Yttrium zirconium oxide

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:

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

Adequacy of study:

weight of evidence

Justification for type of information:

Following the read across strategy added in section 13 of IUCLID, it is considered appropriate to cover this endpoint using data from acute daphnid toxicity studies performed with zirconium dioxide and yttrium oxide.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Remarks on result:

other: Not harmful to daphnids.

Remarks:

Both zirconium dioxide and yttrium oxide were demonstrated not to cause any immobilisation in acute daphnid toxicity studies at the loading rate of 100 mg/L. Therefore, it can be concluded that yttrium zirconium oxide will not be harmful to daphnids either.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 08 AUG 1994 to 18 OCT 1994

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to the EU method C2 and the GLP. But no analytics were performed.

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

not specified

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Stock solutions were prepared by dissolving 100 mg of substance in 1000 g of test medium. The flasks were magnetically stirred for 24h at 30°C, then for 24h at 20°C and finally centrifugated at circa 9000 g for 20 min. The extracted solution was then used as test solution. The concentration of this test solution was expressed in percentage of dilution of the extracted solution. Here, only the undiluted extracted solution was tested (concentration = 100%)
- Controls: yes, test water without test item
- Evidence of undissolved material: no data

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain: Daphnia magna strauss 1820
- Source: : IRCHA-INERIS (Daphnia breeding in Décines Rhône-Poulenc laboratory)
- Age at study initiation: no data
- Weight at study initiation : no data
- Length at study initiation: 560 µm- Method of breeding: no data
- Feeding during test: no data

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

no data

Test temperature:

20.1-20.4°C

pH:

8.4

Dissolved oxygen:

92-96%

Salinity:

not applicable

Nominal and measured concentrations:

100 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 ml glass beaker
- Type: open
- Material, size, headspace, fill volume: 100 ml filled with 40 g of solution
- Aeration: The test medium was aerated with compressed air before the start of the test
- No. of organisms per vessel: 20
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 1
- Biomass loading rate: 1 daphnia per 2 g of tested solution

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: bidistillated water
- Total organic carbon: no data
- Particulate matter: no data
- Metals: no data
- Pesticides: no data
- Chlorine: no data
- Alkalinity: NaHCO3: 0.2 g/l
- Ca/mg ratio: CaCl2,2H2O: 0.297 g/l; MgCl2,6H2O: 0.167 g/l
- other: K2SO4: 0.026 g/l
- Conductivity: 0.90 µS/cm (of the bidistillated water)
- Culture medium different from test medium: no data
- Intervals of water quality measurement: The concentration of dissolved oxygen and the pH were measured after 48 h in each test flask


OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: exposure in the dark
- Light intensity: no

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : The measured effect is the mortality of the daphnids estimated through their immobilisation after 24 and 48 hours of exposure


TEST CONCENTRATIONS
- Spacing factor for test concentrations: not applicable (limit test)
- Justification for using less concentrations than requested by guideline: not applicable (limit test)
- Range finding study : no

Reference substance (positive control):

yes

Remarks:

potassium dichromate (K2Cr2O7).

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 other: % saturated solution (initial loading rate = 100 mg/L)

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

No further details given on the study results

Results with reference substance (positive control):

the 24-h EC50 for potassium dichromate was 1.4 ppm (w/w) (1.3-1.5 ppm (w/w)).

Reported statistics and error estimates:

not necessary as no adverse effect was observed

Effect of Zirconium dioxide on the Mobility of Daphnia magna:

Treatment (Loading rate)	No. of daphnids tested	Immobilized daphnids after 24 hours           No.                   %		Immobilized daphnids after 48 hours           No.                   %
Control	20	0	0	0	0
100 mg/L	20	0	0	0	0
100 mg/L	20	0	0	1	5

Validity criteria fulfilled:

not specified

Conclusions:

Zirconium dioxide had no acute effect on Daphnia magna at an initial loading rate of 100 mg/L.

Executive summary:

The acute toxicity of zirconium dioxide to Daphnia magna was studied under static conditions according to EU method C2. Daphnids were exposed to control and test chemical at an initial loading rate of 100 mg/L for 48 hours. Mortality and immobilization were observed after 24 and 48 hours.

No significant immobilization was observed at the loading rate of 100 mg/L. The 48-h NOEC and 48-h EC50 were thus superior to this value.

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 09 MAY 2006 to 30 JUL 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)

Version / remarks:

and 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 were added to stabilize 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 in 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

ACCLIMATION
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

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 immobilized).
The NOEC and EC0 were determined directly from the raw data.The EC50 and EC100 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: no mortality at the undiluted loading rate.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

LC50

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 (see IUCLID section 4.8). 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 effect was 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 yttrium/L, corresponding to 1.3 µg yttrium oxide/L

Validity criteria fulfilled:

yes

Conclusions:

Yttrium oxide has no acute toxic effect on Daphnia magna up to its solubility limit in the test water at a loading rate of 100 mg/L under the present test conditions.

Executive summary:

The 48-h acute toxicity of yttrium oxide to Daphnia magna was studied under static conditions according to the 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/immobilization 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 LC50 and NOEC were thus > 100 mg/L and >= 100 mg/L, respectively.

Description of key information

Based on results from the studies of Bazin (1994) and Seyfried (2007), in which the acute toxicity of respectively zirconium dioxide and yttrium oxide was investigated in Daphnia magna and in which no adverse effects were observed up to the limit concentration of 100 mg/L (nominal loading rate), it can be concluded that yttrium zirconium oxide is not expected to cause toxic effects in daphnids up to the limit concentration of 100 mg/L either.

Additional information

1. Information on zirconium dioxide (CAS# 1314-23-4)

In a study from Bazin (1994), the acute toxicity of the read across substance zirconium dioxide to Daphnia magna was studied under static conditions according to EU method C2. Daphnids were exposed to control and test chemical at an initial loading rate of 100 mg/L for 48 hours. Mortality and immobilization were observed after 24 and 48 hours. No significant immobilization was observed at the loading rate of 100 mg/L. The 48-h NOEC and 48-h EC50 were thus superior to this value.

2. Information on yttrium oxide (CAS# 1314-36-9)

In a study from Seyfried (2007), the acute toxicity of the read across substance yttrium oxide to Daphnia magna was assessed in accordance with the standardised guidelines OECD 202 and EU Method C.2 under GLP conditions. Daphnids were exposed to a loading rate of 100 mg/L for 48 hours under static test conditions. Immobilisation and any adverse reactions to exposure were recorded after 24 and 48 hours. The study showed that there were no toxic effects as no immobilisation was seen. Therefore the 48 hour LC50 and NOEC were > 100 mg/L and ≥100 mg/L respectively.

3. Conclusion on yttrium zirconium oxide

Both zirconium dioxide and yttrium oxide were demonstrated not to cause any immobilisation in acute daphnid toxicity studies at the loading rate of 100 mg/L. Therefore, it can be concluded that yttrium zirconium oxide will not be harmful to daphnids either.