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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:
read-across based on grouping of substances (category approach)
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:
other: Read across study
Justification for type of information:
Read-across justification appended to Section 13 of the IUCLID file.
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
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  13  56
 0.5  2  4  15  60
 1.0  2  5  18  64
 2.0  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 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).

Description of key information

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).