Population differences in skin structure and physiology and the susceptibility to irritant and allergic contact dermatitis: implications for skin safety testing and risk assessment

Efficacy and Safety of Crisaborole Ointment 2% in Chinese Patients Aged ≥ 2 Years with Mild to Moderate Atopic Dermatitis

INTRODUCTION

Atopic dermatitis (AD) is a chronic immuno-inflammatory skin disease. Crisaborole ointment, 2%, is a nonsteroidal phosphodiesterase 4 inhibitor approved for the treatment of mild to moderate AD. This post hoc analysis assesses the efficacy and safety of crisaborole in Chinese patients aged ≥ 2 years with mild to moderate AD.

METHODS

We evaluated the efficacy and safety of crisaborole in Chinese patients from the vehicle-controlled, phase 3 CrisADe CLEAR study. Patients were randomly assigned 2:1 to receive crisaborole or vehicle twice daily, respectively, for 28 days. The primary endpoint was percent change from baseline in Eczema Area and Severity Index (EASI) total score at day 29. Key secondary endpoints were improvement in Investigator's Static Global Assessment (ISGA), ISGA success, and change from baseline in weekly average Peak Pruritus Numerical Rating Scale (PP-NRS) score. Adverse events were documented.

RESULTS

Of 391 patients in the overall study, 237 were from China, 157 assigned to crisaborole and 80 assigned to vehicle. A greater reduction in percent change from baseline in EASI total score at day 29 was shown in the crisaborole vs. vehicle group (least squares mean [LSM]: -66.34 [95% (confidence interval) CI -71.55 to -61.12] vs. -50.18 [95% CI -58.02 to -42.34]). Response rates for achievement of ISGA improvement (43.2% [95% CI 35.4-51.1] vs. 33.4% [95% CI 22.5-44.2]) and ISGA success (31.7% [95% CI 24.3-39.0] vs. 21.5% [95% CI 12.1-30.9]) at day 29 were higher in the crisaborole vs. vehicle group. A greater reduction in change from baseline in weekly average PP-NRS score at week 4 was observed in the crisaborole vs. vehicle group (LSM: -1.98 [95% CI -2.34 to -1.62] vs. -1.08 [95% CI -1.63 to -0.53]). No new safety signals were observed.

CONCLUSION

Crisaborole was effective and well tolerated in Chinese patients aged ≥ 2 years with mild to moderate AD.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04360187.

Effects of regular exercise on skin moisturizing function in adults

Among lifestyle habits, the effect of exercise on skin moisturizing function has not been studied. Therefore, we aimed to clarify the effect of regular exercise on skin moisturizing function. The participants were 30-64 years old with no history of skin diseases and no exercise habits at the start of the study. The intervention group (n=9) continued to exercise at least 600 Mets/week for 8 weeks, while the control group (n=28) followed conventional lifestyle habits for 8 weeks. Questionnaires regarding lifestyle habits were administered at the beginning and after 8 weeks, and skin moisturizing function (stratum corneum hydration: SC hydration, Trans-Epidermal Water Loss: TEWL) was measured. Analysis of covariance was performed using sex, age, and measurements at the start of the study as covariates. Analysis of covariance showed that after 8 weeks of "moderate" or "higher" exercise, there was a trend toward higher SC hydration in the intervention group compared to that in the control group (p=0.083, η2=0.10). There was no difference in TEWL after 8 weeks (p=0.864, η2=0.00). These results suggest that regular exercise may help maintain and improve skin moisturizing function.

Single-cell analysis of human dermal fibroblasts isolated from a single male donor over 35 years

The aim of this study is to examine the effects of ageing on dermal fibroblast heterogeneity based on samples obtained from the same donor. We used a dermal fibroblast lineage (named ASF-4 cell lines) isolated from the inner side of the upper arm of a healthy male donor over a 35-year period, beginning at 36 years of age. Because clonal analysis of ASF-4 cell lines demonstrated a donor age-dependent loss of proliferative capacity and acquisition of senescent traits at the single-cell level, cultured cells frozen at passage 10 at ages 36 and 72 years were subjected to single-cell RNA sequencing. Transcriptome analysis revealed an increase in senescent fibroblasts and downregulation of genes associated with extracellular matrix remodelling with ageing. In addition, two putative differentiation pathways, with one endpoint consisting of senescent fibroblasts and the other without, were speculated using a pseudo-time analysis. Knockdown of the characteristic gene of the non-senescent fibroblast cluster endpoint, EFEMP2, accelerated cellular senescence. This was also confirmed in two other normal human dermal fibroblast cell lines. The detection of a common cellular senescence-related gene from single-donor analysis is notable. This study provides new insights into the behaviour of dermal fibroblasts during skin ageing.

