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Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

See attached document in section 13 "Assessment report" for justification and rationale of the analogy approach.
Original letters from the French Competent Authorities requiring the read across to be done with cerium and iron oxide isostearate are attached below.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 100 other: % saturated solution

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 other: % saturated solution

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Conclusions:

Iron oxide isostearate is to be considered as cerium and iron isostearate as having no acute toxic effects on Oncorhynchus mykiss up to its solubility limit in the test water at the loading rate of 100 mg/L (100% saturated solution) under the present test conditions.

Executive summary:

The source and target substances present similar characterization (nanoparticles of very similar parameters), and similar physico-chemical and ecotoxicological properties (high melting point, low vapour pressure, very low water solubility, no expected bioaccumulation potential when considering cerium and iron elements and isostearate parts, no acute toxicity to daphnids up to and including the saturation concentration). This similarity supports the relevance of the read-across.

Thus, the short term toxicity to fish is expected to be the same for the source and target substances.

Iron oxide isostearate is to be considered as cerium and iron isostearate as having no acute toxic effects on Oncorhynchus mykiss up to its solubility limit in the test water at the loading rate of 100 mg/L (100% saturated solution) under the present test conditions.

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from October 2001 to 17 January 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0 and 100 mg/L (loading rate)
- Sampling method: each sample contained 100 mL (control solution) or 50 mL (loading rate 100 mg/L). Samples were taken in triplicate (control solution) or duplicate (loading rate 100 mg/L) at the beginning of the test, before and after each change and at the end of the test, and analysed for Cerium content.
- Sample storage conditions before analysis: all samples were acidified just after sampling with 1% (v/v) of nitric acid and refrigerated at +4°C.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
As the test item, when added to water, is dissociated into a mixture of poorly soluble components (isostearate, cerium and iron), the water-soluble fractions (WSF) procedure was applied to prepare the test solutions.
Each solution was prepared by stirring the test item in test water at the appropriate loading rate during 7 days at 20-25°C ± 2°C in darkness. After a filtration through a filter of porosity 4-7µm and then a filter of porosity 0.45µm, the WSF was collected and used as the test solution.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: rainbow trout
- Strain: /
- Source: CIT ; animals were cultured from eggs obtained from Viviers de France, Piscicultures des Fontaines,64490 Sarrance, France
- Age at study initiation: data not available
- Length at study initiation: mean value of 40.3 mm (mean value of a sample of 24 fish, range from 40 to 42 mm)
- Weight at study initiation: 0.41 g (mean value of 10 fish)
- Method of breeding: under flow-through system in water of the same quality and temperature as that to be used in the test
- Feeding during test: no

ACCLIMATION
- Acclimation period: yes
- Acclimation conditions: same as test
- Type and amount of food: trout chow
- Feeding frequency: twice daily ceasing 48h before start of the test

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Post exposure observation period:

none

Hardness:

153 to 157 mg/L as CaCO3

Test temperature:

12.7°C to 14.2°C

pH:

7.62 to 8.40

Dissolved oxygen:

6.0 to 8.6 mg/L (>60 % oxygen saturation)

Nominal and measured concentrations:

Nominal loading rate: 100 mg/L (= 100% saturated solution)
Measured concentration in the fresh solutions at T0, T24, T48 and T72: 2.9 - 5.9 µg/L
Measured concentration in the stale solutions at T23.9, T47.9, T71.9 and T96: ca. 2.9 - 5.9 µg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: data not available
- Aeration: not during the test. Dilution water was aerated prior to addition of test item.
- Renewal rate of test solution (frequency): daily at T24, T48 and T72
- No. of organisms per vessel: seven
- No. of vessels per concentration (replicates): one
- No. of vessels per control (replicates): one
- Biomass loading rate: 0.41 g/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: filtered and dechlorinated potable water, which is then softened. Half of the water passes directly into a holding tank attached to the flow-through system while the remaining half passes through a deionizer producing ultra pure water which is then fed into the holding tank.
- Ca/Mg ratio: ca. 4:1
- Na/K ratio: ca. 9:1
- Metals: copper < 0.04 mg/L
- Culture medium different from test medium: no.
- Intervals of water quality measurement: the pH, temperature and dissolved oxygen values were measured in the limit test solutions (control and highest loading rate) at T0 and then daily. Measurements of total hardness in dilution water were made daily.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16hr light/8 hrs dark
- Light intensity: data not available

