Yttrium

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

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.

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 (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

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

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

Key result

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:

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.

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

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.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Data from the related substance yttrium oxide is used to cover this endpoint. The justification for read across is attached in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: Based on the result of Seyfried (2007) obtained with the read across substance Y2O3.

Conclusions:

No study is available on acute toxicity of yttrium metal to aquatic invertebrates. Therefore, read across is performed using a study from the related substance yttrtium oxide. In this study, the 48-h acute toxicity of yttrium oxide to newborn daphnids (Daphnia magna) was studied under static conditions according to the EU Commission Directive 92/69/EEC, Part C.2 (1992) and the OECD Guideline 202 and conform GLP requirements. The toxicity test was performed as a limit test. No mortality was observed during the test, neither in the control nor in the undiluted filtrate (100mg/L). Since their water solubilities are within the same range (1.3 mg/L for yttrium metal at 20°C and 0.7 mg/L for yttrium oxide at 20°C), the results of this study performed with yttrium oxide are considered suitable for concluding on the endpoint for yttrium metal too.

Description of key information

No key study is available on the acute toxicity of yttrium metal to aquatic invertebrates. The endpoint is therefore covered by read across from a study performed with the related substance yttrium oxide (Seyfreid, 2007; Klimisch 1). In this study, the 48-h LL50 obtained on Daphnia magna for yttrium oxide is > 100 mg/L based on the nominal loading rate corresponding to > 0.523 mg/L based on the measured concentration (> 0.465 mgL when expressed as Y concntration). Therefore, yttrium oxide is not harmful to aquatic invertebrates up to its solubility limit into water. Consequently, by analogy with yttrium oxide, yttium metal is considered not to be harmful to aquatic invertebrates. Since yttrium metal and yttrium oxide are both poorly water soluble yttrium compounds, the results of the study performed with yttrium oxide are considered suitable for concluding on the endpoint for yttrium metal too. The read across study was assigned key status for endpoint coverage.