Table 2.
Toxicity of (doped) rare earth oxide particles and soluble metal salts to protozoa Tetrahymena thermophila and bacteria Vibrio fischeri. The rare earth elements (REEs) in REOs are indicated in bold letters. The average EC50 a values with their 95% confidence intervals (in the brackets) are presented. N indicates the number of repetitive experiments performed to obtain the average value. For MBC b values, the representative value is presented (i.e., the value obtained in majority of experiments).
| Compound | Toxicity Endpoint | ||
|---|---|---|---|
| 24-h Decrease of Viability, % | 30-min Inhibition of Luminescence, % | Ability to Yield Colonies on Agar Plates after 24-h Exposure to Chemical | |
| Protozoa T. thermophila | Bacteria V. fischeri | Bacteria V. fischeri | |
| (Doped) rare earth oxides | EC50 a, mg compound/L | MBC b, mg compound/L | |
| Ce0.9Gd0.1O2 | >100; N = 2 | >500; N = 2 | >500; N = 2 |
| LaFeO3 | >100; N = 2 | >500; N = 2 | >500; N = 2 |
| Gd0.97CoO3 | >100; N = 2 | >500; N = 2 | >500; N = 2 |
| LaCoO3 | >100; N = 2 | >500; N = 2 | >500; N = 2 |
| (La0.5Sr0.5)0.99MnO3 | >100; N = 2 | >500; N = 2 | >500; N = 2 |
| CeO2 | >100; N = 2 | >500; N = 2 | >500; N = 2 |
| Ce0.8Pr0.2O2 | >100; N = 2 | >500; N = 2 | >500; N = 2 |
| (La0.6Sr0.4)0.95CoO3 | >100; N = 2 | >500; N = 2 | >500; N = 2 |
| La2NiO4 | >100; N = 2 | >500; N = 2 | 25; N = 4 |
| Rare earth elements | EC50, mg metal/L | MBC, mg metal/L | |
| Ce(NO3)3·6H2O | 41.7 (38.3–46.5); N = 3 | 6.70 (5. 81–8.48); N = 5 | 12.5; N = 3 |
| Gd(NO3)3·6H2O | 28.4 (27.3–30.6); N = 3 | 3.53 (3.38–3.76); N = 5 | 6.25; N = 3 |
| La(NO3)3·6H2O | 41.9 (38.0–47.2); N = 3 | 20.93 (17.07–25.94), N = 5 | 62.5; N = 4 |
| Nd(NO3)3·6H2O | 29.8 (29.5–31.2); N = 2 | 6.87 (6.66–8.57); N = 3 | 15.6; N = 4 |
| Pr(NO3)3·6H2O | 30.8 (26.6–35.8); N = 2 | 12.17 (11.08–14.82); N = 3 | 12.5; N = 4 |
| Dopant metals | EC50, mg metal/L | MBC, mg metal/L | |
| Fe(NO3)3·9H2O | 4.9 (4.4–5.3); N = 3 | 0.44 (0.40–0.46); N = 6 | 1.25; N = 4 |
| Co(NO3)2·6H2O | >100; N = 4 | 462 (404–564); N = 5 | 62.5; N = 5 |
| Mn(NO3)2·6H2O | 82.0 (76.9–90.4); N = 4 | >500; N = 5 | >500; N = 3 |
| Ni(NO3)2·6H2O | 2.7 (2.6–2.9); N = 3 | >500; N = 5 | 1.25; N = 5 |
| Sr(NO3)2 | >100; N = 2 | >500; N = 5 | >500; N = 3 |
a EC50—half-effective concentration; b MBC—minimal bactericidal concentration.