Efficacy and safety of crisaborole ointment in Chinese and Japanese patients aged ≥2 years with mild-to-moderate atopic dermatitis

Atopic dermatitis is a chronic inflammatory skin disease with a significant impact on the overall wellbeing of patients and their families. Crisaborole ointment, 2%, is a nonsteroidal phosphodiesterase 4 inhibitor approved for the treatment of mild-to-moderate atopic dermatitis in multiple countries. However, in the key pivotal trials, a low proportion of the overall patient population was Asian, therefore the safety and efficacy of crisaborole in the Asian population with atopic dermatitis remains unclear. CrisADe CLEAR was a multicenter, randomized, double-blind, vehicle-controlled, phase 3 study (NCT04360187) to assess the efficacy and safety of crisaborole ointment in Chinese and Japanese patients aged ≥2 years with mild-to-moderate atopic dermatitis involving ≥5% treatable body surface area. Patients were randomly assigned 2:1 to receive crisaborole or vehicle twice daily for 28 days. The primary endpoint was percentage change from baseline in the Eczema Area and Severity Index total score at day 29. Additional endpoints were improvement and success per Investigator's Static Global Assessment score at day 29 and change from baseline on the Peak Pruritus Numerical Rating Scale at week 4. Safety was assessed using rates of treatment emergent adverse events, serious adverse events, and clinically significant changes in vital signs and clinical laboratory parameters. Crisaborole-treated patients showed a significantly greater reduction versus vehicle in percentage change from baseline in Eczema Area and Severity Index total score at day 29 (P = 0.0002). Response rates for achievement of Investigator's Static Global Assessment improvement and success at day 29 were significantly higher for patients treated with crisaborole versus vehicle (P = 0.0124 and P = 0.0078, respectively). Crisaborole-treated patients showed a significantly greater reduction versus vehicle in change from baseline on the Peak Pruritus Numerical Rating Scale at week 4 (P = 0.0009). No new safety signals were identified. Treatment with crisaborole was effective and well tolerated in Chinese and Japanese patients with mild-to-moderate atopic dermatitis.

Updating exposure assessment for skin sensitization quantitative risk assessment for fragrance materials

In 2008, a proposal for assessing the risk of induction of skin sensitization to fragrance materials Quantitative Risk Assessment 1 (QRA1) was published. This was implemented for setting maximum limits for fragrance materials in consumer products. However, there was no formal validation or empirical verification after implementation. Additionally, concerns remained that QRA1 did not incorporate aggregate exposure from multiple product use and included assumptions, e.g. safety assessment factors (SAFs), that had not been critically reviewed. Accordingly, a review was undertaken, including detailed re-evaluation of each SAF together with development of an approach for estimating aggregate exposure of the skin to a potential fragrance allergen. This revision of QRA1, termed QRA2, provides an improved method for establishing safe levels for sensitizing fragrance materials in multiple products to limit the risk of induction of contact allergy. The use of alternative non-animal methods is not within the scope of this paper. Ultimately, only longitudinal clinical studies can verify the utility of QRA2 as a tool for the prevention of contact allergy to fragrance materials.

Plant Complexity and Cosmetic Innovation

Plants have been used in cosmetic products since ancient times and are the subject of scientific investigation even nowadays. During the years, a deeper understanding of both the behavior of skin and of plants have become available drawing increasingly complex pictures. Plants are complex organisms that produce different metabolites responding to the environment they live in. Applied to the skin, phytomolecules interact with skin cells and affect the skin well-being and appearance. Ethnobotanical studies on the one hand and physico-chemical analyses on the other have pictured a rich inventory of plants with potential to enrich modern cosmetic products.

Remodelling of fibrillin-rich microfibrils by solar-simulated radiation: impact of skin ethnicity

Cutaneous fibrillin-rich microfibrils (FRMs) should be considered as two distinct populations that differentially accrue damage in response to SSR. Furthermore, FRMs derived from black African skin show greater change following UVR challenge.

Occupational hand dermatitis in car repair workers

Introduction

Exposure to used gasoline engine oils during oil change and other automobile repair services is common for many mechanics, electrical technicians, and other car service workers. We aimed to determine the prevalence of hand dermatitis in car repair workers with different specialty and actual dermal exposure hazards in the workplace.

Methods

We examined the dermal problems in 153 male car repair workers and compared it to 140 office workers. Exposed and control groups were administered a Nordic Occupational Skin Questionnaire. Dermal exposure score also was calculated.

Results

The prevalence of hand dermatitis in car repair workers (19.0%) was significantly higher than office worker (7.9%) [OR: 2.74, (95% CI = 1.31, 5.73)] and also higher than general population. Prevalence of atopic dermatitis was significantly higher in exposed group that had hand dermatitis compared with those who had no hand dermatitis (P < 0.001). The highest hand dermatitis as well as actual dermal exposure was observed in the mechanics and transmission technician respectively.

Conclusion

Car repair workers have an elevated prevalence of hand dermatitis in comparison with office workers. The most important risk factors for hand dermatitis among car repair workers are atopic dermatitis and the next the level of skin exposure to potential skin hazards.

The 21st Century movement within the area of skin sensitization assessment: From the animal context towards current human-relevant in vitro solutions

In a regulatory context, skin sensitization hazard and risk evaluations of manufactured products and their ingredients (e.g. cosmetics) are mandatory in several regions. Great efforts have been made within the field of 21st Century Toxicology to provide non-animal testing approaches to assess the skin allergy potential of materials (e.g. chemicals, mixtures, nanomaterials, particles). Mechanistic understanding of skin sensitization process through the adverse outcome pathway (AOP) has promoted the development of in vitro methods, demonstrating accuracies superior to the traditional animal testing. These in vitro testing approaches are based on one of the four AOP key events (KE) of skin sensitization: formation of immunogenic hapten-protein complexes (KE-1 or the molecular initiating event, MIE), inflammatory keratinocyte responses (KE-2), dendritic cell activation (KE-3), and T-lymphocyte activation and proliferation (KE-4). This update provides an overview of the historically used in vivo methods as well as the current in chemico and in cell methods with and without OECD guideline designations to analyze the progress towards human-relevant in vitro test methods for safety assessment of the skin allergenicity potential of materials. Here our focus is to review 96 in vitro testing approaches directed to the KEs of the skin sensitization AOP.

