Assessing Indoor Dust Interference with Human Nuclear Hormone Receptors in Cell-Based Luciferase Reporter Assays

BACKGROUND: Per- and polyfluoroalkyl substances (PFAS), organophosphate esters (OPEs), and polybrominated diphenyl ethers (PBDEs) are hormone-disrupting chemicals that migrate from building materials into air and dust.

OBJECTIVES: We aimed to quantify the hormonal activities of 46 dust samples and identify chemicals driving the observed activities. METHODS: We evaluated associations between hormonal activities of extracted dust in five cell-based luciferase reporter assays and dust concentrations of 42 measured PFAS, OPEs, and PBDEs, transformed as either raw or potency-weighted concentrations based on Tox21 high-throughput screening data.

RESULTS: All dust samples were hormonally active, showing antagonistic activity toward peroxisome proliferator-activated receptor (PPARc2) (100%; 46 of 46 samples), thyroid hormone receptor (TRb) (89%; 41 samples), and androgen receptor (AR) (87%; 40 samples); agonist activity on estrogen receptor (ERa) (96%; 44 samples); and binding competition with thyroxine (T4) on serum transporter transthyretin (TTR) (98%; 45 samples). Effects were observed with as little as 4 lg of extracted dust. In regression models for each chemical class, interquartile range increases in potencyweighted or unknown-potency chemical concentrations were associated with higher hormonal activities of dust extracts (potency-weighted: RPFAS–TRb, ” 28%, p< 0:05; ROPEs–TRb, ” 27%, p= 0:08; RPBDEs–TRb, ” 20%, p< 0:05; RPBDEs–ERa, ” 7:7%, p= 0:08; unknown-potency: ROPEs–TTR, ” 34%, p< 0:05; ROPEs–AR, ” 13%, p= 0:06), adjusted for chemicals with active, inactive, and unknown Tox21 designations.

DISCUSSION: All indoor dust samples exhibited hormonal activities, which were associated with PFAS, PBDE, and OPE levels. Reporter gene cellbased assays are relatively inexpensive,