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EC number: 233-059-8 | CAS number: 10026-12-7
Short-term toxicity to aquatic invertebrates
Administrative data
Link to relevant study record(s)
Description of key information
For the conducted semi-static acute immobilization test with Daphnia magna, applying nominal concentrations of 889 to 4500 mg/L niobium pentachloride, nominal effect levels were calculated:
- 48 h EL50 (nominal): 1498 mg/L (95%-CI: 1286 – 1723 mg/L);
- 48h LOELR: 1333 mg/L;
- 48h NOELR: 889 mg/L.
Due to methodological difficulties, it was not possible to calculate effect concentrations based on measured concentrations. Hence, values are reported based on the nominal loading rates.
Key value for chemical safety assessment
Additional information
The 48-h acute toxicity of niobium pentachloride to Daphnia magna was studied under the conditions of OECD guideline 202 (semi-static conditions). Daphnids were exposed to a control containing no test substance and niobium pentachloride at nominal loading rates of 889, 1333, 2000, 3000 and 4500 mg/L for 48 h. Immobilization was observed daily. Due to highly variable Nb5+ concentrations in solution, effect concentrations were based on nominal loading rates.The 48-hour EL50 was 1498 mg/L. The 48-h NOELR based on immobilization was 889 mg/L and the LOELR was 1333 mg/L.This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates. However, it was not possible to determine effect levels based on measured effective test substance concentrations. After pH adjustment the measured Nb5+ concentrations were low and showed high variability. Therefore, no concentration-response relationship could be established. Concentrations of the test sample varied due to precipitation, agglomeration and adsorption reactions. In addition, slight changes in pH had profound impact on the test concentrations. Observed immobilization effects may therefore rather predominantly refer to elevated NaCl concentrations, originated from neutralization, than released Nb5+ ions. Reported EC50 values for sodium chloride vary but may be as low as 874 mg/L (ECHA registry for sodium chloride). Due to a concentration of approximately 4.68 g/L NaCl, present at the highest loading rate of 4500 mg/L test substance, and the sensitivity of D.magna to salinity, any hypothetical Nb5+ related effects cannot be distinguished from NaCl induced inhibition in the conducted test.
This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.
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