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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:
other: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
From November 12 to January 24, 1991
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The test was conducted by means of Read Across approach. The reliability of the source study report is 1. Further information was attached at section 13
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to
Guideline:
other: Draft International Standard ISO/TC 147: "Water quality - Algal growth inhibition test, submitted June 25, 1987.
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Sampling method: Samples of 1 ml test solution were sterily taken out of all flasks after 24, 48, 72 and 96 hours of exposure and not replaced.
The algae cell densities in the samples were determined by counting with an electronical particle counter.
Vehicle:
no
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Strain:CHODAT, Strain No. 8681 SAG
- Source : Sammlung von Algenkulturen Pflanzenphysiologisches Institut der Universität
- Method of cultivation:under standardized conditions according to the OECD Guideline No. 201.

ACCLIMATION
- Acclimation period:72 hours
- Culturing media and conditions: same as test
- Any deformed or abnormal cells observed:no data
Test type:
static
Water media type:
freshwater
Total exposure duration:
96 h
Test temperature:
18 - 26 °C
During test duration the temperature was measured daily in an Erlenmeyer flask, filled with water and incubated at the same conditions as the test flasks.
pH:
8.4 - 10.3
The pH-values of the test solutions were measured in samples of all test concentrations and controls at the start and in one replicate at the end of the test.
Nominal and measured concentrations:
Nominal: 0.0, 1.0, 3.2, 10.0, 32.0 and 100 mg test article/l
Details on test conditions:
TEST SYSTEM
- Test vessel:250 ml Erlenmeyer flasks stoppered with permeable plugs
- Type : closed
- Initial cells density: 10.000 cells per ml test solution
- No. replicates:3
- No. of vessels per control: 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
NaHC03 50.0 mg/l
CaCl2 X 2 H20 18.0 mg/l
NH4Cl 15.0 mg/l
MgS04 X 7 H2O 15.0 mg/l
MgCl2 X 6 H2O 12.0 mg/l
KH2P04 1.6 mg/l

Trace Elements :
Na2EDTA X 2 H20 100.0 µg/l
FeCl3 X 6 H20 80.0 µg/l
MnCl2 X 4 H20 415.0 µg/l
H3BO3 185.0 µg/l
Na2Mo04 X 2 H20 7.0 µg/l
ZnCl2 3.0 µg/l
CoCl2 X 6 H20 1.5 µg/l
CuCl2 X 2 H20 0.01 µg/l

OTHER TEST CONDITIONS
- Adjustment of pH:no
Reference substance (positive control):
no
Duration:
96 h
Dose descriptor:
EC0
Effect conc.:
ca. 3.2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
ca. 31.8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
96 h
Dose descriptor:
EC100
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
The test item has obviously an inhibition effect on the growth of Scenedesmus subspicatus first on the concentration of 10 mg test substance/l

In the control the cell density has increased from nominal N = 10,000 cells/ml at the start of the test (0 hours) to N = 2879222 cells/ml after 96 hours by a factor of about 287.

Validity criteria fulfilled:
yes
Conclusions:
Biomass:
- EbC 0 (0 -96h): 3.2 mg/l
- EbC 50 (0 -96h): 13.1 mg/l (95 % conf. limits) 12.4 -13.8 mg/l
- EbC 100 (0 -96h): 100.0 mg/l
Growth rate µ:
- EµC 50 Ic 0 (0 - 96 h): 3.2 mg/l
- EµC 50 Ic 50 (0 - 96 h): 31.8 mg/l (95 % conf. limits) 30.1 - 33.5 mg/
- EµC 50 Ic 100 (0 - 96 h): > 100.0 mg/l
Executive summary:

The influence of test substance on the growth of the green alga Scenedesmus subspicatus Chodat was investigated in a 96-hour static test according to the OECD Guideline No. 201, adopted June 7, 1984 and the Draft ISO/TC 147, submitted June 25, 1987. The test was performed in compliance with the Good Laboratory Practice Regulations. The nominal concentrations tested were 1.0, 3.2, 10.0, 32.0 and 100 mg test article/l and a control without any additions. The test item has obviously an inhibition effect on the growth of Scenedesmus subspicatus. The inhibition was calculated for both parameter, the algae biomass (EbC 50, determined as the area under the growth curve) and the growth rate u (EUC 50):

Biomass:

- EbC 0 (0 -96h): 3.2 mg/l

- EbC 50 (0 -96h): 13.1 mg/L (95 % conf. limits) 12.4 -13.8 mg/l

- EbC 100 (0 -96h): 100.0 mg/l

Growth rate µ:

- EµC 50 Ic 0 (0 - 96 h): 3.2 mg/l

- EµC 50 Ic 50 (0 - 96 h): 31.8 mg/L (95 % conf. limits) 30.1 - 33.5 mg/l

- EµC 50 Ic 100 (0 - 96 h): > 100.0 mg/l

The test article concentrations in the analysed test media amounted to 97.3 - 104.3 % of the nominal values. In the test media, incubated under test conditions (but without algae), the test article was sufficiently stable. Therefore, the reported results are related to the nominal concentration of the test article.

Description of key information

ECr50(96h) = 31.8 mg/l

Key value for chemical safety assessment

EC50 for freshwater algae:
31.8 mg/L
EC10 or NOEC for freshwater algae:
3.2 mg/L

Additional information