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Introduction: Shellac is a known allergen present mainly in cosmetics used on the eyelids and lips, although new sources of exposure have recently been described. Our objective was to assess the use of shellac as a contact allergen in Spain and the clinical profile of patients allergic to shellac., Methods: This retrospective cross-sectional study included patients patch tested for shellac between 2018 and 2021 from the Spanish Registry of Contact Dermatitis and Cutaneous Allergy (REIDAC)., Results: A total of 980 patients were patch tested for shellac (20% in ethanol), and 37 (3.77%, 95% confidence interval [CI], 2.58-3.97%) showed positive results. Most of these patients were tested for shellac due to a suspicion of cosmetic contact dermatitis. Seven patients with present relevance were found, five with relation to cosmetics, and the other two with an occupational background of food handling. The reaction index for shellac was 0.51 and the positivity ratio was 67.56% (95% CI, 52.48-82.65%)., Conclusions: Shellac appears to be a prevalent allergen in patients with suspected contact dermatitis related with cosmetics or foodstuff. However, further studies are needed to validate its use in other patients., (Copyright © 2023 AEDV. Publicado por Elsevier España, S.L.U. All rights reserved.)

Introduction: Shellac is a known allergen present mainly in cosmetics used on the eyelids and lips, although new sources of exposure have recently been described. Our objective was to assess the use of shellac as a contact allergen in Spain and the clinical profile of patients allergic to shellac., Methods: This retrospective cross-sectional study included patients patch tested for shellac between 2018 and 2021 from the Spanish Registry of Contact Dermatitis and Cutaneous Allergy (REIDAC)., Results: A total of 980 patients were patch tested for shellac (20% in ethanol), and 37 (3.77%, 95% confidence interval [CI], 2.58-3.97%) showed positive results. Most of these patients were tested for shellac due to a suspicion of cosmetic contact dermatitis. Seven patients with present relevance were found, five with relation to cosmetics, and the other two with an occupational background of food handling. The reaction index for shellac was 0.51 and the positivity ratio was 67.56% (95% CI, 52.48-82.65%)., Conclusions: Shellac appears to be a prevalent allergen in patients with suspected contact dermatitis related with cosmetics or foodstuff. However, further studies are needed to validate its use in other patients., (Copyright © 2023 AEDV. Publicado por Elsevier España, S.L.U. All rights reserved.)

Background: Methyldibromo glutaronitrile (MDBGN) was one of the most frequent and relevant allergens found in patch testing at the beginning of this century. In 2008, this preservative was banned from cosmetics in Europe and ever since the prevalence of contact allergy to MDBGN has progressively decreased. Despite that gradual decline, MDBGN is still patch-tested in most baseline series. This study assessed the frequency of MDBGN sensitization, epidemiological characteristics of allergic patients, and the relevance of positive patch tests in a nationwide Spanish registry (REIDAC)., Patients and Methods: We evaluated consecutively patch-tested patients in all participating centres. Using these data, we calculated the proportion of patients with positive patch tests to MDBGN from June 2018 to June 2020 and evaluated the relevance of the positive patch tests., Results: One hundred and fourteen out of 5072 (2.24 %) tested patients were sensitized to MDBGN. Clinical current relevance was confirmed in only one case., Conclusion: Although the frequency of contact allergy to MDBGN remains high, no clinical significance was found in most of these patients (5072 tests needed to obtain one relevant positive result). The clinical usefulness of this allergen seems weak and its continued inclusion in the European baseline series is questionable., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objectives: To analyze trends in the prevalence of contact sensitization to p-phenylenediamine between 2004 and 2014, taking into consideration that the concentration of this product in cosmetics was regulated in 2009. To explore risk factors for contact allergy to p-phenylenediamine., Material and Methods: Retrospective observational study of patients suspected of having contact dermatitis from allergy to p-phenylenediamine during the years between 2004 and 2015 in 8 tertiary level hospitals. The patients underwent patch testing (TRUE-test) with the standard series of the Spanish Research Group on Contact Dermatitis and Skin Allergies. This series included p-phenylenediamine 1%. We followed international recommendations for the statistical analysis of data related to contact allergies., Results: Three hundred eighty-six out of 9341 patients (4.1%) had positive reactions to p-phenylenediamine. The prevalence tended to decrease in the early years (2004-2007) and then leveled off at around 4%. Risk factors for developing contact dermatitis from p-phenylenediamine were sex, age over 40 years, multiple sensitivities, and profession, notably workers in hair salons and those who handle rubber and plastics., Conclusions: The prevalence of p-phenylenediamine allergy remains high among patients with contact eczema. Risk factors for p-phenylenediamine contact allergy are consistent with previous reports., (Copyright © 2019 AEDV. Publicado por Elsevier España, S.L.U. All rights reserved.)