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Case Reports
July 1969

Allergy to Frullania: Allergic Contact Dermatitis Occurring in Forest Workers Caused by Exposure to Frullania nisquallensis

Author Affiliations

Vancouver, BC

From the Division of Dermatology, Department of Medicine (Dr. Mitchell) and the Department of Botany (Drs. Schofield, Singh, and Towers), The University of British Columbia.

Arch Dermatol. 1969;100(1):46-49. doi:10.1001/archderm.1969.01610250052012

Positive patch test reactions to Frullania nisquallensis were observed in seven forest workers who had allergic contact dermatitis. Frullania is a genus of leafy liverworts. Five of these seven patients also showed coincidental positive patch test reactions to usnic acid derived from lichenized fungi. Attacks of such dermatitis occurred only during work in forest areas, were worse in wet weather, appeared within a day or two of starting work amongst vegetation, and subsided in two to four weeks after leaving work. "Cedarpoisoning" is a misnomer for allergic contact dermatitis occurring in forest workers in British Columbia; such dermatitis results from exposure to species of epiphytes on trees.

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