Neodymium trichloride

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:

20 March 2017 to 16 August 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:

2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Samples were taken from the control and each test group from the freshly prepared bulk test preparation at 0 and 24 hours and from the pooled replicates of the old or expired media at 24 and 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.
- Only samples at the No Observed Effect Concentration and above were analysed.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- A nominal amount of test material (200 mg) was dissolved in test water and the volume adjusted to 2 liters to give the 100 mg/L test concentration from which a series of dilutions was made to give further test concentrations of 1.0, 3.2, 10 and 32 mg/L.
- Each prepared concentration was inverted several times to ensure adequate mixing and homogeneity.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Source: first instar Daphnia magna were derived from in-house laboratory cultures.
- Age: 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.
- Feeding during test: no

CULTURE CONDITIONS
Adult daphnids were maintained in 150 mL glass beakers containing 100 mL Elendt M7 medium 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.
- Elendt M7 medium ingredients and their final concentration (mg/L): H3BO3 0.715, MnCl2.4H2O 0.090, LiCl 0.077, RbCl 0.018, SrCl2.6H2O 0.038, NaBr 0.004, Na2MoO4.2H2O 0.016, CuCl2.2H2O 0.004, ZnCl2 0.013, CoCl2.6H2O 0.010, KI 0.0033, Na2SeO3 0.0022, NH4VO3 0.00058, Na2EDTA.2H2O 0.625, FeSO4.7H2O 0.249, CaCl2.2H2O 293.8, NaHCO3 64.8, MgSO4.7H2O 123.3, Na2SiO3.9H2O 10, KCl 5.8, NaNO3 0.274, K2HPO4 0.184, KH2PO4 0.143, Thiamine hydrochloride 0.075, Cyanocobalamine (vitamin B12) 0.0010 and D(+) biotin (vitamin H) 0.00075.
- Type and amount of food: Each culture was fed daily with a mixture of algal suspension (Desmodesmus subspicatus) and Tetramin® flake food suspension.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

250 mg/L as CaCO3

Test temperature:

22°C

pH:

6.3 to 8.0

Dissolved oxygen:

8.5 to 8.9 mg O2/L

Nominal and measured concentrations:

- Nominal concentrations: 1.0, 3.2, 10, 32 and 100 mg/L
- The geometric mean measured test material concentrations were determined to be: 7.7, 26 and 84 mg/L at nominal concentrations of 10, 32 and 100 mg/L, respectively. No analytical measurement was performed for the treatments corresponding to concentrations below the NOEC.

Details on test conditions:

TEST SYSTEM
- Test vessel: 150 mL glass jars
- Test vessels were covered to reduce evaporation
- Material, size, headspace, fill volume: 100 mL of test preparation
- Aeration: no
- Renewal rate of test solution: For the test media renewal at 24 hours, the test concentrations were freshly prepared and the daphnids transferred by wide bore pipette from the 24-Hour old test media into the fresh test media. Concentrations at which 100 % immobilisation was observed after 24 hours exposure were not renewed.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Reconstituted water- ISO Medium contained the following ingredients: CaCl2.2H2O 294 mg/L, MgSO4.7H2O 123 mg/L, NaHCO3 65 mg/L and KCl 5.8 mg/L.
- Culture medium different from test medium: yes
- Intervals of water quality measurement: The water temperature, pH and dissolved oxygen concentrations were recorded daily throughout the test. The measurements at 0 hours and after the test media renewal at 24 hours represent those of the freshly prepared test preparations while the measurements taken prior to the test media renewal, and on termination of the test after 48 hours, represent those of the used or 24-Hour old test preparations. 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.

OTHER TEST CONDITIONS
- Adjustment of pH: The pH of the reconstituted water was adjusted (if necessary) with NaOH or HCl to 7.8 ± 0.2.
- Photoperiod: 16 hours light (between 200 and 1200 Lux) and 8 hours darkness with 20 minute dawn and dusk transition periods.
- Light Intensity: 340 to 450 Lux

EFFECT PARAMETERS MEASURED: Any immobilisation 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 immobilised if they were unable to swim within 15 seconds after gentle agitation.

