PREDICTION OF AN OCCUPATIONAL EXPOSURE LIMIT FORA MIXTURE ON THE BASIS OF ITS COMPONENTS - APPLICATION TO METALWORKING FLUIDS

Using a previously developed mouse bioassay, a semisynthetic metalwork ing fluid (MWF''B'') and its major components were evaluated. In mice MWF''B'' and its components produced both sensory (S) and pulmonary (P ) irritation. Using respiratory frequency (f) depression, concentratio n-response relationships were developed for each component as well as for MWF''B.'' From such relationships the concentration capable of evo king a 50% decrease in mean f was determined for each component and de signated as RD(50)S if the decrease in f was due to sensory irritation , or RD(50)P if the decrease in f was due to pulmonary irritation. Bas ed on RD(50)P values, the results indicated that the alkanolamides, po tassium soap, sodium sulfonate, and triazine components were similar i n irritation potency both to one another and to MWF''B.'' Through an e xamination of potency and fractional composition it was concluded that these five components largely contributed to the irritancy of MWF''B. '' From the RD(50)P values, occupational exposure limits that would pr otect workers from respiratory irritation were proposed for MWF''B'' a nd each of its components. Using the approach of the American Conferen ce of Governmental Industrial Hygienists for mixtures, an occupational exposure limit was calculated for MWF''B'' employing the component da ta. The two limits for MWF''B'' were similar to one another, suggestin g that exposure limits for MWFs may be obtained through the evaluation of the fluids themselves or through evaluation of the components.