MACHINE OPERATORS LUNG - A HYPERSENSITIVITY PNEUMONITIS DISORDER ASSOCIATED WITH EXPOSURE TO METALWORKING FLUID AEROSOLS

Six auto parts manufacturing workers were referred for evaluation of a 6-week history of work-related dyspnea, cough, and fatigue. Two worke rs also reported fever and weight loss. All six worked in a machining area where a waterbased metalworking fluid was used and recirculated u nder high pressure, thereby creating an aerosol, Chest radiographs rev ealed pulmonary interstitial infiltrates in four workers. Lung functio n tests showed that four workers had decreased diffusing capacity. Aft er removal from the work area, all workers recovered. The metalworking fluid was cultured for bacteria and fungi. Isolates from broth cultur es were sonicated to obtain antigen extracts, Serum precipitins to one or more of the microbial isolates were identified in all six workers but not in eight of nine nonexposed control subjects. The most frequen t precipitin response (six of six workers) was against antigens of Pse udomonas fluorescens, which was cultured from the metalworking fluid. In all workers, precipitins to at least one other cultured organism we re detected; these included Aspergillus niger, Staphylococcus capitas, an acid-fast Rhodococcus sp, and Bacillus pumilus. This represents th e first report of hypersensitivity pneumonitis associated with industr ial exposure to aerosolized metal working fluid. Observed precipitin r esponses to a variety of microbial contaminants in metalworking fluid strongly suggest a causative role for microbial antigens in the induct ion and elicitation of this manifestation of hypersensitivity pneumoni tis.