Causes Radiation-induced cancer

1 causes

1.1 background
1.2 medical
1.3 occupational
1.4 accidental

causes

according prevalent model, radiation exposure can increase risk of cancer. typical contributors such risk include natural background radiation, medical procedures, occupational exposures, nuclear accidents, , many others. major contributors discussed below.

background

radon responsible worldwide majority of mean public exposure ionizing radiation. single largest contributor individual s background radiation dose, , variable location location. radon gas natural sources can accumulate in buildings, in confined areas such attics, , basements. can found in spring waters , hot springs.

epidemiological evidence shows clear link between lung cancer , high concentrations of radon, 21,000 radon-induced u.s. lung cancer deaths per year—second cigarette smoking—according united states environmental protection agency. in geographic areas radon present in heightened concentrations, radon considered significant indoor air contaminant.

residential exposure radon gas has similar cancer risks passive smoking. radiation more potent source of cancer when combined other cancer-causing agents, such radon gas exposure plus smoking tobacco.

medical

in industrialized countries, medical imaging contributes radiation dose public natural background radiation. collective dose americans medical imaging grew factor of 6 1990 2006, due growing use of 3d scans impart more dose per procedure traditional radiographs. ct scans alone, account half medical imaging dose public, estimated responsible 0.4% of current cancers in united states, , may increase high 1.5-2% 2007 rates of ct usage; however, estimate disputed. other nuclear medicine techniques involve injection of radioactive pharmaceuticals directly bloodstream, , radiotherapy treatments deliberately deliver lethal doses (on cellular level) tumors , surrounding tissues.

it has been estimated ct scans performed in in 2007 alone result in 29,000 new cancer cases in future years. estimate criticized american college of radiology (acr), maintains life expectancy of ct scanned patients not of general population , model of calculating cancer based on total-body radiation exposure , faulty.

occupational

in accordance icrp recommendations, regulators permit nuclear energy workers receive 20 times more radiation dose permitted general public. higher doses permitted when responding emergency. majority of workers routinely kept within regulatory limits, while few essential technicians routinely approach maximum each year. accidental overexposures beyond regulatory limits happen globally several times year. astronauts on long missions @ higher risk of cancer, see cancer , spaceflight.

some occupations exposed radiation without being classed nuclear energy workers. airline crews receive occupational exposures cosmic radiation because of reduced atmospheric shielding @ altitude. mine workers receive occupational exposures radon, in uranium mines. working in granite building, such capitol, receive dose natural uranium in granite.

accidental

chernobyl radiation map 1996

nuclear accidents can have dramatic consequences surroundings, global impact on cancer less of natural , medical exposures.

the severe nuclear accident chernobyl disaster. in addition conventional fatalities , acute radiation syndrome fatalities, 9 children died of thyroid cancer, , estimated there may 4,000 excess cancer deaths among approximately 600,000 highly exposed people. of 100 million curies (4 exabecquerels) of radioactive material, short lived radioactive isotopes such chernobyl released dangerous. due short half-lives of 5 , 8 days have decayed, leaving more long-lived cs (with half-life of 30.07 years) , sr (with half-life of 28.78 years) main dangers.

in march 2011, earthquake , tsunami caused damage led explosions , partial meltdowns @ fukushima nuclear power plant in japan. significant release of radioactive material took place following hydrogen explosions @ 3 reactors, technicians tried pump in seawater keep uranium fuel rods cool, , bled radioactive gas reactors in order make room seawater. concerns large-scale release of radioactivity resulted in 20 km exclusion zone being set around power plant , people within 20–30 km zone being advised stay indoors. on march 24, 2011, japanese officials announced radioactive iodine-131 exceeding safety limits infants had been detected @ 18 water-purification plants in tokyo , 5 other prefectures .

other serious radiation accidents include kyshtym disaster (estimated 49 55 cancer deaths), , windscale fire (an estimated 33 cancer deaths).

the transit 5bn-3 snap 9a accident. on april 21, 1964, satellite containing plutonium burnt in atmosphere. dr. john gofman claimed increased rate of lung cancer worldwide. said although impossible estimate number of lung cancers induced accident, there no question dispersal of plutonium238 add number of lung cancer diagnosed on many subsequent decades.