Contents of sensitising rubber accelerators in disposable rubber gloves: A Copenhagen market survey.

BACKGROUND: Rubber gloves contain rubber accelerators that may cause contact allergy. The content of sensitising rubber accelerators in contemporary rubber gloves is not well known. OBJECTIVES: Identify and quantify the content of rubber accelerators in disposable rubber gloves. METHODS: Fifty-one gloves of 49 different brands were collected. Forty-eight of the gloves were disposable and three re-usable. The gloves were analysed for their content of sensitising rubber accelerators, that is, zinc dithiocarbamates, thiurams, thiazoles/benzothiazoles, diphenylguanidine, and thioureas by high-performance liquid chromatography. RESULTS: Rubber accelerators were identified in 43/48 (90%) of the disposable gloves. In total, 39 gloves contained zinc dibutyldithiocarbamate (ZDBC) (0.18-1.96 mg/g), 34 zinc diethyldithiocarbamate (ZDEC) (0.032-2.78 mg/g), three zinc dibenzyldithiocarbamate (0.65-1.4 mg/g), one zinc dimethyldithiocarbamate (0.23 mg/g), and one 1,3-diphenylguanidine (0.21 mg/g). 2-cyanoethyl dimethyldithiocarbamate (CEDMC) was identified in three gloves (<0.052 mg/g). The one glove labelled as accelerator free contained ZDBC (1.07 mg/g). Only few glove packages had the specific content of rubber accelerators labelled. CONCLUSIONS: The most frequent rubber accelerators in rubber gloves are ZDEC and ZDBC. Accelerator-free gloves may contain rubber accelerators. Full labelling of rubber gloves is needed and producers should be sure not to falsely claim that the rubber gloves are free of rubber accelerators.

Insights into hair dye use and self-reported adverse skin reactions in the Dutch general population: A cross-sectional questionnaire-based study.

BACKGROUND: Hair dyes are widely used in daily life. However, data on self-reported adverse skin reactions are scarce. OBJECTIVES: To estimate the proportion of lifetime hair dye use and self-reported adverse skin reactions in the Dutch general population, and to investigate the association between (adverse skin reactions to) hair dye use and contact allergy-related factors. METHODS: This cross-sectional study collected questionnaire-derived data from the Lifelines cohort. Logistic regression analyses were conducted between (adverse skin reactions to) hair dye use and black henna tattoo use, reactions to henna tattoos, patch testing, hand eczema and an occupation as hairdresser or beautician. RESULTS: The proportion of hair dye use was 63.1% of 70 987 participants, of which 6.8% experienced adverse skin reactions, mostly mild (77.7%). Hair dye users and those with skin reactions were both positively associated (p < 0.05) with female sex, middle-age, (positive) patch test results and hairdresser or beautician occupations. Hair dye users were more likely to have had henna tattoos, and those with reactions to hair dye were more likely to have had reactions to henna tattoos. CONCLUSIONS: Hair dye use is prevalent among the Dutch general population and frequently causes adverse skin reactions, especially in females who had black henna tattoos.

Atopic dermatitis and hand eczema in Danish adults: A nationwide population-based study.

BACKGROUND: Atopic dermatitis (AD) and hand eczema often co-occur, particularly among adults. OBJECTIVES: To examine the interplay between AD and hand eczema in the general population, by characterising prevalence, disease severity, contact sensitization, and comorbidities in individuals with one or both conditions. MATERIALS AND METHODS: In this cross-sectional study, 100 000 randomly selected adults in the Danish general population received a questionnaire via a secure, digital mailbox linked to their civil registration number. Participants answered questions regarding eczema, disease severity, patch testing, and comorbidities. RESULTS: A total of 40 007 individuals responded to the question on a lifetime prevalence of AD, and the prevalence among adult Danes was 9.0%. Nearly one third of individuals with AD reported moderate to severe disease. AD was associated with contact sensitization and increased hand eczema prevalence. Individuals with both AD and hand eczema reported worse disease severity. Furthermore, having both conditions was associated with an increased risk of psychiatric comorbidities. CONCLUSIONS: This study provided updated information about unselected adults with AD in Denmark. Individuals with both AD and hand eczema represent a vulnerable subgroup that physicians should be attentive to.

Contact Allergy Screening for Atopic Dermatitis.

Atopic dermatitis (AD) and allergic contact dermatitis (ACD) are common inflammatory skin diseases in both children and adults that present similarly and often coexist. Patch testing is the gold standard for establishing the diagnosis of ACD and can often help distinct between the 2 conditions. Patch testing is more challenging in patients with underlying AD due to potential for angry back reactions. In this review, we discuss the current evidence and guidelines regarding the screening for contact allergies in patients with AD. We also discuss the most frequent relevant allergens in adults and children with atopic dermatitis.

