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Endpoint:
toxicity to soil microorganisms
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
other:
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING
According to Column 2 of Information Requirement 9.4., Annex IX, Commission Regulation (EU) 1907/2006 ”These studies do not need to be conducted if direct and indirect exposure of the soil compartment is unlikely. In the absence of toxicity data for soil organisms, the equilibrium partitioning method may be applied to assess the hazard to soil organisms. Where the equilibrium partitioning method is applied to nanoforms, this shall be scientifically justified. The choice of the appropriate tests depends on the outcome of the chemical safety assessment. In particular for substances that have a high potential to adsorb to soil or that are very persistent, the registrant shall consider long-term toxicity testing instead of short-term.”

According to Section 8.4.2 of ECHA Guidance on IR & CSA, Part B: Hazard assessment (Version 2.1; ECHA, 2011), “For substances which are classified as harmful, toxic or very toxic to aquatic life (i.e. H412, H411, H410 and H400), an aquatic PNEC can be derived. In these circumstances there are unclassified hazards to the sediment and soil compartments because toxicity to aquatic organisms is used as an indicator of concern for sediment and soil organisms, and a screening risk characterisation is undertaken using the equilibration partitioning method (EPM) to derive PNECs for sediment and soil. Hence quantitative exposure assessment, i.e. derivation of PECs, is mandatory for the water, sediment and soil environmental compartments.

Substances with the only environmental classification as ‘May cause long lasting harmful effects to aquatic life’ (i.e. H413) have been established as persistent in the aquatic environment and potentially bioaccumulative on the basis of test or other data. There are also potential hazards for these substances for the sediment and soil compartments, because these substances are potentially bioaccumulative in all organisms and are also potentially persistent in sediment and soil. Hence exposure assessment is mandatory for the water, sediment and soil environmental compartments, which may be quantitative or qualitative as appropriate. PBT and vPvB substances have been established as persistent and bioaccumulative (and the former also as toxic) in the environment as a whole. Hence qualitative exposure assessment is mandatory for the water, sediment and soil environmental compartments…

If there are ecotoxicity data showing effects in aquatic organisms, but the substance is not classified as dangerous for the aquatic environment, an aquatic PNEC can nevertheless be derived thus indicating a hazard to the aquatic environment. In these circumstances there are also unclassified hazards to the sediment and soil compartments because toxicity to aquatic organisms is used as an indicator of concern for sediment and soil organisms and a screening risk characterisation is undertaken using the equilibration partitioning method (EPM) to derive PNECs for sediment and soil. Hence quantitative exposure assessment, i.e. derivation of PECs, is mandatory for the water, sediment and soil environmental compartments.”

Chrome antimony titanium buff rutile 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 (Klawonn, 2017) that indicate a very low release of pigment components. Transformation/dissolution tests of chrome antimony titanium buff rutile for 24 h at a loading of 100 mg/L (24 h-screening test according to OECD Series 29) resulted in mean dissolved antimony concentrations of 1.859 and 2.139 µg Sb/L and dissolved chromium concentrations of 0.029 and 0.192 µg Cr/L at pH 6 and 8, respectively. 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 is greater than 1 mg/L, the metals need not be considered further in the classification scheme”. Accordingly, titanium was not considered in the T/D assessment since it does not have an ecotoxic potential as confirmed by ecotoxicity reference values of > 100 mg Ti/L listed in the Metals classification tool (MeClas) database. The release of antimony and chromium from chrome antimony titanium buff rutile in aqueous media is highest at pH 8 and thus pH 8 is considered as pH that maximises dissolution. Metal release at the 1 mg/L loading and pH 8 resulted in dissolved antimony and chromium concentrations of 0.766 µg Sb/L and 0.071 µg Cr/L after 7 days and 1.027 µg Sb/L and 0.050 µg Cr/L after 28 days, respectively. Thus, the rate and extent to which chrome antimony titanium buff rutile produces soluble (bio)available ionic and other antimony- or chromium-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 antimony titanium buff rutile is expected to determine its behaviour and fate in the environment, and subsequently its potential for ecotoxicity.

