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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2012-09-18 to 2012-09-20
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
see section 13.1 for read-across justification
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
Samples of the test media (all concentrations and control) were taken from the preparat ion flasks prior to distribution to test vessels at the test start. At test end (48 h), further samples of test media (all concentrations and control) were taken from pooled replicate vessels according to treatment.
Duplicate test media samples of ca. 20 mL were taken on each occasion.
Vehicle:
no
Details on test solutions:
Due to the very low water solubility of tellurium dioxide, the appropriate method of dosing the test item was to prepare a water accommodated
fraction (WAF) in accordance with the OECD guidance documents No. 23 and No. 29.

A concentrated stock solution of tellurium dioxide was prepared by dissolving 100 mg in 1 L of copper-free dilution water and the solution stirred at 100 rpm, to avoid bubble and foam formation, using a star shape magnetic stirring bar, for 48 h at room temperature (about 20°C). The test
preparation was then filtered using a 0.2 11m filter (e.g. Sartolab 150v, PESmembrane, Sartorius Stedim Biotech SA , Aubagne Cedex, France) to
separate insoluble parts from the aqueous phase.

The filtrated WAF eluate formed the 100 mg/L test loading. The 50.0, 25.0, 12.5, and 6.25 mg/L test concentrations were prepared by diluting 500,
250, 125, and 62.5 mL of the WAF to a final volume of 1L with dilution water, respectively. The control medium was prepared similarly using dilution water.
All test media was used within 1-2 hours of final preparation. The concentration of tellurium dioxide in the aqueous phase was chemically analysed
from the fresh and aged solutions at test start and end, respectively.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Source: German Federal Environment Agency , Institute for Water, Soil, and Air Hygiene.
- Age at study initiation (mean and range, SD): less than 24 hours
- Method of breeding: stock culture animals were held in batches of 30 - 50 adults at room temperature in ca. 1.8 L of dilution water for one week.
- Feeding during test: no


ACCLIMATION
- Acclimation period: 1 hour

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
Total hardness: 1.0 mmol/L
Test temperature:
The temperature of the incubator was 20.1°C at both test start and end.
pH:
The pH of all treatments ranged between 7.85 and 8.48.
Dissolved oxygen:
The oxygen saturation in the control vessels ranged between 8.0 - 8.6 mg O2/L.
Nominal and measured concentrations:
Nominal test concentrations: 6.25, 12.5, 25, 50 100 mg/L
Corresponding mean measured concentrations: 2.23, 4.55, 8.74, 19.72, 37.90 mg TeO2/L
Details on test conditions:
TEST SYSTEM
- Test vessel:60 mL glass beakers
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 50 mL
- Aeration: no

- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Purified drinking water
- Total organic carbon: 1.154 mg/L DOC
- Particulate matter:
- Metals µg/L: cooper < 1.51; iron < 5.7, manganese < 0.452, zinc 1.70
- Pesticides: no data
- Chlorine total residual: < 0.02 mg/L
- Alkalinity: 2.0 mmol/L
- Ca: 0.8 mmol/L
- Conductivity: 244.5 µS/cm
- Culture medium different from test medium: no
- Intervals of water quality measurement: regularly

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: light/dark cycle of 16/8 hours
- Light intensity: 508 - 528 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study
- Test concentrations: loading WAF of 100 mg/L, 10-fold and 100-fold dilutions.
- Results used to determine the conditions for the definitive study: At the loading of 100 mg/L, 100% mortality was observed after 48 h.
Thus, it was agreed that the definitive test would be performed with a maximum nominal WAF loading of 100 mg/L.
Reference substance (positive control):
no
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
7.24 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
dissolved
Remarks:
Tellurium dioxide
Basis for effect:
mobility
Remarks on result:
other: CL (6.4 - 8.3)
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
4.55 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
dissolved
Remarks:
Tellurium dioxide
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
5.79 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
dissolved
Remarks:
Tellurium
Basis for effect:
mobility
Remarks on result:
other: CL (5.1 - 6.6)
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
3.64 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
dissolved
Remarks:
Tellurium
Basis for effect:
mobility
Validity criteria fulfilled:
yes
Conclusions:
The EC50 for immobilisation of Daphnia magna by tellurium dioxide is 7.24 mg/L.
The EC50 for immobilisation of Daphnia magna by tellurium is 5.79 mg/L .
Executive summary:

