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Recently, animal experiments become very difficult to be done in the research and development of cosmetics and cosmeceuticals due to animal welfare and 3Rs (replacement, reduction, refinement) concept. However, usefulness and safety of these preparations must be strictly guaranteed before human use. We thus proposed three sets of extrapolation methods to estimate in vivo profiles from in vitro and in silico approaches, to evaluate permeation profiles through real human skin from those through animal skin and cultured human skin model, and to estimate responses such as usefulness and safety of cosmetics and cosmeceuticals from their skin permeation and concentration profiles. Although we need more data and discussion, the present extrapolation methods must be very useful for estimation of cosmetics and cosmeceuticals without using animal experiments.

Background: Eyelash extensions involve the attachment of synthetic eyelashes made of chemical fibers or other materials individually onto natural lashes. However, there are no uniform or well-established guidelines for this procedure. Consultations with ophthalmologists and local consumer centers regarding eyelash-extension-related skin and eye disorders have been increasing yearly throughout Japan. This study was conducted to obtain epidemiologic data on eyelash extensions and their related health problems among the Japanese., Methods: A web-based survey was prepared and conducted with questions regarding the basic characteristics of the study participants, their experience with eyelash extensions (including the number of procedures, frequency of extension, year of first extension, and years since the first extension), and any extension-related health problems. Data from 2000 women, aged 15 to 59 years and randomly selected from across the country in accordance with the demographic composition of Japan, were included in the analysis., Results: In total, 205 (10.3%) respondents reported having experienced eyelash extensions (average, 6.2 procedures; median, 3.0), with a peak among those aged 25 to 29 years and a larger proportion of those living in urban areas than in rural areas. Of these women, 55 (26.8%) experienced health problems such as ocular hyperemia, pain, and itchy swollen eyelids. Multivariate analysis revealed that short intervals of extensions were associated with health problems (multiadjusted odds ratio (95% confidence interval); 2.88 (1.09-7.61))., Conclusions: Eyelash extensions are a popular procedure, especially among urban, young women. However, attention must be paid to the potential health risks of the procedure.

Cosmetics are defined as "articles with mild action on the human body, which are intended to be applied to the human body through rubbing, sprinkling or other methods, aiming to clean, beautify and increase the attractiveness, alter the appearance or to keep the skin or hair in good condition (The Pharmaceutical Affairs Law: Article 2)." Consequently, they include personal hygiene products such as shampoos, soaps and toothpaste. In Europe, 1% of the population is estimated to be allergic to fragrances and 2-3% to ingredients of cosmetics; 10% of outpatients patch-tested for cosmetics allergy were found to be positive. Allergenic ingredients of cosmetics can be fragrances, hair dye, preservatives, antioxidants, emollients, surfactants, UV absorbers, pigments or resins used in nail cosmetics. Among standard allergen series, eight substances are related to cosmetics; in Japan in 2003, p-phenylenediamine (hair dyes) induced allergic reactions with the highest rate of 7.9% in outpatients patch-tested (n=805), followed by fragrance mix No. 1 (4.0%, mixture of eight fragrances frequently used), colophony (3.2%, main contents of pine resin), lanolin alcohol (2.7%,emollients), and formaldehyde, parabens, Kathon CG (2.7% ,1.9% and 1.0%, respectively; preservatives). Cosmetic allergy symptoms tend to be mild except those caused by hair dye. However, the population exposed to cosmetics is huge and the number of ingredients used in cosmetics increased up to more than 6000. Here, major cosmetic ingredient allergens, mainly reported in Japan, are reviewed and discussed.

Although cosmetic manufacturing has progressed significantly, we still see a lot of skin problems caused by cosmetics. We patch tested 307 patients who showed signs of cosmetic contact dermatitis on the face from using their own cosmetics. The most common sensitizers were hair dyes, especially paraphenylenediamine (PPDA). Eighty-six of the 307 patients were assessed with patch tests for 23 perfumes, 16 tar dyes, preservatives, bases and 7 other items. Perfumes were frequently identified as allergens such as hidroxycitronellal, which turned out to be the most common sensitizer. The eighty-six patients were divided into 7 groups according to the clinical features and were discussed in terms of the period of onset and their age distribution. The relationship between positive patch test results and atopy is also reported.