Patch test results with the European baseline series, 2019/20-Joint European results of the ESSCA and the EBS working groups of the ESCD, and the GEIDAC

Prevalence of Contact Allergy to Neomycin in Dermatitis Patients: A Systematic Review and Meta-Analysis

Neomycin, an aminoglycoside antibiotic frequently employed in topical formulations, is a recognised allergen that is part of many baseline series and can cause contact allergy (CA) in both adults and children. It is an allergen of interest as it has a widespread use in over-the-counter and prescription products globally, but geographical variations may exist. This study aimed to establish prevalence estimates of CA to neomycin in dermatitis patients and to investigate potential geographical variations. Three databases (PubMed, Embase, and Web of Science) were screened, revealing 70 included studies comprising 456 372 adults and 17 720 children who underwent patch testing. The pooled prevalence of CA to neomycin was found to be 3.2% (95% confidence interval [CI]: 2.6%-3.8%) in adults and 4.3% (95% CI: 2.65%-6.3%) in children. The highest prevalences were observed in North America (adults: 6.4%; children: 8.1%) and South Asia (adults: 4.9%), while Europe showed lower rates (adults: 2.5%; children: 0.8%). Studies after the year 2000 indicated a prevalence of 2.1% in adults and 5.1% in children across geographical regions. These findings highlight a public health concern, particularly in regions with high prevalence rates. The study underscores the need for more restrictive use of neomycin to reduce the incidence of neomycin-induced CA.

Prevalence and Determinants of Sensitisation to Neomycin in North-Eastern Italy, 1997-2021

BACKGROUND

Allergic contact dermatitis (ACD) induced by topical application of neomycin is frequently reported.

OBJECTIVES

This multi-center study investigated prevalence and determinants of neomycin sensitisations in 30 629 outpatients from North-eastern Italy during 1997-2021.

PATIENTS AND METHODS

European baseline and extended Triveneto series were applied on the upper back of patients patch testing for suspected ACD and removed after 48 h.

RESULTS

Prevalence of neomycin sensitisation was 2.29% (=701/30 629), significantly decreasing over time, especially after 2003. Neomycin sensitisation increased with age, especially in female patients older than 60 with leg dermatitis. The majority of patients sensitised to neomycin (74.5%) tested positive also against other haptens, particularly ingredients included in creams and emollients, as lanolin or benzocaine or preservatives as thimerosal or parabens.

CONCLUSIONS

The decreasing prevalence of neomycin sensitisation over time likely reflected reduced accessibility and circulation of neomycin in Italy, due to containment of prescriptions and over-the-counter accessibility. Older individuals are typically more likely to be treated by topical medications and antibiotics as neomycin for various conditions, including stasis dermatitis. Since ACD caused by topical medications is relatively easy to miss, comprehensive drug history and patch testing are essential for any patient with suspected sensitisation caused by neomycin.

Extended fragrance ingredients surveillance study (EFISS)-protocol for a clinical surveillance study on contact allergy to 7 fragrance materials in widespread use but hitherto not systematically patch tested

Contact allergy (CA) is not uncommon in the population, including to various fragrance allergens. If not diagnosed correctly, allergic contact dermatitis (ACD) may ensue, because targeted allergen avoidance is not possible. The primary objective of the study is to estimate the prevalence of CA to seven fragrance materials in patients with suspected ACD across Europe. Based on the outcome, a conclusion will be drawn as to whether present risk management regarding maximum recommended concentrations of each of these, based on quantitative risk assessment (QRA2), is adequate. The planned study is a surveillance study based on consecutive patients, patch tested in 10 European departments of dermatology with a series of allergens as indicated by their personal history, including the European baseline series, supplemented with the seven additional fragrance ingredients. The patch test procedure will follow the guideline of the European Society of Contact Dermatitis (ESCD) with additional standardization procedures. The envisaged sample size is 8100; recruitment will be in three data cycles with brief intervals allowing for descriptive interim analyses. Those patients reacting positively to any of the study allergens will be followed-up specifically to identify the source of sensitizing and/or eliciting exposure(s). Results will inform risk reassessment and subsequent risk management measures. Study results will be published in an open-access peer-reviewed scientific journal. Structured post-marketing surveillance of consumer risk of contact allergy by monitoring prevalences of positive patch test reactions in a dedicated European expert network is developed which can serve as a model for further chemicals. Important outcomes will be either a confirmation of effectiveness of risk management measures in place, or alternatively identifying aspects needing improvement (for certain cosmetic product categories). DRKS registration (DRKS00033263) 16.09.2024, mirrored at https://trialsearch.who.int.

Allergens Responsible for Contact Allergy in Children From 2010 to 2024: A Systematic Review and Meta-Analysis

Contact allergy (CA) is a frequent condition in children; however, newer estimates of the prevalence of CA in children are lacking. Herein, we aim to provide an estimate of the prevalence of CA in children from 2010 to 2024. Two authors independently searched PubMed, Embase and Web of Science for studies reporting the prevalence of positive patch tests (PPTs) to allergens in populations including ≥ 100 children (< 18 years). Proportion meta-analyses were conducted to calculate the pooled prevalence estimates of CA in children. Seventeen studies comprising 11 593 children undergoing patch testing with 4176 (36%) PPTs were eligible for inclusion. The allergen with the highest prevalence was nickel (11.9% [95% confidence interval [CI], 8.6%-15.71%]), followed by cobalt (6.6% [95% CI, 4.2%-9.5%]), cocamidopropyl betaine (5.5% [95% CI, 3.1-8.7]), bacitracin (5.2% [95% CI, 1.2%-10.0%]), fragrance mix I (4.8% [95% CI, 2.9%-7.1%]) and methylisothiazolinone (4.3% [95% CI, 2.2%-7.2%]). Children with atopic dermatitis had higher rates of PPTs for cocamidopropyl betaine, propylene glycol, lanolin alcohol and carba mix. Across geographical areas, higher prevalences of several allergens were found in the United States compared to Europe, for example, for methylisothiazolinone. This meta-analysis confirmed that CA is frequent in children across geographical areas; however, differences in the frequency of top allergens depend on regulatory interventions, indicating their value.

