ost of the chemicals contained in sunscreens have minimal toxicological effects when first applied to the skin. However, when exposed to sunlight, the chemicals are heated and reactions occur between the sunscreen's active and inactive ingredients and the epidermis. Most of the risks associated with sunscreens lie in the method used to stop the UV radiation harming our skins. Sunscreens use organic compounds to either reflect or absorb different parts of the UV spectrum. When the absorption method is used to protect us from UV radiation, the particles absorbing the UV are energised, or elevated to a higher energy level. This energy is re-emitted when the particles drop back to their former, lower energy level. The released energy enters the epidermis. It is this process that causes the skin damage.
Many of the chemicals in sunscreens have been found to cause phototoxic, photoallergic or photogenotoxic (DNA altering) effects. PABA (Paramino benzoic acid) has been found to increase the development of a particular DNA defect in human cells. When this occurs in people who lack the mechanism to repair the defect, they are more susceptible to skin cancer. When exposed to sunlight, PABA also readily generates oxygen radicals which harm DNA strands . An ester of PABA, amyl paradimethylarninobenzoate (Padimate A) was found to cause phototoxic reactions. Padimate A reacts with UVA to produce symptoms widely resembling sunburn. The similarity between sunburn and a phototoxic response has led people to mistakenly believe that the sunscreen causes sunburn. An ingredient commonly used in sunscreens, 2-phenylbenzimidazole-5-sulfonic acid (PBSA), strongly absorbs UVB radiation, thus becoming energised and capable of affecting adjacent skin tissue by damaging the guanine base sites of the cell's genetic material. This may increase the risk of developing skin cancer....read more>>>...