The headline may sound like a Frank Zappa tune, but in reality, California in fact is considering listing both acetaminophen (the active ingredient in Tylenol) and cannabis smoke, along with delta-9-tetrahydrocannabinol (otherwise known as “THC”), under Proposition 65.

Marijuana smoke has been listed as a Prop 65 carcinogen since 2009. The California Office of Environmental Health Hazard Assessment (OEHHA), which oversees the Prop 65 program, is now considering also listing cannabis smoke and THC as reproductive toxins under the law. The Developmental and Reproductive Toxicant Identification Committee (DARTIC) of OEHHA’s Science Advisory Board will meet on December 11 to consider the listings. Further details on the meeting can be found here. While Prop 65 warnings already appear on many marijuana-based products, the new listing of cannabis smoke as a reproductive toxin is likely to require businesses to amend their warnings. This opens the door for plaintiff groups to challenge the adequacy of current warnings that are not updated to reflect the new listing. Moreover, a first-time listing of THC may require new Prop 65 warnings for many cannabis products that do not expose users to smoke, such as edibles or vape cartridges. Plaintiff groups have been extremely active on the marijuana front in the last year or so, filing hundreds of Prop 65 notices of violations against businesses for failure to provide a required warning.

If approved by DARTIC, the listing would be formally adopted by OEHHA in coming weeks after which a one year grace period would kick in. During that year, businesses would have an opportunity to determine whether their product requires a warning to reflect the new listing. In addition, OEHHA could pursue development of “safe harbor levels” that would designate the amount of exposure above which a warning is required (absent such action by OEHHA, businesses would be left to make that “safe level” determination on their own).

On the acetaminophen front, OEHHA’s Carcinogen Identification Committee (CIC) will consider the proposed listing at a meeting that recently was postponed from December 5 and will be rescheduled after the close of the comment period on January 27, 2020. OEHHA issued a hazard identification document on September 20 that cites studies the agency claims as associating acetaminophen with a variety of cancers. The pharmaceutical industry vigorously opposes the listing, noting (as OEHHA acknowledges) that the authoritative bodies most often relied upon by OEHHA for cancer classification information (including U.S. EPA and FDA, the National Toxicology Program, and the International Agency for Research on Cancer) have not classified acetaminophen as a potential carcinogen. Acetaminophen, millions of pounds of which are consumed each year, has been approved by FDA since the 1960s to treat fever and pain, apparently without adverse health impacts on the population.

An acetaminophen listing, if adopted, seemingly would set up yet another conflict between the Prop 65 program and federal regulators -- following on the heels of FDA’s criticism of Prop 65 warnings related to acrylamide in cereal and EPA’s opposition to the listing of glyphosate -- not to mention common sense, as evidenced by the whole acrylamide in coffee fiasco.

Tylenol and Pot Smoke: California Prop 65 Targets New Listings