Cerium dioxide

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 11 SEP 2006 to 08 AUG 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

and EU Method C.2 (Acute toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: triplicates samples from the test medium (loading rate of 100 mg/L) and from the control were taken just before test start and after 48 hours.
- Sampling method: no data
- Sample storage conditions before analysis: Immediately after sampling, the samples were acidified with 3% (v/v) nitric acid (HNO3, 65% Suprapur®, Merck) to stabilize the samples during the storage period. Then the samples were deep frozen and stored at about -20°C.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: an undiluted filtrate of a supersaturated dispersion with the loading rate of 100 mg/L was tested. The dispersion with the loading rate of 100 mg/L was prepared by dispersing 50.3 mg of the test item in 500 mL of test water. The test item was mixed into the test water as homogeneously as possible using ultrasonic treatment for 15 min and intense stirring. The dispersion was stirred on a magnetic stirrer at room temperature in the dark for seven days. After the stirring period, the dispersion was filtered through a membrane filter (0.45 µm). The undiluted filtrate of the dispersion was used as the test medium.
- Differential loadings: No (limit test)
- Controls: blank (test water without test item)
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no data

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain: clone defined as clone 5
- Source: supplied in 1992 by University of Sheffield/UK
- Age at study initiation : 6-24 hours, not first brood progeny
- Weight and length at study initiation (mean and range, SD): no data
- Method of breeding: bred in RCC since 1992 in reconstituted water of the quality identical to the water used in the tests and under temperature and light conditions identical to those of the test.
- Feeding during test: No

ACCLIMATION
- Acclimation period: no

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

2.5 mmol/L (= 250 mg/L as CaCO3)

Test temperature:

20°C

pH:

7.8

Dissolved oxygen:

between 8.5 and 8.8 mg/L

Salinity:

not applicable

Nominal and measured concentrations:

Nominal loading rate: 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type : 100 mL glass beakers
- Material, size, headspace, fill volume: vessels filled with 50 mL of test medium
- Aeration: The test water was aerated prior to the start of the study until oxygen saturation was reached.During the test period, the test water was not aerated.
- Type of flow-through (e.g. peristaltic or proportional diluter): none (static test)
- Renewal rate of test solution (frequency/flow rate): no renewal (static test)
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: 2 mL of medium per daphnia

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted test water : analytical grade salts dissolved in purified water
- Alkalinity: 0.8 mmol/L
- Ca/Mg ratio (mol): 4:1 (based on molarity)
- Na/ K ratio (mol): 10:1 (based on molarity)
- Culture medium different from test medium: no
- Intervals of water quality measurement: The pH values, the dissolved oxygen concentrations and the water temperature were determined at the start and at the end of the test in the control and the test medium. The appearance of the test medium was also recorded at the start of the test and after 24 and 48 hours.
- No further data

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: a 16 hour light to 8 hour dark with a 30 minute transition period.
- Light intensity: between 470 and 640 lux

EFFECT PARAMETERS MEASURED :
The daphnids were observed for immobility after 24 and 48 hours of exposure (daphnids not being able to swim within 15 seconds after gentle agitation of the test beaker are considered to be immobilized).
The NOELR and EL0 were determined directly from the raw data. The EL50 and EL100 could not be determined due to the absence of a toxic effect of the test item in this test.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: not relevant (limit test)
- Range finding study: yes
- Test concentrations of the range finding study: no data
- Results used to determine the conditions for the definitive study: no mortality at the undiluted loading rate.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

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. As a result, cerium dioxide is not acutely toxic for daphnids up to its solubility limit into water.

The analyticaly measured concentrations of cerium in the test medium samples taken at the start and at the end of the test were below the LOQ (< 1 µg/L)

No remarkable observations concerning the appearance of the test medium.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- 48h-EC50: 0.67 mg/L (acceptance range : 0.53 - 1.1 mg/L) (potassium dichromate)

Reported statistics and error estimates:

None as no adverse effect was observed

Effect of OPALINE DE POLISSAGE on the Mobility of Daphnia magna:

Treatment (Loading rate)	No. of daphnids tested	Immobilized daphnids after 24 hours	Immobilized daphnids after 48 hours
Control	20	No.: 0 %: 0	No.: 0 %: 0
Undiluted filtrate (100 mg/L)	20	No.: 0 %: 0	No.: 0 %: 0

Validity criteria fulfilled:

yes

Conclusions:

Cerium dioxide had no acute toxic effects on Daphnia magna up to its solubility limit in the test water at the loading rate of 100 mg/L under the present test conditions.

