Portable erythema meter and its application to use in human skin

In this study a compact, hand-held, solid state erythema meter using light emitting diodes is described. This device has been constructed and used to compare with visual assessments of ultraviolet radiation in human subjects. A statistically significant correlation was obtained between erythema index and visual assessment in 24 ultraviolet irradiated subjects. Furthermore, the effects of three aftersun treatments have also been assessed objectively using the meter and subjectively using visual assessments. The ultraviolet-irradiated areas were less red following treatment than the irradiated and untreated areas. The results obtained by the meter were similar to and statistically significant with those obtained by visual assessment.
It is concluded that widespread use of an erythema meter such as that described would greatly improve all cutaneous erythema assessments.     

一款含鲜奶面霜缓解皮肤红斑反应的功效评价研究

采用客观仪器评价方法对含鲜奶面霜单次使用后的缓解皮肤红斑反应的功效进行研究。选择30名18~55周岁有效受试者为研究对象,使用胶带粘贴及组胺刺激构建皮肤红斑反应模型,并采用无创仪器的方式检测并记录实验组、安慰剂组、阴性组及空白组受试者在组胺造模前、造模后、涂抹产品后30 min和60 min时的皮肤红斑指数EI值、皮肤敏感度值,采集皮肤图像,通过SPSS数据统计软件对实验结果进行统计分析。结果显示,含鲜奶面霜可以持续改善皮肤红斑指数EI值和皮肤敏感度,缓解由组胺导致的皮肤红晕反应,说明其具有一定的缓解皮肤红斑反应,改善皮肤敏感状态的功能。     

Methods for water resistance testing of sun protection products

Water resistance of sun protection products has been found to be best determined by the following methods: (1) Tests for determining UVL filter adherence to merino wool; this gives a rough value for orientation. Values in excess of 6% are suggestive of satisfactory adherence. (2) Tests for determining water resistance of sunscreen products on pig skin constitute a further essential step. Values in excess of 50% provide a realistic basis for tests in humans. In addition to filter adherence the product base, i.e. primarily the emulsifiers, are of special significance. Adequate results can be obtained with both W/O and O/W systems. Tests on volunteers are best done at the time of determining the sun protection factor, i.e. when simulating the events during a 2–3 h sunbath. Simulation should involve a single application of the test product in a pre-defined quantity and all activities conmmonly done in sunlight, e.g. swimming, as well as intermittent exercises to induce sweating. Values are considered as excellent, if 1 MED is not exceeded after 3 h exposure. Sun protection products with this characteristic qualify as adequate ‘all-day’ sunscreen for individuals with average sensitivity. Methodes pour mesurer la résistance à l'eau des produits anti-solaires     

Protective effect evaluation of free radical scavengers on UVB induced human cutaneous erythema by skin reflectance spectrophotometry

This paper assesses the suitability of UVB induced skin erythema measured by reflectance spectrophotometry in humans as a model for differentiating topical efficacy of free radical scavengers. Two different formulations (aqueous gels and O/W emulsions) of each active compound (tocopherol, tocopherol acetate, superoxide dismutase (SOD), glutathione, ascorbyl palmitate) were tested on healthy human volunteers before and after skin exposure to UVB radiation. Skin erythema was monitored by calculating erythema index values from the skin spectral data obtained using a reflectance spectrophotometer. The free radical scavengers tested were not able to inhibit UVB induced skin erythema from both formulations when they were topically applied before UVB irradiation. Applying the free radical scavenger formulations after skin exposure to UVB radiation, glutathione and SOD showed the best ability in inhibiting the induced erythema (percentage inhibition 53.3 and 41.6%, respectively from gels). Tocopherol and tocopherol acetate inhibited UVB skin erythema by 27% while ascorbyl palmitate showed a poor efficacy. For all the active compounds tested, no significant difference was observed comparing the results obtained from gels to those from emulsions. Liposomal gel formulations containing the free radical scavengers which showed the best activity (SOD and glutathione) were prepared and topically applied after skin exposure to UVB radiation. SOD and glutathione liposomal formulations were more effective than the corresponding conventional gels. The proposed model, if validated by further studies, could be useful for differentiating the effectiveness of free radical scavengers in inhibiting photoaging due to long-term sunlight skin exposure.     

