Contact Allergy to 4,4'-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 in a previous study to be a good tracer of patients with contact allergy to phenol-formaldehyde resins. 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 3 new sensitizers are reported. Investigations by mass spectrometry and nuclear magnetic resonance spectrometry identified the compounds to be 4,4'-dihydroxy-3-(hydroxymethyl)-diphenyl methane (4,4'-H-3-HPM), 4,4'-dihydroxy-3,3'-di-(hydroxymethyl)-diphenyl methane (4,4'-H-3,3'-HPM), and 4,4'-dihydroxy-3,5-di-(hydroxymethyl)-diphenyl methane (4,4'-H-3,5-HPM). Six of the 11 patients reacted to at least one of these compounds. All 6 patients reacted to 4,4'-H-3,3'-HPM and 5 reacted simultaneously to 4,4'-H-3-HPM. Four patients reacted to all 3 compounds tested. By patch testing with serial dilutions (ethanol 99.5%) of the three 4,4'-H-HPM, positive reactions were noted down to 0.5 × 10-6%, 1.0 × 10-6%, and 1.3 × 10-3% w/v for 4,4'-H-3-HPM, 4,4'-H-3,3'-HPM, and 4,4'-H-3,5-HPM, respectively