According to the prevalent model, any<unk>  exposure can increase the risk of cancer. Typical contributors to such risk include natural background<unk> , medical procedures, occupational exposures, nuclear accidents, and many others. Some major contributors are discussed below. Radon Radon is responsible for the worldwide majority of the mean public exposure to ionizing<unk> . It is often the single largest contributor to an individual's background<unk>  dose, and is the most variable from location to location. Radon gas from natural sources can accumulate in buildings, especially in confined areas such as attics, and basements. It can also be found in some spring waters and hot springs. Epidemiological evidence shows a clear link between lung cancer and high concentrations of radon, with 21,000 radon-induced U.S. lung cancer deaths per year—second only to cigarette smoking—according to the United States Environmental Protection Agency. Thus in geographic areas where radon is present in heightened concentrations, radon is considered a significant indoor air contaminant. Residential exposure to radon gas has similar cancer risks as passive smoking.<unk>  is a more potent source of cancer when it is combined with other cancer-causing agents, such as radon gas exposure plus smoking tobacco. Medical In industrialized countries, Medical imaging contributes almost as much<unk>  dose to the public as natural background<unk> . Collective dose to Americans from medical imaging grew by a factor of six from 1990 to 2006, mostly due to growing use of 3D scans that impart much more dose per procedure than traditional radiographs. CT scans alone, which account for half the medical imaging dose to the public, are estimated to be responsible for 0.4% of current cancers in the United States, and this may increase to as high as 1.5-2% with 2007 rates of CT usage; however, this estimate is disputed. Other nuclear medicine techniques involve the injection of radioactive pharmaceuticals directly into the bloodstream, and radiotherapy treatments deliberately deliver lethal doses (on a cellular level) to tumors and surrounding tissues. It has been estimated that CT scans performed in the US in 2007 alone will result in 29,000 new cancer cases in future years. This estimate is criticized by the American College of Radiology (ACR), which maintains that the life expectancy of CT scanned patients is not that of the general population and that the model of calculating cancer is based on total-body<unk>  exposure and thus faulty. Occupational In accordance with ICRP recommendations, most regulators permit nuclear energy workers to receive up to 20 times more<unk>  dose than is permitted for the general public. Higher doses are usually permitted when responding to an emergency. The majority of workers are routinely kept well within regulatory limits, while a few essential technicians will routinely approach their maximum each year. Accidental overexposures beyond regulatory limits happen globally several times a year. Astronauts on long missions are at higher risk of cancer, see cancer and spaceflight. Some occupations are exposed to<unk>  without being classed as nuclear energy workers. Airline crews receive occupational exposures from cosmic<unk>  because of reduced atmospheric shielding at altitude. Mine workers receive occupational exposures to radon, especially in uranium mines. Anyone working in a granite building, such as the US Capitol, is likely to receive a dose from natural uranium in the granite. Accidental Chernobyl<unk>  map from 1996 Nuclear accidents can have dramatic consequences to their surroundings, but their global impact on cancer is less than that of natural and medical exposures. The most severe nuclear accident is probably the Chernobyl disaster. In addition to conventional fatalities and acute<unk>  syndrome fatalities, nine children died of thyroid cancer, and it is estimated that there may be up to 4,000 excess cancer deaths among the approximately 600,000 most highly exposed people. Of the 100 million curies (4 exabecquerels) of radioactive material, the short lived radioactive isotopes such as 131I Chernobyl released were initially the most dangerous. Due to their short half-lives of 5 and 8 days they have now decayed, leaving the more long-lived 137Cs (with a half-life of 30.07 years) and 90Sr (with a half-life of 28.78 years) as main dangers. In March 2011, an earthquake and tsunami caused damage that led to explosions and partial meltdowns at the Fukushima I Nuclear Power Plant in Japan. Significant release of radioactive material took place following hydrogen explosions at three reactors, as technicians tried to pump in seawater to keep the uranium fuel rods cool, and bled radioactive gas from the reactors in order to make room for the seawater. Concerns about the large-scale release of radioactivity resulted in 20 km exclusion zone being set up around the power plant and people within the 20–30 km zone being advised to stay indoors. On March 24, 2011, Japanese officials announced that "radioactive iodine-131 exceeding safety limits for infants had been detected at 18 water-purification plants in Tokyo and five other prefectures". Also in Japan was the Tokaimura nuclear accidents of 1997 and 1999. The 1997 accident was far less fatal than the 1999 accident. The 1999 nuclear accident was caused by two faulty technicians who, in their desire to speed up the process of converting uranium hexafluoride to enriched uranium dioxide, resulted in a critical mass that resulted in technicians Hisashi Ouchi being dosed with approximately 17 sieverts of<unk>  and Masato Shinohara to be does with 10 sieverts of<unk> , which resulted in their deaths. The two's supervisor, Yutaka Yokokawa, who was sitting in a desk far from the tank where the uranium hexafluoride was being poured into, was dosed with 3 sieverts and survived, but was charged with negligence in October 2000. In 2003, in autopsies performed on 6 children dead in the polluted area near Chernobyl where they also reported a higher incidence of pancreatic tumors, Bandazhevsky found a concentration of 137-Cs of 40-45 times higher than in their liver, thus demonstrating that pancreatic tissue is a strong accumulator of radioactive cesium. In 2020, Zrielykh reported a high and statistically significant incidence of pancreatic cancer in Ukraine for a period of 10 year, there have been cases of morbidity also in children in 2013 compared with 2003. Other serious<unk>  accidents include the Kyshtym disaster (estimated 49 to 55 cancer deaths), and the Windscale fire (an estimated 33 cancer deaths). The Transit 5BN-3 SNAP 9A accident. On April 21, 1964, the satellite containing plutonium burnt up in the atmosphere. Dr. John Gofman claimed it increased the rate of lung cancer worldwide. He said "Although it is impossible to estimate the number of lung cancers<unk>  by the accident, there is no question that the dispersal of so much Plutonium-238 would add to the number of lung cancer diagnosed over many subsequent decades."
Radiation-induced cancer
Chronic radiation syndrome
Radiation burn
Spaceflight radiation carcinogenesis
Radiation damage
Metastatic breast cancer
Senile osteoporosis
Bone metastasis