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Introduction: Leather has been a significant source of chromium (Cr) allergy in Denmark since the 1990s. More recently, cobalt (Co) allergy has been identified in leather as a source of allergic contact dermatitis., Objectives: To measure Cr and Co levels in Danish leather goods., Methods: A total of 87 leather samples were collected, all tanned in Europe. Handheld X-ray fluorescence (XRF) device was used to screen for the presence of Cr and Co. The 20 leather samples with the highest concentrations of Co and Co were tested using International Organization for Standardization (ISO)-standards., Results: XRF analysis showed Cr in 78/87 (83.9%) samples and Co in 52/87 (59.7%), with average concentrations of 41 mg/kg (range: 0.0-77 mg/kg) and 0.22 mg/kg (range: 0.0-2.9 mg/kg), respectively. ISO 10195 and 17 075-1 testing identified Cr (VI) in 7 out of 20 samples (1.4; 0.3-4.2 mg/kg), while ISO 17072-1 detected Co in 6 of 20 samples, averaging 3.95 mg/kg (range: 0.22-7.9 mg/kg)., Conclusion: Most leather samples contained Cr, which was expected, while Cr (VI) was detectable in seven out of twenty tested samples but only detected in one product above the regulatory limit of 3 mg/kg. A potentially significant concentration was found for Co., (© 2024 The Author(s). Contact Dermatitis published by John Wiley & Sons Ltd.)

Background: The international classification of diseases, 10th revision (ICD-10) includes several unvalidated diagnostic codes for hand eczema (HE). Knowledge is sparse on HE patient characteristics., Objectives: To validate selected HE ICD-10 codes in the Danish National Patient Registry (DNPR) and describe disease characteristics, lifestyle factors and medication use in adult HE patients., Methods: Nineteen HE ICD-10 codes were selected and validated based on patient charts. Five cohorts were constructed based on the diagnostic code, DL30.8H (HE unspecified), in the DNPR: (i) patients with DL30.8H code (n = 8386), (ii) patients with DL30.8H code, but without atopic dermatitis (AD) (n = 7406), (iii) sex- and age-matched general population (n = 8386) without HE. Two additional cohorts nested in the DNPR included participants from the Danish Skin Cohort, (iv) patients with DL30.8H code but without AD (n = 1340) and (v) general population cohort (n = 9876)., Results: ICD-10 codes revealed positive predictive values ≥90% except irritant contact dermatitis (unspecified) (79.7%) and hyperkeratotic hand and foot eczema (84.1%). HE patients were most often women, middle-aged or older, of Danish ethnicity, had an atopic medical history and were smokers. Topical corticosteroid prescriptions were almost doubled in HE cohorts compared to general populations., Conclusion: We validated several HE ICD-10 codes and identified important HE patient characteristics., (© 2023 The Authors. Contact Dermatitis published by John Wiley & Sons Ltd.)

Background: Rubber accelerators are used in the production of rubber gloves and may cause contact allergy., Objectives: To estimate long-term trend and prevalence of contact allergy to rubber accelerators for a 30-year period in Denmark, high-risk occupations, and exposures., Methods: Data from all patients with contact dermatitis consecutively patch tested at the department of Skin and Allergy Gentofte hospital with the rubber accelerators from the European baseline series (EBS) from 1990 to 2019, were analysed. Further, patients under suspicion of rubber accelerator contact allergy were additionally patch-tested with rubber accelerators from the specialised rubber series from 2005 to 2019 and these were additional extracted., Results: The overall prevalence of contact allergy to one or more of the rubber accelerators from the EBS series was 2.7% with a significant decline in the first 12-years, followed by a stable frequency in the past 18-years. Associations with occupational contact dermatitis, hand dermatitis, and leg/foot dermatitis were found. Wet-work occupations were most often affected and gloves the most frequent exposure., Conclusions: Contact allergy to one or more of the rubber accelerators from the EBS is frequent and has been unchanged for several decades, which calls for prevention., (© 2023 The Authors. Contact Dermatitis published by John Wiley & Sons Ltd.)

