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Radiation and Radioactivity : Effects of Radiation : Low Levels of Radiation
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Humans are subject to background radiation all the time and the normal levels are well known. There is evidence that unless radiation exposure reaches about ten (10) times that normal level there is no harm to humans from radiation. Furthermore, there is now evidence that radiation at or near the normal background level is beneficial to, and even necessary for, life. People living at elevated-radiation levels are healthier than those who receive the U.S. sea-level background radiation dose.
There is good evidence that radiation doses below 100 millisievert (10 rem) cause no discernible harm to human beings.
There is no harm to humans at low levels.
Studies of equivalent populations in which one population recieves ten times as much background radiation as the other show no adverse effects from the higher radiation doses.
- in Chinese studies involving 70,000 people who have lived in the high thorium soil areas for six generations at up to four times the dose of others without high thorium backgrounds
- in Indian studies involving 12,918 plus people in and around Kerala where the background was four times low background areas
- in Guarapari, Brazil, where the background is six times sea-level background
- in the seven Colorado plateau states where backgrounds are up to four times U.S. sea-level background
Studies of excess cancers in British radiologists; radium dial painters, 75,000 atomic bomb survivors, Swedish hyperthyroid patients receiving radiotherapy, thousands of U.S. radiological workers, and nuclear weapons-test participants also show that there is a level below which no harm from radiation has been detected.
The threshold for harm is at least ten times the normal background radiation levels, and is probably two or three times higher than that. No harm as been found below these levels. In fact, low levels of radiation exposure produce health benefits.
Studies are confirming the necessity (and benefits) of low-level radiation environments: French studies have showed that cellular cultures (protozoa) could not grow normally when they were deprived of background radiation. Between 1978 and 1987, 108,000 nuclear submarine workers were matched against 700,000 other shipyard workers. There were 24% fewer cancers among those exposed to low-doses of radiation. The seven Colorado plateau states have 15% fewer cancers than the national average. Canadian studies showed a significant decrease in breast cancers for women with tuberculosis who had undergone fluoroscopy x-ray doses for lung diagnosis at up to 150 times the normal ranges of background dose. Good science requires that we use all data including data that show beneficial effects at low dose.
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