The Centers for Disease Control and Prevention and the National Institute for Occupational Safety and Health (NIOSH), which began studying the phenomenon in 2000 when workers at a microwave popcorn packaging plant began complaining of bronchiolitis obliterans, provide further evidence to support the contention that exposure to flavoring agents in popcorn production presents an occupational hazard.
"Results of the health hazard evaluations to date suggest that adverse effects may result from occupational inhalation exposures to high, airborne concentrations of some flavourings or their ingredients in the form of vapours, dusts, or sprays," NIOSH said in a statement.
And after completing their study of conditions at the Missouri plant, investigators have concluded that workers exposed to chemicals given off by flavor additives being mixed into the popcorn had a higher chance of falling ill.
Experts diagnosed severe lung illnesses in eight workers. These people had no other risk factors for lung disease, but became severely ill with respiratory illness.
The findings have worrying implications for flavor businesses. Last year for example, jurors decided that IFF and its subsidiary, Bush Boake Allen, should pay $20 million in damages after a US popcorn factory worker sustained harm to his lungs from mixing flavouring oils.
The company then narrowly avoided a hefty payout later in the year after a jury ruled against four popcorn factory employees who claimed a butter flavoring caused harmful lung injuries.
IFF, the second largest flavor firm in the world, faced potentially massive charges following a string of charges from 30 plaintiffs claiming they had contracted the lung disease bronchiolitis obliterans, the widespread obstruction of the small airways, from mixing flavoring oils.
Butter flavoring oils are also big business in the US. The market is tipped to hit $4.4 billion (€3.4bn) by 2007, with products used in biscuit and confectionery manufacturing as well as margarines and soft spreads.
But in January this year, NIOSH recommended that employers should take measures to limit employees 'occupational respiratory exposures to food flavorings and flavoring ingredients in workplaces where flavorings are made or used'. And the recent NIOSH study on the Missouri factory goes even further.
Reporting in the journal Chest, the team concluded that the Missouri factory workers exposed to flavoring agents were nearly four times more likely to develop airway inflammation, a sign people were breathing in harmful agents.