Natural Sources of Radiation
First of all, every creature on earth encounters naturally occurring sources of radiation on a daily basis. The Earth and everything on it are constantly exposed to radiation from space, similar to a steady drizzle of rain. Charged particles from the sun and stars enter the earth’s atmosphere and interact with it and the earth’s natural magnetic field, producing typically beta and gamma radiation. This is referred to as “cosmic radiation”.
Another form of radiation occurring naturally is “terrestrial radiation” which can be found in soil, water and vegetation. These are usually variations of uranium and the decay products of uranium, such as thorium, radium, and radon, and are naturally occurring. In addition to these two forms of naturally occurring radiation, human beings have radiation inside their bodies. These forms include radioactive potassium-40, carbon-14, lead-210, and other isotopes.
Man-Made Sources of Radiation
Members of the public and individuals with certain occupations are exposed to man-made sources of radiation. The most common man-made sources affecting members of the public are tobacco, televisions, medical x-rays, smoke detectors, lantern mantles, fertilizer, nuclear medicine and building materials. Medical procedures make up the the most significant source of man-made radiation exposure such as diagnostic X-rays, nuclear medicine, and radiation therapy.
According to the Nuclear Regulatory Commission (NRC), individuals identified to experience occupational exposure to radiation work in the following environments:
· Fuel cycle;
· Industrial radiography;
· Radiology departments (medical);
· Radiation oncology departments;
· Nuclear power plants;
· Nuclear medicine departments; and
· National (government) and university research laboratories.
Physical and Psychological Effects
The effects of radiation exposure will vary, depending on the type, amount, and duration of exposure. Late or delayed effects of radiation occur following a wide range of doses and dose rates. Delayed effects may appear months to years after irradiation and include a wide variety of effects involving almost all tissues or organs. Some of the possible delayed consequences of radiation injury are life shortening, carcinogenesis, cataract formation, chronic radiodermatitis, decreased fertility, and genetic mutations (Jarrett, 1999).
Carcinogenesis, or the formation of cancerous cells, is statistically evidenced in persons with elevated radiation exposure. Radiation attacks the cells and disrupts DNA. Most cells tend to die and be sloughed off after being significantly damaged by radiation. It is also possible for the cell to remain alive, but have its DNA code significantly changed. These cells could become a fast growing mass of cancerous cells.
The psychological effect of a radiological release into a public area will be wide reaching. The facts about radiation are not well known amongst the public, and will add to the confusion and hysteria. The unrealistic fear of radioactive material and its properties are so prevalent in many civilian populations, the effects could easily overwhelm medical and emergency capabilities.
Jarrett, David G. Medical Management of Radiological Casualties: AFRRI Special Publication 99-2. (1999). (pp. 34-43). Bethesda, MD: Armed Forces Radiobiology Research Institute Information Services Division.