The International Contact Dermatitis Research Group increased the patch test concentration of formaldehyde from 1.0% aqueous (aq) to 2.0% aq (in 2011).
This study was designed to investigate the outcome of the decision.
Consecutive dermatitis patients in 8 different clinics were patch tested with formaldehyde 1.0% aq and 2.0% aq. The test solutions were applied with a micropipette to the filter paper discs in the respective chamber.
A total of 2778 patients were tested with 1.0% aq and 2766 to 2.0% aq. Sixty-five patients (2.3%, calculated from 2766 tested, to 2.0% aq) had positive patch test reactions interpreted as contact allergy to formaldehyde. This is a rather low frequency. Of these 65, 46 were women (46/1703 [2.7%]) and 19 were men (19/1063 [1.8%]). Thirty-six reacted only to 2.0% aq, 21 patients reacted to both concentrations, and 8 patients reacted only to 1.0% aq. Significantly, more patients reacted to 2.0% aq compared with 1.0% aq (P < 0.001). There was no significant sex difference. A total of 0.8% irritant reactions were recorded to formaldehyde 2.0% aq and 0.1% to 1.0% aq.
The increased formaldehyde patch test concentration to 2.0% aq revealed more formaldehyde contact allergy.
From the *Department of Occupational and Environmental Dermatology, Lund University, Skåne University Hospital, Malmoe, Sweden
†Allergy Center and Department of Dermatology, University Hospital, Republic University of Uruguay, Montevideo
‡Department of Dermatology and Allergy Centre, Odense University Hospital, University of Southern Denmark
§Department of Dermatology, National Skin Center, Singapore
∥Contact Allergy Unit, Department of Dermatology, University Hospital K.U. Leuven, Belgium
¶Department of Dermatology, MGM Medical College, Navi Mumbai, India
#Department of Integrative Medical Science for Allergic Disease, Fujita Health University School of Medicine, Nagoya, Japan
**St John's Institute of Dermatology, Contact Dermatitis Clinic, St Thomas' Hospital, London, United Kingdom.
Address reprint requests to Marléne Isaksson, MD, PhD, Department of Occupational and Environmental Dermatology, Jan Waldenströms gata 16, SE 205 02, Malmö, Sweden. E-mail: marlene.isaksson@skane.se.
The authors have no funding or conflicts of interest to declare.
Online date: September 16, 2019
