How can excessive sun exposure lead to skin cancer?

Excessive sun exposure is primarily harmful because it causes DNA damage in the skin cells. Ultraviolet (UV) radiation from the sun is a significant factor in this process. When skin cells are exposed to UV radiation, the energy from the UV light can directly damage the DNA within those cells. This damage can lead to mutations, which are alterations in the DNA sequence. If these mutations occur in genes that control cell growth, division, and repair mechanisms, they can disrupt normal cellular function. Over time, this can lead to uncontrolled cell proliferation, which is a hallmark of cancer.

The ability of the skin cells to repair themselves can also be overwhelmed by excessive and repeated UV exposure. If the repair mechanisms fail or the DNA damage is too severe, the risk of developing skin cancer increases significantly. This underlines the significance of protective measures such as sunscreen and clothing to limit UV exposure.

The other options address different aspects of skin physiology but do not directly relate to the development of skin cancer due to sun exposure. For instance, while excessive sweating and increased collagen breakdown are effects of UV exposure, they do not contribute directly to cancer development. Similarly, while UV rays can enhance melanin production as a defense mechanism against UV damage, this response does not negate