Allergic contact dermatitis caused by hydroperoxides of limonene and dose‐response relationship—A repeated open application test (ROAT) study

Fragrance Contact Allergy - A Review Focusing on Patch Testing

Fragrance materials are widely used in various types of products in daily life and many of them can be contact sensitizers. Contact allergy to fragrances has been reported to be common worldwide. Unlike other groups of contact allergens such as metals and preservatives, fragrance materials in consumer products can be present as single fragrance chemicals or in the form of mixtures known as natural complex substances. Due to the complexity of the fragrance materials and the high number of fragrance substances known to cause contact sensitization, selecting suitable materials for patch testing is challenging. Emerging fragrance markers have been additionally introduced in different baseline series for screening to enhance the rate of fragrance contact allergy detection. Moreover, there have been continual updates on basic knowledge, clinical perspectives, sources of exposure, and regulations on the use of fragrance materials. Avoiding pitfalls while performing patch testing with fragrance test materials is also crucial and should not be overlooked. Therefore, this review aims to update knowledge to provide a high-quality holistic approach to fragrance contact allergy diagnosis and management.

Allergic Contact Dermatitis to Linalool Hydroperoxides: Pitfalls in the Diagnostic Process-Findings from a Repeated Open Application Test Study

Background: Increasing trends of oxidized linalool contact allergy have been reported. However, the impact of reactivity and dose in eliciting allergic contact Dermatitis caused by linalool hydroperoxides is insufficiently investigated. Objectives: To perform repeated open application tests (ROATs) using the real-world concentrations of linalool hydroperoxides in patients and control participants. Materials and Methods: Patients who previously had a positive (patients) and a negative (controls) patch test reaction to linalool hydroperoxides 1.0% in petrolatum were patch tested with a dilution series of linalool hydroperoxides preparations and asked to perform ROAT twice daily with 3 concentrations of linalool hydroperoxides creams and a negative control cream for 28 days. The creams contain 44, 140, and 440 PPM of linalool hydroperoxides, representing real-world doses reported in consumer products. Results: Of all 47 participants, 31 were linalool hydroperoxides contact allergy patients, and 16 were controls. One patient had a positive ROAT reaction in the area where cream at the highest concentration of linalool hydroperoxides was applied for 28 days. Conclusions: Repeated exposure to creams containing linalool hydroperoxides at real-life concentrations could rarely elicit an allergic reaction on intact skin after 4 weeks.

Fragrance allergens in cosmetic products marketed for children in Denmark

BACKGROUND

Fragrances are among the most common contact allergens in children. Cosmetic products are the most frequent source of skin exposure.

OBJECTIVE

To investigate exposure to fragrance allergens among Danish children, based on a sample of 1179 cosmetic products marketed for children.

METHODS

Information regarding cosmetic products marketed to children was obtained using a non-profit smartphone application registry, with data from December 2015 to November 2022.

RESULTS

The number of validated products was 26  537, of which 1349 marketed for children. After elimination of duplicates, 1179 (4.4%) individual products remained. The majority 53.8% (634/1179) of the products were fragranced. The highest frequency of declared fragrances was found in 'Facial care'-products: 93.0% (80/86), of which 97.7% were lip balms. The highest number of labelled fragrances in one single product (n = 16) was found in a baby perfume. Fragrance mix I (FMI) or II (FMII) allergens were found in 25.3% (298/1179) of the products. Limonene and linalool were the two most frequently labelled fragrance allergens.

CONCLUSION

Children can be exposed to a vast number of fragrance allergens from scented cosmetic products. Allergens from FM I and FMII are widely used in cosmetic products marketed to children. Patch testing with FMI and FMII remains relevant in children.

Patch testing hydroperoxides of limonene and linalool in consecutive patients-Results of the IVDK 2018-2020

BACKGROUND

Hydroperoxides of limonene (Lim-OOHs) and linalool (Lin-OOHs) are potent contact sensitizers.

