Background radiation impacts human longevity and cancer mortality: reconsidering the linear no-threshold paradigm

Abstract

BACKGROUNDThe current linear-no-threshold paradigm assumes that any exposure to ionizing radiation carries some risk, thus every effort should be made to maintain the exposures as low as possible. Here, we examined whether background radiation impacts human longevity and cancer mortality. METHODSOur data covered the entire US population of the 3139 US counties, encompassing over 320 million people. The data on background radiation levels, the average of 5-year age-adjusted cancer mortality rates, and life expectancy for both males and females in each county, was extracted using publicly available tools from official sources, and analyzed with JMP®™ software. RESULTSWe found for the first time that life expectancy, the most integrative index of population health, was approximately 2.5 years longer in people living in areas with a relatively high vs. low background radiation (≥ 180 mrem/year and ≤ 100 mrem/year, respectively; p < 0.005; 95% confidence interval [CI]). This radiation-induced lifespan extension could to a great extent be associated with the decrease in cancer mortality rate observed for several common cancers (lung, pancreas and colon cancers for both genders, and brain and bladder cancers for males only; p < 0.05; 95% CI). CONCLUSIONSExposure to a high background radiation displays clear beneficial health effects in humans.These hormetic effects provide strong evidence for re-considering the linear no-threshold paradigm, at least within the natural range of low-dose radiation.

Can Low-Level Ionizing Radiation Do Us Any Harm?

“…As indicated by the authors, such lifespan extension, established with high statistical significance (p > .005), could be associated with a decrease in cancer mortality from common malignancies, such as lung, pancreas and colon cancers for either sex, and brain and bladder cancers, for males only. 44 While the findings of this study could be influenced by the inherent assumptions in the EPA model applied in the calculation of background radiation doses, such results are in accord with and complement earlier observations from some of the world’s high background natural radiation areas in India, Brazil, China, and Iran where no, or a reverse, relationship was observed between exposure to elevated (up to 50 mSv/y.) natural background radiation and the rate of cancer mortality (reviewed by Ref.…”

“…36 Recently, a large-scale statistical study to evaluate the impact of natural background radiation on human longevity and cancer mortality has been published. 44 Individual values of dose equivalents (in mrems or mSv) from terrestrial and cosmic sources (including radon), averaged over a 5-year period (2011-2015) were evaluated for the entire population of all 3139 USA counties (involving over 320 million inhabitants) using the 'radiation dose calculator' 4 of the U.S. Environmental Protection Agency's (EPA). Data on cancer statistics over the same period were collected from the U.S. Cancer Statistics (USCS), the official federal statistics on cancer incidence and deaths, produced by the Centers for Disease Control and Prevention (CDC) and the National Cancer Institute (NCI).…”

Effects of Chronic Low-Dose Internal Radiation on Immune-Stimulatory Responses in Mice

“…In fact, exposure to low radiation doses may induce trivial stress factors to enhance protective antioxidant pathways that may contribute to longevity [ 5 , 18 ]. It has recently been determined that background radiation within the natural range of low-dose radiation increases the life expectancy by approximately 2.5 years [ 92 ]. In support of this, others have shown that LDR is involved in DNA double-stranded-break repair mechanisms [ 33 , 93 ], which can ultimately delay cell death mechanisms.…”

Impact of Environmental Radiation on the Incidence of Cancer and Birth Defects in Regions with High Natural Radioactivity

“…Although for practical purposes this might be irrelevant, the domain of such effect is at the normal radiation background, i.e., <5 mSv y −1 (the world average human exposure is 2.4 mSv y −1 ) [ 6 ]. At this dose rate level, it was claimed that exposure might be beneficial trough adaptive response and translated in a smaller morbidity of cancer and a longer lifetime [ 29 ]. However, in the HBRAs, the effective dose rates are in the range of 5–203 mSv y −1 , or 0.01–0.55 mSv d −1 [ 4 , 30 ].…”