[4] Rats exposed to acetylpropionyl develop both fibrosis and necrosis of the respiratory tract.

[4] Mice exposed to acetylpropionyl demonstrate more bronchial constriction in response to methacholine challenge.

[4] However, in one flavoring manufacturing facility that substituted diacetyl for acetylpropionyl, abnormal lung function values were associated with total time spent in production areas.

[4] An investigation by NIOSH in 2009 at a facility that used buttermilk flavoring containing acetylpropionyl demonstrated that workers had higher than average reports of shortness of breath, asthma, and restrictive type spirometry defects.

[8] Another investigation by NIOSH in 2013 at a flavoring manufacturer that used acetylpropionyl revealed that those workers who spent the most time working with flavoring chemicals, including acetylpropionyl, were more likely to have abnormal lung function as detected by pulmonary function tests.