Cerium trinitrate

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:

04 Sept 2012 - 15 Mar 2013

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)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Concentrations of dissolved Ce were determined in at least one of the triplicate samples from each treatment per sampling time.
- Sampling method: Triplicate samples were taken from each treatment at the start and end of each test medium renewal period (after filtration through a membrane filter, Whatman, Type NC45, pore size 0.45 µm).
- Sample storage conditions before analysis: All samples are stored at room temperature in the dark after sampling until analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Due to the low solubility of the test item in the test media, a dispersion with the loading rate of 100 mg/L (based on anhydrous cerium trinitrate) was prepared at the start of the test and before each test medium renewal by dispersing 133.3 mg of the test item (dosing range: 133.2-133.3 mg to take into account the water content in the test item) in 1000 mL of test water. This preparation was supported by ultrasonic treatment for 15 minutes and intense stirring on a magnetic stirrer over 3 hours in the dark, to dissolve a maximum amount of the test item in the dispersion. No auxiliary solvent or emulsifier was used.

An optimal stirring period of 3 hours was chosen based on the results of a pre-experiment, which showed that the solution equilibrium was reached after this time. In this pre-experiment, similar concentrations of dissolved elemental cerium were analytically measured in filtrates after stirring for 3, 24 and 96 hours.

After stirring and pH adjustment, the dispersion of the test item was filtered through a membrane filter (Whatman, Type NC45, pore size 0.45 µm). The undiluted filtrate was used as highest concentrated test medium and as a stock solution for preparation of the test media with lower test concentrations. For preparation of the latter, the filtrate was diluted with pH adjusted test medium.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Strain: Straus
- Source: University of Sheffield / UK in 1992
- Age at study initiation (mean and range, SD): 6-24 hours (not a first brood progeny)
- Feeding during test: no
- Method of breeding: clone has been bred at Harlan Laboratories in reconstituted water of the quality identical to the water quality used in the test

ACCLIMATION
- Type and amount of food: green algae Desmodesmus subspicatus CHODAT, Strain No. 86.81 SAG, supplied by the Collection of Algal Cultures or a mixture of this algal suspension and a commercial fish diet (Tetra Min Hauptfutter)
- Feeding frequency: daphnids are generally fed three times a week

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

250 mg CaCO3/L

Test temperature:

20-21°C

pH:

New test media:
0 h = 6.0-6.4
24 h = 5.9-6.2
Old test media:
24 h = 6.8-7.0
48 h = 6.1-7.1

Dissolved oxygen:

at least 8.1 mg/L

Salinity:

not applicable

Nominal and measured concentrations:

Analytically determined concentrations of dissolved cerium in the test media (control, dilutions 1:16, 1:8, 1:4, 1:2, and the undiluted filtrate) were as follows:
Day 0, 0 h (beginning of the experiment)= < LOQ, 0.294, 0.664, 1.37, 2.82, and 5.58 mg Ce/L
Day 1, 24 h (end of 1st renewal period) = < LOQ, 0.203, 0.124, 0.130, 0.305, and 2.24 mg Ce/L
Day 1, 0 h (beginning of 2nd renewal period) = < LOQ, 1.95, 3.97, 8.02, 17.2, and 33.4 mg Ce/L
Day 2, 24 h (end of second renewal period) = < LOQ, 0.0266, 0.109, 1.56, 9.80 and 30.3 mg Ce/L
Over the test medium renewal periods of 24 h, the concentrations of dissolved Ce decreased (recovery 1.0 to 91% of initially measured concentrations, on average 11 to 65%). Further, the dissolved Ce levels were overall higher during the second renewal period.
Biological results were based on mean measured concentrations calculated as the arithmetic mean of the two geometric means determined for dissolved Ce measured at the start and end of each test medium renewal period.
Mean measured concentrations were as follows (not mentioning the control, for which dissolved Ce was < LOQ):
0.2, 0.5, 2.0, 7.0 and 18.0 mg Ce/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 100-mL glass beakers filled with 50 mL of test medium
- Type (delete if not applicable): covered with glass plates to reduce the loss of water by evaporation and to avoid the entry of dust
- Aeration: The test water was aerated prior to the start of the study. No aeration during the study.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted test water according to ISO 6341
- Ca/mg ratio: 4:1
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Adjustment of pH: 1) adjustment of dispersion to pH 6.0 after the 3-h stirring period using 1 M NaOH, 2) adjustment of test medium (for dilution of the filtrate) to pH 6.0 using 1 M HCl
- Photoperiod: A 16-hour light to 8-hour dark cycle with a 30-minute transition period
- Light intensity: Light intensity during the light period was approximately between 390 and 560 Lux.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): immobilisation, daily

