A field investigation of the acute respiratory effects of metal working fluids. II. Effects of airborne sulfur exposures.

An investigation of the acute respiratory effects of workers exposed to metal working fluids (MWF) was conducted in an automobile parts manufacturing facility. After observing an association between cross-shift decline in forced expiratory volume in the first second (FEV1) and aerosol mass concentration, improved characterization of the exposure was sought through investigation of four elements of a priori interest (Cl, Cr, Ni, S). Of these, only sulfur showed an association with cross-shift FEV1 decrement. The relative risk of 5% cross-shift FEV1 decrement was 2.7 (95% confidence interval = 1.0-6.0) comparing those with > 4.4 micrograms/m3 to those with < 2.5 micrograms/m3 sulfur exposure. Because the concentrations of sulfur in this environment were relatively low and other respiratory irritants were present, sulfur is more likely to be an indicator of more irritating conditions than the sole agent responsible for the observed acute respiratory effects.