03/14/2008A recent study adds more evidence that diacetyl, the compound frequently used in the food industry to produce butter flavor, causes obliterative bronchiolitis (OB), a serious, irreversible lung disease, in factory workers who inhale high concentrations of the ingredient. Scientists at the National Institute of Environmental Health Sciences (NIEHS), part of the National Institutes of Health, conducted the study, which showed breathing diacetyl can harm the nose and airways of mice.
The research (“Respiratory Toxicity of Diacetyl in C57Bl/6 Mice,” Toxicological Sciences, doi:10.1093/toxsci/kfn016) found that, when laboratory mice inhaled diacetyl vapors for three months, they developed lymphocytic bronchiolitis, a potential precursor of OB, but not the disease itself. In the study, mice were exposed to several concentrations and durations of inhaled diacetyl, or by direct aspiration.
“This is one of the first studies to evaluate the respiratory toxicity of diacetyl at levels relevant to human health. Mice were exposed to diacetyl at concentrations and durations comparable to what may be inhaled at some microwave popcorn packaging plants,” said Daniel L. Morgan, Ph.D., head of the Respiratory Toxicology Group at the NIEHS and coauthor of the paper, which was done in collaboration with DukeUniversity researchers.
The authors conclude the results suggest workplace exposure to diacetyl contributes to the development of OB in humans, but that more research is needed, partly because of the anatomical differences between mice and people.
In nature, diacetyl is a natural byproduct of fermentation found in dairy products such as butter, cheese and milk, as well as in bread, coffee, brandy and rum. It has been used as a component of artificial butter flavoring for many years. Butter flavorings consist of mixtures of more than 100 different chemicals, of which diacetyl and acetoin are more prominent.
After cases of bronchiolitis obliterans in former workers of a microwave popcorn plant in Jasper, MO, were brought to the attention of the National Institute of Occupational Safety and Health (NIOSH), the discovery of other affected workers, and further research, linked the disease, also known as “popcorn worker’s lung,” to diacetyl in butter flavors. This resulted in a 2004 NIOSH Alert, “Preventing Lung Disease in Workers Who Use or Make Flavorings.” Additionally, several food companies have announced plans to remove added diacetyl from microwave popcorn to provide safer work environments for their employees, and to address consumer concerns about any potential risks for those who consume the product.
The National Toxicology Program at the NIEHS plans to carry out additional studies on artificial butter flavoring and the two major components, diacetyl (C4H6O2) and acetoin (C4H8O2) to help pinpoint the components responsible for lung injury and to help identify biomarkers for early detection. The data will be used to help set safe exposure levels for these compounds and to develop guidance to protect those who work with them.
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Edited by Hongyun, 15 March 2008 - 12:51 PM.