Respiratory health of automobile workers and exposures to metal-working fluid aerosols: Lung spirometry

Background Despite substantial evidence that workers exposed to metal-worki ng fluids (MWF) have increased respiratory morbidity, the few studies of ch ronic effects on lung function have not been conclusive. Methods Lung spirometry was measured and both current and past exposures to metal-working fluid (MWF) aerosols were estimated in this cross-sectional cohort of 1,811 male automobile workers. Satisfactory exposure data were av ailable for 1,745 (96%): 239 assemblers (never-exposed to MWF), 487 assembl ers (previously exposed), 352 machinists currently exposed to straight oils , 441 to soluble oils, and 226 to synthetic fluids. Operations were classif ied as either grinding or non-grinding machining. Results Current exposure was not found to be associated with either forced expiratory volume in 1 second (FEV1) or forced ventilatory capacity (FVC). Nor was past exposure to water-based fluids (soluble or synthetic MWF) rela ted to pulmonary function. Past exposure to straight oils, however, was sig nificantly associated with FVC. This association was more obvious among old er workers and among workers who had never transferred from MWF exposed job s to assembly. Conclusions The magnitude of the association between FVC and lifetime expos ure to straight MWF was slightly larger than the estimated cigarette effect , suggesting that the impact of an additional year of exposure to 1 mg/m(3) of mineral oil particulate in the thoracic particle size range, has the sa me impact on FVC as smoking one pack per day for one more year. Am. J. Ind. Med. 39:443-453, 2001. (C) 2001 Wiley-Liss, Inc.