-THC,” California Office of Environmental Health Hazard Assessment, (Nov. 27, 2019).

CBD products have become increasingly popular among a wide demographic of consumers because it is non-intoxicating and offers potential health benefits. Because the legality of CBD products depends on the product containing less than 0.3 percent of THC, the intoxicating effect of CBD on users is presumed minimal. Therefore, many consumers believe they are not ingesting THC, which is not always the case. Science suggests it is possible for CBD products to contain trace amounts of THC.

Consequently, if DARTIC concludes that THC should be included on the Proposition 65 published list, then the effect on manufacturers, producers, packagers, importers, suppliers or distributors of CBD products could be significant. Specifically, because DARTIC could also decide to promulgate a safe-harbor level for CBD that no product could meet due to the minimal amounts of THC present in the product, every product that contains CBD would need to include a Proposition 65 warning.


Manufacturers of CBD products should pay close attention to the Dec. 11 meeting of DARTIC. Failure to provide the required warning on products that contain threshold amounts of chemicals listed on the Proposition 65 list could lead to potential litigation from plaintiffs attempting to enforce the law. This litigation can be costly to defend and often results in monetary settlements between the plaintiff and defendant. In the future, it may be necessary for manufacturers to warn of the risks of CBD products if those products will be sold in California.

DARTIC’s consideration of THC will begin Dec. 11.