Ionizing Radiation
Ionizing radiation comes from matter, which is composed of atoms. Some atoms are unstable. As unstable atoms change and become more stable, they give off invisible energy waves or particles called radiation. This radiation is called ionizing radiation.
Ionizing radiation is energy in the form of waves or particles with enough force to remove electrons from atoms. One source of ionizing radiation is the nuclei of unstable atoms. In the process of the radioactive atoms (also referred to as radionuclides or radioisotopes) seeking to become more stable, their nuclei eject or emit particles and high-energy waves. Radioactive decay is what this process is known as.
Current evidence suggests that exposure to ionizing radiation does pose some risk, however, that has not been definitively demonstrated at very low exposure levels. While experts disagree over the definition of “low dose,” ionizing radiation protection measures are based on an assumption that even small amounts of ionizing radiation exposure may pose some small risk. If one factors in the entire dose of natural background radiation accumulated over a lifetime, the risk of developing cancer as a result of this exposure is estimated to be roughly 1 in 100. Additional contribution from all man-made sources of ionizing radiation is much smaller. All of the long-term health effects associated with exposure to radiation may also occur in humans due to other causes.
Survivors of the atomic bomb explosions in Japan, provide the most complete data available to scientists on radiation industry workers and on people receiving large doses of medical radiation. This data demonstrates a higher incidence of cancer with exposed individuals as well as a greater probability of cancer as the level of exposure increases. Because more direct information is not available, the data also are used to estimate what the effects might be at lower exposures. Scientists attempt to come to conclusions based on information obtained from laboratory experiments, however, these determinations are considered to be uncertain. In the case of radon, scientists largely depend on data collected on underground miners. Those professionals in the radiation protection field wisely assume that the chance of a deadly cancer from radiation exposure increases in direct proportion to the amount of the exposure. It is assumed that no radiation exposure is completely risk free.
Chronic exposure is considered continuous or intermittent exposure to low doses of radiation over a long period of time. Regarding chronic exposure, there is a delay between the exposure and the observed health effect. Among these observed effects are cancer and other health outcomes, including benign tumors, cataracts, and potentially harmful genetic effects.
Acute exposure is considered to be exposure to a large, single dose of radiation, or a series of moderate doses received in a short period of time. These large doses can result from accidental or emergency exposures as well as from specific medical procedures like radiation therapy. For approved medical exposures, the benefit of the procedure may outweigh the risk from exposure.