UV Exposure: Effects

What are the effects of ultraviolet (UV) exposure?

Exposure to UV rays is linked to a number of harmful health conditions. Some of these are discussed below.

Skin Cancer
Consider the following statistic related to skin cancer:

• More than 1 million cases of non-melanoma skin cancer are diagnosed in the US each year.
• Melanoma represents only 4 percent of all skin cancers in the US, but accounts for more than 75 percent of all skin cancer deaths.
• Although exposure to the sun's ultraviolet (UV) rays is said to be the most important factor in the cause of skin cancers, about 70 percent of American adults do not use sun-protection measures.
• Most skin cancers appear after age 50, but skin damage from the sun begins at an early age. Therefore, protection should start in childhood to prevent skin cancer later in life.

Premature Aging (Photoaging)
Sun exposure also causes premature aging of the skin, a condition called photoaging, which is different than chronological aging.

• People who sunbathe regularly show photoaging early in life - often before 30 years of age. Chronologically-aged skin, more often, shows changes after age 40 or older.
• Freckling, fine wrinkling, and dilation of capillaries are often seen early in the photoaging process.
• Photoaged skin often develops irregular pigmentation (liver spots) in later years.
• Both photoaging and chronological aging cause wrinkling and loss of skin elasticity. However, these changes occur much earlier when skin has been overexposed to the sun.

Cataracts and Other Eye Disorders
Cataracts, an eye disorder characterized by a change in the structure of the crystalline lens that causes blurred vision, are a leading cause of blindness around the world - and excessive UV exposure is one of the risk factors in the development of cataracts. In fact, persons who spend more time in the sun may develop cataracts earlier than others. The American Academy of Ophthalmology now recommends wearing UV sunglasses and a wide brimmed hat to lessen exposure to ultraviolet rays. Corneal sunburn, growths on the outer surface of the eye, retinal-tissue damage, and other eye diseases are also known, or suspected, to be related to long-term exposure to UV rays.

Immune system damage
The skin is part of the body's natural defense system. Many healthcare professionals believe that UV radiation can alter immune system functions. When UV radiation suppresses immune responses, the body's ability to fight certain diseases, including skin cancer, is reduced. It is suspected that overexposure to UV radiation also interferes with the effectiveness of immunizations given through the skin.

Sunscreens Can Help

Studies have shown that sunscreens can prevent UV-induced wrinkling. Animal studies demonstrated that sunscreens with adequate UVA coverage can prevent sagging and wrinkling due to high-intensity UVA.