The e-cigarette, also known as a JUUL or vape pen, uses a battery to heat a liquid into an aerosol that users inhale. This liquid, called e-liquid or e-juice, often contains nicotine (which is extracted from tobacco), propylene glycol and flavorings. It may also contain trace amounts of other chemicals that can cause harm when the e-juice is heated. These include cancer-causing chemicals, such as acetaldehyde and formaldehyde; chemical additives that can cause lung disease, such as diacetyl and acrolein; vitamin E acetate, linked to e-cigarette vaping-associated lung injury (EVALI); heavy metals like nickel, tin and lead; and tiny particles that can get deep into the lungs. E-cigarettes are not safe for anyone, but they can be especially harmful for youth and young adults because of the nicotine in them. Nicotine affects the brain’s reward system and circuits that control attention and learning, which can lead to addiction. E-cigarettes also can increase the risk of adolescent smoking and other drug use.

E-cigarettes come in a variety of shapes and sizes, including ones that look like regular cigarettes, cigars, pipes and USB flash drives. They can be refillable and can use either disposable or rechargeable batteries. Some e-cigarettes are made to hold pre-filled pods, which can have different levels of nicotine. Others are disposable and do not use pre-filled pods. Most e-cigarettes are small and easily hidden, making them popular among youth and young adults.

A few studies have examined whether e-liquids and/or vapors contain toxicants that can harm human health. Most have looked at the e-liquids themselves and their components, but others have also studied the material of the electronic device. For example, one study found that a battery can produce toxic metal oxides when it is overheated. Another study found that e-liquids can contain volatile organic compounds (VOCs) that can be inhaled into the lungs.

Some research has also found that e-cigarettes can damage the immune system. For example, a recent study found that e-cigarette use increased the number of inflammatory cells in the lungs of nonsmoking adults. It is not clear if this was due to the e-cigarettes or because of other factors, such as decreased physical activity. 電子煙