The effect of tellurium dioxide on the acute immobilisation of Daphnia magna was investigated. The study was conducted according to the OECD guideline 202. Juveniles were exposed for 48 hours to the test item and the effects compared to a control group of dilution water only. The control and treatmen t groups consisted of four replicates each housing five daphnids. The test item media was prepared from a WAF with the nominal loading of 100 mg tellurium dioxide/l that was diluted to form the remaining concentrations of 50.0, 25.0, 12.5, and 6.25 mg/L. Samples were taken for chemical analysis from fresh and aged media at test start and end, respectively. The chemical analysis of tellurium in both the fresh lest and aged media revealed measured concentrations between 33.57 - 40 .53% of the nominal concentrations. As the concentration of tellurium was stable during the test the mean measured concentrations were calculated and converted to mean tellurium dioxide concentrations. The mean measured concentrations of tellurium were 1.78, 3.64, 6.99,15.77, and 30.3 mg/L. The mean measured concentrations of tellurium dioxide were 2.23, 4 .55, 8.74, 19.72, and 37.9 mg/L.

At 24 hours , an immobilisation effect of 70% in the highest test concentration was observed . After 48 hours, further concentration dependent effects of tellurium dioxide were apparent. Immobilisation was statistically significant in the three highest test concentrations at 80, 100 , and 100%, respectively . The NOEC is 4.55 mg Te02/L (3.64 mg Te/L). The EC50 is 7.24 mg Te02/L (5.79 mg Te/L).

The test fulfilled the validity criteria.

Conclusion

The EC50 for immobilisation of Daphnia magna by tellurium dioxide is 7.24 mg/L.

The EC50 for immobilisation of Daphnia magna by tellurium is 5.79 mg/L .

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012-09-18 to 2012-09-20
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
Samples of the test media (all concentrations and control) were taken from the preparat ion flasks prior to distribution to test vessels at the test start. At test end (48 h), further samples of test media (all concentrations and control) were taken from pooled replicate vessels according to treatment.
Duplicate test media samples of ca. 20 mL were taken on each occasion.
Vehicle:
no
Details on test solutions:
Due to the very low water solubility of tellurium dioxide, the appropriate method of dosing the test item was to prepare a water accommodated
fraction (WAF) in accordance with the OECD guidance documents No. 23 and No. 29.

A concentrated stock solution of tellurium dioxide was prepared by dissolving 100 mg in 1 L of copper-free dilution water and the solution stirred at 100 rpm, to avoid bubble and foam formation, using a star shape magnetic stirring bar, for 48 h at room temperature (about 20°C). The test
preparation was then filtered using a 0.2 11m filter (e.g. Sartolab 150v, PESmembrane, Sartorius Stedim Biotech SA , Aubagne Cedex, France) to
separate insoluble parts from the aqueous phase.

The filtrated WAF eluate formed the 100 mg/L test loading. The 50.0, 25.0, 12.5, and 6.25 mg/L test concentrations were prepared by diluting 500,
250, 125, and 62.5 mL of the WAF to a final volume of 1L with dilution water, respectively. The control medium was prepared similarly using dilution water.
All test media was used within 1-2 hours of final preparation. The concentration of tellurium dioxide in the aqueous phase was chemically analysed
from the fresh and aged solutions at test start and end, respectively.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Source: German Federal Environment Agency , Institute for Water, Soil, and Air Hygiene.
- Age at study initiation (mean and range, SD): less than 24 hours
- Method of breeding: stock culture animals were held in batches of 30 - 50 adults at room temperature in ca. 1.8 L of dilution water for one week.
- Feeding during test: no


