• Anna Solana, science journalist

    Skin types: phototypes

    2 Jan

    Medicine currently classifies human skin in six phototype groups (I to VI), based on sensitivity to the sun and covering people as different as platinum blondes and redheads to people with dark brown or black skin. It is important to know our skin type to care for it properly.

     

    Smooth, firm, flawless and glowing skin, or oily with open pores and imperfections? For the cosmetics industry, the physiology of skin —which depends on age, hormones and external factors like the climate, pollution and lifestyle— is linked to the external appearance of the mantle that envelopes our body: dry, oily, mixed or sensitive. For medicine, however, skin type is determined by its capacity to assimilate solar radiation.
     
    Our skin type, or phototype, is based on a set of characteristics that determines the sensitivity of our skin to ultraviolet radiation. In other words, it tells us to what extent our skin is capable of going brown, which, in turn, depends on pigmentation, determined by genetic factors.

     

    The most vulnerable skins
    Whiter, less pigmented (e.g., Celtic) skins are usually more sensitive to the sun’s radiation and more likely to burn, age and develop erythema or skin cancer. This kind of skin is classified as phototype I in the group of six phototypes (I to VI) described in the internationally accepted scale developed by Thomas B. Fitzpatrick in 1975. This highly vulnerable skin is associated with platinum blondes and redheads with numerous freckles, who need to take great care with the sun. This means not only using sunscreens with a minimum sun protection factor of 20, but also avoiding the sun in the central hours of the day and seeking shade to avoid over-exposure.

    The same recommendations apply to people with phototypes II (Caucasian), III (mixed Caucasian) and IV (Mediterranean). However, these skin types, according to a study published in the Revista de la Facultad de Farmacia of the University of the Andes (Venezuela), have a higher Natural Protection Index, which means that they can tolerate longer exposure to the sun without a sunscreen. Nonetheless, people with phototype II are also prone to sunburn, although, unlike phototype I, the skin will tan somewhat. People with this skin type generally have blonde or fair hair and blue, grey or green eyes.

     

    The most common phototype
    The most common phototype, III, is associated with people whose skin tends to go red first but then tan after a few days of exposure. People with this skin type usually have brown hair and brown or green eyes. People with phototype IV have olive-coloured skin, dark hair and brown eyes and tend to tan quickly. Phototype V people (Hispanic and Amerindian) typically have brown skin, dark hair and brown eyes and only burn if over-exposed to the sun. Finally, phototype VI people (Africans) have dark brown or black skin, black hair and dark brown eyes and their skin only burns in conditions of extreme exposure to the sun. Naturally, in referring to sun exposure, we need to take geographic region, climate, altitude, latitude, surface, time of day and season into account.

    Double the care need to be taken with children, since their skin is in still maturing and has not yet developed natural mechanisms to protect itself from the sun’s radiation, namely, thicker skin, melanin secretion and sweat glands.

    Despite the usefulness of the Fitzpatrick classification, a number of scientists have questioned, for instance, the criteria for determining the colour of a skin and deciding its phototype. A study by dermatologists at the Faculty of Medicine and Surgery of the University of Siena (Italy) recommends measuring constituent skin colour in the part of the body normally least exposed to the sun: the buttocks.

     

    A popular skin classification
    For most of the population, skin type continues to be associated with adjectives like normal, dry, oily, mixed or sensitive. Normal skin is optimally hydrated and is firm, elastic and glowing. Dry skin lack protective water or lipids, or both. Oily skin secretes excessive amounts of sebum and is prone to acne in both adolescence and adulthood. Mixed skin has the microrelief of normal skin but secretes excessive sebum in the T-zone (forehead, nose and chin area). Finally, sensitive skin reacts strongly to certain stimuli.

    Knowing that our skin needs more hydration or that our pores become less sensitive to excessive sebum with the passing of time does not mean that should not know our phototype, as this knowledge is important in terms of preventing the sun from leaving permanent marks on our skin.

     

     

    Sources:
    Skin Type: DermNet

    Skin phototypes: Scientific Committees of the European Union

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