NEW YORK--Sunscreens represent the first line of defense against skin damage from the sun, and broad-spectrum products offer the best protection, Madhukar A. Pathak, MB, PhD, said at a media conference sponsored by the Skin Cancer Foundation.
Commonly available products are very effective at preventing the acute effects of ultraviolet B (UVB) radiation, but many products offer no protection against UVA light, said Dr. Pathak, senior associate in dermatology, Harvard Medical School, and chairman of the Foundation's Photobiology Committee.
UVB radiation (wavelengths from 290 nm to 320 nm) causes sunburn, tanning, photoaging, and skin cancer induction, while UVA radiation (wavelengths of 320 nm to 400 nm) is associated with the immediate tanning reaction, photoaging, and tumor promotion.
The currently available products (SPF 15 or less) do an excellent job of preventing sunburn when used properly, but they are unsatisfactory in preventing tanning, he said. In addition, although sunscreens provide good protection from the DNA damage caused by low doses of UVB, it is not yet known how effective they are in preventing DNA damage at high exposure dose levels.
Current sunscreens do only a fair to good job against the chronic effects of high-dose UVA and UVB radiation, he said. They will ameliorate but not necessarily prevent photoaging, sun-related immunosuppression, and non-melanoma skin cancer.
Possible new sunscreen strategies that might provide better protection include the use of antioxidants, free radical quenchers, melanin, and sunscreen-enriched liposomes, he noted, but these are all in the future.
Dr. Pathak said that the "bottom line" for sunscreen strength is SPF 15. Any sunscreen with a lower SPF does not provide sufficient protection. However, he recommends the use of products with an SPF of 30, because they also provide partial, if not total, protection from UVA radiation.