LC₅₀ of zebrafish embryos exposed to actual concentrations (ppm) of (A) Lanthanide’s light REE and (B) Lanthanide’s heavy REE for 96 h. The 96 h LC50 values were calculated by using the sigmoid curve fitting method and the data are expressed as mean ± SEM.

Swimming activity of zebrafish after exposure to different Lanthanides. The mean ± SEM of (A,B) distance traveled, (C,D) burst movement, and (E,F) rotation counts per minute by zebrafish larvae after 24 h exposure of 1 ppm LREE and HREE during both light and dark cycles. A two-way ANOVA test with Geisser-Greenhouse’s correction continued with Dunnett’s multiple comparisons test was carried out to compare all treatments with the control (presented in Table S2).

The photo motor response (PMR) of zebrafish after 96 h exposure to 1 ppm of (A) light REE and (B) heavy REE. The data are expressed as mean ± SEM and statistical differences were analyzed by two-way ANOVA followed with Fisher’s LSD test (* p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001).

Correlations of properties of the Lanthanides complexes to the acute toxicity of fourteen Lanthanides. (A) The linear regression analysis showed a significant correlation between LC₅₀ and Lanthanide’s atomic numbers with r = 0.72. (B) A violin plot shows a statistical difference between the two LC₅₀ of LREE and HREE (p = 0.0111). (C) The linear regression analysis showed a significant correlation between LC₅₀ and Lanthanide’s Milliken charge with r = 0.70. (D) The linear regression analysis showed the most significant correlation between LC₅₀ and the aromatic C_avg charge with r = −0.85.

Summary of the covalency and ionicity property of the chelating bonds of Lanthanide (III) complexes.