Determination of butoxyacetic acid and N-butoxyacetyl-glutamine in urine of lacquerers exposed to 2-butoxyethanol.

To determine the fraction of butoxyacetic acid (BAA) which is excreted as the amino acid conjugate N-butoxyacetylglutamine (BAA-GLN), urine samples of six lacquerers exposed to 2-butoxyethanol (BE) were collected before and after work and analysed using an HPLC-method which allows the simultaneous quantification of both BAA species. Whereas the pre-shift samples contained only little or no butoxyethanol-related material, concentrations of BAA and BAA-GLN amounted collectively to up to 7 mmol/l in the samples obtained at the end of work. The ratio BAA-GLN vs. total BAA ranged from 0.16 to 0.64 (mean value 0.48) indicating that a substantial fraction of BAA was eliminated as the amino acid conjugate. The results demonstrate that BAA-GLN is an important metabolite of BE in man. Procedures employed for the biological monitoring of exposure to BE should therefore include the quantification of BAA-GLN, otherwise exposure levels would be underestimated.