Cigarette smoke contains more than 7,000 chemicals, and among those, 69 are known carcinogens [source: American Lung Association]. But it's not only regular cigarettes that are toxic to our bodies; e-cigarettes, too, come with health and safety concerns. The problem? Liquid nicotine.
Liquid nicotine is extracted from tobacco, but unlike tobacco leaves, liquid nicotine can be lethal. It can cause harm when it's inhaled, but it can also be harmful when ingested or absorbed through your skin. Only a small dose is dangerous -- less than one tablespoon of many of the e-liquids on the market is enough to kill an adult, and as little as a teaspoon could kill a child) [source: Richtel]. The number of calls to poison control centers regarding e-cigarette nicotine-infused liquids rose sharply every month between September 2010 and February 2014, from just one call per month to as many as 215 -- that's a rise from 0.3 percent to 41.7 percent of all emergency calls. As many as 51.1 percent of those calls involved accidental poisoning of kids under the age of 5 (roughly 42 percent involved adults age 20 or older) [source: CDC].
Some testing suggests it's not only the nicotine that may be dangerous. Certain e-cigarette devices may also release metals during use -- including tin in some cases -- as well as other impurities known to be toxic and/or carcinogenic.