Thyroid hormone-disrupting activity and ecological risk assessment of phosphorus-containing flame retardants by in vitro, in vivo and in silico approaches

• Published in: Environmental pollution (1987) Vol. 210; pp. 27 - 33
• Main Authors: Zhang, Quan, Ji, Chenyang, Yin, Xiaohui, Yan, Lu, Lu, Meiya, Zhao, Meirong
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-03-2016
• Subjects: Animals; CHO Cells; Computer Simulation; Cricetulus; Ecological risks; Ecology; Environment; Flame Retardants - analysis; Flame Retardants - toxicity; Humans; Molecular Docking Simulation; Organophosphates - chemistry; Organophosphates - toxicity; Phosphorus-containing flame retardants; Rats; Reporter gene assay; Risk Assessment; Thyroid Hormone Receptors beta - antagonists & inhibitors; Thyroid hormone-disrupting effects; Xenopus; Xenopus tropicalis; Reporter gene assay; Phosphorus-containing flame retardants; Thyroid hormone-disrupting effects; Ecological risks
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2015.11.051

In recent years, phosphorus-containing flame retardants (PFRs) have been frequently detected in various environmental media and biota - and in humans - as the result of steady increase in global usage of PFRs. However, studies on the potential health and ecological risks of PFRs are still scarce. In this study, we investigated the thyroid hormone-disrupting activity and ecological risk of nine frequently detected PFRs by in vitro, in vivo and in silico approaches. Results from the dual-luciferase reporter gene assay showed that tributyl phosphate (TNBP), tricresyl phosphate (TMPP), tris(2-chloroisopropyl)phosphate (TCIPP) and tris(2-chloro-1-(chloromethyl)ethyl)phosphate (TDCIPP) exerted thyroid receptor β (TRβ) antagonistic activity, with the values of RIC20 of 5.2 × 10−7, 2.7 × 10−7, 1.2 × 10−6 and 6.8 × 10−6 M, respectively. Molecular docking platform simulations suggested that the observed effects may be attributed to direct binding of PFRs to TR. Results from the T-screen assay indicated that TNBP and TMPP showed T3 antagonistic activity and thus significantly decreased the viability of GH3 cell lines in the presence of T3. The exposure assay using Xenopus tropicalis embryos revealed the potential teratogenic effect of TNBP, TMPP, TCIPP and TDCIPP. In conclusion, our studies revealed that some PFRs were potential thyroid hormone disruptors and may cause health and ecological risks. However, the mode of action of PFRs on TR remains uncertain. The correlation between the predicted affinity and the amplitude of the effect observed in cell based assay is encouraging, but not decisive. Further in vitro binding experiments of TR and PFRs are required. At the same time, the results provided here also demonstrated that multi-model approaches are of great importance to comprehensively evaluate the potential risks of emerging contaminants.
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•Four PFRs exerted thyroid receptor β antagonistic activity.•TNBP and TMPP significantly decreased the viability of GH3 cell lines with T3.•Four PFRs possessed the potential teratogenic effect on Xenopus tropicalis embryos.
Four PFRs exerted thyroid receptor β antagonistic activity.