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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:
09 - 12 Aug 2011
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was conducted according to the appropriate OECD test guideline and in compliance with GLP. Effects reported are above the water solubility of the test substance. No analytical verification was conducted. A saturated stock solution was prepared and final loading rates prepared by addition of the appropriate volume of the stock solution using pipettors to test media. However, no data is given on the stirring and equilibration period. Effects might be overestimated and being physical effects.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2015
Report Date:
2015

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution of 10 mg/L was prepared and stirred well to produce a clear, colourless solution. The test concentrations were prepared by addition of the appropriate volume of the stock solution using pipettors to test media. They were then made up to the mark in volumetric flasks to give the required concentrations for the test.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Green alga
- Strain: CCAP 278/4
- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa, Institute of Freshwater Ecology, Windermere Laboratory
- Culture conditions: Temperature: 23 ± 2 °C; Illumination: 6000 - 10000 lux continuous white light
- Shaking: 200 rpm

Study design

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

Test conditions

Test temperature:
21.3 - 27.5 °C
pH:
7.0 - 7.8
Nominal and measured concentrations:
control, 0.08, 0.19, 0.48, 1.2 and 3.0 mg/L (nominal)
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 250 mL conical flasks filled with 100 mL test solution
- Initial cells density: 10^4 cells/mL
- Control end cells density: 94.3 x 10^4 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Test and culture medium were the same: Deionised water with added nutrients was used. Before use the water was sterilised by autoclaving at 120 °C for 30 minutes. Sterile nutrient stock solutions were then added and the pH value adjusted to 8.0 ± 0.2 to obtain the culture medium
- Intervals of water quality measurement: pH and temperature determinations on pooled replicates for each test and control solution were carried out immediately prior to initiating the test and at the end of the 72 hour test period.


OTHER TEST CONDITIONS
- Adjustment of pH: yes
- Photoperiod: continuous
- Light intensity and quality: white light, 6000 to 10000 lux
- Shaking: 200 rpm

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Cekll density was determined after 24, 48 and 72 hour exposure periods on a small volume removed from each replicate flask.
- Determination of cell concentrations: haemocytometer; counts were made in triplicate; cells showing abnormal morphology were included in the count and recorded in the observation section of the report

TEST CONCENTRATIONS
- Range finding study:
Test concentrations: control, 0.1, 1, 10 and 100 mg/L
Results used to determine the conditions for the definitive study: Data from the preliminary study identified the 72 hour EC50 as being approximately 10 mg/L
Reference substance (positive control):
yes
Remarks:
Potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
0.1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Remarks on result:
other: 95% CL: 0.00 - 0.13 mg/L
Duration:
72 h
Dose descriptor:
EL20
Effect conc.:
0.13 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Remarks on result:
other: 95% CL: 0.05 - 0.19 mg/L
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
0.25 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Remarks on result:
other: 95% CL: 0.14 - 0.36 mg/L
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
0.08 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
0.18 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 0.12 - 0.25 mg/L
Duration:
72 h
Dose descriptor:
EL20
Effect conc.:
0.26 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 0.19 - 0.35 mg/L
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
0.48 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 0.37 - 1.91 mg/L
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
0.19 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): all cells appeared normal
Results with reference substance (positive control):
EC50 (growth rate, 72 h) = 0.69 mg/L
NOEC (groth rate, 72 h) = 0.26 mg/L
Reported statistics and error estimates:
NOEC was determined by the Bonferroni T test

Any other information on results incl. tables

Table 1: Results range-finding study

Nominal concentration (mg/L)

Percent inhibition by yield integral

Percent inhibition by growth rate

0 – 72 hours

0 – 72 hours

0.1

48

19

1

47

18

10

81

46

100

100

100

Table 2: Cell density measurements

Nominal concentration (mg/L)

Replicate

Cell density measurements (cells/mL x 10^4)

24 hours

48 hours

72 hours

0

1

2.0

18.7

133.7

2

3.3

12.7

104.7

3

3.3

13.3

91.7

4

3.3

13.3

60.3

5

2.3

12.0

86.7

6

3.3

24.7

88.7

Mean

2.9

15.8

94.3

0.08

1

1.3

16.7

78.3

2

1.7

14.3

105.0

3

1.3

13.0

89.3

Mean

1.4

14.7

90.9

0.19

1

1.7

4.0

60.0

2

3.7

9.3

70.0

3

0.7

3.7

42.7

Mean

2.0

5.7

75.6

0.48

1

0.0

3.0

25.0

2

0.3

3.7

5.7

3

0.0

0.3

5.7

Mean

0.1

2.3

12.1

1.2

1

1.0

1.7

0.0

2

0.7

1.0

0.0

3

1.0

1.7

16.3

Mean

0.9

1.5

5.4

3.0

1

0.7

0.7

2.7

2

0.7

4.0

0.3

3

0.3

0.7

0.7

Mean

0.6

1.8

1.2

Table 3: Percent inhibition at each concentration compared to the control

Nominal concentration (mg/L)

Percent inhibition by yield

Percent inhibition by growth rate

0 – 48 hours

0 – 72 hours

0 – 48 hours

0 – 72 hours

0.08

8

4

2

0

0.19

68

39

40

11

0.48

91

88

85

51

1.2

97

95

87

79

3.0

95

100

92

100

Applicant's summary and conclusion