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2 (spacing factor for serial dilutions)
- Range finding study: yes
- Test concentrations range finding study: undiluted filtrate, 1:10, 1:100, 1:1000 dilution, and control
- Results used to determine the conditions for the definitive study: 0% immobilisation at 1:10 dilution, 100% immobilisation in undiluted filtrate

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

6.9 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

mobility

Remarks on result:

other: 95% CL = 5.9-8.2

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

16 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

other: cerium trinitrate, anhydrous

Basis for effect:

mobility

Remarks on result:

other: 95% CL = 14-19

Details on results:

48-hour EC0 and NOEC of dissolved cerium were both 2.0 mg/L, since no toxic effect was observed up to and including this test concentration. 48-hour EC100 of dissolved cerium was 18 mg/L.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- 48-hour EC50: 0.94 mg/L (within the internal historical range: 48-hours EC50 from 2000 to 2012: 0.43 - 1.1 mg/L)

Reported statistics and error estimates:

NOEC, EC0 and EC100 were determined directly from the raw data.
24-h EC50 could not be calculated due to absence of toxicity and was therefore also determined directly from the raw data.
48-h EC50 and 95% confidence limits were calculated using Weibull Analysis with linear weighted regression.
The two lowest treatments were excluded from the statistical evaluation, as they did not contribute to the dose-response relationship.

The acute toxicity of cerium trinitrate to Daphnia magna was determined in a 48-hour semi-static test according to the OECD guideline 202 and in compliance with the principles of Good Laboratory Practice.Juvenile daphnids were exposed to a control treatment and the test chemical at various concentrations (a dispersion with the loading rate of 133 mg/L (corresponding to 100 mg/L of anhydrous cerium trinitrate) was used as stock solution for test media preparation; the undiluted filtrate and dilutions 1:2, 1:4, 1:8 and 1:16 of this undiluted filtrate were used as test media). Organisms were observed after 24 and 48 hours for immobility.After 48 hours of exposure, no immobilized test organisms were recorded in the control and up to and including the mean measured concentration of 2.0 mg/L of dissolved cerium, corresponding to 4.6 mg/L of anhydrous cerium trinitrate. At the mean measured concentration of 7.0 and 18 mg/L of dissolved cerium (corresponding to 16 and 41 mg/L of anhydrous cerium trinitrate), 50% and 100% of the daphnids were found to be immobile, respectively. The 48-h EC50 was determined to be 6.9 mg/L for dissolved cerium and 16 mg/L for anhydrous cerium trinitrate.

Validity criteria fulfilled:

yes

Conclusions:

The test item had acute toxic effects on Daphnia magna. Based on mean measured concentrations, the 48-hour EC50 was determined to be 6.9 mg/L for dissolved cerium with 95% confidence limits of 5.9 and 8.2 mg/L and 16 mg/L for anhydrous cerium trinitrate with 95% confidence limits of 14 and 19 mg/L. Based on this value, cerium trinitrate should be considered as harmful to aquatic invertebrates.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Study period:

from 12 DEC 1994 to 14 SEP 1995

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

Underestimation of toxicity likely. The study is GLP-compliant and performed according to an internationally recognised guideline. The results can however not be considered reliable as toxicity may be considerably underestimated. Dissolved Ce analysis indicates that Ce precipitates and disappears from the test solution. However, effect concentrations were based on nominal concentrations.

