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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
21 - 23 January 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose:
reference to other study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
(2004)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Version / remarks:
(2008)
Deviations:
no
Qualifier:
according to
Guideline:
other: ISO 6341 Water quality - Determination of the Inhibition of the Mobility of Daphnia magna Straus (Cladocera, Crustacea) (1996)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 0 (blank-control) and 100 mg/L
- Sampling: 9.6 ml of test solution were sampled from the approximate centre of the test vessels at t=0 h and t=48 h.
- Sample storage conditions before analysis: Samples were stored in a freezer until analysis. On the day of analysis, the samples were defrosted at room temperature. Nitric acid was added to the test samples to obtain a 4% Nitric acid matrix, after which the samples were analysed.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The preparation of test solutions started with a nominal concentration of 100 mg/L applying a short period of vigorous shaking to accelerate the dissolving of the test substance in the test medium. The lower test concentrations were prepared by subsequent dilutions of the 100 mg/L concentration in test medium.
- Controls: test medium without test substance or other additives
- Evidence of undissolved material: The final test solutions were all clear and colourless.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Source: In-house laboratory culture with a known history
- Validity of batch: Daphnids originated from a healthy stock, 2nd to 5th brood, showing no signs of stress such as mortality >20%, presence of males, ephippia or discoloured animals and there was no delay in the production of the first brood.
- Age at study initiation: <24 h, originated from parental daphnids of more than two weeks old
- Method of breeding
Start of each batch: With newborn daphnids, i.e. less than 3 days old, by placing about 250 of them into 5 litres of medium in an all-glass culture vessel.
Feeding: Daily, a suspension of fresh water algae.
Medium: M7, as prescribed by Dr. Elendt-Schneider (Elendt, B.-P., 1990: Selenium deficiency in Crustacea. An ultrastructural approach to antennal damage in Daphnia magna Straus. Protoplasma 154, 25-33).
- Feeding during test: No
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
180 mg/L expressed as CaCO3
Test temperature:
Start of the test: 20.0-20.2°C
During the test: 19.1-19.8°C
pH:
7.8-8.1
Dissolved oxygen:
9.1-9.3 mg O2/L
Nominal and measured concentrations:
- Nominal: 0 (blank control), 0.10, 1.0, 10 and 100 mg/L

- Measured: See the "Remarks on results including figures and tables" field for details. Samples were quantitatively analysed on Fe in water. Subsequently, test substance concentrations were calculated from these Fe-analyses.
Details on test conditions:
TEST SYSTEM
- Test vessel: all-glass, with a capacity of 100 ml and filled with 80 ml of test solution
- Aeration: No
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4 for the highest test concentration; 2 for each of the lower test concentrations
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: tap water purified by Reverse Osmosis
- Test medium: Adjusted ISO medium
- Intervals of water quality measurement
pH and dissolved oxygen: at the beginning and at the end of the test, for the control and the highest test concentration.
Temperature of medium: continuously in a temperature control vessel, beginning at the start of the test.

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16 h light: 8 h dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobility (including mortality) at 24 and 48 h.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: x10
Reference substance (positive control):
yes
Remarks:
Potassium dichromate (K2Cr2O7)
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks:
(including mortality)
Details on results:
- Measured concentrations: Analysis of the samples taken from the highest test concentration showed that the actual test concentration was in agreement with nominal at the start (100%) and remained stable during the test period (104% of initial at the end of the test).

- Biological results: No (significant) immobilisation was observed at any of the test concentrations and the control during the test period. Only one daphnid was immobilized at the highest test concentration.

- Acceptability of the test:
1. In the control, no daphnids became immobilised.
2. The oxygen concentration at the end of the test was ≥3 mg/L in control and test vessels.
Results with reference substance (positive control):
Potassium dichromate (K2Cr2O7): The 48h-EC50 was 0.38 mg/L with a 95% confidence interval between 0.34 and 0.45 mg/L
Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of the present study Sodium ferrocyanide did not induce acute immobilisation of Daphnia magna at 100 mg/L after 48 hours of exposure. Hence, the 48h-EC50 was >100 mg/L.
Executive summary:

In a 48-h acute toxicity study conducted according to OECD guideline 202, water fleas (Daphnia magna) were exposed to Sodium ferrocyanide under static conditions at the following nominal concentrations: 0 (blank-control), 0.10, 1.0, 10 and 100 mg/L. The test substance did not induce significant acute immobilisation of Daphnia magna at 100 mg/L after 48 hours of exposure. The 48h-EC50 was >100 mg/L based on analytically confirmed nominal exposure concentrations. The study is considered to be reliable without restrictions.

Description of key information

The 48-h EC50 for acute toxicity to aquatic invertebrates was determined to be >100 mg/L (analytically confirmed nominal exposure concentration), based on read across using sodium ferrocyanide as the source substance.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
100 mg/L

Additional information

Key study (read across):

In a 48-h acute toxicity study conducted according to OECD guideline 202, water fleas (Daphnia magna) were exposed to Sodium ferrocyanide under static conditions at the following nominal concentrations: 0 (blank-control), 0.10, 1.0, 10 and 100 mg/L. The test substance did not induce significant acute immobilisation of Daphnia magna at 100 mg/L after 48 hours of exposure. The 48h-EC50 was >100 mg/L based on analytically confirmed nominal exposure concentrations. The study is considered to be reliable without restrictions.

Supporting information (Ewell, et al. 1986):

Daphnia Magna were exposed to several nominal concentrations of potassium ferrocyanide in a light-dark test. The test was repeated 6 months later. The nominal 96h LC50 were estimated to be 32 and 75 mg/L respectively. These values are higher than the literature value of 0.18 mg/L, but it is anticipated that little information of this literature value can be obtained for further comparison. Based on the fact that the substance has a good water solubility (32 g/L at 20 ºC), the nominal values are deemed acceptable without analytical support. The ferrocyanide complex is known to be stable. Only by influence of sunlight, photodegradation can take place with the formation of free cyanides. As this test was performed under light-dark conditions, it is anticipated that the longer exposure time of 96 hrs instead of 48 hrs should lead to lower LC50 values. It is thus anticipated that the 48hr LC50 will be even higher than the values obtained in this test.