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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:
2016-05-18 to 2016-05-20
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
2004
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Remarks:
at start and end of experiment
Details on sampling:
- Sampling method: at start and at end of experiment
- Dilution: using mobile phase, 40% acetonitrile, 60% HPLC water
- Sample storage conditions before analysis: 6 +/- 2 °C
Vehicle:
no
Details on test solutions:
- Stock solution: 100 mg/L mixed by manual agitation; freshly prepared with dilution water
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Strain/clone: straus, clone 5
- Source: available in study report
- Age at start of experiment: Less than 24 h old. No first brood progency used.
- Feeding during test: No feeding during the test
- Feeding of culture (before test): 5 times per week, ad libitum with mix of unicellular algae
- Culture medium: Elendt M4
- Application: 20 mL test solution per test vessel, daphnids inserted with small amount of dilution water by a pipette.

ACCLIMATION
- Acclimation period: no acclimatisation as dilution water was equivalent to culture medium
Test type:
static
Water media type:
other: Elendt M4
Limit test:
no
Total exposure duration:
48 h
Hardness:
167 mg CaCO3/L
Test temperature:
20.3°C, constant within +/- 1°C
pH:
at start: approx. pH 8.9, at end of experiment: approx. pH 7.7
Dissolved oxygen:
at start: approx. 8.9 mg O2/L, at end of experiment: approx. 8.6 mg O2/L
Conductivity:
476 µS/cm
Nominal and measured concentrations:
Nominal concentrations: 6.25, 12.5, 25, 50 and 100 mg/L
Measured concentrations (0 h): 6.36, 12.3, 25.0, 49.8 and 102 mg/L
Measured concentrations (48 h): 6.38, 12.4, 25.0, 49.5 and 101 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: glass beaker, 50 mL capacity
- Type: loosely covered with watch glass
- Material, size, headspace, fill volume: 50 mL, filled with 20 mL test solution, 4x7 cm, glass
- No. of organisms per vessel: 5 daphnids
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M4 medium, same as culture medium.

OTHER TEST CONDITIONS
- Adjustment of pH: 8.2 +/- 0.8
- Photoperiod: 16/8 hours light/dark cycle
- Light intensity: Diffuse light, max. 20 µE/m2/s

EFFECT PARAMETERS MEASURED: Immobilisation

RANGE-FINDING STUDY
- Test concentrations: 1, 10, 100 mg/L
- Results used to determine the conditions for the definitive study: Only at 100 mg/L effect on immobilisation observed (mean of 30 % immobilisation)
Reference substance (positive control):
yes
Remarks:
Potassium dichromate tested once per month
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 on result:
other:
Remarks:
Nominal concentrations verified by measurements
Duration:
48 h
Dose descriptor:
EC0
Effect conc.:
50 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other:
Remarks:
Nominal concentrations verified by measurements
Duration:
48 h
Dose descriptor:
EC100
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other:
Remarks:
Nominal concentrations verified by measurements
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
50 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other:
Remarks:
Nominal concentrations verified by measurements
Details on results:
- Observations in control group: no immobilisation, no signs of disease or stress.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Relevant effect levels: EC50 = 2.08 mg/L, which is within the required range of 0.6 to 2.4 mg/L
- Dose-response test: yes
Reported statistics and error estimates:
An ECso-value was calculated only for the reference item by sigmoidal dose-response regression. The respective 95% confidence limits for the ECs was calculated from the standard error and the t-distribution. All calculations were carried out from the best-fit values with the software GraphPad Prism5.

Immobilisation was only observed at 100 mg/L test item. Immobilisation ranged between 20 and 40 % with mean value of 30 %

nominal test concentration (mg/L)

Immobilisation (%)

24 h

48 h

Rep 1 Rep 2 Rep 3 Rep 4  Mean Rep 1 Rep 2 Rep 3 Rep 4  Mean
100 0 0 0 0 0 40 20 40 20 30
50 0 0 0 0 0 0 0 0 0 0
25 0 0 0 0 0 0 0 0 0 0
12.5 0 0 0 0 0 0 0 0 0 0
6.25 0 0 0 0 0 0 0 0 0 0
control 0 0 0 0 0 0 0 0 0 0

Measured exposure concentrations during the Definitive Test:

Sampling date

2016-05-18

Start of the exposure

(0 hours)

2016-05-20

End of the exposure

(48 hours)

Start of analysis

2016-05-18

2016-05-20

Nominal conc. (mg/L)

Measured conc. (mg/L)

%

Measured conc. (mg/L)

%

100

102

102

101

101

50.0

49.8

100

49.5

99

25.0

25.0

100

25.0

100

12.5

12.3

98

12.4

99

6.25

6.36

102

6.38

102

Control

< LOQ

 

< LOQ

 

 

Validity criteria fulfilled:
yes
Remarks:
All validity criteria were verified and fulfilled.
Conclusions:
The 48-hour EC50 for Daphnia magna is above 100 mg/L and the NOEC is 50 mg/L.
Executive summary:

The short-term toxicity to Daphnia magna was determined according to OECD 202 guideline. The study was conducted under static conditions. The daphnids were exposed over a period of 48 hours to 5 concentrations of the test item (0, 6.25, 12.5, 25, 50 and 100 mg/L). The test substance concentrations remained constant during the test period as measured concentrations were in the range of 98 to 102 % of the nominal values. The validity criteria were fulfilled. The EC50 value was determined to be > 100 mg/L and the NOEC is 50 mg/L.

Description of key information

OECD 202 (Daphnia magna): EC50 > 100 mg/L (nominal concentrations)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
100 mg/L

Additional information