Surprising results of patch testing with the baseline series in patients with photocontact allergy to ketoprofen.

OBJECTIVE: Photoallergic reactions due to topical ketoprofen are common. As some simultaneous contact allergies have been described in the literature, we aimed to get an overview of the pattern of reactivity towards common allergens in the baseline series in ketoprofen-photoallergic individuals. METHODS: Using our database, we found 94 patients with photocontact allergy to ketoprofen diagnosed during 1999-2018. Approximately 12 800 patients patch tested with the baseline series during the same time frame served as controls. Data on patch testing with the baseline series of 518 individuals belonging to the general population were obtained from an earlier study, and a comparison of allergy rates was made with the ketoprofen group. RESULTS: Contact allergy to fragrance mix I and Myroxylon pereirae was overrepresented among patients with photocontact allergy to ketoprofen (42.3% vs. 6.6% and 47.9% vs. 6.6%, p < 0.001, respectively). Significant overrepresentation was also shown for 4-tert-butylphenolformaldehyde resin (PTBP-F-R), phenol formaldehyde resin (PFR-2), black rubber mix, budesonide (all p < 0.001), and fragrance mix II (p = 0.02). The pattern was similar, but with lower significance levels for fragrance mix II and budesonide, regardless of whether or not the individuals had been photopatch tested because of a suspected photoallergic contact dermatitis from ketoprofen. CONCLUSION: Contact allergy to fragrance mix I, Myroxylon pereirae, black rubber mix, PFR-2, PTBP-FR, and to a somewhat lower extent, to fragrance mix II and budesonide, is common in individuals photoallergic to ketoprofen. It remains to be seen whether sensitisation to ketoprofen leads to simultaneous sensitisation to a number of other, chemically non-related, substances.

Prevalence of contact allergy to gold in dermatitis patients from 2010 to 2024: A systematic review and meta-analysis.

Gold contact allergy is diagnosed by patch testing using gold chloride or gold sodium thiosulfate. These tests often show high positivity rates, but a direct correlation with dermatitis from everyday gold exposure is rare. The aim of this study was to investigate and estimate the current prevalence of gold contact allergy in dermatitis patients. We performed a systematic literature search in PubMed, Embase and Web of Science for studies reporting the prevalence of gold contact allergy in dermatitis patients and published between January 2010 and May 2024. Data extraction and quality assessment were performed, and pooled proportions were calculated using random effects models. Sixteen studies with 14 887 dermatitis patients were included. The pooled prevalence of gold contact allergy was 14.1% (95% confidence intervals: 9.5%-19.4%) with significant heterogeneity (I2 = 98.3%). High positivity rates with limited clinical relevance highlight the need for cautious interpretation. Even within the same country, studies find different prevalence rates. Standardized testing protocols and further research are needed to better understand and manage this allergy.

Cross-reactivity between thiuram disulfides and dithiocarbamates. A study of TETD and ZDEC using mouse models.

BACKGROUND: Rubber accelerators are used in the vulcanization of rubber. However, rubber accelerators for example tetraethylthiuram disulfide (TETD) and zinc diethyldithiocarbamate (ZDEC) may cause contact allergy. Concomitant reactions between ZDEC and TETD have been observed in patients which could be explained by co- or cross-reactivity. OBJECTIVES: To investigate cross-reactivity between TETD and ZDEC and vice versa. METHODS: Groups of mice were sensitized with TETD or ZDEC based on reported EC3-values. Proliferation of lymphocytes were measured on day 5. To test cross-reactivity, mice were sensitized and challenged 3 weeks later with TETD or ZDEC. The inflammatory response was measured by changes in ear thickness and the proliferative response in CD4+ and CD8+ T cells in the submandibular and cervical draining lymph nodes. RESULTS: Sensitization of mice with doses of ZDEC 3%, TETD 5.6% or TETD 16.2% induced significant increased ear thickness and proliferation of CD4+ and CD8+ T cells. Challenge with ZDEC or TETD in these groups induced significant increased ear thickness. Challenge with ZDEC in mice sensitized to TETD 5.6% or TETD 16.2% induced significant increased proliferation of CD4+ and CD8+ T cells. CONCLUSIONS: We show cross-reactivity between TETD and ZDEC. Patients sensitized to TETD or ZDEC should avoid exposure to both ZDEC and TETD.

Results of patch testing propolis in the European baseline series: A 4-year retrospective study.

