During the last eight months, 11 workers at a pork processing plant in Austin, Minn., have developed numbness, tingling or other neurological symptoms, and some scientists think pieces of inhaled pig brain matter may be the origin of the illnesses.

The use of compressed air to remove pig brains on the slaughterhouse floor at Quality Pork Processors Inc. has come under suspicion from U.S. health authorities and was suspended earlier last week until authorities solve the mystery.

"I'm still in shock, I guess," said 37-year-old Susan Kruse, who worked at the plant for 15 years until she got too weak to do her job last February. "But it was very surprising to hear that there was that many other people that have gotten this."

Five of the workers — including Kruse, who has been told she may never work again — have been diagnosed with chronic inflammatory demyelinating polyneuropathy, or CIDP, a rare immune disorder that attacks the nerves and produces tingling, numbness and weakness in the arms and legs, sometimes causing lasting damage.

Minnesota health officials said there is no evidence the public is at risk — either from those afflicted or from any food leaving the plant, which supplies Hormel Foods Inc.

The working theory from two Mayo Clinic neurologists treating the workers: Exposure to pig brain tissue scattered by the compressed air triggered the illnesses.

"As we've investigated these patients, we have information that suggests very strongly that the immune system is activated very strongly in a very compelling way," said Dr. Daniel Lachance.

Compressed air could turn some brain matter into a mist that could be inhaled by workers, said Mike Doyle, a microbiologist who heads the University of Georgia's Center for Food Safety. Or the workers may have come into contact with something dangerous and then touched their noses or mouths, he said.

(Agencies via Xinhua News Agency December 11, 2007)