Yttrium zirconium oxide

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

bioaccumulation in aquatic species: algae / cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No analytical measurement performed. No GLP compliance. No international guideline mentioned.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Sorption/uptake - desorption study with various microalgae and cyanobacteria.

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Zirconium dichloride oxide was used as test substance. Nevertheless, when put in water, zirconium dichloride oxide hydrolyses rapidly and precipitates as zirconium dioxide. Therefore, zirconium dioxide is actually the substance being tested in this study.

Radiolabelling:

no

Test organisms (species):

Chlorella emersonii

Details on test organisms:

For the bioaccumulation test, algae in the exponential phase of growth were centrifuged. The supernatant was removed and the cells washed once with 10 mM sodium acetate buffer, pH 5.0. Cells were centrifuged and resuspended in 10 mM sodium acetate buffer, pH 5.0 to cell densities of 5 x 10 6 mL-1.

Route of exposure:

aqueous

Test type:

not specified

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

4 h

Total depuration duration:

24 h

Hardness:

No information available

Test temperature:

23°C

pH:

5

Dissolved oxygen:

No information available

TOC:

No information available

Salinity:

No information available

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume: 25 mL acid-washed plastic vials
- Biomass loading rate: 5. 10 6+ Cells/mL
- Replicates: 3

TEST MEDIUM / WATER PARAMETERS
- Growth medium: BG11 medium which comprised: 1.5 g NaNO3, 0.04 g K2HPO4, 0.075 g MgSO4.7 H2O, 0.036 g CaCl2.2 H2O, 0.006 g citric acid, 0.006 g ferric ammonium citrate, 0.001 g disodium ethylenediaminetetraacetate (Na2EDTA), 0.02 g NaHCO3, 1 mL trace metal mix A5 (2.86 g H3BO3, 1.81 g MnCl2.4 H2O, 0.222 g ZnSO4.7 H2O, 0.039 g Na2MoO2.2 H2O, 0.079 g CuSO4.5 H2O, 0.0494 g Co(NO3)2.6 H2O in 1 L distilled water.

OTHER TEST CONDITIONS
- Adjustment of pH: 10 mM sodium acetate buffer , pH 5.0
- Light intensity: 300 µE m-2 s-1

RANGE-FINDING / PRELIMINARY STUDY
- Test concentrations: Aliquots from 10 mM and 100 mM zirconium dichloride oxide aqueous solution were added to give a final concentration in the range of 0.5-50 mM

Nominal and measured concentrations:

Nominal concentrations : 0.5 to 50 mM of Zr
Actual concentration : 3.7 g/L

Details on estimation of bioconcentration:

UPTAKE:
The amount of Zr taken up by cells was calculated from the reduction of Zr in the buffer, after taking into account any binding to the plastic vial (determined in control experiments without cells).

DESORPTION :
Cell suspensions were prepared in 10 mM sodium acetate buffer, pH 5.0, with 100 µM zirconium dichloride oxide. Cell suspensions were then incubated for at least 24 h in the light. Three replicate samples (1 mL) were taken from the cell suspensions and centrifuged after which the supernatant was removed and the Zr concentration measured by polarography.

Key result

Type:

BCF

Value:

0.64 L/kg

Basis:

whole body d.w.

Time of plateau:

4 h

Calculation basis:

steady state

Remarks on result:

other: expressed in Zr

Remarks:

Conc.in environment / dose:3.7 g/L

Elimination:

yes

Parameter:

other: 28 to 87% of the Zr accumulated

Depuration time (DT):

5 min

Details on results:

Zr accumulation (µmol g dry wt-1) after 4h: 25.6+/- 0.7
Zr accumulation (µmol g dry wt-1) after 5 min: 25.0+/- 1.0

Validity criteria fulfilled:

yes

Conclusions:

In conclusion, the BCF value is very low for Chlorella emersonii. Zr accumulation in µmol g dry wt-1 was in the same order of magnitude after 5 minutes and 4 hours of exposure. Similarly, rapid desorption (within 5 min) has been observed.

Reference 2

Endpoint:

bioaccumulation in aquatic species: algae / cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No analytical measurement performed. No GLP compliance. No international guideline mentioned.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Sorption/uptake - desorption study with various microalgae and cyanobacteria.

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Zirconium dichloride oxide was used as test substance. Nevertheless, when put in water, zirconium dichloride oxide hydrolyses rapidly and precipitates as zirconium dioxide. Therefore, the actual test substance was zirconium dioxide.

Radiolabelling:

no

Test organisms (species):

other: Synechococcus PCC 6301

Details on test organisms:

For the bioaccumulation test, algae in the exponential phase of growth were centrifuged. The supernatant was removed and the cells washed once with 10 mM sodium acetate buffer, pH 5.0. Cells were centrifuged and resuspended in 10 mM sodium acetate buffer, pH 5.0 to cell densities of 5 x 10 8 mL-1.

Route of exposure:

aqueous

Test type:

not specified

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

4 h

Total depuration duration:

24 h

Hardness:

No information available

Test temperature:

23°C

pH:

5

Dissolved oxygen:

No information available

TOC:

No information available

Salinity:

No information available

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume: 25 mL acid-washed plastic vials
- Biomass loading rate: 5. 10 6+ Cells/mL
- Replicates: 3

TEST MEDIUM / WATER PARAMETERS
- Growth medium: BG11 medium which comprised: 1.5 g NaNO3, 0.04 g K2HPO4, 0.075 g MgSO4.7H2O, 0.036 g CaCl2.2H2O, 0.006 g citric acid, 0.006 g ferric ammonium citrate, 0.001 g disodium ethylenediaminetetraacetate (Na2EDTA), 0.02 g NaHCO3, 1 mL trace metal mix A5 (2.86 g H3BO3, 1.81 g MnCl2.4H2O, 0.222 g ZnSO4.7H2O, 0.039 g Na2MoO2.2H2O, 0.079 g CuSO4.5H2O, 0.0494 g Co(NO3)2.6H2O in 1 L distilled water.

