Contribution of high natural background radiation area studies to an evolved system of radiological protection

At the start of the 21st century, the most important task of the radiation protection community is to demonstrate that workers and members of the public have been adequately protected by the current dose limits. There is no evidence that natural radiations are causing adverse health effects in those high background radiation areas exceeding 10 mSv/y in India, Brazil and Iran. Evidence increasingly shows that there are threshold effects in risk of radiation. An evolved system of radiological protection with a “practical” threshold concept will be an alternative to the current system based on the linear-no-threshold (LNT) hypothesis. “Practical” thresholds may be defined as dose levels below which induction of detectable radiogenic cancers or hereditary effects are not expected. If the current dose limits are assumed to be below “practical” thresholds, there may be no need of “justification” and “optimization” (ALARA) principles for occupational and public exposures in normal situations.