Methyl stearate

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP - Guideline study, tested with the source substance methyl myristate (CAS 124-10-7). In accordance to the ECHA guidance document “Practical guide 6: How to report read-across and categories (March 2010)”, the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Test guideline 3

Qualifier:

equivalent or similar to guideline

Guideline:

ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum)

Test guideline 4

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

Test material information

Constituent 1

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

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 concnetrations 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

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:
- Material, size, headspace, fill volume: 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
- Other: Singular reserve samples of 3 mL were taken from all test solutions for possible analysis.

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: Continously
- 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 concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.023 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 0.023 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 5

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 6

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

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 NOELR was ≥ 100 mg/L and the ErL50 (72h) > 100 mg/L. The loading rate 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