What chemical substances are added to e-cigarette cartridges that can harm human health?

The harmful chemical substances added to e-cigarette cartridges are diverse and can be classified into the following categories, each with its own specific health risks:
Addictive substances
Nicotine (Nicotine): This is the most significant bioactive component in electronic cigarettes, and it is a highly addictive substance. It can cause addiction and have negative effects on brain development, especially being harmful to fetuses and teenagers. Long-term exposure can also increase the risk of cardiovascular diseases.
2. Carcinogens and Toxic Degradation Products
Formaldehyde: Extremely carcinogenic, classified as a 1-category carcinogen. It also irritates the respiratory epithelial cells, inhibits their ciliary movement, and causes damage to the respiratory tract.
Acetaldehyde: Classified as a Group 2B carcinogen, it also irritates the respiratory tract.
Acrolein: A chemical substance mainly used in herbicides. Inhalation of it can cause irreversible damage to the lungs.
Polycyclic Aromatic Hydrocarbons (PAHs): These include 1-naphthol, 2-naphthol, and 1-hydroxyphenanthrene, among others. Some of them have been classified as carcinogens by the International Agency for Research on Cancer.
3. Flavoring agents and volatile organic compounds (VOCs)
Diacetyl: A chemical substance used to impart flavor to butter and cream. Inhalation of it is associated with a serious lung condition called "popcorn lung" (obstructive bronchiolitis).
Ethyl Maltol: A common sweetener.
Benzoic Acid: It is used to adjust the pH value of nicotine and may have an impact on the lungs.
Benzene series (Benzene, Toluene, Xylene): This includes benzene, toluene, ethylbenzene, and xylene, among others. Benzene is a known carcinogen.
Other VOCs: such as methanol, ethanol, acetone, etc., are toxic to the cells in the human respiratory tract, nose, alveoli, etc.
4. Solvents and Carriers
Propylene Glycol: A common solvent, it is considered safe in food, but inhalation can cause dryness in the mouth and throat, and may also cause damage to the kidneys and liver.
Glycerol (Vegetable Glycerin): Used to produce smoke, but when heated, it may decompose into harmful substances such as formaldehyde and acetaldehyde.
Diethylene Glycol: A toxic chemical substance used in antifreeze, associated with lung diseases.
5. Heavy Metals
The heating elements (such as coils) of electronic cigarettes may release various heavy metals. Long-term inhalation of these metals may cause respiratory diseases, neurological damage and an increased risk of cancer.
Lead: A neurotoxin that affects multiple organ systems.
Cadmium: A toxic metal that can cause respiratory problems.
Nickel (Nickel), Chromium (Chromium): These elements are often derived from the materials of the atomizing coil and are potential carcinogens.
Other metals: such as tin (Tin), arsenic (Arsenic), selenium (Selenium), mercury (Mercury), antimony (Antimony), etc., may all cause harm to the human body.
6. Other harmful additives
Vitamin E acetate (Vitamin E Acetate): This is the most dangerous additive. It was identified by the Centers for Disease Control and Prevention (CDC) in the United States as the culprit behind the outbreak of e-cigarette-related lung injury (EVALI) in 2019. When this substance is inhaled into the lungs, it interferes with normal lung function.
Phthalates: A type of plasticizer commonly used in plastics, they are classified as environmental endocrine disruptors and may affect the reproductive system.
Tobacco-specific nitrosamines (TSNAs): Examples include N'-nitrosodimethylamine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), both of which are known strong carcinogens.
These harmful substances come in various types and have different health risks. The ones listed above are just typical examples.
Overall, the chemical substances added to e-cigarette cartridges are diverse, and they include several definite carcinogens, neurotoxins, and lung-damaging substances. In particular, additives such as ethyl acetate of vitamin E have directly caused a fatal lung injury epidemic.