URINARY HEXANE DIAMINE AS AN INDICATOR OF OCCUPATIONAL EXPOSURE TO HEXAMETHYLENE DIISOCYANATE

The occupational exposure of 19 men to hexamethylene diisocyanate (HDI ) vapour was monitored during one 8-h shift. It ranged from 0.30 to 97 .7 mu g/m(3). This was compared with the urinary output of hexane diam ine (HDA) liberated by acid hydrolysis from its conjugates in post-shi ft samples. The excretion varied from 1.36 to 27.7 mu g/g creatinine, and there was a linear association of HDI air concentration with urina ry HDA excretion. The validity of the urinary analysis was confirmed b y simultaneous blind analysis in another laboratory. The results had a n excellent linear concordance. Thus, it seems that while the gas chro matographic-mass spectrometric detection method requires sophisticated apparatus, the results are very useful to occupational health practic es. A biological exposure index limit of 19 mu g HDA/g creatinine in a post-shift urine specimen is proposed as an occupational limit level of HDI monomer (time-weighted average = 75 mu g/m(3)). Most importantl y, biological monitoring of HDA is sensitive enough to be used at and below the current allowable exposure limit levels.