OBJECTIVES

To investigate the prevalence of positive patch test (PT) reactions to Lim-OOHs and Lin-OOHs in consecutive patients, their demographic factors and concomitant reactions.

METHODS

Between 7/2018 and 12/2020, Lim-OOHs 0.3% pet. and Lin-OOHs 1% pet. were patch tested in 5511 consecutive patients. We assessed PT reactivity and analysed data from patients with either positive or negative PTs to Lim-OOHs and Lin-OOHs.

RESULTS

Positive PT results to Lim-OOHs (n = 170, 3.1%) and Lin-OOHs (n = 483, 8.8%) were frequent. Most of the positive reactions were weak (LimOOHs n = 134/LinOOHs n = 429), and even more frequently, doubtful (n = 252/n = 578) or irritant reactions (n = 81/n = 178) were documented. PT reactivity to Lim-OOHs and Lin-OOHs was increased in patients with irritant reactions to sodium lauryl sulphate (SLS). The proportion of leg dermatitis and concomitant positive reactions to fragrances and essential oils was increased in patients with reactivity to these hydroperoxides.

CONCLUSION

The observed reaction pattern suggests that both test preparations display an irritant potential with an increased risk of false positive reactions. Preparations should be chemically monitored in order to reduce irritancy. Mindful interpretation of PT results and aimed patch testing of lower concentrations is recommended.

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.

Contact sensitization to essential oils: IVDK-data of the years 2010 - 2019

BACKGROUND

Essential oils (EOs) are widely used in cosmetics, perfumes, massage fluids, aroma therapy, and natural medicine. Some essential oils contain contact sensitizers.

OBJECTIVES

To describe the frequency of sensitization to EOs in dermatitis patients presenting in skin clinics including concomitant reactions, to evaluate the EO patch test preparations, and to identify patient groups with an increased risk of EO sensitization.

PATIENTS AND METHODS

Retrospective analysis of data from the Information Network of Departments of Dermatology (IVDK), 2010-2019.

RESULTS

Twelve EOs were patch tested in an aimed manner in 10 930 patients, of whom 908 (8.3%) reacted to at least one EO. Only 6 EOs elicited more than 1% positive patch test reactions: ylang ylang (I + II) oil (3.9%), lemongrass oil (2.6%), jasmine absolute (1.8%), sandalwood oil (1.8%), clove oil (1.6%), and neroli oil (1.1%). Concomitant reactions among EOs or to EOs and fragrances were frequent. Among EO-positive patients, women, leg dermatitis patients, patients aged 40 years or more, masseurs and cosmeticians were over-represented.

CONCLUSIONS

Sensitization to EOs occurs, albeit infrequently in most cases. Masseurs and cosmeticians have an increased risk of sensitization to EOs. This article is protected by copyright. All rights reserved.

Novel insights into contact dermatitis

Contact dermatitis is a common disease, caused by repeated skin contact to contact allergens or irritants, resulting in allergic contact dermatitis (ACD) and/or irritant contact dermatitis. Attempts have been made to identify biomarkers to distinguish irritant and allergic patch test reactions, which could aid diagnosis. Some promising candidates have recently been identified, but verification and validation in clinical cases still need to be done. New causes of ACD are constantly recognized. In this review, 10 new contact allergens from recent years, were identified, several relating to anti-age products. Frequent allergens causing considerable morbidity in the population such as the preservative methylisothiazolinone (MI) have been regulated in EU. A significant drop in cases has been seen, while high rates are still occurring in other areas such as North America. Other frequent causes are fragrance allergens especially widely used terpenes and acrylates used in medical devises for control of diabetes. These represent unsolved problems. Recent advances in immunology have opened for a better understanding of the complexity of contact dermatitis, especially ACD. The disease may be more heterogenous that previous understood with several subtypes. With the rapidly evolving molecular understanding of the disease, the potential for development of new drugs for personalized treatment of contact dermatitis is considerable.

