Iron hydroxide oxide yellow

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: as reported in source record(s)

Remarks:

This target record summarises individual studies on the toxicity to aquatic algae and cyanobacteria that ranged in reliability from 2-3.

Justification for type of information:

see "Endpoint-specific read-across justification for nanoforms of iron oxide_2021” and "Read-across justification-environ assessment-iron oxides_2021” attached in IUCLID section 13

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 20 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: as reported in source record

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 20 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: as reported in source record

Description of key information

Applying read-across (category approach) to diiron trioxide in nanoform (see attachment "Iron oxides category justification” in IUCLID section 13), iron hydroxide oxide yellow in nano-form (alpha) is considered not toxic to aquatic algae. In a reliable 72 h algae growth inhibition test according to OECD 201 with Fe2O3 nanoparticles, no significant effect on the growth rate of Pseudokirchneriella subcapitata was observed at the applied concentrations of 8.2 to 20.0 mg/L and thus an unbounded 72 h NOEC≥20 mg/L (nominal) was derived.

Additional information

In a supporting, non-guideline study, effects of diiron trioxide nanoparticles (α-Fe2O3-NP) on the freshwater algae Chlorella pyrenoidosa were assessed (Lei et al., 2016). Based on the obtained results a 96 h IC50 and IC10 forα-Fe2O3 of 71.0 and ~20 mg/L (graphical estimate, extrapolated value) were assessed, respectively. The study is considered as supporting only since it cannot be considered reliable due to a number of methodological shortcomings. It is not clear whether growth rates were calculated from cell counts (only % inhibition is presented) and the growth of the control cannot be checked (validity criteria not assessable).