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

not specified

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: The cerium content was determined in the solution at 100 mg/L after 0 and 24 hours of exposure. The analysis was performed on the solutions prepared for the daphnids assays or prepared separately under identical conditions.
- Sampling method: Sampling was performed after homogenization on magnetic stirrer.
- Sample storage conditions before analysis: The homogenized solution was acidified. No further data.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A solution at 100 mg/L cerium trinitrate was prepared using bidistilled water.
- Differential loading: No (limit test)
- Controls: Test water without test item
- Evidence of undissolved material (e.g. precipitate, surface film, etc): At the beginning of the assay, the solutions contained fine particles which settled down progressively with time. Test solutions were slightly opalescent.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain: Strauss 1820
- Source: Source IRCHA, obtained in Ecotoxicology laboratory of CRIT/D
- Length at study initiation (length definition, mean, range and SD): between 560 and 800 µm
No further data

ACCLIMATION
No data

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

No data

Test temperature:

19.8-20°C

pH:

8.0-8.4

Dissolved oxygen:

95-99%

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentration : 100 mg/L (Ce(NO3)3)

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL glass vessels filled with 40 mL test medium
- Aeration: Test medium was aerated with compressed air.
- Type of flow-through (e.g. peristaltic or proportional diluter): None (static test)
- No. of organisms per vessel: 20 daphnids
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 1
No further data

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Bidistilled water containing analytical grade salts
- Conductivity: 0.86 µS/cm
- Culture medium different from test medium: No data
- Intervals of water quality measurement: pH and dissolved oxygen were measured at the end of the 48-hour test. Temperature was continuously monitored.

OTHER TEST CONDITIONS
- Adjustment of pH: No data
- Photoperiod: 24-hour darkness

EFFECT PARAMETERS MEASURED (with observation intervals if applicable)
Immobile daphnids were counted after 24 and 48 hours.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: Not applicable (limit test)
- Range finding study: No data

Reference substance (positive control):

yes

Remarks:

potassium dichromate (K2Cr2O7).

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 42.96 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

cerium

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

APPEARANCE OF THE TEST MEDIA
Fine particles were observed at the beginning of the test. They settled down slowly in the bottom of the vessel.

ANALYTICAL RESULTS
Analysis showed that the cerium ion content was 34 mg/L at the beginning of the test (t=0). It diminished to < or = 3 mg/L after 24 hours. At 24h, cerium was observed in the bottom of the vessel.

BIOLOGICAL RESULTS:
No immobilization was observed, neither in the control group, nor in the group exposed to 100 mg/L cerium trinitrate.

Results with reference substance (positive control):

- Results with reference substance valid? Yes. The EC50 value is conform to the predicted value (0.9-2.0 mg/L).
- Mortality: Mortality was first observed at 1.1 mg/L with 20 % of immobilized individuals. An immobilization rate of 65 % was observed at 1.4 mg/L. And, 100 % immobilization was observed at 2.1 mg/L and higher.
- 24h-EC50: 1.3 mg/L.

Reported statistics and error estimates:

Not necessary as no adverse effect was observed.

Validity criteria fulfilled:

yes

Conclusions:

Based on the 48h-EC50 > 100 mg Ce(NO3)3/L, cerium trinitrate does not present any adverse effect on daphnids under the present conditions. However, this result is based on nominal concentration, whereas the Ce disappeared from solution as demonstrated by analytical monitoring (after 24 h <= 3 mg Ce/L). Therefore the results of this study could not be considered reliable. The 48-h EC50 corresponds to a value > 42.96 mg Ce/L, when expressed on nominal elemental basis.

Executive summary:

The acute toxicity of cerium trinitrate to Daphnia magna was determined in a 48-hour static test according to the C2 method described in annex V of the 67/548/EEC Directive and in compliance with the principles of Good Laboratory Practice.

 

Daphnids were exposed to control and test chemical at 100 mg/L. Organisms were observed after 24 and 48 hours for immobiliy.

 

No immobilization was observed, neither in the control group, nor in the group exposed to 100 mg/L cerium trinitrate.The 48-hour LC50 of cerium trinitrate to daphnids was determined to be > 100 mg/L (corresponding to> 42.96 mg Ce/L). On this basis, cerium trinitrate does not present any adverse effect on daphnids under the present conditions. However, this result is based on nominal concentration, whereas the Ce disappeared from solution as demonstrated by analytical monitoring (after 24 h <= 3 mg Ce/L). Therefore the results of this study could not be considered reliable as toxicity may be considerably underestimated.