Limonene and linalool hydroperoxides review: pros and cons for routine patch testing

Limonene and linalool are among the most common fragrance terpenes used in products of everyday life. They are pre-haptens forming hydroperoxides (Lim-OOHs, Lin-OOHs) upon oxidation inducing frequent positive patch test reactions in patients with dermatitis. Still, they are not yet routinely tested in Europe. This review evaluates the patch testing experience with Lim-OOHs and Lin-OOHs by answering key questions such as whether hydroperoxide patch testing is warranted, understand difficulties or challenges related to the reading and interpretation of hydroperoxide patch test results with currently available material, assessing their relevance. Studies are increasingly pointing out to high percentages of positive reactions in patients consecutively patch tested with these oxidized products. An association between a positive clinical history and a strong patch test reaction has been described, but problems with doubtful/irritant reactions have also been reported. Considering the high frequencies of relevant positive reactions, the incorporation of Lim-OOHs 0.3% and Lin-OOHs 1% in the baseline series could be discussed and is maybe justified. Since exposure, sensitization and elicitation limits of Lim-OOHs and Lin-OOHs in the products still need to be better determined, an assessment of previous exposure, possible sensitizations and reactions may help to improve the clinical assessment. This article is protected by copyright. All rights reserved.

What is the added value of patch testing with 30 fragrance allergens in addition to the European baseline series?

Background

Patch testing with the fragrance allergy markers in the European baseline series (EBS) does not identify all patients with fragrance allergy. Hydroperoxides of linalool and limonene have been shown to be useful allergens in detecting fragrance sensitization.

Objectives

To evaluate the added value of testing with 30 fragrance allergens in addition to the EBS.

Methods

All patients with suspected fragrance allergy who underwent patch testing at the Amsterdam University Medical Centers between November 2019 and January 2021 to the EBS and fragrance series were included.

Results

Of 323 patients tested, 162 (50.2%) were found to be fragrance sensitized. The most sensitizing single allergens were the hydroperoxides of linalool (1.0 and 0.5% pet.) and limonene (0.3 and 0.2% pet.). Testing with the hydroperoxides of linalool and limonene identified 62 fragrance‐sensitized patients (38.3%) who could not be detected by the common fragrance markers. Of all fragrance‐sensitized patients, 21 (13.0%) would have been missed when not testing with the fragrance series.

Conclusions

Patch testing with the fragrance series in addition to the EBS is valuable. To reduce the risk of false‐negative reactions, it is advisable to test the hydroperoxides of linalool and limonene.

Highlights

Of the 323 patients with suspected fragrance allergy, 162 (50.2%) were found to be fragrance sensitized.

Testing with the hydroperoxides of linalool and limonene identified 62 fragrance‐sensitized patients (38.3%) who could not be detected by the European baseline series (EBS) fragrance markers. When not tested with the fragrance series, 21 (13.0%) of the sensitized patients would have been missed.

Routinely performing patch testing with the fragrance series in addition to linalool and limonene hydroperoxide as part of the EBS is recommended.

European patch test results with audit allergens as candidates for inclusion in the European Baseline Series, 2019/20 - Joint results of the ESSCAA and the EBSB working groups of the ESCD, and the GEIDACC

BACKGROUND

In 2019, a number of allergens (haptens), henceforth, 'the audit allergens,' were considered as potential additions to the European baseline series (EBS), namely, sodium metabisulfite, 2-bromo-2-nitropropane-1,3-diol, diazolidinyl urea, imidazolidinyl urea, Compositae mix II (2.5 or 5% pet), linalool hydroperoxides (lin-OOH), limonene hydroperoxides (lim-OOH), benzisothiazolinone (BIT), octylisothiazolinone (OIT), decyl glucoside, lauryl glucoside; Evernia furfuracea (tree moss), was additionally tested by some departments, too.

OBJECTIVES

To collect further data on patch test reactivity and clinical relevance of the audit allergens in consecutive patients across Europe.

METHODS

Patch test data covering the audit allergens in 2019 and 2020 were collected by those departments of the ESSCA testing these, as well as further collaborators from the EBS working group of the ESCD, and the Spanish GEIDAC. As patch test outcome, reactions between day (D) 3 and D5 were considered.

