Barium selenate

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

21 March 2018 - 04 April 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

All validity criteria were met

Justification for type of information:

Test data are required for classification purposes.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

Adopted 13 April 2004

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Barium selenate

EC Number:

232-113-8

EC Name:

Barium selenate

Cas Number:

7787-41-9

Molecular formula:

Ba.H2O4Se

IUPAC Name:

barium selenate

Test material form:

solid: crystalline

Specific details on test material used for the study:

- Expiration date of the batch: 24 April 2019
- Appearance / colour: solid / white
- Purity analysed: 97.6% w/w
- Storage condition of test material: ambient (5 °C - 30 °C), dark, dry

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Analytical samples were taken from all test item concentrations and control at test start and after 48 hours from aged solutions. For each sampling a retained sample was also taken. All samples were stored refrigerated until they were transferred to the analytical laboratory.
After receipt in the analytical laboratory the test medium samples (21 mL) were stored between 1-10 °C until analysis. On the day of analysis, the samples were brought to room temperature. Samples were diluted with 5% nitric acid by the following dilution factors:
Control- dilution factor 1
1.94 mg test item/L- dilution factor 2
4.27 mg test item/L- dilution factor 5
9.39 mg test item/L- dilution factor 10
20.7 mg test item/L- dilution factor 20
45.5 mg test item/L- dilution factor 200
100 mg test item/L- dilution factor 200

Test solutions

Vehicle:

no

Details on test solutions:

ISO test water was used as test medium.
Based on the results of a non GLP range-finding test, the following nominal concentrations were tested in the main test: 100, 45.5, 20.7, 9.39, 4.27, 1.94 mg barium selenate/L, and control.
The necessary amount of test item for preparing the stock solution was weighed on a weighing scoop and transferred to a volumetric flask. Test medium was added up to the benchmark and the solution was homogenised by shaking and treated with 5 minutes of ultrasonication. Lower test concentrations were prepared by dilution of the stock solution with test medium.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

- Clone: Daphnia magna Straus, Clone V
- Source: The animals are continuously bred in the laboratory and were originally purchased in a healthy condition from the Federal Environment Agency in Berlin/Germany. Daphnia magna were bred as a single culture (1 daphnid per 100 mL) in Elendt M4 medium.
- Age at test start: Freshly hatched daphnids less than 24 hours old.
- Feeding of culture: Animals were fed with single cell green algae (Desmodesmus subspicatus, formerly Scenedesmus subspicatus) at least three times a week.
- Culture conditions: pH of aerated water 6.0 – 9.0; dissolved oxygen > 60% saturation; total hardness 140 - 250 mg/L (as CaCO3), corresponding to 7.8 - 14°dH; temperature 20 ± 2 °C; photoperiod 16 hours light: 8 hours darkness.
- Feeding during test: None.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

Not applicable

Test conditions

Hardness:

12°dH (214 mg/L as CaCO3) at test start

Test temperature:

18.4 – 19.2 °C

pH:

7.28 – 7.98

Dissolved oxygen:

≥ 9.0 mg/L

Salinity:

Not applicable

Conductivity:

Not applicable

Nominal and measured concentrations:

Nominal (barium selenate): 100, 45.5, 20.7, 9.39, 4.27, 1.94 mg barium selenate/L, and control.

Nominal (barium): 47.8, 21.8, 9.90, 4.49, 2.04, 0.926 mg barium/L, and control.
Measured (barium calculated as barium selenate: 0 h fresh sample): 84.9, 41.0, 18.3, 8.12, 3.49, 1.65 mg barium selenate/L and not detectable in control (87, 92, 91, 89, 84, 87 % of nominal, respectively).
Measured (barium calculated as barium selenate: 48 h aged sample): 1.60, 1.40, 0.947, 0.506, 0.362, 0.522 mg barium selenate/L and not detectable in control (2, 3, 5 % of nominal,
Nominal (selenium): 27.5, 12.5, 5.70, 2.58, 1.17, 0.532 mg selenium/L, and control.
Measured (selenium calculated as barium selenate: 0 h fresh sample): 90.8, 40.8, 18.7, 8.52, 3.55, 1.71 mg barium selenate/L and not detectable in control (93, 92, 93, 93, 85, 90 % of nominal, respectively).
Measured (selenium calculated as barium selenate: 48 h aged sample): 38.6, 27.7, 15.9, 7.66, 3.43, 1.17 mg barium selenate/L and not detectable in control (40, 62, 79, 84, 82, 62 % of nominal, respectively).

Details on test conditions:

- Test vessel: 100 mL glass vessel, with approximately 50 mL of test solution, covered with a glass plate to reduce evaporation.
- Aeration: none
- Photoperiod: 16 hours light: 8 hours dark
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4, plus one additional replicate for physico-chemical measurements without test organisms

Reference substance (positive control):

yes

Remarks:

potassium dichromate (1.00 mg/L and 2.00 mg/L)

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

15.7 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

barium selenate

Basis for effect:

mobility

Remarks on result:

other: 95% confidence limit: 6.73 – 36.3 mg/L

Effect concentrations 2

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

4.27 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

barium selenate

Basis for effect:

mobility

Details on results:

VALIDITY CRITERIA
All validity criteria were met:
- % immobilisation in the control was ≤10% (actual = 5%).
- Dissolved oxygen concentration at test end was ≥3 mg/L in all test units (actual ≥9.0 mg/L).

