Gamma rays have the most penetrating powers of all three radiation sources. Particles called neutrinos have no electrical charge or measurable mass. Neutrinos are the most penetrating type of radiation. Its penetrating powers are so great that “a neutrino has to go through many 'light years of matter to have a 50-50 chance of interacting with the nucleus of an atom, according to “The New Quantum Universe” by Tony Hey and Patrick Walters.
They can easily pass through the earth. Gamma rays pose a radiation hazard to the entire body. They can easily penetrate barriers that can stop alpha and beta particles, such as skin and clothing. Gamma rays have such penetrating power that it may take several inches of dense material such as lead, or even a few feet of concrete to stop them.
Gamma rays can completely pass through the human body; as they pass through it, they can cause ionizations that damage tissues and DNA. In general, alpha particles have a very limited ability to penetrate other materials. In other words, these particles of ionizing radiation can be blocked with a sheet of paper, skin, or even a few centimeters of air. However, materials that emit alpha particles are potentially hazardous if inhaled or swallowed, but external exposure generally does not pose a hazard.
The EPA's mission in radiation protection is to protect human health and the environment from ionizing radiation that comes from the human use of radioactive elements. In contrast, ionizing radiation (such as x-rays and cosmic rays) is more energetic than non-ionizing radiation. The ionizing radiation that is emitted may include alpha particles alpha particles A form of particulate ionizing radiation composed of two neutrons and two protons. This form of radiation known as electromagnetic radiation is like the vibrating or pulsating rays or waves of electrical and magnetic energy.
The other form of radiation known as particle radiation are tiny, fast-moving particles that have energy and mass (weight).