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

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation, other

Type of information:

other: weight of evidence analysis based on expert evaluated data on hydrolysis products and structural analogues

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: based on expert group reviews

Justification for type of information:

No studies are available for Stearic acid, monoester with propane-1,2-diol (PGMS). Data were therefore obtained for the group of propylene glycol stearate (PGS), the relevant hydrolysis products and structural analogues.

PGMS and PGS are both UVCB substances, formed by esterification of propane-1,2-diol and stearic acid (and to a lesser extent palmitic acid) but PGS has a higher diester content and lower monoester content than PGMS. The UVCB substance belongs to the group of PGS, which are commonly used in cosmetics and as food ingredients (CIR 1983 and CIR 2015).

In order to assess the skin sensitisation potential of PGMS, the toxicity of PGS in general is therefore considered. Based on the data on PGS, the close similarity between PGS and PGMS and the identical QSAR predictions for the skin irritation potential of PGS and PGMS it can by weight of evidence be concluded that the data is considered acceptable for the present substance.

In general, data from the following expert assessments evaluating PGS are used in a weight of evidence approach:
CIR (1983). Final report on the safety assessment of propylene glycol stearate and propylene glycol stearate self-emulsifying. J Am Coll Toxicol 2(5), 101-124.
CIR (2015). Safety Assessment of Propylene Glycol Esters as Used in Cosmetics. Final amended report December8-9, 2014. 23 pp.
CIR (2019). Safety Assessment of Fatty Acids & Fatty Acid Salts as Used in Cosmetics. Tentative Report for Public Comment. January 4, 2019
EFSA (2018). Re-evaluation of propane-1,2-diol (E 1520) as a food additive EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS). EFSA Journal 2018;16(4):5235
Guillot JP, Gonnet JF, Clément C, Faccini JM (1983). Comparative study of methods chosen by the Association Française de Normalisation (AFNOR) for evaluating sensitizing potential in the albino guinea-pig. Fd. Chem. Toxic. 21, 795-805
Basketter DA, Gerberick GF, Kimber I (1998). Strategies for identifying false positive responses in predictive skin sensitization tests. Food and Chemical Toxicology, 36, 327-333

Data source

Reference

Reference Type:

other company data

Title:

Unnamed

Year:

2022

Report date:

2022

Materials and methods

Principles of method if other than guideline:

The results are based on a weight of evidence analysis from collection of studies extracted from the literature. For more details please refer to the attached weight of evidence document.

Stearic acid, monoester with propane-1,2-diol (PGMS) is an UVCB substance, formed by esterification of propane-1,2-diol and stearic acid (and to a lesser extent palmitic acid). The UVCB substance belongs to the group of propylene glycol stearate (PGS), which are commonly used in cosmetics and as food ingredients.

In order to assess the skin sensitisation potential, the toxicity of PGS in general is therefore considered. PGS is very comparable to PGMS as the substances are formed by esterification of propane-1,2-diol and stearic acid (and to a lesser extent palmitic acid) although PGS has a higher diester content and lower monoester content than PGMS. As expert-reviewed information/reports on in vivo metabolism and toxicity are available, read-across to data on PGS is considered acceptable for the present substance.

Type of study:

other: weight of evidence analysis based on expert evaluated data on hydrolysis products and structural analogues using in vivo/in vitro data

Test material

Test material information

1

Reference substance name:

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

EC Number:

215-354-3

EC Name:

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

Cas Number:

1323-39-3

Molecular formula:

C21H42O3

IUPAC Name:

2-hydroxypropyl stearate

Test material form:

solid: pellets

Results and discussion

In vivo (non-LLNA)

Results

Remarks on result:

other: Based on the studies available for propylene glycol stearate, the relevant hydrolysis products and the components of the UVCB substance, it is concluded that the test substance is not a skin sensitiser.

In vivo (LLNA)

Results

Remarks on result:

other: Based on the studies available for propylene glycol stearate, the relevant hydrolysis products and the components of the UVCB substance, it is concluded that the test substance is not a skin sensitiser.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

No relevant testing data for stearic acid, monoester with propane-1,2-diol (PGMS) regarding skin sensitisation is available and also, no conclusive data is available for propylene glycol stearate (PGS) which is widely used in cosmetics (PGS has a higher fraction of diester compared to PGMS). A limited study in two guinea pigs using intracutan injections of 0.1% (PGS) did not result in sensitisation. Further, clinical testing of cosmetic formulations containing PGS in a concentration of 1.5-2.5% did not result in any cases of sensitisation among 4984 subjects suggesting a lack of skin sensitising properties. Danish QSAR database predictions of propylene glycol monostearate further indicate lack of a skin sensitising properties. Also, in relation to the primary starting materials and possible product of hydrolysis of PGMS, propane-1,2-diol and stearic acid, there is no concern for skin sensitising properties according to experimental animal data for propane-1,2-diol and according to QSAR predictions for stearic acid. So, overall, and by weight of evidence PGMS is concluded without potential for skin sensitisation. Thus, PGMS is not to be classified as a skin sensitiser according to the CLP-criteria (EC no 1272/2008).

Executive summary:

No test data on stearic acid, monoester with propane-1,2-diol (PGMS) is available for skin sensitisation, but some data on propylene glycol stearate (PGS), that contains a higher fraction of diesters as PGMS is available from CIR safety assessments reports evaluating the use of PGS in cosmetics (CIR 1983 and CIR 2015). Furthermore, QSAR predictions are included in the overall weight of evidence assessment.

 

A limited study in two guinea pigs using intracutaneous injections of 0.1% (PGS) did not result in sensitisation. Further, clinical testing of cosmetic formulations containing PGS in a concentration of 1.5-2.5% did not result in any cases of sensitisation among 4984 subjects suggesting a lack of skin sensitising properties. Danish QSAR database predictions of propylene glycol monostearate further indicate lack of a skin sensitising properties. Also, in relation to the primary starting materials and possible product of hydrolysis of PGMS, propane-1,2-diol and stearic acid, there is no concern for skin sensitising properties according to experimental animal data for propane-1,2-diol and according to QSAR predictions for stearic acid.

 

So, overall, and by weight of evidence PGMS is concluded without potential for skin sensitisation. Thus, PGMS is not to be classified as a skin sensitiser according to the CLP-criteria (EC no 1272/2008).

 

Overall, the available information comprises adequate, reliable studies from reference substances with similar structure and intrinsic properties. Using data from comparable substances 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.