Vanadium zirconium yellow baddeleyite

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance is highly insoluble in water, hence indicating that aquatic toxicity is unlikely to occur

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING

According to Annex VIII, Column 2, Section 9.1.4. of Regulation (EC) 1907/2006, the test for activated sludge respiration inhibition does not need to be conducted “if there are mitigating factors indicating that aquatic toxicity is unlikely to occur, for instance if the substance is highly insoluble in water”.

Vanadium zirconium yellow baddeleyite can be considered environmentally and biologically inert due to the characteristics of the synthetic process (calcination at a high temperature of approximately 1000°C), rendering the substance to be of a unique, stable crystalline structure in which all atoms are tightly bound and not prone to dissolution in environmental and physiological media. This assumption is supported by available transformation/dissolution data (Pardo Martinez, 2013) that indicate a very low release of pigment components and the lack thereof in environmental media at pH 8, the pH that maximises dissolution. Transformation/dissolution at a loading of 1 mg/L and pH 8 resulted in dissolved zirconium concentrations that remained below the LOD (i.e. < 0.5 microg/L during the 28-d test. Dissolved vanadium concentrations after 7 and 28 days amount to 3.1 and 2.8 microg/L, respectively. Thus, the rate and extent to which Vanadium zirconium yellow baddeleyite produces soluble (bio)available ionic and other vanadium- zirconium-bearing species in environmental media is limited. Hence, the pigment can be considered as environmentally and biologically inert during short- and long-term exposure. The poor solubility of Vanadium zirconium yellow baddeleyite is expected to determine its behaviour and fate in the environment, and subsequently its potential for ecotoxicity.

Proprietary studies are not available for Vanadium zirconium yellow baddeleyite. The poorly soluble substance Vanadium zirconium yellow baddeleyite is evaluated by comparing the dissolved metal ion levels resulting from the transformation/dissolution test after 7 d at a loading rate of 1 mg/L with the lowest acute ecotoxicity reference values (ERVs) as determined for the (soluble) metal ions. The ERVs are based on the lowest EC50/LC50 values for algae, invertebrates and fish. Since zirconium ion concentrations remained below the LOD during the T/D test and are well below respective ecotoxicity ERVs, only vanadium concentrations are taken into account. The dissolved vanadium concentration of 3.1 microg/L in the T/D test after 7 days at pH 8 (i.e. the pH that maximizes the dissolution) is significantly lower than the short-term ERV of 693 microg/L (Vanadium Consortium, 2020). Hence, the substance Vanadium zirconium yellow baddeleyite is not sufficiently soluble to cause short-term toxicity at the level of the acute ERVs (expressed as EC50/LC50).

In accordance with Figure IV.4 “Classification strategy for determining acute aquatic hazard for metal compounds” of ECHA Guidance on the Application of the CLP Criteria (Version 5.0, July 2017) and section 4.1.2.10.2. of Regulation (EC) No 1272/2008, the substance Vanadium zirconium yellow baddeleyite is poorly soluble and does not meet classification criteria for acute (short-term) aquatic hazard.

Vanadium zirconium yellow baddeleyite is poorly soluble. Based on the poor solubility and the corresponding lack of a toxic potential, inhibition of activated sludge respiration or toxicity to microorganisms is not expected. In accordance with Annex VIII, Column 2, Section 9.1.4. of Regulation (EC) 1907/2006, the test for activated sludge respiration inhibition is not necessary.

References:
Vanadium Consortium, 2020. Derivation of acute and chronic ecotoxicity reference values of vanadium for the REACH hazard assessment. Unpublished report.