The sun provides warmth for humans, but it also carries invisible dangers.  The ultraviolet rays prompt the skin to produce melanin, the skin pigment that darkens to a tan as well as vitamin D.  For this reason, a good tan is sometimes regarded as the sign of good health.  Yet, the ultraviolet rays also lead to cumulative damage to the skin, leading to sunburn soreness, wrinkles and aging.  Worse yet, the ultraviolet rays can damage the genetic materials in skin cells, resulting in skin cancer such as such as melanoma and basal and squamous cell carcinoma.  Against the potentially damaging effects of the sun's ultraviolet rays, some people use various suntan/sunscreen products.

We will now cite some survey data from the TGI Brasil study.  This is a survey of 5,312 persons between the ages of 12 to 64 years old who were interviewed during the first half of 2002.  According to this study 26.2% of the people said that they had used a sunscreen or sunblock product within the last 30 days.

As a country, the climate of Brazil varies considerably from the mostly tropical North (the equator traverses the mouth of the Amazon) to temperate zones below the Tropic of Capricorn (23°27' S latitude), which crosses the country at the latitude of the city of São Paulo . Brazil has five climatic regions--equatorial, tropical, semiarid, highland tropical, and subtropical.  The following chart shows the incidences by city.  Here, there are in fact two factors involved --- proximity to the equator (as in the cases of Salvador and Recife ) and proximity to beaches (as in the case of Rio de Janeiro ).  When either is true or both are true, the incidences rise.  When neither is true, the incidence falls (as in the case of Sao Paulo ).

Melanin appears to absorb and deflect the rays of UV light. In addition the larger, individually dispersed melanosomes have a higher melanin content and are able to absorb more UV light energy than the aggregated, smaller melanosomes with less melanin content found in fair-skinned white subjects.

Although melanin confers a protection from UV radiation, pigmented skin can also experience significant photo-damage, manifested by epidermal atypia and atrophy, dermal collagen and elastin damage, and marked hyperpigmentation. Melanin is not an efficient absorber of UV light of longer wavelength (eg, UVA spectrum > 320 nm). Infrared radiation may also overwhelm the protective effects of melanin. Furthermore, it has been suggested that melanin is both a photoprotector and a photosensitizer. This pigment can be photoreactive, resulting in the production of damaging free-oxygen radicals.

Due to differences in epidermal melanin content, melanosome dispersion and reactivity of melanocytes compared with fair-skinned persons. Studies have also demonstrated differences in hair structure and fibroblast size. These differences account in part for the lower incidence of skin cancer in certain people of color compared with fair-skinned persons; a lower incidence and different presentation of photo aging; and different pigmentation disorders. Click on this link for Sunblock Products suitable for Latina Skin Sunscreens/Sunblocks