Antimony nickel titanium rutile

Sediment toxicity

Administrative data

Endpoint:

sediment toxicity: long-term

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 9.5.1, Annex X, Commission Regulation (EU) 1907/2006 ” Long-term toxicity testing shall be proposed by the registrant if the results of the chemical safety assessment indicates the need to investigate further the effects of the substance and/or relevant degradation products on sediment organisms. The choice of the appropriate test(s) depends on the results of the chemical safety assessment.”

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.”

Antimony nickel titanium 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 antimony nickel titanium 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 1.893 and 1.607 µg Sb/L and dissolved nickel concentrations of 24.949 and 16.407 µg Ni/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 nickel from antimony nickel titanium rutile in aqueous media is highest at pH 6 and thus pH 6 is considered as pH that maximises dissolution. Metal release at the 1 mg/L loading and pH 6 resulted in dissolved antimony and nickel concentrations of 1.610 µg Sb/L and 0.598 µg Ni/L after 7 days and 1.851 µg Sb/L and 0.480 µg Ni/L after 28 days, respectively. Thus, the rate and extent to which antimony nickel titanium rutile produces soluble (bio)available ionic and other antimony- or nickel-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 antimony nickel titanium rutile is expected to determine its behaviour and fate in the environment, and subsequently its potential for ecotoxicity.

Proprietary studies investigating toxicity to sediment organisms are not available for antimony nickel titanium rutile. The poorly soluble substance antimony nickel titanium 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. 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 antimony (12.1 mg Sb/L, ECHA disseminated database) 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.” The acute ERVs for nickel at pH 6 and pH 8 are 286 µg Ni/L and 146 µg Ni/L, respectively, and are thus well above the dissolved nickel concentration of 0.598 µg Ni/L, measured after 7 days T/D test at a loading of 1 mg/L and pH 6, the pH that maximises dissolution. Due to the lack of an acute aquatic hazard potential for soluble antimony and titanium ions and the fact that the dissolved nickel concentration measured in the T/D test after 7 days at pH 6 (pH that maximises dissolution) is significantly lower than the short-term ERVs for nickel, it can be concluded that the substance antimony nickel titanium 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) and titanium (> 100 mg Ti/L) ions are above 1 mg/L, and thus 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 metals need not to be considered further in the classification scheme for long-term hazard.” The chronic ERVs for nickel at pH 6 and pH 8 are 23 µg Ni/L and 6 µg Ni/L, respectively, and are thus well above the dissolved nickel concentration of 0.480 µg Ni/L, measured after 28 days T/D test at a loading of 1 mg/L and pH 6, the pH that maximises dissolution. Due to the lack of a chronic aquatic hazard potential for soluble antimony and titanium ions and the fact that the dissolved nickel concentration measured in the T/D test after 28 days at pH 6 (pH that maximises dissolution) is significantly lower than the long-term ERVs for nickel, it can be concluded that the substance antimony nickel titanium 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 antimony nickel titanium rutile is poorly soluble and does not meet classification criteria for acute (short-term) and chronic (long-term) aquatic hazard.

Antimony nickel titanium 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 sediment compartment because toxicity to aquatic organisms is used as an indicator of concern for sediment organisms and a screening risk characterisation (using the equilibrium partitioning method to derive a PNEC for sediment) cannot be undertaken. Thus, antimony nickel titanium rutile does not have a “non-classified hazard” potential.

In stream sediments, antimony ions are present primarily in detrital sulphide minerals, e.g., stibnite, sphalerite and galena, some of which may weather relatively rapidly under acid, oxidising conditions. Further remobilisation of antimony is rather limited due to the tendency of antimony ions to form insoluble basic salts and be adsorbed by secondary hydrous oxides of Fe, Al and Mn at pH levels in the range 4.0 - 8.0 (Salminen et al. 2005 and references therein).

In stream sediment, a large proportion of nickel is held in detrital silicate and oxide minerals that are resistant to weathering. Limited dissolution of nickel ions may occur at low pH, but its mobility is generally restricted by its tendency to be sorbed by clay minerals or hydrous Fe and Mn oxides (Salminen et al. 2005 and references therein).

Titanium exists only in a fully hydrated form, TiO(OH)2, in water above pH 2, and is therefore transported in a colloidal state rather than as a dissolved ion. A large proportion of titanium in stream sediments is held in minerals, such as rutile, ilmenite and sphene, all of which are relatively insoluble (Salminen et al. 2005 and references therein).

Monitoring data for antimony, nickel and titanium background concentrations in stream water sediments are provided by the FOREGS Geochemical Baseline Mapping Programme, which offers high quality, multi-purpose homogeneous environmental geochemical baseline data for Europe.

A total of 735 (Sb), 737 (Ni) and 739 (Ti) stream sediment samples were processed in the FOREGS-program for the EU-27, UK and Norway to determine representative concentrations. In stream sediments, antimony concentrations range from < 0.02 (< LOQ) to 34.1 mg Sb/kg with 5th, 50th and 95th percentiles of 0.2, 0.6 and 2.9 mg Sb/kg, respectively. Nickel sediment concentrations range from 3.0 to 1,201.0 mg Ni/kg with 5th, 50th and 95th percentiles of 4.0, 16.0 and 59.2 mg Ni/kg and titanium concentrations range from 95.9 to 29,919.2 mg Ti/kg with 5th, 50th and 95th percentiles of 1,354.5, 3,871.8 and 8,067.2 mg Ti/kg, respectively.

Taking into account the high quality and representativeness of the FOREGS data set, the 95th percentiles of 2.9 mg Sb/kg, 59.2 mg Ni/kg, and 8,067.2 mg Ti/kg sediment can be considered as representative background concentration of antimony, nickel and titanium in European stream sediments.

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). Due to the existing importance of nickel in the catalytic activity of certain plant and bacterial enzymes, the WHO (1991) concludes that “Nickel has been shown to be essential for the nutrition of many microorganisms, a variety of plants, and for some vertebrates.”

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

Antimony nickel titanium rutile is not classified as harmful, toxic or very toxic to aquatic life or may cause long lasting harmful effects to aquatic life. Antimony nickel titanium 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 and bioavailability of antimony, nickel and titanium in sediment as well as essentiality and low bioaccumulation of antimony, nickel and titanium, antimony nickel titanium rutile is also not considered an unclassified hazard to the sediment compartment. Results of the chemical safety assessment do not indicate the need to investigate further the effects of antimony nickel titanium rutile on sediment organisms. Therefore, studies on the long-term toxicity to sediment organisms do not need to be conducted in accordance with Column 2 of Information Requirement 9.5.1., Annex X, Commission Regulation (EU) 1907/2006.

References:

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

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 (1991) Environmental Health Criteria 108 – Nickel. International Programme on Chemical Safety.

Cross-reference

Reason / purpose for cross-reference:

data waiving: supporting information