Second Butter Flavoring Implicated in Bronchiolitis Obliterans
A recent study has allegedly linked a second artificial butter flavoring— 2,3-pentanedione (PD)—to respiratory toxicity in animals, raising concerns about the diacetyl replacement’s potential effects on factory workers. Ann Hubbs, et al., “Respiratory and Olfactory Cytotoxicity of Inhaled 2,3-Pentanedione in Sprague-Dawley Rats,” The American Journal of Pathology, September 2012. After exposing rats to either PD, diacetyl or air for six hours, researchers reported that those inhaling PD “developed necrotizing rhinitis, tracheitis, and bronchitis comparable to diacetyl-induced injury.” The study’s authors then investigated PD’s delayed toxicity on the animals, concluding that the substance caused “respiratory epithelial injury in the upper nose . . . which progressed through 12 to 14 hours after exposure,” as well as the loss of olfactory neurons and altered gene expression in the brain.
“Our study demonstrates that PD, like diacetyl, damages airway epithelium in
laboratory studies. This finding is important because the damage is believed
to be the underlying cause of bronchiolitis obliterans,” said lead author Ann
Hubbs of the Centers for Disease Control and Prevention’s National Institute
for Occupational Safety and Health.“Our study also supports established
recommendations that flavorings should be substituted only when there is
evidence that the substitute is less toxic than the agent it replaces.”
In particular, the study notes that even though PD is classified “as generally
recognized as safe under its normal use when consumed in food,” “a chemical
with a long history of being eaten without any evidence of toxicity [] can
still be an agent with respiratory toxicity.” To this end, the findings seek to
identify the shared features of short-chain diketones like diacetyl and PD that
could contribute to their apparent cytotoxicity. “Thus, our study suggests
several intriguing potential mechanisms for the toxicity of inhaled volatile
α-diketones, demonstrates mRNA changes in the brain, documents olfactory
neurotoxicity, and clearly demonstrates that the remarkable airway toxicity
is shared with its close structural relative, PD,” conclude the authors. See
American Journal of Pathology Press Release, August 13, 2012.