Background: Allergic contact dermatitis (ACD) in the eye region caused by topical eye medications is difficult to diagnose and may be overlooked., Objective: To study the characteristics and causative agents in patients with ACD caused by topical eye medications in a Danish tertiary dermatology department., Methods: A retrospective study of 318 patients, patch tested between 2013 and 2021 due to suspected ACD to topical eye medications. All patients were tested with a locally developed eye medication series, some were additionally tested with suspected eye medications. Medical records were studied in patch test positive patients., Results: Contact allergy to a topical eye allergen/medication was found in 12.9% (n = 41) of 318 patients, and culprit allergens were phenylephrine (6.9%), timolol (2.5%) and ketotifen (1.6%). Patch test positive patients were often previously diagnosed with cataract (29.3%) or glaucoma (24.4%), and the majority reported more than one previous reaction. Initial symptoms were oedema (56.0%), erythema (48.8%) and dermatitis (31.7%) in the eye region, and facial dermatitis was also seen., Conclusions: Patients with symptoms from the eye region who have been using topical eye medications should be patch tested with ingredients from commonly used eye medications supplemented by the products tested 'as is'., (© 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Occupational hand eczema is frequent in metalworkers. The contribution of metal allergies is poorly elucidated even though such exposures are common at the workplace. To estimate the prevalence of metal allergy to cobalt (Co), chromium (Cr) and nickel (Ni) in metalworkers and compare these to estimates from the European Surveillance System on Contact Allergies (ESSCA). Two authors independently searched PubMed for studies reporting on the prevalence of metal allergy in metalworkers. Proportion meta-analyses were performed to calculate the pooled proportions of metal allergy in metalworkers. In total, 29 studies (22 from Europe) were included yielding 5691 subjects for quantitative analysis. The pooled proportion (95% confidence interval) of Co, Cr and Ni in European metalworkers with dermatitis referred to patch test clinics was 8.2% (5.3%-11.7%), 8.0% (5.1%-11.4%), and 11.0% (7.3%-15.4%), respectively. The corresponding estimates for unselected metalworkers from workplace studies were 4.9% (2.4%-8.1%), 5.2% (1.0%-12.6%), and 7.6% (3.8%-12.6%), respectively. In comparison, the prevalence of metal allergy in 13 382 consecutive European males with dermatitis was 3.9% (3.6%-4.2%), 4.4% (4.1%-4.8%) and 6.7% (6.3%-7.0%) for Co, Cr and Ni, respectively. Data on sex, age, body piercings and atopic dermatitis in metalworkers with metal allergy was mostly lacking. Metal allergy to all three metals was significantly more common in European metalworkers with dermatitis attending patch test clinics as compared to ESSCA data, indicating a relationship to occupational exposures, however, confounders could not be accounted for., (© 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Compliance with glove use and safe work practices are important factors in primary prevention of occupational hand eczema (OHE) in hairdressers., Objective: To assess the risk OHE and compliance with skin protective measures in hairdressers trained before and after implementation of a nationwide skin protection program in Danish hairdressing vocational schools in 2011., Methods: A repeated cross-sectional study was performed. A questionnaire was sent in 2009 and 2020. The Danish Labour Market Supplementary Pension Scheme provided information on yearly payments from the hairdressing profession., Results: A response rate of 66.6% (305/460) was obtained in the 2009 survey and of 29.9% (363/1215) in the 2020 survey. The career time prevalence of OHE decreased from 42.8% to 29.0% (adjusted odds ratio 0.55 95% confidence interval [CI] 0.40-0.77) and the incidence rate of OHE decreased from 57.5 (95%CI 48.4-68.4) to 42.0 (95%CI 34.6-50.9) per 1000 person years (incidence rate ratio 0.73 [95%CI 0.56-0.95] between the two surveys). A statistically significant (P < .05) increase in glove use when doing wet-work and when handling hair dyes, permanent wave solutions and bleaching products was observed in the 2020 compared to the 2009 survey., Conclusion: Our data suggest that skin protection training during apprenticeship reduces the risk of OHE in hairdressers. The lack of primary prevention of OHE in hairdressing vocational schools may be a missed opportunity in the prevention of the disease., (© 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Occupational hand eczema (OHE) is common in hairdressers, and many leave the trade because of the disease. However, the exact impact of OHE on career length is unknown., Objective: To assess the effect of OHE on career length and risk factors associated with leaving the trade because of OHE in hairdressers followed-up for up to 35 years., Methods: A prospective cohort study of Danish hairdressers graduating between 