RESULTS

Altogether n=12403 patients were tested with any of the audit allergen. Positive reactions were most common to lin-OOH 1% pet. (8.74 (8.14-9.37)), followed by lin-OOH 0.5% pet., and lim-OOH 0.3% pet (5.41 (4.95-5.89)). Beyond these terpene hydroperoxides, BIT 0.1% pet. was the second most common allergen with 4.72 (4.2-5.28), followed by sodium metabisulfite 1% pet. (3.75 (3.32-4.23)) and Compositae mix 5% pet. (2.31 (1.84-2.87). For some allergens, clinical relevance was frequently difficult to ascertain.

CONCLUSIONS

Despite many positive patch test reactions, it remains controversial whether lin- and lim-OOH should be tested routinely, while at least the two preservatives BIT and sodium metabisulfite appear suitable. The present results are a basis for further discussion among the ESCD members and ultimately decision on their implementation into routine testing. This article is protected by copyright. All rights reserved.

Electron paramagnetic resonance and spin trapping to detect free radicals from allergenic hydroperoxides in contact with the skin: from the molecule to the tissue

A major research topic consists of revealing the contribution of radical-mediated reactions in dermatological diseases related to xenobiotic-induced stress, to succeed risk assessment procedures protecting producers and consumers. Allergic contact dermatitis is the clinically relevant consequence of skin sensitization, one of the most critical occupational and environmental health issues related to xenobiotics exposure. The first key event identified for the skin sensitization process to a chemical is its aptitude to react with epidermal proteins and form antigenic structures that will further trigger the immune response. Many chemical sensitizers are suspected to react through mechanisms involving radical intermediates. This review focuses on recent progress we have accomplished over the last few years studying radical intermediates derived from skin sensitizing chemicals by electron paramagnetic resonance in combination with the spin trapping technique. Our work is carried out "from the molecule", performing studies in solution, "to the tissue", by the development of a methodology on a reconstructed human epidermis model, very close in terms of histology and metabolic/enzymatic activity to real human epidermis, that can be used as suitable biological tissue model. The benefits are to test chemicals under conditions close to human use and real-life sensitization exposures and benefit from the 3D microenvironment. This article is protected by copyright. All rights reserved.

Unique molecular signatures typify skin inflammation induced by chemical allergens and irritants

BACKGROUND

Skin exposure to chemicals may induce an inflammatory disease known as contact dermatitis (CD). Distinguishing the allergic and irritant forms of CD often proves challenging in the clinic.

METHODS

To characterize the molecular signatures of chemical-induced skin inflammation, we conducted a comprehensive transcriptomic analysis on the skin lesions of 47 patients with positive patch tests to reference contact allergens and nonallergenic irritants.

RESULTS

A clear segregation was observed between allergen- and irritant-induced gene profiles. Distinct modules pertaining to the epidermal compartment, metabolism, and proliferation were induced by both contact allergens and irritants; whereas only contact allergens prompted strong activation of adaptive immunity, notably of cytotoxic T-cell responses. Our results also confirmed that: (a) unique pathways characterize allergen- and irritant-induced dermatitis; (b) the intensity of the clinical reaction correlates with the magnitude of immune activation. Finally, using a machine-learning approach, we identified and validated several minimal combinations of biomarkers to distinguish contact allergy from irritation.

CONCLUSION

These results highlight the value of molecular profiling of chemical-induced skin inflammation for improving the diagnosis of allergic versus irritant contact dermatitis.

Allergic contact dermatitis from ("hypoallergenic") adhesives containing D-limonene

BACKGROUND

Besides being a potential component of (some species of) colophonium, D-limonene is also used as a tackifier in the production of adhesives. Hydroperoxides of limonene are well-known skin sensitizers.

OBJECTIVES

To show that D-limonene may be present in colophonium-containing but also colophonium-free ("hypoallergenic") adhesives, and that patients suffering from allergic contact dermatitis (ACD) from both types of adhesives might display positive patch test reactions to limonene hydroperoxides in this regard.

