Recently, many reports on the influence of ultra-violet (UV) rays to the skin have been published. In order to protect the skin from UV rays, many sunscreen products have been developed and marketed. However, few consumers understand how to use these products exactly as well as what is the suitable product for practical use. Present paper reviews the recent progress of sunscreen products and raw materials from the patents published. Our attention to the formulation of sunscreen products are also discussed. These information provide the appropriate usage and knowledge of the products to consumers as well as cosmetic technologists.

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The biological effects of solar ultraviolet light, UV-A (320-404nm) & UV-B (290-320nm) on animals, plants, and oceanic phytoplanktons, and eye lens were mentioned on the rather general point of view.
The UV-B irradiance on the earth's surface is increasing year with decreasing in the stratospheric ozone layer thickness in the present global circumstance. At first, after the speculation of relationship between the destruction of ozone in the stratosphere and the artificial chemicals, CFCs, the formation of DNA lesions produced by the solar ultraviolet light (UV). The UV-B induced DNA lesions are mainly two kinds of dipyrimidine complex, that is, cyclobuthane type dimers and (6-4) type photoproducts. The DNA lesions by UV-A are mainly peroxidized or deaminized pyrimidines and ruptured guanine. The production of strand breaks and crosslinks in DNA molecules are also the serious DNA damage by UV-A.
It is known that the incidence of nonmelanoma skin cancer and malignant melanoma correlates well to the irradiance of solar UV, especialy to that of UV-B. The solar UV corresponds strictly with the solar height from the earth's surface; that is, the reverse degree of earth's latitude. The UV-B irradiation suppresses the skin immune function not only at the irradiated site, but also the systemic immune ability of animals. Although the UV-B irradiation is a powerful cause for induction of skin inflammation, UV-A irradiation seems more powerful cause for that, because, the amount of UV-A reaching to the skin is usually about 10 times more than that of UV-B, and UV-A can penetrate deeper into the skin as compared to that of UV-B. So, the UV-A irradiation suppresses also efficiently the animal immune function. The author claimed that the biological effects of UV-A was rather more serious than those of UV-B, especially for skin cells. It must depend upon the active oxygen species produced by the chromophores in cells by absorbing the UV-A energy. The main undesirable function of active oxygens to organisms is peroxidation or denaturation of the important cell materials keeping the cell function and the structural proteins normally. Induction of skin inframmation is mainly caused by the peroxidation of lipoproteins in cell membranes. As an example, the phenomenon that the release of arachidonic acid, which is the precursor for the formation of prostaglandins, is more pronounced in the case of UV-A irradiation than that of UV-B was shown. The inframmation of cell membrane results in the decrease in membrane intactness and in some case cell morphological collapse. However, it is not usually reasonable that the biological function of UV-A is only the peroxidation of the cell lipids through the active oxygens produced by this light, because the enzymatic decomposition of low density lipoprotein (LDL) in UV-A irradiated cell is not completely protected by a scavenger (vitamine E+C), although the formation and release of peroxidized lipids of membrane occurred significantly by UV-A irradiation, which suggests a possibility that, proteins (LDL-digesting enzyme) could be the target for the UV-A, in stead of lipids. Decomposed figures of protein structures in cells, especially, fibrous proteins were detected in UV-A irradiated cells by electron microscopic observations.
The effects of solar UV on plants referred also for the agricultural and eco-systemic point of view. The production of crop yield of grains and the seedlings of many kinds of vegetables is in generally suppressed significantly by the solar UV, practically by UV-B irradiation. Especially, the easily induced inhibition of proliferation of oceanic phytoplanktons by solar UV penetrating into the sea is a serious global problem; that is, as food problems for human and the earth's climate, because phytoplanktons are the first step organisms in so called food chain, and the huge population of the planktons is the most effeicient absorber of CO₂ in the atmosphere of the

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It has long been thought that the tone of foundation (applied color) could not be accurately determined until after the foundation was applied to bare skin. Only then could the applied color be judged visually or by quantitative color measurement. However, as reported previously, the authors demonstrated that the spectral reflectance of applied color can be estimated using the Kubelka-Munk theory.
Two different approaches can be used to achieve a desired applied color. One involves completely masking the underlying skin with the applied color. The other involves skillfully blending the spectral reflectance properties of the individual's skin and the optical properties of the translucent foundation layer to be applied to the skin. In the later case, the foundation layer is expected to possess some transparent qualities, and it is therefore difficult to determine beforehand which foundation will yield the optimum color when applied to the individual's bare skin. In addition, in order to achieve exactly the desired applied color, it would be necessary to prepare a wide range of foundation colors due to the wide range of individual differences in skin color This task would be virtually impossible in practice.
The authors have overcome this problem by developing a numerical method based on a tristimulus matching for predicting the mixing ratio of four monotone color bases to achieve a targeted applied color. The mixing ratio can be predicted by incorporating the factor that describes change in color when foundation is applied to skin (reported in the previous study) into the color matching method using two-constant proposed by Allen.
This report describes the method for predicting the mixing ratio, validates the algorithm, and adduce several cases of calculating the mixing ratios of monotone color bases.

