H. J. Schwanitz

The Acidic Milieu of the Horny Layer

The acidic pH of the horny layer, measurable on the skin surface, has long been regarded as a result of exocrine secretion of the skin glands. The ‘acid mantle’ was thought to regulate the bacterial skin flora and to be sensitive primarily to skin cleansing procedures.In recent years, an increasing number of investigations have been published on the changes in, and constituents and functions of, the pH of the deeper layers of the stratum corneum, as well as on the influence of physiological and pathological factors. A central role for the acidic milieu as a regulating factor in stratum corneum homeostasis is now emerging. This has relevance to the integrity of the barrier function, from normal maturation of the stratum corneum lipids through to desquamation. Changes in the pH and the organic factors influencing it appear to play a role, not only in the pathogenesis, prevention and treatment of irritant contact dermatitis, but also of atopic dermatitis and ichthyosis and in wound healing.On the basis of these findings, a broader concept, exceeding the superficial ‘acid mantle’ theory, has been formulated.

Multicentre study for the development of an in vivo model to evaluate the influence of topical formulations on irritation

Although skin protective products to prevent irritant skin reactions are in wide use, neither standardized test models to prove differences in efficacy exist, nor has the quality or the reproducibility of results been evaluated in a multicentre approach. This should be mandatory when developing or testing skin care products. Therefore, we have designed a multicentre study in an approach to find a standardized test procedure for the evaluation of skin protective products. In this irritation study, a repeated short‐time occlusive irritation test (ROIT) with a standardized protocol has been evaluated in 2 phases (12 days and 5 days protocol) in 4 (n=20) respectively 6 (n=33) skilled centres. The skin reaction was induced by 2 irritants (0.5% aq. SLS and toluene, 2× a day for 30 min). Its modification by 3 different cream bases with different hydrophilicity was analyzed. The irritation was monitored by bioengineering methods (TEWL measurement, colorimetry) and by clinical scoring. The evaluation showed that significant results could already be achieved with the 5‐day protocol. Furthermore, in spite of the expected inter‐centre variations due to heterogeneity of the individual threshold of irritation, interpretation of clinical score, and inter‐instrumental variability, the ranking of the vehicles regarding reduction of the irritant reaction was consistent in all centres.

Interdigital dermatitis: sentinel skin damage in hairdressers

In the course of a cohort study, 2275 hairdressing apprentices were examined a median of 6 weeks after the start of their training in the years 1992, 1993 and 1994. Skin changes were noted in 821 (36%). The site most often affected was the interdigital web space (664 of those with skin changes: 81%). The proportion of participants with a high atopy score and previous hand and flexural dermatitis was larger in the subset with interdigital dermatitis than in healthy persons, but was particularly elevated in those affected by dermatitis involving other sites. Interdigital dermatitis can be regarded as a potential precursor of more severe hand dermatitis in hairdressers, and probably of irritant hand dermatitis in wet work occupations in general. Thus, it is an important ‘sentinel’ for secondary prevention, e.g. regular and thorough application of emollients.

Relevance of multiparametric skin bioengineering in a prospectively-followed cohort of junior hairdressers

There is conflicting evidence concerning predictors of individual susceptibility to develop irritant contact dermatitis in wet work. A cohort of initially 92 hairdresser apprentices was prospectively followed for 3 years. The association between anamnestic and clinical findings, and multiparametric skin bioengineering data (transepidermal water loss [TEWL], microcirculation, capacitance, pH, sebum, temperature) was investigated. The observation intervals were 3 months in the 1st year of training and 12 months thereafter. Of the 92 apprentices, 6 had already developed hand dermatitis on 1st examination, 20 dropped out or had occupational exposure longer than 7 weeks prior to investigation. Of the remaining 66 participants considered here, 19 (29%) developed moderate or severe dermatitis (“cases”), 32 minimal skin changes, 15 none within the observation period. Average incidence rate of hand dermatitis was 21.1 cases per 100 person years. Atopy score was not associated with the development of dermatitis, nor were the investigated basal bioengineering parameters, including TEWL, in a multivariable model. However, there was a significant increase in TEWL within the 1st year of training in presumptive “cases”. The aim to develop an objective and predictive instrumentary for pre‐employment counselling in wet work, by a combination of (a) clinical and (b) relevant non‐invasive bioengineering parameters, has not yet been accomplished. Skin‐provocation tests employing bioengineering seem to be required. Notwithstanding, work‐related monitoring of basal biophysical skin‐functions may become useful in the secondary prevention of occupational dermatitis.

Atopic signs and symptoms: assessing the 'atopy score' concept.

Background: Score concepts have been suggested for the standardised diagnosis of atopic dermatitis, incorporating various anamnestic and clinical minor criteria of atopy, including the ‘Erlangen Score’, developed in the hospital-based setting of a dermatitis clinic. Objective: To evaluate the properties of this score in the context of a population-based epidemiological study. Methods: The association between relevant atopic criteria and previous or current flexural eczema was evaluated in 2,352 hairdressing apprentices. Results: The association was not as strong as in the patient-based studies, comparing the respective odds ratios. Accordingly, the discriminating power of the Erlangen Score was poor, resulting in low sensitivity (55.7%) and specificity (73.8%) for, e.g., 8 points as cutpoint. Conclusion: While the score appears useful to summarise minor criteria, the individual relevance of its point values should not be overestimated in view of a low positive predictive value in a population (compared to a clinical) setting.

Occupational allergic contact dermatitis from BAC-esterchloride (β-phenylethyl-dibutylacetic acid-ethylester-ammonium chloride)

Case Report A 37-year-old woman, with a history of chronic relapsing hand eczema, had worked as a dental technicain for nearly 20 years. In 1990, a papulovesicular eczema with fissures and erosions of the first interdigital spaces of both hands was noted. It had developed 24 to 28 h after contact with a dental prosthesis material that bad been used for nearly 2 years (Palapress Vario-Fliissigkeit, Heraeus Kulzer GmbH). There were no signs of atopy. Patch testing with the German standard series and supplementary series (rubber, fragrance, preservatives: Hermal, Reinbek, FRG) was performed. In addition, allergologically important ingredients of dental materials, based on the recommendations of Rustemeyer & Frosch (6), were tested (Table 1). For application, Hayes test chambers (lmtradex Service BY, CB Alphen aan den Rijn, The Netherlands) with additional fixation (Fixomull® Stretch, Beiersdorf, FRG) were used. Application time was 2 days, readings being performed according to ICDRG guidelines. Relevant results are shown in Table 1.