Does Prop 65 Really Require a Warning for Hemp Products?

Prop 65 now includes THC. Does that include naturally occurring THC in hemp PRODUCTs?

This article addresses the issue of whether hemp products containing naturally occurring tetrahydrocannabinol (THC) are subject to the warning obligation provisions of California’s “Safe Drinking Water and Toxic Enforcement Act of 1986[1], a consumer protection statute that is more commonly known as “Proposition 65” or simply “Prop 65”. Specifically, must consumer products made from hemp extract which contain naturally occurring THC bear a Prop 65 warning? For the reasons I discuss below, the answer is “no”.

Disclaimer: It is important to note that this article should NOT be construed as legal advice. The specific issues addressed in this article are novel and, as of the date of publication, no court of law has ruled on them. I am not licensed to practice law in California. You should consult with an attorney regarding the issues addressed in this article and how they may impact you. 


As I discuss in an article you can read by clicking here, you should be aware of Prop 65 if you sell hemp products to consumers in California. In that article I stated: 

If you manufacture products that will be sold to Californians or market products to Californians containing THC, CBD, β-myrcene, and/or that produce cannabis or hemp smoke, then Prop 65 applies to you. In fact, for the reasons I [discussed] in [the] article, Prop 65 also affects all hemp and cannabidiol (CBD) products in California.

That opinion is currently the general consensus of most legal commentators on Prop 65 and THC. Since writing that article, my view has evolved. I now contend that consumer products made from hemp extract which contain naturally occurring THC are not required to bear a Prop 65 warning. (For more information on Prop 65, I encourage you to read my article referenced above, which goes into detail about what Prop 65 is and what it covers.)

Summary of the Argument

Products made from hemp extract with naturally occurring THC are not subject to the warning obligation provisions of Prop 65. This is because THC is a naturally occurring constituent of hemp. It is a product of the natural process of the hemp plant’s growth, and is not a chemical contaminant. For these reasons, products manufactured with hemp extract containing naturally occurring THC do not cause any “exposure” within the meaning of Prop 65 when consumed or used by a consumer and therefore do not require a Prop 65 warning.

I. Prop 65 Does Not Require a Consumer Warning for Products Containing Listed Chemicals That Are Naturally Occurring

a. Prop 65 General Requirements. Prop 65 requires businesses to provide warnings to Californians about significant exposures to chemicals that cause cancer, birth defects, or other reproductive harm. Since its enactment over 30 years ago, Prop 65’s list of carcinogens (the “Prop 65 List”) has grown to include over 900 chemicals, including THC. Prop 65 does not prohibit the sale of products containing chemicals that are included on the Prop 65 List. Rather, companies are obligated to provide “clear and reasonable” warnings to California consumers about exposure to the chemicals contained in the products that appear on the Prop 65 list.

b. THC and Prop 65. THC was added to the Prop 65 List in December 2019 by an 8 to 1 vote of the California Developmental and Reproductive Toxicant Identification Committee (DRTIC). Notably, all of the THC studies that the DRTIC evaluated were of THC contained in cannabis smoke. None of the studies analyzed THC as an isolated compound and/or as consumed in methods other than via inhalation of cannabis smoke. Regardless, it is clear that the chemical THC is currently included in the Prop 65 List and is subject to the warning requirements unless there is an applicable exception.

c. Exception for Naturally Occurring Chemicals. An “exposure” to a chemical on the Prop 65 List does not occur to the extent that the chemical at issue is naturally occurring in food.[2] [3] A chemical is “naturally occurring” if it is a natural constituent of a food, or if it is present in a food solely as a result of absorption or accumulation of the chemical which is naturally present in the environment in which the food is grown.[4] Additionally, once a chemical is exempt as a naturally occurring chemical in food, its exempt status will “carry over” to any other food or non-food consumer product to which it is added.[5]

II. THC is a Naturally Occurring Constituent of Hemp Extract

a. THC is a Naturally Occurring Constituent of Cannabis. Cannabis contains THC. In fact, the expression of THC and other similar chemicals known as cannabinoids is one of the cannabis plant’s most notable attributes. In 1964, THC was discovered to be the main active compound in cannabis.[6] While the concentrations of THC in cannabis plants vary from levels that are almost imperceptible to levels that exceed twenty-five percent, THC is present in all known varieties of cannabis. Although THC concentrations in cannabis vary from strain to strain and plant to plant, its presence is naturally occurring in the plant itself and is not attributable to absorption from the surrounding environment or human activity.[7]

