Iron hydroxide oxide yellow

Endpoint summary

Description of key information

Available data for fish and invertebrates indicate a low potential for acute aquatic toxicity of iron hydroxide oxide yellow in nanoforms (alpha and gamma). Based on read-across (category approach) to diiron trioxide (powder and nano-form) and triiron tetraoxide (see attachment "Iron oxides category justification” in IUCLID section 13), available data for fish, invertebrates, algae and microorganisms further indicate a low potential for acute and chronic aquatic toxicity of iron (hydr)oxides. For all reliable studies (RL1 or RL2) with iron (hydr)oxides, unbounded effect concentrations above the OECD test limit were determined (see table below).

Table: Aquatic toxicity of iron (hydr)oxides

Endpoint	Test species	Test results	Test material/ form	Reliability: Reference
Short-term toxicity to fish	Danio rerio	LC50 (96h): > 10 g/L nominal LC0 (96h): >= 10 g/L nominal	diiron trioxide / nano, alpha	RL2: Weyers, 1985
	Danio rerio	LC50 (96h): > 50 g/L nominal LC0 (96h): >= 50 g/L nominal	diiron trioxide / powder	RL2: Bruns, 1989
	Danio rerio	LC50 (96h): > 100 g/L nominal LC0 (96h): >= 100 g/L nominal	iron hydroxide oxide yellow / nano, alpha	RL2:Weyers & Caspers, 1989
	Danio rerio	LC50 (96h): > 10 g/L nominal LC0 (96h): >= 10 g/L nominal	triiron tetraoxide	RL2: Caspers, 2000
	Danio rerio	LC0 (96h): >= 10 g/L nominal	triiron tetraoxide	Bayer AG, 1989
Long-term toxicity to fish	Danio rerio	NOEC (168 h): 10 mg/L nominal	diiron trioxide / nano, alpha	RL3: Zhu et al., 2012
Short-term toxicity to aquatic invertebrates	Daphnia magna	EC50 (48h): >100 mg/L nominal	diiron trioxide / powder	RL2: Neuhahn, 2008
	Daphnia magna	EC50 (48h): >100 mg/L nominal	iron hydroxide oxide yellow / nano, alpha	RL2: Neuhahn, 2008
	Daphnia magna	EC0 (48 h): >= 10 g/L nominal	triiron tetraoxide	RL2: Caspers, 2000
Long-term toxicity to aquatic invertebrates	Daphnia magna	NOEC (21 d): >= 20 mg/L nominal	diiron trioxide / nano	RL2: Nogueira et al., 2015
Toxicity to aquatic algae and cyanobacteria	Pseudo-kirchneriella subcapitata	NOEC (72 h):>= 20 mg/L nominal	diiron trioxide / nano	RL2: Nogueira et al., 2015
	Chlorella pyrenoidosa	IC50 (96 h): 71 mg/L not specified IC10 (96 h): ca. 20 mg/L* not specified	diiron trioxide / nano	RL3: Lei et al. (2016)
Toxicity to microorganisms	Activated sludge	EC50 (3 h): > 10 g/L nominal	iron hydroxide oxide/diiron trioxide (75:25) / nano, alpha	RL2: Bruns, 2004
	Activated sludge	EC50 (3 h): > 10 g/L nominal	triiron tetraoxide	RL2: Bruns, 1989

* graphical estimation, extrapolated value

 

Additional information

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. “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, the substance iron hydroxide oxide yellow in nanoforms (alpha and gamma) is poorly soluble and does not meet classification criteria for acute (short-term) aquatic hazard.

“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, the substance iron hydroxide oxide yellow in nanoforms (alpha and gamma) is poorly soluble and does not meet classification criteria for chronic (long-term) aquatic hazard.

The conclusion on a lack of an aquatic hazard potential of iron hydroxide oxide yellow in nanoforms (alpha and gamma) is in accordance with a Tier-1 assessment performed with MECLAS version 5.2 (http://www.meclas.eu/ accessed on 26.02.2020). 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, it can safely be assumed that iron hydroxide oxide yellow in nanoforms (alpha and gamma) does not need meet classification criteria of an acute or long-term aquatic hazard of Regulation (EC) No 1272/2008.

 “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 (ECHA guidance on IR & CSA, Part B: Hazard Assessment (V. 2.1, December 2011).” For soluble iron salts and poorly soluble iron hydroxide oxide yellow, there are not any ecotoxicity data showing effects in aquatic organisms, soluble iron salts and iron hydroxide oxide yellow in nanoforms (alpha and gamma) are not classified as dangerous for the aquatic environment, an aquatic PNEC cannot be derived thus not indicating a hazard to the aquatic environment.

Iron hydroxide oxide yellow in nanoforms (alpha and gamma) is not classified as harmful, toxic or very toxic to aquatic life or may cause long lasting harmful effects to aquatic life. Iron hydroxide oxide yellow in nanoforms (alpha and gamma) 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 iron (hydr)oxides in the aquatic compartment and essentiality of iron (as described in section "FeOOH_Environmental fate and pathways"), iron hydroxide oxide yellow in nanoforms (alpha and gamma) is also not considered an unclassified hazard to the aquatic compartment.