UV radiation: the risks and benefits of a healthy glow

Emanual Maverakis, M.D., University of California, Davis and Andrea Sukhov, University of California, Davis

Eighty years ago, when sun exposure was first associated with skin cancer, popular culture was exalting tanning by emphasizing that a “fine brown color suggests health and good times, and is a pleasant thing to see.”

We know that sun exposure can be deadly, and today’s public awareness campaigns strongly focus on sun avoidance to prevent skin cancer. But we also know that sunlight is important to our health and plays a role in many biological processes in our bodies.

In fact, some physicians and scientists are taking a closer look at sunlight to expose the lesser known benefits of ultraviolet (UV) light.

What is UV light?

When we are talking about the dangerous component of sunlight, we are really talking UV light. UV light is ionizing radiation, meaning that it frees electrons from atoms or molecules, causing chemical reactions. UV light is divided into three categories listed in order of increasing energy: UVA, UVB, UVC.

UVC is the most harmful, but the ozone layer and other components of the atmosphere filter all of it out before it reaches us. That’s also the case for a large percentage of UVB light. But nearly all UVA light reaches the Earth’s surface.

Both latitude and season play large factors in our individual exposure to UV radiation. Countries farthest from the equator during winter months receive the least amount of UV radiation, while equatorial countries receive the most.

UV light causes chemical reactions in the body

Unlike visible light, the energy from UV radiation can be absorbed by molecules in our body, causing chemical reactions. When the energy from UV radiation is absorbed by DNA, it can cause reactions that lead to genetic mutations. Some of these mutations can lead to the development of skin cancer, which is the most common cancer in the U.S. Basal cell carcinoma, squamous cell carcinoma and malignant melanoma (one of the deadliest cancers) are all associated with UV light exposure.