UVA/B-Induced Formation of Free Radicals from Decabromodiphenyl Ether

Abstract

Polybrominated diphenyl ether (PBDE) flame retardants are ubiquitous in the environment and in humans. A decabromodiphenyl ether mixture (deca-BDE) is the dominating commercial PBDE product today. Deca-BDE is degraded by UV to PBDEs with fewer bromines. We hypothesized that photodegradation of deca-BDE results in the formation of free radicals. We employed electron paramagnetic resonance (EPR) with spin trap agents to examine the free radicals formed from UV irradiation of a deca-BDE mixture (DE-83R). The activating wavelength for deca-BDE photochemistry was in the UVA to UVB range. The yields of radicals from irradiated deca-BDE in tetrahydrofuran (THF), dimethylformamide (DMF), and toluene were about 9-, 4-, and 7-fold higher, respectively, than from irradiated solvent alone. Radical formation increased with deca-BDE concentration and irradiation time. The quantum yield of radical formation of the deca-BDE mixture was higher than with an octa-BDE mixture (DE-79; ~2-fold), decabromobiphenyl (PBB 209; ~2-fold), decachlorobiphenyl (PCB 209; ~3-fold), and diphenylether (DE; ~6-fold), indicating the positive effects of bromine and an ether bond on radical formation. Analysis of hyperfine splittings of the spin adducts suggests that radical formation is initiated or significantly enhanced by debromination paired with hydrogen abstraction from the solvents. To our knowledge this is the first report that uses EPR to demonstrate the formation of free radicals during the photolytic degradation of PBDEs. Our findings strongly suggest the potential of negative consequences due to radical formation during UV exposure of PBDEs in biological systems.

Effect of decabromodiphenyl ether (BDE 209) and dibromodiphenyl ether (BDE 15) on soil microbial activity and bacterial community composition

“…Our results implied that BDE 209 might have had a greater toxicity than BDE 15, which is consistent with the toxicity trends of PBDEs [8,26]. Although the concentration of BDE 209 remained constant throughout 120 days, there might be an effect of the BDE 209 on the enzymes.…”

Is decabromodiphenyl ether (BDE-209) a developmental neurotoxicant?

“…In the environment, BDE-209 has been shown to undergo photolytic debromination with the formation of nona- to tetraBDEs (Soderstrom et al 2004; Ahn et al 2006; Christiansson et al 2009). During such photodegradation of BDE-209, free radicals may be formed (Suh et al 2009). Microbial debromination has also been reported, with the formation of hepta- and octaBDEs (He et al 2006), and hexa- to nonaBDEs (Tokarz et al 2008).…”

Characterization of the molecular degradation mechanism of diphenyl ethers by Cupriavidus sp. WS

“…Nonbiological treatment technologies such as zerovalent iron Responsible editor: Gerald Thouand Electronic supplementary material The online version of this article (doi:10.1007/s11356-015-4854-3) contains supplementary material, which is available to authorized users. (Shih and Tai 2010), wet air co-oxidation ), and photochemical degradation (Shih and Wang 2009;Soderstrom et al 2004;Suh et al 2009;Xie et al 2009) have been studied for their ability to remove PBDEs. However, these techniques are of limited benefit in soil remediation due to incomplete degradation, costs, and low maneuverability.…”