However, the mechanism for the damage to tissue is usually more atomic in nature, even though the source of the radiation may be a nuclear process.
Radiation refers to energetic particles that deposit their energy, often harmful, into tissue.
To do significant damage, the particles must have energies in the keV or MeV range. When charged particles travel through tissue they damage tissue by stripping electrons from atoms and molecules, thus destroying their ability to function. Photons also interact principally with electrons, since electrons are much more easily removed from atoms than are nucleons. Neutrons always react first with a nucleus, but even with neutrons, most of the damage is caused by removing electrons from the protons released from the first nuclear interaction of the neutron. The surface of the earth is in a constant bath of cosmic rays which leave ionization trails through all living organisms.