Response to Galbraith and Weill.

To the Editor:

The article of Galbraith and Weill (2009), which seriously questions whether diacetyl-induced bronchiolitis obliterans exists, also expressed doubt about the validity of the diagnoses of the two cases reported by the California Department of Health Services (Harrison 2006). We agree that the CAT scan results alone do not establish the diagnosis of bronchiolitis obliterans; however, bronchiolitis obliterans is by far the most likely diagnosis when considering the other clinical findings and pulmonary function testing showing severe nonreversible obstructive spirometric abnormalities, lung volume hyperinflation and air trapping, and maintained diffusing capacity. Similar comments apply to the biopsy of the second case, which was actually interpreted as highly consistent with bronchiolitis obliterans by an expert pathologist.

While the authors severely criticize individual components of much of the published literature, the overall weight of the scientific evidence supports an association between flavoring exposure and bronchiolitis obliterans. We concur, however, that the link to diacetyl per se is not 100% established, although the data are strongly supportive of such a causal association.