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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
4 February - 6 March 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
2004
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
Singular samples for possible analysis were taken from all test concentrations and the control according to the schedule below.
Frequency: at t=0 h and t=48 h
Volume: 3 ml
Storage: Samples were stored in a freezer until analysis.
At the end of the exposure period, the replicates were pooled at each concentration before sampling.

Vehicle:
no
Details on test solutions:
The standard test procedures required generation of test solutions, which contained completely dissolved test substance concentrations or stable and homogeneous mixtures or dispersions. The testing of concentrations that would disturb the test system was prevented as much as possible (e.g. film of the test substance on the water surface). No correction was made for the purity/composition of the test substance.
The test substance was a white crystalline powder with a purity of 100.0% and completely soluble in test medium at the highest concentration prepared for the final test.
Preparation of test solutions started with the highest concentration of 100 mg/l. Two days of magnetic stirring were applied to ensure reaching maximum dissolution in test medium. The resulting dispersions obtained in the combined limit/range-finding and final test were filtered through a 0.45 μm membrane filter (Whatman, RC55) to remove a limited fraction of undissolved material. The resulting clear and colourless filtrate was used to prepare the lower test concentrations by subsequent dilution in test medium. The final test solutions were all clear and colourless.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna (Straus, 1820) at least third generation, obtained by acyclical parthenogenesis under specified breeding conditions.
- Source: In-house laboratory culture with a known history; 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.
- Feeding during culture: Daily, a suspension of fresh water algae.
- Feeding during study: no.
- Age at study initiation: young daphnids with an age of < 24 hours

METHOD FOR DAPHNIA 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.
Maximum age of the cultures: 4 weeks
Renewal of the cultures: After 7 days of cultivation half of the medium twice a week.
Temperature of medium: 18-22°C
Type of medium: M7, as prescribed by Dr. Elendt-Schneider.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
no
Hardness:
180 mg/L (as CaCO3)
Test temperature:
The temperature of the test medium was between 19.7 and 20.6°C at the start of the test. The temperature continuously measured in a temperature control vessel varied between 18.9 and 20.5°C during the test, and complied with the requirements for this test (18-22°C, constant within 2°C).
pH:
The pH values complied with the requirements for this test (values between 6.0-8.5, not varying by more than 1.5 unit), because they were in the range of 7.9-8.0 at the start and 8.0-8.1 at the end of the test.
Dissolved oxygen:
The oxygen concentrations complied with the requirements for this test (values ≥3 mg/l at the end of the test), because they were in the range of 9.2-9.4 mg/l at the end of the test.
Nominal and measured concentrations:
The test substance was completely soluble in test medium at the highest concentration prepared for the final test. The highest concentration of 100 mg/l prepared in the final test was completely dissolved and subsequently used for testing and preparation of the lower concentrations by dilution.

Nominal concentrations of 4.6, 10, 22, 46 and 100 mg/l were used.
Analysis of the samples taken during the final test showed that measured concentrations were stable and in agreement with nominal (93-99% relative to nominal): 4.29, 9.34, 21.1, 44.2, 98.9.
Details on test conditions:
TEST SYSTEM
- Test vessel: Glass beakers of approximately 100 mL volume
- Aeration: no
- Renewal rate of test solution: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Type: M7, as prescribed by Dr. Elendt-Schneider
- Culture medium different from test medium: no
- Intervals of water quality measurement: pH-values and dissolved oxygen concentrations were determined in all test media of each treatment group at the beginning and at the end of the test; temperature of medium was measured continuously, beginning at the start of the test.

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

EFFECT PARAMETERS MEASURED: mobility (at 24 and 48 hours)

RANGE-FINDING STUDY
- Test concentrations: 0, 1.0, 10 and 100 mg/l
- Results used to determine the conditions for the definitive study: yes
Reference substance (positive control):
yes
Remarks:
potassium dichromate (January 2017)
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
52 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: The 95% confidence interval between 45 and 64 mg/l.
Remarks:
Analysis of the samples taken during the final test showed that measured concentrations were stable and in agreement with nominal (93-99% relative to nominal). Hence, toxicity parameters could be based on analytically confirmed nominal concentrations.
Details on results:
- Behavioural observations: a number of daphnia were observed trapped at the surface of the test solutions: 1 at 10 mg/l and 1 at 22 mg/l after 48 hours, and 4 at 100 mg/l after 24 hours.
- Mortality of control: no
- Other adverse effects control: no
- Any observations (e.g. precipitation) 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):
- Results with reference substance: valid
- Dose-response test: yes; tested concentrations: 0.10, 0.18, 0.32, 0.56, 1.0 and 1.8 mg/l
- The main test: 24h-EC50 = 0.78 mg/L (95% C.I.: 0.69-0.93 mg/l); 48h-EC50 = 0.53 (95% C.I.: 0.49-0.62 mg/l)
Reported statistics and error estimates:
The EC50-value was calculated at 24 and 48 hours of exposure from the probits of the percentages of affected daphnids and the logarithms of the corresponding test substance concentrations using the maximum likelihood estimation method (Finney, D.J., 1971: Probit analysis, Cambridge University Press, Cambridge, U.K., 3rd edition).