1985 and 2007 (n=5219) was performed. A questionnaire was sent in 2009 and 2020. The Danish Labor Marked Supplementary Pension Scheme provided information on affiliation to the hairdressing profession. Career length was assessed by Kaplan-Meier analyses., Results: The median survival time was 12.0 (95% CI 11.0 to 13.0) years in graduates with OHE and 14.0 (95% CI 12.6 to 15.4) years in graduates without OHE (p<0.001). Graduates with a frequency of hand eczema (HE) of 'once', 'several times' and 'almost all the time' had a median survival time of 20.0 (95% CI 14.6 to 25.4), 12.0 (95% CI 10.7 to 13.3) and 7.0 (95% CI 5.6 to 8.4) years, respectively. Graduates with OHE that left the trade (partly) because of HE constituted 11.7% of the study population. Factors associated with leaving the trade because of HE included a history of atopic dermatitis (adjusted OR (aOR) 2.2 (95% CI 1.2 to 4.0), a history of a positive patch test (aOR 5.1 (95% CI 2.3 to 11.0) and allergy to hair dyes (aOR 9.4 (95% CI 3.4 to 25.6)., Conclusion: Career length is reduced in hairdressers with OHE, especially if frequently relapsing or caused by contact allergy, for example, to hair dyes., Competing Interests: Competing interests: MH has no competing interest. JPT has received consulting fees from Coloplast and honoraria from Pfizer, AbbVie, Regeneron, Sanofi-Genzyme, LEO, Lilly, Almirall and has participated on a Data Safety Monitoring Board or Advisory Board for Pfizer, AbbVie, Regeneron, Sanofi-Genzyme, LEO, Lilly, Almirall, Arena, Aslan. CZ has received consulting fees from Jansen Cilag, Novartis and Leo Pharma and is a board member of the European Academy of Dermatology and Venereology. WU has a grant agreement for providing data management and analysis in the EFISS project of the IDEA/IFRA project group, has received travel reimbursement for attending IDEA project meeting in Munich August 2019 and is an external expert for the ‘Scientific Committee on Consumer Safety’ (SCCS) of the EU. JDJ has received grants from National Environmental Protection Agency and Leo Foundation, received an honorarium for lecture at The Yearly Meeting of Spanish Dermatologist, is head of Cosmetic Council and advisor to the Danish Minister of Environment (unpaid), President Elect in European Society of Contact Dermatitis (unpaid) and editor-in-chief for the journal Contact Dermatitis., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: We observed an increasing number of patients who presented with facial or retro-auricular dermatitis after skin contact with plastic spectacles or plastic covered temples., Objectives: To identify the allergens in plastic spectacles that may cause allergic contact dermatitis., Methods: All patients with suspected allergic contact dermatitis to eyewear were tested with Solvent Orange 60 (SO60), four additionally with Solvent Yellow 14 (SY14), and five with scrapings from their own spectacles. In one case, a chemical analysis of the spectacles was performed to uncover the causative allergen., Results: Three patients were allergic to SO60, two patients to SY14, and two patients were allergic to both SO60 and SY14., Conclusion: Patients with suspected allergic contact dermatitis from spectacles should be tested with SO60 and SY14, and based on findings from previous reports, also with Solvent Red 179., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: In March 2014, the European Commission issued a new regulation restricting the content of hexavalent chromium (Cr) in leather to no more than 3 mg/kg. We previously performed a questionnaire study in January 2014 to characterize our patients with Cr contact allergy prior to regulatory intervention., Objectives: To assess whether clinical characteristics, self-reported sources of Cr exposure, and burden of disease changed in patients with Cr allergy over time., Methods: A questionnaire study was performed among 172 adult dermatitis patients with Cr allergy and 587 age- and sex-matched dermatitis patients without Cr allergy. A questionnaire was sent to all dermatitis patients patch tested from 2003 to 2018 in August 2019., Results: The overall response rate was 61.2% (759/1241). Patients with Cr allergy were still more commonly affected by current foot dermatitis (odds ratio [OR] 3.82, 95% confidence interval [CI] 2.07-7.08) and hand dermatitis (OR 1.98, 95% CI 1.13-3.49) compared with controls diagnosed during 2013 to 2018. The proportion of patients with Cr allergy reporting dermatitis caused by leather exposure did not change during 2003 to 2012 vs 2013 to 2018 (71.0% vs 66.2%, P = .5). Furthermore, estimates on occupational performance and disease severity (eg, current dermatitis), number of anatomical locations with dermatitis, worst-case dermatitis, and effect on work were similar in patients with Cr allergy for 2003 to 2012 vs 2013 to 2018., Conclusion: No immediate sign of improvement was found in patients with Cr allergy concerning severity of disease and dermatitis from leather exposures 5 years after adoption of the regulation against hexavalent