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Radioactive contamination can be due to a variety of causes. It may occur due to the release of radioactive gases, liquids or particles. For example, if a radionuclide used in nuclear medicine is spilled (accidentally or, as in the case of the Goiânia accident, through ignorance), the material could be spread by people as they walk around.
The most widely accepted model posits that the incidence of cancers due to ionizing radiation increases linearly with effective radiation dose at a rate of 5.5% per sievert; [1] if correct, natural background radiation is the most hazardous source of radiation to general public health, followed by medical imaging as a close second.
Ionizing radiation is generally harmful and potentially lethal to living things but can have health benefits in radiation therapy for the treatment of cancer and thyrotoxicosis. Its most common impact is the induction of cancer with a latent period of years or decades after exposure.
Radiation is often categorized as either ionizing or non-ionizing depending on the energy of the radiated particles. Ionizing radiation carries more than 10 electron volts (eV), which is enough to ionize atoms and molecules and break chemical bonds. This is an important distinction due to the large difference in harmfulness to living organisms.
The WHO stresses that the percentages stated in that section of their report are relative risk increases of developing these cancers, not absolute risk increases, since the lifetime absolute baseline risk of developing thyroid cancer in females is 0.75% and the radiation-induced cancer risk is now predicted to increase that 0.75% to 1.25%, with ...
Background radiation is from naturally radioactive materials and cosmic radiation from space. [5] The embryo and fetus are considered highly sensitive to radiation exposure. [8] Complications from radiation exposure include malformation of internal organs, reduction of IQ, and cancer formation. [8]
Exposure to radioactive waste may cause health impacts due to ionizing radiation exposure. In humans, a dose of 1 sievert carries a 5.5% risk of developing cancer, [7] and regulatory agencies assume the risk is linearly proportional to dose even for low doses. Ionizing radiation can cause deletions in chromosomes. [8]
The most widely accepted model posits that the incidence of cancers due to ionizing radiation increases linearly with effective radiation dose at a rate of 5.5% per sievert. [3] If this linear model is correct, then natural background radiation is the most hazardous source of radiation to general public health, followed by medical imaging as a ...