Occupational skin disorders in a subset of Nigerian hairdressers

Introduction

Hairdressing is associated with a wide range of disorders. This is particularly true in the African hairdresser, who is saddled with the responsibility of ‘taming’ the rather difficult-to-manage African hair, and is thus exposed to a wide range of chemical, biological and physical materials in the hair grooming process. We therefore sought to determine the prevalence and pattern of occupational skin disorders among hairdressers in Ibadan, one of the oldest and largest cities in Nigeria.

Methods

This was a cross sectional study of hairdressers conducted in 2013 in Ibadan, Nigeria. Hairdressers and their apprentices were interviewed using a structured questionnaire, following which a thorough physical examination was performed to identify any skin disorder.

Results

A total of 226 hairstylists were recruited. The prevalence of occupational skin disorders in the study was 68.13%. The prevalence of specific skin disorders was 32.74% for nail disorders; 28.75% for traumatic skin disorders; and 2.64% for hand dermatitis.

Conclusion

There is a high prevalence of occupational skin disorders among hairdressers, and this may have personal and public health implications.

Absence of human skin irritation and allergenic potential after repeated patch applications of a lamellar moisturizer

Background

New cosmetic products should undergo clinical evaluation for skin sensitization potential.

Objectives

To assess the irritation and sensitization potential of a moisturizer containing lamellar structured lipids after repeated patch application in humans, using human repeated insult patch test methodology.

Methods

This 6‐week, single‐center, open‐label study compared a lamellar moisturizer with negative saline control in human subjects aged 18‐70 years and skin phototype (Fitzpatrick) classification I–IV. During an initial induction phase, semi‐occlusive multi‐test patches were applied to the skin of participants’ backs three times per week for 3 consecutive weeks; clinical assessments were performed per International Contact Dermatitis Research Group criteria. Participants subsequently underwent a challenge phase, where a new patch was applied to a contact‐naïve area of the skin to assess sensitization to the moisturizer.

Results

The study commenced with 233 voluntary participants, 214 of whom completed the study and underwent the final dermatological assessment. Most participants (232/233; 99.6%) demonstrated negative patch test results. One participant had a positive reaction at the lamellar moisturizer application site, with visible erythema and edema (classified as an adverse event [AE]); however, this reaction was observed 24 hours after a reaction to another product in the patch test panel (a prototype cleanser). Importantly, no skin reactions were detected during the challenge phase. Two participants had AEs of mild contact dermatitis in the area of patch adhesive application during the induction phase. No serious AEs occurred during the study.

Conclusions

These findings suggest that the lamellar moisturizer has low irritant and allergenic potential.

Seeking Clearer Recommendations for Hand Hygiene in Communities Facing Ebola: A Randomized Trial Investigating the Impact of Six Handwashing Methods on Skin Irritation and Dermatitis

To prevent disease transmission, 0.05% chlorine solution is commonly recommended for handwashing in Ebola Treatment Units. In the 2014 West Africa outbreak this recommendation was widely extended to community settings, although many organizations recommend soap and hand sanitizer over chlorine. To evaluate skin irritation caused by frequent handwashing that may increase transmission risk in Ebola-affected communities, we conducted a randomized trial with 91 subjects who washed their hands 10 times a day for 28 days. Subjects used soap and water, sanitizer, or one of four chlorine solutions used by Ebola responders (calcium hypochlorite (HTH), sodium dichloroisocyanurate (NaDCC), and generated or pH-stabilized sodium hypochlorite (NaOCl)). Outcomes were self-reported hand feel, irritation as measured by the Hand Eczema Score Index (HECSI) (range 0-360), signs of transmission risk (e.g., cracking), and dermatitis diagnosis. All groups experienced statistically significant increases in HECSI score. Subjects using sanitizer had the smallest increases, followed by higher pH chlorine solutions (HTH and stabilized NaOCl), and soap and water. The greatest increases were among neutral pH chlorine solutions (NaDCC and generated NaOCl). Signs of irritation related to higher transmission risk were observed most frequently in subjects using soap and least frequently by those using sanitizer or HTH. Despite these irritation increases, all methods represented minor changes in HECSI score. Average HECSI score was only 9.10 at endline (range 1-33) and 4% (4/91) of subjects were diagnosed with dermatitis, one each in four groups. Each handwashing method has benefits and drawbacks: soap is widely available and inexpensive, but requires water and does not inactivate the virus; sanitizer is easy-to use and effective but expensive and unacceptable to many communities, and chlorine is easy-to-use but difficult to produce properly and distribute. Overall, we recommend Ebola responders and communities use whichever handwashing method(s) are most acceptable, available, and sustainable for community handwashing.

