Probabilistic trophic magnification analysis for assessing the bioaccumulation potential of organophosphate flame retardants in freshwater ecosystems of South Korea.

Despite considerable efforts in recent years to quantify the trophic magnification factor (TMF) of organophosphate flame retardants (OPFRs), definitive conclusions regarding their biomagnification potential have not yet been reached. This study hypothesizes that sampling uncertainty may affect TMF calculations. To overcome the limitations of traditional regression-based methods (TMF_R), we applied a Monte Carlo simulation-based probabilistic method (TMF_M), which provides more reliable estimates of OPFR bioaccumulation in freshwater ecosystems. The concentrations of tributyl phosphate (TNBP), tris(2-chloroethyl) phosphate (TCEP), and tris(2-chloroisopropyl) phosphate (TCIPP) were analyzed in relation to the amino acid stable isotope-based trophic position in fish from four major rivers in Korea. The TMF_M values were 1.2 ± 0.3, 1.4 ± 0.9, and 2.0 ± 1.9 for TNBP, TCEP, and TCIPP, respectively, with TCIPP exhibiting a relatively higher biomagnification potential, consistent with previous findings. In contrast, the TMF_R produced extreme values (e.g., 17.8 for TCIPP), whereas TMF_M moderated by approximately 50 %, reducing spatial and temporal variability. A meta-analysis of literature data further supported the TMF_M estimates, revealing that 80 % of TMFs ranged between 0 and 2, while higher values were observed for top predators and specific ecosystems. These results advance the understanding of OPFR bioaccumulation by improving TMF estimation accuracy and highlight the need for ongoing monitoring and mechanistic studies. The probabilistic approach presented here offers a valuable tool for environmental risk assessment and supports informed chemical management.