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

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

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:

Test data on this endpoint are not available for “Stearic acid, monoester with propane-1,2-diol”. The short-term toxicity of this substance is therefore assessed on a weight of evidence analysis of the short-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.
“Stearic acid, monoester with propane-1,2-diol” is an UVCB substance. Data on short-term toxicity to fish, aquatic invertebrate and aquatic algae and cyanobacteria as well as data on inhibition of activated sludge respiration are not available for “Stearic acid, monoester with propane-1,2-diol”. The environmental toxicity of this UVCB substance was therefore assessed based on a weight of evidence analysis.
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 short-term toxicity of the UVCB substance.
The lowest effect concentration to microorganism is found for 1,2,3-Propanetriol, homopolymer, decanoate/ Polygyceryl-6 Dicaprate with a 3hr-NOEC=1000 mg/L and a 3hr-IC50>1000 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

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

Total exposure duration:

3 h

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Basis for effect:

inhibition of total respiration

Validity criteria fulfilled:

not applicable

Conclusions:

Based on a weight of evidence approach the substance is concluded to have a toxicity to microorganisms of 3hr-NOEC=1000 mg/L; 3hr-IC50>1000 mg/L

Executive summary:

Data on this endpoint 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,

-       QSAR predictions for main components (monoesters and diesters of propane-diols).

Hereby, a solid data set is available for deriving a conclusion on the environmental toxicity of the UVCB-substance.

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.

Based on a weight of evidence approach the substance is concluded to have a toxicity to microorganisms of 3hr-NOEC=1000 mg/L; 3hr-IC50>1000 mg/L

Description of key information

Based on a weight of evidence approach the substance is concluded to have a toxicity to microorganisms of 3hr-NOEC=1000 mg/L; 3hr-IC50>1000 mg/L

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L