Radiation is energy from any source travelling through space or some material. It can be in the form of light, heat or sound. It can also be in the form of radioactivity or emissions from unstable atoms giving off some excess energy or mass, or both, in an attempt to reach stability. Such emissions are Radiation and can be:
a) Electromagnetic Waves like Cosmic rays, X-rays, or Gamma rays which are similar to X-rays but have higher energy; or
b) Particulate like Alpha and Beta radiation.
Radiation is said to be Ionizing (radiation) when it produces Ions or charged particles in matter. It strips-off the electrons on the stable atoms it hits, turning them into ions or electrically charged particles. Ionizing radiation is therefore, radiation that ionizes atoms. It has great significance in health because when the atoms making-up the body become unstable electrically, they react differently chemically with great implications. All biochemical reactions in all living things are chemical (not nuclear) because it is the electrons that are reacting in them; not the neutrons in the nucleus of the atoms as in nuclear reactions.
Ionizing radiation can therefore, result in radiation burns, mutation or genetic changes, foetal malformation, still births, increase in cancer cases, especially thyroid cancer etc.
MAIN TYPES OF IONIZING RADIATION
a) Alpha particles are heavy short-range particles that are positively charged because each contains two protons like an ejected Helium nucleus. Since they are short-range, they can be shielded (stopped) by a sheet of paper or human skin but can be harmful when the radioactive source, like Uranium, is swallowed.
b) Beta particles are light in mass, short-range, negatively charged particles because they are ejected electrons like from Hydrogen-3 isotope (Tritium) undergoing what scientists refer to as Beta decay. They are moderately penetrating and cannot be stopped by a sheet of paper. Persons exposed to Beta particles need light protective gears like gloves, aprons etc.
c) X-rays and Gamma rays are waves and are most penetrating because they are not particles. Persons exposed to these need shields as thick as concrete walls or Lead walls.
Radioactivity, which is the spontaneous disintegration of an unstable atomic nucleus by the emission of subatomic particles or waves, can ionize another atom; but does not cause it to become radioactive. This is why it is said that irradiated food is safe and persons receiving Radiotherapy (therapy using ionizing radiation) do not pose radioactive danger to others. Irradiation is exposure to penetrating radiation.
The International Commission for Radiological Protection, ICRP, has specific doses not exceeding the so-called Threshold Limit that people can safely be exposed to. There are many types of protective products in use depending on the type of ionizing radiation. They include: Protective goggles, Lead sleeves, Gonadal shields, Lead blankets as well as Thyroid collars. Even with these, persons working in nuclear facilities are regularly monitored to ensure that they do not receive more than the permitted dose.
