[No public or meaningful name is available]

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1 February 2010 - 26 February 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Uncoated nano CaCO3

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Controls: The control group was maintained under identical conditions but not exposed to the test item.
- The test item did not form a solution using conventional methods such as ultrasonication and high shear mixing. Therefore, a saturated solution of the test item was prepared by stirring an excess (50 mg/L) of test item with reconstituted water for 48 hours at approximately 21 °C, then removing the undissolved test material by filtration through a pre-conditioned filter (0.2 µm) to give a saturated solution (100% v/v).

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Source: Laboratory culture
- Age at study initiation (mean and range, SD): Less than 24 hours old
- Method of breeding: Culture conditions ensured that reproduction was by parthenogenesis.
- Feeding during test: No
- Food type: Suspension of algae (Chlorella sp.)
- Frequency: Fed daily during culturing

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

The reconstituted water had an approximate theoretical total hardness of 250 mg/L as CaCO3.

Test temperature:

Control: 19-21 °C
Test vessels: 20-21 °C

pH:

Control: 7.8-7.9
Test vessels: 7.9-8.4

Dissolved oxygen:

Control: 96-100% ASV (air saturation value)
Test vessels: 95-100% ASV

Control: 8.7-9.3 mg O2/L
Test vessels: 8.6-9.1 mg O2/L

Nominal and measured concentrations:

Nominal concentration: 100% v/v saturated solution of test material

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type: closed
- Material, size, headspace, fill volume: 250 mL glass jars
- Aeration: Not during the test. During preparation, the reconstituted water was aerated until the dissolved oxygen concentration was approximately air-saturation value.
- No. of organisms per vessel: 5 daphnids/ vessel
- No. of vessels per concentration (replicates): 4 replicates/concentration
- No. of vessels per control (replicates): 4 replicates


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water
- Conductivity: <5 µS cm-1
- Culture medium different from test medium: No
- Intervals of water quality measurement: Water temperature was recorded daily throughout the test. Dissolved oxygen concentrations and pH were recorded at the start and termination of the test.

OTHER TEST CONDITIONS
- Adjustment of pH: Only if necessary during preparation of the reconstituted water, with NaOH or HCl (to pH 7.8 ± 0.2)
- Photoperiod: 16 hours light and 8 hours darkness with 20 minute dawn and dusk transition periods
- Light intensity: No data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Any immobilisation or adverse reactions to exposure were recorded at 24 and 48 hours after the start of exposure. The criterion of effect used was that Daphnia were considered to be immobilised if they were unable to swim for approximately 15 seconds after gentle agitation.

TEST CONCENTRATIONS
- Justification for using less concentrations than requested by guideline: Based on the results of the range-finding test a limit test was conducted at a concentration of 100% v/v saturated solution to confirm that at the highest attainable test concentration, no immobilisation or adverse reactions to exposure were observed.
- Range finding study
- Test concentrations: 1.0, 10 and 100% v/v saturated solution of test material
- Results used to determine the conditions for the definitive study: No immobilisation was observed at the test concentrations of 1.0 and 10% v/v saturated solution. A single immobilised daphnid was observed at the 100% v/v saturated solution test concentration after 48 h exposure. This was considered to be due to natural causes rather than a toxic effect and was considered not to be significant given that only 10% immobilisation was observed.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 other: % v/v saturated solution

Nominal / measured:

nominal

Conc. based on:

other: saturated solution of test material

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

100 other: % v/v saturated solution

Nominal / measured:

nominal

Conc. based on:

other: saturated solution of test material

Basis for effect:

other: zero immobilisation

Details on results:

There was no immobilisation in 20 daphnids exposed to a test concentration of 100% v/v saturated solution for a period of 48 hours.

The test preparations were observed to be clear, colourless solutions throughout the duration of the test.

The study showed that there were no toxic effects at saturation.

Results with reference substance (positive control):

24 h EC50: 0.84 mg/L (95% confidence limits 0.72-0.97 mg/L)
48 h EC50: 0.65 mg/L (95% confidence limits 0.58-0.72 mg/L)
48 h NOEC: 0.32 mg/L

Validity criteria fulfilled:

yes

Remarks:

All validity criteria were satisfied.

Conclusions:

The acute toxicity of calcium carbonate (nano) to Daphnia magna has been investigated and gave a 48 h EC50 of >100% v/v saturated solution. The NOEC was 100% v/v saturated solution.
The study showed that there were no toxic effects at saturation.

Description of key information

The acute toxicity of calcium carbonate (nano) to Daphnia magna has been investigated and gave a 48 h EC50 of >100% v/v saturated solution. The NOEC was 100% v/v saturated solution. The study showed that there were no toxic effects at saturation.