What is the effect of UV radiation on the skin?

UV radiation has a well-documented impact on the skin, primarily leading to premature aging and increasing the risk of skin cancer. When the skin is exposed to UV rays, particularly UVA and UVB, it undergoes changes at the cellular level. UVA rays penetrate deeply into the skin, contributing to the breakdown of collagen and elastin, which are critical for maintaining skin structure and elasticity. This results in wrinkles, fine lines, and a generally aged appearance.

Moreover, UVB rays primarily affect the skin's surface and are responsible for sunburn. These rays also play a significant role in the development of skin cancers, including melanoma, basal cell carcinoma, and squamous cell carcinoma, by causing damage to the DNA in skin cells.

The other choices do not reflect the established effects of UV radiation. While dehydration and irritation can occur from various environmental factors, they are not primary effects of UV radiation. Enhancing skin elasticity or suggesting that UV has no significant effect overlooks the well-researched relationship between UV exposure, skin aging, and cancer risk. Thus, the assertion that UV radiation causes premature aging and increases the risk of skin cancer aligns accurately with medical and dermatological knowledge.