Epidemiological and Occupational Pattern of Patch-Test Reactions to p-Tert-butylphenol-formaldehyde Resin in North-Eastern Italy, 1997-2021

Background. Skin contact with items containing p-tert-butylphenol-formaldehyde resin (PTBP-FR) may induce sensitization and allergic contact dermatitis (ACD). Methods. This multi-centric cross-sectional study investigated the prevalence of sensitization to PTBP-FR in 30,629 consecutive outpatients patch-tested during 1997-2021 in four research centers from Northern Italy: Padua; Pordenone; Trieste; and Trento/Bolzano/Rovigo. Patch tests were applied on the upper back of patients with suspected ACD. All patches were removed after 48 h and read at 72 or 96 h. Results. The overall prevalence of PTBP-FR sensitization was 1.11% (=341/30,629) of cases, with lower prevalence occurring in the Province of Trento/Bolzano/Rovigo (0.36%). The body area most frequently affected were the hands (36.32%), followed by face (19.52%) and legs (8.09%). During 1997-2004, the prevalence of PTBP-FR positivity was significantly lower in Trento/Bolzano/Rovigo (aOR = 0.19; 95%CI: 0.11; 0.35), whereas it was higher among restaurant workers (aOR = 2.44; 95%CI: 1.44; 4.13). During the entire study period (1997-2021), excluding Trento/Bolzano/Rovigo, PTBP-FR positivity significantly decreased in the period 2011-2021 (aOR = 052; 95%CI: 0.39; 0.69) compared to 1997-2010 in males (OR = 0.69; 95%CI: 0.52; 0.91). Conclusions. Females were likely to react to PTBP-FR at patch tests. Prevalence of PTBP-FR sensitization significantly decreased over time, possibly reflecting reduced occupational and non-occupational exposure due to replacement of the resin with other adhesive products (acrylates or epoxy agents).

Three Cases of Allergic Contact Dermatitis to 2-(Thiocyanomethylthio)benzothiazole in Leather Items

BACKGROUND

2-(Thiocyanomethylthio)benzothiazole (TCMTB) is a fungicide product widely used in the leather industry, particularly since the 1990s. However, reports of allergic contact dermatitis triggered by this chemical are scarce.

OBJECTIVES

To investigate three cases of dermatitis following contact with leather products, possibly related to TCMTB.

METHODS

Three female patients, aged 33-53, were referred with suspected allergic contact dermatitis related to leather products. Two patients presented with dermatitis on the feet, while one patient had dermatitis on the back and thighs. All patients were patch-tested with the European baseline series, a shoe series, TMCTB (0.1% pet), and scrapings from their personal leather products.

RESULTS

All patients showed reactions to the scrapings from their personal products (+ to ++) and to TCMTB (++ to +++). Additionally, one patient was sensitised to mercapto mix and mercaptobenzothiazole (both ++), while another reacted to chromium (++), cobalt (+), 4-tert-butylphenol-formaldehyde resin (+) and colophonium (++). All patients were advised to avoid TCMTB and to be cautious with leather, synthetic leather, and varnished wood.

CONCLUSIONS

If contact dermatitis related to leather exposure is suspected, patch testing with TCMTB 0.1% pet should be included, as it might be the only positive finding.

Skin sensitizers enhance superoxide formation by polycyclic aromatic hydrocarbons via the aldo-keto reductase pathway

Exposure to combustion-derived airborne polycyclic aromatic hydrocarbons (PAHs) may harm human skin, exacerbate cutaneous inflammatory diseases and accelerate skin aging. The toxicity of PAHs is unleashed upon their metabolic activation by cytochrome P450 (CYP) 1 monooxygenases, resulting in the formation of reactive intermediates that form mutagenic DNA adducts. Moreover, PAHs cause oxidative stress, which is primarily due to aldo-keto reductases (AKRs), such as AKR1C3, which convert CYP1-derived PAH-trans-diols to PAH-catechols. The catechols undergo autooxidation leading to the formation of reactive oxygen species (ROS) and PAH-quinones. The latter are highly reactive, mitotoxic and are reduced back to PAH-catechols, thus facilitating redox cycling. As AKR1C expression is inducible by other NRF2-stimulating chemicals, we tested the hypothesis that co-exposure of HaCaT keratinocytes to skin sensitizers and the PAH benzo[a]pyrene (BaP) enhances ROS formation. We observed a synergistic effect of the skin sensitizers on the BaP-induced expression of the NRF2 target genes heme oxygenase-1, sulfiredoxin-1 and AKR1C3. In fact, co-exposure to the skin sensitizers also enhanced the BaP-induced formation of superoxide anions. Intriguingly, the co-exposure-related ROS formation was abolished upon inhibition of either CYP1A1 or AKR1C3. Testing of additional skin-sensitizing compounds, differing in their mode of action, indicated that especially potent Michael acceptors enhance the toxicity of BaP by increasing AKR1C3 expression and, presumably, downstream BaP-quinone formation. Our study reveals potential health risks associated with the simultaneous exposure to common skin-sensitizing substances and ubiquitous PAHs, and implies a role for NRF2 in mediating PAH toxicity.

Prevalence, pattern, contact sensitisers and impact on quality-of-life of occupational dermatitis among beekeepers in North India

BACKGROUND

Beekeepers face specific occupational health risks due to exposure to bee products and chemicals. Propolis is a notable cause of contact hypersensitivity in beekeepers. Its chemical composition varies by region, complicating allergy investigations. While propolis allergies are documented in Western populations, no studies exist in India.

AIM

To assess the prevalence and patterns of dermatitis among beekeepers, identify contact sensitisers and evaluate its impact on quality-of-life (QoL).

METHODS

An 18-month community-based cross-sectional study was conducted involving 340 beekeepers from the Kashmir Valley in North India. Data collection included personal interviews, dermatological examinations and patch testing using self-made antigens of propolis, beeswax, royal jelly and standardised Baseline Indian Standard Series. The Dermatology Life Quality Index (DLQI) was used to measure the impact of dermatitis on QoL.

RESULTS

Dermatitis prevalence among beekeepers was 17.1%, with the majority presenting with hand eczema. Onset or worsening of dermatitis was reported by 77.6% after working in apiaries. Significant associations were found with duration of beekeeping (p < 0.05) and a history of atopy (p < 0.001). Patch testing revealed 27.5% of beekeepers with positive reactions, primarily to propolis (10% in pet). The mean DLQI score was 3.5, indicating a generally small impact on QoL.

