The safety of using ethanol-based products for hygienic hand disinfection in healthcare workers is controlled by restricting air levels. This raises the question of whether these workers are sufficiently protected against potential dermal absorption. The study aim was to determine the contribution of the dermal route to the total uptake of ethanol. A laboratory-controlled study of 25 sequential alcohol-based-hand-rubs (ABHRs) with subsequent intermediate glove use was conducted in seven healthcare workers. Two exposure conditions were compared: hands and forearms placed inside a laboratory fume hood preventing inhalation (skin-only condition) and the same procedure but outside the fume hood to allow inhalation (native condition). The hand hygiene product contained 84

This is the second part of a two-part narrative review of contact allergy and allergic contact dermatitis to alkyl glucosides (AGs), presenting patient demographics, products causing allergic contact dermatitis, patch test considerations, co-/cross-reactions, and the presence of AGs in cosmetics and other products. There are strong indications that atopic patients, or at least those with a history of atopic dermatitis, have an increased risk of becoming sensitized to AGs. This results in higher prevalences of sensitization to AGs in pediatric populations. Female sex does not appear to be a risk factor. The sites most commonly affected by allergic contact dermatitis are the face (+/- neck and scalp), hands, and "generalized." Occupational allergic contact dermatitis from AGs does not occur frequently and usually manifests as hand dermatitis from shampoos (in hairdressers) and hand cleansers. Cosmetics are by far (>80%) the most common products responsible for allergic reactions to AGs. Other culprit products include household and industrial cleansers, topical medications, wound foam dressings, and antiseptic products. Patch testing with commercial decyl glucoside (5% pet.) and lauryl glucoside (3% pet.) results not infrequently in dubious (?+) and irritant reactions. There are concerns that some weak "allergic" reactions may actually be false-positive. Frequent coreactivity between AGs may be caused by cross-reactions, concomitant sensitization due to mixed alkyl chain compositions, common allergenic impurities, and overlapping composition of patch test materials. Cosmetics with the highest prevalences of one or more AGs are cleansing products for babies and children.

ABSTRACT Background Allergens are periodically added to the European Baseline Series (EBS) to audit their value in consecutive patch testing. Objectives To present results of audit allergens tested in consecutive patients in 54 departments in 13 European countries during 2021 and 2022. Methods Anonymized or pseudonymized individual data, and partly aggregated data on patch test rest results and their clinical relevance were prospectively collected and centrally pooled and analyzed. Results In 2021 and 2022, 18 832 patients were patch tested with the EBS, and 2860 with the TRUE Test baseline series (supplemented with some missing EBS allergens). Of these patients, 17 359 were additionally tested with one or more of the 19 audit allergen preparations examined. Apart from the terpene hydroperoxides (OOH) which yielded the highest numbers of positive patch test reactions (linalool‐OOH 1% pet.: 7.65 (7.09%–8.23%) [95% CI] and limonene‐OOH 0.3% pet. 6.78 (6.26%–7.32%)), positive reactions were most often seen to benzisothiazolinone (3.71 (3.3%–4.15%)), sodium metabisulfite (3.49 (3.14%–3.88%)), Evernia furfuracea (tree moss, 1.79 (1.4%–2.26%)), and decyl and lauryl glucoside, at 1.49 (1.25%–1.76%) and 1.26 (1.05%–1.51%), respectively. The other allergens yielded around 1% or fewer positive patch test reactions. Clinical relevance varied, with Evernia furfuracea , 2‐bromo‐2‐nitropropane‐1,3‐diol and terpene hydroperoxides considered relevant in more than 2/3 cases, while for other frequent sensitizers benzisothiazolinone and sodium metabisulfite, relevance could be confirmed in half of the cases or less often. Conclusions The current results, along with other published data, will serve to inform decisions concerning possible revision of the EBS, considering frequency of positive reactions, their clinical relevance and the overall reaction profile of each of the allergens.

