The needles are a reminder that insiders – people who work within the industry and have passed a background check – are among the biggest threats to aviation security, Southers said.

Gate Gourmet’s ads for cooks say applicants must be able to pass a criminal background check. The TSA declined to discuss the security process.

Ton Scherrenberg, chairman of the VNC union that represents some 7,000 Dutch cabin personnel, said cabin crews check prepared food for foreign objects when they open catering packages, “but you can’t check every single sandwich.”

When the needles were discovered on the first Delta flight, a message went out to other Delta flights, which is why some of the needles were found before they got to passengers. The TSA said it “immediately notified all U.S. air carriers with flights from Schiphol to ensure awareness.”

On board Tonjes’ flight, he pushed the flight attendant call button as soon as he found his needle. A few minutes later, another passenger nearby did the same thing. He said flight attendants offered to call ahead for an ambulance.

“When we landed, it was very, very impressive. When they opened the door, it was flooded with customs agents, police, paramedics and firefighters. It was the whole jetway full of people.”

The FBI interviewed him for about three hours. He said he was told the remaining sandwiches were X-rayed, and a third needle was found.

Gate Gourmet was cited by the FDA in 2005 for failing to keep meat at proper temperatures and for the presence of live flies and roaches near its salad production area, plus other violations.

Roy Costa, who runs food safety consulting firm Environ Health Associates in Deland, Fla., and used to be an auditor with the Department of Health and Human Services for more than 20 years, said food preparation standards are not as tight in Europe as in the U.S.

“Everything we do over here, we do because the (Food and Drug Administration) requires it,” he said. “There’s just a huge hole there.”

Associated Press writers Doug Glass in Minneapolis, Mike Corder in the Hague, Netherlands, and Samantha Bomkamp in New York contributed to this report.