Neodymium trihydroxide

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

26 April to 24 May 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Dineodymium tricarbonate

EC Number:

227-579-4

EC Name:

Dineodymium tricarbonate

Cas Number:

5895-46-5

Molecular formula:

CH2O3.2/3Nd

IUPAC Name:

dineodymium tricarbonate

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material (as cited in study report): Dineodymium tricarbonate
- Substance type: Monoconstituent
- Physical state and appearance: Extremely pale purple powder
- Analytical purity: 99.7% as Nd2O3/TREO; 59.8% TREO
- Purity test date: 22 January 2010
- Storage condition of test material: At room temperature in the dark, or at room temperature in the dark over silica

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Control and the 100% v/v saturation solution at 0 and 48 hours
- Sampling method: Duplicate samples taken
- Sample storage conditions before analysis: Stored at -20°C prior to analysis

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Saturation solution prepared by adding 1100 mg of test substance to 11 litres of reconstituted water and stirred with a propeller stirrer at 1500 rpm for 48 hours. Undissolved test item was filtered out of solution via a 0.2 µm Gelman AcroCap filter to produce a saturated solution.
- Controls: Water only
- Evidence of undissolved material: None, test solutions were clear and colorless throughout the duration of the test.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Species: Daphnia magna
- Strain: not reported
- Source: not reported
- Age at study initiation: less than 24 hours old
- Weight at study initiation: not reported
- Length at study initiation: not reported
- Method of breeding: parthenogenesis
- Feeding during test: no

ACCLIMATION
- Acclimation period: none
- Type and amount of food during culturing: suspension of algae (Chlorella sp.)
- Feeding frequency during culturing: daily

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Post exposure observation period:

None

Test conditions

Hardness:

Approximate theoretical total hardness of 250 mg/L as CaCO3

Test temperature:

21 to 22 ºC

pH:

7.8 to 8.2

Dissolved oxygen:

8.6 to 9.4 mg O2/L (note: concentrations exceeding oxygen saturation were likely a result of micro-bubbles super-saturating the solutions)

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal: Control + 100% v/v saturated solution.

Measured concentrations in 100% v/v saturated solution (as Nd carbonate):
0 hours: 0.0154 and 0.0155 mg/L
48 hours: 0.0112 and 0.0114 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250-mL glass jars
- Fill volume: filled with 200 mL of test solution
- Aeration: test vessels not aerated
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
Stock Solutions
a) CaCl2.2H2O 11.76 g/L
b) MgSO4.7H2O 4.93 g/L
c) NaHCO3 2.59 g/L
d) KCl 0.23 g/L

Preparation
An aliquot (25 mL) of each of solutions a-d was added to each litre (final volume) of deionised water with a conductivity of < 5 µS cm-1. The reconstituted water had a pH of 7.8 ± 0.2 adjusted (if necessary) with NaOH or HCl and was aerated until the dissolved oxygen concentration was approximately the oxygen-saturation value.
The reconstituted water had an approximate theoretical total hardness of 250 mg/L as CaCO3.

OTHER TEST CONDITIONS
- Adjustment of pH: pH of water adjusted if necessary
- Photoperiod: 16 hours light / 8 hours dark
- Light intensity: not reported

EFFECT PARAMETERS MEASURED: mobility

TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: nominal test concentrations of 0.10, 1.0, 10 and 100% v/v of a saturated solution.
- Results used to determine the conditions for the definitive study: No adverse effects observed at any concentration in range finding test.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 0.013 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Effect concentrations 2

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: None observed. Immobilisation observed in range finding test was considered to result from natural causes rather than toxic effect.
- Mortality of control: No mortality.
- Other adverse effects in the control: None reported.
- Abnormal responses: None reported.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: Test solutions were clear and colorless.
- Effect concentrations exceeding solubility of substance in test medium: Yes (when expressed based on loading rate).

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Mortality: Yes, at concentrations of 0.56 mg/L and greater.
- EC50/LC50: 48-h EC50 = 0.65 mg/L (95% CI: 0.58 to 0.72 mg/L)

Any other information on results incl. tables

Table 1: Cumulative Immobilisation Data in the Definitive Test

Mean measured concentration (mg/L)	Replicate	Cumulative Immobilised Daphnia (initial population: 5 per replicate)
		24 hours	48 hours
Control	R1	0	0
	R2	0	0
	R3	0	0
	R4	0	0
	R5	0	0
0.013	R1	0	0
	R2	0	0
	R3	0	0
	R4	0	0
	R5	0	0

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity of the test item to the freshwater invertebrate Daphnia magna was investigated according to OECD guideline 202. Based on mean measured concentrations, a 48-h EC50 greater than 0.013 mg/L (as Nd carbonate) was obtained.
This study showed that there were no toxic effects at saturation (nominal loading rate 100 mg/L). Therefore the 48-h EL50 is > 100 mg/L (i.e., based on loading rate).

Executive summary:

Following a preliminary range finding test, twenty daphnids (4 replicates of 5 animals) were exposed to an aqueous solution of the test item at a concentration of 100% v/v saturated solution for 48 hours at a temperature of 20-22°C under static test conditions. The test item solution was prepared by stirring an excess (100 mg/L) of test item in reconstituted water using a propeller stirrer at approximately 1500 rpm for 48 hours. After the stirring period, any undissolved test item was removed by filtration to produce a saturated solution of the test item. Immobilisation and any adverse reactions to exposure were recorded after 24 and 48 hours.

The test item contained neodymium at a concentration of 61.5% w/w. The test samples were analysed for neodymium only. Analysis of the fresh test item solution at 0 hours yielded measured concentrations of 0.0155 and 0.0154 mg/L as test item. Analysis of the test media at 48 hours yielded measured concentrations of 0.0114 and 0.0112 mg/L as test item.

The 48-h EC50 for Daphnia magna, based on the mean measured test item concentration, was greater than 0.013 mg/L.

This study showed that there were no toxic effects at saturation (nominal loading rate 100 mg/L). Therefore the 48-h EL50 is > 100 mg/L (i.e., based on loading rate).