Research from the University of Gothenburg reported that eczema-provoking allergens formed by the reaction with acid in the ambient air (autoxidation) or with skin enzymes may be to blame for allergic reactions to essential oils. The research report, Formation of Skin Sensitizers from Fragrance Terpenes via Oxidative Activation Routes: Chemical Analysis, Structure Elucidation and Experimental Sensitization Studies, was written by Lina Hagvall, a researcher at the university's chemistry department.
Although many manufacturers find that the antioxidant content in essential oils provides protection against autoxidation, making them safer and longer-lasting than artificial perfumes, the study finds that this may not be the case. The researchers examined natural lavender oil and found that essential oils do not prevent the formation of allergenic substances through reactions with acid. The research also examined geraniol, a common constituent of perfumes such as rose oil. The study shows geraniol by itself to be only slightly allergenic; however through autoxidation and reaction with skin enzymes, the substance is activated and becomes the closely related allergen geranial. This reportedly is the first time these activation pathways have been demonstrated for the substance.
Sensitive skin and immunology research have been topics of great interest in the cosmetics R&D industry, as new mechanisms and pathways to topically incite skin responses are discovered. Thus, it is important to investigate and consider how perfumes as well as other topical agents might react with air on skin.