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Case Study: Comparison of approaches for the exposure assessment of triphenyl phosphate, a semi-volatile flame retardant, used in an upholstered chair
Citation:
Bevington, C., C. Eichler, M. Babich, X. Liu, L. Krnavek, Y. Ahmad, AND D. Poppendieck. Case Study: Comparison of approaches for the exposure assessment of triphenyl phosphate, a semi-volatile flame retardant, used in an upholstered chair. ISES 2021 Virtual, NA, Online, August 30 - September 02, 2021.
Impact/Purpose:
Triphenyl phosphate (TPP, CAS#115-86-6) is one of the 20 priority chemicals under evaluation for EPA’s Toxic Substances Control Act. The experimental and modeling approaches to quantify emission, fate, and transport of SVOCs is important to understand their implications for subsequent human exposure to TPP. This investigation will highlight differences in experimental techniques and modeling assumptions for estimating emission and migration of TPP from an upholstered chair into the indoor environment. The case study will characterize the uncertainty and amount of evidence for each exposure pathway, and will provide recommendations for future SVOC exposure assessments.
Description:
Semi-volatile organic compounds (SVOCs), when compared to volatile organic compounds (VOCs), tend to emit more slowly and steadily, and to sorb to surfaces, suspended particulates and settled dust. Exposure assessments of SVOCs require both measured data and modeling approaches that quantify emission, fate and transport of SVOCs in the indoor environment. When experimental parameter data are not available for a chemical or product of interest, estimated parameters based on physical-chemical properties can be utilized. Triphenyl phosphate (TPP, CAS#115-86-6) is one of the 20 high-priority chemicals under evaluation for EPA’s Lautenberg Chemical Safety Act (amended Toxic Substances Control Act). It is a relatively well-studied SVOC and has sufficient experimental data for comparison of assessment approaches. This case study used existing experimental data and models for indoor exposure assessment of SVOCs to characterize exposures to TPP. It highlighted differences in experimental techniques and modeling assumptions for estimating emissions and migration of TPP from an upholstered chair into the indoor environment. Exposure pathways considered in this case study include dermal, inhalation, and oral. Dermal exposure occurs via direct skin contact with product while sitting. Inhalation exposure occurs via gaseous emissions and particulate formation from the product. Oral exposure can occur via hand-to-mouth, mouthing of product, and via ingestion of particulate (settled dust). To the extent possible, human exposure factors (i.e., inhalation rates, ingestion rates, and dermal surface area) as well as building characteristics (i.e., room size, air-exchange rates) were kept constant in the case study, so that differences in exposure estimates were attributed to experimental and modeling assumptions. The case study characterized the quality, certainty and uncertainty of measurements, estimates, and parameters and how these were integrated in each exposure pathway and provided recommendations for future SVOC exposure assessments.