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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:
Feb. 16, 1993-Feb. 19. 1993
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study.
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Test substance was added to demineralized water at 1g/L and stirred for 18 hrs.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Source (laboratory, culture collection): Aus dem Institut fur Wasser-, Boden-, und Lufthygiene
Test type:
static
Total exposure duration:
72 h
Test temperature:
24 +/- 2°C
pH:
7.3 to 7.7 at test initiation and from 8.9 to 9.3 at 72-hours
Nominal and measured concentrations:
Nominal test concentrations were 0.23, 0.39, 0.69, 1.16 and 2.08 mg/L, plus a control.
Details on test conditions:
TEST SYSTEM
- Material, size, headspace, fill volume: Erlenmeyer flasks
- Initial cells density: 20,000 cells/ml
- No. of vessels per concentration (replicates): 8
- No. of vessels per control (replicates): 8


GROWTH MEDIUM
- Standard medium used: yes



OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Light intensity and quality: 8000 lux


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: spectrophotometer


Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 2.08 mg/L
Nominal / measured:
nominal
Duration:
72 h
Dose descriptor:
other: EbC50
Effect conc.:
> 2.08 mg/L
Nominal / measured:
nominal
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
other: ErC50
Effect conc.:
> 2.08 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate

Cell Growth ( x 104cells/ml)

Concentration

0 hrs

24 hrs

48 hrs

72 hrs

Control

2

6

24

69

0.23 mg/l

2

6

24

68

0.39 mg/l

2

6

24

79

0.69 mg/l

2

6

26

78

1.16 mg/l

2

6

26

80

2.08 mg/l

2

6

26

77

Validity criteria fulfilled:
yes
Conclusions:
The 72-hr ErC50 and EbC50 was > 2.08 mg/L test substance. This represents the solubility limit of the test substance.
Executive summary:

This study examined the potential of the test substance to cause toxicity to aquatic algae. Algae of the species Scenedesmus subspicatus were exposed to concentrations of 0, 0.23, 0.39, 0.69, 1.16 and 2.08 mg/L of test substance. The 2.08 mg/L concentration represents the solubility limit of the test substance. Algae were exposed for 72 hrs. Observations for biomass and growth rate were made at 24, 48, and 72 hrs after start of exposure. No reduction in either of these parameters as compared to controls was seen. The 72 -hr ErC50 and EbC50 was > 2.08 mg/L of test substance. The NOEC was >= 2.08 mg/L of test substance. The 72 -hr ErC50 and EbC50 are therefore greater than the solubility limit of the test substance.

Description of key information

The key study examined the potential of HAB to cause toxicity to aquatic algae. Algae of the species Scenedesmus subspicatus were exposed to concentrations of 0, 0.23, 0.39, 0.69, 1.16 and 2.08 mg/L of test substance. The 2.08 mg/L concentration represents the solubility limit of the test substance. Algae were exposed for 72 hrs. Observations for biomass and growth rate were made at 24, 48, and 72 hrs after start of exposure. No reduction in either of these parameters as compared to controls was seen. The 72 -hr ErC50 and EbC50 was > 2.08 mg/L of test substance. The NOEC was >= 2.08 mg/L of test substance. The 72-hr ErC50 and EbC50 are therefore greater than the solubility limit of the test substance.

Key value for chemical safety assessment

Additional information