b. Hemp is a Form of Cannabis. Under US law, cannabis is divided into two categories: hemp[8] and marijuana[9]. The sole distinction between hemp and marijuana is their respective concentrations of THC. Hemp is a lawful form of cannabis with THC concentrations that do not exceed 0.3% on a dry weight basis.[10] Since hemp is a form of cannabis it produces THC, albeit in very low concentrations. For this reason, most hemp extracts contain naturally occurring THC. In order to avoid confusion, it is important to note that California and a handful of other states use the term “cannabis” to refer to what federal law and most state laws call “marijuana”. In this article I am using the term “cannabis” in the botanical sense that encompasses both hemp and marijuana, not as a synonym for marijuana.

III. Prop 65 Does Not Require a Consumer Warning for Hemp Products Because They Contain Naturally Occurring THC

Absent an exemption, Prop 65 obligates companies to issue a warning when their products are sold in California and contain chemicals on the Prop 65 List.[11] Some hemp products contain lawful THC, a chemical that is included on the Prop 65 List. These hemp products are exempt from the Prop 65 warning requirement when they are manufactured using hemp extract because the THC in hemp extract is a naturally occurring constituent of hemp and its presence is not the result of human activity.[12] Additionally, THC in hemp extract is not a chemical contaminant as defined in Prop 65. Its exempt status extends to non-food consumer products, such as topicals, to which it is added.[13]

For the same reasons set forth in a 2002 letter from the OEHHA regarding naturally occurring methyleugenol (see FN5, below), THC found in hemp extract “does not cause an ‘exposure’ for purposes of [Prop 65].” Since there is no exposure arising from using naturally occurring THC in hemp extract, the warning obligation of Prop 65 does not apply to naturally occurring THC.


As discussed above, consumer products made from hemp which contain naturally occurring THC do not require a Prop 65 warning.

Special thanks to the founder and general counsel of a client who chose to remain anonymous for their invaluable insights and contributions. You know who you are. 

[1] 27 Cal. Code Regs. § 25249.5 et seq.

[2] With respect to non-food products, 27 CCR § 25501(b) provides that “an exposure to a listed chemical in a consumer product, other than food, does not “expose” an individual within the meaning of [Prop 65] to the extent that the person can show that the chemical was a naturally occurring chemical in food, and the food was used in the manufacture, production, or processing of the consumer product.

[3] See People ex rel. Brown v. Tri-Union Seafoods, LLC (2009) 171 Cal.App.4th 1549, 1554, 90 Cal.Rptr.3d 644, “[T]he duty to warn before exposing any person to a listed chemical also escapes activation to the extent a listed chemical is naturally occurring in the food.”

[4] 27 CCR § 25501(a)(1).

[5] See, eg, letter below from the California Office of Environmental Health Hazard Assessment (OEHHA) dated January 8, 2002, finding that naturally occurring methyleugenol, a chemical on the Prop 65 List, in food and consumer products does not cause “exposure” for purposes of Prop 65 and that no warnings are thus required for products containing it. See also, People ex rel. Brown (FN3, above), in which the California Court of Appeals upheld a trial court ruling that no warning was required by tuna distributors for methylmercury, a chemical on the Prop 65 List, because it is naturally occurring in tuna. (“[V]irtually all methylmercury is “naturally occurring,” and under the governing regulations does not count toward the threshold exposure[.]”)

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[6] Thomas, Brian & ElSohly, Mahmoud. (2016). “The Botany of Cannabis sativa L..” 10.1016/B978-0-12-804646-3.00001-1: 5-6. See also, Zerrin Atakan, “Cannabis, a complex plant: different compounds and different effects on individuals”, Ther Adv Psychopharmacol. 2012 Dec; 2(6): 241–254.

[7] 27 CCR § 25501(a)(3).

[8] 7 U.S. Code § 1639o(1).

[9] 21 U.S. Code § 802(16).

[10] 7 U.S. Code § 1639o(1).

[11] 27 CCR § 25249.6.

[12] 27 CCR § 25501(a).

[13] 27 CCR § 25501(b).

February 4, 2021

Rod Kight, Cannabis industry attorney

Rod Kight is an international hemp lawyer. He represents businesses throughout the hemp industry. Additionally, Rod speaks at hemp and cannabis conferences, drafts and presents legislation to foreign governments, is regularly quoted on hemp and cannabis matters in the media, and is the editor of the Kight on Cannabis legal blog, which discusses legal issues affecting the hemp and cannabis industry. You can contact him by clicking here


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