The buses pull up to the Atlantic City casinos every day, each one full of elderly day-trippers like May Riches, 66, who disembark and head straight for the slot machines and gambling tables, toting their pocketbooks, rolls of quarters and lighted cigarettes.

With more smoking areas than nonsmoking areas, casinos are among the last public refuges for smokers. No one knows the exact percentage of patrons who smoke, but casino operators here know very well that older smokers like Riches are a large part of their highly competitive business. And the casinos strive to keep them comfortable.But some casino employees say they are another story. Last month, a group of nonsmoking casino workers brought suit in New Jersey Superior Court against a dozen tobacco companies and the industry's marketing association, the Tobacco Institute, asserting that secondhand smoke was making them sick.

Lawyers for the employees said that the tobacco industry was liable because it had conspired over the years to withhold information about the dangers of smoking. And the lawyers are armed with recent studies on the effects of secondhand smoke.

Nat Walker, a spokesman for R.J. Reynolds Tobacco Co., a defendant in the lawsuit, said that there were "extraordinarily weak statistical associations" between secondhand smoke and health prob-lems cited in many of the studies. He noted that there were about a half-dozen such secondhand-smoke cases among the flurry of legal actions aimed at the tobacco industry nationwide.

"This might be a case like so many others today of people jumping on the gravy train," he said.

Although aimed at the tobacco companies, the lawsuit, which is similar to one pending in federal court in Las Vegas, has not been welcomed by casino operators. If a jury sides with the casino workers and the casinos are subsequently forced to crack down on smoking, they expect business to suffer. Casinos have found that many older smokers are not eager to quit or to cede even more gambling space to nonsmokers.

Casino dealers have not been shy in the past about complaining about job-related problems like repetitive stress injuries, too few bathroom breaks and abdominal strains from the constant bending at the waist to rake in chips or dice. But most who were asked recently about whether secondhand smoke was a hazard were silent.

Even so, said Roger Gros, a former dealer and now senior editor at the Atlantic City-based Casino Journal, dealers will privately tell story after story about the players at their tables who seem oblivious to the smoke they are blowing on others.

"It's not something that we are crazy about," Gros said.

Similarly, Brad Smith, the chairman of the New Jersey Casino Control Commission, said that tobacco smoke was by far the most common complaint he heard from casino workers.

"But the casinos cater to their customers, and most see it as a problem that comes with the territory," he said. And the commission has no jurisdiction over smoking.

Hoping to make the case a class-action suit, Brian Clodes, a Philadelphia-based lawyer for the four current and former Atlantic City dealers who brought the suit, cited recent studies by the National Institute of Occupational Safety and Health in an Atlantic City casino and at the University of Nevada at Reno of the effects of secondhand smoke at some casinos.

The Atlantic City study found that casino workers were exposed to higher levels of environmental tobacco smoke than were members of the general population. The study also found that test levels were similar for workers in both smoking and nonsmoking areas of casinos.

And the Nevada study found that, in reaction to this exposure, casino workers' bodies produced higher levels of "oxidative stress" in the blood, a biochemical reaction that causes DNA damage and "may increase the risk of certain diseases," said Chris Pritsos, one of the researchers. He said that there was a correlation between this reaction and cancer and coronary heart disease.