CANTON, Mass. — It’s been a rite of passage for decades: At the age of 18, students still in high school are suddenly able to vote in elections, serve in the military and buy cigarettes.

But as the tobacco industry renews its push to reach young would-be smokers with innovative products -– like electronic cigarettes and flavored “cigarillos” -– several South Shore communities are joining a growing movement to keep tobacco products out of high schools by pushing the legal purchasing age back to 19 or even 21. Canton and Sharon made the move to 21 last year, and Braintree and Scituate officials are now considering similar regulations, news partner The Patriot Ledger reports.

“We’re trying to keep tobacco out of younger kids’ hands,” said John Ciccotelli, director of public health in Canton, which banned tobacco sales to people under 21 at the start of the year. “The main avenue for them getting tobacco is that three to four-year-older group that is still young enough to be hanging around with these younger kids and may be sharing their cigarettes with them.”

The move to age 21 for tobacco sales, which was unheard of a decade ago, is now seen as inevitable by many health officials and even by tobacco shop owners. Six Massachusetts towns now ban tobacco sales to anyone younger than 21 and New York City is set to become the first major city in the U.S. to make the move in May, though the new law still faces legal challenges.

The push to raise the tobacco-purchasing age has accelerated rapidly in the last year, coming as many communities scramble to update their regulations to address a flood of new “nicotine-delivery devices” such as electronic cigarettes. Just two years ago, the town of Needham was the only municipality in the country that required consumers to be 21 to purchase tobacco, according to D.J. Wilson, tobacco control director for the Massachusetts Municipal Association.

“This is all very new,” he said.

Dr. Lester Hartman, a Needham physician who has spent the last year convincing health boards across eastern Massachusetts to increase the tobacco-purchasing age, said new research into addiction has made the move an easy sell. He and another physician, Jonathan Winickoff, point to recent neuroscientific evidence showing that adolescent brains are more susceptible to the addictive qualities of nicotine, making teenagers likely to become addicted to the drug more quickly while smoking less often than adults.

The research is also borne out by studies of today’s smoking population. A 2012 report from the U.S. surgeon general found that 88 percent of adults who smoke daily had started by the time they were 18, while 99 percent started by the time they were 26.

“Studies have shown definitively that the earlier a smoker starts, the harder it is for them to quit,” said Wilson, the tobacco control director. “If we can at least delay the age of initiation … it’ll be easier for them to quit, and they won’t be a smoker for as long.”

Creating minor barriers for teenagers seeking cigarettes has shown to dramatically lower youth smoking rates, Hartman said. In Needham, the smoking rate among high school students dropped from 12.9 percent before new tobacco regulations were adopted in 2005 to 6.7 percent in 2010.

Hartman, who lives in Needham, said the drop came despite the fact that students could have gone into nearby towns to buy cigarettes. After seeing the effects of the new regulations in his own town, he joined forces with Winickoff in late 2012 and began going from town to town trying to persuade health boards to make similar changes.

“The key with all this is it’s only a small group, it’s only one town, but it makes a huge difference in that town,” he said. “We know if we go town by town, we’ll get to 351.”

The trend has already raised concerns in the retail industry, which sees the age limits as an unwarranted obstacle to consumer choice and convenience as well as a hardship for retailers. Stephen Ryan, executive director of the New England Convenience Store Association, said shop owners worry that they will soon be faced with a patchwork of age restrictions that may put them at a disadvantage based on which town they’re in.

“You’re putting them in a position where you’re going to be losing customers to a store that is a block away or maybe a hundred yards away but happens to be on the other side of the town line,” he said.

But some in the tobacco business say the changes won’t make much of a difference. Geoff Yalenezian, a member of the family that owns six Brennan’s Smoke Shop locations in Southeastern Massachusetts, said teenagers are a tiny fraction of his stores’ clientele and tend to be the ones who give his staff the most trouble about showing identification to verify their age.

Brennan’s shops are all in towns that allow sales to 18-year-olds, but Yalenezian said he has no doubt that will change soon.

“It is what it is,” he said. “Tell me what the rules are; tell me what the laws are, and I’ll abide by them.”