CONCLUSION

Dermatitis was a common occupational condition among beekeepers, strongly associated with the duration of beekeeping and a history of atopy, though its overall impact on QoL was limited. Propolis emerged as a primary sensitiser in the study population.

Should Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde (Lyral®) still be part of the Baseline Series?

BACKGROUND AND OBJECTIVES

Hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC), or Lyral®, is a fragrance marker that is part of the Fragrance Mix II (FM II) and is still patched as an independent allergen within the European and other baseline series despite the European Commission banning its use in cosmetics in 2021. We aimed to study the prevalence of sensitization to the HICC in Spain and its simultaneous positivity with the FM II to determine whether it should be part of the Spanish baseline series.

MATERIAL AND METHOD

We analysed all consecutive patients simultaneously patch-tested with HICC and FM II within the Spanish Contact Dermatitis Registry (REIDAC) from June 1st, 2018 through December 31st, 2023.

RESULTS

A total of 96 (0.8%) out of 12,029 patients analysed yielded positive to HICC and 396 (3.3%) to FM II. In 53% and 64% of the patients, respectively, findings were considered currently relevant. A total of 72 out of 96 (75%) HICC positives would be detected if only FM II was patched.

CONCLUSIONS

Prevalence of HICC sensitization in Spain is low and has decreased in recent years. HICC is a prohibited fragrance in cosmetics and FM II detects 3 in 4 sensitized patients. Our results suggest that HICC should remain outside the Spanish baseline series and support its exclusion from the European baseline series.

Allergic contact dermatitis caused by glucose sensors and insulin pumps: A full review: Part 1: Sensors and pumps, adverse cutaneous reactions, allergens, and diabetes devices causing allergic contact dermatitis

During the past 8 years, a large number of reports have appeared on allergic contact dermatitis to glucose sensors and insulin pumps in paediatric and adult patients with type 1 diabetes mellitus. Isobornyl acrylate in one particular sensor sensitised many hundreds of (published) individuals, and many other allergens were discovered in a large number of sensors and pumps. Diagnostic procedures with patch tests proved very complicated, as manufacturers showed a serious lack of cooperation with dermatologists in providing information on the ingredients of their products and samples for patch testing. This two-part article provides a full and detailed review of all aspects of the subject of allergic contact dermatitis to glucose sensors and insulin pumps. Part 1 begins with a general introduction to sensors and pumps, followed by the cutaneous adverse reactions that they have caused and a full account of the allergens in the diabetes devices. In addition, an overview of the glucose sensors and insulin pumps that have caused allergic contact dermatitis is presented. Part 2 presents all published case reports and case series, clinical features of allergic contact dermatitis to sensors and pumps, patch test procedures, differentiation from irritant dermatitis, management of allergic patients and (proposed) legislation.

Evaluation of cellular and physiological alterations of cells from Mytilus galloprovincialis exposed to benzisothiazolinone

Benzisothiazolinone (BIT) is a preservative and antimicrobial agent widely used in various household and industrial products. It is readily detectable in pesticides, polishes, printing inks and detergents. This extensive use is reflected in a vast amount of this compound in the environment, which may cause toxic effects in organisms that come in contact with it. In light of the aforementioned context, this work aims to investigate the potential cellular and physiological impact on aquatic organisms through in vitro tests, utilising haemocytes and digestive gland (DG) cells derived from the Mediterranean mussel (Mytilus galloprovincialis). Two different concentrations (B1: 0.03 µg/L; B2: 0.3 µg/L) were tested at two different times of exposure (T1: 1 h; T2: 3 h) to evaluate the viability of cells, the phagocytic activity (haemocytes), the regulation volume decrease (RVD on DG cells) capability. Moreover, the cytoprotective mechanisms related to oxidative stress and detoxification were evaluated through the expression analysis by qPCR of key genes involved in these pathways. The most significant results obtained from these tests were the reduction of viability of haemocytes at T2 of exposure to B2, a decrease of vitality in DG cells exposed to B1 during the T1, the significant alteration in the phagocytosis activity, the upregulation of Cu/ZnSOD gene, the inhibition of the CYPY1 gene expression and upregulation of the Heat shock protein 70 (Hsp70) gene following the BIT exposure. These findings provide a valuable foundation for further investigation, offering insights into the potential impact of BIT on aquatic communities.

Pandemic of sensitivity to acrylate containing nail cosmetic among young Israeli women? Result of patch testing 2-hydroxyethyl methacrylate in the European baseline series

BACKGROUND

2-Hydroxyethyl methacrylate (HEMA) was added into the European baseline series (EBS) in 2019. There is limited data regarding the frequency, relevance, and sources of exposure to HEMA.

OBJECTIVES

To investigate the frequency and clinical relevance of positive reactions to HEMA in the EBS in Israel, and explore sources of exposure.

METHODS

Retrospective cohort study that included all patients who underwent patch testing with the EBS in a tertiary center in Israel between 2020 and 2023. Positive reactions to HEMA were stratified by sex, six age groups, and year of study. Sources of exposure to HEMA as well as occupational data were recorded.

RESULTS

A total of 1671 consecutive patients underwent HEMA patch testing, with 135 (8.1%) showing positive reactions to HEMA (130 females, 5 males). The prevalence in women (11.0%) was significantly higher compared to men (1.0%) (p < 0.001). Stratification by age and sex revealed the highest frequency of HEMA sensitivity of 16.7% among women younger than 30 years of age, with odds ratio of 2.3 (95%CI: 1.6-3.3, p < 0.001) compared to older women. There was an increase in frequency among women between the years 2022 and 2023 when compared to 2020-2021 (OR 1.7, 95%CI: 1.5-2.1, p < 0.01) attributable to COVID-19 pandemic and social restrictions. Among men the frequency fluctuations over the study period and age categories were nonsignificant. 111 (84%) were judged to be of clinical relevance and nail cosmetics was responsible for 95% of them. Of 111 patients with relevant reaction (110 females, 1 males), 20 (18%) had occupational contact dermatitis (18 nails stylists, 2 dentists). Other culprit products included sanitary pads (n = 4), medical adhesives (n = 3), and paints (n = 2).

