Chromium (III) oxide

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The study was conducted in accordance with a recognised guideline and to GLP, and the validity criteria were fulfilled. However, the report omits some procedural details and contains no information about the preparation and analysis of samples for dissolved chromium.

Qualifier:

equivalent or similar to guideline

Guideline:

ISO 7346-1 (Determination of the Acute Lethal Toxicity of Substances to a Freshwater Fish [Brachydanio rerio Hamilton-Buchanan (Teleostei, Cyprinidae)] - Part 1: Static Method)

Version / remarks:

The report cites section 2.B.3 of a proposed method of the German Umweltbundesamt (UBA), Berlin (1984)

Deviations:

no

Principles of method if other than guideline:

Not relevant.

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Not relevant.

Analytical monitoring:

yes

Details on sampling:

Samples were taken from the control and nominal 10000 mg/L treatments at initiation (0 h) and termination (96 h) and analysed to determine concentrations of dissolved Cr. Analytical data indicate there were two vessels containing 10000 mg 'Chromoxid-gruen GN'/L: one with fish and the other without; samples were taken from both after 96 h.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A weighed quantity of the test substance was added directly to water and stirred for 67 hours before test initiation, forming a green coloured suspension.
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): no vehicle or co-solvent was used.
- Evidence of undissolved material (e.g. precipitate, surface film, etc): undissolved test substance on the surface of the test medium and attached to the sides of the test vessel.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: zebra fish.
- Strain: Brachydanio rerio Hamilton-Buchanan.
- Source: Commercial supplier: 'West Aquarium', Bad Lauterberg, Germany.
- Age at study initiation: ca. 17 weeks.
- Length: 2.5 to 3.3 cm (control) and 2.5 to 3.1 cm (10000 mg/L treatment) at termination.
- Weight: mean 0.163 g (control) and 0.176 g (10000 mg/L treatment) at termination.
- Feeding during test: not stated.


ACCLIMATION
- Acclimation period: ca. 6 weeks.
- Acclimation conditions (same as test or not): not stated.
- Type and amount of food: not stated.
- Feeding frequency: not stated.
- Health during acclimation (any mortality observed): no mortalities or medication.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Post exposure observation period:

Not relevant.

Hardness:

5.1 degrees dH in synthetic fresh water, composition according to ISO .

Test temperature:

control: 20.4- 21.0 °C;
10000 mg/L treatment: 20.5-21.8 °C.

pH:

control: 6.8 to 7.4;
10000 mg/L treatment: 6.8 to 7.4.

Dissolved oxygen:

control: 8.7 to 10.8 mg/L (equivalent to 100.2 to 123.4% ASV);
10000 mg/L treatment: 8.9 to 10.8 mg/L (equivalent to 104.0 to 124.0% ASV).

Salinity:

Not relevant.

Nominal and measured concentrations:

Nominal: 0 (control) and 10000 mg 'Chromoxid-gruen GN'/L.

Measured:
0.1 microgram dissolved Cr/L (control) at 0 h and 96 h;
0.8 microgram dissolved Cr/L (10000 mg 'Chromoxid-gruen GN'/L) at 0 h;
0.8 microgram dissolved Cr/L (10000 mg 'Chromoxid-gruen GN'/L) at 96 h in a vessel containing no fish;
1.3 microgram dissolved Cr/L (10000 mg 'Chromoxid-gruen GN'/L) at 96 h in the vessel containing 10 fish.

The arithmetic mean measured exposure concentration in the nominal 10000 mg 'Chromoxid-gruen GN' treatment was 1.0 microgram dissolved Cr/L, equivalent to 2.9 microgram dissolved test substance/L.

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): aquaria.
- Material, size, fill volume: 300 x 135 x 200 mm, 5 L medium.
- Aeration: yes.
- No. of organisms per vessel: 10.
- No. of vessels per concentration (replicates): two: one with, one without fish.
- No. of vessels per control (replicates): one.
- Biomass loading rate: 0.33 to 0.35 g wet weight/L.


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: synthetic freshwater, composition according to ISO.
- Total organic carbon: not stated.
- Particulate matter: not stated.
- Metals: not stated, with the exception of dissolved Cr (0.1 microgram/L in the control).
- Pesticides: not stated.
- Chlorine: not stated.
- Alkalinity: not stated.
- Ca/mg ratio: not stated.
- Conductivity: not stated.
- Culture medium different from test medium: no.
- Intervals of water quality measurement: 0, 24, 48, 72 and 96 h.


OTHER TEST CONDITIONS
- Adjustment of pH: no.
- Photoperiod: not stated.
- Light intensity: not stated.


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality and sub-lethal effects (after 2, 24, 48, 72 and 96 h).


TEST CONCENTRATIONS
- Spacing factor for test concentrations: not applicable (limit test).
- Justification for using less concentrations than requested by guideline: not applicable.

Reference substance (positive control):

no

Remarks:

Not required.

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

'Chromoxid-gruen GN'

Basis for effect:

mortality (fish)

Remarks on result:

other: None

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 1 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Remarks:

chromium

Basis for effect:

mortality (fish)

Remarks on result:

other: None

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 2.9 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Remarks:

dissolved equivalent, derived from dissolved Cr analysis

Basis for effect:

mortality (fish)

Remarks on result:

other: None.

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

'Chromoxid-gruen GN'

Basis for effect:

behaviour

Remarks:

(swimming)

Remarks on result:

other: None.

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

dissolved

Remarks:

chromium

Basis for effect:

behaviour

Remarks:

(swimming)

Remarks on result:

other: None

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 2.9 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Remarks:

dissolved equivalent, derived from dissolved Cr

Basis for effect:

behaviour

Remarks:

(swimming)

Remarks on result:

other: None.