Cr in leather. The regulation may have to be revised for better protection of those already sensitized., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Patch testing is the gold standard for identifying culprit allergens in allergic contact dermatitis; however, it is laborious and positive reactions are difficult to quantitate. Development of complementary in vitro tests is, therefore, of great importance., Objectives: This study aimed to improve the in vitro lymphocyte proliferation test (LPT) to detect allergic responses to nickel (Ni), cobalt (Co), and chromium (Cr)., Methods: Twenty-one metal allergic patients with a positive patch test to Ni (n=16), Co (n=8), and Cr (n=3) and 13 controls were included. All were tested by a flow cytometric LPT., Results: Metal-reactive cells were identified as T helper (Th) cells with high expression of the memory marker CD45RO. Skin-homing (cutaneous lymphocyte-associated antigen positive [CLA+]) Ni-reactive memory Th (Th mem hi ) cells identified individuals with a positive patch test for Ni with 100% sensitivity (95% confidence interval [CI] 81%-100%) and 92% specificity (95% CI 67%-100%). Moreover, Co-specific Th mem hi cells expressing CCR6 identified patients with a positive patch test for Co with 63% sensitivity (95% CI 31%-86%) and 100% specificity (95% CI 77%-100%). In Cr allergic individuals, Cr-reactive Th mem hi cells tended to increased CLA and CCR6 expression., Conclusion: Metal-reactive Th cells with high expression of CD45RO and coexpression of CLA and CCR6 improved the LPT, making it an attractive supplement to the patch test., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: In 2005, methylisothiazolinone (MI) was allowed as a stand-alone preservative in cosmetics. This resulted in an epidemic of allergic contact dermatitis to MI, mainly affecting women exposed to leave-on cosmetics. Consequently, a regulation of Annex V in the European Union in 2017 banned the use of MI in leave-on cosmetics and reduced the allowed concentration in rinse-off products., Objective: To analyze the temporal trends in contact allergy to MI in Danish patients in relation to key events including European regulations over time., Methods: A retrospective study of consecutive patients patch tested with methylisothiazolinone from 2005 to 2019. Demographics and clinical characteristics in terms of MOAHLFA (male, occupational, atopic dermatitis, hand dermatitis, leg dermatitis, facial dermatitis and age >40 years), sources of exposure, and clinical relevance were analyzed in relation to key historical events., Results: Three hundred eighty of 12 494 patients (3.0%, 95CI: 2.7-3.4%) tested from 2005 to 2019 were sensitized to MI. An increasing trend in the prevalence of MI contact allergy from 2005 to 2019 (P < .01) was observed, although a decline in the absolute number of patch-test positive patients was seen from 2013 and onward. A reduction in leave-on cosmetics as a source of exposure was observed following the legislative ban in 2017, from 24.8% from in 2010 to 2013 to 6.2% in 2017 to 2019 (P < .01)., Conclusion: The epidemic of MI contact allergy is declining in absolute terms, although the prevalence in the patch-tested population has not returned to its pre-epidemic levels. The legislative regulation of MI in 2017 has been effective in terms of leave-on cosmetics as a source of exposure in MI allergic patients. The process of post-marketing risk assessment of contact allergens in the European Union needs improvement., (© 2020 John Wiley & Sons A/S . Published by John Wiley & Sons Ltd.)

Background: The number of patients with contact dermatitis from glucose sensors and insulin infusion sets is increasing. Patch testing is challenging because of a lack of information concerning the constituent materials of medical devices., Objectives: To report on products and causes of allergic reactions to glucose sensors or insulin infusion sets over a 5-year period and suggest a short screening series., Methods: Analysis of patch test data from consecutive patients suspected of allergic contact dermatitis (ACD) to glucose sensors and/or insulin infusion sets from 2015-2019., Results: Patient numbers increased from 4 to 15 per year; 30/38 (78.9%) were children. In 29 (76.3%), a diagnosis of allergic/probable ACD was established, mostly due to the tapes of the device or allergens in these tapes (n = 23) followed by allergens in the device housing (n = 10). Isobornyl acrylate, abitol, and colophonium were the most common allergens. Information from manufacturers was often difficult to obtain and, if accessible, inadequate. For this reason, the diagnosis was delayed for more than 1.5 years in 12 (31%) patients., Conclusions: The increasing number of patients, mostly children, with ACD from devices used in treatment of type 1 diabetes demonstrates the importance of this problem. Allergies can easily be overlooked, due to the lack of mandatory labeling of the constituent materials of the devices., (© 2020 John Wiley & Sons A/S . Published by John Wiley & Sons Ltd.)

