Evaluatingthe Bioaccessibility of Flame Retardantsin House Dust Using an In Vitro Tenax Bead-Assisted Sorptive PhysiologicallyBased Method

摘要

Exposure to house dust is a significant source of exposure to flame retardant chemicals (FRs), particularly in the US. Given the high exposure there is a need to understand the bioaccessibility of FRs from dust. In this study, Tenax beads (TA) encapsulated within a stainless steel insert were used as an adsorption sink to estimate the dynamic absorption of a suite of FRs commonly detected in indoor dust samples (n = 17), and from a few polyurethane foam samples for comparison. Organophosphate flame retardants (OPFRs) had the highest estimated bioaccessibility (∼80%) compared to brominated compounds (e.g., PBDEs), and values generally decreased with increasing Log Kow, with <30% bioaccessibility measured for BDE209. These measurements were in very close agreement with reported PBDE bioavailability measures from an in vivo rat exposure study using indoor dust. The bioaccessibility of very hydrophobic FRs (Log Kow > 6) in foam was much less than that in house dust, and increasing bioaccessibility was observed with decreasing particle size. In addition, we examined the stability of more labileFRs containing ester groups (e.g., OPFRs and 2-ethylhexyl-tetrabromo-benzoate(EH-TBB)) in a mock-digestive fluid matrix. No significant changesin the OPFR concentrations were observed in this fluid; however, EH-TBBwas found to readily hydrolyze to tetrabromobenzoic acid (TBBA) inthe intestinal fluid in the presence of lipases. In conclusion, ourstudy demonstrates that the bioaccessibility and stability of FRsfollowing ingestion varies by chemical and sample matrix and thusshould be considered in exposure assessments.