Sun protection works, but people apply badly, warn scientists – Business Times

The ultraviolet radiation exposure is the most important factor of its effectiveness. (Photo: Disclosure) "width =" 620 "/> Research shows that the application of the protector plays an important role in its effectiveness. The main cause of skin cancer, but it can be avoided by using sunscreens. It turns out that the correct application of the product is essential to prevent damage to the DNA, prevents a study published Wednesday in the journal Acta Dermatology-venereology. In the manufacturers' tests, the researchers say, a layer of 2 milligrams per square centimeter is applied to achieve the stated protective factor, a hard-to-measure amount, and the typical use is only 0.75 mg / cm².

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– Most people do not apply this amount, nobody wants to fill it and sunscreen is still expensive in Brazil – says Sílvia Schmidt, director of the Brazilian Society of Dermatology . In the experiment, researchers from King's College London shared 16 white-skinned volunteers in two groups with three women and five men each. One group underwent only one radiation exposure, while the other underwent exposures for five consecutive days. All covered parts of the skin with different amounts of filter – 0.75 mg / cm², 1.3 mg / cm² and 2 mg / cm² – and left a room without protection.

In the group having received more than one exposure, the radiation levels were at different levels of intensity to simulate conditions in common tourist destinations among the British such as Tenerife, Florida and Sao Paulo. To badess protection, the researchers took small skin samples from each exposed area of ​​each participant for biopsies.

The results show considerable damage to DNA in areas that have not received sunscreen in the group receiving multiple exposures. even at low levels of radiation. The researchers found that five days of exposure to high doses of ultraviolet radiation (UV radiation) were badociated with increased exposure to UV radiation, with a layer of 2 mg / cm 2, showed less damage to the skin only one day's DNA with a low dose of unprotected radiation in all participants.

– There is no discussion about the important protection that sunscreens offer against cancer caused by the impact of the sun's ultraviolet rays, says Young, lead author of the study, Antony Young. However, what this research shows is that the way the protector is applied plays an important role in its effectiveness.

In the laboratory, the application of the amount recommended by the manufacturers is simple. As the skin test area was delineated in areas of five centimeters by seven, it was sufficient to weigh 70 milligrams of protector and apply it as evenly as possible. But on a daily basis, this measure is not feasible. Therefore, the recommendation is to use filters with high protection factors and reapply the product continuously.

– There is a myth that the filter with the protection factor 15 is sufficient. In theory, yes, but in practice, it is impossible to track the correct use. Therefore, it is recommended to use filters with higher protection factors of 30 or 50 – Sylvia Alert. – And do not forget to reapply, especially during walks on the beach.