ACUTE RESPIRATORY EFFECTS ON WORKERS EXPOSED TO METALWORKING FLUID AEROSOLS IN AN AUTOMOTIVE TRANSMISSION PLANT

Exposure to metalworking fluids has been linked to modest cross-shift reductions in FEV(1) and occupational asthma. To identify responsible agents, we measured personal exposures to thoracic particulate (TP), v iable plus nonviable thoracic bacteria (BAC), and vapor phase nicotine (VPN) (as a surrogate for tobacco particulate) among 83 machinists ex posed to soluble oils and 46 dry assemblers working in an automotive t ransmission machining plant using biocides infrequently. The participa nts completed interviews and performed pre- and postshift spirometry o n Monday and Thursday of the same week in each of three rounds of data collection (June 1992, January 1993, June 1993). Generalized estimati ng equations were used to combine information across rounds in multipl e regression models of cross-shift and cross-week changes in forced ex piratory volume, 1 second (FEV(1)) and forced vital capacity (FVC). Me an seniority was 19 years among machinists. Mean personal TP levels we re 0.41 mg/m(3) in machinists and 0.13 mg/m(3) in assemblers. Six of t he 83 machinists and none of the 46 assemblers experienced a greater t han 19% cross-shift decrement in FEV(1) or FVC at least once (p=.07). In regression models using either TP or BAC, among subjects with lower baseline (Monday preshift) FEV(1)/FVC ratios, increasing exposure was significantly associated with increasing cross-shift decrements in FE V(1), and FVC in linear models, and with increased likelihood of a 10% or greater cross-shift decrement in FEV(1) or FVC in logistic models. Adjustment of TP for VPN did not affect models significantly. We conc lude that clinically important cross-shift decrements in pulmonary fun ction are associated with exposure to metalworking fluid aerosols with in a high-seniority population. (C) 1997 Wiley-Liss, Inc.