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Background: Isocyanates are used as starting materials of polyurethane (PU) products. They are relatively important occupational skin sensitizers., Objectives: To analyse results of a large isocyanate patch test series of 19 isocyanate test substances and 4,4'-diaminodiphenylmethane (MDA), a marker of 4,4'-diphenylmethane diisocyanate (MDI) hypersensitivity., Methods: Test files were screened for positive reactions in the isocyanate series. Patients with positive reactions were analysed for occupation, exposure and diagnosis., Results: In 2010-2019, 53 patients had positive reactions in the series (16% of 338 patients tested). MDA, the well-established screening substance for MDI allergy, was positive in 30 patients, an in-house monomeric MDI test substance in 23 patients and 3 different polymeric MDI test substances in 19-21 patients. We diagnosed 16 cases of occupational allergic contact dermatitis (OACD) from MDI including 3 pipe reliners. Hexamethylene-1,6-diisocyanate (HDI) oligomers in paint hardeners caused 5 cases of OACD, more cases than 2,4-toluene diisocyanate (TDI; n = 3) and isophorone diisocyanate (IPDI; n = 1) put together., Conclusions: In contrast to previous studies, polymeric MDI test substances were not superior to a monomeric MDI. Pipe reliners may get sensitised not only by epoxy products and acrylates but also by MDI in hardeners of PU pipe coatings. HDI oligomers were the second most important causes of OACD after MDI., (© 2024 The Author(s). Contact Dermatitis published by John Wiley & Sons Ltd.)

Patch testing is the only clinically applicable diagnostic method for Type IV allergy. The availability of Type IV patch test (PT) allergens in Europe, however, is currently scarce. This severely compromises adequate diagnostics of contact allergy, leading to serious consequences for the affected patients. Against this background, the European Society of Contact Dermatitis (ESCD) has created a task force (TF) (i) to explore the current availability of PT substances in different member states, (ii) to highlight some of the unique characteristics of Type IV vs. other allergens and (iii) to suggest ways forward to promote and ensure availability of high-quality patch testing substances for the diagnosis of Type IV allergies throughout Europe. The suggestions of the TF on how to improve the availability of PT allergens are supported by the ESCD, the European Academy of Allergy and Clinical Immunology, and the European Academy of Dermatology and Venereology and intend to provide potential means to resolve the present medical crisis., (© 2024 The Authors. Contact Dermatitis published by John Wiley & Sons Ltd.)

Background: The practical importance of two recently described epoxy hardener allergens-1,3-benzenedimethanamine, N-(2-phenylethyl) derivatives (1,3-BDMA-D) and hydrogenated formaldehyde benzenamine polymer (FBAP)-as occupational allergens remains to be defined., Objectives: To describe patients diagnosed at the Finnish Institute of Occupational Health (FIOH) with positive reactions to 1,3-BDMA-D or FBAP., Methods: We searched FIOH's patch-test files from January 2017 to December 2020 for patients examined due to suspected occupational contact allergy to epoxy compounds. We analyzed the patch-test results and sources of exposure to various epoxy hardeners and focused on occupations, symptoms, and the sources of exposure to 1,3-BDMA-D and FBAP., Results: During the study period, 102 patients were examined at FIOH for suspected occupational contact allergy to epoxy compounds. Of these, 19 (19%) were diagnosed with contact allergy to 1,3-BDMA-D (n = 10) or FBAP (n = 12). The largest occupational group was sewage pipe reliners (n = 8). Seven different hardener products contained FBAP, whereas 1,3-BDMA-D was present in only one hardener used by spray painters., Conclusions: A substantial number of patients with suspected occupational epoxy resin system allergy tested positive to in-house test substances of 1,3-BDMA-D and/or FBAP., (© 2022 The Authors. Contact Dermatitis published by John Wiley & Sons Ltd.)

Contact dermatitis tremendously impacts the quality of life of suffering patients. Currently, diagnostic regimes rely on allergy testing, exposure specification, and follow-up visits; however, distinguishing the clinical phenotype of irritant and allergic contact dermatitis remains challenging. Employing integrative transcriptomic analysis and machine-learning approaches, we aimed to decipher disease-related signature genes to find suitable sets of biomarkers. A total of 89 positive patch-test reaction biopsies against four contact allergens and two irritants were analyzed via microarray. Coexpression network analysis and Random Forest classification were used to discover potential biomarkers and selected biomarker models were validated in an independent patient group. Differential gene-expression analysis identified major gene-expression changes depending on the stimulus. Random Forest classification identified CD47 , BATF , FASLG , RGS16 , SYNPO , SELE , PTPN7 , WARS , PRC1 , EXO1 , RRM2 , PBK , RAD54L , KIFC1 , SPC25 , PKMYT , HISTH1A , TPX2 , DLGAP5 , TPX2 , CH25H , and IL37 as potential biomarkers to distinguish allergic and irritant contact dermatitis in human skin. Validation experiments and prediction performances on external testing datasets demonstrated potential applicability of the identified biomarker models in the clinic. Capitalizing on this knowledge, novel diagnostic tools can be developed to guide clinical diagnosis of contact allergies., Competing Interests: The authors declare no competing interest., (Copyright © 2020 the Author(s). Published by PNAS.)

