Zinc ferrite brown spinel

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

no hazard identified

Marine water

Hazard assessment conclusion:

no hazard identified

STP

Hazard assessment conclusion:

no hazard identified

Sediment (freshwater)

Hazard assessment conclusion:

no hazard identified

Sediment (marine water)

Hazard assessment conclusion:

no hazard identified

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

no hazard identified

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Conclusion on classification

Data available on the short-term toxicity of different iron (hydr)oxides, including micro- and nano-sized iron hydroxide oxide yellow, diiron trioxide, triiron tetraoxide, zinc ferrite brown spinel and manganese ferrite black spinel, to fish (Danio rerio), invertebrates (Daphnia magna) and algae (Pseudokirchneriella subcapitata) indicate a low potential for acute toxicity. Respective unbounded EC/LC50 values amount for fish up to > 100 g/L, a concentration that is 1000-fold above the corresponding OECD test limit for acute toxicity, for invertebrates up to > 10 g/L, a concentration that is 100-fold above the corresponding OECD test limit for acute toxicity and > 20 mg/L for algae, and are thus all above classification criteria for acute (short-term) aquatic hazard according to Table 4.1.0 (a) of Regulation (EC) No 1272/2008.

 

Furthermore, chronic toxicity data of diiron trioxide in nanoform indicate a low potential for aquatic toxicity since NOECs available for three trophic levels (algae, invertebrates, fish) are ≥ 10 mg/L, and thus above the corresponding OECD test limit of 10 mg/L for chronic toxicity and above classification criteria for chronic (long-term) aquatic hazard according to Table 4.1.0 (b) of Regulation (EC) No 1272/2008. 

 

Further, soluble iron salts are not considered toxic to the aquatic life, i.e. do not meet CLP classification criteria for Acute (short-term) aquatic hazard and Long-term aquatic hazard. The acute and chronic ecotoxicity reference values (ERVs) for iron (ions) are above the respective CLP classification criteria of 1 mg/L as confirmed by the absence of ecotoxicity reference values for iron (ions) in the Metals classification tool (MeClas) database (Version 5.9 accessed on 22.11.2021).

 

“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 (ECHA, 2017, Section IV.5.2.1 Classification strategy for determining acute aquatic hazard for metals, Guidance on the application of CLP criteria V. 5.0)”. In accordance with Figure IV.4 “Classification strategy for determining acute 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, iron (hydr)oxides are poorly soluble and do not meet classification criteria for acute (short-term) aquatic hazard. 

 

The acute aquatic hazard potential of poorly soluble substance zinc ferrite is evaluated by comparing the dissolved metal ion levels resulting from the transformation/dissolution test after 7 days at a loading rate of 1 mg/L with the lowest acute ecotoxicity reference values (ERVs) as determined for the (soluble) metal ions. The ERVs are based on the lowest EC50/LC50 values for algae, invertebrates and fish. Acute ERVs were obtained from the Metals classification tool (MeClas) database (Version 5.9 accessed on 22.11.2021) as follows: Iron (hydr)oxides are not expected to have an ecotoxic potential as confirmed by the absence of acute ecotoxicity reference values for iron (ions) in the Metals classification tool (MeClas) database. 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.” Thus, a concern for short-term (acute) toxicity of iron ions was not identified (no classification). The acute ERVs for zinc at pH 6 and 8 amount to 413 µg Zn/L and 136 µg Zn/L and are thus well above dissolved zinc concentration of 9.2 µg Zn/L and 3.0 µg Zn/L, measured at a loading of 1 mg/L and pH 6 and pH 8 after 7 days T/D, respectively. Due to the lack of an acute aquatic hazard potential for soluble iron ions and the fact that the dissolved zinc concentrations measured in the T/D test after 7 days at pH 6 and pH 8 are significantly lower than the respective lowest acute ERVs for zinc, it can be concluded that the substance zinc ferrite is not sufficiently soluble to cause short-term toxicity at the level of the acute ERVs (expressed as EC50/LC50).

 

 ”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 (ECHA, 2017, Section IV.5.2.2.1 Approach based on available chronic toxicity reference data, Guidance on the application of CLP criteria V. 5.0).” 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 (V. 5.0, July 2017) and section 4.1.2.10.2. of Regulation (EC) No 1272/2008, iron (hydr)oxides are poorly soluble and do not meet classification criteria for chronic (long-term) aquatic hazard. 

 

The chronic aquatic hazard potential of poorly soluble substance zinc ferrite 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: Iron (hydr)oxides are not expected to have an ecotoxic potential as confirmed by the absence of chronic ecotoxicity reference values for iron (ions) in the Metals classification tool (MeClas) database. 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.” Thus, a concern for long-term (chronic) toxicity of iron (ions) was not identified (no classification). The chronic ERVs for zinc at pH 6 and 8 amount to 82 µg Zn/L and 19 µg Zn/L and are thus well above the dissolved zinc concentration of 12.5 µg Zn/L and 8.0 µg Zn/L, measured at a loading of 1 mg/L and pH 6 and pH 8 after 28 days T/D, respectively. Due to the lack of an chronic aquatic hazard potential for soluble iron ions and the fact that the dissolved zinc concentrations measured in the T/D test after 28 days at pH 6 and 8 are significantly lower than the respective lowest long-term ERVs for zinc, it can be concluded that the substance zinc ferrite is not sufficiently soluble to cause long-term toxicity at the level of the chronic ERVs (expressed as NOEC/EC10).

 

 

The conclusion on a lack of an aquatic hazard potential of iron (hydr)oxides is in accordance with a Tier-1 assessment performed with MECLAS version 5.2 (http://www.meclas.eu/ accessed on 22.11.2021). The Metals Classification Tool (MECLAS) is a web enabled classification tool always updated to the latest classification guidance, legal ruling, information on toxicity references and available self-classifications. 

 

In sum, iron (hydr)oxides (poorly soluble iron oxide category substances incl. zinc ferrite) do not meet classification criteria of an acute or long-term aquatic hazard of Regulation (EC) No 1272/2008.