Kordula Schlotmann

Cosmetic efficacy claims in vitro using a three-dimensional human skin model.

Synopsis A tissue engineered human skin equivalent is successfully used for the testing of raw materials and cosmetic formulations. This reconstructed skin is supported by a collagen‐glycosaminoglycan‐chitosan biopolymer in which human keratinocytes and dermal fibroblasts were co‐cultured to form a tissue that closely reproduces the in vivo architecture of normal human skin and takes into account the complex interactions between epidermis and dermis. On the other hand, dermal and epidermal responses can be assessed separately in the dermal or skin equivalent.

Unveiling the molecular basis of intrinsic skin aging1

The process of skin aging is a combination of an extrinsic and intrinsic aspect, and knowing the molecular changes underlying both is a prerequisite to being able to effectively counter it. However, despite its importance for a deeper understanding of skin aging as a whole, the process of intrinsic skin aging in particular has barely been investigated. In this study, the molecular changes of intrinsic skin aging were analyzed by applying ‘Serial Analysis of Gene Expression’ (SAGETM) to skin biopsies of young and aged donors. The analysis resulted in several hundred differentially expressed genes with varying statistical significance. Of these, several genes were identified that either have never been described in skin aging before (e.g. APP) or have no identified function, e.g. EST sequences. This is the first time that intrinsic skin aging has been analyzed in such a comprehensive manner, offering a new and partially unexpected set of target genes that have to be analyzed in more detail in terms of their contribution to the skin aging process.

Skin sensitization quantitative risk assessment for occupational exposure of hairdressers to hair dye ingredients

ABSTRACT Occupational exposure of hairdressers to hair dyes has been associated with the development of allergic contact dermatitis (ACD) involving the hands. p‐Phenylenediamine (PPD) and toluene‐2,5‐diamine (PTD) have been implicated as important occupational contact allergens. To conduct a quantitative risk assessment for the induction of contact sensitization to hair dyes in hairdressers, available data from hand rinsing studies following typical occupational exposure conditions to PPD, PTD and resorcinol were assessed. By accounting for wet work, uneven exposure and inter‐individual variability for professionals, daily hand exposure concentrations were derived. Secondly, daily hand exposure was compared with the sensitization induction potency of the individual hair dye defined as the No Expected Sensitization Induction Levels (NESIL). For PPD and PTD hairdresser hand exposure levels were 2.7 and 5.9 fold below the individual NESIL. In contrast, hand exposure to resorcinol was 50 fold below the NESIL. Correspondingly, the risk assessment for PPD and PTD indicates that contact sensitization may occur, when skin protection and skin care are not rigorously applied. We conclude that awareness of health risks associated with occupational exposure to hair dyes, and of the importance of adequate protective measures, should be emphasized more fully during hairdresser education and training. Graphical abstract Figure. No Caption available. HighlightsOccupational Quantitative‐Risk‐Assessment (QRA) approach for the induction of contact allergy to hair dyes in hairdressersQRA uses two independent published sources of hairdresser occupational hand exposure to hair dyesConsidering hand size differences, uneven hand exposure during hair cutting following coloration and wet working conditionsApplication to hair dyes PPD and 2,5‐TDA indicates that sensitization may occur when hand protection is not rigorously used