Most people – and many scientists – believe that exposure to radiation is harmful. But it depends on what kind of radiation, asserts researchers at Ben-Gurion University (BGU) of the Negev in Beersheba, who have disproved a theory held by scientists for decades that exposure to a high background radiation causes harm to health.
Background radiation is an ionizing radiation that exists in the environment because of natural sources – for example, environmental terrestrial radiation and cosmic radiation from space. The researchers found in their study that such a phenomenon might actually lead to clear beneficial health effects in humans. This is the first large-scale study that examines these two major sources of background radiation covering the entire population of the US.
In their study, recently published in the journal Biogerontology under the title “Background radiation impacts human longevity and cancer
mortality: reconsidering the linear no-threshold paradigm,” Prof. Vadim Fraifeld and Prof. Marina Wolfson, along with Dr. Elroei David of the Nuclear Research Center Negev (NRCN) showed that life expectancy is about 2.5 years longer among people living in areas with a relatively high vs. low background radiation.
Since the 1960s, there has been a linear, no-threshold hypothesis guiding policy that any radiation level carries some risk. Hundreds of billions of dollars are spent around the world to reduce radiation levels as much as possible.
In the early decades of the 20th century and mainly during World War II, extensive radiobiological studies were performed to establish a basic radiation-protection policy and philosophy, they wrote. “Theconcept of tolerance dose was developed and widely accepted, based on two major postulates – a threshold dose e xists, which when exceeded may cause harmful effects, and even in case of certain exceeding the threshold, a complete recovery from radiation effects is still possible.”
In 1946, American geneticist Hermann J. Muller, who received the Nobel Prize in Physiology or Medicine for his work on the mutagenic effect of radiation, stated in his inauguration lecture that ‘‘there is no
escape from the conclusion that there is no threshold dose and that the individual mutations result from individual ‘hits,’ producing genetic effects in their immediate neighborhood.”
According to the BGU team, lower levels of several types of cancers were found when the radiation levels were on the higher end of the spectrum rather than on the lower end. Among both men and women, there was a significant decrease in lung, pancreatic, colon and rectal cancers. Among men, there were additional decreases in brain and bladder cancers. There was no decrease in cervix, breast or prostate cancers or leukemia.
“It is reasonable to suggest that a radiation threshold does exist, yet it is higher than the upper limit of the natural background radiation levels in the US (227 mrem/year),” the researchers wrote. “These findings provide clear indications for re-considering the linear no-threshold paradigm, at least within the natural range of low-dose radiation.”
“Decades of scientific theory are potentially being disproven by the remarkable researchers at BGU,” commented Doug Seserman, chief executive officer of American Associates of BGU. “These findings might even provide a sense of relief for those who reside in areas in the US with higher-than-average background radiation.”
Using the US Environmental Protection Agency’s radiation dose calculator, the researchers retrieved data about background radiation from all 3,129 US counties where encompassing over 320 million Americans live. The study’s data regarding cancer rates were retrieved from the United States Cancer Statistics. Life expectancy data was retrieved from the Institute for Health Metrics and Evaluation at the University of Washington Medical Center.