Formation of 1,3,8-tribromodibenzo-p-dioxin and 2,4,6,8-tetrabromodibenzofuran in the oxidation of synthetic hydroxylated polybrominated diphenyl ethers by iron and manganese oxides under dry conditions

Occurrence and formation pathways analysis of PBDD/Fs from 2,4,6-tribromophenol under thermal reaction conditions

Polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) are highly toxic and persistent compounds that provoke a wave of publicity. Bromophenols are important precursors for forming PBDD/Fs, and their reaction path has always been a research hotspot. In this study, the formation characteristic of PBDD/Fs from 2,4,6-TBP were studied. The yields of 2,3,7,8-substituted PBDD/Fs and 2,4,6,8-TBDF for the different thermal products ranged from 0.067 to 10.3 ng/g and 0.207-9.68 ng/g, respectively. The effects of adding Cu, Fe, and Sb₂O₃ were investigated and found to be more inclined to accelerate the formation of ortho-substituted PBDD/Fs than 2,3,7,8-PBDD/Fs. The formation pathways of 2,3,7,8-substituted PBDD/Fs and 2,4,6,8-TBDF were also proposed. 2,4,6,8-TBDF is generated in the C-C coupling reactions of some radical intermediates from the debromination of 2,4,6-TBP. The 2,3,7,8-PBDD/Fs are produced through more complex debromination, bromine substitution, and bromine rearrangement reactions. In addition, various catalytic effects on PBDD/F formation pathways were found, and the catalytic effect of Cu by the Ullmann reaction was the highest, while bromophenol oxidation by Fe was the highest. These results proved that both 2,3,7,8-substituted and non-2,3,7,8-substituted PBDD/Fs would be generated from 2,4,6-TBP, and the effects of the catalyst on the Br substituted position of 2,3,7,8-substituted PBDD/Fs were much lower than the Br-substituted position on bromophenol.

Oxidative Stress, Induced by Sub-Lethal Doses of BDE 209, Promotes Energy Management and Cell Cycle Modulation in the Marine Fish Cell Line SAF-1

The effects of sub-lethal doses of polybrominated diphenyl ether (PBDE)-209 in terms of toxicity, oxidative stress, and biomarkers were evaluated in the Sparus aurata fibroblast cell line (SAF-1). Vitality and oxidative stress status were studied after incubation with PBDE for 72 h. Concomitantly, the quantification of proteins related to cell cycle and DNA repair (p53), cell proliferation (extracellular signal–regulated kinase 1 (ERK1)), energetic restriction (hypoxia-inducible factor 1 (HIF1)), and redox status (Nuclear factor erythroid 2–related factor 2 (NRF2)) was also determined after prolonged exposure (7–15 days) by immunoblotting. Our results demonstrated that rising concentrations of PBDEs exposure-induced oxidative stress, and that this event modulates different cell pathways related to cell cycle, cell signaling, and energetic balance in the long term, indicating the negative impact of sub-lethal dose exposure to cell homeostasis.