Methyl stearate

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

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 202 (Daphnia sp. Acute Immobilisation Test)

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Test guideline 3

Qualifier:

equivalent or similar to guideline

Guideline:

ISO 6341 (Water quality - Determination of the Inhibition of the Mobility of Daphnia magna Straus (Cladocera, Crustacea))

Test guideline 4

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECDGuideline 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:

- Concentrations: Samples were taken from all test concentrations and the control.
- Sampling method: Singular samples (3 mL from the approximate centre of the test vessel) for possible analysis were taken at the start of the test, after 24 hours from the freshly prepared solutions and at the first renewal, and at the end of the test from the 24-hour old solutions. At the end of each refreshment period, the replicates were pooled at each concentration before sampling. Additionally, reserve samples of 3 mL were taken for possible analysis.
- Sample storage conditions before analysis: The samples were stored in the freezer until analysis.

Test solutions

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Preparation of test solutions started with aqueous mixtures at a loading rate of 100 mg/L. The mixtures were magnetically stirred for 23 to 24 hours. The mixtures were left to settle for 2 hours to achieve a good phase separation. The Water Soluble Fraction (WSF) was collected from mid solution by siphoning and additionally filtered through a glass fibre filter. The lower test concentrations were prepared by subsequent dilutions in test medium.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain: Straus
- Source: In-house laboratory culture
- Age at study initiation: < 24 h
- Method of breeding: Start of each batch with newborn daphnids, i.e. less than 3 days old, by placing about 250 of them into 5 litres of medium in an all-glass culture vessel.

Study design

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Test temperature:

At the start: 21°C
During the test: 20.6 - 21.2°C

pH:

Control and all concentrations from start till the end of the test: 7.9 - 8.1

Nominal and measured concentrations:

nominal: 10, 18, 32, 56 and 100% of the WSF prepared at a loading rate of 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 60 mL, all-glass, containing 50 mL test solution
- Renewal rate of test solution (frequency/flow rate): after 24 hours
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Adjusted ISO medium
- Intervals of water quality measurement: PH and dissolved oxygen at the beginning, after 24 h of exposure and at the end of the test for all concentrations and the control; temperature of medium was measured continously in a temperature control vessel, beginning at the start of the test.

OTHER TEST CONDITIONS
- Photoperiod: 16 hours daily

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Immobility including mortality at 24 and 48 hours.

TEST CONCENTRATIONS
- Range finding study: Yes
- Test concentrations: Control and the WSF prepared at a loading rate of 100 mg/L and 0.10, 1.0 and 10% of the WSF.
- Results used to determine the conditions for the definitive study: After 24 hours of exposure 55% immobile daphnids were observed after 48 exposed to the undiluted WSF (100 mg/L nominal). No immobility was observed at any of the dilutions. The expected EC50 was between 10 and 100% of the WSF or between initial measured concentrations of 2.1 and 0.21 mg/L. Measured concentration decrease during the 48-hour test period to a value below the Limit Of Detection (LOD). Based on these results it was decided to continue with testing a range of WSF dilutions between 10 and 100% with a spacing factor of 1.8 and to renew test solutions after 24 hours.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 0.02 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 2

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: WAF loading rate

Results with reference substance (positive control):

- Results with reference substance valid? Yes, 48h-EC50 was between 0.3 and 1.0 mg/L
- EC50/LC50: EC50 (48h) = 0.36 mg/L (95% confidence interval 0.28 - 0.49 mg/L)

Any other information on results incl. tables

Due to the very low solubility of the test substance in water, concentration levels that might be toxic for daphnia could not be reached. No floating layer or trapped daphnia were observed.

Table 1: Immobility of daphnids after 24 and 48 hours

Test substance % of WSF prep. at 100 mg/L	Vessel number	Number Daphnia exposed	Response at 24h		Response at 48 h
			Number	Total %	Number	Total %
Control	A B C D	5 5 5 5	0 0 0 0	0	0 0 0 0	0
10	A B C D	5 5 5 5	0 1 0 0	5	0 1 1 0	10
18	A B C D	5 5 5 5	0 1 0 0	5	0 1 1 0	10
32	A B C D	5 5 5 5	0 0 0 0	0	1 1 0 0	10
56	A B C D	5 5 5 5	0 0 1 0	5	0 0 1 0	5
100	A B C D	5 5 5 5	0 1 0 0	5	0 1 0 0	5

 

 

Table 2: Concentrations of the test medium

(LOD = Limit of detection (0.013 mg/L); * = Obtained by extrapolation of the calibration curve, indicative result)

Time of sampling [hours]	Date of sampling [dd-mm-yy]	Date of analysis [dd-mm-yy]	Percentage of WSF [%]	Analysed concentration [mg/L]
0 (fresh)	13-07-10	16-07-10	0 100	< LOD < LOD
24 (old)	14-07-10	16-07-10	0 100	< LOD < LOD
24 (fresh)	14-07-10	16-07-10	0 100	< LOD 0.0198*
48 (old)	15-07-10	16-07-10	0 100	< LOD < LOD