OTHER TEST CONDITIONS
- Adjustment of pH: 10 mM sodium acetate buffer , pH 5.0
- Light intensity: 300 µE m-2 s-1

RANGE-FINDING / PRELIMINARY STUDY
- Test concentrations: Aliquots from 10 mM and 100 mM zirconium dichloride oxide aqueous solution were added to give a final concentration in the range of 0.5-50 mM

Nominal and measured concentrations:

Nominal concentrations : 0.5 to 50 mM of Zr
Actual concentration : 3.7 g/L

Details on estimation of bioconcentration:

UPTAKE:
The amount of Zr taken up by cells was calculated from the reduction of Zr in the buffer, after taking into account any binding to the plastic vial (determined in control experiments without cells).

DESORPTION :
Cell suspensions were prepared in 10 mM sodium acetate buffer, pH 5.0, with 100 µM zirconium dichloride oxide. Cell suspensions were then incubated for at least 24 h in the light. Three replicate samples (1 mL) were taken from the cell suspensions and centrifuged after which the supernatant was removed and the Zr concentration measured by polarography.

Key result

Type:

BCF

Value:

0.455 L/kg

Basis:

whole body d.w.

Time of plateau:

4 h

Calculation basis:

steady state

Remarks on result:

other: expressed in Zr

Remarks:

Conc.in environment / dose:3.7 g/L

Elimination:

yes

Parameter:

other: 28 to 87% of the Zr accumulated

Depuration time (DT):

5 min

Details on results:

Zr accumulation (µmol g dry wt-1) after 4h: 18.2+/- 0.8
Zr accumulation (µmol g dry wt-1) after 5 min: 19.9+/- 0.1

Validity criteria fulfilled:

yes

Conclusions:

In conclusion, the BCF value is very low for Synechococcus sp. Zr accumulation in µmol g dry wt-1 was in the same order of magnitude after 5 minutes and 4 hours of exposure. As well, rapid desorption (within 5 min) has been observed.

Reference 3

Endpoint:

bioaccumulation in aquatic species: algae / cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No analytical measurement performed. No GLP compliance. No international guideline mentioned.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Sorption/uptake - desorption study with various microalgae and cyanobacteria.

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Zirconium dichloride oxide was used as test substance. Nevertheless, when put in water, zirconium dichloride oxide hydrolyses rapidly and precipitates as zirconium dioxide. Therefore, the actual test substance was zirconium dioxide.

Radiolabelling:

no

Test organisms (species):

other: Synechococcus PCC 6803

Details on test organisms:

For the bioaccumulation test, algae in the exponential phase of growth were centrifuged. The supernatant was removed and the cells washed once with 10 mM sodium acetate buffer, pH 5.0. Cells were centrifuged and resuspended in 10 mM sodium acetate buffer, pH 5.0 to cell densities of 5 x 10 8 mL-1.

Route of exposure:

aqueous

Test type:

not specified

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

4 h

Total depuration duration:

24 h

Hardness:

No information available

Test temperature:

23°C

pH:

5

Dissolved oxygen:

No information available

TOC:

No information available

Salinity:

No information available

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume: 25 mL acid-washed plastic vials
- Biomass loading rate: 5. 10 8+ Cells/mL
- Replicates: 3

TEST MEDIUM / WATER PARAMETERS
- Growth medium: BG11 medium which comprised: 1.5 g NaNO3, 0.04 g K2HPO4, 0.075 g MgSO4.7H2O, 0.036 g CaCl2.2H2O, 0.006 g citric acid, 0.006 g ferric ammonium citrate, 0.001 g disodium ethylenediaminetetraacetate (Na2EDTA), 0.02 g NaHCO3, 1 mL trace metal mix A5 (2.86 g H3BO3, 1.81 g MnCl2.4H2O, 0.222 g ZnSO4.7H2O, 0.039 g Na2MoO2.2H2O, 0.079 g CuSO4.5H2O, 0.0494 g Co(NO3)2.6 H2O in 1 L distilled water.

OTHER TEST CONDITIONS
- Adjustment of pH: 10 mM sodium acetate buffer , pH 5.0
- Light intensity: 300 µE m-2 s-1

RANGE-FINDING / PRELIMINARY STUDY
- Test concentrations: Aliquots from 10 mM and 100 mM zirconium dichloride oxide aqueous solution were added to give a final concentration in the range of 0.5-50 mM

Nominal and measured concentrations:

Nominal concentrations : 0.5 to 50 mM of Zr
Actual concentration : 3.7 g/L

Details on estimation of bioconcentration:

UPTAKE:
The amount of Zr taken up by cells was calculated from the reduction of Zr in the buffer, after taking into account any binding to the plastic vial (determined in control experiments without cells).

DESORPTION :
Cell suspensions were prepared in 10 mM sodium acetate buffer, pH 5.0, with 100 µM zirconium dichloride oxide. Cell suspensions were then incubated for at least 24 h in the light. Three replicate samples (1 mL) were taken from the cell suspensions and centrifuged after which the supernatant was removed and the Zr concentration measured by polarography.

Key result

Type:

BCF

Value:

0.052 L/kg

Basis:

whole body d.w.