RANGE-FINDING STUDY
- Test concentrations: Daphnia magna were exposed to a series of nominal test concentrations of 0.10, 1.0, 10 and 100 mg/L.
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

69 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

28 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

7.7 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

26 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

RANGE-FINDING TEST
- No significant immobilisation was observed at the test concentrations of 0.10 and 1.0 mg/L, however, immobilisation was observed at 10 and 100 mg/L. Sub-lethal effects of exposure were observed in the control and 10 mg/L test group. These responses were trapping at the surface and a reduction in movement.
- After 24 hours exposure, test material was observed to have precipitated out of solution in the 10 and 100 mg/L test preparations. Microscopic observations made on the immobilised daphnia in the 100 mg/L test preparations showed no particles of test material adhered to the appendages, suggesting that no physical effect was observed. Based on this information test concentrations of 1.0, 3.2, 10, 32 and 100 mg/L were selected for the definitive test.
- Chemical analysis of the test preparations at 0 hours showed measured test concentrations to range from 0.042 to 39 mg/L as neodymium (equivalent to 0.11 to 97 mg/L as test material). After 48 hours exposure, measured concentrations were observed to range from 0.29 to 28 mg/L as neodymium (equivalent to 0.73 to 70 mg/L as test material) indicating that the test material was not stable under test conditions.

DEFINITIVE TEST
- Verification of Test Concentrations: Analysis of the freshly prepared 10, 32 and 100 mg/L test preparations at 0 and 24 hours showed measured neodymium concentrations of between 3.7 and 39 mg/L (equivalent to 9.2 and 97 mg/L as test material). Analysis of the old or expired test preparations at 24 and 48 hours showed measured neodymium concentrations had declined, to range from 2.3 to 32 mg/L (equivalent to 5.8 to 80 mg/L as test material). Given this decline in measured test concentrations it was considered justifiable to base the results on the geometric mean measured test concentrations in order to give a "worst case" analysis of the data. The geometric mean measured test concentrations were determined to be: 7.7, 26 and 84 mg/L at nominal concentrations of 10, 32 and 100 mg/L, respectively.
- Immobilisation Data: The 24 and 48 hour EC50 values were 69 and 28 mg/L, respectively. The No Observed Effect Concentrations after 24 and 48 hours exposure were 26 and 7.7 mg/L respectively. The Lowest Observed Effect Concentrations after 24 and 48 hours exposure were 84 and 26 mg/L respectively. The slopes and their standard errors of the response curves at 24 and 48 hours were 12 (SE = 0.74) and 3.7 (SE = 0.062) respectively.
- Sub-Lethal Effects: Sub-lethal effects of exposure were observed in the 32 and 100 mg/L test concentration. These responses were a reduction in movement and being covered in debris. No mircoparticles of test material were observed to be adhered to the immobilised daphnia.
- Validation Criteria: The test was considered to be valid given that none of the control daphnids showed immobilisation or other signs of disease or stress and that the oxygen concentration at the end of the test was equal to or greater than 3 mg/L in the control and test vessels.
- Water Quality Criteria: Temperature was maintained at 22 °C throughout the test. While there were no treatment related differences for oxygen concentration, concentration dependent differences in pH were observed throughout the test. Throughout the test the light intensity was observed to be in the range 340 to 450 Lux.
- Observations on Test Material Solubility: In the freshly prepared test solutions at 0 hours, all control and test media were observed to be clear colourless solutions, and in the freshly prepared test solutions at 24 hours, the control, 1.0, 3.2, 10 and 32 mg/L test media were observed to be clear colourless solutions and the100 mg/L test media was observed to be a very slightly cloudy dispersion. In the old or expired media at 24 and 48 hours, the control, 1.0, 3.2 and 10 mg/L test media were observed to be clear colourless solutions, the 32 mg/L test media was observed to be a clear colourless solution with test material precipitated on the base of the vessel and the 100 mg/L test media was observed to be a very slightly cloudy dispersion with test material precipitate on the bottom.

Results with reference substance (positive control):

- A positive control used potassium dichromate as the reference material at concentrations of 0.32, 0.56, 1.0, 1.8 and 3.2 mg/L.
- The No Observed Effect Concentration is based upon equal to or less than 10% immobilisation at this concentration. The 24 and 48 h EC50 was 0.56 mg/L. The results from the positive control with potassium dichromate were within the normal range for this reference material.

