Assessment of cross-reactivity of new less sensitizing epoxy resin monomers in epoxy resin-allergic individuals

The new Italian SIDAPA Baseline Series for patch testing (2023): an update according to the new regulatory pathway for contact allergens

Allergic contact dermatitis (ACD) is a common inflammatory skin disease caused by delayed hypersensitivity to chemical and biotic contact allergens. ACD significantly affects the patients' quality of life negatively impacting both occupational and non-occupational settings. Patch testing is the gold standard diagnostic in vivo test to precise the ACD etiology and to correctly perform prevention. According to the Italian Medicines Agency (AIFA) legislative decree no. 178 of 29th May 1991, allergens are defined as medicines and therefore they are subject to strict regulation. In 2017, AIFA (decree no. 2130/2017) started a procedure to regulate contact allergens on the Italian market and actually the contact allergens temporarily authorized are reported in AIFA decree no. 98/2022, valid until November 2023. The availability on the market of contact allergens to diagnose ACD and continuous updating on the basis of new epidemiological trends are mandatory, jointly with the continuous update of the baseline and integrative series for patch testing. For this reason, the scientific community represented in Italy by the Skin Allergies Study Group of SIDeMaST (Italian Society of Dermatology and Venereology) and SIDAPA (Italian Society of Allergological, Occupational and Environmental Dermatology) are constantly working, in close relationship with the European scientific communities with large expertise in this important sector of the modern Dermatology. Herein, we report the setting up of regulatory legislation by AIFA and the new Italian Adult Baseline Series for patch testing.

Occupational exposure to epoxy components and risk of dermatitis: A registry-based follow-up study of the wind turbine industry

BACKGROUND

Allergic contact allergy and dermatitis are frequently reported among epoxy-exposed workers.

OBJECTIVES

To determine the risk of dermatitis associated with epoxy exposure.

METHODS

We followed 825 epoxy-exposed and 1091 non-exposed blue-collar workers, and 493 white-collar workers of a Danish wind turbine blade factory during 2017-2022 with linked data from national health registers on diagnoses, patch testing, or fillings of prescriptions for topical corticosteroids. Incidence rate ratios of dermatitis or a first-time topical corticosteroid prescription were estimated with Poisson regression using non-exposed blue-collar workers as reference. We similarly estimated incidence rate ratios for the duration of epoxy exposure and current epoxy exposure.

RESULTS

Epoxy-exposed blue-collar workers showed a dermatitis incidence rate of 2.1 per 100 000 person days, a two-fold increased risk of dermatitis and a 20% increased risk of filling a prescription for topical corticosteroids. Incidence rate ratios were higher during early exposure and declined with further exposure for both outcomes. White-collar workers had generally lower risks.

CONCLUSION

We observed an increased risk of dermatitis following epoxy exposure confirming previous case reports and cross-sectional studies emphasizing the need for intensified focus on preventive efforts for this group of workers.

Epoxy allergy, investigation of a modern industry

BACKGROUND

Five workers from an industry manufacturing various articles from carbon fibre reinforced epoxy plastics were referred to our department because of suspected occupational allergic contact dermatitis (OACD). When patch tested, four of them had positive reactions to components of epoxy resin systems (ERSs) that could explain their current skin problems. All of them had been working at the same workstation at a specially designed pressing machine, with operations including manually mixing epoxy resin with hardener. Multiple cases of OACD in the plant prompted an investigation including all workers with possible risk exposures at the plant.

OBJECTIVES

To investigate the prevalence of occupational dermatoses and contact allergies among the workers at the plant.

MATERIALS AND METHODS

Totally 25 workers underwent investigation that included a brief consultation with a standardized anamnesis and clinical examination followed by patch testing.

RESULTS

ERSs-related reactions were found in 7 of the 25 investigated workers. None of the seven had a history of previous exposure to ERSs and they are regarded as sensitized through work.

CONCLUSIONS

Twenty-eight percent of investigated workers showed reactions to ERSs. Of these the majority would have been missed if supplementary testing would not have been added to testing with the Swedish base line series.

Prevalence of skin sensitization and dermatitis among epoxy-exposed workers in the wind turbine industry

BACKGROUND

A high prevalence of skin sensitization and dermatitis has been reported among workers exposed to epoxy components.

OBJECTIVES

To estimate the risk of skin sensitization and dermatitis among workers exposed to epoxy components during production of wind turbine blades while using comprehensive safety measures.

METHODS

A cross-sectional study of 180 highly epoxy-exposed production workers and 41 nonexposed office workers was conducted at two wind turbine blade factories in Denmark. Participants underwent a skin examination, were tested with a tailored patch test panel including epoxy-containing products used at the factories, and answered a questionnaire.

