DENVER -- A U.S. federal court jury on Wednesday awarded a Colorado man $7.2 million in damages for developing a chronic condition known as popcorn lung from a chemical used in flavoring microwave popcorn.

Jurors agreed with the claims by Wayne Watson, 59, that the downstate Illinois popcorn manufacturer and the supermarket chain that sold it were negligent by failing to warn on labels that the butter flavoring, diacetyl, was dangerous.

The condition is a form of obstructive lung disease that makes it difficult for air to flow out of the lungs and is irreversible, according to WebMd.

Watson, of suburban Denver, was the first consumer of microwave popcorn diagnosed with the disease, bronchiolitis obliterans, his attorney Kenneth McClain said.

Watson was diagnosed in 2007 at Denver's National Jewish Health, a respiratory health center, after years of inhaling the smell of artificial butter on the popcorn he said he ate daily.

The verdict was the latest in a line of cases in the past 15 years, starting with workers in popcorn plants where diacetyl was an ingredient, that has linked the chemical to health problems.

Jurors found Gilster-Mary Lee Corp., the Chester, Ill., private-labeling manufacturer of the popcorn, liable for 80 percent of the $7,217,961 damages and the King Soopers supermarket chain and its parent, Kroger Co, liable for 20 percent.

An attorney for the defendants had told jurors that Watson's health problems were from his years of using dangerous chemicals as a carpet cleaner.

A spokeswoman for King Soopers and Kroger said the companies intended to appeal the decision. An attorney for Gilster-Mary Lee was not immediately available for comment.

Similar cases are pending in federal court in Iowa and in state court in New York, Watson's attorney said.

McClain said he has represented microwave popcorn and flavoring workers across the United States who began suing in 2004 and have been awarded large damages.

He said Dr. Cecile Rose, a witness for Watson and one of his physicians at National Jewish Health, made the connection between his disease and diacetyl when she asked him if he had been around large quantities of microwave popcorn.

She had been a consultant to the flavorings industry and had seen the same disease that Watson had among workers exposed to the chemical.

The jury took a day to reach its verdict after a nine-day trial.

(Editing by Tim Gaynor and Prudence Crowther)