Cobalt aluminate blue spinel

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”.

Cobalt 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 (Pardo Martinez, 2013) that indicate a very low release of pigment components at pH 8, the pH that maximises dissolution. Transformation/dissolution tests at a loading of 1 mg/L and pH 8 resulted in dissolved cobalt concentrations that remained below the LOD (i.e. < 0.5 µg Co/L) during the 28-d test. Dissolved aluminium concentrations after 7 and 28 days amount to 1.9 and 2 µg Al/L, respectively. Thus, the rate and extent to which Cobalt aluminate blue spinel produces soluble (bio)available ionic and other aluminium-and cobalt-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 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 aluminate blue spinel. The poorly soluble substance Cobalt 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. Cobalt ion concentrations remained below the LOD (i.e. < 0.5 µg Co/L) after 7 days in the T/D test and are thus well below the respective ERV. Thus, only aluminium concentrations are taken into account. The dissolved aluminium concentration of 1.9 µg Al/L in the T/D test after 7 days at pH 8 is significantly lower than the lowest short-term ERV (1,040 µg Al/L and 3,390 µg Al/L at pH 6 and 8, respectively). Hence, the substance Cobalt 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 aluminate blue spinel is poorly soluble and does not meet classification criteria for acute (short-term) aquatic hazard.

Regarding the long-term toxicity, the poorly soluble substance Cobalt aluminate blue spinel is evaluated by comparing the dissolved metal ion levels resulting from the transformation/dissolution test after 28 days at a loading rate of 1 mg/L with the lowest chronic ecotoxicity reference values (ERVs) as determined for the (soluble) metal ions. The ERVs are based on the lowest EC10/NOEC values for algae, invertebrates and fish. In accordance with the Classification and Labelling Committee in 1999 (see report 013-003-00-7 submitted to the C&L Committee, 1999) a chronic ERV for dissolved aluminium ions has not been derived since a concern for long-term (chronic) toxicity of aluminium ions was not identified (no classification). Due to the lack of a chronic hazard potential for dissolved aluminium ions, only cobalt concentrations and the respective chronic ERV are taken into account. Respective chronic ERV was obtained from the Metals classification tool (MeClas) database and is 7.6 µg Co/L for cobalt. Since cobalt ion concentrations remained below the LOD (i.e. < 0.5 µg Co/L) during the 28-days test and are well below the respective chronic ecotoxicity ERV, there is not a concern for long-term (chronic) toxicity of cobalt ions. Hence, the substance Cobalt aluminate blue spinel is not sufficiently soluble to cause long-term toxicity at the level of the chronic ERV (expressed as NOEC/EC10).

In accordance with Figure IV.5 „Classification strategy for determining long-term 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 aluminate blue spinel is poorly soluble and also does not meet classification criteria for chronic (long-term) aquatic hazard.

Cobalt aluminate blue spinel 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.