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The sun emits a continuous spectrum, which extends from high-energy X-ray radiation to low-energy heat radiation. Only UVB, UVA, visible, and infrared radiation reach the surface of the earth. The other spectral parts are absorbed by the earth΄s atmosphere. On one hand, sun radiation is essential for human life; for instance, it stimulates vitamin D synthesis and is important for human wellbeing [6]. On the other hand, high doses of UV radiation can cause sunburn, immune-suppression, skin aging, and even skin cancer [11, 13]. However, the human body has developed protection strategies against UV radiation by increasing melanin synthesis, which is an efficient UV absorber [12, 19]. Additionally, melanin has strong scattering properties in the visible spectral range, which reduce the penetration of the sunlight into the living tissue [1]. The high melanin concentration in the skin is the base of visible sun-tanning effect. Furthermore, UV radiation may induce an increase in the thickness of the uppermost layer of the human skin – the stratum corneum. This effect is called hyperkeratosis [7]. It represents an additional efficient defence against UV-radiation. The development of these protection effects takes several weeks. In most cases, in our daily life, when skin is exposed to sun irradiation, for example, during leisure activities or holidays, the skin does not have enough time to adapt to the changes originating from sun exposure. Under such circumstances, artificial sun protection is necessary. Covering the sun exposed skin with textiles and sunscreens are both effective forms of protection. In the past, the sunscreen efficacy was characterized by the sun protection factor (SPF) [11], which describes the UVB protection. Today, the UVA protection is also declared by the manufacturer on sunscreen products. [ABSTRACT FROM AUTHOR]

Antiperspirants and deodorants are two separate entities with regard to their definition, mechanism of action, and legislation. The most important methods used for efficacy proof of antiperspirants include gravimetric, biophysical, and imprint casting assessment as well as visual evaluation. Different designs for antiperspirants testing exist depending on the study objectives. Standardization of the criteria for selecting study population, measuring conditions, anatomical test site, and timing should be considered when performing antiperspirants testing in practice. Multiple products test design is useful in assessing relative differences between products and allows ranking of products and comparison with a standard of known efficacy. Clinical evaluation, that is, sniff test, microbiological analyses, and chemical chromatographic analyses are applied in deodorant testing. Sensory evaluation of the armpit malodor is still present in the routine procedure for deodorants efficacy testing. [ABSTRACT FROM AUTHOR]

The formation of skin hydration is a complex and multifactor process including the natural sources of skin moisturization and the effect of exogenously applied substances on the skin. An objective evidence for the claimed effect of a moisturizer/emollient is required. A variety of non-invasive methods for the evaluation of skin hydration exist, however none discloses the complete interactions between a moisturizer and the skin. A multiparametric approach is useful in the assessment of moisturizers efficacy. Evaluation of the cutaneous electrical properties (capacitance, resistance, impedance) is among the the most commonly used methods in proving the efficacy of moisturizers. The choice of the proper device should be based on its technical bases, the assessed parameters of skin hydration, and the objective of the study. Study design, population, anatomical test site, and procedures should be in accordance with the study aims. Controlling subject-, instrument-, and environment-related variables is a key issue in performing skin physiology study. [ABSTRACT FROM AUTHOR]

The chronological (intrinsic) and extrinsic aging demonstrate typical macroscopic, histological, and functional characteristics. The relative improvement in different parameters characterizing aging skin can be used in efficacy proof of antiaging and antiwrinkle cosmetic products. Different approaches to investigate the efficacy of antiaging products exist such as clinical evaluation and objective assessment with noninvasive methods and invasive procedures. A multiparametric approach is useful in the assessment of antiaging products efficacy. There is no uniform consensus on the protocol and the design of studies aiming efficacy proof of antiaging cosmetics. [ABSTRACT FROM AUTHOR]

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