Background: Naturally derived cosmetic product ingredients of both plant and animal origin are being included increasingly in product formulations in order to cater to consumer preferences. They may be an overlooked cause of reactions to cosmetic products in some patients with dermatitis., Objectives: To identify naturally derived cosmetic product ingredients with allergenic potential (type I and type IV) and propose a cosmetic screening test series., Methods: The study was conducted in two steps. The first step was a market survey using a nonprofit application helping consumers avoid problematic substances in cosmetic products. The application contained 10 067 cosmetic products that were label checked for naturally derived cosmetic product ingredients. The second step was a literature search to examine how frequently the naturally derived ingredients were described and related to allergic reactions in cosmetics or other topically administered products., Results: We identified 121 different naturally derived cosmetic product ingredients that were included in at least 30 cosmetic products. In total, 22 ingredients were selected for a screening test series., Conclusions: We propose a supplemental patch test and a prick test screening series with naturally derived cosmetic product ingredients for patients with skin reactions to cosmetic products, aiming to identify a cause in more patients than is currently possible., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Insulin pump therapy and the use of flash or continuous glucose monitoring in children is increasing. The diabetes devices are attached to the skin for several days to weeks with a strong adhesive, and recently, several cases of allergic contact dermatitis in children caused by components of the adhesive have been reported. In this review, we discuss such problems. The most frequent cause of allergic contact dermatitis is acrylates in the adhesive material, and the problem is serious and calls for rapid development of devices used in the treatment and monitoring of Type 1 diabetes without allergenic agents.

Background: Cobalt contact allergy is common, but clinical relevance is often difficult to determine., Objectives: To examine the aetiology, prevalence and clinical characteristics of cobalt-allergic patients who were patch tested between 2002 and 2017 at the Department of Dermatology and Allergy, Herlev-Gentofte Hospital., Methods: Patch test data, along with patient characteristics and causative exposures, from all adult dermatitis patients seen and tested between 2002 and 2017 were analysed. Associations were tested with the χ 2 test and logistic regression., Results: A total of 13 475 adults aged 18 to 99 years were patch tested. The overall prevalence of cobalt allergy and the prevalence of isolated cobalt allergy were 3.3% and 1.5%, respectively. The prevalence of isolated cobalt allergy decreased from 2.4% in 2006 to 2009 to 1.1% in 2014 to 2017 (P trend = 0.00003). Leather exposure as a relevant cause of allergic cobalt dermatitis increased from 3.7% in 2002 to 2009 to 8.3% in 2010 to 2017 (P = 0.04). The current clinical relevance of positive patch test reactions, that is, a positive reaction to cobalt combined with a history of current skin exposure to a source of cobalt, was 20.1%., Conclusions: We conclude that cobalt allergy is relatively common, but causative exposures are largely unknown, and the proportion of positive patch test reactions with clinical relevance is low. It is therefore currently unclear how we can better protect consumers and workers from cobalt exposure., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Contact allergy to oxidized limonene, with hydroperoxides of limonene (Lim-OOHs) as the main allergens, is common. However, high proportions of weak positive and doubtful patch test reactions have been reported., Objectives: To determine the clinical relevance, elicitation threshold and dose-response relationship of Lim-OOHs in individuals with a positive or doubtful patch test reaction to standard Lim-OOHs 0.3% pet., Methods: A multicentre 3-week double-blind vehicle-controlled repeated open application test (ROAT) study with a simulated fine fragrance containing Lim-OOHs at 1260, 420 and 140 ppm, equal to a dose/area per application of Lim-OOHs of 3.0, 0.99 and 0.33 μg/cm 2 , was performed., Results: Among 11 subjects allergic to Lim-OOHs, 11 (100%), 7 (64%), and 3 (27%), respectively, reacted to the applied doses. No reactions were seen in 17 healthy controls exposed to the highest dose. This difference in reactivity was statistically significant (P < 0.0001). Among 13 subjects with doubtful patch test reactions to Lim-OOHs, two (15%) had positive ROAT reactions to the highest Lim-OOH dose applied (P = 0.36 as compared with controls)., Conclusions: Contact allergy to Lim-OOHs is of clinical relevance in patients with positive patch test reactions. A doubtful patch test reaction to Lim-OOHs 0.3% pet. can be of clinical relevance., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: In 2012, Danish authorities submitted a proposal to the European Chemical Agency restricting the content of hexavalent chromium to a maximum of 3 ppm in leather goods. Following its adoption, this proposal was implemented in 2015 as a directive in the EU., Objectives: To examine the temporal