Evaulation of irritation potential of surfactant mixtures

Irritation potential of sodium laureth sulfate (SLES) alone, and in combination with lauryl glucoside (LG), polysorbate 20 (PS) and cocoamidopropyl betaine (CAPB) was tested in 13 human subjects. Four main and six sub-formulations were prepared and evaluated. Formulations were applied to the forearm as a 24 h close patch study. Irritation was scored by two different methods using an in vivo clinical protocol based on visual scoring and on the stratum corneum capacitance measurement. Irritation was found to be dose dependent. At 2 mg/patch level ten subjects did not show any skin reaction. At 20 mg/patch level eleven subjects showed a broad range of skin irritation. The highest irritation was observed with the formula that contained SLES, LG, and cocamide DEA together. Among the sub-formulations, cocamide DEA showed the highest irritation grade. A statistically significant correlation was observed between visual, clinical and corneometer scores. It was concluded that the irritation potential of surfactants was related to the total surfactant concentration, application mode, and the thermodynamic activity of molecules in the solution as well as the chemical structure of the surfactant molecules.     

Skin colour assessment in safety testing of cosmetics. An overview

Synopsis
Few subjects are as problematical to dermatologists, cosmetologists and related experimenters involved in safety testing as the clinical assessment of skin colour. At the core of the problem is the word erythema, which does not communicate a sense for the nuance of red. In addition, light shades of red are not visible in dark-skinned people. Human assays aiming at evaluating the irritancy and allergic potential of cosmetics take advantage to use instrumental assessments of skin colour. However, there are pitfalls related to the complex biological aspects of the cutaneous reactivity, to the design of the in vivo assay, and to technical aspects bound to the principle of the measuring methods. Sound information can only be reached when these concerns are solved.
Résumé
Peu de sujets sont aussi problématiques pour les dermatologues, cosmétologues et autres expérimentateurs impliqués dans les tests de sûreté que l'évaluation clinique des couleurs cutanées. Au centre du problème est le mot érythème qui ne communique pas la notion des nuances de rouge. De plus, un érythème discret peut ne pas être visible chez des individus à la peau foncée. Les tests humains visant àévaluer les potentialités d'irritation et d'allergie aux cosmétiques bénéficient des évaluations instrumentales de la couleur cutanée. Cependant, il existe des pièges liés aux aspects biologiques complexes de la réactivité cutanée, au choix du test in vivo et à des aspects techniques en relation avec le principe du système de mesure. Une information adéquate ne peut être obtenue qu'après avoir résolu ces problèmes.     

Collaborative development of a sun protection factor test method: a proposed European Standard. COLIPA Task Force 'Sun Protection Measurement', Europe

Standardization of the method to determine sun protection factors (SPF) is fundamental to uniform labelling of SPF values on sun products. The COLIPA Task Force 'Sun Protection Measurement'(SPM), including representatives of major European sun-product manufacturers and contract testing laboratories, was established in 1990 to define methods for sun products testing. The process involved in developing the COLlPA SPF Test Method started with a critical appraisal of previously existing methods, and identification of areas for improvement. Experiments were performed by the participating laboratories to establish the new recommended test protocol which was then confirmed in two multicentred ring tests. Improvements to test methodology included the number and selection of volunteers and skin types, the application of the product, the definition of W output from solar simulators, and the method for assessing erythemal response (MED) including an option to use colorimetry to define objectively the 'erythemal threshold' of skin and to predetermine MED prior to exposure. Four cosmetic formulations and neutral density physical filters (SPF from 4 to 20) were tested in two ring tests. Results showed that variations in SPF of the cosmetic products were, on average, directly proportional to SPF value. An excellent correlation was found between visual and colorimetric SPF assessments (r = 0.99). An acceptable range of values for low and high SPF standard products was also established. The COLIPA SPF test method is now fully defined and supported by experimental data. Its use will harmonize SPF testing throughout Europe and help in the quest for global harmonization in testing sun products.     

Infrared photoprotection properties of cosmetic products: correlation between measurement of the anti-erythemic effect in vivo in man and the infrared reflection power in vitro

Measurements were carried out on 19 commercial cosmetic samples. Initially, their anti-infrared properties were quantified, in vivo , on healthy volunteers, by measuring variations in the Colorimetric Erythema Index ΔCEI, before and after application of a normalized quantity of product. Subsequently, the physico-chemical response of the product was tested in vitro by measuring the infrared reflection coefficient ΔIR at 800 nm.
The correlation established between these two parameters enables products to be ranked in three categories. A good correlation was demonstrated between reflective power (ΔIR) and anti-erythemic properties (—ΔCEI) of the products in the first two groups.
A qualitative examination of the diffraction of X-rays confirms the presence of titanium dioxide, TiO₂ rutile, in most products with high IR protection properties whereas TiO₂ anatase was detected in a sample with no IR reflection properties.     

Skin irritancy testing of toiletries and cosmetics on novel human models

A brief review of new techniques of assessing skin irritancy is presented. Some of the difficulties of assessing minor degrees of irritancy are discussed. Nouvelles méthodes pour l'évaluation sur l'être humain du pouvoir irritant des produits cosmetiques at d'hygiene