Details on results:

- Behavioural abnormalities: None.
- Observations on body length and weight: No evidence of treatment-related effects, relative to the control, following exposure to 'Chromoxid-gruen GN'.
- Other biological observations: No evidence of adverse sub-lethal effects in the control or the 'Chromoxid-gruen' GN treatment.
- Mortality of control: 0% after 96 h.
- Other adverse effects control: None.
- Abnormal responses: None.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: 'Chromoxid-gruen' GN was observed floating on the surface of the test medium and deposited on the walls of the test vessel. At the initial 2 h observation, the fish in the 'Chromoxid-gruen' GN treatment were obscured from view by suspended test material, but this difficulty was resolved by the time of the next observation at 24 h. From 24 h onwards, the fish of the 'Chromoxid-gruen' GN treatment were coloured green, presumably due to deposition of the suspended test substance.
- Effect concentrations exceeding solubility of substance in test medium: the nominal limit concentration of the test substance (10000 mg 'Chromoxid-gruen' GN) exceeded its solubility in the test medium, however analytical measurements were made to facilitate expression of the endpoint in terms of dissolved chromium.
- Effect concentrations exceeding solubility of substance in test medium: Yes: nominal 'Chromoxid-gruen' GN limit concentration exceeds solubility limit.

Results with reference substance (positive control):

Not relevant.

Reported statistics and error estimates:

Not relevant.

Sublethal observations / clinical signs:

Measured concentrations of dissolved Cr and observations of fish mortality and sub-lethal effects following exposure to 'Chromoxid-gruen GN' are presented in the table below:

Chromoxid-grün GN' nominal concentration (mg/L)	Dissolved Cr measured concentration (µg/L)			Mortality (%) after 96 hours	Sublethal effects^a
	0 h	96 h	mean
0 (control)	0.1	0.1	0.1	0	none
10000	0.8	1.3	1.0	0	none
10000 (abiotic, no fish)		0.8		n.a.	n.a.
a              Based on observations of swimming behaviour after 2, 24, 48, 72  and 96 h exposure.  The fish in the 'Chromoxid-gruen GN' treatment were obscured from view by suspended test material at the 2 h observation.

Validity criteria fulfilled:

yes

Remarks:

Control morality <10%, dissolved oxygen concentration >60% ASV.

Conclusions:

A study of the acute toxicity of 'Chromoxid-gruen GN' (chromium (III) oxide) to fish was conducted with zebra fish (B. danio) exposed to a nominal limit concentration of 10000 mg 'Chromoxid-gruen GN'/L for 96 hours under static conditions.

The 96 hour LC50 of 'Chromoxid-gruen GN' (chromium (III) oxide) to the zebra fish (B. rerio), under static conditions, was >10000 mg/L, based on the nominal limit concentration applied in the test. Based on the absence of abnormal swimming behaviour, the unbounded 96 h NOEC was ≥ 10000 mg/L (nominal).

The solubility of 'Chromoxid-gruen GN' was low under the conditions of the test. Based on the mean measured concentration of dissolved chromium at the nominal limit concentration of 'Chromoxid-Gruen GN', the 96 hour LC50 of was >1.0 microgram Cr/L (equivalent to 2.9 microgram dissolved 'Chromoxid-gruen GN'/L).

Description of key information

The rate and extent to which chromium (III) oxide produces soluble (bio)available ionic and other chromium-bearing species in environmental media is limited. Further, the poor solubility of chromium (III) oxide is expected to determine its behaviour and fate in the environment, and subsequently its potential for ecotoxicity. Therefore, the fate and toxicity of chromium (III) oxide in the environment is evaluated by assessing the fate of its ecotoxicologically relevant moiety, the chromium (III) ion, and read-across to data available for other chromium (III) substances is applied.

In accordance with ECHA’s Guidance on IR & CSA, Appendix R.7.13-2 (2008), the poorly soluble substance chromium (III) oxide is evaluated by comparing the dissolved chromium (III) ion level resulting from the T/Dp at a loading rate of 1 mg/L after 7 d with the lowest acute effect concentration as determined for the (soluble) chromium (III) ion. The lowest reliable acute effect concentration determined for the (soluble) chromium (III) ion is a LC50 of 4.0 mg Cr(III)/L observed in a 96-h acute toxicity test on the effects of chromium (III) nitrate to juvenile Oncorhynchus mykiss in a flow-through exposure system (Stevens & Chapman, 1984). Dissolved chromium concentrations of <0.01 microg/L in the T/Dp after 7 days at pH 6 (i.e. the pH that maximizes the dissolution) are significantly lower than the lowest acute effect concentration derived for fish (i.e. LC50 of 4.0 mg Cr(III)/L). Hence, chromium (III) oxide is not sufficiently soluble in environmental media to cause acute toxicity to fish at the level of the lowest acute effect concentration for dissolved chromium (III) ions (expressed as LC50).

For further information on the applied read-across approach and the evaluation of the poorly soluble substance chromium (III) oxide, please refer to the section "Cr2O3_Aquatic toxicity".

Additionally, effects on survival and swimming behavior of freshwater fish Danio rerio were not observed at the nominal limit concentration of 10,000 mg Cr2O3/L in an acute toxicity study with chromium (III) oxide (Caspers, 1992). The solubility of Cr2O3 was however low under the conditions of the test. Based on the mean measured dissolved chromium concentration at the nominal limit concentration, the 96-h LC50 corresponds to >1.0 microg Cr/L (equivalent to 2.9 microg dissolved chromium (III) oxide).

Based on the poor solubility of chromium (III) oxide in environmental media, acute toxicity to fish is not expected.