Diacetyl-induced occupational lung disease: insights from two cases

Introduction Occupational exposure to diacetyl may cause severe respiratory diseases, including bronchiolitis obliterans. Research has focused on diacetyl vapor exposure, but the risk from diacetyl-containing powder may also be problematic. We investigated two cases of occupational lung disease in workers at a flavor manufacturing facility.Case reports Two cases of occupational lung disease caused by diacetyl exposure were identified in workers at a flavor manufacturing plant in China, including one case of bronchiolitis obliterans. Both workers developed severe obstructive lung disease after short-term exposure to diacetyl-containing flavoring powder.Discussion The two patients and existing literature show that workers exposed to diacetyl-containing flavoring powder are at higher risk of occupational lung disease, particularly obliterative bronchiolitis, compared to unexposed workers. Case study findings suggest the lung damage from powder exposure may be underestimated. The likely mechanism involves hydrated particles releasing diacetyl directly onto bronchiolar epithelial cells, triggering local inflammation and abnormal fibrosis. Key knowledge gaps include validating particle-mediated release in vivo, characterizing aerosol properties beyond size and quantifying diacetyl in powder.Conclusion Inhalation of diacetyl-containing flavoring powder may play a more critical role in occupational lung disease than exposure to diacetyl vapor alone, but the underlying injury mechanisms remain poorly understood.