Spinels, chromium iron manganese brown

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”.

Spinels, chromium iron manganese brown 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 6. Transformation/dissolution at a loading of 1 mg/L for 24 hours, 7 and 28 days resulted at pH 8 in dissolved chromium, iron and manganese concentrations below the LOD of 0.5 µg/L, respectively. At pH 6 and a loading of 1 mg/L for 24 hours, 7 and 28 days, dissolved iron and chromium concentrations remained also below the LOD of 0.5 µg/L whereas manganese concentrations remained below the LOQ of 1 µg/L. Due to the slightly higher release of manganese, pH 6 is considered the pH that maximises the metal release. Nevertheless, the rate and extent to which spinels, chromium iron manganese brown produces soluble (bio)available ionic and other chromium-, iron and manganese-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 spinels, chromium iron manganese brown is expected to determine its behaviour and fate in the environment, and subsequently its potential for ecotoxicity.

Proprietary studies are not available for spinels, chromium iron manganese brown. The poorly soluble substance spinels, chromium iron manganese brown 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 and NOEC/EC10 values for algae, invertebrates and fish, respectively. Acute and chronic ERVs were obtained from the Metals classification tool (MeClas) database as follows: The acute ERVs of trivalent chromium (> 100 mg Cr/L), iron (>100 mg Fe/L) and manganese (3.2 mg Mn/L) ions are above 1 mg/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 aquatic hazard potential for trivalent chromium, iron and manganese ions and the fact that dissolved chromium and iron concentrations remained below the LOD of 0.5 µg/L and manganese concentrations below the LOQ of 1 µg/L after 7 days at pH 6 and a loading of 1 mg/L in the T/D test, it can be concluded that the substance spinels, chromium iron manganese brown is not sufficiently soluble to cause short-term toxicity at the level of the acute ERVs (expressed as EC50/LC50).

Regarding long-term toxicity, the chronic ERVs of trivalent chromium and iron ions are also above 1 mg/L, respectively, 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.” The chronic ERV for manganese amounts to 550 µg Mn/L whereas dissolved manganese concentrations after 28-days T/D at pH remained below the LOQ of 1 µg/L. Due to the lack of a chronic aquatic hazard potential for trivalent chromium and iron ions and the fact that after 28 days T/D at pH 6 and a loading of 1 mg/L, dissolved chromium and iron concentrations remained below the LOD of 0.5 µg/L and dissolved manganese concentrations below the LOQ of 1 µg/L and well below the chronic ERV of 550 µg Mn/L, it can be concluded that the substance spinels, chromium iron manganese brown is not sufficiently soluble to cause long-term toxicity at the level of the chronic ERVs (expressed as 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 spinels, chromium iron manganese brown is poorly soluble and does not meet classification criteria for acute (short-term) and chronic (long-term) aquatic hazard.

Spinels, chromium iron manganese brown 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.