Does the sun cause cancer? That is the question. Unfortunately, there is no clear answer.
The medical profession and the media have done a good job of convincing the public to stay out of the sun to prevent cancer. Is there any evidence for this claim though? Surprisingly, evidence is lacking. Furthermore, there is evidence to the contrary.
Considering a large number of people that are exposed to the sun on a daily basis for an extended period of time we would expect to see a pandemic of skin cancer. This obviously is not happening. Athletes and construction workers would be good examples. Yet, there has not been an abnormally high level of cancer occurrence in these groups. An increase of cancer has been reported in migrant farm workers primarily on the back of the neck. Although, this increased of cancer has not been attributed to the sun but rather skin exposure to herbicides and pesticides.
Sun exposure actually has beneficial effects on the immune system, such as activation of macrophages. In addition, sunlight reacts with cholesterol in the skin to form vitamin D, which has been shown to have strong antitumor affects. The production of active vitamin D decreases with age though. This could help partially explain the increased risk of cancer with age.
Ironically, sunscreens being used in an attempt to protect the skin that may be increasing the risk of cancer. Sunscreens often contain chemicals that are known carcinogens.