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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2002-12-23 to 2003-05-09
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: OECD Guideline under GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report Date:
2003

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
(92/69/EWG, C.3)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
Duplicate samples were taken at the start of the test from the freshly prepared test media (without algae) of all test concentrations and from the control. For the determination of the stability of the test item under the test conditions respectively the maintenance of the test item concentrations during the test period, sufficient volumes of the freshly prepared test media of all test concentrations and the control were incubated under the same conditions as in the actual test (but without algae), and were sampled in duplicate at the end of the test (after the 72 hours test period).

The concentrations of the test item were analysed in the duplicate test media.samples from all test concentrations and both sampling times (0 and 72 hours). From the control samples only one of the duplicate samples was analysed from each of both sampling times.

Test solutions

Vehicle:
no
Details on test solutions:
In a first experiment a stock solution of nominal 100 mg/L was prepared by dosing 120 mg test item into 1.2 litre test medium by intense stirring for 24 hours. Thus, the main part of the test item at the start of the test were hydrolysis products. Adequate volumes of this stock solution were diluted with test water to prepare the test media.
In a second experiment a concentration of nominal 150 mg/L was prepared by dissolving 150 mg test item into 1 litre test water by intense stirring for 24 hours.

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Desmodesmus subspicatus (Chodat)
- Strain: No 86.81 SAG
- Source (laboratory, culture collection): University of Göttingen, Germany
- Method of cultivation: according to guidelines

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Post exposure observation period:
-

Test conditions

Hardness:
24 mg CaCO3/L
Test temperature:
23 °C
pH:
8.0 to 8.1 at the beginning
8.4 to 9.1 at the end
This increase of the pH during the. test was obviously caused by the CO2-consumption of the algae due to their rapid growth respectively their high densities (although the test media have been intensively stirred).
Dissolved oxygen:
not given
Salinity:
not given
Nominal and measured concentrations:
1st experiment: 4.6, 10, 21, 46, 100, 150 mg/L nominal
2nd experiment: 150 mg/L nominal
During the test period, the test item was not stable in testwater. At the highest test concentration of nominal 150 mg/L at the start of the test 84 % of nominal were determined. During the test period of 72 hours the concentration decreased to 67 - 68 % of the nominal value. Thus, during the test period of 72 hours the algae were exposed to the hydrolysis products of a mean of 114 mg test item/L at the highest test concentration.
Therefore, the reported results are related to this concentration of 114 mg test item/L.
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flasks of 50 mL volume with at least 50 mL of test medium
- Initial cells density: 10000 algal cells per mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3



GROWTH MEDIUM
- Standard medium used: yes


TEST MEDIUM / WATER PARAMETERS
see above


OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: continious
- Light intensity and quality: 1st experiment 8488 lux (mean); 2nd experiment 7677 lux (mean)


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



Reference substance (positive control):
yes
Remarks:
potassium dichromate at least twice a year

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 114 mg/L
Nominal / measured:
meas. (arithm. mean)
Basis for effect:
biomass
Remarks on result:
other: CL not determined
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 114 mg/L
Nominal / measured:
meas. (arithm. mean)
Basis for effect:
growth rate
Remarks on result:
other: CL not determined
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 114
Nominal / measured:
meas. (arithm. mean)
Basis for effect:
biomass
Remarks on result:
other: CL not determined
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 114
Nominal / measured:
meas. (arithm. mean)
Basis for effect:
growth rate
Remarks on result:
other: CL not determined
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 114 mg/L
Nominal / measured:
meas. (arithm. mean)
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 114 mg/L
Nominal / measured:
meas. (arithm. mean)
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test):
- Unusual cell shape: no
- Colour differences: not reported
- Flocculation: not reported
- Adherence to test vessels: not reported
- Aggregation of algal cells: not reported
- 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 remarkable observations, no precipitation or formation of surface films
Results with reference substance (positive control):
no details in report
Reported statistics and error estimates:
standard procedures

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The 72-hours EC50 value was calculated to be greater than 114 mg/L (NOEC: >=114 mg/L) for the growth rate and biomass, respectively. Thus, it can be concluded that the test substance is not toxic to the green algal species Desmodesmus subspicatus.
Executive summary:

The infuence of the test item on the growth of the freshwater green algal species Desmodesmus subspicatus was assessed in a static dose-response test (OECD Guideline 201). The 72-hours EC50 value was calculated to be greater than 114 mg/L (NOEC: >=114 mg/L) for the growth rate and biomass, respectively. Thus, it can be concluded that the test item is not harmful to the green algal species Desmodesmus subspicatus.