Time of plateau:

4 h

Calculation basis:

steady state

Remarks on result:

other: expressed in Zr

Remarks:

Conc.in environment / dose:3.7 g/L

Elimination:

yes

Parameter:

other: 28 to 87% of the Zr accumulated

Depuration time (DT):

5 min

Details on results:

Zr accumulation (µmol g dry wt-1) after 4h: 2.1+/- 0.5
Zr accumulation (µmol g dry wt-1) after 5 min: 1.85+/- 0.2

Validity criteria fulfilled:

yes

Conclusions:

In conclusion, the BCF value is very low for Synechococcus sp. Zr accumulation in µmol g dry wt-1 was at the same order of magnitude after 5 minutes and 4 hours of exposure. As well, rapid desorption (within 5 min) has been observed.

Reference 4

Endpoint:

bioaccumulation in aquatic species: algae / cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No analytical measurement performed. No GLP compliance. No international guideline mentioned.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Sorption/uptake - desorption study with various microalgae and cyanobacteria.

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Zirconium dichloride oxide was used as test substance. Nevertheless, when put in water, zirconium dichloride oxide hydrolyses rapidly and precipitates as zirconium dioxide. Therefore, the actual test substance was zirconium dioxide.

Radiolabelling:

no

Test organisms (species):

other: Plectonema boryanum

Details on test organisms:

For the bioaccumulation test, algae in the exponential phase of growth were centrifuged. The supernatant was removed and the cells washed once with 10 mM sodium acetate buffer, pH 5.0. Cells were centrifuged and resuspended in 10 mM sodium acetate buffer, pH 5.0 to cell densities of OD680 of approx. 6.

Route of exposure:

aqueous

Test type:

not specified

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

4 h

Total depuration duration:

24 h

Hardness:

No information available

Test temperature:

23°C

pH:

5

Dissolved oxygen:

No information available

TOC:

No information available

Salinity:

No information available

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume: 25 mL acid-washed plastic vials
- Biomass loading rate: OD680 of approx. 6
- Replicates: 3

TEST MEDIUM / WATER PARAMETERS
- Growth medium: BG11 medium which comprised: 1.5 g NaNO3, 0.04 g K2HPO4, 0.075 g MgSO4.7H2O, 0.036 g CaCl2.2H2O, 0.006 g citric acid, 0.006 g ferric ammonium citrate, 0.001 g disodium ethylenediaminetetraacetate (Na2EDTA), 0.02 g NaHCO3, 1 mL trace metal mix A5 (2.86 g H3BO3, 1.81 g MnCl2.4H2O, 0.222 g ZnSO4.7H2O, 0.039 g Na2MoO2.2H2O, 0.079 g CuSO4.5H2O, 0.0494 g Co(NO3)2.6 H2O in 1 L distilled water).

OTHER TEST CONDITIONS
- Adjustment of pH: 10 mM sodium acetate buffer , pH 5.0
- Light intensity: 300 µE m-2 s-1

RANGE-FINDING / PRELIMINARY STUDY
- Test concentrations: Aliquots from 10 mM and 100 mM zirconium dichloride oxide aqueous solution were added to give a final concentration in the range of 0.5-50 mM

Nominal and measured concentrations:

Nominal concentrations : 0.5 to 50 mM of Zr
Actual concentration : 3.7 g/L

Details on estimation of bioconcentration:

UPTAKE:
The amount of Zr taken up by cells was calculated from the reduction of Zr in the buffer, after taking into account any binding to the plastic vial (determined in control experiments without cells).

DESORPTION :
Cells suspensions were prepared in 10 mM sodium acetate buffer, pH 5.0, with 100 µM zirconium dichloride oxide. Cell suspensions were then incubated for at least 24 h in the light. Three replicates samples (1 mL) were taken from the cell suspensions and centrifuged after which the supernatant was removed and the Zr concentration measured by polarography.

Key result

Type:

BCF

Value:

0.4 L/kg

Basis:

whole body d.w.

Time of plateau:

4 h

Calculation basis:

steady state

Remarks on result:

other: expressed in Zr

Remarks:

Conc.in environment / dose:3.7 g/L

Elimination:

yes

Parameter:

other: 28 to 87% of the Zr accumulated

Depuration time (DT):

5 min

Details on results:

Zr accumulation (µmol g dry wt-1) after 4h: 16.0+/- 0.1
Zr accumulation (µmol g dry wt-1) after 5 min: 16.8+/- 0.1

Validity criteria fulfilled:

yes

Conclusions:

In conclusion, the BCF value is very low for Plectonema boryanum. Zr accumulation in µmol g dry wt-1 was at the same order of magnitude after 5 minutes and 4 hours of exposure. As well, rapid desorption (within 5 min) has been observed.

Reference 5

Endpoint:

bioaccumulation in aquatic species: algae / cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No analytical measurement performed. No GLP compliance. No international guideline mentioned.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Sorption/uptake - desorption study with various microalgae and cyanobacteria.

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Zirconium dichloride oxide was used as test substance. Nevertheless, when put in water, zirconium dichloride oxide hydrolyses rapidly and precipitates as zirconium dioxide. Therefore, the actual test substance was zirconium dioxide.

Radiolabelling:

no

Test organisms (species):

other: Scenedesmus obliquus

Details on test organisms:

For the bioaccumulation test, algae in the exponential phase of growth were centrifuged. The supernatant was removed and the cells washed once with 10 mM sodium acetate buffer, pH 5.0. Cells were centrifuged and resuspended in 10 mM sodium acetate buffer, pH 5.0 to cell densities of 5 x 10 7 mL-1.