Executive summary:

The 48hr-acute toxicity of cerium dioxide to Daphnia magna was studied under static conditions according to the EU Commission Directive 92/69/EEC, Part C.2 (1992) and the OECD Guideline for Testing of Chemicals, N°202 (2004). Daphnids were exposed to control and test chemical at nominal concentration of 100 mg /L (loading rate) for 48 hr. Mortality/immobilization were observed daily. In the control and at the loading rate of 100 mg/L, no immobilized test organisms were determined during the test period of 48 h. Thus, the 48 hour EL50 and the 48 hour NOEC were > 100 mg/L. 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 dioxide is not acutely toxic for daphnids up to its solubility limit into water.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

not specified

Analytical monitoring:

no

Details on sampling:

none

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Cerium oxide was poorly soluble in water. According the Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures (2002), a saturated solution of these high purity cerium oxide was prepared. No other details.
- Controls: yes, test water without test item
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no data
- No further data

Test organisms (species):

Daphnia magna

Details on test organisms:

No data

Test type:

not specified

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

No data

Test temperature:

No data

pH:

No data

Dissolved oxygen:

No data

Salinity:

No data

Nominal and measured concentrations:

Nominal concentration: 100% (v/v saturated solution) cerium oxide

Details on test conditions:

TEST SYSTEM
- Test vessel: no data
- Aeration: no data
- Type of flow-through (e.g. peristaltic or proportional diluter): no data
- Renewal rate of test solution (frequency/flow rate): no data
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- No. of vessels per positive control (replicates): 2
- Biomass loading rate: no data

TEST MEDIUM / WATER PARAMETERS
No data

EFFECT PARAMETERS MEASURED : The daphnids were observed for immobility after 24 and 48 hours of exposure.
The 48-hour EC50 and the 48-hour NOEC were determined.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: not applicable (limit test)
- Justification for using less concentrations than requested by guideline: not applicable (limit test)
- Range finding study: none

Reference substance (positive control):

yes

Remarks:

potassium dichromate (0.32; 0.56; 1.0 mg/l)

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 other: % (v/v) saturated solution of cerium oxide

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 other: % (v/v) saturated solution of cerium oxide

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

There were no toxic effects observed i.e. no immobilisation occurred at any time period during the test.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- The 48h-EC50 was not calculated in the publication. It should be noticed that no adverse effect was observed at 0.56 mg/L, while 100% immobility was observed at the highest tested (1.0 mg/L) (potassium dichromate)

Reported statistics and error estimates:

No data

Effect of Cerium oxide on the Mobility of Daphnia magna:

Nominal concentration (% v/v saturated solution)	No. of daphnids tested	Immobilized daphnids after 24 hours	Immobilized daphnids after 48 hours
Control	40	No.: 0 %: 0	No.: 0 %: 0
100% cerium oxide	40	No.: 0 %: 0	No.: 0 %: 0

Validity criteria fulfilled:

not specified

Conclusions:

Cerium oxide had no acute toxic effects on Daphnia magna at 100% (v/v) saturated solution.

Executive summary:

The 48hr-acute toxicity of cerium oxide to Daphnia magna was studied according to the OECD Guideline for Testing of Chemicals, N°202 (2004). Daphnids were exposed to control and test chemical at 100% (v/v) saturated solution for 48 hr. Immobilization were observed during the test. In the control and at 100% (v/v) saturated solution, no immobilized test organisms were determined during the test period of 48 h. Thus, the 48 hour EC50 and the 48 hour NOEC were > 100% (v/v) saturated solution.

