The Associated Press

MARION, Ohio - A federal agency is investigating whether employees of a popcorn plant have been stricken with a lung disease that may be linked to breathing chemicals used in butter flavorings.

The National Institute for Occupational Safety and Health, a division of the Centers for Disease Control and Prevention, began looking this month at the ConAgra Snack Foods Group plant.

The investigation was requested by three employees in December, eight months after the CDC issued a report detailing serious lung disease in workers at a Jasper, Mo., popcorn plant owned by another company.

Similar investigations are in progress at five other plants in Illinois, Iowa, Missouri and Nebraska.

The agency visited the Marion plant, about 40 miles north of Columbus, this month. A team will return in March for a more in-depth evaluation. The plant has about 300 employees.

Results are not ready on preliminary sampling. A full analysis will take several months.

Dr. Richard Kanwal, the medical officer leading the investigation, said he is preparing to recommend immediate changes, including respirators for workers who mix popcorn flavorings.

He said it's too soon to say what, if anything, is making the workers sick.

"I think all bets are off until we actually do our survey at this plant," Dr. Kanwal told the Columbus Dispatch for a story Sunday.

Timothy Arthur, a former employee who left the plant last August, suffers from bronchitis and acute emphysema he thinks he contracted while working there.

"Three years ago, I could walk around the block in the country. Now I have no lung capacity - 50 to 75 feet, and I'm out of breath," said Mr. Arthur, 42.

During the past couple of years, he and other current and former employees say they had similar health problems: colds they couldn't shake, recurring bronchitis, asthma and emphysema.

ConAgra officials said they have no confirmation that any current or former Marion employees have "verified cases of bronchial issues."

"Our microwave popcorn is completely safe to manufacture," said Bob McKeon, spokesman for the Omaha, Neb.-based company.

Last April, the CDC expressed concern about a link between exposure to chemicals in popcorn flavorings and cases of fixed obstructive lung disease.

The disease is rare and severe. It causes coughing, shortness of breath and obstructed airways that don't respond to normal asthma medication. It can be triggered by exposure to ammonia, chlorine, nitrogen dioxide, sulfur dioxide or other chemicals.

Three years ago, an occupational-medicine doctor contacted the Missouri Department of Health and Senior Services to report eight cases of the disease in former workers at the plant in Jasper. Four were awaiting lung transplants.

An investigation showed that those who mixed ingredients were at the highest risk of the disease and that there was some risk among packagers.