1,18-octadecanedioic acid

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Skin sensitisation

Fatty acids are found in all living organisms fulfilling fundamental physiological functions within the body. Based on this role within the body no sensitization potential of fatty acids is expected as it could be demonstrated by animal studies with C9 fatty acid (azelaic acid), C10 fatty acid (decanoic acid), C12 fatty acid (lauric acid) and C18-di fatty acid (1,18 octadecanedioic acid), respectively.

These considerations are supported by the test result (OECD 406 Vaeth, 2001) of C18 di..

These observations are supported by test results of various category members. Azelaic acid (CAS# 123-99-9) was examined for its skin sensitization potential in a Guinea Pig Maximisation test which was conducted under GLP according to OECD guideline 406 (Lea, 1995). 10 Dunkin-Hartley guinea pigs received an intradermal injection of 0.25% azelaic acid for induction followed by the second induction 8 days later as an application of 50% azelaic acid on the same site, which had been previously treated with 10% SDS in petrolatum. The used concentrations were based on a preliminary range finding test, where the suitable concentrations for the intradermal injection and patch testing were evaluated. Eleven days after the induction application the test animals and the 5 control animals were challenged with 50% test material by occluded patch. As result, no sensitizing effects could be observed 24 and 48 hours after the challenge. The skin sensitization potential of decanoic acid (CAS# 334-48-5) was tested in a Buehler test, where 20 guinea pigs were induced with an epicutanous application of 5% decanoic acid in 40% ethanol under occlusion for 6 hours once a week for three consecutive weeks (Sauter and Ritz, 1975). Two weeks after the last induction, the animals were challenged epicutanously under occlusion with a concentration of 5% decanoic acid in acetone for 6 hours. The readings 24 and 48 hours after removal of the patches revealed occasional very slight degree of irritation in the dose and control groups, respectively. However, no signs of a sensitization reaction were noted. The same negative result was obtained for lauric acid (CAS# 143-07-7) tested in a study according to the method described by Magnusson and Kligman (Gloxhuber and Potokar, 1979). 20 female Pirbright-white guinea pigs received an induction by intradermal injection and were challenged with a concentration of 2.5% epicutanously under occlusion for 24 hours. The readings of the skin sites 24 and 48 hours later did not reveal any reaction so that lauric acid is regarded as not sensitizing to skin. As a short chain dicarboxylic acid (worst case C9 - azelaic acid) shows no sensitizing effect can be concluded that longer chain dicarboxylic acids have also no adverse effects.

On the basis of the results for C18 -di and the other category members it is concluded that these substances are not sensitizing.

Migrated from Short description of key information:
Not sensitising

Respiratory sensitisation

Endpoint conclusion

Additional information:

No data available

Migrated from Short description of key information:
No data available

Justification for classification or non-classification

According to DSD (67/548/EEC) or CLP (1272/2008/EC) classification criteria for skin sensitisation, fatty acids do not fulfill the criteria for classification and thus a non-classification is warranted for this endpoint.