Electronic cigarettes are trendy, but their impact may be more serious than their sweet and innocuous flavors imply.

E-cigarettes are being marketed as a tool to quit smoking and a safer alternative to regular cigarettes, but the lack of research and regulations has caused controversy.

“E-cigarettes have not been fully studied so consumers currently don’t know: The potential risks of e-cigarettes when used as intended, how much nicotine or other potentially harmful chemicals are being inhaled during use, or whether there are any benefits associated with using these products,” warns the website of the Food and Drug Administration.

E-cigarettes are devices that heat liquid nicotine into an aerosol that can be inhaled through a mouthpiece. The liquid nicotine cartridges that go inside e-cigarettes come in a variety of flavors, including strawberry, peach, chocolate, mint, coffee — which seem harmless, but liquid nicotine itself is poisonous.

“These ‘e-liquids,’ the key ingredients in e-cigarettes, are powerful neurotoxins,” reported the New York Times on March 23. “Tiny amounts, whether ingested or absorbed through the skin, can cause vomiting and seizures and even be lethal. A teaspoon of even highly diluted e-liquid can kill a small child.”

According to the Centers for Disease Control and Prevention, drinking ‘e-liquid’ sent over 200 people to hospitals in February 2014, compared to one person in September 2010. Most reports of nicotine poisoning have been of kids under the age of five, but some include teenagers.

“The most common adverse health effects in e-cigarette exposure calls were vomiting, nausea, and eye irritation,” reported the Centers for Disease Control and Prevention on April 4. “One suicide death from intravenous injection of nicotine liquid was reported to (poison centers).”

The same report published by the CDC included that “E-cigarettes accounted for an increasing proportion of combined monthly e-cigarette and cigarette exposure calls, increasing from 0.3 percent in September 2010 to 41.7 percent in February 2014.”

San Francisco is among several cities and states that have decided to regulate e-cigarette smoking the same way they restrict use of regular cigarettes. City supervisors passed an ordinance restricting e-cigarette use on March 18, with the San Francisco Chronicle reporting that the legislation was intended to limit use especially by young people.

“The (e-cigarette) legislation by Supervisor Eric Mar is intended to limit children’s use of the nicotine product, which he and other supporters contend has been marketed heavily toward young people, and to protect all members of the public from the secondhand aerosol emitted by the devices,” the Chronicle reported.