NEW YORK » Laws in New York and Chicago making electronic cigarettes subject to the same regulations as tobacco are taking effect, and their sellers and users are steadfast in their opposition.

The New York law — along with the measure in Chicago, one that previously went into effect in Los Angeles and federal regulations proposed last week — are keeping debate smoldering among public health officials, the e-cigarette industry and users.

Proponents of the regulations, which began Tuesday, say they are aimed at preventing the re-acceptance of smoking as a societal norm, particularly among teenagers who could see the tobacco-free electronic cigarettes, with their candy-like flavorings and celebrity endorsers, as a gateway to cancer-causing tobacco products.

Dr. Thomas Farley, the New York City health commissioner under former Mayor Michael Bloomberg, says allowing electronic cigarettes in bars and restaurants would undermine existing restrictions on tobacco-based products.

The law would prohibit the use of electronic cigarettes in restaurants, bars and other public places, just as regular cigarettes are not allowed.

"Imagine for a moment you’re at a bar and there are 20 people who are puffing on something that looks like a cigarette and then somebody smells something that smells like tobacco smoke," Farley says. "How’s the bartender going to know who to tap on the shoulder and say, ‘Put that out’?"

Makers of the devices say marketing them as e-cigarettes has confused lawmakers into thinking they are the same as tobacco-based cigarettes. They say the new regulations ostracize people who want an alternative to tobacco products and will be especially hard on ex-smokers who are being lumped into the same smoking areas as tobacco users.

Their defenders also say they’re a good way to quit tobacco, even though science is murky on the claim.

Peter Denholtz, the chief executive and co-founder of the Henley Vaporium in Manhattan, says electronic cigarettes "could be the greatest invention of our lifetime in terms of saving lives" by moving smokers away from traditional cigarettes.

"This law just discourages that," he says.

Chris Jehly, a 31-year-old Brooklyn resident, also defends the devices as a vehicle for quitting.

"The tougher they’re going to make it on vapers, the tougher it is people are going to find an actual vehicle for quitting or as a supplement to cigarettes," Jehly says from his perch at the counter at Henley. "There’s no need for it. This is working so much better than patches or gum or prescription drugs."

Robin Koval, chief executive of the anti-smoking Legacy Foundation, says that while ingredients in electronic cigarettes are not as harmful as those in tobacco products, they are still a concern because they contain highly addictive nicotine. The National Institutes of Health says users could expose themselves to toxic levels of nicotine while refilling the devices or even use them to smoke other substances.

Since little evidence exists on the effect of the devices on smoking — whether as an aid in quitting, a gateway for non-smokers or a bridge to keep smokers hooked longer — she says she favors a legislative approach that balances public health with the development of safer alternatives.

"The right way forward will be a way that promotes innovation that helps us do everything we possibly can to get combustible tobacco to be history," Koval says. "We want a generation of Americans where, for them, cigarettes are a thing of the past — an artifact like a roll of film or a rotary telephone."