Background: The environmental degradation of novel brominated flame retardants (BFRs) is largely unknown. Here, the photolytic degradation of the two novel BFRs, PolymericFR and Tetrabromobisphenol A-bis (2,3-dibrom-2-methyl-propyl) ether (TBBPA-BDBMPE), has been investigated by studying the chemical composition and ecotoxicological effects of their degradation mixtures. Furthermore, the stability of those mixtures during sample storage under different conditions has been examined.

Results: In the analytical characterization of the degradation mixtures, 14 previously identified degradation products and the sum formulas of six novel products of PolymericFR, as well as 22 sum formulas for previously unknown degradation products for TBBPA-BDBMPE, were detected in a suspect screening. The number of detected products increased with longer exposures to UV light and after the frozen storage of the samples. The freezing/thawing of the photolysis degradation mixtures led specifically to the detection of more polybrominated degradation products for both BFRs. The acute exposure of Desmodesmus subspicatus and Daphnia magna to the degradation mixtures did not affect the green algae but led to the immobility of the invertebrates at high concentrations. 

Conclusions: The results suggest that the effects of the degradation mixtures of PolymericFR and TBBPA-BDBMPE on daphnids increase with advancing photolysis. This highlights the importance of photolytic degradation processes for the hazard assessment of polymeric and monomeric brominated flame retardants. Additionally, the sample storage assessment results suggest that the degradation mixtures of brominated flame retardants should not be frozen for their storage, to avoid unintended changes in sample composition and ecotoxicological effects.