The results may have implications for individual diagnosis and prevention and when comparing test results from various centres.

SummaryBackground Acrylates ⁄methacrylates are volatile substances. There might be a gradual decrease in acrylate ⁄methacrylate allergen content over time in patch test preparations but this has not yet been documented. Objectives To determine the allergen content of acrylates ⁄methacrylates in patch test preparations over time under different storage conditions. Methods Five acrylate ⁄methacrylate allergens [2-hydroxyethyl methacrylate (2-HEMA), methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDMA), triethylene glycol diacrylate (TREGDA) and 2-hydroxypropyl acrylate (2-HPA)] in syringes and IQÔ chambers (Chemotechnique Diagnostics, Vellinge, Sweden) were analysed using gel permeation chromatography and high-performance liquid chromatography to measure the allergen content over time in samples stored in the freezer, refrigerator and under room temperature. Results The concentration of allergens in syringes decreased with time. Those stored at room temperature had the fastest rate of decrease, followed by those in the refrigerator and freezer. In most cases, in syringes or IQÔ chambers under all storage conditions, the MMA decreased most rapidly, followed by 2-HPA, 2-HEMA, EGDMA and TREGDA. The allergens in the IQÔ chambers rapidly disappeared, with almost all samples reaching nondetectable levels by day 8. MMA was the first to reach a nondetectable level -at day 2. Conclusions Acrylate ⁄methacrylate allergens are lost rapidly from IQÔ chambers especially if stored at room temperature. Allergens in syringes remain above 80% of their initial concentrations for longer periods compared with IQÔ chambers. In syringes and IQÔ chambers there is a slower rate of decrease in concentration when the storage temperature is lower. Allergens should be stored refrigerated, replaced regularly, and freshly applied on to test patches on the day of use.

The majority of toothpastes on the Swedish market contain l-carvone, but the concentration hardly relates to the advertised flavour or labelled ingredients. It is hitherto unknown whether the found concentrations are sufficient for induction of contact allergy in individuals with healthy oral mucosa or in those with oral lichenoid lesions or other mucosal disease.

In this study, the sensitizing capacities of the 3 main low-molecular-weight isomers of epoxy resins based on diglycidyl ether of biphenol F (DGEBF) were investigated in a guinea pig maximization test (GPMT). The isomers are p,p'-DGEBF, o,p'-DGEBF, and o,o'-DGEBF. The sensitization capacities were compared to diglycidyl ether of bisphenol A (DGEBA), which is the main constituent in the most common epoxy resin. The cross-reaction pattern between all 4 compounds was also investigated. It was found that all 3 DGEBF isomers were potent sensitizers. It was also found that p,p'-DGEBF, o,p'-DGEBF, and DGEBA cross-reacted with one another, and that animals induced with o,o'-DGEBF reacted significantly only to o,p'-DGEBF, but not to the other 2 DGEBF isomers or DGEBA.

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Diglycidyl ether of bisphenol A (DGEBA) is the monomer and most important contact allergen in epoxy resin(s) based on bisphenol A (DGEBA-R). Both thin-layer chromatography (TLC) and high-pressure liquid chromatography (HPLC) methods are available for the analysis of products containing DGEBA-R. With respect to detection and quantification, epoxy resins of the bisphenol F-type, i.e. epoxy resins containing the isomers of diglycidyl ethers of bisphenol F (DGEBF), are not as well investigated as DGEBA-R. The isomers of DGEBF are p,p'-DGEBF, o,p'-DGEBF and o,o'-DGEBF. Both p,p'-DGEBF and o,p'-DGEBF have been shown to be contact allergens in humans, and all 3 isomers are sensitizers in the guinea pig maximization test. We aimed (i). to develop HPLC methods for separation and purification of the individual DGEBF isomers, (ii). to detect and quantify the DGEBF isomers in epoxy resins of the bisphenol F-type and (iii). to evaluate and develop the TLC as a method for the detection of the DGEBF monomers. We found the total content of the DGEBF isomers in the investigated epoxy resins of the bisphenol F-type to vary from 17.0 to 81.7% w/w. Some of them also contained 0.1-2.4% w/w DGEBA. The HPLC method showed a sensitivity that was 2000-20 000x higher than that obtained with the TLC method for the DGEBF monomers. We concluded that the range of the DGEBF isomer content in epoxy resins of the bisphenol F-type is approximately the same as the monomer content in liquid compared to solid DGEBA-R. The relevance of contact allergy to DGEBA-R can remain unrecognized if the suspected product is an epoxy resin of the bisphenol F-type, which is analysed with the TLC method.

Allergy to p-tert-butylphenol formaldehyde resin (PTBP-F-R) is not rare. More knowledge about the sensitizers in the resin can contribute to the development of diagnosis and prevention. The objective was to study some trimers in PTBP-F-R. Preparative and analytical high-pressure liquid chromatography, nuclear magnetic resonance spectrometry, mass spectrometry and patch testing in patients hypersensitive to PTBP-F-R were used. Four trimers were isolated and identified: 4-tert-butyl-2,6- bis-(5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzyloxy-methyl)-phenol (XIII), 4-tert-butyl-2-(5-tert-butyl-2-hydroxy-benzyloxymethyl)-6-(5-tert-butyl-2-hydroxy-3-hydroxymethyl-benzyloxymethyl)-phenol (XIVa), 9,17,25-tri-tert-butyl-27,28,29-trihydroxy-2,3,4,5,12,13,20,21-octahomo-3,5,13,21-tetraoxacalix[3]arene (XVIIa) and 7,15,23-tri-tert-butyl-25,26,27-trihydroxy-2,3,10,11,18,19-hexahomo-3,11,19-trioxacalix[3]arene (XVIII). Six patients hypersensitive to PTBP-F-R were patch tested with serial dilutions of XIII, XIVa, XVIIa and XVIII. Six 6, 1 and 0 patients reacted positively to XIII, XIVa, XVIIa and XVIII, respectively. No control patient reacted positively to XIII or XIVa. Positive patch test reactions were seen down to 0.025 mmol × 1^–1 for XIII and XIVa. The study shows that XIII and XIVa are allergens in PTBP-F-R and strongly argues that XVIIa is also one.

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