Pruritus is a common and distressing symptom among dialysis patients, yet its underlying mechanisms remain incompletely understood. Most previous research has focused on systemic inflammatory markers, while little is known about local skin alterations contributing to pruritus. This study aimed to characterize skin biomarker profiles in dialysis patients with pruritus, in comparison with dialysis patients without pruritus and healthy controls, and to explore differences between pruritic and non-pruritic skin sites. In this multi-center cross-sectional exploratory study, stratum corneum samples were obtained using the tape-stripping method from 91 participants (67 dialysis patients and 24 healthy controls). Biomarkers were quantified, and adjusted linear and logistic (mixed) models were used to assess group differences and skin site variations. Dialysis patients with pruritus exhibited a significantly elevated IL-1RA/IL-1α ratio and reduced IL-18 levels compared to non-pruritic patients. There was also a strong indication of concomitant increases in IL-1RA and IFN-β in pruritic skin. Across all dialysis patients, IL-8, CCL17, and CXCL10 levels were significantly lower than in healthy controls, independent of pruritus status. Dialysis patients with pruritus demonstrate distinct alterations in skin immune profiles suggestive of localized inflammation and potential involvement of the opioid pathway. These findings provide new insights into the inflammatory mechanisms underlying pruritus in this population and may inform the development of targeted, personalized therapies.

BACKGROUND:Allergens are periodically added to the European Baseline Series (EBS) to audit their value in consecutive patch testing. OBJECTIVES:To present results of audit allergens tested in consecutive patients in 54 departments in 13 European countries during 2021 and 2022. METHODS:Anonymized or pseudonymized individual data, and partly aggregated data on patch test rest results and their clinical relevance were prospectively collected and centrally pooled and analyzed. RESULTS:In 2021 and 2022, 18 832 patients were patch tested with the EBS, and 2860 with the TRUE Test baseline series (supplemented with some missing EBS allergens). Of these patients, 17 359 were additionally tested with one or more of the 19 audit allergen preparations examined. Apart from the terpene hydroperoxides (OOH) which yielded the highest numbers of positive patch test reactions (linalool-OOH 1% pet.: 7.65 (7.09%-8.23%) [95% CI] and limonene-OOH 0.3% pet. 6.78 (6.26%-7.32%)), positive reactions were most often seen to benzisothiazolinone (3.71 (3.3%-4.15%)), sodium metabisulfite (3.49 (3.14%-3.88%)), Evernia furfuracea (tree moss, 1.79 (1.4%-2.26%)), and decyl and lauryl glucoside, at 1.49 (1.25%-1.76%) and 1.26 (1.05%-1.51%), respectively. The other allergens yielded around 1% or fewer positive patch test reactions. Clinical relevance varied, with Evernia furfuracea, 2-bromo-2-nitropropane-1,3-diol and terpene hydroperoxides considered relevant in more than 2/3 cases, while for other frequent sensitizers benzisothiazolinone and sodium metabisulfite, relevance could be confirmed in half of the cases or less often. CONCLUSIONS:The current results, along with other published data, will serve to inform decisions concerning possible revision of the EBS, considering frequency of positive reactions, their clinical relevance and the overall reaction profile of each of the allergens.

BACKGROUND:Propolis, Myroxylon pereirae resin (balsam of Peru), and colophonium are complex botanical materials that frequently co-react when patch tested. Detailed knowledge of their compositions may help explain the co-reactivity pattern and identify the haptens responsible for positive patch tests. OBJECTIVE:To study the compositions of propolis, M. pereirae resin, and colophonium used for patch testing and assess whether they contain identical ingredients. METHODS:The ingredients of 3 samples of propolis, 2 of M. pereirae resin and 2 of colophonium used for preparing patch test preparations by Chemotechnique and SmartPractice (brand Allergeaze) were analyzed using gas chromatography-mass spectrometry. RESULTS:Major ingredients in Brazilian propolis were non-volatile fatty materials; in Chinese propolis tectochrysin, pinostrobin, pinocembrin, and p-vinylguaiacol; in M. pereirae resin benzyl benzoate, benzyl cinnamate and nerolidol; in colophonium Chemotechnique isoabienol, β-caryophyllene, sandaracopimarinal, sandaracopimarinol and longifolene; in colophonium Allergeaze lupeol acetate, longifolene, sandaracopimarinol, abietinal and isoabienol. Only 11 chemicals were present in 2 materials, none in all 3. CONCLUSIONS:Very few identical chemicals were found in propolis, M. pereirae resin, and colophonium. The results do not support the notion that the frequently observed co-reactivity to these complex natural materials can be explained by identical chemicals detected in this study.

