Comparative evaluation of urinalysis and blood analysis as means of detecting exposure to organic solvents at low concentrations

One hundred and forty-three workers exposed to one or more of toluene, xylene, ethylbenzene, styrene, n-hexane, and methanol at sub-occupational exposure limits were examined for the time-weighted average intensity of exposure by diffusive sampling, and for biological exposure indicators by means of analysis of shift-end blood for the solvent and analysis of shift-end urine for the corresponding metabolite(s). Urinalysis was also performed in 20 nonexposed control men to establish the "background level." Both solvent concentrations in blood and metabolite concentrations in urine correlated significantly with solvent concentrations in air. Comparison of blood analysis and urinalysis as regards sensitivity in identifying low solvent exposure showed that blood analysis is generally superior to urinalysis. It was also noted that estimation of exposure intensity on an individual basis is scarcely possible even with blood analysis. Solvent concentration in whole blood was the same as that in serum in the case of the aromatics, except for styrene. It was higher in blood than in serum in the case of n-hexane, and lower in the cases of styrene and methanol.