CONCLUSION

We report the highest frequency of HEMA sensitivity to date of 8.1%, that was most common among young women and in vast majority of cases was attributable to nail cosmetics. Our findings reflect the popularity of nail cosmetics in Israel as well as the global trend of increasing sensitivity to (meth)acrylates.

Is the Use of the Extended (Meth)acrylate Series - Nails Justified? Characterization of Nail Acrylate Allergy in a Tertiary Medical Centre

Methacrylate allergy is a common cause of allergic contact dermatitis, and its incidence has surged over the past decade. Consequently, the primary sensitizing agent, 2-hydroxyethyl methacrylate, was recently added to the European Baseline Series of contact allergens. This study aimed to assess the added value of testing for allergens included in the (Meth)Acrylate Series - Nails, in addition to 2-hydroxyethyl methacrylate, as well as to characterize patients who may benefit from more extensive testing. A retrospective analysis of medical records of patch-tested patients was conducted between June 2013 and July 2022. Among the 3,828 patients who underwent patch testing, 396 were tested with the (Meth)Acrylate Series - Nails; 153 (38.6%) of those patients tested positive for at least 1 acrylate. The most common hapten was 2-hydroxyethyl methacrylate (85.6%), followed by hydroxypropyl methacrylate (85.0%) and ethylene glycol dimethacrylate (80.4%). In our study, 22/153 patients (14.4%) would have been missed if tested only for 2-hydroxyethyl methacrylate. The analysis showed that including hydroxypropyl methacrylate and ethylene glycol dimethacrylate improved detection rate to 98%, rendering the use of the entire tray unnecessary in most cases.

Chemical-Specific T Cell Tests Aim to Bridge a Gap in Skin Sensitization Evaluation

T cell activation is the final key event (KE4) in the adverse outcome pathway (AOP) of skin sensitization. However, validated new approach methodologies (NAMs) for evaluating this step are missing. Accordingly, chemicals that activate an unusually high frequency of T cells, as does the most prevalent metal allergen nickel, are not yet identified in a regulatory context. T cell reactivity to chemical sensitizers might be especially relevant in real-life scenarios, where skin injury, co-exposure to irritants in chemical mixtures, or infections may trigger the heterologous innate immune stimulation necessary to induce adaptive T cell responses. Additionally, cross-reactivity, which underlies cross-allergies, can only be assessed by T cell tests. To date, several experimental T cell tests are available that use primary naïve and memory CD4+ and CD8+ T cells from human blood. These include priming and lymphocyte proliferation tests and, most recently, activation-induced marker (AIM) assays. All approaches are challenged by chemical-mediated toxicity, inefficient or unknown generation of T cell epitopes, and a low throughput. Here, we summarize solutions and strategies to confirm in vitro T cell signals. Broader application and standardization are necessary to possibly define chemical applicability domains and to strengthen the role of T cell tests in regulatory risk assessment.

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.

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.

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.

A re-assessment of the value of markers of corticosteroid contact allergy in the Spanish baseline series: Clobetasol propionate in the spotlight

BACKGROUND

Budesonide and tixocortol pivalate as markers of contact allergy to corticosteroids have been questioned, as they are not able to detect a significant percentage of allergic patients.

OBJECTIVES

To investigate the potential role of clobetasol propionate in enhancing corticosteroid sensitisation detection.

METHODS

Between January 2022 and December 2023, patients who attended centres involved in the Spanish Registry of Research in Contact Dermatitis and Cutaneous Allergy were tested with an extended baseline series that included budesonide, tixocortol pivalate, clobetasol propionate 0.1% in ethanol and 1% in petrolatum.

RESULTS

A total of 4338 patients were tested. Twenty-four patients were allergic to budesonide (0.55%, 95% CI: 0.37-0.82); nine patients were allergic to tixocortol pivalate (0.21%, 95% CI: 0.11-0.39); and 23 patients were allergic to clobetasol (0.53%, 95% CI: 0.35-0.79). Only four of those patients allergic to clobetasol were detected by budesonide and one by tixocortol pivalate. No significant differences in the number of positive tests were found between clobetasol in petrolatum or ethanol.

CONCLUSIONS

In Spain budesonide remains the main corticosteroid allergy marker whereas the role of tixocortol pivalate is questionable. The addition of clobetasol propionate to the Spanish baseline series would improve the ability to detect patients allergic to corticosteroids.

Recognizing and Managing Allergic Contact Dermatitis: Focus on Major Allergens

Patch testing is the reference standard for the diagnosis of allergic contact dermatitis. Identification and avoidance of culprit allergens are essential in the treatment of this disease. Each year, new allergens are identified as emerging or important. The authors discuss allergens that are common, enduring, emergent, incompletely recognized, and controversial for the practicing allergist and dermatologist. This Clinical Management Review will encompass a review of fragrances, preservatives, rubber, acrylates, metals, and medications; their common sources of exposure; controversies in diagnosis and patch testing; management and how to avoid those allergens. This review will also include practical aspects of diagnosis and management and will provide resources that can be used as guidance for physicians and patients on nickel, methylchloroisothiazolinone/methylisothiazolinone, and fragrance, the most common allergens positive on patch testing.

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.

Allergic Contact Dermatitis to Acrylates: A Case Report

(Meth)acrylates are a common cause of allergic contact dermatitis (ACD) that can be found in medical (such as pads) and aesthetic (specifically nail cosmetics) products. Prolonged and intimate contact with sanitary pads can predispose individuals to ACD triggered by a variety of allergens. This report presents the case of a young female patient with episodes of nail contact dermatitis followed by a protracted history of intensely symptomatic allergic contact dermatitis affecting the external genital area, precipitated by methacrylates present in menstrual pads.

[Translated article] Standard and Expanded Series Patch Testing Update by the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC)

After the meeting held by the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC) back in October 2021, changes were suggested to the Spanish Standard Series patch testing. Hydroxyethyl methacrylate (2% pet.), textile dye mixt (6.6% pet.), linalool hydroperoxide (1% pet.), and limonene hydroperoxide (0.3% pet.) were, then, added to the series that agreed upon in 2016. Ethyldiamine and phenoxyethanol were excluded. Methyldibromoglutaronitrile, the mixture of sesquiterpene lactones, and hydroxyisohexyl 3-cyclohexene (Lyral) were also added to the extended Spanish series of 2022.

