Effect of mineral oil and linoleic-acid-containing emulsions on the skin vapour loss of sodium-lauryl-sulphate-induced irritant skin reactions

This study evaluates the influence of mineral oil and linoleic-acid-containing emulsions on the skin vapour loss (SVL) of detergent-induced irritant skin reactions. During a period of 2 weeks, 2 x 45 min applications of a sodium lauryl sulphate solution of low molarity were performed on the forearm of 9 volunteers. In the same period, a standard amount of each emulsion was applied on the induced irritant skin reactions, 3 times each day. The effect of the emulsions on the barrier function of the skin was evaluated by means of SVL measurements. The emulsion based on mineral greases significantly reduced SVL values during both weeks, possibly because of an occlusive effect. The emulsion with 15% of linoleic acid significantly reduced SVL values during the 1st week but not during the 2nd week. The emulsion with 38% of linoleic acid did not reduce SVL values at all.     

The transient and cumulative effect of sodium lauryl sulphate on the epidermal barrier assessed by transepidermal water loss: inter-individual variation

The aims of the investigation were: 1) to study the inter-individual variation in time course of TransEpidermal Water Loss and of clinical manifestations after a 24-h single exposure to Sodium Lauryl Sulphate. This TEWL time course (expressed as the difference in TEWL between the day of patch removal and a subsequent day) reflected the epidermal barrier response to the damage caused by SLS; 2) to investigate the association between the TEWL time course after the single SLS exposure and the TEWL value after 4-day repeated SLS exposure (as a model for cumulative irritation). The 35 healthy subjects tested could be divided into four sub-groups according to the day of their maximum TEWL value after the single SLS exposure (days 2 to 5). For the whole group, inter-individual variation in TEWL course was most pronounced in the first days following the single SLS application. Moreover, there was an inverse relationship (R = -0.61) between TEWL course during the first days after the single exposure and the TEWL value after 4-day repeated exposures. It is concluded that this association illustrates the importance of an adequately responding barrier function against the continuous exposure to irritants in daily life.     

Prediction of susceptibility to an irritant response by transepidermal water loss

The roles of the natural permeability of the stratum corneum to water, and the changes in that permeability effected by a single patch test, were investigated as parameters to predict the susceptibility of the skin to repeated exposures of an irritant. One site on the forearm skin of 27 non-atopic healthy subjects was exposed to a 0.5% concentration of sodium lauryl sulphate by a single occlusive 24-h patch. Another site was exposed to a twice daily 4-day repeated occlusive patch with the same irritant solution. The effects were evaluated by transepidermal water loss measurements made prior to the applications (baseline) on day 1 (BASE), following the single 24-h patch on day 2 (SINGL), and following the 4-day repeated applications on day 5 (REPET). Individuals with higher BASE had higher SINGL (R = 0.80, P less than 0.001) and higher REPET (R = 0.76, P less than 0.001). There was also a significant linear correlation between SINGL and REPET (R = 0.63, P less than 0.001). Multiple linear regression analysis of results, however, indicated that a high baseline TEWL is better indication of an individual's increased susceptibility (high REPET) to weak irritants than a high TEWL value following a single 24-h patch test. Baseline TEWL may therefore be used as a reasonably accurate preliminary "predictive" screening test for susceptibility to irritants.     

Prediction of irritancy in the human skin irritancy model and occupational setting

It is of great importance to find ways to lower the incidence of chronic irritant contact dermatitis. In this process, it is crucial to have insight in the factors that can predict irritancy. This review offers a survey of recent findings in the field of skin irritancy testing, discussed in the context of renowned, older work. Extrinsic and intrinsic factors that may determine the outcome of irritancy testing in the human skin model are considered. In recent decades, there has been increasing interest in factors influencing the development of occupational dermatitis by means of prospective cohort studies. This promising new area of investigation is discussed separately.     

Irritancy of antiseptics tested by repeated open exposures on the human skin, evaluated by non-invasive methods

The aim of the study was to test the irritancy of 6 antiseptics in an open exposure model. The following agents were tested in their normal use concentrations using open exposures. 2 × daily for 4 days in 20 subjects: chlorhexidine 4%(CH), chlorhexidine 0.5% in ethanol 70%(CE), ethanol 70%(ET), iodine 1% in ethanol 70% (IE), povidone-iodine 10% (PI) and sodium hypochlorite 0.25% (SH). Responses were evaluated by visual scoring, subjective irritancy scoring, stratum corneum hydration (Corneometer), transepidermal water loss and laser Doppler flowmetry. Exposure to SH had to be discontinued after 4 applications because of severe subjective irritation. The same held true for IE (7 applications), whereas the other agents were exposed 8 ×. All evaluation methods showed SH to be significantly more irritating than IE, which was in turn more irritating than CH. CE, ET and PI. Thus, it can be concluded that CH, CE, ET and PI were nonirritating in this open exposure model.     

Baseline transepidermal water loss (TEWL) as a prediction of susceptibility to sodium lauryl sulphate

The rôle of different factors in the susceptibility of the skin to weak irritants was studied by means of multiple linear regression models. The skin of 37 healthy subjects was exposed to a solution of sodium lauryl sulphate of low molarity 2 × daily for 4 days. The condition of the skin was evaluated by transepidermal water loss (TEWL) measurements on the 1st day (before exposure, TEWL1) and on the 5th day of exposure (TEWL5), and by a visual scoring system. The TEWL5 value was strongly related to the TEWL1 value (R = 0.71). The influence of such factors as history of mucosal atopy, history of sensitivity to soap, dry skin, skin type, sex and age on the TEWL5 value was negligible. The baseline TEWL level (TEWL1) might be a reliable indication of an individual's susceptibility to weak irritants.