Factors contributing to the acute and subchronic adverse respiratory effects of machining fluid aerosols in guinea pigs.
Toxicol Sci 1999 May; 49(1):86-92
Several physical, chemical, and microbial factors are potential contributors to the adverse pulmonary effects associated with occupational exposure to machining fluid aerosols. The present study examined the relative toxicity of 3 major classes of machining fluids (soluble, semi-synthetic, and synthetic) as well as that of unused (fresh) versus used (grab samples taken from manufacturing sites) machining fluids. Pulmonary function and changes in cellular and biochemical indices in bronchoalveolar lavage fluid were examined during and 24 h after exposure, respectively. Statistically significant differences in toxicity were observed in guinea pigs exposed for 3 h to respirable aerosols of unused machining fluids (semi-synthetic > soluble >> synthetic). In addition, greater toxicity was observed in animals exposed to used, machining fluid aerosols compared to unused fluids. Moreover, within the used machining fluid types, significantly greater adverse effects were observed in animals exposed to poorly maintained fluids (i.e., heavy microbial contamination) versus well-maintained fluids. Changes in biochemical and cellular parameters in bronchoalveolar lavage fluid occurred after a single exposure to 5 mg/m3 of the poorly maintained used machining fluid aerosols. Changes in inflammation but not LDH and protein were observed in animals repeatedly exposed to semi-synthetic machining fluid aerosols. A statistically significant increase in lavage fluid neutrophils was observed in guinea pigs exposed to 5 mg/m3 used, semi-synthetic machining fluid aerosols for 4 weeks. In separate experiments, physicochemical properties of unused machining fluids were found to contribute to the production of adverse effects. Adjustment of the alkaline and hypotonic nature of the unused semi-synthetic machining fluid to isotonicity and pH 7 significantly reduced adverse effects. Together, these findings strongly suggest that multiple factors contribute to the adverse respiratory effects associated with occupational exposure to machining fluid aerosols.
Pulmonary-system-disorders; Respiratory-system-disorders; Laboratory-animals; Inhalation-studies; Cutting-oils; Toxic-effects; Metalworking-fluids; Machine-shop-workers
New York University School of Medicine, Tuxedo 10987
New York University, New York, New York