Flame retardants are used to suppress combustibility of commonly used polymers. Some of these have been taken off the market due to environmental and health concerns. For others that have excellent toxicology profiles, there are concerns about the possibility that they could degrade in the environment to less-benign species. One of these is ethane bis(pentabromophenyl) (EBP), often referred to as decabromodiphenyl ethane (DBDPE). One of the causes of environmental degradation of organic materials, and an important consideration in life-cycle analysis, is photolysis (i.e., due to solar exposure). This can be either direct (photodegradation) or in conjunction with oxygen (photooxidation). Previous studies in dilute solvent systems do not reflect the actual use of EBP as a polymer additive. In this paper, we describe accelerated photolytic aging studies of EBP in polymer formulations that reflect actual product applications. These studies were done in high-impact polystyrene (HIPS) compounds which are typically used in electronic enclosures such as TVs, computers and office equipment. We find that the half-lives of the loss of one Br (from Br10 to Br9) extrapolate to 200+ years, orders of magnitude larger when compared to those in dilute systems. Another, perhaps more important, difference is that further photodegradation to Br8, or to lower brominated congeners of concern, was not observed. And we show that the low levels of photolytic degradation can be further suppressed using UV stabilizers. Our results can be contrasted with previous studies with decabromodiphenyl ether, often referred to as Decabrom. While somewhat structurally similar, Decabrom is significantly less stable to photodegradation and photooxidation in the solid state. Therefore, a simple read-across from Decabrom to EBP is not justified as even minor structural differences can significantly impact degradation processes.

Is Ethane Bis(pentabromophenyl) an environmental concern? Assessing the impact of photolytic degradation in plastics

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