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EC number: 909-709-8 | CAS number: -
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Long-term toxicity to aquatic invertebrates
Administrative data
Link to relevant study record(s)
- Endpoint:
- long-term toxicity to aquatic invertebrates
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- supporting study
- Justification for type of information:
- Read across from studies performed with both micrometric and nanometric cerium dioxide. The read across justification document is attached in IUCLID Section 13.
- Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across source
- Remarks on result:
- other: Based on the results from studies conducted with micrometric and nanometric cerium dioxide, it can be concluded that no effects resulting in classification are expected for the reaction mass of cerium dioxide and zirconium dioxide either.
- Endpoint:
- long-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 with acceptable restrictions
- Remarks:
- The study was conducted according to the OECD internationally recognised guideline, without reference to the application of GLP and without analytical monitoring of the test material. However, the experimental details and results were well described.
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 211 (Daphnia magna Reproduction Test)
- Deviations:
- no
- 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:
- - Method: Experimental test concentrations were prepared by dropwise addition of the cerium dioxide nanoparticle stock suspensions to the test medium adjusted to pH 4 using a 1 M HCl solution, while stirring. Subsequently, the pH of the test suspensions was adjusted to 7.4. Prior to pH adjustment, 750 mg/L MOPS (3-(N-morpholino)propanesulfonic acid) buffer was added to the media.
- Control: yes (test water without test item)
No further data - Test organisms (species):
- Daphnia magna
- Details on test organisms:
- TEST ORGANISM
- Common name: Water flea
- Source: no data
- Age of parental stock: no data
- Feeding during test: yes
- Food type: a mixture of the algae Pseudokirchneriella subcapitata and Chlamydomonas reinhardtii in a 3:1 ratio
- Amount: As the organisms grew, increasing amounts of food were supplied: from day 1 to 7, from day 8 to 14 and from day 15 to 21 each daphnid was fed 250, 500 and 750 µg dry weight of algae mixture per day, respectively.
- Frequency: daily
ACCLIMATION
No data - Test type:
- semi-static
- Water media type:
- freshwater
- Limit test:
- no
- Total exposure duration:
- 21 d
- Hardness:
- No data
- Test temperature:
- 20 +/- 1°C
- pH:
- 7.4
- Dissolved oxygen:
- No data
- Salinity:
- Not applicable
- Nominal and measured concentrations:
- Nominal concentrations: 0, 18, 32, 56 and 100 mg/L
- Details on test conditions:
- TEST SYSTEM
- Test vessel: polyethylene cups containing 50 mL of control solution or test suspension.
- Type of flow-through (e.g. peristaltic or proportional diluter): not applicable (semi-static test).
- Renewal rate of test solution: The medium was renewed three times a week.
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): 10
No further data.
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M4 medium.
No further data
OTHER TEST CONDITIONS
- Adjustment of pH: The pH of the stock suspension was adjusted to 7.4 before introduction into the test vessels. The test vessels were not subjected to pH adjustment.
- Photoperiod: 12-hour photoperiod
- Light intensity: no data
EFFECT PARAMETERS MEASURED:
- Three times a week, in the same time of medium renewal, parent mortality and offspring number were recorded.
- The daphnid size was measured after seven days of exposure and the net reproduction was calculated at the end of the exposure period.
