Background A small epidemic of severe contact dermatitis cases related to newly acquired sofas and chairs has surpassed the news threshold in Finland and the U.K.
Objectives To study affected patients and to identify the cause.
Methods Five patients with contact dermatitis related to a newly purchased chair or sofa were studied. Furniture samples were analysed by gas chromatography–mass spectrometry. Compounds were identified using a mass spectrum library and measured semiquantitatively. Patch tests were performed with commercial standard allergens, furniture upholstery and chemicals found in the analysis.
Results Patch tests with commercial allergens did not solve the problem. Up to 470 μg kg−1 of dimethylfumarate was found in chairs. The patients showed strong positive patch test reactions to upholstery fabric samples and to dimethylfumarate, down to a level of 1 p.p.m. in the most severe case.
Conclusions The cause of the Chinese sofa/chair dermatitis epidemic is likely to be contact allergy to dimethylfumarate, a novel potent contact sensitizer.