Background In patients with contact allergy to Chinese propolis, co-reactivity to the four fragrance markers present in the European baseline series (Myroxylon pereirae resin [balsam of Peru], colophonium, fragrance mixes 1 and 2) has been well documented. The co-reactivity pattern of Brazilian propolis has not yet been sufficiently analysed.Objectives To investigate co-reactivity patterns to the fragrance markers and to the fragrances linalool hydroperoxides and limonene hydroperoxides in patients reacting to Chinese and Brazilian propolis.Materials and Methods Retrospective analysis of patch test results in a cohort of 701 patients tested with Chinese propolis and a cohort of 2509 individuals tested with Brazilian propolis investigated in Amsterdam during 2019-2025.Results For Chinese propolis, we found significant associations with the four fragrance markers and limonene hydroperoxides. For Brazilian propolis, there were significant associations with all four fragrance markers and both limonene and linalool hydroperoxides. There were indications of a closer relationship between Brazilian propolis and fragrances than of Chinese propolis and fragrances, possibly resulting in many more positive patch test reactions to the Brazilian variety.Conclusions Significant co-reactivity to fragrances and -marker(s) was confirmed for patients allergic to Chinese propolis and established for patients with positive patch tests to Brazilian propolis.

The present guideline summarizes all aspects of patch testing for the diagnosis of contact allergy in patients suspected of suffering, or having been suffering, from allergic contact dermatitis or other delayed-type hypersensitivity skin and mucosal conditions. Sections with brief descriptions and discussions of different pertinent topics are followed by a highlighted short practical recommendation. Topics comprise, after an introduction with important definitions, materials, technique, modifications of epicutaneous testing, individual factors influencing the patch test outcome or necessitating special considerations, children, patients with occupational contact dermatitis and drug eruptions as special groups, patch testing of materials brought in by the patient, adverse effects of patch testing, and the final evaluation and patient counselling based on this judgement. Finally, short reference is made to aspects of (continuing) medical education and to electronic collection of data for epidemiological surveillance.

Background Breast Implant Illness (BII) is characterized by systemic and local symptoms in a subset of women with silicone breast implants, but its pathophysiology remains unclear. Mast cell activation has been proposed as an underlying mechanism, yet systemic mast cell–related biomarkers have not been systematically evaluated in this context. This study aimed to assess whether explantation is associated with changes in serum tryptase and total IgE in women with BII. Methods Seventy-one women with BII at a tertiary outpatient clinic provided paired blood samples before and after explantation (median interval, 8 months). Serum tryptase was measured by enzyme-linked fluorescence assay and total immunoglobulin E (IgE) by ImmunoCAP/EliA. Paired changes were analyzed in the overall cohort and in baseline-defined subgroups, including allergy status and pre-explantation IgE >100 kU/L. Results In the full cohort, neither serum tryptase nor total IgE changed significantly after explantation (median differences: +0.09 ng/mL and –1.2 kU/L, respectively; both p > 0.1). Among 13 women with high baseline IgE (>100 kU/L), nine showed declines (median –118 kU/L), whereas tryptase levels remained unchanged and within normal limits. Of five women with elevated baseline tryptase (>11.4 ng/mL), three showed decreases after explantation, but only one normalized. Conclusions These findings show no evidence of explantation-associated changes in serum tryptase in women with Breast Implant Illness. Total IgE levels showed no consistent change overall, although heterogeneous post-explantation IgE changes were observed in a small subgroup with elevated baseline IgE. Mast cell involvement in BII cannot be excluded, as local mast cell activity and other mast-cell–derived mediators were not assessed.

