Tetradecabromo-1,4-diphenoxybenzene (TeDB-DiPhOBz) and 2,2′,3,3′,4,4′,5,5′,6,6′-decabromodiphenyl ether (BDE-209) are flame retardant chemicals that can undergo photolytic degradation. The present study compared the time-dependent photolyic degradation of TeDB-DiPhOBz and BDE-209, and dioxin-like product formation as a result of (UV) irradiation (I; irradiation time periods of 0, 1, 4, 15 and 40 days). Photo-degraded product fractions of UV-I-TeDB-DiPhOBz (nominal concentration: 1.9 μM) were administered to chicken embryonic hepatocytes (CEH), and significant induction of CYP1A4/5 mRNA expression was observed for fractions collected at the day 15 and 40 time points (fold change of 7.3/3.6 and 9.1/4.7, respectively). For the UV-I-BDE-209 fractions (nominal concentration: 10 μM), significant CYP1A4/5 up-regulation occurred at all time points, and the fraction collected on day 1 induced the greatest fold change of 510/86, followed by 410/68 (day 4) and 110/26 (day 15), respectively. For the UV-I-BDE-209 fraction collected at day 40, significant CEH cytotoxicity was observed. As a result, CYP1A4/5 expression was determined at a nominal concentration of 1 μM instead of 10 μM and CYP1A4/5 fold changes of 11/8.2 (day 40) were observed. Fractions eliciting the greatest CYP1A4/5 mRNA upregulation were further screened for transcriptomic effects using a PCR array comprising 27 dioxin-responsive genes. A total of 6 and 16 of the 27 target genes were up or down-regulated following UV-I-TeDB-DiPhOBz and UV-I-BDE-209 exposure, respectively. Overall, and regardless of the formation rate, these results raise concerns regarding the potential formation of dioxin-like compounds from flame retardants in products and materials such as plastics, and in natural sunlight irradiation situations in the environment (e.g. in landfill sites or electronic waste facilities).

Additional Metadata
Keywords Brominated flame retardants, Chicken embryonic hepatocytes, Cytotoxicity, mRNA expression, Photolytic degradation, Time course
Persistent URL dx.doi.org/10.1016/j.chemosphere.2017.11.153
Journal Chemosphere
Citation
Su, G. (Guanyong), Letcher, R.J, Farmahin, R. (Reza), & Crump, D. (Doug). (2018). Photolysis of highly brominated flame retardants leads to time-dependent dioxin-responsive mRNA expression in chicken embryonic hepatocytes. Chemosphere, 194, 352–359. doi:10.1016/j.chemosphere.2017.11.153