BACKGROUND: Propolis was added to the European baseline series (EBS) in 2019. OBJECTIVES: To investigate the frequency and relevance of positive patch tests to propolis in the EBS and to study co-reactivities. PATIENTS AND METHODS: Retrospective study in patients patch tested between June 2019 and November 2023 in a university hospital in Amsterdam, The Netherlands. RESULTS: Of 3134 consecutive patients, 299 (9.5%) had a positive reaction to propolis 10% pet. Only nine reactions (3%) were judged to be clinically relevant. There were significant co-reactivities to Myroxylon pereirae resin (balsam of Peru), colophonium, fragrance mixes 1 and 2, and to limonene and linalool hydroperoxides. A steep increase in rates of positive reactions to propolis was observed from 2020 to 2023. This was highly likely the result of the replacement of Chinese propolis with Brazilian propolis by the manufacturer. CONCLUSIONS: Positive patch tests for propolis are very frequent in Amsterdam, but only a few of these reactions are relevant. Most are probably (pseudo-)cross-reactions in patients with fragrance allergies. Propolis in the EBS has very limited value for dermatologists and patients in The Netherlands. Changes in patch test materials should be provided to all users to avoid misinterpretation of patch test results.

Hidden formaldehyde in cosmetic products.

BACKGROUND: Formaldehyde is a common cause of contact allergy. Hidden formaldehyde, that is, formaldehyde in products without formaldehyde releasers, has previously been detected in cosmetic products. OBJECTIVES: The objective of this study was to investigate the content and causes of hidden formaldehyde in leave-on cosmetic products. METHODS: The formaldehyde release from 142 cosmetic products, primarily creams, was analysed using the chromotropic acid (CA) method. The study included 130 products with no formaldehyde releasers on the ingredient list and 12 products with formaldehyde releasers. Products without formaldehyde releasers positive to CA, that is, with formaldehyde ≥2.5 ppm, were additionally analysed using high-performance liquid chromatography (HPLC). Formaldehyde release from selected raw materials and packaging were also investigated. RESULTS: Hidden formaldehyde was found in 23 of the 130 products (18%) without formaldehyde releasers on the ingredient list. The average formaldehyde content was 105 ppm (range: 0.5-507 ppm) in products with hidden formaldehyde and 355 ppm (range: 75-637 ppm) in eight products with formaldehyde releasers, selected for HPLC analysis. Impurities of formaldehyde in dihydroxyacetone may be a cause of hidden formaldehyde in self-tanners. No clear pattern was found for the other products with hidden formaldehyde. CONCLUSIONS: Changes in regulation are needed to prevent allergic contact dermatitis from hidden formaldehyde in cosmetic products.

Current frequency of contact allergy to isothiazolinones (methyl-, benz- and octylisothiazolinone) across Europe.

BACKGROUND: The use of methylisothiazolinone (MI) as a preservative in cosmetic products caused an alarming increase in MI contact allergy across Europe in the 2010s. This was followed by regulations of use with a total ban on leave-on (implemented in 2017) and reduced use concentrations in rinse-off cosmetics (2018). OBJECTIVE: To follow-up on the prevalence of contact allergy to MI and the related benzisothiazolinone (BIT) and octylisothiazolinone (OIT) in consecutively patch-tested patients in Europe. METHODS: A cross-sectional audit following the design of two previous audits on MI contact allergy from 1 May 2022 to 31 October 2022 included all patients patch tested with the European baseline series, including or supplemented with MI, BIT and OIT across 10 departments in eight European countries. RESULTS: A total of 2554 patients were consecutively patch tested with the three isothiazolinones during the study period. The prevalence of MI and BIT contact allergy was 2.9% (95% confidence interval [CI]: 2.3%-3.7%; range 1.1%-5.8%) and 3.1% (95% CI: 2.4%-3.9%; range 0.0%-6.6%), respectively; that of OIT was 0.7% (95% CI: 0.4%-1.1%; range 0%-3.2%). Rinse-off cosmetic (73.3%) and leave-on cosmetic products (13.3%) were still associated with eliciting allergic contact dermatitis to MI. CONCLUSION: We confirmed a positive impact of regulatory measures on the prevalence of MI contact allergy in Europe, which halved compared to 2015. However, our data suggest that consumers may still be exposed to older cosmetic products containing MI. BIT has superseded MI in causing contact allergy, despite not being allowed for use in cosmetic products.

Contact allergy to neomycin in consecutively patch tested Danish eczema patients from 2000 to 2023: A cross-sectional study.

BACKGROUND: Neomycin is an aminoglycoside antibiotic that may cause contact allergy. It was withdrawn as a medicine for human use in Denmark in October 2009 but is still found in some vaccines. OBJECTIVES: To identify time trends in contact allergy to neomycin in the period from 2000 to 2023. METHODS: A cross-section study of patients ≥18 years consecutively patch-tested with neomycin sulfate (20% in pet.) at Gentofte Hospital, Denmark, during the period 2000-2023 was conducted. RESULTS: The overall prevalence of contact allergy to neomycin was 1.4%. The prevalence was significantly lower in the period '2010-2023' (1.2%) than in '2000-2009' (1.8%) (p < 0.005). Contact allergy to neomycin was significantly positively associated with facial dermatitis and age >40 years, and significantly negatively associated with occupational dermatitis and hand dermatitis. No changes in sex, occupational dermatitis, atopic dermatitis, hand dermatitis, leg dermatitis, facial dermatitis, or age > 40/≤40 (the MOAHLFA-index) were identified when comparing neomycin contact allergic-patients in the two periods '2010-2023' and '2001-2009'. CONCLUSION: Neomycin is a rare cause of contact allergy in Denmark with a significantly lower prevalence following its withdrawal as a medicinal product for human use in Denmark in 2009.

