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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Administrative data

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
9 May 2006 - 30 July 2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report Date:
2007

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
Name of test material: yttrium oxyde
Substance type: mono-constituent substance
Further information on test material confidential.

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Concentrations: triplicate samples from the test medium (100 mg/L) and from the control were sampled just before test start and after 48 hours.
- Sampling method: no data
- Sample storage conditions before analysis: 3% nitric acid was added to stabilise the test item during the storage period. Then the samples were deep frozen and stored at about -20°C.

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: an undiluted filtrate of a supersaturated dispersion with the loading rate of 100 mg/L was tested.
The dispersion with the loading rate of 100 mg/L was prepared by dispersing 50.1 mg of the test item in 500 mL of test water. The test item was mixed into the test water as homogeneously as possible using ultrasonic treatment for 15 min and intense stirring. The dispersion was stirred on a magnetic stirrer at room temperature in the dark for seven days. After the stirring period, the dispersion was filtered through a membrane filter (0.45 µm). The undiluted filtrate of the dispersion was used as the test medium.
- Controls: test water without test item
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no data

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Water flea
- Strain: clone defined as clone 5
- Source: supplied in 1992 by University of Sheffield/UK
- Age at study initiation (mean and range, SD): 6-24 hours (no data on mean). Not first brood progeny.
- Weight at study initiation (mean and range, SD): no data
- Length at study initiation (lenght definition, mean, range and SD): no data
- Method of breeding: bred at RCC since 1992 in reconstituted water of the quality identical to that used in the test and under temperature and light conditions identical to those of the test.
- Feeding during test: No

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h

Test conditions

Hardness:
2.5 mmol/L (= 250 mg/L as CaCO3)
Test temperature:
20°C
pH:
7.8
Dissolved oxygen:
between 8.5 and 8.6 mg/L
Salinity:
not applicable (freshwater)
Nominal and measured concentrations:
Nominal loading rate: 100 mg/L (test item)
Analytically measured concentrations at the start and at the end of the test were 528 and 519 (arithmetic mean = 523 µg/L) µg/L, respectively (test item).
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type: 100 mL glass beakers
- Material, size, headspace, fill volume: vessels filled with 50 mL of test medium
- Aeration: The test water was aerated prior to the start of the study until oxygen saturation was reached. During the test period, the test water was not aerated.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: 2 mL of medium per daphnid

WATER PARAMETERS
- Source/preparation of dilution water: reconstituted test water: analytical grade salts dissolved in purified water
- Alkalinity: 0.8 mmol/L
- Ca/Mg ratio (mol): 4:1 (based on molarity)
- Culture medium different from test medium: no
- Intervals of water quality measurement: At the start and at the end of the test, the pH values, the dissolved oxygen concentrations and the water temperature were determined in the test medium and the control. The appearance of the test medium was recorded at the start of the test and after 24 and 48 hours.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hour light and 8 hour dark with a 30 minute transition period
- Light intensity: between 470 and 640 lux

EFFECT PARAMETERS MEASURED
The daphnids were observed for immobility after 24 and 48 hours of exposure (daphnids not being able to swim within 15 seconds after gentle agitation of the test beaker are considered to be immobilised).
The NOELR and EL0 were determined directly from the raw data. The EL50 and EL100 could not be determined due to the absence of a toxic effect of the test item in this test.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: not relevant (limit test)
- Range finding study: yes
- Test concentrations of the range finding study: no data
- Results used to determine the conditions for the definitive study: Yes: no mortality at the undiluted loading rate, consequently a limit test at the same loading rate was performed.
Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrations
Key result
Duration:
48 h
Dose descriptor:
LL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
No remarkable observations concerning the appearance of the test medium.

The analytically measured concentrations of yttrium oxide in the test medium samples taken at the start and at the end of the test were 528 and 519 (arithmetic mean = 523 µg/L) µg/L, respectively. The solubility limit reached during this test was thus slightly different from that obtained during the water solubility test (0.70 mg/L at pH 6.8-7.1 and 20°C, when expressed as Y2O3). Such contrasting results could be explained by the different water media used in the water solubility test and ecotoxicological studies (media containing analytical grade salts).
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Mortality: no data
- 48 h-EC50: 0.67 mg/L (acceptance range: 0.53-1.1 mg/L) (potassium dichromate)
Reported statistics and error estimates:
None as no adverse effects were observed.

Any other information on results incl. tables

Effect of Yttrium oxide on the Mobility of Daphnia magna:

Treatment (Loading rate)

 

Mean measured

concentration of yttrium oxide

(µg/L)

No. of

daphnids

tested

Immobilized

daphnids after

24 hours

          No.                   %

Immobilized

daphnids after

48 hours

          No.                   %

Control

< 1.3*

20

0

0

0

0

Undiluted filtrate (100 mg/L)

523

20

0

0

0

0

*: limit of quantification of 1 µg Y/L, corresponding to 1.3 µg Y2O3/L

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The 48-h acute toxicity of yttrium oxide to Daphnia magna was studied under static conditions according to EU Commission Directive 92/69/EEC, Part C.2 (1992) and the OECD Guideline for Testing of Chemicals, N°202 (2004). Daphnids were exposed to control and test chemical at a nominal loading rate of 100 mg/L for 48 hours. Mortality/immobilisation were observed daily. No immobility was observed during the 48-h test period, neither in the control, nor at the loading rate of 100 mg/L. The 48-h LL50 and NOELR were thus > 100 mg/L and >= 100 mg/L, respectively.