Cobalt zinc aluminate blue spinel

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

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

the study does not need to be conducted because the substance is unlikely to cross biological membranes, hence indicating that aquatic toxicity is unlikely to occur

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
According to Annex VII, Column 2, Section 9.1.1. of Regulation (EC) 1907/2006, the test for short-term toxicity on invertebrates 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 or the substance is unlikely to cross biological membranes”.

Cobalt zinc aluminate blue spinel 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 (Grané, 2010) that indicate a very low release of pigment components at pH 6, the pH that maximises dissolution. Transformation/dissolution tests at a loading of 1 mg/L and pH 6 resulted in dissolved cobalt and zinc concentrations that remained below the LOD (i.e. < 0.11 µg Co/L and < 0.07 µg Zn/L, respectively) during the 28-d test. Dissolved aluminium concentrations after 7 and 28 days amount to 48.75 and 23.48 µg Al/L, respectively. Thus, the rate and extent to which Cobalt zinc aluminate blue spinel produces soluble (bio)available ionic and other aluminium-, cobalt- and zinc-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 Cobalt zinc aluminate blue spinel is expected to determine its behaviour and fate in the environment, and subsequently its potential for ecotoxicity.

Proprietary studies are not available for Cobalt zinc aluminate blue spinel. The poorly soluble substance Cobalt zinc aluminate blue spinel 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. Acute ERVs were obtained from the Metals classification tool (MeClas) database as follows: Acute ERVs for aluminium are 1,040 µg Al/L at pH 6 and 3,390 µg Al/L at pH 8. The acute ERV for cobalt is 52.0 µg Co/L, and for zinc the acute ERVs are 413 µg Zn/L at pH 6 and 136 µg Zn/L at pH 8. Cobalt and zinc ion concentrations remained below the LOD (i.e. < 0.11 µg Co/L and < 0.07 µg Zn/L, respectively) after 7 days in the T/D test and are thus well below respective ERVs. Thus, only aluminium concentrations are taken into account. The dissolved aluminium concentration of 48.75 µg Al/L in the T/D test after 7 days at pH 6 is significantly lower than the lowest short-term ERVs (1,040 µg Al/L and 3,390 µg Al/L at pH 6 and 8, respectively). Hence, the substance Cobalt zinc aluminate blue spinel 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 Cobalt zinc aluminate blue spinel is poorly soluble and does not meet classification criteria for acute (short-term) aquatic hazard.

Cobalt zinc aluminate blue spinel is poorly soluble and unlikely to cross biological membranes. In accordance with Annex VII, Column 2, Section 9.1.1. of Regulation (EC) 1907/2006, testing for short-term toxicity to invertebrates is not necessary.