As the U.S. Food and Drug Administration (FDA) readies itself to introduce new rules on sunscreens, strong new evidence suggests overall sun exposure in childhood is most likely to develop into deadly skin cancer later in life. The news comes as the government is finishing long-awaited rules to improve sunscreens.

The FDA wants sunscreens' rating to be based not in on how well they block the ultraviolet-B rays that cause sunburn (today's SPF rankings) but for how well they protect against deeper-penetrating ultraviolet-A rays that are linked to cancer and wrinkles.

Experts have warned that children should be equally protected from the harmful rays of sun by the application of sunscreens and everyone must check the weather forecast for the day's "UV index" in town, to learn when to stay indoors or in the shade. UVA, which can even penetrate window glass, vary from state to state, even day to day, because of things like altitude, cloud cover and ozone.

AP quotes Dr. Nancy Thomas, a dermatologist at the University of North Carolina who led the UV research as saying, "Sunscreen is imperfect. Schedule activities when UV irradiation is not quite so high."

Experts have warned against melanoma, the most lethal skin cancer, which s expected to strike almost 60,000 Americans this year, and kill some 8,100. The cancer, which usually strikes people in the 40s or 50s, is now even showing its appearance in ever-younger cases, occasionally even in children.

A recent research has revealed that patients with the most common known melanoma mutations, called BRAF mutations, also had the highest UV exposure by age 20. Also, these people had the most moles, another important melanoma risk factor thus indicating that the young skin may be particularly vulnerable to damaging UV rays, especially as moles are developing.

Some experts also believe that early childhood sun exposure also leads moles to develop in the first place. Until recently, sunscreens have filtered out mostly UVB rays that cause sunburns, not UVA rays. Hence the people who apply depended only on sunscreen to prevent skin cancer were not benefited by the product.

However, many manufacturers have introduced sunscreens that offer "broad-spectrum" protection against UVA rays too but there are no such testing requirements available to prove that for UVA protection.

Experts recommend using products with the ingredient Helioplex, a more sun-stable mix of the sunscreen ingredients avobenzone and oxybenzone that seem to provide longer-lasting UVA protection, although they can be more expensive.