Contact allergy to 2,4'-dihydroxy-(hydroxymethyl)-diphenyl methanes. Sensitizers in a phenol-formaldehyde resin

A particular phenol-formaldehyde resin of the resol type (P-F-R-2) was shown to be a good marker for patients with contact allergy. Eleven patients with sensitivity to P-F-R-2 participated in the study in which chromatographically separated fractions of P-F-R-2 were patch tested. This procedure was repeated until a positive reaction to a single substance was noted. In this study 2 sensitizers are reported. Investigations by mass-spectrometry and nuclear magnetic resonance spectrometry identified the compounds to be 2,4'-dihydroxy-3,3'-di-(hydroxymethyl)-diphenyl methane (2,4'-H-3,3'-HPM) and 2,4'-dihydroxy-3',5'-di-(hydroxymethyl)-diphenyl methane (2,4'-H-3',5'-HPM). Six of 11 patients reacted to at least one of the compounds and simultaneous reactions were noted in 4 patients. By patch testing with serial dilutions of the two sensitizers positive reactions were noted down to 0.14 X 10(-3)% and 0.41 X 10(-3)% w/v for 2,4'-H3,3'-HPM and 2,4'-H-3',5'-HPM respectively.