Q. What are the main causes of Mutation?

Some mutations take place randomly and spontaneously during process of mitosis or meiosis. Others are caused by mutagenic agents that are environmental or man-made factors that can increase frequency of mutation. Environmental factors like ultraviolet rays of the sun can cause changes in DNA which can result in skin cancer. Cosmic rays from space that penetrate earth's ozone layer are also a cause of mutation. Ionizing radiation like X-rays, gamma rays and nuclear radiation produce free radicals (atoms with unpaired electrons) in the cell which can cause breaks in DNA molecule. Carcinogens are chemical mutagens which cause gene mutations which can lead to cancer. A few instances of carcinogens are asbestos, benzene, some food dyes and PCBs.