ANALYTICAL RESULTS
The measured content of barium was between 84 and 91% of nominal in the fresh samples with a mean initial concentration of 88% of nominal. In the 48 h aged samples the measured content was between below limit of quantification and 3% of nominal. The measured content of selenium was between 85 and 95% of nominal in the fresh samples with a mean initial concentration of 91% of nominal. In the 48 h aged samples the measured content was between 40 and 84% of nominal with a mean measured concentration of 68% of nominal. Since the content of active ingredient in the fresh samples was between 80 and 120% of nominal the ecotoxicological endpoints were evaluated using nominal concentrations of test item.

BIOLOGICAL RESULTS
24 h after test start, % immobilisation of daphnids was 0, 0, 0, 5, 0, 40 and 60% in the control, 1.94, 4.27, 9.39, 20.7, 45.5 and 100 mg barium selenate/L test groups, respectively. The mobile daphnids at test item concentrations 20.7 to 100 mg/L were partly sticky and showed hectic swimming movements. Additionally, at these concentrations a fine white layer of precipitated substance was observed at the bottom of the glass vessels.
48 h after test start, % immobilisation of daphnids was 5, 0, 0, 20, 70, 100 and 95% in the control, 1.94, 4.27, 9.39, 20.7, 45.5 and 100 mg barium selenate/L test groups, respectively. The mobile daphnids at test item concentrations 9.39 and 20.7 mg/L were partly sticky. Additionally, at these concentrations a fine white layer of precipitated substance was observed at the bottom of the glass vessels. At test item concentrations 45.5 and 100 mg/L white precipitation completely covered the bottom of the glass vessels.

Results with reference substance (positive control):

The toxicity of the reference item potassium dichromate was tested at 1.00 and 2.00 mg/L with 20 test organisms per test concentration (4 replicates of 5).
24 h after test start, % immobilisation of daphnids was 10 and 100% in the 1.00 and 2.00 mg/L test groups, respectively.
48 h after test start, % immobilisation of daphnids was 85 and 100% in the 1.00 and 2.00 mg/L test groups, respectively.
The 24 h EC50 was determined to be between 1.00 and 2.00 mg/L. This is within the range of 0.6 to 2.1 mg/L for inter laboratory tests reported in OECD 202 and also falls within the historical data generated with the reference item at the testing facility.
The results demonstrate that the test system was suitable for the determination of ecotoxicological effects of the test item.

Reported statistics and error estimates:

The NOEC values were determined based on the highest concentration at which immobilisation was not higher than the accepted control immobilisation (i.e. ≤10% immobilisation).
24 h NOEC = 20.7 mg barium selenate/L (nominal)
48 h NOEC = 4.27 mg barium selenate/L (nominal)

EC50 values were calculated by Logit analysis using linear maximum likelihood regression.
24 h EC50 = 72.7 mg barium selenate/L (95% confidence limit: 53.0 - 118 mg/L) (nominal)
48 h EC50 = 15.7 mg barium selenate/L (95% confidence limit: 6.73 – 36.3 mg/L) (nominal)

Any other information on results incl. tables

BIOLOGICAL RESULTS

Nominal test item concentration (mg/L)	% immobilisation after 24 h exposure	% immobilisation after 48 h exposure
Control	0	5
1.94	0	0
4.27	0	0
9.39	5	20
20.7	0	70
45.5	40	100
100	60	95
Toxic reference (potassium dichromate) 1.00 mg/L	10	85
Toxic reference (potassium dichromate) 2.00 mg/L	100	100

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The NOEC values were determined based on the highest concentration at which immobilisation was not higher than the accepted control immobilisation (i.e. ≤10% immobilisation).
24 h NOEC = 20.7 mg barium selenate/L (nominal)
48 h NOEC = 4.27 mg barium selenate/L (nominal)

EC50 values were calculated by Logit analysis using linear maximum likelihood regression.
24 h EC50 = 72.7 mg barium selenate/L (95% confidence limit: 53.0 - 118 mg/L) (nominal)
48 h EC50 = 15.7 mg barium selenate/L (95% confidence limit: 6.73 – 36.3 mg/L) (nominal)

Executive summary:

The acute toxicity of Daphnia magna to barium selenate was tested in a 48 hour static dose-response test in accordance with OECD guideline 202 (2004) and to GLP.

Six test item concentrations were tested at nominal concentrations of 1.94, 4.27, 9.39, 20.7, 45.5 and 100 mg/L. Additionally, a control (ISO test water) group was tested. Four replicates of each test concentration and control were tested, containing five daphnids per replicate. Two concentrations of the reference item potassium dichromate (1.00 mg/L, 2.00 mg/L) were tested around the same time period as the study.

The analytical verification of test item concentrations was conducted by analysing the content of barium and selenium in samples taken at test start and from aged solutions at 48 h. Mean initial concentrations of barium and selenium at test start were 88 and 91% of nominal, respectively. Mean concentrations of barium and selenium in aged solutions at 48 h were <3% and 68% of nominal, respectively. Since the content of active ingredient in the fresh samples was between 80 and 120% of nominal the ecotoxicological endpoints were evaluated using nominal concentrations of test item.

The test was considered valid as all validity criteria were met in accordance with OECD 202 (2004).

48 h after test start, % immobilisation of daphnids was 5, 0, 0, 20, 70, 100 and 95% in the control, 1.94, 4.27, 9.39, 20.7, 45.5 and 100 mg barium selenate/L test groups, respectively.

The 48 h NOEC value was determined to be 4.27 mg barium selenate/L (nominal). The 48 h EC₅₀ value was calculated to be 15.7 mg barium selenate/L (95% confidence limit: 6.73 – 36.3 mg/L) (nominal).