Standard and Expanded Series Patch Testing Update by the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC)

After the meeting held by the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC) back in October 2021, changes were suggested to the Spanish standard series patch testing. Hydroxyethyl methacrylate (2% pet.), textile dye mixt (6.6% pet.), linalool hydroperoxide (1% pet.), and limonene hydroperoxide (0.3% pet.) were, then, added to the series that agreed upon in 2016. Ethyldiamine and phenoxyethanol were excluded. Methyldibromoglutaronitrile, the mixture of sesquiterpene lactones, and hydroxyisohexyl 3-cyclohexene (Lyral) were alo added to the extended Spanish series of 2022.

Preservative contact allergy in occupational dermatitis: a machine learning analysis

Occupational dermatoses impose a significant socioeconomic burden. Allergic contact dermatitis related to occupation is prevalent among healthcare workers, cleaning service personnel, individuals in the beauty industry and industrial workers. Among risk factors, the exposure to preservatives is frequent, since they are extensively added in products for occupational use. The goal of this study is to investigate the contact allergy patterns in order to understand the linkage among hypersensitivity to preservatives, occupational profiles, patients' clinical and demographic characteristics. Patch test results were collected from monosensitized patients to Formaldehyde 2%, KATHON 0.02%, thimerosal 0.1%, and MDBGN 0.5%; information was also collected for an extended MOAHLFA (Male-Occupational-Atopic-Hand-Leg-Face-Age) index. To assess the relationship between allergen group and occupational-related ACD, the chi-square test for independence was utilized. To uncover underlying relationships in the data, multiple correspondence analysis (MCA) and categorical principal components analysis (CATPCA), which are machine learning approaches, were applied. Significant relationships were found between allergen group and: occupation class, atopy, hand, leg, facial, trunk, neck, head dermatitis, clinical characteristics, ICDRG 48 h and ICDRG 72 h clinical evaluation. MCA and CATPCA findings revealed a link among allergen group, occupation class, patients' demographic and clinical characteristics, the MOAHLFA index, and the ICDRG scores. Significant relationships were identified between the allergen group and various manifestations of dermatitis. The utilization of machine learning techniques facilitated the discernment of meaningful patterns in the data.

Results of patch testing with five fragrance materials hitherto not tested: A dose-finding study in the clinical population

BACKGROUND

Quantitative risk assessment (QRA) for skin sensitization is used to derive safe use levels of sensitising fragrance ingredients in products. Post-marketing surveillance of the prevalence of contact allergy to these ingredients provides relevant data to help evaluate the performance of these measures.

OBJECTIVES

To determine a suitable patch test concentration for five fragrance materials that had hitherto not been tested on a regular basis. These concentrations are then to be used in a surveillance study with patch testing consecutive patients over an extended monitoring period.

MATERIALS AND METHODS

Furaneol, CAS.3658-77-3; trans-2-hexenal, CAS.6728-26-3; 4,8-dimethyl-4,9-decadienal, CAS.71077-31-1; longifolene, CAS.475-20-7; benzaldehyde, CAS.10052-7, were patch tested with other fragrance allergens in four clinics. Patch testing was conducted in three rounds, starting with the lowest concentrations of the five ingredients. The doses were increased in the subsequent rounds if no late-appearing positive reactions and virtually no irritant reactions were reported.

RESULTS

Overall, 373 patients were tested. No positive allergic reaction was reported to the five ingredients. Patch test results of other fragrance allergens are reported.

CONCLUSIONS

The highest test concentrations are each considered safe for patch testing consecutive patients. Further surveillance based on these preparations will evaluate the hypothesis that QRA-driven consumer product levels of these fragrances can prevent sensitization.

Trends in contact sensitization, results, and implications from a contact dermatitis clinic in Israel

BACKGROUND

The baseline series includes common allergens, evolves over time, and differs by location. Our study aims to characterize allergen sensitization trends among the Israeli population during the last two decades, compare our results to American and European registries, as well as to highlight significant allergens in additional series outside the European baseline series (OEBS).

METHODS

We analysed patch test results of 2086 patients from a designated contact dermatitis clinic in Tel Aviv between 2019 and 2022, compared them to European and North American registries and to 2156 patch test results conducted in Israel two decades ago.

RESULTS

38.6% of patients had at least one positive reaction to an allergen in the European baseline series (EBS), nickel sulphate (14.6%), fragrance mix I (4.6%), and Methylchloroisothiazolinone methylisothiazolinone (MCI/MI; 3.7%) were the most common among them. N-Isopropyl N-Phenyl-4-Phenylenediamine (NIPPD; 0%), Propolis (0.1%), Sesquiterpene lactone mix (0.1%), and Budesonide (0.1%) elicited a sensitization frequency significantly lower than the proposed threshold for baseline inclusion. Chi-square test revealed a statistically significant decrease (p < 0.05) in the sensitization frequency of fragrance mix I, Formaldehyde, Potassium dichromate, Neomycin sulphate, Myroxylon pereirae, Sesquiterpene lactone, and NIPPD during the last two decades. The overall sensitization frequency to the majority of allergens was lower in our cohort in comparison to the North American and European registries.

CONCLUSIONS

MCI/MI and 2-hydroxyethyl methacrylate-2 (HEMA) are common, relevant allergens, with high SPIN (significance and prevalence index number) and should be better regulated by the authorities. While among the EBS, NIPPD, Propolis, Sesquiterpene lactone, and Budesonide usually do not elicit a positive reaction and therefore should be reconsidered in baseline series, among the OEBS, Chloramphenicol, Quaternium 15, Propyl gallate, and Amerchol L101 have elicited high SPIN values and should be vigilantly examined in the suitable clinical scenario. Significantly lower sensitization frequency to propolis raises the possibility of a protective effect due to early oral exposure among the Israeli population.

