Gadolinium zirconium oxide (Gd2Zr2O7)

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:

From 2016-09-15 to 2016-12-05

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:

13 April 2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source: H.C. Starck GmbH, Batch No.of test material: 150273V2
- Expiration date of the lot/batch:July 2021
- Purity test date: >98%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature, dry, dark and tightly closed
- Stability under test conditions: stable
- Solubility and stability of the test substance in the solvent/vehicle: 4 mg/L (according to OECD 105: loading rate of 100 mg/L and stirring for 72 h at 30 °C)

OTHER SPECIFICS: White Powder

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0 mg/L (NC), 100 mg/L (A)
- Sampling method: At the start of the test (0 h), the test solutions NC and A were sampled before division to the test vessels (each group: 4 samples of 10 mL). After 24 h exposure, all replicates of NC and A were sampled (each group: 4 samples of
10 mL). At the end of the test (48 h), all replicates from NC and A were sampled (each group: 4 samples of 10 mL).
- Sample storage conditions before analysis: The samples were filtered (0.45 μm syringe filter, Whatman), filled in plastic centrifuge tubes and stored (< 4 weeks) in the fridge (5 °C ± 3 °C). Of each treatment, one of the samples from 0 h, 24 h and 48 h was sent to the analytical laboratory (ASG) and analysed.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The stock solution was prepared by adding 24.7 mg test item to 250 mL test medium and shaking for 72 h using an overhead shaker at 21.4 - 22.3 °C in the dark. Subsequently, the test item solution was allowed to settle for ca. 0.5 h before use in the test as single test item loading rate. Into each test vessel, 40 mL test item solution and test medium (NC) was transferred, respectively. Four replicates with five daphnids each, were prepared for the test treatment and the negative control.
- Eluate: ISO 6341 medium
- Controls: ISO 6341 medium
- Medium: According to OECD 202, for testing substances containing metals, media containing chelating agents should be avoided. The test was performed with ISO 6341 medium which does not contain EDTA.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna (Strauss)
- Source: clone breeding of the Federal Environment Agency, department IV 2.4, Berlin, and has been cultivated at Hydrotox GmbH since October 2012.
- Age at study initiation: The test organisms used were 0.25 - 23.25 h old at the start of the test.
- Feeding during test: none
- Feeding during cultivation (on workdays): Desmodesmus subspicatus algae corresponding to 0.1 mg C × daphnid-1 × day-1; food type: Desmodesmus subspicatus algae

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Test temperature:

19.4 - 20.6 °C

pH:

The pH was 7.6 - 7.8 in the control and 7.7 - 7.9 in the test item treatment

Dissolved oxygen:

The dissolved oxygen concentration was 7.9 - 8.0 mg/L in the control and 7.8 - 8.1 mg/L in
the test item treatment.

Salinity:

not applicable

Nominal and measured concentrations:

Nominal: 0 mg/L (NC) , 100 mg/L (A)

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass beakers 50 mL, Schott, Mainz
- Fill volume: 40 mL
- Aeration: no
- 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: ultrapure water
- Culture medium different from test medium: M4 Medium

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16/8 h

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobilisation

RANGE-FINDING STUDY
- Test concentrations:A preliminary test without GLP was performed before start of this GLP-study. Nominal loading rates of 50, 100 and 200 mg/L test item were tested and showed no effects on the mobility of the test organisms.
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

no

Duration:

24 h

Dose descriptor:

NOELR

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

LOELR

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

LOELR

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

The immobility in the control was reported as 0 % after 24 h and after 48 h.
The immobility in the treatment group was 0% after 24 h and 5% after 48 h.

The reported immobility during the test is presented in table 2. The values for the calculated LOELR and NOELR are displayed in table 3.

Table 2: Immobility [%] after 24 h and 48 h exposure.

Nominal test item concentration [mg/L]	Immobility [%]
	24 h	48 h
NC	0	0
A (100 mg/L)	0	5

Table 3: Effect loading rates.

Lowest/No Observed Effect Loadring Rate	Nominal test item loading rate [mg/L]
	24 h	48 h
LOELR	> 100	> 100
NOELR	≥ 100	≥ 100

The dissolved oxygen concentration was 7.9 - 8.0 mg/L in the control and 7.8 - 8.1 mg/L in the test item treatment.
The temperature during the exposure was 19.4 - 20.6 °C (required 18 - 22 °C, constant within ± 1 °C).

The measured concentration of Gd and Zr in the reference sample for quality assurance was within the acceptable tolerance range of ± 20 %.

The measured Gd-concentrations in the test item treatment were 10-20 μg/L and the Zr-concentrations were below the limit of quantification (< 1 μg/L). The Gd- and Zr-concentrations in the control were below the limit of quantification.

Validity criteria fulfilled:

yes

Remarks:

Immobilisation of the test organisms in the control at the end of the test was 0 % and therefore ≤ 10 %. Dissolved oxygen concentration in the control and the test item treatment at the end of the test was ≥ 8.0 mg/L and therefore ≥ 3 mg/L.

Conclusions:

The LOELR of Gadolinium zirconium oxide to Daphnia magna exceeds 100 mg/L, the NOELR exceeds or equals 100 mg/L.

Executive summary:

The 48-h-acute toxicity of Gadolinium zirconium oxide to Daphnia magna was studied under static conditions in accordance with the OECD Guideline 202 (April 2004) and under GLP. The test design was chosen as limit test, as a pre-test with test substance concentrations of 50, 100 and 200 mg/L showed no growth inhibition.

Within the limit test daphnids were exposed to the test chemical at a loading rate of 100 mg/L for 48 hr. Mortality/immobilisation and sub-lethal effects were observed daily. The LOELR was determined as > 100 mg/L, the NOELR as >= 100 mg/L. Sub-lethal effects were not reported.

Due to the poor water solubility, the measured Gd- and Zr-concentrations in the test item treatment were 10 -20 µg/L and below the limit of quantification (< 1 μg/L), respectively.

Based on the results of this study, Gadolinium zirconium oxide would not be classified for aquatic toxicity in accordance with the CLP classification system (Regulation (EC) No 1272/2008).

This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

Results Synopsis

Test organism age: Neonates

Test type: Static

LOELR > 100 mg/L

NOELR >= 100 mg/L

Endpoint(s) effected: Immobilitsation

Description of key information

The 48 h acute toxicity of Gadolinium zirconium oxide to aquatic invertebrates (Daphnia magna) was investigated in a study, according to GLP and OECD 202 under static conditions. The Lowest/No Observed Loading Rates are as follows: NOELR (24 h) ≥ 100 mg/L, LOELR (24 h) > 100 mg/L, NOELR (48 h) ≥ 100 mg/L, LOELR (48 h) > 100 mg/L.