Background radiation is a measure of the level of ionizing radiation present in the environment at a particular location which is not due to deliberate introduction of radiation sources.
The sievert is a unit in the International System of Units (SI) intended to represent the stochastic health risk of ionizing radiation, which is defined as the probability of causing radiation-induced cancer and genetic damage. The sievert is important in dosimetry and radiation protection. It is named after Rolf Maximilian Sievert, a Swedish medical physicist renowned for work on radiation dose measurement and research into the biological effects of radiation.
Ionizing radiation, including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel up to 99% of the speed of light, and the electromagnetic waves are on the high-energy portion of the electromagnetic spectrum.
The roentgen equivalent man (rem) is a CGS unit of equivalent dose, effective dose, and committed dose, which are dose measures used to estimate potential health effects of low levels of ionizing radiation on the human body.
The linear no-threshold model (LNT) is a dose-response model used in radiation protection to estimate stochastic health effects such as radiation-induced cancer, genetic mutations and teratogenic effects on the human body due to exposure to ionizing radiation. The model statistically extrapolates effects of radiation from very high doses into very low doses, where no biological effects may be observed. The LNT model lies at a foundation of a postulate that all exposure to ionizing radiation is harmful, regardless of how low the dose is, and that the effect is cumulative over lifetime.
Radiation hormesis is the hypothesis that low doses of ionizing radiation are beneficial, stimulating the activation of repair mechanisms that protect against disease, that are not activated in absence of ionizing radiation. The reserve repair mechanisms are hypothesized to be sufficiently effective when stimulated as to not only cancel the detrimental effects of ionizing radiation but also inhibit disease not related to radiation exposure. This hypothesis has captured the attention of scientists and public alike in recent years.
Rolf Maximilian Sievert was a Swedish medical physicist whose major contribution was in the study of the biological effects of ionizing radiation.
The National Radiological Protection Board (NRPB) was a public authority in the UK created by the Radiological Protection Act 1970. Its statutory functions were to conduct research on radiological protection and provide advice and information on the subject to Government Departments and others. It was also authorized to provide technical services and charge for them. Originally NRPB dealt only with ionizing radiation, but its functions were extended in 1974 to non-ionizing radiation.
The 1986 Chernobyl disaster triggered the release of radioactive contamination into the atmosphere in the form of both particulate and gaseous radioisotopes. As of 2022, it was the world's largest known release of radioactivity into the environment.
Chernobyl liquidators were the civil and military personnel who were called upon to deal with the consequences of the 1986 Chernobyl nuclear disaster in the Soviet Union on the site of the event. The liquidators are widely credited with limiting both the immediate and long-term damage from the disaster.
The International Commission on Radiological Protection (ICRP) is an independent, international, non-governmental organization, with the mission to protect people, animals, and the environment from the harmful effects of ionising radiation. Its recommendations form the basis of radiological protection policy, regulations, guidelines and practice worldwide.
Radiobiology is a field of clinical and basic medical sciences that involves the study of the action of ionizing radiation on living things, especially health effects of radiation. 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. High doses can cause visually dramatic radiation burns, and/or rapid fatality through acute radiation syndrome. Controlled doses are used for medical imaging and radiotherapy.
The Chernobyl Forum is the name of a group of UN agencies, founded on 3–5 February 2003 at the IAEA Headquarters in Vienna, to scientifically assess the health effects and environmental consequences of the Chernobyl accident and to issue factual, authoritative reports on its environmental and health effects.
Between March and July 1962, a radiation incident in Mexico City occurred when a ten-year-old boy took home an industrial radiography source that was not contained in its proper shielding. Five individuals received significant overdoses of radiation from the 200-gigabecquerel cobalt-60 capsule, four of whom died.
Recognized effects of higher acute radiation doses are described in more detail in the article on radiation poisoning. Although the International System of Units (SI) defines the sievert (Sv) as the unit of radiation dose equivalent, chronic radiation levels and standards are still often given in units of millirems (mrem), where 1 mrem equals 1/1,000 of a rem and 1 rem equals 0.01 Sv. Light radiation sickness begins at about 50–100 rad.
To date, the nuclear accidents at the Chernobyl (1986) and Fukushima Daiichi (2011) nuclear power plants, are the only INES level 7 nuclear accidents.
Exposure to ionizing radiation is known to increase the future incidence of cancer, particularly leukemia. The mechanism by which this occurs is well understood, but quantitative models predicting the level of risk remain controversial. 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; if correct, natural background radiation is the most hazardous source of radiation to general public health, followed by medical imaging as a close second. Additionally, the vast majority of non-invasive cancers are non-melanoma skin cancers caused by ultraviolet radiation. Non-ionizing radio frequency radiation from mobile phones, electric power transmission, and other similar sources have been investigated as a possible carcinogen by the WHO's International Agency for Research on Cancer, but to date, no evidence of this has been observed.
The International Radiation Protection Association (IRPA) is an independent non-profit association of national and regional radiation protection societies, and its mission is to advance radiation protection throughout the world. It is the international professional association for radiation protection.
Angelina Konstantinovna Guskova was a Russian neurologist, neurosurgeon and radiation protection expert. She was associated with the Soviet atomic bomb project from 1949 and thereafter established radiation protection standards and medical management guidelines after nuclear accidents, also serving on the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR).
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