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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:
2017
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:
EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)
Version / remarks:
1996
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
For determination of the test item concentrations, 4 replicates of 5 mL were taken from the test solution (100 mg/L) and the control at the start and at the end of each water renewal period.
Vehicle:
no
Details on test solutions:
The test solution was prepared by mechanical dispersion. An amount of 0.03 g test item was dissolved in 300 mL test medium (ISO medium) resulting a nominal concentration of 100 mg/L. The test solution was freshly prepared in the test laboratory just before introduction of the test animals (start of each renewal period).
Test organisms (species):
Daphnia magna
Details on test organisms:
Species and strain: Daphnia magna (Straus)
Origin: Laboratory of Hydrobiology (Central Agricultural Office, Directorate of Plant-, and Soil Protection) 2100 Gödöllő, Kotlán S. u. 3. Hungary
Breeding: The Daphnia are bred in the Laboratory of TOXI-COOP ZRT.
Number of animals: Twenty animals in both groups (concentration and untreated control), divided into 4 concurrent batches (5 animals per batch).
Age of animals: Less than 24 h old at the beginning of the test.
Sex: Female
Animal health: Apparently healthy animals were used in this test with a known history
Acclimatization: Test animals were bred under similar (or the same) conditions as that used during the exposure period (holding water, temperature, background colour etc.), therefore additional acclimatisation before the test was not necessary. Brood daphnids were maintained in dilution water at the test temperature for at least 48 hours prior to the start of the test.
Food and Feeding: The Daphnia were fed with concentrated algal suspension of Raphidocelis subcapitata during the holding. Test animals were not fed during the exposure.
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Remarks on exposure duration:
According to Guidelines.
Post exposure observation period:
No.
Hardness:
The reconstituted water (ISO medium) had an approximate theoretical total hardness of 249 mg/L (as CaCO3).
Test temperature:
The test temperature was in the range of 19.9 – 20.3°C measured in the test vessels during the test. The additionally measured ambient temperature within the climate chamber was between 19.3 – 20.6°C.
pH:
The pH of the test solution was not adjusted and not varied by more than 1.5 units in any one test. The pH was in the range of 7.51 – 8.24 during the test.
Dissolved oxygen:
The dissolved oxygen concentration was in the range of 7.27 – 8.33 mg/L during the test.
Salinity:
No.
Conductivity:
Not reported.
Nominal and measured concentrations:
0 - 100 mg/L nominal. The measured concentrations varied between 80 and 101 % of the nominal.
Details on test conditions:
Reconstituted water (ISO medium, according to OECD 202) was used as dilution water and as a control solution in the experiment.

Test type: Semi-static test. Based on the results obtained during analytical method validation (see Section 8, Nemeth 2017) the test item is not stable for the duration of 48 hours in ISO Medium, therefore a semi-static test was performed with daily water renewal periods.

The test vessels were kept during the test in a climate chamber under controlled conditions. The temperature, dissolved oxygen concentration and pH were measured in the test item treated and the control group at the start (before test solutions had been distributed into the test vessels) and in each test vessel at the end of the water renewal periods. Additionally, the ambient temperature was measured continuously using a min/max thermometer in the climate chamber.

Light-Dark Cycle: The light-dark cycle during the test was 16 hours light (artificial illumination) and 8 hours darkness.

In order to select appropriate test concentrations for use in the definitive test, a non-GLP preliminary range-finding test was conducted to determine the approximate toxicity of the test item.
No immobility or sub-lethal effects were observed during the preliminary test, therefore, a single concentration of 100 mg/L (limit concentration) and a concurrent control were included in the main test.

Performance of the Test
Twenty animals, divided into four groups (glass beaker; volume app. 50 mL) of five animals each (at least 4 mL test solution/animal) were exposed to 100 mg/L test item or included as control over a period of 48 hours. The test animals were not fed during the test. Each test vessel contained approximately 40 mL of test solution and was uniquely identified with study code, test group and replicate.
Daphnia were observed for immobility or mortality by visual observation after 24 and 48 hours of exposure. Those animals not able to swim within 15 seconds after gentle agitation of the test beaker were considered to be immobile.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate.
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
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
Key result
Duration:
48 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
Analytical Results
The concentration of the test item was analytically determined at the start and at the end of each water renewal period. In the untreated control group the test item was not detected.
The measured concentration of the test item varied between 80 and 101 mg/L of the nominal.

Biological Results
There was no immobilisation observed in twenty daphnids exposed to each test item treated and control group. Further no abnormal behaviour or appearance of test animals was noted.
Results with reference substance (positive control):
The date of the last study (Study Code: 392-202-2533) with reference item Potassium dichromate was: 7 - 8 March 2017.
The 24-h EC50: 1.57 mg/L, (95 % confidence limits: 1.19 – 1.68 mg/L).

Validity of the Study

• Immobilisation or any sub-lethal effects were not detected either in the control or in the test item treated group.

• The dissolved oxygen concentration was greater 3 mg/L in each test vessel at the end of the test.

All validity criteria were within acceptable limits and therefore the study considered valid.

Validity criteria fulfilled:
yes
Conclusions:
The test item had no toxic effect at 100 mg/L concentration (i.e. limit test concentration) on Daphnia magna; the EC10, EC20, EC50 results and the LOEC are higher than 100 mg/L.
Executive summary:

A semi-static 48h-test with Daphnia magna was performed according to OECD guideline 202. The test item had no toxic effect at 100 mg/L concentration (i.e. limit test concentration) on Daphnia magna; the EC10, EC20, EC50 results and the LOEC are higher than 100 mg/L.

Description of key information

A semi-static 48h-test with Daphnia magna was performed. The test item had no toxic effect at 100 mg/L concentration (i.e. limit test concentration) on Daphnia magna; the EC10, EC20, EC50 results and the LOEC are higher than 100 mg/L.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
100 mg/L

Additional information

The EC50 is not 100 mg/L, as one is forced to enter in the field above, but the EC50 is >100 mg/L.