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

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

Adequacy of study:

disregarded due to major methodological deficiencies

Justification for type of information:

As the toxicity of cerium compounds is mainly determined by the extent to which the compound gives rise to bioavailable cerium in the water column, and equally water soluble cerium compounds can be expected to give rise to similar levels of bioavailable cerium under similar conditions, aquatic toxicity data obtained with water soluble cerium compounds are lumped for hazard assessment purposes. In the case of cerium trinitrate, a study on the toxicity of cerium trichloride to aquatic invertebrates (Bringmann and Kühn, 1959) was therefore included in this dossier. This study was however not considered reliable as the observed toxicity is likely to be largely underestimated. The full read across justification is attached to IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

mobility

Remarks on result:

other: disregarded as the observed toxicity was likely to be underestimated

Reference 4

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

Underestimation of toxicity likely. Test conducted according to method similar to OECD 202. Test results should be used with caution as 1) materials and methods are not clearly described, and 2) Ce was not determined in the test media, which may have resulted in an underestimation of toxicity.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

Daphnid mobility was investigated after inducing an electro-acoustic sound (50 Hz), rather than after a gentle agitation of the test vessel .

GLP compliance:

no

Analytical monitoring:

no

Details on sampling:

no analytics performed

Vehicle:

no

Details on test solutions:

Test substances were diluted with water from the river Havel at the village Gatow. Test solutions were prepared in closed glass tubes (18 mm diameter)

Test organisms (species):

Daphnia sp.

Details on test organisms:

TEST ORGANISM
- Common name: waterflea
- Source: laboratory culture
- Age at study initiation (mean and range, SD): not older than 24h
- Method of breeding: from in-house adult daphnids
- Feeding during test: no
- Feeding during culturing: yes, with Scenedesmus sp.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

12° dH

Test temperature:

23°C

pH:

7.5

Dissolved oxygen:

not applicable

Salinity:

not applicable

Nominal and measured concentrations:

no data

Details on test conditions:

- The hazardous properties of the test substances on the daphnids was tested by testing the mobility after inducing an electro-acoustic sound (50 Hz).
- Test concentrations with 50% or more immobile daphnids were regarded as being hazardous.
- 10 daphnids per 10 mL

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

mobility

Details on results:

Ce was not determined in the test media. Results should be used with caution since toxicity may have been largely underestimated.

Reported statistics and error estimates:

none

Conclusions:

No hazardous effects (i.e. 50% or more immobile daphnids) were observed up to a concentration of 1000 mg Ce/L. Therefore, the 48h-EC50 is > 1000 mg Ce/L for Daphnia sp. after exposure to CeCl3. Results are not reliable as Ce was not determined in the test media, which may have resulted in a substantial underestimation of toxicity.

Description of key information

The key study of Hefner (2014), in which Daphnia magna was exposed for 48 h to Ce(NO3)3, yielded a 48-h EC50 of 6.9 mg Ce/L corresponding to 16 mg Ce(NO3)3/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

6.9 mg/L

Additional information

Three studies were included in this dossier as containing relevant information on this endpoint. However, two of these studies were disregarded in the evaluation because the results were not in agreement with those of the key study. This was most likely due to the fact that test concentrations were not analytically verified and effect concentrations were based on nominal concentrations. Therefore, toxicity may have been substantially underestimated.

The first disregarded study was that of Bringmann and Kühn (1959), reporting a 48-h EC50 of > 1000 mg Ce/L after exposing Daphnia magna for 48 h to CeCl3. Cerium concentrations were not analytically verified during the test. The second disregarded study was that of Bazin (1995). This study reported a 48-h EC50 of > 100 mg Ce(NO3)3/L (corresponding to a value > 42.96 mg Ce/L). Cerium disappeared from solution, with concentrations <= 3 mg Ce/L after 24 h of exposure. Data for recalculation of the EC50 value based on measured concentrations was not available.

The third study (Hefner, 2014) was also a 48-h study with Daphnia magna in which Ce(NO3)3 was used as test item and dissolved cerium concentrations were analytically monitored during the test. The 48-h EC50 was calculated based on mean measured concentrations and was 6.9 mg Ce/L (corresponding to 16 mg Ce(NO3)3/L). These results are considered as the key values for this endpoint.