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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:
2017-05-04 to 2017-06-17
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:
For the determination of the actual test item concentration, duplicate samples were taken at the start and at the end of the test (after 48 hours) from the single test concentration of 100 mg/L and from the control. For the 48-hour stability samples, the contents of the respective replicates
were combined prior to sampling.
Immediately after sampling, all samples were frozen (at -20 ± 5 °C). Based on pre-experiments for investigation of the storage stability (actual study), the test item was found to be stable in the test water under these storage conditions.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
The test medium of the nominal concentration of 100 mg/L was prepared by dissolving 50.04 mg of the test item completely in 500 mL of test water using ultrasonic treatment for 15 minutes and intense stirring for 15 minutes at room temperature. After the dissolving procedure the single test concentration of 100 mg/L was a clear solution. The test medium was prepared just before the introduction of the daphnids.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Waterflea
- Strain: Straus
- Source: Daphnia Collection of the University of Basel/Switzerland in 2015
- Age of test organisms: 6 - 24 h
- Feeding during test: no

ACCLIMATION
- Acclimation period: no
- Acclimation conditions: same as test
- Type and amount of food: Desmodesmus subspicatus or a commercial fish diet (Tetra Min® Hauptfutter, supplied by TETRA-GmbH, 49324 Melle / Germany)
- Feeding frequency: three times a week
- Health during acclimation: no mortality observed
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Test temperature:
20 - 21 °C
pH:
7.8 - 7.9
Dissolved oxygen:
8.5 - 8.8 mg/L
Nominal and measured concentrations:
Nominal concentration: 100 mg/L
Measured concentration (0 h): 105 mg/L
Measured concentration (48 h): 107 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: glass beakers
- Type: closed with glass plates to reduce the loss of water by evaporation and to avoid the entry of dust into the solutions
- Size, fill volume: 100 mL, 50 mL
- Aeration: yes
- No. of organisms per vessel: 20
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: 1 Daphnid - 10 mL

TEST MEDIUM PARAMETERS
- Preparation of dilution water: Reconstituted test water (ISO Test water) according to OECD Guideline No. 202

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16-hour light to 8-hour dark cycle with a 30-minute transition period
- Light intensity: 15 and 17 μmol m-2 s-1

EFFECT PARAMETERS MEASURED:
Immobility was determined by visual inspection after 24 and 48 hours
Observations were also performed for other non-lethal effects (e.g. abnormal behavior or appearance).

RANGE-FINDING STUDY
- Test concentrations: 1.0, 10, 100 mg/L
- Results used to determine the conditions for the definitive study: yes
Reference substance (positive control):
yes
Remarks:
potassium dichromate
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
Duration:
48 h
Dose descriptor:
EC0
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC100
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Behavioural abnormalities: no
- Observations on body length and weight: no abnormalities
- Mortality of control: no
- Other adverse effects control: no
- Abnormal responses: no
- Any observations that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: no
Results with reference substance (positive control):
For evaluation of the quality of the daphnia clone and the experimental conditions, potassium dichromate is tested as a positive control twice a year. The result of the latest positive control test in March 2017 (24-hour EC50: 1.2 mg/L) showed that the sensitivity of the test organisms was within the range given by the guideline (24-hour EC50: 0.60-2.1 mg/L).
Reported statistics and error estimates:
The NOEC, EC0, EC50 and EC100 were directly determined from the raw data.

In the control and in the test item concentration of 100 mg/L, no daphnids showed immobilization or other signs of disease or stress (e.g., discoloration or unusual behavior such as trapping at the surface water) during the test period of 48 hours

Table 1. Analytical Results for Test Samples

Sampling Day/

Sample Age

[d/h]

Nominal Concentration of
Test Item
cnom

[mg/L]

Measured Concentration
 of Test Item
x

[mg/L]

Sample Preparation Factor

F

Determined Concentration of Test Item

c

[mg/L]

% of Nominal Concentration

0/0

Control

n.d.

2

< LOQ

n.a.

(fresh)

100

52.9 and 52.4

2

105

105

3/72

Control

n.d.

2

< LOQ

n.a.

(aged)

100

53.4 and 53.2

2

107

107

n.d.       = no test item detected

n.a.        = not applicable

LOQ:    6.8 mg/L

The tabulated values of the samples represent rounded results obtained by calculation using the exact raw data.

Validity criteria fulfilled:
yes
Conclusions:
The test item had no acute toxic effects on Daphnia magna in a 48-hour static test up to the nominal concentration of 100 mg/L.
Executive summary:

The acute toxicity of the test item on Daphnia magna was determined in a 48-hour static test according to the OECD Guideline for Testing of Chemicals, No. 202 (2004). A limit test was performed in accordance with the test guidelines to demonstrate that the test item has no toxic effect on the test organisms up to and including a nominal concentration of 100 mg/L. Thus, the only nominal concentration tested was 100 mg/L. Additionally, a control group was tested in parallel. The average of the measured concentrations of the test item in the test medium of the single test concentration of 100 mg/L was 105 and 107 % of nominal value at the start and the end of the test, respectively. Thus, the test item was stable in the test medium over the test period of 48 hours. Therefore, the endpoint values were related on the nominal concentration of 100 mg/L. The 48 -hour EC50 and EC100 values were >100 mg/L.

Description of key information

The test item had no acute toxic effects on Daphnia magna in a 48-hour static test up to the nominal concentration of 100 mg/L according to OECD 202 (2004).

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
100 mg/L

Additional information

The acute toxicity of the test item on Daphnia magna was determined in a 48-hour static test according to the OECD Guideline for Testing of Chemicals, No. 202 (2004). A limit test was performed in accordance with the test guidelines to demonstrate that the test item has no toxic effect on the test organisms up to and including a nominal concentration of 100 mg/L. Thus, the only nominal concentration tested was 100 mg/L. Additionally, a control group was tested in parallel. The average of the measured concentrations of the test item in the test medium of the single test concentration of 100 mg/L was 105 and 107 % of nominal value at the start and the end of the test, respectively. Thus, the test item was stable in the test medium over the test period of 48 hours. Therefore, the endpoint values were related on the nominal concentration of 100 mg/L. The 48-hour EC50 and EC100 values were >100 mg/L.