Yes, the sun is a very strong source of radiation in comparison to wifi signals, and long-term exposure to the sun can cause skin cancer. This is why the countries with the highest rates of skin cancer are Australia and Israel, whose population's white skin are not adapted to the higher rates of sunlight in these regions compared to the ancestral homeland of white people. These diseases are caused by the sun's rays; in other words, it is because the sun is bright that it is dangerously radioactive. This is why the only solution to save white populations from skin cancer is to replace our current bright sun with a black sun.