Route of exposure:

aqueous

Test type:

not specified

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

4 h

Total depuration duration:

24 h

Hardness:

No information available

Test temperature:

23°C

pH:

5

Dissolved oxygen:

No information available

TOC:

No information available

Salinity:

No information available

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume: 25 mL acid-washed plastic vials
- Biomass loading rate: 5. 10 7+ Cells/mL
- Replicates: 3

TEST MEDIUM / WATER PARAMETERS
- Growth medium: BG11 medium which comprised: 1.5 g NaNO3, 0.04 g K2HPO4, 0.075 g MgSO4.7H2O, 0.036 g CaCl2.2H2O, 0.006 g citric acid, 0.006 g ferric ammonium citrate, 0.001 g disodium ethylenediaminetetraacetate (Na2EDTA), 0.02 g NaHCO3, 1 mL trace metal mix A5 (2.86 g H3BO3, 1.81 g MnCl2.4H2O, 0.222 g ZnSO4.7H2O, 0.039 g Na2MoO2.2H2O, 0.079 g CuSO4.5H2O, 0.0494 g Co(NO3)2.6 H2O in 1 L distilled water.

OTHER TEST CONDITIONS
- Adjustment of pH: 10 mM sodium acetate buffer , pH 5.0
- Light intensity: 300 µE m-2 s-1

RANGE-FINDING / PRELIMINARY STUDY
- Test concentrations: Aliquots from 10 mM and 100 mM zirconium dichloride oxide aqueous solution were added to give a final concentration in the range of 0.5-50 mM

Nominal and measured concentrations:

Nominal concentrations : 0.5 to 50 mM of Zr
Actual concentration : 3.7 g/L

Details on estimation of bioconcentration:

UPTAKE:
The amount of Zr taken up by cells was calculated from the reduction of Zr in the buffer, after taking into account any binding to the plastic vial (determined in control experiments without cells).

DESORPTION :
Cell suspensions were prepared in 10 mM sodium acetate buffer, pH 5.0, with 100 µM zirconium dichloride oxide. Cell suspensions were then incubated for at least 24 h in the light. Three replicate samples (1 mL) were taken from the cell suspensions and centrifuged after which the supernatant was removed and the Zr concentration measured by polarography.

Key result

Type:

BCF

Value:

0.55 L/kg

Basis:

whole body d.w.

Time of plateau:

4 h

Calculation basis:

steady state

Remarks on result:

other: expressed in Zr

Remarks:

Conc.in environment / dose:3.7 g/L

Elimination:

yes

Parameter:

other: 28 to 87% of the Zr accumulated

Depuration time (DT):

5 min

Details on results:

Zr accumulation (µmol g dry wt-1) after 4h: 22.0+/- 0.6
Zr accumulation (µmol g dry wt-1) after 4h: 21.3+/- 0.5

Validity criteria fulfilled:

yes

Conclusions:

In conclusion, the BCF value is very low for Scenedesmus obliquus. Zr accumulation in µmol g dry wt-1 was at the same order of magnitude after 5 minutes and 4 hours of exposure. As well, rapid desorption (within 5 min) has been observed.

Reference 6

Endpoint:

bioaccumulation in aquatic species: algae / cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No analytical measurement performed. No GLP compliance. No international guideline mentioned.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Sorption/uptake - desorption study with various microalgae and cyanobacteria.

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Zirconium dichloride oxide was used as test substance. Nevertheless, when put in water, zirconium dichloride oxide hydrolises rapidly and precipitates as zirconium dioxide. Therefore, the actual test substance was zirconium dioxide.

Radiolabelling:

no

Test organisms (species):

other: Chlamydomonas reinhardtii

Details on test organisms:

For the bioaccumulation test, algae in the exponential phase of growth were centrifuged. The supernatant was removed and the cells washed once with 10 mM sodium acetate buffer, pH 5.0. Cells were centrifuged and resuspended in 10 mM sodium acetate buffer, pH 5.0 to cell densities of 1 x 10 7 mL-1.

Route of exposure:

aqueous

Test type:

not specified

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

4 h

Total depuration duration:

24 h

Hardness:

No information available

Test temperature:

23°C

pH:

5

Dissolved oxygen:

No information available

TOC:

No information available

Salinity:

No information available

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume: 25 mL acid-washed plastic vials
- Biomass loading rate: 1. 10 7+ Cells/mL
- Replicates: 3

TEST MEDIUM / WATER PARAMETERS
- Growth medium: BG11 medium which comprised: 1.5 g NaNO3, 0.04 g K2HPO4, 0.075 g MgSO4.7H2O, 0.036 g CaCl2.2H2O, 0.006 g citric acid, 0.006 g ferric ammonium citrate, 0.001 g disodium ethylenediaminetetraacetate (Na2EDTA), 0.02 g NaHCO3, 1 mL trace metal mix A5 (2.86 g H3BO3, 1.81 g MnCl2.4H2O, 0.222 g ZnSO4.7H2O, 0.039 g Na2MoO2.2H2O, 0.079 g CuSO4.5H2O, 0.0494 g Co(NO3)2.6H2O in 1 L distilled water.

OTHER TEST CONDITIONS
- Adjustment of pH: 10 mM sodium acetate buffer , pH 5.0
- Light intensity: 300 µE m-2 s-1

RANGE-FINDING / PRELIMINARY STUDY
- Test concentrations: Aliquots from 10 mM and 100 mM zirconium dichloride oxide aqueous solution were added to give a final concentration in the range of 0.5-50 mM

Nominal and measured concentrations:

Nominal concentrations : 0.5 to 50 mM of Zr
Actual concentration : 3.7 g/L

Details on estimation of bioconcentration:

UPTAKE:
The amount of Zr taken up by cells was calculated from the reduction of Zr in the buffer, after taking into account any binding to the plastic vial (determined in control experiments without cells).