- To see the potential effect of a lack of food due to complexation with cerium dioxide nanoparticles, the algal cell density was measured. (see "Any other information on materials and methods incl. tables")
RANGE-FINDING STUDY
no data - Duration:
- 21 d
- Dose descriptor:
- NOEC
- Effect conc.:
- 32 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- other: survival
- Remarks on result:
- other: Cerium dioxide diameter: 14 nm
- Duration:
- 21 d
- Dose descriptor:
- LOEC
- Effect conc.:
- 56 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- other: survival
- Remarks on result:
- other: Cerium dioxide diameter: 14 nm
- Duration:
- 21 d
- Dose descriptor:
- NOEC
- Effect conc.:
- < 18 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- reproduction
- Remarks on result:
- other: Cerium dioxide diameter: 14 nm
- Duration:
- 21 d
- Dose descriptor:
- LOEC
- Effect conc.:
- 18 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- reproduction
- Remarks on result:
- other: Cerium dioxide diameter: 14 nm
- Duration:
- 21 d
- Dose descriptor:
- NOEC
- Effect conc.:
- 32 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- other: survival
- Remarks on result:
- other: Cerium dioxide diameter: 20 nm
- Duration:
- 21 d
- Dose descriptor:
- LOEC
- Effect conc.:
- 56 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- other: survival
- Remarks on result:
- other: Cerium dioxide diameter: 20 nm
- Duration:
- 21 d
- Dose descriptor:
- NOEC
- Effect conc.:
- < 18 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- reproduction
- Remarks on result:
- other: Cerium dioxide diameter: 20 nm
- Duration:
- 21 d
- Dose descriptor:
- LOEC
- Effect conc.:
- 18 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- reproduction
- Remarks on result:
- other: Cerium dioxide diameter: 20 nm
- Duration:
- 21 d
- Dose descriptor:
- NOEC
- Effect conc.:
- 56 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- other: survival
- Remarks on result:
- other: Cerium dioxide diameter: 29 nm
- Duration:
- 21 d
- Dose descriptor:
- LOEC
- Effect conc.:
- 100 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- other: survival
- Remarks on result:
- other: Cerium dioxide diameter: 29 nm
- Duration:
- 21 d
- Dose descriptor:
- NOEC
- Effect conc.:
- 18 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- reproduction
- Remarks on result:
- other: Cerium dioxide diameter: 29 nm
- Duration:
- 21 d
- Dose descriptor:
- LOEC
- Effect conc.:
- 32 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- reproduction
- Remarks on result:
- other: Cerium dioxide diameter: 29 nm
- Details on results:
- - Characterisation of nanoparticles:
The suspensions appear turbid within an hour of suspension preparation, indicating particle aggregation to diameters ranging from 425 to 549 nm. Hence, the organisms were exposed to cerium dioxide nanoparticles aggregates.
- Biological results:
Significant adverse effects were found in the 18 – 100 mg/L concentrations range. In the treatments exposed to 56 and 100 mg/L of 14-nm and 20-nm cerium dioxide nanoparticles, all daphnids died within nine days. Exposure to 100 mg/L of 29-nm cerium dioxide nanoparticles induced 100 % mortality. However, the mortality reported in the presence of cerium dioxide nanoparticles could be indirectly caused by a lack of food for the three following reasons:
- (1) the cerium dioxide nanoparticles aggregates clustered together with algal cells, resulting in pale (during the first week) to green (during the third week) clumps with diameters exceeding 1mm;
- (2) the daphnids exposed to cerium dioxide nanoparticles were smaller than control individuals. Mean length (+/- standard deviation) of the test organisms exposed to 100 mg/L of 14, 20 and 29 nm cerium dioxide nanoparticles after 7 days was: 1.06 (+/- 0.18), 1.17 (+/- 0.27) and 1.27 (+/- 0.04) mm, respectively, while daphnids in the control individuals measured 2.484 (+/- 0.02) mm;
- (3) algae were absent from the gut of cerium dioxide nanoparticles-exposed organisms.
These observations suggest that decreased reproduction and eventual mortality was due to the inability to take up sufficient food.
Such hypothesis is supported by the results of the algal cell density measurements which showed that when agglomerates of nanoparticulate cerium dioxide were mixed with the algal cells, both clustered together and sedimented (see "Any other information on materials and methods incl. tables").
