Sawnet - Health -

Brown skin and sunscreen

If you live outside South Asia, you cannot help being bombarded with news and advice about sunscreen. Exposure to the sun, we hear, causes skin cancer, assorted other skin problems, and wrinkles. In South Asia, however, the topic rarely emerges. To most of us with our varying shades of brown skin, it is not obvious whether our risk is as high as Caucasians, if we've just been ignorant all these years, and if we do need sunscreen, what SPF we should use. This page is an attempt to collect the scientific facts about sun exposure that are relevant to people from the subcontinent.

UV radiation

It's the UV wavelength in solar radiation that is responsible for skin damage. UV constitutes about 5% of the total solar radiation, but is responsible for all the skin damage. UV comes in two flavours, A & B. A (320-400 nm) has lower energy , so that it penetrates more deeply but does not burn skin as easily. 98% of UV radiation is UV-A. UV-B (290 - 320 nm) has higher energy, penetrates only the outer skin layers, but causes skin to burn easily. It was formerly thought that only UV-B contributed to skin damage, but evidence is mounting (see Ref 2 for example) that both forms of UV can damage the skin.

UV-A is more or less constant throughout the year, and is not absorbed by the ozone layer. UV-B increases in summer, at higher altitudes and closer to the equator. (so you are at most risk when climbing Mt. Kilimanjaro in December!) It is partially absorbed by the ozone layer, and thus is highest in places like South Africa and Australia where the ozone layer is thin.

Melanin

Melanin is the pigment that makes skin brown. People with more melanin have darker skin. Melanin absorbs UV and is thus a natural sunscreen, and is probably the reason that dark skinned people have a tenth of the skin cancer rate of fairer folks. When fairskinned people are exposed to the sun, this stimulates melanin production in their skin, thus giving them a 'tan', but along the way causes lots of skin damage. The two most common forms of skin cancer, basal cell carcinoma and squamous cell carcinoma, are found largely in fairskinned people. (Ref 4.)

Some Indians, Pakistanis and Afghans have very light skin and eyes, which may indicate that their risk factors are similar to those of Southern Europeans (Italians, Spanish, Greeks). This is a lower risk level than that of Europeans with Celtic ancestry.

Apart from cancer, sun exposure will also eventually cause everyone to wrinkle, though this effect is also less for those with darker skin. This wrinkling is called "premature aging", and skin becomes thick, wrinkled and leathery. In many countries this is considered the normal result of aging, but it can be prevented to some extent by reducing sun exposure.

Research

There is very little research on sun protection for dark-skinned people. A search of PubMed shows that there is lots of research on skin damage, but the abstracts indicate that almost all the research has been performed on fair-skinned subjects. Several studies have noticed racial differences in skin cancer rates, but there are few studies within South Asian populations. Most web pages that list risk factors and SPFs are based on Caucasian skin.

Risk factors: People with skin types I, II and III are at greatest risk.

(from Ref 8)

The Phillips skin type table (PDF) has a self-test of skin type. Chances are you will be able to identify your own type from the photographs.

Sunscreens and other skin treatment

There is more and more evidence that both forms of UV damage the skin, but most sunscreens protect only against UV-B. Some "broad-spectrum" sunscreens protect against UV-A (ref 11) but it is important to check the UV-A SPF. Sunscreens do prevent sunburn in fairskinned people, but they may not (Ref 5)

If you decide to use sunscreen, what SPF do you need? The Phillipine Dermatological Society says that brown skin has a natural SPF of 4-5. Most recommendations (e.g. Texas A&M University) recommend an SPF of 6-15 for brown skin.

Clothing is a noncontroversial, completely safe way to protect against sun damage. Loose long clothing like salwar kameez is ideal for protection, as are long pants and shirts. Cotton clothing has a UPF (equivalent to SPF) of about 5, and interestingly, well-washed cotton is even better (Ref 12, so pull out those old kurtas). Sunscreen is necessary only for the exposed parts of the body.

Whatever your skin colour, sunscreen may be a good idea if you're planning extended intense sun exposure, such as a day at the beach.

Note that prolonged use of bleaching creams (Fair and Lovely, for example) can burn the skin because they remove the inherent melanin protection of brown skin. Most bleaching creams contain hydroquinone which blocks the production of melanin and also destroys the skin's melanocytes, thus increasing skin sensitivity to sun. (Ref 8)

Sunscreen and children: Children tend to play and stay in the sun more than adults. Research indicates that one blistering sunburn in childhood doubles the risk of skin cancer in later years. (Ref 13), and several web pages assert that most people receive 80% of their lifetime sun exposure by age 18. (e.g. Ref 10), so that it is very important to protect children from the sun. As with adults, dark-skinned children have more inherent protection against sun damage.

Previous recommendations were that sunscreen should not be used on children under 6 months of age. The American Assoc. of Pediatrics now says that "when adequate clothing and shade are not available, parents can apply a minimal amount of sunscren to small areas, such as the infant's face and back of hands".

Sunglasses

As opposed to skin cancer, cataracts are more common in tropical or sunny areas. Brown/black eyes don't seem to protect against eye damage from the sun, unfortunately. A pair of UV-absorbing glasses are highly recommended.

Prickly Heat

Prickly heat is common in South Asia, and it is not the same as sunburn. Its official name is milaria, and it occurs mostly in hot humid environments. The sweat glands get blocked, sweat is trapped under the skin causing itching. It occurs under clothing, and even when out of the sun. The cure is to cool and dry the affected areas.

References


Susan Chacko, all errors mine alone