TRIAL REGISTRATION

International Standard Randomized Controlled Trial Registry ISRCTN89815514.

Introduction to skin aging

Cutaneous science has seen considerable development in the last 25 years, in part due to the Omics revolution, and the appreciation that this organ is hardwired into the body's key neuro-immuno-endocrine axes. Moreover, there is greater appreciation of how stratification of skin disorders will permit more targeted and more effective treatments. Against this has been how the remarkable extension in the average human life-span, though in the West at least, this parallels worrying increases in lifestyle-associated conditions like diabetes, skin cancer etc. These demographic trends bring greater urgency to finding clinical solutions for numerous age-related deficits in skin function caused by extrinsic and intrinsic factors. Mechanisms for aging skin include the actions of reactive oxygen species (ROS), mtDNA mutations, and telomere shortening, as well as hormonal changes. We have also significantly improved our understanding of how to harness the skin's considerable regenerative capacity e.g., via its remarkable investment of stem cell subpopulations. In this way we hope to develop new strategies to selectively target the skin's capacity to undergo optimal wound repair and regeneration. Here, the unsung hero of the skin regenerative power may be the humble hair follicle, replete with its compliment of epithelial, mesenchymal, neural and other stem cells. This review introduces the topic of human skin aging, with a focus on how maintenance of function in this complex multi-cell type organ is key for retaining quality of life into old age.

Anti-aging cosmetics: facts and controversies

The authors review ageing in its extrinsic and intrinsic mechanisms, as well as the therapies available for improving its effects, and present some of the facts and controversies related to anti-aging cosmetics.

Contact hypersensitivity: quantitative aspects, susceptibility and risk factors

The development of allergic sensitisation by environmental chemicals results in allergic contact dermatitis and highly undesirable morbidity and disability. This form of hypersensitivity is mediated by specific T lymphocytes that recognise the chemical sensitiser bound to self-proteins. Use of deliberate experimental contact sensitisation with dinitrochlorobenzene (DNCB) has been used to investigate the human immune system which exhibits dose-related responses. Many factors contribute to whether sensitisation occurs and the nature and magnitude of the immune response. Chemicals vary in sensitising potency, mainly reflecting their intrinsic protein-binding properties. The amount of sensitiser reaching the immune system is determined by many factors of which the concentration (dose per unit area), the relative lipid solubility and molecular weight are the most critical. Host-related factors contributing to the nature and magnitude of immune responses are mainly genetically determined including gender, age, the biochemical/physical integrity of the epidermal barrier and the quality of the innate and adaptive immune systems. The underlying mechanisms must be elucidated before it will be possible to make reliable predictions of whether a given individual will develop allergic sensitisation by a given chemical.

Contact sensitivity to metals (chromium, cobalt and nickel) in childhood

Metals, especially nickel, are the most common contact allergens in children. Recent data has shown increased incidence of allergy in industrialized countries. Sensitization can occur at any age, even in neonates. Costume jewelry, particularly earrings, is linked to increased sensitization to nickel. Sensitization to cobalt often occurs by the use of costume jewelry. The most common source of sensitization to chromium is leather. Due to the absence of a specific therapy, the main treatment is to identify and avoid the responsible allergens. This article presents an updated view on the epidemiological and clinical aspects of contact allergy to metals, focusing on prevention strategies and risk factors, and warns about possible and new sources of contact.

Irritant contact dermatitis: effect of age

Knowledge on age-relationship to irritant contact dermatitis (ICD) remains of interest. We searched for articles and textbooks on age-relationship to ICD and evaluated relevant data. Irritant response may be enhanced in children and decline with increasing age. In general, older skin reacts more slowly and with less intensity to irritants when compared with young skin. Such age-related changes may depend: (i) on differences in percutaneous penetration in old and young skin, and/or on (ii) differences in the microcirculatory efficiency, which serves as the route by which inflammatory cells make their way to the site of inflammation. Additionally, stratum corneum turnover time increases with age which means that an irritant remains longer on the skin; a compromised cutaneous blood vessel network with ageing may lead to a decreased inflammatory response, decreased absorption and decreased clearance. In conclusion, age-related differences of ICD are present despite some conflicting data. Investigations elucidating this interesting subject may benefit in prevention and intervention strategies.

Contact dermatitis in older adults: a review of the literature

Contact dermatitis is a significant health problem affecting the elderly. Impaired epidermal barrier function and delayed cutaneous recovery after insult enhances susceptibility to both irritants and allergens. Exposure to more numerous potential sensitizers and for greater durations influences the rate of allergic contact dermatitis in this population. Medical co-morbidities, including stasis dermatitis and venous ulcerations, further exacerbate this clinical picture. However, while these factors tend to increase the degree of sensitization in the elderly, waning immunity can actually decrease such a propensity. This interplay of both intrinsic and extrinsic factors makes a generalization on trends for contact dermatitis in older adults challenging. The literature has varying reports on the overall incidence of allergic contact dermatitis with advancing age. Nevertheless, it does clearly show that sensitivity to topical medicaments increases with age. Irritant contact dermatitis studies are more consistent, with less reactivity (to irritants) in older compared with younger skin. Diagnosis of both irritant and allergic contact dermatitis is based on a thorough history, complete skin examination, and comprehensive patch testing. The mainstay of therapy is avoidance of the offending chemical substances and the use of topical along with systemic therapies, depending on the severity of the condition.