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

From JAN 2007 to 26 APR 2007

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Remarks:

The study was conducted according to an american guideline, without reference to the application of GLP and without analytical monitoring of the test substance. However, the experimental details and results were well described.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: U.S. Environmental Protection Agency. 2002a. Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms. EPA-821-R-02-012. Office of Water, Washington D.C.

Deviations:

no

GLP compliance:

not specified

Analytical monitoring:

no

Details on sampling:

none

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Test solution was prepared by combining Cerium oxide with moderately hard reconstituted lab water. Cerium oxide was insoluble, which resulted in highly turbid solution. As a result, in order to eliminate any toxic effects due to high suspended solids, the solids were allowed to settle before using the solution in the test. The stock solution was prepared and allowed to mix for 24 hours. After 24 hours of mixing, it was removed from the stir plate and the suspended solid was allowed to settle for an additional 24 hours. The stock solution (100 g/L) was then decanted and used to prepare the tests solutions.
- Controls: yes, reconstituted water without test item
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no data
- No further data

Test organisms (species):

Ceriodaphnia dubia

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain: no data
- Source: Organisms were cultured in-house.
- Age at study initiation : < 24 hours old
- Lenght / Weight at study initiation : no data
- Method of breeding: no data
- Feeding during test : Organisms were fed YCT and Selenastrum 2 hours prior to test initiation, but were not fed for the duration of the test.
- No further data

ACCLIMATION
- Acclimation period: yes
- Acclimation conditions : cultured in reconstituted water
- No further data

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

80-98 mg CaCO3/L

Test temperature:

20.0 ± 1.0°C

pH:

7.85 - 8.12

Dissolved oxygen:

7.0 - 7.5 mg O2/L

Salinity:

not applicable

Nominal and measured concentrations:

Nominal concentrations: 12500, 25000, 50000 mg/L

Details on test conditions:

The test was performed twice on the same day.

TEST SYSTEM
- Test vessel: 30 ml disposable plastic cup filled with 25 ml test solution
- Aeration: no data
- Type of flow-through (e.g. peristaltic or proportional diluter): none (semi-static test)
- Renewal rate of test solution (frequency/flow rate): after 24 hours of exposure
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: no data


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The reconstituted lab water was prepared using ultra-pure deionized water combined with reagent grade chemicals and followed the standard EPA recipe, with a slight modification to increase the hardness to approximately 100 mg/L.
- Alkalinity: 44-64 mg CaCO3/L
- Conductivity: 324-349 µmho/cm
- Total dissolved solids: 155-167 mg/L
- Ammonia: 0.12-0.32 mg NH3/L
- Intervals of water quality measurement: Total hardness (as mg CaCO3/L), pH, alkalinity (as mg CaCO3/L), conductivity, total dissolved solids, ammonia, and dissolved oxygen were measured in all concentrations at test initiation. Temperature, conductivity, pH, and dissolved oxygen were measured daily in each concentration.
- No further data

OTHER TEST CONDITIONS
- Photoperiod: 16L:8D light cycle
- Light intensity: 50-100 ft-c light intensity

EFFECT PARAMETERS MEASURED : The daphnia acute bioassay measure survivability to determine the Lethal Concentration for 50% of the organisms, also known as the LC50.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Justification for using less concentrations than requested by guideline: no data
- Range finding study: yes
- Test concentrations: 12500, 25000, 50000 mg/L
- Results used to determine the conditions for the definitive study: no mortality at 12500, 25000, 50000 mg/L

Reference substance (positive control):

not specified

Remarks:

Reference toxicity tests were conducted monthly to ensure consistent organism quality. No further information.

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

> 50 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Results with reference substance (positive control):

no data

Reported statistics and error estimates:

No data

Effect of Cerium oxide on the Mortality of Ceriodaphnia dubia:

Nominal concentration (mg/L)	0	12500	25000	50000
Test A: Alive/Exposed % survival	20/20 100	19/20 95	20/20 100	14/20 70
Test B: Alive/Exposed % survival	19/20 95	19/20 95	18/20 90	20/20 100

Validity criteria fulfilled:

not specified

Conclusions:

Cerium oxide had no acute toxic effect on Ceriodaphnia dubia up to 50000 mg/L.

