Methyl 12-hydroxyoctadecanoate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

26 April 2010 to 29 April 2010

Reliability:

1 (reliable without restriction)

Justification for type of information:

The analogue approach is used for the hazard assessment of toxicological, eco-toxicological and environmental fate endpoints for the registration of 12-hydroxstearate methyl ester (CAS 141-23-1). The hypothesis is that data can be read-across between this ester and its structural analogues, based on structural similarity and which cause the same type of effect(s) in physical and biological systems (Scenario 2 of the Read-Across Assessment Framework (RAAF, ECHA, 2015). The primary fatty acid ester in this read-across for environmental fate and ecotoxicological endpoints is methyl myristate (C14), as this substance is well-studied with high-quality experimental data. Supplemental analogues are used which contribute understanding of the effects of other structural features not contained in the two primary analogues.

The substance and its analogue have not been shown to exhibit toxicity to aquatic organisms (based on short-term studies on all three trophic levels) or be inhibitory to degradative micro-organisms. Both the substance and its analogue have been shown to be readily biodegradable and are not expected to be highly persistent in the environment. And, although both substances exhibit low solubility and a high octanol-water partition coefficient, neither substance is expected to bioaccumulate and pose a concern for food chain exposures, due to the metabolism by carboxylesterases and lipases in vertebrate and invertebrate systems.

There are no GHS classifications for 12-hydroxstearate methyl ester for endpoints which are reliant on read-across. There is a high degree of confidence that hazards for these endpoints are not underestimated, based on a strong weight of evidence from multiple data sources.

Read-across data, all evaluated as reliable according to Klimisch scores of 1 or 2, were used to estimate the toxicity of the registered substance for fulfilling the data requirements of the REACH registration and classifying potential hazards. This read-across approach is adequate for the purposes of risk assessment and classification and labeling.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

2006

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

2009

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2004

Deviations:

no

GLP compliance:

yes

Test organisms (species):

Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Key result

Duration:

72 h

Dose descriptor:

EL50

Remarks:

WSF loading rate

Effect conc.:

> 100 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other:

Remarks:

The EC50 for growth rate reduction (ERC50: 0-72h) and the EC50 for yield inhibition (EYC50: 0-72h) exceeded a WSF prepared at a loading rate of 100 mg/l, corresponding to a TWA concentration of 0.023 mg/l.

Key result

Duration:

72 h

Dose descriptor:

NOELR

Remarks:

WSF loading rate

Effect conc.:

100 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other:

Remarks:

The NOEC for growth rate reduction and yield inhibition equaled a WSF prepared at a loading rate of 100 mg/l, corresponding to a TWA concentration of 0.023 mg/l.

Details on results:

Due to the very low solubility of Fettsauremethylester-C14 in water, concentration levels that might be toxic for algae could not be reached.

Results with reference substance (positive control):

The results were within the normal ranges for the reference item.

Conclusions:

The test substance did not cause inhibition of growth rate or yield in a series of algal cultures (test units) exposed to the test item in a series of test concentrations prepared from an initial Water Soluble Fraction (WSF) with a loading rate of 100 mg/L. Subsequent dilutions of the WSF containing 0.1 %, 1.0%, of 10% of the initial test concentration were prepared. Both the 72-h EC50 and 72-h LOEC were reported as >100 mg/L (corresponding to a measured concentration of 0.023 mg/L). The 72-h NOEC was 100 mg/L based on the WSF loading rate of 100 mg/L (corresponding to a measured concentration of 0.023 mg/L).

Description of key information

The key study was a static growth inhibition test on the effects of the substance on the freshwater unicellular green alga, Pseudokirchneriella subcapitata following OECD Guideline 201. The test substance did not cause inhibition of growth rate inhibition or yield in a series of algal cultures (test units) exposed to the test item in a series of test solutions. The initial test solution was prepared as a Water Soluble Fraction (WSF) with a loading rate of 100 mg/L; additional test solutions were prepared as dilutions containing 0.1 %, 1.0%, and 10%.  Both the 72-h ELR50 and the 72-h LOELR were reported as >100 mg/L (corresponding to a measured concentration of 0.023 mg/L). The 72-h NOELR was 100 mg/L based on the WSF loading rate of 100 mg/L (corresponding to a measured concentration of 0.023 mg/L).  

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

100 mg/L