We conducted a full lab report with a third party lab, with our Safety Data Sheets reporting that our products contain no toxicity, no irrigation, no allergenicity, no carcinogenicity, nor any hazard for its intended use. The Zero and E-Z can be used fully independent of any natural extracts, so all that occurs is that you would be breathing in the same air around you, just passing through a silicone valve to create the throat hit. Therefore, our products are safe for its intended purpose. If you are unaware of certain allergies or reactions to natural extracts and essential oils, please consult with a health professional before using any flavoring.