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Ecotoxicological information

Toxicity to soil microorganisms

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toxicity to soil microorganisms
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No toxicity test with soil microorganisms is available for niobium (CAS 7440-03-1).


Aquatic long-term tests with algae, aquatic invertebrates and aquatic microorganisms are available for niobium. Following effect values were determined: Aquatic algae revealed an EC10 (72 h) of 16.1 mg/L (nominal, OECD 201) for Raphidocelis subcapitata, aquatic invertebrates showed a NOEC (21 d) of ≥ 10 mg/L (nominal, OECD 211) for Daphnia magna, and aquatic microorganisms showed a NOEC (3 h) of ≥ 1000 mg/L (nominal, OECD 209) for activated sludge microorganisms. The observed effects on algae are considered to be caused by physical effects due to the presence of particles in the test medium and not by the intrinsic toxicity of the test item. Thus, the available acute and chronic ecotoxicity data show that, niobium (CAS 7440-03-1) is not acutely and chronically toxic to freshwater organisms.

This assumption will be reevaluated, based on the results of the ongoing long-term tests with fish (OECD 210; CCH-D-2114517391-56-01/F). Reasons for the delay are summarized in the statements attached in IUCLID section 6.1.2 (‘Status of Fish early life stage toxicity Tests (OECD 210) with Niobium metal powder’ (Sept. 2022) and Status of Aquatic Toxicity Tests (OECD 201, 210 and 211) with Niobium metal powder (May 2022).


Considering the available aquatic toxicity results, especially the results of the aquatic microorganisms tests (NOEC (3 h) of ≥ 1000 mg/L (nominal, OECD 209)), it is not expected that niobium (CAS 7440-03-1) shows long-term effects to soil microorganisms.


For assessing this assumption, a soil toxicity long-term test will be conducted. Since aquatic algae were the most sensitive organisms group upon the tested aquatic organisms, a terrestrial long-term test according to OECD Guideline 208 (Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test) will be conducted. This test will be performed after a decision on the requirement to carry out the proposed test has been taken according to the procedure laid down in Regulation (EC) 1907/2006 and a deadline to submit the information required has been set by the Agency.

The choice of the terrestrial tests will be reevaluated, based on the results of the ongoing long-term tests with fish (OECD 210).


Furthermore, as explained above it is expected that niobium (CAS 7440-03-1) does not show long-term effects to soil organisms, including terrestrial microorganisms and this assumption will be assessed by conducting a soil toxicity long-term test according to OECD 208. Therefore, no further terrestrial toxicity test with microorganisms is required.