"I feel so stupid right now."

So said a 26-year-old California woman who admitted to police that she falsely reported finding a needle in a can of Diet Pepsi this week. The woman, who spoke on the condition that her name not be used, said she acted on a prankish impulse: "I had just heard about the Pepsi that day, and thought, 'Ha, ha -- this would be a funny joke.' "

Food and Drug Administration officials were not amused. FDA Commissioner David A. Kessler held a news conference yesterday, hoping to lay to rest "the notion that there has been a nationwide tampering of Diet Pepsi."

Kessler stated that not one case among scores reported in two dozen states had yet been confirmed. He pledged that the FDA would continue to work with industry to make products safe, but warned, "I will not stand before you today and promise that you will never find a foreign object in any food or beverage. . . . No product -- no container -- is 100 percent tamper-proof." Kessler suggested that consumers "look twice" at whatever they buy. "A little prudence with all products is appropriate. It just makes good sense."

The agency is not releasing the number of can complaints, Kessler said, because "if I give you a number, there's always somebody who will want to make it that number plus one. We need to end this vicious cycle."

The Pepsi-Cola Co. trumpeted the growing evidence that most of the reports are frauds. "These developments bring us a day closer to business as usual," Craig Weatherup, president and chief executive officer of Pepsi-Cola North America, said in a statement. Calls to the company's toll-free product line have swelled from the usual hundred or so a day into the thousands as consumers clamored for information about the safety of the product. Yesterday the company released a surveillance tape from a Colorado store that Pepsi officials said showed a woman dropping a syringe into a can of Diet Pepsi and claiming it had been tampered with by someone else.

At least 10 claims of tampering reportedly have fallen apart under questioning by federal or local authorities.

Why have people lied? The California woman cited pressures that might also have contributed to her state of mind, including her recent divorce, the responsibility of raising two children on her own, and the fading of a new relationship she felt showed promise. "I thought I was losing everything," she said. "I was just basically wanting attention."

Police responded to the woman's complaint Tuesday evening, but grew suspicious of her claim when they discovered on reaching her house that local television news crews had arrived first. Sgt. Nick Concolino of the Davis city police said he took the woman aside after her TV appearance and explained that falsely reporting a tampering incident is a felony punishable by up to five years in prison. She recanted, explaining that she had broken a sewing needle and dropped the pieces into a can. The woman, who has not been charged and has since sought counseling, said, "I will definitely use my head before I do anything like that again."

According to the FDA and police sources, at least five people have been arrested so far on charges of filing false claims. Arrests include: Christopher J. Burnette, 25, of Williamsport, Pa., who gave FDA officials a sworn statement admitting the fraud; Maria Luz Martinez, 62, of Covina, Calif.; Debbie Lynn Branham, of Albion, Mich.; and Kelly Fitzwater, 29, of Beach City, Ohio.

Police arrested Eugene A. Bunting, 37, of Rantoul, Ill., who walked into the lobby of the local police station earlier this week with a needle in a can. Detective John Grabow said the man was a diabetic and admitted using one of his own needles to create the hoax.

Katherine "Kitty" Wuerl -- an employee in the marketing department of Journal/Sentinel Inc., a newspaper publisher in Milwaukee -- said she found a syringe in a Pepsi she opened in the company's lounge.

The morning Milwaukee Sentinel put the story on the front page. The competing afternoon Milwaukee Journal -- which shares facilities with the Sentinel and whose reporters work near their counterparts -- then published a debunking story. The Journal noted that no one else saw Wuerl open the can and cited files that showed physicians had doubted her credibility on past injury reports. The Sentinel is publishing a similar report today.

One of the first people to report finding a syringe stuck by her story yesterday. Rock Springs, Wyo., resident Peggy Syndergaard, who reported being stuck in the lip after taking her second sip from a Pepsi can on Monday, told the local press that she feels harassed by authorities. Her attorney, Richard Honaker, told the Rock Springs Rocket Miner that, "The consumer should not be put on trial because of a defective product." Industry experts said Wyoming stores could have gotten cans from the same supplier as Washington state, where the first incident was reported last week.

FDA Commissioner Kessler said yesterday that, "We will never accuse anyone of anything as long as {the report is made} in good faith."

Industry experts said that tampering hoaxes will not fade away. Jesse Meyers, publisher of the Old Greenwich, Conn., newsletter Beverage Digest, said, "Emulative crises are a contemporary fact of life," pegged to whatever is in the media spotlight at the time. "I'm sure with the current state of affairs, we will soon have reports of small dinosaurs in cans."