METHODS

Five patients with suspected ACD from adhesives were patch tested to the baseline series (containing limonene hydroperoxides 0.3 and 0.2% pet.), additional series and, if available, to the culprit adhesives. The adhesives labelled as containing colophonium (n = 3) or free from it (n = 2) were analysed with gas chromatography - mass spectrometry (GC-MS) for the presence of D-limonene.

RESULTS

All five patients sensitised to adhesives had (strong) positive patch test reactions to limonene hydroperoxides. The presence of D-limonene, and/or related components, could be demonstrated in all three colophonium-containing and, surprisingly, also in two colophonium-free ("hypoallergenic") tapes.

CONCLUSIONS

D-limonene may be present in both regular and "hypoallergenic" adhesives, with limonene hydroperoxides potentially contributing to ACD from such medical devices. The use of fragrance chemicals in adhesives deserves further research.

Contact allergy to oxidized linalool and oxidized limonene: Patch testing in consecutive patients with dermatitis

BACKGROUND

Contact allergy to oxidized (ox.) linalool and ox. limonene has been reported to have a high prevalence, raising the question of inclusion into the baseline series. However, several important issues should be clarified and further investigated before inclusion can be warranted.

OBJECTIVES

To report the trends of ox. terpenes allergy in patients with dermatitis, features of the patch test reactions, and clinical characteristics of the patients.

METHODS

A retrospective analysis of 5773 patients was performed. All patients were patch tested with baseline series, individual ingredients of fragrance mix I and II, ox. linalool, and ox. limonene from 2013 to 2020.

RESULTS

The prevalence rates of contact allergy to ox. linalool and ox. limonene were 7.0% and 5.1%, respectively. Significantly increasing trends of contact allergy were observed. More than 95% of contact allergy cases were identified on Day 3/4. Patients with contact allergy to ox. linalool and ox. limonene were significantly younger than those with contact allergy to other fragrances and were predominantly female. Strong reactions were associated with older age and multiple fragrance allergies.

CONCLUSIONS

Contact allergy to ox. linalool and ox. limonene is becoming increasingly important, and findings show intriguing features. More studies concerning the clinical relevance before recommending these substances for screening are required.

Does aluminium in sunscreens cause dermatitis in children with aluminium contact allergy: A repeated open application test study

BACKGROUND

Parents report that children with aluminium contact allergy and vaccination granulomas may react to aluminium-containing sunscreen following application.

OBJECTIVES

To evaluate whether contact dermatitis develops following repeated application of aluminium-containing sunscreens in children with aluminium sensitization and vaccination granulomas.

METHODS

Sixteen children aged 2-9 years (mean age 5 years) with vaccination granulomas and a positive patch test reaction to aluminium chloride hexahydrate 2%/10% petrolatum completed a blinded repeated open application test (ROAT) with two daily applications of two sunscreens for 14 days. One cream contained aluminium and the other did not. The children served as their own controls.

RESULTS

Sixteen children completed the study. Only one child (6%) had a positive skin reaction during ROAT on day 2 to the sunscreen with aluminium. None reacted to the sunscreen without aluminium.

CONCLUSIONS

Use of aluminium-containing sunscreens may on a case basis lead to allergic contact dermatitis in aluminium allergic children.

One hundred years of allergic contact dermatitis due to oxidized terpenes: What we can learn from old research on turpentine allergy

