If it is true, as research has suggested, that people who live within 10 miles of a casino are twice as likely as others to become addicted to gambling, what happens if casino gambling is as close as a laptop computer - or a smartphone?

New Jersey is about to find out.

Thirteen online gambling sites sponsored by six Atlantic City casinos received a green light to open to the public and start advertising to gamblers at 12:01 a.m. Tuesday, the New Jersey Division of Gaming Enforcement said Monday.

Opponents of government-sponsored gambling decried New Jersey's new era.

"There's absolutely no denying the fact that offering Internet gambling to citizens is the equivalent of opening a Las Vegas casino in every home, office, dorm room, smartphone in the state of New Jersey," said Les Bernal, national director of Stop Predatory Gaming, a nonprofit based in Washington and Lawrence, Mass.

Bernal and others worry that young adults who spend a significant amount of time on social media and may already play games on Facebook or other sites will be particularly susceptible to being sucked into a vortex of online gambling.

"In the past few years, that's been something we've been watching, the convergence between the social media, the social games, and the real-money games. For some people it may be a gateway," said Donald Weinbaum, executive director of the Council on Compulsive Gambling of New Jersey.

"The technology itself is going to be attractive to younger people," said Weinbaum, who estimated that New Jersey has at least 350,000 people with a gambling problem.

Some companies are active in both areas - social-media gaming and real-money gambling.

International Game Technology, for example, is supplying online games, such as DaVinci Diamonds and Wolf Run, to several Atlantic City operators. The Las Vegas firm also has DoubleDown Casino Slots and Poker, the third highest-grossing social game on Facebook.

New Jersey's Internet gambling regulations require a firewall between Internet gambling accounts and social-media games that require payment for certain features.

David Rebuck, executive director of New Jersey's gaming enforcement agency, said Monday that owners of social games had already checked with his technical services staff about how to convert social games into gambling games.

"If we approve that as a gambling game, then that would be different. They would go up on the gambling site. We don't regulate social games," Rebuck said.

Built into New Jersey's Internet gaming sites are safeguards, Rebuck said. Gamblers "can set spending limits. They can set deposit limits," he said.

When a gambler's lifetime deposits into an Internet gambling account reach $2,500, the casino must block any further gambling until the gambler acknowledges that he has reached that threshold, has the capability to set limits, and is aware of the help line 1-800-GAMBLER.

But that threshold applies to each individual online casino, which means that starting Tuesday, a gambler could deposit a total of $15,000 in accounts at six online casinos before getting those cautionary notices.

The regulations also require each Internet casino to generate a weekly report that identifies potential problem gamblers, including those who self-report. But the rules do not define "problem gambler."

A big concern for compulsive-gambling experts is the tendency of electronic gambling - even in the form of the electronic slot machines that dominate casino floors - to turn gamblers into addicts in an ever-shorter period of time.

"It used to take 15 to 20 years for people to become compulsive gamblers, back in the '60s and '70s," said C.P. Mirarchi III, a counselor for compulsive gamblers in Philadelphia and clinical director of Genesis Gambling and Treatment Program in Collingswood. Now he treats people who get addicted in a year, he said.

First came Atlantic City casinos, then Pennsylvania slots barns, and finally the Internet. "Imagine, now they don't even have to go out," Mirarchi said.

215-854-4651 @InqBrubaker