Bioaccessibility of PBDEs present in indoor dust: A novel dialysis membrane method with a Tenax TA® absorption sink

Human uptake of flame retardants (FRs) such as polybrominated diphenyl ethers (PBDEs) via indoor dust ingestion is commonly considered as 100% bioaccessible, leading to potential risk overestimation. Here, we present a novel in vitro colon-extended physiologically-based extraction test (CE-PBET) with Tenax TA (R) as an absorptive sink capable to enhance PBDE gut bioaccessibility. A cellulose-based dialysis membrane (MW cut-off 3.5 kDa) with high pH and temperature tolerance was used to encapsulate Tenax TA (R), facilitating efficient physical separation between the absorbent and the dust, while minimizing re-absorption of the ingested PBDEs to the dust particles. As a proof of concept, PBDE-spiked indoor dust samples (n - 3) were tested under four different conditions; without any Tenax TA (R) addition (control) and with three different Tenax TA (R) loadings (i.e. 0.25, 0.5 or 0.75 g). Our results show that in order to maintain a constant sorptive gradient for the low MW PBDEs, 0.5 g of Tenax TA (R) are required in CE- PBET. Tenax TA (R) inclusion (0.5 g) resulted in 40% gut bioaccessibility for BDE153 and BDE183, whereas greater bioaccessibility values were seen for less hydrophobic PBDEs such as BDE28 and BDE47 (similar to 60%). When tested using SRM 2585 (n = 3), our new Tenax TA (R) method did not present any statistically significant effect (p > 0.05) between non-spiked and PBDE-spiked SRM 2585 treatments. Our study describes an efficient method where due to the sophisticated design, Tenax TA (R) recovery and subsequent bioaccessibility determination can be simply and reliably achieved. (C) 2017 Elsevier B.V. All rights reserved.