Increasing non-cosmetic exposure and sensitization to isothiazolinones require action for prevention: Review

Frequent use of methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) and MI in cosmetic products has been the main cause of widespread sensitization and allergic contact dermatitis to these preservatives (biocides). Their use in non-cosmetic products is also an important source of sensitization. Less is known about sensitization rates and use of benzisothiazolinone (BIT), octylisothiazolinone (OIT), and dichlorooctylisothiazolinone (DCOIT), which have never been permitted in cosmetic products in Europe. BIT and OIT have occasionally been routinely patch-tested. These preservatives are often used together in chemical products and articles. In this study, we review the occurrence of contact allergy to MI, BIT, OIT, and DCOIT over time, based on concomitant patch testing in large studies, and case reports. We review EU legislations, and we discuss the role of industry, regulators, and dermatology in prevention of sensitization and protection of health. The frequency of contact allergy to MI, BIT, and OIT has increased. The frequency of contact allergy to DCOIT is not known because it has seldom been patch-tested. Label information on isothiazolinones in chemical products and articles, irrespective of concentration, is required for assessment of relevance, information to patients, and avoidance of exposure and allergic contact dermatitis.

Declining frequency of sensitization to fragrance mixes I and II: IVDK-data of the years 2012-2021

BACKGROUND

EU Commission Regulation 2017/1410 prohibits using atranol and chloroatranol, the main allergens in Evernia prunastri (oakmoss), and hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC) in cosmetic products. Oakmoss absolute is contained in fragrance mix (FM) I and HICC in FM II which are patch tested as screening mixtures in the baseline series.

OBJECTIVE

To describe the time trends of reaction frequencies to both FMs as well as to their components in FM-positive patients.

METHODS

Retrospective analysis of data from the Information Network of Departments of Dermatology (IVDK), 2012-2021.

RESULTS

Positive reactions to FM I (FM II) declined from 9.1% (4.7%) in 2012 to 4.6% (3.0%) in 2021. Full breakdown tests were performed in 24% (FM I) and 31% (FM II), respectively, of the mix-positive patients. From this data, frequencies of sensitization to the 14 single fragrances of FM I and FM II were calculated. For the majority, a decline was noted from 2012/2013 to 2020/2021, for oakmoss absolute 1.9%-0.8% and for HICC 1.8%-0.9%.

CONCLUSION

EU Commission Regulation 2017/1410 was an effective measure. However, our data have some limitations, possibly causing underestimation of sensitization frequencies to fragrances.

2-Hydroxyethyl methacrylate (2-HEMA) sensitization, a global epidemic at its peak in Spain?

BACKGROUND

A global epidemic of allergic contact dermatitis to (meth)acrylates has been described in relation to the widespread use of manicure products.

OBJECTIVES

To evaluate the frequency of sensitization to 2-hydroxyethyl methacrylate (2-HEMA) among consecutively patch tested patients with eczema in Spain; the percentage of current relevance; the MOAHLFA index; and, the potential sources of exposure to (meth)acrylates.

METHODS

From January 2019 to December 2022, 2-HEMA 2% pet. was prospectively patch tested in 24 REIDAC (Spanish Allergic Contact Dermatitis Registry) centres.

RESULTS

Six thousand one hundred thirty-four patients were consecutively patch tested with 2-HEMA 2% pet. 265/6134 (4.3%) were positive. Positive reactions of current relevance were identified to involve 184/265 (69%). The efficiency (number of patch tests needed to detect relevant positive patch test reactions) was 34 (6134/184). The variable 'occupational' was found to be significantly associated with a higher risk for relevant positive reactions to 2-HEMA (OR: 10.9; 95% CI: 8.1-14.9).

CONCLUSION

(Meth)acrylate sensitization is a prevalent health issue in Spain. 2-HEMA 2% pet. has been identified to be a highly effective (meth)acrylate allergy marker in the GEIDAC baseline series. The responsible authorities should implement policies guaranteeing accurate labelling of industrial, medical, and consumer materials while ensuring the enforcement of said labelling through appropriate legal means.

Results of patch testing 2-hydroxyethyl methacrylate (HEMA) in the European baseline series: A 4-year retrospective study

BACKGROUND

2-Hydroxyethyl methacrylate (HEMA) was added to the European baseline series (EBS) in 2019. Few recent data are available on the frequency and relevance of positive reactions to this hapten.

OBJECTIVES

To investigate the frequency and relevance of positive patch tests to HEMA in the EBS in a university hospital in Amsterdam, The Netherlands.

PATIENTS AND METHODS

Retrospective study in patients with positive patch tests to HEMA investigated between June 2019 and August 2023.

RESULTS

Of 2927 consecutive patients, 88 (79 women and 9 men; 3.0%) had a positive reaction to HEMA. The prevalence in women was 3.9%, in men 1.0%. Forty-three (49%) reactions were judged to be of current clinical relevance and 21 (24%) of past relevance. In this group of 64 patients with relevant reactions, 18 (28%) had occupational contact with (meth)acrylate-containing products, of who 11 (61%) were nail stylists. In 46 patients with non-occupational allergic contact dermatitis, 31 (67%) had allergic reactions to nail cosmetics. Glues and glue-containing products accounted for 22% of the materials causing allergic contact dermatitis and dental products for 8%.

CONCLUSIONS

Allergic reactions to HEMA are very frequent in women investigated in Amsterdam. Nearly two thirds of cases were caused by nail cosmetics.

The new Italian SIDAPA Baseline Series for patch testing (2023): an update according to the new regulatory pathway for contact allergens

Allergic contact dermatitis (ACD) is a common inflammatory skin disease caused by delayed hypersensitivity to chemical and biotic contact allergens. ACD significantly affects the patients' quality of life negatively impacting both occupational and non-occupational settings. Patch testing is the gold standard diagnostic in vivo test to precise the ACD etiology and to correctly perform prevention. According to the Italian Medicines Agency (AIFA) legislative decree no. 178 of 29th May 1991, allergens are defined as medicines and therefore they are subject to strict regulation. In 2017, AIFA (decree no. 2130/2017) started a procedure to regulate contact allergens on the Italian market and actually the contact allergens temporarily authorized are reported in AIFA decree no. 98/2022, valid until November 2023. The availability on the market of contact allergens to diagnose ACD and continuous updating on the basis of new epidemiological trends are mandatory, jointly with the continuous update of the baseline and integrative series for patch testing. For this reason, the scientific community represented in Italy by the Skin Allergies Study Group of SIDeMaST (Italian Society of Dermatology and Venereology) and SIDAPA (Italian Society of Allergological, Occupational and Environmental Dermatology) are constantly working, in close relationship with the European scientific communities with large expertise in this important sector of the modern Dermatology. Herein, we report the setting up of regulatory legislation by AIFA and the new Italian Adult Baseline Series for patch testing.

