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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:
April 9 - June 3, 1999
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-study

Data source

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

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
RCC Ltd., Switzerland

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): DASTIB 845 / SANDUVOR 845
- Substance type: organic
- Physical state: wax-like solid
- Analytical purity: 100% (pure waxy product)
- Lot/batch No.: 040698-27/V
- Expiration date of the lot/batch: December 31, 2001
- Expiration date of radiochemical substance (if radiolabelling):
- Stability under test conditions: maximum 1 hour
- Storage condition of test material: at room temperature at about 20 °C, away from direct sunlight.
- Other: Not miscible with water at concentration above 500 ug/L.

Sampling and analysis

Analytical monitoring:
yes

Test solutions

Vehicle:
no

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

Results and discussion

Effect concentrations
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.

Any other information on results incl. tables

At the microscopic examination of the shape of the algal cells after 72 hours test period no difference was observed between the algae growing in the test medium and the algal cells in the control. Thus, the shape of the algal ceils growing at a loading rate of 100 mg/l was obviously not affected.

In the control the cell density has increased from nominal N = 1 x 10e4 cells/ml at the start of the test (0 hours) to N = 79.8 x 10e4 cells/ml (mean value) after 72 hours by a factor of approximately 80. Thus, the algal growth in the control was sufficiently high under the test conditions.

No remarkable observations were made concerning the appearance of test medium. The test medium was a clear solution throughout the entire test period.

At the start of the test the pH-value of control and test medium were in the range of pH 8.0-8.1. At the end of the test the pH in the test medium and the control had increased to pH 8.8

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The test item DASTIB 845 / SANDUVOR 845 had clearly no inhibitory effect on the growth (biomass and growth rate) of Scenedesmus subspicatus during the exposure period of 72 hours at the loading rate of 100 mg/l. Thus, this loading rate was determined as the 72-hour NOEC (highest concentration tested without toxic effects after a test period of 72 hours). The NOEC might even be higher, but loading rates in excess of 100 mg/l were not tested, according to the guidelines.
Executive summary:

The influence of the test item DASTIB 845 / SANDUVOR 845 on the growth of the green algal species Scenedesmus subspicatus CHODAT was investigated in a 72-hour static test according to the Commission Directive 92/69/EEC, C.3, 1992, and the OECD Guideline No. 201, 1984.

A limit test was performed in accordance with the directive to demonstrate that the test item has no toxic effect on Scenedesmus subspicatus at a loading rate of 100 mg/l.

Due to the low water solubility of the test item a supersaturated suspension with a loading rate of nominal 100 mg/l was prepared by ultrasonic treatment for 15 minutes. No auxiliary solvent or emulsifier was used. This supersaturated suspension was stirred by a magnetic stirrer at 40°C in the dark over 24 hours to dissolve and disperse a maximum amount of the test item in the suspension. Then the suspension was filtered and the undiluted filtrate was used as the only test concentration. Additionally, a control was tested in parallel.

The mean analytically determined test item concentration in the analyzed test medium samples amounted to 0.15 mg/l at the start of the test. In this test medium, incubated under the test conditions during the test period (but without algae), the measured concentrations of DASTIB 845 / SANDUVOR 845 decreased below the limit of determination of the analytical method of 0.04 mg/l after 72 hours. The losses could be due to hydrolysis of the test item during the performance of the test. The total mean measured concentration (calculated as the average over the mean value at the start of the test and the value for the limit of determination) was about 0.1 mg/l. The biological results are related to the loading rate of 100 mg/l.

The test item DASTIB 845 / SANDUVOR 845 had clearly no inhibitory effect on the growth (biomass and growth rate) of Scenedesmus subspicatus during the exposure period of 72 hours at the loading rate of 100 mg/l. Thus, this loading rate was determined as the 72-hour NOEC (highest concentration tested without toxic effects after a test period of 72 hours). The NOEC might even be higher, but loading rates in excess of 100 mg/l were not tested, according to the guidelines.

The 72-hour LOEC (lowest concentration tested with toxic effects), respectively the 72-hour EC50, EC10 and EC90 for the algal biomass and the growth rate were clearly higher than the loading rate of 100 mg/l. These parameters could not be quantified due to the absence of a toxic effect of DASTIB 845 / SANDUVOR 845 up to the loading rate of 100 mg/l, and thus above the water solubility limit.