Proprietary studies investigating the effects on soil microorganisms are not available for chrome antimony titanium buff rutile. The poorly soluble substance chrome antimony titanium buff rutile 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. Acute and chronic ERVs are based on the lowest EC50/LC50 and NOEC/EC10 values for algae, invertebrates and fish, respectively. The ERVs were obtained from the Metals classification tool (MeClas) database as follows: The acute ERVs of antimony (12.1 mg Sb/L, ECHA disseminated database), trivalent chromium (> 100 mg Cr/L) and titanium (> 100 mg Ti/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.” Furthermore, the metal release in the T/D test at 1 mg/L loading and pH 8, the pH that maximises dissolution, resulted in dissolved antimony and chromium concentrations of 0.766 µg Sb/L and 0.071 µg Cr/L after 7 days, respectively. Due to the metal release in the T/D test after 7 days at pH 8 with 1 mg/L loading and the lack of an aquatic hazard potential for antimony, chromium and titanium ions, it can be concluded that the substance chrome antimony titanium buff rutile 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 of antimony (1.130 mg Sb/L), trivalent chromium and titanium (> 100 mg Ti/L) 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 is greater than 1 mg/L, the metal compounds need not to be considered further in the classification scheme for long-term hazard.” Furthermore, the metal release in the T/D test at 1 mg/L loading and pH 8, the pH that maximises dissolution, resulted in dissolved antimony and chromium concentrations of 1.027 µg Sb/L and 0.050 µg Cr/L after 28 days, respectively. Due to the metal release in the T/D test after 28 days at pH 8 with 1 mg/L loading and the lack of an aquatic hazard potential for antimony, chromium and titanium ions, it can be concluded that the substance chrome antimony titanium buff rutile 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 antimony titanium buff rutile is poorly soluble and does not meet classification criteria for acute (short-term) and chronic (long-term) aquatic hazard.

Chrome antimony titanium buff rutile is not classified as dangerous for the aquatic environment, an aquatic PNEC cannot be derived, thus not indicating a hazard to the aquatic environment. In these circumstances there are also no unclassified hazards to the soil compartment because toxicity to aquatic organisms is used as an indicator of concern for soil organisms and a screening risk characterisation (using the equilibrium partitioning method to derive a PNEC for soil) cannot be undertaken. Thus, chrome antimony titanium buff rutile does not have a “non-classified hazard” potential.

Antimony is a chalcophile element with a low crustal abundance of 0.5 mg Sb/kg. Antimony is largely immobile due to the tendency of antimony ions to form insoluble salts and to be adsorbed by Fe, Al and Mn oxides at pH levels in the range 4.0 - 8.0. Antimony is enriched in the soil surface horizon due to chelation with organic matter, but also in the B-horizon as a result of the strong adsorption by Fe, Al and Mn oxides and clay minerals (Salminen et al. 2005 and references therein).

Chromium is ubiquitous in soil and a constituent of several rock forming minerals. According to the EU RAR on chromates (ECB, 2005), “Chromium (III) has generally been shown to be less toxic than chromium (VI) to soil organisms…Since chromium (III) adsorbs more strongly onto soil than chromium (VI), it would again be expected that in soils, chromium (III) would be less toxic than chromium (VI)”.

Titanium is a common lithophile metallic element with a crustal abundance of 6,320 mg/kg. Titanium ions have very low mobility under almost all environmental conditions, mainly due to the high stability of the insoluble oxide TiO2 under all but the most acidic conditions, i.e., below pH 2. Titanium minerals are resistant to weathering, they occur practically undecomposed in soil. Titanium ions are mobilised more readily in peats and podzols, at low pH (< 4.5) and in the presence of organic acids (Salminen et al. 2005 and references therein).

Monitoring data for elemental antimony, chromium and titanium background concentrations in soil are provided by the FOREGS Geochemical Baseline Mapping Programme that offers high quality, multi-purpose homogeneous environmental geochemical baseline data for Europe (Salminen et al. 2005). The FOREGS dataset for EU-27 countries plus UK and Norway reports metal concentrations for 827 (Sb), 825 (Cr) and 833 (Ti) topsoil samples. Baseline antimony levels in topsoil range from 0.02 to 31.1 mg Sb/kg with 5th, 50th and 95th percentiles of 0.1, 0.6 and 3.1 mg Sb/kg, respectively. Baseline chromium levels in topsoil range from 1.0 to 2,340.0 mg Cr/kg with 5th, 50th and 95th percentiles of 5.0, 22.0 and 69.8 mg Cr/kg, respectively. Baseline titanium levels in topsoil range from 125.9 to 32,652.2 mg Ti/kg with 5th, 50th and 95th percentiles of 1,068.0, 3,428.2 and 6,650.3 mg Ti/kg, respectively. Taking into account the high quality and representativeness of the data set, the 95th percentile of 3.1 mg Sb/kg, 69.8 mg Cr/kg and 6,650.3 mg Ti/kg can be regarded as representative background concentration of antimony, chromium and titanium in topsoil of EU countries.