trend of chromium contact allergy in adult dermatitis patients patch tested between 2002 and 2017, and to determine clinical characteristics and causative exposures in these patients., Methods: All adult dermatitis patients patch tested between 2002 and 2017 were included. Patch test data were reviewed retrospectively. Comparisons were performed with the χ 2 test and logistic regression analysis., Results: A total of 13 379 adults aged 18 to 99 years were patch tested between 2002 and 2017. The overall prevalence of chromium allergy was 2.2%. An overall decreasing trend was found for the prevalence of chromium allergy (P trend = 0.00002). Specifically, a significant difference was found for the study periods 2010 to 2013 (P trend  = 0.002) and 2014 to 2017 (P trend  < 0.0001) as compared with 2002 to 2005. Leather remained the most important single cause of allergic contact dermatitis caused by chromium. The proportion of clinically relevant leather exposures increased from 42.3% during 2002 to 2009 to 54.8% during 2010 to 2017 (P = 0.04)., Conclusions: The prevalence of chromium allergy is decreasing. The EU Directive restricting the use of hexavalent chromium in leather goods is thought to be playing a central role in this change., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Contact allergy is common in children, but may be underdiagnosed. Importantly, the clinical relevance of specific allergies is subject to constant change, and it is therefore important to continuously monitor the trends and changes of contact allergies in the paediatric population., Objectives: To identify possible changes in contact allergy and allergic contact dermatitis among Danish children referred for patch testing., Methods: A retrospective study was performed based on patch test data from the Danish National Database of Contact allergy. The current data were compared with previously published data on Danish children referred for patch testing., Results: Between 2012 and 2016, 1573 children and adolescents were patch tested. Overall, 385 (24.5%) had at least 1 positive patch test reaction. The overall prevalence was similar in boys and girls, across age groups, and in patients with and without atopic dermatitis. Statistically significant increases in contact allergy to fragrances and isothiazoliones were seen, whereas a decrease in nickel allergy was found., Conclusion: Allergic contact dermatitis continues to be a common disease in children, and is even significantly increasing for some allergens., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: For cosmetics, it is mandatory to label 26 fragrance substances, including all constituents of fragrance mix I (FM I) and fragrance mix II (FM II). Earlier reports have not included oxidized R-limonene [hydroperoxides of R-limonene (Lim-OOH)] and oxidized linalool [hydroperoxides of linalool (Lin-OOH)], and breakdown testing of FM I and FM II has mainly been performed in selected, mix-positive patients., Objectives: To report the prevalence of sensitization to the 26 fragrances, and to assess concomitant reactivity to FM I and/or FM II., Methods: A cross-sectional study on consecutive dermatitis patients patch tested with the 26 fragrances and the European baseline series from 2010 to 2015 at a single university clinic was performed., Results: Of 6004 patients, 940 (15.7%, 95%CI: 14.7-16.6%) were fragrance-sensitized. Regarding the single fragrances, most patients were sensitized to Lin-OOH (3.9%), Evernia furfuracea (3.0%), Lim-OOH (2.5%), and hydroxyisohexyl 3-cyclohexene carboxaldehyde (2.1%). Significantly fewer patients were 'FM I-positive and constituent-positive' than 'FM II-positive and constituent-positive' (32.7% versus 57.0%, p < 0.0001). Additionally, significantly more patients were 'FM II-negative but constituent-positive' than 'FM I-negative but constituent-positive' (12.4% versus 3.2%, p = 0.0008)., Conclusions: Non-mix fragrances are the most important single fragrance allergens among consecutive patients. The test concentration of the single FM I constituents should be increased when possible., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Chromium coatings on metal alloys can be decorative, and prevent corrosion and metal ion release. We recently showed that handling of a chromium-containing disc resulted in chromium deposition on the skin., Objectives: To examine patch test reactivity to chromium-coated discs., Methods: We included 15 patients: 10 chromium-allergic patients, and 5 patients without chromium allergy. All were patch tested with potassium dichromate, cobalt chloride, nickel sulfate, and nine different metallic discs. The chromium-allergic patients were also patch tested with serial dilutions of potassium dichromate., Results: Positive/weaker reactions were observed to disc B (1 of 10), disc C (1 of 10), and disc D, disc E, and disc I (4 of 10 each). As no controls reacted to any of the discs, the weak reactions indicate allergic reactions. Positive patch test reactions to 1770 ppm chromium(VI) in the serial dilutions of potassium dichromate were observed in 7 of 10 patients. When the case group was narrowed down to include only the patients with a current positive patch test reaction to potassium dichromate, elicitation of dermatitis by both chromium(III) and chromium(VI) discs was observed in 4 of 7 of