Calls to U.S. poison control centres involving electronic cigarettes rose sharply between 2010 and 2014 as the nicotine delivery devices grew in popularity, health officials say.
According to the U.S. Centers for Disease Control and Prevention, the number of calls each month involving exposure to the liquid nicotine in the devices rose from one in September 2010 to 215 in February 2014.
"This report raises another red flag about e-cigarettes — the liquid nicotine used in e-cigarettes can be hazardous," CDC Director Dr. Tom Frieden said in a statement. "Use of these products is skyrocketing, and these poisonings will continue."
First introduced in China in 2004, e-cigarettes have become a $2 billion US industry. The battery-powered devices let users inhale nicotine-infused vapours, which do not contain the harmful tar and carbon monoxide in tobacco.
Because of that, some proponents think e-cigarettes may be useful in helping individuals stop smoking. But public health officials are becoming increasingly wary of the devices, which they fear can serve as a gateway to smoking for the uninitiated, particularly teenagers.
The U.S. Food and Drug Administration is "pushing very hard" to release a proposed rule that would establish its authority over e-cigarettes, the head of the agency said on Thursday.
For the study, researchers at the CDC analyzed poison centre data on exposure to conventional cigarettes, e-cigarettes or nicotine liquid used in e-cigarettes in the 50 U.S. states, the District of Columbia and U.S. Territories.
They found 2,405 calls involving e-cigarettes and 16,248 calls involving exposure to conventional cigarettes in the 3-½ year period. Some 51 percent of the calls to poison centres due to e-cigarettes involved children 5 years old and under.
Poisoning from conventional cigarettes generally happens when young children eat them. Poisoning from e-cigarettes can occur when the liquid containing nicotine is ingested, inhaled or absorbed through the skin or eyes.
In the study, the most common side effects from e-cigarette exposure were vomiting, nausea and eye irritation.
Frieden said e-cigarette liquids were "a threat to small children" because they come in candy and fruit flavours and the packaging does not have to be child-proof.
Although the risks of e-cigarettes are still not clear, many municipalities are moving to curb their use in public places, with bans in place in New York, Los Angeles, Boston and Chicago.
In Canada, poisonings have so far been rare. The Ontario Poison Centre, for example, counted 10 cases last year.