Executive summary:

The 48hr-acute toxicity of cerium oxide to Ceriodaphnia dubia was studied according to the US EPA Method EPA-821 -R-02 -012 (2002). Ceriodaphnia dubia were exposed to control and test chemical at 12500, 25000 and 50000 mg/L for 48 hr. Mortality were observed during the test. No significant mortality was observed during the test period of 48 h at any concentration tested. Thus, the 48 hour LC50 was >50000mg/L.

Reference 4

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: :

Remarks:

Some tables and figures of the publication report results on bulk cerium dioxide. However, the article primarily deals with the nanoparticle form, and no experimental detail is given concerning the experiment with the micrometric ones. Therefore, a reliability 4 was attributed to this data.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

No data are available on the bulk form. As results are presented concomittantly with those on nanoparticles, one can expect that the same experimental protocol was applied (i.e. OECD method 202).

GLP compliance:

not specified

Analytical monitoring:

not specified

Details on sampling:

No data on the analytical monitoring of concentrations of bulk cerium dioxide during the test.

Vehicle:

not specified

Details on test solutions:

No data are available on the bulk form.

Test organisms (species):

Daphnia magna

Details on test organisms:

No data are available concerning the organisms tested during the experiment on the bulk form.

Test type:

not specified

Water media type:

freshwater

Total exposure duration:

48 h

Hardness:

No data

Test temperature:

No data

pH:

No data

Dissolved oxygen:

No data

Salinity:

Not applicable

Nominal and measured concentrations:

No data are available on the bulk form.

Details on test conditions:

No data are available on the bulk form.

Reference substance (positive control):

not specified

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

No further data.

Validity criteria fulfilled:

not specified

Conclusions:

Based on the limited details provided, cerium dioxide does not present acute toxicity for daphnids.

Executive summary:

In this publication primarily dealing with nanoparticulate cerium dioxide, some results are given concerning the bulk form. A 48-hour NOEC superior to 1000 mg/L based on immobility was reported; implying that bulk cerium dioxide does not present acute toxicity for Daphnia magna.

Reference 5

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: The level of details provided in the publication is considerably to low to conclude on its reliability.

Principles of method if other than guideline:

No data except that daphnids were exposed for 96 hours to test chemical.

GLP compliance:

not specified

Analytical monitoring:

no

Details on sampling:

No analytical monitoring of the test substance concentration during the test

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Particles were prepared by sonicating for 30 minutes in EPA water containing 0.01 - 10 µg/mL of particles.
- Controls: Yes, EPA water without the addition of particles.
No further data.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Age at study initiation (mean and range, SD): no data, except that neonates were used.
No further data.

ACCLIMATION
No data.

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

No data

Test temperature:

No data

pH:

No data

Dissolved oxygen:

No data

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentrations: 0.01 to 10 mg/L

Details on test conditions:

TEST SYSTEM
No data

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: EPA medium
No further data

OTHER TEST CONDITIONS
No data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable)
Endpoints assessed included lethality and shedding of the carapace.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: No data
- Range finding study: No data

Details on results:

No mortality was observed among the daphnids exposed to 0.01 to 10 mg/L.

Validity criteria fulfilled:

not specified

Conclusions:

Based on the limited details provided, cerium dioxide does not present acute toxicity for daphnids.

Executive summary:

The impacts of cerium dioxide were investigated on Daphnia magna assessing mortality when exposed for 96 hours to concentrations ranging from 0.01 to 10 mg/L. No mortality was observed among the daphnids exposed to the different concentrations.

Description of key information

The 48-hour EL50 (Daphnia magna) of the bulk form of cerium dioxide is > 100 mg/L based on the mobility. Hence, the bulk form of cerium dioxide is not harmful for the daphnids.

Additional information

Five experimental studies are available. One of them (RCC, 2007), quoted as reliability 1 according to Klimisch, was selected as a key study; the other ones of reliability 2 (Park et al, 2007a and Lambert, 2007) and 4 (Van Hoecke et al., 2009a, Gaiser et al., 2009) gave consistent results and were selected as supporting studies. All of these data concluded that the bulk form of cerium dioxide was not acutely harmful to daphnids.