[No public or meaningful name is available]

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

fish, juvenile growth test

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 06 May 2008 to 20 November 2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 215 (Fish, Juvenile Growth Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: all test concentrations and control
- Sampling method: for the determination of the test item concentrations, triplicate samples were taken from the freshly prepared test media of all test concentrations and from the control at the start of the test (Day 0), and at the start of each treatment period (Days 3, 7, 10, 14, 17, 21 and 24).
To determine the maintenance of the test item concentrations in the test media, triplicate stability samples were taken at least once a week (at the end of two 72-hour and two 96-hour renewal periods on Days 3 and 17 and on Days 14 and 21, respectively).
Samples were taken from the approximate center of the aquaria without prior mixing of the test media.
- Sample storage conditions before analysis: immediately after sampling, the samples were acidified with 10% (v/v) nitric acid (HNO3, 65% Suprapur®, Merck) to stabilize the samples during the storage period. Then the samples were stored at room temperature.
Two of the triplicate samples were used for analysis. The third was retained as a reserve sample.
The samples to be analyzed were sent to the Test Site ICP-MS Measurement.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method:
Prior to the start of the test and prior to each test medium renewal, a dispersion of the test item with a loading rate of 100 mg/L was prepared by dispersing 13.0 mg (effective weights: 13.0-13.1 g) of the test item in 130 liter test water.
This dispersion was stirred over 6 days in a glass tank in the dark by a powerful electric stirrer. Thereafter, stirring was stopped and the undissolved test item was allowed to separate from the water phase (settling down on the bottom of the glass tank) for one day. Stirring period and settling period resulted in a contact time of 7 days. After separation, the clear test medium was sucked of with a teflon tube from the middle of the water column. No filtering of the test medium was applied.
The undiluted supersaturated solution of the test item with the maximum concentration of dissolved test item (and possibly a small amount of very finely dispersed test item particles) was used as highest test concentration. Requisite aliquots of the highest test concentration were diluted with test water to obtain the lower test concentrations.
The test concentrations were the undiluted supersaturated solution of the test item and the dilutions 1:2.2, 1:4.6, 1:10 and 1:22.
- Controls: test water without test item

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: rainbow trout
- Strain: /
- Source: P. Hohler, trout breeding station Zeiningen, 4314 Zeiningen / Switzerland
- Age at study initiation: juvenile
- Length at study initiation: no data
- Weight at study initiation: mean body weight was 1.4 g, ranging from 1.3 g to 1.5 g.
- Method of breeding: held at Harlan Laboratories for two weeks prior to the start of test without any medication under similar conditions as in the test.
- Feeding during test
- Food type: commercial fish diet
- Amount: 2% during the first week, and increased by 25% each week (dry weight related to the mean initial fish wet weight in each treatment)
- Frequency: daily (two feeding intervals per day (separated by more than five hours) during the light period)

ACCLIMATION
- Acclimation period: 7 days
- Acclimation conditions: same as test
- Type and amount of food: commercial fish diet (2% as dry weight related to the mean initial fish wet weight in each treatment)
- Feeding frequency: daily
- Health during acclimation: during acclimation, no fish died in the test fish batch and all fish were healthy.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

28 d

Post exposure observation period:

none

Hardness:

about 214 mg/L as CaCO3 (measured once per week during the test)

Test temperature:

13-14°C (measured in the control and all test media at least three times per week)

pH:

8.4 to 8.5 (measured at the start and end of the Test Medium Renewal Periods)

Dissolved oxygen:

8.8 to 9.9 mg/L

Nominal and measured concentrations:

Nominal loading rates (mg/L): 100, 45.5 (dilution 1:2.2), 21.7 (dilution 1:4.6), 10 mg/L (dilution 1:10) and 4.5 (dilution 1:22)
Measured concentration at the loading rate of 100 mg/L: from < LOQ to 11 μg Ce/L (in the freshly prepared test medium) ; < LOQ (at the end of the test medium renewal periods of 72 and 96 hours)
Mean measured concentration of test item (μg/L): 5.1 µg/L (geometric mean of the mean concentrations measured at the start and at the end of the test medium renewal periods)

Details on test conditions:

TEST SYSTEM
- Test vessel: 60-litre aquarium
- fill volume: about 50 liters of test medium
- Aeration: slightly aerated during the test
- Renewal rate of test solution (frequency/flow rate): the test media were renewed two times per week (every three and four days).
- No. of organisms per vessel: 10 fish
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Biomass loading rate: =< 1 g fish wet weight per liter medium at the end of the test

