Caesium fluoride

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

30 January 2017 to 10 March 2017

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:

April 2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 216091B008
- Purity test date: 99.9%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Over silica gel at room temperature in the dark. The samples were stored frozen prior to analysis
- Stability under test conditions: Stable
- Solubility and stability of the test substance in the solvent/vehicle: Stable

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: Dissolved in water
- Preliminary purification step (if any): None
- Final dilution of a dissolved solid, stock liquid or gel: In the range-finding test Daphnia magna were exposed to a series of nominal test concentrations of 0.10, 1.0, 10 and 100 mg/L. A nominal amount of test item (50 mg) was dissolved in test water and the volume adjusted to 500 mL to give the 100 mg/L test concentration from which a series of dilutions was made to give further test concentrations of 0.10, 1.0 and 10 mg/L. Based on the results of the range-finding test the following test concentrations were assigned to the definitive test: 10, 18, 32, 56 and 100 mg/L. A nominal amount of test item (200 mg) was dissolved in test water and the volume adjusted to 2 litres to give the 100 mg/L test concentration from which a series of dilutions was made to give further test concentrations of 10, 18, 32 and 56 mg/L.

-

Analytical monitoring:

yes

Details on sampling:

The test samples were thawed with the aid of sonication. Nitric acid (2 mL) was added to a volume (100 mL) of sample and the samples were ultrasonicated for 15 minutes before being filtered through 0.45 μm cellulose acetate filters. If required, samples were diluted into the calibration range with 2% (v/v) nitric acid in test medium.

Vehicle:

yes

Details on test solutions:

In the range-finding test Daphnia magna were exposed to a series of nominal test concentrations of 0.10, 1.0, 10 and 100 mg/L. A nominal amount of test item (50 mg) was dissolved in test water and the volume adjusted to 500 mL to give the 100 mg/L test concentration from which a series of dilutions was made to give further test concentrations of 0.10, 1.0 and 10 mg/L. Based on the results of the range-finding test the following test concentrations were assigned to the definitive test: 10, 18, 32, 56 and 100 mg/L. A nominal amount of test item (200 mg) was dissolved in test water and the volume adjusted to 2 litres to give the 100 mg/L test concentration from which a series of dilutions was made to give further test concentrations of 10, 18, 32 and 56 mg/L.

Test organisms (species):

Daphnia magna

Details on test organisms:

The test was carried out using first instar Daphnia magna derived from in-house laboratory cultures.
Adult daphnids were maintained in 150 mL glass beakers containing Elendt M7 medium (see Annex 1) in a temperature controlled room maintaining the water temperature at 18 to 22 °C. The lighting cycle was controlled to give a 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods. Each culture was fed daily with a mixture of algal suspension (Desmodesmus subspicatus) and Tetramin® flake food suspension. Culture conditions ensured that reproduction was by parthenogenesis. Gravid adults were isolated the day before initiation of the test, such that the young daphnids produced overnight were less than 24 hours old. These young were removed from the cultures and used for testing. The diet and diluent water are considered not to contain any contaminant that would affect the integrity or outcome of the study.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

250 mg/L as CaCO3

Test temperature:

21 deg C

pH:

7.9-8.0

Dissolved oxygen:

8.7 mgO2/L

Salinity:

See study report for further details

Conductivity:

See study report for further details

Nominal and measured concentrations:

A nominal amount of test item (200 mg) was dissolved in test water and the volume adjusted to 2 litres to give the 100 mg/L test concentration from which a series of dilutions was made to give further test concentrations of 10, 18, 32 and 56 mg/L.

Details on test conditions:

Based on the results of the range-finding test the following test concentrations were assigned to the definitive test: 10, 18, 32, 56 and 100 mg/L.
A nominal amount of test item (200 mg) was dissolved in test water and the volume adjusted to 2 litres to give the 100 mg/L test concentration from which a series of dilutions was made to give further test concentrations of 10, 18, 32 and 56 mg/L.
Each prepared concentration was inverted several times to ensure adequate mixing and homogeneity.
The concentration and stability of the test item in the test preparations were verified by chemical analysis at 0 and 48 hours
Exposure conditions - As in the range-finding test 150 mL glass beakers containing approximately 100 mL of test preparation were used. At the start of the test five daphnids were placed in each test and control vessel at random, in the test preparations. Four replicate test and control vessels were prepared. The test vessels were then covered to reduce evaporation and maintained in a temperature controlled room maintaining the water temperature at 18 to 22 °C with a maximum deviation of ±1 °C with a photoperiod of 16 hours light (between 200 and 1200 Lux) and 8 hours darkness with 20 minute dawn and dusk transition periods. The daphnids were not individually identified, received no food during exposure and the test vessels were not aerated. The control group was maintained under identical conditions but not exposed to the test item.
The test preparations were not renewed during the exposure period.
Test Organism Observations - Any immobilization or adverse reactions to exposure were recorded at 24 and 48 hours after the start of exposure. The criterion of effect used was that daphnia were considered to be immobilized if they were unable to swim within 15 seconds after gentle agitation.
Water Quality Criteria - Water temperature was recorded daily throughout the test. Dissolved oxygen concentrations and pH were recorded at the start and termination of the test. The pH and dissolved oxygen concentration were measured using a Hach Flexi handheld meter whilst the temperature was measured using a Hanna Instruments HI 93510 digital thermometer. The light intensity during the light period was measured using an ATP Instrumentation Lux meter. The appearance of the test media was recorded daily.
Verification of Test Concentrations - Samples were taken from the control and each test group from the bulk test preparation at 0 hours and from the pooled replicates at 48 hours for quantitative analysis. All samples were stored frozen prior to analysis. Duplicate samples were taken and stored frozen for further analysis if necessary.

Reference substance (positive control):

yes

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

62 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

56 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

Cumulative immobilization data and other observations from the exposure of Daphnia magna to the test item during the definitive test are given in Table 2 of the study report. The relationship between percentage immobilization and concentration at 48 hours is given in Figure 1 of the study report. The No Observed Effect Concentrations after 24 and 48 hours exposure were 100 and 32 mg/L respectively. The Lowest Observed Effect Concentrations after 24 and 48 hours exposure were greater than 100 and 56 mg/L respectively The slopes and their standard errors of the response curves at 24 and 48 hours were 0.76 (SE = 1.3) and 23 (SE = 0.20) respectively.

Results with reference substance (positive control):

A positive control (Envigo Study Number MS29MC) used potassium dichromate as the reference item at concentrations of 0.32, 0.56, 1.0, 1.8 and 3.2 mg/L.
Exposure conditions for the positive control were similar to those in the definitive test.
Analysis of the immobilization data by the probit analysis using the linear maximum likelihood regression method at 24 and 48 hours using the ToxRat Professional computer software package based on the nominal test concentrations. The No Observed Effect Concentration is based upon equal to or less than 10% immobilization at this concentration. The results from the positive control with potassium dichromate were within the normal range for this reference item.

Reported statistics and error estimates:

Analysis of the immobilization data by Probit analysis using Linear Maximum-Likelihood regression based on the nominal test concentrations was performed.

Validity criteria fulfilled:

yes

Conclusions:

Exposure of freshwater invertebrate Daphnia magna to the test item was investigated and gave the following results:
At 48 hrs, EC50 = 62 mg/L, NOEC = 32 mg/L, LOEC = 56 mg/L

Executive summary:

A study was performed to assess the acute toxicity of the test item to Daphnia magna. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (April 2004) No 202, "Daphnia sp., Acute Immobilisation Test" referenced as Method C.2 of Commission Regulation (EC) No. 440/2008 and according to GLP. Following a preliminary range-finding test, twenty daphnids (4 replicates of 5 animals) were exposed to an aqueous solution of the test item at nominal concentrations of 10, 18, 32, 56 and 100 mg/L for 48 hours at a temperature of 21°C to 22 °C under static test conditions. The number of immobilized daphnia were recorded after 24 and 48 hours.

Exposure of freshwater invertebrate Daphnia magna to the test item gave the following results at 48 hrs, EC50 = 62 mg/L, NOEC = 32 mg/L, LOEC = 56 mg/L. The validity criteria of the test was fulfilled.

Description of key information

A study was performed to assess the acute toxicity of the test item to Daphnia magna. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (April 2004) No 202, "Daphnia sp., Acute Immobilisation Test" referenced as Method C.2 of Commission Regulation (EC) No. 440/2008 and according to GLP. Following a preliminary range-finding test, twenty daphnids (4 replicates of 5 animals) were exposed to an aqueous solution of the test item at nominal concentrations of 10, 18, 32, 56 and 100 mg/L for 48 hours at a temperature of 21°C to 22 °C under static test conditions. The number of immobilized daphnia were recorded after 24 and 48 hours.

Exposure of freshwater invertebrate Daphnia magna to the test item gave the following results at 48 hrs, EC50 = 62 mg/L, NOEC = 32 mg/L, LOEC = 56 mg/L. The validity criteria of the test was fulfilled.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

62 mg/L