Cal. HSC § 111929.2

An inhalable product shall not contain any of the following: (a) Flavorings other than natural terpenes. (b) Polyethylene glycol (PEG). (c) Vitamin E acetate. (d) Medium chain triglycerides (MCT oil). (e) Squalene or squalane. (f) Any other substance that the department finds to be a danger to public health.