For the love of color: Plant colors and the dermatologist.

Humans have been anointing their skin with natural colorants since antiquity. Before the advent of modern cosmetics, tattoos and hair dyes, the spectacular colors in plants served as a palette for humanity's fascination with color. Skin, hair, nails, teeth and clothing have been altered with botanical colorants for centuries. Understanding the relevance of botanical colorants is an important part of cultural competency. Substitution or adulteration of plant colorants with synthetic colorants has played a role in varied dermatoses (eg. black henna, kumkum, and Holi dermatoses). Safety concerns over synthetic colorants have led to a resurgence of natural colorants. However, some plant colorants have produced adverse reactions. Plant colorants have also played an integral role in medicine. Ingested plant colorants are an indispensable part of our diet, playing crucial roles in the maintenance of health and prevention of disease. Excessive intake of some pigments can alter skin color (carotenoderma, lycopenemia, and the golden tan of canthaxanthin). We have relied on the colors of hematoxylin and alizarin red, derived from the logwood tree and madder roots, respectively, to study and diagnose disease in pathology. We briefly review the uses, cultural relevance, and adverse effects of the common botanical colorants on the skin, hair, and mucosa. We also describe their relevance in our diet, and in the diagnosis and description of dermatological diseases.

Sensitive skin: an overview.

Sensitive skin is less tolerant to frequent and prolonged use of cosmetics and toiletries. It is self-diagnosed and typically unaccompanied by any obvious physical signs of irritation. With the change in lifestyle and also with increased opportunity to use many new brands of cosmetics and toiletries, there has been an increase in females complaining of unique sensation in their facial skin. Sensitive skin presents as smarting, burning, stinging, itching, and/or tight sensation in their facial skin. The condition is found in more than 50% of women and 40% of men, creating a sizable demand for products designed to minimize skin sensitivity. Good numbers of invasive and non-invasive tests are designed to evaluate and predict the sensitive skin. Management includes guidelines for selecting suitable cosmetics and toiletries in sensitive skin individuals.

Nail cosmetics.

The nail as an anatomic structure protects the terminal phalanx of the digit from injury. Historically, it has served as a tool for protection and for survival. As civilizations developed, it attained the additional function of adornment. Nail beautification is a big industry today, with various nail cosmetics available, ranging from nail hardeners, polishes, extensions, artificial/sculpted nails, and nail decorations. Adverse events may occur either during the nail-grooming procedure or as a reaction to the individual components of the nail cosmetics. This holds true for both the client and the nail technician. Typically, any of the procedures involves several steps and a series of products. Separate "nail-bars" have been set up dedicated to serve women and men interested in nail beautification. This article attempts to comprehensively inform and educate the dermatologist on the services offered, the products used, and the possible/potential adverse effects related to nail-grooming and nail cosmetics.

Adverse reactions to cosmetics and methods of testing.

Untoward reactions to cosmetics, toiletries, and topical applications are the commonest single reason for hospital referrals with allergic contact dermatitis. In most cases, these are only mild or transient and most reactions being irritant rather than allergic in nature. Various adverse effects may occur in the form of acute toxicity, percutaneous absorption, skin irritation, eye irritation, skin sensitization and photosensitization, subchronic toxicity, mutagenicity/genotoxicity, and phototoxicity/photoirritation. The safety assessment of a cosmetic product clearly depends upon how it is used, since it determines the amount of substance which may be ingested, inhaled, or absorbed through the skin or mucous membranes. Concentration of ingredients used in the different products is also important. Various test procedures include in vivo animal models and in vitro models, such as open or closed patch test, in vivo skin irritation test, skin corrosivity potential tests (rat skin transcutaneous electrical resistance test, Episkin test), eye irritation tests (in vivo eye irritancy test and Draize eye irritancy test), mutagenicity/genotoxicity tests (in vitro bacterial reverse mutation test and in vitro mammalian cell chromosome aberration test), and phototoxicity/photoirritation test (3T3 neutral red uptake phototoxicity test). Finished cosmetic products are usually tested in small populations to confirm the skin and mucous membrane compatibility, and to assess their cosmetic acceptability.