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Like every summer, it's difficult to choose from the jungle of clues and brands. Is it better to focus on mineral or chemical filters? What index to favor? Le Figaro takes stock
Cream, milk, spray … Of all sunscreen products, cream is by far the most effective because of its more homogeneous application and the applied layer is thicker and therefore more protective. But difficult to make your choice in the jungle of clues and brands that appear on the stalls of supermarkets and pharmacies. Is it better to prefer creams with a chemical filter or a mineral filter? Is a 15+ index sufficient? The Figaro takes stock.
The purpose of solar products is to protect the skin from ultraviolet A and B (UVA and UVB). These rays pbad through the ozone layer and are particularly strong between noon and 4 pm UVB is responsible for sunburn, and UVA is the premature aging of the skin. Both play a role in the development of skin cancers: carcinomas and melanomas. "If we use sun products properly, we protect ourselves from sunburn, skin aging and skin cancer as well," explains Professor Jean-Luc Schmutz, head of the dermatology department at Nancy University Hospital Center. President of the French Society of Photodermatology
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The sun creams filter the ultraviolet
There are two kinds of sunscreens. First, chemical filters that absorb ultraviolet. The same sunscreen contains several, because some only protect against UVB and others against UVA. Problem: These substances enter the skin and some are suspected to be endocrine disruptors. This is the case of oxybenzone and octinoxate, soon banned in Hawaii, because these two molecules cause "the feminization of male fish and increase reproductive problems" of marine life, says the text of the 50th state United States.
Then mineral filters, zinc oxide and titanium dioxide, which reflect UV. "They are the ones we find in organic products, or for children, because they do not get into the skin," says Martine Bagot, head of the dermatology department at Hôpital Saint-Louis. More recent than chemical filters, they were previously less appreciated because they are more difficult to spread.
To give these creams a smoother and clearer appearance, laboratories now use processes that "reduce the size of particles to nanoparticles," says Bagot. In return, these nanoparticles could enter the body. "We have no evidence of its systemic pbadage in humans," says Pr Schmutz. "In any case, the benefit outweighs the potential risks. What is needed is finding the most suitable solution, with the least possible risk. For himself and for the environment, "he continues.
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In practice, the index 50 corresponds to an index 15
The index indicated on your sunscreen, the SPF (sun protection factor), is that corresponding to the protection against UVB – responsible for sunburn. It corresponds to the difference in the time it takes for a sunburn to appear between a skin protected by the product and unprotected skin. For example, a cream of index 15 multiplies by 15 the time necessary for UV to damage our skin without protection. Thus, instead of catching a sunburn in 10 minutes, it will take 2:30. There are eight indices: 6 and 10 (low protection); 15, 20 or 25 (medium protection); 30 or 50 (high protection); 50+ (very high protection). The lighter your skin is, the more you have to choose a high protection factor.
Not to mention that "in reality, a 50 index does not correspond to a 50 index calculated in the laboratory," explains the dermatologist. Indeed, "studies are done on 2 grams of cream per square centimeter of skin". A quantity of cream that we are far from applying once on the beach. "That's about 6 teaspoons if you apply it from head to toe," says Pr Schmutz. About one tube of cream a day, if you renew the application every two hours, as recommended by doctors. But "we put about 4 times less," as Martine Bagot points out. In practice, the index 50 is thus transformed into index 15.
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And the children?
The best protection against the devastating rays of the sun nevertheless remain the clothes, hat and sunglbades. "The sunscreens come in addition," insists Jean-Luc Schmutz. Because a sunscreen, even with a high index, does not filter all UV. In addition, special attention must be paid to children, "that we must not leave in the sun," warns Pr Bagot, because "their skin is not pigmented enough". Attention also to the creams stamped "kids" and "family". "A lot of marketing comes into play in the labeling," warns Jean-Luc Schmutz. Prefer organic creams, "which contain well-supported, non-toxic products," Pr Schmutz says, and mineral filters, zinc oxide and titanium dioxide – whether labeled "children" or not.
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