Allergic contact dermatitis from non-diglycidyl-ether-of-bisphenol-A epoxy resins

In addition to previously presented patients with allergic contact dermatitis from cycloaliphatic epoxy resins (ERs), during 1974-1990, we have seen 4 patients with allergic contact dermatitis (ACD) caused by products containing uncured non-diglycidyl-ether-of-bisphenol-A ER. The patients were negative on patch testing with the standard ER based on diglycidyl ether of bisphenol A (DGEBA-ER). The following non-DGEBA-ERs were included in the causative agents: heterocyclic dimethylhydantoin ER, phenol novolak ER, and brominated ER. We were unable to specify the type of ER in an epoxy primer used by the 4th patient. Apart from the ACD caused by the brominated ER, 1 of the patients also had IgE-mediated occupational rhinitis caused by methyl hexahydrophthalic anhydride (MHHPA), an epoxy hardener. The diagnosis was verified by positive prick tests and specific IgE determinations with MHHPA. Intense rhinitis evoked by a bronchial challenge with MHHPA confirmed the diagnosis. We stress the importance of performing patch testing with the relevant epoxy resins to which the patient has been exposed, in addition to patch testing with the standard ER.     

Simple methods for demonstration of epoxy resins of bisphenol A type

Low molecular weight oligomers of epoxy resins of bisphenol A type are common sensitizers. For demonstrating the presence of sensitizing oligomers of these resins, two simple methods are described. The first one, a colour reaction, demonstrates the presence of the bisphenol A skeleton. If this test is positive, thin-layer chromatography is carried out to demonstrate the presence of low molecular weight oligomers of epoxy resins. Some practical applications are reported.     

Sensitivity to epoxy resins and triethylenetetramine

The present studies concerned 31 work sites in eight factories at which 422 persons were employed. In the course of seven years there were 126 cases of dermatitis, 99 of whom were patch-tested. Positive reactions to epoxy resin and/or to triethylenetetramine were found in 65.7% of the subjects. The aetiology of the other cases is discussed. Some of the patients who were positive to epoxy resin were tested with Bisphenol A and modified resins with blocked epoxy groups. The latency period of dermatitis and the localization were recorded, as well as the influence of the season and of certain working conditions on the occurrence of sensitization. Of the 80 patients who changed their occupation, there were relapses in 50 within one year. Relapses were more frequent in persons who continued to work with epoxy resins for more than three months after the appearance of dermatitis and in those simultaneously sensitive to allergens in the standard series.     

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.     

Hand dermatoses and contact allergic reactions in construction workers exposed to epoxy resins

In 23/135 (18%) workers exposed to epoxy resins, a work-related dermatosis on the hands and/or forearms had been present during the past 3 years. In 9 persons, the occupational dermatosis was still present at the time of investigation. In all workers, patch tests were performed with epoxy resin, isophoronediamine, triethylenetetramine and xylenediamine. Positive patch tests were observed in 27 of the 135 exposed workers (20%) 13 of whom had never previously experienced skin problems. Epoxy resin accounted for the majority of the positive reactions. There was no relation between a history of atopy and the development of contact allergy. Only half of all workers had received any safety instructions. The wearing of gloves (mostly cotton), intended to protect the skin, had an adverse effect.     

Patch testing with a mixture of 2 phenol-formaldehyde resins

1310 patients were routinely patch tested with a paratertiary-butylphenol-formaldehyde resin (PTBP-F-R), a resol resin based on phenol and formaldehyde (P-F-R-2), and a mixture of these 2 resins. Approximately 2.5 times more patients with contact allergy to phenol-formaldehyde resins were diagnosed when routinely patch tested with P-F-R-2 in addition to PTBP-F-R. Although patch testing with a mixture of both resins was not as good as patch testing with the 2 resins separately, it was better than testing only with PTBP-F-R, since 1.6 times more patients with contact allergy to phenol-formaldehyde resins were still diagnosed. P-F-R-2 is therefore recommended for routine patch testing, preferably as a separate patch test but otherwise as a mixture with PTBP-F-R.     

Penetration of protective gloves by epoxy resin

A gas jointer developed dermatitis from epoxy resin of Bisphenol A type. This substance penetrates plastic and rubber gloves. The man was compelled to change his job. There is a need for new types of gloves which are impermeable. The wearing of the existing types of glove by those not sensitised may be worthwhile because it probably lessens the dose of allergen absorbed and hence lessens the incidence of sensitisation.     

Allergic contact dermatitis from dental composite resins due to aromatic epoxy acrylates mid aliphatic acrylates

7 patients were occupationally sensitized to dental composite resin products (DCR): 6 dental nurses and 1 dentist. All had a positive patch test to their DCR. 2 independent types of allergy were seen; (a) aromatic epoxy acrylate, and/or (b) aliphatic acrylates. 4 out of 5 patients reacted to BIS-GMA, the most widely used aromatic epoxy acrylate in DCR, but not the dentist. She and 2 dental nurses were allergic to aliphatic acrylates, including triethylene glycol dimethacrylate (TREGDMA) and triethylene diglycol diacrylate (TREGDA). 4 patients were allergic to epoxy resin (ER) (containing mainly MW 340), possibly an impurity in some DCR. 2 patients were also allergic to methyl methacrylate (MMA): the dentist, had been exposed to MMA, but the nurse's exposure was uncertain. 1 patient was also allergic to rubber gloves, 2 to rubber chemicals but not their gloves, and 5 to disinfectants used. diagnosis was delayed as long as 13 years in spite of previous patch testing. Dermatologists need to use the patients' own DCR and the (meth)acrylate series for patch testing. No dental nurses could continue their occupation, but the dentist could occasionally handle DCR if wearing PVC gloves. Dental personnel need to know about the risks of DCR, and use no-touch techniques and protective gloves.