In particular, radioactive chemicals are often used in medicine as body tracers and to attack cancers. Types of Radiation Radiation consists of alpha, beta and gamma particles. Alpha radiation is simply helium nuclei, that is, each particle consists of two protons and two neutrons. Because of its mass, alpha radiation will not penetrate healthy skin or even a piece of paper. However, if alpha radiation enters the mouth or nose, it may cause cancers in lungs or other organs.
Beta radiation consists of electrons.
They have negative charges. Because they are energetic and have no rest mass, they are more of a potential health threat than alpha radiation. Beta radiation may penetrate 1-2 cm of human flesh, but may be stopped by a few millimeters of aluminum. Like light, gamma radiation consists of photons. Gamma rays are extremely energetic and potentially dangerous.