Hypersensitivity pneumonitis in a metal-working environment

Background An outbreak of lung disease among workers lit a metal-working pl ant included 16 biopsy-confirmed cases of hypersensitivity pneumonitis and additional patients with asthma, bronchiolitis and emphysema, usual interst itial pneumonitis, and sarcoidosis. Study design Clinical examination of patients; cross-sectional questionnair e survey of the outbreak plant and two control plant areas, one with and on e without MWF exposures, in a separate facility; industrial hygiene survey with laboratory characterization of microbial flora; and immunological inve stigation Methods Patients with suspected hypersensitivity pneumonitis underwent a cl inical examination including detailed lung function, imaging, and tissue st udies. A plant walk through identified metal-working processes, microbial a erosols, and work practices. Microbial characteristics of the three microbi al aerosol-producing precesses were characterized. Antibodies to those agen ts were determined in patient sera. A questionnaire survey was conducted in the case plant and irt two areas of a control plant one with and one witho ut metal-working fluids exposure. Results Thirty-nine (79.6%) patients described symptoms consistent with wor k-related lung disease, eight received other diagnoses, and two did not com plete their examinations. Sixteen patients had hypersensitivity pneumonitis confirmed on biopsy. Mean decrements in lung forced expiratory volume in 1 s and force vital capacity from before to after work were similar in the 1 6 biopsy-confirmed cases of hypersensitivity pneumonitis (-6.3%; -7.2%) and the 19 symptomatic patients without biopsies (-11.2%, -10.1%). Symptoms we re more common in rite case plant than in a non-MWF control plant area. Thr ee sources of water-based aerosols were identified that grew similar microb ial flora. Although machining increased airborne bacterial levels, the incr ease was not related to the concentration of viable bacteria in the sumps. Antibody testing did not identify a specific single organisms. Endotoxin le vels were similar in case and MWF control plant. Conclusion Lung disease in environments with water-based aerosols may be mo re common than usually recognized. Patients with HP often present with only subtle abnormalities and may be missed if multiple clinical abnormalities are required to document disease. Am. J. Ind. Med. 39:616-628, 2001. (C) 20 01 Wiley-Liss, Inc.