Effect of orally administered Eriobotrya japonica seed extract on allergic contact dermatitis in rats

The anti-allergic activity of Eriobotrya japonica seeds extract (ESE) was investigated. Oral administration of ESE dramatically inhibited ear swelling due to allergic contact dermatitis caused by repeated application of two antigens, 4-ethoxymethylene-2-phenyl-2-oxazolin-5-one (oxazolone) and dinitrofluorobenzene (DNFB), respectively. The increase of histamine content in inflamed ear tissue induced by oxazolone and DNFB was significantly antagonized by orally administered ESE. Eosinophil peroxidase and myeloperoxidase activity in both models was suppressed by orally administered ESE. Tumour necrosis factor-α in the inflamed region caused by repeated application of DNFB was also significantly suppressed. The findings suggest that ESE may be effective for treating allergic contact dermatitis.

Functional and physiological characteristics of the aging skin

As life expectancy in the U.S. increases - and with it the proportion of the aged in the population - appropriate care of elderly skin becomes a medical concern of increasing importance. As skin ages, the intrinsic structural changes that are a natural consequence of passing time are inevitably followed by subsequent physiological changes that affect the skin's ability to function as the interface between internal and external environments. The pH of the skin surface increases with age, increasing its susceptibility to infection. Neurosensory perception of superficial pain is diminished both in intensity and speed of perception (increasing the risk of thermal injury); deep tissue pain, however, may be enhanced. A decline in lipid content as the skin ages inhibits the permeability of nonlipophilic compounds, reducing the efficacy of some topical medications. Allergic and irritant reactions are blunted, as is the inflammatory response, compromising the ability of the aged skin to affect wound repair. These functional impairments (although a predictable consequence of intrinsic structural changes) have the potential to cause significant morbidity in the elderly patient and may, as well, be greatly exacerbated by extrinsic factors like photodamage. As numbers of the elderly increase, medical as well as cosmetic dermatological interventions will be necessary to optimize the quality of life for this segment of the population.

Intrinsic and extrinsic factors in skin ageing: a review

As the proportion of the ageing population in industrialized countries continues to increase, the dermatological concerns of the aged grow in medical importance. Intrinsic structural changes occur as a natural consequence of ageing and are genetically determined. The rate of ageing is significantly different among different populations, as well as among different anatomical sites even within a single individual. The intrinsic rate of skin ageing in any individual can also be dramatically influenced by personal and environmental factors, particularly the amount of exposure to ultraviolet light. Photodamage, which considerably accelerates the visible ageing of skin, also greatly increases the risk of cutaneous neoplasms. As the population ages, dermatological focus must shift from ameliorating the cosmetic consequences of skin ageing to decreasing the genuine morbidity associated with problems of the ageing skin. A better understanding of both the intrinsic and extrinsic influences on the ageing of the skin, as well as distinguishing the retractable aspects of cutaneous ageing (primarily hormonal and lifestyle influences) from the irretractable (primarily intrinsic ageing), is crucial to this endeavour.

Skin differences, needs, and disorders across global populations

Accurately determining the incidence and prevalence of dermatologic disease in most large populations has been challenging for reasons ranging from the lack of easily quantifiable tests and measures to imprecision around definitions of race, ethnicity, photo skin type, pigmentation, and population groups. Compounding the problems with these categorizations is the fact that skin disease and skin health are affected not just by inherent risk factors but also by habits and environment. Thus, a fundamental question remains as we evaluate the effects of cultural and environmental factors: do genetic factors account for most of the difference that we see in skin types? Is the primary influence the way the skin mediates the environmental insult of UV radiation or how inflammation is handled? Is melanization the primary characteristic that we should measure and consider? This article will provide an introduction to current knowledge and future directions researchers are taking in differentiating both the biological differences of skin and the clinical manifestations of skin disease among the groups described above. This discussion will be followed by a brief overview of cultural practices and environmental factors that are known to have significant impact on skin disease and a summary of the most common conditions that are encountered worldwide.

Estimates of percutaneous toxicity of sulfur mustard vapor suitable for use in protective equipment standards

An analysis was performed of historical human chamber data for exposure to sulfur mustard vapor, in order to correlate skin exposure dosages with effects in a manner specifically suitable for use in protective clothing standards. Data were reanalyzed to take into account (1) body region variability of skin responses to a single acute exposure to sulfur mustard vapor, (2) effect of hot/humid versus cooler exposure, and (3) influence of clothing. This approach permits deriving predicted skin responses pertinent to a protective clothing wearer, for a relatively short single acute exposure to vapor (up to a few hours) under the hot/humid conditions expected within a protective ensemble. Values for permissible dermal exposure to sulfur mustard vapor are proposed for protected emergency responders or military serving in combat theaters that may be used in standards intended to be employed in conjunction with evaluation of vapor protection provided by individual protective equipment for protection against chemical warfare agents by Man-in-Simulant vapor test methods.