In addition to the lethal effects, impacts on reproduction were observed. Significant alterations of this endpoint were observed at 18 mg/L in the presence of 14- and 20-nm particles and at 32 mg/L in the presence of 29-nm particles. It was not clear if this effect on reproduction was linked to a lack of food. - Validity criteria fulfilled:
- not specified
- Conclusions:
- Significant adverse effects were found on both survival and reproduction in the 18 - 100 mg/L concentrations range, with the following NOECs:
- Cerium dioxide nanoparticles, 14- and 20-nm diameter:
21d-NOEC = 32 mg/L, based on survival
21d-NOEC < 18 mg/L, based on reproduction
- Cerium dioxide nanoparticles, 29-nm diameter:
21d-NOEC = 56 mg/L, based on survival
21d-NOEC = 18 mg/L, based on reproduction
However, it is very likely that such effects could be linked to food deprivation due to complexation of nutritive algal cells with the nanoparticles of cerium dioxide. - Executive summary:
The effect of cerium dioxide nanoparticles on the survival and reproduction of Daphnia magna was investigated over 21 days following the OECD Guidelines for Testing of Chemicals, No. 211 (1998). Daphnids were exposed to control, and test chemicals at nominal concentrations of 18, 32, 56 and 100 mg/L at three nanoparticle sizes (14, 20 and 29 nm). Parent mortality and offspring number were recorded. The daphnids size was measured after seven days of exposure and the net reproduction was calculated at the end of the exposure period.
Significant adverse effects were found for the survival in the 18 - 100 mg/L concentrations range. In addition to the lethal effects, impacts on reproduction were observed.
The following NOEC could thus be deduced:
- Cerium dioxide nanoparticles, 14 - and 20 -nm diameter:
21d-NOEC = 32 mg/L, based on survival
21d-NOEC < 18 mg/L, based on reproduction
- Cerium dioxide nanoparticles, 29-nm diameter:
21 d-NOEC = 56 mg/L, based on survival
21d-NOEC = 18 mg/L, based on reproduction
However, it is very likely that such effects could be linked to food deprivation due to complexation of nutritive algal cells with the nanoparticles of cerium dioxide.
- Endpoint:
- long-term toxicity to aquatic invertebrates
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Study period:
- from 21-DEC-2007 to 27-FEB-2009
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 211 (Daphnia magna Reproduction Test)
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Analytical monitoring:
- yes
- Details on sampling:
- - Concentrations:
Triplicate samples were taken from the test media of all test concentrations (loading rate of 100 mg/L and dilutions 1:3.2, 1:10, 1:32 and 1:100) and from the control at the start of the first treatment period (Day 0), at a treatment period in the second week (Day 7), and at a treatment period in the last week (Day 16). The following samples were taken in triplicate at the end of two test medium renewal periods of 48 hours (Days 2 and 9) and at the end of one renewal period of 72 hours (Day 19):
a) Samples with food, taken from the actual test by combining the contents of the test beakers after the end of the treatment period.
b) Samples without food and test animals incubated during the renewal periods under the test conditions.
The concentrations of cerium were measured in two of the triplicate test media samples from the highest test concentration (loading rate of 100 mg/L) which was determined to be the 21-day NOELR.
- Sampling method: data not available
- Sample storage conditions before analysis: immediately after sampling, the samples were acidified with 10% (v/v) nitric acid (HNO3, 65% Suprapur, Merck) to stabilise the samples during storage. Then the samples were stored in PE flasks at ambient temperature and protected from light until analysis. - Vehicle:
- no
- Details on test solutions:
- PREPARATION AND APPLICATION OF TEST SOLUTION
- Method:
Due to the low water solubility of the test item, a saturated solution of the test item with the loading rate of 100 mg/L was tested as the highest test concentration and was used as a stock solution for preparation of the test media of lower test concentrations (dilutions 1:3.2, 1:10, 1:32 and 1:100). Additionally, a control (test water without test item) was tested in parallel.
The test method is based on the OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures.
Seven days before the start of the test and seven days prior to each test medium renewal, a dispersion of the test item with the loading rate of 100 mg/L was prepared by dispersing 200 mg (effective weights: 200.0-201.4 mg) of the test item in 2000 mL of test water. The test item was mixed into the test water as homogeneously as possible using ultrasonic treatment for 15 minutes and intense stirring. No auxiliary solvent or emulsifier was used. The dispersions were stirred on magnetic stirrers at room temperature in the dark over six days. Then, the stirrers were switched off in order to allow the non-dissolved test item to deposit at the bottom of the stirring vessel. The contact time of the test item and the test water for equilibration (i.e. stirring time and deposition period) was 7 days.
