Exposure to organophosphate flame retardants in spray polyurethane foam applicators: Role of dermal exposure

Background: Spray polyurethane foam (SPF) is a highly effective thermal insulation material that has seen considerable market growth in the past decade. Organophosphate flame retardants (PFRs) are added to SPF formulations to meet fire code requirements. A common flame retardant used in SPF formulations is tris 1-chloro 2-propyl phosphate (TCIPP), a suspected endocrine disruptor. Exposure monitoring efforts during SPF applications have focused primarily on the isocyanate component, a potent respiratory and dermal sensitizer. However, to our knowledge, there is no monitoring data for TCIPP. Objective: To characterize occupational exposures to TCIPP and other flame retardants during SPF insulation. Methods: Workers at four SPF insulation sites and one foam removal site (total n = 14) were recruited as part of this pilot study. Personal inhalation exposure to TCIPP was monitored with a CIP-10MI inhalable sampler and potential dermal exposure was assessed through the use of a glove dosimeter. Biomarkers of TCIPP and three other PFRs were measured in urine collected from workers pre-and post-shift. Linear mixed effect models were used to analyze associations of urinary biomarkers with inhalation and dermal exposures and paired t-tests were used to examine the difference on the means of urinary biomarkers pre-and post-shift. Chemical analysis of all species was performed with liquid chromatography-electrospray ionization tandem mass spectrometry. Results: Geometric mean (GM) concentrations of TCIPP in personal air monitors and glove dosimeters collected from SPF applicators, 294.7 mu g/m(3) and 18.8 mg/pair respectively. Overall, GM concentrations of the two TCIPP urinary biomarkers BCIPP and BCIPHIPP and (6.2 and 88.8 mu g/mL) were 26-35 times higher than reported in the general population. Post-shift levels of TCIPP biomarkers were higher than pre-shift even though workers at insulation sites wore supplied air respirators, gloves and coveralls. The urinary biomarkers for the other PFRs were not elevated post shift. Concentrations of TCIPP on glove dosimeters were positively associated with post-shift urinary TCIPP biomarkers (p < 0.05) whereas concentrations in personal air samples were not. Conclusions: High levels of urinary biomarkers for TCIPP among SPF applicators, including post-shift, points to absorption of TCIPP during the work shift, in spite of the use of best industry exposure control practices. Dermal exposure appears to be an important, if not the primary exposure pathway for TCIPP, although inhalation or incidental ingestion of foam particles post-SPF application cannot be ruled out in this pilot study.