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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
17. Jan. 1994 - 20. Jan. 1994
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 21 µg/L analytically measured / constitutes the solubility limit of test substance under the conditions of the test
- Sampling method: Samples drawn from container kept under test conditions but without algal inoculum
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 1 g/L of poorly soluble test substance in demineralized water was stirred for 18 h, undissolved test substance was then removed by filtration. The resulting solution served as stock solution
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Scenedesmus subspicatus
- Strain: 86.81 SAG
- Source (laboratory, culture collection): own culture, orginally received from "Institut für Wasser-, Boden- und Lufthygiene, Berlin Germany"
- Age of inoculum (at test initiation): 3 days
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
none
Test temperature:
24 ± 2 °C
pH:
7,9 - 9,2
Nominal and measured concentrations:
Nominal concentration: 900 mL/L
Analytically measured concentration: 21 µg/L / constitutes the solubility limit of test substance under the test conditions
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: conical flasks
- Aeration: aerated with steril air
- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate):
- Initial cells density: 20000 cells/mL
- Control end cells density: 20000 cells/mL
- No. of organisms per vessel:
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 8
- No. of vessels per vehicle control (replicates): none

GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used:

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Light intensity and quality: 8000 lux, white

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: photometrically at 685 nm, measured values were than transformed to cell number/mL by means of a straight calibration line.

TEST CONCENTRATIONS: limit test
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 21 µg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 21 µg/L constitutes the solubility limit of test substance under test conditions.
Details on results:
NOEC Growth Rate ≥ 21 µg/L
EC50 Growth Rate > 21 µg/L

 

Cell number x 104

Test vessels

0 h

24 h

48 h

72 h

 

Control

21 µg/L

Control

21 µg/L

Control

21 µg/L

Control

21 µg/L

1

2

2

7

7

28

28

119

114

2

2

2

7

7

31

31

121

119

3

2

2

7

7

28

33

121

118

4

2

2

8

8

32

30

118

110

5

2

2

8

8

29

29

125

116

6

2

 

8

 

30

 

127

 

7

2

 

7

 

28

 

118

 

8

2

 

7

 

32

 

120

 

 

 

 

 

 

 

 

 

 

Mean

 -

 -

7

7

30

30

121

115

SD

 -

 -

0.5

0.5

1.6

1.7

3.1

3.2

Validity criteria fulfilled:
yes
Conclusions:
Tetrabutan, dest. induced no growth inhibition up to the solubility limit of the test substance under the given test conditions in a limit test with single cell green algae Scenedesmus subspicatus. The 72 h NOEC Growth rate ≥ 21 µg/L, the EC50 for Growth rate > 21 µg/L.
This concentration constitutes the solubility limit of test substance under the test conditions.
Executive summary:

Tetrabutan, dest. was tested in growth inhibitions test with single cell green algae Scenedesmus subspicatus under static conditions according to the guideline EU Method C.3 (Algal growth inhibtion test). The test was conducted as a limit test. In order to attain the solubility limit of the test substance, which is poorly soluble in water, 1 g Tetrabutan, dest./L was stirred for 18 h and undissolved test substance was then removed by filtration. Since no relevant loss of test substance over the test period was recorded by analytical determination with gas chromatography, the concentration value given is therefore the initially measured value. No effects on growth rate were recorded, thus the NOEC Growth rate ≥ 21 µg/L and the EC50 Grwoth rate > 21 µg/L which constitutes the solubility limit of Tetrabutan, dest. under the conditions of the test.

Description of key information

Tetrabutan, dest. did not induce growth inhibition in freshwater single cell green algae Scenedesmus subspicatus.
NOEC Growth rate (72 h, static) ≥ 21 µg/L (measured)/ which constitutes the solubility limit of the test substance under the conditions of the test (Scenedesmus subspicatus, 92/69/EEC part C3)

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
21 µg/L

Additional information

Tetrabutan, dest. was tested in growth inhibitions test with single cell green algae Scenedesmus subspicatus under static conditions according to the guideline EU Method C.3 (Algal growth inhibtion test). The test was conducted as limit test. In order to attain the solubility limit of the test substance, which is poorly soluble in water, 1 g Tetrabutan, dest./L was stirred for 18 h and undissolved test substance was then removed by filtration. No relevant loss of test substance over the test period was recorded by analytical determination with gas chromatography, the concentration value given is therefore the initially measured value. No effects on growth rate were recorded, thus the NOEC Growth rate≥ 21 µg/L and the EC50 Growth rate > 21 µg/L which constitutes the solubility limit of Tetrabutan, dest. under the conditions of the test.