Respiratory effects of a synthetic metalworking fluid and its components.

A synthetic metalworking fluid, MWF "A", and its major components were evaluated using a previously developed mouse bioassay. This fluid and its components evoked sensory (S) and pulmonary (P) irritation in mice. For MWF "A" and each of its components, a concentration-response relationship was developed on the basis of respiratory frequency (fR) responses. From such relationships, the concentration capable of evoking a 50% decrease in mean fR was determined for MWF "A" and each component (RD50). RD50S or RD50P was used to distinguish decreases in fR that were due to sensory irritation (S) from those due to pulmonary irritation (P). From RD50P values, it was concluded that the fatty acid alkanolamide condensates, tolutriazole, and triazine-type biocide components were similar in potency to one another and similar in potency to MWF "A". By examining potency and fractional composition, it was concluded that the fatty acid alkanolamide condensates and the triazine-type biocide largely contributed to the irritancy of MWF "A". From RD50P values, occupational exposure limits were proposed for MWF "A" and each of its components. The current Threshold Limit Value of 10 mg/m3 established by the American Conference of Governmental Industrial Hygienists for "particulates not otherwise classified" (PNOC) would be inadequate to protect workers from the irritating properties of MWF "A" and most of its components.