EFFECT PARAMETERS MEASURED: mortality and visible abnormalities at 0, 2, 4, 14, 48, 72 and 96 hours

TEST CONCENTRATIONS
Spacing factor for test concentrations: not relevant (limit test)
- Range finding study: yes
- Test concentrations of the range finding study: 1 and 10 mg/L (loading rate)
- Results used to determine the conditions for the definitive study: no mortality observed up to 10 mg/L (loading rate).

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 100 other: % saturated solution

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 other: % saturated solution

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

BIOLOGICAL RESULTS:
No mortality or sub-lethal effects were noted at any of the loading rates tested during range-finding and limit tests.

ANALYTICAL RESULTS:
The measured concentration of Cerium in the solution at 100 mg/L in the fresh solutions at T0, T24, T48 and T72 was 2.9 - 5.9 µg/L. As this range of values is close or slightly higher than the water solubility determined in the OECD test No. 105 (i.e. 2.8 µg Ce/L), it was thus considered that the saturation level of all test item components was reached. The slight discrepancy can be explained by the use of different water media between OECD test No. 105 and 203.
The measured concentration in the stale solutions at T23.9, T47.9, T71.9 and T96 were very similar to those measured in the corresponding fresh solutions. Consequently, the concentration of cerium was stable during 24 hours at the loading rate of 100 mg/L.

Results with reference substance (positive control):

No reference substance used.

Reported statistics and error estimates:

None as no adverse effect was observed.

Sublethal observations / clinical signs:

Observation time (hours)	Mortality at each range-finding or limite test loading rate (mg/L) N fish out of 7 (0 and 100 mg/L) or 5 fish (1 and 10 mg/L)
	0	1	10	100
0	0	0	0	0
2	0	0	0	0
4	0	0	0	0
24	0	0	0	0
48	0	0	0	0
72	0	0	0	0
96	0	0	0	0

Validity criteria fulfilled:

yes

Conclusions:

Cerium and iron oxide isostearate had no acute toxic effects on Oncorhynchus mykiss up to its solubility limit in the test water at the loading rate of 100 mg/L (100% saturated solution) under the present test conditions.

Executive summary:

The 96hr-acute toxicity of cerium and iron oxide isostearate to Oncorhynchus mykiss was studied under semi-static conditions according to OECD Guideline 203 and GLP. Fish were exposed to control and test chemical at nominal loading rate of 100 mg/L. The water-soluble fraction (WSF) procedure was applied to prepare the test solutions. Mortality and visible abnormalities were observed at 0, 2, 4, 24, 48, 72 and 96 hours.

No mortality was observed during the test, neither in the control nor in the group exposed to the test item.

Thus, the 96-hour LC50 is > 100% saturated solution

and the 96 hour NOEC is ≥ 100% saturated solution

As no adverse effect was observed at the highest loading rate tested (i.e. 100 mg/L), which corresponded to the maximum concentration of dissolved test item, cerium and iron oxide isostearate is not acutely toxic for fish up to its solubility limit into water.

Description of key information

By analogy with cerium and iron oxide isostearate (active matter of DPX10), iron oxide isostearate (active matter of DPX13) is not considered as acutely harmful for the fish species tested.

Additional information

One GLP-compliant study performed according to OECD guideline 203 is available on the analogue, cerium and iron oxide isostearate (active matter of DPX10). It is quoted as reliability 1 according to Klimisch criteria and flagged as a key study.