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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
Study period:
1991
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1991
Report Date:
1991

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Concentrations: all

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- test solutions prepared according to the OECD GUideline No. 201 with the following final concentrations: 62.3, 250 and 1000 mg/L and the control sample.


Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Scenedesmus subspicatus CHODAT
- Common name: unicellular green algal species.
- Strain: No. 8681 SAG
- Source (laboratory, culture collection):Sammlung von Algenkulturen, Pflanzenphysiologisches Institut der Universität, D-3400 Göttingen, F.R:G.
- Age of inoculum (at test initiation): The algae were grown in the laboratories of RCC
- Method of cultivation: Under standardized conditions according to the OECD Guideline No 201.

ACCLIMATION
- Acclimation period: 72h
- Culturing media and conditions (same as test or not):10000 cells per ml test solution were taken from a sterile pre-culture, at the same conditions as in the test.

Study design

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

Test conditions

Test temperature:
21.0 - 23.4°C
pH:
7.8 - 10.3
Nominal and measured concentrations:
The nominal concentrations tested were 62.3, 125, 250, 500 and 1000 mg test substance/L and a control without any additions.
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 ml Erlenmeyer flasks stopped with permaeble plugs.
- Test solutions were incubated on a laboratory shaker in an air-conditioned room
- Initial cells density: 10.000 cells/mL
- No. of vessels per concentration (replicates): 2



GROWTH MEDIUM
- Standard medium used: yes


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: According to OECD guideline 201


OTHER TEST CONDITIONS
- Adjustment of pH: 7.8 at the begining of the test
- Photoperiod: continuous illumination
- Light intensity and quality: 8000 lux (±20%)


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: measured according to guidelin


TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
Reference substance (positive control):
yes
Remarks:
Potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
72 h
Dose descriptor:
EC0
Effect conc.:
ca. 62.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
27.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
344.8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass

Any other information on results incl. tables

Influence of the test substance on algae growth (cells x 103/ml) during the test duration of 96 hours.

 Concentration  24h rep./mean  48h /mean  72h /mean  96h/mean
 Control 42.6  260.8  1178.7  3013.0
 62.3 mg/l  36.0  198.9  1032.6  2322.4
 125.0 mg/l  33.3  155.6  778.1  1598.0
250.0 mg/l   28.7  145.3  660.3 1501.3 
 500.0 mg/l  26.6  120.1  552.6  1564.7
 1000 mg/l  23.7  91.4  322.6  1041.3

Influence of the test substance on algae growth (Growth Rate μ and Percentage Inhibition of μ)

 Nominal test subst. concentration  μ (0 -72h)     Iμ (0 -72h)  μ (0 -96h)  Iμ (0 -96h)
 Control  1.590  --  1.428  --
 62.3 mg/l  1.547  2.7  1.363  4.6
 125.0 mg/l  1.453  8.6  1.270  11.0
 250.0 mg/l  1.397  12.2  1.253  12.3
 500.0 mg/l  1.337  15.9  1.265  11.4
 1000.0 mg/l  1.160  27.0  1.163  18.6

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The 72-h ErC0 was determined at ca. 62 mg/L. The ErC50 is >1000 mg/L. The substance is not acutely or chronically harmful to freshwater green algae.
Executive summary:

The purpose of this test was to determine the effects of the test substance on the growth of a unicellular green algal species (Scenedesmus subspicatus) over several generations. The influence of test sample 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 62.3, 125, 250, 500 and 1000 mg test substance/1 and a control without any additions. The test substance has obviously a low inhibition effect on the growth of Scenedesmus subspicatus. At the highest concentration tested the algae biomass was inhibited by about 70 %, the growth rate only by about 19 % at the end of the test. In conclusion the EC50 (72h) > 1000 mg/l.