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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:
From 2017-03-14 to 2017-03-25
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline 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
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 100 (stock solution), 20, 9.1, 4.1, 1.9, 0.85, 0 (Control) mg test item/L
- Sampling method: Duplicate samples from the freshly prepared test media of all test concentrations and the control were taken at the start and the end (after 48h) of the test.
- Sample storage conditions before analysis: Extract all samples directly after sampling and then stored in a fridge (4 ± 4°C) immediately after extraction until analysis.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A stock solution of 100 mg test item/L was prepared by dissolving 57.5 μL test item into 500 mL test water by intense stirring for 10 minutes. Adequate volumes of this stock solution were diluted with test water to prepare the test media of the desired test concentrations.
- Controls: Test water was used without addition of the test item.
- Evidence of undissolved material: no remarkable observations
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Species: Daphnia magna (Straus), clone 5
- Age at Test Start: From 6.25 to 22.25 hours old
- Sex: Female
- Breeding Conditions: fed at least on all working days with green algae freshly grown
- Source: see study report for details

ACCLIMATION
- Acclimation period: 6.25 hours
- Acclimation conditions: same as test
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
2.5 mmol/L as CaCO3c
Test temperature:
Test temperature at test start: 20.0 to 20.4 °C;
Test temperature at test end: 20.2 to 20.3 °C
pH:
pH at test start: 6.1;
pH at test end: 6.2 to 6.3
Dissolved oxygen:
Dissolved oxygen concentration at test start: 8.8 to 9.4 mg/L;
Dissolved oxygen concentration at test end: 8.3 to 8.8 mg/L
Conductivity:
< 5 µS cm-1
Nominal and measured concentrations:
Nominal: 20, 9.1, 4.1, 1.9 and 0.85 mg test item/L
Measured (geometric mean): 17.0, 7.81, 3.17, 1.70 and 0.712 mg test item/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Glass beakers
- Type: closed
- Material, size, headspace, fill volume: Glass beakers of approximately 110 mL volume containing as much test medium as possible
- No. of organisms per vessel: 5 animals
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to OECD 202, Annex 3 (2004)
- Alkalinity: 0.9 mmol/L
- Culture medium different from test medium: no
- Intervals of water quality measurement: 0 hours and 48 hours

OTHER TEST CONDITIONS
- Adjustment of pH: MES buffer was added to the test water to stabilize the pH to 6.0 ± 0.2
- Photoperiod: 16 h light : 8 h dark
- Light intensity: 300 to 510 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Immobility: The mobility of the daphnids was determined by visual observation after 24 and 48 hours.

RANGE-FINDING STUDY
- Test concentrations: 100, 10, 1 and 0.1 mg test item/L
- Results used to determine the conditions for the definitive study: 10 mg test item/L: immobilisation at 48 h: 100%; 1 mg test item/L: immobilisation at 48 h: 0%
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
8.86 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% confidence interval: 4.28 - > 17 mg/L
Duration:
48 h
Dose descriptor:
EC10
Effect conc.:
3.59 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% confidence interval: 1.13-11.4 mg/L
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
3.17 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
LOEC
Effect conc.:
7.81 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Signs of Intoxication after 48 Hours: After 48 hours of exposure no immobilisation of the test animals was observed in the control and up to and including the test item concentration of 3.17 mg test item/L. At the concentration of 7.81 mg test item/L, 13 animals were immobile (65%) and 14 animals were immobile at the highest concentration of 17.0 mg test item/L (70%).
- Analytical Results: At the start of the test 96% of the nominal test concentrations were found (average of all test concentrations). After 48 hours test duration, 75% of the nominal value was determined (average of all test concentrations).
Results with reference substance (positive control):
In the most recent test with the reference item potassium dichromat, the EC50 after 24 hours was determined to be 1.48 (95% CI: 1.26 - 1.71) mg test item/L, indicating that the sensitivity of the daphnids was consistent with the level proposed by the OECD 202 guideline (EC50-24 h between 0.6 and 2.1 mg potassium dichromate/L).
Reported statistics and error estimates:
The 24-hour and 48-hour EC50, EC20 and EC10 and the 95 % confidence limits were calculated by logit analysis.
The NOEC and LOEC after 24 and 48 hours were determined directly from the raw data.
The software used to perform the statistical analysis was ToxRat Professional, Version 3.2.1, ToxRat Solutions GmbH.

Influence of test item on the mobility of Daphnia magna

Geometric mean [mg test item/L]

No. of Daphnia tested

No. of immobilised Daphnia after

% of immobilised Daphnia after

24 h

48 h

24 h

48h

Control

20

0

0

0

0

0.712

20

0

0

0

0

1.70

20

0

0

0

0

3.17

20

0

0

0

0

7.81

20

0

13

0

65

17.0

20

1

14

5

70

Summary of analytical results:

nominal concentration (mg/L) measured concentration (mg/L) % of nominal concentration (%)
0h, fresh 48h, aged 0h, fresh 48h, aged
0.85 0.91 0.55 107 65
1.9 1.90 1.52 100 80
4.1 3.94 2.54 96 62
9.1 8.10 7.55 89 83
20 17.20 16.80 86 84

As the reduction in measured concentration was more than 20 %, geometric means were calculated to report effect levels.

Validity criteria fulfilled:
yes
Conclusions:
The toxic effect of the test item to Daphnia magna was assessed in a static concentration-response test. The 48-hour EC50 value was calculated to be 8.86 mg test item/L (geometric mean of measured concentrations).
Executive summary:

The purpose of this study was to determine the influence of the test item on the mobility of Daphnia magna according to OECD 202 (2004).

For this purpose, young daphnids (< 24 hours old) were exposed in a static test to various concentrations ( 20, 9.1, 4.1, 1.9 and 0.85 mg test item/L and a control) under defined conditions for 48 hours. The recorded effects were the mobility of the daphnids after 24 and 48 hours.

All reported results refer to geometric mean concentrations, since the test item concentrations were not within ± 20% of the nominal or measured initial concentrations during the test.

After 48 hours of exposure no immobilisation of the test animals was observed in the control and up to and including the test item concentration of 3.17 mg test item/L. At the concentration of 7.81 mg test item/L, 13 animals (65%) were immobile and 14 animals (70%) were immobile at the highest concentration of 17.0 mg test item/L.

The 48-hour NOEC was determined to be 3.17 mg test item/L. The 48-hour LOEC was determined to be 7.81 mg test item/L and the 48-hour EC50 value was calculated to be 8.86 mg test item/L.

Description of key information

The 48 -hour EC50 value was calculated to be 8.86 mg test item/L for Daphnia magna.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
8.86 mg/L

Additional information

For this endpoint only one test is available. In this acute immobilization test with Daphnia magna (STRAUS), young daphnids (< 24 hours old) were exposed in a static test to various concentrations under defined conditions (20, 9.1, 4.1, 1.9 and 0.85 mg test item/L and a control) for 48 hours and the mobility of the daphnids after 24 and 48 hours were recorded.

All reported results refer to geometric mean concentrations, since the test item concentrations were not within ± 20% of the nominal or measured initial concentrations during the test.

After 48 hours of exposure no immobilisation of the test animals was observed in the control and up to and including the test item concentration of 3.17 mg test item/L. At the concentration of 7.81 mg test item/L, 13 animals were immobile and 14 animals were immobile at the highest concentration of 17.0 mg test item/L.

The 48-hour NOEC was determined to be 3.17 mg test item/L. The 48-hour EC50 value was calculated to be 8.86 mg test item/L.