The equilibrated test medium (saturated solution) was carefully separated from the non-dissolved test item. The saturated solution was used as the highest test concentration. Additionally, adequate volumes of the saturated solution were diluted with test water for the preparation of the test media with lower test item concentrations.
- Eluate: no
- Differential loading: yes
- Controls: test water without test item
- Evidence of undissolved material (e.g. precipitate, surface film, etc): yes, on the bottom of the stirring vessel, but not in the final test solution - 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 of parental stock (mean and range, SD): < 24 hours. These daphnids originated from parental daphnids that were at least 14 days old but no older than 4 weeks, and were not first brood progeny.
- Feeding during test
- Food type: a food mixture containing a suspension of green algae of the species Scenedesmus subspicatus (freshly grown in the Harlan laboratories) and a fish food suspension.
- Amount:
The carbon contents of the algal and fish food suspensions were determined using a Shimadzu TOC 5000A Analyzer. The food amounts were based on the measured concentrations of total organic carbon (TOC) in the food suspensions and consisted of 50% algae and 50% fish food (based on TOC). The amounts of TOC fed per test animal and day were as follows:
Day 0-4: 0.10 mg TOC / Daphnia
Day 5-13: 0.15 mg TOC / Daphnia
Day 14-20: 0.20 mg TOC / Daphnia
- Frequency: daily
ACCLIMATION
- Acclimation period: no
- Test type:
- semi-static
- Water media type:
- freshwater
- Limit test:
- no
- Total exposure duration:
- 22 d
- Remarks on exposure duration:
- It was expected at the observation of the test animals on Day 21 that some test animals would release their offspring from brood pouch in the next hours. Therefore the test was extended for 24 hours.
- Post exposure observation period:
- none
- Hardness:
- 2.5 mmol/L (= 250 mg/L as CaCO3)
- Test temperature:
- 20°C
- pH:
- between 7.5 to 8.0
- Dissolved oxygen:
- at least 7.9 mg/L
- Salinity:
- not applicable
- Nominal and measured concentrations:
- loading rate of 100 mg/L and dilutions 1:3.2, 1:10, 1:32 and 1:100
- Details on test conditions:
- TEST SYSTEM
- Test vessel:
- Type: 100 mL glass beakers covered with glass plates to reduce the loss of water by evaporation and to avoid the entry of dust into the solutions
- Material, size, headspace, fill volume: vessels containing 80 mL of test medium
- Aeration: Before use, the test water was aerated until oxygen saturation. During the test, the test media were not aerated.
- Type of flow-through (e.g. peristaltic or proportional diluter): none (semi-static test)
- Renewal rate of test solution (frequency/flow rate): three times per week
- No. of organisms per vessel: Each test animal was kept individually in test vessel.
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): 10
- Biomass loading rate: 80 ml of medium per parental daphnid.
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted test water: analytical grade salts dissolved in purified water
- Alkalinity: 0.9 mmol/L
- Ca/Mg ratio (mol): no data
- Culture medium different from test medium: no
- Intervals of water quality measurement: At the beginning and end of each test medium renewal period, the pH and dissolved oxygen concentrations were measured in one replicate of each test concentration and the control. At the same time, the water temperature was measured in one of the control replicates. Additionally, the room temperature was continuously monitored. The appearance of the test media was recorded at the beginning and end of each test medium renewal period.
- 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 500 and 630 lux
EFFECT PARAMETERS MEASURED :
Each working day, the test replicates were observed for mortality of the parental daphnids and the presence of juveniles. The offspring were counted and removed three times per week at the renewal of the test media. At the same dates, the test beakers were also checked for the presence of aborted eggs or dead offspring.
The reproduction rate was calculated as the total number of living offspring produced per parent female surviving until the end of the test.
The mean reproduction rates of the daphnids at the test concentrations were compared to the control by multiple Williams’ tests. No EL values for the inhibition of the reproduction rate could be calculated since no effect was determined on the reproduction of the daphnids up to the highest concentration tested.
