DEFINITION
Sunscreen is a lotion, spray, gel or other topical
product that absorbs or reflects some of the sun's ultraviolet
radiation on the skin exposed to sunlight and thus helps protect against sunburn.
HISTORY
The first effective sunscreen may have been
developed by chemist Franz Greiter in 1946. The product, called (Glacier
Cream), subsequently became the basis for the company Piz Buin, which is still
today a marketer of sunscreen productsIt has been estimated that (Glacier
Cream), had a sun protection factor of 2.
The first widely used sunscreen was produced by
Benjamin Green, an airman and later a pharmacist, in 1944.
This product was developed during the height of
World War II, when it was likely that the hazards of sun overexposure were
becoming apparent to soldiers in the Pacific and to their families at home.
Sales of this product boomed when Coppertone acquired the patent and marketed
the substance.
Franz Greiter is credited with introducing the
concept of sun protection factor in 1962, which has become a worldwide standard
for measuring the effectiveness of sunscreen
Newer sunscreens have been developed with the
ability to better withstand contact with water, heat and sweat.
BENEFITS
Sunscreen use
prevents melanoma and squamous cell carcinoma, two types of skin cancer
There is little evidence that it is effective in preventing basal cell carcinoma
A 2013 study concluded that the diligent, everyday
application of sunscreen can slow or temporarily prevent the development of
wrinkles and sagging skin. The study involved 900 white
people in Australia and required some of them to apply a broad-spectrum
sunscreen every day for four and a half years. It found that people who did so
had noticeably more resilient and smoother skin than those assigned to continue
their usual practices.
COMPOSITION
Sunscreens contain one or more of the following ingredients:
- • Organic chemical compounds that absorb ultraviolet light.
- • Inorganic particulates that reflect, scatter, and absorb UV light (such as titanium dioxide, zinc oxide, or a combination of both).
- • Active ingredients: The principal ingredients in sunscreens are usually aromatic molecules conjugated with carbonyl groups. This general structure allows the molecule to absorb high-energy ultraviolet rays and release the energy as lower-energy rays, thereby preventing the skin-damaging ultraviolet rays from reaching the skin.
DOSAGE
More recent research at the University of
California, Riverside, indicates that sunscreen must be reapplied within two
hours in order to remain effective. Not reapplying could even cause more cell
damage than not using sunscreen at all, due to the release of extra free
radicals from those sunscreen chemicals that were absorbed into the skin.