Table 1: Cumulative Immobilisation Data and Observations in the Definitive Test at 24 hours

Nominal Concentration (mg/L)	24 Hours
	Cumulative Immobilised Daphnia (Initial Population: 5 Per Replicate)						Observations
	R1	R2	R3	R4	Total	%	R1	R2	R3	R4
Control	0	0	0	0	0	0	5 N	5 N	5 N	5 N
1.0	0	0	0	0	0	0	5 N	5 N	5 N	5 N
3.2	0	0	0	0	0	0	5 N	5 N	5 N	5 N
10	0	0	0	0	0	0	5 N	5 N	5 N	5 N
32	0	0	0	0	0	0	5 N	5 N	5 N	5 N
100	4	4	5	4	17	85	1 R + C	1 R + C	A/I	1 R

 

Table 2: Cumulative Immobilisation Data and Observations in the Definitive Test at 48 hours

Nominal Concentration (mg/L)	48 Hours
	Cumulative Immobilised Daphnia (Initial Population: 5 Per Replicate)						Observations
	R1	R2	R3	R4	Total	%	R1	R2	R3	R4
Control	0	0	0	0	0	0	5 N	5 N	5 N	5 N
1.0	0	0	0	0	0	0	5 N	5 N	5 N	5 N
3.2	0	0	0	0	0	0	5 N	5 N	5 N	5 N
10	0	0	1	0	1	5	5 N	5 N	4 N	5 N
32	3	2	1	1	7	35	2 R	3 R	4 R	4 R
100	5	5	5	5	20	100	A/I	A/I	A/I	A/I

R₁– R₄= Replicates 1 to 4

N = No sub-lethal effects observed

R = Reduced movement

C = Covered in debris

A/I = All daphnia immobilised

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of this study the 48-h EC50 was 28 mg/L. The 48-h NOEC was 7.7 mg/L and the 48-h LOEC was 26 mg/L.

Executive summary:

The potential of the test material to cause acute toxicity to aquatic invertebrates was investigated in accordance with the standardised guidelines OECD 202 and EU Method C.2, under GLP conditions.

Following a preliminary range-finding test, twenty daphnids (4 replicates of 5 animals) were exposed to an aqueous solution of the test material at nominal concentrations of 1.0, 3.2, 10, 32 and 100 mg/L for 48 hours at a temperature of 22°C under semi-static test conditions. The number of immobilised daphnia were recorded after 24 and 48 hours.

Analysis of the freshly prepared test preparations at 0 and 24 hours showed measured neodymium concentrations of between 3.7 and 39 mg/L (equivalent to 9.2 and 97 mg/L as test material). Analysis of the old or expired test preparations at 24 and 48 hours showed measured neodymium concentrations had declined, to range from 2.3 to 32 mg/L (equivalent to 5.8 to 80 mg/L as test material) and so it was considered justifiable to base the results on the geometric mean measured test material concentrations in order to give a "worst case" analysis of the data.

Sub-lethal effects of exposure were observed in the 32 and 100 mg/L test concentration. These responses were a reduction in movement and being covered in debris. No mircoparticles of test material were observed to be adhered to the immobilised daphnia.

Therefore, under the conditions of this study the 48-h EC50 was 28 mg/L. The 48-h NOEC was 7.7 mg/L and the 48-h LOEC was 26 mg/L.

Description of key information

Under the conditions of this study the 48-h EC50 was 28 mg/L. The 48-h NOEC was 7.7 mg/L and the 48-h LOEC was 26 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

28 mg/L

Additional information

The potential of the test material to cause acute toxicity to aquatic invertebrates was investigated in accordance with the standardised guidelines OECD 202 and EU Method C.2, under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

Following a preliminary range-finding test, twenty daphnids (4 replicates of 5 animals) were exposed to an aqueous solution of the test material at nominal concentrations of 1.0, 3.2, 10, 32 and 100 mg/L for 48 hours at a temperature of 22°C under semi-static test conditions. The number of immobilised daphnia were recorded after 24 and 48 hours.

Analysis of the freshly prepared test preparations at 0 and 24 hours showed measured neodymium concentrations of between 3.7 and 39 mg/L (equivalent to 9.2 and 97 mg/L as test material). Analysis of the old or expired test preparations at 24 and 48 hours showed measured neodymium concentrations had declined, to range from 2.3 to 32 mg/L (equivalent to 5.8 to 80 mg/L as test material) and so it was considered justifiable to base the results on the geometric mean measured test material concentrations in order to give a "worst case" analysis of the data.

Sub-lethal effects of exposure were observed in the 32 and 100 mg/L test concentration. These responses were a reduction in movement and being covered in debris. No mircoparticles of test material were observed to be adhered to the immobilised daphnia.

Therefore, under the conditions of this study the 48-h EC50 was 28 mg/L. The 48-h NOEC was 7.7 mg/L and the 48-h LOEC was 26 mg/L.