RANGE-FINDING STUDY
Test concentrations / Results used to determine the conditions for the definitive study: The choice of the test concentrations was based on the results of the acute toxicity test with Daphnia magna (RCC Study Number A17493). Concentrations of the test item far above the water solubility or loading rates above 100 mg/L were not tested in accordance with the test guidelines. - Reference substance (positive control):
- no
- Duration:
- 22 d
- Dose descriptor:
- NOELR
- Effect conc.:
- >= 100 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- other: survival and reproduction
- Duration:
- 22 d
- Dose descriptor:
- LOELR
- Effect conc.:
- > 100 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- other: survival and reproduction
- Details on results:
- Analytical Results :
The concentration of cerium in test medium samples was below the limit of quantification of the analytical method (0.004 or 0.02 µg/L) with the exception of two samples taken at the end of the first test medium renewal period from the test medium of the actual test. In these samples concentrations of cerium of 0.2 mg/L were found.
The saturated solution used as test medium was prepared by sedimentation of the undissolved test item until the supernatant appeared to be a clear solution (24 hours). The test medium was not filtered on the request of the Sponsor. The wide range of measured concentrations of the test item was considered to be caused by very fine particles of the test item which were obviously still present in the supernatant after the deposition period. Thus, the test medium contained the maximum concentration of dissolved test item and very fine undissolved test item particles. The cerium found in the two samples was considered to originate from particles which were present in these samples.
Biological results:
In the control and at all test concentrations up to and including the loading rate of 100 mg/L, the survival of the test animals was at least 80% or higher at the end of the test. Thus, the survival of Daphnia magna over 21 days was not affected by the test item up to and including the highest test concentration (loading rate of 100 mg/L).
The first young offspring released from their parent animals were recorded in the control and at all test concentrations at observation on Day 8. Thus, the time of the first brood was not affected by the test item up to and including the loading rate of 100 mg/L.
The mean reproduction rate of the daphnids in the control was 100.4 ± 16.7 living offspring per adult (mean ± standard deviation). The mean reproduction rates of the exposed daphnids were between 104 and 121% of the reproduction in the control and no concentration-effect relationship was determined. No significant inhibitory effect of the test item on the mean reproduction rate was determined up to and including the highest test concentration (Williams’ test, one-sided, alpha = 0.05).
No visible abnormalities were observed in the test animals during the test.
No adverse effect, neither in terms of survival, nor in terms of reproduction, 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 does not exhibit any chronic toxicity to daphnids up to its solubility limit into water.
General results:
No remarkable observations were made concerning the appearance of the test media. All test media were clear throughout the test medium renewal periods. - Results with reference substance (positive control):
- none
- Reported statistics and error estimates:
- The mean reproduction rates of the daphnids at the test concentrations were compared to the control by multiple Williams' test.
- Validity criteria fulfilled:
- yes
- Remarks:
- Control's survival rate = 80%, and control's mean reproduction rate > 60
- Conclusions:
- The test item cerium dioxide had no toxic effect on survival and reproduction of Daphnia magna after the exposure period of 22 days up to the loading rate of 100 mg/L. Thus, the NOELR of the test item was determined to be at least the loading rate of 100 mg/L. The LOELR was above the loading rate of 100 mg/L.
- Executive summary:
The effect of the test item cerium dioxide on the survival and reproduction of Daphnia magna was investigated in a semi-static test over 22 days following the OECD Guidelines for Testing of Chemicals, No. 211 (1998) and the EU Commission Directive 92/69/EEC, C.20 (2001). Daphnids were exposed to control, and test chemical at nominal concentration of 100 mg of dry substance /L (loading rate) and the dilutions 1:3.2, 1:10, 1:32 and 1:100 of the saturated solution. The mortality and reproduction of the daphnids were compared with the corresponding parameters in the control and symptoms of toxicity were recorded.
