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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 07.04.1999 to 09.04.1999
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
This study was performed according to EU Method C2 with GLP statement. All validity criteria were fulfilled except the concentration of the test substance which was not maintained at 80% of the initial concentration throughout the duration of the test. The results were not based on measured concentrations and the endpoints had to be recalculated using geometric mean measured concentrations.
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes
Remarks:
1999-05-07
Specific details on test material used for the study:
- Vapour pressure: < 0.1 mbar (20°C)
- Water solubility (under test conditions): 128.248 mg/L
Analytical monitoring:
yes
Details on sampling:
No data
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Solubilisant: Ultra-Turrax.
- Dilution water: M4 medium
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna STAUS
- Strain: no data
- Source: Bayer AG Leverkusen
- Age at study initiation (mean and range, SD): 0 to 24h
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Remarks on exposure duration:
None
Post exposure observation period:
No
Hardness:
14.9°dH.
Test temperature:
20.1 to 20.2 °C (at 48h sampling time).
pH:
7.8 to 8.0 (at 48h sampling time).
Dissolved oxygen:
7.8 to 9.1 (at 48h sampling time).
Salinity:
Not applicable
Nominal and measured concentrations:
Nominal concentrations: 1.0, 2.0, 4.0, 8.0 and 16 mg/L plus one control.
Measured concentrations: see table 6.1.3/1 in "Any other information on results incl. tables".
Details on test conditions:
TEST SYSTEM
- Test vessel: cylindric test container
- Material, size, headspace, fill volume: 20 mL test medium (4.0 cm diameter, 6.5 cm height)
- Aeration: not aerated.
- Type of flow-through (e.g. peristaltic or proportional diluter): not applicable (static system)
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: M4 medium according to Elendt Version of the BGA (1992).

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light / 8 hours dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Number of immobile Daphnia after 24 and 48 hours of exposure.

TEST CONCENTRATIONS
- Test concentrations: control, 1.0, 2.0, 4.0, 8.0 and 16 mg/L.
Reference substance (positive control):
no
Duration:
48 h
Dose descriptor:
other: maximum concentration tested causing no immobilisation
Effect conc.:
2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
other: maximum concentration tested causing 100% immobility
Effect conc.:
8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: geometric mean of the maximum concentration tested causing no immobilisation and the maximum concentration tested causing 100% immobility.
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
5.853 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: EC50 recalculated with ToxRat Professional software v2.10 (probit analysis) using the geometric mean measured concentrations (95% CL: 5.24-6.50 mg/L). See report in "Attached background material".
Details on results:
See raw data in table 6.1.3/2 in "Any other information on results incl. tables".
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
See ToxRat report in "Attached background material".

Table 6.1.3/1: Measured concentrations

Nominal concentrations (mg/L)

Experimental measurements (mg/L)

0h

48h

TOC

Test item

TOC

Test item

Control

1.0

2.0

4.0

8.0

16.0

<2

+)

+)

4

8

13

<2.8

+)

+)

5.6

11.2

18.2

<2

+)

+)

3

4

9

<2.8

+)

+)

4.2

5.6

12.6

geometric mean (24 -48h): control, 1.0, 2.0, 4.85, 7.92 and 15.14 mg/L.

Table 6.1.3/2: Raw data

Nominal concentration (mg/L)

Immobile daphnia

number

%

24h

48h

24h

48h

Control

1.0

2.0

4.0

8.0

16.0

0

0

0

0

6

12

0

0

0

2

20

20

0

0

0

0

30

60

0

0

0

10

100

100

Validity criteria fulfilled:
no
Remarks:
The concentration of the test substance was not maintained at 80% of the initial concentration throughout the duration of the test. However, the results are based on the geometric mean values.
Conclusions:
Under the conditions of the test, the acute EC50 of Daphnia magna was recalculated to be 5.85 mg/L, based on geometric mean measured concentrations.
Executive summary:

In a 48h acute toxicity study, Daphnia magna were exposed to the test substance at nominal concentrations of 0 (blank control), 1.0, 2.0, 4.0, 8.0 and 16.0 mg/L under static conditions.

An analytical monitoring of the concentrations was performed at t=0h and t=48h. The concentrations were not maintained during the exposure period (70 to 105% of the initial concentrations after 48 hours), therefore the result was based on the geometric mean measured concentrations. The 48h-EC50 was determined by geometric mean of EC0 and EC100 values and corresponds to 4.0 mg/L, based on nominal values. However, this value was recalculated with ToxRat Professional software v2.10 using the geometric mean of the measured concentrations at 0h and 48h. The 48h-EC50 corresponds to 5.85 mg/L.

Description of key information

EU Method C.2, GLP, key study, validity 2:

48h-EC50 (Daphnia magna) = 5.85 mg/L based on geometric mean measured concentrations.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
5.85 mg/L

Additional information

One valid key study is available to assess the 48h acute toxicity study of the registered substance to aquatic invertebrates. This study was performed according to EU Method C2 with GLP statement.

Daphnia magna were exposed to the test substance at nominal concentrations of 0 (blank control), 1.0, 2.0, 4.0, 8.0 and 16.0 mg/L under static conditions.

An analytical monitoring of the concentrations was performed at t=0h and t=48h. The concentrations were not maintained during the exposure period (70 to 105% of the initial concentrations after 48 hours), therefore the result should be based on the geometric mean measured concentrations. The 48h-EC50, reported in the study report, was determined by geometric mean of EC0 and EC100 values and corresponds to 4.0 mg/L based on nominal values. However, this value was recalculated with ToxRat Professional software v2.10 using the geometric mean of the measured concentrations at 0h and 48h. The 48h-EC50 corresponds to 5.85 mg/L.

In conclusion, the 48h-EC50 at 5.85 mg/L was chosen for the chemical safety assessment.