Solvent levels were about five times higher in small enterprises as compared with the levels in large enterprises. There was a gradual shift in solvent use from aromatics to other solvents, typically alcohols. The use of hexane in adhesives was reduced. Solvent levels were relatively high in solvent-drying and printing workplaces and low in degreasing/cleaning/wiping workplaces and testing/research laboratories.

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In over-all evaluation, hippuric acid, followed by un-metabolized toluene and omicron-cresol, is the marker of choice for occupational toluene exposure. When toluene exposure level is low (e.g., 2 ppm), un-metabolized toluene and benzylmercapturic acid in urine may be better indicators. Detection of un-metabolized toluene or benzylmercapturic acid in urine at the levels in excess of the LODs may be taken as a positive evidence of toluene exposure, because their levels in urine from the controls are below the LODs. The value of benzyl alcohol as an exposure marker should be limited.

ICP-SF-MS is a reliable method of blood analysis for Cd, Mn and Pb even for the evaluation on an individual basis. Cr and Ni analyses should be reliable on a group basis, probably due to limited performance inherent to the analysis principle and matrix. Possible contamination from phlebotomy devices with Cr should be taken into account in evaluating the results.

No abstract