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Local tap water (non chlorinated well water of drinking water quality), reduced for total hardness by ion exchange was used. The total hardness was about 214 mg/L as CaCO3. The test water was aerated prior to the preparation of the test media until oxygen saturation was reached.
- Culture medium different from test medium: no
- Intervals of water quality measurement: The pH values and the dissolved oxygen concentrations in the test media of all test concentrations and the control were measured in all freshly prepared and aged test media. The water temperature was measured in the control and all test media at least three times per week. Additionally, the water temperature in the control was monitored continuously by a data logger. The water hardness of the test water was measured once per week during the test. The appearance of the test media was daily recorded.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16-hour light to 8-hour dark photoperiod
- Light intensity: approximately 240–560 Lux (with a 30-minute transition period)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
During the test period, the fish were observed at least once each working-day for mortality and visible abnormalities.
At the start (Day 0) and at the end of the test (Day 28) the body wet weight of all fish was determined. The fish were not individually marked for reasons of animal welfare. Therefore, the ‘pseudo’ specific growth rate of each test fish was calculated for the study period of 28 days, using the equation:
r' = [(ln w2 - ln mw1) / (t2 - t1)] x 100
where:
r’ = ‘pseudo’ specific growth rate of the test fish during the test period
ln w2 = natural logarithm of body weight of each individual fish at the end of the test period
ln mw1 = mean value of the natural logarithms of body weight of all fish in the aquarium at the start of the test period
t1, t2 = day at the start and end of the test period, respectively

RANGE-FINDING STUDY
- Range-finding study: yes
- Test concentrations: no data
- Results used to determine the conditions for the definitive study: no data

Reference substance (positive control):

no

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 100 other: % saturated solution

Conc. based on:

test mat.

Basis for effect:

other: mortality, observations for visible abnormalities, fish wet weight, and pseudo specific growth rate for body wet weight

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

> 100 other: % saturated solution

Conc. based on:

test mat.

Basis for effect:

other: mortality, observations for visible abnormalities, fish wet weight, and pseudo specific growth rate for body wet weight

Details on results:

ANALYTICAL RESULTS:
The analytically measured concentration of cerium in the freshly prepared test media of the highest test concentration (saturated solution of the test item with a test item loading rate of 100 mg/L) ranged from < LOQ (limit of quantification of 1 μg/L) to 11 μg/L at the start of the test medium renewal periods. The arithmetic mean was 3.3 μg/L, corresponding to a test item concentration of 14 μg/L. The variation of cerium concentrations at the start of the renewal periods may be due to very finely test item particles, which remained in the water column during the settling period.
At the end of the test medium renewal periods of 72 and 96 hours, the concentrations of cerium were < LOQ.
The mean measured test item concentration over the 28-day test period was 5.1 µg/L. The solubility limit into water reached during this test was thus different from that obtained during the water solubility test (see IUCLID section 4.8). Such contrasting results could be explained by the different water media used in the water solubility test and ecotoxicological studies (media containing analytical grade salts).

BIOLOGICAL RESULTS:
Neither mortality nor visible abnormalities were observed at the test fish during the test in the control and at all test concentrations up to and including the highest test concentration (loading rate of 100 mg/L).
At the start of the test, the mean body wet weights of the test fish, used at each test concentration and the control, were identical. The range of individual body wet weight was 1.3 g to 1.5 g in all treatments and, thus, in the range of ±10% of the mean value as requested by the guideline. During the test period of 28 days, the mean wet weight of the test fish in the control had increased by a factor of 3.4.
At the end of the test period of 28 days, the mean fish wet weight and the pseudo specific growth rate for wet weight of the test fish were nearly identical or even slightly higher compared to the control up to and including the highest loading rate of 100 mg/L and no concentration effect relationship was observed.

Results with reference substance (positive control):

No reference substance used.

Reported statistics and error estimates:

None as no adverse effect was observed.
A statistical evaluation of the mean values of the pseudo-specific growth rates and the mean body wet weights was not necessary due to the clear results obtained in this test.

Table 1 Mortality and Visible Abnormalities

Number of fish tested at each concentration and control: 10

Day	0 (after 2 hours)	During 1. week	During 2. week	During 3. week	During 4. week
Treatment / dilution	Number of abnormal and dead fish / number of dead fish Type of visible abnormalities
Control	0 / 0	0 / 0	0 / 0	0 / 0	0 / 0
Dilution 1:22	0 / 0	0 / 0	0 / 0	0 / 0	0 / 0
Dilution 1:10	0 / 0	0 / 0	0 / 0	0 / 0	0 / 0
Dilution 1:4.6	0 / 0	0 / 0	0 / 0	0 / 0	0 / 0
Dilution 1:2.2	0 / 0	0 / 0	0 / 0	0 / 0	0 / 0
Saturated solution (loading rate 100 mg/L)	0 / 0	0 / 0	0 / 0	0 / 0	0 / 0

