Monitoring of occupational exposure to cyclohexanone by diffusive samplingand urinalysis

The present study was initiated in order to identify the best marker of occ upational exposure to cyclohexanone among cyclohexanone and its metabolites in urine. To examine if diffusive samplers are applicable to personal moni toring of exposure to cyclohexanone in workroom air, the performance of car bon cloth to adsorb cyclohexanone in air was studied by experimental exposu re of the cloth to cyclohexanone at 5, 10, 25 or 50 ppm (i.e. 20, 40, 100 o r 200 mg m(-3)) for up to 8 h. Cyclohexanone in the exposed cloth was extra cted with carbon disulphide followed by gas chromatographic (GC) analysis. The cloth adsorbed cyclohexanone in proportion to the concentration (up to 50 ppm) and the duration (up to 8 h), and responded quantitatively to a 15 min exposure at 100 ppm. In a field survey end-of-shift urine samples were collected from 24 factory workers occupationally exposed to cyclohexanone ( up to 9 ppm) in combination with toluene and other solvents. Urine samples were also collected from 10 subjects with no occupational exposure to solve nts. The urine samples were treated with acid or an enzyme preparation for hydrolysis, and extracted with dichloromethane or ethyl acetate, The extrac ts were analysed by GC for cyclohexanone, cyclohexanol, and trans- and cis- isomers of 1,2- and 1,1-cyclohexanediol. Both cyclohexanol and trans-1,2-cy clohexanediol in urine correlated significantly with time-weighted average intensity of exposure to cyclohexanone. Although trans-1,4-isomer was also excreted, its quantitative relation with cyclohexanone exposure could not b e established, because the solvent extraction rate was low and unstable. Ex cretion of cis-isomers was not confirmed. The two analytes, cyclohexanol an d trans-1,2-cyclohexanediol, appeared to be equally valid as exposure marke rs, but the latter may be superior to the former in the sense that it is se nsitive enough to separate the exposed from the non-exposed at 1 ppm or les s cyclohexanone exposure.