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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:
March 28, 2000 - July 17, 2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
adopted 7 June, 1984
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
Official Journal No. L 383 A, December 29, 1992
Deviations:
no
GLP compliance:
yes (incl. certificate)
Test material information:
Composition 1
Specific details on test material used for the study:
Batch No.: E99988541
Appearance: white crystals





PREPARATION OF THE TEST MATERIAL
The test medium (reconstituted water and test material) was freshly prepared.
Therefore, the calibrated flask with test material and vehicle (reconstituted water) was treated in an ultrasonic device for 1 hour. Subsequently, the preparation was aerated and stirred with a magnetic stirrer for further 23 hours. After 24 hours the formulation was given through a nutsch filter (pore size >10 - <16 µm). The filtrate of the test material preparation was used for the study.

Analytical monitoring:
yes
Details on sampling:
A filtrate of the test material preparation (0.1 g/L nominally) was taken at the start of the experimental part of the study and at the end of the exposure period for analyses. Two samples of about 20 ml filtrate were filled in siliconized glass bottles. They were stored deeply frozen (at least –18°C) until analyses.
Vehicle:
yes
Details on test solutions:
Preparation of the Test Item:
The test medium (reconstituted water and test material) was freshly prepared.
Therefore, the calibrated flask with test material and vehicle (reconstituted water) was treated in an ultrasonic device for 1 hour. Subsequently, the preparation was aerated and stirred with a magnetic stirrer for further 23 hours. After 24 hours the formulation was given through a nutsch filter (pore size >10 - <16 µm). The filtrate of the test material preparation was used for the study.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Unicellular green algae
- Strain: Desmodesmus subspicatus
- Source (laboratory, culture collection): The test system used was Desmodesmus subspicatus, strain No. SAG 86.81 (Sammlung von Algenkulturen, Pflanzenphysiologisches Institut der Universität Göttingen, Germany). This strain was further cultivated in the laboratories of the Institute of Toxicology.

ACCLIMATION
- Acclimation period: 72h
- Culturing media and conditions (same as test or not): same as test
- Any deformed or abnormal cells observed: no
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
-
Test temperature:
23 - 24°C
pH:
7.81 - 7.84

Nominal and measured concentrations:
Nominal concentrations: 100.0 mg/L (measured: < 0.00727 g/L)
Details on test conditions:
TEST SYSTEM
- Test vessel: 300 mL Erlenmeyer flasks
- Type: open
- Material, size, headspace, fill volume: 300 mL Erlenmeyer glas flasks filled with 100 mL cell suspension
- Aeration: no
- Initial cells density: 10 000 cells per ml
- Control end cells density: 1 496 418 cells per ml
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted water according to OECD TG 201

Macro-nutrients:
NaHCO3 50.0 mg/L
CaCl2 x 2 H2O 18.0 mg/L
NH4Cl 15.0 mg/L
MgSO4 x 7 H2O 15.0 mg/L
MgCl2 x 6 H2O 12.0 mg/L
KH2PO4 1.6 mg/L

Trace elements:
Na2EDTA x 2 H2O 100.0 µg/L
FeCl3 x 6 H2O 80.0 µg/L
MnCl2 x 4 H2O 415.0 µg/L
H3BO3 185.0 µg/L
Na2MoO4 x 2 H2O 7.0 µg/L
ZnCl2 3.0 µg/L
CoCl2 x 6 H2O 1.5 µg/L
CuCl2 x 2 H2O 0.01 µg/L


- pH: 7.81

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Light intensity and quality: 6700 to 9000 Lux


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

TEST CONCENTRATIONS
- Nominal test concentration: 100 mg/L
Reference substance (positive control):
no
Remarks:
The accuracy and reliability of the test method is demonstrated periodically as recommended by OECD Guideline No. 201.
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: EC10 >0.00727 g/L
Key result
Duration:
72 h
Dose descriptor:
EC20
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: EC20 >0.00727 g/L
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: EC50 >0.00727 g/L
Details on results:
The 72 hour EC50 for the test material to Desmodesmus subspicatus could not be quantified. An aqueous filtrate of nominal 0.1 g test item/ L, corresponding to an analytical concentration of <0.00727 g/L, revealed no inhibition of algal growth in this test system.

- Observation of abnormalities (for algal test): no
- Unusual cell shape: no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
Results with reference substance (positive control):
The accuracy and reliability of the test method is demonstrated periodically as recommended by OECD Guideline No. 201.

Objective

The objective of this study was to evaluate the influence of the test material on the growth of the green algal species Desmodesmus subspicatus in a static test.

Study Design

For this purpose green algae were exposed to an aqueous filtrate of the test material preparation under defined conditions. The growth was calculated after 24, 48, and 72 hours exposure in the test medium. The algae were exposed to an aqueous filtrate of a nominal test material concentration of 0.1 g/L and the study was performed as limit test.

Results

Samples for analysis were taken from the test material filtrate directly after preparation and at the end of the exposure period. The analytically determined test material concentrations were below the limit of quantification of about 0.00727 g/L.

No effect on growth of the algae was observed at a nominal concentration of 100 mg/L.

For the test item the following EC values were determined:

 Parameter (0 -72h) Growth Rate 

EC10 [mg/L] 

95% confidence interval

>0.00727 g/L (nominal >100 mg/L)

n.d. 

EC20 [mg/L]

95% confidence interval

 >0.00727 g/L (nominal >100 mg/L)

n.d.

EC50 [mg/L]

95% confidence interval

 >0.00727 g/L (nominal >100 mg/L)

n.d.

Conclusion

The 72 hour EC50 for the test material to Desmodesmus subspicatus could not be quantified. An aqueous filtrate of nominal 0.1 g test item/ L, corresponding to an analytical concentration of <0.00727 g/L, revealed no inhibition of algal growth in this test system.

Validity criteria fulfilled:
yes
Conclusions:
The 72 hour EC50 for the test material to Desmodesmus subspicatus could not be quantified. An aqueous filtrate of nominal 0.1 g test item/ L, corresponding to an analytical concentration of <0.00727 g/L, revealed no inhibition of algal growth in this test system.
Executive summary:

This study was performed according to GLP and the methods applied are fully compliant with OECD TG 201. The 72 hour EC50 for the test material to Desmodesmus subspicatus could not be quantified. An aqueous filtrate of nominal 0.1 g test item/ L, corresponding to an analytical concentration of <0.00727 g/L, revealed no inhibition of algal growth in this test system.

Description of key information

The 72 hour EC50 for the test material toDesmodesmus subspicatus could not be quantified. An aqueous filtrate of nominal 0.1 g test item/ L, corresponding to an analytical concentration of <0.00727 g/L, revealed no inhibition of algal growth in this test system. Thus, the EC50 values and the no observed effect concentration (NOEC) referred to the following nominal concentration: 72 h EC50 (growth rate) > 0.1 g/L and NOEC >= 0.1 g/L.

Key value for chemical safety assessment

Additional information