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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:

From March 20, 1991 to September 26, 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

No analytical dose verification

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

The discrepancy between originally usded identifier of the substance and new test material information is due to change in the main identifier through the Substance identity adaptation service offered by ECHA. The new identifier is covered by old identifier mentioned in Additional test material information section

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Strain: CHODAT (86.81 SAG)
- Source (laboratory, culture collection): Own culture started from a smaple obtained from the 'Institut für Wassr-, Boden- und Lufthygiene, Berlin, Germany'
- Age of inoculum (at test initiation): 3 d

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

22°C

pH:

8.2 - 8.6 at test start; 8.4 - 9.1 at test end

Nominal and measured concentrations:

Nominal: 0, 0.5, 1.0, 2.0, 4.0, 8.0, 16.0 and 32.0 mg/L

Details on test conditions:

TEST SYSTEM
- Initial cells density: 20,000 cells/ml
- Control end cells density: 560,000 cells/ml
- No. of vessels per concentration (replicates): 5 - 8

GROWTH MEDIUM
- Standard medium used: yes


OTHER TEST CONDITIONS
- Sterile conditions: yes
- Adjustment of pH: no
- Light intensity and quality: 8000 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: photometric determination at 685 nm using a reference calibration curve.

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

18.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

23.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

4.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Details on results:

- Exponential growth in the control (for algal test): yes

Table 1: Scenedesmus subspicatus cell density (10E+4 cell/ml) after exposure to the test substance

Concentration (mg/L)	0 h	24 h	48 h	72 h
0	2	3	13	56
0.5	2	4	15	60
1.0	2	5	18	64
2.0	2	4	16	61
4.0	2	3	14	43
8.0	2	3	21	21
16.0	2	3	27	10
32.0	2	4	7	13

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the study, the 24 -72 h ErC50 was 18.6 mg/L (nominal). The nominal 72 h EbC50 was 23.4 mg/L and the NOEC was 2.0 mg/L.

Executive summary:

A study was conducted to determine the toxicity of the test substance to the green algae Scenedesmus subspicatus according to EU Method C.3. Algae were exposed for 72 h at nominal concentrations of 0, 0.5, 1.0, 2.0, 4.0, 8.0, 16.0 and 32.0 mg/L in a static system. No analytical dose verification was conducted. Biomass and growth rate were determined. Under the conditions of the study, the 24 -72 h ErC50 was 18.6 mg/L (nominal). The nominal 72 h EbC50 was 23.4 mg/L and the NOEC was 2.0 mg/L (Scholz, 1991).

Key value for chemical safety assessment

EC50 for freshwater algae:

18.6 mg/L

EC10 or NOEC for freshwater algae:

2 mg/L

Additional information

A study was conducted to determine the toxicity of the read across substance, C16-18 and C18-unsatd., N,N-bis(hydroxyethyl), to the green algae Scenedesmus subspicatus according to EU Method C.3. Algae were exposed for 72 h at nominal concentrations of 0, 0.5, 1.0, 2.0, 4.0, 8.0, 16.0 and 32.0 mg/L in a static system. No analytical dose verification was conducted. Biomass and growth rate were determined. Under the conditions of the study, the 24 -72 h ErC50 was 18.6 mg/L (nominal). The nominal 72 h EbC50 was 23.4 mg/L and the NOEC was 2.0 mg/L (Scholz, 1991).