Gamma radiation results from radioactive atoms. When the ratio of neutrons to protons in the nucleus is not compatible, and the binding energy is not enough to keep the nucleus intact inside the atom, the atom becomes unstable. Atoms with this type of nuclei change. Their nuclei undergoes decay, and loses energy as packets called photons. These fast and intra atomic particles that are released during radioactive decay of the radioactive nuclei, which can ionize the atoms with which they interact, are called gamma rays.
Gamma rays have a high penetrating capacity. These rays have a lot of energy to destroy atoms in your body and transform them into radioactive ions. Gamma rays possess the top most frequencies of all the electromagnetic radiations. Hence, it has the shortest wavelength and highest energy. As they are highly energetic, they can cause severe problems in humans and other animals if they pass into their bodies.
Gamma rays are dangerous because they have a high energy to break bonds. Even in low doses they can alter the DNA in the cell and result in changed metabolic functions of the cell. They can even cause cancer. Gamma rays can destroy cells and cause the immediate death of a person if given in high doses. Microwaves and infrared waves are also dangerous if they reach you in high intensity. Radio waves are also harmful if they fall on you for a long time.
Gamma rays are so energetic that they are not stopped by the human skin. Hence, they pass into our body and can damage the cells and tissues. Low energy gamma rays have to be stopped by a very thick layer of strong material. Its high energy rays cannot be easily stopped.
Gamma rays are released from nuclear reactors and from celestial space. Earth’s atmosphere is so dense that it prevents most of the gamma radiation from reaching the earth’s surface.