UV Radiation and Skin Cancer

Written By: SERO Board-Certified Physicians

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By Hillebrand Steve, U.S. Fish and Wildlife Service via Wikimedia Commons

Exposure to ultraviolet (UV) radiation is a leading cause of skin cancer. For the majority of people, exposure to UV radiation comes mainly from sunlight. With the classification of UV radiation as a human carcinogen by the World Health Organization, it is important to understand how exposure to UV radiation increases skin cancer risk and what you can do to minimize that risk.

What is UV Radiation?

Sunlight generates UV radiation in the form of UVA, UVB, and UVC rays. UVC rays have the shortest range and are completely absorbed by the earth’s ozone layer. UVB rays have a moderate range and a good deal of this radiation is absorbed by the ozone layer. Conversely, UVA rays have the longest range; none of these rays are absorbed by the ozone layer. The majority of skin cancer risk comes from exposure to the UVA and UVB rays that make it through the ozone layer to the earth’s surface. The use of tanning beds, which provides direct exposure to UV radiation, also increase skin cancer risk.

Effects of UV Exposure

UVA and UVB rays affect the skin in different ways. UVA radiation penetrates more deeply into the skin than UVB radiation and is responsible for the skin changes attributed to premature aging, such as wrinkles. Recent research indicates that UVA radiation plays more of a role in the development of skin cancer than previously thought.

UVB radiation affects the upper layers of skin and is primarily responsible for changes to the surface of the skin, such as the reddening and darkening of the skin associated with sunburns and suntans. UVB radiation also stimulates vitamin D production in the body, but prolonged exposure provides more damage than reward.

Both types of UV rays damage the DNA of skin cells. This damage can lead to the skin cell mutations that cause skin cancer. In addition to skin cancer, UV radiation exposure can also cause premature aging, immune suppression, and irreversible eye damage.

Reducing UV Exposure

You cannot completely avoid UV rays, but you can significantly reduce your exposure. Sunscreen is one of the most useful tools in combating UV radiation. Select a broad-spectrum sunscreen with an SPF of 15 or higher that protects against UVA and UVB radiation. Apply sunscreen 20 to 30 minutes before sun exposure and reapply your sunscreen every two hours or immediately after getting wet or sweating excessively. Wear a hat and sunglasses to protect your scalp, ears, and eyes. UVA rays can penetrate glass and clouds, so it is still important to wear sunscreen indoors and on cloudy days. If possible, avoid prolonged time outdoors during peak hours of sunlight, particularly in the summer.