DESORPTION :
Cell suspensions were prepared in 10 mM sodium acetate buffer, pH 5.0, with 100 µM zirconium dichloride oxide. Cell suspensions were then incubated for at least 24 h in the light. Three replicate samples (1 mL) were taken from the cell suspensions and centrifuged after which the supernatant was removed and the Zr concentration measured by polarography.

Key result

Type:

BCF

Value:

0.188 L/kg

Basis:

whole body d.w.

Time of plateau:

4 h

Calculation basis:

steady state

Remarks on result:

other: expressed in Zr

Remarks:

Conc.in environment / dose:3.7 g/L

Elimination:

yes

Parameter:

other: 28 to 87% of the Zr accumulated

Depuration time (DT):

5 min

Details on results:

Zr accumulation (µmol g dry wt-1) after 4h: 7.5+/- 0.5
Zr accumulation (µmol g dry wt-1) after 5 min : 11.2+/- 0.6

Validity criteria fulfilled:

yes

Conclusions:

In conclusion, the BCF value is very low for Chlamydomonas reinhardtii. Zr accumulation in µmol g dry wt-1 was at the same order of magnitude after 5 minutes and 4 hours of exposure. As well, rapid desorption (within 5 min) has been observed.

Reference 7

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well performed study, however, a K2 (reliable with restrictions) was assigned because measured Y concentrations in test medium were not reported.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Bioaccumulation of representative light (yttrium), medium (lanthanum) and heavy (gadolinium) REEs in a variety of tissues of Cyprinus carpio are investigated. Therefore, the fish were exposed to solutions containing 0.5 mg/L of each element separately for 45 d and sacrificed at time intervals. No depuration study was followed by the uptake studies.

GLP compliance:

not specified

Radiolabelling:

no

Details on sampling:

- Sampling intervals/frequency for test organisms and test medium: 5, 10, 17, 24, 31, 38 and 45 d
- Four fish were sacrificed from each of the test groups at each time interval.

Vehicle:

no

Details on preparation of test solutions, spiked fish food or sediment:

Stock solutions (5 mg/L) of individual REEs were added dropwise to the diluent water, stirring to make final concentration of 0.50 mg/L. Individual treatments were used, as well as a mixed treatment containing both Y, Gd, and La.

Test organisms (species):

Cyprinus carpio

Details on test organisms:

TEST ORGANISM
- Common name: carp
- Age at study initiation (mean and range, SD): first-year juveniles
- Length at study initiation (length definition, mean, range and SD): 5.5-7.3 cm (average: 6.4 cm)
- Weight at study initiation (mean and range, SD): 4.2-8.7 g (average 6.2 g)
- Feeding during test: the fish were fed on dry food 1 h prior to each renewal

ACCLIMATION
- Acclimation period: 10d
- Health during acclimation (any mortality observed): mortality rate was less than 5 %

Route of exposure:

aqueous

Test type:

semi-static

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

45 d

Hardness:

53-60 mg/L as CaO

Test temperature:

11-14°C

pH:

adjusted to 6.0

Dissolved oxygen:

> 7.0 mg/L

TOC:

no data

Salinity:

not applicable

Details on test conditions:

TEST SYSTEM
- Test vessel: 20 L aquarium, containing 15 L dilution water
- Renewal rate of test solution (frequency/flow rate): 10 L test solution was renewed in each aquarium every other day
- No. of organisms per vessel (test concentration): 20
- No. of organisms per vessel (control): 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: tap water, purified and dechlorinated
- Chloride: 7.0-8.5 mg/L
- Total alkalinity: 1.15-2.15 mmol/L
- Conductivity: 170 (mOhm*cm)-1

OTHER TEST CONDITIONS
- Adjustment of pH: yes (by HNO3)

RANGE-FINDING / PRELIMINARY STUDY
- Test concentration: value chosen was close to the concentration in a natural aquatic environment

Nominal and measured concentrations:

0.5 mg/L (nominal)
Measured data not shown (nominal concentrations were not maintained, sometimes the measured values were as little as one-tenth of the initial one. Actual test concentration (e.g. geometric mean) could not be assessed, because the pH was constantly changing and the test solution was replaced partly every 2 days).

Reference substance (positive control):

no

Details on estimation of bioconcentration:

Control animals were used for analysis of the background value in carp. Measured RE concentrations in tissue were corrected for background concentrations.
The maximum bioconcentration factor (BCFmax) is calculated by dividing the maximum concentration of the test substance in certain tissues of carp by the nominal concentration of the same element in the test water.

Type:

BCF

Value:

3.8

Basis:

organ w.w.

Remarks:

skeleton

Calculation basis:

other: maximum concentration in tissue

Remarks on result:

other: Conc.in environment / dose:0.5 mg/L

Type:

BCF

Value:

1.3

Basis:

organ w.w.

Remarks:

muscle

Calculation basis:

other: maximum concentration in tissue

Remarks on result:

other: Conc.in environment / dose:0.5 mg/L

Type:

BCF

Value:

8

Basis:

organ w.w.

Remarks:

gills

Calculation basis:

other: maximum concentration in tissue

Remarks on result:

other: Conc.in environment / dose:0.5 mg/L

Type:

BCF

Value:

54

Basis:

organ w.w.

Remarks:

internal organs

Calculation basis:

other: maximum concentration in tissue

Remarks on result:

other: Conc.in environment / dose:0.5 mg/L

Details on kinetic parameters:

It is observed that the bioaccumulation values in various tissues of carp increased with time. At the end of the 45-day exposure period, equilibria were reached or approached.

