• Mayo Clinic Minute: Vaping chemicals, not water

Millions of people use electronic cigarettes, or vaping devices. While tobacco use remains the largest cause of preventable death and disability in the U.S., vaping concerns — and injuries — are on the rise. "Electronic cigarettes are probably safer than cigarettes, but they are not safe", says Dr. J. Taylor Hays, director of the Mayo Clinic Nicotine Dependence Center.

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Vaping is not water vapor. Dr. Hays says what people are inhaling is a complex solution of chemicals that have been changed from their original state because they've been heated to high temperatures.

"The solutions that are heated by these devices contain nicotine. They also contain a vehicle, typically vegetable glycerin or propylene glycol, and these are common vehicles for ingested substances."

 And then there are a host of added e-juices, or vaping flavors and blends.

"Although these components are considered safe for ingestion, the flavorings like cinnamon and the vehicles like vegetable glycerin are not safe for heating and inhaling because the chemical constituents have changed," says Dr. Hays.

And that's the concern.

"Many of the chemicals that can be inhaled are different aldehydes and other chemicals that are derivative from these original ones, and we think those are likely harmful," says Dr. Hays.

Is vaping safer than smoking tobacco? Dr. Hays says that vaping probably is safer, but he stresses that it is not safe.

"Never inhale anything in your lungs except air," he says.