The latest petition by workers unions to the California Occupational Safety and Health Standards Board requests an emergency temporary standard to be immediately established for the ingredient, with permanent regulations following close behind.
The move comes just a few weeks after a similar petition filed in July with the Department of Labor (DOL).
Diacetyl, an artificial butter flavouring used in popcorn, pastries, frozen foods and confectionery, has been repeatedly linked to lung disease in employees of popcorn plants. However, there are currently no enforceable Occupational Safety and Health Act (OSHA) standards requiring exposures to be controlled.
And while unions push for the regulatory loophole to be addressed, employees in popcorn plants continue to be diagnosed with the rare and often fatal - lung disease bronchiolitis obliterans, while flavor manufacturers continue to fork out settlement charges in cases brought against them.
The first major US case filed by workers who had contracted the disease, otherwise known as popcorn workers lung, resulted in a $20m verdict.
Filed two years ago, the case involved the first of around 40 affected workers at a Gilster-Mary Lee plant in Jasper, Missouri, and was brought against flavor firms International Flavors and Fragrances (IFF) and its subsidiary Bush Boake Allen. According to attorney Steve Crick of Humphrey Farrington & McClain, the case went on appeal and a settlement was subsequently reached.
Eight trials in the same case have since occurred, all of which have resulted in significant verdicts, and which were ultimately settled out of court.
Crick told FoodNavigator-USA.com that his law firm has dealt with over 100 cases in the past two years, and that these continue to flow in. The most recent case involving workers at a ConAgra plant and filed against IFF and Givaudan was due to go to trial on August 29, but was settled immediately before, he said.
The flavour firms caught up in the litigation were reluctant to comment, but maintained that their products are safe if used properly. And popcorn manufacturers, such as ConAgra, which have not been embroiled in the cases but which are ultimately responsible for the health and safety of their workers, claim to strictly follow ingredient manufacturers instructions for handling the ingredients.
Indeed, according to Crick, the food firms took the precautions they needed to take. And when they knew there was a hazard, they took more precautions.
In January last year, the National Institute of Occupational Safety and Health (NIOSH), a body that falls under the US Department of Health and Human Services, recommended that employers take measures to limit employees occupational respiratory exposures to food flavorings and flavoring ingredients in workplaces where flavorings are made or used'.
Reporting in the journal Chest, the team concluded that workers exposed to flavoring agents were nearly four times more likely to develop airway inflammation, a sign people were breathing in harmful agents.
The alert stemmed from a series of NIOSH health hazard evaluations that began in 2000 when NIOSH learned of the occurrence of bronchiolitis obliterans in workers at a microwave popcorn packaging plant.
"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 vapors, dusts, or sprays, said NIOSH had said in a statement.