Details on results:

There was no mortality of fish during the 45-day exposure period.

Only results for yttrium are shown here.

Table 1: Background values of yttrium in Cyprinus carpio

tissue	Y concentration (µg/g wet weight)
	before test	after test	average
gills	0.02	0.03	0.02
muscle	0.01	0.01	0.01
skeleton	0.03	0.03	0.03
internal organs	0.02	0.02	0.02

Content of yttrium in the dry fish food was under the detection limit.

Table 2: Bioaccumulation in Cyprinus carpio exposed to 0.5 mg/L yttrium

tissue	Y concentration (µg/g wet weight)
	5 d	10 d	17 d	24 d	31 d	38 d	45 d
skeleton	0.43	0.91	1.30	1.75	1.52	1.49	1.89
muscle	0.09	0.24	0.16	0.35	0.59	0.67	0.48
gills	1.87	2.32	2.94	3.95	3.41	3.07	?
internal organs	6.82	15.9	19.3	24.5	22.7	21.1	23.6

Conclusions:

In this study, Cyprinus carpio (carp) was exposed for up to 45 days to 0.5 mg Y/L (as well as a mixture of 0.5 mg/L of La, Gd and Y) and frequent samples of fish were taken for analysis of Y in tissues (muscle, skeleton, gills, internal organs). The maximal BCF values obtained were 3.8, 1.3, 8.0 and 54 L/kg ww for skeleton, muscle, gills and internal organs, respectively; indicating that the bioaccumulation potential of yttrium in fish is low. Measured concentrations in test medium were not reported hence actual BCFs may have been somewhat higher.

Reference 8

Endpoint:

bioaccumulation in aquatic species, other

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well performed study, however, it is not entirely clear why for certain organisms no BCF/BAF values were reported, since data in figures indicate relevant bioconcentration/bioaccumulation. Mixed exposure.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Microcosm study for evaluation of distribution and bioavailability of rare earth elements. Duckweed (phytoplankton), Daphnia (crustaceans), shellfish (benthic species) and goldfish (fishes) were used as representative aquatic community.

GLP compliance:

not specified

Radiolabelling:

no

Details on sampling:

Water, sediment, duckweed, daphnids: sampled at 12, 24, 48, 96, 192, 288, 384 h.
Shellfish and goldfish: sampled at 48, 96, 192, 288, 384 h.
Water samples: 5 mL, filtered 0.45 µm.
Sediment samples: washed by deionised water, dried by air, 0.5 g digested with Na2O2 under 700°C and passed through cation-exchange columns.
Organism samples: 50 mg duckweeds, 30 daphnids, 1 shellfish, 1 goldfish digested (HNO3 and HClO4). Final solutions brought to 5 mL with 7% HCl.

Vehicle:

no

Details on preparation of test solutions, spiked fish food or sediment:

Water and sediment samples were collected from an eutrophic lake - Xuanwu Lake in Nanjing, China.
Water 0.45 µm filtered.
Sediment samples dried by air and weighed before adding to aquarium.
Sediment was placed at the bottom of the aquarium to about 2 cm thick (aquarium of 20x50x50 cm).
50 L lake water was added.
After 1 week equilibration (with organisms added too), a stock solution (mixture of five REEs with 1.00 mg/mL each) was spiked into the aquarium to 1 mg/L.

Test organisms (species):

other: duckweed, Daphnia, shellfish, goldfish

Details on test organisms:

1. Duckweed (Sperollela polyrrhiza), cultured in laboratory.
2. Crustaceans (Daphnia magna), parthenogenetic females maintained in laboratory and fed unicellular green algae (Chlorella pyrenoidosa, cultures in HB-4 aqueous medium by the method of Hua (1986).
3: Goldfish (Carassius auratus): 5 cm body length, fed commercial fish food.
4. Shellfish (Bellamya aeruginosa): reared in laboratory.
All organisms acclimated to laboratory conditions one week prior to the experiment.

Route of exposure:

aqueous

Test type:

static

Water / sediment media type:

natural sediment: freshwater

Total exposure / uptake duration:

16 d

Hardness:

not reported

Test temperature:

water temperature held at 22 +/- 1 °C

pH:

kept at ca. 6.5-6.8

Dissolved oxygen:

not reported (continuous aeration)

TOC:

not reported

Salinity:

not applicable

Details on test conditions:

TEST SYSTEM
- Test vessel: aquarium
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: aquarium 20x50x50 cm), 50 L lake water, 2 cm thick sediment layer
- Aeration: yes
- No. of organisms per vessel: 400 adult daphnids (placed in nylon cage 15x15x20 cm with 1x1 mm mesh to maintain adult daphnids while allowing larvae to swim through freely), 20 g duckweeds (ww), 30 shellfish, 15 goldfish
- No. of vessels per concentration (replicates): 1
- No. of vessels per control / vehicle control (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Lake water (Xuanwu Lake, Nanjing, China)
- Holding medium different from test medium: yes
- Intervals of water quality measurement: physicochemical characteristics of sediment and water of Xuanwu Lake have been studied by Nanjing EPA (1996).

OTHER TEST CONDITIONS
- Adjustment of pH: pH kept at 6.5-6.8 because REEs will precipitate under alkaline conditions
- Photoperiod: 12L:12D
- Light intensity: not reported, fluorescent lamps used

Nominal and measured concentrations:

nominal: 1 mg Y/L
measured: ca. 20 µg Y/L, as apparent from Figure

Reference substance (positive control):

no

Details on estimation of bioconcentration:

BCF/BAF values calculated dividing concentrations in test species (mg/kg ww), corrected for background concentrations observed in the control, by concentrations in test water (mg/L).

