These are unsightly but they are not usually considered dangerous. The eyes are also affected by radiation from the sun. Minor damage will show up in the formation of a pterygium , which can be removed. Far more serious are cataracts , which can cause blindness. Reactions to sunlight differ People vary in how much ultraviolet exposure their bodies can tolerate before their skin is damaged or cancer occurs.
Melanin absorbs ultraviolet radiation, like a sunblock.
The cells beneath the melanin are therefore somewhat protected. Exposure to sunlight causes the skin to produce more melanin in an attempt to protect itself. In pale-skinned races, this shows up as a tan. Dark-skinned people will also produce more melanin after time spent in sunlight. In pale-skinned people, the maximum amount of melanin that the skin can make isn t enough to protect against the doses of ultraviolet radiation that occur in and around the tropics.