Dermal sensitization quantitative risk assessment (QRA) for fragrance ingredients

Based on chemical, cellular, and molecular understanding of dermal sensitization, an exposure-based quantitative risk assessment (QRA) can be conducted to determine safe use levels of fragrance ingredients in different consumer product types. The key steps are: (1) determination of benchmarks (no expected sensitization induction level (NESIL)); (2) application of sensitization assessment factors (SAF); and (3) consumer exposure (CEL) calculation through product use. Using these parameters, an acceptable exposure level (AEL) can be calculated and compared with the CEL. The ratio of AEL to CEL must be favorable to support safe use of the potential skin sensitizer. This ratio must be calculated for the fragrance ingredient in each product type. Based on the Research Institute for Fragrance Materials, Inc. (RIFM) Expert Panel's recommendation, RIFM and the International Fragrance Association (IFRA) have adopted the dermal sensitization QRA approach described in this review for fragrance ingredients identified as potential dermal sensitizers. This now forms the fragrance industry's core strategy for primary prevention of dermal sensitization to these materials in consumer products. This methodology is used to determine global fragrance industry product management practices (IFRA Standards) for fragrance ingredients that are potential dermal sensitizers. This paper describes the principles of the recommended approach, provides detailed review of all the information used in the dermal sensitization QRA approach for fragrance ingredients and presents key conclusions for its use now and refinement in the future.

The effect of population diversity on skin irritation

The impact of many human variables on the response to skin irritating substances has been studied to varying degrees, including the impact of age, sex, and atopic status. However, the importance of ethnic origin has been more difficult to investigate, leading to a relative paucity of compelling data, either for or against the existence of differences. A primary reason for this lack is that studies on different ethnic groups often have to be undertaken in different locations thus introducing variables, e.g. time, environmental conditions that confound interpretations. In the present work, an attempt has been made to eliminate all variables except ethnicity by conducting a study on 2 distinct populations (Punjabis and Tamils) at the same location on the same day with a single assessor of the skin reactions, using sodium lauryl sulfate as the skin irritant. The skin reactions were assessed visually, and it was demonstrated that the modality of the reactions in these 2 populations had clear differences, but that the dose-response profiles were very similar. Thus, although the irritant response was expressed differently (e.g. erythema was much less evident in the darker Tamil population), the overall outcome was that the populations reacted in an equivalent manner.

The course of eczema in children aged 5-7 years and its relation to atopy: differences between boys and girls

BACKGROUND

The role of atopy in the pathophysiology of eczema is still under debate. The concept and analyses of the nonatopic and atopic subtypes of eczema have gained increasing interest in recent studies. The course of these subtypes and differences between boys and girls have not been investigated so far.

OBJECTIVES

To examine the course of nonatopic and atopic eczema in preschool children from Germany with regard to sex.

METHODS

Repeated cross-sectional studies were performed in 5-7-year-old preschool children from Germany between 1994 and 2000. Individuals with eczema were identified by a dermatological examination. In addition to a questionnaire, skin prick tests and analyses of serum IgE antibodies against seven and five environmental allergens, respectively, were performed. Atopy was defined by sensitization to at least one of five common aeroallergens (birch, grass and mugwort pollen, house dust mites, cat dander). In part of the study population investigations of spare time behaviour and skin function were carried out (including stratum corneum hydration and skin surface pH).

RESULTS

A total of 2693 girls and 2783 boys underwent a full dermatological examination of the skin and determination of sensitization. Among the girls, 8.7% demonstrated eczema clinically at the day of investigation in contrast to 6.1% of the boys. In girls, early onset eczema (< 2 years of age) was strongly related to atopy at age 5-7 years [odds ratio (OR) 3.7; 95% confidence interval (CI) 2.7-5.1], whereas late-onset eczema (> or = 2 years of age) was not (OR 1.0; 95% CI 0.7-1.5). Boys were more often atopic at the age of 5-7 years than girls (28.3% vs. 20.6%), and early and late-onset eczema were related to atopy without such a difference (OR 2.8, 95% CI 2.0-4.0; OR 1.9, 95% CI 1.3-2.8, respectively). The excess of current eczema in 5-7-year-old girls compared with boys was related to the nonatopic type. The higher susceptibility of girls in that age group to develop eczema was reflected by the skin physiological examination: even girls without eczema had significantly higher skin surface pH and lower stratum corneum hydration than boys. Additionally, questionnaire data revealed that girls more often than boys predominantly played indoors, which was associated with more eczema.

CONCLUSIONS

Atopy and eczema develop differently in boys and girls. Boys are more often atopic, whereas girls suffer significantly more often from eczema without relation to atopy. The nonatopic type of eczema in preschool girls is noticed predominantly after their second birthday. Genetic and lifestyle factors may contribute to this difference.

Occupational contact dermatitis: etiology, prevalence, and resultant impairment/disability

Cutaneous irritant and allergic responses account for the vast majority of cases of occupational contact dermatitis (OCD). Although the pathophysiologic responses to these two different exposures are distinct, the clinical differentiation between chronic cumulative irritant contact dermatitis and allergic contact dermatitis can be difficult and frequently requires patch testing. This article reviews the recommended algorithms that clinicians should utilize to assess whether a worker suffers from OCD. The prevalence of OCD, its predisposing factors (both endogenous and exogenous), and prognosis are discussed in depth. Finally, issues surrounding the assessment of impairment and disability resulting from OCD are summarized.

