Japan experienced two outbreaks of serious cosmetic-induced health hazards in 2011 and 2013. One was a transdermal sensitization wheat allergy due to hydrolyzed wheat powder in face soaps, and the other was Rhododenol(rhododendrol)-induced leukoderma. These cosmetic-induced skin disorders could have been prevented if an action had been taken when a small number of cases were discovered. The authors had started a study in 2010, before the two health problems occurred, to survey cases of allergic contact dermatitis every year after the end of the business year to identify the products causing allergic contact dermatitis and their responsible ingredients. These incidents subsequently led to the establishment of SSCI-Net, a general incorporated association, in April 2016 as an outcome of a research granted from AMED to develop an online case registration system from the web to speed up case registration. This article provides an overview of a series of SSCI-Net-related studies conducted around 2016 that aimed to identify the causative products of cosmetic-induced skin disorders, compile guidance on how to identify causative ingredients and minimize risk by monitoring skin disorders after cosmetic sales.

There are approximately 8 million species of organisms on Earth. While we do not have complete knowledge about all of them, one thing we can say for certain is that they will all eventually die. The reason we can make such a claim is because all organisms are the result of evolution. Evolution can be like a program that involves “change and selection” repeating over time, where “change” creates diversity and “selection” ensures that only those organisms that are well-suited to their environment can survive. In other words, it means that other organisms die. Thus, evolution has progressed through death, leading to the birth of all living creatures, including humans¹⁾.

What causes death? Death follows the process of aging, which is caused by the accumulation of DNA damage. For instance, ultraviolet radiation can damage DNA in skin cells, leading to aging. The genomic DNA contains fragile and unstable regions that may function as “aging switches” in cells. In fact, our study in yeast has revealed that when one of these regions, ribosomal RNA gene, becomes more stable, aging is suppressed, and the lifespan is extended. If the aging signal from the switch can be identified, it may be possible to control aging²⁾.

Cells are constantly changing in response to environmental changes in order to maintain the unique functions of each organ. However, cells have a life span, and eventually they lose their ability to divide, resulting in cellular senescence. The accumulation of these senescent cells leads to inflammation, deterioration of tissue function, and the onset of disease, which in turn affects individual aging. However, the details of how the senescence process occurs remain unclear. Therefore, it is difficult to distinguish between healthy aging, which occurs as functional decline, and aging that leads to disease. Recently, however, interest in aging research has increased, and studies of cellular and individual aging have been conducted from various approaches. And clinical research for anti-aging is also being conducted. However, since we cannot shorten the time axis of aging, further research is required to fully understand the aging process. To study the aging process, we focused on glycans on the cell membrane. Glycans cover the cell surface and are involved in various biological activities, and are called the face of the cell. In other words, cellular changes correlate with glycan structures and their functions. In this section, we would like to introduce our research and the latest information on how glycan as the cellular face changes during the aging process.

Solar lentigo and melasma are common acquired disorders of facial pigmentation. The molecular mechanisms of these disorders have been extensively studied. It is now well known that sun exposure and aging are the causative factors of solar lentigo and sun exposure and female sex hormone are the those of melasma. There is a significant increase in melanin deposition in the epidermis and melanophages are recognized in the dermis in both pigmentary disorders. The strategy of these pigmentary disorders consist of skin lightening agents, chemical peeling, lasers, intense pulsed light, skin care with sunscreens, and targeting dermal cells. To avoid further inflammation and worsening of the pigmentary disorders, the professional technique and knowledge of chemical peeling and laser therapies are required. This review provides a comprehensive update on the current understanding of the pathogenesis and therapy of solar lentigo and melasma.

Makeup products, body care products and fragrance can cause skin disorders such as contact dermatitis. To identify the cause, patch testing is most useful. Based on results of the test, we can advise patients to avoid the causative products and provide daily life guidance.

Here, we will provide 6 cases of contact dermatitis to makeup products, body care products and fragrance.

Case 1: Allergic contact dermatitis due to the ethylhexyl methoxycinnamate of sunscreen base.

Case 2: Allergic contact dermatitis due to the diisostearyl malate of lipstick.

Case 3: Semiopen patch test was positive for mascara and mascara remover, but the patch testing of the ingredients could not be performed.

Case 4: Allergic contact dermatiits due to the cetanol of the hand cream.

Case 5: Irritant contact dermatitis due to the body soap.

Case 6: Photoallergic contact dermatitis due to the perfume.