Popcorn worker's lung: in vitro exposure to diacetyl (D), an ingredient in microwave popcorn butter flavoring, damages guinea-pig tracheal epithelium (E) and increases reactivity to methacholine (MCh).
Fedan-JS; Dowdy-JA; Hubbs-AF; Fedan-KB
Proc Am Thorac Soc 2005 May; 2(Abstracts):A814
Workers exposed by inhalation to volatile microwave popcorn butter flavorings experience decrements in lung function and develop bronchiolitis obliterans, i.e., "popcorn worker's lung." D, a major flavoring ingredient, is implicated in causing workers' symptoms. After inhalation exposure of rats, D caused necrosis of E in upper and lower airways. We investigated the hypothesis that D-induced damage to E alters airway reactivity by examining in the guinea-pig isolated, perfused trachea, its direct effects, and its effect on reactivity to MCh and terbutaline (T). Cumulative additions of D to the intraluminal (IL) bath resulted in responses that began with contraction and ended with relaxation, with a threshold of ca. 3 mM. After a 4-h incubation with IL applied D (3 mM), contractions to cumulative concentrations of MCh added to the extraluminal (EL) bath were increased; the EC50 was unaffected. However, sensitivity to IL-applied MCh was increased (EC50s [M] were, control: 3.4xl0^-4, D-treated: 3.0xl0^-5; p<0.05). D had no effect on maximum responses to MCh. Reactivity to ELapplied T in MCh (3x10^-7 M)-contracted tracheas was unaffected by D. These findings indicated that the increase in reactivity to IL MCh after D-treatment resulted from an alteration in E, e.g., a compromise in its barrier function and/or a decrease in the release of epithelium-derived relaxing factor. H&E sections of tracheas perfused (4 h) with D and not challenged with MCh or T demonstrated E degeneration or necrosis in 2 of 5 preparations; no changes were seen in vehicle controls or in the smooth muscle. These findings suggest that functional changes in reactivity may precede light microscopic evidence of pathologic changes after D-treatment.
In-vitro-studies; Methacholines; Laboratory-animals; Animals; Animal-studies; Workers; Worker-health; Lung-function; Lung-disorders; Inhalants; Inhalation-studies; Pulmonary-system-disorders; Respiratory-system-disorders
Abstract; Conference/Symposia Proceedings
Issue of Publication
Proceedings of the American Thoracic Society. 2005 ATS International Conference, May 20-25, 2005, San Diego, California