Diiron trioxide

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

Daphnia magna

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

The test item was insoluble in water. Treatment in an ultrasonic bath (1 h) resulted in red-brown colouration of the flask content, indicating fine dispersal of the test item. After treatment on a magnetic stirrer for 24 h, the suspension was tested without filtration.

Validity criteria fulfilled:

yes

Remarks:

The immobilisation and other abnormalities in the controls did not exceed 10% by the end of the test. The dissolved oxygen concentration remained above 3 mg/L throughout the exposure period.

Conclusions:

The observed 48-hour EC50 on Daphnia magna was >/= 100 mg/l. The test was conducted according to guideline OECD 202.

Executive summary:

The acute toxicity of diiron trioxide to Daphnia magna STRAUS was conducted in a static test. Observations were made on the swimming ability and the immobilisation rate, respectively, after 24 and 48 hours of exposure. The test item was insoluble in water. Treatment in an ultrasonic bath (1 h) resulted in red-brown colouration of the flask content, indicating fine dispersal of the test item. After treatment on a magnetic stirrer for 24 h, the suspension was tested without filtration. The results are expressed in terms of nominal concentrations. Defined concentrations of the test item led to a certain percentage proportion of immobilised Daphnia at the end of the 48 hour study period. Immobilisation rates were recorded at 24-hour intervals. The EC 0 and the EC 100 were determined directly from the study, while the EC 50 was calculated or read from the concentration/percentage response curve. Additionally any abnormal behaviour or appearance of the Daphnia was reported. The Test was carried out without chemical analysis. The test was only conducted at a nominal concentration of 100 mg/L.

No toxic effects against daphnia were observed at a limit test concentration of 100 mg/L under static conditions.

Description of key information

Applying read-across to micro- and nano-sized iron (hydr)oxides (see attachment "Read-across justification-environ assessment-iron oxides" in section 13), micro-sized iron (hydr)oxides are not considered acutely toxic to aquatic invertebrates. For micro- and nano -sized iron (hydr)oxides, the observed 48-h EC50 values for the immobilization of Daphnia magna range from > 100 mg/L to > 10,000 mg/L, a concentration that is 100-fold above the corresponding OECD test limit.

Additional information

The acute toxicity of the micro-sized form of diiron trioxide to Daphnia magna STRAUS was conducted in a static test. Observations were made on the swimming ability and the immobilisation rate, respectively, after 24 and 48 hours of exposure. The test item was insoluble in water. Treatment in an ultrasonic bath (1 h) resulted in red-brown colouration of the flask content, indicating fine dispersal of the test item. After treatment on a magnetic stirrer for 24 h, the suspension was tested without filtration. The results are expressed in terms of nominal concentrations. Defined concentrations of diiron trioxide led to a certain percentage proportion of immobilised Daphnia at the end of the 48 hour study period. Immobilisation rates were recorded at 24-hour intervals. The EC 0 and the EC 100 were determined directly from the study, while the EC 50 was calculated or read from the concentration/percentage response curve. Additionally any abnormal behaviour or appearance of the Daphnia was reported. The test was carried out without chemical analysis. The test was only conducted at a nominal concentration of 100 mg/L.

No toxic effects against Daphnia were observed at a limit test concentration of 100 mg/L under static conditions.

Based on read-across to iron hydroxide oxide yellow and triiron tetraoxide (see attachment "Iron oxides category justification” in IUCLID section 13), available data further indicate a low potential for acute toxicity of iron hydr(oxides) to aquatic invertebrates (see table below).

Table: Acute toxicity of iron (hydr)oxides to aquatic invertebrates

Endpoint	Test species	Test results	Test material/form	Reliability: Reference
Short-term toxicity to aquatic invertebrates	Daphnia magna	EC50 (48h): > 100 mg/L nominal	diiron trioxide / powder	RL2: Neuhahn, 2008
.	Daphnia magna	EC0 (48 h): >= 10 g/L nominal	triiron tetraoxide /powder	RL2: Caspers, 2000
.	Daphnia magna	EC0 (48 h): >= 10 g/L nominal	zinc ferrite brown spinel / powder	RL2: Caspers, 1999
.	Daphnia magna	EC0 (48 h): >= 10 g/L nominal	manganese ferrite black spinel / powder	RL2: Caspers, 2000
.	Daphnia magna	EC50 (48h): > 100 mg/L nominal	iron hydroxide oxide yellow / nano, alpha	RL2:Neuhahn, 2008

Iron oxide category

For micro- and nano-sized iron (hydr)oxides, five reliable studies on short-term toxicity to aquatic invertebrates are available. No acute toxicity was observed in Daphnia magna exposed to micro- and nano-sized iron (hydr)oxide forms, and unbounded 48 h EC50 values of > 100 mg/L were derived.

In a reliable study with Daphnia magna according to OECD 202 (Neuhahn, 2008), an unbounded 48 h EC50 value of > 100 mg/L (nominal) was derived for acute toxicity of micro-sized diiron trioxide, as no toxic effects were observed at the limit test concentration of 100 mg/L under static conditions.

Unbounded 48 h EC50 values of > 10 g/L (nominal) were derived for micro-sized triiron tetraoxide (Caspers, 2000), zinc ferrite brown spinel (Caspers, 1999) and manganese ferrite black spinel (Caspers, 2000) in reliable studies with Daphnia magna according to EU Method C.2 (Acute toxicity to Daphnia).

Acute toxicity of iron(hydr)oxidenanoforms to aquatic invertebrates was investigated in a reliable study withnano-alphairon hydroxide oxide yellow according to OECD 202 (Neuhahn, 2008). Toxic effects to Daphnia magna were not observed at a limit test concentration of 100 mg/L under static conditions and an unbounded 48 h EC 50 value of > 100 mg/L (nominal) was derived.

Based on read-across to micro- and nano-sized iron (hydr)oxides (see attachment "Read-across justification-environ assessment-iron oxides" in section 13), available data indicate a low potential for acute toxicity of iron(hydr)oxidesto aquatic invertebrates (see table below).Acute toxicity ofmicro- and nano-sized iron (hydr)oxidesto aquatic invertebrates was not observed up to 10 g/L (Caspers, 1999; Caspers, 2000), a concentration that is 100-fold above the corresponding OECD test limit for acute toxicity.