A nationwide warning of possible salmonella contamination in raw red tomatoes has led some grocery stores to remove them from the shelves, restaurants to quit serving them and consumers to ponder whether to slice them from their diets.

The Food and Drug Administration issued a warning Thursday about possible salmonella contamination of Roma, plum and round red tomatoes from certain sources. But it has issued no recall.

Homegrown tomatoes and grape, cherry and cluster tomatoes with vines still attached, and from any source, remain safe for consumption. The FDA said updates are available on its Web site at www.fda.gov.

The Allegheny County and state health departments report no cases of salmonellosis, or illness from salmonella contamination, related to tomato consumption.

But Guillermo Cole, Allegheny County Health Department spokesman, said "every retailer, restaurateur and food operator should be checking the tomatoes they carry and the source."

"We're telling them not to offer to sell any except those from approved sources," Mr. Cole said.

Last week, the FDA reported a salmonellosis outbreak in New Mexico and Texas that it linked to consumption of "plum and Roma tomatoes, or round red tomatoes."

From April 23 through June 1, there were 57 reported cases of salmonellosis, caused by an uncommon strain known as Salmonella Saintpaul. Of 57 reported cases, 17 involved hospitalizations, with no deaths.

The FDA and Centers for Disease Control and Prevention are investigating 30 reports of illness in Arizona, Colorado, Idaho, Illinois, Indiana, Kansas and Utah to determine if they can be linked to tomatoes.

Roma, plum and round red tomatoes from Arkansas, California, Georgia, Hawaii, North Carolina, South Carolina, Tennessee and Texas are not subject to the warning.

The FDA recommends that people limit tomato consumption to types not implicated in the outbreak. It also said to contact the supplier to determine whether tomatoes already purchased are from approved states. It advises against consuming tomatoes that are rotting, bruised or damaged.

The FDA said it recognizes "that the source of the contaminated tomatoes may be limited to a single grower or packer or tomatoes from a specific geographic area." It said it continues working "to determine the source and type of the contaminated tomatoes."

All Salmonella infections should be reported to state or local health officials, the FDA said. Mr. Cole said doctors are required to report cases of salmonellosis to county and state health departments.

Allegheny County averages about 100 cases of salmonellosis a year, with the state reporting 1,948 cases last year. Most could be traced to a specific source, said Stacy Kreideman, state health department spokeswoman.

"As for grocery stores, there's no recall at this point that's been issued, so grocery stores and restaurants that are pulling them off the shelves are doing it as a precaution, and it's totally voluntary," she said.

Giant Eagle has removed varieties of green, yellow, Roma, plum and organic tomatoes from its store shelves throughout the tri-state area, grocery chain spokesman Victor Kimmel said.

"This is a voluntary removal," he said. "There is no reason to believe any tomatoes from Giant Eagle are involved" in the outbreak.

Because only a small number of tomatoes are subject of the warning, a variety of tomatoes remain available, he said.

Jennifer R. Daurora, spokeswoman for McGinnis Sisters Special Food Stores in Brentwood and Monroeville, said the company is buying tomatoes only from approved states.

The warning has put Strip District produce suppliers in a real pickle. With a warning, rather than recall, growers are not required to take back tomatoes they've shipped. Unable to return them, the distributors are unable to sell the tomatoes in question.

Gloria Garofalo, director of marketing for Paragon Monteverde, a fresh food distributor in the Strip District, said her company may be forced to discard tomatoes it cannot sell.

Her company spent considerable time yesterday "dealing with the situation and working with customers to assure they are getting what they want."

She said customers are seeking replacements for plum and Roma tomatoes. "We're in the middle of it, but we'll deal with it," she said.

Brad Kokowski, owner of Superior Produce Co. in the Strip, which provides produce to hundreds of restaurants and other food operators, said one restaurant chain returned all tomatoes yesterday morning and announced it would quit serving tomatoes for a week.

He's advising restaurants to keep tomatoes available and let their customers decide.

"This will affect our sale of tomatoes by at least 50 percent," Mr. Kokowski said. "It's been nothing but headaches all morning."