Contact allergy to epoxy hardeners.

Background. Diglycidylether of bisphenol A resin is the most important sensitizer in epoxy systems, but a minority of patients develop concomitant or solitary contact allergy to epoxy hardeners. At the Finnish Institute of Occupational Health, several in-house test substances of epoxy hardeners have been tested in a special epoxy compound patch test series. Objectives. To analyse the frequency and clinical relevance of allergic reactions to different epoxy hardeners. Methods. Test files (January 1991 to March 2013) were screened for contact allergy to different epoxy hardeners, and the clinical records of patients with allergic reactions were analysed for occupation, concomitant allergic reactions, and exposure. Results. The most commonly positive epoxy hardeners were m-xylylenediamine (n=24), 2,4,6-tris-(dimethylaminomethyl)phenol (tris-DMP; n=14), isophoronediamine (n=12), and diethylenetriamine (n=9). Trimethylhexamethylenediamine (n=7), tetraethylenepentamine (n=4), and triethylenetetramine (n=2) elicited some reactions, although most patients were found to have no specific exposure. Allergic reactions to hexamethylenetetramine, dimethylaminopropylamine and ethylenediamine dihydrochloride were not related to epoxy products. Conclusions. Tris-DMP is an important sensitizer in epoxy hardeners, and should be included in the patch test series of epoxy chemicals.