Bioaccumulation, Biomagnification, and Potential Toxicity of Lithium-Ion Battery-Derived Cyclotriphosphazenes

Manufacturing of lithium-ion batteries (LIBs) has the potential to release cyclotriphosphazenes (CTPs) into the surrounding aquatic environment. However, the bioaccumulation and biomagnification potential of CTPs in fish species, as well as their associated toxicological impacts on aquatic organisms, remain insufficiently investigated. We examined water and fish samples collected near a lithium-ion battery (LIB) production facility for six CTPs, and assessed their effects on the locomotor activity of zebrafish larvae. All target CTPs were detected in collected water, with the dominance of phosphonitrilicchloridetrimer (HCCTP; mean 19 ± 9.6 ng/L), hexafluorocyclotriphosphazene (HFCTP; 14 ± 6.0 ng/L), and ethoxy (pentafluoro) cyclotriphosphazene (EPFCTP; 12 ± 6.7 ng/L). EPFCTP (3.4−47 ng/g ww) showed the highest mean levels in varying fish species, followed by HCCTP (3.0−39 ng/g ww) and HFCTP (2.6−20 ng/g ww). The mean log bioaccumulation factor values of HCCTP (2.2−3.2) across different fish species were comparable to that of EPFCTP (2.3−3.4) and HFCTP (2.0−2.9). Trophic magnification factor values of HFCTP, HCCTP, and EPFCTP were 2.5 (95% confidence interval, 1.5−3.6), 3.0 (2.2−4.2), and 3.2 (2.5−4.3), respectively. Exposure to target CTPs (excluding hexamethoxyphosphazene) resulted in a non-monotonic hyperactive locomotor response in 6 dpf zebrafish larvae at spiking concentrations of 1.0 ng/L−100 μg/L. To the best of our knowledge, this study first reports the bioaccumulation, biomagnification, and toxicological effects of CTPs in aquatic organisms. These findings are essential for elucidating the environmental fate and ecological risks posed by CTPs released during LIB manufacturing processes. • We detected six CTPs in surface water collected surrounding a LIB manufacturing park. • The mean log BAF values of HCCTP were comparable to that of EPFCTP in fishes. • TMF values of HFCTP, HCCTP, and EPFCTP were 2.5, 3.0, and 3.2, respectively. • CTPs lead to a hyperactive locomotor response in zebrafish larvae at 1.0−100 μg/L.