ACCLIMATION
- Acclimation period: 1 hour

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
Total hardness: 1.0 mmol/L
Test temperature:
The temperature of the incubator was 20.1°C at both test start and end.
pH:
The pH of all treatments ranged between 7.85 and 8.48.
Dissolved oxygen:
The oxygen saturation in the control vessels ranged between 8.0 - 8.6 mg O2/L.
Nominal and measured concentrations:
Nominal test concentrations: 6.25, 12.5, 25, 50 100 mg/L
Corresponding mean measured concentrations: 2.23, 4.55, 8.74, 19.72, 37.90 mg TeO2/L
Details on test conditions:
TEST SYSTEM
- Test vessel:60 mL glass beakers
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 50 mL
- Aeration: no

- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Purified drinking water
- Total organic carbon: 1.154 mg/L DOC
- Particulate matter:
- Metals µg/L: cooper < 1.51; iron < 5.7, manganese < 0.452, zinc 1.70
- Pesticides: no data
- Chlorine total residual: < 0.02 mg/L
- Alkalinity: 2.0 mmol/L
- Ca: 0.8 mmol/L
- Conductivity: 244.5 µS/cm
- Culture medium different from test medium: no
- Intervals of water quality measurement: regularly

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: light/dark cycle of 16/8 hours
- Light intensity: 508 - 528 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study
- Test concentrations: loading WAF of 100 mg/L, 10-fold and 100-fold dilutions.
- Results used to determine the conditions for the definitive study: At the loading of 100 mg/L, 100% mortality was observed after 48 h.
Thus, it was agreed that the definitive test would be performed with a maximum nominal WAF loading of 100 mg/L.
Reference substance (positive control):
no
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
7.24 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
dissolved
Remarks:
Tellurium dioxide
Basis for effect:
mobility
Remarks on result:
other: CL (6.4 - 8.3)
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
4.55 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
dissolved
Remarks:
Tellurium dioxide
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
5.79 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
dissolved
Remarks:
Tellurium
Basis for effect:
mobility
Remarks on result:
other: CL (5.1 - 6.6)
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
3.64 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
dissolved
Remarks:
Tellurium
Basis for effect:
mobility
Validity criteria fulfilled:
yes
Conclusions:
The EC50 for immobilisation of Daphnia magna by tellurium dioxide is 7.24 mg/L.
The EC50 for immobilisation of Daphnia magna by tellurium is 5.79 mg/L .
Executive summary:

The effect of tellurium dioxide on the acute immobilisation of Daphnia magna was investigated. The study was conducted according to the OECD guideline 202. Juveniles were exposed for 48 hours to the test item and the effects compared to a control group of dilution water only. The control and treatmen t groups consisted of four replicates each housing five daphnids. The test item media was prepared from a WAF with the nominal loading of 100 mg tellurium dioxide/l that was diluted to form the remaining concentrations of 50.0, 25.0, 12.5, and 6.25 mg/L. Samples were taken for chemical analysis from fresh and aged media at test start and end, respectively. The chemical analysis of tellurium in both the fresh lest and aged media revealed measured concentrations between 33.57 - 40 .53% of the nominal concentrations. As the concentration of tellurium was stable during the test the mean measured concentrations were calculated and converted to mean tellurium dioxide concentrations. The mean measured concentrations of tellurium were 1.78, 3.64, 6.99,15.77, and 30.3 mg/L. The mean measured concentrations of tellurium dioxide were 2.23, 4 .55, 8.74, 19.72, and 37.9 mg/L.

At 24 hours , an immobilisation effect of 70% in the highest test concentration was observed . After 48 hours, further concentration dependent effects of tellurium dioxide were apparent. Immobilisation was statistically significant in the three highest test concentrations at 80, 100 , and 100%, respectively . The NOEC is 4.55 mg Te02/L (3.64 mg Te/L). The EC50 is 7.24 mg Te02/L (5.79 mg Te/L).

