Bromide and N-acetyl-S-(n-propyl)-l-cysteine in urine from workers exposed to 1-bromopropane solvents from vapor degreasing or adhesive manufacturing
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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.
Keywords1-Bromopropane CAS No. 106-94-5 Vapor degreasing Urine Bromide N-acetyl-S-(n-propyl)-l-cysteine
This study was funded by an interagency agreement between the National Toxicology Program (NTP), National Institute of Environmental Health Sciences (NIEHS), and the National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention (CDC). This study was approved by and was conducted in accordance with review of the CDC-NIOSH Human Subjects Review Board (01-DSHEFS-05-XP), and the workers provided their voluntary written consent prior to their participation in the study. The authors would like to acknowledge Belinda Johnson; Kevin Dunn; Brian Curwin (NIOSH); Jason Potter; Jason Forbes; and Justin Byrd (IHI Environmental, Inc.) for field assistance; Kate Marlowe (NIOSH) for laboratory assistance; DataChem Laboratories for analytical services; Wayne Sanderson PhD (University of Iowa) for consultation and protocol review; and Elizabeth Whelan, PhD; Cheryl Estill, MS, PE; Mark Toraason, PhD; Scott Dotson, PhD (NIOSH); Jeffrey Nemhauser, MD (NCEH, CDC) for manuscript review prior to submission to the journal. The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of neither NIOSH nor NTP-NIEHS. This manuscript has not been formally disseminated by NIOSH or NTP-NIEHS, and it does not represent and should not be construed to represent any agency determination or policy. Mention of any company name or product does not constitute endorsement by NIOSH or NTP-NIEHS.
Conflict of interest statement
The authors declare that they have no conflict of interest. This study was partially funded by a US government interagency agreement NTP-NIEHS:NIOSH Y1-ES-9045.
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