Irritant contact dermatitis induced by a common household irritant: A noninvasive evaluation of ethnic variability in skin response

OBJECTIVE

This study was undertaken to investigate the ethnic susceptibility to irritant contact dermatitis induced by a common dishwashing liquid using noninvasive technologies.

METHODS

A total of 30 participants (15 Caucasian, 15 African American) were patch tested to graded concentrations of a common household irritant and evaluated using clinical scoring, reflectance confocal microscopy, transepidermal water loss, and fluorescence excitation spectroscopy.

RESULTS

At 24 hours, the concentration thresholds for clinically perceptible irritancy were significantly higher for African American compared with Caucasian participants. Reflectance confocal microscopy showed stratum corneum disruption, parakeratosis, and spongiosis; these features were more severe in Caucasian participants (P < or = .002). Mean values for transepidermal water loss were significantly higher in the Caucasian group at comparable clinical scores (P < or = .005). Fluorescence excitation spectroscopy showed a broad excitation band at 300 nm (emission 340 nm) and values in both groups returned to baseline by day 7.

LIMITATIONS

This pilot study was limited in scope and larger studies are needed to further evaluate ethnic differences in irritant contact dermatitis and to demonstrate the applicability of our findings for other irritants.

CONCLUSION

Clinical evaluation, reflectance confocal microscopy, and transepidermal water loss showed significant differences in the cutaneous irritant response between both groups suggesting a superior barrier function of African American skin. Fluorescence excitation spectroscopy on the other hand demonstrated no differences in the hyperproliferative response after irritant exposure and indicated similar kinetics for the two groups.

Allergic contact dermatitis in children

INTRODUCTION

Allergic contact dermatitis (ACD) is equally as likely in infancy as in adulthood, and represents 20% of all cases of dermatitis in children. Its true prevalence and incidence are, however, unknown.

MATERIALS AND METHODS

We have conducted a retrospective study over 10 years of a group of patients aged 15 years or less, with clinical suspicion of ACD. Patch tests were performed in accordance with the standards of the GEIDC.

RESULTS

The study covered 96 patients with a mean age of 10.57+/-0.67 years. The zones most frequently affected by eczemas were those of diffuse distribution (28% of patients) and of the hands (27%). We found at least one positive response in 52% of the cases. The most frequent allergens were thiomersal (21%), mercury (19%) and nickel (18%). We have found a statistically significant association between age of less than 15 years and positive response to thiomersal [P<0.01; OR: 8.5 with confidence interval (CI) 95%: 5.08<odds ratio (OR)<14.20] and mercury (P<0.01; OR: 4.38 with CI 95%: 3.02<OR<6.33).

CONCLUSIONS

With increasing age, nickel takes the place of the mercurials as the principal allergen.

Patch testing with a standard allergen ("screening") tray: rewards and risks

The TRUE Test panels, which are the only patch testing devices approved by the Food and Drug Administration in the US, consist of 24 patches, one of which is a negative control. The remaining 23 patches contain 42 unique allergens and four complex mixtures. Although these panels contain approximately 1.4% of the > 3700 known allergens, they perform robustly in detecting allergic contact dermatitis (ACD). Twenty-eight percent of patients are fully evaluated by application of TRUE Test((R)). The present paper reviews the appropriate use of the TRUE Test panels. The need to determine relevance of any positive reaction is stressed. The common causes of false-positive and false-negative reactions are outlined. Those product types where the TRUE Test panels detect the majority of relevant allergic reactions are reviewed, as are the other sources of exposure to the allergens on these panels. The impact of ACD on quality of life is significant. Only by patch testing can the diagnosis be made.

Quantitative relationship between the local lymph node assay and human skin sensitization assays

The local lymph node assay (LLNA) is a new test method which allows for the quantitative assessment of sensitizing potency in the mouse. Here, we investigate the quantitative correlation between results from the LLNA and two human sensitization tests--specifically, human repeat insult patch tests (HRIPTs) and human maximization tests (HMTs). Data for 57 substances were evaluated, of which 46 showed skin sensitizing properties in human tests, whereas 11 yielded negative results in humans. For better comparability data from mouse and human tests were transformed to applied doses per skin area, which ranged over four orders of magnitude for the substances considered. Regression analysis for the 46 human sensitizing substances revealed a significant positive correlation between the LLNA and human tests. The correlation was better between LLNA and HRIPT data (n=23; r=0.77) than between LLNA and HMT data (n=38; r=0.65). The observed scattering of data points is related to various uncertainties, in part associated with insufficiencies of data from older HMT studies. Predominantly negative results in the LLNA for another 11 substances which showed no skin sensitizing activity in human maximization tests further corroborate the correspondence between LLNA and human tests. Based on this analysis, the LLNA can be considered a reliable basis for relative potency assessments for skin sensitizers. Proposals are made for the regulatory exploitation of the LLNA: four potency groups can be established, and assignment of substances to these groups according to the outcome of the LLNA can be used to characterize skin sensitizing potency in substance-specific assessments. Moreover, based on these potency groups, a more adequate consideration of sensitizing substances in preparations becomes possible. It is proposed to replace the current single concentration limit for skin sensitizers in preparations, which leads to an all or nothing classification of a preparation as sensitizing to skin ("R43") in the European Union, by differentiated concentration limits derived from the limits for the four potency groups.

