Isooctadecanoic acid, monoester with propane-1,2-diol

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Remarks:

toxicity control of study on ready biodegrdation according to OECD 301B

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data based on the inhibition control of a ready biodegradability study. This approach is in accordance with the Guidance on information requirements and chemical safety assessment (Chapter R.7b: Endpoint specific guidance, ECHA 2017).

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: OECD 301 B

Version / remarks:

1992

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health of the Government of the United Kingdom

Test organisms (species):

other: freshwater

Details on inoculum:

- Source of inoculum/activated sludge: Surface water was collected from Malmesbury Pond, Sandymoor, Runcorn on 12th February 2018.
- Laboratory culture: no
- Preparation of inoculum for exposure: The collected surface water was filtered to remove coarse particles and aerated at 22 ± 2ºC prior to use. The surface water was then added to test media so as to achieve a final concentration of 100 mL per L of test media. The test suspensions were then aerated until the study pre-conditioning period was ready to commence on 14th of February.
- Initial cell/biomass concentration: not reported

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

14 d

Test temperature:

22 ± 2 °C

Nominal and measured concentrations:

25.8 mg test item/L

Details on test conditions:

TEST CONDITIONS
- Composition of medium: according to guideline
- Additional substrate: no
- Solubilising agent (type and concentration if used): no
- Aeration: yes, carbon free air (rate: 30 - 100 mL / min)
- Continuous darkness: yes
- Other: 3 L volumes of test media were stirred constantly in round, flat bottomed flasks.

TEST SYSTEM
- Culturing apparatus: conical flasks (with 3 L test media)
- Number of culture flasks/concentration: 1 (102.9 mg (20 mg C/L) of the reference material, sodium benzoate and test material at 25.8 mg/L).
- Method used to create aerobic conditions: aeration with carbon free air
- Other: test substance was added directly to the test vessels to achieve final test concentrations

SAMPLING
- Sampling frequency: Measurements were performed after the appearance of a precipitate of barium carbonate. This was on days 2, 4, 7, 10, 14, 18, 23, 28 and 29.
- Sampling method: The contents of each dreschel bottle were titrated against standardised hydrochloric acid to a pH 7 endpoint. Titres were taken for the barium hydroxide at the start and end of each time period.

Reference substance (positive control):

yes

Remarks:

sodium benzoate

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 25.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: inhibition of respiration

Remarks on result:

other: Result of toxicity control from ready biodegradability test

Details on results:

A degradation of 79.8% after 14 days was obtained for the toxicity control.

Results with reference substance (positive control):

A degradation figure of 70.1% after 14 days was obtained for the reference material.

Since more than 25% degradation occurred in the toxicity control, the substance is with high probability not toxic to aquatic microorganisms. The test item concentration in the toxicity control of 25.8 mg/L can be used as NOEC value for the toxicity to aquatic microorganisms.

Validity criteria fulfilled:

not applicable

Description of key information

The hazard assessment is based on the data currently available. New studies with the registered substance and/or other member substances of the glycol esters category will be conducted in the future. The finalised studies will be included in the technical dossier as soon as they become available and the hazard assessment will be re-evaluated accordingly.

For further details, please refer to the category concept document attached to the category object (linked under IUCLID section 0.2) showing an overview of the strategy for all substances within the glycol esters category.

Additional information

The hazard assessment is based on the data currently available. New studies with the registered substance and/or other member substances of the glycol esters category will be conducted in the future. The finalised studies will be included in the technical dossier as soon as they become available and the hazard assessment will be re-evaluated accordingly.

For further details, please refer to the category concept document attached to the category object (linked under IUCLID section 0.2) showing an overview of the strategy for all substances within the glycol esters category.

Since no studies on the toxicity to aquatic microorganisms are available the results of a ready biodegradability study are used to evaluate the toxicity of the substance to aquatic microorganisms. If a compound degrades rapidly in a ready biodegradability test, or does not inhibit at a certain concentration the degradation process of the microorganisms in the positive control, the applied concentration can be used as a NOEC value. This approach is in accordance with the Guidance on information requirements and chemical safety assessment (Chapter R.7b: Endpoint specific guidance, ECHA, 2017).

The biodegradation study according to OECD guideline 301B (2018) showed that freshwater microorganisms biodegrade rapidly isooctadecanoic acid, monoester with propane-1,2-diol (CAS 68171-38-0) at a test item concentration of 12.9 mg/L. Furthermore within the same study, the toxicity control containing 102.9 mg of the reference material, sodium benzoate and 25.8 mg/L test material clearly showed that no toxicity is expected by the substance to microorganisms since a degradation of 79.8% was obtained after 14 d. Therefore, no further study was necessary and no hazard towards aquatic microorganisms is expected. The NOEC (14 d) was therefore ≥ 25.8 mg/L.