Occupational Allergic Contact Dermatitis to Formaldehyde Released by Work Clothes

Formaldehyde (FA) is one of the oldest and still widely used preservatives. It is a common allergen and has been included in the standard series since the 1930s [1]. FA is commonly found in consumer products such as cosmetics, household detergents, pharmaceuticals, industrial products [2] and in occupational exposures such as protective gloves [3]. FA can also be released from clothing [4]. At the time of the investigation, the patient was a 54-year-old man with no history of atopy. He had been working in the home health care service for more than 20 years without any skin problems. However, due to changes in hygiene practices during the COVID-19 pandemic, work clothes were introduced instead of the wearing of his own civil clothes. Since the introduction of the new garment (a set of trousers and a shirt in 50% cotton/50% polyester, made in Laos) the patient had started to experience itch on the skin exposed to the garment, that is, the trunk, upper arms and legs. The itch was strongly related to wearing the new garment at work and decreased during weekends and holidays. At the time of the investigation, the patient was clear of symptoms from the skin, and he could not give an objective description of any efflorescence. The patient was patch-tested with the Swedish baseline series [5], textile series, and textile dye mix series. The patch tests were occluded for 48 h, and patch test readings were performed according to the ICDRG and ESCD guidelines [6, 7] on day 3 and day 7. Patch testing was performed using Finn Chamber Aqua (Chemotechnique Diagnostics, Vellinge, Sweden). Twenty milligrams of petrolatum preparations (40 mg/cm2) or 15 μL of liquid preparations (31 μL/cm2) were applied [8]. At the patch test reading on day 3, the patient showed a positive reaction to FA (2% aq) in the Swedish baseline series and to multiple FA-related chemicals in the textile series. He had a weak positive reaction to chromium that was not assessed as relevant, and no contact allergies for textile dyes. He was further tested with a dilution series of FA, in which he had strong positive reactions to the highest concentrations, successively tapering down (Table 1). The release of FA from the new, unwashed work clothes and old multiply washed work clothes was analysed by the chromotropic acid method [9]. The analysis of the new work clothes indicated a high release of FA with darkly coloured reagent, whereas no release of FA was indicated from the old work clothes. We interpreted the patient as suffering from an OACD to FA in his new work clothes, based on the aggregated information and test results. FA-releasing preservatives are widely used, and the patient might have been sensitised to them elsewhere, but he was not aware of any excessive exposure to FA in the past, and he had never had any skin problems before. With time and multiple washings of the garment, the itch decreased according to the patient's experience, in line with the results of the analysis of old and new garments, which revealed the release of FA only in the new work clothes. In this case, the FA is likely to be present after release from durable chemical finishes that are often used on textiles to increase strength, prevent shrinking, and resist wrinkling [4]. Our patient was tested negative to all FA-releasing chemicals in Chemotechnique Diagnostics textile series. FA-induced ACD associated with clothing was reported in the 1930s, and since then, case reports have continued to be described. Studies have shown that unwashed clothing has a higher concentration of unbound FA [10]. This case is unique since it describes an OACD to FA in a patient group that is not very well studied, health care workers in the domestic health care service, working in the homes of the care recipients. The exposure of health care workers in this group differs from the exposure of health care workers at institutions and hospitals. The patient's employer was informed of the investigation findings, and the patient was spared from using new unwashed work garments. At follow-up, the patient was free of symptoms. Tina Lejding: writing – original draft, investigation, project administration, data curation. Anna Kiuru: methodology, validation, writing – review and editing, project administration, data curation, supervision. Ola Bergendorff: methodology, validation, writing – review and editing, project administration, data curation, supervision. The authors declare no conflicts of interest.