Photochemical and microbial transformation of emerging flame retardants: Cause for concern?

Abstract

Among anthropogenic chemicals, flame retardants have attracted mounting environmental concerns. In recent years, an increasing number of studies have been conducted worldwide to investigate flame-retardant sources, environmental distribution, wildlife and human exposure, and toxicity. Data generated have demonstrated that some flame-retardant substances such as polybrominated diphenyl ethers (PBDE) are persistent, bioaccumulative, and toxic to exposed organisms. However, comparatively much less attention has been paid to the mechanisms and products of environmental transformation of flame retardants. This lack of information undermines our understanding of the environmental behavior and fate of flame retardants, as well as the associated risks to environmental and human health. Photochemical and microbial transformation of flame retardants in various matrices and environmental compartments can elevate the toxicological significance of flame retardant exposure, via the formation of, for example, lesser halogenated but more bioaccumulative degradation products and toxic radicals. Such pathways raise concerns related to the environmental safety of some alternative flame retardants that are presumably safe and used to replace PBDEs. To fully assess the environmental risks, more research is needed to investigate the environmental transformation potential of emerging flame retardants including polymeric flame retardants. Enhanced analytical efforts are needed to better characterize transformation products and transient radicals. Additional mesocosm and field studies are needed to elucidate transformation kinetics and consequences under environmentally relevant conditions.

Degradation of the Polymeric Brominated Flame Retardant “Polymeric FR” by Heat and UV Exposure

“…Typically, the toxicity of a BFR is evaluated without considering degradation products, even though it was shown that the degradation of a BFR can alter its toxic potential. − Especially for polymeric BFRs, which are claimed to be more environmental friendly, degradation products should be considered. In a previous study dealing with “Polymeric FR”, possible structures of such products were listed.…”

The photodegradation of polybrominated diphenyl ethers (PBDEs) in various environmental matrices: Kinetics and mechanisms

“…Available reviews about PBDEs in the literature focus on the analytical methods applicable in various media (water, dust, soil, sediment, polymers, biological samples and food) [36][37][38][39], their regional environmental occurrence (especially in European countries, the USA, China and Japan) [40][41][42][43], human exposure through inhalation and ingestion [44][45][46][47], biotic and abiotic transformation in the environment [48], and the degradation technologies of PBDEs in liquid systems [49]. However, the photochemical behavior of PBDEs in different natural and artificial media under various environmental conditions still has not been critically evaluated and compared.…”

Mechanistic Aspects Regarding the Ultraviolet Degradation of Polychlorinated Biphenyls in Different Media: Insights from Carbon and Chlorine Isotope Fractionation

“…Light-induced transformation is an important natural attenuation of persistent organic pollutants (POPs) . A typical type of POP, polychlorinated biphenyls (PCBs), was previously used extensively as a hydraulic and dielectric fluid for transformers and capacitors .…”

“…Light-induced transformation is an important natural attenuation of persistent organic pollutants (POPs). 1 A typical type of POP, polychlorinated biphenyls (PCBs), was previously used extensively as a hydraulic and dielectric fluid for transformers and capacitors. 2 Although the production and use of PCBs were forbidden 50 years ago, existing equipment that contains PCBs is allowed to be used until 2025.…”