Fatty acids, C12-14 (even numbered), methyl ester

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The water soluble fraction (WSF) was prepared with a nominal loading of the test item of 100 mg/L. 100 mg/L of the test item was weighed on a glass slide and inserted in a brown glass bettle with an appropriate amount of dilution water. The test item dispersion was shaken for 24 hours with 20 rpm at room temperature. After a separation phase of 24 hours, undissolved particles were removed by membrane filtration (membrane filter 0.45 μm, RC, MACHEREY-NAGEL). During filtration, the filter was always covered. The resulting water soluble fraction (WSF) was used in the test.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: SAG 86.81
- Source (laboratory, culture collection): inhouse culture originated from the Collection of algal cultures, Plant physiol. Institute of the University of Göttingen
- Method of cultivation: Fresh stocks are prepared every month on Z-Agar (according to Lüttge et al. 1994). Light intensity amounts to 35-70 μE · m-2 * s-1 for 24 h per day.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

0.24 mmol/L

Test temperature:

23 - 24 °C (room temperature)

pH:

7.90 - 8.33

Nominal and measured concentrations:

Nominal: 100 mg/L loading rate WSF

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flask with cotton wool plugs
- Material: glass; Size: 250 mL; Fill volume: 100 mL
- Initial cells density: 4.864E3 cells/mL
- Control end cells density: 1.31E6 cells/mL
- No. of vessels per concentration: 6
- No. of vessels per control: 6

GROWTH MEDIUM
- Standard medium used: yes (according to OECD 201)

TEST MEDIUM / WATER PARAMETERS
- Intervals of water quality measurement: The pH-value at the beginning of the test was measured in one additional replicate of the limit loading level and the control. At the end of the exposure, it was measured in a pooled sample of the limit loading level and the control. The room temperature was measured continuously. Light intensity was measured prior to the start of the test.

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: 24 h/day light
- Light intensity and quality: 60 120 µE*m2*s

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: fluorimeter
- Chlorophyll measurement: The cell density was measured daily via Chlorophyll-a-fluorescence, excitation at 436 nm, emission at 685 nm. Dilution
water was used as background signal.
- Other: Algae cells were evaluated microscopically at the start and the end of the incubation period. The cells were checked for unusual cell shapes, colour differences, differences in chloroplast morphology, flocculation, adherence of algae to test containers and agglutination of algae cells.

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 1, 10 and 100 mg/L loading rate WAFs
- Results used to determine the conditions for the definitive study: A growth rate stimulation of 5% was found in the 1 mg/L WAF and of 4% in the 100 mg/L WAF. The 10 mg/L WAF showed no difference in growth rate to the control.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

(WSF)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EL10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

(WSF)

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control: yes
- Observation of abnormalities: Microscopic evaluation of the cells at the start and the end of the incubation period revealed no morphological abnormalities. All effect values are based on the nominal loading rate of the test item.
- Any stimulation of growth found in any treatment: The 100 mg/L loading rate treatment showed a growth rate stimulation of 1.6 % compared to the control.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50: 0.59 mg/L (growth rate)

Validity criteria fulfilled:

yes

Conclusions:

The toxicity of the substance to freshwater algae is investigated according to OECD guideline 201 and GLP. Based on the 72h-EL50/EL10 values of > = 100 mg/L (loading rate WSF) the substance is very likely neither acute harmful to algae nor harmful at chronic exposure.

Executive summary:

The toxicity of Fatty acids, C12-14 (even numbered), methyl ester (CAS 308065-15-8) to freshwater algae was investigated according to OECD guideline 201 and GLP using Desmodesmus subspicatus as test organism. A nominal loading rate WSFs of 100 mg/ was tested as limit test. Due to the insolubility of the test item, no analytical evaluation of the limit test item loading and the control was carried out. No significant effects were observed in the control and any treatment after 72 h exposure time. Thus, the 72h-EL50 and EL10 value is determined to be >= 100 mg/L.

Description of key information

EL50/EL10 (72h) >= 100 mg/L (loading rate WSF) for growth rate of Desmodesmus subspicatus (OECD 201)