Objective: To report the cases of four patients with bronchiolitis caused by exposure to artificial butter flavoring at a cookie factory in Brazil. Methods: We described the clinical, tomographic, and spirometric findings in the four patients, as well as the lung biopsy findings in one of the patients. Results: All four patients were young male nonsmokers and developed persistent airflow obstruction (reduced FEV1/FVC ratio and FEV1 at 25-44% of predicted) after 1-3 years of exposure to diacetyl, without the use of personal protective equipment, at a cookie factory. The HRCT findings were indicative of bronchiolitis. In one patient, the surgical lung biopsy revealed bronchiolitis obliterans accompanied by giant cells. Conclusions: Bronchiolitis resulting from exposure to artificial flavoring agents should be included in the differential diagnosis of airflow obstruction in workers in Brazil.

Keywords: Diacetyl; Flavoring agents; Bronchiolitis.