Skin is the body’s largest organ. It is also one of the most important parts of the body because it interfaces with the environment and is the first line of defense from external factors. Since the skin is exposed to environmental pollutions more than any other organ during life, skin protection is important.
The most important burden on skin is the sunlight (UV radiation), which causes a wide array of visible alterations such as wrinkles and discoloring. The most hazardous consequence of sunlight exposure is the development of skin cancer. Many common misconceptions exists about UV radiation, sunscreen, and skin.
What Is Ultraviolet Radiation?1
You hear about it constantly. Doctors, news reporters, advertisers, and others are constantly proclaiming that ultraviolet radiation is bad for you. But, rarely do any of them explain what UV radiation really is. There are actually two types of UV radiation that humans should be concerned about, UV-A and UV-B.
The Differences Between UV-A and UV-B
UV-A
- Wavelenths from 320-400 nm
- Penetrates more deeply into skin and may have greater destructive potential and greater potential to cause cancer
- The main cause of photoaging of the skin (wrinkles, drooping, visible blood vessels, leathery appearance)
UV-B
- Wavelenths from 290-320 nm
- The main cause of sunburn in humans
- Still possesses potential to cause cancer, especially squamous cell carcinoma
Most importantly, both types of ultraviolet radiation are extremely dangerous and damaging to the skin. They work together to cause all three major types of skin cancer (melanoma, squamous cell carcinoma, and basal cell carcinoma) as well as other damaging effects to the skin and the rest of the body (sunburn, photoaging, immune suppression). Therefore, it is important to wear sunscreen that properly protects against both types of UV radiation (See Sunscreens and Sunscreen Recommendations for Men).
Why Is UV Radiation Dangerous?1
Simply put, UV radiation is dangerous because it raises your risk of having skin cancer and of sun-related damage to the skin and the rest of the body. Contrary to popular belief, it is dangerous regardless of whether sunburn occurs.
Both types of UV radiation also contribute to all three major types of skin cancer, melanoma, squamous cell carcinoma, and basal cell carcinoma. In fact, UV-A and UV-B work synergistically to further damage the skin and increase the risk of cancer. Intensive UV exposure over short periods is a risk factor for basal cell carcinoma and malignant melanoma, especially if a blistering sunburn occurs. Chronic UV exposure increases the risk of squamous cell carcinoma.
Additionally, UV radiation causes photoaging of the skin. Photoaging is basically breakdown of the skin’s normal tone and turgor. This breakdown of the skin becomes visible as wrinkles, age spots, blood vessels, drooping, and leathery appearance.
UV radiation also suppresses the immune system. This immune suppression actually further increases the risk of getting skin cancer while also increasing the risk of acquiring various infections.
Ultraviolet Radiation Misconceptions
- Tanning protects the skin from ultraviolet radiation (Wrong! Tanning offers no additional protections form UV-induced cancer, photoaging, and immunosuppresion.)
- Clouds block ultraviolet radiation (Wrong! No one is quite sure what clouds do to UV radiation. However, they definitely do not block it. In fact, for one or more reasons, people are more likely to incur sunburn and other UV damage on cloudy days.)
- Indoor tanning is not as dangerous as outdoor tanning (Wrong! In fact, the opposite is often true. Indoor tanning does not cause sunburn and thus allows users to receive even higher doses of UV radiation than they could normally take from the sun.)
- Higher SPF sunscreens last longer (Wrong! Sunscreen should be reapplied every 2 hours regardless of SPF.)
References1. Jou PC, Feldman RJ, Tomecki KJ. UV protection and sunscreens: what to tell patients. Cleve Clin J Med. Jun 2012; 79 (6): 427-436.