Free radicals are basically atoms with highly reactive electrons, which can lead to strange bonds in cells. It's these bonds, which create oxidation and can lead to cancer-or specifically-skin cancer. Some radicals, like diradical O2, represent the normal metabolism in cells, where controlled reduction of reactive oxygen occurs. In other words, not all free radicals cause damage.
Some research suggests that while UV irradiation over a prolonged period can cause free radical damage to skin cells, it is not the most prevalent of topological causes. Afterall, skin requires sunlight in order for needed chemical reactions to take place. There is even evidence that regular sunlight can help to prevent depression. Naturally, too much sunlight leads to sunburn, which is obviously deleterious, and extensive sunburn over a prolonged period provides a higher risk of skin cancer.
So what's the solution? Sunscreen? Maybe not...
First of all, sunscreen can clog your pores and lead to irritation or acne. Second of all, sunscreens utilize a metal-based reflector to keep the sun rays from being absorbed into the skin; this along with a whole slew of other chemicals, which my cause irritation especially if used daily and not properly removed.
According to (insert site and link) Titanium DiOxide has been noted (US Federal Register, 43FR38206, 25 August 1978) to be a safe physical sunscreen because it reflects and scatters UVB and UVA in sunlight. However, this metal compound absorbs about 70% of incident UV, and with moisture this leads to the generation of a special kind of free radicals, which can initiate oxidations. Furthermore, this particular study showed that sunlight-illuminated titanium dioxide assists in the production of DNA damage in skin cells. These results may be relevant to the overall effects of sunscreens.
This study by Dunford, Salinaro, Cai, Serpone, Horikoshi, Hidaka, and Knowland (available here) continues by reporting that titanium dioxide in sunscreens is formulated as "micronised" or "ultrafine" particles. These are so-called "microreflectors" because they scatter light according to Rayleigh's law, whereby the intensity of scattered light is inversely proportional to the fourth power of the wavelength. Consequently, they scatter UVB and UVA more than the longer, visible wavelengths, preventing sunburn while remaining invisible on the skin. However, titanium dioxide also absorbs UV light efficiently, assisting in the formation of free radicals, which can initiate oxidations.
This article is no way implying that people should not protect themselves from the sun, neither does it imply that the sun should be avoided. Instead, limit your exposure. If you can, wear loose fitting garments with long sleeves. Perhaps, the most important way to protect against free radical is by altering your diet.
Health always starts from the inside out. Try adding garlic, ginger, artichokes, cranberries, apples and plums, to your favorite meals, but be careful what you choose because you may not want to ingest too much Iron either. Check with your physician before altering your diet.