Type:

BAF

Value:

27.36 L/kg

Basis:

whole body w.w.

Calculation basis:

steady state

Remarks on result:

other: shellfish, reported in Table for 16 d sampling point

Remarks:

Conc.in environment / dose:ca. 0.02 mg Y/L

Type:

BCF

Value:

992.7 L/kg

Basis:

whole body w.w.

Calculation basis:

steady state

Remarks on result:

other: duckweed, reported in Table for 16 d sampling point

Remarks:

Conc.in environment / dose:ca. 0.02 mg Y/L

Type:

BAF

Value:

430.5 L/kg

Basis:

whole body w.w.

Calculation basis:

steady state

Remarks on result:

other: Daphnia, reported in Table for 16 d sampling point

Remarks:

Conc.in environment / dose:ca. 0.02 mg Y/L

Type:

BAF

Value:

ca. 2.5 L/kg

Basis:

whole body w.w.

Calculation basis:

steady state

Remarks on result:

other: goldfish, not reported in Table but derived based on Figure for 16 d sampling point

Remarks:

Conc.in environment / dose:ca. 0.02 mg Y/L

Details on results:

In fish and shellfish BAFs were rather low compared to Daphnia and duckweed.
BAF = Bioaccumulation factor, combined exposure via food and water (i.e., because this is a microcosm study in which the organisms are not administered external feed, the animals in the microcosm study were exposed both via water and via food).
BCF = Bioconcentration factor, exposure via water only (in this case relevant for the plants present in the microcosm study).

Reported statistics:

Student's t test for comparison of treatments with control, p <= 0.05.

Conclusions:

In this microcosm study, goldfish, shellfish, Daphnia and duckweed were exposed for up to 16 days to a single concentration of Y (added as a mixture of REEs). Y analysis in samples taken after 16 days of exposure yielded BCF/BAF values of ca. 2.5, 27.36, 430.5 and 992.7 L/kg ww for goldfish, shellfish, Daphnia and duckweed, respectively.

Reference 9

Endpoint:

bioaccumulation in aquatic species: invertebrate

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Scientific review listing available data on several endpoints. Source publication not available.

Remarks:

It is important to note that field studies provide snapshots in time of environmental concentrations of polluents and therefore cannot entirely guarantee steady state in the sampled organisms. For this reason, BAF values resulting from such studies have to be considered with caution.

Qualifier:

no guideline followed

Principles of method if other than guideline:

BAFs were determined in a field study for amphipods in salt and brackish water.

GLP compliance:

not specified

Radiolabelling:

not specified

Details on sampling:

no data

Vehicle:

no

Test organisms (species):

other: Corophium volutator (amphipoda)

Details on test organisms:

TEST ORGANISM
- Common name: mud shrimp
- Source: field collection

Route of exposure:

other: aqueous and sediment

Test type:

other: field study

Water / sediment media type:

natural sediment: marine

Hardness:

no data

Test temperature:

no data

pH:

8-8.5

Dissolved oxygen:

no data

TOC:

no data

Salinity:

30 g/L

Details on test conditions:

SEDIMENT
- harbour sediment from Nieuwe Maas, Rijnmond, The Netherlands

Nominal and measured concentrations:

Not reported by Sneller et al. (2000).

Details on estimation of bioconcentration:

Determination of BAF: content of Y in biota per content of Y in pore water (mg/kg dw per mg/L)

Type:

BAF

Value:

7 413

Basis:

whole body d.w.

Calculation basis:

other: assumed steady state

Remarks on result:

other: field data

Remarks:

Conc.in environment / dose:concentration in pore water: no data given

Conclusions:

In this study, field samples were taken from sediment and amphipods (Corophium volutator) from a harbour in the Netherlands. Based on Y measured in pore water and amphipods, a BAF of 7413 L/kg dw could be calculated. Y concentrations in pore water and supernatant water may have been very low. Note that a concentration dependency may exist for Y resulting in higher BAF values with decreasing Y concentrations in water.

Reference 10

Endpoint:

bioaccumulation in aquatic species, other

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, it is considered appropriate to cover this endpoint by data on bioconcentration/bioaccumulation of zirconium and yttrium. For zirconium, only one study is available: the study of Garnham et al. (1993). For yttrium three studies are available, reporting on bioconcentration/bioaccumulation of yttrium in aquatic plants (Yang et al., 1999), aquatic invertebrates (Yang et al., 1999; Stronkhorst and Yland, 1998), and fish (Yang et al., 1999; Tu et al., 1994). The read across justification is attached to IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Type:

BCF

Value:

0.064 L/kg

Remarks on result:

other: zirconium

Type:

BAF

Value:

4.65 L/kg

Remarks on result:

other: yttrium, average BAF value for fish

Description of key information

Following the read across strategy, it is considered appropriate to cover this endpoint by data on bioconcentration/bioaccumulation of zirconium and yttrium.
For zirconium, only one study is available: the study of Garnham et al. (1993), yielding a maximum BCF value of 0.064 L/kg ww for bioconcentration of zirconium (added as zirconium dichloride oxide, but quickly hydrolysed to zirconium dioxide and/or hydroxide) in cyanobacteria and microalgae. These results indicate that zirconium has no potential for bioconcentration/bioaccumulation.
For yttrium three studies are available, reporting on bioconcentration/bioaccumulation of yttrium in aquatic plants (Yang et al., 1999), aquatic invertebrates (Yang et al., 1999; Stronkhorst and Yland, 1998), and fish (Yang et al., 1999; Tu et al., 1994). Overall, the obtained BCF/BAF values were 992.7 L/kg ww for aquatic plants, 27.36 to 1482.6 L/kg ww for aquatic invertebrates, and 1.3 to 54 L/kg ww for fish. A key BAF value of 4.65 L/kg ww is calculated for fish. As for otherare earth elements, yttrium bioaccumulation seems to decrease when ascending the food chain. Therefore, the bioaccumulation potential of yttrium can be concluded to be low.
Due to the low water solubility of yttrium zirconium oxide as well as the individual substances yttrium oxide and zirconium dioxide, yttrium and zirconium bioavailability in the aquatic environment, after introduction of yttrium zirconium oxide, is expected to be very low. Consequently, based on the results on bioconcentration/bioaccumulation of yttrium and zirconium, no substantial bioconcentration/bioaccumulation is to be expected.

