Urinary Bromide and Breathing Zone Concentrations of 1-Bromopropane from Workers Exposed to Flexible Foam Spray Adhesives

Abstract

1-Bromopropane (1-BP) has been marketed as an alternative for ozone depleting solvents and suspect carcinogens and is in aerosol products, adhesives and solvents used for metal, precision and electronics cleaning. Toxicity of 1-BP is poorly understood, but it may be a neurologic, reproductive and hematologic toxin. Sparse exposure information prompted this exposure assessment study using air sampling, and measurement of urinary metabolites. Mercapturic acid conjugates are excreted in urine from 1-BP metabolism involving removal of bromide (Br) from the propyl group. One research objective was to evaluate the utility of urinary Br analysis for assessing 1-BP exposure using a relatively inexpensive, commercially available method. Complete 48 h urine specimens were obtained from 30 workers on two consecutive days at two facilities using 1-BP adhesives to construct polyurethane foam seat cushions and from seven unexposed control subjects. All of the workers' urine was collected into composite samples representing three daily time intervals (at work; after work but before bedtime; and upon wake-up) and analyzed for Br ion by inductively coupled plasma-mass spectrometry. Full-shift breathing zone samples were collected for 1-BP on Anasorb carbon molecular sieve sorbent tubes and analyzed by gas chromatography-flame ionization detection via NIOSH method 1025. Geometric mean (GM) breathing zone concentrations of 1-BP were 92 parts per million (p.p.m.) for adhesive sprayers and 11 p.p.m. for other jobs. For sprayers, urinary Br concentrations ranged from 77 to 542 milligrams per gram of creatinine [mg (g-cr)(-1)] at work; from 58 to 308 mg (g-cr)(-1) after work; and from 46 to 672 mg (g-cr)(-1) in wake-up samples. Pre-week urinary Br concentrations for sprayers were substantially higher than for the non-sprayers and controls, with GMs of 102, 31 and 3.8 mg (g-cr)(-1), respectively. An association of 48 h urinary Br concentration with 1-BP exposure was statistically significant (r(2) = 0.89) for all jobs combined. This study demonstrates that urinary elimination is an important excretion pathway for 1-BP metabolism, and Br may be a useful biomarker of exposure.