Although in recent years the focus on sensitizing terpene oxidation products has been on oxidized limonene and linalool, the autoxidation of terpenes in relation to allergic contact dermatitis is not new and dates back to the early part of the 20th century with the use of turpentine causing occupational contact dermatitis in painters. This review is written in a way as to allow us to get closer to the work of the scientists in earlier days, to participate in the successes, and also to observe the weak points. The researchers concluded that the main culprit in Scandinavian turpentine was Δ³ -carene hydroperoxides. This explains its high sensitizing effect compared with French turpentine which is of the Iberian type with no or only traces of Δ³ -carene. Historical exposure to turpentine showed that ending the industrial exposure stopped the occupational skin sensitization. Patch test studies demonstrated that monoterpene hydroperoxides, far from being an obsolete source of contact allergy solely related to turpentine, is a common cause of contact allergy in the population. A hundred years of extensive chemical and clinical studies worldwide should be sufficient to meet the evidence requirement regarding allergic contact dermatitis caused by terpenes. HIGHLIGHTS: The autoxidation of terpenes in relation to allergic contact dermatitis is not new and dates back to the early part of the 20th century with the use of turpentine. The main culprit in Scandinavian turpentine was Δ³ -carene hydroperoxides. This explains its high sensitizing effect compared with French turpentine with no or only traces of Δ³ -carene. Recent patch test studies demonstrated that monoterpene hydroperoxides, far from being an obsolete source of contact allergy solely related to turpentine, is a common cause of contact allergy in the population.

Candidate Allergens for Inclusion in the Spanish Standard Series Based on Data from the Spanish Contact Dermatitis Registry

BACKGROUND

Standard patch test series must be updated using objective data on allergen sensitization. The Spanish standard series was last updated in 2016 and the European series in 2019, and the inclusion of several emerging allergens needs to be evaluated.

MATERIAL AND METHODS

We conducted a prospective, observational, multicenter study of consecutive patients from the registry of the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC) who were patch tested in 2019 and 2020 with linalool hydroperoxide, limonene hydroperoxide, 2-hydroxyethyl-methacrylate, benzisothiazolinone, octylisothiazolinone, textile dye mix (TDM), sodium metabisulfite, propolis, bronopol, Compositae mix II, diazolidinyl urea, imidazolidinyl urea, decyl glucoside, and lauryl glucoside.

RESULTS

We analyzed data for 4654 patients tested with diazolidinyl urea, imidazolidinyl urea, and bronopol, and 1890 tested with the other allergens. The values for the MOAHLFA index components were 30% for male, 18% for occupational dermatitis, 15% for atopic dermatitis, 29% for hand, 6.5% for leg, 23% for face, and 68% for age > 40 years. Sensitization rates above 1% were observed for 7 allergens: linalool hydroperoxide, 2-hydroxyethyl-methacrylate, benzisothiazolinone, limonene hydroperoxide, TDM, sodium metabisulfite, and propolis. Three allergens had a current relevance rate of over 1%: linalool hydroperoxide, 2-hydroxyethyl-methacrylat, and limonene hydroperoxide. Benzisothiazolinone and TDM had a relevance rate of between 0.9% and 1%.

CONCLUSIONS

Our results indicate that 7 new allergens should be considered when extending the Spanish standard patch test series. The data from our series could be helpful for guiding the next extension of the European baseline series.

Validation of questionnaire algorithm based on repeated open application testing with the constituents of fragrance mix II: the EDEN Fragrance Study

BACKGROUND

In a European study on contact allergy in the general population, it has been hypothesized that the combination of contact allergy to a fragrance together with a history indicating dermatitis at exposure and thereafter subsequent avoidance of scented products implied a diagnosis of allergic contact dermatitis.

OBJECTIVES

The primary aim of this study was to validate this hypothesis/algorithm. The secondary aim was to investigate whether there was any association between the outcome of the recent repeated open application test (ROAT) and the patch test reactivity.

METHODS

One hundred nine subjects with and without contact allergy to fragrance mix II (FM II) were recruited. Volunteers from six European dermatology clinics participated in the study including a patch test and a ROAT.

RESULTS

Twenty-four positive ROAT reactions were noted in total including 20 of those 32 with contact allergy to FM II. None of the volunteers reacted to the vehicle (P < 0.001). More individuals with a positive algorithm had positive ROATs when compared with those with a negative algorithm. However, the difference was not statistically significant (P = 0.12). The lower the patch test concentration eliciting a positive test reaction, the more likely was a positive ROAT and the more likely that the positive ROAT appeared early during the investigative period.

