A US man has been awarded $7.2m (£4.4m) in damages after claiming he developed "popcorn lung" from inhaling the artificial butter in microwave popcorn.

A Colorado jury agreed with Wayne Watson that a popcorn manufacturer should have had warning labels that the bag's fumes were dangerous to inhale.

Defence lawyers argued that Mr Watson's problems stemmed from years of working with carpet-cleaning chemicals.

He developed respiratory problems in 2007, after regularly eating popcorn.

Image caption Wayne Watson (left) says he had not had any microwave popcorn since being diagnosed

"Popcorn lung" is a form of irreversible obstructive lung disease that scars the lung and makes it difficult for air to flow out.

The verdict is the latest in a series of successful cases, including by popcorn plant workers who became ill. The cases link diacetyl, an ingredient in the flavouring, to health problems.

Jurors found Gilster-Mary Lee Corp, a private-labelling manufacturer of popcorn, liable for 80% of the damages. Supermarket company Kroger Co was held liable for the other 20%.

Mr Watson had previously settled with flavourings company FONA International Inc.

"[The popcorn manufacturer] did absolutely no testing whatsoever to think the consumer might be at risk," Mr Watson told CBS News.

Mr Watson's case was helped by the testimony of Dr Cecile Rose, the doctor who diagnosed him with the condition.

She had been a consultant to the flavourings industry and had seen the same disease Mr Watson had developed among workers exposed to the chemical, Reuters reports.