Because of such errors, sunscreens often lose their protective effect

The wrong use of sunscreen has dangerous consequences

Sunscreens are intended to protect the skin from the harmful effects of sunlight, especially in summer. But researchers have now found that most people benefit from less than half of the protection they expect from damaging ultraviolet rays. This is due to incorrect application.

In their latest research, the scientists at King’s College London found that the typical way in which most people use sunscreen means that our skin is not really effectively protected against ultraviolet rays. The experts published the results of their study in the English-language journal "Acta Dermato-Venereologica".

How thick should sunscreen be applied?

Most people misuse sunscreens. As a result, the protective effect only reaches 40 percent of the protection that would be expected due to the sun protection factor. The current study found that protecting the skin from the harmful UV-induced DNA damage that causes cancer was only significant when the sunscreen was applied in a thickness between 1.3 and 2.0 milligrams per square centimeter. Most people only apply a layer of 0.75 milligrams, the scientists explain.

A higher sun protection factor can compensate for thin application

Most skin cancers are caused by DNA damage from UV radiation from sunlight. People can increase their sun protection by using sunscreen with a higher sun protection factor. If the cream is applied too thinly, this can be compensated for, the experts explain. Given that most people don't use sunscreens as manufacturers say, people should simply use a much higher sun protection factor than they think is necessary, study author Professor Antony Young of King's College London writes from the English-language newspaper "The Guardian" quotes.

As a rule, too little sunscreen is applied

The sun protection factors given are based on the assumption that sunscreen is applied in a thickness of two milligrams per square centimeter. This corresponds to the manufacturer's recommendation. But the average user usually uses a lot less sunscreen.

Sun protection factor 20 can quickly become sun protection factor four

For example, if people use sun protection factor 20 and apply the cream with a thickness of only 0.75 milligrams per square centimeter, their actual level of protection is around sun protection factor four, the study authors explain. In order to investigate the protective effect of the sun creams when used normally and inadequately, the researchers measured the amount of DNA damage in the skin of 16 volunteers.

How was the investigation carried out?

The study participants were divided into two groups of eight. One group received only a single dose of UV radiation to mimic normal sun exposure. The second group received multiple doses of UV radiation over a five-day period to mimic continuous vacation exposure. The scientists varied the amount of UV radiation during the experiment in order to reproduce the conditions in classic holiday destinations such as Tenerife.

The sunscreen used complied with EU regulations

Volunteers received their UV radiation dose within 15 minutes after applying their sunscreen and the skin biopsies were taken immediately after UV radiation, the doctors explain. The sunscreen used in the study complied with EU regulations.

Effective protection through correct application

The skin biopsies carried out showed that the participants from the holiday group, who applied the sunscreen in the higher thickness recommended by the manufacturer, had significant protection against damage even after a high UV dose over several days compared to test subjects who only had a thin one Had applied a layer of sunscreen. There is no denying that sunscreens provide important protection against the carcinogenic effects of the sun's UV rays, says Young. However, the study shows that the way the sunscreen is applied plays an important role in determining its effectiveness, the expert adds. (as)

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