CONCLUSIONS

The algorithm used in this study was not validated but it was indicated in this ROAT setup. The stronger the patch test reactivity the more likely was a positive ROAT and the more likely it was that the positive ROAT appeared early during the application period.

Myroxylon pereirae (balsam of Peru): Still worth testing?

Background

Because Myroxylon pereirae (MP), or balsam of Peru, is nowadays almost not used “as such,” and fragrance mix 1 (FM1) apparently is more sensitive in detecting fragrance allergy, the usefulness of testing MP in baseline series was recently questioned.

Objectives

Identification of the number of clinically relevant patch test reactions to MP not detected by FM1.

Methods

Retrospective analysis of 12 030 patients patch tested with MP and FM1 for contact dermatitis between January 2018 and December 2019 in 13 Italian dermatology clinics.

Results

Four hundred thirty‐nine patients (3.6%) had a positive patch test reaction to MP; 437 (3.6%) had a positive patch test reaction to FM1. Positive reactions to both MP and FM1 were observed in 119 subjects (1.0%), 310 (2.6%) reacted to MP only, 304 (2.5%) to FM1 only, 5 to MP and sorbitan sesquioleate (SSO), 9 to FM1 and SSO, and 5 to MP, FM1, and SSO. Single sensitizations were clinically relevant in 75.2% of cases for MP (62.9% current, 12.3% past) and 76.3% for FM1 (70.1% current, 6.2% past).

Conclusions

Based on our results, MP appears to be still worth testing along with FM1 in baseline series, because it allows detection of a remarkable number of fragrance allergies, often relevant, which would be otherwise missed.

Men's Facial Moisturizers in the Metrosexual Era

BACKGROUND

Manufacturers are increasingly branding personal care products (PCPs) specifically for men.

OBJECTIVE

The aim of the study was to characterize ingredients and claims of facial moisturizers marketed to men.

METHODS

Men's facial moisturizers from 7 different online retailers were identified in June-September 2018. Ingredients were grouped and identified per the Ingredient Database of the Personal Care Products Council. Potential allergens were identified using the 2017 American Contact Dermatitis Society (ACDS) Core Allergen Series and 2017-2018 North American Contact Dermatitis Group Screening Series.

RESULTS

Sixty-five men's facial moisturizers were identified with a total of 1930 ingredients. On average, there were 12 ACDS Core and 9 North American Contact Dermatitis Group Screening allergens per product. A total of 70.8% of products contained between 6 and 15 ACDS Core allergens. The most notable allergens were fragrances (present in 98.5% of products), propylene glycol/derivatives (32.3%), parabens (29.2%), and alkyl glucosides (26.2%). Interestingly, less than 10% of products contained the most common allergenic preservatives in PCPs: formaldehyde releasers and methylisothiazolinone.

CONCLUSIONS

Men's facial moisturizers commonly contain fragrances, emulsifiers, and glucosides but relatively few allergenic preservatives. This may reflect changes in modern PCP preservation. These findings are important for modern dermatologists to be aware, especially in a new era of male skincare.

Environmental Distribution of Personal Care Products and Their Effects on Human Health

Personal care products (PCPs) are generally used for personal hygiene, cleaning, grooming, and beautification. These include hair and skin care products, baby care products, UV blocking creams, facial cleansers, insect repellents, perfumes, fragrances, soap, detergents, shampoos, conditioners, toothpaste, etc., thus exposing humans easily. Personal preferences related to PCPs usage frequency are highly variable and depend on socioeconomic status and lifestyle factors. The increasing availability and diversity of PCPs from the retailer outlets consequently result in higher loading of PCPs into wastewater systems and, therefore, the environment. These compounds persistently and continuously release biologically active and inactive ingredients in the atmosphere, biosphere, geosphere, and demonstrating adverse effects on human, wild, and marine life. Advanced techniques such as granular activated carbon filtration and algae-based system may help biotransformation and remove PCP contaminants from water with improved efficiency. Additionally, harmony among PCPs related regulations of different countries may encourage standard checks to control their manufacturing, sale, and distribution across the borders to ensure consumers' safety. Furthermore, all intended ingredients, their concentrations, and instructions for frequency of use as per age groups may be clearly labeled on packages of PCPs. In conclusion, the emerging environmental contaminants of PCPs and their association with the growing risks of negative effects on human health and globally on the environment emphasize the chemical-free simple lifestyle.

