Contact allergy to the monomers in p-tert-butylphenol-formaldehyde resin

In many adhesive formulations p-tert-butylphenol-formaldehyde resin (PTBP-F-R) is used as a binder. Contact allergy to this resin is not rare. In patients hypersensitive to PTBP-F-R, and butylphenol derivatives therein, it is for diagnostic and preventive reasons necessary to know the nature of the primary sensitizing substances, as well as the cross-reaction patterns for these. The aim of this study was to investigate contact allergy to monomers in PTBP-F-R and potential cross-reacting substances. 12 patients hypersensitive to PTBP-F-R were patch tested with 2 monomers, the raw materials formaldehyde and p-tert-butylphenol, and 3 closely related substances. High pressure liquid chromatography (HPLC) was used to investigate the purity of the test substances. It was shown that the monomers 2-methylol p-tert-butylphenol and 2,6-dimethylol p-tert-butylphenol could elicit allergic reactions in humans hypersensitive to PTBP-F-R. No simultaneous reactions or cross-reactions were shown to formaldehyde, p-tert-butylphenol, p-tert-butylcatechol, 2(3)-tert-butyl-4-hydroxyanisole (BHA) or 3,5-di-tert-butyl-4-hydroxytoluene (BHT). It was also shown that low amounts of contaminants in the test substances, if not taken into account, could influence the conclusions drawn from the test results obtained.