The test item cerium dioxide had no toxic effect on survival and reproduction of Daphnia magna after the exposure period of 22 days up to the loading rate of 100 mg/L. Thus, the NOELR of the test item was determined to be at least the loading rate of 100 mg/L. The LOELR was above the loading rate of 100 mg/L. As no adverse effect, neither in terms of survival, nor in terms of reproduction, 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 does not exhibit any chronic toxicity to daphnids up to its solubility limit into water.
This study is classified as acceptable and satisfies the guideline requirements for a chronic toxicity study with freshwater invertebrates.
- Endpoint:
- long-term toxicity to aquatic invertebrates
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 4 (not assignable)
- Rationale for reliability incl. deficiencies:
- documentation insufficient for assessment
- 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 details 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
- Principles of method if other than guideline:
- No data are available on the bulk form. As results are presented concommittantly with those on nanoparticles, one can expect that the same experimental protocol was applied (i.e. OECD method 211).
- GLP compliance:
- not specified
- Analytical monitoring:
- not specified
- Details on sampling:
- No data on the analytical monitoring of the concentrations of the 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:
- 21 d
- 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:
- 21 d
- Dose descriptor:
- NOEC
- Effect conc.:
- >= 100 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- mortality
- Duration:
- 21 d
- Dose descriptor:
- NOEC
- Effect conc.:
- 32 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- reproduction
- Details on results:
- Bulk cerium dioxide caused a 40% decrease in reproduction at the maximum test concentration (i.e. nominal concentration: 100 mg/L).
- Validity criteria fulfilled:
- not specified
- Conclusions:
- Based on the limited details provided, cerium dioxide did not show any effect on daphnids survival after a 21-day exposure to concentrations up to 100 mg/L, but induced a reproduction decrease of 40% at the highest concentration tested.
- Executive summary:
In this publication primarily dealing with nanoparticulate cerium dioxide, some results are given concerning the bulk form. Based on survival and reproduction, 21-day NOECs of >= 100 mg/L and 32 mg/L are reported for Daphnia magna, respectively.
- Endpoint:
- long-term toxicity to aquatic invertebrates
- Data waiving:
- other justification
- Justification for data waiving:
- other:
Referenceopen allclose all
Algal cell density measurements:
Table 1: Algal cell density measured 24 hours after media refreshment. Results are expressed as x 104 c/mL and as percentage relative to (rt) the start and to the cell density in the control after 24 hours. The standard deviation is given in between brackets.
|
Mixed |
All Cerium dioxidesedimentedafter 24h |
||
Concentration (mg/L) |
Start (0h) |
24h |
rt start |
rt control |
x 104c/mL |
% |
% |
||
Control |
5.45 (0.29) |
2.17 (0.19) |
39.9 (6.2) |
100.0 (9.9) |
14 nm |
||||
18 |
5.61 (0.27) |
0.10 (0.04) |
1.9 (0.7) |
4.8 (1.8) |
32 |
5.92 (0.87) |
0.05 (0.00) |
0.8 (0.1) |
2.2 (0.3) |
56 |
5.21(0.26) |
0.04 (0.02) |
0.8 (0.4) |
2.0 (1.0) |
100 |
5.88 (0.15) |
0.04 (0.01) |
0.8 (0.1) |
2.0 (0.3) |
20 nm |
||||
18 |
5.60 (0.02) |
0.11(0.02) |
1.9 (0.3) |
4.9 (0.8) |
32 |
5.88 (0.21) |
0.01(0.00) |
0.2 (0.0) |
0.6 (0.1) |
56 |
5.25 (0.09) |
0.05 (0.00) |
0.9 (0.1) |
2.1 (0.2) |
100 |
5.77 (0.18) |
0.05 (0.02) |
0.9 (0.4) |
2.5 (1.1) |
29 nm |
||||
18 |
5.59 (0.48) |
0.23 (0.04) |
4.2 (0.7) |
10.7 (1.8) |
32 |
5.59 (0.35) |
0.01(0.00) |
0.2 (0.1) |
0.5 (0.2) |
56 |
5.09 (0.25) |
0.01(0.01) |
0.2 (0.3) |
0.6 (0.6) |
100 |
5.52 (0.22) |
0.01(0.01) |
0.1 (0.1) |
0.3 (0.2) |
It is clear that within the first 24h, the cell density decreased dramatically to only 100 - 1000 cells/mL at each cerium dioxide nanoparticles concentration, which is about 0.5 - 5% of the algal density in the control after 24h.