patients., Conclusions: Many of the patients reacted to both chromium(III) and chromium(VI) surfaces. Our results indicate that both chromium(VI) and chromium(III) pose a risk to chromium-allergic patients., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Contact dermatitis in healthcare workers is a world wide problem. We conducted a retrospective observational study of the patch-test results of 1402 healthcare workers and 1402 matched controls with contact dermatitis who were treated at 3 hospitals departments in Denmark between 2007 and 2014. The primary objective was to determine whether healthcare work was associated with contact allergy to thiuram mix. Unadjusted univariate analyses revealed that healthcare work was significantly associated with occupational contact dermatitis and hand dermatitis. Contact allergy to thiuram mix was more common in healthcare workers was significantly associated with having occupational contact dermatitis, hand dermatitis and older age. In conclusion, we report here a potential problem of contact allergy to thiurams in healthcare workers with contact dermatitis. Legislative authorities may in the future focus on the use of rubber accelerators in, for example, protective gloves, which are widely used by healthcare professionals.

Background: Chlorhexidine is a widely used disinfectant in the healthcare setting and in cosmetic products. A high prevalence of chlorhexidine contact allergy was reported in Denmark in the 1980s (2.0-5.4% of patients patch tested). It is unknown whether the prevalence is still high, which products cause the contact allergy, and whether accidental re-exposure occurs in some patients., Objectives: To estimate the prevalence of chlorhexidine contact allergy in a tertiary dermatology clinic in Denmark; to investigate whether patch testing with both chlorhexidine diacetate and chlorhexidine digluconate is necessary; to investigate how many patients have combined immediate-type allergy and contact allergy; and to identify which products cause chlorhexidine contact allergy, and whether patients are accidentally re-exposed., Methods: This was a retrospective study including all patients patch tested with chlorhexidine during 2003-2013 at the Department of Dermato-Allergology at Copenhagen University Hospital Gentofte (n = 8497). All patients with a positive patch test reaction to chlorhexidine were sent a questionnaire comprising questions about the cause of the allergy and re-exposure., Results: Overall, 1.0% (n = 82) of all patients patch tested with chlorhexidine were positive. A decrease in the prevalence was observed over time, most likely because of lowering of the test concentration from 1.0 to 0.5% in 2008. Of the 82 patients, 28 (0.3%) had positive test reactions to both chlorhexidine salts, 43 (0.5%) had a positive test reaction only to chlorhexidine diacetate, and 11 (0.1%) had a positive test reaction to chlorhexidine digluconate. Three patients were both patch test-positive and prick test-positive. A known cause of the allergy was reported by 19 patients (40%) in the questionnaire: the products used in the healthcare setting were mainly reported, but some reported cosmetic products. Accidental re-exposure was reported by 15 patients (32%), of whom 13 reported symptoms., Conclusions: The prevalence of chlorhexidine contact allergy does not seem to be higher in Denmark than in other European countries. Patch testing with both chlorhexidine diacetate and chlorhexidine digluconate may be beneficial. Testing for immediate-type allergy in patients with a positive patch test reaction to chlorhexidine is recommended. Chlorhexidine-containing products used in the healthcare setting and in cosmetics are potential causes of sensitization and allergy. Re-exposure is common, highlighting the fact that patients and healthcare personnel need to be well informed about possible sources of exposure., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The history of chromium as an allergen goes back more than a century, and includes an interventional success with national legislation that led to significant changes in the epidemiology of chromium allergy in construction workers. The 2015 EU Leather Regulation once again put a focus on chromium allergy, emphasizing that the investigation of chromium allergy is still far from complete. Our review article on chromium focuses on the allergen's chemical properties, its potential exposure sources, and the allergen's interaction with the skin, and also provides an overview of the regulations, and analyses the epidemiological pattern between nations and across continents. We provide an update on the allergen from a dermatological point of view, and conclude that much still remains to be discovered about the allergen, and that continued surveillance of exposure sources and prevalence rates is necessary., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Vaccination with aluminium-adsorbed vaccines can induce aluminium allergy with persistent itching subcutaneous nodules at the injection site – vaccination granulomas. In this article we give an overview of childhood aluminium-adsorbed vaccines available in Denmark. Through literature studies we examine the incidence, the symptoms and the prognosis for the vaccination granulomas and the allergy. Finally we discuss the status in Denmark.