 

Table 2 Body Wet Weight of All Test Fish at the Start and End of the Test (measured in g)

Fish	Treatment / dilution
	Control	Dilution 1:22	Dilution 1:10	Dilution 1:4.6	Dilution 1:2.2	Saturated solution (loading rate 100 mg/L)
Start of test :
Mean ± SD MIN MAX n	1.4 0.09 1.3 1.5 10	1.4 0.07 1.3 1.5 10	1.4 0.10 1.3 1.5 10	1.4 0.09 1.3 1.5 10	1.4 0.09 1.3 1.5 10	1.4 0.09 1.3 1.5 10
End of test :
Mean ± SD MIN MAX N % growth	4.7 0.52 3.8 5.6 10 345	4.8 1.04 2.9 6.0 10 344	4.5 0.99 2.9 6.1 10 326	4.3 0.67 3.2 5.2 10 308	4.5 0.45 3.8 5.2 10 325	4.8 0.70 3.9 5.7 10 346

% Growth: increase of mean body wet weight compared to the mean body wet weight at the start of the test (= 100%).

 

Table 3 Pseudo Specific Growth Rate r’ for Body Wet Weight of Each Test Fish during the Test Period of 28 Days

Fish	Treatment / dilution
	Control	Dilution 1:22	Dilution 1:10	Dilution 1:4.6	Dilution 1:2.2	Saturated solution (loading rate 100 mg/L)
End of the test after 28 days :
Mean ± SD MIN MAX N % of control	4.41 0.40 3.67 5.02 10 100	4.33 0.89 2.67 5.24 10 98	4.15 0.81 2.69 5.32 10 94	3.98 0.58 2.98 4.70 10 90	4.20 0.35 3.63 4.73 10 95	4.41 0.52 3.67 5.09 10 100

 

Validity criteria fulfilled:

yes

Remarks:

Mortality in control < 10%; Increase of weight in control ≥ × 1.5; acceptable pH, T° and oxygen concentration

Conclusions:

Based on mortality, observations for visible abnormalities, fish wet weight, and pseudo specific growth rate r’ for body wet weight, the highest concentration tested without toxic effects (NOEC) observed at rainbow trout after an exposure period of 28 days was determined to be ≥100 % saturated solution.
Cerium and iron oxide isostearate had thus no adverse chronic effect up to its solubility limit.

Executive summary:

The toxicity of the test item cerium and iron oxide isostearate to rainbow trout (Oncorhynchus mykiss) was investigated in a 28-day semi-static test according to OECD Guideline No 215 and GLP. Juvenile trouts were exposed to control and test chemical at nominal loading rates of 4.5 (dilution 1/22), 10 (dilution 1/10), 21.7 (dilution 1/4.6), 45.5 (dilution 1/2.2) and 100 mg/L (saturated solution, mean measured concentration 5.1 μg/L). The mortality, the visible abnormalities, the body weight and the pseudo specific growth rate of the exposed fish were compared with the corresponding parameters in the control.

Considering that a saturated solution was produced at the highest loading rate tested, the following biological results were obtained:

– 28-day NOEC: ≥100 % saturated solution

– 28-day LOEC: >100 % saturated solution

Based on mortality, visible abnormalities, fish wet weight and pseudo specific growth rate for body wet weight, the test item cerium and iron oxide isostearate had no chronic toxic effects on rainbow trout (Oncorhynchus mykiss) up to its solubility limit in test water under the present test conditions.

Reference 2

Endpoint:

fish, juvenile growth test

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:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 100 other: % saturated solution

Conc. based on:

test mat.

Basis for effect:

other: Mortality, observations for visible abnormalities, fish wet weight, and pseudo specific growth rate for body wet weight.

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

> 100 other: % saturated solution

Conc. based on:

test mat.

Basis for effect:

other: Mortality, observations for visible abnormalities, fish wet weight, and pseudo specific growth rate for body wet weight.

Conclusions:

Iron oxide isostearate is to be considered as cerium and iron oxide isostearate as having no chronic toxic effects (based on mortality, visible abnormalities, fish wet weight and pseudo specific growth rate) on rainbow trout (Oncorhynchus mykiss) up to its solubility limit in test water 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 long 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 oxide isostearate as having no chronic toxic effects (based on mortality, visible abnormalities, fish wet weight and pseudo specific growth rate) on rainbow trout (Oncorhynchus mykiss) up to its solubility limit in test water under the present test conditions.

Description of key information

By analogy with cerium and iron oxide isostearate (active matter of DPX10), iron oxide isostearate (active matter of DPX13) should not have any adverse chronic effect on the fish species tested.

Additional information

One GLP-compliant study performed according to OECD guideline 215 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.