Evernia Prunastri (Oakmoss) Extract
Evernia prunastri, also known as Oakmoss, is a species of lichen that can be found in many mountainous temperate forests throughout the Northern Hemisphere, especially on the bark of oak trees and other deciduous trees and conifers such as fir and pine. The thalli of Oakmoss are short and bushy, and they grow together on bark to form large clumps. The color of Oakmoss ranges from green to greenish-white when dry and dark olive-green to yellow-green when wet.
In cosmetics, Oakmoss extract is used extensively in modern perfumery due to its distinct and complex odor, which can be described as woody, sharp, and slightly sweet. The extract is commercially harvested, primarily in South-Central Europe, and usually exported to the Grasse region of France, where its fragrant compounds are extracted as Oakmoss absolutes and extracts. These materials are often used as perfume fixatives and form the base notes of many fragrances. They are also key components of Fougère and Chypre class perfumes.
However, Oakmoss should be avoided by people with known skin sensitization issues. Its use in perfumes is now highly restricted by International Fragrance Association regulations, and many scents have been reformulated in recent years with other chemicals substituted for Oakmoss. Certain constituents in Oakmoss extracts, such as Atranorin, Evernic acid, Fumarprotocetraric acid, Stictic acid, and Usnic acid, are regarded as responsible sensitizers based on experience from patch testing patients.
According to a report from the European Union, Oakmoss absolute accounts for most of the reactions to the fragrance mix and is regarded as one of the principal allergens in contact sensitivity to perfumes. In a 17-year study in the United Kingdom, Oakmoss absolute was found to be the most common overall allergen, with the incidence of positive tests to Oakmoss increasing by 5% yearly. For these reasons, Oakmoss extract is included in the EU's list of 26 allergens that must be explicitly listed in cosmetics ingredient lists when used above certain concentrations.
It is worth noting that the potential for skin sensitization varies among individuals. In one study, 7 out of 53 healthy human volunteers (approximately 13%) were sensitized to Oakmoss absolute by a procedure involving repeated patch tests with various concentrations of the substance2. In another study, only seven patients among 2000 tested were proven to have an allergy to Oakmoss absolute.