Background: Cobalt is a strong skin sensitizer and a prevalent contact allergen. Recent studies have recognized exposure to leather articles as a potential cause of cobalt allergy., Objectives: To examine the association between contact allergy to cobalt and a history of dermatitis resulting from exposure to leather., Methods: A questionnaire case-control study was performed: the case group consisted of 183 dermatitis patients with a positive patch test reaction to cobalt chloride and a negative patch test reaction to potassium dichromate; the control group consisted of 621 dermatitis patients who did not react to either cobalt or chromium in patch testing. Comparisons were made by use of a χ(2) -test, Fisher's exact, and the Mann-Whitney test. Logistic regression analyses were used to test for associations while taking confounding factors into consideration., Results: Leather was observed as the most frequent exposure source causing dermatitis in the case group. Although the case group significantly more often reported non-occupational dermatitis caused by leather exposure (p < 0.001), no association was found between cobalt allergy and dermatitis caused by work-related exposure to leather., Conclusions: Our study suggests a positive association between cobalt allergy and a history of dermatitis caused by non-occupational exposure to leather articles., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Chromium-tanned leather articles currently constitute the most important cause of contact allergy to chromium in Denmark. A regulation on the content of hexavalent chromium in leather was adopted in November 2013 by the EU member states., Objectives: To characterize patients with chromium allergy and their disease, to serve as a baseline for future studies on the potential effect of the new regulation on chromium in leather., Methods: A questionnaire case-control study was performed on 155 dermatitis patients with positive patch test reactions to potassium dichromate and a matched control group of 621 dermatitis patients. Comparisons were made by use of a χ(2) -test and the Mann-Whitney U-test. Logistic regression analyses were used to test for associations., Results: Sixty-six per cent of chromium-allergic patients had a positive history of contact dermatitis caused by leather exposure. They had a significantly lower quality of life (p < 0.001), a higher prevalence of dermatitis during the last year (p = 0.008), a higher use of medication during the past 12 months (p = 0.001) and a higher prevalence of sick leave (p = 0.007) than patients in the control group., Conclusions: Chromium-allergic patients have more severe and more chronic contact dermatitis. Their primary chromium exposure comes from leather articles., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Vaccination with aluminium-adsorbed vaccines can induce aluminium allergy with persistent itching subcutaneous nodules at the injection site - vaccination granulomas. In this article we give an overview of childhood aluminium-adsorbed vaccines available in Denmark. Through literature studies we examine the incidence, the symptoms and the prognosis for the vaccination granulomas and the allergy. Finally we discuss the status in Denmark.

Background: A patient who had suffered from persistent generalized dermatitis for 7 years was diagnosed with cobalt sensitization, and his leather couch was suspected as the culprit, owing to the clinical presentation mimicking allergic chromium dermatitis resulting from leather furniture exposure., Materials and Methods: The cobalt spot test, X-ray fluorescence, inductively coupled plasma mass spectrometry and scanning electron microscopy were used to determine cobalt content and release from the leather couch that caused the dermatitis and from 14 randomly collected samples of furniture leather., Results: The sample from the patient's leather couch, but none of the 14 random leather samples, released cobalt in high concentrations. Dermatitis cleared when the patient stopped using his couch., Conclusions: Cobalt is used in the so-called pre-metallized dyeing of leather products. Repeated studies have found high levels of cobalt sensitization, but not nickel sensitization, in patients with foot dermatitis. We raise the possibility that cobalt may be widely released from leather items, and advise dermatologists to consider this in patients with positive cobalt patch test reactions., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)