This study aims to investigate the underlying mechanisms and triggers of delayed-onset inflammatory responses DIRs after hyaluronic acid (HA) fillers injections. The literature review included articles on DIRs following HA filler treatments and identified immunological triggers, bacterial contamination, and filler degradation as key factors contributing to DIRs. Additionally, patient data were analyzed from patients treated for DIRs and showed possible immune activation events prior to DIRs included flu-like symptoms. This study underscores the complexity of DIRs following HA filler treatments and the need for transparency from manufacturers. Comprehensive ingredient data are crucial to better understand DIRs and ensure patient safety.

Background Cosmetics have been suggested as sources of exposure in patients with positive patch tests to propolis. It has also been proposed that beeswax in cosmetic products may cause allergic contact dermatitis due to contamination with propolis.Objectives To assess how often propolis is listed in cosmetics and to review evidence on the propolis-beeswax relationship, including whether residual propolis in beeswax can elicit dermatitis in propolis-sensitised individuals.Materials and Methods Market survey of ingredient lists for 500 cosmetics and a literature review on allergy to beeswax and its association with propolis allergy.Results None of the 500 cosmetics contained propolis. Evidence on the propolis-beeswax relationship is inconsistent, but occasional co-reactivity is reported.Conclusions Based on the available evidence, propolis is not or only rarely used in conventional cosmetics on the European market and is therefore unlikely to be a relevant exposure source for patients with positive patch tests to propolis. Reactions to beeswax in propolis-sensitised individuals from residual propolis cannot be fully excluded but appear uncommon and mainly involve allergic contact cheilitis from lip balms. Within the scope of the present data, patients with positive patch tests to propolis do not need to avoid all cosmetics containing beeswax.

BACKGROUND:Allergic contact dermatitis from hearing aid ear moulds is infrequently reported. OBJECTIVES:To identify cases of allergic contact dermatitis from hearing aid moulds in a cohort of patients investigated between 2022 and 2025 at Amsterdam University Medical Center. MATERIALS AND METHODS:Retrospective analysis of patients referred for investigation of suspected allergic reactions to ear moulds. RESULTS:Of 20 patients with suspected allergic reactions to ear moulds, 8 (40%) had positive patch tests to (meth)acrylates considered to be probably relevant. All eight reacted to tetrahydrofurfuryl methacrylate, of whom five had a positive reaction to this hapten only. The other three all co-reacted to isobornyl acrylate and 1,6-hexanediol diacrylate. None had positive patch tests to hydroxyethyl methacrylate. CONCLUSIONS:There are strong indications that tetrahydrofurfuryl methacrylate and isobornyl acrylate are relevant contact allergens present in hearing aid ear moulds. Hydroxyethyl methacrylate did not identify a single case of contact allergy to these materials.