The test fulfilled the validity criteria.

Conclusion

The EC50 for immobilisation of Daphnia magna by tellurium dioxide is 7.24 mg/L.

The EC50 for immobilisation of Daphnia magna by tellurium is 5.79 mg/L .

Description of key information

Study was conducted according to OECD guideline 202, data are reliable without restrictions. 

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
5.79 mg/L

Additional information

The effect of tellurium dioxide on the acute immobilisation of Daphnia magna was investigated. The test item media was prepared from a WAF with the nominal loading of 100 mg tellurium dioxide/l that was diluted to form the remaining concentrations of 50.0, 25.0, 12.5, and 6.25 mg/L. Samples were taken for chemical analysis from fresh and aged media at test start and end, respectively.

At 24 hours , an immobilisation effect of 70% in the highest test concentration was observed . After 48 hours, further concentration dependent effects of tellurium dioxide were apparent. Immobilisation was statistically significant in the three highest test concentrations at 80, 100 , and 100%, respectively . The NOEC is 4.55 mg Te02/L (3.64 mg Te/L). The EC50 is 7.24 mg Te02/L (5.79 mg Te/L).

The test fulfilled the validity criteria.

Conclusion

The EC50 for immobilisation of Daphnia magna by tellurium dioxide is 7.24 mg/L.

The EC50 for immobilisation of Daphnia magna by tellurium is 5.79 mg/L .

Justification for read-across:

This read-across is based on the hypothesis that source and target substances do possess similar ecotoxicological properties.

Since the physico-chemical behaviour of elemental Tellurium and Tellurium dioxide is the same with regard to their metabolic fate (reduction to the Telluride cation) there seems to be good evidence that Tellurium from different moieties will behave very similar with regard to systemic toxicity.

Elemental Tellurium and Tellurium dioxide are relatively poorly water soluble and their systemic uptake by environmental organisms will be directly comparable.

Thus the bioavailability will be an important factor for assessment of ecotoxicity of both substances. The water solubility of both substances is relatively low, with 1.7 and 2.5 mg/L for Tellurium and Tellurium dioxide, respectively.

Data from transformation dissolution tests at different pH values and loadings are available for both substances, indicating Tellurium dioxide to be more soluble at pH 8.

 

Corresponding standard information requirement

Source substance

Tellurium dioxide

Target substance

Tellurium

Water solubility

Transformation dissolution test: OECD guideline 29

 

Target pH 8 at 21.5 °C.

Loadings TeO2: Te concentrations after 7 days:

1 mg/L: 698.9 µg/L

10 mg/L: 6.254 mg/L

100 mg/L: 30.72 mg/L

Transformation dissolution test: OECD guideline 29

 

Target pH 8 at 21.5 °C.

Loadings: Te concentrations after 7 days:

1 mg/L: 20.02 µg/L

10 mg/L: 183.3 µg/L

100 mg/L:1.762 mg/L.

Water solubility:

OECD guideline 105

 

2.5 mg/L at 23 °C

pH 6.4

Water solubility:

OECD guideline 105

 

1.7 mg/L at 20 °C

pH 5.5 – 6.3

 

Underlying the basic assumption that effects caused by the bioavailable metal fraction and the same toxicokinetic behaviour (outlined in detail in the chapter toxicokinetic), ecotoxicity data from the relatively higher soluble Tellurium dioxide were considered appropriate for the ecotoxicity assessment of Tellurium.

In conclusion read-across is considered an appropriate adaptation for ecotoxicological endpoints to meet the standard information requirements according to REACH Regulation.

A detailed justification for read-across describing the toxicokinetic profile, comparing physico-chemical and toxicological properties as well as classification and labelling is outlined in IUCLID chapter 13 in a separate paper.