When new food was added without resuspending the cerium dioxide agglomerates, the cell did not precipitate severely and could be taken up by Daphnia magna during the next 24h (from t = 24h until t = 48h). However, when after the first 24h the cerium dioxide agglomerates were re-suspended before algae addition, the cell density decreased again during the second 24h period.
Table 2: Algal cell density measured 48 hours after media refreshment. Results are expressed as x 104 c/mL and as a percentage relative to the cell density in the control after 48 hours. The standard deviation is given in between brackets.
|
Not resuspended after 24h |
Resuspended after 24h |
||
Concentration (mg/L) |
Cell density after 48h |
Cell density after 48h |
||
x 104c/mL |
% rtc |
x 104c/mL |
% rtc |
|
Control |
3.52 (0.33) |
100 (13.3) |
4.16 (0.32) |
100 (11.2) |
14 nm |
||||
18 |
2.18 (0.10) |
61.7 (6.4) |
1.50 (0.12) |
36.0 (4.0) |
32 |
1.92 (0.19) |
54.6 (7.4) |
0.24 (0.07) |
5.9 (1.8) |
56 |
1.85 (0.28) |
52.5 (9.5) |
0.03 (0.01) |
0.7 (0.3) |
100 |
1.63 (0.27) |
46.2 (8.8) |
0.01 (0.00) |
0.2 (0.0) |
20 nm |
||||
18 |
2.04 (0.09) |
57.8 (6.0) |
|
|
32 |
2.13 (0.30) |
60.3 (10.2) |
|
|
56 |
2.14 (0.52) |
60.7 (15.8) |
|
|
100 |
1.73 (0.06) |
49.0 (4.9) |
|
|
29 nm |
||||
18 |
2.32 (0.28) |
65.7 (10.0) |
|
|
32 |
2.43 (0.25) |
68.9 (9.7) |
|
|
56 |
2.24 (0.39) |
63.5 (12.6) |
|
|
100 |
2.05 (0.39) |
58.3 (12.4) |
|
|
Thus, it appears that when cerium dioxide nanoparticles agglomerates were mixed with the algal cells, both clustered together and sedimented.
Number of surviving test animals:
Exposure day |
Treatment / Dilution |
|
|
|
|
|
|
Control |
Dilution 1:100 |
Dilution 1:32 |
Dilution 1:10 |
Dilution 1:3.2 |
Saturated solution (loading rate 100 mg/L) |
0 1 2 5 6 7 8 9 12 13 14 15 16 19 20 21 22 |
10 10 10 10 10 10 10 10 9 9 9 9 9 9 9 8 8 |
10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 |
10 10 10 10 10 10 10 10 10 10 9 9 9 9 9 9 9 |
10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 |
10 10 10 10 10 10 9 9 9 9 9 9 9 9 9 9 9 |
10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 |
% surviving on Day 22 |
80 |
100 |
90 |
100 |
90 |
100 |
Total number of living young daphnids produced by all adults (cumulative values):
Exposure day |
Treatment / Dilution |
|
|
|
|
|
|
Control |
Dilution 1:100 |
Dilution 1:32 |
Dilution 1:10 |
Dilution 1:3.2 |
Saturated solution (loading rate 100 mg/L) |
0 1 2 5 6 7 8 9 12 13 14 15 16 19 20 21 22 |
0 0 0 0 0 0 172 172 428 475 475 615 618 719 719 789 884 |
0 0 0 0 0 0 160 160 422 479 480 666 670 842 842 915 1047 |
0 0 0 0 0 0 182 182 482 614 614 761 762 925 925 1056 1139 |
0 0 0 0 0 0 170 170 456 607 607 739 742 910 910 1053 1152 |
0 0 0 0 0 0 185 185 446 586 586 676 676 837 837 1012 1079 |
0 0 0 0 0 0 169 169 382 485 487 589 647 837 837 973 1094 |
% of control(1) |
100.0 |
118.4 |
128.8 |
130.3 |
122.1 |
123.8 |
(1): based on the value of the last exposure day
Number of living offspring produced per surviving adult after 22 days of exposure:
Replicate No. |
Treatment / Dilution |
|
|
|
|
|
|
Control |
Dilution 1:100 |
Dilution 1:32 |
Dilution 1:10 |
Dilution 1:3.2 |
Saturated solution (loading rate 100 mg/L) |
1 2 3 4 5 6 7 8 9 10 |
110 * 75 110 111 119 * 75 104 99 |
100 105 137 112 103 126 105 110 114 35 |
130 137 100 129 137 122 * 108 113 114 |
