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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:
26 Apr-29 Apr 2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP-Guideline study with acceptable restrictions (test concentrations could not be maintained throughout the test)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report date:
2010

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Qualifier:
equivalent or similar to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Qualifier:
equivalent or similar to guideline
Guideline:
ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum)
Qualifier:
equivalent or similar to guideline
Guideline:
other: OECD Guideline 23 (Guidance document on aquatic toxicity testing of difficult substances and mixtures)
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
Methyl myristate
EC Number:
204-680-1
EC Name:
Methyl myristate
Cas Number:
124-10-7
Molecular formula:
C15H30O2
IUPAC Name:
methyl myristate
Test material form:
other: liquid
Details on test material:
- Name of test material (as cited in study report): Fettsäuremethylester-C14
- Physical state: Clear colourless liquid
- Analytical purity: > 99%
- Lot/batch No.: S5327813912
- Expiration date of the lot/batch: 23 February 2011
- Storage condition of test material: At room temperature in the dark

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Sampling method: Singular samples (3 mL) for analysis were taken from the WSF prepared at 100 mg/L and all other test solutions at 0, 24 and 72h
- Sample storage conditions before analysis: Samples were stored in a freezer until analysis, if not already used

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Water Soluble Fraction (WSF): The preparation of test solution started with an aqueous mixture at a loading rate of 100 mg/L. The mixture was magnetically stirred for 25 hours resulting in a clear and colourless solution with a floating layer. The mixture was left to settle for 2 hours and the WSF was collected by siphoning. The lower test concentrations were prepared by subsequent dilutions of the WSF in test medium.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Strain: NIVA CHL 1
- Source: In-house laboratory culture
- Method of cultivation: Algae stock cultures were started by inoculating growth medium (M1 according to NPR 6505, "Nederlandse Praktijk Richtlijn no. 6505") with algal cells from a pure culture on agar. The suspensions were continuously aerated and exposed to light in a climate room at a temperature of 21-24 °C.

ACCLIMATION
- Acclimation period: 3 days before the start of the test, cells from the algal stock culture were inoculated in culture medium at a cell density of 1x10E4 cells/mL.
- Culturing media and conditions: Same conditions and medium (M2) as used in the test

Study design

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

Test conditions

Test temperature:
21.9-23.9 °C
pH:
7.8-8.1
Nominal and measured concentrations:
Nominal: 100 mg/L and dilutions containing 0.1, 1.0 and 10% of the WSF
Measured for 100 mg/L WSF: 0 h 0.42 mg/L, 24 h < 0.014 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 100 mL (all-glass) containing 50 mL of test solution
- Initial cells density: 10000 cells/mL
- No. of vessels per concentration (replicates): 6 of the WSF for 100 mg/L, 3 of each WSF dilution
- No. of vessels per control (replicates): 6

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: M2 according to OECD 201
- Culture medium different from test medium: yes, M1 according to the NPR 6505 ("Nederlandse Praktijk Richtlijn no. 6505")
- Intervals of water quality measurement: pH at the beginning and at the end of the test, temperature continously in a temperature control vessel

OTHER TEST CONDITIONS
- Photoperiod: Continous
- Light intensity and quality: 62 to 69 µE/mE2/s, TLD-lamps of cool-white of 30 Watt

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: At the beginning: microscope and a counting chamber; after 24, 48 and 72 h: spectrophotometric measurement of samples at 720 nm
- Other: At the end microscopic observations were performed on the limit concentration.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
other: filtered test solution
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
other: filtered test solution
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 0.023 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
other: filtered test solution
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.023 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
other: filtered test solution
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
other: filtered test solution
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
other: filtered test solution
Basis for effect:
biomass
Details on results:
- Exponential growth in the control (for algal test): Yes
- Observation of abnormalities (for algal test): No
Results with reference substance (positive control):
- Results with reference substance valid? Yes
- EC50: 1.2 mg/L for growth rate (95% confidence interval 0.77 to 2.0 mg/L)

Any other information on results incl. tables

No reduction of growth rate or inhibition of yield was recorded at any of the tested concentrations (100 mg/L WSF and dilutions of 0.1, 1.0 and 10% of the WSF). Therefore the NOEC was ≥ 100 mg/L and the ErC50 (72h) > 100 mg/L. The nominal concentration of 100 mg/L corresponds to a TWA concentration of 0.023 mg/L.

Table 1: Mean cell densities (x 10000 cells/ML) at 0, 24, 48 and 72 h of exposure to the test material.

% WSF prep. at 100 mg/L

Exposure time (hours)

0

24

48

72

Control

1.0

8.0

30.8

109.9

0.10

1.0

8.1

29.2

105.1

1.0

1.0

7.9

31.5

110.6

10

1.0

8.0

32.3

115.0

100

1.0

7.5

31.9

129.6

 

 

Table 2: Percentage reduction of growth rate and percentage inhibition of yield

% WSF prep. at 100 mg/L

Mean growth rate r (0-72 h)

Yield (0-72 h)

r

Reduction (%)

x10000 cells/mL

Inhibition (%)

Control

0.06524

 

108.91

 

0.10

0.06464

0.9

104.13

4.4

1.0

0.06531

-0,1

109.61

-0.6

10

0.06587

-1.0

113.96

-4.6

100

0.06755

-3.5

128.57

-18.0

 

 

 

Applicant's summary and conclusion