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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:
1991
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP Guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Principles of method if other than guideline:
As 2-amylanthraquinone is unstable in water under normal light conditions, the study was conducted in red light with wavelengths above 600 nm.
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: nominal test concentrations of 13, 25, 50, 100 and 200 µg/l algal medium. The test solutions of 13 and 25 µg/l were not analysed. A control series of all test concentrations without algae was included in the test, to assess the stability of the test compound under reduced light
conditions.
- Sampling method: samples of the test solutions were taken at day 0 and 4.
- Sample storage conditions before analysis: cool and dark.
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: On the day of test initiation a stock solution was prepared by dissolving 20 mg 2-amylanthraquinone in 10 ml DMSO resulting in a
concentration of 2000 mg/l. This solution was diluted with DMSO resulting in stock solutions of 130, 250, 500 and 1000 mg/l. An amount of 50 µl of these stock solutions was added to 500 ml algal medium.
- Controls: A control with DMSO in algal medium (0.1 ml/l) and a control with algal medium only were included.
- Chemical name of vehicle: DMSO.
- Concentration of vehicle in test medium: 0.1 ml/l.
- Evidence of undissolved material: No.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Selenastrum capricornutum
- Strain: ATCC 22662
- Source (laboratory, culture collection): TNO, The Netherlands.
- Age of inoculum (at test initiation): 4 days.
- Method of cultivation: Each week an inoculum (1 ml) is transferred into fresh algal medium.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Post exposure observation period:
none
Hardness:
No measurement.
Test temperature:
22.5 - 25.5°C.
pH:
controls: 7.1 - 7.6.
test solutions: 7.2 - 7.8.
Dissolved oxygen:
No measurement.
Nominal and measured concentrations:
See Table 1.
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type: Erlenmeyer flasks closed with a stopper.
- Material, size, headspace, fill volume: glass/ 250 ml / headspace / 100 ml.
- Aeration: No.
- Initial cells density: 2.5 x 10E4 cells/ml.
- Control end cells density: 140 x 10E4 cells/ml.
- No. of vessels per concentration: 4 replicates.
- No. of vessels per control: 4 replicates.
- No. of vessels per vehicle control: 4 replicates.

GROWTH MEDIUM
- Standard medium used: yes.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: not applicable, the medium was prepared in distilled water.

OTHER TEST CONDITIONS
- Sterile test conditions: yes.
- Adjustment of pH: no.
- Photoperiod: 24 hours light.
- Light intensity and quality: All wavelengths below 600 nm were filtered by a red sheet, in this way the light intensity was reduced from 8000 to 2000 lux.

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: the absorption was measured at 680 nm at day 1, 2, 3 and 4 using a spectrophotometer.
- Chlorophyll measurement: No.
- Other: after 4 days the condition of the algae was examined under the microscope.
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
95 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
other: growth rate/biomass
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
> 95 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
other: growth rate/biomass
Details on results:
The algae were examined by microscope at test termination. No abnormalities were observed at a nominal concentration of 200 µg/l. The cell concentration is presented in Table 2.

Table 2: Mean number of algae cells per ml

Nominal test concentration (µg/l)

Mean cell concentration (x 104 cells/ml)

Day 0

Day 1

Day 2

Day 3

Day 4

0 (control)

2.5

8.2

23

56

140

0 (DMSO-control)

2.5

8.2

20

56

125

13

2.5

8.2

20

50

125

25

2.5

9.2

23

68

170

50

2.5

8.2

19

45

125

100

2.5

8.2

20

50

140

200

2.5

9.2

20

56

140

Validity criteria fulfilled:
yes
Conclusions:
Short term toxicity of 2-amylanthraquinone to aquatic algae was studied on Selenastrum capricornutum. Algae were exposed to the nominal concentrations of the test substance: 13, 25, 50, 100 and 200 µg/l algal medium for 96 hours. The highest nominal concentration of 200 µg/l was equivalent to a measured concentration 95 µg/l. At the end of the test the algae were examined by microscope at test termination. No abnormalities were observed at a nominal concentration of 200 µg/l. EC50 was calculated to be > 95 µg/l (measured concentration). NOEC was 95 µg/l (measured concentration).

Description of key information

In a OECD 201 test guideline study, Selenastrum copricornutum were exposed, static, to 2-amylanthraquinone for 96 hours. The substance is unstable in water under influence of light, therefore the study was performed under reduced light. Algae were exposed to the nominal concentrations of the test substance: 13, 25, 50, 100 and 200 μg/L. At the end of the test the algae were examined by microscope at test termination. No abnormalities were observed at a nominal concentration of 200 μg/L. The EC50 was calculated to be > 95 μg/L (measured concentration), while the NOEC was 95 μg/L (measured concentration).

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
95 µg/L

Additional information