Registration Dossier

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
other:
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING

High-temperature calcination products of diiron trioxide and amorphous silica resulting in a glassy silica matrix 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. Transformation/dissolution of High-temperature calcination products of diiron trioxide and amorphous silica resulting in a glassy silica matrix (24-screening test according to OECD Series 29, loading of 100 mg/L, pH 6 and 8) resulted in mean dissolved iron concentrations of 0.131 µg/L Fe and 0.002 µg/L Fe, silicon concentrations of 215.7 µg/L Si and 204 µg/L Si at pH 6 and 8, respectively. Dissolution of iron and silicon is highest at pH 6, therefore pH 6 is considered as pH that maximised metal release. Metal release at the 1 mg/L loading and pH 6 remained below the respective LOD for iron and silicon (<0.22 µg/L Fe and <0.07 µg/L Si). After 28 days at the 1 mg/L loading and pH 6 iron concentrations of 0.29 µg/L were measured whereas silicon concentrations remained below the LOD (< 0.07 µg/L Si). Thus, the rate and extent to which High-temperature calcination products of diiron trioxide and amorphous silica resulting in a glassy silica matrix produces soluble (bio)available ionic and other silicon- and iron-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 High-temperature calcination products of diiron trioxide and amorphous silica resulting in a glassy silica matrix is expected to determine its behaviour and fate in the environment, and subsequently its potential for ecotoxicity.

Proprietary studies are not available for High-temperature calcination products of diiron trioxide and amorphous silica resulting in a glassy silica matrix. The poorly soluble substance High-temperature calcination products of diiron trioxide and amorphous silica resulting in a glassy silica matrix is evaluated by comparing the dissolved metal ion levels resulting from the transformation/dissolution test after 7 and 28 days at a loading rate of 1 mg/L with the lowest acute and chronic ecotoxicity reference values (ERVs) as determined for the (soluble) metal ions. The ERVs are based on the lowest EC50/LC50 or NOEC/EC10 values for algae, invertebrates and fish. Acute and chronic ERVs were obtained from the Metals classification tool (MeClas) database as follows: For iron ions, the acute and chronic ERVs are above 1 mg/L, respectively, and a concern for short-term (acute) and long-term (chronic) toxicity was not identified (no classification). An acute as well as chronic ERV for silicon has not been derived since a concern for short-term (acute) and long-term (chronic) toxicity of silicon ions was not identified (see also OECD, 2004). According to ECHA Guidance on the Application of the CLP Criteria (Version 5.0, July 2017), “Where the acute ERV for the metal ions of concern is greater than 1 mg/l the metals need not be considered further in the classification scheme for acute hazard.” Further, ”Where the chronic ERV for the metal ions of concern corrected for the molecular weight of the compound (further called as chronic ERV compound) is greater than 1 mg/L, the metal compounds need not to be considered further in the classification scheme for long-term hazard.” Due to the lack of an acute and chronic aquatic hazard potential for soluble silicon and iron ions and the fact that dissolved silicon and iron concentrations were below the LOD (<0.22 Fe and <0.07 µg/L Si) after 7 days and below 0.5µg/L (0.29 Fe and <0.07 µg/L Si) after 28 days at pH 6 in the T/D test, respectively, it can be concluded that the substance High-temperature calcination products of diiron trioxide and amorphous silica resulting in a glassy silica matrix is not sufficiently soluble to cause short- or long-term toxicity at the level of the acute or chronic ERVs (expressed as EC50/LC50 or NOEC/EC10, respectively).

In accordance with Figure IV.4 “Classification strategy for determining acute aquatic hazard for metal compounds” and 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 High-temperature calcination products of diiron trioxide and amorphous silica resulting in a glassy silica matrix is poorly soluble and does not meet classification criteria for acute (short-term) and chronic (long-term) aquatic hazard.

High-temperature calcination products of diiron trioxide and amorphous silica resulting in a glassy silica matrix is poorly soluble and unlikely to cross biological membranes. In accordance with Annex VII, Column 2, Section 9.1.2. of Regulation (EC) 1907/2006, testing for growth inhibition of aquatic plants is not necessary.

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Applicant's summary and conclusion