Potassium dichromate sensitivity presenting as tefillin dermatitis: A retrospective cohort study.

BACKGROUND: Tefillin are a religious article worn by Jewish men during daily prayer. Tefillin dermatitis secondary to potassium dichromate sensitivity is recognised, but data remain sparse. OBJECTIVE: To investigate the prevalence and clinical characteristics of tefillin dermatitis. METHODS: Patients who underwent patch testing with the European baseline series in a tertiary dermatology clinic in 2009-2023 and were diagnosed with tefillin dermatitis were identified by file review and their clinical data recorded. RESULTS: Of 1679 consecutive male patients tested, 25 (1.49%) were diagnosed with tefillin dermatitis, accounting for 15.34% of all potassium-dichromate-positive patients (163/1679). Mean pre-symptomatic duration of tefillin use was 38 ± 16.9 years, and mean follow-up time, 3.1 ± 2.9 years. Patients presented with an eczematous rash on body areas in direct contact with the leather box or straps of the tefillin. An id reaction was noted in 32%, and sensitivity to other leather accessories, in 44%. Fourteen patients (56%) switched to chromate-free tefillin: symptoms resolved completely in 11 (79%) and partially in 2. LIMITATIONS: Retrospective cohort design. CONCLUSION: This is the largest study to date of tefillin dermatitis caused by sensitivity to potassium dichromate used in leather production. Prognosis after switching to chromate-free tefillin was good-to-excellent. Tefillin dermatitis may be more prevalent than previously thought.

The correlation between self-reported hand eczema and clinically based diagnosis in professional cleaners.

BACKGROUND: Most studies investigating the prevalence of hand eczema (HE) in professional cleaners use self-reported questionnaire-based data. However, no validation studies of self-reporting of HE among professional cleaners have previously been conducted. OBJECTIVES: To investigate (1) the point prevalence of self-reported HE, (2) the point prevalence of HE estimated by physical examination of the hands and (3) the sensitivity and specificity of self-reporting of HE compared with the diagnosis based on physical examination among professional cleaners. METHODS: Professional cleaners at three different hospitals in Region Zealand were invited to fill out a questionnaire. The point prevalence of self-reported HE was estimated based on questions from the Nordic Occupational Skin Questionnaire. After completing the questionnaire, each cleaner underwent a physical examination of the hands by a dermatologist on the same day. RESULTS: In total, 234 cleaners were invited to participate in the study, and 224 (response rate = 96.0%) agreed to take part. Based on the self-reported questionnaires, 5.3% (n = 12) of the cleaners had current HE. Based on an examination by a physician, 19.2% (n = 43) of the cleaners had current HE. The sensitivity of self-reported HE was found to be 28.0%, while the specificity was found to be 100.0%. The positive predictive value was found to be 100.0%, while the negative predictive value was 85.0%. CONCLUSION: The true point prevalence of HE among professional cleaners is underestimated when based on self-reporting.

Contact sensitization to fragrance mix I and fragrance mix II among European dermatitis patients: A systematic review.

BACKGROUND: Fragrance substances are a frequent cause of contact allergy worldwide. Fragrance exposure varies by sex, age and possibly country, influenced by cosmetic availability, environmental conditions and cultural practices. OBJECTIVES: To systematically review and gather prevalence of sensitization to fragrance mix I (FM I) and fragrance mix II (FM II) in consecutively patch tested European dermatitis patients. METHOD: A total of 4134 publications on patch test results of European dermatitis patients, published from 1981 to 2022, were systematically reviewed according to a previously registered and published PROSPERO protocol. RESULTS: Eighty-four eligible original articles were analysed. Overall prevalence of sensitization to fragrance mix I (FM I) was 6.81% (95% CI: 6.37-7.28), and FM II was 3.64% (95% CI: 3.3-4.01). Sensitization to FM I was most prevalent in Central and Eastern Europe and to FM II in Western Europe. No clear time trends were observed. Among paediatric dermatitis patients, sensitization prevalence for FM I and FM II was 4.09% (95% CI: 3.37-4.96) and 2.17% (95% CI: 1.53-3.07). CONCLUSION: The frequency of positive patch test results for both FMI and FMII remains high. Sensitization is also prevalent among children. Enhanced regulation and labelling of cosmetic products play a vital role in averting exposure and sensitization to fragrance allergens.