Skin sensitization to fragrance hydroperoxides: interplay between dendritic cells, keratinocytes and free radicals

BACKGROUND

Skin sensitization to hydroperoxides (R-OOHs) of the commonly used fragrance terpenes limonene, linalool and citronellol is frequently reported. R-OOHs are believed to initiate the process leading to sensitization and allergic contact dermatitis through mechanisms involving radical intermediates. Thus, radical intermediates, keratinocytes and dendritic cells (DCs) may act in concert to initiate the process.

OBJECTIVES

To evaluate individual DC activation profiles by R-OOHs in the context of keratinocytes with regard to frequency, specificity and magnitude of upregulation.

METHODS

We used 2D and 3D cocultures with keratinocytes/reconstructed human epidermis (RHE) and DCs to evaluate cell surface levels of the costimulatory molecules CD86, CD80 and the adhesion molecule CD54 on cocultured DCs. Analysis of radical formation from limonene hydroperoxides in RHE was performed using electron paramagnetic resonance combined with the spin trapping technique.

RESULTS

R-OOHs induce donor-dependent DC activation. Major differences were found between the limonene-OOHs. Limonene-1-OOH was stronger with respect to both frequency and magnitude of response. Using a 3D coculture model, no DC activation was detected after topical application of 0·2% limonene-OOHs (20 µg cm^-2 ), while 1·2% limonene-1-OOH or 2% limonene-2-OOH induced DC activation. Furthermore, we demonstrated differences in the carbon and oxygen radicals formed from the limonene-OOHs using RHE, mimicking what may happen in vivo.

CONCLUSIONS

We report clear individual differences in DC maturation induced by the most important hydroperoxides. Response rates and magnitude of response both indicate that very small structural alterations in the hydroperoxides are translated into specific DC responses. In addition, we provide more insight into the amounts of hydroperoxides that can activate DCs and induce sensitization.

Contact Allergy-Emerging Allergens and Public Health Impact

Contact allergy (sensitisation) and allergic contact dermatitis (ACD) resulting from it have a considerable public health impact. For the present review, all pertinent articles were systematically searched via Medline and Web of Science™; additionally, all available issues of the journals "Contact Dermatitis" and "Dermatitis" were manually searched, covering the years 2018-2019, thereby extending and re-focusing a previous similar review. New allergens, or previously described allergens found in a new exposure context or of other current importance, are described in sections according to substance classes, e.g., metals, preservatives, fragrances. As a common finding in many investigations, a lack of information on product composition has been noted, for instance, regarding a newly described allergen in canvas shoes (dimethylthiocarbamylbenzothiazole sulfide) and, most notably, absence of co-operation from manufacturers of glucose-monitoring devices and insulin pumps, respectively. These latter devices have been shown to cause severe ACD in a considerable number of diabetic patients caused by the liberation of isobornyl acrylate and N,N'-dimethylacrylamide, respectively, as demonstrated by an international collaboration between dermatologists and chemists. Improved and complete ingredient labelling for all types of products, and not just cosmetics, must be put on the legislative agenda.

Limonene Hydroperoxides

Limonene is a fragrance widely used in cosmetics and household products. Until recently, contact allergy to limonene was considered rare because positive patch tests to it were infrequently observed. In recent years, however, it has been demonstrated that exposure of limonene to oxygen (air) results in the formation of a number of oxidation products, of which the hydroperoxides have a far stronger sensitizing potency than the pure compound. By routine testing of patients suspected of contact dermatitis with hydroperoxides of limonene, high frequencies of positive reactions were found, indicating that these chemicals are important fragrance allergens. It should be realized, however, that a number of "positive" reactions may well be false-positive, irritant responses.