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

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

other: Weight of evidence

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Weight of Evidence (WoE) assessment based on structural analogues and hydrolysis products

Justification for type of information:

No data on the ecotoxicity are available for Stearic acid, monoester with propane-1,2-diol. The ecotoxicity of this substance is therefore assessed in a weight of evidence analysis based on existing data on similar compounds and hydrolysis products. See the attached report.
The environmental toxicity to invertebrates is assessed based on existing data on:
- the group of fatty acid esters (C10-C18),
- the relevant hydrolysis products including the group of fatty acids and propane-diol.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Test data used in the weight of evidence analysis are results from studies performed according to standard guidelines.

GLP compliance:

no

Test organisms (species):

other: Several organisms

Details on test organisms:

Test organisms for the weight of evidence analysis includes following species:
- Daphnia magna
- Brachionus calyciflorus
- Corbicula fluminea
- Elimia
- Ceriodaphnia dubia
- Dugesia gonocephala
- Chironomus tentans
- Hyallela azteca


Exposure duration from the above organism tests spans from 7-d to 21-d test with among other NOEC and EC10 endpoints. Effect concentration differs between population size, weight gain, reproduction, survival and growth rate. The tested substances were comparable hydrolysis products and alcohol ethoxylates.

The test conditions are not specified.

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.03 mg/L

Nominal / measured:

estimated

Basis for effect:

other: population size, weight gain, reproduction, survival and growth rate

Remarks on result:

other: It is to be noted that all long-term effect concentrations are above the estimated water solubility of 0.0062 mg/L at 25 °C.

Details on results:

The predicted NOEC concentration is based on a correlation between EC10/NOEC test results (Daphnia Magna) and estimated logKow.

Validity criteria fulfilled:

not applicable

Conclusions:

As a conservative approach, the conclusions in this weight-of-evidence approach are based on the results obtained during the studies leading to the highest toxicity, i.e., the lowest EC10/NOEC values respectively, leading to the following value:
- Long-term toxicity to invertebrates: 21-d NOEC (Daphnia magna): 0.03 mg/L
It is to be noted that the long-term effect concentrations are above the estimated water solubility of 0.0062 mg/L.

Executive summary:

Data on the endpoints are not available for “Stearic acid, monoester with propane-1,2-diol”. The environmental toxicity of this UVCB substance is therefore assessed in the present weight of evidence analysis based on existing data on:
- the group of fatty acid esters (C10-C18),

- the relevant hydrolysis products including the group of fatty acids and propane-diol,

- Read-across to similar substances

Hereby, a solid data set is available for deriving a conclusion on the environmental toxicity of the UVCB-substance “Stearic acid, monoester with propane-1,2-diol”.
As the substance is an UVCB-substance, and as expert assessments of substances with similar properties and structure in addition to assessments of the components in the substance and the hydrolysis products are considered the most valid method for the assessment of the environmental toxicity of the UVCB substance, an overall weight of evidence approach is used for the assessment.

 

As a conservative approach, the conclusions in this weight-of-evidence approach are based on the results obtained during the studies leading to the highest toxicity, i.e., the lowest EC10/NOEC values respectively, leading to the following value:

- Long-term toxicity to invertebrates: 21-d NOEC (Daphnia magna): 0.03 mg/L

It is to be noted that the long-term effect concentrations are above the estimated water solubility of 0.0062 mg/L.

Description of key information

Test data on this endpoint are not available for “Stearic acid, monoester with propane-1,2-diol”. The long-term toxicity of this substance is therefore assessed on a weight of evidence analysis of the long-term toxicity of the components in the substance, their major metabolites, the substances used for the synthesis of the UVCB-substance.

The two main constituents of the UVCB substance are both monoester of propane-diol with octadecanoic acid (45-98%) and the monoester of propane-diol with palmitic acid (2-50%). Thus, the UVCB substance belongs to the group of fatty acid esters, and has a very similar structure to the well-known monoglycerides – the only exception being the lack of a OH-group on the C₃-carbon in the propylene glycol. The UVCB substance is assessed to be metabolised in the same manner as the monoglycerides via the formation of the fatty acid and the propylene glycol.

The substance “Stearic acid, monoester with propane-1,2-diol” is an UVCB substance. Data on long-term toxicity to fish and aquatic invertebrates are not available for “Stearic acid, monoester with propane-1,2-diol”. The long-term environmental toxicity of this UVCB substance was therefore assessed based on a weight of evidence analysis, using data from comparable fatty acid esters, fatty acids and glycols (hydrolysis products) as well as alcohol ethoxylates.

A large set of test data on environmental toxicity have been found for the group of fatty acid esters including substances of similar structure and for the hydrolysis products of the UVCB substance to constitute a basis for conclusion on long-term toxicity of the UVCB substance.

As a conservative approach, the conclusions in this weight-of-evidence approach are based on the results obtained during the studies leading to the highest toxicity, i.e., the lowest EC10/NOEC values respectively, leading to the following value:

• Long-term toxicity to invertebrates: 21-d NOEC (Daphnia magna): 0.03 mg/L

It is to be noted that the long-term effect concentrations are above the estimated water solubility of 0.0062 mg/L.

The available information comprises adequate, reliable studies from reference substances with similar structure and intrinsic properties. Weight of Evidence is justified based on common functional group, common precursors/breakdown products. The information from these independent sources is consistent and provides sufficient weight of evidence leading to an endpoint conclusion in accordance with Annex XI, 1.2, of Regulation (EC) No 1907/2006.