Source: FDA, 8/31/16

FDA has revised a guidance defining the phrase “harmful and potentially harmful constituent.” The revised guidance represents FDA’s current thinking on the matter, and it better reflects the current range of tobacco products subject to the agency’s authority. For the purpose of establishing a list of tobacco product constituents that are harmful or potentially harmful to human health, as required under section 904(e) of the FD&C Act, FDA believes the phrase “harmful and potentially harmful constituent” includes any chemical or chemical compound in a tobacco product or in tobacco smoke that is, or potentially is, inhaled, ingested, or absorbed into the body, including as an aerosol (vapor) or any other emission.  

For the full definition, please read the revised guidance: