Quick burns, DNA mutations: Why children should not be exposed to the sun before age 3

It's summer, the weather's nice, and the temptation to spend the day outdoors during the holidays is great, whether at the beach, by the pool, or in the mountains. But for younger children, caution is advised. Because, just like with screens, experts agree on this recommendation: no sun exposure before the age of 3.

"Until the age of 3, children should not be exposed to the sun at all," dermatologist and venereologist Catherine Olivérès-Ghouti insists to BFMTV.com. "And after the age of 3 and until puberty, it's best to do so in moderation and, above all, with protection."

Because children are much more sensitive to the sun, which emits light, heat, and especially ultraviolet (UV) rays. While UVC rays—the most harmful—are completely filtered by the Earth's atmosphere and do not reach the surface, this is not the case for UVA and UVB rays, as the World Health Organization (WHO) points out.

The latter two are responsible for skin aging, can cause burns, and in the long term lead to skin cancers, melanomas—the most dangerous, with a high propensity to metastasize—and carcinomas. The WHO states that UV rays cause more than 80% of skin cancers worldwide.

"Sunburn in a child is much more serious than in an adult," Virginie Prod'homme, a researcher at Inserm and specialist in cancer risks, explained to BFMTV.com.

"Children burn more and more quickly."

To understand why children's skin is more sensitive to ultraviolet rays, a brief scientific explanation is in order. The skin is made up of keratinocytes—the cells of the dermis, the outermost layer. With UV rays, keratinocytes multiply, making the skin thicker and less permeable to radiation.

UV rays also stimulate the production of melanocytes—the skin cells responsible for pigmentation. Melanocytes secrete melanin, which is the basis of tanning, a barrier that absorbs and protects the skin from radiation.

But as Public Health France points out, tanning is not good for your health. "Tanning is a protective reaction of the skin against damage caused by ultraviolet rays (...). Tanned skin indicates that skin cells are damaged."

"However, children secrete very little melanin," warns Virginie Prod'homme. "They therefore have no filter, neither through thicker skin thanks to keratinocytes, nor through melanocytes."

It's also important to note that UV rays create stress for skin cells, which leads to DNA mutations. "All these mutations will accumulate over the course of a person's life," explains Virginie Prod'homme, a research fellow at the Mediterranean Center for Molecular Medicine at the Université Côte-d'Azur. "This can lead to skin cancer in adulthood."

"Accumulating DNA mutations at a very young age, from the first years of life, multiplies the risks."

The WHO also warns on the subject: "excessive exposure to the sun in children and adolescents contributes to the occurrence of skin cancer in adulthood."

Because the potential for sun resistance—which varies from one individual to another, particularly depending on skin tone—is acquired from birth. This is what we call sun capital, a capital that cannot be renewed. "From the moment an adult no longer tans, their sun capital has been reached," continues researcher Virginie Prod'homme.

"A child exposed to the sun from a young age begins to accumulate their sun capital."

In addition to sun exposure, UV intensity is also important to consider. In metropolitan France, solar radiation is strongest between May and August, particularly during the two hours before and after solar noon. This occurs around 2 p.m., when the sun's rays most directly hit the ground. However, in the early morning or late afternoon, these rays are more absorbed by the atmosphere.

Also be careful when staying in the mountains: the higher the altitude, the less atmosphere there is to absorb UV radiation. It is commonly accepted that for every 1,000 meters of elevation gain, UV intensity increases by 10%.

Furthermore, you should be wary of clouds. "An overcast sky doesn't provide protection," maintains Virginie Prod'homme. Because an overcast sky doesn't prevent UV rays from penetrating. Light or thin clouds can even increase the intensity of UV rays.

And imagining that children are protected in the shade, outdoors, is a mistake. On a day when UV intensity is high, even if you stay in the shade—for example, between two buildings—it is possible, especially for children with light skin, who are the most sensitive, to get sunburned.

Because many surfaces reflect UV rays. While grass, soil, or water reflect less than 10% of UV rays, sand reflects 15% and sea foam 25%. It's even worse with snow, which doubles UV exposure. The shade provided by a parasol therefore seems quite insufficient.

"During the hottest hours (from noon to 4 p.m., editor's note), it is essential to give children shade under a solid roof," urges Catherine Olivérès-Ghouti, also a member of the National Union of Dermatologists and Venereologists.

For this doctor, loose, covering clothing, a wide-brimmed hat to protect the neck and sunglasses are essential, especially for the little ones, and even if they are in the shade, with sunscreen on uncovered parts of the body.

Because for the eyes, the lens—transparent during childhood and adolescence—does not play its role as a natural barrier against UV rays, warns the website 1000 premiers jours. "For the eyes, serious damage can appear in the short term, such as ophthalmia (a 'sunburn' of the eye), or in the longer term, such as cataracts or retinal degeneration."

Health insurance therefore recommends glasses that carry the CE mark (a standard that requires UV 400 lenses that filter 100% of UV rays) and advises checking the protection categories (category 0 does not protect against solar UV rays, categories 1 and 2 are suitable for attenuated and medium sunlight, only categories 3 or 4 are suitable for strong sunlight at the seaside or in the mountains). Be careful, because well-treated transparent lenses can filter 100% of UV rays and dark lenses do not protect.

As for sunscreen, no less than SPF 50, containing protection against UVA and B rays, should be applied twenty minutes before sun exposure, reapply every two hours and after swimming, recommends Catherine Olivérès-Ghouti. The Ministry of Health insists that applying sunscreen does not prevent prolonged exposure to the sun.

But the dermatologist and venereologist points out that sunscreen alone remains "ineffective protection at midday in full sun." Its protection is calculated based on 2 mg of cream per cm2 of skin. "That's the equivalent of a golf ball for each application and one tube of cream per day. In practice, we're far from that."

"Sunscreen is no substitute for an anti-UV T-shirt," insists researcher Virginie Prod'homme.

The number of skin cancers more than tripled between 1990 and 2023, according to data from Public Health France. Each year, between 141,200 and 243,500 cases of these cancers are diagnosed. Some 1,975 people died from them in 2018.

"It's easy to protect yourself from it," Catherine Olivérès-Ghouti continues. "You just have to adopt the right habits from a young age and maintain them throughout your life."