125 121 81 115 133 135 135 106 97 104 |
123 125 121 120 108 94 118 113 * 135 |
119 106 96 119 124 126 101 86 112 105 |
Mean SD n |
100.4 16.7 8 |
104.7 27.0 10 |
121.1 13.1 9 |
115.2 18.1 10 |
117.4 11.6 9 |
109.4 12.9 10 |
CV % |
16.6 |
25.8 |
10.8 |
15.7 |
9.9 |
11.8 |
% of control |
100.0 |
104.3 |
120.7 |
114.8 |
117.0 |
109.0 |
STAT |
- |
n.s. |
n.s. |
n.s. |
n.s. |
n.s. |
SD: standard deviation
n: number of replicates (surviving adults)
CV %: coefficient of variation in %: (SDx/meanx)x100%
*: test animal died during the test period
STAT: results of a Williams’ test with the mean values of living offspring
(one-sided, alpha = 0.05)
n.s.: mean value not significantly lower than in the control
Description of key information
By analogy with one of its constituents (i.e. cerium dioxide), the reaction mass of cerium dioxide and zirconium dioxide should not show any adverse chronic effect in aquatic invertebrates resulting in classification.
Key value for chemical safety assessment
Additional information
No data is available on the reaction mass. Based on the physicochemical, environmental and ecotoxicological data available on both the reaction mass and its two constituents, the three substances show highly similar intrinsic properties. Therefore, a read across with constituents when data are not available on the reaction mass appears fully relevant.
Studies carried out with cerium dioxide are available and the results can be used to conclude on the chronic toxicity of the reaction mass of cerium dioxide and zirconium dioxide without launching further tests.
Micrometric cerium dioxide: One experimental study (Höger, 2009), scored as Klimisch 1, concluded on the absence of chronic adverse effects on survival and reproduction of daphnids. Another study of reliability 4 is available (Van Hoecke et al., 2009), yielding similar results in terms of survival, but not in terms of reproduction (21d-NOEC = 32 mg/L versus 22d-NOEC ≥ 100 mg/L in the study by Höger, 2009). However, due to the lack of experimental details provided in this study, it is not possible to conclude on its reliability.
Nanometric cerium dioxide: Only one study is available concerning the nanoparticulate form of cerium dioxide. It was scored as Klimisch 2 and conducted according to the OECD guideline (Van Hoecke et al., 2009). Significant effects on survival and reproduction were observed in the range 18 - 100 mg/L. However, due to the complexation of nanoparticles with nutritive algal cells, it cannot be excluded that these effects were linked to food deprivation rather than impacts of nanoparticulate cerium dioxide. Several observations supported this hypothesis:
- The cerium dioxide nanoparticles aggregates clustered together with algal cells.
- The daphnids exposed to cerium dioxide nanoparticles were smaller than control individuals.
- Algae were absent from the gut of cerium dioxide nanoparticles-exposed organisms.
These observations suggest that decreased reproduction and eventual mortality may have been due to the inability to take up sufficient food. Such hypothesis is supported by the results of the algal cell density measurements which showed that when agglomerates of nanoparticulate cerium dioxide were mixed with the algal cells, both clustered together and sedimented.
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