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Over-exposure to certain types of electromagnetic radiation can be harmful.

The higher the frequency of the radiation, the more energy it carries and the more damage it is likely to cause to the body:

• radio waves: one of the few known effects of radio waves on the human body is a very small rise in temperature of up to 0.2 ^oC. Some people claim the very low frequency radio waves from overhead power cables and mobile phone base stations near their homes has affected their health, although this has not been reliably proven;
• microwaves can cause internal heating of body tissues;
• infrared radiation is felt as heat and causes skin to burn;
• visible light from a laser which is very intense can damage the retina at the back of the eye;
• ultraviolet can damage skin cells and lead to skin cancer and damage the eyes, it can cause skin to age prematurely;
• X-rays damage cells inside the body. They can damage the genetic material of a cell, the DNA. This can lead to cancer. This is why doctors and dentists stand behind protective screens when taking lots of X-rays;
• gamma rays also damage the genetic material of a cell, the DNA. This can lead to cell death and cancer.