Electronic cigarettes are handheld nicotine-delivery devices that, despite a devoted following, are currently swirling in controversy.
New York is pushing to become the first state to ban the devices, which so far remain unregulated and mostly unstudied. With cutesy colors, fruity flavors, clever designs and other options, e-cigarettes may hold too much appeal for young people, critics warn, offering an easy gateway to nicotine addiction.
But those criticisms clash with equally strong arguments for the value of e-cigarettes. The devices, which are tobacco-free, may be a safer alternative to cigarettes, say advocates, who point to testimonials from thousands of smokers who say they have used e-cigarettes to help them quit.
As the U.S. Food and Drug Administration struggles to gain regulatory control, and as safety studies remain works in progress, the debate continues.
"There really are a lot of unknowns with respect to health," said Prue Talbot, a toxicologist at the University California, Riverside. "I don't know of any studies in the literature which are peer-reviewed. Almost all of the studies have been paid for by the e-cigarette companies.
"E-cigarettes are often sold as safe, which is probably not true," Talbot added. "They may not be as dangerous as real cigarettes, but on the other hand, they could be. We just don't know."
Electronic cigarettes typically use a rechargeable battery-operated heating element to vaporize the nicotine in a replaceable cartridge. Nicotine is usually dissolved in propylene glycol, a clear and colorless liquid that is commonly found in inhalers, cough medicines and other products.
Some e-cigarettes are made to look like real cigarettes, cigars or pipes. Others look like pens or USB memory devices. There is no tobacco involved, and no smoke either. Instead, users do what's called "vaping." As they inhale, they take in nicotine-filled vapor.
By isolating nicotine, e-cigarettes should carry far fewer chemical risks than regular cigarettes, said Michael Siegel, a tobacco researcher at Boston University. Tobacco contains about 5,000 known chemicals, he said, with as many as 100,000 more that haven't yet been identified. E-cigarettes eliminate many of those ingredients.
Siegel and a colleague reviewed 16 studies that analyzed the contents of electronic cigarettes. In a paper just published in the Journal of Public Health Policy, they reported that levels of certain harmful chemicals were on par with levels found in nicotine patches and hundreds of times lower than what's found in cigarettes.
The researchers also found evidence that vaping reduces cravings among smokers, not just for nicotine but also for the need to hold something in their hands and put something in their mouths -- making the devices more appealing to them than patches or gum.
As a cigarette-quitting strategy, Siegel compared e-cigarettes to heroin needle exchange programs. It's not that the devices are good for anyone, he said. They are just better than what they're meant to replace.
"The relevant question is not, 'Are these things safe?'" he said. "But are these things much safer than real cigarettes, and do they help people quit smoking? The answer to both of those questions we know is yes."
"What New York is doing is equivalent to outlawing lifeboats on a sinking ship because they haven't been FDA approved," he added. "It's a really crazy approach to public health."
For other experts, the list of unknowns is still too large for them to consider e-cigarettes worth recommending. Some users, Talbot said, have reported problems with their lungs and throats that have forced them to stop using the devices.
And even though industry-funded studies have deemed the devices to be safe, an FDA report found levels of carcinogens and toxic contaminants that they determined to be were worthy of concern. Without regulation, Talobt added, cartridges may contain undisclosed chemicals that could end up being more toxic than tobacco smoke.
Quality control is also lacking. In a recent study, Talbot evaluated six brands of e-cigarettes acquired over the Internet. None of the devices were labeled clearly with nicotine levels, expiration dates or other information, she reported in December in the journal Tobacco Control.
Most cartridges leaked onto her hands, the study found, and all were defective in some way. Talbot also found unsubstantiated health claims on many of the company websites and print materials. One says they put vitamins in their e-cigarettes.
Other experts worry about the appeal of e-cigarettes to children. The devices are easy to buy online or in mall kiosks. They come in flavors ranging from chocolate to bubble gum. You can buy them in pink, gold or blue.
"Once a youth has decided to try an e-cigarette, there is nothing that protects him from getting addicted to nicotine by puffing this product," wrote Jonathan Winickoff, a pediatrician at the MassGeneral Hospital for Children, in a letter to the FDA. "Nicotine itself is not safe for children. Nicotine addiction is one of the hardest addictions to break."
New York's move is a reaction to what can't yet happen on the national level. According to a series of recent court decisions, e-cigarettes cannot qualify as drug delivery products, said Jeff Ventura, a spokesman for the FDA. As a result, the agency cannot ban them or require more arduous testing.
But even though they are now considered tobacco products, they are not mentioned in the Tobacco Control Act, either. For now, then, they remain unapproved and unregulated.
And anyone is free to buy them.