Halogenated organic pollutants in aquatic invertebrate – Fish food webs: Global distributions and trophic magnification

Persistent halogenated organic pollutants (HOPs) are globally concerned owing to their persistence, bioaccumulation, and potential toxicity to aquatic organisms. The trophic transfer of HOPs can affect their toxic effects on both humans and ecosystems. Previous studies mostly focused on HOPs biomagnification within specific regional or ecosystem contexts, however, the variation in trophic magnification factors (TMFs) among different HOPs across a spectrum of diverse aquatic systems globally remains unclear. By collating literatures encompassing TMFs of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), or perfluoroalkyl acids (PFAAs) along invertebrate–fish food webs on a global scale, our analysis revealed that Asia, North America, and Europe exhibited the highest pollution levels of HOPs. PCBs were found to have the highest trophic magnification capability (TMF = 3.14), followed by PBDEs (TMF = 2.48) and PFAAs (TMF = 1.97). TMF values and the probability of TMF exceeding 1 for PCB, PBDE and PFAA congeners showed a parabolic relationship with halogenation degree and carbon chain length. Specifically, PCBs with 6 chlorines, PBDEs with 5 bromines, and PFAAs with 12 carbons exhibited maximum trophic transfer capability and potential along food webs. Fractionation of PCBs and PFAAs was observed, with the proportions of higher chlorination degree and longer chain PFAAs increasing while the others decreased with trophic levels. Surprisingly, we also found a positive relationship between site latitude and TMF values of HOP congeners. This study provides a valuable basis for gauging ecological and health risks of HOPs, facilitating the development of robust standards for aquatic environment management.