Occurrence, bioaccumulation, fate, and risk assessment of novel brominated flame retardants (NBFRs) in aquatic environments - A critical review

Novel brominated flame retardants (NBFRs), which have been developed as replacements for legacy flame retardants such as polybrominated diphenyl ethers (PBDEs), are a class of alternative flame retardants with emerging and widespread applications. The ubiquitous occurrence of NBFRs in the aquatic environments and the potential adverse effects on aquatic organisms have initiated intense global concerns. The present article, therefore, identifies and analyzes the current state of knowledge on the occurrence, bioaccumulation, fates, and environmental and health risks of NBFRs in aquatic environments. The key findings from this review are that (1) the distribution of NBFRs are source-dependent in the global aquatic environments, and several NBFRs have been reported at higher concentrations than that of the legacy flame retardants; (2) high bioaccumulative properties have been found for all of the discussed NBFRs due to their strong hydrophobic characteristics and weak metabolic rates; (3) the limited information available suggests that NBFRs are resistant to biotic and abiotic degradation processes and that sorption to sludge and sediments are the main fate of NBFRs in the aquatic environments; (4) the results of ecological risk assessments have indicated the potential risks of NBFRs and have suggested that source areas are the most vulnerable environmental compartments. Knowledge gaps and perspectives for future research regarding the monitoring, toxicokinetics, transformation processes, and development of ecological risk assessments of NBFRs in aquatic environments are proposed. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Novel brominated flame retardants (NBFRs) are emerging as alternative flame retardants to legacy compounds, with concerns raised over their presence, bioaccumulation, fate, and risks in aquatic environments. NBFRs show source-dependent distribution, high bioaccumulative properties, resistance to degradation processes, and sorption to sludge and sediments in aquatic environments. Ecological risk assessments have suggested potential risks of NBFRs primarily in source areas. Further research is needed to address knowledge gaps in monitoring, toxicokinetics, transformation processes, and ecological risk assessments of NBFRs in aquatic environments.