Bromide and N-acetyl-S-(n-propyl)-l-cysteine in urine from workers exposed to 1-bromopropane solvents from vapor degreasing or adhesive manufacturing

Abstract

1-Bromopropane (1-BP) is an alternative for ozone depleting and other solvents; it is used in aerosol products, adhesives, and cleaning solvents. There is concern that 1-BP may be a reproductive and neurological toxicant. Mercapturic acid conjugates are excreted in urine from 1-BP metabolism involving debromination. The main objectives were to evaluate urinary bromide [Br(-)] and N-acetyl-S-(n-propyl)-L-cysteine (AcPrCys) for assessing 1-BP exposure in workers with low exposure. Workers' 1-BP exposures were measured in their breathing zones with gas chromatography-flame ionization detection via NIOSH 1025. Urine specimens were obtained over a 48-h period at five facilities using vapor degreasers and one adhesive manufacturer. All of the workers' urine was collected into composite samples and analyzed separately representing daily time intervals: at work, after work but before bedtime, and upon awakening. Urinary metabolites were analyzed using intra-coupled plasma-mass spectroscopy for Br(-), and high-performance liquid chromatography and electro-spray ionization mass spectroscopy for AcPrCys. Time-weighted average (TWA) geometric mean (GM) breathing zone concentrations of 1-BP at vapor degreasing facilities were 2.6 and 0.31 ppm, respectively, for workers near degreasers and those remote from degreasers. Urine metabolites showed the same trend as TWA exposures: higher levels were observed for workers near degreasers (48-h GM Br(-) = 8.9 vs. 3.7; 48-h GM AcPrCys = 1.3 vs. 0.12, respectively). Associations of Br(-) and AcPrCys concentrations with 1-BP TWA were statistically significant near degreasers (p < 0.01). This study shows that urinary Br(-) and AcPrCys are useful biomarkers of workers' 1-BP exposures using analyses sensitive enough to measure low exposure jobs.