Contact allergy to gold is frequently observed in patch testing, although with low clinical relevance. Nickel allergy, in contrast, is common, clinically relevant, and nickel release from jewellery remains a regulatory concern. Standardised artificial sweat tests show no detectable gold release from gold-containing jewellery. To assess surface composition and the release of nickel and gold from gold-plated earrings under clinically relevant biochemical conditions. Ten pairs of low-cost gold-plated earrings were analysed by scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS) and X-ray fluorescence. Metal release was assessed using a cysteine-modified artificial sweat solution at 30°C for 168 h. Gold and nickel concentrations were quantified by inductively coupled plasma mass spectrometry. Nickel release was detected in 10/10 earrings (median: 2.1 μg/cm2, range: 0.00032-10.0) frequently exceeding the EU regulatory limit. Gold release was detected in 4/10 earrings (median: 0.00092 μg/cm2, range: 0.00041-0.21). Gold was identified by cross-sectional SEM/EDS in a subset of components (6/20) but was not detected by top-down XRF analysis. Nickel release from gold-plated earrings was widespread and often exceeded regulatory limits, indicating that gold plating does not reliably prevent nickel exposure. Gold release occurred in some earrings, but the clinical relevance remains uncertain.

1,3-Diphenylguanidine (DPG) is a known contact sensitiser and rubber vulcaniser. A retrospective audit was performed including 2675 patients tested to 1% DPG in petrolatum between 2002 and 2024. The MOAHLFA index of those with allergic contact dermatitis (ACD) was compared to the remainder of the patch test clinic population. Temporal changes in the prevalence of contact allergy and ACD to DPG were assessed. 50 (1.9%) patients had positive reactions to DPG on patch testing, with 31 (62% of positive reactions) diagnosed with ACD. In those with ACD, there was a significantly higher proportion of men (64.5% vs. 30.6%, p < 0.001), more occupational cases (41.9% vs. 17.7%, p < 0.001), more cases with hand dermatitis (64.5% vs. 33.1%, p < 0.001), more cases aged over 40 years (71.0% vs. 53.2%, p = 0.048), and fewer cases with face dermatitis (9.7% vs. 25.5%, p = 0.043). The most common exposure sources were gloves and shoes, with the four most recent cases involving polyisoprene (PI) gloves. However, information regarding DPG in shoes was lacking, and some patients reacted to multiple haptens, making it unclear as to the primary culprit. DPG causes occupational ACD in especially in healthcare workers (HCW), with recent cases involving exposure to PI gloves.

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. 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. 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. 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. 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.

Artificial intelligence programs were not used in the provision of this article. The authors declare no conflicts of interest. Research data are not shared. Table S1: MOAHFLA (% male patients; % occupational dermatitis; % with atopic dermatitis; % hand dermatitis; % leg dermatitis; % face dermatitis; % age > 40 years) characteristics for individuals with alkyl glucoside (AG) allergic contact dermatitis (ACD) compared to those tested to AG without a relevant reaction from a retrospective study from 1st January 2016 to 31st December 2024. Analysis was made with χ2 test with Yate's continuity correction unless otherwise specified. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Atopic dermatitis is a common chronic inflammatory skin condition. Data on contact sensitization in adults with atopic dermatitis remain limited. To investigate the prevalence of contact sensitization in adults with and without AD: PATIENTS/METHODS: A monocentric, retrospective study analysed 8967 adults (≥ 16 years) patch-tested at the University of Padua (1997-2018). Patients were tested with a standard baseline series (44 allergens). 540 (6.0%) patients had atopic dermatitis; 8273 (92.3%) did not; 154 (1.7%) had missing/uncertain AD status and were excluded from subgroup comparisons. Contact sensitization prevalence was 65.4% in both groups. Adults with atopic dermatitis showed significantly higher rates of sensitization to formaldehyde (p < 0.00001), HICC (hydroxyisohexyl 3-cyclohexene carboxaldehyde) (p = 0.04), thiuram mix (p = 0.03), and carba mix (p = 0.004). Non-AD patients showed significantly higher sensitization to nickel (p = 0.001), disperse blue (p = 0.006), and primin (p = 0.05). Nickel was the most frequent allergen (21.30% AD; 27.59% non-AD). Higher prevalence of contact sensitization to specific allergens in adults with atopic dermatitis suggests a tailored patch test series including allergens from rubber, fragrance, and preservative groups. The lower prevalence of metal sensitization in patients with atopic dermatitis may reflect distinct immunological mechanisms that warrant further research.

The author declares no conflicts of interest. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.

The authors declare no conflicts of interest. Research data are not shared.

Hair cosmetic products contain various chemicals which are partly potent contact sensitizers. These may cause occupational hand eczema in hairdressers, but also scalp and face dermatitis in consumers. To (i) highlight differences between the spectrum of occupational and non-occupational exposure reflected in sensitization, and (ii) correlate trends in the last decades with regulatory interventions (or the lack thereof). Patch test and clinical data collected by the IVDK (https://www.ivdk.org) between 01/1995 and 12/2020 were subjected to a pooled re-analysis. Age-stratified sensitization prevalences in female hairdressers and consumers, respectively, were calculated for 2-yearly intervals spanning the study period. Log-binomial regression models were employed to estimate the association between contact allergy and (i) subgroup (hairdresser vs. consumer), (ii) a 3-level age category, and/or (iii) time period, respectively. Hair dyes were the most frequent sensitizers in hairdressers and consumers; however, there was a marked increase in (particularly the young) consumers. Pyrogallol had been banned in 1992 but still elicited positive patch test reactions even in the young. Hydroquinone, banned in 2013 in dyes, showed no decline in sensitization prevalence. Glyceryl thioglycolate has been withdrawn and later banned in Germany since around 1995, which caused contact allergy prevalence to drop to almost zero in the youngest age group, largely until today. As a limitation, putatively differing selection for patch testing render prevalences difficult to compare between hairdressers and consumers. The importance of hair dye allergy is evident, needing continued efforts to increase product safety from the manufacturing and regulatory side. The potential of (self-)regulatory intervention is well illustrated by the decline of contact allergy to glyceryl thioglycolate.