C16-(branched), C20-(branched) and C24-(branched)-alkanes

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

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 10^4
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.