Chrome tin orchid cassiterite

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”.

Chrome tin orchid cassiterite 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 transformation/dissolution data (Klawonn, 2017) that indicate a very low release of pigment components at pH 6 and 8. Transformation/dissolution tests of Chrome tin orchid cassiterite at a loading of 1 mg/L and pH 6 resulted after 7 days in dissolved chromium concentrations below the LOQ of 0.028 µg Cr/L and tin concentrations of 0.463 µg Sn/L. After 28 days at pH 6 dissolved chromium concentrations amounted to 0.046 µg Cr/L, while tin concentrations amounted to 0.352 µg Sn/L. T/D tests at pH 8 resulted after 7 days in dissolved chromium and tin concentrations of 0.042 µg Cr/L and 2.873 µg Sn/L, respectively. After 28 days at pH 8 dissolved chromium and tin concentrations amounted to 0.052 µg Cr/L and 4.320 µg Sn/L, respectively. Thus, the rate and extent to which Chrome tin orchid cassiterite produces soluble (bio)available ionic and other chromium- and tin-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 Chrome tin orchid cassiterite is expected to determine its behaviour and fate in the environment, and subsequently its potential for ecotoxicity.

Proprietary studies are not available for Chrome tin orchid cassiterite. The poorly soluble substance Chrome tin orchid cassiterite 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 acute and chronic ERVs are based on the lowest EC50/LC50 or NOEC/EC10 values for algae, invertebrates and fish, respectively, and were obtained from the Metals classification tool (MeClas) database as follows: For trivalent chromium and tin ions, the acute ERVs are above 1 mg/L (>100 mg Cr3+/L; 9.8 mg Sn/L) and thus a concern for short-term (acute) toxicity was not identified (no classification). 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.” Due to the lack of an acute aquatic hazard potential of chromium and tin ions and the fact that the maximum quantified concentrations of chromium and tin after 7 days T/D tests at pH 6 and 8 (<=0.042 µg Cr/L and <=2.873 µg Sn/L at pH 8) remained well below the respective lowest acute ERVs, it can be concluded that the substance Chrome tin orchid cassiterite is not sufficiently soluble to cause short-term toxicity at the level of the acute ERVs (expressed as EC50/LC50).
Regarding the long-term toxicity, the chronic ERVs for trivalent chromium and tin ions, are above 1 mg/L and a concern for long-term (chronic) toxicity was not identified (no classification). According to ECHA Guidance on the Application of the CLP Criteria (Version 5.0, July 2017), ”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 a chronic aquatic hazard potential of chromium and tin ions and the fact that the maximum quantified concentrations of chromium and tin after 28 days T/D tests at pH 6 and 8 (<=0.052 µg Cr/L and <=4.320 µg Sn/L) remained well below the respective chronic ERVs, it can be concluded that the substance Chrome tin orchid cassiterite is not sufficiently soluble to cause long-term toxicity at the level of the chronic ERVs (expressed as NOEC/EC10).

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 Chrome tin orchid cassiterite is poorly soluble and does not meet classification criteria for acute (short-term) and chronic (long-term) aquatic hazard.

Chrome tin orchid cassiterite 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.