Cumulative Immobilization Data and Observations in the Definitive Test

Geometric mean measured 

Concentration

[mg/L]

No. of Daphnia tested

No. of immobilized Daphnia

after

% of immobilized Daphnia after

24 h

48 h

24 h

48 h

 

 

Control

20

0

0

0

0

4.6

20

0

0

0

0

10

20

1

1

5

5

22

20

0

0

0

0

46

20

1

7

5

35

100

20

14

19

70

95

Analytical results:

Time of sampling [hours]

 

Concentration Nominal [mg/l]

 

Concentration Analysed [mg/l]

 

Relative to nominal [%]

 

0

0

n.d.

n.a.

 

4.6

4.33

94

 

10

9.68

97

 

22

20.7

94

 

46

44.0

96

 

100

98.2

98

48

0

n.d.

n.a.

 

4.6

4.29

93

 

10

9.34

93

 

22

21.1

96

 

46

44.2

96

 

100

98.9

99

Validity criteria fulfilled:
yes
Remarks:
1) In the control, no daphnids became immobilised or showed other signs of disease or stress. 2) The oxygen concentration at the end of the test was ≥3 mg/L in control and test vessels.
Conclusions:
The 48h-EC50 value to Daphnia magna was 52.0 mg/L based on the nominal concentrations. Analysis of the samples taken during the final test showed that measured concentrations were stable and in agreement with nominal (93-99% relative to nominal). Hence, toxicity parameters could be based on analytically confirmed nominal concentrations.
Executive summary:

A study was performed to assess the acute toxicity of the substance to Daphnia magna. The study was conducted in accordance with OECD Guideline for Testing of Chemicals No. 202 and GLP under static conditions. Based on the results of a range-finding test, the following nominal concentrations were tested in the definitive test: untreated control, 4.6, 10, 22, 46 and 100 mg/l. For each concentration and a control group, twenty Daphnia magna (less than 24 hours old) were exposed for 48 hours. The incidence of immobilisation was recorded for each test and control group at 24 hours and at 48 hours. Samples taken from all concentrations at the start and the end of 48 -hour exposure were analysed. The measured concentrations were in agreement with nominal (93-99% relative to nominal). Hence, toxicity parameters could be based on analytically confirmed nominal concentrations. The 48h-EC50 value to Daphnia magna was 52.0 mg/L based on these nominal concentrations.

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: read across was applied
Justification for type of information:
Read across from Piperonal was applied. The respective read-across document can be found in the endpoint summary. The read-across document is also attached in the endpoint summary.
Reason / purpose:
read-across source
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
52 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: The 95% confidence interval between 45 and 64 mg/l.
Remarks:
Analysis of the samples taken during the final test showed that measured concentrations were stable and in agreement with nominal (93-99% relative to nominal). Hence, toxicity parameters could be based on analytically confirmed nominal concentrations.
Validity criteria fulfilled:
yes
Remarks:
Read across documentation according to Annex XI is available
Conclusions:
The EC50 for Daphnia is 52 mg/l.

Description of key information

Read across from Piperonal was applied. The full read across justification can be found in the Endpoint Summary. Below is the summary of the study performed with Piperonal.

A study was performed to assess the acute toxicity of the substance to Daphnia magna. The study was conducted in accordance with OECD Guideline for Testing of Chemicals No. 202 and GLP under static conditions. Based on the results of a range-finding test, the following nominal concentrations were tested in the definitive test: untreated control, 4.6, 10, 22, 46 and 100 mg/l. For each concentration and a control group, twenty Daphnia magna (less than 24 hours old) were exposed for 48 hours. The incidence of immobilisation was recorded for each test and control group at 24 hours and at 48 hours. Samples taken from all concentrations at the start and the end of 48 -hour exposure were analysed. The measured concentrations werein agreement with nominal (93-99% relative to nominal). Hence, toxicity parameters could be based on analytically confirmed nominal concentrations.

The 48h-EC50 value to Daphnia magna was 52.0 mg/L based on these nominal concentrations.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
52 mg/L

Additional information