Four-year Epidemiological Surveillance of the Spanish Registry of Research in Contact Dermatitis and Cutaneous Allergy: Current Situation and Trends

BACKGROUND

The epidemiological surveillance of contact dermatitis is one of the objectives of the Spanish Registry of Research in Contact Dermatitis and Cutaneous Allergy. Knowing whether the prevalence of positive tests to the different allergens changes over time is important for this monitoring process.

OBJECTIVES

To describe the various temporary trends in allergen positivity in the GEIDAC standard series from 2018 through December 31, 2022.

METHODS

This was a multicenter, observational trial of consecutive patients analyzed via patch tests as part of the study of possible allergic contact dermatitises collected prospectively within the Spanish Registry of Research in Contact Dermatitis and Cutaneous Allergy. The data was analyzed using 2 statistical tests: one homogeneity test (to describe the changes seen over time) and one trend test (to see whether the changes described followed a linear trend).

RESULTS

A total of 11327 patients were included in the study. Overall, the allergens associated with a highest sensitization were nickel sulfate, methylisothiazolinone, cobalt chloride, methylchloroisothiazolinone/methylisothiazolinone, and fragrance mix i. A statistically significant decrease was found in the percentage of methylisothiazolinone positive tests across the study years with an orderly trend.

CONCLUSIONS

Although various changes were seen in the sensitizations trends to several allergens of the standard testing, it became obvious that a high sensitization to nickel, methylchloroisothiazolinone/methylisothiazolinone and fragrances mix i remained. Only a significant downward trend was seen for methylisothiazolinone.

[Translated article] Four-year Epidemiological Surveillance of the Spanish Registry of Research in Contact Dermatitis and Cutaneous Allergy: Current Situation and Trends

BACKGROUND

The epidemiological surveillance of contact dermatitis is one of the objectives of the Spanish Registry of Research in Contact Dermatitis and Cutaneous Allergy. Knowing whether the prevalence of positive tests to the different allergens changes over time is important for this monitoring process.

OBJECTIVES

To describe the various temporary trends in allergen positivity in the GEIDAC standard series from 2018 through December 31, 2022.

METHODS

This was a multicenter, observational trial of consecutive patients analyzed via patch tests as part of the study of possible allergic contact dermatitises collected prospectively within the Spanish Registry of Research in Contact Dermatitis and Cutaneous Allergy. The data was analyzed using 2 statistical tests: one homogeneity test (to describe the changes seen over time) and one trend test (to see whether the changes described followed a linear trend).

RESULTS

A total of 11327 patients were included in the study. Overall, the allergens associated with a highest sensitization were nickel sulfate, methylisothiazolinone, cobalt chloride, methylchloroisothiazolinone/methylisothiazolinone, and fragrance mix i. A statistically significant decrease was found in the percentage of methylisothiazolinone positive tests across the study years with an orderly trend.

CONCLUSIONS

Although various changes were seen in the sensitizations trends to several allergens of the standard testing, it became obvious that a high sensitization to nickel, methylchloroisothiazolinone/methylisothiazolinone and fragrances mix i remained. Only a significant downward trend was seen for methylisothiazolinone.

Sensitization to ethylenediamine dihydrochloride in patients with contact dermatitis in northeastern Italy from 1996 to 2021

BACKGROUND

Ethylenediamine dihydrochloride is a versatile aliphatic amine found in numerous medications and industrial compounds and is a known sensitiser. The sensitization prevalence is affected by geographical and socio-cultural factors.

OBJECTIVES

The objectives are to analyse the temporal trend of sensitization to ethylenediamine dihydrochloride in northeastern Italy and to investigate associations with occupations.

METHODS

Between 1996 and 2021, 30 629 patients with suspected allergic contact dermatitis were patch tested with the Triveneto baseline series. Individual characteristics were collected through a standardised questionnaire.

RESULTS

The overall prevalence of ethylenediamine dihydrochloride sensitization was 1.29% with percentages similar in both sexes. We observed a significant decreasing trend over time (p < 0.001), yielding a sensitization prevalence <1% in recent years. Among departments, residence in Pordenone area was protective for sensitization. No significant associations were observed with specific occupations. We found significant associations between ethylenediamine dihydrochloride sensitization and being 26-35 years old (odds ratio [OR], 1.47; 95% confidence interval [CI]: 1.05-2.08), and sensitization for many haptens, such as paraben mix (OR, 5.3; 95% CI: 3.3-8.5), epoxy resin (OR, 5.1; 95% CI: 3.0-8.7), neomycin sulphate and mercaptobenzothiazole.

CONCLUSIONS

Our study showed a downward time trend of ethylenediamine dihydrochloride sensitization in northeastern Italian population and pointed to an update of the Triveneto baseline series.

2-Hydroxyethyl methacrylate (HEMA): A clinical review of contact allergy and allergic contact dermatitis. Part 2. Cross- and co-sensitization, other skin reactions to HEMA, position of HEMA among (meth)acrylates, sensitivity as screening agent, presence of HEMA in commercial products and practical information on patch test procedures

This is the second part of a literature review of the clinical aspects of contact allergy to and allergic contact dermatitis from 2-hydroxyethyl methacrylate (HEMA). Topics include cross- and co-sensitization, atypical manifestations of contact allergy, frequency of positive patch tests to HEMA compared with other (meth)acrylates, sensitivity of HEMA as a screening agent, the presence of HEMA in commercial products, and practical information on patch testing procedures. Primary sensitization to methacrylates including HEMA may result in methacrylate and acrylate cross-sensitization. There is a strong cross-allergy between HEMA, ethylene glycol dimethacrylate (EGDMA), and hydroxypropyl methacrylate; many reactions to EGDMA are cross-reactions to primary HEMA sensitization. Rare atypical manifestations of HEMA-allergy include lichen planus, lymphomatoid papulosis, systemic contact dermatitis, leukoderma after positive patch tests, and systemic side effects such as nausea, diarrhoea, malaise, and palpitations. The occurrence of respiratory disease caused by methacrylates such as asthma is not infrequent. HEMA is the most frequently patch test-positive methacrylate. It is a good screening agent for allergy to other (meth)acrylates. Patch test sensitization to HEMA 2% pet. is extremely rare. There are (some) indications that HEMA is frequently used in dental products and nail cosmetics.