Introduction:Tattooing is common in many populations, yet population-based data on side effects remain limited. We aimed to describe the occurrence of self-reported acute- and delayed-onset side effects following tattooing and investigate individual and tattoo-related determinants in a Swedish population. Methods:The Swedish Tattoo and Body Modifications Cohort includes 13 049 participants, of whom 2633 reported having at least one tattoo and constituted the study sample. In 2021, participants reported predefined acute (within 1 month) and delayed (after 1 month) side effects following tattooing using a structured questionnaire. Information on educational attainment and yearly disposable income was obtained through linkage to national registers. Multivariable logistic regression was used to identify determinants of reporting any acute- and delayed-onset side effects. Results:Overall, 40% of participants reported at least one acute-onset side effect and 10% reported a delayed-onset side effect following tattooing. A larger tattooed body surface area (>5 hand palms), compared with <1 hand palm, was associated with higher odds of both acute- and delayed-onset side effects (OR 1.81, 95% CI 1.13 to 2.90 and OR 2.06, 95% CI 1.04 to 4.10, respectively). Use of coloured inks, compared with black ink only, was also associated with increased odds of side effects. Acute-onset side effects were associated with younger age, a low-melanin, highly photoreactive skin phenotype, cosmetic tattooing and more tattoo sessions, whereas delayed-onset side effects were most strongly associated with prior acute-onset reactions (OR 8.17, 95% CI 5.45 to 12.20, compared with no acute-onset side effects). Healthcare-seeking for delayed-onset side effects was uncommon. Conclusions:Acute- and delayed-onset side effects following tattooing were common and associated with individual characteristics and tattoo-related factors. Delayed-onset side effects were strongly associated with prior acute-onset reactions, while healthcare-seeking was uncommon. These findings indicate that a substantial proportion of tattoo-related side effects never reach the healthcare system, highlighting the importance of population-based studies for assessing their occurrence and determinants.

This is Part 1 of a 2-part narrative review of contact allergy and allergic contact dermatitis (ACD) to alkyl glucosides. It discusses the nature of alkyl glucosides (mainly decyl, lauryl, cetearyl, and coco-glucoside), their properties and applications, results of patch testing in routine testing and in groups of selected patients, and presents all reported case series and case reports of ACD to decyl and lauryl glucoside. The alkyl glucosides are nonionic surfactants that are produced by the reaction of glucose with fatty alcohols and that are increasingly being used in cosmetics. This class of surfactants and emulsifiers has a low potential for irritation and favorable ecological characteristics, being manufactured from renewable sources and being completely biodegradable. Alkyl glucosides are chemically stable and hardly protein-reactive; they do not contain chemically reactive sites or strongly polarized structures. Therefore, they were not predicted to have allergenic potential. Yet, they can induce contact sensitization, which is increasingly recognized. Currently, decyl glucoside has a rate of 2.4% positive reactions in routine testing in the United States. Most positive patch test reactions have current relevance, in >80% from their presence in personal care products. Part 2 will discuss patient demographics (gender and age, atopic diathesis, distribution of dermatitis, occupational contact dermatitis), products causing ACD, patch test considerations, co-/cross-reactions between alkyl glucosides and nonrelated haptens, and the presence of alkyl glucosides in cosmetics and other products.

Introduction:Due to ultraviolet radiation (UVR) exposure at work, outdoor workers face a higher risk of keratinocyte carcinoma (KC) than indoor workers. This study evaluates the short-term effectiveness of a sun-safety risk communication toolbox aimed to increase sun-safety behavior among male outdoor workers. Methods:This parallel-controlled, non-randomized study included outdoor construction and arboricultural workers, recruited from five companies. Twenty-eight workers were assigned to the intervention group, where they received a preventive toolbox, while 26 workers were assigned to the control group. The toolbox included information on UVR health risks and preventive measures, as well as sunscreen provision. The primary outcome was internal UVR exposure, measured by the relative cis-urocanic acid (cUCA) levels in the stratum corneum (SC). SC samples were taken from two skin sites (cheek and neck) at baseline and 6 weeks. Secondary outcomes included sun-protective behavior, workplace encouragement, knowledge and attitude/motivation, all assessed using questionnaires. Results:A difference in cUCA was found between groups with lower cUCA at the cheek (-0.065 (95% CI: -0.101 to -0.029)) and neck location (-0.032 (95% CI: -0.068-0.004)) for the intervention group. Reported sunscreen use significantly improved in the intervention compared with control group (difference between group (11.01 (95% CI: 2.04-20.10)). For other secondary outcomes no statistical differences between groups were found. Conclusion:The toolbox intervention led to a reduction of internal UVR exposure, consistent with a self-reported increase in sunscreen use, compared to no intervention. Future research should focus on the longer-term preventive effects of this type of toolbox following further development and evaluation.