Confocal histopathology of irritant contact dermatitis in vivo and the impact of skin color (black vs white)

BACKGROUND

The pathogenesis of irritant contact dermatitis and its modulation according to skin color is not well understood. Reflectance confocal microscopy (RCM) enables high-resolution, real-time, in-vivo imaging of human skin.

OBJECTIVE

The goal of our study was to use RCM to determine whether susceptibility to irritant contact dermatitis differs between black and white skin.

METHODS

Participants were placed in groups on the basis of skin color and the volar aspects of their forearms exposed to 1% and 4% sodium lauryl sulfate using Finn Chambers (Allerderm Laboratories Inc, Petaluma, Calif). They were evaluated at 6, 24, and 48 hours by RCM, transepidermal water loss, laser Doppler velocimetry, and routine histology.

RESULTS

Participants with white skin had more severe clinical reactions than those with black skin. RCM revealed microscopic changes even without clinical evidence of irritation. Confocal features included parakeratosis, spongiosis, perivascular inflammatory infiltrate, and microvesicle formation, and these features were confirmed by routine histology. Also, participants with white skin had greater mean increases in transepidermal water loss after exposure to 4% sodium lauryl sulfate than did participants with black skin.

CONCLUSION

In-vivo RCM can track early pathophysiologic events revealing differences between black and white skin during the development of irritant contact dermatitis, and may support the theory that those with black skin are more resistant to irritants.

Levels of enzymatic antioxidants activities in mononuclear cells and skin reactivity to sodium dodecyl sulphate

Chemical irritants are able to produce several biological modifications of the skin, including the direct or indirect production of cytokines and reactive oxygen species leading to an inflammatory reaction. This report examines the existence of a possible correlation between the skin sensitivity to the irritant sodium dodecyl sulphate (SDS) and the activity of the enzymatic antioxidants. In twenty-three healthy subjects the evaluation of the epidermal and peripheral blood mononuclear cells (PBMCs) activities of Superoxide Dismutase (SOD) and Catalase (Cat) demonstrate a significant correlation (r= 0,85 and p< 0,005 for SOD, and r= 0,87 and p< 0,0001 for Cat). Based on this result, on a further group of normal subjects (n=13) we studied the link between the threshold dose of skin reactivity to SDS and the activities of the enzymatic antioxidants in PBMCs. The degree of skin modification induced by SDS, applied at different concentrations for 24 hrs, was determined by means of Trans Epidermal Water Loss (TEWL), Erythemal Index or by Visual Score (VS). The minimal dose of the irritant capable of inducing skin modifications, was significantly correlated with SOD (r=0,77) and Cat (r=0,81) activities in PBMCs, and the modification of TEWL or EI were inversely correlated with levels of antioxidants in PBMCs (r=-0,62 for SOD and r=-0,66 for Cat). Our results indicate that the skin reactivity to irritants can be modulated by the levels of antioxidants, and suggest a possible therapeutical approach in preventing irritant contact dermatitis.

Racial (ethnic) differences in skin properties: the objective data

Racial (ethnic) differences in skin properties may explain racial disparities seen in dermatologic disorders and provide insight into appropriate differences in the management of these disorders. However, racial differences in skin have been minimally investigated by objective methods and the data are often contradictory. Objective methods studied include transepidermal water loss (TEWL), water content (WC), corneocyte variability, blood vessel reactivity, elastic recovery/extensibility, pH gradient, lipid content, surface microflora, microscopic evaluation of mast cell granules, and confocal microscopy. The majority of the evidence (six out of eight studies) indicates that TEWL is greater in Black skin compared with White skin. TEWL measurements of Asian skin are inconclusive as they have been found to be equal to Black skin and greater than Caucasian skin, equal to Caucasian skin, and less than all other ethnic groups in different studies. Racial differences in WC, as measured by resistance, capacitance, conductance and impedance, are also inconclusive as the data are contradictory. While the evidence regarding corneocyte desquamation is minimal, one clinically provocative observation is that Blacks have a 2.5 times greater spontaneous desquamation rate compared with Caucasians and Asians, possibly accounting for an increased frequency of xerosis seen clinically in Blacks. With regards to blood vessel reactivity, studies can not be compared to each other because each uses different vasoactive substances. However, each study, except for one study comparing Hispanics and Whites, and another comparing Japanese and German women, reveal some degree of racial variation in blood vessel reactivity. It has been demonstrated that the pH of Black skin is less than White skin; however, the studies that have demonstrated this have done so under different skin conditions and on different anatomic sites. Racial differences in lipid content are inconclusive. Additionally, there is insufficient and conflicting evidence to make conclusions regarding racial differences in skin biomechanics and skin microflora. Microscopic evaluation reveals that Black skin contains larger mast cell granules, and differences in stuctural properties and enzymes of mast cells compared with White skin, possibly accounting for differences in pruritus experienced by the individuals of these racial groups. There exists substantial evidence to support that Black skin has a higher TEWL, variable blood vessel reactivity, decreased skin surface pH, and larger mast cell granules compared with White skin. Although some deductions have been made about Asian and Hispanic skin, further evaluation needs to be done. Differences in WC, corneocyte desquamation, elastic recovery/extensibility, lipid content and skin microflora, although statistically significant, are inconclusive.