| SKIN PIGMENTATION | OPINION T
HROUGHOUT HISTORY, the colour of oneÕs skin has been a matter of great significance, raising as it does questions of race, class and aesthetics. The Romans
used lead-based paints and chalks to lighten the colour of their skin, a practice that was also evident during ShakespeareÕs time, when lighter skin was associated with higher social status (because a tanned or weather-beaten complexion implied outdoor manual labour). In the 20th century, fashion designer
Coco Chanel was attributed with being among the first to popularise a suntan. The trend received a boost during the 1930s from the popularity of outdoor pursuits such as walking and cycling, and continued after World War II. By the 1970s, when most people worked indoors, the situation of previous centuries was completely reversed, with the possession of a tan implying higher social standing and the financial means to Ô follow the sunÕ. More recently, of course, since the
dangers of exposure to the sun have become better understood, the pendulum has again begun to swing in the opposite direction. But while it has been fashionable for
people of Caucasian origin to try to darken their skin by tanning, the opposite phenomenon can be observed in people with naturally dark skin. Again, the origins of such a practice are historical and cultural. For
example, it has been
documented that before emancipation in the US, slaves with lighter skin generally enjoyed greater freedom and opportunity than their dark-skinned fellows. Slave traders perpetuated the idea that light-skinned black women were particularly suitable for domestic service, while darker-skinned slaves were only suited to heavy physical work. Gradually, lighter skin came to be regarded as physically more attractive, both among the white and the black communities. Given the advantages that accrue from
having a lighter skin tone, it is not surprising that a demand grew for ways to lighten dark skin, and many products have emerged to meet this demand. Around the end of the 19th century and the first two or three decades of the 20th century, products with names such as Snow White Bleaching Cream were heavily promoted to black people, often showing pictures of white women and
In the 20th century,
fashion designer Coco Chanel was attributed with being among the first to popularise a suntan.
PETER CHARLISH Principal Analyst, Informa Business Information
email:
peter.charlish@
informa.com
implying that the product would increase the attractiveness of darker-skinned women. Today, skin lightening products are
used not just by individuals of African descent, but also by people in other parts of the world where skin colour can affect perceptions of social status, such as India. At the same time, while the original users of such products were predominantly women, men have also become the targets of product advertising.
Medical conditions As well as the desire to lighten the skin for cosmetic reasons, there are a number of medical conditions associated with hyperpigmentation that are treated with products designed to lighten the skin. These include: ■ Melasma (chloasma), where brown or greyÐ brown patches appear on the face or other parts of the body
■ Post-inflammatory hyperpigmentation
■ AddisonÕs disease ■ Acanthosis nigricans, hyperpigmentation of areas of skin that rub together, associated with insulin resistance
■ Linea nigra, a hyperpigmented line that can appear on the abdomen during pregnancy.
In addition, a number of drugs can
cause hyperpigmentation including bleomycin, cisplatin and salicylic acid. The primary determinant of skin
colour is the pigment melanin, which is derived from the amino acid tyrosine. From an evolutionary point of view, the presence of melanin in the skin is highly desirable as it absorbs harmful ultraviolet radiation, thus helping to prevent DNA
damage that can lead to skin cancers such as melanoma. There are a number of types of melanin: the most common form in skin is eumelanin, of which there are two types (black and brown), while a second form of melanin, pheomelanin, has a pink to red colour and is particularly found in the lips and similar parts of the body. The precise skin colour is determined by the relative amounts of the different forms of melanin. Most skin-lightening products act by
inhibiting the formation of melanin, rather than bleaching the skin per se. Probably the most widely used ingredient for reducing melanin synthesis is hydroquinone, which inhibits the enzyme tyrosinase. This enzyme catalyses the oxidation of a number of phenolic compounds in the body, but in the present context is involved in the formation of a number of intermediates in melanin synthesis. A congenital deficiency of tyrosinase is associated with albinism, where there is an absence of pigment in the skin, hair and eyes. Already suspected on the basis of animal experiments, the potential of hydroquinone as a skin-lightening agent was confirmed in 1940, when depigmentation of the skin was noted among workers at a tannery in Chicago. The cause of the depigmentation was traced to the monobenzyl ether of hydroquinone, which was present in the rubber gloves worn by the tannery workers. This led to hydroquinone being used in various concentrations in creams for treating conditions associated with melanin hyperpigmentation. However, soon after hydroquinone
began to be used, it became apparent that, not only was its hypopigmenting effect
prime-journal.com | April/May 2012 ❚ 65
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