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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Endpoint:
bioaccumulation in aquatic species, other
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.



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.
Endpoint:
bioaccumulation in aquatic species, other
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.



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.
Endpoint:
bioaccumulation in aquatic species, other
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.



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.
Endpoint:
bioaccumulation in aquatic species, other
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.



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.
Endpoint:
bioaccumulation in aquatic species, other
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.



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.
Endpoint:
bioaccumulation in aquatic species, other
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.



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.

Description of key information

This endpoint is covered by the results of a key study performed with zirconium dichloride oxide. This study (Garnham et al., 1993) was assigned a Klimisch score of 2 (reliable with restrictions). Bioconcentration factors were measured in cyanobacteria and microalgae and observed to be low. A key BCF value of 0.064 L/kg ww was selected as a worst case key value for use in case exposure calculations are needed for secondary poisoning (aquatic foodchain) or man via the environment.

Key value for chemical safety assessment

BCF (aquatic species):
0.064 L/kg ww

Additional information

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. This highest value can be considered as key value.