Antimony nickel titanium rutile

Long-term toxicity to fish

Administrative data

Endpoint:

fish early-life stage toxicity

Data waiving:

study technically not feasible

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
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 long-term toxicity to fish 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 28 days at a loading rate of 1 mg/L with the lowest chronic ecotoxicity reference values (ERVs) as determined for the (soluble) metal ions. The chronic ERVs are based on the lowest NOEC/EC10 values for algae, invertebrates and fish. ERVs were obtained from the Metals classification tool (MeClas) database as follows: The chronic ERVs of antimony (1.130 mg Sb/L) 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 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 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 an 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.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 chronic (long-term) aquatic hazard.

In accordance with Annex XI, Section 2 of Regulation (EC) 1907/2006, “Testing for a specific endpoint may be omitted, if it is technically not possible to conduct the study as a consequence of the properties of the substance”.

Antimony nickel titanium rutile is poorly soluble and unlikely to cross biological membranes. Hence, antimony nickel titanium rutile can be considered environmentally and biologically inert during aquatic exposure (please see above). For a highly insoluble substance such as antimony nickel titanium rutile, it may neither be possible nor relevant to try and conduct aquatic toxicity tests, as it is difficult to maintain a quantifiable and constant concentration of the substance in the environmental test medium. In accordance with the generic testing recommendations in the “Executive summary of the MISA 2 workshop (https://echa.europa.eu/misa)” for difficult to test substances, “The Water Accommodated Fraction (WAF) method (see REACH and OECD guidance on difficult to test substances), should not be used for metals. The reason is that this method often uses nominal loadings and lacks the pH and surface relationships necessary to estimate the potential hazard. Direct aquatic ecotoxicity testing of metals and SSMCs is in principle not recommended. However, if used or needed (e.g. for complex materials like UVCBs) then it should be conducted based on the dissolved fraction(s) of the T/D medium, at the appropriate pH (pH that dilutes the most).”

Since 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), it is neither technically possible in accordance with Annex XI, Section 2 of Regulation (EC) 1907/2006 nor scientifically justified to conduct any further aquatic toxicity study, including long-term toxicity to fish with antimony nickel titanium rutile. Long-term toxicity testing of fish is also not justifiable for the reasons of animal welfare.