Additionally, antimony, chromium and titanium concentrations in soils were determined in the GEMAS project (Geochemical Mapping of Agricultural and Grazing land Soil), that offers high quality harmonized, freely and interoperable geochemical data for the top layer of agricultural and grazing land soil (Reimann et al. 2014). For the EU-27, UK and Norway, 1,867 and 1,781 samples of agricultural and grazing land soil were analysed. Antimony levels of agricultural soil range from < 0.02 (< LOQ) to 17.1 mg Sb/kg with 5th, 50th and 95th percentiles of 0.05, 0.2 and 1.0 mg Sb/kg, respectively. In grazing land, soil concentrations of antimony range from < 0.02 (< LOQ) to 24.6 mg Sb/kg with 5th, 50th and 95th percentiles of 0.06, 0.3 and 1.2 mg Sb/kg, respectively. Chromium levels of agricultural soil range from 0.40 to 696.02 mg Cr/kg with 5th, 50th and 95th percentiles of 4.16, 19.87 and 67.16 mg Cr/kg, respectively. In grazing land, soil concentrations of chromium range from 0.78 to 576.74 mg Cr/kg with 5th, 50th and 95th percentiles of 3.87, 19.75 and 67.82 mg Cr/kg, respectively. Titanium levels of agricultural soil range from < 5.0 (< LOQ) to 7,860.1 mg Ti/kg with 5th, 50th and 95th percentiles of 16.9, 96.4 and 1,006.8 mg Ti/kg, respectively. In grazing land, soil concentrations of titanium range from < 5.0 (< LOQ) to 10,420.8 mg Ti/kg with 5th, 50th and 95th percentiles of 15.4, 77.7 and 910.5 mg Ti/kg, respectively. Representative antimony, chromium and titanium concentrations (95th percentile) of agricultural land soil (i.e. ambient levels) amount to 1.0 mg Sb/kg, 67.2 mg Cr/kg and 1,006.8 mg Ti/kg, respectively. Representative antimony, chromium and titanium concentrations (95th percentile) of grazing land soil amount to 1.2 mg Sb/kg, 67.8 mg Cr/kg and 910.5 mg Ti/kg, respectively.

Regarding the essentiality of pigment components, antimony and titanium are non-essential elements without a known biological function in living organisms (Goyer et al, 2004; Salminen et al. 2005 and references therein; WHO, 1982). “Chromium (III) is required by only some microorganisms for specific metabolic processes, such as glucose metabolism and enzyme stimulation. Chromium (III), in trace amounts, has been reported to be an essential component of animal nutrition and is most notably associated with glucose and fat metabolism (WHO, 2009).”

Antimony, chromium and titanium are abundant in soil environments and soil organisms are well adapted to it. The addition of anthropogenic antimony, chromium and titanium in a poorly soluble form to soil is not expected to be relevant for respective total and bioavailable soil concentrations and toxicity. Thus, additional soil testing is not expected to provide any further insights.

Chrome antimony titanium buff rutile is not classified as harmful, toxic or very toxic to aquatic life or may cause long lasting harmful effects to aquatic life. Chrome antimony titanium buff rutile is also not an unclassified hazard to the aquatic environment. Based on the poor solubility, bioavailability, lack of a potential for bioaccumulation and toxicity to aquatic organisms and considering ubiquitousness of antimony, chromium and titanium in soil, chrome antimony titanium buff rutile is also not considered an unclassified hazard to the soil compartment. Results of the chemical safety assessment do not indicate the need to investigate further the effects of chrome antimony titanium buff rutile on soil organisms. Therefore, studies on effects on soil microorganisms do not need to be conducted in accordance with Column 2 of Information Requirement 9.4.2., Annex IX, Commission Regulation (EU) 1907/2006.

References:

ECB (2005) European Union Risk Assessment Report: Chromium trioxide, sodium chromate, sodium dichromate, ammonium dichromate and potassium dichromate. EUR 21508 EN.

Goyer R et al (2004) Issue paper on the human health effects of metals. Submitted to U.S. Environmental Protection Agency, 19.08.2004.

Reimann et al. (2014) Chemistry of Europe’s agricultural soils - Part A: Methodology and interpretation of the GEMAS data set.

Salminen et al. (2005) Geochemical Atlas of Europe - Part 1: Background information, Methodology and Maps. EuroGeoSurveys.

WHO (1982) Environmental Health Criteria 24 – Titanium. International Programme on Chemical Safety.

WHO (2009) Concise International Chemical Assessment Document 76 (CICAD). Inorganic chromium (III) compounds. International Programme of Chemical Safety (IPCS), WHO, Geneva.
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Reason / purpose for cross-reference:
data waiving: supporting information

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Materials and methods

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Applicant's summary and conclusion