For the first time in history the Food and Drug Administration plans to regulate the level of nicotine in cigarettes, attempting to bring it down to “non-addictive” levels. The move, announced Friday, was praised by scientists — who also noted that there’s no consensus on what a “non-addictive” level of nicotine is.

“I guess I personally would frame it as less addictive, because I’m not sure about that, ‘non-addictive,’” said Eric Donny, director of the Center for the Evaluation of Nicotine and Cigarettes at the University of Pittsburgh, who noted that FDA commissioner Dr. Scott Gottlieb did say that he wanted to reduce the nicotine level in cigarettes until they were “minimally or non-addictive.”

Gottlieb did not address the level of nicotine that would be required to render a cigarette “non-addictive.” An agency press officer said that they didn’t have any more information to share on specific levels.

Dr. Neal Benowitz, a professor of medicine at at the University of California San Francisco, said that a 95 percent reduction would be a good start. This could be done through genetic engineering of the tobacco plant or chemical extraction after the fact — a similar process to decaffeinating coffee beans.

But even a 95 percent reduction might be more addictive for some than for others, given that different people inhale different amounts of nicotine even from the same cigarette, and process it differently in their bodies.

“Some people extract more nicotine out of a cigarette than others,” Donny said. “Some people metabolize nicotine more slowly or quickly than others. In thinking about a standard, you want to be able to account for that variability.”

Benowitz proposed the idea of reducing nicotine in cigarettes in a 1994 letter to the New England Journal of Medicine — but at the time, the FDA didn’t have the authority to regulate the level of nicotine in cigarettes. (Benowitz has worked as a consultant to pharmaceutical companies regarding tobacco cessation medication and served as an expert witness in lawsuits against tobacco companies.) That changed in 2009 with the adoption of the Tobacco Control Act, which gave the FDA the power to limit the amount of, but not eliminate, nicotine.

That prompted the question — what would be the impact on cigarette smokers of reducing the amount of tobacco in cigarettes? In the largest published study to date, Donny showed that smokers given less potent cigarettes did indeed smoke less, and showed fewer signs of addiction, than smokers using conventional cigarettes.

That study, published in 2015 in the New England Journal of Medicine, used research-grade cigarettes with varying levels of nicotine — everywhere from 0.4 to 15.8 milligrams of nicotine per gram of tobacco, with the upper limit corresponding to conventional cigarettes. Those nicotine levels were achieved through genetic engineering.

Researchers gave those cigarettes to smokers who were not intending to quit, and then observed changes in their behavior and asked them to respond to standard questionnaires to measure their level of addiction. The people who smoked the cigarettes with the lowest level of nicotine for six weeks straight did show signs of addiction, but fewer signs than individuals who smoked cigarettes with higher levels of nicotine, according to the study.

“Dependence is not magically gone in six weeks,” Donny said. “But it’s certainly reduced, and we would predict [less dependence] would enable more quitting.”

Donny’s study also showed that individuals who were given the lower-nicotine cigarettes smoked fewer cigarettes overall, which means they didn’t compensate for the low nicotine levels by smoking more.

“They’d have to smoke so may more cigarettes to compensate, and it becomes too harsh, too hard on their systems,” Benowitz said.

Both Benowitz and Donny said that it’s important to make sure alternatives to cigarettes — read: electronic cigarettes — remain available to individuals who are reducing their nicotine intake from regular cigarettes, to make for a smoother transition.

It’s going to be a transition for the tobacco industry too, Donny said, to try to figure out how to comply with whatever limits are eventually set. They have some time: The FDA on Friday announced an intention to issue an “advance notice of proposed rulemaking,” which is typically followed by an actual “notice of proposed rulemaking,” which would be followed, presumably, by a “final rule” — a process that could drag out for months.

Republished with permission from STAT. This article originally appeared on July 31, 2017