Aniline in hydrolyzed urine and plasma--possible biomarkers for phenylisocyanate exposure.

There are few studies on phenylisocyanate (PhI) exposure, although there are studies indicating that PhI is a very potent chemical sensitizer. The aim of this study was to evaluate aniline in urine and plasma as possible biomarkers of exposure to PhI. Occupational airborne exposure to PhI was measured during one day for 11 workers exposed to thermal degradation products from polyurethane with filters impregnated with 2-methoxyphenyl piperazine. A urine sample was collected from each worker on measurement day, and plasma samples were collected within the following 2 weeks. Urine and plasma samples also were collected from four unexposed subjects. The biological samples were hydrolyzed and analyzed with gas chromatography mass spectrometry. The time-weighted averages (TWA) for the workers were between 0.1 and 1.6 microg/m3. Aniline levels in urine were in the same range for the exposed and unexposed workers, but there was a significant correlation between air and urinary levels (Pearson's correlation coefficient r = 0.518; p = 0.05). All exposed workers had higher levels in the plasma samples than the highest control, and there was a significant correlation between the plasma levels and measured air levels (r = 0.675; p = 0.008). The conclusion is that aniline in hydrolyzed urine and plasma are possible biomarkers of exposure to PhI, and that the plasma biomarker is more sensitive, at least at this rather low exposure.