The sesquiterpene lactone mix: A review of past, present and future aspects

The sesquiterpene lactones (SLs) are secondary plant metabolites, which are widespread in the Compositae/Asteraceae plant family. The first SLs were detected more than 100 years ago, and allergic contact dermatitis from Compositae has been reported since the beginning of the 1900s, but it was not until the late 1960s and early 1970s that a collaboration between dermatologists, chemists and botanists led to the detection of SLs as the main allergens of Compositae plants. In the 1980s, the SL mix, consisting of equimolar amounts of alantolactone, costunolide and dehydrocostus lactone, was developed as a screening agent for Compositae sensitisation. Today, after inclusion of SL mix in the baseline series, the mean prevalence of reactions in Europe is around 1%, and in North America 0.8%. In countries outside Europe and North America, the prevalence ranges between 0% and 10.7%. The detection rate of SL mix is lower than that of some plant extracts, and ideally, SL mix should be supplemented with a mix of SLs from locally prevalent allergenic plants. The prevalence of positive reactions to SL mix suggests continued baseline testing in most European countries, North America, New Zealand, Australia and probably some Chinese centres.

2-Hydroxyethyl methacrylate (HEMA): A clinical review of contact allergy and allergic contact dermatitis-Part 1. Introduction, epidemiology, case series and case reports

2-Hydroxyethyl methacrylate (HEMA) has been increasingly recognised as a contact allergen and was added to the European baseline series in 2019. In this article (2 parts), the results of an extensive literature review of the clinical aspects of contact allergy/allergic contact dermatitis to HEMA are presented. In part 1, the epidemiology of HEMA contact allergy is discussed and detailed information on published case series and case reports presented. HEMA is an important cause of contact allergy/allergic contact dermatitis in North America and Europe with recent prevalences of >3% in the USA + Canada and 1.5%-3.7% in Europe. Currently, most cases are caused by nail cosmetics, both in consumers and professional nail stylists. In our literature review, we have found 24 studies presenting case series of patients with allergic contact dermatitis attributed to HEMA and 168 case reports. However, the presence of HEMA in the products causing ACD was established in only a minority. Part 2 will discuss cross- and co-sensitisation, and other skin reactions to HEMA, will assess whether HEMA is the most frequent (meth)acrylate allergen and how sensitive HEMA as a screening agent is, investigate the presence of HEMA in commercial products and provide practical information on patch testing procedures.

Patch Testing to Paraphenylenediamine: The North American Contact Dermatitis Group Experience (1994-2018)

Background/Objectives: Paraphenylenediamine (PPD) is an aromatic amine dye that may cause allergic contact dermatitis. This study examines the epidemiology of allergic patch test reactions to PPD. Methods: This retrospective analysis characterizes individuals tested to PPD (1% petrolatum) by the North American Contact Dermatitis Group (1994-2018). Demographics and dermatitis site(s) were compared between PPD-allergic and PPD-negative patients. PPD reactions were analyzed by reaction strength, clinical relevance, occupational relatedness, and source as well as coreactivity with structurally related compounds. Results: Of 54,917 patients tested to PPD, 3095 (5.6%) had an allergic patch test reaction. Compared with PPD-negative patients, PPD-allergic patients had significantly greater odds of age >40 years (odds ratio [OR] 1.55 [95% confidence interval; CI 1.43-1.69]) and female gender (OR 1.52 [95% CI 1.41-1.66]), but lower odds of being White (OR 0.66 [95% CI 0.60-0.71]). The most common primary anatomic sites of dermatitis were face (25.5%), hands (21.9%), and scattered/generalized pattern (15.5%). Over half (55.3%) of PPD reactions were ++ or +++ at the final reading and 60.9% were currently relevant. Common exposure sources included hair dye (73.5%) and clothing/shoes/apparel (3.9%). Occupationally related reactions occurred in 8.3%, most commonly in hairdressers/cosmetologists (72.8%). The most common coreactions were benzocaine (11.3%), N-isopropyl-N'-phenyl-p-phenylenediamine (6.7%), disperse dye mix (6.5%), and black rubber mix (5.1%). Conclusions: The 24-year percentage of allergic reactions to PPD was 5.6%. PPD allergy was associated with female gender and age >40 years. PPD allergic patients were less likely to be White. Allergic reactions were usually clinically relevant and hair dye was the most frequently identified source.

Risk management of skin sensitisers: A commentary

Historically, allergic contact dermatitis (ACD) to chemicals encouraged hazard identification improvements, more sophisticated risk assessment and implementation of regulatory strategies, including banning of specific sensitising substances. The validation process applied to hazard identification methods demonstrates their accuracy; their use to characterise sensitiser potency facilitates quantitative and transparent risk assessment. Diagnostic patch testing at dermatology clinics worldwide delivers feedback showing where risk assessment/management has been insufficient or did not target the exposure of concern, thereby facilitating improvements. When urgent action to protect human health was required, regulations limited/banned, specific skin sensitisers. This can be seen in practice with the fragrance industry, a known source of ACD, thus requiring risk management, usually restrictions to limit allergy induction, and very rarely specific bans on ingredients. Experience and development of more sophisticated tools, e.g. to assess aggregate exposure from multitude of consumer product types, has led to repeated adaptation of risk assessment and promulgation of updated fragrance use limits. Although targeted control may not always lead to rapid change in the overall clinical picture, it is preferable to a blanket undifferentiated regulatory control of all sensitisers, resulting in unwarranted restrictions for many uses of no health concern, with consequent substantial socio-economic impacts.

The European baseline series and recommended additions: 2023

The European baseline series was last updated in 2019. This article discusses the reasoning behind a further iteration of the series for 2023.