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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From July 28th to September 7th, 2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report Date:
2000

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
1984
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent

Sampling and analysis

Analytical monitoring:
yes

Test solutions

Vehicle:
no
Details on test solutions:
Due to the very low water solubility of test item, a supersaturated stock dispersion of test item with a loading rate of nominal 100 mg/l was continuously stirred at room temperature in the dark over 96 h. Then the dispersion was filtered. The undiluted filtrate with the maximum concentration of dissolved test item was used as test medium. Additionally, a control was tested in parallel.

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h

Test conditions

Hardness:
24 mg CaCO3/l
Test temperature:
22 °C
pH:
7.9-8.2 (undiluted filtrate)
7.9-8.5 (control)
Nominal and measured concentrations:
Nominal 100 mg/l as loading rate
Details on test conditions:
cell density 1 × 10^4 cells/ml at t = 0 h
cell density 104 × 10^4 cells/ml at t = 72 h
Reference substance (positive control):
no

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Details on results:
Test item has clearly no inhibitory effect on the growth of algae during the exposure period of 72 h in the undiluted filtrate with a concentration of 41 µg/l and a loading rate of 100 mg/l. This test concentration was thus determined as the 72-h NOEC. NOEC might even be higher but concentrations in excess of 41 µg/l could not be tested due to the low water solubility of test item.
The 72-h LOEC and EC50 for mean algal biomass and growth rate were clearly higher than 41 µg/l and higher than a loading rate of 100 mg/l. These values could not be quantified, since test tiem had no toxic effect on algae up to the highest test item concentration which could be dissolved in test water.

The biological results are related to the loading rates of 100 mg/l. No effects were observed at the solubility limit of 41 µg/l (mean measured test tem concentration calculated as the average over all measurements of the undiluted filtrate). 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Test item had no toxic effect on the algae up to its solubility limit in test water.