The use of laboratory methods in contact dermatitis induced by composite materials

Chemical analysis of monomers in epoxy resins based on bisphenols F and A

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.

Analysis of patients with allergic patch test reactions to a plastics and glues series

839 patients were patch tested with a series of 31 plastics and glues allergens at a dermatologic clinic over a period of 7 years. 52 (6%) had a positive patch test reaction to 1 or more such allergens. Clinic charts of 47 patients (out of 52) were available for the study. All but 3 patients had dermatitis on their hands: 17 had only hand dermatitis. 25 (53%) patients' test results were of present or past relevance to their skin diseases. 11 patients (68%) with occupational allergic contact dermatitis (ACD) and 14 (45%) with non-occupational dermatitis had relevant reactions. p-tertiary-butylphenol-formaldehyde resin was the most common allergen (9 cases). 7 patients reacted to diaminodiphenylmethane. 5 patients, who had colophony allergy, reacted to abietic acid and 4 to abitol. There was no reaction to 14 test substances. Special series, such as this plastics and glues series, reveal the cause of ACD less frequently than standard series. However, there is no other way to confirm allergy to these usually industrial allergens, which can also sensitize through non-occupational exposure during hobby working or through unpolymerized monomer left in the finished plastic product.

Allergic contact dermatitis of the lip margins from para-tertiary-butylphenol in a lip liner

We describe the use of gas chromatography with mass spectrometry (GC-MS) in the investigation of a case of allergic contact dermatitis of the lip margins caused by a lip liner. Patch testing identified sensitization to para-tertiary-butylphenol-formaldehyde resin (PTBP-FR), a resin glue frequently used in leather work but rarely found in cosmetics. Investigation specified the para-tertiary-butylphenol (PTBP) component of the resin as the hapten responsible for the allergic contact dermatitis, as well as for associated depigmentation.