Researchers have found that improper usage of sunscreen creams can do more damage than good. The researchers at the University of California, Riverside, have reported that it is the first time that the filters in sunscreen have been found to act in this manner.
According to Dr Kerry Hanson, a senior research scientist in the university's department of chemistry, the problem arises when sunscreen gets beneath the surface of the epidermis that is the outermost layer of skin.
Dr Hanson said, "Sunscreens do an excellent job protecting against sunburn when used correctly. This means using a sunscreen with a high sun protection factor and applying it uniformly on the skin. Our data show, however, that if coverage at the skin surface is low, the UV filters in sunscreens that have penetrated into the epidermis can potentially do more harm than good".
"Reactive Oxygen Species" (ROS) are the harmful compounds produced when the when UV radiation is absorbed by the skin exposed to sunlight. ROS are highly reactive molecules that can cause "oxidative damage".
Skin cancer and increasing the visible signs of aging can be caused by the reaction between ROS and cellular components like cell walls, lipid membranes, mitochondria and DNA. UV filters usually prevent this process. However, when they penetrate into the skin, the top skin layer is exposed to damage again.
According to the researchers, the 3 commonly used UV filters found to act in this manner are octylmethoxycinnamate, benzophenone 3 and octocrylene.
Dr. Hanson said, "More advanced sunscreens that ensure that the UV filters stay on the skin surface are needed."
Professor John Hawk, dermatologist for the British Skin Foundation, said "It seems possible that penetration of sunscreen filters into the skin might slightly increase sunlight induced damage, if no further sunscreen is applied and the skin is exposed to UV light. But we already warn against not re-applying sunscreen regularly, since ordinary sun damage would be occurring".
"High factor sunscreens can be considered safe and effective if re-applied frequently. If not reapplied, there might be a slight increase in the damage outlined in the study but it is not likely to be significant".