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Darkening of the skin is a well-known phenomenon that presents a cosmetic problem for a large number of women. However, the physiological significance of darkening and the mechanism by which it occurs are not precisely understood. Precipitation of melanin and changes in hemoglobin level have both been suggested as possible causes of darkening, although there is no firm evidence linking these causes to the phenomenon.
Since apparent darkening is a psycho-physical phenomenon, it is necessary to first investigate the nature of light reflected from the skin. The authors therefore attempted to express the spectral reflectance of light reflected from the skin as a single linear expression to isolate the factors that contribute to apparent darkening. Significant correlations were observed between the results of visual evaluation of darkening and the spectroscopic characteristics of light reflected from skin with various amounts of melanin and blood flow values.

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In order to get natural anti-irritants for mild cosmetic products, several plants have been evaluated by the MTT assay of 3 D-Histoculture. Guinia pig skin irritation test, and Red Blood Cell membrane lysis.
As the results, it is found that Betula Pendula bark extract with several solvents reduce irritation score of SDS, and the extract with ethyl acetate exhibits the highest effect among them. It is also indicated that three triterpene derivatives in the ethyl acetate extract act as the anti-RBC lysis and it seems that the hydrophobicity of compounds plays an important role in the anti-RBC lysis mechanism.

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Long lasting performance is very important for make up products. Ideally, the make up color should not change after the application until it is removed. In investigating the causes of make up degradation, we discovered that the wetness of the pigments by secreted sebum from skin is an important factor causing “sebum darkening” which reduces the freshness and attractiveness of the make up.
We attempted to prevent sebum darkening by incorporating spherical silica into the make up formula in order to increase oil absorption. This, however, resulted in only a small improvement. For more substantial improvement, a new approach or new materials were needed. After testing many materials, it was found that titanium dioxide encapsulated in a porous of spherical silica, was the most effective. This process is believed to be due to the unique ability of the encapsulated titanium dioxide to maintain the brightness of the make up even after the silica is wet by sebum and becomes transparent. By using titanium dioxide encapsulated in silica, we have developed a long-lasting make up foundation and solved the sebum darkening problem which has troubled the make up manufacturers for many years.

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An optimized FAB-MS measurement method has successfully been incorporated into the systematic analysis method of cosmetic products based upon a stepwise elution silica-gel column chromatography as a skeleton fractionation method and a combined use of ¹³C-NMR and GC/MS. The system was able to precisely identify the components such as polyoxyalkyleneglycol, oxyalkylated nonionic surfactants, polyglycerin and its derivatives, etc. for their alkyl and/or oxyalkylene chain distributions, which are eluted in the acetone and methanol fractions in silica-gel column chromatography. A simulation was carried out for various cosmetic ingredients based upon the results of spectral analysis and it was constructed in a simple retrieval system using a database of the numerical values and chemical structures. Reflection of a mixture state to the spectrum has been studied semi-quantitatively including an optimization of measuring conditions.

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The hair conditioning effect of stearamidoethyl diethylamine (AEAS) was evaluated in terms of the kinetic frictional coefficient (μk) of hair and surface electric resistance (Rs) of woolen cloths. In addition, the thermal property of a gel composed of AEAS, cetyl alcohol (C₁₆OH) and water was studied using DSC measurements. The mixed system of AEAS-C₁₆OH-water formed a gel structure similar to that occurring in the ternary system of stearyltrimethylammonium chloride (STAC)-C₁₆OH-water. The melting point of the STAC-gel continuously increased with increasing molar ratio (C₁₆OH/STAC) up to 3 above which it became constant at 71°C. On the other hand, that of the AEAS-gel became constant above the molar ratio of 4-5 at 68°C. It was found that AEAS is comparable to STAC in reducing μk and Rs.

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Some of the viscoelastic properties of cosmetics (mainly creams and milk lotions) are supposed to have close relationship with sensory evaluation terms such as smoothness, richness and feeling of film thickness, etc. A new instrument equipped with a newly-developed tactile sensor was designed and introduced in order to measure viscoelasticity and the film thickness of cosmetics under the high shear-rate condition. 2 types of milk lotions which have different results of sensory evaluation were measured by the instrument. The results obtained from the instrument were found to correspond to some of the sensory evaluation results and the idea of measuring viscoelasticity and the film thickness of cosmetics under the high shear-rate condition was proved to be effective.

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