Additional information

1. Information on zirconium

The accumulation of zirconium by cyanobacteria and microalgae was characterized by Garnham et al. (1993). In this study the organisms were exposed to solutions of zirconium dichloride oxide. Actual exposure however was rather to zirconium dioxide, since zirconium dichloride oxide hydrolyses rapidly in aqueous solutions at environmentally relevant pH, resulting in the precipitation of zirconium as zirconium dioxide or hydroxide. In all cyanobacterial and microalgal species examined, accumulation consisted of a single rapid energy-independent phase ("biosorption"). No energy-dependent accumulation was observed. Biosorption of zirconium was concentration-dependent, followed a Freundlich adsorption isotherm, and was dependent on pH, showing decreasing accumulation with decreasing pH. Zirconium desorption from micro-algae and cyanobacteria was increased by increasing external cation concentrations or by decreasing the pH of the desorption agent. Overall, biosorption/bioaccumulation was very limited. BCF values between 0.0525 and 0.64 L/kg dw were obtained. Assuming 90% water content in the organisms, the highest value can be recalculated to a BCF of 0.064 L/kg ww. Since no bioconcentration/bioaccumulation data are available for zirconium for other groups of organisms, this BCF can be considered as the key BCF for zirconium.

2. Information on yttrium

Published data are available reporting on the bioaccumulation potential of yttrium.

Yang et al. (1999) studied the potential for bioaccumulation of rare earth elements in different species (duckweed, daphnids, shellfish and goldfish) in a static laboratory experiment using aquatic microcosms. In this microcosm study, goldfish, shellfish, daphnids and duckweed were exposed for up to 16 days to a single concentration of yttrium (added as yttrium oxide, together with other rare earth compounds). Yttrium analysis in samples taken after 16 days of exposure yielded BCF/BAF values of ca. 2.5, 27.36, 430.5, and 992.7 L/kg ww for goldfish, shellfish, daphnids, and duckweed, respectively.

The laboratory study of Tu et al. (1994) reported BCF values for muscle, skeleton, gills, and internal organs of carp (Cyprinus carpio) after 45 days of exposure to yttrium trinitrate. Maximum BCF values found during the 45-day exposure period for muscle tissue, skeleton, gills, and internal organs were 1.3, 3.8, 8.0 and 54 L/kg ww, respectively. The BCF values for internal organs were the highest but are not considered as a good indication of the bioconcentration potential of yttrium, since the alimentary tract reflects the normal transit of the substance. Anyhow, the results of this study, together with those of the microcosm study of Yang et al. (1999), indicates that yttrium has an extremely low bioaccumulation potential in fish.

Sneller et al. (2000) discussed the study of Stronkhorst and Yland (1998), which calculated BAF values for amphipods (Corophium volutator) taken from a harbour in the Netherlands. The BAF value from this study reported by Sneller et al. (2000) for yttrium was 7413 L/kg dw (corresponding to 1482.6 L/kg ww, assuming 20% dw).

From the available studies, BCF/BAF values for aquatic plants, aquatic invertebrates and fish were 992.7 L/kg ww, between 27.36 and 1482.6 L/kg ww, and between 1.3 and 54 L/kg ww, respectively. As for other rare earth elements, bioconcentration/bioaccumulation in fish seems to be substantially lower than in organisms at a lower level in the food chain. The fact that goldfish in a microcosm study (in which they could feed on other organisms present in the microcosm) did not bioaccumulate yttrium (estimated BAF value of 2.5 L/kg ww), indicates that any bioconcentration/bioaccumulation is levelled out when ascending the food chain. Clearly, yttrium has a very limited potential to bioaccumulate through the food chain and it definitely does not biomagnify. In case exposure assessments need to be performed, a value is needed that can be used for calculating exposure levels in prey via the generic scenario for secondary poisoning starting in the aquatic food chain, as well as for calculating exposure levels for exposure of man via the environment. An average (arithmetic mean) BAF of 4.65 L/kg ww for fish was therefore calculated based on the results of the two available studies. Before calculating the overall mean, a study-specific mean (geometric mean) was calculated for the study of Tu et al. (1994). All data were included, i.e. also data for internal organs. Therefore, the average BAF of 4.65 L/kg ww can be considered as a worst case value.

3. Conclusion on yttrium zirconium oxide

Based on the low water solubility of yttrium zirconium oxide as well as the individual components of the solid solution (zirconium dioxide and yttrium oxide), the bioavailability of yttrium and zirconium from yttrium zirconium oxide is anticipated to be extremely low in the aquatic environment. Any bioavailable yttrium or zirconium is not expected to bioaccumulate/biomagnify throughout the aquatic food chain to a significant extent, based on the available data on bioconcentration/bioaccumulation of zirconium and yttrium (see above). Based on these studies, it can be concluded that there is no concern for bioconcentration/bioaccumulation.