Background: Colophonium is a common contact allergen that is present not only in household products but also in occupational settings., Objectives: To describe the sources of occupational exposure to colophonium and the occupations at risk of colophonium allergy., Methods: We reviewed patch test files from the years 2002 to 2017 at the Finnish Institute of Occupational Health for patients with allergic reactions to colophonium and abietic acid. We analysed the patch test, occupation and exposure data of 39 patients diagnosed with occupational allergic contact dermatitis (OACD) caused by colophonium., Results: Of the patients examined for suspected occupational dermatitis, 4.6% (n = 118) reacted positively to colophonium. The majority of the OACD patients worked in the wood industry, as machinists, or were involved in soldering or agriculture. The most common occupational sources of exposure were coniferous wood and wood-derived materials, followed by glues, metalworking fluids, and soldering materials. Colophonium is not always mentioned in safety data sheets (SDSs), and the sources of colophonium exposure are often materials for which there are no SDSs., Conclusion: OACD caused by colophonium is quite common and occurs in a variety of occupations. SDSs provide poor information for exposure assessment. Patch testing with the patient's own materials was often useful in establishing the diagnosis., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Contact sensitization is common and affects up to 20% of the general population. The clinical manifestation of contact sensitization is allergic contact dermatitis. This is a clinical expression that is sometimes difficult to distinguish from other types of dermatitis, for example irritant and atopic dermatitis. Several studies have examined the pathogenesis and severity of allergic contact dermatitis by measuring the absence or presence of various biomarkers. In this review, we provide a non-systematic overview of biomarkers that have been studied in allergic contact dermatitis. These include genetic variations and mutations, inflammatory mediators, alarmins, proteases, immunoproteomics, lipids, natural moisturizing factors, tight junctions, and antimicrobial peptides. We conclude that, despite the enormous amount of data, convincing specific biomarkers for allergic contact dermatitis are yet to be described., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Amines in epoxy hardeners are significant causes of occupational allergic contact dermatitis among workers who use epoxy resin systems., Objectives: To describe a novel group of contact allergens: N-(2-phenylethyl) derivatives of the reactive amine 1,3-benzenedimethanamine (1,3-BDMA)., Methods: We describe the clinical examinations and exposure of 6 patients with occupational contact allergy to derivatives of 1,3-BDMA., Results: Of the 6 patients, 4 were spray painters who used epoxy paints, 1 was a floor layer who handled a variety of epoxy coatings, and 1 was a worker in epoxy hardener manufacture. We were able to confirm exposure to epoxy hardeners that contained derivatives of 1,3-BDMA in 5 of the 6 sensitized patients. Despite the close structural resemblance between derivatives of 1,3-BDMA and m-xylylenediamine (MXDA), only 3 patients reacted positively to MXDA. Concomitant contact allergy to diglycidyl ether of bisphenol A resin was seen in 2 of the 6 patients., Conclusions: Because of the lack of a commercially available patch test substance, the diagnosis of contact allergy to derivatives of 1,3-BDMA requires patch testing with either the epoxy hardener product or a hardener ingredient that contains the derivatives of 1,3-BDMA., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI) and MI are common preservatives in industrial and household products and in cosmetics. Occupational contact allergy to MCI/MI or MI has been reported among painters and paint factory workers in particular., Objectives: To retrospectively describe patients with occupational contact allergy to MCI/MI and MI at the Finnish Institute of Occupational Health (FIOH)., Methods: Patch test files and clinical records of patients examined at the FIOH between January 2002 and February 2013 were reviewed to identify the patients., Results: Seventy-two of 1745 patients showed positive reactions to MCI/MI and/or MI. Of these, 36 were occupational cases, and 31 were diagnosed during the second half of the study period. Hairdressers and beauticians, mechanics and repairmen, and machinists were the most significant occupational groups, followed by painters and paint factory workers, and café and restaurant workers., Conclusions: We observed a sixfold increase in the number of occupational cases in the second half of the study period as compared with the first half. Liquid soaps and industrial hand cleansers were common sources of exposure to MCI/MI or MI. A total of 33% of the patients used products without any mention of MCI/MI or MI in safety data sheets or product declarations., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Limonene is widely used as a fragrance substance and solvent in cleansing products. Oxidized limonene is a frequent contact allergen among consumers of cosmetics, personal care products, and scented household cleaning products. Less is known about the sources of occupational exposure and occupational contact dermatitis caused by limonene., Objective: To report 14 patients with occupational contact allergy to limonene., Methods: The patients were examined in 2008-2013. An in-house preparation of oxidized limonene was patch tested as 3% and 5% in petrolatum from 2008 to August 2010, and after this as 3%, 1% and 0.3% pet. From 2012 onwards, a commercial test substance of limonene hydroperoxides was also used. We assessed the patients' occupational and domestic exposure to limonene., Results: Occupational limonene allergy was observed in workers who used limonene-containing machine-cleaning detergents and hand cleansers, and in workers who used limonene-containing surface cleaners and dishwashing liquids similar to those used by consumers. In 3 cases, the occupational limonene allergy resulted from work-related use of limonene-containing, leave-on cosmetic products., Conclusions: Limonene is a frequent occupational sensitizer in hand cleansers and cleaning products. Occupational limonene contact allergy may also be caused by exposure to cosmetic products scented with limonene., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)