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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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1999
Report Date:
1999

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
The initial cell density of ~ 70000/mL was distinctly above the recommended one of 10000/mL.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid
Specific details on test material used for the study:
Name of test material (as cited in study report) = Shieldex AC 3

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Aqueous extracts of loadings (water-accommodated fraction, WAF)
after 24-h shaking of the suspensions in deionised water at approx. 130 revolutions/min;.
fitration through folded paperfilter;
addition of necessary salts from stock solutions before test
- Differential loading: yes
- Controls: yes, without respective filtrates, but with algae
- Evidence of undissolved material (e.g. precipitate, surface film, etc): Filtrates (WAFs) were clear.

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: green alga
- Strain: Scenedesmus subspicatus CHODAT
- Source (laboratory, culture collection): Institute of Plant Physiology, University Göttingen
- Age of inoculum (at test initiation): 3 d, actively growing cell culture
- Method of culture: preculture 3 days prepared before test from a stock culture

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h

Test conditions

Hardness:
no data
Test temperature:
25 ± 1 °C
pH:
control: 8.29 (initial); 9.97 (final)
tests: 8.35 --> 9.43 (100 mg/L)
8.66 --> 8,44 (200 mg/L)
9.04 --> 8.39 (400 mg/L)
9.16 --> 8.49 (800 mg/L)
9.19 --> 8.73 (1000 mg/L)
Dissolved oxygen:
not applicable
Salinity:
no data
Nominal and measured concentrations:
100, 200, 400, 800, and 1000 mg/L (nominal, WAFs of loadings)
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: no data
- Initial cells density: ~ 72000/mL
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 7


GROWTH MEDIUM
- Standard medium used: yes



TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted water


OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous
- Light intensity and quality: > 120 µE/m2s; ~ 8000 Lux (400 - 700 nm)


EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: spectrophotometer at 578 nm (cell density, extinction)
- Chlorophyll measurement: no


TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study
- Test concentrations: 100; 1000; and 10000 mg/L (loadings)
Reference substance (positive control):
no

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
41 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
33 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
410 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no data
- Any stimulation of growth found in any treatment: no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: no, WAFs were used
Reported statistics and error estimates:
No standard deviations of mean cell concentrations reported. 95%-Confidence limits graphically given in the growth curve plot.
No statistical evaluation available.

Any other information on results incl. tables

Average cell densities and inhibition values over time  (from Report, Sections 7.1 and 7.2)

Concentration [mg/L]

Cell density*) after time of incubation

% inhibition after 72 h

24 h

48 h

72 h

Biomass

Growth rate

Control (0)

2.92 x105

1.14 x106

3.32 x106

0

0

100

2.38 x105

7.72 x105

1.98 x106

37.4

14.5

200

4.37 x105

8.55 x105

2.00 x106

27.4

30.2

400

3.92 x105

6.70 x105

1.48 x106

44.3

34.6

800

2.85 x105

4.97 x105

9.37 x105

63.2

36.9

1000

2.64 x105

4.25 x105

8.38 x105

68.1

39.8

*) Initial cell density = ~ 7.2 x104 cells/mL

Results of pre-testing not provided.

The EC10 value was extrapolated, but procedure not explicitely documented. However, the value is plausible.

The inhibitory effect showed a relatively weak dose-response relationship, with no unequivocal dose response

discernible from 100 to 400 mg/L.

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Remarks:
Cell proliferation valid (~50-fold increase of initial over 72 h); statistical criteria for the validation parameters appear to be met.