A potent, liquid form of nicotine poses a serious and potentially deadly threat, but is sold legally in stores across the United States and online.
The so-called "e-liquids" -- which are the key ingredients in e-cigarettes -- are extracted from tobacco and enhanced with flavorings, colorings and various chemicals, The New York Times reported.
The liquids, which come in small bottles that people keep on hand in order to refill their e-cigarettes, are not regulated by the federal government.
E-liquids are powerful neurotoxins that can cause vomiting, seizures and even death when small amounts are ingested or absorbed through the skin. A small child can be killed by only a teaspoon of even highly diluted e-liquid, according to The Times.
Experts warn that children are at special risk because they may be attracted by e-liquids' bright colors and appealing flavors such as bubble gum, chocolate and cherry.
"It's not a matter of if a child will be seriously poisoned or killed," Lee Cantrell, director of the San Diego division of the California Poison Control System and a professor of pharmacy at the University of California, San Francisco, told The Times. "It's a matter of when."
The number of accidental poisonings involving e-liquids was 1,351 in 2013, a 300 percent increase from 2012. The number of cases is on track to double this year, according to National Poison Data System figures.
"This is one of the most potent naturally occurring toxins we have," Cantrell said of nicotine. Despite the danger, e-liquids are now available almost everywhere in the U.S. "It is sold all over the place. It is ubiquitous in society."
The Food and Drug Administration has said it plans to regulate e-cigarettes, but has not provided any details, The Times reported.