BIOLOGICAL MONITORING OF OCCUPATIONAL EXPOSURE TO N-HEXANE BY EXHALEDAIR ANALYSIS AND URINALYSIS

To compare two methods of biological monitoring for the evaluation of risk of occupational exposure to n-hexane, we analyzed the relationshi p between environmental exposure to this solvent and urinary excretion of 2,5-hexanedione and n-hexane in exhaled air in 69 workers employed in the shoe industry. Environmental exposure to the solvent was monit ored with personal diffusive samplers, which were desorbed with carbon sulfide and analyzed by gas chromatography. To measure 2,5-hexanedion e, urine was subjected to acid hydrolysis, separation in octadecyl sil ane columns, elution with 5% aqueous acetonitrile solution and extract ion with dichloromethane, followed by gas chromatography. In exhaled a ir, n-hexane was measured with a sampling system that permitted concen tration of aliquots of end-exhaled air (alveolar air) from one or more exhalations in a tube packed with activated charcoal, which was then desorbed with carbon sulfide and analyzed by gas chromatography. Conce ntrations of n-hexane in breathing zone air were significantly correla ted with urinary concentrations of 2,5-hexanedione (r = 0.88) and with exhaled air n-hexane (r = 0.86); in addition, the two biological indi cators correlated significantly (r = 0.70). Analyses in both exhaled a ir and urine were thus considered useful for biological monitoring of the risk of exposure to n-hexane.