RESULTS

Sixteen production workers (8·9%) were sensitized to an epoxy component compared with none of the office workers. Skin sensitization was more frequent within the first year of exposed employment. Strong selection bias by atopic status was indicated. Among nonatopic workers, the prevalence of dermatitis was higher among production workers (16·4%) than among office workers [6·5%, odds ratio (OR) 2·3, 95% confidence interval (CI) 0·6-9·1] and higher among the sensitized workers (43·8%) than the nonsensitized workers (14·6%, OR 4·5, 95% CI 1·6-12·7). Resins based on diglycidyl ether of bisphenol A and F were the most frequent sensitizers. One of the four workers sensitized to epoxy components used at the factories did not react to the epoxy resin of the TRUE test^® panel.

CONCLUSIONS

Despite comprehensive skin protection, sensitization and dermatitis are prevalent among highly epoxy-exposed workers in the wind turbine industry in Denmark. Our findings document the need for intensified preventive efforts and emphasize the importance of tailored patch testing. What is already known about this topic? Epoxy components are well-known sensitizers of the skin. A high prevalence of skin sensitization and dermatitis has been reported among workers exposed to epoxy components. Comprehensive protective equipment is recommended when working with epoxy components. What does this study add? Despite comprehensive skin protection, skin sensitization and dermatitis are prevalent among epoxy-exposed workers. We found that 40% of workers sensitized to epoxy products had dermatitis. Only 75% of the sensitized workers were detected by the epoxy resin of the TRUE test^® , which emphasizes the importance of tailored testing.

Development of New Epoxy Resin Monomers - A Delicate Balance between Skin Allergy and Polymerization Properties

Epoxy resin monomers (ERMs) are used as building blocks for thermosetting polymers in applications where strong, flexible, and lightweight materials are required. Most epoxy resins are polymers of diglycidyl ether of bisphenol A (DGEBA). It is highly allergenic and causes occupational allergic contact dermatitis and contact allergy in the general population. Thus, measures to prevent exposure by protective clothing and education are not enough. This work describes a continuation of our research aiming at reducing the skin-sensitizing potency of ERMs while maintaining the ability to form polymers. Alternative ERMs were designed and synthesized whereafter the sensitizing potency was determined using the murine local lymph node assay (LLNA). The reactivity of the diepoxides toward a nucleophilic peptide was investigated, and the differences in reactivity explained using computational studies. The diepoxides were reacted with triethylenetetramine, and the formed polymers were tested for technical applicability using thermogravimetric analysis. We had previously shown that the absence of an oxygen atom in the side chains or removal of aromaticity reduced the sensitizing potency compared to that of DGEBA. Thus, a cycloaliphatic analogue 1 of DGEBA without ether oxygen in the side chains was considered promising and was synthesized. As predicted, the sensitizing potency was considerably reduced (10 times) compared to that of DGEBA. However, the technical properties of the polymer of this compound were not considered sufficient. More polar aromatic analogues were investigated, but they could not compete with our previously described ERMs regarding polymerization properties and with 1 regarding low skin sensitization properties. Development of alternative epoxy materials is a delicate balance between allergenic activity and polymerization properties. Tuning of structural properties together with investigation of polymerization conditions combined with skin sensitization studies should be used in industrial research and development. ERM 1 could be used as a lead compound for further studies of aliphatic ERMs.

Skin exposure to epoxy chemicals in construction coating, assessed by observation, interviews, and measurements

BACKGROUND

Epoxy resin systems (ERSs) are among the leading causes of occupational allergic contact dermatitis.

OBJECTIVES

To identify riskful exposures and sources of skin exposure, and to quantify skin exposure to diglycidyl ether of bisphenol A (DGEBA) epoxy monomer, in construction coating work.

METHODS

Skin exposure to epoxy chemicals was studied in 5 coating companies through (a) interviews and visual observation, (b) quantifying DGEBA on 12 workers' skin by tape-stripping, (c) measuring DGEBA on 23 surfaces by wipe-sampling, and (d) quantifying DGEBA in new sewage pipe. Acetone extracts of the tapes, wipes and sawdust from a newly hardened sewage pipe were analysed by gas chromatography/mass spectrometry.

RESULTS

Identified riskful exposures were, for example, mixing ERSs, handling coating pots, and working above shoulder level. Epoxy stains on, for example, tools, equipment and clothing were seen in all workplaces. Protective gloves were of varying quality, and were not always suitable for chemicals. The amount of DGEBA on the workers' skin varied considerably. All screened tool handles were contaminated. Two-day-old epoxy sewage pipe contained 3.2% DGEBA.

CONCLUSIONS

Construction coating entails skin contact with ERSs directly and via contaminated surfaces, personal protective equipment, and recently hardened epoxy materials. Observation is a useful method for assessing skin exposure in coating work.