Sixteen factory workers in two US states have been diagnosed with a severe lung disease that experts from the US National Institute for Occupational Safety and Health are linking to their work with large vats of artificial butter flavoring.

The Institute issued a report in August detailing the nine Missouri workers who developed bronchiolitis obliterans, a rare and permanently disabling lung disorder, and a further seven workers who experienced other lung problems after working with the artificial flavoring.

Four of the workers diagnosed with bronchiolitis obliterans are currently on the waiting list for lung transplants.

Experts have stressed that the cases have not revealed any risks to consumers, as the disease has only occured in those who inhaled large amounts of the liquid flavouring.