Polybrominated diphenyl ethers in bivalves: metabolites, accumulation, quantification and ecological risks

Polybrominated diphenyl ethers (PBDEs) are extensively used as flame retardants in plastics but have emerged as persistent environmental pollutants due to their bioaccumulation and toxicity. Analysis of 74 studies from 2000 to 2024 highlights the increasing research interest in PBDE contamination, particularly in aquatic ecosystems and bivalves. Recurring themes such as "health risk," "bioaccumulation," and "risk assessment" dominate the discourse, emphasizing the need for deeper investigations into PBDE pathways and impacts. This trend underscores the critical importance of evaluating PBDE contamination in seafood species like oysters, mussels and clams, which are integral to human diets and aquatic food chains. Building on these insights, this study focused on analyzing PBDEs and their metabolites (MeO-BDE, OH-BDE) in commonly consumed bivalve species. Advanced methods for extraction, purification and simultaneous analysis revealed significant variations in PBDE concentrations: oysters (29-101 ng/g lw), mussels (10-274.8 ng/g lw) and clams (23-64,900 ng/g lw). Notably, metabolites MeO-BDE and OH-BDE were frequently detected, sometimes surpassing PBDE levels, indicating complex bioaccumulation processes. Bioaccumulation and bio-sediment accumulation factors (BAF and BSAF) showed that PBDEs and their metabolites accumulate more effectively through water pathways than sediment. Trophic magnification factor (TMF) analysis further revealed higher TMF values for PBDEs compared to their metabolites, categorizing PBDEs and MeO-BDE as low-risk TMFs. These findings align with citation analysis trends, which emphasize "risk assessment" as a pivotal theme, particularly concerning human exposure. The human health risk assessment based on bivalve consumption highlights potential exposure concerns in regions with high seafood intake. This study not only enriches the understanding of PBDE distribution and bioaccumulation in bivalves but also emphasizes the importance of effective monitoring, regulatory control and continued investigation into their ecological and human health impacts.