Experimental human exposure to N,N-dimethylbenzylamine: generation of a controlled atmosphere and biological monitoring.

The aim of the present study was to develop a method for generation of dimethylbenzylamine (DMBA) atmospheres in an exposure chamber and to investigate the possibility of using urinary DMBA metabolites for biological monitoring of exposure to DMBA. A DMBA atmosphere was generated by use of the gas-permeation principle. Six health male volunteers were exposed for 8 h to DMBA at air levels of 20, 45, and 80 microns/m3. Air levels of DMBA were analyzed by gas chromatography (GC). The total urinary amount of DMBA (U-SumDMBA; DMBA and metabolites that can be reduced to DMBA, e.g., DMBAO) was analyzed using GC-mass spectrometry (MS). The exposure chamber maintained very low (0-130 micrograms/m3) and steady concentrations for several weeks. DMBA uptake by inhalation was 76%. The amine was quickly distributed and biotransformed to nearly 100%. DMBA was eliminated in the urine with a half-time of 4.3 h. More than 50% was eliminated within 2 h of exposure. However, at all exposure levels the subjects continued to excrete DMBA the next morning. There was a significant correlation between the exposure to DMBA and the U-SumDMBA. Thus, U-SumDMBA may become an important biomarker for monitoring of industrial exposure to DMBA.