Cross-Sensitization Between Frullania and Laurus nobilis: The Allergen Laurel

To the Editor.—  The essential oil extracted from the leaves of Laurus nobilis (L) is responsible for a number of allergic contact dermatitides.¹ At the Consultation d'Allergologie et de Dermatoses Professionnelles of Strasbourg in France, this allergy represented 17.8% of the total allergic contact dermatitides to plants in the 1967-1972 statistics. Frullania. a liverwort commonly found in forests, growing on tree barks or even rocks in France,^2-4 Scotland,⁵ and British Columbia, Canada,⁶ especially, is also known to cause allergic contact dermatitis. Two or three years ago in Strasbourg, it was found that patients allergic to Frullania were also allergic to the laurel essential oil extracted from the leaves. More recently, these cross-sensitizations were also found in Bordeaux, France, and in British Columbia (J. C. Mitchell, MD, written communication, March 1974).A number of allergens have been isolated from Frullania species.^2-6 They all are α-mathylene γ-butyrolactone