Natural aromatic oils may cause allergies

Feb 3 2009

Hypersensitivity to perfumes is the most common contact allergy in adults.

Research at the University of Gothenburg has demonstrated that even natural aromatic oils, which many deem harmless compared to synthetic perfumes, may cause allergic reactions.

Roughly one in five adults in northern Europe is believed to suffer from contact allergy to one or more chemicals. The most common is nickel allergy, but many people also suffer from contact allergy to perfumes – even perfume substances that at first glance appear to be harmless can cause allergic reactions. New eczema-provoking allergens are formed by reaction with acid in the ambient air (known as autoxidation) or with skin enzymes.

Modern society commonly regards anything that comes from nature as being healthier and less dangerous. Where it concerns natural aromas, known as essential oils, many manufacturers believe that natural antioxidants in these oils offer protection against autoxidation thus making them safer and longer lasting than artificial perfumes. Research at the University of Gothenburg shows this is not the case.

Lina Hagvall, a researcher at the University of Gothenburg's Department of Chemistry, has examined natural lavender oil in her thesis. Her results show that essential oils do not prevent the formation of allergenic substances through reactions with acid; something which had not previously been possible to confirm. Hagvall's thesis also examines 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 is the first time these activation pathways have been demonstrated for the substance.

It is important to investigate how perfumes react with air or on skin. Lina Hagvall's thesis concludes that such risks must be factored into health risk assessments of chemicals relating to contact allergy. The thesis also demonstrates that more perfumes than previously believed can be activated into allergens, and that more studies should be done to increase knowledge within the field and thus reduce the number of eczema cases.